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I 


Uiemical  Ubraq 

TV 


/ 


HANDBOOK     ^*  ' 


OF 


CHEMICAL  TECHNOLOGY 


BY 


RUDOLF    WAGNER,    PH.D., 

PROFESSOR    OF    CHEMICAL    TECHNOLOGY    AT    THE    UNIVERSITY    OF    WURT2BURG. 


Translated  and  Edited  from  the  Eighth  German  Edition, 

with  extensive  additions, 

BY 

WILLIAM    CROOK  ES,    F.R.S. 


WITH    336    ILLUSTRATIONS. 


LONDON: 
J.  &  A.  CHURCHILL,  NEW  BURLINGTON  STREET. 

1872. 


/  uO  37 


LONDON: 

PRINTED  AT  THE  CHEMICAL  NEWS  OFFICE, 

BOY  COURT,   LUDOATK   HILL,   B.C. 


TRANSLATOR'S  PREFACE. 


The  several  Editions  of  Professor  Rudolf  Wagner's  "  Handbaoh  der  ChemiBchen 
Technologie"  have  succeeded  each  other  so  rapidly  that  no  apology  is  needed  in 
offering  a  translation  to  the  public. 

There  is  little  to  be  said  as  to  the  arrangement.  Improvements  in  Technological 
processes  that  have  appeared  since  the  publication  of  the  Eighth  Grerman  Edition 
have  been  added  during  translation.  Only  when  necessary  have  Foreign  weights 
and  measures  been  stated  in  English  equivalents ;  where  the  point  has  been  one  of 
comparison,  the  weights  have  been  left  unaltered.  The  Metrical  System  has  in 
some  cases  been  of  great  service  in  avoiding  the  repetition  of  tiresome  distinctions 
between  English  and  Prussian  grain  weights,  English  and  Bavarian  foot  measure, 
Ac.  The  formulsd  have  been  subjected  to  careful  revision,  and  are  molecular 
throughout  Indeed,  every  care  has  been  taken  to  merit  the  confidence  of  the 
manu£Ekcinrer  and  of  the  student. 

Under  the  head  of  Metallurgical  Chemistry,  the  latest  methods  of  preparing  Iron, 
Cobalt,  Nickel,  Copper,  Copper  Salts,  Lead  and  Tin  and  their  Salts,  Bismuth,  Zinc, 
Zinc  Salts,  Cadmium*  Antimony,  Arsenic,  Mercury,  Platinum,  Silver,  Gold,  Man- 
ganates.  Aluminum,  and  Magnesium,  are  described.  The  various  applications  of 
the  Voltaic  Current  to  Electro-Metallurgy  follow  under  this  division.  The  Prepara- 
tion of  Potash  and  Soda  Salts,  the  Manufacture  of  Sulphuric  Acid,  and  the  Recovery 
of  Sulphur  from  Soda- waste,  of  course  occupy  prominent  places  in  the  consideration 
of  chemical  manufiu^tores.  It  is  difficult  to  over-estimate  the  mercantile  value  of 
Mond's  process,  as  well  as  the  many  new  and  important  applications  of 
Bisulphide  of  Carbon.  The  Manufacture  of  Soap  will  be  found  to  include  much 
detail.  The  Technology  of  Glass,  Stoneware,  limes,  and  Mortars,  will  present 
much  of  interest  to  the  builder  and  engineer.  The  Technology  of  Vegetable  Fibres 
has  been  considered  to  include  the  preparation  of  Flax,  Hemp,  Cotton,  as  well 
as  Paper  Making ;  while  the  applications  of  Vegetable  Products  will  be  found 
to  include  Sugar-boiling,  Wine  and  Beer  Brewing,  the  Distillation  of  Spirits, 
the  Baking  of  Bread,  the  Preparation  of  Vinegar,  the  Preservation  of  Wood,  Ac. 


iv  TRANSLATOR'S  PREFACE, 

Dr.  Waomeb  gives  mnch  information  in  reference  to  the  production  of  Potash 
from  Sugar  residues.  The  use  of  Baryta  Salts  is  also  fully  described,  as  well  as  the 
Preparation  of  Sugar  from  Beet-roots.  Tanning,  the  Preservation  of  Meat,  Milk, 
Ac.,  the  Preparation  of  Phosphorus  and  Animal  Charcoal,  are  considered  as 
•belonging  to  the  Technology  of  Animal  Products.  The  Preparation  of  the  Materials 
for  Dyeing  has  necessarily  required  much  space ;  while  the  final  sections  of  the 

•  

book  have  been  devoted  to  the  Technology  of  Heating  and  Illumination. 

We  cannot  let  this  work  pass  out  of  our  hands  without  expressing  the  hope 
that,  at  no  distant  date.  Chairs  of  Technology  will  be  founded  in  all  our  Univer- 
sities, and  that  the  subject  will  be  included  in  the  curriculum  of  every  large  school. 

LoHDOH,  May,  1872. 


AUTHOB'S    PREFACE    TO    THE    EIGHTH    EDITION. 


The  Eighth  Edition  of  mj  **  Chemischen  Technologie'*  having  followed  the  Seyenth 
within  two  years,  but  few  words  of  introdaetion  are  necessary. 

The  arrangement  of  the  snbject-matter  in  former  Editions  has  essentially  been 
left  unaltered,  with  the  exceptions  that  I  have  brought  the  consideration  of  the 
materials  and  products  of  Chemical  Industry,  and  the  Technology  of  Glass  and  of 
Stoneware,  in  former  Editions  arranged  as  one  section,  under  distinct  headings. 
The  Tarious  processes  of  Chemical  Manufeuiture  have  had  much  detail  added.  The 
descriptions  of  the  Technological  Preparation  of  Alkali  and  Ammoniacal  Salts, 
as  well  as  of  the  Tar-colours,  have  in  consequence  of  the  extended  application 
of  these  products,  been  much  enlarged.  The  Chemical  formuha  are  molecular 
throughout 

Of  the  present  Edition  translations  will  be  made  into  EInglish  by  Mr.  William 
Crookes,  of  London,  and  into  French  by  Professor  L.  Gautier,  of  Melle,  Deux- 
Sevres.  A  translation  into  Dutch  of  part  of  the  Seventh  Edition  that  has  reoentiy 
appeared  has  been  made  without  my  permission  or  that  of  my  publishers. 

The  First  Edition  of  this  work,  written  whilst  I  held  the  position  of  Private  Tutor 

in  Chemistry  to  the  Philosophical  Faculty  to  the  High- School  of  Leipsic,  appeared 

in  September,  1850.    The  Second  in  May,  1853,  and  the  Third  Edition  in  July, 

1856,  were  presented  to  the  puUio  during  my  Professorship  of  Technological 

Chemistry  in  the  Imperial  Industrial  Schools  of  Nuremburg.    The  later  Editions 

appeared — 

The  Fourth  in  May,  1859, 

Fifth  in  May,  1862, 

Sixth  in  Octobw,  1865, 

„    Seventh  in  Bfarch,  1868, 

during  intervals  in  my  official  duties  in  Wurtzburg ;  and  in  these  I  have  been  much 
assisted  by  the  contributions  and  suggestions  of  many  friends,  to  whom  I  now  tender 
my  sincere  thanks. 

Db.  RUDOLF  WAGNER. 
Unitebsitt  of  Wubtzbubo, 
December  lotht  1870. 


»» 


I* 


CONTENTS. 


DIVISION  I. 

CHEMICAL   METALLURGY,   ALLOTS,   AND  PREPARATIONS   MADE   AND   OBTAINED   FROM 

METALS. 

Gkxxral  Obsebtations. — Meaning  of  the  term  Metallurgy,  4.  Ores,  4.  Dressing  of 
Ores,  5.  Preparation  of  Ores,  5.  Smelting  of  the  Ores,  6.  The  Mixing  of  the 
Smelt,  7.    Products  of  the  Smelting  Operation,  7.    Slags,  7. 

Ibox. — ^Its  Occurrence,  8. 

Pig  OB  Cbitdb  Ibon. — Extraction  of  Iron  from  its  Ores,  9.  Theory  of  the  Iron  Extraction 
Process,  10.  Blast-furnace  Process,  10.  Description  of  the  Blast-furnace,  11.  The 
Blowing  Engine  and  Blast,  12.  Course  of  the  Smelting  Process,  13.  Chemical  Pro- 
cess going  on  in  the  Interior  of  the  Blast-furnace,  13.  Temperature  in  the  Blast- 
furnace at  Different  Points,  15.  Blast-furnace  Gases,  15.  Application  of  these 
Oases  to  the  Manufacture  of  Sal-ammoniac,  16.  Crude  Iron,  Cast-iron,  16.  White 
Cast-iron,  16.  Grey  Cast-iron,  16.  Statistics  concerning  the  Production  of  Crude 
Iron,  18.  Iron  Foundry  Work — Be-smelting  Crude  Cast-iron,  18.  Shaft  or  Cupola 
Furnace,  z8.  Beverberatory  Furnace,  18.  Making  the  Moulds,  19.  Annealing, 
Tempering,  20.    Enamelling  of  <3a8t-iron,  20. 

MA1.T.F.ABIJE,  Bab,  OB  Wbouoht-Ibon. — ^Bar  Iron,  Refined  Iron,  20.  German  Iron-refining 
Process,  21.  Swedish  Befining  Process,  22.  The  Puddling  Process,  22.  Puddling 
Furnace,  22.  Heating  with  Gases,  24.  Befining  of  Iron  by  Mechanical  Means,  24. 
Boiler-plate  Boiling,  24.    Iron  Wire  Manufacture,  25.    Properties  of  Bar  Iron,  26. 

Btbxl. — Steel,  26.  Bough  Steel,  27.  Steel  Making  by  Imparting  Carbon  to  Wrought- 
iron,  28.  Befined  Steel,  Shear  Steel,  29.  Cast-steel,  29.  Steel  made  from  Malleable 
and  Crude  Cast-iron,  29.  Surface  Steel  Hardening,  29.  Properties  of  Steel,  29. 
Tempering,  30.  Steel  and  other  Metals,  30.  Damascene  or  Wootz  Steel,  30.  Sidero- 
graphy or  Steel  Engraving,  31.    Statistics  of  Steel  Production,  31. 

Ibom  Pb^pabatioms. — Coppera8--Green  Vitriol,  31.  Preparation  of  Green  Vitriol  as  a  By- 
product in  Alum  Works,  32.  Preparation  of  Green  Vitriol  in  Beds,  32.  Green 
Vitriol  from  the  Besidues  of  Pyrites  Distillation,  32.  Green  Vitriol  from  Metallic 
Iron  and  Sulphuric  Acid,  32.  F'rom  Spathic  Iron  Ore,  32.  Uses  of  Green  Vitriol,  32. 
Iron  Minium,  32.  Yellow  Prussiate  of  Potassa,  33.  Applications  of  the  Yellow 
Prussiate,  35.  Bed  Prussiate,  35.  Cyanide  of  Potassium,  35.  Berlin  Blue,  36.  Old 
Method  of  Preparing  Prussian  Blue,  36.  Becent  Methods  of  Preparing  Berlin  Blue, 
36.  Tnmbull's  Blue,  37.  Berlin  Blue  as  a  By-product  of  the  Manufactures  of  Coal- 
gas  and  Animal  Charcoal,  37.    Soluble  Berlin-Blue,  37. 

Cobalt. — Metallic  Cobalt,  37.  Cobalt  Colours,  371  Smalt,  38.  Cobalt  Speiss,  38.  Appli- 
cations of  Smalt,  38.  Cobalt  Ultramarine,  38.  Caeruleum,  39.  Binmann's  or  Cobalt 
Green,  39.  Chemically  pure  Protoxide  of  Cobalt,  39.  Nitrate  of  Protoxide  of 
Cobalt  and  Potassa,  39.    Cobalt  Bronze,  39. 

MiCBEL. — Nickel  and  its  Ores,  39.  Preparation  of  Nickel  from  its  Ores,  40.  The  Concen- 
tration-Smelting of  the  Nickel  Ores,  40.  Preparation  of  Metallic  Nickel,  or  of  Alloys 
of  Nickel  and  Copper,  41.    Properties  of  Nickel,  43. 

CopPBB. — Where  it  Occurs,  and  How,  43.  Ores  of  Copper,  43.  Mode  of  Treating  the 
Copper  Ores  for  the  Purpose  of  Extracting  the  Metal,  44.  The  Working-up  of  the 
Copper  Ores  in  the  Shaft  Furnace,  44.  Befining  the  Copper,  46.  Befining  on  the 
Hetfth,  46.  Befining  Copper  in  Large  Quantities,  46.  Liquation  Process,  47. 
English  Mode  of  Copper  Smelting,  47.  Calcining  or  Boasting  the  Ores,  48.  Smelting 
the  Ores,  48.  Boasting  or  Calcining  the  Coarse  Metal,  49.  Smelting  for  Wbite 
Metal,  49.  Blistered  or  Crude  Copper,  49.  Befining  the  Blistered  Metal,  ^9.  Mode 
of  Obtaining  Copper  from  Oxidised  Ores,  49.  Hydro-Metallurgical  Method  of  Prepa- 
ring Copper,  49.  Copper  obtained  by  Voltaic  Electricity,  50.  Properties  of  Copper, 
50.  Alloys  of  Copper,  51.  Bronze,  51.  Brass,  52.  German  or  Nickel  Silver,  53. 
Amalgam  of  Copper,  54. 


▼iii    •  CONTENTS. 

Pbepabitionb  or  Ooppeb. — ^Blne  Vitriol,  Snlphate  of  Copper,  54.  Preparation  of  Blue 
Vitriol,  54.  Doable  Vitriol,  55.  AppHoations  of  Blue  Vitriol,  56.  Copper  Pigments,  56. 
Brouswiok  Chreen,  56.  Bremen  Blue  or  Bremen  Green,  56.  Casaelmann's  Green,  57. 
Mineral  Green  and  Bine,  57.  Oil  Bine,  57.  Schweinfurt  Green  or  Emerald  Green, 
58.    Stannate  of  Oxide  of  Copper,  58.    Verdigris,  58.    Applications  of  Verdigris,  59. 

Lead. — Occnrrenoe  of  Lead,  59.  Method  of  Obtaining  Lead  hj  Precipitation,  59. 
Obtaining  Lead  by  Calcination,  60.  Baw  Lead,  61.  BoTivification  of  Litharge,  6z. 
Properties  of  Lead,  62.  Applications  of  Metallic  Lead,  62.  Mannfactnre  of  Shot,  63. 
Alloys  of  Lead,  62. 

Pbbpabationb  of  Lead.  —  Oxide  of  Lead,  63.  Massicot,  63.  Mininm,  Bed-lead,  63. 
Superoxide  of  Lead,  64.  Combinations  of  Oxide  of  Lead,  64.  Aoetaie  of  Lead,  64. 
Chromate  of  Lead,  64.  Neutral  or  Yellow  Chromate  of  Potassa,  64.  Applications  of 
the  Chromates  of  Potassa,  65.  Chrome  Yellow  or  Chromate  of  Lead,  6(5.  Chrome 
Bed,  66.  Chrome  Oxide  or  Chrome  Green,  67.  Chrome  Alum,  67.  TVliite-lead,  67. 
English  Method  of  Manufacturing  White-lead,  68.  French  Method  of  Preparing  White- 
lead,  69.  Apparatus  used  in  White-lead  Manufacture  at  Clichy,  69.  White-lead  from. 
Sulphate  of  Lead,  70.  Theory  of  Preparing  White-lead,  70.  White-lead  from  Chloride 
of  Lead,  70.  Basic  Chloride  of  Lead  as  a  Substitute  for  White-lead,  71.  Properties  of 
White-lead,  71.    Adulteration  of  White-lead,  72.    Applications  of  White-lead,  72. 

Tnv. — Occurrence  and  Mode  of  Obtaining  the  Metal,  73.  Properties  of  Tin,  74, 
Tinning,  75.  Tinning  of  Copper,  Brass,  and  Malleable  Iron,  75.  Tinned  Sheet-iron, 
75.    Moir^  Metallique,  75. 

Pbepabations  07  Tin. — Aurum  MusiTum,  Mosaic  Gold,  75.  Tinsalt,  75.  Nitrate  of 
IHn  or  Physic,  76.    Stannate  of  Soda,  76. 

BisxuTH. — Occurrence  and  Mode  of  Obtaining,  76.  Bismuth  Idquation-Fumaee,  76. 
Properties  of  Bismuth,  77.    Applications  of  Bismuth,  77. 

Zinc. — Occurrence  of  Zinc,  77.  Method  of  Extracting  Zinc,  77.  Distillation  of  Zinc  in 
Muffles,  78.  Distillation  in  Tubes,  79.  Distillation  of  Zinc  in  Crucibles,  79.  Mode 
of  Obtaining  Zinc  from  Sulphuret  of  Zinc,  the  Bl&ok-Jack  of  the  English  Mhiers,  79. 
Properties  of  Zinc,  79.    Application  of  Zinc,  80. 

Pbepabations  of  Zinc. — Zinc- white,  80.  White  Vitriol,  Sulphate  of  Zinc,  81.  Chromate 
of  Zinc,  81.    Chloride  of  Zinc,  81. 

CADMirif,  82. 

Antimony. — Antimony,  82.    Properties  of  Antimony,  84. 

Antikonial  Pbepabations^  in  Technical  Use. — Oxide  of  Antimony,  84.  Black  Snlphnret 
of  Antimony,  85.    Neapolitan  Yellow,  85.     Antimony  Cinnabar,  85. 

Absenio. — Arsenic,  85.  Arsenious  Acid,  85.  Arsenic  Acid,  86.  Sulphurets  of  Arsenic, 
86.    Bealgar,  87.    Orpiment,  87.    Busma,  87. 

QuiOKSiLyEB  OB  Mebctjbt. — Occurrence  and  Mode  of  Obtaining  Mercury,  87.  Method  of 
Extracting  Mercury  pursued'in  Idria,  87.  Spanish  Method  of  Extracting  Mercury, 
89.  Method  of  Decomposing  the  Ore  by  the  Aid  of  other  Substances,  90.  Proper- 
ties of  Mercury,  gi.    Applications  of  Mercury,  91. 

Pbepabations  of  Mebcubt. — Mercurial  Compounds,  91.  Chloride  of  Mercury,  91.  Cin- 
nabar, 91.    Fulminating  Mercury,  92.    Percussion-Caps,  93. 

Platinum. — Occurrence  of  Platinum,  93.  Platinum  Ores,  93.  Wollaston's  Method  of 
Extracting  Platinum  from  its  Ores,  94.  Method  of  Deville  and  Debray,  95.  Proper- 
ties of  Platinum,  95.  Black  Platinum,  Spongy  Platinum,  95.  Hammered  or  Cast 
Platinum,  and  its  Applications,  95.  ,  Platinum  Alloys,  96.    Elayl-platino-chloride,  96. 

SiLYEB. — Silver  and  its  Occurrence,  96.  Extraction  of  Silver  from  its  Ores,  96.  Smelting 
for  Silver  directly,  97.  Extraction  of  Silver  by  Amalgamation,  97.  European 
Amalgamation  Process,  97.  American  Amalgamation  Process,  98.  Augustin's 
Method  of  Silver  Extraction,  99.  ZiervogeVs  Method,  gg.  Sundry  Hydro-Metallur- 
gical  Methods  of  Extracting  Silver,  99.  Extraction  of  Silver  by  the  Dry  Process,  100. 
Mode  of  Preparing  the  Lead-containing  Silver,  100.  Befining  Process,  100.  Pattin- 
8on*s  Method,  loi.  Beduction  by  Means  of  Zinc,  102.  The  Ultimate  Befining  of 
Silver,  102.  Chemically  Pure  Silver,  102.  Properties  of  Silver,  102.  Alloys  of 
Silver,  103.  Silver  Alloy  for  Plate,  <^c.,  103.  Silver  Assay,  103.  Dry  Assay,  103. 
Wet  Assay,  104.  Hydrostatical  Assay,  104.  Silvering,  104.  Igneous  or  Fire 
Silvering,  104.  Silvering  in  the  Cold,  104.  Silvering  by  the  Wet  Way,  105. 
Nitrate  of  Silver,  105.    Marking  Ink,  105. 

Gold. — Occurrence  and  Mode  of  Extracting  Gold,  105.  Mode  of  Extracting  Gold,  105, 
Extraction  by  Means  of  Mercury,  106.  Smelting  for  Gold,  106.  Treating  with 
Alkali,  106.  Extraction  of  Gold  from  other  Metallic  Ores,  106.  Extraction  of  Gold 
from  Poor  Minerals,  106.  Befining  Gold,  to6.  By  Means  of  Sulphuret  of  Antimony, 
106.     By  the  Aid  of  Sulphur,  107.     Cementation  Process,  107.    Quartation,  107. 


CONTENTS.  ix 

Befimng  Gold  by  the  Aid  of  Snlphnrio  Add,  107.  ChemicftUy  Pare  Gt>ld,  108.  Pro- 
perties of  Gold,  Z08.  Alloys  of  Gold,  109.  Colour  of  Gold,  109.  Testing  the  Fine- 
ness of  Gold,  109.  Applications  of  Gold,  no.  Gilding,  no.  (Hiding  with  Gold- 
leaf,  no.  Gilding  by  the  Cold  Prooess,  no.  Gilding  by  the  Wet  Way,  no.  Rre- 
gilding,  no.    CassiuB's  Pnrple,  in.    Salts  of  Gold,  in. 

Manganxse  A2n>  rrs  Pbbpabationb. — ^Manganese,  in.  Testing  the  Quality  of  Manganese, 
ni. 

PKSiCAjiaANATX  ow  PoTABSA.— Permanganate  of  Potassa,  112. 

AiiUKiHinif. — Preparation  of  Aluminium,  113.  Properties  of  Aluminium,  113.  Applica- 
tions, 114. 

Maohssium. — Magnesium,  114. 

Electbo-Mbtallubot. — ^Application  of  Galvanism,  114.  Electrolytic  Law,  114.  Electro- 
typing,  115.  Reproduction  of  Copper-plate  Engravings,  115.  Deposition  of  Metals, 
115.  Electro-plating  with  Gold  and  Silver,  115.  Gold  Solution,  116.  Silver  Solu- 
tion, 116.  Copper  Solution,  116.  Zinc  and  Tin  Solution,  116.  Etching  by  Gal- 
vanism, 117.  MetaUochromy,  117.  Electro-stereotyping,  117.  Glyphography,  117. 
Galvanography,  117. 

DIVISION  II. 

CBUDE  MATEBIALS  AND   PBODUCTS  OF  CHEMICAL  U^DUSTBT. 

Cabbokatx  of  Potassa. — Sources  whence  Potassa  is  Perived,  118.  Potassa  Salts  from  the 
Stassfurt  Salt  Minerals,  118.  Mode  of  Obtaining  Potassa  from  Felspar,  122. 
Potassa  Salts  from  Sea-water,  122.  Potash  from  the  Ashes  of  Plants,  122.  Potash 
from  Molasses,  125.  Potassa  Salts  from  Sea-weeds,  129.  Potassa  Salts  from  Suint, 
132.    Caustic  Potassa,  133. 

Saltpktbe,  Nitbate  of  Potassa. — Saltpetre,  134.  Occurrence  of  Native  Saltpetre,  134. 
Mode  of  Obtaining  Saltpetre,  135.  Treatment  of  the  Bipe  Saltpetre  Earth,  135. 
Preparation  of  Baw  Lye,  136.  Breaking  up  the  Baw  Lye,  136.  Boiling  down  the 
Baw  Lye,  136.  Befining  the  Crude  Saltpetre,  137.  Preparation  of  Nitrate  of 
Potassa  from  Chili  Saltpetre,  138.  Testing  the  Saltpetre,  140.  Quantitative  Estima- 
tion of  the  Nitric  Acid  in  Saltpetre,  140.   Uses  of  Saltpetre,  141.  Nitrate  of  Soda,  141. 

NiTBic  AoiD. — Methods  of  Manufacturing  Nitric  Acid,  142.  Bleaching  Nitric  Acid,  143. 
Condensation  of  the  Nitric  Acid,  144.  Other  Methods  of  Nitric  Acid  Manufacture,  145. 
Density  of  Nitric  Acid,  146.    Fuming  Nitric  Acid,  147.    Uses  of  Nitric  Acid,  147. 

TsCHNOIiOaY  OF  THE  EXPLOSIVE  COMPOUNDS — ^GUNPOWDBB,  AKD  THE  ChEMIBTBY  OF  FiBEWOBXS, 

OB  Pyrotechny. — On  Gunpowder  in  General,  148.  Manufacture  of  Gunpowder,  148. 
Mechanical  Operations  of  Powder  Manufacture,  149.     Pulverising  the  Ingredients, 

149.  Mixing  the  Ingredients,  149.  Caking  or  Pressing  the  Powder,  150.  Granula- 
tion of  the  Cake  and  Sorting  the  Powder,  150.    Polishing  the  Granulated  Powder, 

150.  Prying  the  Powder,  151.  Sifting  the  Dust  from  the  Powder,  151.  Properties 
of  Gunpowder,  151.  Composition  of  Gunpowder,  152.  Products  of  the  Combustion 
of  Powder,  153.  New  Kinds  of  Blasting  Powder,  154.  Testing  the  Strength  of  Gun- 
powder, 154.  White  Gunpowder,  154.  Chemical  Principles  of  Pyrotechny,  155. 
The  more  commonly  used  Firework  Mixtures,  156.  Gunpowder,  156.  Saltpetre  and 
Sulphur  Mixture,  156.  Grey-coloured  Mixture,  156.  Chlorate  of  Potassa  Mixtures, 
156.  Friction  Mixtures,  Percussion  Powders,  156.  Mixture  for  Igniting  the  Cart- 
ridges of  Needle-guns,  15^.    Heat-producing  Mixtures,  157.    Coloured  Fires,  157. 

NiTBOGLYCBBiNE. — Nitroglycennc,  158.    NobePs  Dynamite,  160. 

GuE-corroN. — Gun-cotton,  160.  Properties  of  Gun-cotton,  161.  Gun-cotton  as  a  Substi- 
tute for  Gunpowder,  162.    Other  Uses  of  Gun-cotton,  162.    Collodion,  162. 

Common  Salt.— Occurrence,  163.  Method  of  Preparing  Common  Salt  from  Sea- water,  163. 
Method  of  Obtaining  Common  Salt  in  Salines,  164.  By  Freezing,  165.  By  Artificial 
Evaporation,  165.  Bock-salt,  165.  Mode  of  Working  Bock-salt,  167.  Mode  of 
Working  Salt  Springs,  167.  Preparation  of  Common  Salt  from  Brine,  168. 
Concentrating  the  Brine,  168.  Enriching  by  Gradation,  168.  Faggot  Gradation,  168. 
Boiling  down  ike  Brine,  168.  Properties  of  Conmion  Salt,  169.  Uses  of  Common 
Salt,  170. 

Mavufactube  OF  Soda — Native  Soda. — Occurrence  of  Native  Soda,  170. 

Soda  fbom  Plants  ob  Soda- Ash. — Soda  from  Soda  Plants  and  from  Beet-root,  171. 

Soda  Pbepabed  by  Chemical  Pbocessbs. — Soda  from  Chemical  Processes,'i72.  Leblanc's 
Process,  172.  Sulphate  or  Decomposing  Furnace,  172.  New  Decomposition  Fur- 
nace, 173.    Conversion  of  the  Sulphate  into  Crude  Soda,  174.    Soda  Furnace  with 


X  CONTENTS. 

Rotatory  Hearth,  175.  liziviation  of  the  Crude  Soda,  176.  Evaporation  of  the 
Ley,  180.  Theory  of  Leblanc's  Process,  183.  Utilisation  of  Soda  Waste,  184. 
Sohaffner'B  Sulphur  Begeneration  Process,  185.  Sundry  Methods  of  Preparing  Soda 
from  Sulphate  of  Soda,  187.  Direct  Conversion  of  Common  Salt  into  Soda,  t88. 
Soda  from  Cryolite,  188.  Soda  from  Nitrate  of  Soda,  189.  Caustic  Soda,  189.  New 
Methods  of  Caustic  Soda  Manufacture,  189.    Bicarbonate  of  Soda,  190. 

pBBPiiuLTioN  OF  loDiNE  AND  Bbomine.  —  Preparation  of  Iodine,  191.  Fteparation  from 
Kelp,  191.  Stanford  and  Moride^s  Method  of  Preparing  Iodine  from  Carbonised  Sea- 
weed, 192.  Preparation  of  Iodine  ffom  Chili  Saltpetre,  192.  Properties  and  Uses  of 
Iodine,  193.    Preparation  of  Bromine,  193. 

SuLPHUi. — Sulphur,  194.  Smelting  and  Befimng  Sulphur,  194.  Lamy's  Bcfining  Appa- 
ratus, 196.  Boll  Sulphur,  197.  Flowers  of  Sulphur,  197.  Preparation  of  Sulphur 
from  I^^tes,  197.  Preparation  of  Sulphur  by  Boasting  Copper  Pyrites,  198.  Sul- 
phur obtained  as  a  By-product  of  Gas  Manufacture,  198.  Sulphur  from  Soda- 
Waste,  198.  Production  of  Sulphur  by  the  Beaction  of  Sulphuretted  Hydrogen  upon 
Sulphurous  Acid,  198.  Sulphur  obtained  by  the  Beaction  of  Sulphurous  Acid  on 
Charcoal,  198.  By  Heating  of  Sulphuretted  Hydrogen,  198.  Properties  and  Uses  of 
Sulphur,  199. 

SiJLPHUBOus  AKD  Htposulphuboub  Acio. — Sulphurous  Acid,  199.  Sulphite  of  Lime,  201. 
Hyposulphite  of  Soda,  201. 

Makufactube  of  Sulphubic  Acm. — Sulphuric  Acid,  201.  Fuming  Sulphuric  Acid,  202. 
Ordinary  or  English  Sulphuric  Acid,  203.  Present  Manufacture  of  Sulphuric  Acid, 
203.  Use  of  Pyrites  for  the  Preparation  of  Sulphurous  Acid,  206.  Chamber  Add, 
206.  Concentration  of  Sulphuric  Acid,  206.  Concentration  in  Leaden  Pans,  207. 
Concentration  in  Glass  Betorts,  208.  Other  Methods  of  Sulphuric.  Acid  Manufac- 
ture, 208.    Properties  of  Sulphuric  Acid,  209. 

Sulphide  of  Cabbon. — Sulphide  of  Carbon,  210.    Carbon,  211.    Chloride  of  Sulphur,  211. 

Htpbochlobig  Acid  amd  Glaubbb's  Salt,  ob  Sulphate  of  Soda. — Hydrochloric  Acid,  211. 
Properties  of  Hydrochloric  Acid,  213.  Uses  of  Hydrochloric  Acid,  213.  Glauber's 
Salt,  2x3.    Uses  of  Sulphate  of  Soda,  214.    Bisulphate  of  Soda,  214. 

Blsachino-powdeb  and  Hypochlobites. — Chlorine,  214.  Preparation  of  Bleaching- 
powder,  214.  Preparation  of  Chlorine  without  Manganese,  214.  Apparatus  for  Pre- 
paring Chlorine,  216.  Condensing  Apparatus,  217.  Utilisation  of  the  Chlorine 
Production  Besidues,  218.  Dunlop's  Process,  218.  Gatty's  Process,  219.  Hofmann*s 
Process,  219.  Weldon's  Process,  219.  Other  Methods  of  Utilising  the  Besidues,  219. 
Theory  of  the  Formation  of  Bleaching-powder,  220.  Properties  of  Bleaching- 
powder,  220.  Chlorimetry,  221.  Gay-Lussac's  Chlorimetrio  Method,  221.  Perrot's 
Test,  221.  Dr.  Wagner's  Method,  222.  Chlorimetrical  Degrees,  222.  Alkaline 
Hypochlorites,  223.    Chlorate  of  Potassa,  223. 

AiiKALiMETBT. — Alkalimetry,  224.  Volumetric  Method,  224.  Mohr's  Method,  225. 
Gruneberg's  Method  of  Estimating  the  Value  of  Potash,  226. 

Ajcm GNU  AKD  Ammonuoal  Salts. — ^Ammouia,  226.  Preparation  of  Liquid  Ammonia,  227. 
Inorganic  Sources  of  Ammonia,  228.  Organic  Sources  of  Ammonia,  229.  Ammoma 
from  Gas-water,  230.  Mallet's  Apparatus,  230.  Bose's  Apparatus,  232.  Lunge's 
Apparatus,  232.  Ainmonia  from  Lant,  234.  Ammonia  from  Bones,  235.  Ammonia 
as  a  By-product  of  Beet-root  Sugar  Manufacture,  236.  Technically  Important 
Ammoniacal  Salts,  236.  Sulphate  of  Ammonia,  238.  Carbonate  of  Ammonia,  238. 
Nitrate  of  Ammonia,  238. 

Soap  Maeimo.— Soap,  239.  Baw  Materials  of  Soap  Boiling,  239.  Ley,  242.  Theory  of  Saponi- 
fication, 242.  Chief  Varieties  of  Soap,  243.  Olive  Oil  Soap,  244.  Oleic  Acid  Soap,  245. 
Besin  Tallow  Soaps,  245.  Fulling  Soaps,  245.  Soft  Soap,  246.  Various  other 
Soaps,  247.  Toilet  Soaps,  247.  Transparent  Soap,  248.  Uses  of  Soap,  248.  Soap 
Tests,  248.    Insoluble  Soap,  249. 

BoBio  oB  BoBAcic  AciD,  AMD  BoBAX. — Theory  of  the  Formation  of  the  Native  Boracic  Acid, 

250.  The  Production  of  Boracic  Acid,  250.    Properties  and  Uses  of  Boracic  Acid, 

251.  Borax,  252.  Borax  from  Boracic  Acid,  252.  Purifyiog  the  Borax,  254.  Octa- 
hedral Borax,  255.    Uses  of  Borax,  255.    Diamond  Boron  or  Adamantine,  256. 

Pboduction  of  Alum,  Sulphates  of  Alumina,  and  Aluminates. — Alum,  256.  Material  of 
Alum  Manufacture,  256.  Preparation  of  Alum  from  Alum-stone,  257.  Preparation 
of  Alum  from  Alum-shale  and  Alum-earths,  257.    Alum-shale,  257.    Alum-earths, 

257.  Preparation  of  Alum,  257.  Boasting  the  Alum-earths,  257.  LizLviation,  257. 
Evaporation  of  the  Ley,  257.    Alum  Flour,  258.    Washing  and  Be-crystaUisation, 

258.  Preparation  of  Alum  from  Clay,  258.  Preparation  of  Alum  from  Cryolite,  258. 
Preparation  of  Alum  from  Bauxite,  259.  Preparation  of  Alum  from  Blast-furnace 
Slag,  260.    Alum  from  Felspar,  260.    Properties  of  Alum,  260.    Ammonia-alum,  260. 


CONTENTS.  xi 

SodA-almn,  261.  Sulphate  of  Alnxnina,  261.  Alnminate  of  Soda,  262.  Uses  of 
Alum  and  of  Sidphate  of  Alumina,  263.  Acetate  of  Alumina,  263. 
UuTBAMABiMB. — ^Ultramarine,  26a.  Native  Ultramarine,  264.  AriiificifJ  Ultramarine,  264. 
Baw  Materials,  264.  MannfaotTire  of  Ultramarine,  265.  Preparation  of  Soda  Ultra- 
marime,  266.  Preparation  of  Silica  Ultramarine,  267.  Oonstitntion  of  Ultramarine, 
367.    Proporties  of  Ultramarine,  267. 


DIVISION  m. 

TBCHNOLOOY  OF  0LAS8,  OEBAMIC  WARE,  OYPSUM,  LIME,  AND  MORTAB. 

Glass  I^anufaotubb. — Definition  and  Qeneral  Properties  of  Glass,  268.    Glassifioation 
of  the  Yarions  Kinds  of  Qlass,  268.    Baw  Materials  used  in  Glass  Making,  269. 1 
Utilisation  of  Befose  Glass,  270.    Bleaching,  2^0.    The  Melting  Vessel,  270.    The 
Glass  Oren,  271.     Preparation  of   the  Material,  and  Melting,  274.     Drying  the 
Materials,  274.    Melting  the  Glass  Material,  275.    Clear-melting,  275.    Gold-stoking, 

275.  Defects  in  Glass,  276.    Various  Kinds  of  Glass«  276.    Plate  or  Window  Glass, 

276.  Tools,  277.  Crown  Glass,  277.  Sheet  Glass  or  Cylinder  Glass,  278.  Plate 
Glass,  2^9.  The  Melting  and  Clearing,  280.  Casting  and  Cooling,  281.  Polishing, 
281.  Silvering,  281.  SUvering  by  Precipitation,  281.  Platinising,  282.  Bottle 
Glass,  282.  ^ssed  and  Cast-glass,  283.  Water-glass,  283.  Stereochromy,  285. 
Crystal  Glass,  285.  Polishing,  286.  Optical  Glass,  286.  Strass,  288.  Coloured 
Glass  and  Glass  Staining,  289.  Glass  Painting,  289.  Enamel,  Bone  Glass,  Alabaster 
Glass,  290.  Cryolite  Glass,  291.  Ice  Glass,  291.  Hssmatinon  Astralite,  291.  Ayen- 
turin  Glass,  291.  Glass  Belief,  291.  Filigree,  or  Beticulated  Glass,  292.  Millifiore 
Work,  292.    Glass  Pearls,  292.    Blown  Pearls,  292.    Hyalography,  292. 

CsBAKic  OB  Eabthenwabb  Manxtfaotubb. — Clays  and  their  Application — ^Felspar,  293. 
Kaolin  or  Porcelain  Clay,  293.  The  Technically  Important  Quidities  of  the  Clays,  293. 
Colour,  294.  Plasticity,  294,  Kinds  of  Clay,  294.  Potter's  Clay,  295.  Walkerite, 
295.    Marl,  295.    Loam,  29*6.    Composition  of  Kaolin,  296.    Kinds  of  Clay  Ware,  296. 

L  Habd  Pobcblain. — Grindbig  and  Mixing  the  Material,  297.  Drying  the  Mass,  298. 
Kneading  the  Dried  Mass,  298.  The  Moulding,  298.  The  Potter's  Wheel,  298. 
Moulding  in  Plaster-of-Paris  Forms,  299.  Casting,  299.  Preparation  of  Porcelain 
Articles  without  Moulds,  299.  Glazing,  299.  Drying  the  Porcelain,  299.  Porcelain 
Glaze,  300.  Applying  the  Glaze,  300.  Immersion,  300.  Dusting,  300.  Watering, 
300.  By  Volatilisation  or  Smearing,  300.  Lustres  and  Flowering  Colours,  301.  The 
Capsule  or  Sagger,  301.  The  PorcelaLi  Oren,  301.  Emptying  the  Oren  and  Sorting 
the  Ware,  302,  Faulty  Ware,  302.  Porcelain  Painting,  302.  Ornamenting  the  Por- 
eelain,  303.    Bright  Gilding,  303.    Silvering  and  Platioicdng,  303.    Lithophanie,  303. 

n.  Tbbdbb  Pobcblain. — ^French  Fritte  Poroelidn,  304.  English  Fritte  Porcelain,  304. 
Parian  and  Carrara,  304. 

nL  Stokewabb* — Stoneware,  305.    Stoneware  Ovens,  306.    Lacquered  Ware,  307. 

IV.  Fayxnob  Wabe. — ^Fayence  Ware,  307.  Ornamenting  Fayence,  308.  Flowing  Colours, 
309.    Lustres,  309.    Etruscan  Vases,  309.    Clay  Pipes,  309.    Water  Coolers,  309. 

V.  Coiocoir  PoTTBBY.--Common  Pottery,  310.    Burning,  310. 

VL  Bbick  AMD  Tile  Making,  <fec. — ^Bricks,  310.  Terra  Cotta,  311.  Brick  Material,  311. 
Preparation  of  the  Clays,  311.  Moulding  the  Brick,  312.  Brick  Moulding  by 
Machinery,  312.  Bricks  from  Dried  Clay,  314.  The  Burning  of  the  Bricks,  315. 
Annular  Kilns,  317.  Field  Burning,  318.  Dutch  Clinkers,  318.  Boofing  and  Dutch 
Tiles,  318.  I^rain  and  Gutter  Tiles,  318.  Floating  Bricks,  318.  Fire-bricks,  319. 
Sanitai^  Ware,  321.    Crucibles,  321. 

Idxx  AND  LncE-BuBNnfo. — ^Lime,  322.  Properties,  322.  Lime-Burning,  322.  Occasional 
or  Periodic  Kilns,  323.  The  Continuous  Kilns,  324.  Kilns  for  Burning'  Lime  and 
Bricks,  325.    Properties  of  Lime,  325.    Slaking  Lime,  326.    Uses  of  Lime,  326. 

MoBTAB. — Mortar,  326. 

A.  GoMifON  OB  Aib-Sbttino  Mobtab. — Setting  of  the  Mortar,  327. 
'  B.  Htdbaulio  Mobtab. — ^Hydraulic  Mortar,  327.    Cement,  327.    Artificial  Cements,  328. 
Manufacture  of  Axtifioial  Cement  in  Germany,  330.     The  Setting  of  Hydraulic 
Mortars,  331. 

GiFSUM  AND  rrs  Pbepabation.— Occurrence,  333.  Nature  of  Gypsum,  333.  The  Burning 
of  Gypsum,  333.  Kilns  or  Burning  Ovens,  334.  Grinding  the  Gypsum,  335.  Uses 
of  Gypsum,  335.    Gypsum  Casts,  336.    Hardening  of  Gypsum,  336. 


xii  CONTENTS, 


DIVISION  IV. 

VEGETABLS  FIBRES  AND  THEIR  TECHNICAL  APPUCATION. 

The  Tschnoloot  of  Veostablb  Fibre — FLAX.~Flax,  338.  Hot  Water  Cleansixig,  339. 
Beating  or  Batting  the  Flax,  339.  Combing  the  Flax,  340.  Tow  or  Tangled  Fibre, 
340.    Flax  Spinning,  340.    Weaving  the  linen  Threads,  340.    Linen,  340. 

Heup. — ^Hemp,  340.    Its  Snbstitntes,  340. 

Cotton. — Cotton,  342.  Species  of  Cotton,  342.  Cotton  Spinning,  342.  Fin&  Spinning, 
343.  Tarn,  343.  Cotton  Fabrics,  343.  Sabstitntes  for  Cotton,  343.  Detecting 
Cotton  in  Linen  Fabrics,  343. 

Paper  Masino. — Histoiy  of  Paper,  345.  Materials  of  Paper  Mannfaotore,  346.  Sab- 
stitnte  for  Bags,  346.  Mineral  Additions  to  the  Bags,  346.  Manufacture  of  Paper  by 
Hand,  346.  Cntting  and  Cleaning  the  Bags,  347.  The  Separation  of  the  Bags  for 
Half-stofr  and  Whole-stuff,  347.  Stamp  Machine,  347.  The  Hollander,  347. 
Bleaching  the  Pulp,  349.    Anticblore,  349.    Blaeing,  350.     Sizing,  350. 

A.  Hand  Paper. — Straining  the  Paper  Sheets,  350.    Pressing  the  Paper,  351.    Drying  the 

Paper,  351.     Sizing  the  Paper,  351.     F^eparing  the  Paper,  351.     The  Different 
Kinds  of  Paper,  351. 

B.  Machine  Paper. — Manufacture  of  Machine  Paper,  352.    Paper  Cutting  Machine,  353. 

C.  Pasteboard  and  Other  Paper.  —  Making  Pasteboard,  353.     Coloured  Paper,  355. 

Parchment  Paper,  355. 

Starch. — Nature  of  Starch,  356.  Sources  of  Starch,  357.  Starch  from  Potatoes,  357. 
Drying  the  Potato  Starch,  358.  Preparation  of  Wheat  Starch,  358.  Constituents 
and  Uses  of  Commercial  Starch,  360.  Bice  Starch,  Chesnut  Starch,  Cassava  Starchy 
Arrow-root,  360.    Sago,  361.    Dextrine,  361. 

ScoAB  Manufacture. — History  of  Sugar,  362.    Nature  of  Sugar,  362. 

Cane  Sugar. — Sugar  from  the  Sugar-cane,  364.  Components  of  the  Sugar-cane,  364. 
Preparing  the  Baw  Sugar  from  the  Sugar-cane,  365.  Varieties  of  Sugar,  366. 
Molasses,  366.    Befining  the  Sugar,  366.    Production  of  Baw  Sugar,  367. 

Bbbt-root  Sugar. — Its  Nature,  367.  Species  of  Beet,  367.  Chemical  Constituents  of 
the  Beet,  368.  Saccharimetiy,  369.  Mechanical  Method,  369.  Chemical  Method, 
369.  Ferment  Test,  370.  Physical  Method,  370.  Preparation  of  Sugar  from  the 
Beet,  370.  The  Besidue,  372.  Components  of  the  Juice,  373.  Other  Methods  of 
De-Liming  the  Juice,  374.  Purifying  with  Baryta,  374.  The  Filter,  375.  Dumont's 
Filter,  375,  Evaporation  Pans,  375.  Vacuum  Pans,  377.  Evaporating  the  Juice, 
380.  Draining  the  Crystals,  381.  The  Centrifugal  Drier,  381.  Bemoving  the  Sugar 
from  the  Form,  381.    Beet  Molasses,  382.    Sugar-candy,  382. 

Grape  Sugar. — Grape  Sugar,  383.  Preparation  of  Grape  Sugar,  384.  Composition  of 
Starcli  Sugar,  386.    Uses  of  Grape  Sugar,  386. 

Fermentation. — Fermentation,  386.  Vinous  Fermentation,  387.  Yeast,  387.  Condi- 
tiouR  of  Alcoholic  or  Vinous  Fermentation,  389. 

Wine-Makdco. — ^Wine,  390.  The  Vine  and  its  Cultivation,  390.  Vintage,  390.  The  Pres- 
sing of  the  Grapes,  391.  The  Centrifugal  Machine,  391.  Chemical  Constituents  of 
the  Must,  391.  The  Sugar  of  the  Grape,  392.  The  Fermentation  of  the  Grape 
Juice,  393.  Drawing  Off  and  Casking  the  Wine,  393.  Constituents  of  Wine,  393. 
Maladies  of  Wines,  396.  Ageing  and  Conservation  of  Wines,  397.  Clearing  or 
Fining  the  Wine,  399.  The  Besidue  or  Waste  of  Wine  Making,  399.  Effervescing 
Wines,  399.    The  Improving  of  the  Wine  Must,  401. 

Beer-Brewing. — Beer,  403.  Materials  of  Beer-Brewing,  403.  Hops,  404.  QuaHty  of  the 
Hops,  404.  Substitutes  for  Hops,  405.  Water,  405.  The  Ferment,  405.  The  Pro- 
cess of  Beer  Brewing,  405.  The  Malting,  405.  The  Bruising  of  the  Malt,  408. 
Mashing,  408.  Decoction  Method,  409.  Thick  Mash  Boiling,  409.  Augsburg 
Method,  410.  Infusion  Method,  410.  Extractives  of  the  Wort,  411.  Boiling  the 
Wort,  411.  Adding  the  Hops,  412.  Cooling  the  Wort,  413.  The  Fermentation,  414. 
Sedimentary  Fermentation,  415.  After-Fermentation  in  the  Casks,  416.  Surface-  * 
Fermentation,  417.  Steam-Brewing,  418.  Constituents  of  Beer,  418.  Beer-Testing, 
420.  Balling's  Saccharometrical  Beer  Test,  420.  Fuchs's  Beer  Test,  422.  By-pro- 
ducts of  the  Brewing  Process,  423. 

Preparation  or  Distillation  of  Spirits. — Alcohol,  424.  Alcohol  and  its  Technically 
Important  Properties,  424.    Baw  Materials  of  Spirit  Manufacture,  425. 

A.  Preparation  of  a  Vinous  Mash. — Vinous  Mash  from  Cereals,  426.  The  Bruising,  426. 
The  Mixing  with  Water,  426.    The  Cooling  of  the  Mash,  426.    The  Fermentation  of 


CONTENTS.  xUi 

the  Bfash,  427.  Mash  from  Potatoes,  427.  Mash  with  Snlphnrio  Acid,  428.  The 
Fermentation  of  the  Potato  Mash,  429.  Mash  from  Boots,  429.  Spirits  from  the 
Bj-prodncts  of  Sugar  Mannfactnre,  430.     Spirits  from  Wine  and  Marc,  430. 

B.  DxBTiiiLATioN  OF  THK  YiNODS  Mash. — ^Distillation  of  the  Mash,  431.  The  Distilling 
Apparatus,  432.  Improved  Distilling  Apparatus,  432.  Dom's  Apparatus,  433.  Pis- 
torius*8  Apparatus,  435.  Gall's  Apparatus,  433.  Schwarz's  Apparatus,  436. 
Siemens*8  Apparatus,  440.  Continuous  Distilling  Apparatus,  440.  Tangier'sl^Appa- 
ratuB,  443.  Bemoying  the  Fusel  Oils — ^Defuseling,  445.  Yield  of  Alcohol,  446. 
Aleoholometry,  447.  Areometer,  447.  Relation  of  Brandy  Distilling  to  Agriculture, 
448.  The  Besidue  or  Wash,  448.  Dry  Teast,  449.  So-called  Artificial  Yeast,  450. 
Vienna  Yeast,  450.    Duty  on  Spirits,  451. 

Bbsad  Bakino. — ^Modes  of  Bread  Making,  451.  The  Details  of  Bread  Baking,  451.  The 
Mixing  of  the  Dough  and  the  Kneading,  452.  Kneading,  452.  Kneading  Machines, 
453.  The  Oven,  45 a.  Substitutes  for  the  Ferments,  456.  Yield  of  Bread,  459. 
Composition  of  Bread,  459.    Impurities  and  Adulteration  of  Bread,  460. 

Thb  Manutactubb  of  Yineoab. — Yinegar  and  its  Origin,  460. 

A.  Pbsfabation  of  Yinzgab  fbom  Alcoholic  Fluids. — ^Yinegar  from  Alcohol,  461.  Pheno- 

mena of  Yinegar  Formation,  462.  The  Older  Method  of  Yinegar  Making,  462. 
Quick  Yinegar  Making,  463.  Yinegar  from  Sugar-beet,  466.  Yinegar  with  the  help 
of  Myooderma  Aceti,  466.  Yinegar  with  the  help  of  Platinum  Black,  467.  Testing 
Vinegar,  467.    Aoetometry,  468. 

B.  Pbipabation  of  Yineoab  fbom  Wood  Yinboab. — Wood  Yinegar,  469.    Purifying  Wood 

Vinegar,  471.    Wood  Spirit,  472. 

Thb  Pbesebyation  of  Wood. — On  the  Durability  of  Wood  in  General,  472.  Preservation 
of  Wood  in  Particular,  474.  Drying  Wood,  474.  Elimination  of  tne  Constituents  of 
the  Sap,  474.  Air  Drains,  475.  Chemical  Alteration  of  the  Constituents  of  the  Sap, 
475.    liOneralising  Wood,  4^6.    Boucherie's  Method  of  Impregnation,  477. 

ToBAOOO. — Tobacco,  477.  Chemical  Composition  of  the  Tobacco  Leaf,  478.  Manufacture 
of  Tobacco,  478.    Smoking  Tobacco,  479.    Snuff,  480. 

TicHNOLoaT  OF  EssBMTiAL  OiLS  AND  Bbsims. — ^Essential  Oils  and  Besins,  480.  Prepara- 
tion of  Essential  Oils,  481.  Preparation  of  Essential  Oils  by  Pressure,  481.  Extrac- 
tion of  Essential  OUb  by  Means  of  Fatty  Oils,  481.  Properties  and  Uses  of 
Essential  Oils,  481.  Perfum^,  481.  Chemical  Perfumes,  482.  Preparation  of 
Cordials,  482.  Besins,  483.  Use  of  Besins  as  Sealing-wax,  483.  Asphalte,  484. 
Caoutchouc,  484.  Solyents  of  Caoutchouc,  485.  Properties  and  Use  of  India-rubber, 
486.  Vulcanised  Caoutchouc,  486.  Production  and  Consumption  of  Caoutchouc,  486. 
Gutta-percha,  486.  Solyents  of  Gutta-percha,  487.  Uses  of  Gutta-percha,  487. 
Mixture  of  Gutta-percha  and  Caoutchouc,  ^,  Yamishes,  488.  Oil  Varnishes, 
4S8.  Gold  Size,  489.  Printing  Ink,  489.  Oil  Yamishes,  A89.  Spirit  Varnish,  489. 
Coloured .  Spirit  Yamishes,  490.  Turpentine  Oil  Yamishes,  490.  Polishing  the 
Dried  Varnish,  490.    Pettenkofer's  Process  for  Bestoring  Pictures,  490. 

Cbmbmtb,  Lutbs,  and  Puttt. — Cements,  491.  Lime  Cements,  491.  Oil  Cements,  491. 
Beam  Cements,  492.    Iron  Cement,  493.    Paste,  493. 

DIVISION  V. 

ANIMAL   SUBSTANCES   AND  THEIB  INDUSTRIAL   APPLICATION. 

WooLLBN  Industbt. — Origin  and  Properties  of  Wool,  494.  Chemical  Composition  of  Wool, 
495.  Properties  of  Wool,  497.  Colour  and  Gloss,  497.  Preparation  of  Wool,  497. 
Wool  Spinning,  498.  I.  Washing,  498.  n.  Dyeing,  498.  m.  WiUowing  or  Devilling, 
498.  Oiling  or  Greasing,  498.  Y.  The  Carding,  498.  YI.  Boving,^499.  Artificial 
Wool,  499.  Weaving  the  Cloth,  499.  Washing  and  Milling  the  Bough  Cloth,  499, 
Teasling  and  Shearing  the  Cloth,  499.  Dressing  the  Cloth,  499.  Other  doth 
Fabrics,  500.    Worsted  Wool,  500. 

81UL — Silk,  501.  Seridoulture— Varieties  of  Silkworms,  501.  Manipulation  of  the  Silk, 
503.  The  Throwing  of  Silk,  504.  Conditioning  or  Testing  of  Silk,  504.  Scouring  or 
Boiling  the  Gum  out  of  Silk,  504.  Weaving  of  Silk,  505.  Means  of  Distinguishing 
Bilk  from  Wool  and  from  Vegetable  Fibre,  506. 

TAHimo. — Tanning,  508.    Anatomy  of  Animal  Skin,  508. 

L  Bid-  ob  Babk-Tannino. — Tanning  Materials,  509.  Oak  Bark,  509.  Sumac,  510. 
Dividivi,  511.  Nut  Galls,  511.  Valonia  Nuts,  511.  Chinese  Galls,  511.  Cutch,  512. 
Kino,  512.  Estimation  of  the  Value  of  the  Tanning  Materials,  512.  The  Skins,  513. 
The  Bertral  Operationfl,  513.     Cleansing  the  Hides,  514.     Cleansing  the  Flesh 


iiv  CONTENTS. 

Side,  514.  CleanBing  the  Hair  Sidet  514.  Stripping  ofif  the  Hair,  515.  Swelling  the 
Hides,  515.  The  Tanning,  516.  Tanning  in  the  Bark,  516.  Tanning  in  Liquor,  517. 
Qnick  Tanning,  517.  Dressing  or  Onrrying  the  Leather,  518.  Sole  Leather,  518. 
Upper  Leather,  518.  The  Paring,  518.  The  Scraping  or  Smoothing,  518.  Oraining 
the  Leather, '519.  Polishing  with  Prunice-stone,  519.  Baising  the  Grain  slightly 
with  Pommels  of  Cork,  519.  Smoothing  with  Tawer's  Softening  Lron,  519.  Bollizig» 
519.  Finishing  Off,  519.  Greasing,  519.  Tufts,  Russia  Leather,  520.  Morocco 
Leather,  520.  Dressing  Morocco  Leather,  521.  Cordwain,  Gordoyan  Leather,  521^ 
Lacquered  Leather,  521. 

II.  Tawing.— Tawing,  Preparation  of  White  Leather,  522.  Common  Tawing,  522.  Hun- 
garian TawiQg  Process,  524.    Glove  Leather,  524.    Enapp's  Leather,  525. 

HI.  Samiam  OB  Oil-Tawino  Process. — Samian  Tawing  Process,  525.  Parchment,  527. 
Shagreen,  527. 

Glue  Boilino. — ^General  Obserrations,  528.  Leather  Glue,  529.  Treating  with  Lime, 
529.  Boiling  the  Materials,  530.  Fractioned  BoiUng,  530.  Moulding,  531.  Diyixig 
the  Glue,  531.  Glue  from  Bones,  532.  Liquid  Glue,  533.  Test  for  the  Quality 
of  Glue,  533.  Isinglass,  535.  Substitutes  for  Glue,  and  New  Preparations  obtained 
from  Glue,  536. 

MANtJFACTUBE  OF  PHOSPHORUS. — General  Properties,  537.  Preparation  of  Phosphorus, 
537.  Burning  of  the  Bones  to  Ash,  538.  Decomposition  of  the  Bone-ash  by 
Sulphuric  Acid,  538.  Distillation  of  Phosphorus,  539.  Befining  and  Purifying  the 
Phosphorus,  540.  Moulding  the  Befined  Phosphorus,  541.  Other  Proposed  MeUiods 
of  Preparing  Phosphorus,  543.  Fleck's  Process,  543.  Gentele,  Gerland,  Minaiy, 
and  Soudry's  Methods  of  Preparing  Phosphorus,  544.  Properties  of  Phosphorus,  544. 
Amorphous  or  Bed  Phosphorus,  545.    Properties  of  Amorphous  Phosphorus,  546. 

Requisites  fob  Producino  Fibe. — Generalities  and  History,  546.  Manufacture  of  Lucifer 
Matches,  548.  The  Preparation  of  the  Wood  Splints,  548.  The  Preparation  of  the 
Combustible  Composition,  549.  Dipping  and  Drying  the  Splints,  550.  Anti- 
Phosphor  Matches,  552.    Wax  or  Vesta  Matches,  553. 

Animal  Charcoal. — Animal  Charcoal,  553.  Preparation  of  Bone-black,  553.  Properties 
of  Bone-black,  554.  Testing  Bone-black,  554.  Beyivifioation  (re-burning)  of  Char- 
coal, 555.    Substitutes  for  Bone-black,  555. 

Milk. — Milk,  556.  Whey,  557.  Lactose,  Sugar  of  Milk,  557.  Means  to  Preyent  Milk 
becoming  Sour,  557.  Testing  Milk,  557.  Uses  of  Milk,  558.  Butter,  558.  Chemical 
Nature  of  Butter,  559.    Cheese,  559. 

Meat.— ^jreneralities,  562.  Constituents  of  Meat,  562.  The  Cooking  of  Meat,  563.  The 
Boiling  of  Meat,  564.  Preservation  of  Meat,  564.  Preservation  of  Meat  by  with- 
drawsJ  of  Water,  565.    Salting  Meat,  565.    Smoking  or  Curing  Meat,  566. 


DIVISION  VI. 

DYEING   AND   aKLICO   PRINTING. 

On  Dyeing  and  Printing  in  Genebal. — ^Dyeing  and  Printing  in  General,  568.    Dyes,  568. 

Lake  Pigments,  569.    Colouring  Materials,  569.    The  Coal-Tar  Colours :  Coal- Tar, 

569.    Benzol,  570.    Nitro-benzol,  572.    Aniline,  573. 
I.  Aniline  Coloubs. — ^Aniline  Colours,  575.    Aniline  Bed,  575.    Aniline  Violet,  577. 

Aniline  Blue,  578.    Aniline  Green,  578.    Aniline  Yellow,  579.    Aniline  Orange,  579. 

Aniline  Black,  579.    Aniline  Brown,  579. 
n.  Cabbolio  Acid  Coloubs. — Carbolic  Acid  Dyes,  580.    Picric  Acid,  580.    Pheniciexme, 

581.    Grenate  Brown,  581.    Coralline,  581.    Azuline,  581.    Pigment  Directly  |rom 

Nitro-benzol,  581. 
ni.  Naphthaline  Pigments. — Naphthaline,  581.    Martins  Yellow,  582.    Magdala  Bed, 

583.    Naphthaline  Blue  and  Naphthaline  Violet,  583. 
rV.  Anthracen  Pigments. — Anthracen  Pigments,  584. 
V.  Pigments  fbom  Cinchonine. — Cinchoine  Pigments,  585. 
fisD  Pigments  Oocdbbino  in  Plants  and  Animals. — ^Bed  Dye  Materials — ^Madder,  586. 

Madder  Lake,  587.    Flowers  of  Madder,  587.    Azale,  587.    Garanoine,  587.    Ganm- 

ceux,  587.    Colorine,  588.    Brazil  or  Camwood,  588.    Sandalwood,  588.    Safflower,  ' 

589.    Cochenille  or  Cochineal,  589.    Lac  Dye,  590.     Orchil  and  Persio,  590.    Less 

Important  Bed  Dyes,  591. 
Blue  Dte  Materials.^:— Indigo,  591.    Properties  of  Indigo,  592.    Testing  Indigo,  592. 

Berzelius's  Indigo  Test  by  Beduction,  593.    Penny's  Test,  593.    Indigo  Blue»  594. 

Logwood  or  Gampeachy,  594.    Litmus,  594. 


CONTENTS.  XV 

Tei<low  Dyes. — Yellow-wood,  Fustic,  595.  Youug  Fustic,  French  Fustet,  595.  Annatto 
or  Amotto,  595.  Yellow  Berries  or  Simply  Berries,  596.  Turmeric,  596.  Weld, 
596.    Quercitron  Bark,  596.    Brown,  Green,  and  Black  Dyes,  596. 

Blbachino. — Bleaching,  597.    Bleaching  of  Silk,  599. 

Dtbino  of  Spun  Y'arn  and  Woven  Textile  Fabrics. — Dyeing,  599.  Mordants,  601. 
Dyeing  Woollen  Fabrics,  601.  Dyeing  Wool  Blue,  601.  Indigo  Blue,  602.  Blue 
Vats,  602.  Saxony  Blue,  603.  Beoovering  Indigo  from  Bags,  604.  Berlin  or  Prussian 
Blue  on  Wool,  604.  Dyeing  Blue  with  Logwood  and  a  Copper  Salt,  604.  Dyeing 
Yellow,  604.  Dyeing  Wool  Red,  605.  Green  Dyes,  605.  Mixed  Shades,  605.  Black 
Dyes,  605.  Wlute  Cloth,  606.  Silk  Dyeing,  606.  CaHco  Dyeing,  608.  Turkey  Bed, 
608.    Dyeing  Linen,  609. 

The  Printing  of  Woven  Fabrics.— Printing  of  Woven  Fabrics,  609.  Mordants,  609. 
Thickenings,  610.  Resists,  or  Reserves,  610.  Discharges,  611.  Acid  Discharges, 
611.  Oxidising  Agents  as  Discharges,  611.  Reducing  Agents  as  Discharges,  611. 
CiJico  Printing,  612.  Topical  or  Surface  Colours,  613.  Discharge  Style,  614. 
Aniline  Printing,  614.  Hotpressing,  Finishing,  and  Dressing,  616.  Printing  Linen 
Goods,  616.  Printing  Woollen  Goods,  616.  Printing  Silk  Goods,  616.  Mandarin 
Printing,  6x6.    Bandanas,  616. 


DIVISION  vn. 

THE   MATERIALS   AND   APPARATUS   FOB   PRODUCING    ARTIFICIAL   LIGHT. 

Artificial  Illumination  in  General,  617.    Flame,  618. 

I.  Artificial  Light  from  Candles. — Lignt  from  Candles,  620.  Manufacture  of  Stearine 
Candles,  621.  Preparation  of  Fatty  Acids  by  Means  of  Lime,  621.  Saponification 
with  Less  Lime,  623.  Saponification  by  Means  of  Sulphuric  Acid,  624.  Sapo- 
nification with  Water  and  High  Pressure,  626.  Manufacture  of  Fatty  Adds  by 
Means  of  Superheated  Steam  and  Subsequent  Distillation,  627.  Candle  Making, 
627.  Moulding  the  Candles,  628.  Tallow  Candles,  629.  ParafiSn  Candles,  630. 
Candles  from  Fatty  Adds,  631.  Wax  Candles,  631.  Other  Kinds  of  Wax,  632. 
The  Making  of  Wax  Candles,  633.  Sperm  or  Spermaceti  Candles,  634.  Glyce- 
rine, 634. 

n.  Illumination  bt  Means  of  Lamps. — Dlumination  with  Fluid  Substances,  636.  Puri- 
fying or  Refining  the  Oils,  636.  Lamps,  636.  Various  Kinds  of  Lamps,  639. 
Suction  Lamps,  639.  The  Lamp  with  Constant  Oil  Level,  640.  Pressure  Lamps, 
641.  Mechanical  Lamps,  642.  Clockwork  Lamp,  642.  Moderateur  or  Moderator 
Lamp,  642.    Petroleum  Oil  and  Paraffin  Oil  Lamps,  644. 

IIL  Gab.— -General  Introduction  and  Historical  Notes,  645.  Raw  Materials  of  Gas 
Lighting,  646.  Coal-Gas,  646.  Products  of  the  Distillation,  647.  Manufacture  of 
Goal-Gas,  648.  Retorts,  648.  Mouth-piece  and  Lid  of  Retorts,  649.  Retort  Fur- 
naces, 650.  Charging  the  Retorts  and  Distillation,  650.  The  Hydraulic  Main,  650. 
Cooling  or  Condensing  Apparatus,  652.  The  Scrubber,  653.  Exhauster,  654. 
Purifying  Gas,  654.  Gas  Holders,  656.  Distribution  of  Gas,  660.  Hydraulic  Valve, 
661.  ^essure  Regulator,  661.  Testing  Illuminating  Gas,  661.  Methods  of 
Testing  Illuminating  Gas,  662.  Gas  Meters,  664.  Burners,  665.  Gas  Lamps,  665. 
By-Products  of  Coal-Gas  Manufacture,  665.  Composition  of  Coal-Gas,  668.  Wood 
Gas,  668.  Method  of  Wood  GLas  Manufacture,  669.  Wood  Gas  Burners,  670.  Peat 
Gas,  670.  Water  Gas,  671.  Gillard's  Gas,  Platinum  Gas,  672.  Carburetted  Water 
Gas,  672.  Whitens  Hydrocarbon  Process,  673.  Leprince's  Water  Gas,  Isoard's 
Gbs,  674.  Baldamus  and  Grune's  Gas,  6^4.  Carburetted  Gas,  674.  Air  Gas,  67A. 
Oil  Gas,  Itesin  Gas,  674.  Gas  from  Suint,  675.  Gas  from  Petroleum  Oil,  or  Ou 
from  Bituminous  Shales,  675.  Petroleum  Gas,  676.  Resin  Gas,  678.  Lime-Light, 
678.  Tessie  du  Motay's  Method  of  Illumination,  679.  Magnesium  Light,  679. 
Chatham  Light,  680.     Electric  Light,  680. 

Pa&affim  and  Solar  or  Petroleum  Oils. — Paraffin  Oils,  683.  Manufacture  of  Paraffin, 
683.  Preparation  of  Paraffin  from  Petroleum,  684.  Paraffin  from  Ozokerite  and 
Neftgil,  684.  Paraffin  from  Bitumen,  685.  Preparation  of  Paraffin  by  D17  Distilla- 
tion, 685.  Preparation  of  the  Tar,  685.  Condensation  of  the  Vapours  of  the  Tar, 
686.  Properties  of  Tar,  687.  Mode  of  Operating  with  the  Tar,  688.  Distillation 
of  the  Tar,  688.  Treatment  of  the  Products  of  Distillation,  689.  Rectification  of 
the  Crude  Oils,  689.  Refining  of  the  Crude  Paraffin,  690.  Hubner's  Method  of 
Preparing  Paraffin,  690.  Yield  of  Paraffin,  691.  Brown-coal,  691.  Properties  of 
Paraffin,  692.    Paraffin  Oil,  693.    Preparation  of  Mineral  Oil,  694. 


XTi  CONTENTS. 

PsTBOLSUM.— Petroleum  Oil  and  its  Ooourrences,  695.  Origin  and  Formation  of  Petro- 
leum, 695.  Befining  of  Crude  Petroleum,  696.  (Constitution  of  Petroleum,  696. 
Technology  of  Petroleum,  697. 

DIVISION   VIII. 

FUEL   AND   HEATING  APPABATUS. 

A.  FuKL. — ^Fuel,  698.  Combustibiiity,  698.  Inflammability,  698.  Calorific  Effect,  698. 
Determination  of  Combustive  Power,  699.  Karmarsch's  Evaporation  Method,  699. 
Berthier's  Beduction  Method,  700.  Elementary  Analysis,  700.  Stromeyer's  Test, 
701.    Pyrometrical  Calorific  Test,  701.    Mechanical  Equivalent  of  Heat,  702. 

Wood. — ^Wood,  702.  Constituents  of  Wood,  703.  Heating  Value  of  Wood,  704.  Wood 
Charcoal,  704.  Carbonisation  of  Wood,  705.  Carbonisation  in  Heaps,  705.  Con- 
struction of  the  Heap,  705.  Charcoal  Burning,  706.  Carbonisation  in  Beds,  706. 
Carbonisation  in  Ovens  or  Kilns,  706.  Carbonisation  of  Wood  in  Ovens,  ^08.  Pro- 
perties of  Charcoal,  710/  Composition  of  Wood  Charcoal,  71  x. .  Combustibility  and 
Heating  Effect,  711.  Charbon-Bouz ;  Terrified  Charcoal,  711.  Boasted  Wood; 
Bois-Boux,  712. 

PsAT — Peat,  712.  Drying  Peat,  713.  Heating  Effect  of  Peat,  715.  New  Method  of 
Utilising  reat,  715. 

Cabbonised  Peat. — Carbonised  Peat,  715.  • 

Bbown-coal. — Brown-coal,  716.    Brown-coal  as  Fuel,  717. 

Pit  Coal,  ob  Coal. — Coal,  717.  Accessory  Constituents  of  Coal,  718.  Classification  of 
Coals,'^7i8.  Anthracite,  719.  Caking  Coal,  719.  Calorific  Effect,  721.  Evaporative 
Effect  of  Coals,  721.    Boghead  Coal,  722. 

PxTBOLBuu  AS  FuEL. — Pctrolcum  as  Fuel,  722. 

Coke. — Coke,  723.  Coking  in  Heaps,  724.  Coking  in  Ovens,  724.  Properties  of  Coke, 
729.    Composition  of  Coke  and  its  Value  as  Fuel,  729. 

Abtificial  Fuel. — Artificial  Fuel,  729.    Peras,  729.    Briquettes,  730. 

Gaseous  Fuel. — Gaseous  Fuel,  730.    Gas  for  Heating  Purposes,  731. 

Heating  Appabatus. — Warming,  731. 

Heating  Dwelling  Houses. — Heating'  Dwelling  Houses,  732.  Direct  Heating,  732. 
Chimney  Heating,  733.  Stove  Heating,  733.  Iron  Stoves,  734.  Fire-clay  Stoves, 
734.  Compound  Stoves,  735.  Air  Heating,  737.  Calorifiers,  738.  Flue  Heating, 
739.  Hot  Water  Heating,  739.  Heating  with  Steam,  740.  Combination  of  Steam 
and  Hot  Water  Heating,  740.  Gas  Heating,  740.  Heating  without  Ordinary  Fnel, 
740. 

BomsB  Heating  and  Consumption  of  Smoke. — Boiler  Heating,  740.  Smoke  Consuming 
Apparatus,  741.  Step  Grate,  742.  Etage,  or  Stage  Grate,  743.  Movable  Grate, 
743.  Chain  Grates,  743.  Botating  Grate,  744.  Improved  Fuel  Supply,  744.  Pnlt 
Fires,  744.  Vogl's-  Grate,  744.  Boquillon's  Grate,  744.  Apparatus  of  Cutler  and 
George,  ^44.  Apparatus  with  Unequal  Distribution,  744.  Consumption  of  Smoke 
by  the  Aid  of  Collateral  Air  Currents,  745.    Gall's  Fireplace,  745.    Besom^,  745. 


/• 


INTRODUCTION. 


Man's  labour,  considered  from  an  economical  point  of  view,  is  of  a  threefold  kind,  being 
either  productive,  improving,  or  converting.  We  distinguish  likewise  between  the 
productions  obtained  from  the  soil  taken  in  its  widest  sense,  and  between  commerce 
and  manufacturing  industry. 

The  department  of  labour,  the  object  of  which  is  to  prepare  and  render  fit  for  use 
the  raw  materials  yielded  by  nature,  is  that  which,  in  a  more  restricted  sense,  is 
called  manu&u^turing  industry,  and  the  description  and  elucidation  of  the  methods 
by  which  this  object  is  attained  is  called  technology,  from  rkx*^  and  \oyos.  Taken  in 
a  general  sense,  this  word  would  apply  to  all  trades,  arts,  and  manufactures  what- 
soever; exclusive,  however,  of  actual  artist's  work — ^notwithstanding  the  latter 
exceeds  the  industries  in  respect  of  the  money -value  of  its  productions — and  exclusive, 
also,  of  such  trades  as  tailoring,  dress-  and  shoe-making,  in  which  only  certain  commo- 
dities from  materials  that  have  been  produced  by  manufacturing  industry  are 
worked  up. 

Mining  and  quarrying  operations,  as  well  as  commerce,  do  not  belong  to  technology, 
because  the  former  deal  with  the  getting  to  hand  of  naturally  existing  materials,  and 
the  object  of  the  latter  is  either  the  carrying  and  distributing  of  the  products  from 
various  parts  of  the  world  to  the  wholesale  consumers,  or  the  products  of  different 
kinds  of  one  and  the  same  country  to  the  population  thereof.  The  position  of  some 
industries  is  somewhat  difficult  to  define  in  this  sense,  for  while  metallurgy  and  the 
knowledge  of  tools  and  machinery  are  undoubtedly  an  integral  portion  of  technology, 
taken  in  its  widest  sense,  the  construction  of  railways,  roads,  and  bridges,  as  well 
as  shipbuilding,  architecture,  artillery  science,  &c.,  do  not  come  within  the  province  of 
technology,  but  belong  either  to  engineering  science  or  are  specialities  to  be  separately 
taught  and  described. 

Technology  is  not  a  self-contained  science  which  possesses  its  own  peculiar  doctrine 
and  foundation;  it  simply  borrows  the  principles  and  experience  obtained  by 
mechanical  and  natural  sciences,  always  taking  into  consideration  the  best  mode  of 
applying  these  principles  to  the  preparation  of  raw  materials  to  become  objects  suitable 
for  use.  Technology  is  accordingly  practical  natural  science,  having  for  its  object 
the  reduction  of  manufacturing  industry  to  the  natural  principles  upon  which  it  is 
based,  and  teaching  the  most  advantageous  methods  and  processes  by  which  the  raw 
materials  are  prepared  for  use.  Raw  products,  which  are  either  in  the  condition 
nature  yields  them,  or  which  have  already  been  in  the  hands  of  the  manufacturer,  are 

B 


2  CHEMICAL   TECHNOLOGY. 

changed  by  the  labour  of  men,  either  in  their  outward  form  only,  or  in  their 
composition,  and  upon  this  distinction  is  based  tlie  di\dsion  of  technology 
mechanical  and  chemical ;  the  former  division  embraces  such  industries  as  h.a.ve 
for  their  object  the  changing,  altering,  and  modifying  the  form  and  shape  of  tlie 
material,  its  inner  composition  remaining  unaltered ;  as  instances  we  quote  the  jo 
and  carpenter  working  in  wood,  the  making  of  iron  rails,  sheath  metal,  and  v^rire, 
casting  of  iron,  zinc,  and  alloys  of  copper  into  various  objects,  the  spinnixig 
weaving  of  various  fibres,  flax,  cotton,  jute,  to  become  materials  of  greater  value  ; 
the  manufacturing  of  paper  from  rags,  of  horn  into  combs,  and  bristles  into  bxxLsIi 
belong  to  this  section. 

Chemical  technology,  however,  deals  with  the  operations  by  wliich  a  raw  nL&tejri 
is  not  only  changed  in  its  form,  but  espeeiMy  as  regards  its  nature :  such,  for  instctzice* 
is  the  case  with  the  extraction  of  metals  from  their  ores ;  the  conversion  of  lead  into 
white-lead  and  sugar  of  lead  (acetate  of  lead) ;  the  conversion  of  sulphate  of  baryt 
into  chloride  of  barium  and  baryta  white  (permanent  or  Chinese  white) ;  the  converHiont 
of  cryolite  into  sulphate  of  alumina,  alum,  and  soda ;  the  conversion  of  rock  salt  into 
sulphate  and  carbonate  of  soda ;  the  conversion  of  camallite  and  kainite  into  chloride 
and  bromide  of  potassium,  sulphate  and  carbonate  of  potassa;  the  conversion,  of 
copper  into  verdigris  and  sulphate  of  copper;  the  manufacture  of  paraffine  and 
paraffine  or  crystal  oils  from  peat.  Boghead  coal,  and  hgnite ;  the  preparation  of  kelp 
and  iodine  from  seaweeds ;  the  manufacture  of  stearine  candles  (stearic  acid  prox>erly  I 
and  soap  from  oils  and  fats ;  the  preparation  of  sugar  and  alcohol  from  starch ;  the 
conversion  of  alcohol  into  vinegar ;  the  brewing  of  beer  from  barley  and  hops  ;  the 
manufacture  of  pig-iron  into  malleable  iron  (puddling  process),  and  the  conversion  of 
malleable  iron  into  steel ;  the  production  of  gas,  coke,  and  tar  from  coals ;  the  extrac- 
tion from  the  tar  of  such  substances  as  benzol,  carbolic  acid,  aniline,  anthracen,  « 
asphalte,  naphthaline ;  the  preparation  of  tar  colours,  as  rosaniline,  aniline  blue,  1 
Manchester  yellow,  Magdala  red,  alizarine,  iodine  green,  picric  acid,  &c.  In  very 
many  cases,  however,  the  preparation  which  the  raw  materials  have  to  undergo 
before  fit  for  use  is  simultaneously,  or  at  least  consecutively,  a  mechanical 
as  well  as  a  chemical  process;  for  instance,  in  the  manufacture  of  glass,  sand, 
potash,  Glauber  salt  (sulphate  of  soda)^  carbonate  of  soda,  and  hmestone,  are  first 
fused  together  to  form  glass  (a  true  salt,  a  silicate),  and  the  soft  mass  is  next  wrought 
in  various  ways  to  form  window-glass,  tumblers,  bottles,  &c.  Another  instance  is  the 
manufacture  of  beet-root  sugar,  in  the  extraction  of  which  the  sugar  itself  is,  it  is 
true,  not  altered  or  changed  in  any  way  (tliis  being  as  much  as  possible  avoided),  hot 
the  process  of  extraction  is  a  combination  of  mechanical  and  chemical  operations,  the 
^*  latter  bearing  chiefly  upon  the  purification  of  the  sugar  so  as  to  free  it  from  adhering 
foreign  substances.  The  same  observation  appUes  to  the  manufacture  of  starch,  to 
tanning  operations,  also  to  the  various  processes  of  dyeing  and  calico  printing. 

The  ceramic  arts  (that  is  to  say,  the  manufacture  of  earthenware,  pottery,  china,  &c.) 
are  generally  included  in  chemical  technology,  although,  in  the  production  of  the 
objects  alluded  to,  the  mechanical  operations  and  fine  art  processes  predominate. 
PVrotechny  (that  is  to  say,  the  consideration  of  fuel  and  of  its  most  useful  and  advan- 
tageous application  to  the  production  of  heat,  and  the  best  mode  of  constructing 
furnaces,  ovens,  chimneys,  &c.)  is  one  of  the  most  important  parts  of  chemical 
technology. 

From    the  foregoing  the  reader  wiH  readily  perceive  ijiat  it  is  scarcely  possible 


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INTRODUCTION.  3 

to  draw  a  sharp  line  of  demarcation  between  the  two  divisions  of  technology 
(ibechanical  and  chemical)  alluded  to.  We  therefore  define  chemical  technology 
best  by  designating  it  as  that  branch  of  industrial  science  which  treats  of  the  processes 
and  methods  by  which  the  nature  of  raw  materials  is  usually  altered. 

In  mechanical  technology,  machinery  of  various  description,  acting  as  the  motive 
agent  or  for  the  exertion  of  great  power,  for  the  transference  of  movement  or  for  the 
nd  i  regulation  thereof,  and,  lastiy,  as  an  actual  implement,  always  plays  a  very  prominent 
^  ;  part,  whilst  in  chemical  technology  its  position  is  altogether  subordinate ;  the  great 
^  '  aim  of  imfirovement  being  chiefly  directed  towards: — i.  Economisation  of  raw 
material,  and,  if  by  any  possible  means,  its  regeneration.  2.  Economy  of  fuel. 
3.  Economy  of  time  by  improved  and  shortened  methods  of  the  various  operations. 
The  ideal  of  a  chemical  manufactory  is  that  there  should  be  no  real  waste  products 
^M  '•  all*  but  only  chief  or  main,  and  by-products.  The  better,  therefore,  the  waste 
^  products  are  applied  to  good  and  advantageous  use,  the  more  nearly  Uie  manufactory 
^      mill  approach  tiie  ideal,  and  the  larger  \vill  be  the  profit.   , 


n  2 


DIVISION    I. 

CHEMICAL   METALLURGY,  ALLOYS,   AND   PREPARATIONS   MADE   AND   OBTAINED   FROM   METALS. 


General  Observations. 

'***°5ettu^^  Metallurgy,  in  a  more  restricted  sense,  embraces  the  doctrine  of 
the  various  processes  and  operatiouB,  some  of  which  are  purely  mechanical,  others 
again  pui'ely  chemical,  by  means  of  which  metals  and  some  preparations  thereof  are 
obtained  on  a  large  scale.  We  treat  in  the  following  pages  almost  exclusively  of 
the  chemical  operations  and  processes  by  the  aid  of  which  ores  are  converted  into 
metal  or  into  some  other  product,  and  we  shall  therefore  investigate  the  changes 
which  the  ore  undergoes  when  submitted  to  different  processes  and  operations  re- 
sulting in  the  extraction  of  the  metal.  The  number  of  the  metals  which  belong  to 
this  category  is  not  veiy  large;  the  chief  are  iron,  cobalt,  nickel,  copper,  lead, 
chromium,  tin,  bismuth,  zinc,  antimony,  arsenic,  mercury,  platinum,  silver,  gold. 
Excepting  chromium  and  cobalt,*  other  metals  are  brought  into  the  metallic  state  by 
means  of  smelting  furnaces;  but  preparations  of  nickel,  antimony,  and  arsenic  are 
also  obtained  metallurgically.  Magnesium  and  aluminium  are  as  yet  only  prepared 
in  chemical  manufactories.  Metallurgy,  as  a  part  of  technology,  treats  chiefly  of 
the  physical  and  chemical  principles  upon  which  the  extraction  of  metals  from  their 
ores  is  based;  and  includes,  therefore,  the  description  of  the  operations  as  based  upon 
these  principles.  Only  very  few  metals  are  found  in  the  native,  that  is,  metallic 
state ;  most  of  them  occur  as  chemical  compounds  in  the  mineral  kingdom,  and  these 

Qroi.  are  termed  ores ;  they  are  partly  chemical  combinations  of  Hie  metal  with 
metalloids,  and  partly  consist  of  rock  or  gaugue.  Moreover,  the  term  ore  applies  only 
in  an  industrial  sense  to  those  minerals  which  are  worth  the  miner's  working. 
Metals  are  found  chiefly  in  combiuation  with  oxygen  and  sulphur.  Metals  occur  in 
the  ores  in  the  following  conditions: — i.  In  the  native  state,  embedded  in  quartz, 
granite,  gneiss,  and  other  minerals, — ^gold,  silver,  platinum,  mercury,  copper,  and 
bismuth.  2.  Combined  with  sulphur,  as,  for  instance,  antimony,  arsenic,  and  lead ; 
these  combinations  being — (a)  single  ores,  as,  for  instance,  cinnabar  (sulphuret  of 
mercury),  HgS;  galena  (sulphuret  of  lead),  PbS;  speisscobalt  (a  compound  of  cobalt 
metal  'and  arsenic),  CoAs;  {b)  double  ores,  as,  for  instance,  sulphuret  of  iron  and 
copper  (peacock  ore),  Fe2S3,3CuaS;  iron  and  copper  pyrites,  FcaSj.CuaS;  red  silver 

*  Since  1862  M.  Fleitmann  has  prepared  chromium  and  cobalt  on  the  large  scale  by  a 
metallurgical  process. 


PREPARATION    OF    ORES,  5 

ore,  SbaS3,3AgS.  3.  Gombmed  with  oxygen,  ores  occur  as — (a)  basic  oxides,  as,  for 
instance,  hsematite  iron  ore,  Fe203 ;  tinstone,  SnOa ;  red  copper  ore,  GuaO ;  (b)  as 
hjdrated  oxides,  as,  for  instance,  bog  iron  ore,  Fe203,3H20  ;  (0)  as  oxysalts,  as  for 
instance,  malachite,  CuCOj+CuHaO.  4.  Combined  with  sulphur  and  oxygen, 
as  for  instance,  red  antimony  ore,  2SbaS3+Sb203.  5.  Combined  with  haloids,  as,  for 
instance,  the  so-called  horn  silver  ore,  AgCl.  6.  In  combination  with  haloids  and 
oxygen,  as,  for  instance,  horn  lead  ore,  PbC03+PbCl3. 

'^'^oSf  "*  Since  the  ores  are  not  found  in  a  state  anything  approacliing  to  purity, 
but  are  mixed  in  the  first  place  with  what  is  technically  termed  gangue — ^rock,  stone,  or 
earth  of  any  kind ;  and,  moreover,  since  very  frequently  the  ores  of  different  metals 
occur  mixed  together,  they  require,  on  being  brought  out  of  the  mine,  to  be  broken 
up  and  to  be  separated  by  mechanical  means  from  the  gangue  and  from  other  im- 
purities. These  operations  as  a  rule  are  carried  out  on,  or  near,  the  spot  where  the  ores 
are  raised,  and  are  designated  by  the  name  of  dressing ;  the  mechanical  preparation 
of  the  ore  is  partly  executed  by  hand,  women  and  children  being  frequently  engaged 
in  picking  out  worthless  stuff  from  among  the  minerals  brought  to  bank ;  this  sorting, 
accompanied  commonly  by  the  breaking  up  of  the  ore  into  small  lumps,  an  operation 
executed  by  men  vdih  suitable  hammers,  is  usually  so  carried  on  as  to  separate  the 
ore  into  three  kinds.  The  ore  thus  selected  is  placed  in  separate  heaps,  which  may  be 
classed  as  follows: — a  heap  containing  rich  ore  of  sufficiently  good  quality  to  be  fit  to 
be  directly  smelted ;  another  heap  contains  ore  which,  previous  to  its  being  fit  for 
the  smelter,  has  to  be  further  prepared,  that  is,  purified  from  mechanically  adhering 
impurities ;  while  the  third  heap  is  devoted  to  such  poor  ore  as  would  not  pay  the 
expense  of  the  extraction  of  the  comparatively  small  quantity  of  metal  it  contains. 
The  mechanical  operations  alluded  to  are  frequently  effected  by  the  aid  of  machinery, 
stamp  and  dressing  mills,  while  very  often  water  is  used  in  completing  tlie 
operations,  its  use  being  chiefly  to  remove  the  clay  and  earthy  matter,  sand,  and 
pulverised  rock  from  the  specifically  heavier  mineral.  '    The  dressing  of  the  ores 

^"*owJ.**" ^  having  been  finished,  they  are  fit  for  the  smelting  operations,  but  in 
majiy  instances  these  cannot  be  proceeded  Tvith  until  the  ores  have  undergone  a 
preparation,  consisting  in  some  cases  of  an  exposure  to  air — ^weathering ;  in  otliers, 
again,  in  a  heating  of  the  ores,  without  access  of  air,  designated  calcination,  or  a 
heating  with  access  of  air,  termed  roasting. 

The  object  of  the  expo^nire  to  air  is  in  some  instances  to  effect  the  weathering  and 
subsequent  loosening  and  separation  (mechanically)  of  such  minerals  as  slate,  clay, 
and  marly  materials,  which  frequently  adhere  to  certain  kinds  of  iron  and  zinc  ores ; 
in  other  instances,  again,  the  object  of  the  exposure  of  metallic  ores  to  air  is  tlie 
oxidation  of  iron  pyrites,  which  is  washed  out  by  rain  as  sulphate  of  protoxide  of 
iron.  The  object  of  the  calcination  of  ores  is  partly  to  drive  off  water, 
carbonic  acid,  and  bituminous  materials ;  partly,  also,  to  render  the  ores 
softer,  and  thus  better  fitted  for  the  metallurgical  processes  by  which  the  re- 
duction to  the  metallic  state  is  effected.  The  roasting  of  ores  is  carried  on  with  the 
same  object,  but  since  the  temperature  is  far  higher,  although  not  carried  to 
the  fusion  of  the  ores,  a  more  energetic  chemical  action  takes  place,  and  is  in  some 
cases  promoted  by  the  addition  of  common  salt;  moreover,  the  great  object  of  the 
roasting  of  ores  is  to  effect  an  oxidation  of  tlie  same,  accompanied  in  some,  if  not  in  all, 
cases  bv  the  volatilisation  of  various  substances.  As  uistances  of  the  action  of  Uiis 
process,  we  quote  wliat  occihtj  when  magnetic  iron  ore,  (Fea03,FeO),  is  roasted; 


6  CHEMICAL  TECHNOLOGY, 

tlie  protoxide  in  this  case  is  gradually  converted  into  peroxide.    When  oxidation  is 
accompanied  by  volatilisation  three  different  things  may  happen. 

1.  A  volatilisation  of  certain  Bubstances  attended  by  oxidation.  The  ores  which  are 
chiefly  submitted  to  this  process  are  snch  as  are  combinations  of  sulphur,  arsenic,  and 
antimony,  either  jointly  or  siQgly,  in  which  cases  sulphurous  and  arsenious  acids  and 
oxide  of  antimony  are  volatilised,  with  the  result  that  either  pure  metal  is  obtained,  as  is 
the  case  with  cinnabar,  which  yields  mercury,  or  the  formation  of  metallie  oxides  and 
sulphates.  The  volatilised  substances  may  be  collected  and  utilised,  as,  for  instanee, 
the  arsenious  acid,  and  the  sulphurous  acid  for  the  production  of  sulphuric  acid,  Ac. 

2.  Volatilisation  of  certain  substances  by  reduction  is  a  less  frequently  occurrizig 
operation,  chiefly  carried  on  with  some  sulphates  and  arseniates  of  metallic  oxides  by 
heating  the  same  with  coal  or  charcoal,  the  result  being  the  volatilisation  of  sulphur  in 
the  form  of  sulphurous  acid  and  of  arsenic  per  se. 

3.  Volatilisation  by  conversion  into  chlorides  of  metal.  When  an  ore  is  roasted  with  the 
addition  of  conmion  salt  and  free  access  of  air,  some  partly  volatile  chlorides  may  be 
formed,  as,  for  instance,  in  the  extraction  of  silver  from  its  ores  by  the  European 
amalgamation  process  and  M.  Augustin's  method. 

smoiuiigof  theOxM.  As  soon  as  the  ores  are  sufficiently  prepared  by  the  methods  just 
described,  they  are  submitted  to  an  operation  having  for  its  object  the  conversion  of 
the  ore  into  metal,  or  into  some  other  combination  thereof;  the  process,  which  is  a 
true  chemical  operation,  is  called  the  smelting  process.  It  rarely  happens  that  only 
one  kind  of  ore  is  operated  upon ;  the  more  usual  plan  is  to  mingle  richer  and  poorer 
ores  together  in  certain  quantities,  so  as  to  obtain  a  suitable  mixture,  attention  also 
being  paid  to  the  various  kinds  of  rock  which  accompany  the  ores,  so  as  to  obtain  by 
the  smelting  process  a  proper  slag ;  but  if,  as  is  more  often  the  oase,  this  end  caonot 
be  attained  by  the  mixing  of  ores  of  different  quality,  it  becomes  almost  always 
necessary  to  add  other  materials  which  either  chiefly  or  solely  act  as  fluxes,  and 
also  as  reducing  or  converting  agents,  by  promoting  in  various  ways,  to  be  presently 
more  fully  described,  the  separation  of  the  metals  from  their  ores.  We  distinguish 
accordingly  between  such  materials  as  charcoal,  coal  and  coke,  lime,  and  common 
salt,  which  we  term  roasting  materials  (Rostzuschlage),  and  smelting  or  fluxing 
materials,  such  as  quartz  and  various  silicates,  among  which  are  hornblende,  feldspar, 
augite,  greenstone,  chlorite-schist,  slag;  lime-containing  minerals,  as  limestone,  fluor- 
spar, gypsum,  heavy-spar;  minerals  containing  alumina,  as,  for  instance,  clay-slate 
and  marl.  Saline  materials  (admixtures)  are  also  used,  as  potassa,  borax,  Glauber 
salt,  and  saltpetre ;  likcTiise  metallic  admixtures,  as,  for  instance,  iron,  used  in  the 
decomposition  of  cinnabar  and  sulphuret  of  lead ;  zinc,  for  the  extraction  of  silver 
from  lead ;  arsenic,  in  the  preparation  of  certain  nickel  and  cobalt  ores ;  protoxide 
of  iron  (anvil  dross),  haematite  iron  ore,  and  manganese,  used  in  the  puddling  process ; 
certain  saline  admixtures,  by  which  we  understand,  in  this  instance  more  especially, 
such  blast  furnace  slags  as  contain  a  large  proportion  of  protoxide  of  iron,  and  are 
applied  in  the  process  of  puddling  on  account  of  the  oxygen  they  contain ;  or,  on  the 
otlier  hand,  are  used  as  so-called  precipitating  agents,  on  account  of  the  iron  they 
contain,  e.g.^  for  the  throwing  down  of  lead  from  galena.  The  substances  which  act 
only  as  fluxes  promote  the  separation  of  the  metal,  because  the  ore  is  more  readily 
rendered  fluid,  thereby  causing  the  particles  of  metal  to  unite  more  easily.  According 
to  their  mode  of  action,  fluxes  can  be  brought  under  three  heads,  viz. : — i.  Such  as 
exercise  no  chemical  action,  but  are  only  substances  promoting  fluidity,  as,  for 
instance,  fluor-spar,  borax,  common  salt,  and  various  slags ;  2.  Such  as  at  the  same 
time  exert  a  reducing  action,  as,  for  instance,  a  mixture  of  argol  and  saltpetre,  so- 
called  black  flux ;  3.  Such  as  act  as  absorbents,  either  of  acids  or  of  bases :  but  this 
class  belongs  more  properly  to  admixtures  ah-eady  alluded  to  above. 


SLAGS.  7 

The  uixiag  of  the  Smelt.  That  Operation,  by  which  the  ore  and  the  materials  required  for 
the  smelting  process  are  intimately  mixed  together,  often  in  previously  weighed  out 
quantities,  is  called  the  mixing,  and  the  quantity  which  is  to  be  used  within  a  given 
lapse  of  time  (generally  12  or  24  hours)  is  called  the  charge. 

8iMi3S*o5>2aaSii-      '^6  following  are  the  products  which,  generally  speaking,  are 
obtained  by  the  smelting  process  : — i.  Metals — ^Educts.  The  relative  degree  of  the 
purity  of  these  substances  is  indicated  when  gold  or  silver  are  alluded  to  by  the  title 
of  their  fineness  (purity),  fine  gold  or  fine  silver  being  understood  as  the  perfectiy 
pure  metal ;  but  as  regards  the  metals  not  designated  by  the  term  noble,  they  are 
called  raw  or  crude  metal,  while  a  higher  degree  of  purity  is  indicated  by  refined. 
2.   Such  products  as  are  not  present  ready  formed  in  the  ore,  but  are  the  result  of 
peculiar  reactions  which  take  place  during  the  smelting  process  between  the  various 
in^edients  submitted  to  the  operation ;   these  materials    are,  in  most  instances, 
ready  for  the  market,  and  comprise  the  so-called  hard  lead  which  contains  antimony, 
arsenic,  and  other  impurities;   arsenical  preparations,  as,  for  iastance,  arsenious 
acid,  orpiment,  realgar;  and  black  sulphuret  of  antimony.    3.  The  preparation  of 
educts  is  often  accompanied  by  the  formation  of  intermediate  or  by-products ;  if  these 
happen  still  to  contain  a  sufficient  quantity  of  the  metal  operated  upon  to  make  it 
worth  while  to  extract  it,  they  are  termed  intermediate  products ;  but  if  the  reverse  is 
the  case  they  are  called — 4.  Dross.     Such  intermediate  products  are  often  alloys ;  as, 
for  instance,  one  consisting  of  silver,  copper,  and  lead — ^the  so-called  TellerHlber — 
silver  containing  lead,  consisting  chiefly  of  lead,  with  a  smaller  or  larger  quantity  of 
copper  and  some  silver ;  so-called  black  copper,  a  mixture  of  copper,  iron,  and  lead ; 
snlphurets ;  arsenic  alloys,  so-called  Speiss,  as,  for  instance,  the  cobalt  and  nickel 
compounds  obtained  in  smalt  works,  chiefly  consisting  of  arsenical  nickel ;  carburetted 
metals,  as,  for  instance,  pig-iron  and  steel ;  r)xides,  as,  for  instance,  litharge  (oxide 
of  lead). 

aatu.  The  material  which  usually  passes  by  this  name  exhibits,  when  cold,  an 
enamel  or  glass-hke  appearance,  and  is  generally  made  up  of  various  combinations  of 
silica  with  earths,  such  as  lime,  magnesia,  alumina,  and  metallic  oxides,  as  the 
protoxides  of  iron  and  manganese.  The  slags  are  formed  during  the  smelting  process, 
because  the  raw  materials,  and  the  various  substances  employed,  contain  the  elements 
for  their  formation.  The  functions  of  the  slag  during  the  smelting  process  are  rather 
important,  servinjr  to  protect  the  particles  of  metal,  or  of  sulphuret  of  metal,  from  the 
oxidising  action  of  the  blast,  and  promoting  the  adhesion  and  union  of  the  particles'. 
Slags  are  applied  in  some  smelting  processes  as  a  flux ;  and  if  they  should  still  contain 
a  sufficient  quantity  of  metal,  tliey  are  added  to  another  batch  of  ore  to  be  operated 
upon.  As  regards  their  composition  and  nature,  they  are  classified  according  to  the 
quantity  of  silica  they  contain  as  sub-,  mono-,  hi-,  and  tri-silicates.  The  proportion 
which  the  oxygen  of  the  silica  beai's  to  tliat  contained  in  the  bases  is  as  follows : — 

Subsilicate 3  •  6 

Monosilicate      3  •  3 

jDisiixcaie    ••■     ■••     •■•     •••     ■•■     «••     0.3 
A.  nsLucaie  ••■     ■••     ■••     •••     •••     ■••     3*^ 

Slags  are  either  vitreous  or  crystalline.  It  very  jfrequentiy  happens  that  from  the 
latter  kind  portions  of  silicates  separate,  which,  as  regards  their  chemical  and  mineral- 
ogical  characters,  agree  with  minerals  met  with  in  nature,  such  as  augite,  olivine, 
WoUastonite,  mica,    idocraso,    chrysolite,    feldspar,   &c.     Generally    speaking,  the  . 


8  CHEMICAL  TECHNOLOGY. 

mixtures  of  monoailicates  produce  slags  which  are  very  fluid,  and  apt  to  consolidate 

rapidly  while  cooling,  while  the  mixtures  of  hi-  and  tri-silicates  produce  slags  which 

have  the  opposite  properties,  heing  pasty  and  tough. 

The  following  properties  and  constitution  denote  that  the  slags  are  suited  to  the 
smelting  process  : — i.  The  specifio  gravity  of  the  slag  while  molten  should  he  less  than 
that  of  the  product  (metal)  it  is  desired  to  obtain,  in  order  that  the  Blag  may  cover  the 
surface  of  the  molten  metal,  a.  The  slag  should  be  homogeneoas  throughout  the  duration 
of  the  process  of  smelting ;  since  the  contrary  would  denote  an  abnormal  working  of  the 
operation.  3.  The  slag  should  melt  readily,  and  thus  admit  of  the  particles  of  metal 
readily  sinking  downwards  as  a  consequence  of  their  higher  specific  gravity.  4.  The 
chemical  composition  of  the  slag  should  be  so  regulated  as  to  prevent  them  exerting  any 
decomposing  action  upon  the  metal. 

Iron. 

(Fe  =  56 ;  Sp.  gr.  =  77.) 

in>n;iuoeeiuniu».  Iron  is  the  most  important  and  most  useful  of  all  metals.  Its 
application  is  most  intimately  connected  with  all  branches  of  industry,  and  almost  all 
the  wants  and  requirements  of  common  daily  life.  The  reason  of  this  very  extended 
employment  of  iron  is  due,  partly  to  its  being  plentifully  and  even  superabundantly 
met  wiih.  in  nature,  but  partly,  if  not  chiefly,  in  consequence  of  the  great  ease  where- 
with this  metal,  during  its  reduction  from  the  ore,  assumes  various  modifications  and 
exhibits  different  characters,  each  possessing  some  special  feature  of  usefulness. 
Although  the  number  of  minerals  which  contain  iron  is  very  great,  comparatively  few 
are  used  in  practice  for  the  extraction  of  the  metal.  Those  that  are  used  are  all 
oxygen  compounds  of  iron,  and  chiefly  what  are  technically  known  to  ironmasters  and 
the  trade  as  ironstones. 

The  follovTing  is  a  list  of  the  minerals  termed  "  ironstones  "  : — 

1.  Magnetic  iron  ore,  (FeaO^,FeO=Fe304),  the  richest  of  all  iron  ores  (it  contains 
upwards  of  72  per  cent  of  iron),  is  pretty  largely  found,  especially  in  Russia,  Norway,  and 
Sweden,  in  the  crystalline  schistose  rock.  The  celebrated  Dannemora  (Sweden)  iron  is 
obtained  from  this  ore.  It  not  unfrequently  happens  that  this  mineral  is  more  or  less 
mixed  with  iron  p^tes,  galena,  copper  pyrites,  apatite  (chiefly  phosphate  of  lime),  and 
other  minerals,  which,  by  their  presence,  impair  the  good  quaUties  of  the  magnetic  iron  ore 
as  a  mineral. 

2.  HsBmatite  iron  ore,  red  ironstone,  (Fe^OO,  contains  about  69  per  cent  of  iron.  This 
mineral  occurs  in  seams  and  veins  in  the  older  geological  formations,  often  embedded 
in  gneiss  and  granite.  It  is  also  met  with  in  the  metamorphic  rocks,  and  is  frequently 
called  glassy  head,  owing  to  its  external  lustre;  also  bloodstone,  on  account  of  exhibiting, 
when  scratched  with  a  file  or  a  knife,  a  deep  red-coloured  streak.  When  this  ore  is  found 
mixed  with  silica,  it  is  called  siliceous  ironstone ;  when  occurring  along  and  mixed  with 
fidumina,  it  is  called  red  aluminous  iron  ore ;  mixed  with  lime,  the  ore  is  known  as 
ininette.  The  quantity  of  iron  present  in  these  ores  varies,  of  course,  considerably.  TfaJs 
ore  occurs  in  crystalUne  state,  in  especially  large  quantities  in  the  Island  of  Elba, 
and  ores  of  the  same  kiud,  but  different  in  quality,  are  found  in  England  and  Ireland, 
Saxony,  and  many  parts  of  Germany.  They  are,  in  all  eases,  especially  as  regards  the 
first-named  country,  largely  applied,  e.g,y  Lancashire  (Dlverston  and  Barrow-in-Furness). 

3.  Spathose  iron  ore,  (FeCOj),  with  48-3  per  cent  of  iron.  This  ore,  which  occurs  in  great 
variety,  is,  indeed,  the  chief  iron-stone,  often  containing  carbonate  of  protoxide  of  manganese 
in  larger  or  smaller  quantity.  This  ore  is  often  met  within  a  globular  or  kidney-like  shape, 
and  hence  called  Iddney  iron  ;  in  mineralogy,  spherosiderite.  The  ore  bears  a  great  many 
other  names,  derived  from  some  peculiarities  in  its  composition ;  for  instance,  it  is  known 
and  veiy  largely  worked  in  Scotland  as  black-band,  owing  to  its  being  mixed  with 
carbonaceous  and  bituminous  matters,  and  alternating  with  seams  of  coal.  It  is  known, 
also,  as  clay-ironstone,  being  then  mixed  with  more  of  less  argillaceous  matter,  and 
occurring  in  enormous  quantities  in  that  condition  in  Cleveland  and  Bosedale  (Yorkshire), 
in  Wales,  and  also  on  the  Continent  in  various  countries. 

4.  When  the  last-named  ore  is  acted  upon  by  air  and  water  containing  carbonic  acid,  a 
secondary  ore  is  formed,  known  as  brown  ironstone  (partly  FeaOs.HjO,  partiy  FeaO,,3HaO). 
In  mineralogy  this  ore  is  named  according  to  its  varying  physical  properties,  as  follows  : — 
Lepido-crocite,  needle-iron  ore,  pyroaiderite,  and  stilpnosiderite.     As  may  be  expected. 


IRON.  g 

thiB  mineral  is  often  mixed  with  carbonate  of  lime,  gilioa,  alumina ;  the  yellow  ironstone 
being  a  variety  of  the  aluminons  kind.  Banxite  may  in  some  instances  range  along  with 
this  kind  of  ore,  when  that  substance  consists  of  an  intimate  mixture  of  alumina  and 
peroxide  of  iron. 

5.  Pea-iron  ore,  in  smaller  or  larger  globular-shaped  particles,  formed  of  concentric  layers, 
containing  either  an  intimate  mixture  of  silica,  protoxide  of  iron,  and  water,  or  brown  iron 
ore  and  siliceous  clay.  The  origin  and  mode  of  formation  of  this  ore  are  unknown.  It 
occurs  in  France  and  in  the  South- West  of  Germany. 

6.  Marsh  iron  ore,  limonite,  met  with  in  parts  of  Europe,  generally  those  which  are 
only  Uttle  elevated  above  the  sea  level,  and  more  especially  in  or  near  moors  and  marshes, 
peat  bogs,  Ac. ;  in  some  parts  of  the  Netherlands,  Denmark,  Sweden,  and  North  Germany, 
and  also  in  the  United  iUngdom  to  some  extent.  This  ore  owes  its  origin  to  the  action  of 
decaying  vegetable  matter  upon  water  containing  carbonate  of  protoxide  of  iron  in  solution. 
The  ore  is  met  with  in  irregularly  shaped  lumps,  as  hard  sometimes  as  pebbles,  but  idso 
in  a  soft  and  spongy  condition ;  its  colour  is  brownish,  or  black,  and  it  consists  of  prot- 
oxide of  iron,  oxide  of  manganese,  phosphoric  acid,  organic  matter,  and  sand.  According 
to  M.  Hermann,  however,  the  ore  contams  hydrated  peroxide  of  iron,  hydrated  oxida  of 
manganese,  phosphate  of  peroxide  of  iron,  tribasic  crenate  of  peroxide  of  iron.  This 
ore  is  in  some  instances  largely  used  for  the  manufacture  of  cast-iron  objects  (especially 
for  domestic  and  ornamental  uses),  on  account  of  its  yielding  an  iron  of  great  fluidity, 
which  fills  the  moulds  very  completely,^  giving  sharp-figured  castings.  This  condition  is 
due  to  the  presence  of  the  phosphorus  in  such  iron  ;  but  the  presence  of  this  element  also 
causes  the  pig-iron  made  from  this  ore,  if  puddled,  to  yield  a  wrought-iron  which  is  both 
cold-  and  red-short. 

7.  Franklinite,  (Fea03[ZnO,MnO]),  containing  45  per  cent  of  iron,  21  percent  of  zinc, 
and  9  per  cent  of  manganese.  This  ore  occurs  in  New  Jersey,  U.S.,  and  is  there  employed 
both  for  the  extraction  of  iron  and  zinc. 

Iron  is  also  obtained  from  rich  slags,  which  often  contain,  in  the  shape  of  protoxide  of 
iron,  an  amount  varying  from  40  to  75  per  cent  of  that  metal ;  they  are  employed  in  the 
puddling  process.  The  scraps  of  iron  resulting  from  various  operations,  old  iron,  and 
waste  pieces  of  the  metal,  are  usefully  applied,  either  alone  or  with  the  ores,  to  be  re-con- 
verted into  metal. 

Taken  from  a  metallurgical  point  of  view,  iron  ores  are  distinguished  as  reducible  easily 
or  with  difficulty  (convertible  into  metal  readily,  or  fusible  with  difficulty).  To  the  former 
Class  belong  all  those  ores  which,  while  being  submitted  to  a  preliminary  roasting,  become 
porous,  and  hence  more  readily  penetrable  by  the  reducing  gases  present  in  the  blast- 
fomaoe ;  and,  as  a  consequence,  more  rapidly  reduced  and  molten.  The  spathose  iron 
ore  and  brown  iron  ore  belong  to  this  class ;  the  former  because  on  roasting  it  loses 
carbonic  acid,  while  the  latter  loses  water.  Magnetic  iron  ore,  and  hematite  iron  ore  in  all 
its  varieties,  are  reducible  with  difficulty. 

a.  Pio  OB  Crude  Iron. 

^*Sj£*iuSi^  The  extraction  of  iron  from  its  ores  is  chiefly  based  upon  the  two 
foUowing .  properties : — i.  While  particles  of  pure  or  nearly  pure  iron  are  infusible 
even  by  the  heat  produced  in  the  blast  furnace,  they  are  possessed  of  the  property  of 
agglutination  to  larger  masses ;  in  other  words,  the  property  (possessed  by  iron  and  only 
a  few  other  metals)  of  welding  together  at  a  bright  red  heat. 

2.  Iron  is  capable  of  uniting,  while  exposed  to  a  high  temperature,  and  in  the 
presence  of  an  excess  of  carbonaceous  matter  or  gases  containing  carbon,  with 
that  metalloid,  forming  with  it  an  easily  fusible  compound,  viz.,  a  carburet  of  iron, 
the  so-called  pig-  or  cast-iron. 

The  direct  manufacture  of  malleable  iron  from  iron  ores  was  in  former  times  a  very 
nsual  proceeding,  and  is  yet  carried  on  to  a  small  extent  in  some  parts  of  Europe 
(Styria,  Andorra,  Sardinia,  and  Sicily),  and  far  more  so  in  Hindostan ;  but  this 
method,  known  as  the  Catalan  process,  is  wasteful,  and  although  it  yields  iron  of 
excellent  quality,  it  also  requires  ores  of  great  richness.  The  process  is  not  suited  to 
meet  tlie  large  demands  now  made  for  iron ;  with  these  trifling  exceptions  aJl  iron  at 
the  present  day  is  obtained  by  the  production  first  of  pig-iron,  which  is  afterwaida 
converted  into  malleable  iron  by  the  puddling  process. 


lo  CHEMICAL  TECHNOLOGY. 

The  operations  by  which  iron  is  extracted  from  its  ores  are : — calcination  or  roasting, 
and  smelting.  The  object  of  the  first-named  operation  is  the  removal  from  the  ore 
of  such  substances  as  water,  carbonic  acid,  carbonaceous  matter  (as  present  in  the 
black-band  ironstone) ;  also  the  conversion  of  any  protoxide  into  peroxide,  because 
the  latter  is  less  apt  to  become  absorbed  by  the  slag,  and  to  promote  the  porosity  of 
the  ore.  The  calcined  ores  are  next  broken  up  to  lumps  of  suitable  size  by  means 
either  of  stamping  mills  or  cylinders,  or  by  macliinery  specially  made  for  the  purpose 
on  the  principle  of  quartz  and  stone  crushers ;  after  this  has  been  done  the  ores  are 
mixed,  rich  and  poor  together,  in  such  proportions  as  have  been  found  in  the  ex- 
perience of  the  workmen  to  jrield  the  best  quality  and  largest  quantity  of  iron. 

Theory  of  theLitm  Bxtroction  ^hc  orcs  having  thus  becu  mingled,  constitute  a  mixture  made 
up  chiefly  of  an  oxide  of  iron  and  of  gongue  (silica)  or  lime ;  carbonaceous  matter 
is  added  thereto,  and  the  mass  is  submitted  to  a  strong  heat,  the  result  being  the 
reduction  of  the  iron  to  the  metallic  state,  according  to  the  following  equation: — 

Fe203-J-3C=3CO-|-2Fe; 
the  action,  therefore,  of  coal  is  to  serve  as  fuel  and  at  the  same  time  as  reducing; 
agent  along  with  carbonic  oxide  and  carburetted  hydrogen ;  if,  however,  the  operation 
were  performed  by  simply  mixing  the  broken  up  ores  and  coal  or  coke,  and 
submitting  this  mixture  to  the  smelting  process,  the  iron  would  be  obtained  in  a 
finely  divided  and  spongy  condition ;  and  in  order  to  procure  the  union  of  the  particles 
of  metal  so  as  to  form  a  molten  mass  previous  to  the  smelting  operation  being  pro- 
ceeded with,  certain  substances  which  have  the  property  of  forming  with  the  gangue 
a  readily  fusible  glassy  mass  are  added.  The  substance  added  is  technically  known 
as  slag,  and  it  serves  not  only  the  purpose  just  mentioned,  but  also  that  of  with- 
drawing and  absorbing  from  the  ore  such  materials  as  might  injure  the  quality  of 
the  iron ;  and,  lastly,  the  slag  being  by  far  specifically  lighter  tlian  molten  iron,  floats 
on  the  surface  and  protects  the  metal  from  the  oxidising  action  of  the  air  blown  into 
the  furnace.  Slag  is  a  mixture  of  various  silicates ;  in  some  instances  the  ore  itself 
contains,  along  witli  the  oxide  of  iron,  the  constituents  necessary  to  form  a  good 
slag,  but  in  most  instances  ores  require  the  addition  of  such  materials  as  will  form, 
with  the  constituents  (excepting  the  iron  oxides)  a  proper  slag ;  thus,  for  instance,  if 
silica  were  wanting,  quartz  or  sand  would  be  added ;  and  if  bases  were  wanting,  lime- 
stone or  fluor-spar  (fluoride  of  calcium)  would  be  added.  The .  slag  should  become 
fluid  at  or  about  the  same  temperature  as  the  metal.  The  mixture  of  ironstone  aid 
slag-forming  material  is  caUed  a  batch,  and  is  so  arranged  as  not  to  contain  above  50 
per  cent  of  iron.  When  iron  in  the  molten  condition  and  carbonaceous  matter  (coal, 
coke,  or  charcoal,  although  the  latter  is  very  rarely  used)  come  in  contact,  as  is  the 
case  during  the  smelting  process  just  alluded  to,  the  molten  metal  dissolves  a  lai^e 
proportion  of  carbon ;  but  when  the  metal  cools  a  portion  of  the  cai'bon  separates  in 
the  crystalline  form ;  this  is  termed  blast-furnace  graphite :  another  portion  of  the 
carbon  remains,  however,  in  chemical  combination,  and  it  is  therefore  evident  that 
the  smelting  of  iron  ores  produces  an  iron — ^pig  or  crude  iron — ^which  contains 
carbon,  and  is,  therefore,  not  a  pure  metal. 

BiMt-farnAoe  proeeaa.  At  the  prcscut  day  the  extraction  of  iron  from  its  ores  (smelting)  is 
chic^fly  carried  on  eitlier  in  what  are  termed  blast-furnaces  or  blowing-furnaces. 
Tlirse  contrivances  are  not  essentially  diflerent  from  each  other  as  regards  their 
action,  but  their  arrangement  and  construction  is  so  far  different  that  the  slag  from 
blast-furnaces,  working  as  thoy  do  witli  what  is  termed  an  open  breast-plate,  runs  off" 


IHO.W  1, 

continiiously,  while  the  eIi^  from  the  blowing -fiimace  lina  to  be  cleared  from  to  time 
when  tapping  the  metal. 
""Sln'i^JiSU!"  *  blast-fnmace  is  an  oven  shon-inft  on  the  exterior  a  heavily  made 
wall  (Fig.  I,  A,  the  outer  wall],  having  a  height  of  from  14  t«  35  metiee;  the  imier 
limng  ia  made  in  the  shape  of  two  tmncaUd  cones  placed  together  at  their  basee ; 
the  brickwork  ifire  bricks)  which  constitute  this  double  cone-like  Btructure,  b,  is 


Fio.  1 


"7% 


BniTound  d  by  a  cftain"  m  1,  le  up    f  1  rikm  s  01         r  1  t    -\      u  1       lu  !    is  eil 

Teloped  bj  the  cxtcrTtal  coHtin„  of  heaiy  mas  nij  the  aajid  is  a,  bad  conductor  of 
heat  and  admits  also  of  space  bemg  allowed  for  the  expansion  by  heat  of  the  interior 
Blructure  The  portion  of  the  mtemal  rone  extPn  hn,,  from  b  to  c  IB  called  the  shaft, 
or  chamber,  while  the  portion  which  extends  from  d  to  e  is  named  the  boshes ;  the 
part  of  B  where  the  diameter  ia  greatest  is  called  the  belly  or  upper  part  of  the 
bosheB.  Below  the  bosliea  at  r.  the  space  is  gradually  made  nsirower,  and  called 
the  throat,  or  tunnel  hole,  the  lower  part  of  which  is  intended  for  collecting  the  molten 
metal,  and  named  the  crucible  or  hearth ;  this  portion  of  tlie  blnst-fumoce  is  lite 
most  important,  because  the  Bracltiiig  process  goes  on  in  it;  the  crucible  is  pro- 
Tided  with  two  openii^  placed  opposite  to  each  otlier.  and  containing  conically- shaped 
lubes  (see  Fig.  2)  called  the  tuyores,  euding  in  what  are  termed  the  nozzles  or  nose 
pipes,  or  the  blast  pipes ;  these  tubes  scn-e  to  convey  tlie  ah-  necessary  for  the 
furnace.     As  ahown  in  the  engraving,  the  admissiuu  of  air  to  the  nozzles  is  regulated 


12  CHEMICAL  TECHNOLOGY. 

by  a  valve.  The  upper  open  end  of  the  furnftoe  at  *  is  caUed  the  mouth  or  furnace-top ; 
through  this  opening  the  fuel  and  nuKture  of  ore  and  flux  are  put  iuto  the  furnace, 
which  is  (as  also  shown  in  Fig.  i)  situated  on  or  near  the  slope  of  a  hill,  so  as  to 
have  ready  access  to  the  mouth  by  meane  of  the  bridge  for  conveying  the  materials 
to  the  furnace-top.  The  lower  part  of  the  hearth  is  prolonged  towards  the  front,  thus 
forming  the  breast-pan,  which  is  enclosed  by  the  dam-stone,  m  ;  this  stone  is  somewhat 
removed  at  one  side  from  the  wall,  thereby  forming  a  alit,  which  is  technically  called 
the  tap-hole ;  this  is  the  discharge  aperture ;  while  the  smelting  is  going  on  this 
aperture  is  closed  up  with  fire-clay,  which  is  removed  when  it  is  required  to  with- 
draw the  sl^s  or  tap  the  crucible,  that  is  to  say,  discharge  the  molten  metal.    The 

Fio.  3. 


dam-stone  is  protected  by  an  iron  plate.  Three  only  of  the  sides  of  the  hearth  are 
continued  to  the  stone  constituting  tlie  bottom  of  the  arrangement :  the  fourth  is 
merely  brought  to  within  a  certain  distance  of  the  base,  where  it  is  supported  by 
strong  girders  of  caat-iron  firmly  fiied  into  the  masonry  of  tlie  walls,  and  on  which 
rests  a  heavy  bloch  of  sandstone  called  the  tymp  (see  Fig.  i),  which  is  supported 
by  a  very  heavy  and  stout  piece  of  iron  called  the  tymp  iron. 

iiM^wtaBKmiM  Jn  order  to  provide  the  necessary  quantity  of  air  for  the  blast- 
furnace, a  blowing  engine  is  attached ;  this  is  now  almost  exclnsively  constructed 
npon  what  ia  termed  the  cylinder  principle,  which  iu  one  of  its  most  convenient 
forms  is  delineated  in  Fig.  3.  The  cast-iron  cylinder,  a,  contains  a  piston,  c,  which 
by  means  of  the  piston  rod,  a,  passing  air-tight  through  the  stuffing  box,  e.  can 
be  moved  upwards  and  downwards;  at  b  and  d  the  cylinder  ia  in  commnnication  n-itli 
tlie  outer  air,  and  by  means  of/  and  g  it  communicates  with  the  chest,  e.  The 
openings  alluded  to  are  provided  with  self-acting  valves  for  regulating  the  flow  of  air, 
wliich  is  conveyed  through  i  into  the  pipes  communicating  with  the  blast-fiimace.  In 
order  to  regulate  the  blast,  a  large  sheet-iron  vessel,  in  construction  very  similar  to 
the  jias-holders  of  gas-works,  and  acling  on  the  same  principle,  is  applied.  The 
application  of  hot  air  for  the  blast  is  one  of  the  most  important  improvements  iu  the 


IRON.  13 

mannfiactare  of  iron,  since,  in  this  way,  a  decreased  consumption  of  fael,  to  the 
extent  on  an  average  of  0366  (from  i  to  |),  has  been  obtained;  while,  moreover, 
the  absolute  gain  in  the  production  of  iron  amounts  to  about  50  per  cent.  It  is  also 
stated  bj  many  iron-masters  that  the  fiimace  is  more  readily  and  regularly  worked ; 
but  this  statement  is  discredited  by  others,  who  aver  against  the  hot  blast  that  dis- 
turbances arise  more  frequently  in  the  regular  course  of  working ;  also,  that  the  very 
high  temperature  in  the  crucible  causes  the  rapid  destruction  of  the  fire-bricks,  and 
consequently  impairs  the  time  of  what  is  technically  termed  the  campaign,  that  is  to 
sav,  the  duration  of  the  fabric  of  the  blast-famace.  The  air  intended  for  the  hot  blast 
is  heated  either  by  the  gases  given  off  by  the  blast-furnace,  or  by  means  of  separate 
fire-places  which  heat  a  pipe  apparatus,  or  lastiy  by  means  of  Siemens's  regenerative 
furnace  system.  This  system  consists  in  first  conducting  the  gases  of  the  blast- 
famace  through  a  fire-brick  built  space  filled  with  fire-bricks  loosely  piled  together, 
which  becoming  thoroughly  red-hot  are  in  that  condition  capable  of  heating  the 
cold  air  previous  to  admitting  it,  care  being  taken  to  shut  off  the  blast-furnace  gases; 
by  this  means  the  air  can  be  heated  to  a  temperature  very  far  exceeding  that  which 
is  attainable  by  passing  the  air  through  iron  tubes,  these  not  admittiQg  without  serious 
injury  of  being  heated  to  so  high  a  temperature  in  contact  with  air.  The  hot  blast 
air  is  heated  to  from  200**  to  400'*  C. ;  blast-furnaces  fed  with  coke  as  fuel  require  per 
minute  of  time  from  2000  to  4000  cubic  feet  of  air. 

s^SSi  ft«J«.  -^^  blast  furnace  is  worked  in  the  following  planner : — The  furnace 
is  first  heated  by  igniting  in  it  a  quantity  of  wood.  When  this  has  rendered  the  oven 
thoroughly  dry,  the  fuel  intended  for  use  in  the  course  of  the  continued  process  is 
put  in  (this  fuel  used  to  be  in  Germany  wood  charcoal,  but  at  the  present  time  there, 
as  in  England,  coke  is  employed,  or  sometimes  smthracite ;  common  coals  are  rarely 
used) ;  the  furnace  is  at  first  entirely  filled  with  fuel,  and  when  quite  full  the  blast  is 
turned  on  and  a  beginning  made  with  the  charging  of  the  mixture  of  ore  and  flux, 
alternating  with  fresh  fuel.  By  the  burning  of  the  fuel,  and  the  fusing  of  the  ore  and 
flux,  the  layers  sink  downwards,  the  silica  fuses,  forming,  while  combuiing  with  the 
earths  and  some  of  the  oxides  present  in  the  ore,  a  slag  which  is  commonly  coloured 
by  the  presence  therein  of  oxide  of  iron,  while  the  iron  reduced  to  the  metallic  state, 
and  semi-fluid  at  first,  combines  with  carbon  to  form  readily  fusible  pig-iron ;  the  molten 
metal  collects  in  the  hearth  or  crucible ;  the  fused  slag  floats  on  the  top  of  the  motal,  but 
is  run  off  over  the  dam-stone.  The  molten  metal  is  tapped  off  about  twice  every 
24  hours,  or  as  soon  as  it  appears  to  reach  the  height  of  the  dam-stone.  The  aperture 
here  alluded  to,  and  closed  provisionally  by  means  of  fire-clay,  is  opened  by  the 
piercing  of  the  latter,  while  the  molten  metal  is  conveyed  through  channels  made  in 
the  sand  to  the  moulds,  also  formed  in  the  same  material :  during  the  operation  of 
tapping,  the  blast  is  shut  off.  Crude  iron  cast  in  the  shape  of  cakes  is  called  lump 
iron,  and  when  run  into  bars,  pig-iron.  The  campaign,  that  is,  the  operation  of 
smelting  with  the  same  furnace,  often  lasts  many  years ;  it  is,  in  fact,  continued  until 
the  oven  or  blast  furnace  becomes  worn  out. 

ciwminiProcMiKoinff      The  chemical  process  which  is  going  on  in  the  interior  of  the 

onfaiUwIatatlorof  the  o        o 

BUatFaxuM.  blast  fumaoe  when  at  work  (technically,  while  in  blast)  differs  con- 
siderably in  different  portions  of  the  vertical  section.  The  annexed  Figs.  4  and  5  repre- 
sent the  interior  of  a  blast  furnace  exhibited  in  perpendicular  section,  and  filled  with 
alternate  layers  of  fuel  and  mixed  ore  and  flux,  the  latter  being  indicated  by  the 
narrower,  the  former  by  tiie  wider  layers.     Counting  from  the  siu*facc  of  the  fluid  slag, 


14  CHEmCAL    TECHNOLOGY. 

//,  op  to  the  mouth  of  the  furnace  tlie  iuteiior  may  bu  divided  iut«  fivu  zoiiee  or 
regions,  viz : — 

I.  The  &'st  heating  zone,  a  b. 

z.  The  reduction  zone,  b  c. 

3.  The  carburfttiou  zone,  0  d. 

4.  The  meltii^  zone,  d  e. 

5.  The  comboBtion  zone,  ef. 

In  the  upper  part  of  the  furnace,  the  first  heating  zone,  the  materialB  become  warmed 
and  are  rendered  tlioroughly  dry,  but  they  hardly  become  hotter  than  a  low  red  heal. 
The  reduction  zone  ie  the  largest  in  extent.  In  the  lower  part  of  the  shaft  of  the  fumaoe, 
and  especially  towards  the  belly,  the  oxide  of  iron  is,  by  the  action  of  the  redticiiig 
gases,  first  converted  intoprotoxideof  iron  and  nest  into  metal.-  The  reducing  agents 
present  in  thia  :;one  are — carbonic  oxide,  earburetted  hydrogen  gas,  and  hydro- 
cyanic acid  gas  (cyanide  of  hydrogeni,  or  vapours  of  cyanide  of  potaEsium;  at  a  certain 
part  in  this  zone  the  iron  is  present  as  malleable  iron.  Deeper  dorni  in  the  furnace 
the  oarburation  zone  is  met  witli ;  liere  tlie  combination  between  the  iron  and  carbon 


takes  place,  producing  a  more  or  less  al«el -like  and  somewhat  caked  iron,  wliich,  when 
sinkii^,  enters  the  melting  zone  and  is  saturated  with  carbon  and  entirely  brought  to 
the  state  of  pig-iron.  At  the  portion  foi-ming  the  corabnstion  or  oxidation  zone,  which 
is,  as  compared  with  the  other  zones,  only  of  very  small  extent,  tlic  air  from  the 
blast  enters  the  fiimace  through  tlie  nozzles,  and  meeting  with  iuciindcscent  coke  at 
the  highest  possible  white  heat,  causes  the  formation  of  cai-bonic  acid,  but  tliis  gas  in 
passing  upwards  tlirough  other  layers  of  incandescent  fuel  becomes  reduced  to 
carbonic  oxide  ;C0i+C=2C0i ;  by  the  corabnstion  of  the  hydi'ogen  contained  in  Uie 
fuel,  water  is  also  formcil.  wHclv,  alonj;  witli  the  aiineoiis  vapour  contained  in  Uic  air 


IRON.  15 

of  the  blast  (recently  it  has  been  tried  to  eliminate  tliis  aqueous  vapour  by  passing 
the  air  previous  to  reaching  the  nozzles  through  concentrated  sulphuric  acid)  is 
decomposed  by  the  enormous  heat  of  the  middle  portion  of  the  furnace  as  well  as 
by  the  presence  of  carbon,  forming  hydrogen  and  oxygen,  the  former  of  which  enters 
into  combination  with  the  carbon,  forming  carburetted  hydrogen,  while  the  latter  com- 
bining with  the  same  element  produces  carbonic  oxide.  The  nitrogen  present  in  tlie 
coke,  as  well  as  a  portion  of  tlie  nitrogen  present  in  the  air  of  tlie  blast,  combines  %vith 
the  carbon,  forming  cyanogen  (eitlier  as  cyanide  of  some  metal  or  as  cyanide  of 
hydrogen).*  Tlie  reducing  gases  meeting  with  the  ores  cause  the  oxides  present 
to  be  converted  into  metal,  wlule  the  gases  remaining  (the  blast  furnace  gases) 
escape  from  the  mouth  of  the  furnace.  The  reduced  iron  combines,  wlule  sinking 
downwards,  with  carbon,  forming  the  crude  metal,  and  fuses  in  so  doing ;  the  imion  of 
the  particles  being  promoted  by  the  slag.  As  soon  as  the  iron  reaches  that  portion  of 
the  furnace  where  the  heat  is  strongest,  the  carbon  contained  in  the  metal  begins  to 
exercise  its  reducing  action  upon  such  substances  as  alumina,  lime,  silica,  &c.,  which 
in  the  reduced,  or  metaUic,  state  combine  with  the  iron. 

Becent  researches  have  proved  that  the  copious  production  of  hydrocyanic  acid 
generated  by  the  process  going  on  in  the  1>last-fumace  greatly  and  very  essentially  assists 
the  redaction  of  the  ores  ;  that  compound  of  course  combines  with  the  edkaUes  and  alkaline 
earths  contained  in  the  fuel  and  other  materials.  It  has  been  surmised  that  the  crude 
iron  is  not  solely  a  carburet  of  that  metal,  as  might  be  produced  by  the  decomposition 
of  cyanide  of  iron,  but,  in  addition  to  a  small  quantity  of  that  body,  contains  also 
nitride  (a  nitrogen  compound)  of  that  metal.  In  support  of  this  view  the  fact  is  brought 
forward,  that  Dr.  Wdhler,  of  Gottingen,  found  many  years  ago  that  the  cubical  crystals 
of  what  was  considered  to  be  metallic  titanium,  and  found  in  the  blast  furnace  slag,  turned 
ont  to  be  a  compound  of  nitride  of  titanium  and  cyaaide  of  that  metal.  In  order  to  give 
some  idea  of  the  large  quantity  of  metaUic  cyanides  generated  by  the  blast  fxuTiace  process, 
we  briefly  quote  from  the  researches  made  on  this  subject  by  Drs.  Bunsen  and  L.  Playfair, 
that  an  English  blast-furnace,  fed  with  coal  as  fuel,  produced  daily  a  quantity  of 
225  ponnds.  M.  Eck,  who  made  some  researches  on  this  subject  at  Eonlgshutte,  in  Upper 
Silesia  (Prussia),  discovered  the  formation  of  both  cyanide  and  sulphooyanide  of  potassinm, 
and  he  found  by  calculating  from  the  quantity  of  potassa  contained  in  the  ores,  flux,  and 
fuel,  a  daily  production  of  35  i  pounds  of  cyanide  of  potassium.  The  reduction  of  alumina 
and  silica  to  aluminium  and  silidum  also  takes  place  in  the  melting  zone. 

SSJSSDiif^'pSSi!  ^^'  5  exhibits  the  temperature  prevailing  at  the  limits  of  each 
zone.  The  temperature  of  the  combustion-zone  would  be  far  higher  than  happens 
to  be  the  case  were  it  not  that,  by  the  conversion  of  carbonic  acid  into  carbonic 
oxide — ^that  is,  the  absorption,  or  more  correctly  vapourisation  of  carbon — a  considerable 
lowering  of  temperature  (in  other  words,  absorption  of  heat  which  becomes  latent)  is 
produced.  It  should  be  remembered  that  here  the  volume  of  tlie  carbonic  acid  is 
also  doubled,  while  this  reaction  is  taking  place,  and  that  process  of  course  also 
absorbs  heat. 

Taking  into  due  consideration  the  fact  that,  under  tlie  most  favourable  conditions, 
only  i6'55  P^^  ^^^  ^^  ^^  ^^^  supphed  to  a  blast-furnace  is  usefully  consumed, 
while  no  less  than  83*45  P^  *^^^^  escapes  from  the  mouth  in  the  shape  of  com- 

^^■JJJJ^**  bustible  gases,  it  cannot  excite  any  wonder  that  the  idea  arose  of  utilising 
these  gases :  this  idea  has  actually  resulted  in  various  useful  ways,  as,  for  instance, 
for  the  fusion  and  puddling  of  the  iron,  for  the  refining  and  cleansing  by  welding 
of  the  iron,  for  the  heating  of  the  blast,  the  roasting  of  the  ore,  and  the  drying 
and  carbonisation  of  the  wood. 

*  According  to  the  view  of  M.  Berthclot  [1869]  there  is  in  this  instance  first  formed 
acetylide  of  potasflium,  GaKa*  which  then  combines  directly  with  nitrogen  to  form  cyanide 
of  potassinm,  2(CNK). 


i6  CHEMICAL    TECHNOLOGY. 

^^toSfuanniiS^?^*      ^®  application  of  the  gases  to  the  useful  purposes  just  mentioned 
Sia-«mmoniac.  does  uot  exhaust  the  list  of  such  appUcations.    Drs.  Bunsen  and 

Playfair  found  that  the  gases  emitted  by  blast-furnaces  fed  with  coal  as  fuel  contain  such 
a  large  amount  of  ammonia  that  the  presence  of  that  gas  in  the  lower  parts  of  the  blast- 
furnace is  even  perceptible  to  the  smell.  These  eminent  savants  proposed  to  convey  the 
gases  previous  to  being  used  as  fuel  through  a  chamber  containing  hydrochloric  acid  gas : 
the  solution  of  sal-ammoniac  thus  obtained  should  be  run  into  the  pan  of  a  suitably 
constructed  reverberatory  furnace;  and  a  small  portion  of  the  current  of  gas,  after 
having  been  ignited,  being  carried  over  the  surface  of  the  liquid,  the  evaporating  process 
can  be  regulated  so  as  to  obtain  a  continuous  stream  of  a  concentrated  solution  of  sal- 
ammoniac  as  a  metallurgical  by-product.  Experiments  instituted  at  the  Alfreton  Iron 
Works  (blast-furnace)  proved  that  in  this  way  about  2-44  cwts.  of  sal-ammoniac  could  be 
produced  daily  without  any  great  expense  and  without  any  interference  with  the  process 
of  iron  manufacture.  The  formation  of  sal-ammoniac  is  intimately  connected  with  the 
formation  of  cyanogen  just  spoken  of.  When  cyanide  of  potassium  comes  into  contact  with 
aqueous  vapour,  it  is  decomposed  into  ammonia  and  formiate  of  potassa — 

(KCN-f  2H20=NH3-fCHK02}  ; 
the  reverse  reaction,  that  is  to  say,  the  withdrawal  of  aU  oxygen  in  the  form  of  water, 
from  formiate  of  ammonia  would  result  in  the  formation  of  cyanide  of  hydrogen — 

[CH(NH4)  Oa  ~  2H2O  =  CHN] . 

^Ss^iron?*  '^^  ^^^^  obtained  by  the  blast-fttmace  process  is  impure,  and  therefore 
called  crude  cast-iron  ;  it  contains  carbon  (in  the  shape  of  graphite  as  well  as 
in  a  state  of  intimate  chemical  combination  witli  iron  as  a  carburet  of  that  metal), 
silicium  again  as  so-called  silicium  graphite  and  as  a  siliciuret  of  iron,  sulphur, 
phosphorus,  arsenic,  and  aluminium.  The  colour  and  physical  properties  of  the  iron 
are  determined  by  the  quantity  of  carbon  it  contains.  Formerly  the  more  or  less 
deep  colour  of  the  crude  iron  was  believed  to  be  dependent  upon  the  larger  or 
smaller  quantity  of  carbon  the  iron  contained,  and  accordingly,  the  deepest 
coloured  metal  was  supposed  to  contain  the  largest,  and  the  least  coloured  iron  the 
smallest,  quantity  of  carbon ;  investigations  have,  however,  satis£a,ctorily  proved  that 
it  is  not  so  much  the  quantity  as  the  manner  in  which  the  carbon  (likewise  the 
silicium)  is  present  that  determines  the  quality.  The  fact  is,  that  ^dth  carbon  and 
silicium  a  portion  only  is  chemically  combined  with  the  iron,  while  the  largest  pro- 
portion of  these  metalloids  is  only  mechanically  mixed  with  the  metal,  being,-  as 
already  stated,  present  in  the  form  of  graphite  (graphitic  carbon  and  silicium). 
According  to  the  researches  of  M.  Fr6my  and  others,  it  is  probable  that  crude  iron 
frequently  contains  nitrogen,  and  that  the  presence  of  this  element  influences  the 
quality  of  the  metal ;  but  tliis  view  is  not  endorsed  by  MM.  Caron,  Gruner,  and 
Dr.  Kammelsberg.  There  are  two  chief  qualities  of  crude  iron  in  the  trade,  viz., 
white  and  grey  coloured. 

White  cwt-iron.  "White  cast-irou  is  distinguished  by  its  silvery  white  colour,  hardness, 
brittleness,  strong  lustre,  and  higher  specific  gravity,  which  ranges  from  758  to  768. 
Sometimes  this  kind  of  iron  happens  to  contain  prismatic  crystals  visible  to  the 
naked  eye,  and  such  iron  is  then  caUed  spiegeleisen,  or  crystalline  pig  (crude  steel 
iron).  This  variety  of  iron  may  be  viewed  as  a  combination  of  CFes,  or,  more  accu- 
rately stated  as  FeeC+FeaC,  with  593  per  cent  of  C.  If  the  structure  of  the  white 
cast-iron  is  radiated  and  fibrous,  while  the  colour  is  bluish  grey,  ihe  metal  is  known 
as  white  pig-iron  with  a  granular  fracture.  When  the  white  colour  disappears  still 
more,  and  the  fracture  becomes  jagged,  such  a  metal  holds  a  medium  between  wbite 
and  grey  pig,  and  is  therefore  called  porous  white  pig. 

owy  Out-Iron.  Grey  cast-iron  exhibits  a  bright  grey  to  deep  blackish  grey  colour. 
Its  texture  is  granular  or  scaly  ;  its  specific  gi'avity  averages  about  7,  consequently 
less  than  the  white  variety,  and  the  grey  iron  is  also  less  hai-d/   When  pigs  happen 


IRON.  17 

to  contain  both  grey  and  white  iron  in  portions  only,  or  dispei-sed  t}u'oug}i  their  entue 
mass,  such  metal  is  called  half-and-half  iron,  and  is  specially  applicable  to  foundry 
purposes.  The  chemical  diJSerence  between  white  and  grey  cast-iron  is  due  to  the 
fact  that  the  former  only  contains  chemically-combined  carbon  (from  4  to  5  per  cent), 
while  the  latter  contains  from  05  to  2  per  cent  of  this  element  in  the  combined 
state,  with  rather  more  than  that  amount  mechanically  mixed,  viz.,  from  13  to  37 
per  cent.  As  regards  the  melting-point  of  cast-iron,  the  white  variety  fuses  at  a 
lower  temperature  and  more  easily ;  but  the  grey  cast-iron  possesses  far  gi'eater 
fluidity.  Crude  cast-iron  is  not  malleable,  and  cannot  be  welded  or  forged ;  when 
made  red-hot,  it  becomes  very  soft — so  soft  that  it  can  be  cut  with  a  saw  such  as  is 
used  for  sawing  wood;  but  when  placed  on  an  anvil  and  hammered,  this  iron 
breaks  into  fragments  even  when  red  hot.  Grey  cast-iron  is  the  best,  and,  in  fact, 
only  suitable  kind  of  crude  iron  to  be  used  for  making  iron  castings.  The  perfect 
fluidity  of  this  metal  when  molten  causes  it  to  fill  the  moulds  well,  and  to  yield  excel- 
lently sharp  and  well-defined  forms.  White  cast-iron,  on  the  contrary,  is  not  used 
for  iron-foundry  purposes,  because,  while  solidifying,  it  warps,  and  the  surface 
becomes  concave.'  Grey  cast-iron  can  be  filed,  cut  with  the  cold  chisel,  turned  upon 
the  lathe,  and  planed.  White  cast-iron  is  too  hard  to  admit  of  any  such  operations 
being  performed  upon  it.  Grey  cast-iron,  molten  and  tlien  suddenly  cooled,  is 
converted  into  white  cast-iron ;  on  the  other  hand,  white  cast-iron,  molten  at  a  very 
bigh  temperature  (heated  far  above  its  melting-point),  and  cooled  very  slowly,  becomes 
converted  into  grey  cast-iron. 

The  quality  of  the  iron  produced  by  the  blast-furnace  process  does  not  so  much  depend 
apon  the  ores  and  other  materials  Used.  In  this  respect  the  temperature  is  of  far  greater 
importance.  It  would  appear  that  after  eveiy  fresh  charge  there  is  at  first  produced  white 
cast-iron,  which  is  only  converted  into  grey  cast-iron  by  a  very  much  increased  tempera- 
ture. If  the  reduction  of  the  ore  to  metal — care  being  of  course  taken  to  have  a  proper 
proportion  of  ore  and  the  other  materials — proceeds  reg^nlarly,  the  furnace  is  said  to  be  in 
a  healthy  state  of  working.  Under  such  conditions,  the  slag,  which  contains  only  very 
little  protoxide  of  iron,  is  never  deeply  coloured.  If  fuel  were  not  snppUed  in  proper 
proportion  and  the  ore  to  prevail,  the  reduction  would  probably  be  imperfect  and  the  slag 
a  deep  eolonr,  in  consequence  of  the  presence  of  a  liurge  quantity  of  protoxide  of  iron 
(colour  of  dark  green  bottle  glass).  Such  a  condition  of  working  is  termed  irregular. 
When,  in  consequence  of  an  excess  of  fuel,  the  heat  in  the  furnace  becomes  very  great, 
that  condition  of  workmg  is  termed  hot,  and  only  grey  oast-iron  is  formed. 

The  results  of  the  chemical  analysis  of  some  varieties  of  crude  metal  may  elucidate  the 
general  composition  of  cast-iron :  the  under-mentioned  samples  are  : — i.  Speigol  iron,  made 
from  14  parts  of  spathose  ironstone  and  9  parts  brown  iron  ore  (Hammerhiitte).  2.  White 
pig-iron,  with  a  granular  fracture,  from  Styria.  3.  White  pig.  4.  Half-and-half  pig. 
5.  Grey  east-iron  (from  brown  iron  ore  and  charcoal).  6.  Grey  cast-iron,  from  brown  iron 
and  spathose  iron  ore  mixed.  7.  Grey  cast-iron,  from  ochreous  brown  iron  ore  and  coke. 
The  sign  —  indicates  that  no  search  or  testing  was  made  for  the  substance  ;  the  sign  o  in- 
dicates that  the  substance  was  not  found. 

I.  2.  3.  4.  5.  6.  7. 

Combined  carbon      ..     5'i4        4-920        2*91        278        0*89        i'03        0*58 

Graphite     o  o  o  1-99        371        3*62        2*57 

Sulphur      o*o2        0*017        o'oi  o  —  —  — 

Phosphorus        ..     ..     o-o8  o  o"o8        1*23         —  —  — 

SilicLum      0*55  o  o  871         —  —  — 

Manganese 4*49  o  179  o  —  —  — 

The  results  below  are  those  obtained  by  M.  Buchner,  while  examining  the  quantities  of 

earbon  and  sUicium  contained  in  crude  iron  :  x,  2,  3,  4,  are  spiegel  iron,  almost  or  quite 
ciystaUine ;  5,  6,  porous  white  pig. 

1.           2.  3.            4.            5.             6. 

Cy 4'i4        3«o  4*09        375        3*3i        3'03 

C/3 ^           _  _           _           -           - 

Si O'oi        001  0*26        0*27        Spur        0*15 


i8  CHEMICAL  TECHNOLOGY, 

7,  8,  9.  White,  very  bright,  crude  iron.  10.  White  pig.  11.  Half-and-half  pig. 
12.  Strongly  mixed  half-and-half. 

7.  8.  9.  10.  II.  12. 

%::  ::  :;  ^1°    *r   'i^   ^'^]  3-34    ^t 

Si o'i4        o*i2        0*10        0*66        o'lo        0*20 

13.  Less  strongly  mixed  half-and-half.  14, 15,  16.  Qrey  cast-iron.  17.  Ooarse-grained 
cast-iron.     18.  Over-coaled  black-greyish  cast-iron. 

13;  14.  15.  16.  17.  18. 

O7 2*17  i'35  i*i8  071  0*38  0*26 

C^ 2'ii  2*47  2*42  279  3*28  3*83 

Si 0*09  070  o'66  1*53  1*62  0*59 

"ttSplStaSS???*      ^®  present  (1870)  production  of  crude  iron  (pig-iron)  amounts  to 
crade-iron.        rather  more  than  200  zuillions  of  hundred  weights.    Of  this  quantity  the 
under-mentioned  countries  produce : — 

United  Kingdom  of  Great  Britain  and  Ireland 115,000,000  cwts. 

France      24,500,000  „ 

North  America,  U.S 20,200,000  „ 

Prussia     16,300,000  „ 

Belgium 8,900,000  „ 

Austria     6,750,000  „ 

Bussia       6,000,000  „ 

Sweden     4,500,000  „ 

Luxemburg      1,100,000  „ 

Bavaria     732,000  „ 

Saxony      280,000  „ 

Wurttemburg 138,000  „ 

Baden       16,000  „ 

Hesse        250,000  „ 

Brunswick        90,000  „ 

Thuringia 18,000  „ 

Australia 2,000,000  „ 

Italy 750,000  „ 

Spam 1,200,000  „ 

Norway     500,000  „ 

Denmark  . .     . .  ^ 300,000  „ 

209,524,000  owts. 
EEaving  a  value  of  about  97*5  million  pounds  sterling. 

iron<<oiiiidry-wotk.  For  the  manufacture  of  iron  castings  a  somewhat  mixed  greyiron 

B«Miiing  onuto  oait-boD.  jg  employed,  because  its  qualities  best  suit  the  purpose.  Theee 
qualities  are  closeness  of  grain,  strength,  a  capability  to  well  fill  the  moulds,  coupled  with 
sufficient  softness  to  admit  of  boring,  filing,  &o.  Although  iron  castings  can  be  made 
directly  from  the  tapping  of  the  blast-furnace,  it  is  found  advantageous  and  preferable  in 
practice  to  re-melt  the  pigs.  This  operation  is  carried  on  in  crucibles  in  a  cupola  furnace, 
or  in  a  reverberatory  furnace.  Crucibles  (made  of  plumbago  or  fire-clay)  are  only  used  for 
making  castings  of  small  size.  The  quantity  of  iron  melted  in  crucibles  does  not  usually 
exceed  five  or  eight  pounds. 

Shaft  at  oapoi*  rnnuuM.  For  the  purpoBCS  of  the  iron-foundry,  the  shaft  or  cupola  furnace, 
represented  in  Figs.  6  and  7,  is  more  generally  used.  The  cupola  furnace  is  in  form  cylin- 
drical, and  from  2*5  to  3*5  met.  high.  The  pig-iron,  previously  broken  up  to  lumps 
of  suitable  size,  and  the  fuel,  which  may  be  either  coke  or  wood  charcoal,  are  placed  m 
alternate  layers  in  the  shaft  a  ;  the  openings  e  and  d  are  intended  for  the  insertion  of  the 
tuyeres  connected  with  tiie  blast.  The  opening  leading  to  the  spout,  b,  is  closed  during 
the  progress  of  the  melting ;  as  soon  as  the  molten  iron  reaches  the  orifice  at  a,  this 
opening  is  closed  by  means  of  fire-clay,  and  the  tuyere  first  placed  in  a  is  transferred  to 
the  opening  d.  The  molten  metal  is  either  conducted  by  the  aid  of  channels  direct  to  the 
moulds,  or  tapped  into  suitable  vessels  and  carried  to  the  moulds.  In  many  instances 
cranes  are  used  to  transport  the  molten  metal.  Here  also  the  application  of  hot  air  has 
been  attended  with  a  great  saving  of  fuel. 

B«TariMn*oi7  roinMo.  In  some  cases  pig-iron  is  melted  in  a  reverberatory  furnace,  the  iron 
being  placed  on  the  smelting-hearth,  which  is  covered  with  sand ;  the  hearth  is  slightly 
inclined  and  narrowed  towards  the  tapping-hole.  A  strong  coal  fire  is  made  up,  and  the 
flame  playing  across  the  fire-bridge  is  directed  over  the  entire  length  of  the  foniace.  and 


ISON. 


>9 


thenoe  into  b  high  ohimnBy,  Tha  molten  metal  on  being  tapped  is  oondnoted  to  the 
■uoDlds  in  the  Bune  manner  aa  with  the  oapola  fnrnaoB.  Rather  more  than  50  owta.  of 
mg-iroD  oao  be  melted  at  once  in  a  reverberatory  fnmaoa  ;  but  ainoe  the  air  has  free  aooeas, 
the  iron  beoomea  gradnally  deoarboaiaed,  and  is  thuH  rendered  unfit  for  oaatings. 

iuWb«  ih>  miiul  The  most  aaBential,  and  also  most  diffionlt,  part  of  the  iron-fonnder's 
work  IS  the  proper  oonrtmctionof  themouLla.  Aooording  to  themateriaU  from  which  the 
moiildB  are  oongtmctod,  wo  distinguieh — 1.  Sand  mouldmg  or  green-sand  moulding,  the 
material  being  a  peculiar  kind  of  aand  (foundry- aand).— It  ia  necesaa^  for  this  aand  to  be 
«oeedmgly  fine,  and  yet  suffioiently  coherent  that  the  aharpeBt  anglee  and  oomerB  will 
TBBinn  standing.  This  latter  property  ie  imparted  to  the  Band  by  adding  as  much  clay  aa 
will  render  the  mass  capable  of  being  squeezed  with  the  baud  into  balls  when  uioiBtened 
with  water.  A  certain  amount  of  porosity  ia  also  requisite  to  enable  the  steam  which  is 
loimed  whan  the  molten  iron  oomes  into  contact  with  the  monhl  to  readily  escape.  This 
propatty  LB  oommunioated  by  the  addition  of  powdered  charcoal.  Sand-monlda  are  not 
dned  before  the  molten  iron  is  ponied  in.     Such  objects  as  platea,  grates,  tailinga.  and 


wbeda,  which  are  lerel  on  one  aide,  are  oast  in  open  sand-monldB ;  that  is  to  say,  od  the 
floor  of  the  foundry.  preTionaly  covered  with  sand  of  the  requiaite  quality,  the  moold* 
being  obtained  by  pressing  the  patterns  into  the  Band.  For  other  branchee  of  the  work, 
as,  for  instance,  iron-pots,  the  boi  mould  is  used.  a.  Dry  sand  moulding. — The  forms  are 
made  in  MUid  and  oUy,  or  loam,  care  being  taken  to  dry  the  monlda  thoroughly  before 
easting.  3.  Loam -casting.— The  material  need  for  this  purpose  is  loam,  whi<£,  prerioua 
to  being  nsed,  is  sifted,  moistened,  and  mixed  with  horae.dong  to  picTent  the  moulds  from 
oraoking  during  drying.  4.  Oasa-hardeoing,  or  casting  in  iron  moulds. — Thia  mode  of  casting 
iron  only  applies  to  some  pemliar  descriptions  of  work,  as,  for,  inBtanoo,  the  cylinders  of 
roUing-millfl,  aome  kinds  of  shot  and  shells,  and  railway  waggon-wheels.*  Bj  the  nse  of 
irim  monlds,  the  casting  oools  and  solidifies  Tery  rapidly,  and,  as  a  conseguenoe,  the  outer 
layer  beoomei  oonvertol  into  white  cast-iron,  which  is  very  hard.  Thus  the  cylinders  for 
rolling-mills  can  be  so  made,  that  while  the  eurtace  ia  very  hard,  they  are  not  brittle,  and, 
therefore,  fragile,  heoanse  the  interior  condsts  of  grey  cast-iron. 

Oreen-sand  casting  is  by  far  the  most  general  mode  ot  casting:  furnace-bars,  cast-iron 
railings,  grates,  plates,  wheels,  and  a  Taiiety  of  objects,  are  thus  made.  Dry-sand 
moulding  is  used  for  the  casting  of  iron  gas-  and  water-pipes,  and  also  of  east-iron 
ordnance.  This  latter  ia  preferably  made  from  such  pig-iron  as  contains  grey  and  white 
iron  mixed ;  a  higher  degree  of  tonghneia  and  elasticity  can  thus  be  obtained.  Dry-«and 
monlding  is  also  used  tor  the  maUng  of  Bmall  ornamental  objects,  so.called  fer  dt  Berlin, 
■uoh  as  cast-iron  ink-stands,  candlesticks,  and  a  peculiar  kind  of  cast-iron  pins,  as  well  as 
brooches,  ear-rings,  and  aimilaT  things.  Loam-monlding  is  used  for  the  casting  of  large- 
■ited  eaiUdrons,  beUa,  and  other  large  objects  for  which  no  wooden  pattern  is  made ;  (Jio 
for  the  eaMing  of  »tMm-«ngine  cylinders.  We  distinguish  in  this  kmd  ot  monlding  three 
chief  parts,  Tiz. : — 

e  made  of  best 


wroaght-iron,  and  forged  by  n 


n  itaam-hammeni.  - 


20  CHEMICAL  TECHNOLOGY, 

a.  The  core,  or  kernel,  the  size  and  shape  of  which  corresponds  to  the  intOTior  of  the 
object  to  be  cast. 

b.  The  foundry-pattern. 

c.  The  exterior  mould,  also  termed  the  case. 

The  loam  mouldings  are  verj'  rapidly  dried ;  the  casting  of  statues  and  other  monumental 
work  is  done  by  loam  moulding,  but  zinc  is  beginning  to  supersede  iron  for  this  purpose. 
Whenever  objects  have  to  be  cast,  the  surface  of  which  is  very  unequal,  ».#.,  so  shaped 
that  a  partial  dismounting  of  the  case  is  impossible,  as  may  happen  for  instance  with 
statues  and  monumental  work,  the  shape  is  made  on  the  core  by  means  of  wax :  the 
pattern  maker  constructs  a  pattern,  often  consisting  of  a  number  of  loose  pieces ;  into  this 
the  molten  wax  is  poured,  and  the  mould  thus  obtained  is  carefully  placed  on  the  core  and 
properly  joined.  The  wax  mould  is  brushed  over  with  a  mixture  of  pulverised  graphite  and 
very  finely  divided  clay,  which  operation  is  several  times  repeated  ;  after  this  the  mould  is 
covered  with  a  layer  of  loam  mixed  with  cow  hair,  and  as  soon  as  this  layer  is  dry  the  wax  is 
removed  by  applying  a  gentle  heat,  a  channel  having  been  left  by  which  the  wax  can  escape. 

Annealing.     The  Castings,  when  sufficiently  cool,  are  deaned  from  adhering  sand,  the  seams  cut 

Tempering,  ^ff  with  acoldchisel,  and  in  many  cases  submitted  to  a  series  of  mechanical  opera- 
tions, as,  for  instance,  cast-iron  ordnance,  which  has  to  be  bored,  while  other  ohjects  have  to 
be  worked  in  the  lathe  and  planed.  Frequently  cast-iron  objects  have  become  as  hard  and 
brittle  as  if  they  had  been  cast  from  white  pig-iron,  and  consequently  are  unfit  for 
filing,  (&c.  ;  such  iron  is  restored  to  the  requisite  softness  by  annealing  or  tempering.  In 
this  operation  the  castings  are  submitted  to  a  strong  red  heat  and  cooled  slowly,  being  at 
the  same  time  protected  from  the  oxidising  influence  of  the  air ;  the  annealing  is  effected 
either  by  a  physical  or  a  chemical  process.  If  the  former  is  used,  the  castings  are  simply 
covered  with  a  thick  layer  of  clay  and  made  red-hot,  the  effect  being  a  simple  rearrangement 
of  the  molecules  of  the  iron,  which  is  thus  rendered  soft  again ;  the  heating  to  redness  is 
also  sometimes  effected  by  placing  the  castings  under  a  layer  of  dry  sand  or  in  suitably 
constructed  vessels  filled  with  charcoal  or  coke  powder.  If  it  is  desired  to  impart  to  the 
castings  somewhat  of  the  strength  and  toughness  possessed  by  steel  and  malleable  iron, 
the  tempering  is  so  arranged,  and  heat  appUed  for  a  longer  time,  while  the  metal  is 
surrounded  by  a  mixture  of  pulverised  charcoal,  bone-ash,  and  forge  scales,  red  oxide  of 
iron,  oxide  of  manganese,  or  oxida  of  zinc ;  cast-iron  which  has  been  uniformly  and 
thoroughly  decarbonised,  is  called  malleable  cast-iron.  A  great  many  objects  formerly 
exclusively  made  of  wrought-iron  are  now  cast  and  treated  in  this  way,  while  a  number  of 
others,  inclusive  even  of  razors,  are  made  of  cast-iron  superficially  converted  into  steel  by 
a  method  which  will  be  described  under  the  heading  of  Steel.  In  order  to  prevent  the 
rusting  of  articles  made  of  cast-iron,  they  are  frequently  covered  with  a  varnish  made  from 
coal  tar  and  powdered  graphite,  or  boiled  linseed  oil  and  lamp-black,  and  when  intended 
for  ornamental  or  domestic  use  they  are  bronzed  or  burnished. 

Enamelling  of  Among  the  first  cast-iron  objects  ever  enamelled  were  the  pans  used  in 
caat-iron.  kltchens  for  culinary  purposes,  but  at  the  present  time,  especially  in  England, 
the  enamelling  of  cast-iron  is  carried  on  to  a  large  extent  and  includes  a  variety  of  things 
made  of  cast-  and  even  wrought-iron.  The  process  in  use  is  briefly  as  follows : — The 
surface  of  the  cast-iron  to  be  enamelled  is  first  carefully  cleaned  by  scouring  with  sand 
and  dilute  sulphuric  acid,  next  a  somewhat  thickish  magma,  made  of  pulverised  quartz, 
borax,  feldspar,  kaolin,  and  water,  is  brushed  over  the  clean  metallic  surface  as  evenly  as 
possible,  and  immediately  after  a  finely  powdered  mixture  of  feldspar,  soda,  borax,  and 
oxide  of  tin  is  dusted  over,  after  which  the  enamel  is  burnt  in  by  the  heat  of  a  muffle. 
In  France  an  enamel  is  applied  which  consists  of  a  mixture  of  130  parts  of  flint  glass, 
20 1  parts  of  carbonate  of  soda,  and  12  parts  of  boracic  acid  fused  together  and  afterwards 
ground  to  a  fine  powder.  Enamelled  iron  has  in  some  manufactured  articles  taken  the 
place  of  tinned  iron  or  zinc. 

/3.  Malleable,  Bar,  or  Wrouoht-Iron. 

BSn*.?'2on.  ^  comparatively  olden  times  the  custom  was  to  produce  malleable 
iron  direct  from  its  ores  by  a  process  still  in  use  to  some  extent  in  Styria,  Illyria,  Italy, 
Sweden,  some  parts  of  Asia,  Andorra,  and  other  localities.  The  process  (a  modification 
of  wliich  is  known  as  tlie  Catalan  process)  consists  in  the  reduction  of  the  iron  ores, 
which  must  be  very  rich  and  pure,  by  means  of  charcoal,  which  serves  also  as  fuel  on 
a  hearth,  the  combustion  being  aided  by  a  blast,  often  simply  bellows ;  the  lump  of 
iron  thus  obtained  is  immediately  submitted  to  the  blows  of  a  heavy  forge  hammer. 
Excepting  in  the  few  instances  just  mentioned,  this  process  of  direct  extraction  of  iron 


from  its  ores  has  been  altogether  abandoned,  and  has  given  place  to  the  production  of 
malleable  iron  from  pig-iron ;  the  process  by  which  this  is  effected  is  tenned  refining, 
And  consiats  in  the  removal  of  the  greater  portion  of  the  carbon  and  other  imporitieB 
contained  in  the  crude  meUl  by  oxidation.  The  crude  metal  cliiefly  employed  for 
refining  is  white  pig-iron,  preferably  that  containing  the  least  possible  quantity  of 
cubon,  because  this  kind  of  iron  becomes  soft  before  melting  and  remains  for  a  long 
time  very  fluid,  and  therefore  presents  a  larger  surface  to  oxidising  agents ;  the  chemi- 
cally combined  carbon  of  while  pig-iron  bums  far  more  readily  tlian  the  graphite  con- 
tained in  the  cmde  grey  cast-iron.  The  refining  process  is  executed  eitlier ; — (i)  On 
hearths  |the  German  process) ;  or  (2I  In  reverberator)-  fiimaces  (puddhng  or  English 
process)  ;  In  the  preparation  of  bar -iron  (3)  by  tlie  forcing  of  air  into  the  molten  metal 
(Bessemer  and  other  siniilar  processes).  This  latter  process  is  described  under  Steel. 
°'™"pJSJi?''°'^  '^^  hearth  on  which  this  process  is  carried  out  is  represented  in 
Fig.  8.  The  cmde  iron  is  placed  in  the  cavity  a  of  tlie  hearth,  6,  and  the  metal  is 
brought  to  fusion  in  such  quantity  that  the  molten  mass  has  a  lei^th  of  from  i  to 
i'3  metre,  a  width  of  about  27  ceutims.,  and  a  thickness  of  from  4  to  9  centims.  The 
canity,  a,  is  hned  with  thick  plates  of  fron,  and  the  tuyere,  e,  supplies  the  necessary 
air  from  a  blast  which  is  directed  against  the  molten  metal.  The  hearth  is  ffrst  filled 
with  ignited  charcoal ;  next  the  blast  is  turned  on.  and  tlien  the  crude  metal  is  placed 
on  the  hearth,  b.  and  becoming  gradually  melted,  flows  into  the  cavity,  a.  The  action 
uf  the  blast  causes  the  combustion  of  the  carbonaceous  matter  of  the  metal,  while  the 


sand  adhering  to  the  pigs,  thcsilicadae  to  the  oxidation  of  the  siUeiiuncontsiued  in  the 
cmdeiroD,  andthesilicacontainediu  theashof  the  fuel,  airplay  an  important  part  in 
the  process,  because  these  substances  combine  with  the  protoxide  of  irnn  which  is  pre- 
sent, forminjn  slag,*  compo^d  of  basic  siEcate  of  protoxide  of  iron  lin  100  parts,  68-84 
protoxide  and3i'i6  silical.  This  slag  protects  the  iron  during  the  refining  process,  but 
is  gradually  run  off.  eare  being  taken,  however,  to  leave  a  sufficient  quantity  to  cover  the 
melal.  Mixed  with  for^n-seaiea  (o  mixture  of  prote- and  peroxide  of  iron),  the  slag  of 
the  first  refining  is  employed  in  the  further  refining  process  to  decarbonise  the  iron. 
When  crude  cast-iron  is  heated  to  redness  along  with  tliese  materials,  the  oxygen  con- 
tained in  them  is  given  off,  and  combining  with  the  carbon  contained  in  the  cast-iron, 
forms  carbonic  oxide  and  leaves  malleable  iron.  The  refining  process  also  cansee  the 
moreor  less  complete  elimination  of  such  substances  as  alumininm,  phosphorus,  and 
manganesefrom  the  cmde  metal,  by  convertiog  them  into  alumina,  phosphoric  acid,  and 
protoxide  of  manganese,  all  of  which  are  taken  up  in  the  slag.  As  soon  as  all  the  iron 
has  become  fluid  the  slag  is  run  off  and  the  metal  exposed  to  the  action  of  the  blast. 


22  CHEMICAL  TECHNOLOGY, 

oare  being  taken  to  work  the  metal  about  so  as  to  render  the  action  nniform ;  the 
somewhat  thickish  flnid  mass  becomes  during  decarbonisation  more  and  more  fluid,  and 
the  stirring  up,  or  raising  up,  as  the  operation  is  termed,  is  continued  untQ  the  iron  is 
refined,  which  is  shown  by  the  iad  of  the  slag  becoming  very  rich  in  protoxide  of 
iron.  Towards  the  end  of  the  operation,  the  rich  slag,  Si04,Fe2,  is  formed,  which 
along  with  forge  scales,  is  employed  for  decarbonising  the  metal.  This  rich  slag  is 
never  crystalline  in  structure,  but  exhibits  a  dense  tough  mass  of  higher  specific 
gravity  than  the  raw  slag.  The  operation,  called  the  last  breaking  up  of  the  lump, 
consists,  first,  in  the  rendering  of  the  entire  mass  (the  contents  of  the  hearth)  semi- 
fluid, by  increased  heat ;  and,  secondly,  in  the  separation  of  the  slag  firom  the  metal. 
This  end  having  been  attained,  the  lump,  or  ball,  or  bloom,  is  removed  from  the  fire, 
in  the  red-hot  state,  and  brought  under  the  lift-hammer,  a  (Fig.  9),  which  is  set 
in  motion  by  means  of  a  lifter  and  beam.  By  the  blows  of  the  hammer  all  the 
particles  of  slag  are  squeezed  out  from  the  metal ;  afterwards  the  lump  is  cut  into 
smaller  pieces,  which  are  forged  into  bars ;  100  parts  of  crude  cast-iron  yield  on  an 
average  70  to  75  parts  of  malleable  iron. 

Swedish  Bdflniag  proeeo.  The  Swedish  process  of  iron-refining  (also  called  Walloon-forging 
differs  from  the  German  process,  inasmnch  as  only  small  quantities  of  crude  metal  are 
operated  upon  at  a  time,  while  no  slag  is  added,  the  decarbonisation  being  effected  by  the 
action  of  the  oxygen  of  the  air.  This  process  requires  a  great  deal  of  fuel  (in  Sweden 
almost  exclusively  charcoal),  while  at  the  same  time  a  not  inconsiderable  quantity  of  the 
iron  is  oxidised.  The  malleable  iron  obtained  is,  however,  of  far  better  quality,  being 
denser  and  tougher,  owing  to  greater  purity  and  freedom  from-slag. 

TiM  Paddling  proeeM.  The  proccBS  designated  by  this  name  is  carried  on  in  a  reverbera- 
tory  furnace.  In  countries  where  charcoal  is  scarce,  and  hence  too  expensive  to  be 
applied  to  the  refining  of  iron,  coal  is  used,  and,  indeed,  of  later  years,  has  be- 
come more  generally  employed  on  the  Continent  for  this  purpose.  For,  although 
the  iron  thus  obtained  is  of  inferior  quality  to  that  refined  with  charcoal,  to  the  use  of 
coal  alone  must  the  increase  in  the  production  of  iron  to  the  present  ^lormous 
extent  be  attributed.  Since  coal  contains  sulphur,  direct  contact  with  iron  has  to 
be  avoided,  and  the  operation  is  carried  on  in  a  reverberatory  furnace,  which,  in 

Paddling  Foxnao*.  this  instance,  is  termed  a  puddling  furnace,  represented  in  vertical 
section  in  Fig.  10,  and  in  horizontal  section  in  Fig.  11.  f  is  the  fire-place,  a  the 
puddling-hearth,  and  c  the  flue  along  which  the  gases  are  carried  to  the  chimney. 
The  puddling-hearth,  a,  consists  of  a  square  iron  box,  to  which  air  has  free  access 
from  the  fire-place.  A  layer  of  refining  (puddling)  slag,  to  which  some  forge-scales 
have  been  added,  is  first  placed  on  the  hearth,  and  heated  until  it  begins  to  soften  at 
the  sur£Eu^.  This  point  reached,  the  crude  metal  (by  preference  white  cast-iron)  is 
placed  on  the  hearth  in  quantities  of  from  300  to  350  lbs.  at  a  time  and  heated. 
When  softened,  the  iron  is  spread  evenly  over  the  surface  of  the  hearth  by  means  of 
a  rake  or  stirrer,  and  continually  stirred  about  (puddled),  the  heat  being  greatly 
iucreased.  d  and  e  represent  openings  giving  access  to  the  hearth  for  the  tools, 
capable  of  beiug  readily  closed. 

The  soft  pasty  mass  of  metal  exhibits  on  its  surface  blue  flames  of  burning  carbonic 
oxide,  the  metal  becoming  at  the  same  time  thicker  and  thicker ;  the  slag  which  is 
formed  runs  off  at  b,  and  is  tapped  at  intervals  at  0.  When  the  iron  has  been 
sufficiently  puddled,  it  is  scraped  together  and  formed  into  lumps  or  balls,  which  are 
submitted  to  the  action  either  of  heavy  hammers  or  squeezers,  to  free  the  metal  from 
slag.  Grey  cast-iron,  when  used  for  puddling,  is  first  converted  into  white  cast- 
iron  by  smelting  in  a  reverberatory  furnace,  known  as  the  refining  process. 


ISON.  2j 

^M  theoi7  of  the  pDddling  proMK  is  the  follawing : — The  enrrent  of  air  whioh  oomes 
into  oontoot  with  the  molten  iion  o&nsee  the  formation  of  a  aot  inoonsidereble  qnantitj  ot 
protoparoxiile  of  iron,  the  oxygen  of  whioh  elimtiiat««  the  carbon  ooniained  in  the  pig-iron 
in  the  shape  of  eaibouic  oxide,  whioh  boroi  off  with  a  bloiEh  flune  Tbe  progceaa  of  the 
deaarbooiaation  rendere  the  mase  more  and  more  past;  ;  while,  in  the  interior,  pieoea  of 
mftlleable  iron  are  gradnall;  formed,  whioh,  being  gathered  together  hj  meant  of  the  rake, 
become  looaaly  wtlded,  and  the  iron  not  fnlly  deoarboiueed  nmi  together,  and  being  well 
ataired  np  soon  ondecgOM  the  Mme  ohAUge.    Although  this  rerujut  ot  Uie  puddling  prooess 

FiQ.  lo. 


is  tfaeoretisally  correct,  in  practioe  the  prooesa  la  not  to  limple,  beeaofe — i.  It  Is  seareelj 
possible  to  mix  all  the  esrbon-oontaining  iron  intimately  wiUi  the  protoperoiide,  and,  as  a 
eonseqaence,  some  of  that  oxide  remains  mixed  with  the  iron,  whioh  is  thereby  rendered 
incapable  ol  bejng  welded  (the  iron  loses  eoheeion  and  becomes  of  a  gritty  nature) :  this  sub- 
atanee  has  to  be,  therefore,  removed  by  the  addition  of  coarse  slag,  which  is  thus  converted 
into  refined  slag.  The  oxidation  ot  the  iron  oauses  a  loss  of  some  4  to  5  per  oent.  while  the 
loM  from  tlie  oombnstioD  ot  the  oarbon  amounts  to  a  further  5  per  cent.      1.  The  crude 


iron  ajways  contains  more  or  less  blast- tumaoe  slag  and  adhering  sand  and  dirt  oentaintng 
■iliea.  Daring  the  puddling  process  any  free  eilioa  present  combines  with  the  blaat- 
tornaoe  dag,  and  when  this  slag,  rich  in  silica,  comes  at  the  end  of  the  process  into 
Mntaot  with  protoxide  ot  iron  while  carbon  is  deficient,  a  portion  of  the  giUoa  (or  gilicic 
aoid)  combines  with  the  oxide,  forming  a  slag  which  adheres  to  the  aides  and  bottom  of  the 
hearth,  while  a  basic,  not  easily  fusible  slog  remains  mixed  up  with  tbe  metal.  In  the 
paddling  prooess  the  great  drawback  Is  that  the  complete  removal  ot  the  slag  from  the 
iroa  is  praetioally  impossible ;  at  least,  such  has  been  the  case  hitherto.  That  iron 
prepared  in  this  way,  which  may  even  contain  two  or  more  per  cent  of  such  slag,  is  some- 
times luittle  and  cold-short  is  not  to  be  wondered  at. 


24  CIlEillCAL  TECHNOLOGY. 

Hniiini  with  oiM.  Instead  of  emplojing  coal  or  coke  as  fnei,  the  reverberatorj  famftoes 
arc  often  heated  ^ith  oombnutible  ganes  eEoaptng  from  the  blaet-fnmaoeB  or  vith  gas  made 
for  the  pnrpoBO  m  a  geDerator — on  arroDgement  not  unlike  a  coke-oTon,  in  which  aneh 
refuse  fuel  aa  cannot  be  othemise  ntilined,  viz.,  waste  of  timber-yarda,  refuse  charcoal, 
peat,  and  small  coal,  ie  submitted  to  dr;  distillatioD.  The  generator  is  oonneeted  to  the 
ceverberatory  fnmace  in  such  a  manner  that  the  gases  evolved  in  the  former  reaeh  the 
latter  very  highly  heated.  Foraome  jeara  Siemene's  regencrator-fumaoe  has  l>een  applied 
to  this  purpose,  and  found  to  anrpaes  all  ether  arrangements  of  the  kind.  When  erode 
pig-iron  oontaina  much  phosphorus,  that  element 
may  bo  eliminated  daring  the  puddling  prooeaa  by 
adding  to  the  metal  a  mixture  of  mangmeae, 
common  salt,  and  clay,reduoed  to  powder.  Solphiir, 
when  present,  may  be  burnt  off  by  adding  Uthlrge  ; 
steam  has  also  been  used  suocesafally  for  this  latter 
purpose. 

S;^^!™,";  The  metal  obtained  by  the 
puddling  procesa  ia  submitted  to  beavy  hammer- 
ing or  to  squeezers  in  order  to  remove  as  mach 
mechanically  adhering  slag  ns  poaaible :  aUfa 
this  it  is  ready  for  the  operations  carried  ont 
BoUiDtiraii  in  the  rolling  mill  (Fig.  la)  which 
consists  in  the  main  of  the  following  parts : — b  b' 
and  K  a'  are  grooved  rollers  made  of  chilled  cast^ 
iron :  A  a'  are  destined  for  shaping  flat  bars,  and 
B  B ,  for  the  shaping  of  square  bars  ;  bymeana  of 
the  nuts,  o  o.  the  position  of  the  rollers  towards 
each  other  can  be  regulated  ;  the  tubes,  i  i,  carry 
water  for  keeping  cool  portions  of  the  machinery. 
The  contrivance  m  n  serves  to  connect  or  dis- 
connect the  rollers  from  the  steam  engine  or 
water-wheel  from  which  is  obtained  the  motive 
power :  the  cog-wheels  f  and  £  impart  motion  to 
the  cog-wheels  f'  and  c'  connected  with  the  npper 
rollers  a'  and  a',  which  are  thus  made  to  move  in 
Uie  opposite  direction  to  the  under  rollers.  The 
metal  to  be  rolled  is  first  roughly  shaped  by 
means  of  heavy  hammers  (steam  hammers  are 
now  often  used),  and  then  passed  gradually 
through  tlie  varionsly  sized  grooves  of  the  rollers. 
Fig,  13  exhibite  rollers  of  a  peculiar  construction, 
viz.,  steel  rings  or  discs  wedged  to  iron  shafting 
so  as  to  form  alternately  large  and  small  groovee 
for  the  manufacture  of  thin  bars  of  iron,  such  as 
naU-rods,  &c. 

A  variety  of  rolled  iron  objects  are  made  ; 
among  these,  square  and  flat  bars,  round  bars. 
T-pieces,  angle-iron,  hoop-iron,  and  n&il-rods; 
railroad  rails  constitute  an  important  item. 
Boii«pw.BnUia,.  The  rolling  of  boiler-  and  armour-plate  is  an  isolated  branch,  dnce  it 
requires  a  metal  of  good  qaality.  combining  softness  with  toughness,  and  capable  of  being 
worked  far  below  red  heat  without  becoming  too  brittle  or  requiring  annealing  too  often  ; 
(or  boiler-  and  armonr-platcs  the  metal  is  formed  into  slabs  of  proper  size,  which,  while 
nearly  white-hot.  are  forced  through  the  rollers.  After  each  succeeding  passage  of  the 
slab,  the  rollers  are  set  tighter,  the  oiide  (forge  scale)  which  is  formed  c 


1  the  surface  of 


inoN. 


as 


the  meUl  U  removed  by  bnubicg  with  wet  coarsdj-nutde  heather  brashea.  Thin  sheet- 
iron  is  rolled  oat  from  plate-iron  oDt  into  ansM  slabn,  which  are  at  first  hot,  bat  at  a  later 
it^e  of  the  operation  the  rolling  is  performed  cold,  the  metal 
having  been  prerionHly  annealed  in  properly  conetructed 
lonwcea.  Under  the  headings  of  Zinc  and  "Kn  the  galvaniaiog 
and  the  tinning  of  iron  ore  treated  of ;  corrugated  :' 
made  bj  pecnliarl;  shaped  and  gcooved  rollerB. 

iiOT  wir»  Thedrawingoliionintowirereqairesparticalarly  , 

KuDfuUm.  tou((h  and  fibroQS  metal.  In  former 
wire  vaa  mode  by  drawing  thin  oircnlarbara,  by  the  aid  of  tongs,  I 
through  holee  made  in  steel  plates;  in  the  present  day  ir~ 
wire,  if  stoat,  is  made  with  rollers,  while  the  thinner  wire 
made  with  machinery  to  be  presently  described.  The  rulling- 
mili  for  the  drawing  of  iron  wire  ap  to  a  diameter  of  aboat  i  of 
an  incb  eongistE  of  three  rollers  provided  with  grooves  which  correspond  to  and  catch  a  bar 
of  iron  when  placed  between,  the  bar  being  tbna  sqaeened  in  the  grooTes  ;  these  rotlera 
make  240  revolutions  a  minnte,  and  since  the  diameter  is  8  inches  their  circomferential 
Telocity  is  =8'37  feet,  or  in  other  words  8  feet  4J  inches  of  wire  paaa  through  the  rollers 
in  a  second  of  time ;  thinner  wire  is  obtained  by  drawing,  with  the  aid  of  machinery,  the 
itonter  kinds  of  wire  thioagh  holes  made  in  hard  and  nnchangeable  materials,  the  size 
of  these  holes  gradually  decreasing.  For  this  pnrpose  the  previounly  annealed  wire,  from 
)  to  ^igth  of  an  inch  diameter,  is  wound  on  the  reel,  «  fFig.  14) ;  the  end  ol  the  wire  shaped 
somewhat  to  a  point  is  pntthrongh  the  bole  made  in  the  draw-plate,  b  ;  this  hole  being  of  a 
■lightly  less  diameter  than  that  of  the  wire,  which  is  next  fastened  to  the  hook,  c  (Fig,  ij), 
of  the  oonically-ahaped  dmm.  c,  which  acquiies  a,  rotatory  motion  from  the  main  shaft,  d 
(Fig.  14)  ,by  means  of  conically-shaped  cog-wheels,  an  arrangement  being  provided  to  oonneot 


1  F,o.  ,3. 

i4t 


or  disconnect  the  apparatns  from  the  steam  engine,  so  as  to  atop  or  set  in  motion  the 
wire-drawing  machinery  without  stopping  the  ateam  engine.  The  ahape  of  the  holes  in 
the  draw-plate  la  ol  the  highest  importance  for  the  nacceBs  of  tbe  operation,  and  to  obtain 
periectly  round  wire  the  holes  ought  to  be  quite  true ;  if,  however,  the  holes  were  made 
perfect  cylindera  throngh  the  entire  thickness  of  the  draw-plates  the  ceanlt  would  be  that 
the  wire,  instead  of  suddenly  dT"^iniHhing  in  size,  would  break  ;  on  that  account  the  holes 
are  boied  funnel-shaped.  The  draw-plate  is  made  of  steel,  but  for  very  thin  wire  hard  gems 
properly  fastened  and  pierced  are  employed.  Iron  wire  has  to  be  repeatedly  annealed 
during  the  process,  and  since  hj  this  annealing  operation,  unless  carried  on  with  complete 
nclasion  of  air.  a  layer  of  oiide  of  iron  is  formed,  tbe  wire  requires  treatment  in  what  is 
technically  termed  a  scour  hath,  composed  of  dilate  snlphuric  acid  and  a  certain  amount 
of  Bniphate  of  copper ;  the  thin  layer  ol  copper  deposited  on  (he  wire  during  the  immersion 
in  this  bath  lessens  the  friction  on  the  wire  in  passing  through  the  holes.  The  thinnest 
iron  wire  met  with  in  the  trade  baa  a  diameter  ol  only  ^igtb  of  an  inch,  and  is  known  as 
piano  wire.  Iron  wire  is  rendered  soft  by  being  heated  to  redness,  and  is  protected  from 
ruMing  by  inunersioa  in  a  bath  of  molten  zinc,  so-called  galvanising.  The  nsee  to  which 
iron  wire  is  applied  are  so  varied  that  it  is  Bcaroely  posaibU  to  enumerate  them;  this  is 


26  CHEMICAL  TECHNOLOGY, 

the  lees  naoeesary  as  m  no  oonntry  in  the  world  is  iron  wire  so  largely  used  as  in  the 
United  kingdom,  especially  instead  of  hemp  for  rope-making. 

Prope^Mof  Malleable-  or  bar-iron  is  made  up  of  an  aggregation  of  fibres  which, 

according  to  the  researches  of  Dr.  Fuchs,  are  composed  of  a  series  of  very  small 

crystals.    Heavy  blows,  continuous  vibration,  and  sudden  cooling  of  the  metal  while 

red-hot,  all  cause  the  particles  to  lose  cohesion  and  alter  the  texture  from  fibrous  to 

granular:  a  well  known  consequence  of  this  change  of  structure,  which  is  also 

suddenly  induced  by  great  cold,  is  the  loss  of  tenacity  in  the  iron,  often  attended  with 

breakage,  as  happens  frequently  enough  to  railway  wheel-tyres,  axles,  &c.  The  colour 

of  malleable  iron  is  bright  grey,  the  firactore  granular  or  jagged ;  its  specific  gravity 

varies  from  7*6  to  7*9  (that  of  chemicaQy  pure  iron  being  7*844) ;  from  0*24  to  0-84  per 

cent  of  carbon  is  present  in  the  iron,  the  greater  part  in  a  state  of  chemical  combination, 

in  fact  there  is  only  a  trace  of  graphite. 

The  chemical  constitution  of  malleable  iron  is  shown  in  the  following  analytical 
results : — Sample  I.  being  English  iron  from  South  Wales ;  11.,  soft  iron  from  Magdespmng 
«n  the  Harz  (Fruamsk) ;  TO.,,  Dannemora  iron  from  Sweden. 

I.  n.  m. 

Iron 98*904  98-963  98775 

Carbon     0*411  0*400  0*843 

Silioium 0*084  0*014  0-118 

Manganese      ••     ..  0*043  0*303  0*054 

Ck>pper      nil  0*320  0-068 

Phosphorus     ..     ..  0*041  nil  nil 

Malleable  iron  of  good  quality  does  not  become  brittle  when  placed  red-hot  into  cold  water; 
it  ought  not  to  lose  its  malleability  when  thus  treated :  it  is  far  softer  than  white  and 
bright  grey  cast-iron,  and  is  therefore  easily  filed,  cut  with  the  cold  chisel,  planed,  and 
shaped  in  various  ways  even  cold ;  it  melts  with  far  more  difficulty — ^requiring  a  much  higher 
temperature — than  cast-iron ;  but  malleable-iron  is  possessed  of  the  valuable  property  of 
becoming,  at  a  bright  red  heat  (orange  heat),  so  soft  as  to  admit  of  two  pieces  being  firmly 
welded  together.  The  malleable-iron  of  commerce  is  often  more  or  less  mixed  with  foreign 
substances  which  in  some  cases  impair  its  quality ;  if  sulphur,  arsenic,  or  copper  is  present, 
the  iron  is  thereby  rendered  red-short  (breaks  when  hammered  in  the  red-hot  state) ; 
silioium  renders  iron  hard  and  brittle ;  phosphorus  makes  it  cold-short,  t.«.,  rather  readily 
breakable  when  cold,  although  not  so  when  red-hot ;  calcium  has  the  effect  of  greatty 
impairing,  if  not  altogether  destroying,  the  welding  capability  of  the  metal.  As  regards 
the  choice  of  the  different  qualities  of  malleable  iron  for  various  uses,  it  is  not  in  the  scope 
of  this  work  to  enter  into  detail,  the  question  being  one  of  applied  mechanics  and 
engineering  rather  than  of  chemistry.  Swedish  bar-iron  is  for  certain  purposes  in  high 
repute,  owing  to  the  purity  and  strength  of  this  kind  of  iron. 

y.  Stsel. 

stML  This  substance  diSexB  from  crude  pig-iron  and  from  bar-iron  in  the  amount  of 
carbon  it  contains;  from  crude  iron,  moreover,  by  being  capable  of  welding;  and  again 
from  bar-iron  by  being  comparatively  readily  fusible :  in  reference  to  the  amount  of 
carbon  present,  steel  holds  a  position  between  crude  pig-iron  and  bar-iron.  Recent 
researches  have  revealed  the  fiict  that  steel  contains  nitrogen ;  but  whether  this 
element  really  contributes  to  the  peculiar  properties  of  steel  obtained  from  different 
sources  is  not  a  definitely  settied  point.  Steel  is  obtained  of  various  qualities  by  a 
number  of  processes,  as  will  be  seen  in  the  following  brief  reference : — 
a.  DirecUy  from  iron  ores : — 

1.  By  the  reduction  of  iron  ores  direotiy  with  the  aid  of  fuel  (chiefly  diarcoal),  and  a 
blast  on  the  hearth,  the  steel  hemg  obtaiued  in  the  form  of  lumps  (so-called 
natural  steel]. 

2.  By  the  heating  of  certain  iron  ores  along  with  coal,  but  without  fusion  (cementation 
steel  from  ores). 

3.  By  the  fuaon  of  the  iron  ores  along  with  charcoal  in  omoibles  (oast-steel  from  ores). 


IRON.  27 

h.  By  the  partial  deoarboniflation  of  pig-iron  (rongh  steel,  fomaoe-steel,  or  German-steel) : — 

4.  By  the  refining  (partial  decarbonisation)  of  pig-iron  by  means  of  eharooal  fuel  on 
the  hearth  (shear-steel). 

By  treating  pig-iron  in  reyerberatoiy  fomaees  fed  by  ooal  or  blast-fnmaoe  gases 
as  fnel  (padcUed-steel). 

6.  By  forcing  air  through  molten  cast-iron  (Bessemer-steel). 

7.  By  heating  oast-iron  to  redness  along  with  substances  which  will  effect  decarboni- 
sation below  the  fasion-point  of  the  metal ;  if  the  sabstances  employed  for  partial 
decarbonisation  are  iron  ores,  the  steel  is  called  iron  ore  steel. 

8.  By  melting  crude  oast-iron  with  such  substances  as  those  just  mentioned. 

9.  By  treating  crude  cast-iron  with  sodium  nitrate  (Heaton-steel,  Hargreave-steel). 

e.  By  imparting  carbon  to  bar  or  malleable-iron : — 

10.  By  ignition  with  carbonaceous  matter,  but  without  fusion  (cementation-steel.) 

11.  By  fusion  with  charcoal  (cast-steel). 

d.  By  combination  of  methods  h  and  e,  as  in  fluxed  steel : — 
II.  By  melting  crude  pig-iron  and  malleable-iron  together. 

In  India  a  kind  of  steel  is  still  made  directly  from  iron  ores,  and  known  as  woots  (as  to 
the  composition  of  this  substance,  see  the  **  Chemical  News,"  vol.  xzii.,  p.  46) ;  it  is  possessed 
of  excellent  qualities.  The  Japanese  also  understand  the  art  of  malong  steel  of  most 
excellent  quidity  by  rather  rough  and  primitiye  means.  According  to  the  modes  of 
manufacture,  we  distinguish  the  following  kinds  of  steel : — 


This  material,  obtained  by  the  partial  decarbonisation  of  orude  pig-iron, 
may  be  either : 

I.  Bough  steel  made  on  a  hearth  (natural  steel),  chiefly  obtained  from  the  pure 
spathic  iron  ore,  from  which  in  Styria,  Carinthia,  l^rol,  and  various  other  parts, 
porous  white  pig-iron,  or  white  pig-iron,  with  granular  structure,  is  first  obtained  by 
means  of  charcoal  and  coke  as  fuel ;  the  ordinary  grey  cast-iron  can  also  be  used,  biit 
the  resulting  steel  is  not  of  such  good  quality.  The  general  arrangement  of  the 
hearths  on  which  rough  steel  is  made  is  the  same  as  for  the  operatioH  of  iron  refining ; 
the  only  diffiorence  is  in  the  mode  of  placing  the  metal  in  reference  to  the  blast,  the 
operation  being  so  conducted  as  to  cause  only  the  gradual  combustion  of  the  carbon : 
the  workmen  take  care  to  control  the  blast  and  place  the  metal  in  a  manner  which 
enables  them  to  stop  the  further  action  of  the  air  the  momeiLt  the  proper  amount  of 
decarbonisation  has  been  effected. 

a.  Steel  obtained  in  a  reverberatory  furnace,  or  puddled  steel ;  obtained  from  various 
kinds  of  cast-iron  by  a  process  akin  to  the  puddling  of  crude  cast-iron,  the  burning  off 
of  the  carbon  not  being  carried  so  far.  This  mode  of  manufacturing  steel  is  exten- 
sively employed,  and  yields  a  material  well  suited  for  the  making  of  various  kinds  of 
machinery,  railway  carriage-wheel  tyres,  and  is  also  largely  used  in  the  manufacture 
of  cast-steeL 

Syrian  and  Carinthian  cast-steel  (charcoal  iron-steel)  is  far  more  expensiye  than 
pad Jled  steel,  but  the  former  is  indispensable — at  least  on  the  Continent — ^for  the  manu- 
facture of  all  kinds  of  cutting-tools. 

3.  Beesemer-steeL    Mr.  Henry  Bessemer,  in  1855,  first  applied  a  process  of  making 

steel  directly  from  cast-iron ;  the  process  consists  in  forcing  large  quantities  of  air 

through  molten  crude  iron ;  the  consequence  is  that  the  conversion  cf  the  iron  into  steel  is 

effected  in  a  comparatively  brief  space  of  time ;  moreover,  the  resulting  steel  remains 

fluid ;  the  difference  of  the  action  of  the  air  as  an  oxidising  or  decarbonising  agent  in 

this  instance,  as  compared  with  the  process  of  steel-making,  mentioned  under  No.  i 

and  2,  is  that  in  the  case  of  the  Bessemer  method,  the  air  thoroughly  penetrates  and 

comes  into  contact  with  every  particle  of  iron ;  whereas,  in  the  other  instances,  the 

action  of  the  air  is  only  at  the  surface ;  and  since  the  steel  obtained  by  methods 


28  CHEMICAL  TECHNOLOGY, 

I  and  2  is  less  fusible  than  the  crude  iron  used,  a  second  refining  or  smelting  becomes 
necessary  to  render  the  steel  uniform  and  homogeneous. 

The  Bessemer  process  is  executed  either  in  diminutive  shaft-ovens  or  in  egg-shaped 
vessels  made  of  boiler-plate  converters,  and  lined  with  fire-claj ;  projecting  for  some  inches 
through  the  inside  of  the  bottom,  five  gth  inch  wide  fire-clay  tubes  are  carried,  through 
which  powerfully  compressed  air  can  be  forced.  The  apparatus  is  placed  in  close 
proximity  to  a  blast-furnace,  so  as  to  admit  of  running  the  molten  iron,  purposely  kept  at 
a  very  high  degree  of  heat,  readily  into  the  oven  or  other  vessel,  while  at  the  bottom  of  the 
converter  there  is  an  aperture  closed  with  a  fire-clay  plug,  through  which  the  molten  steel 
can  be  discharged.  As  soon  as  the  blast  is  turned  on  and  the  vessels  half  filled  with 
molten  iron,  a  very  violent  action  ensues,  the  metal  apparently  begins  to  boil,  flames  and 
myriads  of  sparks  burst  forth  from  the  converter  (this  phenomenon  appears  to  be  due  to 
the  fact  that  particles  of  partly -decarbonised  iron  and  a  mixture  of  iron  and  oxide  are 
driven  against  each  other).  According  to  the  duration  of  the  action  of  the  blast  (lo  to  25 
minutes),  steel  or  bar-iron  may  be  made,  and  of  late,  even  in  making  steel,  the  action  is 
carried  to  the  highest  possible  pitch,  and  to  the  resulting  metal  a  portion  of  molten  white 
pig-iron  is  added.  Bessemer  steel  is  largely  used  for  a  variety  of  purposes ;  but  it  is  not 
suitable  for  the  manufacture  of  such  cutting-tools  and  instruments  as  require  a  keen  and 
durable  edge ;  on  the  other  hand,  Bessemer  metal  is  an  excellent  material  for  the  manu- 
facture of  boiler  and  armour-plates,  ordnance,  railroad-rails,  and  a  great  variety  of  heavy 
machinery.  As  might  be  expected,  this  method  of  steel-making  has  rapidly  spread  from 
England  to  all  parts  of  Europe  and  to  America ;  and  as  a  proof  of  the  handsome  profit 
earned  by  the  inventor,  whose  royalty  amounts  to  is.  per  cwt.,  we  may  state  that  the  total 
quantity  of  Bessemer  steel  produced  in  Europe  in  the  year  1869  amounted  to  5'5  millions 
of  cwts.,  70  per  cent  thereof  being  produced  in  Great  Britain. 

4.  Uchatius  and  Martin  steel  are  also  directly  prepared  from  crude  cast-iron,  by  mix- 
ing granulated  crude  pig-iron,  made  from  native  magnetic  iron  ore,  along  with  pul- 
verised spathic  iron  ore  and  fusing  this  mixture  in  plumbago  crucibles.  M.  Martin 
replaced  the  use  of  the  crucibles  in  this  process  by  that  of  the  somewhat  hollow  floor 
of  a  reverberatory  furnace  heated  by  means  of  a  Siemens's  regenerative  gas-furnace. 
A  quantity  of  crude  pig-iron  is  melted  under  a  layer  of  slag,  and  from  time  to  time 
bar-iron  is  added  until  a  sample  taken  out  is  found  to  possess  the  texture  and  good 
qualities  of  malleable-iron.  When  this  stage  has  been  reached,  a  certain  amount  of 
crude  cast-iron  is  added,  whereby  the  entire  quantity  of  metal  is  converted  into  a  kind 
of  cast-steel,  chiefly  suited  to  the  making  of  railroad-rails,  wheel-tyres,  and  especially 
gun-barrels  and  ordnance.  Tunner's  steel,  which  dates  from  1855,  also  known  as 
malleable  cast-iron,  is  obtained  by  igniting  white  pig-iron  to  bright  redness  with 
substances  which  give  off  oxygen  (oxides  of  iron  and  zinc  and  peroxides  of  man- 
ganese) when  thus  treated. 

5.  Heaton  steel.  Prepared  by  a  process  devised  by  Mr.  Heaton,  in  which  crude- 
iron  is  heated  with  nitrate  of  soda  (Chili-saltpetre).  By  this  method  not  only 
the  carbon  is  eliminated,  but  the  sulphur  and  phosphorus  being  oxidised  and  con- 
verted into  phosphates  and  sulphates,  find  their  way  into  the  slag.  Tlie  principle  of 
this  method  is  the  same  as  in  Mr.  Hargreaves's  plan,  and  again  identical  with  a  pro- 
posed new  method  of  Bessemer  steel-making. 

^ou^it^^rS^SSS^  ^  The  second  kind  of  steel  is  that  known  as  cementation- 
steel — a  metal  prepared  by  the  ignition  of  bar-iron  in  contact  with  carbonaceous 
matter,  preferably  containing  nitrogen.  The  bar-iron  to  be  employed  for  this 
purpose  should  be  of  the  very  best  quality,  and  since  in  Great  Britain  and  France, 
the  best  iron  produced  is  not  good  enough,  both  these  countries  draw  largely  upon 
Sweden  for  a  supply  of  Danncmora  iron,  made  from  magnetic  and  red  hsBmatite-iron 
ores  mixed.  The  Russian  iron  from  the  Ural  is  of  the  same  good  quality,  but  the 
transport  is  at  present  far  too  costly.  It  is  almost  superfluous  to  mention  that  the 
chief  seat  of  the  steel  manufacture  in  England  is  Sheffield. 


IRON,  29 

The  process  of  making  cementation-steel  is  simple  enongh.  The  hars  of  lion  are  placed 
in  fire-clay  boxes,  in  layers  alternating  with  the  carbonaceous  matter  (cementation- 
powder).  Two  of  such  boxes  are  placed  in  a  furnace  which  is  heated  with  coal,  and  the 
boxes  are  kept  at  a  red  heat  for  some  six  or  seven  days,  and  after  cooling,  the  bars,  con- 
Terted  into  steel,  are  taken  out.  Each  furnace  contains  from  300  to  350  cwts.  of  iron.  In 
the  cementation-powder  such  substances  as  will  form  cyanide  of  potassium,  or  ready- 
formed  cyanides,  ought  to  be  present.  It  appears  from  recent  researches  that  cyanogen 
(CN)  is  to  be  viewed  as  the  carrier  of  the  carbon  to  the  metal.  The  crude  steel  (blistered- 
steei)  obtained  by  this  operation  is  not,  as  such,  fit  for  use,  but  has  to  undergo  a  process 
of  purifying. 
Befined-3t««L  Not  Only  cemontatlon-steel,  but  also  that  obtained  by  the  other  methods,  is 
sfacar-atML  (oo  coarso  and  not  sufficiently  homogeneous  for  immediate  use,  and  therefore 
a  process  of  refining  has  to  be  resorted  to.  This  process  consists,  firstly,  in  the  hammering 
out  of  of  the  steel  bars,  previously  made  red-hot,  into  thin  rods,  which  are,  while 
red-hot,  quenched  with  cold  water.  Next  a  number  of  these  are  placed  together  in  the 
form  of  a  bundle,  which  is  again  made  red-hot,  well  hammered,  and  afterwards  rolled  into 
bars.  The  method  of  refining  here  alluded  to  is  more  suited  to  the  quality  of  steel 
obtained  from  crude  pig-iron  than  to  cementation-steel.  Sfceel  thus  refined,  on  account  of 
being  used  for  making  large  pairs  of  scissors  or  shears,  bears  the  name  of  shear-steel. 

ohM^ueL  Cast-steel,  in  modem  industry,  has  assumed  a  most  enormous  importance, 
as  e\idenced  by  such  gigantic  works  as  those  of  M.  Krupp,  at  Essen  (Prussia).  The 
eiustence  of  these  works  notwithstanding,  Sheffield  takes  the  foremost  rank  in  the 
manufacture  of  cast-steel.  The  following  is  the  plan  pursued : — The  bars  of  blistered- 
Bteel,  cut  to  a  convenient  size,  are  introduced  into  crucibles  made  of  Stourbridge  clay, 
which  are  heated  in  furnaces  similar  to  glass-melting  ovens,  fed  mth  coke  or  coal  as 
fuel ;  the  molten  metal  is  cast  into  bar-shaped  moulds,  and  the  bars  are,  after  cooling, 
again  heated  to  redness  and  hammered  or  rolled  out  in  a  mill.  As  to  the  uses  to 
which  cast-steel  is  applied,  suffice  it  to  say  that  heavy  ordnance,  as  well  as  large 
bells,  excellent  cutting-tools  and  files,  best  cutleiy,  and  many  surgical  instruments, 
number  among  them.    Cast-steel  is  homogeneous,  and  therefore  strong  and  durable. 

^'tid&tt^clrtJSS!****  •^-  ^  third  kind  of  steel  (varying  accordiug  to  the  mode  and 
materials  of  production)  is  that  called  Glicenti-steel,  obtained  by  melting  together  a 
peculiar  white  pig-iron  (spiegel-iron),  and  bar  or  malleable-iron.  The  toughness, 
hardness,  and  malleability  of  this  metal  depend  upon  the  quantity  of  bar-iron  which 
has  been  added  to  the  mixture. 

BiBfkee  stMi-Hatdening.  It  frequently  happens  that  for  certain  purposes  soft  iron  only 
requires  to  be  converted  into  steel  superficially,  an  operation  termed  surface-harden- 
ing or  surface-steel  hardening,  which  is  done  by  placing  the  metal)  previously  polished 
with  emery,  in  a  suitable  vessel  covered  in  cementation-powder  (see  above) ;  the  vessel 
and  contents  being  next  heated  to  redness,  malleable  iron  tools,  spanners,  for  instance, 
keys,  and  small  objects,  may  be  readily  surface-hardened  by  being,  while  red-hot, 
dusted  over  with  powdered  ferrocyanide  of  potassium,  yellow  prussiate,  or  with  pul- 
verised borax  and  pipe-clay. 

PnptftiMof  steeL  The  colour  of  steel  is  bright  greyish-white,  its  texture  is  imiformly 
granular,  the  better  the  quality  the  smaller  the  grain.  Sound  soft  (that  is  not 
hardened)  steel,  never  exhibits  the  coarse  texture  characteristic  of  crude  cast-iron,  nor 
the  fibrous  texture  of  bar-iron.  Hardened-steel  exhibits  a  fracture  very  similar  to 
that  of  the  finest  silver,  so  close  that  the  granular  texture  can  hardly  be  detected  with 
the  naked  eye.  When  red-hot,  steel  is  nearly  as  readily  malleable  as  bar-iron,  and 
may  be  welded,  but  very  careful  management  is  required  to  prevent  its  becoming 
decarbonised.  By  inmiersing  a  piece  of  steel  in  dilute  hydrochloric  or  nitric  acid,  the 
texture  of  the  metal  becomes  apparent,  and  tills  test  may  be  applied  to  deteimine  the 
quality.    The  specific  gravity  of  steel  varies  from  762  to  7*81,  and  decreases  in 


30 


CHEMICAL   TECHNOLOGY. 


hardening  (for  instance,  from  7*92  to  7*55) ;  the  quantity  of  carbon  contained  in  steel 

varies  from  o'6  to  1*9  per  cent ;  the  toughness,  tenacity,  and  hardness  of  steel,  increase 

with  the  quantity  of  carbon  it  contains,  but  good  steel  never  contains  graphite ;  the 

high  degree  of  elasticity  exhibited  by  good  steel  decreases  with  the  hardness.    When 

red-hot  steel  is  suddenly  quenched  with  cold  water,  the  metal  becomes  &r  harder,  but 

also  brittle,  and  will  even  scratch  glass  and  withstand  the  file;   when  brightly 

polished,  if  steel  is  gradually  heated,  it  assumes  peculiar  shades  of  colour  (annealing 

or  tempering  colour).     This  colouration  is  due  to  the  formation  on  the  surface  of  the 

steel  of  thin  layers  of  oxide,  which  exhibit  colours  like  other  very  thin  surfaces — soap 

bubbles,  for  instance,  or  a  drop  of  oily  or  tarry  matter  extended  over  water.    The 

operation  which  causes  the  formation  upon  steel  of  these  colours  is  called  tempering. 

T«mp«iiag.      In  judging  the  proper  temperature  and  the  corresponding  hardness  these 

tints  serve  admirably.     Since  it  is  often  rather  difficult  to  heat  a  piece  of  steel 

uniformly,  molten  metallic  mixtures  are  employed,  beiDg  chiefly  made  up  of  tin  and 

lead ;  the  bright  hardened  steel  is  kept  in  these  molten  mixtures  until  it  has  assumed 

the  temperature  of  the  bath.    The  following  tabulated  form  exhibits  the  composition 

of  the  metallic  baths,  which  experience  has  proved  to  be  the  best  for  the  tempering  of 

cutlery : — 

Ck>mpoBition  of     Melting 
metallic  mixture,    point. 


Temperature. 


I  iftfioeiio    ••.     ...  •••     ••• 

fUkzors     .••     ...  •••     ••• 

Pen-knives 

Pairs  of  scissors  

Clasp-knives,  joiners'  andi 
carpenters' tools j 

Swords,  cutlasses,  watch-  j    ^ 
springs        j  ^ 

Stilettos,  boring-tools,  and 
fine  saws     


Pb. 
7 


8 
8i 

19 


Sn. 

4 

4 
4 
4 


Ordinary  saws 


50  2 

inboilin^\ 
linseed-ou  J 


2ao* 
228° 
232° 

254^ 
265^ 

288** 

292** 
316' 


Hardly  pale  yellow. 
Pale-yellow  to  straw-yeUow. 
Straw-yellow. 
Brown. 

Purplish-coloured. 

Bright-blue. 

Deep  blue. 
Blackish  blue. 


Such  tools  as  are  required  to  work  iron  and  other  metals  and  hard  stones  are 
heated  to  bright-yellow ;  razors,  surgical-instruments,  coining-dies,  engravers' -tools, 
and  wire-drawing  plates  follow  next  to  straw-yellow ;  caipenters'-tools  to  purphah- 
red ;  while  such  tools  and  objects  as  are  required  to  be  elastic  are  heated  to  the  violet 
or  deep-blue  tint;  the  less  steel  is  heated  the  harder  it  remains,  but  also  the  more  brittle. 
Other  substances  than  carbon  (for  instance,  silicon  and  boron)  maybe  capable  of 
imparting  to  iron  properties  sioiilar  to  those  we  are  acquainted  with  in  steeL     Some 

o£?iiSds.  0^^^  metals  mixed  with  steel  in  greater  or  lesser  quantity  improve  the 
quality  in  some  respects ;  for  instance,  for  the  last  few  years  steel  has  been  made  in 
Styria,  which,  owing  to  its  containing  tungsten,  is  exceedingly  tough  and  hard. 

^y^^Si^  ^^^^^  Bteel,  specially  celebrated  for  making  swords,  was  first  made 
at  Damascus.  Its  name,  Damascene,  is  appUed  to  the  property  it  possesses  of 
exhibiting  a  peculiar  appearance  when  acted  upon  by  an  acid;  but  tbis  appears  to  be 
due  rather  to  some  imperfection  of  the  welding  of  the  metal,  since,  after  melting,  the 
same  peculiar  shades  of  colour  do  not  appear.  We  have  already  alluded  to  the  recent 
researches  concerning  the  true  composition  of  this  metal.    One  of  the  largest  collec- 


IRON.  31 

tioDB  of  toolB,  swordB,  gun-barrels,  and  bars  of  this  kind  of  steel  to  be  found  in  Europe 
IB  in  the  India  Museum,  Whitehall.  -  In  order  to  elucidate  the  composition  of  some 
kinds  of  steel,  the  following  analyses  are  appended: — The  samples  are — i.  Befined 
steel,  from  Siegen  (Prussia) ;  2.  Cast-steel,  from  Schmalkalden  (Prussia) ;  3.  Puddled- 
steel ;  4.  Steel  from  Russian  cast-ordnance ;  5.  Cementation- steel,  Elberfeld  (Prussia) ; 
6.  English  cementation-steel ;  7.  Krupp's  steel  (Essen). 

|.  2.  3'  4'  5'  fi'  7- 

Iron 97*91    93*154    98602    9875    99'oi    99*12    99*351 

Carboal^Sl       ...      169      ^'7J°     P^      ^'^     °*Jl    rS?      0-532 
1C/3J  ^      0010      trace      015      o"o8j         '       "oo* 

Silieium       0*03  0202  o*oo6  0*04  —  cio  0*032 

Sulphur       trace  0003  —  —  —  —  o'ooi 

Phosphorus —        —  trace  —  —  —  o'ooi 

Manganese —        —  o'oi2  —  —  —        — 

Copper o'37        —  —  —  —  —        — 

loo'oo  loo'ooo  100*000  loo'oo    99*50    101*09  99*917 

flUemrmpiiyorstMi  The  eugrayiug  of  steel  requires  plates  made  of  cast-steel,  which,  in 
Kagnvinc.  order  to  be  sufficiently  soft  for  the  engrayer's  tools,  are  first  superficially 
deearbonised,  and  after  the  engfaying  is  made,  again  hardened.  The  engraved  plate  is 
not  employed  direct  for  printing,  but  is  used  as  a  matrix  for  the  preparation  of  plates  to 
be  printed  from ;  this  process  is  carried  out  In  the  following  manner : — ^A  solid  cast-steel 
cylmder,  turned  in  a  lathe,  is  superficially  softened,  f^d  the  engraved  plate  is  placed 
imder  this  cylinder,  so  that  with  great  pressure  and  a  slow  revolutioo  of  the  cylinder,  the 
plate  moving  also  very  slowly,  a  relief  of  the  engraving  is  produced  on  the  cylinder,  and 
this  being  again  hardened,  is  employed  to  reproduce  the  engraving  on  other  metallic 
plates,  w£dch  may  be  either  copper  or  soft  steel.  Instead  of  engraving  the  design  on 
soft  steel  plates,  etching  is  often  resorted  to,  for  which  purpose  corroding  fluids,  such  as 
nitric  ,acid  (aquafortis),  nitrate  of  silver,  sulphate  of  copper  in  solution,  or,  lastly,  a 
aolation  of  2  parts  of  iodine,  5  of  iodide  of  potassium,  and  40  of  water,  are  used. 

flutMiM  of  stMi  The  annual  production  of  steel  in  Burope  may  be  roughly  estimated  for 
^ndB^too-      1870  at  6,285,000  cwts.  at  50  kilos,  to  the  cwt. 

The  imperial  English  crwt.  is  equal  to  508,023  Idlos. ;  of  this  total  the  undermentioned 
eonntries  produce : — 

United  Kingdom  of  Ghreat  Britain  and  Ireland  2,300,000 

France ii35o,ooo 

Belgium        225,000 

North  German  Confederation 1,120,000 

Austria 900,000 

Sweden 250,000 

Russia ^ 150,000 

Italy      75»ooo 

Spain 15,000 

Total     6,285,000 

Ibon  Pbxfabitions. 

aSSS^fvSca.  ^^  substance  called  copperas  and  green  vitriol,  sulphate  of  protoxide 
of  iron,  (FeS04+7H20),  is  met  with  in  the  trade  in  the  form  of  greenish-coloured 
crystals  possessed  of  an  inky  astringent  taste ;  on  exposure  to  dry  air  the  crystals 
edfioresoe,  and  are  gradually  converted  into  a  yellowish  powder — ^basic  sulphate  of 
peroxide  of  iron.    100  parts  of  the  chemically  pure  crystallised  salt  consist  of : — 

26' 10   parts  of    protoxide  of  iron. 

2990         „         sulphuric  acid. 

4400         „         water. 


32  CHEMICAL  TECHNOLOGY. 

prepanuon  of  Gwen  Since  the  minerals  ordinarily  used  in  the  manufacture  of  alum — 
^'to -uii^orfci,"*  the  alum  schists — generally  contain  iron  pyrites,  (FeSa),  either  as 
such  or  already  partly  converted  into  a  hasic  sulphate  of  the  peroxide  (which,  on 
being  treated  along  with  the  alum  shale,  becomes  by  weathering  and  roasting 
converted  into  protosulphate  and  peroxide  of  iron),  green  vitriol  is  frequently 
a  by-product  of  alum  manufacture,  and  is  obtained  by  evaporating  the  mother-liquor 
containing  iron,  and  leaving  it  to  crystallise.  In  some  localities,  as,  for  instance, 
at  Goslar  (Prussia) ,  on  the  Hartz  mountains,  the  liquor  obtained  by  the  lixiviation  of 
the  iron-containing  minerals  alluded  to  .is  first  evaporated  for  the  separation  ]of  the 
green  vitriol,  then  a  potassa  or  ammonia  salt  added  to  the  remaining  acid  liquid  to 
obtain  alum. 

^'^WSofL^BedL**"      ^^^6  material  sometimes  rather  largely  found  in  coal  pits,  and 

called   brass   (iron  pyrites),  is  collected  and  placed  in  layers  over  a  somewhat 

excavated  surface,  which  has  been  rendered  impervious  to  water  by  puddling  with 

clay,  and  made  to  incline  slightly  in  one  direction  where  water-tight  tanks  stand, 

into  which  scraps  of  old  iron  are  placed  with  the  view  of  saturating  any  free  acid ; 

the  pyrites,  placed  on  these  beds  to  a  thickness  varying  from  li  to  3^  or  4  feet,  is 

slowly  oxidised  by  atmospheric  agency,  and  the  falling  rain  carries  into  the  tanks  a 

more  or  less  strong  solution  of  copperas,  which,   when   sufficiently  concentrated, 

is  slowly  evaporated,  some  scrap-iron  being  placed  in  the  evaporating-pans.    In 

Green  Vitriol  from   couutries   whcrc    irou  pyrites    abound^,    and  fuel  and  labour  are 

pyriUM  Dutiuation.  sufficiently  chcap  to  make  the  distillati^  of  sulphur  from  pyrites  a 

profitable  business,  the  residues  are  utilised  in  green  vittiol  making,  a  salt  which 

thus  made  must,  of  necessity,  contain  a  good  deal  of  impurity.    The  brown  sulx)huiic 

Green  Vitriol  from    acid  or  chamber  acid,  also  such  waste  sulphuric  acid  liquids  as  are 

and  soiphorirAdd.  obtained  in  the  oil  and  petroleum  refining,  are  sometimes  used  as 

solvents  for  scrap-iron  for  the  preparation  of  green  vitriol,  which  may  also  be  made 

by  boiling  the  finely  pulverised  puddling  and  iron  refining  sla^s  with  sulphuric  acid. 

From  spAthio  Ii^  localities  where  spathic  iron  (carbonate  of  protoxide  of  iron,  FeCO]) 
Iron  Ore.  occurs  in  a  pure  state,  that  mineral  may  be  usefully  applied  to  the  preparation 
of  green  vitriol  by  treatment  with  sulphuric  acid,  and  evaporating  the  solution  thus 
obtained.  The  sulphate  of  iron  (protoxide),  prepared  on  the  large  scale,  is  often  met  with 
crystallised  round  a  small  thin  stick  of  wood,  which  is  hung  up  in  the  solution  to  promote 
crystaUisation ;  sometimes,  at  least  abroad,  a  so-called  black  vitriol  is  met  with,  which  is 
simply  green  copperas  superficially  coloured  black  by  means  of  some  astringent  decoction, 
such  as  nut  galls. 

Uses  of  Green  Vitriol.  Tbls  Bubstanco  is  employed  as  a  disinfectant,  as  a  mordant  in  dyeing 
and  caUco  printing  for  various  black  and  brown  shades,  for  the  preparation  of  ink,  the 
deozidation  of  indigo — so-called  cold  vat — in  gas  purifying,  in  the  precipitation  of  gold 
from  its  solutions,  in  the  preparation  of  Prussian  blue,  in  the  manufacture  of  fuming 
(Nordhausen)  sulphuric  acid,  and  for  a  host  of  other  purposes. 

Iron  Miniom.  During  the  last  10  or  15  years  a  large  number  of  substances  under  this 
name  have  been  introduced  as  paints,  especially  for  iron  sea-going  vessels  and  other 
ironwork.  The  late  Dr.  Bleekrode  analysed  two  samples  of  this  paint,  one  of  which, 
made  and  sold  by  M.  Cartier  in  Belgium,  was  found  to  consist  in  100  parts  of : — 

Moisture 275 

Red  peroxide  of  iron  68'27 

Clay 27*60 

Lime        0*40 

A  sample  of  Holland's  iron  minium  was  found  to  contain  in  100  parts : — 

Water       6*oo 

Peroxide  of  iron     . .     85 "57 
Clay  (burnt)    . .     . .       8-43 


IfiO.V. 


33 


In  Dr.  O.  J.  Mnlder'B  vork  on  the  "  CbemJatry  of  Drjiag  Oils  " ' — seoond  or  applied  part 

attention  is  called  to  the  fact,  and  supported  by  resnlta  of  aiialyties  of  differeut  iron 
miuioiDii  ubtoiaed  b;  the  author,  that  aoiuo  of  thcae  paints  contain  free  Bolphuric  aoid, 
which  is  always  preneat  in  oolcothar ;  this  acid  may  eierciae  an  iujurioas  effect  on  iron 
painted  with  snch  materials. 

It  is  hardly  neceasoi?  to  point  ont  that  the  uao  of  iron  mininm  aa  paint  is  less 
eipensive  than  the  use  of  red-lead,  in  the  proportion  of  20  to  30  for  coating  the  same 
extent  of  surface. 

'^(TmSS™  ^*  yeilow-coloured  salt,  generally  laio(vn  as  yellow  prussiate  of 
polaesa  (ferrocyanide  of  potassium.  K,FeCy6+3HjO),  is,  in  a  technical  point  of  view, 
a  verj  important  substance.  It  crystallises  in  large  lemon-ooloured  prismatio 
rr^stals,  which  are  not  affected  by  exposure  to  air,  are  not  poisonous,  and  possesa  a 
nweelish  bitter  taste.  This  salt  ia  soluble  in  4  parts  of  cold  aud  2  of  boiling  wal«r, 
but  is  iiiDoluhle  in  alcohol ;  in  100  parts  there  are : — 
37 '03  Potasaium, 


1704  Carbon,      jcyanogen. 
io-Sq  Nitroaen,   >     '       ^ 


}  Nitrogen 
13-25  Iron, 
1279  Water. 
At  100°  the  water  is  driven  off.     The  salt  is  prepared  on  a  large  scale  by  igniting 
snch   carbon   as  contains  nitrogen  to  a  red  beat   with  potassa- carbonate  in   closed 
vessels.    The  quantities  of  the  materiala  may  be  varied,  the  relatire  proportions 
being  given  by  some  makers  aa  100  parts  of  potassa- carbonate  to  75  of  the  mtrogenons 
carbon,  or.  according  to  Ilunge,  100  parts  of  carbonate  of  potassa,  400  of  calcined 
hum,  and  10  parta  of  iron-filinga. 

The  fusion  of  these  ingredients  is  carried  on  either  in  cloaed  iron  vessels  of  a 
peculi&r  shape,  or  in  a  reverberatory  furnace.    The  iron-vessel,  a,  tenned  a  muffle 


Fio.  16. 


Fig   1 


(Fig.  16)  ia  egg-  or  pear-shaped,  having  a  diameter  of  I'z  metres,  a  width  of  o'8  metre, 
and  vaiying  from  13  tai5centiias.in  thickness.  As  shown  in  tlie  woodcut,  the  iron  vessel 
is  placed  in  the  furnace  in  such  a  manner  as  to  be  exposed  to  the  action  of  the  flame 
and  hot  gases  on  all  sides,  being  supported  at  the  back  by  a  projection  about  27  centims. 
long,  and  resting  at  g  on  the  brickwork,  leaving  space  sufficient  for  the  gases 
generated  in  the  interior  to  pass  off  by  c  int«  the  chimney-flues ;  m  is  on  iron  cover 
which  is  dosed  during  the  operation  of  melting,  g  being  an  opening  in  the  front  wall 
of  Uie  furnace,  through  which   tlie  ingredients  are  put  into  the  iron  vessel,  and  the 

■  The  original  iBinDatch,and  the  noik  Jim  not  been  tranalalcd  into  any  nthei  Inneu.iije. 


34  CHEMICAL    TECHNOLOGY. 

molten  mass  taken  out.  The  shallow  pan,  t\  on  the  top  of  the  furnace,  is  intended 
for  the  evaporation  of  the  liquor  obtained  by  treating  the  molten  mass  with  water. 
The  use  of  the  iron  vessel,  however,  is  attended  with  the  serious  drawback  that  the 
iron  is  eaten  into  holes  in  a  comparatively  short  space  of  time ;  and,  though  this 
action  is  greatest  on  the  lower  part  of  the  vessel,  and  it  may  therefore  be  turned 
bottom  upwards,  and  tlie  holes  stopped  witli  fire-clay,  the  vessel  has  soon  to  be 
replaced  by  anotlier.  It  is  on  tliis  account,  and  also  owing  to  the  fact  that  a  larger 
quantity  of  raw  mateiial  can  be  operated  upon  at  once,  that  instead  of  the  apparatus 
described  above,  tliere  has  come  into  general  use  a  reverberatory  furnace.  Fig.  17, 
arranged  with  a  shallow  cast-iron  pan,  a,  from  i  to  i'8  metre  in  diameter,  vnih  a  rim 
about  I  decini.  high;  b  is  the  fu'e-place;  g  the  bridge;  c  a  flue  leading  to  the  cbinmey.  e. 
Sometimes  the  hot  air  is  applied  to  the  heating  of  evaporating-pans,  being  carried 
imder  them  before  entering  tlie  cliimney.  The  result  of  the  ignition  is  the  formation 
of  a  black  mass,  technically  called  the  metals  yielding  the  liquor  from  which  the  crude 
salt  crystallises.  The  salt  is  purified  by  re-crystallisation,  while  the  black  residue  is 
employed  as  a  manure. 

The  theory  of  the  formation  of  the  ferrocyanide  of  potassium  is  as  follows: — The 
carbonate  and  sulphate  of  potassa,  the  nitrogenous  coal  and  the  iron  reacting  upon 
each  other,  give  rise  to  the  formiition  first  of  sulphuret  of  potassium,  which  in  its  turn 
converts  the  iron  into  sulphuret,  while  the  nitrogen  contained  in  the  charcoal  unites, 
under  the  influence  of  potassium,  with  the  cyanogen  of  the  carbon,  which  again  in  its  turn 
combines  with  the  potassium,  giving  rise  to  the  formation  of  cyanide  of  potassium.  When 
the  fused  mass  is  treated  with  water,  cyanide  of  potassixmi  and  sulphuret  of  iron  decom- 
pose each  other,  the  result  being  the  formation  of  ferrocyanide  and  sulphide  of  potassiom, 
the  last-named  salt  remaining  in  the  mother-liquor.  M.  E.  Meyer  states  (1868)  that  it  is 
more  advantageous  to  employ,  instead  of  the  sulphuret  of  iron,  the  carbonate  of  that 
metal,  for  the  purpose  of  converting  cyanogen  into  ferrooyanogen,  because  the  ferro- 
cyanide of  potassium  crystallises  far  more  completely  and  freely  from  solutions  not  con- 
taining any  sulphuret  of  potassium.  Professor  Dr.  von  Liebig  has  since  proved  that 
the  fused  mass  only  contains  cyanide  of  potassium  and  metaUic  iron,  and  not  any  ferro- 
cyanide of  potassium,  which  is  only  formed  by  treating  the  molten  mass  with  water,  or 
more  slowly  by  its  exposure  to  moist  air.  Among  the  materials  frequently  added  to  the 
fueling  mass  are — scraps  of  metal,  the  refuse  of  leather,  dried  blood  and  other  dry  animal 
offal,  because  the  ammonia  evolved  by  their  decomposition  in  the  presence  of  an  alkali 
aids  the  formation  of  cyanide  of  potassium.  According  to  M.  P.  Havrez,  the  crude  snint 
obtained  from  wool  is  an  excellent  material  for  the  preparation  of  ferrocyanide  of  potas- 
sium, since  100  kilos,  of  the  suint  contain  about  40  kilos,  of  carbonate  of  potassa,  from 
I  to  2  kilos,  of  cyanide  of  potassium,  and  about  50  kilos,  of  combustible  hydrocarbons,  the 
heating  value  of  which  is  at  least  equal  to  that  of  40  kilos,  of  coal. 

It  has  been  tried  to  obtain  the  cyanide  of  potassium  on  a  large  scale,  by  causing  a 
current  of  ammoniacal  gas  to  pass  through  and  over  carbonate  of  potassa  heated  to 
redness  ;  and  also  to  obtain  cyanide  of  potassium  from,  or  by  aid  of,  the  nitrogen  of  the 
atmosphere.  This  process  was  tried  nearly  40  years  ago  at  Mr.  Bramwell's  works  near 
Newcastle-on-Tyne,  but  was  found  to  be  a  failure  commercially.  The  reader  interested  in 
a  detailed  account  of  this  process  may  find  it  in  the  excellently-written  chapter  on  the 
manufacture  of  the  pmssiates,  in  Bichardson  and  Watts*s  **  Chemical  Technology.** 
As  it  has  been  proved  by  experiment  that  baryta,  far  more  readily  than  potassa,  converts 
carbon  and  nitrogen  into  cyanogen,  forming  cyanide  of  barium  at  a  lower  temperature, 
baryta  might  perhaps  be  substituted  for  potassa,  but  as  yet  this  plan  is  not  carried  out 
commercially.  According  to  G^hs  (1861),  the  yellow  prussiate  may  be  prepared  by  the 
mutual  reaction  of  sulphide  of  carbon  and  sulphide  of  ammonium,  the  resulting  sulpho- 
oarbonate  being  converted  into  sulphocyanide  of  potassium  by  means  of  sulphuret  of 
potassium,  by  which  reaction  sulphuret  of  ammonium  and  sulphuretted  hydrogen  are 
volatilised.  The  sulphocyanide  of  potassium  is  next  converted  into  ferrocyanide  of 
potasF-ium  by  being  heated  with  metallic  iron  to  redness,  sulphuret  of  iron  being  at  the 
same  time  formed.  It  is  evident  that  this  process  could  not  be  carried  out  commercially. 
Mr.  H.  Fleck  described,  in  1863,  a  plan  for  preparing  the  ferrocyanide  by  the  action  of  a 
mixture  of  sulphate  of  ammonia,  sulphur,  and  carbon,  upon  fusing  sulphide  of  potassiom, 
which  thus  becomes  sulphocyanide  of  potassium,  one-half  of  the  nitrogen  of  the  sulphate 


IRON, 


35 


of  azmnonia  remaining  in  the  fused  metal  as  cyanogen,  while  the  other  half  escapes 
as  solphide  of  ammonium,  which  is  again  converted  into  sulphate  of  ammonia.  The 
Bolphocyamde  of  potassium  produced  is  treated  with  metallic  iron  at  a  red-heat,  and 
thus  cyanide  of  potassium  and  sulphide  of  iron  are  produced.  This  process  is  also  too 
cumbrous  and  expensive  on  a  large  scale. 
Appu»tioiis  of  tiu  This  salt  is  employed  in  the  manufacture  of  the  red-cyanide  or  prussiate, 
leiiow  Fmscut«.  in  the  preparation  of  Berlin  blue,  and  of  cyanide  of  potassium  (the  impure 
salt  as  met  within  commerce),  in  dyeing  and  calico-printing  for  the  production  of  blue  and 
brown-red  colours,  for  the  purpose  of  surface-hardening  small  iron  articles,  and  lastly  as 
an  ingredient  of  white  gunpowder,  and  for  use  in  chemical  laboratories. 

acdPniMiatc.      The    80-called    red    prussiate  of  potassa,    properly  ferricyanide  of 

potassium,  or  Gmelin's  salt,  K3FeCy,  is  prepared  on  a  large  scale  and  extensively 

used  in  dyeing  and  calico-printing.    This  salt  ciystallises  in  prismatically-shaped 

ruby-red-coloured,  anhydrous  crystals,  which  consist  in  loo  parts  of: — 

35*58  Potassium, 

21-63  Carbon,     jcyanogen, 
25-54  Nitrogen,  > 
17-29  Iron. 

It  is  prejxared  by  submitting  either  the  solution  of  the  yellow  prussiate  or  tliat 
tialt  in  powder  to  the  action  of  chlorine  gas  until  a  sample,  when  heated,  yields 
no  precipitate  with  a  solution  of  a  per-salt  of  iron.  When  the  dry  and  pulverised 
yeUow  prussiate  is  ftcted  upon  by  chlorine  gas,  the  salt  is  frequently  placed  in  casks, 
closed  so  as  only  to  leave  a  small  outlet,  while  the  vessel  can  be  made,  by  means 
of  machinery,  to  turn  slowly  on  its  axis,  so  as  to  bring  all  the  particles  of  the 
salt  into  contact  with  the  chlorine.  Sometimes,  again,  the  pulverised  yellow  prus- 
siate is  placed  on  trays  in  a  chamber,  into  the  top  of  which  chlorine  gas  is  admitted ; 
when  no  more  chlorine  is  absorbed  the  newly-formed  salt  is,  if  a  solution  of  the 
yellow  prussiate  has  been  operated  upon,  evaporated  to  dryness,  or  in  the  case  where 
the  dry  powder  of  the  salt  has  been  taken,  the  newly-formed  salt  is  dissolved  in  the 
smallest  possible  quantity  of  water,  and  the  solution  left  to  crystallise,  the  mother- 
Kqiior  containing  chloride  of  potassium.    This  reaction  is  represented  by — 

K+FeCye  -i-  CI = KCl + KaFeCy . 

, '  ^ , - 

Yellow  prussiate.  Bed  prussiate. 

The  powdered  red  prussiate  is  of  an  orange -yellow  colour.  According  to 
M.  E.  Reichardt  (1869)  bromine  may  be  successfully  employed  instead  of  chlorine  for 
the  preparation  of  this  salt,  which  is  chiefly  used  for  dyeing  woollen  fabrics  blue, 
And,  with  solutions  of  caustic  soda  or  potassa,  for  the  Mercerising  process  of  cotton. 

cjniAt  of  poUsdom.  This  salt  is  obtained  in  an  impure  state — Liebig's  or  crude  cyanide 
of  potassium — by  the  fusion  of  the  yellow  prussiate  of  potassa  in  a  porcelain  crucible, 
continued  as  long  as  nitrogen  escapes.  Carburet  of  iron  sinks  to  the  bottom  of  the 
crucible,  while  the  crude  cyanide  is  poured  off  in  a  state  of  fusion ;  10  parts  of  the  yellow 
prussiate  of  potassium  yield  7  parts  of  crude  cyanide,  (K4FeCy6=4KCy-HFeC2-H2N). 
According  to  Liebig^s  plan,  the  cyanide  of  potassium  is  prepared  by  fusing  i  molecule  of 
ferrocyanide  of  potassium  with  i  molecule  of  carbonate  of  potassa ;  by  this  method  10  parts 
of  the  ferrocyanide,  yielding  8-8  cyanide  of  potassium,  mixed  with  2*2  parts  cyanate  of 
potassa.  For  aU  technical  and  industrial  purposes  it  is  far  cheaper  to  use  cyansalt,  a 
mixture  of  the  cyanides  of  potassium  and  sodium,  prepared  by  fusing  together  8  parts  of 
previously  dried  (anhydrous)  ferrocyanide  of  potassium  and  2  parts  of  carbonate  of  soda. 
As  this  mixture  fuses  readily,  the  carburet  of  iron  easily  separates ;  moreover,  the  salt  thus 
obtained  is  less  liable  to  decomposition  on  exposure  to  air,  and  its  preparation  requires 
less  heat.  The  industrial  applications  of  the  crude  cyanide  of  potassium,  or  of  the  cyan- 
**lt,  are  the  following  : — In  the  process  of  electro-gUding,  for  the  preparation  of  GrSnat 
foluble^  isopurpurate  of  potassa,  from  picric  acid,  and  in  the  reduction  of  metals.    It 

P  2 


36  CHEMICAL  TECHNOLOGY, 

has  been  mentionel,  while  treating  of  the  blast-furnace  process,  that  oyanide  of  potassiam 
is  formed  daring  the  reduction  of  iron. 

Beriin-Biua.  Thls  substaiice,  80  named  when  it  was  accidentally  discovered  at  Berlin, 
in  1 710,  by  Diesbach,  is  chemically  a  ferrocyanide  of  iron,  more  correctly  ferrous- 
ferric  cyanide.  A  distinct  variety  of  this  substance  is  known  as  Paris-blue.  Three 
different  kinds  of  Berlin-blue  are  known,  viz.,  neutral,  basic,  and  a  mixtnre  of  the 
two,  differing  in  composition  and  prepared  by  different  processes. 

(a).  Neutral  Berlin-blue,  also  known  as  Paris-blue,  is  obtained  by  pouring  a  solution  of 
yellow  prussiate  into  a  solution  of  chloride  of  iron,  or  into  a  solution  of  a  peroxide  salt  of 
iron ;  the  result  is  the  formation  of  a  larg^  quantity  of  a  magnificently  blne-ooloured 
precipitate,  very  difficult  to  wash  out  and  always  retaining  a  certain  quantity  of  the  yellow 
prussiate,  which  cannot  be  removed  by  washing. 

(b).  Basic  Berlin-blue  is  obtained  by  precipitating  a  solution  of  yellow  prussiate  with  a 
solution  of  a  salt  of  protoxide  of  iron  (green  copperas),  the  result  being  at  first  the  forma- 
tion of  a  white  precipitate  of  protooyanide  of  iron,  which,  either  by  exposure  to  air,  or  hj 
the  action  of  oxidising  substances,  becomes  blue ;  because  a  portion  of  the  iron  is  oxidised 
and  another  portion  takes  up  the  cyanogen  thus  liberated,  converting  some  of  the  proto- 
cyanide  into  percyanide,  wMoh  in  its  turn  combines  with  the  unattacked  protocyamde  to 
form  Berlin-blue,  with  which,  however,  some  peroxide  of  iron  remains  mixed.  It  is  stated 
that  basic  Berlin-blue  is  distingui^ed  from  neutral  Berlin-blue  by  being  soluble  in  water; 
but  this  solubility  is  due  to  the  presence  of  some  of  the  yellow  prussiate,  and  is  not  a 
property  inherent  in  the  basic  Berlin-blue  in  a  pure  state. 

(c).  As  the  materials  employed  on  a  large  scale  are  neither  pure  protoxide  nor  puie 
peroxide  salts  of  iron,  but  a  peroxide  containing  protosalt  of  iron,  the  ^precipitate  obtained 
consists  at  first  of  a  mixture  of  neutral  Berlin-blue  wi^  more  or  less  of  the  white  proto- 
cyanide  of  iron,  which  afterwards  becomes  basic  Berlin-blue ;  accordingly  the  Berlin-blue 
of  commerce  is  a  variable  mixture  of  neutral  and  basic  Berlin-blues.  The  iron  salt 
employed  is  green  copperas  (sulphate  of  protoxide  of  iron),  which  of  course  should  not 
contain  any  appreciable  amount  of  copper,  the  salts  of  this  metal,  as  is  well  known, 
yielding  with  yellow  prussiate  of  potassa  a  chocolate-brown  coloured  precipitate. 
Old  Method  of  Prepaziiig  The  sulphate  of  iron  and  alum  are  dissolved  together  in  boiling 
Pruaaian-Biue.  ram-  or  river-water ;  the  fluid,  while  yet  hot,  is  decanted  from  any 

sediment  and  forthwith  poured  into  a  hot  aqueous  solution  of  yellow  prussiate,  oare  being 
taken  to  stir  the  mixture,  and  to  add  the  copperas  and  alum-solution  as  long  as  any  preci- 
pitate is  formed.  The  liquor  is  run  off,  and  the  precipitate  washed  with  fresh  water,  ontQ 
all  the  sulphate  of  potassa  is  removed ;  after  which  the  precipitate  is  drained  on  filters 
made  of  coarse  canvass.  This  haying  been  accomplished  the  substance  is  suspended  in 
water  in  a  boiler,  and,  while  being  heated  to  the  boiling-point,  nitric  acid  is  added ;  after 
a  few  minutes'  boiling,  the  contents  of  the  boiler  are  poured  into  a  large  wooden  tub  or 
cask,  and  strong  sulphuric  acid  is  added.  The  solution  is  now  allowed  to  stand  for  some 
tune,  during  which  the  blue  colour  fully  developes.  The  Berlin-blue  is  then  thoroughly 
washed  with  water,  drained  on  coarse  canvass  Mters,  next  dried,  pressed,  and  cat  into 
cakes ;  finally  it  is  dried  in  rooms  heated  to  80°.  As  Berlin-blue,  when  once  quite  dry,  ia 
reduced  to  powder  with  great  difficulty,  and  cannot  be  brought  to  the  state  of  fine  division 
as  when  first  precipitated,  it  is  also  sent  into  the  market  in  the  state  of  paste.  The 
alumina  derived  from  the  alum  is  so  intimately  mixed  with  the  blue  that  the  bulk  of  the 
mass  is  thereby  increased  without  any  very  perceptible  decrease  in  the  intensity  of  the 
colour.  If  the  quantity  of  alumina  is  very  much  increased,  the  colour,  of  course,  becomes 
much  lighter,  and  this  variety  of  Berlin-blue  is  then  Imown  as  mineral-blue ;  a  name  also 
given  to  a  preparation  of  copper  obtained  either  from  the  native  hydrated  carbonate  of 
copper,  or  artificially  prepared  by  precipitating  nitrate  or  diloride  of  copper  by  means  of 
Ume  and  chalk. 

B«ccnt  Methods  of  Among  the  improvements  made  more  recently,  we  may  briefly  notice 
Propiiring  Berlin-Blue,  the  following :— I.  The  mixing  of  the  solutions  of  copperas  and  alum 
with  that  of  yellow  prussiate  is  effected  as  above  described,  but  great  care  is  taken  to 
prevent  any  oxidation  of  the  white  precipitate,  which  is  converted  into  an  intense  blue  by 
being  treated  with  nitro-hydrochloric  acid,  the  chlorine  evolved  serving  as  an  oxidising 
agent.  The  remaining  operations,  viz.,  washing,  drying,  <&c.,  are  performed  as  in  the 
former  methods.  2.  Perchloiide  of  iron  solution  is  employed  for  the  purpose  of  converting 
the  white  precipitate  into  blue,  while  the  protochloride  of  iron  thus  formed  serves  at  a 
subsequent  operation  instead  of  protosulphate  of  iron.  3.  In  some  cases  perchloride  of 
inanganeso  (Mn^Cle),  is  applied ;  likewise  a  solution  of  chromic  acid,  a  mixture  of 
bichromate  of  potassa  and  sulphuric  acid ;  but  it  is  self-evident  that  the  application  of 


COBALT.  37 

anj  of  those  improvements  is  dependent  as  regards  success  in  a  commercial  point  of 
Titfw,  npon  local  conditions,  and  upon  the  possibility  of  advantageously  obtaining  the 
▼aiiouB  ingredients. 

TuntrairB-Bine.  By  mixing  together  a  solution  of  red  prussiate  and  of  protosulphate  of 
iron  in  such  proportions  as  to  prevent  the  entire  saturation  of  the  former  salt,  there  is 
obtained  a  blne-coloored  precipitate,  known  in  commerce  as  Tumbull's-blue,  consisting  of 
Fe2Cy3,3FeCy,  bat  also  oontaing  some  chemically-combined  yellow  prussiate.    MM.  Mallett 

BtriiiiBfa&euftBy-  ^"^^  Gautier-Bouchard  have  proved  experimentally  that  Berlin-blue  may 
Prodnct  of  the      be  obtained  as  a  by-product  of  coal-gas  manufacture  from  the  ammoniacal 
"SlSSeSi*'     liquor,  from  the  spent  lime  of  the  purifiers,  and  from  Laming's  purifying- 
Aojjua  CbueoaL    mixture.    The  spent  lime  contains,  in  addition  to   the  cyanides  of 
ealdnm  and  ammonium,  a  good  deal  of  free  ammonia,  mechanically  absorbed  in  the 
moiBt  lime.     Free  ammonia  is  first  removed  by  forcing  steam  through  the  lime,  and 
eollecting  the  ammoniacal  gas  in  dilute  sulphuric  acid.    The  lime  is  next  washed  with 
water,  and  the  Uquor  obtained,  containing  the  cyanogen  compounds,  is  employed  for  the 
mannfaetofie  of  Berlin-blue.    According  to  M.  Erafft's  experiments,  looo  kilos,  of  spent 
gas-lime  yield,  when  treated  as  described,  from  12  to  15  kilos,  of  Berlin-blue,  and  from 
15  to  20  kilos,  of  sulphate  of  ammonia.    Mr.  Phipson  states  that  i  ton  of  Newcastle  gas- 
coal  yields  a  quantity  of  cyanogen  which  corresponds  to  from  5  to  8  lbs.  of  Berlin-blue. 
The  manufacture  of  animed-charcoal  also  yields,  if  desired,  Berlin-blue  as  a  by-product. 

Soluble  Betiin-BiiM.  As  ordinary  Berlin-blue  is  quite  insoluble  in  water,  and  the  basic 
viriety  only  soluble  in  the  presence  of  ferrooyanido  of  potassium,  these  pigments  are  only 
fit  for  use  as  paints,  and  the  discovery  of  the  solubility  of  pure  Berlin -blue  in  oxalic  acid 
is  of  some  importance,  for  thereby  its  application  as  a  water-colour  becomes  possible. 
This  soluble  blue  is  obtained  by  digesting  the  Berlin-blue  of  commerce  for  i  to  2  days, 
with  either  strong  hydrochloric  acid  or  with  strong  sulphuric  acid,  which  latter,  after 
having  been  mixed  with  the  Berlin-blue  previously  pulverised,  is  diluted  with  its  own  bulk 
of  water.  The  acid  is  liext  decanted  from  the  sediment  of  blue,  and  the  latter  thoroughly 
washed  and  dried,  and  then  dissolved  in  oxalic  acid,  the  best  proportions  being  8  parts  of 
Berlin-blue,  treated  as  just  mentioned,  i  part  of  oxalic  acid,  and  256  of  water.  According 
to  other  directions,  Berlin-blue  readily  soluble  in  water  can  be  obtained: — i.  By  the 
precipitation  of  protoiodide  of  iron  with  yellow  prussiate  of  potassa,  care  being  taken  to 
keep  the  latter  in  excess.  2.  By  mixing  a  solution  of  perchloride  of  iron  in  alcoholic 
ether  (tinciura  fernchlorati  cetherea^  Ph.  Buss.)  with  an  aqueous  solution  of  yellow 
pnusiate. 

Pure  Berlin-blue  is  of  a  very  deep  blue  colour,  with  a  cupreous  gloss ;  it  is  insoluble  in 
water  and  alcohol,  is  decomposed  by  alkalies,  concentrated  acids,  and  by  heat.  Tho 
lighter  and  more  spongy  it  is,  the  better  is  its  quality ;  it  is  employed  as  a  pigment  and  in 
dyeing  and  calico-printing,  but  in  the  two  latter  instances,  pigment-printing  excepted,  it 
is  obtained  on  the  tissues  by  a  circuitous  process.  The  Berlin-blue  of  commerce  is 
frequently  adulterated  with  alumina,  pipe-clay,  kaolin,  magnesia,  heavy-spar,  and, 
according  to  Pohl,  even  with  starch-paste  coloured  blue  b.y  means  of  tincture  of  iodine. 

Cobalt. 
(Co=s5g;  Sp.  gr.  =  87). 

Xfuuk  Cobalt.  This  metal  is  found  native  as  cobalt-spoiss  (CoAsa),  containing  from 
3  to  24  per  cent  of  cohalt,  and  from  o  to  35  per  cent  of  nickel ;  also  as  cobalt-glance, 
bright  white  dobalt  (CoAsS),  containing  from  30  to  34  per  cent  of  cobalt.  Cobalt  is 
prepared  on  a  large  scale  as  a  metal  at  Isorlohn,  and  at  Pfannensticl,  near  Aue,  in 
Germany.  Metallic  cobalt  exhibits  a  stccl-grey  colour,  somewhat  verging  upon  red, 
a  strong  metallic  lustre,  assumes  a  brilliant  polish,  is  malleable  and  ductile,  and  far 
tougher  than  iron.  It  requires  a  very  high  tompcrature  for  fusion,  is  only  slowly 
•cted  upon  by  dilute  acids,  but  readily  dissolved  by  nitric  acid  and  aqua  regia. 

GotaitGoioon.  The  orcs  intended  for  the  manufacture  of  the  cobalt  colours  are  roasted 
for  the  double  purpose  of  volatilising  the  sulphur  and  arsonir  they  contain,  and  for 
effecting  tiie  oxidation  of  the  cobalt.  After  roasting,  the  orcs  are  known  as  Zaffer  or 
Saphera.  According  to  the  degree  of  purity,  the  trade  distinguishes  the  ores  as 
'* coniiuon/*  '*  medium,"  and  "  very  fine  ;"  they  contain  essentially  a  mixture  of  proto 


38  CHEMICAL  TECHNOLOGY. 

peroxide  of  cobalt,  arsenic,  nickel,  and  traces  pf  the  oxides  of  manganese  and  bismntb, 
and  are  used  in  the  preparation  of  cobalt-colours.  In  Sweden  "  zaffers  "  are  prepared 
by  precipitating  a  solution  of  sulphate  of  protoxide  of  cobalt  with  a  solution  of 
carbonate  of  potassa.  Zaffer  is  used  for  the  manufacture  of  smalt,  cobalt-ultra- 
marine,— a  misnomer,  for  evidently  ultramarine  is  contracted  from  ultra-mare,  because 
the  lapis  lazuli  was  brought  across  the  seas  from  India — ^OsBruleum,  Rinmann's-green 
(cobalt-green  or  Saxony -green),  and  also  cobalt-yellow,  cobalt- violet,  and  cobalt- 
bronze. 

Smalt.  Compounds  ^f  cobalt  have  the  property  of  imparting  a  blue  colour  to  glassy 
substances  at  a  red-heat ;  when,  therefore,  impure  protoxide  of  cobalt  is  fused  with  sihca 
and  carbonate  of  potassa,  the  result  is  the  formation  of  an  intensely  blue-coloured  glass, 
which,  when  pulverised,  is  known  as  smalt.  This  substance  was  discovered  and  first 
prepared  by  the  Bohemian  glass-blower,  G.  Schurer,  who  lived  in  the  sixteenth  centniy. 
Smalt  is  now  prepared  by  melting  the  roasted  cobalt  ores  with  quartzose-dand  and  potash,  in. 
crucibles  placed  in  a  glass-furnace.  The  red-hot  glass  produced  is  quenched  in  cold  water  to 
render  it  brittle.  It  is  next  pulverised  and  scoured  with  water,  by  which  operation  smalts 
are  obtained  of  different  degrees  of  fineness,  not  simply  as  regards  minute  state  of  division, 
but  also  depth  of  colour,  all  of  which  varieties  abroad — where  to  a  limited  extent  the 
smalt  is  still  used,  though  it  is  almost  entirely  superseded  by  artificially-made  ultramarine 
— ^bear  distinctive  names.  It  has  been  proved  experimentally  that  the  colouring-matter  of 
smalt  is  potassio-siUcate  of  protoxide  of  cobalt,  in  which  the  proportion  of  the  oxygen  of 
the  acid  to  that  of  the  base  is  as  6 :  i.  According  to  M.  Ludwig,  loo  parts  of  the  under- 
mentioned cobalt  colours  contain : — 

Norwegian  Smalt.  German  Smalt. 


Termed         Coarse  and 
High  colour.  high  Eschel.    pale  coloured. 

Silica        70*86  66'2o  72*11 

Protoxide  of  cobalt        . .  6*49  675  1*95 

Potassa  and  soda . .       ..  21*41  16*31  i'8o 

Alumina 0*43  8*64  20*04 

These  substances,  moreover,  contain  small  quantities  of  protoxide  of  iron,  lime,  prot- 
oxide of  nickel,  arsenic  acid,  carbonic  acid,  water,  and  oxides  of  lead  and  iron.  Dr.  Oude- 
mans  lately  analysed  a  beautifully  ultramaiine-colom'ed  sample  of  smalt,  which  was 
found  to  contain  5*7  per  cent  of  protoxide  of  cobalt.  As  cobalt-glass  obtained  with  soda  is 
never  of  a  pure  colour,  that  alkali  cannot  replace  potassa  in  the  manufacture  of  smalt. 
Since  the  roasting  of  the  cobalt  ores  is  not  continued  long  enough  to  oxidise  the  nickel 
contained  in  them,  that  and  some  other  metals  present  fuse  during  the  preparation  of 
the  smalt,  and,  settling  to  the  bottom  of  the  crucible,  form  an  alloy  termed  Cobali-speiss. 
cobait-BpeisB.  This  substance  is  of  a  reddish-white  hue,  has  a  strong  metallic  lustre,  is  fine- 
grained in  structure,  and  contains  on  an  average  from  40  to  56  per  cent  nickel,  26  to  44 
per  cent  arsenic,  as  well  as  copper,  iron,  bismuth,  sulphur,  &c.  Dr.  Wagner  found  that 
(1870)  a  sample  of  this  alloy  from  a  Saxon  mine  contained  in  100  parts : — 

Nickel     48*20 

Cobalt 1-63 

Bismuth 2*44 

Iron 0*65 

Copper 1*93 

Arsenic 42*08 

Sulphur 3*07 


100*00 
The  material  is  chiefly  used  for  the  preparation  of  nickel. 

AppucaUoni  of      Smalt  is  still  employed  in  washing  and  dressing  blue,  and  for  imparting  a 
Smalt.        YjIjj^q  tint  to  paper.     It  is  not,  however,  very  suitable  for  this  purpose,  as, 
on  account  of  its  hardness,  it  soon  destroys  the  points  of  writing-pens.    Smalt  is  more 
extensively  used  for  blue-enamclUng  glass,  porcelain,  and  earthenware. 

Cobalt  uitnmaiine.  This  Bubstance,  also  known  as  Th^nard's  blue,  is  a  pigment  consisting 
of  alumina  and  protoxide  of  cobalt.  Curiously  enough  this  pigment  has  been  discovered 
and  prepared  at  three  several  periods  and  localities  by  different  people ;  first,  by  Wenzel, 


NICKEL.  39 

St  Freiberg,  Saxony ;  next  by  Gahn,  at  Fahlnn,  Sweden ;  and  lastly,  Biniultaneously  at 
Paria  and  Vienna,  by  Th^nard  and  von  Leithener.  TLe  pigment  is  prepared  either  by 
mixing  Bolutions  of  alnm  and  a  salt  of  protoxide  of  cobalt,  precipitating  the  mixture  by  a 
eolation  of  carbonate  of  soda ;  or  by  the  decomposition  of  aluminate  of  eoda  by  meanb  of 
chloride  of  cobalt.  The  ensuing  precipitate,  consisting  of  an  intimate  mixture  of  hydrate  of 
alamina  and  hydrate  of  protoxide  of  cobalt,  is  first  well  washed,  then  dried  and  heated  lor 
some  time.  The  pigment  thus  produced  is,  when  seen  in  daylight,  of  course  after  pulver- 
isation, vezy  siihilar  to  ultramarine,  but  by  artificial  light  its  colour  is  a  dirty  riolet.  It 
is,  however,  not  acted  upon  by  acids)  as  distinguished  from  artificial  ultramarine  ;  neither 
is  it  a£feoted  by  alkaUes  nor  heat,  as  is  copper  or  mineral  blue.  Cobalt-ultramarine, 
chiefly  under  the  denomination  of  Thdnard's  blue,  is  employed  as  a  paint  m  oil-  and  wat^r- , 
colours,  and  also  for  staining  glass  and  porcelain. 

cmiram.  Is  a  pigment  prepared  in  England,  exhibiting  a  bright  blue  colour,  not 
changing  in  artificial  light,  and  consisting  of  stannate  of  protoxide  of  cobalt  (Sn02,CoO), 
mixed  with  stannic  acid  and  gypsum  in  the  proportions,  in  loo  parts,  of  49*6  of  oxide  of 
tin,  18-6  protoxide  of  cobalt,  31*8  gypsum.  This  pigment  is  not  affected  by  heat,  or  the 
action  of  dilute  acids  and  aUcalies ;  nitric  acid  dissolves  the  protoxide  of  cobalt,  leaving 
the  other  ingredients,  from  which  the  gypsum  may  be  cleared  by  water. 

MxuBBDii'a,  or  This  substanco,  also  known  as  cobalt-green,  zinc-green,  and  Saxony-green, 
cob«iv<H««n.  ig  a  compound  similar  to  the  cobalt-ultramarine,  for  the  alumina  of  which 
oxide  of  zinc  is  substituted.  This  green  is  prepared  by  mixing  a  solution  of  white 
vitriol  with  a  solution  of  a  salt  of  protoxide  of  cobalt,  precipitating  by  carbonate  of 
soda,  and  washing,  diying,  and  heating  the  precipitate.  This  pigment  when  pure  con- 
tains 88  per  cent  of  oxide  of  zinc  and  12  per  cent  of  protoxide  of  cobalt.  It  is  not  affected 
by  btroug  heat,  tinges  the  borax-bead  blue,  dissolves  in  warm  hydrochloric  acid,  forming  a 
line  colour,  which,  upon  water  being  added,  becomes  a  pale  red.  Treated  with  caustic 
potassA,  the  oxide  of  zinc  is  dissolved,  and  may  be  detected,  after  previous  dilution  with 
water,  by  the  addition  of  a  solution  of  sulphuret  of  potassium. 

cheinieanT  i>iii«  ThiB  Bubstauce  is  occasionally  employed  for  the  preparation  of  fine 
prounidc  oi  Cobalt,  colours.  It  may  be  obtained  by  heating  one  part  of  previously  roasted 
and  finely-pulverised  cobalt  ore  with  two  parts  of  sulphate  of  potassa  until  no  more 
solphnric  acid  is  given  off.  The  fused  mass,  consisting  of  sulphate  of  potassa,  sulphate 
of  protoxide  of  cobalt,  and  insoluble  arsenical  salts,  is,  when  cooled,  first  treated  witii 
water,  and  next  digested  with  hydrated  protoxide  of  cobalt  to  precipitate  any  iron  which 
may  happen  to  be  present,  and  in  order  to  eliminate  the  oxide  of  that  metal  the  solu- 
tion is  filtered.  It  is  next  precipitated  with  carbonate  of  soda,  and,  finally,  the  precipitate 
is  washed  and  heated. 
Kitnto  of  Protoxide  of  This  doublc  salt,  known  by  its  trade  name  of  cobalt-yellow,  is 
cotait  sad  Pouaaa.  obtained  by  mixing  a  solution  of  protoxide  of  cobalt  with  nitrite  of 
potassa ;  it  is  a  yellow  crystalUne  precipitate,  perfectly  insoluble  in  water.  M.  Saint-Evre 
first  investigated  this  body,  and  struck  with  its  beautifully  yellow  colour,  quite  like  that 
of  purrhee  (euxanthinate  of  magnesia),  and  with  the  fact  that  cobalt-yellow  resists 
oxidising  and  sulphurettuig  infiuences,  suggested  its  applicabihty  to  artistic  purposeH. 
He  prepares  this  pigment  by  precipitating  with  a  slight  excess  of  potassa  the  double  salt 
of  protoxide  of  cobalt  and  potassa,  obtaining  a  rose-red-coloured  protoxide  of  cobalt  and 
potassa.  Into  tuis  thickish  magma  deutoxide  of  nitrogen  gas  is  passed.  According  to 
Hayes,  this  pigment  is  readily  obtained  by  causing  the  vapours  of  hyponitric  acid  to  pass 
into  a  solntion  of  protonitrate  of  cobalt,  to  which  some  potassa  has  been  added ;  the 
whole  of  the  cobalt  is  then  converted  into  cobalt-yellow.  As  the  nitrite  of  protoxide 
of  cobalt  and  potassa  can  be  obtained  even  from  impure  solutions  of  protoxide  of  cobalt, 
so  as  to  be  quite  free  from  any  nickel,  iron,  dec,  the  use  of  this  preparation  of  cobalt  is 
preferable  for  glass  and  porcelain  staining,  when  a  pure  blue  is  required. 

cobttit-BraoM.  This  substance,  a  double  salt  of  phosphate  of  protoxide  of  cobalt  and 
ammonia,  prepared  at  Pfannenstiel,  near  Aue,  in  Saxony,  hns  been  but  lately  brought  into 
commerce.  It  is  a  violetrcoloured  powder,  very  much  like  the  \i<)lct-c<>l<>iiri'd  clilorile  of 
chromium,  and  oxhibits  a  strong  metallic  luKtrc. 

Nickel. 

(Ni  =  59;  Sp.  jrr.=.?  07  to  qzCv 

Kkkd  and  its  oks.  This  mctal  occurs  in  the  Ibllnuin;^  ores: — Copper  nickel  or 
arsenical  nickel,  NiAs,  containing  alxmt  44  ppr  cent  Ni ;  nntimonial  nickel,  NiSl), 
with  about  3 14  per  cent  Ni;  wliite  arsenical  nickel,  NiAsj,  witli  iibout  28  2  per 


40  CHEMICAL  TECHNOLOGY. 

cent  Ni ;  in  some  varieties  of  cobalt-speiss,  as,  for  instance,  the  capillaiy  pyrites 
(sulphuret  of  nickel)  with  648  per  cent  Ni ;  and  the  antimonial  nickel-ore, 

NiS2+Ni(Sb,As2), 
with  about  268  per  cent  Ni.  There  is  found  at  llewdansk,  Oural,  Russia,  a  mineral 
known  as  Rewdanskite,  a  silicate  of  hydrated  protoxide  of  nickel  (i2'6  per  cent  Ni), 
from  which  the  metal  is  obtained.  Nickel  is  also  extracted  from  ores  which  contain 
it  accidentally,  as,  for  instance,  some  species  of  iron  and  copper  pyrites,  cobalt-speiss, 
and  certain  copper  ores  known  as  Mansfeld  ores,  which  yield  sulphate  of  nickel  as  a  by- 
product. Several  varieties  of  manganese  contain  nickel  and  also  cobalt ;  and  in  England 
the  residues  arising  from  the  manufacture  of  chlorine  are  in  some  instances  applied 
in  the  production  of  these  metals,  the  process  yielding,  according  to  Gerland,  2*5  Idloe, 
of  nickel  and  5  kilos,  of  cobalt  for  i  ton  of  manganese.  Some  magnetic  iron  ores 
3deld  nickel,  a  specimen  of  such  ore  from  Pragaten,  Tyrol,  Austria,  containing, 
according  to  M.  T.  Petersen,  176  per  cent  of  NiO. 

^*"SS!tt?ora[!*^*^  ^*  ^^T  rarely  happens  that  the  natural  ores  of  nickel  are  so  pure, 
that  is  to  say,  contain  the  metal  in  such  a  state  of  combination,  as  to  admit  of  the 
direct  extraction  of  the  metal,  and  tlierefore,  as  is  the  case  \\4th  copper,  a  preliminary 
operation  is  required,  wliich  aims  at  the  concentration  of  the  metal  in  combination 
either  with  sulphur,  in  wliich  case  the  combined  substance  is  termed  regulus,  and 
sulphuret  of  iron  is  applied  as  a  means  of  concentrating  tlie  nickel  contained  in  the 
ore  as  sulphuret ;  or,  if  the  nickel  happens  to  be  combined  cliiefly  with  arsenic,  the 
concentrated  mass  is  termed  speiss ;  while  in  a  few  instances  an  alloy  of  nickel  an<l 
coarse  or  black  copper  is  obtained.  From  aU  these  products  the  metallic  nickel,  or 
sometimes  an  alloy  of  nickel  and  copper,  is  prepared  by  the  dry  or  moist  process. 

The  method  of  obtaming  nickel  embraces  two  distinct  features,  viz. : — 
I.  A  smelting  process,  which  aims  at  rendering  the  nickel  of  the  ores  richer,  and 
concentrating  the  metal — 
a.  fn  a  regulus, 
/3.  In  a  speisB,  or 
y.  In  alloy  with  coarse  or  black  copper. 

n.  In  the  separation  of  the  nickel,  or  a  definite  alloy  from  the  products  obtained  by 
the  concentration-smelting ;  this  can  be  done — 

a.  By  the  dry,  or 

6.  By  the  hydro-metallurgical  method. 
As  it  is  found  that  the  preparation  of  an  alloy  of  copper  and  nickel,  for  the  manufac- 
ture of  so-called  German- silver,  impairs  the  most  valuable  properties  of  nickel — its 
white  colour  and  resistance  to  chemical  action — the  obtaining  of  pure  metallic  nickel  is 
t)referred. 
^uieiUn'"o?So"  ^'  ^^®  Operation  is  carried  on  (a)  for  regulus,  when  the  nickel-ores  are 
Niekei  Ores.  mixed  with  iron  pyrites  and  magnetic  pyrites,  and  consists  in  smelting  the 
previously  partly  roasted  ore  with  quartz  or  substances  rich  in  sihca.  During  the  process 
the  greater  portion  of  the  oxide  of  iron  generated  is  absorbed  by  the  slag,  while  the  nickel, 
also  first  oxidised,  and  more  readily  reduced  than  the  oxide  of  iron,  is  converted  to  the 
metaUic  state  and  taken  up  by,  and  concentrated  in,  the  regulus,  a  mixture  of  undecom- 
posed  sulphnrets  of  metals  and  reduced  sulphates.  If  at  the  same  time  the  ore  contains 
copper,  that  metal  is  even  more  readily  and  completely  incorporated  with  the  regnlua  than 
the  nickel  itself.  If  the  roasted  mass  contains  too  much  protoxide  of  iron,  a  portion  of  that 
metal  is  reduced,  and  either  taken  up  by  the  regulus,  or  separated  as  containing  nickel. 
The  separation  of  the  iron  from  the  regulus  frequently  requires  the  application  of  a  refining 
furnace  provided  with  a  blast  so  as  to  oxidise  the  iron.  A  better  result  is  obtained  by 
treating  the  previously  roasted  ore  in  a  reverberatory  furnace  with  quartz,  heavy  spar,  and 
charcoal  or  coal;  sulphuret  of  barium  results,  which,  becoming  converted  into  barj'ta,  trans- 
I  1-9  its  sulphur  to  the  oxides  of  nickel  and  copper,  while  the  baryta  forms  with  the  quartz 
mid  protoxide  of  iron  a  readily  fusible  slag.  At  Dillenburg  an  ore  which  ctntains  tb*» 
f.dlphurets  of  nickel  to  about  7*5  per  cent,  and  copper,  is  treated  in  the  fallowing 
iii^umer: — It  is  roasted  in  stacks,  built  not  unlike  coke-ovens;   next  broken   up  and 


NICKEL.  41 

smelted  in  a  low  blast-famace  heated  by  means  of  coke,  no  other  ingredients  being  added, 
as  the  ore  contains  silica,  alumina,  and  lime  in  sufficient  quantities,  so  as  to  obtain  crude 
regains  (I.)  This  crude  regulus  is  next  melted  with  slags  so  as  to  obtain  concentrated 
regains  (II.)  It  is  lastly  submitted  to  the  action  of  a  refining  blast-furnace  in  order 
to  lessen  the  quantity  of  iron,  care  being  taken  to  leave  enough  sulphur  to  keep  the 
refined  regains  (lU.)  brittle;  finally,  the  regulus  is  employed  in  the  manufacture  of  nickel 
and  alloys  of  nickeL    Composition — 

I.        II.       III. 

Nickel ig  24  35 

Copper 13  39  43 

Iron      35  12  2 

Sulphur       33  25  20 

100      100      100 

This  mode  of  operation  is  employed  at  Elefver  (Sweden),  and  in  some  other  localities. 

{fl).  The  smelting  of  nickel  ores  for  the  purpose  of  concentrating  the  metal  in  speiss  is 
applied  when  the  nickel  occurs  in  combination  with  either  arsenic  only  or  with  that 
metal  and  antimony,  such  compounds  being  occasionally  obtained  in  the  operations  of 
smelting  copper,  lead,  and  silver  ores,  and  as  by-products  of  the  smelting  of  metals  not 
containing  arsenic,  as,  for  instance,  in  slags  from  copper-smelting,  in  which  case  there 
is  added  arseniuret  of  iron  (arsenical  iron  pyrites,  FeAs+FeSz,  which  when  heated  by 
itself  splits  up  into  As  and  2FeS).  When  a  mixture  consisting  of  nickel,  iron,  and  arsenic 
is  first  submitted  to  a  partial  calcination,  and  next  to  a  simultaneously  reducing  and 
fnsing  smelting,  the  iron  is  taken  up  by  the  slag,  the  nickel-oxide  is  reduced,  and  the 
arseniates  are  converted  into  arseniurets,  and  as  the  nickel  has  a  greater  affinity  for 
arsenic  than  for  sulphur,  the  speiss  will  also  take  up  that  metal.  If  the  compound 
originally  operated  upon  happens  to  contain  copper,  that  metal  is  present  in  the  speiss, 
from  which  it  may  be  separated  as  a  sulphuret  by  the  addition  of  ordinary  pyrites  to  the 
arsenical  pyrites  during  the  smelting.  By  frequently  roasting  and  smelting  the  speiss, 
aided  occasionally  by  an  oxidising  blast  and  the  use  of  heavy  spar  and  quartz  as  slag,  the 
iron  is  gradually  eliminated.  At  Birmingham,  Hungarian  and  Spanish  nickel  ores  are 
smelted  for  speiss,  these  minerals  containing  on  an  average  from  40  to  55  per  cent 
of  nickel,  and  from  30  to  40  per  cent  of  arsenic,  as  well  as  sulphur,  bismuth,  and 
copper. 

(y).  Smelting  for  the  concentration  of  coarse  copper  or  nickeliferous  pig-iron.  When 
the  quantity  of  nickel  contained  in  the  copper  ores  is  very  small,  the  nickel  accumulates 
in  the  first  portions  of  the  refined  copper  in  such  quantities  as  to  repay  the  trouble  of 
extraction.  M.  Willo  analysed  some  refined  copper,  obtained  from  the  cupriferous  slate 
of  lUechelsdorf,  and  found  it  to  contain  from  7*8  to  13 '6  per  cent  of  nickel ;  occasionally 
the  Borfaoe  discs  of  rosette-copper  contain  crystals  of  protoxide  of  nickel. 

Me£S^Ktekri.°or  of  ^^*  "^^^  ^^  eflfectcd  by  submitting  the  product  of  the  concentra- 

AU4>y«  of  Miekci  aad  oopper.  tion-smeltiug  to  either  (a)  a  dry  method  of  treatment,  or  (b)  a 
hydro>metallurgioal  process. 

(a).  Preparation  of  nickel  by  the  dry  method.  It  appears  that  the  methods  hitherto 
employed  have  not  led  to  very  satisfactory  results ;  it  is  true  that  when  nickel-speiss  is,  as 
snggeeted  by  M.  von  Qersdorf,  repeatedly  roasted  with  charcoal-powder  and  wood- 
afaavings,  oxide  of  nickel  is  obtained,  and  may  be  reduced  by  means  of  coal,  coke,  or  cliar- 
coal;  but  as  this  oxide  is  always  mixed  with  arseniato  of  oxide  of  nickel,  the  metal  also 
contains  arsenic,  and  any  German-silver  made  vdth  it  is  brittle  and  turns  brown  on 
exposure  to  air ;  moreover,  a  small  quantity  of  iron  is  always  present  in  the  nickel  thus 
prepared.  A  better  result  is  obtained  by  the  process  proposed  by  the  late  H.  Boso,  in 
1863,  for  the  preparation  of  the  metal  free  from  arsenic,  and  which  consists  in  mixing 
the  pulverised  speiss  with  sulphur  and  heating  this  mixture,  thereby  forming  sulphuret  of 
nickel  and  sulphuret  of  arsenic,  the  latter  being  volatilised.  This  operation  is  repeated 
as  often  as  may  be  necessary ;  the  sulphuret  of  nickel  is  roasted,  and  sulphate  of  protoxide 
of  the  metal  is  formed,  which,  at  a  high  temperature,  as  is  the  case  with  protosulphate  of 
iron,  loses  its  sulphuric  acid,  leaving  the  oxide  of  nickel  to  be  reduced  to  the  metallic 
state  by  means  of  charcoal.  At  Dillenburg  experiments  have  been  made  in  order  to 
obtain  from  what  is  termed  a  refined  stone — a  compound  of  nickel,  copper,  iron,  and 
sulphur — an  alloy  of  nickel  and  copper,  by  first  coraplotoly  calcining  the  sulphurets,  and 
so  driving  off  the  free  sulphur;  next  mixing  the  remainder  of  the  substance  in  quantities 
of  100  lbs.  with  45  lbs.  of  soda,  and  submitting  this  mixture  to  the  heat  of  a  reverberatory 
furnace  in  order  to  render  the  sulphur  soluble  in  water  as  sulphuret  of  Hodium  aitil 


42  CHEMICAL  TECHNOLOGY. 

sulphate  of  soda,  leaving  an  alloy  which,  of  courBe,  has  to  he  refined  in  order  to  eliminate 
the  last  traces  of  iron. 

(b).  Ohtaining  nickel  hy  the  wet,  or  hydro-metallurgical  method.  A  preliminary 
roasting  of  the  ores  or  products  of  metallurgical  operations  containing  nickel  is  required 
in  order  to  convert  the  iron  into  an  oxide  soluhle  in  acid,  and  to  convert  the  nickcQ, 
copper,  and  cobalt,  either  into  sulphates  soluble  in  water  or  into  oxides  or  basic  salts, 
both  of  which  are  soluble  in  sulphuric  and  hydrochloric  acids.  From  any  such  solution 
the  nickel  is  precipitated  by  a  suitable  reagent  either  as  oxide  or  as  snlphuret,  and  from 
these  materials  metallic  nickel  or  an  alloy  of  that  metal  with  copper  is  prepared.  The 
preparation  of  nickel  by  the  moist  method  consists  of  three  different  operations : — 
I.  The  preparation  of  the  nickel  solution.  When  nickeliferous  metallurgical  produets 
are  roasted,  either  with  or  without  the  addition  of  copperas,  the  result  is  the  formation  of 
the  sulphates  of  iron,  copper,  nickel,  and  cobalt,  and  this  mixture  when  roasted  becomes 
decomposed,  the  sulphuric  acid  being  driven  off  first  and  most  readily  from  the  sulphates 
of  the  oxides  of  iron,  and  with  greater  difficulty  from  the  sulphate  of  protoxide  of  cobalt. 
Accordingly,  after  roasting,  the  mass  on  being  treated  with  water,  yields  the  larger  portion 
of  the  nickel  and  cobalt  with  some  of  the  copper,  while  the  greater  part  of  the  latter, 
with  very  small  quantities  of  cobalt  and  nickel  and  the  whole  of  the  iron,  remain  undis- 
solved as  oxides ;  by  the  use  of  acids  the  protoxides  of  copper  and  nickel  are  extracted 
from  this  residue.  If  the  roasted  material  is  immediately  treated  with  hydrochloric  acid, 
the  result  is  that  more  of  the  oxide  of  copper  than  of  the  protoxide  of  nickel  is  dissolved ; 
but  by  again  treating  the  residue  with  boiling  acid  the  oxides  of  iron  and  nickel  are 
extracted.  Speiss  may  be  used  for  obtaining  a  nickel  solution  by  first  heating  the  previ- 
ously roasted  speiss  with  a  mixture  of  soda  and  nitrate  of  soda»  next  extracting  the 
arseuiate  of  soda  by  means  of  water,  and  afterwards  treating  the  residue  with  sulphuric 
acid,  roasting  the  sulphates  obtained  so  as  to  decompose  only  that  of  iron,  and  finally 
treating  the  mass  again  with  water  to  obtain  the  sulphates  of  nickel  and  cobalt  in  solution. 
According  to  Professor  Wohler's  plan,  the  arsenic  of  the  speiss  can  be  removed  by  fusion 
with  sulphuret  of  sodium  and  a  subsequent  treatment  with  water,  in  which  it,  as  a  sulpho- 
salt,  is  soluble.  2.  The  nickel  may  be  precipitated  from  the  solution  in  various 
ways.  According  to  M.  Stapff's  plan  (1858),  a  fractioned  precipitation  maybe  obtained 
by  means  of  chaXk  employed  at  various  temperatures,  the  result  being  that  first  iron 
and  arsenic,  and  next  copper,  are  separated,  so  that  only  the  nickel  remains  in  solution, 
and  can  be  thrown  down  by  milk  of  lime.  According  to  M.  Louyet  (1849),  iron  and 
arsenic  are  first  precipitated  by  milk  of  lime  mixed  with  bleachmg-powder,  and  the 
liquid  containing  this  precipitate  filtered  off.  From  the  acid  filtrate  the  bismuth,  lead, 
and  copper  that  may  be  present  are  removed  by  sulphuretted  hydrogen ;  the  filtrate  from 
these  joint  sulphides  is  next  boiled  with  bleaching-powder,  the  cobalt  being  separated  as 
a  peroxide,  and  the  nickel  remaining  in  solution.  If  it  is  desired  to  obtain  the  cobaltie 
peroxide  in  a  pure  state,  the  precipitation  should  be  so  conducted  as  to  leave  a  little 
cobalt  with  the  nickel,  no  injury  therefrom  accruing  to  that  metal.  At  Joachimsihal, 
Bohemia,  the  nickel  is  precipitated  from  the  acid  solution  after  the  removal  of  the 
copper  by  sulphuretted  hydrogen,  by  means  of  bisulphate  of  potassa  as  bisulphates  of 
protoxide  of  nickel  and  potassa,  leaving  the  cobalt  in  solution  free  from  nickel,  which  iu 
its  turn  is  thrown  down  by  carbonate  of  soda.  3.  The  conversion  of  the  nickeliferous 
precipitate  into  metal,  or  into  an  alloy  with  copper,  may  be  carried  out  in  the  following 
manner.  The  protoxide  of  nickel  is  first  separated  from  the  liquid  by  filtration,  then 
pressed  so  as  to  admit  of  its  being  dried  by  intense  heat,  and  next  ground  up  with  water 
and  washed  with  very  dilute  hydrochloric  acid,  in  order  to  remove  the  gypsum,  of  which 
some  8  to  12  per  cent  is  mixed  with  the  oxide.  The  oxide  is  then  made  with  beet-root  sugiu-, 
molasses,  and  coarse  rye-meal  into  a  stiff  paste,  which  is  shaped  into  cubes  from 
I '5  to  3  centimetres  in  size;  these  cubes  are  next  rapidly  dried,  and  after  drying  are 
placed  with  charcoal  powder  in  crucibles  or  in  perpendicular  fire-clay  cylinders,  where 
being  submitted  to  a  very  strong  white  heat,  the  metal  is  reduced ;  an  operation  which,  in 
the  case  of  the  alloy  of  copper  and  nickel,  or  of  cupriferous  nickel,  is  finished  in  i|  hours, 
the  reduction  of  the  pure  metal  taking  fully  three  hours.  The  copper  soon  becomes 
molten,  but  the  nickel  only  sinters  together  on  account  of  the  very  great  infusibility  of 
this  metal.  The  small  cubical  pieces  of  nickel  as  met  with  in  commerce  exhibit  externally 
a  strong  metallic  lustre,  produced  by  putting  the  cubes  with  water  into  casks,  which  are 
made  to  rotate.  In  order  to  ensure  uniformity  of  composition,  and  hence  a  good  sale  for 
the  alloy  of  copper  and  nickel,  rosette-nickel,  care  is  taken  to  procure  the  mixture  of 
the  two  metals  in  the  proportion  of  66*67  P^^  ^^^^  copper  and  33*33  per  cent  nickel,  while 
the  cubical  nickel  contains  from  94  to  99  per  cent  of  pure  met^U.  At  a  nickel-oven  at 
Dillenburg,  the  metal  is  not  made  into  cubes,  but  treated  in  the  same  way  as  rosette- 
copper. 


COPPER.  43 

propert'Mof  KiekeL  Pure  nickel  has  a  nearly  silver- white  colour,  with  a  slight 
jellowish  hue,  is  very  difficult  to  melt,  rather  hard,  very  ductile,  and  easily  polished ; 
sp.  gr.  =  8*97  to  9*  26.  When  quite  pure  this  metal  may  be  drawn  into  wire,  rolled 
into  sheets,  hammered,  and  forged ;  its  tensile  strength  stands  to  that  of  iron  as  9  : 7. 
Nickel  is  analogous  to  iron,  but  distinguished  from  it  by  possessing  a  greater  power 
of  resisting  chemical  agents ;  on  this  account,  and  for  its  not  becoming  rusty  in  air  or 
when  in  contact  with  water,  nickel  is  used  for  obtaining  silver-like  alloys  (see 
Copper).  In  Belgium,  Switzerland,  the  United  States,  and  Jamaica,  small  coins 
have  been  made  of  an  alloy  of  nickel  with  zinc  and  copper,  pure  nickel  being  too 
bard  to  admit  of  readily  coining.  An  alloy  known  as  tiers-argent,  one-third  silver, 
consists  in  100  parts  of: — 

ouLver  •••     •••     •••     •••     •••     •••     Z7  3^ 

Copper       59*0^ 

Mi\i\G    •••      •••      •••      •••      •••      •••       9  j7 

i^\C]aML»»»        •••         •••         •••        •••        •••  ^  4^ 

9961 

The  total  annual  production  of  nickel  on  the  continent  of  Europe  amounts  (1870) 
to  11,200  cwts.,  exclusive  of  what  is  made  in  England.  Very  pure  nickel  is  obtained 
at  Val  B6noit,  near  Luik,  Belgium,  from  an  Italian  nickel  ore,  the  metal  containing 
less  than  i  per  cent  impuriticB. 

Copper. 

(Cu==63-4;  Sp.gr.  =  8-9.) 

*'*''**''^  tow."****^  Copper  is  one  of  the  metals  met  with  most  abundantly.  It  has 
been  known  from  a  very  remote  antiquity — even  before  iron — and  bears  tlie  Latin 
name  Cuprum^  because  it  was  obtained  by  the  Romans  and  Greeks  from  the  Island 
of  Cyprus ;  from  the  Latin  name  of  this  metal  the  English,  German,  Dutch,  and 
French  names  are  derived.  Copper  is  found  to  some  extent  in  a  metallic  state 
naturally,  but  it  is  chiefly  obtained  from  ores,  among  which  the  oxides  and  sulphides 
are  the  chief. 

On*  of  Copper.  Native  copper  is  found  in  large  quantities  near  Lake  Superior,  in  North 
America;  and  in  Chili  there  is  known  a  peculiar  kind  of  sand  called  copper-sand,  or 
eopper-barilla,  consisting  of  from  60  to  80  per  cent  of  metallic  copper  and  20  to  40  per 
cent  of  quartz.  This  sand  is  imported  into  England  and  smelted,  vdth  other  copper  ores, 
at  Swansea. 

Bed  copper  ore  (suboxide,  or  red  oxide  of  copper),  GuaO,  containing  88*8  per  cent  of 
copper,  is  met  with  in  octahedrical-shaped  crystalB,  disseminated  or  instratiiied  through 
rock  in  Cornwall.  An  intimate  mixture  of  suboxide  of  copper  and  iron-ochre  is  known  as 
tile-ore,  or  earthy  red  oxide  of  copper.  Azurite,  or  blue  copper  ore,  containing  55  per 
cent  of  copper,  is  a  compound  of  carbonate  of  protoxide  of  copper  and  hydrated  protoxide 
(2CuC0|-|-CuHa02.  It  occurs  in  beautifully  blue-coloured  crystals  disseminated  through 
rock  and  gangue  in  Cornwall,  and  was  formerly  found  at  Chessy,  near  Lyons. 

Malachite,  containing  57  per  cent  of  copper,  consists  of  basic  carbonate  of  hydrated 
oxide  of  copper  (CUCO3-HCUH2O2),  and  occurs  inrhoinbio  crystals,  also  as  stalactite  and 
stalagmite,  and  in  Atlas  ore,  a  veined  and  earthy  ore  called  copper-green  os  earthy 
malachite,  and  very  frequently  with  azurite  in  Australia  and  Canada. 

Copper-glance,  copper-glass,  sesqniBulphuret  of  copper  (CuaS),  contains  80  per  cent  of 
the  metal.  Purple  copper  ore,  variegated  copper  ore,  a  compound  of  copper-glance  and 
sesquisulphnret  of  iron  (sCu^S-hFeaSj),  with  55 '54  per  cent  of  copper  and  copper  pyrites 
(Cu^S+FeaSj  or  CuFeSa),  with  34*6  per  cent  of  copper  are  the  chief  sulphur  ores  used  in 
the  extraction  of  copper.  Copper  pyrites  is  often  mixed  with  iron  pyrites,  and  also  often 
contains  silver  and  nickel.  The  mineral  known  as  Bonmonite,  although  a  lead  ore,  often 
contains  as  much  as  1276  per  cent  of  copper. 


44  CHEMICAL  TECHNOLOGY. 

Slaty  copper  ore  is  a  bitmninons  marly  schist  belonging  to  the  permian  formation, 
through  which  sulphuretted  copper  ores  are  disseminated ;  this  ore  is  chiefly  found  in 
Germany. 

Grey  or  black  copper  ores,  so  called  Fahl  ores,  are  compounds  consisting  of  electro- 
positive  sulphurets,  viz.,  ^ulphuret  of  copper  and  of  silver,  with  electro-negative 
sulphurets,  viz.,  those  of  arsenic  or  antimony.  As  these  ores  contain  silver  they  are  usually 
considered  as  silver  ores,  the  quantity  of  copper  contained  in  them  amounting  to  about 
14  to  14*5  per  cent.  Atacamite  is  also  a  copper  ore  (3GuH202+Cu0l2)»  containing  56  per 
cent  of  copper.  This  substance  is  chiefly  met  with  in  Chili  and  other  parts  of  the  Western 
Coast  of  South  America,  in  Southern  Australia,  and  in  Peru,  and  in  that  country  it  is 
ground  to  powder  and  used  instead  of  sand  or  sawdust  to  strew  on  the  floors  of  rooms. 
It  is  imported  in  that  state  under  the  name  of  ArsenHlo,  and  is  smelted  with  the  atacamite 
in  lumps  at  Swansea. 

Mode  of  Treating  the  Copper       It  is  quite  evident  that  the  treatment  of  the  ores  must  vary 

Ore^  for  the  Purpose  of  ■•  •  -i  ... 

ExtrActing  the  Met«L  according  to  the  constitution  of  the  metals.  The  ores  in 
which  copper  is  contained  as  oxide,  or  ochrey  ores,  are  reduced  readily  enough  by 
simple  treatment  with  carbonaceous  matter  and  a  flux ;  but  these  ores  are  by  no 
means  abundantly  found,  and  are  therefore  usually  mixed  with  pyritical  sulphu- 
retted ores.    The  smelting  of  copper  from  its  ores  therefore  embraces : — 

1.  The  smelting  from  ores  containing  oxides, 

2.  From  pyritical  ores,  and 

3.  The  hydro-metallurgical  method. 

Pyritical  copper  ores  are  smelted  either  in  a  shaft,  or  pit-fumace,  or  in  a  reverbera- 
tory  furnace,  in  the  latter  instance  the  reduction  of  the  metallic  regulus  of  copper, 
obtained  from  a  previous  roasting  of  the  ore,  is  effected  by  the  aid  of  sulphur,  not  by 
that  of  coal.  The  regulus  is  gradually  rendered  richer  and  richer  in  metal,  until  at 
last  the  decomposition  of  the  sulphur  is  completed  by  the  action  of  the  oxygen  of  tlie 
air ;  by  this  operation  suboxide  is  plentifully  formed,  and  as  a  consequence  the  metallic 
copper  obtained  is  in  the  state  technically  termed  '*  over-reflned."  When  the  shaft- 
furnace  is  employed,  the  first  portion  of  the  operation  is  similar  to  that  alluded  to, 
but  the  metal  is  reduced  with  coal  or  charcoal,  and  hence  the  copper  obtained — 
leaving  out  of  the  question  the  presence  of  the  foreign  metals — ^is  never  over-refined, 
but  contains  carbonaceous  matter,  so  that  in  order  to  render  the  copper,  as  it  is 
technically  termed,  tough — ^that  is  to  say,  malleable  when  cold  as  well  as  when  hot, 
another  operation  is  required,  which  it  is  evident  from  the  foregoing  must  differ  for 
the  two  qualities  of  crude  metal. 
TheWorkinu-npofthe      The  orcs  are  first  roasted  or  calcined,  and  a  portion  of  the 

Copper  Ores  in  tha 

Shaft  Furnace.  sulphuT,  arsenic,  and  the  antimony  they  contain  volatilised ;  sul- 
phates of  the  metals  as  well  as  arscniates  and  antimoniatcs  are  at  tlie  same  time 
formed,  while  a  portion  of  the  ore  is  not  acted  upon  at  all.  Wlien  the  smelting 
operation  is  commenced,  fluxes  are  added,  and  any  oxide  of  copper  present  is  reduced 
to  the  metallic  state,  while  simultaneously  the  sulphates  are  again  converted  into 
sulphurets,  which  jointly  with  the  metallic  copper  form  the  rather  richer  crude 
regulus  of  copper ;  whUe  if  arsenic  and  antimony  prevail  speiss  is  formed.  The 
more  readily  oxidised  metals  present,  chiefly  iron,  form,  as  protoxides,  compounds 
with  the  fluxes.  By  a  repetition  of  this  process  vdOi  the  coarse  metal  regulus — ^tlie 
operation  being  known  as  a  concentration- smelting — ^there  are  obtained  tliin  matt, 
and  what  is  termed  black  copper,  containing  foreign  metals,  wliich  are  got  rid  of  by 
a  first  or  coarse  refining,  a  portion  of  the  impurities  under  the  influence  of  a  high 
temperature,  the  oxygen  of  the  air  and  fluxes,  being  partly  volatilised,  pai-tly  taken 
up  in  the  slag.    The  copper  obtained  by  tliis  operation,  rose-  or  disc-copper,  contains. 


COPPER. 


45 


becaose  the  calcination  is  carried  rather  too  far.  suboxide  of  copper,  which  impnira 
the  dnctility  of  the  melal.  This  defect  is  remedied  hy  a  rapid  smeltiBg  under  a 
layer  of  charcoal,  the  suboxide  being  reduced  and  touph  copper  obtained.  Wlien  a 
rererberatoiy  furnace  la  employed,  the  coarse  and  last  refJiiinga  are  usually  included 
in  one  process . 

According  to  the  continental  methods,  the  calcined  ore  is  smelted  and  converted 
into  coarse  regulua  in  a  shaft-furnace,  the  fuel  employed  being  charcoal  or  coke,  or  a 
mixture  of  the  two.  Fig.  iS  exhibits  the  vertical  section  of  the  furnace  ;  Fig.  19  is 
a  front  view,  the  front  wall  being  removed  to  show  the  interior  construction.  Fig.  20 
exhibits  the  lower  part  of  this  furnace;  (  (  are  the  tuyere-holes  for  the  blast;  the 
apertures,  o  o,  placed  just  above  the  lowest  part  of  the  breast  of  the  hearth,  communi- 
cale  by  means  of  channels  with  the  smelting-pots,  c'  c',  the  object  being  to  gradually 
collect  the  molten  contents  of  the  furnace  Smco  copp  r  ores  always  contom 
more  or  less  iron,  it  might  happen  that  by  simph  employing  a  reducmg  smeltmg 
some  of  that  metal  would  become  mixed  with  tlie  copper  m  order  to  avoid  this 
fluxing  materials  rich  m  sihca  are  added  with  ^\hich  the  protoxide  of  iron  forms  a 

Fig.  18. 


readily  fusible  slag.     The  oxides  of  copper  present  in  tlie  calcined  materials  are 
reduced  to  the  metallic  state  by  the  sulphuret  of  iron — 

3CUO  +  FeS  =  S0,+ FeO+ 3CU. 
The  metal  regulns.  a  mixture  of  sulphnrets  of  copper  and  iron  and  other  metals,  con- 
taining on  an  average  32  per  cent  of  copper,  collects  in  tlie  lower  part  of  the  fomace, 
snd  the  slag  formed  is  called  crude  or  coarse  slag.  The  roasting  of  the  regulus  aims 
« ita  most  complete  oxidation,  while  the  sulphur  is  eliminated.  The  calcined  regulus 
is  next  smelted  in  a  shaft  furnace  with  the  addition  of  a  flux,  a  process  technically 
known  as  concentration- smelting.*  Tlie  refined  regulus  obtained  by  this  smelting 
eontains  some  50  per  cent  of  copper,  and  is  next  treated  to  obtain  black -copper,  coarse 
melal.  But  if  the  regulus  contain  a  sufficient  quantity  of  silver,  that  metal  is 
extracted  by  methods  which  will  be  fully  elucidated  when  silver  is  treated  of;  in 
Mme  cases  this  operation  is  combined  with  the  extraction  of  lead  from  the  copper, 
»nd  effected  by  what  is  termed  Uqnation,  of  which  more  presently. 

'  There  are  no  oquitUcnt  terms  in  English  to  express  tho  real  meaning  of  the  German 
woidg,  a  (act  which  is  readily  accouuted  for,  if  we  consider  that  these  operations  are 
Msentially  Uciman  and  of  very  ancient  ittauding. 


46  CHEMICAL    TECHNOLOGY. 

The  operation  of  Bmelting  for  a  refined  regoIuB  is  omitted  if  tolerablj  pure  copp«r 
ores  are  operated  upon,  and  suck  ores  Sifter  calcination  are  immediate!;  treated  in  » 
low  blaat-fiimoce  to  obtain  the  lila«li- copper.  In  addition  to  black-copper,  a  thin 
matt  coutaining  from  93  to  95  per  cent  of  that  metal  is  obtained.  As  an  instance  of 
the  composition  of  blaok-copper,  we  quote  Dr.  Fach's  analysis  of  a  sample  of  that 


o  parts  there  a 


material  prodnced  at  Mansfeld,  in  18G6 ; 

Copper       9349 

Nickel  and  cobalt  together 

Silver 

Sulphnr      

9975 
TO".      The  black-copper  ia  next  submitted  to  an  energetic  oxidising 
Iting  process  in  older  to  get  rid  of  Ibe  impurities  in  the  slag.     This  procCGS  is 


carried  on  either— 


1.  In  a  small  refining  furnace ; 

2.  In  a  large  refining  furnace ;  or 

3.  In  a  reverberator^  furnace. 

This  operation  is  effected  in  a  furnace  or  bearth,  represented 
Fig.  31,  and  in  perspective  in  Fig.  32;  a  is  a  semi -globular 

Fio. 


excavation,  termed  the  crucible ;  6  is  a  cast-iron  bed-plate ;  h  represents  one  of  the 
two  tnjeres  by  means  of  which  a  blast  is  conveyed  to  the  fuel  and  the  suHace  of  the 
copper.  The  black  or  coarse  copper  is  melted  bj  the  heat  of  charcoal  aided  by  the 
blast,  the  sulphur,  arsenic,  and  antimony  being  volatilised,  while  the  oxides  of  iron 
and  of  the  other  non-volatile  metals  are  token  up  with  the  suboxide  of  copper  by  the 
slag,  which  gathers  at  the  sur&ce  of  the  molten  metal,  and  is  from  time  to  time 
removed.  As  soon  as  the  refining  is  complete,  the  blast  is  turned  off  and  the  surface 
of  the  copper,  the  metal  being  heated  far  above  its  melting-point,  covered  with 
charcool-dost.  When  cooled  sufficiently,  water  is  poured  on,  and  a  portirai  of  the 
metal  thus  suddenly  solidified  admits  of  being  lifted  off  from  the  rest  of  the  molten 
mass  in  cakes  or  discs,  technically  known  as  rose  or  rosette -copper ;  this  <^>eration  is 
repeated  until  the  crucible  contains  no  more  metal. 

"i£S™l!Si.''  -A*  U)«  refining  of  copper  on  the  bearth  has  Ifflln  found  to  yield  but 
poor  results,  another  contrivance,  shown  in  vertical  section  in  Fig.  23,  ia  now  more 
generally  employed,    a  is  the  smelting- hearth ;  b  the  refining  crucible,  of  which  there 


COFFER. 


47 


are  two;  n,  the  opening  lot  the  tuyere  of  the  bloat;  I,  the  furnace.  The  mode  of 
operation  is  similar  to  thatjuat  given.  When  thereliningis  complete  the  molten  metal 
is  run  into  the  cruciblea,  and.  after  having  cooled  Bufflciently,  water  is  epTinkled  on  and 
the  discs  of  roBC-copper  lifted  off.  For  the  reason  that  in  this  kind  of  reverberatory 
fnmace  the  copper  is  not,  as  is  the  case  on  the  hearth,  in  contact  with  the  fuel,  the 
lefnilt  is  iL  purer  metal. 

tOflmiioB  ptocm.  When  the  copper  ores  contain  silver,  the  black  copper  is  submitted, 
before  being  reRned,  to  a  process  known  as  liquation,  unless  it  should  be  preferred  to 
extract  the  silver  by  the  Ziervogel  method  (see  Silver).  The  hquation  process  is 
based  upon  the  fact  that  lead  and  copper  may  be  melted  together,  hut  do  not  remain 
alloyed  on  cooling,  so  that  a  compound  is  formed  containing  much  more  copper  than 
lead,  the  remainder  of  the  lead  separating  and,  while  taking  up  the  silver,  settling 
down  in  consequence  of  its  specific  gravity.  When  the  molten  mass  is  slowly  cooled, 
the  lead  combined  nith  the  silver  runs  off  after  the  solidification  of  the  copper ;  hot 
if  the  molten  metals  are  rapidly  cooled,  an  intimate  mixture  of  the  two  takes  place. 
The  mode  of  separating  the  silver  from  the  lead  will  be  referred  to  when  treating  of 
the  former  of  these  metals. 

It  has  been  alreadj  mentioned  that  the  refined  copper  reBolting  from  the  above  proceBBes 
contains  aaboiide  of  that  metal,  which,  if  amounting  to  a  quantity  of  I'l  per  cent,  renders 
the  copper  nnfit  for  use  at  ordinary  temperatures,  by  impairing  its  ductiUty  and  mollea- 
hiiity;  while  if  the  quantity  ot  the  suboxide  amonnte  to  ti  per  cent,  the  metal  la  nnfit  for 


oie  both  cold  and  at  a  red  heat — that  is,  becomes  cold-  and  red-short.  This  condition  ot 
the  metal  is.  in  Germany,  termed  "  over- cooked,"  and  the  remedy  is  simply  to  melt  the 
copper  and  submit  it  to  what  ie,  in  England,  technically  known  as  poling  ;  that  is  to  say, 
a  snfficiently  long,  stont,  and  green  piece  of  wood,  ia  lued  for  thoroughly  stirring  up  the 
molten  masH.  The  ratiomtU  is  that  the  Carbon  and  hydrogen  contained  in  the  wood 
deoxidise  the  anboiide  at  the  high  temperature,  rendering  the  metal  veiy  malleable  and 
dnctile.  makiag  it,  as  is  technically  termed,  toii^A.  A  sample  of  Mansfetd  refined  and 
loaghened  copper  was  found  by  Dr.  Steinbeck  (o  contain  in  loo  parts  :— 

Copper 94-37 

Silver      o-oi 

Niokel 0-36 

Oiygeu 058 

Snlphui 0-02 


sLujUDf.      Owing  chieSy  to  the  possession  of  an  enormous  wealth  of  coal,  the 
It  suited  for  the  reverberatory  fnmacca,  a  method  of  copper- smelting  peculiar 


48  CHEMICAL  TECHNOLOGY. 

to  England  is  puraiied,  and  b.  metal  obt^ued  of  n  rery  superior  quali^.  aJthongh  not 
ao  good  BB  tliat  extracted  from  particulax  ores  in  Russia  and  Australia,  Swans(^a  is 
the  cliief  and  most  important  seat  of  this  industry  in  the  United  Kingdom,  and  to  it 
copper  ores  are  not  only  carried  Irom  Cornwall,  North  Wales,  Westmoreland, 
Anglesea.  and  other  portions  of  the  realm,  Ireland  included,  hnt  are  imported  from 
Chili,  Peru,  Cuba,  Norway,  Australia,  and  other  parts  of  the  world.  The  English, 
ores  are  mainly  pyritical. 

The  chief  procesBes  of  this  mode  of  smelting  ooneist  in — i.  Calcination  of  the  ore; 
2.  Smelting  for  coaree  metal;  3.  Calcination  of  coarse  metal;  4.  Making  of  nhite  metal,  a 
concentration  process  in  whieh  calcined  coarse  metal  is  smelted  with  rich  ores;  5.  Prepa- 
tion  of  the  bine  metal  by  smelting  together  oolcined  coarse  metal  and  calcined  ores  of 
medium  richness  ;  6,  Preparation  of  a  red  and  white  metal  by  smelting  together  the  slaga 
of  the  prerioud  operations  ;  7.  Calcination  of  the  bine  metal  (5)  and  preparation  of  whlto 
extra  metal ;  8.  CalcinBtion  of  the  white  extra  metal  and  preparation  of  the  ooncentration 
metal;  9.  Calcination  of  the  ordinary  white  metal  of  ouprifeioas  residues  for  the  purpose 
of  obtaining  blistered  ooppei.  According  to  M.  Ourlt's  views,  all  these  operations  may  be 
reduced  to,  at  most,  two  calcinations  and  three  smelting  operations,  viz. :— r.  Calcioatioa 
of  the  previously  polveriaed  ores  with  the  addition  of  oommun  salt,  or  of  chloride  of 
calcium,  to  form  volatile  chlorides;  I.  The  smelting  of  calcined  ores  and  obtainiog  a  more 
hquid  slag  and  a  coarse  metal;  3.  The  calcination  of  coarse  metal  by  the  aid  of  a  blast  for 
the  production  of  blistered  copper  with  or  without  the  addition  of  chlorides;  4.  Befining 
and  toughening  Uie  blistered  copper. 

caictuini.'n'niiHtiiig       This  operation  as  carried  on  at  Swansea  does  not  materially  differ 
uwOth,  from  that  pursned  on  the  Continent.      Mo  very  appreciable  loss  of 

weight  is  etpeiieneed,  as  the  weight  of  the  osygen  taken  up  compensstes  for  the  loss 
occasioned  by  the  more  or  less  complete  volatilisation  of  the  aulphnr,  antimony,  arsenic, 
iSc.  The  roasted  ore  is  block,  this  colour  being  due  to  the  oxidea  of  iron  and  oopper- 
Durin);  the  roasting  heavy  white  femea  ore  emitted,  consisting  of  sulphnrousand  arseuious 
acids  mixed  with  other  substances ;  more  recently,  calcining  furnaces  have  been  con- 
structed on  Oorstenhofer's  patent  system,  so  as  to  admit  of  the  utilisation  of  the  snl- 
phnrous  acid  for  the  mannfaeture  of  snlphnric  acid. 

smciuu!  tho  OM.  This  operation  is  Iffected  at  Swansea  In  a  furnace  of  which  Fig.  34 
eihibits  a  sectional  view,  e  is  a  funnel  intended  for  the  introduction  of  the  roasted  ore ; 
o  is  on  ash-pit  filled  with  cold  water.    The  object  in  view  is  to  separate  the  oree  from 

Fio.  24. 


the  gangoe  as  well  as  from  oudes  other  than  that  of  copper,  by  cansing  the  sulphur  of  the 
BUll^urets  remaining  undecomposed  to  act  apon  a  portion  oC  the  oxides  and  snlpbates  in 
SD<di  a  manner  that  theee  ore  either  taken  up  by  the  slag,  as,  for  instance,  the  oxide  of 
iron,  or  aro  again  reduced  to  sulphide,  as  the  oxide  and  sulphate  of  copper.  At  a  higher 
temperature  the  oxide  of  eopjH-r  is  reiluci^d  to  the  metallic  state  by  the  action  of  the 
sulimuretB  of  iron  and  copper,  oxide  of  iron  forming,  and  the  metallic  copper  being  partly 


COPPER.  49 

taken  up  by  the  regnlnB,  partly  converted  into  suboxide  again  by  the  peroxide  of  iron, 
which  is  converted  into  protoxide  and  dissolved  by  the  siliceons  matter.  The  prodnot  of 
the  first  stage  of  the  smelting  is  a  coarse  metal,  regulns. 

BoMtii«orCaidiiiiw  ^^^  roasting  of  the  coarse  metal  is  performed  in  the  reverberatory 
a»  couM  MeuL  furnace  used  for  the  first  calcination  of  the  ores.  The  objects  in  view 
are  the  oxidation  of  any  metallic  iron  present,  and  the  partial  volatilisation  and  combus- 
tion of  tiie  sulphur,  partial  only,  for  otherwise  the  smelting  for  white  metal  would  be 
impeded  or  not  performed  without  serious  loss  of  copper. 

ftTHni  frrr  TiTittn  ^^  Operation  consists  in  mixing  the  previously  calcined  coarse 
ZsteL  metal  with  rich  copper  ores  containing  har^y  any  sulphuret  of  iron, 

but  consisting  chiefly  of  the  sulphide  and  oidde  of  copper  mixed  with  quartz  in  such  pro- 
portion that  the  pyrites  (copper)  is  oxidised  by  the  oxygen  of  the  oxides  present,  the  result 
being  that  all  the  copper  combines  with  the  coarse  metal,  while  the  protoxide  of  iron 
forms  with  the  quartz  Eolicate  of  protoxide.  The  white  metal,  almost  entirely  consisting 
of  (GoaS),  is  run  into  cakes  in  sand-moulds. 

Bitatexvd.  or  Gnuie  The  white  metal  obtained  is  converted  into  blistered  copper  by  placing 
^^v«-  it  on  the  hearth  of  a  reverberatory  furnace  and  causing  the  fire  to  act  at 
first  rather  gently,  but  afterwards  so  as  to  fuse  the  mass,  the  total  duration  of  the 
process  for  each  charge  being  12  to  14  hours;  the  result  is  the  volatilisation  of  the 
sulphnr  in  the  form  of  sulphurous  acid,  and  the  elimination,  partially  by  volatilisation, 
partially  by  their  being  taken  up  in  the  slag,  of  such  impurities  as  arsenic,  cobalt,  nickel, 
tin,  iron,  &c.  When  the  mass  becomes  fused,  suboxide  of  copper  and  sulphide  of  copper 
mutuaUy  decompose,  the  result  being  the  formation  of  sulphurous  acid  and  metallic 
copper,  {2CuaO-hCu2S=S02+6Cu). 

The  molten  coarse  metal,  impure  copper  as  yet,  is  run  into  moulds,  and  its  surface 
beeoming  covered  with  black-coloured  vesicles,  due  to  the  escape  of  gases  and  vapours 
from  the  molten  metal,  it  is  termed  blistered  copper.  On  being  broken,  after  cooling,  it 
exhibits  a  honeycombed  structure,  due  to  the  same  cause  that  produces  the  blistered 
appearance  on  the  surface.  Blistered  copper,  as  usually  obtained,  is  comparatively  pure. 
Bcflniagthe         The  Ust  Operation  in  the  English  method  of  copper-smelting  is  the 

Biiatei^^etaL  refining  of  the  blistered  metal  in  a  reverberatory  furnace,  care  being  again 
taken  to  fire  at  first  gently,  so  that  the  metal  shall  not  become  molten  until  after  some 
six  hours.  Aa  soon  as  the  entire  charge  is  thoroughly  melted  down,  the  slag,  rich  in  sub- 
oxide of  copper,  is  tapped  off  and  the  molten  metal  covered  with  charcoal-powder.  The 
operation  of  poling  (see  above)  is  then  performed,  birch-wood  being  preferred  for  the 
parpose ;  this  done,  tne  copper  having  been  run  into  moulds  of  a  rectangular  shape,  is 
known  as  refined  tough  cake. 

*twSno^S!?8iS?'*'  Copper  is  readily  obtained  from  oxidised  ores  by  smelting  them 
in  a  ahaft-fomace  with  coke  or  coal  and  such  flaxes  as  will  produce  a  slag  which  docs 
not  absorb  copper.  The  crude  metal  obtained  is  refined  in  a  low  blast-furnace.  The 
smelting  of  oxidised  ores  is  limited  to  a  few  locaUties,  among  which  the  Oural  and 
Siberian  works  are  the  most  important.  Large  quantities  of  excellent  and  very  rich 
oxidised  copper  ore  are  found,  but  not  as  yet  wrought,  in  the  Islands  of  Timor  and 
Tunor-Laout  and  the  adjacent  islands  of  Polynesia. 

"'^fJSJSgJ'^JJJ.^  This  method  owes  its  existence  to  the  application  of  practical 
and  analytical  chemistry  to  metallurgy.  As  copper  is  very  readily  obtained,  even 
from  ores  too  poor  to  admit  of  being  treated  by  the  dry  process,  in  such  a  state  of 
combination  as  to  admit  of  its  being  dissolved  in  water,  and  thrown  down  from  this 
solution  by  the  simple  presence  of  metallic  iron,  the  hydrometallurgical  process  is 
often  advantageously  applied.  One  of  the  oldest  of  hydrometallargical  methods  is 
that  known  as  the  cementation-process,  performed  by  precipitating  copper  from  a 
solution  of  the  sulphate  of  the  metal  by  means  of  metallic  iron.  Solutions  of  the 
sulphate  occur  naturally  in  some  mines,  and  are  also  artificially  prepared  by  treating 
poor  oxidised  copper  ores  with  sulphurous  acid,  or  by  exliausting  these  ores  with 
hydrochloric  or  dilute  sulphuric  acids,  or  by  roasting  pyritical  ores  and  exhausting 
them  with  water.  The  copper  obtained  by  this  process  is  called  cementation-copper. 
^  the  Island  of  Anglesea  the  cementation  liquid  is  conducted  first  into  large  basins 
ui  order  that  the  oclirey  and  other  suspended  matters  may  subside,  and  afterwards  is 

K 


50  CHEMICAL  TECHNOLOGY, 

nm  into  the  oementation-taiikB  containing  old  sorap-iron  intended  to  serve  as  a  pre- 
cipitating agent.  This  scrap-iron  is  oooasionally  stirred  up,  so  as  to  renew  the 
metallic  surfiEMse  presented  to  the  solution.  The  muddy  liquid,  containing  spon^ 
metallic  copper  and  impurities,  is  run  into  reservoirs  intended  for  the  deposition  of 
the  spongy  mass,  which,  after  the  supernatant  liquid  is  run  off,  is  dried  in  a  furnace. 
The  material  contains  on  an  average  only  15,  hut  may  contain  from  50  to  65  per 
cent  of  copper.  The  main  body  is  usually  composed  of  basic  sulphate  of  iron,  which  is 
effectually  removed  by  the  application  of  stirring-machinery,  such  as  is  used  in 
breweries  in  the  mash-tubs.  At  Rio  Tinto,  Spain,  and  at  Schmollnitz,  Hungaiy. 
cementation-copper  is  prepared  on  a  very  large  scale.  In  Norway,  copper  solutions 
are  treated,  according  to  Sinding's  plan,  with  sulphuretted  hydrogen,  and  the  preciju- 
tate  either  worked  up  for  metallic  copper  or  for  sulphate  of  copper. 

Instead  of  sulphur,  large  quantities  of  iron  pyrites  containing  more  or  less  copper  are 
burnt,  and  the  sulphurous  aoid  obtained  applied  in  the  manufacture  of  sulphuric  add. 
The  spent  pyrites  is  frequently  treated  hydrometallurgically  with  a  solution  of  chloride  of 
iron,  the  copper  being  precipitated  by  means  of  sulphuret  of  iron.  Poor  ochrey  copper 
ores  are  often  worked  up  to  obtain  sulphate  of  copper  by  some  method  suitable  to  the 
locality;  for  instance,  roasting  with  iron  pyrites  or  with  copperas.  It  pays  in  some 
instances  to  roast  pyritioal  copper  ores,  and  after  roasting  to  treat  them  for  obtaining 
cementation-copper. 
Copper  obtainod  by  Copper  clectrolytically  precipitated  is,  provided  pure  materials  are 
voitaiA  EiMtridty.  operated  upon  and  the  galvanic  current  not  too  strong,  the  purest 
obtainable.  This  method  has  been  proposed  and  even  tried  on  a  large  s(»le  in  Italy  in 
order  to  save  time  and  iron,  and  to  throw  down  the  copper  of  the  cementation-tanks. 
It  is  a  generally  known  and  daUy  applied  fact  that  copper,  as  a  coherent  mass,  can  be 
separated  from  sulphate  of  copper  electrolytioally. 

Pn>p«rtiei  of  oopp«r.  The  pecuHar  and  reaUy  beautiful  red  colour  of  copper,  the  only  metal 
80  distinguished,  is  too  well  known  to  need  mention.  It  is,  although  a  hard  and  tough 
metal,  so  ductile  and  malleable  that  it  may  be  drawn  out  to  the  very  finest  wire  and 
beaten  to  extremely  thin  leaves.  Its  malleability  is  increased  by  increase  of  temperature, 
and  at  a  low  red-heat  it  can  be  hanmiered,  rolled,  and  beaten  into  any  required  shape.  Its 
fracture  is  granular.  Its  sp.  gr.  is  n  8'g ;  one  cubic  metre  weighs  about  8900  kilos.  Its 
melting-point,  according  to  Pouillet,  1200°;  to  Daniell,  1400''.  The  latest  and  mof^ 
careful  researches  on  this  topic  have  been  made  by  Dr.  von  Biemsdijk  at  the  Utrecht  Kint, 
and  he  has  found  that  chemically  pure  copper  fuses  in  an  atmosphere  of  hydrogen  at 
133*0° ;  that  is  to  say,  at  a  temperature  higher  than  the  melting-point  of  either  gold  or 
silver,  as  simultaneously  determined  by  an  extensive  series  of  experiments  made  in 
atmospheres  of  hydrogen.  If  properly  poled,  as  the  term  runs,  or  in  other  words,  free 
from  suboxide,  copper,  when  molten,  flows  readily,  but  when  mixed  with  suboxide  the 
flow  is  sluggish.  While  in  the  molten  state  the  surface  of  themetal  exhibits  a  beautiful 
sea-green  colour.  Copper  is  not  suited  for  the  making  of  castings,  and  probably  this 
is  due  to  a  peculiar  effect  of  heat  upon  this  metal,  as  many  of  its  alloys,  especially  those 
with  tin,  are  very  suited  for  casting.  Molten  copper  suffers  great  expansion  on  cooling, 
and  becomes  honeycombed  and  internally  crystalline.  This  defect  can  only  be  remedied  by 
either  keeping  the  metal  while  molten  under  a  layer  of  charcoal,  or  by  cooling  it  to  some 
extent  before  casting  into  moulds,  which  should  be  made  of  a  good  conducting  material,  eo 
as  to  cause  the  rapid  cooling  of  the  metal.  Iron  moulds,  internally  coated  with  a  layer  of 
bone-ash,  are  the  best.  Small  quantities,  o'l  per  cent,  of  zinc,  lead,  potassium,  and  other 
metals  added  to  the  molten  copper,  entirely  deprive  it  of  the  property  of  expanding  and 
becoming  honeycombed  on  cooling;  the  same  effect  is  observed  when  copper  holds  in 
solution  a  small  quantity  of  suboxide,  but  this  fact  is  not  available  for  any  practical  use,  as 
such  copper  is  cold-short.  Just  before  cooling  the  vessel  exhibits  the  phenomenon  of 
spirting,  the  flying  about  of  small  globules  of  copper,  accompanied,  if  large  quantities  of 
the  metal  are  treated,  by  a  distinctly  audible  report.  This  phenomenon  appears  to  be 
due  to  a  cause  similar  to  that  producing  it  when  silver  is  operated  upon,  viz.,  the  violent 
expulsion  of  previously  absorbed  oxygen.  At  a  very  high  temperature  and  with  free 
access  of  air,  or  under  the  influence  of  electricity,  copper  bums,  giving  a  brilliant  green 
flame.  In  countries  where,  as  in  Sweden,  Bussia,  and  Holland,  the  roofs  of  churches  and 
other  large  buildings  are  covered  with  copper — the  most  expensive  at  the  first  outlay,  but 
the  most  lasting  material  for  roofing  purposes — tlie  phenomenon  of  the  burning  of  copper 
isnow  and  then  witnessed  on  a  very  largo  scale  when  fires  accidentally  occur.  Copper-filings 


COPPER.  51 

are  QBed  in  pyrotechny,  for  produoing  a  green  flame.  Dry  air  does  not  affect  copper, 
unless  sulphuretted  hydrogen  and  other  salphurous  emanations  are  present ;  but  moist 
air  oanses  the  copper  to  become  covered  vrith  carbonate  of  hydrated  suboxide  of  copper, 
verdigris,  or  rust.  Experience  has  proved,  in  the  case  of  copper  roofs,  that  this  material 
protects  the  snbjaoent  metal  and  adheres  to  it  with  great  tenacity.  When  solid  masses  of 
copper  are  heated  they  at  first  assome  an  iridescent  rainbow  hue,  and  next  become 
oovered  with  a  brownish-red  coloured  suboxide,  which,  if  the  heating  is  continued,  becomes 
black  oxide,  technically  known  as  copper-ash  or  copper-forge  scale.  In  order  to  remove 
this  oxide,  when  the  copper  is  to  be  rolled  into  sheets,  <&c.,  the  metal  is  dipped  into  what 
is  termed  a  pickle — a  solution  of  ammonia  and  common  salt,  and  on  being  taken  out  is 
brushed  with  a  heather-broom.  Copper,  as  usually  met  with  in  commerce,  is  not  by  any 
means  pure,  but  contains  variable  quantities  of  other  metals,  among  which  are  chiefly 
iron,  antimony,  arsenic,  lead,  tin,  zinc,  and  sulphur ;  Dr.  Beischauer  found  in  perfectly 
malleable  copper  no  less  than  1-48  per  cent  of  impurities  insoluble  in  nitric  acid.  If 
this  quantity  is  only  slightly  increased,  the  quality  of  the  copper  is  so  impaired  that  it  is 
not  only  nnfit  for  being  rolled  and  hammered,  but  also  for  casting  statues  (always  alloyed), 
because  such  copper  loses  its  peculiar  colour  and  does  not  withstand  atmospheric  influ- 
ences. Copper  is  largely  used  for  various  purposes,  among  which  we  name  only  a  few — 
vacuum  and  other  pans  in  sugar- works;  distillery,  brewery,  and  other  apparatus;  for 
covering  wooden  sea-going  vessels,  and  for  a  variety  of  generally  well-known  purposes. 
Dr.  Steinbeck  foxmd  that  refined  Mansfeld  copper,  analysed  1868,  contained  in  100  parts — 

Copper 99*28 

Silver      .♦.  0*02 

Kickel     0*32 

Iron o'o6 

Lead       0*12 


lOO'OO 


The  total  annual  production  of  copper  over  the  entire  globe  amounts  (1870)  to 
1,300,000  cwts.,  of  which  England  alone  yields  fully  350,000  cwts. 

Aiioyiof  copp«r.      There  are  several  alloys  of  copper,  among  which  bronze,  brass,  and 
German,  or  nickel  silver,  are  the  chief. 

BreoM.  Alloys,  consisting  of  copper  and  tin,  or  of  copper,  tin,  and  zinc,  or  of  copper 
and  alnmininm,  all  bear  the  name  of  bronze.  The  addition  of  any  of  these  metals  to 
copper  renders  it  more  fluid  when  molten,  and  hence  better  suited  for  castings,  as 
well  as  denser  and  consequently  more  easily  polished;  alloys  are  harder,  more 
sontHTOUS,  and  (the  aluminium  aUoy  excepted),  far  cheaper  tlian  copper  itself. 
The  addition  of  from  012  to  050  per  cent  of  phosphorus  to  these  alloys  renders  thorn 
^  more  homogeneous  and  malleable.  The  chief  varieties  of  bronze  in  use  are  known  as 
(a)  bell-metal,  {fi)  gun  metal,  and  (y)  statuary  metal. 

(a).  Bell-metal  consists  on  an  average  of  78  parts  of  copper  and  22  parts  of  tin.  It 
should  be  sonorous,  hard,  and  strongly  cohesive.  Being  a  brittle  alloy  it  cannot  bo 
worked  on  the  lathe ;  hence  the  desired  sound  or  musical  note  of  a  bell  depends 
entirely  upon  the  shape  given  in  the  casting  and  upon  the  constituents  of  the  alloy. 
In  order  to  save  tin,  zinc  and  lead  are  sometimes  added,  but  too  much  of  th(\sc 
impairs  the  goodness  of  the  alloy.  It  is  an  error  to  mix  silver  with  this  aUoy,  in 
order  to  render  it  highly  sonorous ;  analyses  made  of  bell -metal  cast  in  tlie  mid<ilc 
ages  in  various  countries,  prove  the  absence  of  silver  from  such  mptal,  traces  only 
being  present  as  an  impurity. 

(/^).  Gun -metal  consists  on  an  average  of  90  parts  of  copper  and  9  of  tin.  This 
alloy  should  combine  mechanical  and  chemical  durability.  As  r(\i;ards  its  mediiuiical 
properties,  the  metal  should  be : — i.  Tough,  so  as  to  prevent  tlio  piece  or^uu  bursting 
while  the  charge  is  being  fired,  during  wliich  operation  Uie  metal  is  exposed  to  a  pres- 
sure of  from  1200  to  1500  atmospheres.  2.  Elastic,  so  that  the  f^in  may  be  able  to 
Weld  to  some  extent  to  the  smart  shocks  occaiiioned  by  tlie  evolution  of  gas  duiing 

K  2 


52 


CHEMICAL    TECHNOLOGY. 


firing.  3.  Hard,  so  that  the  motion  of  the  ball  should  not  cause  any  damage  to  the 
interior  of  the  gun.  As  regards  chemical  durability,  the  alloy  must  resist  the  action 
of  air  and  of  the  products  of  combustion  of  powder  and  gun-cotton  at  high  tem- 
peratures. Gun-metal  answering  these  requirements  is  unfortunately  subject  to  i^hat 
is  termed  liquation ;  that  is  to  say,  while  in  the  molten  state  it  separates  into  two 
qualities  of  alloy,  one  more  fluid  and  containing  more  tin  than  the  other.  This  separa- 
tion makes  the  casting  of  guns  iu  this  alloy  a  difficult  matter,  because  the  homoge- 
neity of  the  mixture  is  uncertain.  It  appears,  however,  that  the  addition  of  from 
o'i2  to  o'5  per  cent  of  phosphorus  remedies  the  defect.  Gun-metal,  however,  is  fast 
being  superseded  by  steel  in  the  manufacture  of  ordnance.  MM.  Maritz,  at  the 
Hague,  have  for  several  generations  been  renowned  for  the  superiority  of  their  gun- 
metal  manufacture,  which  is  still  pursued  by  them.  According  to  a  statement  in  the 
"  Handworterbuch  der  Ghemie "  (Art.  "  Geschutz-metall,")  the  alloy  employed  hy 
them  consists  of  0*69  per  cent  Fe,  88*61  per  cent  Gu,  and  1070  per  cent  Sn ; 
generally  the  quantity  of  tin  amounts  to  from  9  to  11  per  cent. 

(y.)  Statuary-bronze  for  ornamental  purposes  consists  of  copper,  tin,  lead,  and  zinc. 
It  is  requisite  that  while  molten  this  alloy  should  be  very  fluid,  so  as  to  fill  every  part 
of  the  mould.  After  cooling,  the  metal  must  admit  of  being  chiselled,  and  by  expo- 
sure to  air  it  should  assume  what  is  termed  patina — a  peculiar  greenish-black  htie. 
The  statue  of  Louis  XTV.  at  Paris,  made  1699,  consists  of— Gopper,  91  40 ;  adnc,  553  ; 
tin,  170 ;  lead,  1*37.  The  statue  of  Henri  IV.  on  the  Pont  Nceuf  at  Pads,  consists 
of — Gopper,  89*62;  zinc,  4020;  tin,  570;  lead,  048.  Aluminium-bronze  (90  parts 
copper  and  10  aluminium)  is  used  for  various  ornamental  purposes,  chiefly  in 
imitation  of  gold. 

Bom.  This  alloy  has  teen  known  from  a  very  remote  period.  Zinc  and  copper 
form  various  alloys,  but  brass  only  is  technically  applied,  and  contains  on  an  average 
30  per  cent  of  zinc.  The  colour  of  the  alloy  is  inclined  to  red,  when  the  quantity  of 
zinc  is  small,  and  to  yellow  or  whitish-yellow  when  the  quantity  of  zinc  is  increased. 
The  ductility  and  malleability  of  the  alloy  increase  with  the  quantity  of  copper. 
Brass  may  be  hammered,  rolled  into  sheets,  or  drawn  to  wire  while  cold,  but  cannot 
be  worked  hot.  The  so-called  yellow  metal,  Muntz's  patent,  an  alloy  of  40  parts  of 
zinc  and  60  of  copper,  may  be  wrought  while  red-hot,  rolled  into  sheets,  and  forged 
into  bolts.  It  is  chiefly  used  for  marine  purposes,  including  the  internal  lining  of 
air-pumps  of  marine  steam-engines.  Brass  is  not  so  readily  oxidised  as  copper,  being 
harder,  tougher,  more  easily  fusible,  and  more  fluid  while  molten.  It  solidifies 
without  becoming  honey-combed,  and  hence  is  suited  for  making  all  kinds  of  castings; 
while  simply  by  the  addition  of  from  i  to  2  per  cent  of  lead,  it  is  capable  of  being 
readily  worked  on  the  lathe,  and  may  be  then  filed  without,  as  it  otherwise  does, 
clogging  the  teeth  of  the  file. 

Brass  is  made  by  any  of  the  following  methods : — i.  By  melting  together  a  mixture  of 
calamine  stone  and  black  or  blistered  copper  under  a  layer  of  charcoal.  2.  By  simply  melting 
together  zinc  and  refined  copper.  The  hist  method  is  the  oldest,  and  is  still  carried  on 
in  furnaces  arranged  so  that  they  may  contain  from  7  to  9  fire-clay  crucibles  at  the  same 
time.  These  crucibles  are  fiUed  with  the  necessary  materials,  viz.,  previously  roasted 
zinc  ore,  or  residues  from  zinc-smelting  furnaces,  and  copper.  As  by  the  use  of  calamine 
stone,  only  some  27  to  28  per  cent  of  zinc  can  be  imparted  to  the  alloy,  it  is  usual  to  add, 
previously  to  pouring  out  the  molten  alloy,  another  quantity  of  calamine  stone,  rather  to 
prevent  any  loss  of  zinc  by  ignition  than  to  increase  the  quantity  of  that  metal.  In 
former  times  the  manufacture  of  brass  was  carried  on  in  ^o  distinct  operations,  one 
being  the  preparation  of  an  alloy  containing  only  20  per  cent  of  zinc,  known  as  aroo- 
smelting,  and  the  other  the  conversion  of  the  arco  into  brass  by  a  second  smelting  and  the 


COPPER,  53 

addition  of  zinc.  At  the  present  time  the  manufacture  of  brass  consists  in  simply 
placing  alternate  layers  of  copper  and  zinc  in  fire-clay  or  graphite  crucibles,  and  then 
smelting  the  two  metals  under  a  thick  layer  of  charcoal.  The  alloy  is  cast  in  granite 
moulds  Borronnded  by  a  thick  coating  of  clay  and  cow-dung,  or  sand-moulds.  Occasion- 
aUy  sheet-copper  is  conyerted  into  brass  by  exposing  the  sheets  to  the  fumes  of  metaUio 
zinc.  Among  brass  alloys  we  may  notice  the  following : — Tomback,  or  red  brass,  con- 
sisting of  85  parts  of  copper  and  15  of  zinc.  Butch-gold — a  gross  misnomer,  as  none  of 
it  is  made  in  Holland,  and  as  the  term  really  applies  to  a  very  pure  gold  coin,  the  ducat, 
still  made,  although  not  current,  in  Holland,  at  the  Utrecht  Mnt.  The  brass  alloy  thus 
named  consists  of  1 1  parts  of  copper  and  2  of  zinc,  and  is  made  chiefly  at  Niimberg  and 
Purth,  Bavaria,  for  the  purpose  of  beiag  beaten  into  very  thin  leaves.  The  alloy  termed 
Aich-metal,  and  consisting  of  60  parts  of  copper,  38*2  parts  of  zinc,  and  1*8  parts  of  iron, 
is  in  reality  malleable  brass.  Sterro-metal,  though  very  much  harder,  is  similar  to  the 
foregoing  in  composition. 

The  well-known  yellow,  or  Muntz,  metal,  largely  used  in  this  ooxmtry  for  marine 
purposes,  coating  ships,  <&c.,  is  an  alloy  of  copper  and  zinc  in  proportions  varying  from 
50  per  cent  of  zinc  and  63  of  copper,  to  39  per  cent  of  zinc  and  50  per  cent  of  copper. 
The  alloy  in  use  for  coins  of  small  value  in  this  country,  France,  and  Sweden,  consists  of 
95  parts  of  copper,  4  parts  of  tin,  and  i  of  zinc.  The  alloy  used  for  this  purpose  in  Den- 
mark consists  of  90  parts  of  copper,  5  of  tin,  and  5  of  zinc.  Batii-metal,  or  white  brass, 
eonsists  of  55  parts  of  copper  and  45  of  zinc.  An  alloy  used  for  buttons  consists  of 
20  parts  of  copper  and  80  psurts  of  zinc.  The  bronze  colours  (powdered  alloys  of  copper 
and  zinc),  now  largely  used  for  bronzing  painted  surfaces,  as  well  as  for  lithochromy  and 
various  other  purposes,  are  obtained  from  scraps  of  metal  rubbed  down  with  oil,  tallow, 
or  wax,  and  turpentiue.  The  various  beautiful  colours,  violet,  copper-red,  orange,  gold- 
jdlow,  green,  are  due  to  partial  oxidation.  These  bronze-colours  are  not  to  be  con- 
founded with  a  beautiful  substance  known  as  mosaic  gold — aurum  mvMvum — bisulphide  of 
tin.    Analyses  show  the  proportions  in  these  alloys  to  be — 

For  bright  colours |^?PP«'    ;;     «3 

For  red  or  deeper  colours    -A^^^^^     \\    ^JZ?^ 
For  copper-red  colours        . .  100 

Cbemical  analysis  has  also  proved  the  quantity  of  copper  to  amount  to — 

a.  In  French  bronzes :        Copper-red  colour . .     . .  97*32  per  cent 

Orange 94*44 

Bright  yellow        ..     ..  81*29 

p.  In  English  bronzes  :      Orange 90*82 

Deep  yellow 82*37 

Bright  yellow        . .     . .  80*42 

y.  In  Bavarian  bronzes :      Copper-red     98*92 

Violet      98-82 

Orange 95-30 

Deep  yellow 81-55 

Bright  yellow        . .     . .  82*34 

cciw^  w^Kiotoi  German,  or  nickel  silver,  also  called  Argentan,  packfong,  or  white 
copper,  is  an  alloy  of  copper  with  nickel  and  zinc,  or  tin,  and  may  be  considered  as  a 
ij^tass  to  which  from  one-sixth  to  one-third  of  nickel  has  been  added.  This 
alloy  appears  to  have  been  known  in  China  from  a  very  remote  period ;  in  Europe  it 
I1A8  been  more  generally  in  use  during  the  last  thirty  years.  The  colour  is  nearly 
Bilver-white ;  its  fracture  small-grained  and  compact ;  sp.  gr.  »  8*4  to  8*7.  It  is 
harder,  but  yet  quite  as  ductile  as  ordinary  brass,  and  takes  an  excellent  polish.  It 
is  prepared  by  melting  together  the  granulated  metals,  zinc,  copper,  and  nickel ; 
these  metals  are  put  into  a  crucible  in  such  a  manner  that  copper  is  at  the  bottom  as 
Well  as  the  top,  while  a  layer  of  charcoal-powder  covers  the  whole.  Care  is  taken  to 
stir  the  mass  with  an  iron  rod.  Nickel-silver  of  good  quality  has  the  appearance  of 
a  alver  aQoy,  containing  one-fourth  of  copper.  Nickel-silver  is  capable  of  assuming 
uk  excellent  polish,  and  is  not  readily  acted  upon  by  vinegar  and  the  ordinary  acids 
m  culinary  use ;  hence  it  is  used  for  spoons  and  forks. 


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54  CHEMICAL  TECHNOLOGY. 

Average  Gknuan-Bilver  conslBts  of — 

Copper     50 — 66*0 

Zinc 19 — 31*0 

Nickel       13—18*5 

At  Sheffield  the  following  yarieties  of  this  alloy  are  made : — 

Copper.     Nickel.         Zine. 

Common 8  2  3*5 

White 8  2  35 

Electrum 8  4  3*5 

Infusible 8  6  3-5 

Tutenao      8  3  6-5 

When  tried  on  the  touchstone,  nickel-silver  is  hardly  distinguishable  from  the 
silver  alloy  just  mentioned,  but  on  applying  nitric  acid  to  the  streak  caused  by  the 
nickel  alloy,  it  is  more  rapidly  dissolved,  and  by  adding  a  few  drops  of  chloride  of  sodium 
solution  no  turbidity,  or  precipitate  of  chloride  of  silver,  is  produced  on  the  stone. 
The  alloy  known  as  Alf6nide,  used  for  making  tea-pots,  sugar-basins,  milk-ewers,  and 
similar  articles,  is  nickel-silver,  thickly  electro-plated  with  pure  silver,  the  quantity 
of  silver  amounting  to  about  2  per  cent.  The  alloy,  known  as  tiers-argent  (one-third 
silver),  consists,  according  to  Dr.  C.  Winkler's  analysis  (see  "Chemical  News," 
vol.  xxii.,p.  225),  of—Copper,  59*06 ;  silver,  2756;  zinc,  957;  nickel.  3*42. 

Since  1850  the  Swiss  Confederation  has  brought  into  circulation  a  series  of  small  eoins 
(monnaie  billon)  j  which  contain  in  1000  parts : — 

Silver.  Copper.  Zinc.  Nickel. 

Pieces  of  20  Bappen      . .     . .         150  500  250  100 

„       10      „  ....         100  550  250  100 

„        5      I,  ....  50  600  250  100 

These  coins  are  not  turned  red  by  wear,  but  assume  a  yellowish  hue.  In  Belgium  the 
5, 10,  and  20  centime  pieces  are  made  of  an  alloy  of  25  parts  of  nickel  and  75  parts  of 
copper ;  while  the  United  States'  cent  pieces  contain  12  parts  of  nickel  and  88  of  ooppo-. 
The  alloy  known  on  the  Continent  as  Suhler's  white  copper,  consists  of  88  parts  of  copper, 
8*75  parts  of  nickel,  and  175  parts  of  antimony. 

Amalgam  of  Copper.  By  the  name  of  metallic  cement  is  understood  an  amalgam  of  30  parts 
of  copper  and  70  parts  of  mercury.  It  is  obtained  by  moistening  pulverised  copper, 
obtained  in  a  spongy  state,  by  reducing  its  oxide  at  a  low  red  heat,  by  means  of  "hydrogen 
with  nitrate  of  suboxide  of  mercury,  care  being  taken  to  incorporate  this  saline  solution 
thoroughly  with  the  copper,  while  adding  hot  water.  This  cement,  at  first  soft,  bardenji 
in  a  few  hours.    It  has  been  successfully  applied  in  stopping  decayed  teeth. 

PrepaiUlTIons  of  Copper. 

sui^to  of^iper.  ^^^  ^*  ^^  ^^^  ^^  naturally  in  kidney-shaped  masses,  or  as  an 
outer  covering  of  minerals  containing  copper,  as  well  as  in  solution,  as  referred  to 
imder  Cementation-copper.  Sulphate  of  copper,  blue-  or  Cyprus-vitriol,  crystaUiaes 
in  the  shape  of  triclinohedrical  blue-coloured  crystals,  soluble  in  2  parts  of  hot  and 
4  of  cold  water,  and  insoluble  in  alcohol.     100  parts  of  the  salt  contain: — 

Sulphuric  add      32*14 

Oxide  of  copper 3179 

Water     36-07 

Formula:— CUSO4+5H2O. 

^SJvitriiL'  Chemically-pure  sulphate  of  copper  is  obtained  by  heating  metallic 
copper  with  concentrated  sulphuric  acid ;  the  metal  is  oxidised  by  a  portion  of  the  oxygen 
of  the  acid,  while  sulphurous  acid  escapes,  (Cu+ 2HaS04 = CUSO4+ 2H2O + SOa) .  If 
the  metal  is  previously  converted  into  oxide  of  copper  by  exposure  to  a  red  heat,  only 
half  the  quantity  of  sulphuric  acid  is  required.     Sulphate  of  copper  is  manufactored 


PREPARATIONS  OF  COPPER,  55 

on  a  large  scale  by  any  of  the  following  processes : — i.  By  the  evaporation  of  cemen- 
tation-water until  crystallisation  is  attained.    2.  By  heating  sheets  of  copper  in  a 
reverberatoiy  furnace  to  the  boiling-point  of  sulphur;  a  quantity  of  that  element 
being  then  thrown  in,  and  the  flues  and  other  openings  closed,  the  effect  is  the  forma- 
tion of  sulphide  of  copper  (GuaS),  which  is  converted  by  a  comparatively  low  heat 
and  the  action  of  the  oxygen  of  the  air  into  sulphate  (Cu«S+50=GuS04+CuO). 
The  mass  is  next  placed  in  a  suitable  vessel,  and  as  much  sulphuric  acid  is  added  to 
it  as  is  sufficient  to  saturate  the  oxide  of  copper.    The  clear  solution,  having  been 
decanted  from  the  insoluble  residue,  is  set  aside  for  crystallisation.    3.  By  treating 
the  crude  copper  obtained  by  smelting  the  ores,  and  containing  about  60  per  cent  of 
metal,  with  sulphuric  add.    The  resultiog  solution  is  evaporated  in  leaden  vessels, 
aad  the  clear  liquid  left  to  crystallise  in  copper  pans.    From  the  mother-liquor  of  the 
nystals  metallic  copper  is  precipitated  by  means  of  iron,  because  the  presence  of  a 
large  quantity  of  sulphate  of  iron  renders  this  mother-liquor  unfit  for  the  further 
making  of  blue- vitriol.    This  method  of  obtaining  sulphate  of  copper  is  the  least 
expensive,  but  the  salt  is  not  quite  pure,  containing,  according  to  M.  Herter's  analysis 
of  Mansfeld  blue- vitriol,  about  3  per  cent  of  sulphate  of  iron,  and  0083  per  cent  of 
metallic  nickel.    Veiy  frequently  the  scraps  and  refuse  of  copper-smithies,  copper- 
scale,  and  other  residues  of  that  metal,  are  used  in  preparing  sulphate  of  copper. 
4-  At  Marseilles,  malachite  is  dissolved  in  sulphuric  acid  to  obtain  blue-vitriol. 
5.  In  Norway,  iron  pyrites  containing  copper  are  roasted  and  treated  with  water,  the 
copper  contained  being  precipitated  with  sulphuretted  hydrogen,  and  the  sulphide  of 
eopper,  when  dry,  converted  into  sulphate  by  exposure  to  a  gentle  heat.    6.  Large 
quantities  of  sulphate  of  copper  are  obtained  as  a  by-product  of  silver -refining,  espe- 
cially when  silver  is  treated  for  the  purpose  of  extracting  the  gold  it  contains,  by 
boiling — ^usually  silver  coins,  chiefly  Mexican  and  Peruvian  dollars — ^with  strong 
sulphuric  add;  sulphate  of  silver  and,  as  the  coins  contain  some  copper,  the 
sulphate  of  that  metal,  are  formed,  while  the  gold  is  left  as  an  insoluble  substance. 
The  silver  is  reduced  to  the  metallic  state  (AgaS04+Cu=CuS04+2Ag)  by  means  of 
sheets  of  copper  placed  in  the  acid  solution,  which  is  previously  diluted,  and  which, 
^ftet  having  been  decanted  from  the  sediment,  spongy  metallic  silver,  yields  on 
evaporation  a  very  pure  sulphate  of  copper.    7.  Sulphate  of  copper  is  also  obtained 
as  a  by-product  of  the  hydrometallurgical  process  of  extracting  silver,  or  Ziervogel's 
process.   In  order  to  separate  the  sulphate  of  iron  from  the  crude  blue  vitriol,  as 
oUamed  at  copper-smelting  works  from  various  cupriferous  refuse,  the  crude  salt  is 
roasted  so  as  to  bring  about  a  partial  decomposition.    By  this  means  the  sulphate  of 
inm  is  decomposed,  and  the  oxide  of  that  metal  formed  is  insoluble  in  water.    The 
saline  mass  is  dissolved  in  water,  and  the  clear  solution,  decanted  from  the  sediment, 
evaporated  to  crystallisation.    According  to  Bacco's  plan,  the  crude  blue- vitriol  is 
ilissolved  in  water,  and  carbonate  of  copper  added  to  the  solution,  to  cause  the  preci- 
pitation as  oxide  of  all  the  iron  present,  while  an  equivalent  quantity  of  oxide  of 
c^'Pper  is  dissolved  and  converted  into  sulphate.    The  purified  sulphate  of  copper 
solution  having  been  filtered  is  evaporated  and  left  to  crystallise. 

,  i>o«i>i«  vitrioL  Under  the  name  of  donble-vitriol,  a  mixture  of  the  sulphates  of  copper  and 
^  erystalfised  together,  and  sometimes  containing  white  vitriol,  is  met  with  on  the 
Continttit,  The  Salzburg  vitriol,  known  by  the  brand  of  a  double  eagle,  contains 
•Ixmt  76  per  cent,  the  Admont  83  per  cent,  and  the  double  Admont  80  per  cent  of 
"ilphate  of  protoxide  of  iron.  Of  later  years,  however,  these  vitriols  have  been  less  in 
demtud. 


56  CHEMICAL  TECHNOLOGY. 

ApnUcadoiiB  of  Afl  the  bsse  of  the  pigments  obtainable  from  copper,  the  snlphate  is  very 
Biae-YitrioL  frequently  need,  and  should  be  pure,  or  at  least  free  from  the  sulphates  of 
iron  and  zinc.  Blue-Tltriol  also  serves  for  the  manufacture  of  acetate  of  copper,  for 
bronzing  iron,  for  bringing  out  the  colour  of  alloys  of  gold.  It  is  used  in  dyeing  and 
printing  in  various  ways,  for  galvano-plastic  purposes,  and  during  the  last  twenty  years 
large  quantities  of  tins  salt  have  been  sent  to  Mexico  and  Peru  to  be  applied  in  the 
American  amalgamation-process  of  extracting  silver. 

Copper  Pigments.  Among  Uie  many  pigments  which  owe  their  blue  or  green  colour 
essentially  to  copper,  we  may  treat  of  the  following: — i.  Brunswick-green.  2.  Bremen- 
green  and  Bremen-blue.  3.  Casselmann's-green.  4.  Mineral-green.  5.  Schweinfort- 
green,  also  known  as  emerald-green.  Many  of  the  pigments  mentioned  here  by  tlveir 
German  names  are  known  in  this  country  by  other  denominations,  but  are  not  for 
tliat  reason  any  different  in  composition. 

BraiiB«ick-oz«en.  Under  thls  name  several  compounds  of  copper  are  applied  as  oil-piunie. 
The  pigment  now  chiefly  in  use  bearing  this  name  is  basic  carbonate  of  oxide  of  copper 
rCuG03-}-0uH202),  an  imitation  of  mountain-  or  mineral-green,  and  obtained  from  either 
nnely  pulverised  malachite  or  the  sediment  often  met  with  in  cupriferous  cementation- 
liquids.  Brunswick-green  is  prepared  on  a  large  scale  by  the  decomposition  of  sulphas  of 
iron  by  means  of  either  carbonate  of  soda  or  carbonate  of  lime,  and  in  other  cases  by  the 
decomposition  of  chloride  of  copper  by  means  of  a  carbonated  alkali.  The  ensuing  preci- 
pitate is  wadied  with  boiling  water,  and  afterwards  mixed  with  a  smaller  or  larger  quan- 
tity of  sulphate  of  baryta,  zinc-white,  or  gypsum,  and  frequently  with  Schweinfurt-green 
(aceto-arsenite  of  copper)  in  order  to  obtain  the  desired  hue.  Another  variety  of  Bmna- 
wick-green,  rarely  met  with  in  the  present  day,  appears  to  be  a  kind  of  artiflcially -prepared 
atacamite,  an  oxychloride  of  copper,  the  formula  of  which  is,  according  to  Bitthwisen, 
CuCl2,3CuO-h3H20. 

^"SS^SSm  "      These  substances  are  essentially  hydrated  oxide  of  copper,  and  are 

met  with  as  a  very  bright  blue  spongy  mass  with  a  greenish  hue.    The  value  is 

greater  according  to  the  finer  blue  colour  and  loose  spongy  texture.    When  uaed  with 

water,  gum,  or  glue,  this  pigment  yields  a  bright  blue  colour,  hence  its  first  name ; 

but  when  it  is  mixed  with  Hnseed-oil,  the  blue  colour  turns  within  twenty-four  hours 

to  green,  in  consequence  of  the  saponification  of  the  oxide  of  copper,  which  becomes 

oleate,  paJmitate,  and  linoxate  of  that  base.    Bremen-green  occurs  in  various  hues 

obtained  by  mixing  the  precipitate  with  well-cleansed  gypsum.    At  the  present  time 

the  pigment  is  generally  obtained  from  oxychloride  of  copper  (CuCla,3CuO-h4H20). 

This  preparation  may.  be  made  in  various  ways,  provided  care  be  taken  that  the 

light  green  paste — technically  known  as  oxide — contains  no  protochloride  of  copper 

(CugCla).    Gentele's  method  is  as  follows : — 

I.  112*5  Mies,  of  coxomon  salt,  and  in  kilos,  of  sulphate  of  copper,  both  free  from  iron, 
are  ground  together  with  sufficient  w&ter  to  promote  reaction.  2.  112*5  kilos,  of  old 
copper  sheiBting  is  cut  into  pieces  a  square  inch  in  size,  and  placed  with  water  acidulated 
with  sulphuric  acid  in  rotating  casks  so  as  to  remove  all  rust,  oxide  and  oxychloride,  from 
this  metal,  which  is  next  washed  with  water.  3.  The  dean  metal  thus  obtained  is  next 
placed  in  what  is  known  as  oxidation-closets  and  covered  for  a  thickness  of  half-an-ineh 
with  the  paste  mentioned  above.  A  mutual  action,  aided  by  that  of  the  atmosphere,  is 
set  up,  the  result  being  that  the  chloride  of  copper  first  takes  up  copper,  beooming  proto- 
chloride ;  this  in  its  turn  takes  up  oxygen  from  the  atmosphere  and  water,  and  thus  becomes 
converted  into  the  green-coloured  insoluble  basic  hydrated  oxide  of  copper,  the  action  being 
greatly  aided  by  the  turning  over  of  the  mass  with  a  copper  spade  every  two  or  three  days. 
As  the  treatment  of  protochloride  of  copper  with  alkalies  or  alkaline  earths  gives  rise  to  the 
separation  of  red  or  yellow-coloured  suboxide,  the  mass  should  not,  on  being  tested  and 
previous  to  further  operations,  yield  even  the  faintest  indication  of  the  presence  of  sub- 
oxide, since  the  slightest  trace  would  spoil  the  hue  of  the  pigment  to  be  obtained ;  conse- 
quently in  some  works  the  pasty  mass  is  left  for  years  before  it  is  used  for  further  opera- 
tions. The  action  is  accelerated  by  causing  the  mass  to  become  dry  before  turning  it  over 
^ith  the  spade,  the  consequence  being  that  the  air  gets  thorough  access,  and  a  complete 
oxidation  is  obtained  in  about  three  to  five  months  time.  The  mass  is  then  cleansed  with 
the  smallest  possible  quantity  of  water,  and  is  thus  separated  from  the  non-oxidised 


PREPARATIONS  OF  COPPER.  57 

metallio  copper.  4.  To  Bome  6  gallons  of  this  cleaiiBed  material  are  added  6  kilos,  of 
hydrochloric  add,  and  this  mixture  is  allowed  to  stand  for  abont  two  days.  5.  Into  a 
tank  or  tub — ^the  blue  tnb — are  ponred  some  15  gallons  clear  colourless  potassa-lye.  This 
hanng  been  done,  the  acid  mixture  is  first  diluted  wrth  some  6  more  gaUons  of  water,  and 
then,  as  rapidly  and  expeditiously  as  possible,  ponrei  into  the  bine  tnb,  the  mixture  being 
continuously  stirred.  The  result  of  this  last  operation  is  that  the  previously  basic  copper 
eompound,  converted  by  HGl  into  neutral  cupric  chloride,  is,  when  brought  in  contact 
with  the  potassa,  converted  into  blue-coloured  oxyhydrate  of  copper  or  Bremen-blue, 
while  chloride  of  potassium  is  also  formed.  6.  After  the  mass  has  become  pasty,  it  is  left 
to  stand  for  a  couple  of  days,  and  then  thoroughly  washed  by  decantation  to  remove  ^e 
chloride  of  potassium.  The  cupric  oxyhydrate  is  then  put  on  cloth  filters,  kept  moist,  and 
exposed  to  the  air  for  some  time.  It  is  next  dried  at  a  temperature  of  from  30°  to  35*, 
smce  at  a  higher  temperature  the  hydrate  of  the  oxide  by  losing  its  water  becomes 
bUckish-brown  coloured.  It  is  clear  that  Bremen-blue  can  be  differently  obtained,  but 
these  differences  of  preparation  do  not  bear  so  much  upon  the  precipitation  of  the 
hjdrated  oxide  as  upon  the  means  of  obtaining  chloride  of  copper ;  these  means  may  of 
eourse  be  varied  in  many  ways ;  for  instance,  by  causing  a  mixture  of  common  salt, 
dilute  sulphuric,  and  copper  scraps  to  act  upon  each  other,  the  mass  being  afterwards 
exposed  to  the  action  of  the  air ;  by  the  action  of  hydrochloric  acid  upon  copper  and  its 
oxide ;  or  by  partly  decomposing  neutral  nitrate  of  copper  by  means  of  carbonate  of  soda. 
In  this  case  a  precipitate  of  carbonate  of  copper  is  formed,  which,  while  giving  off  its 
earbonic  add,  ^comes  converted  into  basic  nitrate  of  copper  (OuNaOe+CuHsO^),  deposited 
as  a  heavy  green  powder.  A  solution  of  zinc-oxide  of  potassa  (solution  of  zinc-white  in 
caustic  potassa),  is  next  added,  the  result  being  the  formation  of  a  deep  blue  pigment, 
TQiy  spongy  and  very  covering  (a  technical  term  in  use  by  painters),  consisting  of  zincate 
of  copper  with  a  small  quantity  of  basic  nitrate  of  copper.  A  magnesia  Bremen-blue  is 
obtained  by  the  precipitation  of  a  solution  of  the  sulphates  of  magnesia  and  copper,  to 
vhich  some  cream  of  tartar  is  added,  by  means  of  potassa,  care  being  taken  to  pour  the 
saline  solution  into  the  alkaline,  and  to  keep  an  excess  of  the  latter. 

'^Tfhifim'i  ffrrttn  In  the  year  1865  Dr.  Gasselmann  discovered  this  pigment,  a 
beautiftil  green  free  from  arsenic.  It  is  prepared  by  mixing  together  boiling  solutions 
of  sulphate  of  copper  and  an  alkaline  acetate;  the  resulting  precipitate  is  a  basic  salt 
of  copper  (CUSO44- sCuHaOa + 4HaO) .  After  drying,  this  salt  is,  next  to  Schweinfrirt- 
green,  the  finest  of  all  colours  obtained  from  copper,  and  being  free  from  arsenic,  is 
highly  commendable,  though  yet  poisonous,  as  are  most  preparations  of,  and  esped- 
ally  acetates  of,  copper. 

Mjaenj-orean  '^^^  pigment,  also  known  as  Scheele*s-green,  is  not  so  frequently  used 
aad  BioA.  qqw  as  formerly.  It  is  essentially  a  mixture  of  hydrated  oxide  of  copper  and 
urseuite  of  copper,  and  does  not  cover  very  well.  It  is  prepared  by  dissolving  i  kilo,  of 
pore  sulphate  of  copper  in  12  Jitres  of  water,  to  which  is  added,  whUe  constanUy  stirred, 
s  solution  of  350  grms.  arsenious  acid  and  i  kUo.  of  purified  potash  (carbonate)  in  8  litres 
of  water.  The  resulting  grass-green  coloured  precipitate  is  washed  with  boiling  water  and 
dried.  Another  pigment,  sometimes  known  as  mineral-green,  is  obtained  from  pulverised 
vudachite,  or  basic  hydrated  oxide  of  copper.  By  the  term  mineral-blue  is  generally 
understood  a  kind  of  Berlin-blue,  rendered  less  deep  coloured  by  the  addition  of  pix>e-clay 
or  other  white-coloured  powders,  but  the  term  also  applies  to  a  pigment  formerly  obtained 
by  grinding  and  washing  the  purest  pieces  of  lazurite  of  copper,  a  mineral 

(20uC0,-|-CuHa02), 
found  in  the  Tyrol  and  near  Lyons.  This  pigment  is  artificially  obtained  in  France, 
Holland,  and  Belgium,  by  precipitating  a  solution  of  nitrate  of  copper  with  caustic  lime 
or  caustic  potassa,  and  afterwards  mixing  the  previously  washed  precipitate  with  chalk, 
gypsum,  or  heavy  spar.  The  pigment  is  sent  into  the  trade  for  use  chiefly  as  a  water- 
colour.  Under  the  name  of  lime-blue  a  similar  preparation  occurs  in  quadrangular 
lamps,  obtained  by  precipitating  a  solution  of  100  parts  of  sulphate  of  copper  and 
i2i  parts  of  sal-ammoniac  with  a  milk  of  lime  containing  30  parts  of  caustic-lime.  The 
precipitate  is  a  mixture  of  hydrated  oxide  of  copper  and  sulphate  of  lime,  according  to 
the  formula  2(CaS04,2HaO-f3CuHa02).  This  pigment  exhibits  a  purer  tint  ^an 
Bremen- blue,  but  though  it  covers  pretty  weU  as  a  water-colour,  it  is  almost  useless  as  an 
oil-colour. 

oQBiae.  A  pigment  which,  when  ground  with  oils  and  varnishes,  yields  a  beautiful 
yiolet-blue,  and  is  essentially  composed  of  sulphide  of  copper  (CuS),  there  being  applied 
in  its  manufacture  either  the  native  mineral,  knovm  as  cupreous  indigo,  or  an  artificially 


58  CHEMICAL  TECHNOLOGY, 

prepared  sulphide,  obtained  byfasing  finely  divided  metallio  copper  with  hepar-solphniiB, 
a  mixture  of  several  sulphurets  of  potassium.  The  fused  mass  is  treated  with  water,  and 
the  sulphide  of  copper  remains  in  small  blue-coloured  crystals,  which,  after  drying,  are 
pulverised  and  mixed  with  oil. 

^^E^^SdS^ ""'  This  pigment  is  by  far  the  most  beautiful,  but  also  the  most 
poisonous,  of  aU  green-coloured  copper  pigments.  In  Germany  this  substance  is 
known  under  a  number  of  aliases  derived  from  the  peculiar  depth  of  hue  as  modified 
in  various  manufactories  by  means  of  sulphate  of  bar3rta,  sulphate  of  lead,  snd 
chrome-yellow.  The  constitution  and  mode  of  preparation  of  this  pigment  remained, 
at  least  on  the  Continent,  a  trade  secret  until  the  researches  of  MM.  Braconnot  and 
J.vonLiebig  made  the  particulars  known.  According  to  Dr.  Ehrmann,  pure  emerald- 
or  Schweinfiirt-green  is  an  aceto-arsenite  of  copper : — 

in  100  parts — Oxide  of  copper,  31*29 ;  arsenious  acid,  58*65 ;  acetic  acid,  io'o6. 
Dr.  R.  Wagner  states  tliat  this  formula  is  only  empirical,  because  a  portion  of  the 
copper  is  present  as  suboxide,  and  a  portion  of  tlie  arsenic  as  arsenic  acid. 

According  to  Dr.  Ehrmann's  statement,  this  pigment  is  prepared  by  first  separately 
dissolving  equal  parts  by  weight  of  arsenious  acid  and  neutral  acetate  of  copper  in  boiling- 
water,  and  next  mixing  these  solutions  while  boiling.  There  is  immediately  formed  a 
flocculent  olive-green  coloured  precipitate  of  arsenite  of  copper,  while  the  supernatant 
liquid  contains  free  acetic  acid.  After  a  while  the  precipitate  becomes  gradually  crystal- 
line, at  the  same  time  forming  a  beautifully  green  pigment,  which  is  separated  from  the 
liquid  by  filtration,  and  after  washing  and  carefidly  drying  is  ready  for  use.  The  mode 
of  preparing  this  pigment  on  a  large  scale  was  originaJly  devised  by  M.  Braconnot,  as 
follows : — 15  kilos,  of  sulphate  of  copper  are  dissolved  in  the  smallest  possible  quantity  of 
boiling- water  and  mixed  with  a  boilhig  and  concentrated  solution  of  arsenite  of  soda  or 
potassa,  so  prepared  as  to  contain  20  kilos,  of  arsenious  acid.  There  is  immediately 
formed  a  dirty  greenish-coloured  precipitate,  which  is  converted  into  Sohweinfnrt-green 
by  the  addition  of  some  15  litres  concentrated  wood-vinegar.  This  having  been  done,  the 
precipitate  is  immediately  filtered  off  and  washed.  It  thus  appears  that  the  preparation 
of  this  pigment  aims  first  at  the  least  expensive  preparation  of  neutral  arsenite  of  copper, 
which  is  next  converted  into  aceto-arsenite  by  digesting  the  precipitate  with  acetic  add. 
The  pigment  is  available  as  a  water-  and  an  oil-colour,  but  does  not  cover  very  well  in  oil, 
although  it  dries  rapidly.  The  colour  cannot  be  used  for  mural  painting,  as  the  lime 
absorbs  the  acetic  acid,  leaving  a  yellowish-green  arsenite  of  copper.  The  Schweinfurt- 
green  consists  of  microscopically  small  crystals;  if  these  crystals  are  pulverised,  the 
colour,  previously  grass-green,  becomes  paler.  Air  and  light  do  not  affect  this  pigment, 
which  is  insoluble  in  water,  but  becoming,  when  boiled  with  it  for  a  length  of  time, 
brown-coloured,  probably  in  consequence  of  the  loss  of  some  acetic  acid.  It  is  a  well- 
known  fact  that  paper-hangings  containing  this  pigment,  and  pasted  on  damp  walls, 
cause  the  inmates  of  the  rooms  to  suffer  from  headaches,  due  in  all  likelihood  to  volatile 
arsenical  emanations,  among  which  is  arseniuretted  hydrogen. 
stozmate  of  Oxide  This  preparation,  also  known  as  Qentele's-green,  is  obtained  by  preeipi- 
of  Copper.  tating  a  solution  of  sulphate  of  copper  with  stannate  of  soda,  waeiiing  and 
drying  the  precipitate,  which  forms  a  beautifully  green,  innocuous,  at  least  as  compared 
with  Uie  foregoing,  copper  pigment. 

Verdigris.      Under  this  name  we  meet  in  commerce  with  a  neutral  and  a  basic  acetate 

of  copper ;  the  one,  a  crystalline  substance  is 

a  salt  formerly  only  prepared  in  Holland,  and  designated  as  "  distilled  yerdigris, '  in 
order  to  mislead  as  to  its  mode  of  manufacture. 

The  basic-salt,  blue  verdigris,  is  chiefly  prepared  at  and  near  Montpellier,  by  employing 
the  marc  of  the  grapes,  the  skin  and  stems  of  the  bunches  after  the  juice  has  been  squeezed 
out,  which  readily  forms  acetic  acid  by  fermentation.  Into  the  marc  are  placed  sheets  ol 
copper  previously  moistened  with  a  solution  of  acetate  of  copper.  The  metal  becomes 
coated  with  a  layer  of  verdigris,  which  is  removed  by  scraping.    It  is  next  kneaded  with 


LEAD,  59 

water,  after  which  the  paste  is  pat  into  leathern  bags  and  pressed,  so  as  to  obtain 
reotangnlar  cakes.  The  metal  is^reated  in  the  same  manner  until  it  is  entirely  oonyerted 
into  baisio  yerdigris,  having  a  bine  colour,  and  known  as  French-verdigris.    Formula — 

A  green-coloured  verdigris  is  obtained  at  Grenoble  and  elsewhere  by  submitting  sheets  of 
eopper  to  the  action  of  vapours  of  vinegar,  or  by  placing  the  metal  between  pieces  of 
ooane  flannel  soaked  with  that  liquid.    The  formula  of  the  substance  thus  produced  is — 

(^^|^^^^^}0a,2CuHa0a. 

Neutral  acetate  of  oopper»  first  made  by  the  Saracens  in  Southern  Spain,  and  since  the 
middle  of  the  fifteenth  century  by  the  Hollanders,  is  now  obtained  either  by — i.  Dissolving 
the  bflsio  salt  in  acetic  acid.  2.  Or  by  the  double  decomposition  of  sulphate  of  copper  and 
acetate  of  lead : — 

CUSO4+  I  <^f  1^^^}  02=PbS04+  I  (^^^^30)a|  0^. 

By  the  first  method  the  basic  acetate  is  dissolved  in  4  parts  of  acetum  distillatum 
(punfied  vinegar)  or  in  wood-vinegar,  the  liquid  being  placed  in  a  copper  cauldron  and 
heat  applied.  The  clear  liquid  is  decanted,  and  then  evaporated  in  copper  pans  until  a 
saline  crust  makes  its  appearance,  when  the  fiuid  is  transferred  to  wooden  vessels  pro- 
vided with  thin  laths  serving  as  a  solid  nucleus  for  the  crystals.  According  to  the  second 
plan,  the  solutions  of  the  two  salts  are  mixed,  the  liquid  decanted  from  Uie  sediment  of 
sulphate  of  lead,  and  next  evaporated  after  the  addition  of  some  acetic  acid,  until  a  crust 
of  the  salt  is  formed.  Instead  of  acetate  of  lead,  the  acetates  of  lime  and  baryta  are  now 
used.  The  neutral  acetate  of  copper  is  met  with  in  commerce  in  "  bunches"  (grappes), 
eonmnting  of  deep  green-coloured,  non-transparent  crystals,  soluble  in  13-4  parts  of  cold, 
in  5  parts  of  hot  water,  and  in  14  parts  of  boihng  alcohol.  This  salt,  like  the  basic  acetates, 
is  highly  poisonous. 

AppHeaUnu  of  Both  basic  and  neutral  are  employed  as  oil-  and  water-colours.  In  Russia 
Vcrucrio.  verdigris,  mixed  with  white-lead,  is  frequently  used  as  an  oil  paint,  the 
result  being  the  formation  of  carbonate  of  copper  and  basic  acetate  of  lead.  The  former 
of  these  substances  yields  with  the  undecomposed  white-lead  a  bright  blue  colour,  which, 
after  painting,  turns  to  a  peculiarly  fine  green,  the  usual  colour  of  the  iron  roofs  of  the 
houses  in  Russia,  more  especially  in  Moscow  and  the  interior  of  the  country.  In  Holland 
the  same  mixture  is  frequently  applied  as  a  paint  to  outdoor  woodwork,  of  which  it  is  an 
excellent  preservative.  Verdigris  is  sometimes  further  applied  in  the  preparation  of  other 
copper  colours,  for  instance,  Schweinfurt-green ;  also  in  dyeing  and  oalioo-printing ;  in 
gilding  (see  Qold).    The  neutral  salt  was  formerly  used  in  the  preparation  of  acetic  add. 

Lead. 
(Pb = 207 ;  Sp.  gr.  =- 1 1  -37.) 

oeennvaee  of  Lead.  This  metal  has  been  known  from  a  remote  antiquity.  It  is  only 
rarely  found  native;  its  chief  ore  is  galena  (PbS).  It  also  occurs  as  Boumonite, 
ofT  antimonial  lead  ore,  consisting  of — 4177  parts  of  lead;  1276  copper;  2601 
antimony;  and  1946  sulphur;  formula  (3Cu2S,Sb2S3-|-2[3PbS,Sb2S3]).  From  this 
are  copper  as  well  as  lead  is  extracted.  The  other  lead  ores  of  more  or  less  importance 
are — cerusite  or  white  lead  ore  (PbC03) ;  green  lead  ore  (pyromorphite,  phosphate 
of  oxide  of  lead,  3[P205,3PbO]+PbCla) ;  mimetesite  (arseniate  of  oxide  of  lead, 
3[Afla05,3PbOl+PbCla);  vitriol  lead  ore  or  Anglesite,  sulphate  of  lead  (PbS04) ; 
yeUow  lead  ore  (molybdanate  of  lead,  PbMo04) ;  and  red-lead  ore  or  krokoite, 
chromate  of  lead  (PbCr04). 

"""^j^fteSSffiS.^***  Galena  is  the  chief  lead  ore,  98*9  of  the  metal  produced  being 
extracted  from  it.  It  contains  8657  per  cent  of  lead,  and  1343  per  cent  of  sulphur^ 
with  sometimes  only  mere  traces,  sometimes  an  available  quautily  of  silver.  Galena 
exhibits  a  lead-grey  colour  and  a  strong  metallic  lustre,  crystallises  in  cubes,  is 
brittle,  and  has  a  sp.  gr.»775.  It  is  also  employed,  when  finely  ground,  and  known 
as  Alqnifoux,  for  the  purpose  of  glazing  coarse  pottery  ware ;  for  the  manufacture 
of  Pattinson's  white-lead ;  instead  of  sawdust  for  covering  the  floors  of  rooms  in  some 


60 


CHEMICAL  TECHNOLOGY. 


of  the  German  mining  districts ;  for  onuunental  purposes ;  jewellery ;  and  of  late  in 
a  pecoliar  process  of  ei:tractiiig  platinum  from  its  ore^. 

Lead  is  obtained  &om  galena  either  by  the  precipitation  method  or  by  roasting. 
The  former  process  is  based  upon  the  behavioui  of  metallic  iron  at  a  high  temperature 
towards  galena ;  for  if  these  two  substances  are  heated  together  the  result  is  the 
fonnation  of  sulphuret  of  iron  and  metalho  lead  (PbS+Fe=FeS+Pb).  Accordinglj. 
the  predpitation  method  consists  in  smelting  the  galena,  previously  freed  from  gangue. 
with  granulated  iron  obtiuned  by  ponring  molten  cast-iron  in  a  thin  stream  into  cold 
water.  The  operation  is  carried  on  in  a  shaft  furnace  ;  the  result  is  tlie  fartaaiiou 
of  metallic  lead,  and  of  B  lead  matte  consisting  essentially  of  sulphuret  of  iron, 
undecomposed  galena,  and  sulphuret  of  copper.  Sometimes  iron  ores  and  slogs  of 
ironworks  are  applied,  in  which  case  the  oxygen  of  these  substances  aids  the 
desulphuration. 

The  foruoce  in  nee  for  the  smelting  is  represented  in  fignies  35,  26,  and  37.  b  is  the 
shitft ;  c,  D,  the  hearth  and  crucible,  which  as  exhibited  by  the  cut  is  parti;  outside  the 
Inmace.  By  means  of  a  channel  the  molten  metal  aan  tie  rou  off  from  n  into  the  tap 
cmoilile.  The  gases  and  vapours  previous  to  their  escape  into  the  chimney,  t,  are  mode 
to  pssa  throogh  the  flues,  as  indicated  by  the  arrows,  in  order  that  any  sohd  particles 
oontouiiug  lead,  which  the  blast  at  o  might  carry  off,  may  be  arreated.  The  ore  and 
iron,  previoosly  washed,  are  placed  in  alternate  layers  In  the  furuoee.    The  prodnots  ol 


Pia-  as. 


Fia.  36. 


the  smelting  eoUeeted  in  d,  are  lead,  cont^iug  silver, aud  lead  matte,  the  latter  oontaining 
about  30  lbs.  of  lead  to  the  ewt. ,  the  former  sometimes  3  lbs.  of  silver  to  the  same 
quantity,  while  copper  also  may  be  present.  This  lead  matte  is,  according  to  its  con- 
stituents, either  worked  np  for  cementation  copper,  or  added  to  other  slags  containing 
lead  and  again  smelted. 

°^'^mSJ^  ""^  "^^^  process  is  based  upon  the  behaviour  of  oxide  of  lead  and 
the  sulphate  of  that  oxide  towards  galena,  and  is  effected  on  a  large  scale  in  a 
ceverberatory  furnace.  By  the  action  of  the  oxygen  of  the  air  at  a  high  temperature 
upon  galena,  a  portion  of  this  mineral  is  converted  into  oxide  of  lead  and  snlphorons 
acid,  while  sulphate  of  lead  is  simultaneously  formed.  By  the  oxygen  of  the 
sulphate  aud  of  tlie  oxide  the  sulphur  of  any  undecomposed  galena  is  oxidised  and 
removed  (3PbO+PbS-4pb+S0,+O;PbSO,+PbS=2rb+2S0,),  If  there  is  present 
during  the  roasting  any  excess  of  galena,  there  is  formed  a  subsulphide  of  lead 


LEAD. 


61 


(I%«SI,  from  which  a  Email  quantity  of  metallic  lead  is  obtained  bj  liquation,  while 
the  residne  becomes  a  higlier  eulphuret  (2Pb3S=aPbS+aPb), 

The  English  proeeEB  of  lead  Bmeltiug  b;  roasting  and  Uqaation  is  based  upon  the 
reaction  joiit  deBCiibed,  and  is  aamed  on  in  a  (omace  exhibited  in  fig.  iS,  The  hearth, 
conBtmcted  of  slag  and  built  upon  a  masaive  wall,  ie  arranged  to  elope  in  all  direationa 
tcarda  the  tap-hole,  tbrontth  which  the  lead  nms  oS  into  a  oast-iron  pan  set  in  a  niche. 
The  Bgores,  0,0,0,  indicate  the  opeoingH  for  the  doors,  three  oa  each  aide  of  the  bmlding. 
T  is  a  funnel  Uirongh  which  the  ores  are  placed  on  the  hearth.  Ever;  six  or  BOTcn  honrs 
a  oharge  of  iC  cwts.  ot  ore  is  worked  oET,  while  the  oonBamption  of  fuel  amoontB  to  about 
half  that  weight  in  the  aame  time.  Care  is  taken  to  spread  the  ore  nniforml?  over  the 
hearth ;  thie  haiing  been  done,  the  heat  ia  giadnaU;  increased,  the  doors  of  the  fumaoa 
being  oloBed-  Aiter  a  lapse  ot  two  hours  the  doors  are  opened  stifficiently  to  Teutilate 
Itte  furnace  and  dissipate  the  smoke,  and  are  again  closed,  and  the  heat  increased  until 
tbe  masH,  from  which  lead  eTeryvhere  exudes  and  runs  oQ  to  the  lowest  level,  becomes 
by  stirring  and  the  addition  of  fluor-spar,  almost  perfectly  fluid.  This  point  having  been 
reached,  the  oppcr  layer  of  slag  is  mn  off,  at  once  cooled  with  water,  and  thos  solidifled. 

Fio.  aS. 


Tia»  aUg  is  termed  white  slag  from  its  white  or  hght  grey  eolonr  and  containi  aboat 
11  p«  oent  of  snlpbate  ol  lead.  Borne  small  coal  is  now  oast  into  the  hearth  in  order  to 
solidify  Che  tough,  pastf  alag  which  covers  the  lead,  after  which  the  tap-hole  is  opened 
lod  the  raw  lead  ran  off  into  the  iron  pan,  previously  heated  so  aa  to  keep  the  metal  in 
a  molten  state. 

>>■  Lasd.  The  metallic  lead  obtained  as  described  is  by  no  means  pure,  osnally 
eont^iiing  silver,  copper,  antimony,  arsenic,  and  other  metals  according  to  the  pnri^ 
of  the  ore.  The  separation  of  the  diver,  when  in  sofflcient  quantity  to  repay  the 
expense  of  extraction,  will  be  spoken  of  under  SUver ;  but  one  of  the  by-products  of 
tome  of  tbe  methods  of  extracting  that  metal  is  litharge,  oxide  of  lead,  which  is 
either  brooght  into  commerce  as  such  or  reduced  again  to  metallic  lead  by  a  process 
here  described. 

"T^i;^  •*  This  process  is  pursued  in  a  reverberatory  furnace  by  placing  on 
the  hearth  a  mixture  of  litharge  and  small  coal.  The  lead  resulting,  known  as  hard 
lead,  in  contradistinction  to  the  soft  lead  obtained  &om  refined  litharge,  is  nsnally 
not  quite  pore.  In  order  to  give  some  idea  of  the  compositton  of  the  varions  kinds 
of  lead  as  obtained  at  Freiberg,  Germany,  wo  quote  the  following  results  of  analyses 
by  Dr.  Reich  :— 

AnUmonial  lead. 


Bawlead 

Lead    .    . 

■    9772 

Arsenic     . 

136 

Antimony. 

.      07i 

Iron .    .     . 

007 

Copper-    . 

.      o-as 

SUver  .    . 

0*49 

Beflned  lead.      Hard  lead. 
99' z8  8t6o 

016  790 


Hulden. 


BalsbrOek. 
8760 


62  CHEMICAL  TECHNOLOGY. 

FropeztiM  of  Load.      The  oolooT  and  general  physical  properties  of  this  metal  are  too  well 
known  to  require  detailed  notice.    Lead  assumes  a  crystalline  form  with  difficulty,  bnt  it 
is  obtained  in  that  state  in  a  combination  of  cubes  and  ootahedra  by  some  metcJlnrgieal 
processes,  e.g.,  Pattinson's  method  of  silver  extraction.    Lead  is,  when  refined,  a  veir 
soft  and  tractable  metal ;  its  absolute  eohesiye  strength  is  small.    When  freshly  cnt  it 
exhibits  a  strong  metallic  lustre,  but  tarnishes  rapidly  on  exposure  to  air.    If  handled  it 
dirties  the  skin,  and  -gives,  when  rubbed  on  paper,  linen,  or  cotton,  a  plumbago-colonred 
mark.    Its  sp.  gr.  is  11*37 ;  ^  onbie  foot  weighs  about  600  lbs. ;  i  cubic  metre,  11,370  kilos. 
In  addition  to  the  metallic  impurities  usually  present  in  lead  and  already  alluded  to, 
some  of  its  oxide  is  commonly  mechanically  mixed  with  it,  impairing  its  midleability  and 
ductility,  but,  on  the  other  hand,  increasing  its  resistance  to  pressure.    Lead  belongs  to 
the  most  readily  fusible  metals,  fusing  far  below  red  heat,  at  332^ ;  on  cooling  it  oontraets 
and  assumes  a  concave  surface.    Lead  is  volatilised  and  boils  at  a  strong  white  heat,  air 
being  excluded.    It  is  not  well  suited  for  being  worked  with  files  or  cold  chisels,  the  former 
becoming  clogged,  and  the  latter  blunt.    Sheet  lead  is  out  with  knives  of  well-tempered 
steel,    l^is  metal  does  not  take  up  more  than  about  1*5  per  cent  of  zinc ;  0*07  per  cent  of 
iron,  and  rather  more  copper,  but  alloys  readily  with  tm,  bismuth,  and  antimony. 
AppUeaUoni  of      Lead  is  employed  in  a  variety  of  ways  in  building.    It  is  much  used  for 
Metoiiio  Lead,    the  leaden  chambers  of  sulphuric  acid  works,  and  for  this  purpose  should 
be  as  free  as  possible  from  any  impurities  or  foreign  metals,  all  of  wldoh  impair  the 
resistance  of  the  sheets  of  lead  to  the  acid  vapours,  and  cause  the  metal  to  become 
gradually  perforated  with  holes  and  cracks.    The  metal  is  further  employed  for  leaden 
pans  and  other  apparatus  in  chemical  manufactories,  for  gas-  and  water-pipes,  for  rifle 
balls,  and  for  many  other  purposes  too  numerous  to  be  here  specified. 

uaxvaiMoton  of  Shot  This  manufacture  consists  of  five  distinct  operations,  vis. — (z)  the 
melting  of  the  lead ;  (2)  the  granulation  of  the  molten  metal ;  ^3)  the  sorting  of  the  grain  of 
various  sizes ;  (4)  separation  of  irregularly-shaped  shot ;  and  (5)  the  polishing  of  the  shot. 
Lead  intended  for  this  manufacture  is  never  required  to  be  pure,  and  arsenic  is  purposely 
added,  because  experience  has  taught  that  this  addition  improves  the  spherical  shape  of 
the  shot.  The  quantity  of  arsenic  depends  upon  the  quality  of  the  lead,  but  varies  from 
0'3  to  0*8  per  cent :  too  much  causes  an  irregular  shape,  and  too  little  has  the  same  defect. 
The  arsenic  is  added  either  as  arsenious  add,  in  which  case  the  lead  is  melted  under  a 
layer  of  powdered  charcoal,  or  metallic  arsenic  wrapped  in  a  piece  of  paper  is  introdnoed 
under  the  surface  of  the  molten  lead  by  means  of  a  suitable  pair  of  foreops.  The 
granulation  of  the  lead  is  obtained  by  the  use  of  a  shallow  sieve-like  iron  vess^ 
technically  termed  a  card,  provided  with  holes  of  regular  size.  The  dross  and  scrapings 
from  former  smeltings  are  not  removed,  as  they  prevent  the  lead  running  too  readily 
through  the  holes.  The  operation  of  granulation  is  carried  on  in  shot  towers,  the  card 
with  ihe  molten  lead  being  at  the  top,  the  metal  assuming  a  spherical  shape  while  falling. 
The  small  spheres  or  drops  are  collected  in  water,  to  every  100  parts  of  which  0*025  puts 
of  sulphide  of  sodium  is  added  in  order  to  coat  the  metal  with  a  small  quantity  of 
sulphide  of  lead  and  prevent  its  oxidation.  Shot  is  also  made  on  an  entirely  different 
plan  embodying  the  application  of  centrifugal  force.  The  molten  metal  is  forced  with 
great  speed  through  openings  in  a  centrifugal  machine,  making  1000  revolutions  per 
minute,  the  shot  or  particles  assuming  a  spherical  shape  by  reason  of  the  great  force  of 
impact  with  the  air  near  the  machine.  The  sorting  of  the  shot  is  effected  by  variously- 
sized  sieves,  and  the  separation  of  the  imperiectly-shaped  grains  is  obtained  by  causing 
the  shot  to  run  over  a  long  slightly  sloping  table  provided  with  ledges  of  wood  to  prevent 
the  shot  falling  off  sideways.  Only  the  perfectly  spherical  grains  of  shot  reach  the 
lower  end  of  the  table.  Lastly,  the  shot  is  polished  by  placing  100,000  parts  by  weight 
of  shot  and  6  parts  by  weight  of  graphite  together  in  a  cylindrical  iron  vessel  made  to 
rotate  slowly  on  a  horizontal  axis.  In  this  country  some  manufacturers  prefer  to  use  an 
amalgam  of  tin,  or  simply  mercury,  instead  of  graphite,  for  polishing.  The  loss  of  lead 
in  the  manufacture  of  shot  amounts  to  about  2  per  cent.  The  sizes  and  trade  names  of 
the  several  kinds  of  shot  vary  in  different  countries ;  in  Germany  No.  o  is  the  largest  and 
No.  10  the  smallest  size. 

AUoysot  Load.  THb  foUowisg  alloys  of  lead  in  daily  use  are  made  on  a  large  scale : — 
Bofi  lead  solder  as  used  by  tinsmiths,  equal  paris  of  lead  and  tin ;  the  alloy  used  for 
organ  pipes,  usually  96  parts  of  lead  and  4  of  tin,  but  often  more  tin  is  added  ;  white 
metal  alloy  for  domestic  utensils,  as  coffee  and  teapots,  consists  of  lead,  antimony, 
and  tin ;  alloy  for  ships'  nails,  3  parts  tin,  2  part-s  lead,  i  part  antimony.  The  lecid 
used  by  the  Chinese  for  lining  tea-chests  consists  of  126  parts  lead.  175  parts  tin. 


LEAD.  63 

1*25  parts  copper,  with  a  trace  of  zinc.    Other  alloys,  such  as  type  metal,  will  be 

spoken  of  presently. 

Pebparations  of  Lead. 

oxidcof  LMd.      This  substance  is  oommercially  employed  in  two  different  forms,  viz., 
Bs  massicot  or  as  litharge. 

li^wiw*.  Massicot,  or  yellow  oxide  of  lead,  occurs  as  a  yellow  or  ruddy-coloured 
powder,  obtained  eithw  by  heating  carbonate  or  nitrate  of  lead,  or  by  calcining 
metallic  lead  on  the  hearth  of  a*  reverberatory  furnace.  Before  chromate  of  lead 
was  known,  massicot  was  used  as  a  yellow  pigment.  At  red  heat  this  substance 
foses  and  becomes  glassy.  In  most  instances  it  is  not  a  pure  oxide  of  lead,  but 
mixed  with  silicate  of  lead,  the  fact  being  that  oxide  of  lead  at  a  red  heat  strongly 
attacks  any  material  containing  silica,  dissolving  the  silica  and  combining  with  it. 
utkxcc-  Litharge  is  a  fused  crystalline  oxide  of  lead,  and  is  obtained  as  a  by- 
product of  the  separation  of  silver  from  lead  in  the  process  to  be  fully  described  under 
SOver.  Litharge  always  contains  a  larger  or  smaller  quantity  of  oxide  of  copper. 
Glide  of  antimony,  traces  of  oxide  of  silver,  and,  according  to  Dr.  Wittstein,  metallic 
lead,  varying  in  quantity  from  i'25  to  3*  10  per  cent.  The  oxide  of  copper  can  be 
removed  by  digesting  the  litharge  with  a  solution,  cold  of  course,  of  carbonate  of 
ammonia.  Litharge  absorbs  carbonic  acid  from  the  atmosphere,  combines  at  a  higher 
temperature  with  silica,  forming  with  it  a  readily  fosible  glass,  is  soluble  in  acetic 
and  nitric,  and  also  in  very  dilute  hydrochloric  acids,  and  is  equally  soluble  in  boiling 
solutions  of  caustic  potassa  and  soda.  It  is  insoluble  in  carbonate  of  ammonia  and 
in  the  carbonates  of  potassa  and  soda.  Litharge  is  largely  used,  entering  into 
various  compounds  for  glass,  so-called  crystal-glass,  flint-glass,  strass  for  imitating 
jewels,  for  glazing  pottery  and  eartlienware,  as  a  flux  in  glass  and  porcelain  staining, 
for  the  preparation  of  boiled  linseed  and  poppy-seed  oil,  for  the  preparations  of  lead- 
plaster,  putty,  minium,  red-lead,  and  acetate  of  lead.  A  solution  of  oxide  of  lead  in 
caiistic  aoda  lye  is  applied  in  the  preparation  of  stannate  of  soda ;  this  solution  Ls 
also  used  for  imparting  to  combs  and  other  toilet  articles  made  of  horn  the 
appearance  of  tortoiseshell  or  of  buffalo-horn.  A  very  dilute  solution  is  used  as  a 
^-dye,  and  again  in  metallochromy  to  produce  iridescent  colours  on  brass  and 
bronze. 

WrtML  Be44e«d.  Rcd-lcad  is  a  combination  of  oxide  of  lead  wiih  a  superoxide,  the 
formula  being  Pb304-  Red-lead  of  excellent  quality  is  largely  manufactured  near 
Newcastle-on-Tyne,  by  carefully  heating  oxide  of  lead  in  a  reverberatory  furnace 
expressly  built  for  that  purpose,  the  access  of  air  being  limited  so  as  to  prevent 
*be  fusion  of  that  portion  of  the  oxide  which  cannot  then  be  converted  into 
minium.  Sometimes  metallic  lead  is  oxidised  in  a  reverberatory  furnace,  the  process, 
as,  for  instance,  at  Shrewsbury,  being  so  arranged  that  at  the  hotter  places  of  the 
^^iniace  massicot,  and  at  the  cooler  red-lead,  is  produced.  The  finest  coloured  minium, 
or  Paris-red,  is  obtained  from  carbonate  of  lead  by  the  same  method.  According  to 
Mr.  Burton's  plan,  sulphate  of  lead  is  heated  with  Chili  saltpetre,  and  after  the  mass 
^  been  exhausted  with  water  the  red-lead  is  left,  while  sulphate  and  nitrite  of 
8oda  are  dissolved.  Red-lead  is  used  for  a  variety  of  purposes,  many  similar  to  the 
plications  of  oxide  of  lead.  Besides  being  applied  as  a  cement,  when  mixed  with 
bnseed-oil  and  mastic,  for  the  flanges  of  steam-pipes,  it  chiefly  enters  the  market  as 
a  pigment,  being  for  that  purpose  either  mixed  wdth  water  or  with  linseed-oil,  in  both 
Mwtances  covering  extremely  well. 


64  CHEMICAL  TECHNOLOGY, 

Superoxide  of  Lead.  When  red-lead  is  treated  with  moderately  strong  nitric  acid,  there  are 
formed  nitrate  of  protoxide  of  lead  and  superoxide  of  that  metal,  PbOz,  a  brown  oolonied 
powder  largely  nsed  in  the  composition  of  the  phosphorus  mixture  for  lucifer  matches.  The 
mixture  known  in  lucifer  match  works  as  oxidised  minium,  is  a  dried  composition,  con- 
sisting of  nitrate  of  protoxide  of  lead,  superoxide  of  lead,  and  undecomposed  red-lead,  and 
obtained  by  drying  a  magma  of  minium  and  nitric  acid. 

co»w*^**oM  I*  o^*«  Among  the  salts  of  lead  employed  industrially,  the  followiiig 
are  the  most  important: — 

Acetate  of  LewL         This  Salt, 

(^^»^^*^i)0,  +  3H,0) 

consists  in  loo  parts  of: — Oxide  of  lead,  5871 ;  acetic  acid,  27'o8 ;  water,  14-21. 
It  crystallises  in  four-sided  columnar  figures;  is  soluble  in  1*66  parts  of  water  and 
8  parts  of  alcohol.  When  isubmitted  to  dry  distillation  it  yields  neutral  carbonate 
of  lead  and  aceton,  which  volatilises.  When  heated  with  sulphuric  acid  it  yields 
acetic  acid,  sulphate  of  lead  remaining  in  the  retort.  Acetate  of  lead  is  prepared  by 
heating  litharge  or  massicot  with  rectified  vinegar,  or  with  wood  vinegar  in  leaden 
or  in  tinned  copper  pans.  The  clear  liquid  is  decanted  and  evaporated,  and  then 
left  to  crystallise  in  porcelain  basins  or  in  wooden  tubs :  100  parts  of  litharge  yield 
150  of  acetate  of  lead.  This  salt  is  largely  used  in  dyeing  and  calico  printing,  in 
obtaining  red  liquor  or  acetate  of  alumina;  and  for  the  preparation  of  vamishes, 
white-lead,  and  chrome-yellow.  We  shall  speak  of  sub-acetate  of  lead,  tribasie 
acetate  of  lead,  when  considering  the  manufacture  of  white-lead. 

chronuite  of  Lead.  The  basls  of  chromate  of  lead,  and  indeed  the  substance  from  which 
all  chromium  preparations  are  derived,  is  the  chrome-iron  ore,  consisting  mainly  of 
protoxide  of  iron  and  oxide  of  chromium  (FeO,Gr203,  or  Gr2Fe04).  It  is  a  magnetic 
iron  ore,  isomeric  sesqui-,  or  per-oxide  of  chromium  having  been  substituted  for  the 
peroxide  of  iron,  but  the  mineral  varies  in  composition,  often  containing  considerable 
quantities  of  alumina,  magnesia,  and  protoxide  of  chromium.  It  is  met  with 
interspersed  through  very  hard  metamorphic  rocks  in  some  parts  of  Scotland,  in 
colour  a  steel-grey  or  pitchy  black.  Its  value  for  industrial  purposes  depends  upon 
the  quantity  of  oxide  of  chromium  it  contains;  and  according  to  M.  Glouets 
analysis  (1869)  the  following  chrome-iron  ores  contained  the  quoted  quantities  per 
cent  of  chromic  oxide : — 


M«atzal,  or  TeUow  Chromate 
of  Potaoa. 


Chrome- 

iron 

from  Baltimore            45 

»» 

if 

Norway               40 

ft 

»» 

France         37 — 51 

»» 

it 

Asia  Minor          53 

>f 

ts 

Hungary              31 

i» 

»> 

Oural  (RuRRia)    495 

»j 

»» 

California           425 

•      This  salt, 

CrO^) 

/^       Tr  r^^r\ 

is  prepared  by  heating  chrome-iron  ore,,  previously  pulverised  and  cleansed,  with 
carbonate  and  nitrate  of  potassa  on  the  hearth  of  a  reverberatory  furnace.  The 
oxygen  of  the  saltpetre  causes  the  higher  oxidation  of  the  protoxide  of  irun  and 


CHROMIUM.  65 

sesquioxide  of  chromium,  the  latter  being  converted  into  chromic  aoid.  The 
thoronghly  sintered,  not  molten,  mass,  is,  after  cooling,  again  ground  up  and 
lixiviated  with  boiling  water,  and  also  boiled  for  a  time  to  extract  the  neutral 
chromate  of  potassa.  Wood  vinegar  is  added  to  the  solution  to  precipitate  the 
alamina  and  silica,  after  which  the  clear  liquid  is  evaporated,  until  a  film  of  saline 
material  begins  to  form,  when  it  is  left  to  crystallise.  The  crystals  take  a 
cdnmn-like  form,  and  are  of  a  lemon-yellow  colour,  readily  soluble  in  water,  but 
insoluble  in  alcohol,  and  having  a  great  tendency  to  become  converted  into  bichromate 
or  red  chromate  of  potassa.  This  conversion  of  the  neutral  salt  into  the  hi-,  or  aoid 
salt,  is  at  once  effected  by  the  addition  to  its  solution  of  sulphuric  or  nitric  aoid. 
The  bichromate  of  potassa  or  acid  chromate,  K«0r2O7,  crystallises  in  anhydrous, 
anrora-red  coloured  prismatic  crystals,  soluble  in  10  parts  of  water.  This  solution  is 
hi^y  caustic  and  poisonous.  When  heated  to  redness  the  salt  gives  off  oxygen, 
leaving  oxide  of  chromium  and  neutral  chromate  of  potassa  in  the  retort;  the 
bichromate  is  prepared  from  the  neutral  salt  by  the  addition  to  its  solution  of  either 
solphuric  or  nitric  acid,  preferably  the  latter  on  account  of  the  formation  of  nitrate 
of  potassa,  which  may  be  either  sold  or  used  in  the  manufacture  of  the  neutral 
chromate. 

M.  Jaoqoelain  proposes  that  the  chrome-iron  should  be  mixed  with  ohalk  and  the 
nuxtnre  heated  and  frequently  sturred,  then  oooled,  pulverised,  and  put  into  water,  with 
the  addition  of  enough  Bulpnuxic  aoid  to  produce  a  weak  reaction,  the  result  being  the 
fonnation,  first  of  chromate  of  lime,  which,  by  the  addition  of  the  acid,  becomes  the 
Viehromate  of  that  base.  The  sulphate  of  protoxide  of  iron  present  in  this  solution  is 
pndpitated  by  means  of  ohalk.  In  order  to  convert  the  bichromate  of  lime  into  the  oor- 
responding  potassium  salt,  it  is  only  necessary  to  add  a  solution  of  carbonate  of  potassa, 
the  result  being  of  course  the  precipitation  of  carbonate  of  lime  and  the  exchange  of 
the  ehromic  add  from  the  lime  to  the  potassa.  According  to  Tilghmann's  process 
ehrome-iron  ore  is  mixed  with  2  parts  of  lime,  2  of  sulphate  of  potassa,  and  heated 
fordghteen  to  twenty  hours  in  a  reverberatory  furnace.  The  same  inventor  suggests 
the  heating  of  chrome-iron  ore  with  powdered  feldspar  and  lime.  Mr.  Swindells  ignites 
ehiome  ore  witii  equal  parts  of  either  chloride  of  sodium  or  chloride  of  potassium  to  the 
highest  possible  white  heat,  at  the  same  time  exposing  the  mixture  to  a  constant  current  of 
fsperheated  steam,  the  formation  of  sodium  or  potassium  chromate  resulting.  The  most 
hnportant  improvement  in  the  preparation  of  chromate  of  potassa  is  the  substitution  of 
ttrbonate  of  potassa  for  nitrate  of  potassa,  and  the  use  of  a  furnace  so  constructed  as  to 
>Ut  of  the  proper  access  of  air  to  the  strongly  heated  mass,  the  oxygen  of  the  air  being 
made  to  oxid^  uie  ehromic  oxide  to  chromic  acid.  Another  improvement  is,  that  in  using 
lime  nistead  of  alkali,  the  oxidation  of  the  chromic  oxide  is  greatly  accelerated,  by  reason 
that  when  lime  is  employed  instead  of  potassa  the  heated  materials  do  not  become  semi- 
foied  or  paHy,  but  remaining  pulverulent  admit  of  the  readier  access  of  air,  as  well  as 
prerenting  the  sinking,  on  account  of  higher  specific  gravity,  of  a  portion  of  the  chrome 
ere  to  the  bottom  of  tiie  hearth,  and  there  becoming  withdrawn  from  the  action  of  the 
heat. 

A»9ikitteMof  iht  Before  the  year  1820,  the  salts  spoken  of  were  only  used  for  the  pre- 
^vMiitMof  PoiM«.  paration  of  chrome-yellow;  it  was  then  a  very  expensive  process, 
^.,  the  ealeination  of  the  chrome-iron  ore  with  nitrate  of  potassa  only.  At  this  date, 
ILKceehlin  discovered  the  applicability  of  bichromate  of  potassa  to  the  obtaining  of 
^hat  is  teehnicaJly  termed  "  discharge**  for  Turkey-red — a  madder  colour — a  discovery 
loon  followed  by  others  bearing  upon  the  useful  applications  of  this  salt,  among  which  are 
the  fonnation  of  chrome-yellow  and  chrome-orange  in  calico-printing,  the  clu'ome-blaek 
m  dyeing,  the  oxidation  of  catechu  and  Berlin-blue,  the  discharge  of  indigo-blue,  the 
bleaching  of  palm-oil  and  other  fatty  substances,  the  preparation  of  mixtures  for  the  heads 
e(  Ineifer-matdies,  the  preparation  of  chromate  of  protoxide  of  mercury  and  chromic 
oxide  as  green-coloured  pigments  in  glass-  and  china-painting,  and  for  the  preparation  of 
Vert  Qoignet,  a  peculiar  hydrated  oxide  of  chromium : — 

(Cra)a' 


▼I 


Oc 


66  CHEMICAL   TECHNOLOGY. 

obtained  by  heating  i  part  of  bichromate  of  potassa  and  3  parts  of  crystallised  boric  acid, 
and  used  as  a  pigment  in  calico-printing.  As  might  be  expected,  all  these  discoTeries 
gaye  a  strong  impulse  to  the  mannfactnre  of  the  chromates  of  potassa,  which  have 
recently  fomid  still  farther  asefnl  applications  in  the  obtaining  of  colours  from  coal-tar,  in 
the  manofaotnre  of  chlorine  gas,  in  defnseling  brandy  and  other  spirits,  and  in  ttie  pnxifi- 
cation  of  wood- vinegar  made  from  the  cnide  pyroligneoas  acid. 

According  to  M.  J.  Persoz,  there  exist,  America  excepted,  only  six  manofaotories  of  the 
ohromates  of  potassa,  viz.,  two  in  Scotland,  one  in  France,  one  at  Trjdndhflm,  Norway,  and 
one  at  Kazan,  near  ^e  Onral,  Bnssia ;  the  total  production  of  these  Works  amounted  in 
1869  to  60,0Q0  cwts. 

^SSJ^iS!  T^ere  are  in  technical  use  three  different  compounds  of  lead  and 
chromic  add,  viz.,  neutr^d  chromate  of  lead  or  chrome-yellow,  basic  chromate  or 
chrome-red,  and  a  mixture  of  these  two  salts  constituting  chrome-orange.  The  first 
of  these  substances  is  obtained  by  two  methods: — (i)  By  the  precipitation  of  a 
solution  of  chromate  of  potassa  with  a  solution  of  acetate  of  lead;  or  (z)  by 
the  use  of  sulphate  or  chloride  of  lead.  According  to  the  first  plan,  the  operation 
begins  with  the  preparation  of  a  solution  of  lead,  for  which  purpose  granulated  lead 
is  put  into  wooden  tubs  placed  one  above  the  other,  and  the  taps  each  tub  is  provided 
with  being  turned  off,  vinegar  is  poured  into  the  upper  tub.  In  about  ten  minutes 
the  tap  at  the  bottom  of  the  tub  is  opened,  and  the  contents  let  into  the  second  tub. 
The  operation  is  repeated  with  all  the  tubs,  four  to  eight  in  number,  the  object  simply 
being  to  moisten  the  lead  thoroughly  with  the  vinegar,  so  as  to  cause  rapid  oxida- 
tion on  its  subsequent  exposure  to  air.  The  metal  soon  becomes  coated  with 
a  bluish-white  coloured  film,  and  when  this  is  apparent,  vinegar  is  again  poured 
into  the  topmost  tub  and  left  for  about  an  hour,  after  which  it  is  run  off  into  the 
second  tub,  and  the  operation  continued  until  there  is  obtained  a  saturated  solutfon 
of  basic  acetate  of  lead.  To  prepare  chrome-yellow  enough  vinegar  is  added  ia 
obtain  a  reaction,  and  the  fluid  left  to  deposit  any  suspended  sediment.  At  the  same 
time,  in  another  tub,  a  solution  of  25  kilos,  of  bichromate  of  potassa  in  500  litres  of 
water  is  kept  in  readiness.  The  clear  lead  solution  is  next  poured  into  the  bichro- 
mate solution  as  long  as  any  precipitate  ensues.  This  precipitate  is  well  washed, 
and  usually  mixed  with  gypsum,  or  sulphate  of  baryta,  to  obtain  the  lighter  chrome 
colours ;  finally  it  is  dried.  According  to  Liebig,  chrome-yellow  is  obtained  from 
sulphate  of  lead,  an  almost  useless  by-product  from  calico-printing-  and  dye-worfcBi 
by  digesting  it  with  a  warm  solution  of  neutral  chromate  of  potassa.  The  depth  of 
colour  of  die  ensuing  yellow  pigment  depends  upon  the  quantity  of  sulphate  of  lead 
which  is  converted  into  chromate  of  lead. 

Dr.  £[abich  states  that  there  exist  two  binary  compounds  of  chromate  and  sulphate  of 
lead,  the  formula  of  which  are :— PbS04-fPbCr04  and  2PbS04+PbCr04.  The  former  is 
obtained  when  a  solution  of  bichromate  of  potassa,  previouiuy  mixed  with  enough  sul- 
phuric aeid  to  cause  its  dissociation,  is  precipitated  with  a  solution  of  lead ;  wldle  the 
second  compound  is  formed  if  the  quantity  of  sulphuric  add  is  doubled.  According  to 
M.  Anthon  a  beautdfnl  chrome-yeUow  is  obtained  by  the  digestion  of  100  parts  of  txe&!^ 
predpitated  chloride  of  lead  with  47  parts  of  bichromate  of  potassium. 

chiomepited.  The  bflksic  chromatc  of  lead,  known  as  chrome-red  and  Austrian-cinnabar, 
PbCr04+PbH202,*  is  a  red-coloured  pigment  much  in  demand,  and  obtained  from  the 
yellow  or  neutral  chromate  of  lead,  dtiier  by  boiling  it  witii  a  caustic  potassa  solution,  or 
by  fusing  it  with  nitrate  of  potassa,  the  effect  being  that  half  of  the  chromic  add  is  with- 
drawn from  the  neutral  chromate.  Drs.  Liebig  and  W6hler  state  that  chrome-red  is  best 
obtained  by  fusing  together,  at  a  very  low  red-heat,  equal  parts  of  potassium  and  sodium 
nitrates,  gradually  pouring  into  the  fused  salt  small  quantities  of  chemically  pure  ydlov 

*  According  to  Dr.  Duflos,  see  **  Handbuch  der  Angewandten  Pharmaceutiseh-TeohniBcfa 
Chemische  Analyse,  <&o.,"  Breslau,  1871,  p.  293,  the  formula  of  this  substance  is  aPbO,Gr03, 
ADd  the  dried  salt  does  not  contain  any  water  as  a  component  part. 


> 


LEAD,  67 

ehromAte  of  lead.  After  oooling,  the  insolable  chrome-red  is  well  washed  and  dried.  It 
is  then  a  magnifieently-colonreid  oinnabar-like  orystallme  powder.  Professor  Didong 
prepares  dhrome-red  by  preoipitating  a  solution  of  acetate  of  lead  with  a  eolation  of 
ohromate  of  potassa  to  which  oanstio  potassa  has  been  added.  The  yarious  shades  and 
qualities  of  chrome-red,  from  the  deepest  vermiUion  to  the  palest  red,  are  caused  by  the 
differenoe  in  size  of  the  constituent  ciystalline  particles.  This  fact  is  proved  by  experiment, 
for  when  several  samples  are  uniformly  ground  to  a  fine  powder  the  result  is  the  production 
of  a  uniformly  deep-coloured  hue.  In  preparing  chrome-red  of  a  deep  eolour,  everything 
nhioh  might  interfere  with  or  injure  the  crystaUiBation  has  to  be  avoided,  liie  pigments 
eommercially  known  as  the  chrome-orange  colours  are  mixtures,  in  varying  proportions,  of 
the  basie  and  neutral  ohromates  of  lead,  and  are  usually  made  by  boiling  chrome-yellow 
with  milk  of  lime.  M.  Anthon  recommends  for  the  preparation  of  a  good  chrome-orange 
the  treatment  of  100  parts  of  chrome-yellow  with  55  parts  of  chromate  of  potassa  and 
12 — 18  parts  of  oaustio-lime  made  into  milk  of  lime, 
cbrm^ozide.  or      ^hls  substanoe,  Gr203,  is  used  in  glass-  and  porcelain-staining  as  a 

oiinaa»4ixtB.  cotUew  grand  feu^  that  is  to  say,  it  stands  the  most  intense  heat  provided 
no  reducing  materials  are  allowed  to  affect  it.  It  is  commercially  known  under  the  name 
of  chrome-green  as  an  indelible  pigment  for  printing,  being  especially  employed  for  bank- 
notes. It  is  prepared  in  various  ways,  the  finest  being  obtained  by  heatmg  chromate  of 
protoxide  of  mercury,  but  this  method  is  far  too  expensive  to  admit  of  any  extensive  appli- 
eation«  Dr.  Lassaigne  heats  equal  molecules  of  sulphur  and  yellow  chromate  of  potassa, 
and  exhausts  the  mixture  with  water,  leaving  the  insoluble  green  sesquioxide  behind. 
Professor  Wohler  prefers  to  mix  the  yellow  chromate  of  potassa  with  sal-ammoniac,  to  heat 
that  miztore,  and  afterwards  treat  it  with  water,  leaving  the  insoluble  chrome-green  as  a 
ihie  powder. 

Among  other  methods  of  preparing  the  anhydrous  sesquioxide  is  the  heating  of  an 
intimate  mixture  of  bichromate  of  potassa  and  charcoal.  The  hydrated  oxide  of  chro- 
mium, aooording  to  the  formula  Gr4H60Q,  is  met  with  in  the  trade  under  a  variety  of 
names,  and  often  contains  boric  or  phospnorio  acids,  not,  however,  as  an  essential  oonsti- 
toent  (see  Dr.  P.  Schiitzenberger's  formula  on  p.  65  for  Guignet's-green),  but  as  a  renmant 
of  imperfect  preparation.  This  hydrated  oxide,  the  preparation  of  which  to  ensure  a  good 
colour  is  rather  a  difficult  matter,  requiring  very  careful  manipulation,  is  known  as 
Emerald-green,  Pannetier-green,  Matthieu-Plessy-green,  and  Amaudon-green.  The  pigment 
in  used  as  an  artist's  colour  and  in  calico-printing  as  a  substitute  for  Sohweinfurt-green, 
but  is  very  expensive. 

Or  ) 
ciiwwM  iiiiw       This  salt,  ^^[4S04-H24H20,  is  obtained  in  rather  large  quantities  as  a 

by-product  of  the  manufacture  of  aniline-violet,  aniline-green,  and  anthracene-red.  It  is 
a  deep  violet-coloured,  octahedrically  crystallised  substance,  now  used  to  some  extent  as  a 
mordant  in  dyeing,  for  rendering  gum  and  glue  insoluble,  for  waterproofing  woollen 
fabrics,  and  for  the  preparation  of  chromate  of  potassa. 
cteiak  ohioite.  This  Compound,  CraCl^,  best  prepared  by  the  decomposition  of  sul- 
phuret  of  chromium  by  means  of  chlorine,  constitutes  a  crystalline  violet-coloured  mica- 
like material,  employed  in  the  manufacture  of  coloured  paper  and  paper-hangings. 

wuto-LMid.      This  very  important  preparation  obtained  from  lead  is  the  basic  car- 

Ixniate  of  the  oxide  of  that  metal,  its  formula  being, 

PbOOO,+«>iMHO) 

According  to  the  method  employed,  white-lead  is  commerciaUy  known  as  of 
Holland  or  Dutch,  Frenoh  or  English  manufacture.  The  Dutch  mode  of  making 
^bite-lead  is  founded  on  the  fSaot  that  when  metallic  lead  comes  in  contact  with 
the  vapours  of  acetic  acid,  carbonic  add,  and  oxygen,  at  a  sufficiently  high  tem- 
pffiatore,  the  metal  is  converted  into  basic  carbonate  of  the  oxide  of  lead.  It  is 
<riite  evident  from  this  brief  statement  that  the  chief  conditions  being  fulfilled,  the 
methods  of  operation  may  be  more  or  less  yaried.  In  Holland,  Belgium,  and  some 
puts  of  Germany,  the  lead — as  pure  as  possible  and  free  from  silver,  which,  even  in 
mudl  quantities  greatly  impairs  the  good  colour  of  the  white-lead — ^is  cast  into 
^  strips,  which  are  wound  in  a  spiral  and  placed  in  coarse  earthenware  pots, 
^g-  29).  Conmion  vinegar  is  poured  into  the  lower  part  of  these  pots,  some  beer- 
yeast  being  added.    The  lead  is  then  placed  on  a  perforated  piece  of  wood,  so  as  to 


68  CHEMICAL  TECHNOLOGY. 

prereut  direct  contact  with  the  vinegar.  After  this  Qie-pote  are  oovered  wilhlead«n- 
plat«B  and  buried  (see  Fig,  30)  in  a  masa  of  horse-dung  or  spent-tan  and  dung.  The 
fermentation  of  the  dung  oansea  the  requisite  itkcrease  of  tempwatnre,  and  tbe 
vinegar  evaporating,  aided  hy  the  oxygen  of  the  air,  oonverta  the  lead  into  basic 
acetate,  which  in  its  turn  is  oonverted  into  basic  carbonate  of  lead  bj  the  cartxKiie 
add  resulting  from  the  fenaentiiig  manure.  This  rather  clamsy  prooMS  h«s  given 
plaoB  in  Oennany  to  the  chamber  method,  consisting  essentially  in  the  follmring 
arrangement.  Instead  of  the  pots  being  made  the  receptacles  for  the  lead,  the  Btarips 
of  that  metal  are  bent  and  suspended  on  a  series  of  laths  run  laigthwise  Uizoa^  tfae 
chamber,  on  tiie  floor  of  which  is  placed  a  layer  of  spent  Ian,  marc  of  grapes,  or  other 
fermentable  material,  saturated  with  vinegar.  Ail  improvement  upon  this  arrange- 
ment is  to  have  the  chamber  constnicted  with  a  donble  flooring,  one  water-ti^t,  the 
other  a  light  planking  perforated  so  as  to  admit  of  the  vapours  of  vinegar  being 
carried  into  the  compajtment.  The  action  upon  the  lead  is  in  each  case  the  same ;  it 
is  converted  chiefly  into  whit«-lead.  and  this  cmde  product  is  purified  fhan  any 
adhering  acetate  of  lead  hy  washing  with  water  before  being  brought  into  the  market- 
There  is  atill  in  Qse  in  this  conntry  a  modification  of  the  method  practised  by  the 
Dntch,  who,  by-the-bje.  are  not  the  inventors  of  white-lead  manufacture,  the  tme 


origiii  being  Saracenic,  (he  trade  being  successfully  earned  on  by  these  semi-aaTagn 
in  Southern  Spain,  whence  the  Dntch  brought  over  the  art  in  the  sixteenth  century  to 
Eollaad.  This  modification  consigts  in  the  following  arnmgement : — Qronulatri 
lead  ia  first  moistened  with  about  15  per  oeot  of  vinegar,  the  metal  being  previon^ 
placed  on  hurdles  in  a  wooden  box,  the  interior  of  whioh  is  heated  by  mean*  of  steam 
to  35°,  some  steam  being  introduced  to  keep  the  lead  moist  If  oare  is  taken  to 
supply  carbonic  acid,  after  from  ten  to  fourteen  dtye  the  operation  is  finished,  and 
the  product  having  been  lixiviated  with  water  and  dried,  is  ready  for  use. 
EuuiaHMindiif  According  to  this  plan  the  metal  is  melted  in  a  large  iron  eanldron, 
wuu.LwL  and  then  made  to  flow  on  the  hearth  of  a  reverberatory  furnace  so 
as  to  convert  tiie  lead,  by  proper  access  of  air,  into  lithtage,  which  is  obtained  in  a 
very  finely  divided  stale  by  a  peculiar  arrangement  of  the  fiimace.  The  hearth  is 
constmoted  with  a  gutter,  into  which  the  fumng  mass  flows ;  and  the  mdea  or  waDs 
of  the  gutter  are  perforated  to  admit  of  the  passage  of  the  molten  litharge,  while  the 
heavier  metal  sinks  to  the  bottom.  The  litharge  is  nest  mixed  with  i-iooth  of  its 
weight  of  a  solution  of  acetate  of  lead,  and  then  placed  in  a  series  of  closed  troufi^ 
conununicatir^  with  each  other  and  admitting  of  the  passage  of  a  current  of  impure 
carbonic  acid,  obtained  by  the  combustion  of  coke  in  a  fomace  provided  with  a  blast 
to  give  an  impulse  to  the  gas.  The  litharge  is  coutinnally  stirred  1^  machinery  to 
accelerate  the  absorption  of  the  carbonic  acid  gas.    White-lead  made  by  this  prooess 


tortn  reiy  well,  md  is  preferred  to  that  prepared  by  the  wet  method.  We  may 
mcntioii  in  paasmg  that  it  is  the  custom  in  this  oonittry  to  bring  white-lead  into  the 
msito  ground  with  linseed  oil  to  a 
tliiak  paste,  paeked  in  stioDg  oaken 
logs  or  in  iron  canisters 
itaAa^dtoi  This  metiiod  m 
wSf^  Tented  by  UM  Thi 
Bird  the  elder,  and  Roard  is  not 
•Bly  geuenllj  adopted  m  France 
but  in  all  oonntries  where  it  is 
d«iired  to  cany  ont  a  really  sound 
and  rational  plan  of  white  lead 
■unnfaetore.  The  method  is  as 
foUows: — LiUiarge  is  dissolved  in 
■Mtia  add  to  obtain  a  solution  of 
bsiie  acetate  of  lead, 

and  through  the  solution  a  current 
•tfeaibonio  add  gaa  is  passed.  Two 
mdecoles  of  oxide  of  lead  are  con- 
verted into  irtiite-tead,  while  neutral 
•Mate  of  lead  romains.  Litharge 
ii  i^ain  added  to  the  aolntion  of 
Ibis  salt,  and,  by  digestion,  more 
nbasstate  of  lead  is  obtained,  which 
18  ^flied  as  just  described. 
"VSPm''  The  machmery 
'"alll?."  end  contrivances  at 
Cliehy,  near  Paris,  for  effecting  the 
xethed  just  explained,  are  exhi- 
bited in  Fig.  31.  In  the  tub,  a,  the 
litharge  is  dissolved  in  acetic  acid, 
i  c  is  a  stirrer,  moved  by  means  of 
the  shaft  shown  in  the  engraving, 
bearing  at  the  top  a  pnlley  for  the 
rtnp.  The  solution  of  basio  acetate 
<tf  lead  can  be  run  off  Uirough  the 
t^i  into  the  vessel  e,  made  of  copper 
and  tinned  inside,  the  object  being 
to  let  the  impurities  the  solution 
mi^t  contiun  subside.  From  e  the  fluid  is  led  into  the  decomposition  vessel  con- 
structed with  800  tubes,  which  pass  from  the  lop  to  a  depth  of  32  centims.  beneath  the 
kvel  of  the  fluid.  These  tubes  are  in  communication  with  the  main-pipe,  gg,  which 
alio  conununicatea  with  the  washing  apparatus,  p,  answering  the  porpose  of  purifier 
lor  the  carbonic  acid  gas  generated  in  the  small  lime-ldln,  o,  by  the  ignition  of  a 
■nixture  of  3|  parts  by  bulk  of  chalk  and  i  part  by  bulk  of  coke  with  sufficient  access 
(rftir.  The  decomposition  of  the  basic  acetate  of  lead  being  finished  in  from  twelve  to 
fourteen  hours,  the  supernatant  liquor,  neutral  acetate  of  lead,  is  run  off  into  the 


70  CHEMICAL   TECHNOLOGY. 

vessel,  t,  and  the  semi-fluid  magma  of  white-lead  passes  into  o.  The  pnmp,  b,  serves 
to  again  convey  the  neutral  acetate  to  the  tank,  a,  and  the  operation  is  re-commenced. 
The  white-lead  in  o  is  well  washed — ^the  first  wash-water  being  conveyed  back  to  the 
tank,  A — and  after  drying  is  ready  for  use.  In  order  ta  obtain  the  carbonic  acid 
cheaply,  it  has  been  proposed  to  ignite  a  mixture  of  chalk  or  limestone,  charcoal,  and 
peroxide  of  manganese  (CaCOj-f  C+3MnOj,=Mn304-f  CaO+zCOa.)  Where  admis- 
sible, the  carbonic  acid  resulting  from  the  fermentation  of  beer- wort,  or  of  distillezy- 
wash,  may  be  applied.  Natural  sources  of  carbonic  acid  sometimes  occur  in  the 
neighbourhood  of  active  or  extinct  volcanoes ;  and  near  Brohl,  dose  to  the  Laacher  Sea 
in  Bhenish  Prussia,  a  locality  well-known  to  tourists,  a  very  plentiful  and  continuoiis 
supply  of  carbonic  acid  is  naturally  obtained  and  actually  applied  for  the  poipoae 
under  consideration. 

Among  the  very  various  suggestions  for  improved  methods  of  making  white-leadt  and 
for  which  an  enormous  number  of  patents  have  been  taken  out,  especially  in  this  coontiy 
and  in  the  United  States,  we  briefly  mention  the  following : — MM.  Button  and  Dyer  first 
slightly  moisten  litharge  with  water,  next  mix  it  with  a  small  quantity  of  a  solution  oi 
acetate  of  lead,  place  the  mixture  in  a  stone  trough,  agitating  and  passing  hot  oarbonie 
acid  over  it.  Pallu  (1859)  causes  finely-divided  lead  to  be  thrown  with  great  force,  fay 
means  of  a  centrifugal  machine,  on  an  inclined  plane,  care  being  taken  to  moisten  the  lead 
with  acetic  acid.  After  the  lapse  of  an  hour,  the  finely-divided  lead  is  converted  into 
acetate  and  carbonate.  A  solution  of  acetate  of  lead  is  then  poured  over  the  mass,  and 
the  acetate  of  lead  it  contains  is  dissolved,  while  the  white  lead  is  carried  into  a  tank,  and 
there  forms  a  deposit.  M.  0-runeberg  ^1860)  prepares  white-lead  by  submitting  grann- 
laled  lead  to  the  simultaneous  action  01  air,  acetic,  and  carbonic  acid,  aided  by  Uie  rapid 
motion  of  the  metal.  From  private  information  obtained  from  the  largest  wholesale  hoose 
.  in  London,  whose  connections  and  trade  relations  embrace  literally  the  whole  world, 
dealing  in  white-lead,  we  have  learned  that  not  i-ioooth  part  of  the  lead,  as  it  is  techni- 
cally termed,  of  good  and  saleable  quality  met  with  in  the  trade,  is  made  by  these  new 
processes,  since  the  products  of  most  of  them  are  deficient  in  some  respect  or  other. 
wuto-Le»d  from  It  is  wcll-known  that  sulphate  of  lead  (PbS04)  is  a  by-product  of 
saii^ta  of  Lead,  yarious  chcmioal  operations,  especially  such  as  are  carried  on  in  connection 
with  dyeing  and'calico-printing.  The  salt  of  lead  thus  obtained  is  a  refuse  which  it  haa 
been  sought  to  utilise  in  many  ways.  As  it  does  not  possess  covering  power,  it  cannot  be 
used  instead  of  white-lead  as  a  pigment,  and  the  difficulty  of  reducing  it  to  metallic  lead 
renders  its  metallurgical  utilisation,  if  not  impossible,  at  least  highly  objectionable.  It 
has  been  used  as  a  gas-purifier  instead  of,  or  in  connection  with,  Ume,  and  for  this  purpose 
it  is  a  very  fit  material,  and  by  becoming  converted  into  sulphuret  of  lead  it  may  be 
afterwards  utilised  as  a  lead  ore.  It  is  converted  into  white-lead  by  digesting  it  with  a 
solution  of  either  carbonate  of  ammonia  or  of  soda.  The  best  method  for  converting  the 
sulphate  of  lead  into  metallic  lead  is  to  mix  the  air-dried  salt  with  67  per  cent  of  chaUc, 
12  to  16  per  cent  of  charcoal,  and  37  per  cent  of  fluor-spar,  and  to  smelt  this  mixture  in  a 
furnace.  The  result  is  the  formation  of  carbonate  of  lead,  which  is  reduced  to  the  metailie 
state  by  carbon,  the  sulphate  of  lead  and  fluor-spar  combiuing  as  a  slag — 

(PbS04 -H  CaCOg -f  2C -».  nFlaCa  =»  Pb-»- 3CO4- CaS04-ffiFlaCa). 
Accordiug  to  Dr.  Bolley,  sulpliate  of  lead  may  be  reduced  by  the  moist  method  by  pladng 
the  salt  with  zinc  into  water,  the  result  being  the  formation  of  chloride  of  zinc  (sic)  and 
metallic  lead.*  M.  Eraflt  proposes  to  convert  sulphate  of  lead  into  acetate  of  lead  by 
boiling  the  former  with  a  solution  of  acetate  of  baryta,  sulphate  of  that  base  (permanent, 
or  Chmese-white)  being  simultaneously  formed. 
Thoorr  of  Pnpuing  Leaving  out  of  the  question  the  preparation  of  white-lead  from  sui- 
White-Lead.  phate  of  lead,  the  preparation  of  the  pigment  as  regards  all  the  other 
methods  is  dependent  upon : — 

1.  The  formation  of  basic  acetate  of  lead ; 

2.  The  decomposition  of  that  compound  iato  neutral  acetate  of  lead  and  white-lead. 
Viewing  white-lead  for  this  purpose  simply  as  a  carbonate  of  lead,  although  we  shall 

*  It  reads  in  the  original  exaotiy  as  above  translated,  but  whence  the  chlorine  for  the 
chloride  of  zinc  is  to  come  has  been  left  in  nubibw;  water,  sulphate  of  lead,  and  metaDio 
zinc  do  not  act  upon  each  other  unless  some  acid  be  present.  Should  dilute  sulphuric  be 
present  there  will  be  formed  sulphate  of  zinc. 


LEAD,  71 

praBentl^  see  that  the  white-lead  of  commeroe  is  not  so  simply  constitated,  the  formation 
may  be  illustrated  by  the  following  f ormnlfe : — 

I.  2J^^^30j  o  +  3PbO  =  [(^*°^j|«]o„2PbHaOa; 

, '  s , 1 

Acetio  aoid.  Basic  aoetate  of  lead. 

n.  (^^^30)1 1 02,2PbHaOa  +  200,  +  2PbC03  +  |  (^^^30|a  |  q^, 

^ , '  >- r-. — >  "^ , • — ' 

Basic  aoetate  of  lead.  Carbonate     Neutral  aoetate 

of  lead.  of  lead. 

It  is  therefore  evident  that  a  comparatiyely  very  small  quantity  of  aoetate  of  lead  can 
produce  a  large  quantity  of  white-lead,  and  the  manufacture  of  that  material  would  be 
endless  but  fo/the  fact  that  white-lead  retains  some  neutral  aoetate  of  lead,  and  that  the 
loss  of  acetic  add  cannot  be  practically  avoided. 

wui«.Laad  from  M.  Tourmentin  prepares  white-lead  from  basic  chloride  of  lead,  obtained 
oiiodfk  of  Lead.  },y  ^hc  action  of  common  salt  upon  litharge,  by  mixing  that  compound 
with  water,  passing  through  it  a  current  of  carbonic  acid,  and  next  boiling  the  fluid  in  a 
leaden-pan  with  powdered  chidk  until  a  test-sample,  when  filtered,  does  not  become 
blackened  by  the  addition  of  sulphide  of  ammonium.  The  white-lead  thus  formed  is  freed 
from  salt  by  washing  with  water. 

*M»8SbStitli£?*  ^*  Pattinson,  of  the  Felling  Chemical  Works,  near  Newcastle-on- 
widfe-LMd.  Tyne,  has  proposed  that,  instead  of  white-lead,  a  basic  chloride  (oxy- 
ehloride)  of  lead  should  be  usea,  and  he  prepares  that  substance  by  adding  to  a  hot  solution 
of  chloride  of  lead  (PbC^),  containing  from  400  to  500  grammes  of  the  salt  to  the  cubic 
foot,  an  equal  bulk  of  saturated  lime-water.  This  addition  causes  the  throwing  down  of 
the  compound  (PbCla+PbH^Oa),  which  after  having  been  collected  on  a  filter  and  washed, 
is  dried  and  used  as  a  pigment.  The  chloride  of  lead  is  obtained  directly  from  galena, 
which  is  decomposed  from  leaden- vessels  with  strong  hydrochloric  acid.  The  sulphxuretted 
hydrogen  thus  formed  is  oarried  by  suitable  tubing  to  a  burner  in  the  sulphuric  aoid 
chamber,  the  resulting  sulphurous  aoid  from  the  combustion  being  used  for  the  produc- 
tion of  sulphuric  add.  Pattinson*s  white-lead  is  not  so  white  as  ordinary  white-lead,  its 
colour  verging  to  yellow,  but  this  is  no  objection  where  white-lead  is  to  be  used  witti  other 
paints,  and  the  less  so  as  Pattinson' s  oxychloride  of  lead  covers  weU. 
PuMrtiM  of  When  unadulterated  and  weU-made,  white-lead  is  an  exquisitely  fine  white- 
in&LMd.  coloured  powder,  void  of  taste  and  smell.  The  white-lead  of  commeroe 
exhibits,  according  to  the  mode  of  preparation,  different  features ;  one  preparation  is  met 
with  in  flakes,  having  been  obtained  by  the  corrosion  of  thin  strips  of  lead  placed  in  pots. 
The  lead  known  as  Krems-lead  is  pure  white-lead  made  in  thin  cakes  by  means  of  gum- 
water. 

The  variety  of  white-lead  known  as  pearl-white  is  blued  with  either  a  small  quantity  of 
indigo  or  Berlin-blue.  The  white-lead  of  commeroe  has  frequently  been  made  the  object 
of  chemical  analysis,  especially  by  1^.  G.  J.  Mulder  and  M.  Oriineberg.  The  results  of 
the  analyses  of  the  under-mentioned  samples  prove  the  correctness  of  the  formula  given 
above.  The  numbers  refer  to : — i.  Exems  white-lead.  2.  Prddpitated  by  the  CLiohy 
method  and  manufactured  at  Magdeburg.  3.  From  the  Harz.  4.  Another  sample  from 
Krems.  5.  A  sample  from  a  chemical  laboratory  by  imitating  the  Dutch  method  on  a 
limited  scale.  6,  7.  Samples  from  Klagenfurt,  Carynthia.  8.  English  lead  manufactured 
according  to  the  Dutch  method. 

Oride  of  lead 
Carbonic  acid    . . 
Water 


I. 

2. 

3- 

4- 

5* 

6. 

7- 

8. 

8377 

8593 

86*40 

86*25 

84-42 

86*72 

86*5 

86-5X 

15*06 

11*89 

11*53 

"•37 

14-45 

11*28 

11*3 

11*26 

I"OI 

2'OI 

2*13 

2*21 

1-36 

2*00 

2*2 

2*23 

It  is  certain  that  the  covering  properties  of  white-lead  are  dependent  upon  its  state  of 
aggregation,  because  a  loose  crystalline  white-lead  does  not  cover  nearly  as  well  as  the 
perfectly  amorphous  lead  prepared  by  the  old  Dutch  method.  It  appears  that  the  covering 
power  increases  with  the  amount  of  hydrated  oxide  of  lead.  This  is  proved  by  the  fact  that 
those  who  merely  choose  white-lead  by  its  coveringpower  are  often  misled,  a  fact  lately  tested 
by  the  translator  of  this  work,  by  giving  to  a  man,  thoroughly  acquainted  with  white-lead 
as  eommerdally  met  with,  a  mixture  of  carefully-prepared  and  dried  hydrated  oxide  of 
lead,  to  which  white  predpitate,  subnitrate  of  bismuth,  and  carbonate  of  bismuth  had 
been  added.  The  man,  after  testing  a  series  of  samples  of  purposely-adulterated  white- 
lead,  all  of  which  he  detected  as  adulterated,  was  unable  to  speak  with  certainty  of  the 
above  mixture,  which  he  took  for  pure  lead. 


72  CHEMICAL  TECHNOLOGY. 

AdnitfltaiioB  of  It  has  been,  and  is  still,  to  some  extent,  the  custom  in  the  mAnnfaetories 
whtte-LMd.  ^  fAdi  to  white-lead  a  certain  quantity  of  snlphate  of  baryta,  either  natiT<e 
or  artificially  prepared.  Lead  is  often  mixed  with  sulphate  of  lead,  chalk,  carbonate  of 
baryta,  snlphate  of  baryta,  and  pipe-day ;  but  these  adulterations  are  most  common  in 
the  retail  trade.  Not  any  of  these  substances  ought  to  be  present ;  they  possess  no 
cbyering  power  and  needlessly  absorb  oil.  Pure  white-lead  ought  to  be  perfectly  soluble 
in  yery  dilute  nitric  add,  and  in  the  resulting  dear  solution  caustic  potassa  should  not 
produce  a  precipitate,  for  if  it  does  chalk  is  present.  An  insoluble  reddue  in  the  dilute 
nitric  acid  indicates  the  presence  of  gypsum,  heavy-spar,  or  sulphate  of  lead.  The 
sulphate  of  lead  may  be  recognised  by  reducing  the  lead  with  the  blowpipe.  Sulphate 
of  baiyta  can  be  made  evident  by  ignition  with  charcoal  in  the  blowpipe  flame,  treating 
the  reddue  with  dilute  hydrochloric  add,  and  adding  a  solution  of  gypsum,  which  again 
yidds  a  predpitate  of  sulphate  of  baryta.  Gypsum  does  not  yield  an  ins<^uble  predpitate 
with  dilute  nitric  add,  but  does  so  with  a  solution  of  oxalate  of  ammonia.  According  to 
Dr.  Stein  the  most  simple  method  of  estimating  quantitatively  a  mixture  of  white-lead 
and  sulphate  of  baryta,  is  to  heat  the  weighed  sample  in  a  piece  of  combustion-tube,  and 
to  collect  the  carbonic  add  in  a  Liebig's  potassa-bulb,  a  chloride  of  calcium-tube  being 
fastened  by  a  perforated  cork  to  the  combustion-tube  to  absorb  the  moisture.  The 
quantity  of  carbonic  add  given  off  stands  in  direct  proportion  to  the  quantity  of  carbonate 
of  lead  present.  Pure  white-lead  of  good  quality  gives  off  about  14*5  per  cent  of  the 
gas,  and,  according  to  Dr.  Stein's  researches,  the  undermentioned  series  of  mixtures  gave 
off  the  quantities  of  carbonic  acid  indicated. 

33*3  parts  of  white-lead  and  66-6  parts  of  heavy-spar  lost  by  ignition  4*5 — ^5  per  cent. 
66-6  „  „  33*3  .»  ♦»  »»       6-5—7        t» 

8o-o  „  „  200  „  „  „     13-0  „ 

500  „  „  500  „  „  „     10—10-4      „ 

AmiiMttoosot  The  extensive  applications  of  this  material  as  a  constituent  of  psints, 
whito-LMd.  i<  to  give  body,"  as  the  term  runs,  and  as  putty,  and  for  various  chemical 
operations,  are  well  known.  It  has  been  experimentally  proved  by  Dr.  G.  J.  Mulder  in  bis 
treatise  *'  On  the  Ohemistry  of  Drying  Oils  and  the  tactical  Applications  to  be  drawn 
therefrom,"  that  tiie  quantity  of  white-lead  used  in  proportion  to  linseed-oil  for  painting 
purposes  is  far  too  great,  being  on  an  average  from  250—280  parts  of  white-lead  to  100 
parte  of  oil,  while  the  author  found  that  52  parts  of  unadulterated  white-lead,  or  44  parts 
of  oxide  of  lead  (PbO)  to  100  parts  of  raw  or  boiled  linseed-oil  are  amply  suffident 
quantities.  White-lead,  however  useful,  is  very  sendtive  to  the  action  of  sulphuretted 
hydrogen,  by  which  it  is  blackened  and  discoloured,  causing  not  only  all  the  white  paint 
to  be  spoiled,  but  also  all  pigments  and  paints  of  which  white-lead  is  a  constituent,  as 
may  be  seen  to  a  very  large  extent  every  summer  at  Amsterdam,  where  from  the  stagnant 
canals  sulphuretted  hydrogen  is  abundantiy  given  off.  The  action,  however,  of  the  sea 
air  in  autunm  has  the  effect  of  somewhat  restoring  the  blackened  and  discolotured  painted 
surfooes  to  their  primitive  hue.  The  late  Professor  Th^iard  suggested  that  pictures  which 
had  become  blackened  should  be  cleaned  by  means  of  peroxide  of  hydrogen,  the  oxygen 
of  which  present  as  ozone  converts  the  blackened  lead  colours  into  white  BulphAte 
of  lead. 

In  this  country  it  has  become  an  almost  universal  custom  to  sell  white-lead  ready 
ground  with  linseed-oil  into  a  thick  paste.  This  practice  certainly  saves  painters  a 
great  deal  of  trouble,  but  is  also  pregnant  with  the  difficulty  of  detecting  adul- 
teration, while  there  is  a  chance  of  an  inferior  oil,  rosin  oil,  being  added.  The 
oU  almost  entirely  prevents  the  action  of  any  acid  upon  the  paste;  even  if  very  strong 
nitric  add  be  taken,  and  heat  applied,  the  decomposition  and  disintegratiosi  are 
very  slow  and  incomplete,  and,  besides,  owing  to  the  insolubility  of  nitrate  of  lead 
in  nitric  acid,  the  action  of  strong  nitric  acid  upon  oil  thus  mixed  gives  rise  to  a 
variety  of  compounds,  which  interfere  with  the  usual  modes  of  testing  the  white* 
lead.  To  remove  the  oil  in  order  to  test  white-lead,  the  best  plan  is  to  thoroii^^ 
incorporate  some  of  the  sample  witii  a  mixture  of  chloroform  and  strong  alcohol  in 
equal  parts,  and  to  wash  the  mass  by  decantation  or  on  a  filter  with  a  fluid  composed 
of  2  parts  of  chloroform  and  i  of  strong  alcohol.  The  quantity  of  the  oil  may 
then  be  ascertained  by  the  evaporation  of  this  solvent.  After  washing  once  or  twice 
with  boiling  alcohol  and  then  dxying,  the  white-lead  can  be  readily  tested  by  any  of 
the  known  methods. 


Tin. 

(Sn=ii8;  Sp.  gr.=7-28.) 
Tin  does  not  occur  nstnrolly  in  a  metallic  slAte;  it  is  found  as 
""uSmSZT^  oxide  in  tinstone,  or  tin  ore,  SnO,,  containing  79  per  cent  of  metal, 
and  as  sulphnret  of  tin  in  combination  with  other  metallic  snlpboiets  in  tin  pjrit«B, 
[iCi>iS+SoSi)+2(FeS,ZnS),SnS„  with  26  to  29  per  cent  of  tin.  Tin  ore  occurs 
either  interspersed  in  veins,  in  ajenitic  and  similar  rooks,  or  in  secondary  formations 
depo6it«d  from  water,  and  oonaisting  of  Tariona  detritus,  when  it  is  known  as  tei/fr. 
■  These  ores  are  not  as  a  rule  simpl}'  composed  of  pnre  oxide  of  tin,  but  contain  various 
other  metallic  oomponuds,  among  which  are  snlphnr,  arsenic,  zinc,  iron,  and  copper. 
In  some  instances,  in  Cornwall,  Malacca,  Banca,  and  Klliton,  tin  ore  is  met  with 
among  the  detritoa  of  ancient  river-beds  in  a  very  pnre  state,  since  the  mechsnical 
separation  of  the  ore  from  impurities  has  been  performed  bj  nature  itself,  and  as  a 
consequence  these  ores  yield  a  purer  metal  than  the  ore  obtained  from  veins,  which 
has  to  nndergo  dressing,  washing  with  water,  and  roasting,  previouslj  to  being 
■melted,  in  order  to  eliminate  the  arsenic,  Bolphni,  and  antimony.  Tinstone  ocours 
in  Saxony  in  the  earlier  granitic  formation.  The  ore  is  aooompanied  by,  and  partly 
mixed  with,  wolfram,  molybdeunm-glance,  sulphur,  and  arsenical  pyrites,  and  bears 
the  name  of  Ziimzwitter.  Fig.  33,  I.  and  II.,  represent  the  furnace  in  use  at 
Altenberg,  Saxony,  for  smelting  the  roasted  tin  ore.  It  is  built  of  granite  upon  a 
Fio.  3a. 


strong  foundation  of  gneiss,  and  is  about  three  metres  in  height.  *  is  the  shaft,  b  the 
fbre-hearth,  and  d  the  bottom-stone,  consisting  of  one  single  piece  of  granite  scooped 
ODt  in  tbe  direction  of  s,  B  is  in  communication  with  the  iron  caldron,  c :  while  the 
toyere  of  the  blast  is  placed  at  b.  The  ore.  mixed  with  coke,  coal,  or  charcoal,  and 
with  slag  from  former  smeltings,  is  placed  in  t :  the  reduced  tin  collects  first  on  the 
Ibre-heartb,  b,  and  runs  thence  into  c.  The  metal,  however,  is  not  pnre,  but  contains 
iion  and  arsenic.  It  is  separated  from  these  iropnrities  by  a  process  of  Uqnation ; 
8ie  pore  tin  frising  more  readily,  oozes  out  and  leaves  behiud  an  alloy  of  iron  and 
tin  fusible  with  greater  difficulty.  The  metal  thus  oblained  is  very  pure,  containing 
hardly  as  mnch  as  O'  i  per  cent  of  foreign  metals ;  it  is  known  in  tbe  trade  as  refined 


74 


CHEMICAL  TECHNOLOGY. 


tin.  The  slags,  as  well  as  the  alloy  remaining,  are  smelted  separately  or  together 
for  tin,  and  the  result  brought  into  the  market  as  block-tin.  In  Bohemia  and  Saxony, 
tin  is  cast  either  in  ingots  or  in  cakes.  Banca  and  BiUiton  tin,  a  very  pure  metal, 
is  cast  in  slabs.  If  tungsten  ores  occur  with  tin  ores,  there  is  great  difficulty  in 
obtaining  pure  metal.  Tin  ore  found  in  Cornwall — and  this  county  has  3rielded  tin 
for  at  least  2000  years— has  to  be  smelted  £kccording  to  the  ancient  Stannary  laws. 

t>ropertieB  of  Tin.  Tiu,  as  regards  it8  oolonr,  approftohes  the  nearest  to  silver,  caaiy 
differing  by  a  somewhat  bluish  hue,  and  it  exhibits  a  high  metallic  lustre  Teiy 
Bimilar  to  silyer.  It  is  next  to  lead  the  softest  metal,  yet  is  somewhat  sonoroos,  for  if  a 
rod  oi  tin  be  tree  to  swing,  and  is  gently  tapped,  a  sound  is  produced ;  this  ia  not  the 
-ease  under  similar  conditions  with  lead,  thus  proving  tin  to  be  considerably  harder,  alio 
proved  by  the  fact  that  it  is  not  easily  scratched  with  the  naU.  The  bending  of  a  rod  of ' 
tin  causes  a  creaking  noise,  which  13  the  stronger  the  purer  the  tin.  Tin  is  very  malleable, 
and  admits  of  being  beaten  to  very  thin  foil,  but  it  is  not  a  very  ductile  metaL  'Wben 
rubbed  between  the  fingers  it  imparts  to  them  a  peculiar  odour.  The  sp.  gr.  of  pure  tin 
is  7*28,  and  by  hammering  may  be  increased  to  7*29 ;  a  cubic  foot  of  tin  weighs,  according 
to  its  purity,  from  375  to  400  lbs.  Tin  fuses  at  228*^,  and  becomes  very  brittle  irhen 
heated  to  nearly  that  temperature.  If  the  metal  is  intended  for  casting — ^it  is,  however, 
very  rarely  used  in  a  perfectly  pure  state  for  castings,  as  it  does  not  fill  the  moulds  well- 
its  metallic  lustre  and  degree  of  cohesion  after  cooling  entirely  depend  upon  the  tempera- 
ture of  the  tin  at  the  time  of  casting.  If  too  hot  and  exhibiting  rainbow  colours,  its  sur- 
face will  appear  striped  and  reddish-yeUow  after  cooling,  and  the  metal  will  be  brilUe 
if  again  heated  to  loo**  to  140** ;  if  not  sufficiently  heated,  though  in  a  fluid  state,  it  is,  after 
cooling,  dull  and  brittle.  The  greatest  metallic  lustre  is  obtained,  and  simultaneousiy  the 
greatest  cohesive  strength,  when  the  surface  of  the  metal  while  molten  exhibits  a  high  degree 
of  lustre.  At  a  white  heat  tin  boils  and  volatilises,  air  of  course  being  excluded ;  for 
if  ihe  metal  be  kept  fused  in  contact  with  air,  it  becomes  covered  with  a  greyish  coating 
of  protoxide  of  tin  and  finely  divided  metal,  termed  tin-ash,  which  substance  when  the 
heating  is  continued  becomes  converted  into  a  yellowish-white  stannic  oxide,  kaowa 
as  putty  powder.  Tin  by  exposure  to  air  gradually  loses  its  metaUic  lustre,  but  is  by  no 
means  so  readily  iCffeeted  by  sulphuretted  hydrogen  and  ammoniacal  vapours  as  silver, 
and  is  used  to  imitate  that  metal  in  the  construction  of  lustres  for  gas  lamps,  <&e. 

AppUoatioiu  of  Tin.  Now  that  chiua  and  earthenware  have  become  cheap,  and  oUier  alloys 
are  used  for  spoons,  tin  is  not  so  frequentiy  in  demand  as  in  former  times  for  domestic 
utensils.  Tin,  though  next  to  silver  the  dearest  of  metals,  is  met  with  in  quantities 
measured  by  tiie  ton,  which  of  tin  varies  in  price  from  £120  to  £180— copper  being 
from  £95  to  £105 — and  is  largely  used  both  as  an  alloy  (for  those  wi&  copper 
see  under  that  metal),  and  in  a  pure  state  for  various  kinds  of  vessels  for  pharmaeeutieal 
and  chemical  operations,  for  worms  of  distUling  apparatus,  for  the  working  parts 
for  dry  and  wet  gas-meters,  and  for  block-tin  pipes  for  conveying  gas  and  water,  te 
However,  for  many  purposes,  an  alloy  known  in  this  country  as  pewter,  of  Ic^  and  tin  in 
varying  proportions,  is  preferred,  because  this  compound  is  harder  and  stands  wear  and 
tear  bettor  than  these  metals  separately.  An  alloy  of  lead  and  tin  is  called  abitnd 
two-poundly  when  the  metals  are  present  in  equal  quantities,  and  ihree-^^oundiy  when 
consisting  of  2  pounds  of  tin  and  i  of  lead.  Tin,  either  pure  or  more  or  less  alloyed  with 
lead,  may  be  beaten  or  rolled  into  thin  sheets  and  foil,  and  applied  in  a  great  many  ways ; 
among  which,  one  of  the  chief,  although  gradually  being  superseded  by  a  process  of  aUvering, 
is  tinning  or  amalgamating  mirrors.  Tin-foil  is  also  used  for  the  packing  of  chocolate, 
soap,  cheese,  fruit,  &c.,  all  of  which  keep  very  well  under  these  conditions.  CSommercial 
silver-foil  or  leaf-silver  is  an  alloy  of  tin  with  a  little  zinc ;  in  combination  with  other 
metals,  viz.  copper,  antimony,  and  bismuth,  in  varying  but  small  quantities,  it  constitutes 
a  oompoation  metal  used  for  making  teaspoons  and  other  similar  objects.  Britannia  metal 
consists  of  10  parts  of  tin  and  i  of  antimony,  its  various  applications  are  well  known. 

As  the  specific  gravity  of  those  metals  with  which  tin  is  purposely  or  naturally  alloyed 
differs,  the  determination  of  the  sp.  gr.  is  a  means  of  estimating  the  purity  of  the  meitaL 
The  undermentioned  figures  illustrate  this  in  the  more  commonly  occurring  alloys  of  tin 
and  lead. 

Parts  Sn  -f  Parts  Pb       Sp.  gr. 


Parts  Sn  +  Parts  Pb 

Sp.gr. 

1  + 

2  + 

1  + 

2  + 
X         + 
2        + 

I 
3 

2 

5 

3 
7 

8*8640 
9*2650 

9*5530 
97700 

9-9387 
10*0734 

I 

+ 

4 

10*183 

3 

+ 

2 

8-497 

2 

•f 

I 

8*226 

5 

+ 

2 

8*109 

3 

+ 

I 

7*994 

PREPARATIONS  OF  TIN.  75 

The  materiftl  known  as  putty-powder  and  calcined  tin-ash  is  used  for  polishing  glass 
and  metals,  and  for  producing  white  enamels. 

Tianiaf.  By  this  term  we  understand  the  covering  of  other  metallic  surfaces  with  a  thin 
and  adhesive  film  of  tin.  This  operation  only  succeeds  well  when  the  surface  of  the  metal 
to  be  tinned  is  quite  free  from  oxide,  and  when  during  the  operation  the  oxidation  of  the 
molten  tin  is  preyented.  The  former  requisite  is  attained  by  the  action  of  dilute  acids » 
rubbing  and  scouring  with  sand,  pumice-stone,  Ac. ;  the  latter  condition  by  the  use  oi 
either  rosin  or  sal-ammoniac,  both  of  which  cause  the  reduction  of  any  oxide  that  may  be 
formed. 

of  coDoer.  btsu,      '^^^  vessels  or  other  objects  intended  to  be  tinned  are  heated 


■AdHaUMiUe  Iron,  nearly  to  the  melting-point  of  tin ;  some  molten  tin  is  then  poured 
iato  the  yessel  and  brushed  about  with  a  piece  of  hemp  over  which  some  powdered  sal- 
■mmoniae  is  strewed.  Pins,  hooks  and  eyes,  small  buttons,  and  similar  objects  are  tinned 
by  being  boiled  in  a  tinned  boiler  filled  with  water,  granulated  tin,  and  some  cream  of 
tartar.    The  tinned  objects  vre  dried  by  being  rubbed  with  sawdust  or  bran. 

TiBsaisiiMi-iroii.  TMs  wcll-known  material,  from  which  so  many  useful  objeeta  are  mad* 
by  the  tinman^  is  not,  as  is  frequently  supposed,  rolled  out  sheet- tin,  but  tinned  sheet-iron. 
The  iron  proYiously  to  being  covered  with  tin  is  thoroughly  scoured,  so  as  to  present  a 
dean  metallic  surface,  and  then  immersed  in  baths  of  molten  tin  covered  with  a  layer  of 
molten  tallow  to  prevent  the  oxidation  of  the  metal.  On  being  removed  from  the  tin-bath 
the  sheets  are  immersed  in  a  bath  of  molten  tallow  to  remove  any  excess  of  tin,  wiped 
with  a  brush  made  of  hemp,  next  cleaned  with  bran,  and  packed.  In  order  to  obtiun  iron 
covered  with  an  iJloy  less  easily  fusible,  MM.  Budy  and  Lammatseh  add  about  ,^^1^  ^ 
niekel  to  the  tin. 

M«ii»]i«ui]i4iM.  When  tinned  sheet-iron,  technically  termed  tin-plate,  is  washed  over 
with  a  mixture  consisting  of  3  parts  of  hydrochloric  and  i  part  of  nitric  acid  diluted  with 
3  parts  of  water,  and  then  cleaned  with  pure  water,  there  will  be  observed  a  peculiar* 
somewhat  mother-of-pearl -like  appearance,  due  to  the  crystalline  particles  of  tin,  produced 
by  the  rapid  cooling,  reflecting  the  light  unequally* 

Preparations  of  Tin. 

^'jSS^^S^*  ^®  substance  known  under  that  name  is  in  reality  a  faisniphide  of 
tin  (SuSg),  prepared  in  the  following  manner : — 4  parts  of  pure  tin,  with  2  of  mercuiy, 
are  amalgamated  by  the  aid  of  a  gentle  heat,  and  introduced  with  zk  parts  of  sulphur 
and  2  of  sal-ammoniac  into  a  flask,  and  heated  on  a  sand-bath,  at  first  gently  and 
then  gradnallj  increasing  to  a  full  red  heat.  First  the  sal-ammoniac  volatilises,  and 
next  mereory  in  the  shape  of  cinnabar  mixed  with  a  trace  of  the  sulphide  of  tin ;  while 
there  is  left  the  preparation  known  as  mosaic-gold,  forming  the  upper  layer  of  the 
temaining  contents  of  the  flask,  the  lower  portion  being  a  badly-coloured  sulphide. 
The  ratUmale  of  the  formation  of  this  peculiar  coloured  sulphide,  that  is,  peculiar  as 
regards  its  physical  appearance,  is  not  quite  clearly  explained ;  the  compound,  more- 
over, may  be  prepared  without  mercury.  When  properly  prepared,  it  appears  as  a 
golden-coloured  metallic  substance,  greasy  to  the  touch,  and  soluble  in  the  alkaline 
anlphnrets.  It  is  chiefly  used  for  imitating  gilding  on  painted  surfaces,  but  its 
employment  is  very  much  restricted  from  the  fact  that  the  bronze-colours  are  more 
satisfinctory  in  result,    Indeed,  in  the  English  market,  mosaic-gold  is  almost  obsolete. 

TiMdt  By  the  name  of  tinsalt  the  trade  understands  chloride  of  tin  (Sn01«),  but 
the  commercial  article,  being  prepared  by  dissolving  granulated  tin  in  hydrochloric 
acid  and  evaporating  the  solution,  is  really  (SnCl^-faH^O).  According  to  M.  Nollner 
kydrochloric  acid  gas  should  be  caused  to  act  on  granulated  tin  placed  in  earthenware 
nceivers,  and  the  concentrated  tinsalt  solution  thus  obtained  evaporated  in  block-tin 
veasels.  The  salt  occurs  in  the  trade  in  colourless,  transparent,  deliquescent 
crystals,  of  course  very  soluble  in  water.  The  aqueous  solution,  unless  acidulated 
with  more  hydrochloric  or  tartaric  acid,  soon  deposits  a  basic  salt.  Tinsalt  is  used 
chiefly  in  dyeing  and  calico-printing. 


76  CHEMICAL  TECHNOLOGY. 

"^n^!^  Under  this  name  dyew  use  a  solution  of  refined  block-tiii  in  aqtu 
regia,  and  uauslly  this  substance  ia  a  mixture  of  perchloride  and  protochloride  of  tin. 
The  material  known  as  pinksalt  is  a  double  chloride  of  tin  and  Bnuoonioin — 

(SnCl^+aNH^ai. 
A  couoentrated  aqueous  solution  of  this  salt  is  not  decomposed  hy  being  boiled,  bat, 
when  diluted,  the  oxide  of  tin  is  thrown  down.    Pure  chloride  of  tin  is  used  in  Fimnoe 
in  the  preparation  of  fachsine ;   while  as  a  solutioii  it  is  used  bj  M.  Th.  Petw.  at 
Ohenmitz,  for  dyeing  in  iodine-graeu. 

nuiuUDiBodi.  This  salt  is  now  very  lai^elj  used  in  dyeing  as  well  as  in  calioo- 
printing,  and  is  prepared  in  various  ways,  sometimes  by  fusing  tin-ores  with  caoHtic- 
Boda  and  lixiviating  the  molt«n  mass  with  water ;  oi,  according  to  Mr.  Brown,  by 
boiling  soda-lje  with  metallic  tin  and  litharge,  the  effect  being  the  formation  of 
atannate  of  soda  and  metallic  lead.  Dr.  Hafiely  somewhat  modifies  this  prooeas  br 
digesting  litharge  with  soda-lye  at  2Z  per  cent  in  a  metallic  vessel.  Into  the  aolatwo 
of  plumbateof  aoda  thus  obtuned,  granulated  tin  is  placed  and  heat  applied.  Some- 
times a  stonnite  of  soda  is  used  and  made  by  dissolving  tinsalt  in  an  excess  of  caustic 
soda,  but  this  preparation  is  unstable  and  does  not  answer  well  in  dyeing  and  printing  ; 
it  is  only  extemporaneously  used  on  a  limited  scale  by  small  dyers. 

BiSUUTH. 

(Bi=2io;  Sp.gr.=9'79). 
°*°S'n!Slft?AJ'°*'      Bismuth  is  a  rather  rare  metal.    It  occurs  io  Pern  and  Anstrslia, 
chiefly  native,  and    with  cobalt  and  silver  ores  in  granite -gneiss  and  metamoiphie 
roclcB.     It  is  also  found  as  oxide,  the  ore  being  known  as  bismuth -ochre,  BiOj,  ctm- 
taiaing  89-g  per  cent  metal :  as  snlphide.  or  bismuthine,  BiS,,  with  SogS  per  oent 

Fio.  33. 


metal :  and  as  bismuth  copper  ore,  with  4724  bismuth.  Ah  bismuth  is  chiefly  found 
in  the  native  metallic  stata.  and  is  a  readily  fusible  metal,  its  extraction  from  gangne 
is  not  a  difficult  matter,  and  consists  in  a  process  of  liquation. 

""iSiiiS*'^'  "^^  contrivance  in  use  near  Schneeberg.  in  Saxony,  for  the  smelt- 
ing of  bismuth  is  exhibited  in  Fig.  33.  The  ore.  containing  on  an  average  from 
4  tD  12  per  cent  metal,  separated  as  much  as  poHsible  by  mechanical  means  from  the 
gangue,  is  broken  up  to  the  size  of  hazel-nuts  and  placed  in  the  cast-iron  tube.  a. 


ZINC,  77 

Jbeatod  by  means  of  the  fiimace.  The  fluid  metal  nms  out  into  b,  an  iron-pot  kept 
gniBciently  hot  by  meana  of  charcoal  to  prevent  the  solidification  of  the  metal,  and 
partly  filled  with  charcoal-powder  to  prevent  the  oxidation  of  the  metal.  The  residue 
in  the  iron  tube  is  discharged  into  the  water  which  fills  the  box,  n.  By  this  method 
of  liquation  abont  two-thirds  of  the  bismuth  contained  in  the  ore  is  reduced.  Bismuth, 
as  has  been  stated  (see  Cobalt),  Ib  obtained  as  a  by-product,,  and  from  the  refuse  of  the 
refining  of  certain  sUver  ores  which  are  treated  with  dilute  hydrochloric  acid,  the  basic 
ehloride  of  bismuth  being  precipitated  by  water,  afterwards  dried,  and  reduced  by 
means  of  soda. 

>iwi«um  of  Btamaih.  Bismuth  poBBSSses  a  reddish-white  oolour,  strong  metallic  lustre,, 
and  ciystalline  texture.  It  is  hard,  but  so  brittle  that  it  is  readily  pulTerised,  yet 
with  careful  treatment  proves  to  be  somewhat  ductile.  Its  fusion-point  is  variously 
given  by  different  authors,  the  latest  determination  of  pure  metal  in  an  atmosphere  of 
hydrogen  is  by  Dr.  van  Riemsd^k,  who  found  bismuth  to  melt  at  268*3°.  On  cooling 
bismuth  expands  very  considerably. 

a  is  Saxony,  /3  Peruvian  bismuth ;  composed  in  100  parts : — a.  Bismulh,  96-731 ;  anti- 
many,  0-625;  arsenic,  0*432;  copper,  i'682;  sulphur,  0-530.  /3.  Bismuth,  93*372; 
sntimony,  4-570 ;  copper,  2*058. 

Miatfmfloc  Bismuth  in  the  metallic  state  is  chiefly  used  for  certain  alloys.  Its  oxide 
^^"^  enters  with  bono  and  silicic  adds  into  the  composition  of  some  kinds  of 
|^|sss,  and  is  used  for  porcelain-  and  glass-staining.  The  basic  nitrate,  or  magUterium 
bitmnuki,  and  the  o/irbonate  are  used  in  medicine,  and  the  former,  under  the  name  of 
Bkme  defdrd,  is  employed  by  ladies  for  painting  and  beautifying  their  faces.  Among  the 
alloys  of  bismuth  those  with  lead,  tin,  and  eadTninm  (see  that  metal),  are  the  most  impor- 
tant. Newton's  fusible  alloy  is  composed  of  bismuth,  8  parts ;  tin,  3 ;  lead,  5 ;  and  melts 
at  94*5*.  Bose'B  fosible  metal  consists  of  2-  parts  of  bismuth,  i  of  lead,  i  of  tin,  and 
fuses  at  93-75.  If  a  small  quantity  of  cadmium  be  added  to  these  alloys  they  are 
randsred  still  more  easily  fusible.  An  alloy  composed  of  lead  3  parts,  tin  2  parts,  bis- 
rnath  5  parts,  fuses  at  91-66,  and  may  be  used  for  stereotyping  purposes,  but  is  rather 
tzpenaiTe.  This  alloy  is  also  used  for  making  ihe  pocket-book  metaUic-penoil  for  writing 
on  paper  prepared  with  bone-ash.  Alloys  containing  bismuth  were  used  as  safety-plugs 
in  iteam-boilen ;  these  plugs  were  screwed  into  one  or  more  of  the  plates  exposed  to  the 
foree  of  the  steam,  usually  in  or  near  the  steam-chest  or  dome,  the  idea  being  that  the 
phgs  would  melt  if  the  temperatore  of  the  steam  rose  b^ond  certain  limits.  Experience, 
howsver,  has  sufficiently  proved  that  these  pings,  although  carefully  made,  did  not  act  as 
a  real  preventative  to  boiler-eiplosions. 

ZiNO. 

(Zn«65*2 ;  Sp.  gr.=7-i  to  7*3) 

oocmnMocziM.  Tlus  metal,  known  only  a  comparatively  short  time,  is  never  found 
native,  but  in  combination  with  sulphur  (ZnS),  with  67  per  cent  of  metal,  under  the 
name  of  Uende  or  black-jack,  the  ore  sometimes  containing  traces  of  indium.  It  also 
oecnrs  combined  with  oxygen  as  noble-calamine,  carbonate  of  zinc,  or  zinc-spar 
(ZnCO}),  with  52  per  cent  of  zinc ;  as  ordinaiy  calamine-stone,  or  hydrated  silidate  of 
zinc,  with  53*8  par  cent  of  metal;  as  red  zinc-ore  or  red  oxide  of  zinc,  frequently 
containing  manganese ;  as  Gfahnite  (AlZn04) ;  and  farther  as  an  admixture  with  other 
orea. 

ii£aSf  &M.  -^^  general  plan  is  to  roast  the  ore  and  then  mix  it  with  the  requi- 
nte  quantity  of  carbonaceous  matter  and  suitable  flux,  care  being  taken  that  the  latter 
>lutU  not  give  rise  to  the  formation  of  any  oxidising  material ;  for  instance,  if  the  ore 
nqnires  lime  as  flux  to  take  up  the  gangue,  calcined  limestone,  and  not  chalk  or 
limeatone  is  used.  The  action  of  the  fuel  is  aided  by  a  blast,  best  of  dry  air.  The 
products  of  this  mode  of  treatment  are: — i.  Metallic  zinc,  the  vapours  of  which 


jS  CHEMICAL  TECHNOLOaT. 

eondeOM  in  propetly  constructed  and  cool  channflls.  2.  Hot  gasea  usoBUf  applied  for 
beatmg  Bteam-boilarB  or  other  pnrpoBee.  3.  The  non-volatile  materials,  gangne  and 
flax,  elag  with  some  metoL 

iHitDL^m^ziu  With  the  exception  of  cadmium,  zinc  is  the  moat  volatile  of  £he 
«adily  fusible  metala,  while  its  melting-point  is  nearly  twice  (he  number  of  d^[rees  of 
that  of  tin,  the  meet  ftuifale  of  Qie  commercioll?  valuable  metals ;  this  property  is 
utilised  in  extracting  the  metal  from  its  or«s.  The  mode  of  distillation  vaiies  in 
SDSie  ptutkculort  in  the  three  chief  zinc  prodncing  countries,  SUesi^  Belgium.  «nd 
England.  In  Silesia  and  Oennan])  the  apparatus  nsed  for  the  distillation  of  zine 
connsta  (see  Figs.  33,  34,  and  35)  of  a  moffie-Hhaped  fire-clay  retort,  the  front  or 
isoath  of  vMch  is  provided  with  two  openings,  the  lower,  a.  being  closed  by  a  dow 


Fto.  34. 


Fto.  35. 


irluch  is  opened  only  when  the  residue  of  the  distillation  is  taken  ont.  At  b,  tbe 
other  opening,  a  rectangolarly  bent  tabe  is  inserted,  provided  with  a  small  bole  >t  «. 
closed  by  a  plug  when  the  operation  of  diafUling  i^  proceeding,  and  by  ^diich  the  ore 
is  introduced  into  the  retort.  At  d  Ute  molten  zinc  rons  off.  The  muffles  are  placed 
to  the  number  of  from  10  to  30  in  a  fnnuice  (see  Fig.  36)  constructed  inlemnUy 

Fio.  35. 


somewhat  like  gaa-retort  furnaces,  and  rest  on  what  are  technically  termed  benches. 
The  krohes  of  the  ftamaces  are  so  constructed  as  to  concentrate  the  heat  (rem  th» 
hearths  placed  longitudinally.  The  metal  is  recaved  in  crucibles  plaoed  in  the 
recesses,  a.  As  the  first  portion  of  the  metal  and  oxide  carried  over  contains  nearly 
aU  the  eadmium  existing  in  the  ore,  that  portion  is  kept  separate  for  the  ptupoae  at 
wxtracting  cadmium.  At  the  outset  of  the  distillation  the  condensation  room,  t,  is  so 
cool  that  the  vapours  of  the  zinc  become  solid  without  agglntinstioa,  that  is,  ranaiD 
finely  divided.  This  product,  though  of  course  containing  oxide,  frequenUy  yields 
g8  per  cent  of  metallic  zinc.  Afterwords  the  metal  carried  over  is  what  is  termed 
drop-zinc,  that  is  to  say,  the  liquid  runs  off  in  a  molten  state.  This  crude  zine  is 
refined  by  another  smelting,  and  comes  in  the  market  in  slabs  about  2  inches  thick 
by  10  long  and  5  to  6  wide. 


ZINC.  79 

DMtDatisa  b  TibM  At  the  cdebuted  zmc-worke  of  VieOIe  Uontagne,  near  Ltige, 
Belgium,  zino  ore  is  distilled  in  tnbea.  These  tol^es  are  placed  in  rows  in  a  shnting 
peeitiDni  the;  aiemadeoffire-daj,  i metre inlengthbjiScentims.widUiEuidscentiais. 
fliidDMS  (see  fig.  37) ,  and  dosed  at  one  end ;  Uie  open  ends  are  flosh  with  the  &ont 
biiok-w«rk  of  the  ftunace,  in  order  that  the  charge  of  ore,  Box,  aud  oaibcmB«eons  matter 
maj-  be  introduced.  Fig.  38  exhibits  a  csst-iron  conically-shapad  tabe,  25  centuns. 
long,  and  Fig.  39  a  sheet-iron  tube  zo  oentiins.  long,  both  of  which  are  6tst«cied  to  tli« 


F».  37. 


Fio.  38. 


Fio.  4a 


fire-elay  tnbe  to  reoeive  the  volatilised  metal.  A  vertical  section  of  the  Belgian 
fiuiuee  nsed  for  the  distiUation  of  zino  is  Hhown  in  Fig.  40,  with  the  mode  of  placing 
Ihe  tubes,  the  closed  ends  of  which  rest  on  aproJeGtion  of  the  brick-work.  The  ore  is 
£nt  calcined  in  a  shaft-fumace,  and  the  charging  of  the  tubes  usuallj  takes  plaoe 
aretj  morning  at  mx  o'clock,  when  the  fire  ia  rather  low. 
'*rS3.£^''"  The  zinc-sraelting  as  carried 
en  near  Sheffield,  Birmingham,  and  in  Wales  and 
other  localitiea,  is  performed  b;  downward  dis- 
tilktioB.  The  furnaces  represented  in  Fig.  41 
are  constructed  to  contain  six  or  eight  fire-clay 
erndbles,  oc,  access  to  which  is  obtained  through 
Wee  mads  in  the  fire-arch  of  the  furnace.  The 
bottom  of  each  crucible  is  perforated  and  fitted 
wHh  a  tube  to  carrj  off  the  volatilised  zinc  • 
Bering  the  time  of  charging  t.hia  tube  is  closecl 
with  a  wooden-plog,  which  is  of  coarse  burnt 
dunng  the  strong  ignition.  At  first  (he  cmdUes 
tie  left  open,  hat  as  soon  as  a  bluish  fiome  be- 
pns  to  show  itaelf,  the  covers  are  put  on.  The 
omdaiaation-tnbe  is  then  applied  over  a  vessel 
•mtaining  water  to  prevent  the  spirting  of  the 
metoL  The  zinc  is  nltimatelj  refined  by  smelt- 
ing in  iron  cmcibles. 

*Mii«o|M^su      There  are  two  modes  of  ntU- 

0? iKSl  DTtba  ^^"i  this  zino  mineraL  In  one 
^(■■A  Mtom.  plan  the  Eiilphiuet  is  flrtt  roaited 
■>  U  to  aonvert  it  into  oxide,  and  then  treated 
u  before  deseribed ;  or  the  ore  is  direetlj  applied 
bj  oddiog  a  qnantit?  ol  iron  ore  sufficient  to  desol- 
fbiirin  it,  Uine  being  need  as  flni.  Ihe  iron  ore, 
d  eanlsining  water  or  carbonic  acid,  ought  to  be 
Mloinad  prerionity  t«  being  used  tor  this  purpose ; 
M  instead  of  iron  ore  metolho  iron  is  often  nsed. 
W.  Bvindella  haa  proposed  to  oaloina  native 
siljphnret  et  nna  with  common  salt,  the  remit  beiiu 
and  «hloiide  of  sine.    The  moes  being  liiiTiated  with 

^^  d^staUisee,  the  chloride  of  zino  remain*  in  eolation  and  u  precipitated  b;  11 
bnu,  jifllding  oxide  of  zinc.    This  oxide  is  treated  for  metal  in  the  ordiuor;  manner,     tli 

*y^VmttitK.  The  colour  ol  line  u  bluish-white  or  grey;  its  eryBtalline  stmctare 
<m«i  according  to  its  purity,  and  according  to  the  temperature  at  which  it  was  oast  and 
"»  Bwra  or  leas  rapid  cooling.    Whan  zinc  is  cast  and  rapidly  cooled  the  specific  gravity 


Fio.  41. 


m-j^.^. 


80  CHEMICAL  TECHNOLOGY. 

U  7'i7Ei  bat  when  dowlj  eoc4ed  it  i»  7*145,  and  by  humnering  and  luninftting  xavj  be 
increased  to  7'Z  and  eT«o  tj.  A  onbic  foot  of  zino  weighs  therefore,  from  360  to  390  Iba. 
Zine  IB  alightlf  harder  than  tilver,  bnt  like  lead  and  tin  it  is  not  fitted  for  filing,   ■■  it 

cfaokea  the  teeth  of  the  filaa.     When  pore,  £ina  ie  eonoroaB ;  it  is  k  brittle  mstal  | ■mil 

•f  a  tfsrj  sdmU  abeolnte  tenadtj,  bat  offers  a  great  resistance  to  crashing  weight,  wbcai 
not  nibjeeted  to  sadden  blows.  Teij  pore  zinc  maj  be  hammered  oat  at  the  ordinarj  ' 
temperatare,  bat  the  malleabilitv  ia  greatest  at  tempera- 
tnrea  between  100*  and  150°.  Zmc  melts  at  4.11°  in  tli* 
open  air,  and  perfectly  pore  ziim  melta  in  an  atmospbere  of 
hjdn^en  at  410*.  Aooording  to  UM.  Troost  and  E>eTiUe 
zinc  Tolatilises,  air  or  oxygen  being  eidnded,  at  104a*,  and 
m^  be  distilled ;  when  heated  in  oontaot  with  air  to  son' 
zinc  bams,  emittiag  a  very  strong  greenish  blaa-ooloared 
light  and  forming  oxide  of  lino  (zino-white),  wMoh  is  not 
Tolatile.  Of  all  the  metals  need  on  a  large  scale,  ziim  h>a 
the  highest  coefficient  of  eiponsion  by  heat,  its  longitadinal 
ezpaoBion  for  temperatores  from  0°  to  ioa°  beiog  for  oast 
zinc  i|„  tor  sheet  zino  ,i,,  oonseqaently  molten  xino 
greatly  ODatracts  while  oooling.  The  malleability,  tenacity  ,Biid 
coheaive  force  of  zinc  axe  greatly  impaired  by  temperBtonaa 
ranging  from  r50°  to  100*,  at  which  zinc  maybe  polTeiisad. 
Si^jerheated  steam  oxi^ses  Kino  (Ha0-(-3n  — ZnO+Hi), 
and  this  property  is  made  ose  of  In  the  sepuatioD  of  this 
metal  from  lead.  When  exposed  to  a  moist  atmospb«r« 
zino  is  saperfioialiy  oxidised,  bat  as  the  oxide  adheres 
Btmngly  to  the  metal  farther  corrosion  is  prevented.  Zinc 
is  so  readily  oxidised  and  acted  apon  by  water,  weak  aoidj. 
And  alkalies,  that  it  ia  not  at  all  a  saitable  metal  for  Teaaela 
intended  to  hold  potable  liqaids  or  moist  soUdi,  as  thsaa 
'-■^....^■i  eabatances  take  np  zinc  and  become  poisonoas.  An  addi- 
tion of  o'5  pei  cent  of  lead  renders  zino  far  more  malle«ble; 
bnt  if  the  zinc  ia  to  be  need  for  the  pieparatioil  of  brass,  CTen  0*15  per  cent  of  lead  is 
injarioas,  and  for  hraaa-makiiig  Kino  containing  lead  is  avoided.  Zinc  often  oantatna 
some  0-3  per  cent  of  iron,  bnt  this  does  not  impair  the  good  qaalily  ;  the  iron  is  oaiuJlj 
derived  from  the  iron  pota  need  for  re-meiting  the  crude  metal ;  if,  however,  the  qaantity 
of  iron  incressea  the  zinc  becomes  brittle  and  cracks.  Zinc  obtained  from  calunine  ia 
Diaally  porer  than  that  obtained  bom  the  native  salpharet.  The  blaek  reaidae  remauiiiig 
when  zinc  ia  dissolved  in  acids,  and  often  mistaken  for  a  carbnret  of  zine,  if  a  miitore  in 
Tarions  proportions  of  iron,  lead,  and  carbon.  The  more  impare  the  zinc,  the  more 
readily  it  is  dissolved  in  aoids ;  bat  by  oarefal  distillation  zinc  may  be  almost  entirely 
freed  from  any  foreign  metals.  In  oontaet  with  iron  zino  prevents  tbe  oiidatiou  of  that 
metal.  Zino  precipitates  copper,  silver,  lead,  oadmiam,  arsenic,  atttimoiiy,  and  othe>* 
from  their  soLationB. 

^pUHtkB  ai  ziu.  This  metal  ia  very  largely  ozed  for  oovering  roofs,  making  wNtar- 
spouts,  tanks  for  holding  water,  and  for  vaiions  architectoral  pnrposea.  It  should  bs 
bome  in  mind  that  for  roofing  purposes  sine  is  in  so  far  dangerous  as  to  greatly  inoreaoa 
the  intenaity  of  fire  shoald  boUdings  covered  with  zinc  become  ignited ;  one  instanse  a( 
this  danger  was  exhibited  in  Uarch,  1866,  when  the  huge  wooden  baiJding  then  itandiitg 
in  Iiown  Eennington  Lane,  and  used  as  a  floor-cloth  factory  caaght  Ore,  the  buming  of 
the  sbeeti  of  zinc  covering  the  roof  prodaoing  a  heat  so  intense  as  to  ignite  no  leas  than 
•ixtean  adjaeent  bosses,  althoo^  these  were  from  20  to  30  yards  from  the  baming  ahed. 
Zine  is  need  in  galvamc-batterieH,  in  varions  alloys,  in  chemical  laboratories,  and  for 
galvanising  iron  wires,  as  well  as  for  the  preparation  of  zinc-white,  aad  for  variooa 
ornament^  castinga.  whioh  are  made  in  iron  moalds  previonsly  thoronghly  heated  to 
prevent  a  too  rapid  cooling  and  contraction  of  the  metal.  ThePmssians  make  nse  of  sitie 
for  oartridges.  Tbe  total  annnal  prodnction  in  Eniope  of  this  metal  amomited  {1870)  to 
2,154,000  cwts.,  of  which  England  prodnces  150,000  cwts.;  in  the  metropolis,  Viailla 
Montagne  (Belgiam)  zino  is  almost  eidosiTely  used. 

Prepjuutiohs  op  Zinc. 
ziBC'wuit.    Under  this  name  tbere  has  doring  the  last  fourteen  years  been  bronght 
into  the  muket  anbydroue  white   oxide  of  zinc,  applied  instead  of  white-lead  as  a 
pigment     Zinc-white  is  prepared  for  this  purpose  b;  oxidiung  metallic  zinc  in  fire- 


PREPARATIONS  OF  ZINC,  8i 

cIaj  retorts,  placed  to  the  nmnber  of  8  to  i8,  in  a  reverberatory  furnace.  As  soon  as 
these  retorts  are  at  a  bright  white-heat,  cakes  of  zinc  are  placed  in  them,  and  the 
Taponrs  of  the  metal  on  leaving  the  retort  are  brought  into  contact  with  «  current 
of  air  heated  to  300** ;  oxidation  results,  and  the  oxide,  a  very  loose,  snow-white, 
floceulent  material,  is  carried  by  the  current  of  hot  air  into  condensing  chambers, 
and  gradually  deposited.  The  oxide  thus  prepared  is  immediately  fit  for  use ;  it  is 
of  a  pure  white  colour,  and  very  light.  Zinc- white  is  also  prepared  by  exposing 
metallic  zinc  to  the  action  of  superheated  steam,  hydrogen  being  at  the  same  time 
evolved,  and  used  for  illuminating  purposes,  as  at  Narbonne,  St.  Chinian,  G6ret,  and 
a  few  other  places,  where  it  is  known  as  platinum-gas,  because  the  flame  is  used 
for  imparting  a  white  heat  to  small  coils  of  platinum  wire,  thus  producing  a 
veiy  steady  and  highly  pleasant  light.  As  regards  the  use  of  zinc-white  as  a 
pigment,  it  is  rather  more  expensive  than  white-lead,  yet  according  to  some  is 
a  hotter  covering  material  in  the  surfiBkce  proportion  of  10  to  13,  that  is  to  say,  13  parts 
by  weight  of  zinc-white  cover  as  much  space  as  10  of  white-lead ;  moreover,  zinc- 
white  is  not  affected  by  sulphuretted  hydrogen.  Like  white-lead,  this  compound  may 
be  mixed  with  other  pigments.  By  mixing  Rinmann's  green  with  it  a  green  colour 
nay  be  obtained ;  blue  with  ultramarine ;  lemon-yellow  with  cadmium  orange- 
yellow  (sulphuret  of  cadmium). 

wuuTibioi.sidpiiat«       Zinc-vitrioI  (SZnO^+yHaO),  sulphate  of  zino  or  white  vitriol,  is 
of  Zinc.  found  as  a  native  nunoral,  as  a  product  of  the  oxidation  of  rinc- 

blende ;  it  is  also  prepared  by  disRolving  zino  in  dilnte  sulphuric  acid,  and  by  roasting 
Dative  zinc  sulphuret.  This  vitriol  occnrs  in  white  agglomerated  oryetals  and  in  small 
aeicnkr-shaped  crystals,  as  purified  sulphate  of  zinc  ;  it  is  used  as  a  *'  dryer"  in  oil  paints 
and  varnishes ;  as  a  mordant  in  dyeing  for  disinfecting  purposes,  and  sometimes  as  a 
aonee  of  oxygen,  since,  on  being  submitted  to  a  red  heat,  it  gives  off  sulphurous  acid  and 
oxygen,  oxide  of  zinc  remaining. 

Qraaatoof  ziae.  This  preparation,  obtained  by  precipitating  a  solution  of  sulphate  of 
zino  with  bichromate  of  potassa,  is  a  very  fine  yeUow-coloured  powder,  used  now  and 
then  in  pigment  printing,  because  it  is  soluble  in  anmionia,  and  thrown  down  again  as  a 
powder  insoluble  in  water  when  that  menstruiuu  is  volatilised.  A  basic  chromate  of  zino 
ifl  nsed  as  a  pigment  in  the  paint  trade. 

cuoddt  of  Zinc.  This  compound  of  zinc,  ZnCljf  is  obtained  either  hj  dissolving  zinc  in 
hydrochloric  acid,  or  more  cheaply  by  causing  the  hydrochlorio  acid  gas  given  off  in 
manufacturing  soda  to  act  upon  native  sulphuret  of  zinc.  By  this  action  sulphxuretted 
brdrogen  is  formed  which  can  be  burned  to  produce  sulphurous  acid  for  the  sulphuric 
iotd  ehambers.  The  solution  of  chloride  of  zinc  thus  obtained  is  evaporated  to  the  con- 
mteney  of  a  syrup. 

Anhydrous  chloride,  of  zinc  is  obtained  by  heating  an  intimate  mixture  of  dried 
■nlpha^  of  zino  and  chloride  of  sodium ;  chloride  of  zinc  is  formed  which  sublimes,  and 
•olphateof  soda  which  is  left  behind  (ZnS04-f  2NaCls=NaaS04+ZnCla).  "^^^^^  anhydrous 
ehloride  may  be  sometimes  advantageously  used  instead  of  strong  sulphuric  add,  for 
instance,  in  rape  and  colza  oil  refining,  and  perhaps,  although  it  would  be  more  expensive 
and  less  manageable,  in  the  manufacture  of  garancine  from  madder.  This  chloride  has  of 
late  been  applied  instead  of  sulphuric  acid  in  the  manufacture  of  stearic  acid,  and  in  the 
preparations  of  ether  and  parchment  paper.  Chloride  .of  zino  in  a  strong  and  crude  solu- 
tion is  largely  and  very  successfully  used  for  preserving  timber ;  in  paper  making  for  the 
deeomposition  of  bleaching  powder  for  bleaching  the  half-stuff  and  rags,  and  also  in 
■izing  the  paper.  The  disinfectants  sold  as  Sir  William  Burnett's  Fluid  and  Drew's 
Biiinfeotant  are  solutions  of  chloride  of  zinc.  The  salt  used  in  soldering  iron,  zino, 
P^vter,  dte.,  is  a  compound  of  the  chlorides  of  zinc  and  anunonium  (2NH4Cl-|-ZnQ2) ;  its 
solution  is  obtained  by  dissolving  3  parts  by  weight  of  zinc  in  strong  hydrochloric  acid, 
■nd  adding  after  the  solution  is  complete  an  equal  weight  of  sal-ammoniac.  Oxychloride 
^  zmo,  obtained  by  mixing  oxide  of  zinc  with  a  concentrated  solution  of  chloride  of  zinc, 
^  with  solutions  of  chlorides  of  iron  or  manganese,  has  been  recently  proposed  by 
V.  Borel  as  a  plastic  mass  suited  for  stopping  hollow  teeth. 


82  CHEMICAL  TECHNOLOGY. 

Cadmium. 
(Cd=:ii2;  Sp.gr. =8-6.) 

This  metal  is  rather  rare,  and  as  yet  of  very  limited  use ;  it  is  a  constant  companion 
of  zinc  in  varying  quantities,  but  is  only  found  in  the  Silesian  zinc  ores  in  suificiency 
to  repay  the  trouble  of  extraction.  It  was  discovered  as  a  distmct  metal  by  Dr. 
Stromeyer,  at  Hanover,  and  Dr.  Herman,  at  Schonebeck,  in  1817.  As  A^S^ 
properties,  AOilminnn  stands  between  zinc  and  tin ;  the  colour  and  metalLc  xuhue  ot 
cadmium  are  similar  to  those  of  tin ;  it  is  ductile  and  malleable,  but  more  readily 
acted  upon  by  atmospheric  oxygen  and  moisture  than  tin.  The  specific  gravity  of 
cadmium  is  8*6 ;  it  melts  when  quite  pure  in  an  atmosphere  of  dry  hydrogen  at  320°, 
and  boils  and  volatilises  (air  and  oxygen  being  absent)  at  860^  to  746'2°.  The  cadmium 
sold  by  manufacturing  and  operative  chemists  and  opticians  is  in  small  round  bars, 
weighing  from  60  to  90  grms.  Silesian  calamine  ore  contains  about  5  per  cent 
cadmium ;  the  same  ore  found  near  Wieslock  2  per  cent ;  the  zinc-blende  found  at 
the  Upper  Harz  contains  from  035  to  079  per  cent  cadmium ;  ziac-blende  from 
Przibram,  Hungary,  178  per  cent;  and  the  zinc  ore  of  Eaton,  in  North  America, 
about  3*2  per  cent  cadmium.  Such  ores  give  off,  while  being  heated  in  the  zinc 
furnace,  a  brownish-coloured  smoke,  consisting  of  carbonate  of  zinc  and  metallic 
cadmium ;  this  smoke,  condensed  separately,  is  used  as  cadmium  ore,  and  reduced 
by  means  of  charcoal,  the  materials  being  placed  in  iron  retorts  and  the  metal  distilled 
over,  next  refined,  and  oast  in  the  small  bars  mentioned  above.  The  annual 
production  of  cadmium  in  Belgium  from  Spanish  zinc  ores  amounts  to  about  5  cwts. ; 
while  Silesia  produces  some  2  cwts.  annually. 

Mixed  with  lead,  tin,  and  bismuth,  cadmium  forms  the  so-called  Wood^s  alloy  or  fusible 
metal,  consisting  of  cadmium,  3  parts;  tin,  4;  bismuth,  15 ;  and  lead,  8  parts ;  this  alloy 
fuses  at  70^,  and  is  used  for  stopping  teeth,  and  for  soldering  surgical  instruments.  M.  Hofer- 
Grosjean  used  as  stereotype  metal  an  alloy  consisting  of  lead  50,  tin  36,  and  cadminm, 
22*5  parts.  The  only  preparation  of  cadmium  technically  used  to  any  extent  is  the  oad- 
xxdum-jeilowy  Jaune  hriiliant  (CdS),  sulphuret  of  cadmium,  applied  as  a  pigment  in  oil 
painting,  and  in  pyrotechny  for  producing  blue-coloured  flames.  This  preparation  is  best 
obtained  by  precipitating  a  solution  of  sulphate  of  cadmium  with  snlphuret  of  sodinin, 
and  then  thoroughly  washing,  pressing,  and  drying  the  precipitate.  Dr.  Van  Biemsdijk  of 
the  Utrecht  IMQnt,  while  experimenting  with  cadmium  and  zinc,  both  pure  and  kept  fused 
in  an  atmosphere  of  pure  dry  hydrogen,  found  that  these  metals,  though  perfectly  non- 
volatile at  their  point  of  fusion,  and  while  kept  fluid  at  that  temperature,  became  percep- 
tibly volatilised  at  a  few  degrees  above  this  point. 

Antimony. 
(Sb=i22;  Sp.  gr.=67i2.) 

Antfawmy.  This  metal,  also  named  stibium,  is  chiefly  found  in  combination  with 
sulphur  as  black  antimonial  ore,  or  glass  of  antimony,  containing  71*5  per  cent  of 
metallic  antimony,  formula  (Sb2S3),  in  veins  interspersed  among  granite  and 
metamorphio  rocks.  Antimony  also  occurs  as  oxide  (Sba03)  in  the  minerals  known 
as  Yalentinite  (rhombic)  and  Senarmontite  (tesseral),  this  last  variety  being  found  in 
large  quantities  in  Constantine,  Algeria,  and  in  Borneo.  The  black  sulphuret  of 
antimony  is  separated  from  the  gangue  which  contains  it  by  the  application  of  heat, 
as  the  sulphuret  is  very  fusible. 

The  operation  is  carried  on  at  Wolfsberg,  near  Harzgerode,  Germany,  by  placing  the 
broken  up  ore  and  gangue  in  crucibles,  b  (Fig.  42),  perforated  at  the  bottom,  and  placed 
on   a   smaller    orudble,  c,   surrounded   with   hot  sand   or  ash.     The  waUs   are  oi 


brickirork,   lo  conEtracted  with   openings  for  oaiiamg  a  drangbt 
beat  to  the,  upper  cmoible.      Wood   '  "         ■-  -'       '-    -■' 

in  Honguj,  the  apparatuB  exhibited  i 
will  be  Been  the  principle  Ib  the  same, 
bnt  bet.  the  cmcibleB  containing  the 
ore,  and  the  teoeiiing  araciblea  ontEide 
the  fnniaoa,  and  comieoted  i>j  means 
'  -'  "  h  the  inside  oruoibles,  are 
of  ft  pore  ^Uy  placed.  The  liqua- 
uoa  ol  lu^ '  rather  fnsible  antimon; 
CIS  ii  most  readilj  and  conrenientl/ 
performed  in  the  hearth  of  a  pecnliarlj 
moBtnieted  reverberator;  fnmace,  ex- 
hibited in  Fig.  4j ;  the  main  point  of 
the  arroogemeut  of  the  hearth  being 
Ihat  the  molten  black  sulphniet,  col- 
lected at  the  lowest  level,  ranB  thiongh 
the  spoot,  e,  to  the  reeeiier,  /,  placed 
•mtnde  the  famace.  At  Gist  a  mode- 
rate heat  miGoea,  bat  to  wards  the  latter 
}>irt  of  the  operation  a  stronger  heat 
u  Tsqnired  to  eliminate  all  the  snl-  ' —  - 
Fhuet.  I'he  opening  at  /  ia  now 
cioaed  with  a  ping.  Not  tmtil  the  gangne  becomes  sei 
vhsn  the  haarier  enlphoiet  oollected  under  the  slag  is 
«/■ 


Metallic  intinlotiy  ia  obtained  from  the  black  sulphuret  either  by  roasting  or  hy 
nnelting  it  with  BOitable  fluTes  In  the  former  inBtance  th?  suJphuret  is  placed  on 
the  hearth  of  a  reverberatorj  furnace  and  continuously  etured,  while  a  supply  of  air 
w  Kteaa  to  the  molten  masa ;  the  cBlcination  is  continued  until  the  bulk  of  the  ore 
'iscoDrerted  into  antimoniate  of  antimony-oxide.  This  material,  also  known  as 
■iilunDiu^  aah,  is  rednced  to  metal  in  crucibles,  and  for  the  reduction  heat  alone 


84  CHEMICAL  TECHNOLOGY. 

would  answer,  as  the  calcined  ore  always  contains  nndecomposed  snl^nret  of 
antimony,  (3  Sb408+ 481)283  »2oSb+i2S02);  but  as  some  oxide  of  antimony  would 
be  lost  by  volatilisation,  the  crude  antimonial  ash  is  mixed  with  crude  argol  or 
with  charcoal-powder  and  carbonate  of  soda.  A  strong  red  heat  is  sufficient  for  the 
reduction,  and  it  is  customary  to  allow  the  metal  to  cool  slowly  under  the  super- 
natant slag,  in  order  to  obtain  the  peculiarly  crystalline  appearance  desired  in 
metallic  antimony  in  the  trade. 

By  another  mode  of  operation  the  sulphnr  is  first  removed  from  the  black  solphiiret  by 
means  of  iron,  but  which,  if  used  by  itself,  presents  a  difficulty  arising  from  tiie  almost 
equal  specific  gravities  of  the  metallic  antimony  and  snlphuret  of  iron,  rendering  the  sepa- 
ration of  these  substances  too  imperfect  to  admit  of  the  use  of  iron  alone ;  consequent^, 
either  carbonate  or  sulphate  of  soda  or  potassa  is  added,  which  tends  also  to  increaae  the 
fluidity  of  the  slag.  100  parts  of  black  sulphuret  of  antimony,  42  parts  of  maUeabb 
iron,  10  parts  of  dry  sulphate  of  soda,  and  3^  parts  of  charcoal  powder  are  the  pro- 
portions. In  order  to  eliminate  the  arsenic  from  the  metallic  antimony  thus  obtained,  16 
parts  are  taken,  and  there  are  added  2  parts  of  protosulphuret  of  iron,  i  of  solphuret  of 
antimony,  and  2  of  dry  soda;  this  mixture  is  kept  fused  for  fully  one  hour's  tiiDB, 
the  resulting  metal  is  next  fuseid  with  li  parts  of  soda,  and  a  third  time  with  z  part 
of  soda,  until  the  supernatant  slag  attains  a  bright  yellow  colour. 

Properties  of  Antimony.  The  metallic  antimony  of  commerce  is  never  quite  finee  from 
arsenic,  iron,  copper,  and  sulphur ;  the  influence  of  these  impuritieB  on  the  physical 
properties  of  antimony  is  not  well  ascertained,  as  those  of  chemically  pure  antimony 
are  not  well  known. 

Antimony  may  be  purified  by  fusing  it  with  oxide  of  antimony;  the  snlpbur 
and  iron  are  oxidised  and  some  of  the  oxide  of  antimony  reduced  to  metaL  For 
pharmaoeutical  purposes  antimony  is  purified  by  the  addition  to  the  molten  metal  of 
pure  saltpetre,  but  this  process  is  attended  with  a  loss  of  antimony.  Antimony  pos- 
sesses a  nearly  silver- white  but  slightly  yellowish  colour,  strong  metallic  lustre,  and 
a  foliated  crystalline  structure ;  it  crystallises  like  arsenic  and  bismuth  in  rhombcidio 
crystals.  The  specific  gravity  of  antimony  is  ^6'ji2;  it  melts  at  430^  the  pura 
metal  fuses  at  450"*,  and,  according  to  Dr.  Duflos,  does  not  expand  on  cooling. 
Antimony  is  volatilised,  air  and  oxygen  being  excluded,  only  at  a  bright  white  heat 
It  is  a  very  brittle  metal,  neither  ductile  nor  malleable,  but  harder  than  copper. 
Antrmony  forms  alloys  readily,  imparting  to  them  some  of  its  own  brittleness  and 
hardness;  it  is,  therefore,  added  to  tin,  lead,  and  pewter,  in  small  quantities, 
to  render  these  soft  metals  hard.  As  antimony  is  not  readily  acted  upon  by  air,  it 
has  been  suggested  to  electrotype  copper  with  a  thin  layer  of  this  metaL  The 
powder  sold  as  ironblack,  and  used  to  give  to  papier  mache  and  plaster  of  Paris 
figures  the  appearance  of  polished  steel,  is  finely  divided  antimony,  obtained  by  preci- 
pitating that  metal  from  its  solution  in  an  acid  by  means  of  metaUio  zino;  thia 
powder  is  also  used  to  impart  a  lustre  to  cast  zinc  ornaments.  The  chief  uae  made 
of  antimony  is  as  an  alloy  for  printing  type,  which  usually  consistB  of  4  parts  of 
lead  and  i  of  antimony  with  a  small  quantity  of  copper.  Antimony  also  enters  mio 
the  hard  so-called  anti-friction  alloys  used  for  the  bearings  of  machiDery. 

Antimonial  Preparations  in  Txchnical  Ubb. 

Oxide  of  Antimony.  This  substauce  (Sb^OO,  obtained  by  calcining  sulphuret  of  antimony, 
or  by  the  precipitation  of  a  solution  of  chloride  of  antimony  with  a  solution  of  earbonate 
of  soda,  finally  washing  and  drying  the  precipitate,  has  of  late  been  used  as  a  subsytufee 
for  white-lead,  but  does  not  cover  so  well  and  is  more  expensive,  though  it  is  not  affeotad 
by  sulphuretted  hydrogen.  As  this  oxide  takes  up  oxygen  in  the  presence  of  alkalies,  and 
is  converted  into  antimonio  acid  (SbaOs),  it  has  been  lately  proposed  for  use  in  the  prepa- 


ABSENIC.  85 

ration  of  anOine  red  and  for  the  oonversion  of  nitrobensol  into  aniline;  also  for  the 
pzeparation  of  iodide  of  caloixun  bj  keeping  antimonio  oxide  suspended  in  milk  of  lime, 
and  adding  iodine  as  long  as  the  latter  is  taken  up. 

BiMk  sniphnnt  This  oompoond  (SbaSs),  obtained  by  liquation,  ooours  in  oommeroe  in 
of  AnUmaaj.  ^jj^  oonical  shapo  it  has  assumed  while  oooling;  its  colour  is  like  that 
of  graphite,  but  it  has  a  stronger  metallic  lustre,  is  of  a  deeper  black  colour,  fibrous, 
OTstalline  structure,  and  veiy  brittle;  it  usually  contains  iron,  lead,  copper,  and  arsenic, 
and  is  employed  for  separating  gold  from  sUyer,  in  yeterinary  surgery,  pyrotechny,  and  in 
the  preparation  of  the  percussion  peUets  used  in  the  cartridges  of  ike  now  celebrated 
Pnusian  needle-gun. 

^  HMpoWaB  T«Dow.  This  pigment,  used  as  an  oil  paint  and  in  glass  and  porcelain  staining, 
is  of  an  orange-yellow  colour,  and  very  permanent.  It  is  antimoniate  of  oxide  of  lead, 
and  is  prepared  as  follows : — i  part  of  antimonio-tartrate  of  potassa  (tartar  emetic), 
3  parts  of  nitrate  of  lead,  and  4  parts  of  common  salt,  are  fused  at  a  moderate  red  heat, 
and  kept  at  that  temperature  for  2  hours.  The  molten  mass  is  put  after  cooling  into 
water  and  becomes  disintegrated,  the  salt  dissolved  and  the  pigment  precipitated.  When 
required  for  staining  glass  or  porcelain  it  is  mixed  with  a  lead-glass,  and  has  recently 
been  prepared  by  roasting  a  mixture  of  antimonious  acid  and  litharge. 

iaOmeuyaaaMbu.  Oxysuphuret  of  antimony  (SbeSeOs),  is  a  compound  in  colour  similar 
toTermillion,  and  is  obtained  by  causing  dithionite  of  sodium  or  calcimn  to  act  upon  proto- 
cUoride  of  antimony  in  water,  and  boiling  this  mixture,  a  precipitate  being  readily 
deposited ;  it  is  a  soft,  yelvety  powder,  unaltered  by  the  action  of  air  and  light,  and  suited 
for  either  oil-  or  water-colour.  This  substance  may  be  prepared  on  a  large  scale  by  the 
following  process : — ^i.)  Black  sulphuret  of  antimony  is  calcined  in  a  current  of  air  and 
rteam,  antimonio  oxide  being  formed  as  well  as  sulphurous  acid,  which  may  be  employed 
for  the  preparation  of  caldum-dithionite  from  soda  waste;  the  antimonic  oxide  is 
next  diflsolyed  in  crude  hydrochloric  acid.  (2.)  Large  wooden  tubs  which  admit  of  being 
internaUy  heated  by  steam,  are  for  }ths  of  their  capacity  fiUed  with  the  solution  of 
«Ueiimi  dithionite,  and  the  solution  of  protochloride  of  antimony  is  gradually  added,  the 
Hqnid  being  stirred  and  heated  to  about  60** ;  the  reaction  soon  ensues,  and  the  precipitate 
having  subsided,  is  thoroughly  washed  and  dried  at  a  temperature  not  exceeding  50°. 
There  are  prepared  on  a  large  scale,  by  operative  pharmaceutical  and  manufacturing 
chemists,  numerous  varieties  of  antimonud  preparations,  among  which  are  severid 
ralphurets  and  one  oxysulphuzet,  different  from  the  preparation  here  mentioned. 

Absenic. 
(Afl  =  75 ;  Sp.  gr.  =  5'6.) 

AiMBk.  Arsenio  oocnrs  in  the  mineral  kingdom  either  native  or  in  oombination 
viih  sulphur.  Although  a  few  minerals  are  found  containing  arsenic  in  a  state 
of  oxidation,  the  quantity  is  so  small  that  their  technical  utUisation  for  the  obtaining 
of  arsenical  compounds  is  altogether  out  of  the  question.  Metallic  arsenic  is  a 
BoHd,  crystalline,  steel-grey  coloured  substance.  It  is  prepared  either  by  the  subli- 
nation  of  the  native  metal,  or  by  the  ignition  of  arsenical  iron  pyrites  (FeS^-f  FeAss) 
tnd  of  arsenical  pyrites  (Fe4As6),  or  by  the  reduction  of  arsenious  add 
(AstOj-f  30=:3G04-Asa).  Metallic  arsenic  is  met  with  in  the  trade  in  an  impure 
state,  often  containing  no  less  than  10  per  cent  of  sulphuret  of  arsenic,  in  the  form  of 
gnyiah-bkck  coloured  crusts  and  lumps,  known  as  fly  poison.  Pure  metallic  arsenic 
is  nrdy  employed ;  a  small  quantity  is  used  in  the  manufacture  of  shot,  and  in  pyro- 
techny for  white  Bengal  fire,  which  gives  a  very  brilliant  light,  but  should  only  be 
Ignited  in  the  open  air.  Lastiy,  arsenic  burnt  in  oxygen  gas  is  used  as  signal  lights 
^  the  Trignometrical  Survey  Service. 

A«"i*»MAflid.  The  substance  known  as  white  arsenic  is  really  arsenious  add,  AS2O5, 
•iid  obtained  as  a  by-product  of  a  great  many  metallurgioal  operations,  for  instance, 
the  roasting  of  cobalt  ores  for  smalt,  of  tin  and  silver  ores ;  the  volatilised  add  is 
condensed  by  conducting  it  through  channels  into  wooden  chambers.  In  some 
"^•BtieB,  as  in  Silesia,  where  fuel  and  labour  are  cheap,  arsenical  pyrites  is 
P'UT^^^ly  calcined,  and  the  crude  arsenious  add  obtained  is  refined  by  another 


86  CHEMICAL   TBCHHOLOGY. 

Bublimatioii  process.  For  this  purpose  tbe  cast-iron  vessels,  a,  Fig.  46,  annsed.npon 
which  are  placed  iron  rings  or  collars,  6,  c,  d,  and  a  hood,  e,  conunonicating  by  means 
of  tubes  with  a  series  of  chambers,  of  which  the  first  only  is  shown  in  i.  Tha 
flanges  of  the  oast-iron  collars  and  all  other  joints  having  been  thoronghly  Inted,  the 
fire  is  lighted  and  the  heat  so  increased  as  to 
'"*■  46'  icause  tha  Hemi-fusion   of  the  arsenioDs  acid, 

which  after  cooling  exhibits  a  peculiarly  porce- 
lain-like appearance,  at  first  being  as  trane^iareiit 
as  glass  and  very  pimilar  h>  fused  anhydrona 
phosphoric  acid. 

This  contponnd,  like  nU  arsenical  preparationa, 
is  veiy  poisonous ;  but  it  is  a  remarkable  fact, 
proved  by  direct  experiment,  that  pnre  metallio 
arsenic  introdoced  into  the  stomach  of  rabbifs 
and  other  small  animals  in  a  finely  divided 
state,  by  the  aid  of  pure  water  freed  from  air, 
docs  not  act  on  them  as  a  poison,  being  foimd  in 
their  ficces  unaltered.  The  commercial  ariicle  is 
sometimes  more  or  leas  mised  with  oxide  of 
antimony  and  eulphuret  of  arsenic.  Aiseniooa 
acid  is  need  in  dying  and  calico-printing,  in 
gless-maldng,  for  the  pnrpoae  of  clearing  the 
molten  glass,  for  the  preparation  of  other 
arsenical  compounds  and  pigmeots,  and  farther 
in  arsenioal  soap  for  tlie  preservation  of  stuffed 
animals.  The  air  in  muBeoms  is  sometimes 
poisoned  by  arseniuretled  hydrogen  being  evolved 
if  the  arsenical  compound  has  not  been  properly 
prepared;  and  in  places  where  there  are  large 
collections  of  stuffed  animals  there  should 
always  be  a  good  ventilation  and  a  dry  atmosphere.  Arsenioua  acid  is  also  employed 
in  the  manufactnre  of  aniline. 

Amiaidi  This  add  (H,As04)  has  become  an  article  of  large  consnmption. 
It  is  obtained  by  boiling  400  Mlos.  of  araenions  acid  in  300  HIob.  of  nitric  or  nitro* 
hydrochloric  acid,  and  evaporating  the  solution  to  dryness.  Recently  it  has 
been  prepared  mora  cheaply  by  passing  chlorine  gas  into  water  wherein  arsenioiUi 
acid  ia  suspended,  and  evaporating  this  solution.  Arsenio  add  is  aometimeB 
employed  in  calico-printing  instead  of  tartaric  acid,  and  is  very  largely  used  in  the 
preporadou  of  rosaniliqe  or  fschidne.  some  manufacturers  of  these  dyes  annually 
consuming  zooo  cwta. 

The  acid  arseniate  of  soda,  so-called  dungsalt,  now  used  instead  of  cows'-dung  in 
certain  oalioo-printing  operations,  and  consisting  of  2j  parts  of  soda  and  75  of 
arsenions  acid,  is  prepared  by  heating  for  a  length  of  time,  either  36  parts  of 
^Tsenions  acid,  and  30  parts  of  nitrate  of  soda,  or  a  mixture  of  arsenile  of  soda  and 
nitrate  of  soda.    This  salt  is  obtained  as  a  by-product  of  the  preparation  of  aniline 


from  nitrobenzol. 
Bnipiunii  Di  Annb.      There  a 
realgar  and  orpiment 


i  two  Bulphorets  of  a: 


c  employed  indnstriaUy,  vi?., 


QUICKSILVER,  OR  MERCURY.  87 

Bed  arseme  or  realgar  (AS2S2)  is  found  native  in  a  orystalline  state  and  among 
other  ores.  It  la  artificiidly  prepared  oy  fusing  together  sulphur  and  excess  of  either 
metaUie  arsenic  or  arsenious  acid,  or  on  a  large  scale  hy  <Hstilling  arsenical  pyrites 
and  ores  containing  sulphur.  Bealgar  is  a  ruhy-red  coloured  substance,  exhibiting  a 
conehoidal  fracture.  Its  use  in  pyroteohny  is  based  upon  its  property  of  yielding,  when 
mixed  with  saltpetre  and  ignited,  a  brilliant  white  light.  This  mixture  is  known  as 
Bengal  white  light,  and  is  best  prepared  with  24  parts  of  nitrate  of  potassa,  7  parts 
of  salphur,  and  2  parts  of  realgar. 

oipiBCBL  Auri  pigmentumt  yellow  snlphuret  of  arsenic  (AS3S3),  is  likewise  found  native, 
but  is  generally  art&cially  prepared  by  fusing  together  eiuier  sulphur  and  arsenious  acid 
or  realgar  and  arsenious  acid.  This  sulphuret  is  of  a  bright  orange-colour,  somewhat 
transparent;  it  contains,  if  prepared  by  the  dry  method,  free  arsenious  acid,  and 
may  therefore  be  considered  as  arsenoxysulphuret.  It  is  also  prepared  by  pr^ipitating 
a  hydrochloric  acid  solution  of  arsenious  acid  by  means  of  sulphuretted  hydrogen,  or  by 
decomposing  a  solution  of  the  double  sulphuret  of  arsenic  and  sulphuret  of  sodium  with 

BoBBA.  dilute  sulphuric  acid.  Orpiment  is  used  in  dyeing  to  reduce  indigo,  and  to 
prepare  what  is  termed  rusma,  a  paste  applied  in  dressing  slmiB  in  order  to  remove  the 
bair,  and  which  consists  of  9  parts  of  Ume  and  i  of  orpiment  mixed  with  water.  This 
paste  is  also  employed  in  the  toilet  to  remove  superfluous  hair ;  but  instead  of  this  very 
poisonous  compound,  either  the  spent  lime  from  the  purifiers  of  gasworks,  or  the 
sulphuret  of  lune  solution  obtained  by  passing  a  current  of  sulphuretted  hydrogen 
through  milk  of  lime,  may  be  advantageously  used. 

Quicksilver,  ob  Meboury. 
(Hg=aoo;  Sp.  gr.=i3-5.) 

omotmmii^  This  metal  is  not  met  with  so  generally  dispersed  as  silver  and  gold. 
v«Koi7-  It  occurs  in  the  following  forms: — 'i.  Sparingly  in  the  metallic  state 
interspersed  in  globules  through  the  gangue,  and  in  small  qiuintitids  in  mercury 
mines,  sometimes  containing  sOver.  2.  As  a  sulphuret,  known  as  cinnabar,  HgS,  con- 
taining 86*29  of  metallic  mercury  and  137 1  of  sulphur.  This  ore  is  met  with  among 
primitive  as  well  as  metamorphic  and  sedimentary  rocks,  and  is  often  accompanied 
by  sulphuret  of  iron,  while  the  gangue  or  matrix  is  generally  quartz,  calcareous 
spar,  or  spathic  iron  o^e.  The  richest  mercury  mines  are  those  of  Almaden 
and  Almiidenejas  in  Spain,  which  were  worked  at  a  remote  period  of  antiquity,  and 
next  are  those  of  Idria,  Carynthia.  Cinnabar  is  found  also  in  the  Ehenish  Palatinate, 
at  Olpe  in  Westphalia,  Horzowitz  in  Bohemia,  in  varions  parts  of  Hungary,  at 
Vall*alta  in  Venetia,  in  the  Oural,  in  China  and  Japan,  in  Borneo,  Mexico,  at 
Huancavelica,  in  Pern,  and  in  considerable  quantities  in  California,  where  mercury  ia 
largely  produced. 

Among  the  less  important  mercury  ores  is  found  the  so-called  liver-coloured  ore,  a  clay 
mixed  with  cinnabar,  bitumen,  paraffine,  and  ooaJ-slate.  This  ore  is  only  met  with  in 
GaiynthiA.  There  is  also  the  fawn-coloured  mercury  ore,  containing  2  to  15  per  oent 
of  merooiy,  with  sulphur,  copper,  and  other  impurities,  llie  annual  production  of  mer- 
eory  throughout  the  globe  amounted  in  1870,  to  84,500  ewts.,  of  which  California  yields 
56,000  against  22,000  from  Spain. 

Uercnry  is  extracted  from  its  chief  ore,  cinnabar,  by : — 

1.  Calcination  in  shaft  furnaces,  the  mercurial  vapours  being  condensed  in  chambers  con- 
stmeted  either  of  brick-work  or  boiler-plate,  or  in  earthenware  vessels  (Aludels)  joined 
together  by  flanges  similar  to  earthenware  drain-pipes. 

2.  By  decomposing  cinnabar  in  closed  vessels,  the  ore  being  mixed  with  either  lime  or 
forge  scales.    This  method  is  usual  in  Bohemia  and  the  Bavarian  Palatinate. 

Mrthodof  Extzveunir      The  coutrivances  in  use  in  Idria  for  the  extraction  of  mercury 

HemrTpnnaed  *^ 

tn  JitiM.  from  i\s  ores  are  illustrated  in  Figures  47,  48,  and  49.    a  is  a  cal- 

cination famace,  which  is  flanked  on  each  side  by  a  series  of  condensation  chambers, 
c  c  D,  communicating  with  the  furnace.  The  ore  is  placed  in  lumps  on  the  perforated 
^ches,  n  n',  of  the  furnace,  and  the  space  v  completely  filled.    On  the  arch,  p  p\  the 


8S 


CHEMICAL  TECSNOLOQY. 


smollei  lumps  of  ore  are  plooed,  and  on  r  r,  &e  dust,  pnlTernlent  ore,  utd  reaidneB 
of  former  operations.  This  having  been  done  the  ftiel,  commonly  diy  beechwood,  is 
ignited  on  the  Airnaoe-b&ra.  The  heat  is  gradual);  raised  to  and  kept  at  a  dark  red 
heat  for  lo  to  12  hours.     The  dranght  created  carries  into  the  fiimaoe  enffioietit  air 

Fio.  47. 


to  convert  the  Bolphur  of  the  Tolatjlised  ore  into  Bnlphnnnis  add  and  set  t]ie 
mercury  free  iHgS-f  20=S0i4'Hg).  The  products  of  die  combustion  are  earned 
into  the  chambers,  c.  The  bottom  of  each  chamber  is  made  of  etrongl;  piesaed  day, 
shaped  so  aa  to  form  two  planes  inclined  towards  each  oiher,  and  connected 
trilh  gutters  leading  to  a  reservoir  cut  out  of  a  solid  block  of  porphyry  in  which  the 
ipercury  is  collected.  A  jet  of  water  is  made  to  play  constantly  in  the  last  conden- 
sation-chomber,  in  order  to  keep  it  and  the  adjoining  smoke-chambeis,  d  d,  quite  cool, 
the  last  traces  of  mercury  being  condensed  in  d  s. 


QUICKSILVER.  OR  MERCURY.  89 

Mil*  HfH™*  ■■  ^^  BRangement  for  oondensiiig  the  meronrial  Taponn  in  tue 
•'^'■"■*  ""••^-  «t  Almadea  is  exhibited  in  Fig.  50.  It  oonsiBts  of  a  atring  of  pear- 
ihqied  vessels  open  at  both  ends.  Theae  vewels,  locall;  known  bj  the  Arabian  t«rm, 
AhtdtU,  ara  made  of  Mtrthenware,  and  so  constructed  that  the  narrow  end  of  one  fits 
into  the  wider  end  of  the  olh«r,  care  being  taken  to  Inte  the  joints  with  da;.  The 
mode  of  arranging  these  rows  or  strings  of  (Judela  is  delineated  in  Fig  52, 
which  represents  the  plan  of  the  famace  shown  in  Fig.  51.    This  fnmaoe  oonsista  of 


Fio.  5*. 

( — ■ — -^ 

t     %^^ 

-J^"^ 

F^ 
p, 

II          iiMiil  \m- 

1 

Wi®/, 

•  cj-lindrical  shaft  oven,  which  b;  means  of  a  perforated  arch,  is  divided  into  two 
fWls.  The  fire  is  lighted  in  the  lower  part  of  the  shaft,  while  on  the  perforated 
ttch  is  fint  placed  a  layer  of  sandstone  containing  oinnabar,  in  qoantitiee  too  email 
to  admit  of  being  otherwise  advantageoual;  treated.  He  rich  ore  ia  then  placed  on 
this  layer  of  stone,  and  the  openinga  in  the  arch  of  the  furnace  covered  with  tiles 
ud  tightly  luted.  The  meronrial  vapours  aie  first  conducted  into  the  spsoo 
«c,  and  thence  through  the  twelve  rows  of  aludels,  each  row  having  a  length  of  from 
30  to  21  metres,  and  containing  44  aludels.  The  aludels  are  placed  on  a  somewhat 
inclined  plane  as  shown  in  the  woodcut.    At/the  coudeiksed  mercurj  is  ran  off  by 


90  CSEMICAL   TECHNOLOOY. 

the  gutter,  g,  into  die  stone  cistoms,  kh;  the  vaponrs  not  condensed  being  carried 
on  to  the  chamber,  b,  where  the;  are  completely  liquefied.  The  smoke  escapes 
through  a  chimney  at  b.  As  the  mercuiy  thus  abtnined  is  mixed  iritii  Boot  it  has  to 
be  purified  and  cleansed ;  this  is  effected  by  causing  the  metal  to  flow  down  an 
inclined  plane,  to  which  the  soot  adheres.  The  sooty  mass  and  the  impuritiea 
collected  in  the  room  &,  are  submitted  to  distillation  for  the  purpose  of  extracting  the 
last  traces  -of  mercuiy.  The  quantity  of  ore  operated  upon  at  each  calcination 
amoonts  to  250  to  300  cwts.  Spanish  mercury  is  met  with  in  the  trade  packed 
in  wrought-iron  canisters  or  in  sheepskin  bags.  The  apparatus  above  described  for 
separating  mercuty  from  its  ores  was  invented  by  the  Moora,  who  for  several  centu- 
ries were  the  only  civilised  inhabitants  of  the  greater  portion  of  southern  Spain. 


>u  in.  Di  uu  ui «         Method  oJ  meroury  distillation  pursued  t,t  Honiowitz  in  Bohemia. 
Hbei  aubnuKca.       The  Bulphuret  of  mercury  is  mixed  with  trom  1  to  |  of  its  wei^t  of 
foige-scole,  and  themiiture  placed  on  the  iron  plates,  b  b.  Fig.  53.  These  plates  are  fixed  to  an 


ifon  rod,  and  covered  by  the  iron  oapola,  e  r,  vhich  reels  in  a  tank  filled  with  water.  'Hie 
onpola  is  removable  from  the  furnace  by  means  o(  the  frame  g.  The  metal  is  oolleotad 
in  the  water  at  d.  Each  cupola  oovers  about  )  cwt.  of  ore  and  i  ewt.  of  forgo-seale,  and 
there  are  generally  sli  cupulas  in  one  furnace.     The  operation  lasts  for  30  to  36  hooTH. 

In  the  Bhenish  Palatinate  mercury  baa  hecn  extracted  from  ita  ores  since  1410.  It  is 
there  usual  to  mix  the  mereiuy  ore  with  other  metallic  ores,  that  mainly  worked  being 
ohuabar  interspersed  in  Bondatone.  The  decompoaition  of  the  ore,  which  is  a  rather 
poor  material,  can  lie  made  to  pay  only  by  Rkilfal  management.  The  ore  ia  mixed  with 
lime  and  placed  in  iron  retorts,  very  aimilar  to  those  need  in  gas-works,  and  heat  having 
been  applied  the  cinnabar  is  decomposed,  the  result  being  the  formation  of  metallio 
meromy,  which  volatilisea  and  is  condensed  in  suitably -co  Dstrncted  receivers,  while  there 
remains  in  the  retorts  a  mixtnru  of  sulphuret  of  calcium  and  bypoaulphtte  of  lime.  The 
operation  lasts   ten  hours,  after  wbicb  the  contents  ol  the  receivers  are  poured  into 


PREPARATIONS  OF  MERCURY.  gi 

earthenware  tanks  filled  with  water ;  the  mercury  sipkB  to  the  bottom  and  the  water  is 
allowed  to  ran  off,  carrying  with  it  a  blackish  powder,  consisting  of  finely-divided  mercury 
mixed  with  a  Yolatilised  black  snlphide,  which  is  again  snbmitted  with  lime  to  another 
distillation. 

p)rap«rtiM  of  Meieiiry.  Mercnry  is  the  only  metal  remaining  fluid  at  ordinary  temperatores. 
It  freezes  at  —  sg'S^'t  and  is  in  that  state  a  malleable  and  dnctile  metal.  At  360''  it  boils, 
and  at  a  slightly  higher  temperature  distils  over,  but  is  yolatilised  to  some  extent  at  all 
temperatures  above  its  freezing-point,  as  may  be  proved  by  suspending  a  piece  of  gold-leaf 
in  the  neck  of  a  bottle  containing  a  small  quantity  of  mercury.  Mercury  readily  combines 
at  ordinary  temperatures  with  various  metals,  forming  what  are  termed  amalgams. 
The  ftTnftig«^Tng  most  readily  formed  are  those  of  lead,  bismuth,  zinc,  tin,  silver,  gold ; 
next  is  that  with  copper,  while  with  iron,  nickel,  cobfdt,  and  platinum,  mercury  vdll  only 
amalgamate  with  difficulty.  The  application  of  mercury  in  metiJlurgy  in  the  extraction  of 
gold  and  silver  from  their  ores  is  based  upon  the  property  mercury  possesses  of  readily  com- 
bining with  these  metals.  Amalgams  of  various  lands  are  industrially  employed,  as,  for 
instance,  witli  tin  for  covering  mirrors  and  looking-glasses,  vrith  gold  for  the  so-called 
process  of  fire  gilding  An  amalgam  of  4  parts  mercury  with  2  parts  zinc  and  i  part  tin  is 
used  for  the  cushions  of  electrical  machines. 

Appifcatioiu  of  MereniT*  By  far  the  most  extensive  application  of  mercury  is  in  the  con- 
Etraction  of  various  physical  instruments,  for  filling  the  mercurial  gauges  of  steam-boilers, 
and  on  the  Continent  these  gauges  are  attached  to  all  boilers,  locomotive  engine-boilers 
alone  excepted.  Mercury  is  employed  in  the  preparation  of  a  variety  of  compounds, 
among  which  is  the  fulmmate  of  mercury ;  and,  further,  for  various  purposes  in  chemical 
and  physical  laboratories.  More  recently,  an  amalgam  of  mercury  and  sodium  has  been 
veiy  successfully  used  by  Bir.  Grookes  in  the  metallurgical  extraction  of  silver  and  gold ; 
tod  a  solidified  amalgam  of  the  same  metals  is  recommended  to  facilitate  the  transport 
of  mercury,  the  amalgam  admitting  of  being  very  readily  decomposed  by  treating  with 
dilute  sulphuric  acid.  « 

Prepajutions  op  Mercuby. 

Mttevtat  oompoandi.  The  moTB  important  mercurial  compounds  which  are  manufac- 
tured on  the  large  scale  are  the  following : — 

Mamie  oiiioiide.  The  substauce  commonly  known  as  corrosive-sublimate  is  the  per- 
chloride  of  mercnry,  HgCl,  equivalent  =135^  consisting,  in  100  parts,  of  73 '8  parts  of 
mercury  and  26' 2  parts  of  chlorine.  It  is  prepared  either  by  sublimation  from  a 
mixture  of  sulphate  of  peroxide  (red  oxide)  of  mercury  and  common  salt,  or  by  dis- 
solving the  same  oxide  in  hydrochloric  acid,  and  also  by  boiling  a  solution  of 
chloride  of  magnesium  with  the  peroxide  (MgCl«-(-HgO=HCl-(-MgO)'.  When 
fmblimed,  this  salt  forms  a  white  crystalline  mass,  which  fuses  at  260°,  boils  at  290% 
is  soluble  in  13*5  parts  of  water  at  20°,  and  in  1*85  parts  of  the  same  liquid  at  loo^ 
It  is  more  readily  dissolved  by  alcohol,  i  part  of  the  salt  requiring  only  23  parts  of 
cold  and  1*18  parts  of  boiling  alcohol.  Mercuric-chloride  has  been  industrially 
employed  as  a  preservative  for  timber  by  Mr.  Eyan,  and  is  used  in  the  manufacture  of 
tniline-red,  in  dyeing,  and  calico-printing,  in  etching  on  steel-plates,  and  for  the 
preparation  of  other  mercurial  salts.  Lately,  the  use  of  the  double  salt,  HgGla,2KGl, 
obtained  by  boiling  chloride  of  potassium  with  peroxide  of  mercury,  has  been  sug- 
gested as  a  preservative  for  timber.  It  should  be  borne  in  mind  that  this  preparation 
of  mercury  is  extremely  poisonous  and  easily  absorbed  by  the  skin  of  the  hands. 
oaaaim.  Under  this  name  is  designated  the  mercuric-sulphide,  HgS,  which  occurs 
native  in  crystalline  or  compact  red-coloured  masses,  and  was  known  in  Pliny's 
time  by  the  term  minium.*  The  cinnabar,  or  vermillion  of  commerce,  used  as  a 
pigment,  is  always  artificially  prepared  either  by  the  dry  or  wet  way.  By  the  former 
process  540  parts  of  mercury  and  75  of  sulphur  are  very  intimately  mixed.    The 

*  Bed-lead,  afterwards  called  minium,    was,  as  far  as  it  appears,  unknown  to  the 
tfkcients,  being  first  prepared  by  the  Arabs  and  Saracens. 


92  CHEMICAL   TECHNOLOGY. 

eiLEniiiig  blaok-oolonred  powder  is  introduoed  into  iron  veseels,  and  exposed  to  a 
moderate  heat  so  as  to  cause  the  fusion  of  the  mass,  which,  after  cooling,  is  broken 
up  and  then  introduced  into  earthenware  and  loosely  closed  vessels,  heated  on  a 
sand-batii.  The  sublimed  mass  is  of  a  cochineal-red  colour,  exhibits  a  fibrous 
fracture,  and  yields  when  pulyerised  a  scarlet  powder,  which  is  the  more  beautifal 
the  purer  the  materials  used  in  its  preparation  and  the  greater  the  care  taken  to  avoid 
an  excess  of  sulphur.  Some  chemists  allege  that  a  greatly  improved  veimillion  is 
obtaiued  if  i  part  of  sulphuret  of  antimony  is  added  to  the  mixture  of  sulphur  and 
mercury  previously  to  the  sublimation,  and  the  sublimed  and  pulverised  mass  placed 
in  a  dark  room  for  several  months  and  treated  with  either  dilute  nitric  acid  or  oaustic 
potassa.  According  to  Dr.  J.  von  Liebig,  vermillion  is  obtained  in  the  wet  prooees 
by  treating  the  white  precipitate  of  the  pharmacopoeia,  or  hydrargyrum  amidato 
Mchloratumf  according  to  the  formula,  HgGl,HgNHs,  which  corresponds  to  the  term 
used,  but  in  Dr.  A.  W.  Hofmann's  opinion,  does  not  express  the  true  composition  of 
the  compound.  He  considers  white  precipitate  to  be  a  chloride  of  ammonium,  in  the 
ammonium  of  which  2  equivalents  of  mercury  have  taken  the  place  of  2  equivalents  of 

TT*        Other  chemists,  again,  hold  different  views  as  to  the 

constitution  of  this  body,  which  has  been  used  in  medicine  since,  if  not  before,  the 
time  of  Paracelsus.  Vermillion  is  generally  obtained  by  precipitating  a  solution  of 
corrosive  sublimate  in  ammonia  with  a  solution  of  eulphiir  in  sulphide  of  ammonium ; 
or,  according  to  Dr.  von  Martins,  by  agitating,  in  a  suitable  vessel,  i  part  of 
sulphur,  7  of  mercury,  and  2  to  3  of  a  concentrated  solution  of  liver  of  sulphixr. 
According  to  M.  Brunner's  method,  by  which  decidedly  the  finest  vermillion  is 
obtained,  114  parts  by  weight  of  sulphur  and  300  parts  by  weight  of  mercury  are 
mixed,  with  the  addition  of  a  small  quantity  of  caustic  potassa  solution,  and  incorpo- 
rated by  being  shaken  by  machinery.  The  resulting  black  compound  is  next  treated 
with  a  solution  of  75  parts  caustic  potassa  in  400  parts  of  water,  and  heated  on  a 
water-bath  to  45°.  The  mixture  assumes  a  scarlet-colour  after  a  few  hours,  and  as 
soon  as  this  is  apparent  the  semi-liquid  mass  is  poured  iato  cold  water,  next  collected 
on  filters,  washed,  and  dried.  The  vemullion  of  commerce  is  often  adulterated  with 
red-lead,  peroxide  of  iron,  chrome-lead,  and  more  frequently  with  firom  15  to  20  per 
cent  of  gypsum.  These  adulterations  are,  however,  readily  detected,  as  they  are  left 
behind  when  the  vermillion  is  sublimed.  Red-lead,  one  of  the  most  usual  adultera- 
tions of  vermillion,  can  be  readily  detected  either  by  treating  a  small  quantity  of  the 
suspected  sample  with  nitric  acid,  when  in  consequence  of  the  formation  of  puce- 
coloured  peroxide  of  lead,  the  mass  assumes  a  brown  colour,  or  by  the  addition  of 
hydrochloric  acid,  when  chlorine  is  given  oflf.  Pure  cinnabar  is  completely  and 
readily  soluble  in  hydrosulphuret  of  sulphide  of  sodium  (NaSH). 

FaiminAting  Marearr.      The  oompound  known  as  fulminating  mercury  is  a  combination  of . 
fulminic  acid,  an  acid  unknown  in  a  free  state,  and  of  oxide  of  mercury ;  its  formula  may 
be  written  GaHgaNaOa.    In  100  parte  it  consists  of  77*06  of  peroxide  of  mercury  and 
23'94  of  fulminic  acid.    According  to  the  late  Br.  Gerhardt^s  view,  this  body  is  a  nitro- 
compound which  may  be  regarded  as  cyan-methyl,  the  hydrogen  of  the  me&yl  of  which 

hasbeenreplaced  by  hyponitrio  acid  and  mercury ;  the  formulais  then :  C  |  S5*  |  ,CN.    This 

substance  was  first  discovered  by  Mr.  Howard,  and  was  known,  until  Dr.  von  Liebig  gave 
the  clue  to  its  nature,  as  Howard^s  detonating  powder.  It  is  prepared  on  a  large  scale  in 
the  following  manner.  First,  2  lbs.  of  mercury  are  dissolved,  by  the  aid  of  a  gentle  heat, 
in  ro  lbs.  of  nitric  acid  (sp.  gr.  1-33),  and  10  lbs.  more  of  nitric  acid  are  then  added.  The 
resulting  fluid  is  poured  into  six  tubulated  retorts,  and  to  the  contents  of  each  retort  is 


PREPARATIONS  OF  MERCURY.  93 

added  10  litres  of  alcohol  (ap.  gr.  0*833).  I'  ^^^  ixigredients  are  mixed  by  measure  instead 
of  weight,  for  every  volome  of  mercury,  there  is  taken  7^  volumes  of  nitric  acid,  and 
10  volumes  of  alcohol.  After  a  few  minutes  a  strong  evolution  of  gas  takes  place,  and  at 
the  same  time  a  white  precipitate,  the  fulminate  of  mercury,  is  formed.  The  retorts  are 
fitted  with  tubulated  receivers,  from  which  glass  tubes  carry  off  the  very  poisonous  gas 
and  fumes,  either  to  a  flue  or  directly  to  the  outside  of  the  shed  in  which  the  operation  is 
performed.  The  precipitate  is  collected  on  Alters,  and  washed  with  cold  water  to 
eliminate  the  free  acid.  The  fulminate  is  next  dried,  filtered,  and  all  being  placed  on 
plates  of  copper  or  earthenware,  heated  by  steam  to  less  than  100^.  100  parts  of  mercury 
yield  in  practice  from  118  to  128  parts  of  fulminate,  while,  according  to  theory, 
142  should  be  obtained.  The  dried  fulminate  is,  with  caulious  manipulation,  divided  into 
flnall  portions,  kept  separately  in  a  paper  bag.  The  fulminate  thus  prepared  is  a  crystal- 
lioe  white-coloured  substance,  which,  by  being  heated  to  186°,  or  by  a  smart  blow,  explodes 
with  a  loud  report.  When  placed  on  iron  and  struck  with  an  iron  instrument,  the 
detonation  is  much  increased.  This  substance  also  explodes  by  contact  with  concentrated 
sulphuric  acid.  When  mixed  with  30  per  cent  of  its  weight  of  water,  the  crystallina 
fulminate  may  be  rubbed  to  powder  with  a  wooden  pestle  on  a  marble  slab.  The  manu- 
laoture  of  this  substance  on  a  large  scale  requires  peculiar  arrangements,  into  the  particu- 
lars of  which  we  cannot  here  enter. 
peRudon-OBpii.  The  fulminate  of  mercury  is  chiefly  used  for  filling  percussion-caps. 
For  this  purpose  100  parts  of  the  fulminate  are  rubbed  to  powder  with  30  parts  of  water, 
50  to  62-5  parts  of  saltpetre,  and  29  of  sulphur.  This  mixture  is  dried  sufficiently  to 
admit  of  being  granulated,  after  which  it  is  forced,  by  means  of  machinery,  into  the 
copper  caps,  and  simultaneously  covered  with  either  a  layer  of  varnish  or  tin-foil,  to 
protect  it  from  damp.  Tin-foil  being  more  expensive  is  not  used  for  military  gun-caps. 
The  best  varnish  for  the  purpose  is  a  solution  of  mastic  in  oil  of  turpentine.  The  caps 
are  finally  dried  by  a  gentle  heat,  and  packed  in  boxes.  One  kilogramme  of  mercury 
eonverted  into  fulminate  suffices  for  the  fiUing  of  .40,000  gun-caps  of  the  larger  or  military 
size,  and  for  57,600  caps  of  the  size  used  by  sportsmen. 

Platinum. 
(Pt=i97*4;  Sp.  gr.=3i'o  to  230). 

oecanvDeeofFifttiBim.  This  metal  IB  Only  found  native,  and  then  not  very  abundantly, 
in  platiQum  ore,  more  especially  met  with  in  the  alluvial  deposits  of  South  America 
and  the  Oural,  in  grains  of  a  steel-grey  colour  and  metallic  lustre.  More  recently, 
granules  of  metaUic  pladnum  have  been  found  among  the  gold- washings  in  Galifomia, 
the  Brazils,  Haiti,  Australia,  and  Borneo.  A  very  short  time  ago  this  metal  was 
discovered  in  Europe,  interspersed  in  rocks  situated  in  the  parish  of  Koeraas,  in 
Norway,  and  it  is  reported  to  have  been  found  in  the  lead-mines  near  Ibbinburen,  in 
Westphalia.  Dr.  Pettenkofer  states  that  a  proof  of  the  for  greater  dispersion  of 
platiaum  than  is  generally  supposed  lies  in  the  fact  that  all  silver  contaias  a 
small  quantity  of  platinum.  The  metal  has  also  been  found  to  accompany  some  of 
the  copper  and  antimony  ores  of  Timor  and  New  Guinea.  Platinum  was  disoovered 
in  South  America  by  the  Spaniards,  who,  believing  it  to  be  an  inferior  silver,  gave  it  the 
diminutive  j)2atina  of  the  Spanish  name  for  silver,  plata.  It  was  brought  firom 
Jamaica  and  made  known  in  Europe  by  a  Mr.  Wood  in  1740,  and  somewhat  investi- 
gated in  1767  by  Dr.  R.  Watson,  then  Professor  of  Chemistry  at  Cambridge. 
Br.  Scheffer,  Director  of  the  Mint  at  Stockholm,  was  the  first  who  thoroughly  inves- 
tigated the  various  physical  and  chemical  properties  of  this  metal  in  1752 ;  but  as  hia 
researches  were  published  in  the  Swedish  language,  they  remained  comparatively 
unknown  in  this  country. 

iiiiiBaiii  orw.  The  substanoG  met  with  in  commerce  under  the  name  of  platinum  ore, 
or  crude  platinum,  is  a  mixture  of  a  variety  of  metals,  among  which  the  following 
predominate: — ^Platinum,  palladium,  rhodium,  iridium,  osmium,  ruthenium,  iron, 
copper,  lead,    and  frequently   granules   of   osm-iridium,  gold,   chrome-iron   ore, 


94  CHEMICAL   TECHNOLOGY. 

titaniTim-iron  ore,  spinel,  zircon,  and  quartz.  The  reason  why  this  ore  is  found  in 
alluvial  soil  is,  that  the  rocks  originally  containing  the  ore  having  heen  disintegrated 
by  water,  it  is  carried  off  by  the  streams  and  water-courses.  Boussingault  found, 
when  travelling  in  South  America,  a  seam  of  somewhat  weathered  syenite  containing 
the  platinum  ore  yet  in  situ ;  while,  as  regards  the  Oural,  it  has  been  proved  by 
Pallas  that  the  ore  was  originally  imbedded  in  serpentine-rock  which  has  been 
washed  away  by  water,  the  water,  however,  leaving  such  minerals  as  chrome-iron 
ore,  zircon,  titanium-iron  ore,  &c.  In  the  Island  of  Borneo,  platinum  ore  is  mixed 
with  sesqui-sulphuret  of  ruthenium,  a  mineral  which  has  been  named  by  Dr.  Wohler 
(1866)  Laurite. 

The  compoBition  of  some  platinum  ores  is  exhibited  in  the  following  table : — ^Analysed 
by  Dr.  Berzelius,  a,  ore  from  the  Onral ;  Dr.  Svanberg,  5  and  e,  from  Columbia  and 
dhooo;  Dr.  Bleekxode,  <2,  from  Borneo;  Dr.  Weil,  e,  from  Calif omia. 

a.  b,  c.  d,  e. 

Platinum 86*50  84*30  86- 16  71*87  5775 

Bhodium 1*15  3*46  2*16  —  2*45 

Iridium      —  1*46  I'og  7*92  3*10 

Palladium 1*10  z*o6  0*35  1*28  0*25 

Osmium —  1*03  0-97  0*48  o-8i 

Osm-iridium     ..     ..  1*14  —  1-91  8*43  27*65 

Copper       o*45  0*74  0*40  0*43  0*20 

Iron 8*32  5*31  8*03] 

Lime -—  0*12  —    •  8*40  7*70 

Quartz        —  o'6o  —  ) 

Aooording  to  Dr.  H.  Deville,  the  average  quantity  of  platinum  contained  in  the  fol- 
lowing ores  is: — 

Columbia 76*80 — 86*20  per  cent 

Calif  omia 76*50 — 85*50 

Oregon . .  50*45 

Australia 59*8o — 61*40 

Siberia      73'5o — 78*90        „ 

Borneo      5775— 70*21.      „ 

The  annual  production  of  metallic  platinum  amounts  to  from  35  to  50  cwts.,  of  which 
quantity  the  Oural  yields  28  to  49  cwts.,  Columbia  and  the  Brazils,  6  to  8  cwts. 

woiiMton's  Method  of  The  mcthod  originally  devised  by  the  late  Dr.  Wollaston,  and 
^  from  iSi  Ore*.  still  employed  by  the  Parisian  platinimi-makers,  Ghapuis,  Desmoutis, 
and  Quennessen,  is  as  follows : — The  ore  is  first  treated  with  cold  aqua  regia  to 
dissolve  any  gold,  and  the  liquid  separated  from  the  ore  by  filtration.  The  mineral 
is  again  treated  with  aqua  regia  in  a  retort,  and  heat  applied ;  the  distillate  contains 
osmic  acid,  and  the  insoluble  residue  in  the  retort  osm-iridium,  ruthenium, 
chrome-iron  ore,  and  titanium-iron  ore.  The  acid  liquid  contains  palladium, 
platinum,  rhodium,  and  some  iridiimi,  in  solution,  and  the  acid  having  been  neutral- 
ised with  carbonate  of  soda,  the  fluid  is  mixed  with  cya^oide  of  mercury,  whereby 
palladium  is  separated  as  cyanide  of  palladium.  That  precipitate  having  been 
removed  by  filtration,  the  liquid,  diluted  with  water,  is  next  concentrated  by  evapo- 
ration, and  then  mixed  with  a  concentrated  solution  of  chloride  of  ammonium,  the 
mixture  resulting  in  a  precipitate  (PtCl4,2NH4Cl),  of  the  double  chloride  of  platinum 
and  ammonium,  containing  only  a  trace  of  iridium,  which,  as  it  imparts  greater 
hardness  to  platinum,  is  not  injurious.  The  platinum  sal-ammoniac,  as  the  precipi- 
tate is  industrially  named,  is  first  dried  and  afterwards  ignited,  leaving  spongy 
platinum,  which  is  forced  by  means  of  properly  fitting  pistons  into  steel  tubes  heated 
to  redness,  the  operation  being  repeated  as  often  as  is  required  to  obtain  the  metal 
in  a  compact  coherent  state.    According  to  MM.  Descotil  and  Hess,  platinum  ores 


II 


PREPARATIONS  OF  MERCURY.  95 

should  be  first  fdsed  with  from  2  to  4  times  their  weight  of  zinc,  the  cooled  brittle 
mass  pulverised,  and  treated  with  dilute  sulphuric  acid  to  eliminate  some  of  the  iron 
and  zioc ;  the  remaining  substance  is  then  treated  with  nitric  acid,  which  dissolves 
the  rest  of  the  iron,  copper,  and  lead.  The  ore  is  afterwards  treated  with  aqua 
r^ia,  which  acts  more  readily  on  account  of  the  fine  state  of  division  of  the  mineral. 
M.  Jeannetty  (Paris)  found  that  platinum  becomes  readily  fusible  by  the  addition  of 
metallic  arsenic,  which  is  afterwards  volatilised. 

*  mSmSS?"*  '^^^  excellent  method  introduced  by  MM.  Deville  and  Debray,  in 
1859,  is  based  upon  the  fact  that  metallic  lead,  while  fusing  with  platinum  ore, 
dissolves  all  the  foreign  metals,  osm-iridium  alone  excepted.  The  platinum  ore  is  conse- 
quently placed  on  the  hearth  of  a  reverberatory  furnace,  and,  having  been  mixed 
with  its  own  weight  of  galena,  a  regulus  is  ohtained,  under  which  the  osm-iridium 
is  left,  while  a  lead  slag  floats  on  the  top,  the  iron  decomposing  a  portion  of  the 
galena  and  producing  metallic  lead.  The  regulus  is  heated  in  a  cupel  furnace, 
Thereby  all  foreign  metals  are  volatilised  or  absorbed  as  oxides,  leaving  the  metallic 
phtinum,  which  is  refined  by  being  again  melted  in  crucibles  made  of  lime,  which 
absorbs  and  eliminates  all  impurities,  such  as  silicium,  iron,  copper,  &c.  The  fuel 
used  for  this  purpose  is  coal-gas,  the  combustion  being  kept  up  by  means  of  oxygen. 
The  smelting  of  i  kilo,  of  platinum  requires  100  litres  of  oxygen  gas  and  300  litres  of 
ooal-gas.  The  firm  of  Messrs.  Johnson,  Matthey,  and  Co.,  the  most  eminent  and 
extensive  platinum  smiths  in  the  world,  exhibited  at  the  International  Exhibition 
of  1862  an  ingot  of  pure  platinimi  weighing  no  less  than  2i  cwts.,  valued  at  ^4000, 
smelted  by  the  method  of  MM.  Deville  and  Debray.  The  molten  platinum  is  after- 
wards submitted  to  the  action  of  a  steam-hammer  to  render  it  dense,  solid,  and  fully 
malleable. 

ftopvtiMof  FiKUnnm.  Thls  metal  is  nearly  as  white  as  silver,  but  with  a  steel-grey  shade. 
It  exhibits  considerable  lustre ;  is  very  malleable  and  ductile,  and  so  soft  that  it  readily 
admits  of  being  cut  with  a  pair  of  scissors.  It  may  be  drawn  in  wire  thinner  than  a 
spiders' -web,  an  operation  conducted  by  coating  an  already  thin  platinum  wire  with 
ttlver.  The  wire  thus  prepared  is  drawn  out  and  the  silver  afterwards  removed  by  nitric 
add,  which  dissolves  that  metal  but  leaves  the  platinum.  The  specific  gravity  of 
platinum  varies  from  21*0  to  23*0.  This  metal  admits  of  being  welded  at  a  white  heat, 
and  may  be  melted  by  the  oxyhydrogen  flame,  its  melting-point,  according  to  Dr.  Deville, 
Wmg  between  1460°  to  1480**.  Platinum  occurs  in  commerce  as  spongy  platinum, 
black  platinum,  forged  or  hanmiered  and  cast  platinum. 

BMkrtetiniaii.       Black  and  spongy  platinum  possess  the  property  of  absorbing  and  con- 
^  spangy  PtoUnam.  deusing  large  quantity  of  gases,  more  especially  oxygen.  If  a  jet  of  hydrogen 
is  directed  upon  the  spongy  metal,  black  platinum  being  only  an  exceedingly  finely  divided 
•pongy  platinum,  the  gas  combines  with  the  oxygen  absorbed  by  the  meted,  forming  water ; 
and  this  combination  is  attended  with  so  great  a  development  of  heat  that  the  platinum 
becomes  red-hot  and  causes  the  ignition  of  the  hydrogen.    It  is  upon  this  property  that 
the  well  known  Ddbereiner  lamp  is  based.    Black  platinum  is  prepared  either  by  boiling 
solphate  of  platinum  with  carbonate  of  soda  and  sugar,  when  the  black  platinum  is  pre- 
cipitated as  a  veiy  fine  powder,  or  by  melting  platinum  and  zinc  together,  and  treating 
the  alloy  with  dilute  sulphuric  acid.     Black  platinum  is  industrially  employed  in  the 
manufacture  of  vinegar  directly  from  alcohol. 
I     ^23?'**'  ^*iS'      Platinum  may  be  worked  by  hammering  or  by  casting.    The  following 
^  I        Ap^MiSanM.      firms  are  platinum  workers : — Heraeus,  at  Hanau ;  Freres  Chapuis ;  Des- 
^     numtis  and  Qnennessen,Godart  and  Labordenave,  at  Paris ;  and  Messrs.  Johnson,  Matthey, 
^     and  Ck).,  London.    The  chief  use  of  platinum  is  for  various  apparatus  in  chemical 
laboratories.      Although  this  metal  withstands  a  veiy  high  temperature,  and  is  proof 
^      against  a  large  number  of  chemicals  which  attack  or  destroy  other  materials,  it  requires 
^     great  care  in  its  use,  as  it^is  readily  acted  upon  by  caustic  alkalies,  fusing  nitrate  of 
I     potassa,  free   chlorine,  alkaline   sulphnrets,  phosphorus,  molten  metals,  and  readily 
reducible  metallic  oxides.    Crucibles,  spoons,  blowpipe  points,  the  points  of  lightning  con- 
EM    duetors,  tongs  and  forceps,  and  boilers  for  concentrating  sulphuric  acid  are  made  of  this 


g6  CHEMICAL  TECHNOLOGY. 

metal.  A  boiler  capable  of  concentrating  dally  8  tons  of  snlphnric  acid  costs  about  £2500, 
while  a  smaller  bnt  similar  vessel  for  concentrating  daily  5  tons  of  acid  costs  £1640,  the 
Talne  of  the  metallic  platinom  for  this  size  exceeding  £1000.  Platinum  is  also  used  for 
galyanic  apparatus,  mustard-spoons,  and  now  and  then  for  ornamental  work  in  watch- 
oases,  chains,  &o.  More  recently  platinum  has  been  used  in  porcelain  staining  to  produoe 
a  greyish  hue.  In  the  year  1828,  the  Bussian  Govemment  commenced  coining  platinnxn, 
3,  6,  and  12  rouble  pieces ;  but  by  a  ukase  of  22nd  June,  1845,  ^^^  coinage  was  dia- 
continued,  and  the  money  made,  14,250  kilos,  in  weight,  called  in.  In  France,  pla- 
tinum is  used  for  making  medals,  especially  prize  medals  for  exhibitions.  The  first 
platinum  coin  CTcr  made  was  struck  at  the  Paris  Mint  in  1799,  the  dies  having  been 
engraved  by  M.  Duvivier  with  the  effigy  of  the  first  Consul,  afterwards  Napoleon  I.  In  the 
year  1788,  there  was  presented  to  Louis  XVI.  a  watch,  some  of  the  works  of  which  were 
made  of  platinum.  Small  caps  or  cylinders  woven  in  platinum  wire,  are  used  to  emit 
light  when  rendered  highly  incandescent  by  the  flame  of  burning  hydrogen,  the  arrange- 
ment being  termed  a  platinum  gas  lamp.  According  to  M.  Kraut,  platinum  frequently 
contains  barium,  or  a  combination  of  that  metal. 

naUnmn  Aiioyi.  As  before  observed  platinum  readily  alloys  with  other  metals.  Among  these 
alloys,  that  first  made  by  Deville,  consisting  of  787  platinum  and  21*3  iridium,  especially 
deserves  notice,  as  it  is  not  acted  upon  by  nitro-muriatio  acid,  and  is  hard  and  malleable. 
An  alloy  of  platinum  containing  10  to  15  per  cent  of  iridium  withstands  fire  and  reagents 
far  better  than  platinum  alone  and  is  harder ;  hence  the  vessels  made  with  it  are  not  so 
liable  to  be  bent  out  of  shape  as  those  of  platinum.  According  to  M.  Chapuis,  an  alloy  of 
92  parts  of  platinum,  with  5  parts  of  iridium,  and  3  parts  of  rhodium,  resists  various 
reagents  better  than  platinum  alone.  The  aUoy  of  3  parts  of  platinum  with  13  parts 
of  copper  is,  according  to  M.  Bolzani,  equal  in  all  respects  to  gold.  Dr.  Percy  states  that 
an  alloy  of  platinum  and  gold  for  crucibles  and  other  small  vessels  applied  in  chemical 
operations,  is  best  proof  against  alkalies.  An  aUoy  of  eqnal  parts  by  weight  of  steel  and 
platinnm  is  the  best  white  speculum-alloy  known ;  its  sp.  gr.  —  9*862. 

Biayi  PiatioiHiiiiorida.  This  compound  (PtOjH^Cla),  is  obtained  by  repeatedly  dissolving 
chloride  of  platinum  in  alcohol,  and  evaporatmg  the  solution  to  dryness.  A  very  dilate 
solution  when  heated  on  a  sheet  of  glass  or  a  porcelain  slate,  yields  a  lustrous  coating  of 
platinum. 

SiLVEB. 

(Ag  =  108 ;  Sp.  gr.  =  10-5  to  107.) 

siiYtf  and  its  oocurenee.  Silver  is  a  tolerably  abundant  metal,  and  is  found  partly  in  the 
native  metallic  state,  aJmost  always  containing  gold;  partly  in  combination  with 
other  metals,  as  arsenic,  antimony,  tellurium,  mercury,  or  combined  with  sulphur  and 
other  Billphurets.  Silver  rarely  occurs  as  oxide  or  combined  with  acids.  The  chief 
ores  are : — The  sulphuret,  silver-glance  (Ag^S),  containing  from  84  to  86  per  cent  of 
silver;  the  dark-coloured  ruby  ore  (3AgaS-(-Sb:^S3),  with  58  to  59  per  cent  of  silver ; 
the  light-coloured  ruby  ore  (3AgaS+AsaS3),  with  64  to  64*5  per  cent  of  silver;  miar- 
gyrite  (AgaS-f-Sb^Ss) ;  and  the  brittle  antimonial  silver  ore  (6AgaSb2Ss),  with  about 
67  to  68  per  cent  of  silver;  polybasite  [(AgaS,Cu2S)9,Sb2S3],  with  64  to  726  per 
cent  of  silver;  and  the  white  ore  L(FeS,ZnS,CuaS)4,SbaS3+(PbS,AgS)4,SbaS3],  with 
30  to  32*69  per  cent  of  silver.  Galena  frequently  contains  silver,  usually  between 
00 1  and  0*03  per  cent,  and  sometimes  as  much  as  c 5  to  I'o  per  cent. .  This  lead  ore 
is  the  chief  source  of  the  silver  produced  in  the  United  Eongdom.  Some  copper  ores 
contain  silver  to  an  amount  varying  from  0*020  to  1*101  per  cent.  With  regard  to 
line  ore  the  reader  is  referred  to  the  statements  under  that  head. 

■xtnusUon  of  sfiTw      ^0  metallurgical  process  employed  in  the  extraction  of  alver  may  be 

tnm  lU  Ores.         fl.ny  of  the  following : — 

I.  By  the  wet  way. 

z.  By  the  aid  of  mercury. 

a.  European  method  of  amalgamation. 
h.  American  method  of  amalgamation. 
2.  By  means  of  solution  followed  by  precipitation, 
a.  Augnstine's  method. 
h,  ZiervogePs  method, 
e.  Sundry  methods. 


SILVER.  97 

n.  ^y  the  dry  way. 

z.  By  ooncentratiiig  lead  ores  rich  in  fiilver. 
2.  Separation  of  the  silyer  from  the  lead. 

a.  Separation  on  the  hearth. 

b.  Conoentrating  the  BilTer  in  the  lead  by  Pattinson*B  method, 
e.  Eliminating  the  ailver  from  the  lead  by  means  of  zino. 

d.  Befining  the  sUyer-glanoe. 

ftMittagforaiiTvDinetiy.  I.  It  Only  rarely  happens  that  silver  ores  are  rich  enough  to 
tdmit  of  the  metal  being  obtained  by  a  direct  smelting  process. 

***'l2ISir5Sf  ^^  ^-  T^®  method  of  obtaining  silver  by  the  aid  of  mercury,  or  the 
amalgamation  process,  is  chiefly  applied  to  very  poor  ores,  and  to  such  metallurgical 
products  as  contain  only  loo  to  120  grms.  of  silver  to  the  metrical  cwt. 

^^**'9mnJ^ajpmaatm  jhig  process — ^uow  obsoleto — ^was  conducted  in  four  principal 
operations — ^viz.,  i.  The  roasting ;  2.  Amalgamation ;  3.  Separation  of  excess  of 
meienry  from  the  amalgam  by  mechanical  means ;  4.  Volatilisation  of  the  mercury. 
There  was  first  added  to  the  ores  about  10  per  cent  of  common  salt,  and  the  mixture 
roasted  to  volatilise  the  antimony,  arsenic,  and  other  volatile  minerals,  the  fumes 
bemg  condensed  in  properly  arranged  rooms.  By  the  reaction  of  the  common  salt 
upon  the  pyrites,  converted  by  the  roasting  into  sulphate  of  iron,  there  is  formed 
solphate  of  soda,  chloride  of  iron,  and  sulphurous  add  which  escapes.  The  chloride 
of  iron  exchanges  its  chlorine  with  the  silver,  the  result  being  the  formation  of  per- 
oxide of  iron.  There  are  also  formed  sulphate  of  copper  and  persulphate  of  iron, 
wbieli,  while  oxidising  any  sulphuret  of  silver  to  sulphate,  become  reduced  to  proto- 
aolphates.  By  the  further  action  of  the  common  salt,  chloride  of  silver  and  sul- 
pbste  of  soda  are  formed,  and  the  other  metals  converted  into  chlorides.  The 
Viown-coloured  mass  is  next  transferred  to  the  amalgamation  tuns;  and  after 
the  addition  of  water,  mercury,  and  iron,  these  tuns  are  made  to  rotate  on  their 
loDgitadinal  axes  for  a  period  of  16  to  18  hours,  the  velocity  being  regulated  to  20  to 
22  revolutions  per  minute.  The  iron  while  combining  with  the  chlorine,  causes  the 
lednction  of  all  the  other  metals  to  the  metallic  state,  and  as  far  as  capable  these 
then  form  an  amalgam  with  mercury. 

In  order  to  elucidate  the  amalgamation  process  we  will,  for  example,  take  a  silver  ore  to 
eouutof— 

(CUaS,AgB,FeB)  +  (AflaSa.SbaSa). 

from  which  the  silver  is  to  be  separated,  according  to  the  method  just  described.*  After 
the  roasting  with  common  salt  (ClNa),  there  being  taken  up  in  this  instance  30  mole. 
^  oxygen,  the  following  substances  are  formed : — 

[(OuaCla^AgCl,FeCla)  +  3Naa804]  +  [AsaOa+SbaOj+eSOa] , 

' » '  ^ , ' 

Non-volatile  substances.  YolatiliBed  substances. 

Th«  ohanges  which  are  effected  by  the  action  of  the  iron,  mercury,  and  water  in  the  amal- 
9aiation  tuns  are  exhibited  by : — 

[(CoaCl«,AgCl,FeCla) +3NaaS04+3Pe+nHg=3NaaS04+  (Cn,Ag,nHg) +4^eOU. 

At  the  end  of  the  period  destined  for  the  rotation  of  the  tuns,  the  amalgam  is  run 
^  The  excess  of  mercury  is  strained  through  a  coarse  canvas  bag,  and  collected 
in  a  stone  trough  or  tank.    The  real  amalgam,  a  thick  pasty  mass,  remains  in  the 

*  No  attention  is  paid  in  this  case  to  the  volatile  chlorides  of  sulphmr,  arsenic,  and 
ntixiiQ]^  which  are  cdmultaneoudy  formed.  The  reader  who  desires  more  extensive 
tafoinuition  on  the  subject  here  bridly  outlined,  is  referred  to  Mr.  Crookes*8  **  Metallurgy,** 
'olL 


b8  chemical  TECHNOLOOr. 

bag,  which  is  next  strongly  pressed  between  planks  to  squeeze  out  taj  farther 
escesB  of  non'OrgentiBed  mercury.  The  solid  amalgam*  is  then  transferred  to  the 
iron  plates,  hb,  |Fig.  54),  &rraitged  as  Bhown  in  the  woodcut,  and  as  already  described 
under  the  article  Mercnry.  By  the  action  of  the  fire  the  mercury  is  separated  from 
the  amalgam,  and  being  volatilised,  is  collected  under  the  water  contained  in  d, 
while  the  metallic  silver  and  other  metals  mixed  with  it  are  left  on  the  iron  plales.t 
Fio.  54. 


At  the  present  time  instead  of  the  above  contnianee  there  is  used  an  iron  distil- 
ling apparatus,  not  unlike  cylindrical  iron  gas  retorts  one  end  being  fitted  with 
a  movable  lid  for  the  introdnctioB  of  the  amalgam  and  the  other  end  connected 
with  an  iron  tube  which  dips  into  a  trough  filled  with  water  to  condense  the 
volatiliBed  mercnry  Superheated  steam  ig  also  advantageously  used  to  sepante  the 
mercury  from  the  amalgam  The  crude  silver  left  after  the  separation  of  the  mer- 
cury is  submitted  to  a  first  refining  smelting  by  being  put  into  graphite  cmcibles, 
and  the  surface  covered  with  charcoal  powder  But  even  after  this  smelting  the 
silver  always  contains  a  certain  quantitf  of  copper,  from  which  it  can  only  be  separated 
by  refining  in  a  oupel  furnace. 

j-yH—  Aiui(uutit>ii       l^e  American  proaesa  is  chiefly  naed  in  Meiioo,  Fern,  Chili,  and 

Fn>°~L  California.    The  ores  to  whtcli  it  i>  generally  applied  are  the  rabj- 

silver  oree  and  fahl  ores.    These  aie  first  pnlvsrised  in  (tamping  mills,  and  are  neit 


*  According  to  Dr.  Earaten,  the  composition  of  the  aoUd  wT"itiga'i'  is : — Silver,  ii'o;' 
mercnry,  S4'3  ;  copper,  3';  ;  lead,  O'l ;  lino,  o'3. 

f  The  silver  left  on  the  plates  at  the  Fieibrag  mines  oonnsts,  according  to  Protesur 
Lampadius,  of:— Silver,  75-0;  mercury, 07:  copper.zi'i;  lead,  1-5.  The  reflned  eilver 
of  the  »ame  place  contains,  according  to  ProleBsor  Plattner  : — Silver,  71-55  ;  oopper,  iS'Oi. 


-».  ' 


SILVEH.  \     .,    *  59 

• 
groimd  with  water  nnder  granite  or  porphyry  millstoneB,  to  a  thoroughly  impalpable  paste. 
Tide  niaterial  in  placed  in  a  yard  paved  with  flags,  which  are  laid  with  a  slight  inclination 
sufficient  to  cause  the  rain-water  to  run  off.  After  having  been  kept  there  for  some  days, 
there  is  added  from  i  to  3  per  cent  of  what  the  miners  locally  designate  as  magistral^ 
that  is  to  say,  roasted  iron  and  copper  pyrites  (FeCuS^),  which  is  thoroughly  mixed  with 
the  finely  divided  ore.  Mercury  is  then  added  in  quantity  equivalent  to  about  six  times 
the  amount  of  silver  contained  in  the  ore  ;  this  operation  is  termed  incorporation.  The 
kneading  of  the  mercury  is  continued  on  alternate  days  for  two  to  five  months,  and  after 
that  time  the  mass  is  washed  with  water  in  stone  cisterns  in  order  to  separate  the  heavy 
amalgam  from  the  light  gangue.  The  amalgam  thus  obtained  is  separated  from  any 
excess  of  mercury  by  being  pressed  in  canvas  bags  ;  the  remainder  of  the  mercury  being 
separated  by  distillation.  The,  rationale  of  this  amalgamation  process  is : — The  roasted 
copper-iron  pyrites  is  essentially  made  up  of  mixed  sulphates  of  copper  and  iron,  which, 
when  reacting  upon  the  common  salt,  are  converted  into  chlorides  of  the  metals  and  sulphate 
of  soda.  The  chlorides  acting  upon  the  silver  convert  it  into  chloride,  and  this  becoming 
dissolved  by  the  excess  of  salt,  is  converted  by  the  mercury  to  the  metallic  state.  Some  of 
the  mercury  is  converted  into  calomel,  and  the  excess  dissolves  the  silver,  becoming  amal- 
gamated with  it.  This  American  process  requires  a  great  length  of  time,  and,  moreover, 
occasions  an  enormous  loss  of  mercury,  as  for  every  mol.  of  silver  reduced  from  the  chloride 
of  that  metal  there  is  formed  i  mol.  of  calomel  (Hg2Cl2).  On  the  other  hand,  this  method 
admits  of  the  extraction  of  silver  from  ores  too  poor  to  be  treated  in  any  other  way, 
vhiie  a  great  saving  of  fuel  is  obtained. 

*^'^*'bx1^J£L'*'  This  hydrometallurgical  method,  invented  by  M.  Augastin,  is 
based  upon  the  formation  of  a  soluble  double  chloride  of  silver  and  sodium  when 
chloride  of  silver  is  treated  with  an  excess  of  a  warm  solution  of  common  salt,  and 
also  upon  the  fact  that  copper  is  capable  of  precipitating  all  tlie  silver  from  this 
solution.  The  ore  is  first  reduced  to  a  finely  divided  powder,  which  essentially  con- 
tains sulplmrets  of  copper,  silver,  and  iron.  This  powder  is  roasted,  first  without 
tlie  addition  of  common  salt,  witli  the  result  that  sulphates  of  the  metals  are  formed, 
and  excepting  that  of  silver,  again  decomposed  by  a  higher  temperature.  The  mass 
is  next  roasted  with  common  salt,  whereby  the  sulphate  of  sUver  is  converted  into 
chloride.  The  mass  is  then  treated  with  a  concentrated  hot  solution  of  common  salt, 
which  dissolves  the  chloride  of  silver,  and  from  this  solution  the  silver  is  precipitated 
by  metallic  copper,  which  becomes  chloride  of  copper,  and  is,  in  its  tmn,  precipitated 
by  metallic  iron. 

zioTogei'B  Method.  This  method  is  to  some  extent  similar  to  that  just  described,  but 
no  roasting  with  common  salt  takes  place.  The  roasted  ore,  chiefly  containing  as 
essential  ingredients  sulphate  of  copper  and  sulphate  of  silver,  is  treated  with  boiling 
water  to  dissolve  these  sulphates,  and  yield  a  solution  from  which  metallic  silver  is 
precipitated  bj  means  of  copper,  the  sulphate  of  that  metal  being  obtained  as  a 
by-product.  When  the  ores  happen  to  contain  arsenic  and  antimony,  this  method  is 
not  applicable,  as,  by  the  roasting,  arseniate  and  antimoniate  of  silver  are  formed, 
which  are  insoluble  in  water.  If  lead  is  present,  the  ore  becomes  fluxed  and  the 
roasting  a  far  more  difficult  matter. 

*5jjHyjOTirt^nj!icai  py.  Carl  Bitter  von  Hauer  suggests  the  treatment  of  the  ores 
sqt^.  as  in  tiie  European  amalgamation  process,  and  the  extraction  of 

the  chloride  of  silver  by  means  of  a  hyposulphite  of  soda  solution,  the  metallic  silver  being 
next  precipitated  by  the  aid  of  copper  or  tin.  Dr.  Patera  suggests  the  substitution  in 
AiigQstin's  method  of  a  hyposulphite  of  soda  solution  for  that  of  common  salt,  the  former 
being  more  manageable  and  applicable  cold.  Similar  suggestions  have  been  made  by 
I^.  Percy,  who  also  advocates  the  applicability  of  hypochlorite  of  lime,  and  of  chlorine  gas 
'or  converting  the  silver  into  chloride.  MM.  Rivero  and  Gmelin  were  the  first  to  suggest 
the  use  of  ammonia  for  the  purpose  of  extracting  and  dissolving  the  chloride  of  silver  f^ter 
^  ores  had  been  roasted  with  common  salt ;  the  precipitation  of  the  chloride  from  the 
ammoniacai  solution  by  means  of  sulphuric  acid,  and  the  smelting  of  the  chloride  with  a 
*nitable  flux  to  obtain  metallic  silver.  We  must  not  omit  to  mention  the  method  of 
extracting    silver   from  copper  regulus  and  mattes    by  means  of  hot  dilute   sulphurijs 

u  2 


100  CHEMICAL  TECHNOLOOY. 

add,  irliereby  the  noppv  it  dissolved  and  »  residae  left  oontaising  Oie  aQver,  whieli  ii 
fmilier  extracted  in  the  di?  vrty  b?  meonB  of  lead. 
suncum  oi  bu?k      The  method  of  eztiaatiug  Bilyer  from  its  ores  by  means  of  lead  ia  based 
bi  uu  eut  wii)r.    npon ; —  ^ 

I,  The  propeilT  of  lead  to  deoompou  fmlphimt  of  Hil7er,witlitltefonn«tionof  m^ibiirrt 
of  lead  and  metalUo  iUTer ;  ^  [  yield  |  ^f^ 

ABlead  hardly  acts  at  all  npon  the  other  metalUasolphidea,  and  least  of  all  upon  those  of 
copper  and  iion,  the  prodaete  of  the  amaltinf;  are  lead  combined  with  sUtbt,  and  a  regalnt 
conaistingof  the snlphnretB of  lead,  copper,  and  iron.  This  method  of  extraction  snoceads 
best  with  ores  containing  ss  small  a  qoantity  of  copper  as  possibte. 

3.  Upon  the  deoomposing  reaction  exerted  by  oxide  of  lead  and  solphate  of  lead  npon 
the  Bolphorat  of  mlrer,  in  oonseqaence  of  whiith  then  are'formed  metallic  lead  oontainiog 
silTer  and  sulphniouB  acid :- 


aPbO 


3.  Upon  the  rednoing ^ 

aPb    i  ^„,,   /PbO 


A&8    1  ^j   |PbA«, 
PbSO«r  y^"  laBO, 
of  lead  npon  oxide  of  silTec  or  upon  sulphate  of  d]*er :— 


U 


4.  upon  the  greater  iffini^  of  the  silTeT  tor  lead  than  for  copper.  If  copper  that 
contains  Bilver  is  melted  with  lead,  the  rwolt  is  the  formation  of  a  readily  fnsiUe  idloy  of 
lead  and  a  difficultly  fnsilde  alloy  of  copper  and  lead,  the  fonoer  metal  being  separahle  by 
hqaation. 
Nc^oiFnuLiiiiiihs  Only  genuine  silTer  ores  are  enbmitted  to  (lie  operation  of 
Haw.  smelting  with  lead,  but  these  ores  uauallj  contain  TuiaUa  proper- 

tions  of  copper,  lead,  cobalt,  sulphur,  and  other  anbatancea.    The  result  of  th« 


Fia.  55. 


smelting  with  lead  is  the  production  of  a  metal  containing  silver,  to  be  separttted  bj 
any  of  the  following  operations : — 

1.  On  the  refining-fomace ; 

2.  By  I^ttinson's  proeeea ; 

3.  By  means  of  zinc. 

laiBiBf  n«_.  This  operation  is  as  frequently  carried  on  at  laad-ore  smelting- works 
as  where  only  silTer  is  smelted.  The  ratUmaU  of  the  operation  is  that  lead  is 
readily  separated  from  such  metals  as  are  at  a  high  temperature  either  oxidisable  with 
ver;  great  difficult  or  not  at  .all ;  whereas  lead  oxidiaes  readily,  its  oxide  becoming 


SILVER.  tot 

ftdd.  But  it  is  requisite  that  the  oxide  of  lead  should  be  removed  or  absorbed  by  a 
snitable  medinm,  generally  the  porous  substance  composing  the  cupel  or  bottom  of 
the  hearth  of  the  refining  furnace.  The  operation  is  carried  on  as  long  as  any  oxide 
and  metallic  lead  remain,  so  that  only  the  silver  is  left.  This  operation  is  the  exact 
eoimterpart  on  the  large  scale  of  the,  well-  known  lead-silver  assay  carried  on  in  a 
muffle  with  bone-ash  cupels.  The  refining  furnace,  see  Fig.  55,  is  a  circular  rever* 
beratoiy  blast-fnmaoe.  The  hearth,  a,  is  covered  with  a  dome  of  stout  sheet-iron, 
lined  inside  with  fire-clay,  and  removable  by  means  of  a  crane,  d.  That  portion  of 
the  hearth  upon  which  the  smelting  is  earned  on  is  constructed  of  a  porous  sub- 
stance, generally  lixiviated  wood-ash  or  marl  of  good  quality.  The  cavity,  0,  is 
intended  for  collecting  the  silver;  b  is  the  space  for  the  flame.  In  the  circular  waU 
which  surrounds  the  hearth  there  are : — (i).  The  door,  not  exhibited  in  the  cut,  which 
represents  a  vertical  section  intended  for  the  discharge  of  the  molten  litharge.  At 
the  outset,  of  the  smelting  this  door  is  only  partly  closed  with  fire-clay  to  admit  of 
the  litharge  being  run  off.  The  furnace  is  charged  with  lead  to  a  little  above  the 
level  of  the  lower  sOl  of  this  door,  and  the  fire-clay  gradually  removed  as  the  level  of 
the  fiised  litharge  sinks.  (2) .  The  door,  p»  opposite  to  the  fire-place,  and  intended  for 
the  charging  and  construction  of  the  hearth.  (3).  The  openings,  a  a',  admitting  the 
toyeres  of  the  blast. 

The  refining  operation  is  carried  on  at  a  gradually  increased  temperature  until  only  a  very 
ttun  layer  of  oxide  of  lead  covers  the  surface  of  the  silver.  This  is  known  by  the  peculiar 
diqtiayof  eolonrs,  technically  known  as  the  brightening,  more  aptly  expressed  in  German  by 
a vord  which  means  lightening,  for  that  is  really  the  appearance.  This  being  observed,  the 
tre  ii  alaekenedf  and  the  silver  having  been  cooled  with  water,  is  removed  from  the 
hearth.  The  litharge  which  runs  off  is,  on  cooling,  a  yellow  or  reddish-yellow  crystalline 
(see  Lead,  p.  63). 

I'tMMiiod.      The  refining  process  just  described  is  not  suited,  that  is  to  say, 

does  not  pay,  when  the  lead  contains  only  o'  12  per  cent  of  silver.    Now  it  so  happens 

that  the  various  kinds  of  galena  met  with  in  England  yield  a  lead  which  contains 

only  0*03  to  0*05  per  cent  of  silver.    In  1833,  Mr.  H.  L.  Pattinson,  of  the  Felling 

Chemical  Works,  near  Gfrateshead-on-Tyne,  instituted  a  series  of  experiments  relative 

to  a  new  method,  applicable  on  the  large  scale,  for  separating  lead  from  silver  when 

&e  latter  is  present  in  small  quantities.    His  efforts  were  successful,  and  have 

greatly  benefitted  his  own  and  other  countries  where  his  process  is  worked. 

Pattin8on*B  method  essentiaUy  consiBts  in  a  concentration  process,  based'upon  the  pheno- 
nenon  that  when  a  certain  quantity  of  lead  that  contains  silver  is  melted  in  iron  cauldrons, 
aod  the  fluid  mass  allowed  to  cool  uniformly,  there  ensues  a  formation  of  small 
octahedral  crystals  which  do  not  contain  any  silver  at  all,  or,  at  any  rate,  are  a  great 
M  poorer  in  silver  than  the  metal  originally  taken,  while  the  portion  of  the  metal 
nmaining  fluid  is  found  to  contain  an  increased  quantity  of  silver.  It  is  clear,  there- 
'on,  that  if  the  crystals  first  obtained  are  again  melted  and  cooled  uniformly,  another 
^oooentration  will  be  obtained,  and  that  the  operation  can  be  repeated  until  a  lead  is' 
obtained  rich  enough  in  silver  to  admit  of  tmdergoing  a  refining  process.  Practically, 
Mr.  Pattinson's  method  admits  of  concentrating  2*5  per  cent  of  ralver.  In  the  execution 
of  this  process,  the  }  and  }  systems  are  employed.  If  the  first,  at  every  operation  two* 
thirds  of  the  contents  of  the  cauldron  are  removed  with  perforated  ladles,  while  in  the 
other  ease,  seven-eighths  is  the  quantity  of  crystals  ladled  out,  leaving  respectively  one- 
third  aod  one-eightii  of  the  contents  of  the  cauldron  in  the  shape  of  fluid  lead.  The 
1 9item  is  better  suited  for  the  richer  lead,  the  i  bystem  for  very  poor  lead.  M.  Bondohen 
has  recently  modified  Pattinson's  process.  Instead  of  ladling  out  the  crystals,  he 
^ffoaes  them  in  the  lead,  and  stirs  tiiem  about  to  prevent  them  enclosing  any  lead 
hhe^  to  oontain  silver.  The  lead  is  withdrawn  from  the  cauldron  by  means  of  a  tap  at  the 
bottom.  In  all  cases,  however,  the  quantity  of  lead  operated  on  at  one  time  is  always 
large,  geiteraUy  200  owts.,  to  cause  the  cooling  to  proceed  slowly.  At  the  Freidrich  Lead* 
Silver  Works,  near  Tamowitz,  the  enriched  lead  contains  1*28  per  cent  of  silver. 


102  CHEMICAL  TECHNOLOGY. 

Bedtiefcionb^iieuw      xhis  process,  Suggested  by  Mr.  Parker,  in  1850,  has  only  recently 

been  practically  carried  ont  by  M.  Corduri6,  at  Toulouse.    This  method,  as  &r  as 

we  are  now  capable  of  judging,  will  probably  supersede  even  Pattinson's  excellent 

method.    The  rationale  of  the  process  is  based  upon  the  fi&cts : — i.  That  lead  and 

zinc  do  not  alloy  together.    2.  That  the  affinity  of  silver  for  zinc  is  much  greater 

than  for  lead. 

The  following  is  the  manner  of  execution : — 20  owts.  of  lead,  which  may  contain  (pear 
ton)  only  0*25  kilo,  of  silver,  is  melted,  and  when  properly  Uquefied  there-  is  added  i  cwt, 
of  molten  zinc.  The  zinc  having  been  thoroughly  mixed  with  the  lead,  the  molten  mass 
is  left  to  stand  until  the  zinc,  which  has  risen  to  the  surface,  forms  a  cake  that  is  easily 
removed.  The  zinc  is  then  separated  from  the  silver  by  distillation.  The  residue  of  the 
distillation  is  melted  with  lead,  and  the  alloy  thus  obtained  refined  as  above  described. 
The  zinc  obtained  by  the  distillation  is  used  for  another  operation.  According  to  a  more 
recent  improvement,  the  zinc  is  separated  from  the  silver  by  oxidation  by  passing  super- 
heated steam  over  the  red-hot  zinc  (Zn+H20  =  ZnO  +  H2).  The  lead,  which  of  course 
after  this  operation  contains  traces  of  zinc,  is  purified  by  being  melted  with  either  chloride 
of  lead,  or  a  mixture  of  sulphate  of  lead  and  chloride  of  sodium,  or  with  chloride  of  potas- 
sium from  Stassfurt,  the  result  being  the  formation  of  chloride  of  zinc,  which  collects  at 
the  surface  or  may  be  volatilised  at  a  low  red  heat. 

Tba  uiumato  Beftniii«      ^  whatever  manner  silver  may  have  been  metallurgicaUy  obtained, 
ofsurwr.  the  metal  is  a  crude  material,  very  far    from    being   oent-per-cent 

silver.  The  impurities,  foreign  metals,  or,  more  correctly,  base  metals,  often  amount  to 
7  and  even  8  per  cent ;  and  in  order  to  remove  these,  the  silver  is  submitted  to  a  process 
of  ignition  in,  or  rather  on  the  suriace  of,  vessels  made  of  an  absorbent  material.  This 
material  is,  for  this  ultimate  refining,  generally  bone-ash,  which  is  pressed  into  iron  rings 
of  convenient  size,  care  being  taken  to  fuse  some  lead  with  the  silver,  if  there  is  not  already 
sufficient.  As  regards  this  ultimate  refining,  there  can  be  distinguished  three  different 
methods.  The  first  has  just  been  described.  The  second  is  carried  on  in  muffles,  the 
base  metals  burning  off  slowly.  The  third,  and  most  advantageous  method,  is  carried  on 
in  a  reverberatory  furnace.  100  parts  of  crude  silver  yield  96*8  parts  of  refined  silver  at 
gg-g  per  cent  pure  fine  metal,  which  is  cast  in  largessized  bars.  The  value  of  the  annual 
production  of  fine  silver  amounts  to  £9,000,000.  Of  this,  Mexico's  share  is  the  largest, 
being  half  of  the  entire  production.  The  bulk  of  this  silver  contains  some  gold  and 
platinum. 

Chemically  Pni9  surer.  When  for  certain  purposes  metallic  silver  is  required  chemically 
pure,  it  may  be  obtained  by  dissolving  any  ordinary  silver  coin  in  nitric  acid,  and  precipi- 
tating the  solution  with  an  aqueous  solution  of  common  salt  or  hydrochloric  acid,  llie 
chloride  of  silver  thus  obtained  should  be  reduced  by  ignition  in  a  crucible  with  dry  car- 
bonate of  potassa,  to  which  a  Uttle  resin  may  be  added.  But  chloride  of  silver  is  now 
commonly  reduced  by  the  wet  way,  by  causing  it  to  be  acted  upon  by  metallic  zinc  and  & 
dilute  solution  of  either  sulphuric  or  hydrochloric  acid — 

(2AgCl+ Zn+C1H«  ZnCl2+ Ag2+C1H). 

pn>p«itieB  of  snvcr.  Silver  obtained  by  smelting  exhibits  a  pure  white  colour  and  a  strong 
metalhc  lustre,  which  is  gretftly  increased  by  polishing.  Its  fracture  is  compact  rather 
than  fibrous.  It  is  softer  than  copper,  but  harder  than  pure  gold ;  when  chemically  pure 
its  softness  is  greatest.  It  is  not  a  sonorous  metal,  bearing  a  resemblance  in  this  respect 
to  tin  and  lead.  Gold  only  excepted,  silver  is  the  most  ductile  of  the  metals,  a  property 
impaired  by  the  presence  of  foreign  metals  other  than  copper  and  gold,  by  the  latter  of 
which  the  ductihty  is  slightly  increased.  Lead  and  antimony  render  silver  brittle.  "Wlien 
silver  contains  an  excess  of  carburet,  produced  by  smelting  the  metal  with  an  excess  of 
carbon,  the  metal  is  rendered  less  ductile ;  but  a  smaU  quantity  of  the  carburet,  as  much 
as  is  found  in  coins  of  a  high  percentage  of  silver,  is  rather  advantageous,  increasing  the 
hardness  of  the  metal,  and  causing  it  to  wear  well.  Smelting  in  plumbago  crucibles  does 
injure  silver.  Its  specific  gravity  varies  from  10*5  to  107.  The  absolute  strength  is  far 
less  than  that  of  copper.  Its  expansion  by  heat  in  o*"  to  100°  G.  is  ,  j,th.  According  to 
M.  Deville,  the  melting-point  is  gi6° ;  but  Br.  van  Biemsdijk  states  that  the  results  of  a 
series  of  experiments  made  at  the  Utrecht  Mint,  in  1868,  showed  the  melting-point  tP  be 
10400,  the  metal  being  kept  in  a  slow  current  of  pure  hydrogen.  At  a  very  high  tempera- 
ture, such  as  can  be  produced  only  by  the  oxyhydropen  fiame  or  by  electricity,  silver  is 
volatilised.  When  alloyed  to  other  metals,  especially  to  copper,  the  volatility  is  increased, 
and  even  at  a  lower  temperature  than  the  melting-point  of  copper,  viz.,  1330"*,  Dr.  van 
Biemsdijk  found  such  silver  to  be  perceptibly  volatile.  M.  Stas,  of  the  Brussels  Mint,  in 
2869,  distilled  some  50  grms.  of  silver  by  means  of  the  oxy hydrogen  fiame,  in  order  to 


SILVER.  103 

obtain  the  metal  perfectly  pnre.  Molten  silyer  abBorbs  oxygen,  whioh  is  again  expelled 
from  the  metal  on  Bolidiiication,  and  giyes  rise  to  the  phenomenon  known  by  silYer- 
assayers  as  spirting,  the  escape  of  the  gas  cansing  the  metal  to  be  forced  asunder  in  small 
drops.  Howeyer,  when  the  molten  silver  contains  even  i  per  cent  of  either  lead  or  copper, 
it  BoHdifiee  withont  spirting.  Silver  is  not  acted  npon  by  dilate  acids,  bnt  is  readily 
diBsoWed  in  the  cold  by  nitric  add.  Silver  is  very  sensitive  to  the  action  of  snlphnretted 
hydrogen,  by  which  it  is  readily  tarnished. 

AOoTvefBOTw.  8ilver  alloys  readily  With  lead,  zinc,  bismuth,  tin,  copper,  and  gold ; 
but  Uie  moat  important  alloy,  ia  an  industrial  point  of  view,  is  that  with  copper, 
pure  silver  being  too  soft  for  general  application.  All  silver,  therefore,  whether  used 
for  plate,  coin,  or  for  ornamental  purposes,  invariably  contains  a  certain  amount  of 
copper.  In  most  civilised  countries  there  exist  laws  regulating  the  alloy  of  silver  to 
be  used  for  coin  or  plate.  Pure  silver,  or  fine  silver,  is  now  generally  indicated 
by  Jg{§.  The  alloy  for  the  silver  coins  of  Germany  is  indicated  by  ^^%% ;  meaning 
that  1000  parts  by  weight  of  the  coin  contain  900  parts  of  pure  silver,  the  remainder 
being  copper.  Twenty-seven  Union  thalers  weigh  i  half  kilo.,  therefore  a  single 
thaler  weighs  18*518  grms.,  and  contains  i6'666  grms.  of  pure  silver.  By  an  inter- 
national treaty  with  France,  Italy,  Belgium,  Portugal,  Switzerland,  and  Spain,  i  kUo. 
of^VoB  silver  is  to  yield  200  franc  pieces,  i.e.y  222I  franc  pieces  to  i  kilo,  oi  fine 
silver.  The  same  alloy  is  employed  for  pieces  of  2  and  5  francs,  there  being  200  of 
the  latter  to  the  Idlo.  In  the  Netherlands,  where,  by-the-bye,  gold  coin  is  no  longer 
cmrent,  and  silver  is  the  standard,  the  alloy  used  is  tWo*  The  silver  coins  of  the 
United  Kingdom  are  made  of  an  alloy  tVoV  \  i  ^'  Troy,  or  yjyzoB  grms.,  of  this 
aDoy  \b  coined  into  66  shilling  pieces.  A  pound  Troy  of  fine  silver  would  yield 
71 H  shillings. 

";j£"2^*"  In  nearly  all  European  countries  the  laws  have  fixed  the  composition 
of  the  alloy  of  silver  which,  duly  marked  and  stamped,  shall  be  ofiered  for  sale  as 
plate  by  gold-  and  silver- smiths,  who,  in  Holland,  Belgium,  France,  and  Sweden,  are 
not  allowed  to  have  in  their  workshops  any  electro-plated  articles,  or  any  alloys 
(^er  than  those  fixed  by  law.  The  composition  of  these  alloys  varies ;  expressed  in 
miUiimes  of  fine  metal,  it  is  for  Austria  and  Bavaria,  812 ;  for  Prussia  and  Saxony, 
750;  for  England,  925.  For  France,  Belgium,  and  the  Netherlands,  a  double  alloy 
is  fixed,  the  higher  being  950,  the  lower  800.  The  alloy  lately  brought  iuto  use 
nnder the  name  of  tiers-argent^  one-third  silver,  really  consists  of  2756  per  cent 
flOver,  59  per  cent  copper,  9*57  per  cent  zinc,  and  342  per  cent  nickel,  though  in  the 
trade  this  alloy  is  alleged  to  consist  of  I  nickel  and  ^  silver.  Tiers-argent  sells  at 
^3  i2s.  per  kilo.  This  alloy  is  harder  than  silver ;  its  colour  and  polish  are  as  good. 
It  is  extremely  well  adapted  for  all  kinds  of  plate. 

wvwAMBy.  If  it  be  desured  to  know  the  quantity  of  fine  silver  contained  in  an  alloy  of 
alver—wiiich  for  our  present  purpose  we  will  assume  to  contoin  only  silver  and  copper — 
there  are  three  different  methods  by  which  this  proposition  can  be  solved,  viz. :— yi.  The 
•■tty  by  the  dry  way,  termed  cupellation.  a.  The  assay  by  the  wet  way,  or  titration 
prooess.    3.  The  hydrostatic  assay. 

Dir  AiMy.  Usually  this  assay  is  conducted  by  first  testing  the  alloy  by  comparing  the 
streak  it  makes  upon  touchstone — a  piece  of  polished  basalt  or  siliceous  schist — with  the 
streak  produced  upon  the  same  stone  by  test-needles ;  that  is  to  say,  small  bars  of  silver 
of  known  composition.  It  should,  however,  be  borne  in  mind  that  the  surface  of  silver 
vtioles,  as  well  as  of  coins,  may  have  been  hlanehed^  as  the  term  runs ;  that  is  to  say, 
■eted  upon  by  hot,  dilute  sulphuric  acid,  to  dissolve  a  portion  of  the  copper  of  the  alloy, 
snd  leave  a  film  of  alloy  richer  in  silver.  The  alloy  to  be  further  assayed  is  next  melted 
down  with  a  piece  of  pure  soft  lead,  or  lead  containing  a  known  quantity  of  silver,  in  a 
e^nnle,  technically  €»dled  cupel,  made  of  bone-ash.  The  cupel  is  previously  well  heated 
in  a  muffle,  and  the  lead  is  placed  in  it.  As  soon  as  the  lead  has  become  quite  liquid,  the 
sample  of  silver  to  be  assayed  is  added ;  the  copper  and  lead  are  oxidised,  and  in  that  state 


104  CHEMICAL  TECBNOLOGT. 

absorbed  by  the  porone  substanoes  of  the  (mpd«  As  soon  as  the  surface  of  the  silTer 
button  appears  quite  bright,  the  operation  is  finished,  and  the  cupel  slowly  cooled.  The 
button  of  silver  is  then  weighed.  It  is  usual  to  make  two  assays  of  the  same  sample  ; 
these  assays  should  agree  in  their  results  to  within  tV^i^^  to  be  of  any  value. 

Wet  Amy.  This  method  of  assaying  silver  was  devised  some  sixty  years  ago  by  the  late 
Professor  Gkty-LuBsac,  at  the  request  of  the  French  Government,  in  consequence  of  the 
great  irregularity  of  the  results  obtained  by  the  dry  method.  The  wet  assay,  having  heen 
very  greatly  improved  in  detail  by  Dr.  G.  J.  Mulder,  M.  A.  W.  H.  van  Itiemsdijk,  Br.  Staa, 
and  M.  J.  Dumas,  is  now  generally  adopted,  and  will  remain  to  all  time  a  master- 
piece worthy  of  the  ingenuity  of  its  original  inventor,  who,  by  introducing  this  method, 
laid  the  foundation  of  volumetric  analysis,  now  so  usefully  and  completely  applied.  Gay- 
Lussac's  wet  method  of  silver  assay  is  more  easily  executed  than  the  dry  assay,  while  it  la 
far  more  correct,  admitting  an  accuracy  of  judgment  within  ^th  per  cent.  The  method 
is  based  upon  the  property  possessed  by  common  salt  of  precipitating  silver  as  chloride  of 
silver  from  its  nitric  add  solution.  As  5*4274  grms.  of  pure  common  salt  exactly  convert 
I  grm.  of  pure  edlver,  previously  dissolved  in  nitric  acid,  into  chloride  of  silver,  it  is 
evident  that,  from  these  data  and  with  the  application  of  suitably  constructed  apparatus 
for  the  volumetric  analysis,  the  fineness  of  any  alloy  of  silver  may  be  asoertained  readily, 
rapidly,  and  with  great  accuracy. 

Hydnwutiami  am«7.  Thls  method  is  of  course  by  no  means  so  correct  as  either  of  the 
foregoing,  and,  moreover,  is  impaired  by  the  fact  that,  although  alloys  of  copper  and 
silver  expand  under  pressure,  thiBy  become  denser,  so  that  the  hydrostatic  weighing,  that 
is  to  say,  the  estimation  of  the  specific  gravity  of  the  alloy,  is  only  admitted  as  a  test  of 
its  relative  value.    With  such  alloys  as  have,  like  coins,  to  be  rolled,  pressed,  or  drawn, 

the  hydrostaticalresultsrarely  differ  more  than  —  from  the  results  obtained  by  cupella- 

tion.  The  empirical  rule  for  the  estimation  of  the  value  of  sUver  assayed  by  this  method 
is  the  following : — The  number  8*814  is  subtracted  from  the  specific  gravity  of  the  alloy, 
two  cyphers  are  added  to  the  difference,  and  the  figure  thus  formed,  considered  as  a  whole 
number,  is  divided  by  579 ;  the  quotient  is  the  fineness  of  the  silver-alloy  expressed  in 
grains.  For  instance,  let  the  specific  gravity  of  the  alloy  be  s  io'o65,  then  the  fini*n^»ftff 
is  s2z6  grains,  or  zWo'*  since — 

iO'o65-8'8i4=i'25i 

and 

125,100 

579 
somiag.      The  coating  of  metals  with  a  film  of  silver  can  be  effected  by : — t,  plating ; 
2,  the  igneous  process ;  3,  in  the  cold ;  4,  the  wet  way ;  5,  galvanically,  or  electro-plating. 

sttnerPiBtins.  In  order  to  coat  metallic  copper  with  a  layer  of  silver,  the  sheet  copper  is 
first  thoroughly  cleansed,  then  treated  with  a  moderately  strong  solution  of  nitrate  of 
silver,  and  next  covered  with  a  sheet  of  silver.  After  having  been  made  red-hot,  the  two 
metals  are  rolled  out  together.  The  silver  then  adheres  so  strongly  to  the  copper  as  to 
admit  of  the  metals  being  beaten  or  stamped  into  various  shapes.  Copper-wire  is  readily 
silvered  by  being  covered  with  thin  strips  of  silver,  and  passed  through  rollers.  But  this 
method  of  plating  is  almost  entirely  superseded  by  electro-plating. 

isneoos,  or »!»  This  method  of  silvering  is  effected  by  the  aid  either  of  a  silver-amalgam 
suTering.  qj.  y^y  applying  to  the  w^-deansed  surface  of  the  metal  intended  to  be 
silvered  a  mixture  of  i  purt  of  spongy  precipitated  metallic  silver,  4  parts  sal-ammoniao, 
4  parts  common  salt,  and  i  part  corrosive  sublimate.  The  metal  to  be  silvered  is  rubbed 
with  this  mixture,  and  then  heated  in  a  muffle.  Buttons  intended  to  be  silvered  are 
covered  with  a  paste  consisting  of  48  parts  of  common  salt,  48  parts  sulphate  of  zinc,  z  part 
of  mercuric  chloride,  and  2  t>arts  of  diloride  of  silver. 

sfltoinffintiMOoid.  The  metallic  surface  intended  to  be  silvered,  having  been  well 
cleaned,  is  rubbed  by  means  of  a  smooth  cork,  with  a  mixture  of  equal  parts  of  chloride  of 
silver,  common  salt,  }  of  chalk,  and  2  of  carbonate  of  potash,  made  with  water  into  a 
creamy  paste.  Professor  Hein  recommends  that  i  part  of  nitrate  of  silver  and  3  of 
cyanide  of  potassium  should  be  rubbed  together  in  a  mortar,  with  the  addition  of  sufildent 
water  to  form  a  thick  paste.  The  paste  is  rubbed  on  the  metal  to  be  silvered  with  a  piece 
of  flannel.  MM.  Boseleur  and  Lavaux  recommend  a  mixture  of  100  parts  of  sulphite  of 
soda  and  15  parts  of  any  ealt  of  silver.  For  silvering  the  dial-plates  of  watches,  Ae., 
M.  Thiede  recommends  a  mixture  of  spongy  silver  with  equal  parts  of  common  salt  and 
cream  of  tartar.    In  order  to  silver  iron  it  is  first  covered  with  a  layer  of  copper. 


GOLD.  105 

aanriflcwtiM  This  is  effected  by  imniersmg  the  metal  intended  to  be  silyered  in  a 
w^Twsy.  '  boiling  aqneons  solution  of  equal  parts  of  cream  of  tartar  and  common 
■alt,  with  \  part  of  chloride  of  silver.  The  description  of  the  methods  of  electro-plating 
will  be  giyen  at  the  end  of  the  chapter  on  Metals. 

oiidtawi  sdtw.  The  small  ornaments  met  with  under  the  name  of  oxidised  silyer  are 
prepared  with  either  solphnr  or  chlorine ;  in  the  former  case  a  bluish-black  colour  is 
in^arted,  in  the  latter  a  brown.  The  sulphur  is  applied  simply  by  dipping  the  object  into 
a  Boiution  of  sulphuret  of  potassium,  while  for  the  chlorine  colour  a  mixture  of  sulphate 
of  copper  and  sid-ammoniac  is  used. 

sitate  of  BUvw.  This  salt  (AgN03)  is  now  prepared  on  the  large  scale  by  dissolying  silyer 
iwmt*mfT»g  copper  in  nitric  add,  evaporating  the  solution  to  diyness,  and  ignitmg  the 
nodue  until  all  the  nitrate  of  copper  is  decomposed.  The  residue  is  next  exhausted  with 
pore  water,  the  solution  filtered  and  left  to  crystallise.  For  medical  purposes  the  ciystals 
are  fused,  and  while  liquid  poured  into  moulds  to  form  small  round  sticks.  The  most 
extensive  use  of  nitrate  of  silver  obtains  in  photography,  a  re-crystallised  neutral  and  pure 
salt  bdng  preferred.  Under  the  name  of  Sel  ClSmetUy  there  is  now  in  use  in  photography 
a  mixture  of  fused  nitrates  of  silver,  sodium,  and  magnesium,  recommended  as  preferable 
to  nitrate  of  silver  alone.  It  is  stated  that  the  consumption  of  this  salt  for  photograpl^io 
purposes  amounted,  in  1870,  to  1400  cwts.  for  Germany,  France,  England,  and  the 
United  States ;  the  money  value  of  this  quantity  being  estunated  at  £630,000. 

xuking  Ink.  A  large  quantity  of  nitrate  of  silver  is  also  used  for  the  purpose  of  mitlriTig 
indelible  ink  for  marking  linen.  This  ink  often  consists  of  two  different  fluids,  one  a  solution 
of  pyrogallic  acid  in  a  mixture  of  water  and  alcohol,  being  intended  to  moisten  the  linen 
previous  to  writing ;  the  other,  or  writing  fluid,  consisting  of  a  solution  of  ammoniacal 
nitrate  of  silver  thid^ened  with  gum.  More  recently  aniline  black  has  been  applied  in  the 
maririug  of  linen. 

Gold. 
(Aii=i97;  Sp.  gr.  195  to  19*6). 

'^'^SSS^oSl***      Gold  is  found  only  in  the  native  metallic  state,  sometimes  in 

veins  interspersed  in  rocks,  and  accompanied  by  quartz,  iron  pyrites,  and  iron  ore. 

More  firequently  gold  is  found  finely  divided  in  sand,  mixed  with  larger  or  smaller 

nuggets,  and  imbedded  in  quartz,  with  various  other  minerals,  such  as  mica,  syenite, 

cfalorite  slate,  chrome-iron  ore,  and  spineL    Native  gold  commonly  contains  some 

silver  and  other  metals,  among  which  are  palladium  and  platinum.    According  to 

lecent  analyses,  the  composition  of  samples  of  gold  obtained  from  several  coontries  is  :-^ 

L  IL 

Hungary.      B.  America.     Siberia.    Oalifomia.       Australia. 
Ooid        .        .        .        6477  8804  86*50         89*60         99*2  95*7 

Silver       .  .        35*23  11*96  13*20  io*o6         043  3*9 

Iron  and  other  metals         —  —  0*30  0*34         0*28  02 

Gold  is  found  native  with  tellurium  and  telluride  of  silver,  and  among  antimony, 
zinc,  arsenic,  and  other  ores.  It  is  also  found  in  galena  and  various  kinds  of  clay ; 
indeed,  gold  is,  next  to  iron,  the  most  widely  dispersed  metal.  The  chief  gold 
yielding  countries  are : — ^Africa,  Hungary,  the  Oural,  Australia,  and  America,  especially 
Uiexico,  Pern,  the  Brazils,  California,  Columbia,  and  Victoria. 

The  total  value  of  the  gold  produced  in  the  year  1869  is  computed  at  ^860,000,000, 
one-fourth  of  this  representing  the  value  of  the  production  of  California.  The 
▼ibie  of  the  joint  production  of  the  Australian  Colonies  is  a  littie  above  another 
one-fourth. 

nad«ofxxinMCii«ooid.  The  mode  of  extracting  gold  is  determined  by  the  drcum- 
stances  of  its  occurrence.  By  &r  the  largest  portion  of  the  gold  in  circulation 
is  obtained  by  the  washing  process;  that  is  to  say,  the  elimination  by  means  of  water 
of  the  lighter  minerals,  the  finely  divided  gold  being  left  behind.  This  process  may 
be  carried  on  in  remote  districts  in  a  very  primitive  manner,  by  simply  putting  the 
nad  into  wooden  bowls,  and  washing  it  gradually  away  with  water.    The  gold 


io6  CHEMICAL  TECHNOLOGY. 

so  obtained  is  not  pure,  but  contains  titanic  iron  and  other  minerals.  AVfaerever 
gold  washing  is  a  regularly  established  business,  as  in  some  parts  of  the  Oural, 
properly  constructed  contrivances  are  applied. 

^**^MS?iJf **""*'  The  application  of  mercury  to  the  extraction  of  gold  is  based 
upon  the  fact  that  mercury  amalgamates  with  gold  readily  and  very  eflfectively.  The 
operation  is  carried  on  with  the  gold-containing  sand  in  peculiarly  constructed 
ipiUs.  Mr.  Grookes  has  shown  that  the  addition  of  sodium  to  the  mercury 
facilitates  the  extraction  of  the  gold.  The  excess  of  mercury  having  been  removed 
from  the  amalgam  by  pressure  in  leathern  or  stout  linen  bags,  the  remainder 
in  amalgamation  with  the  gold  is  volatilised  by  ignition  in  suitably  constructed 
furnaces. 

smettiog  for  Gold.  By  a  far  moi^e  perfect  process  than  washing,  gold  is  extracted  from 
the  gold  sand  by  smelting  with  a  suitable  flux  in  a  blast  furnace.  The  object  in 
view  is  to  produce  a  rough  or  crude  iron  from  which  the  gold  is  separated  by  means 
of  sulphuric  acid.  This  process  yields  from  25  to  30  times  more  gold  than  merely 
washing  the  sand. 

Treattnx  ^th  AikaiL  Mr.  Hardlugs  proposcd  to  obtain  the  gold  by  treating  the  quartz 
or  sand  with  caustic  alkalies  under  a  high  pressure  of  steam,  thereby  forming 
a  soluble  silicate  and  leaving  the  gpld. 

"^JS^M^wiS^cfrSf™  ^  ^^^^  happens  to  be  interspersed  through  copper  or  lead  ores, 
they  are  roasted  and  then  washed.  When  the  quantity  of  gold  is  sufficient  such  ores 
are  treated  with  mercury,  while  sometimes  they  are  treated  for  coarse  metal ;  and 
this,  containing  all  the  gold,  is  smelted  with  litharge,  which  absorbs  the  gold,  and  is 
next  separated  from  it  on  a  refining  hearth. 

*^*"po!lrMS»22i'*^''  Some  minerals  and  metallurgical  refuse  containing  only  a  very 
small  quantity  of  gold  have  been  treated  at  Beichenstein,  in  Silesia,  by  means 
of  chlorine  water,  or  an  acidulated  solution  of  bleaching  powder.  The  gold  is  con- 
verted into  chloride  of  gold  (AUCI3),  and  is  precipitated  from  the  solution  by 
sulphate  of  iron  or  sulphuretted  hydrogen.  This  method  has  been  severely  tested  by 
MM.  Plattner,  Th.  Eichter,  Georgi,  and  Dr.  Duflos,  and  has  been  found  to  answer 
epcceedingly  well,  even  with  very  poor  ores.  This  plan  is  of  course  generally 
applicable  to  gold  sand  and  gold  quartz.  According  to  M.  Allain,  pyritical  ores, 
having  been  roasted  and  treated  with  sulphuric  acid  to  eliminate  the  iron,  zinc, 
and  copper,  can  be  then  treated  with  chlorine  water  so  as  to  extract  the  gold  present, 
to  an  amount  only  of  i  part  of  gold  in  10,000  of  mineral. 

Beflning  Gold.  In  Order  to  separate  any  foreign  metals  from  the  gold  obtained  by  the 
above  process,  the  following  methods  have  been  employed,  but  only  the  last  (5.) 
is  now  in  general  use.  For  that  reason  the  other  methods  will  only  be  briefly 
described  :-^ 

1.  Refining  by  means  of  sulphuret  of  antimony  (SbaS^). 

2.  By  means  of  sulphur  and  litharge. 

3.  By  cementation. 

4.  By  quartation. 

5.  By  means  of  sulphuric  acid. 

By  M01UIS  of  sniphnrtt      ^^^  process  Is  effected  by  first  smelting  the  alloy,  which  ought  to 

of  Anumony.        contain  at  least  60  per  cent  of  gold,  in  a  graphite  crucible.    Pulverised 

black  sulphuret  of  antimony  is  added  in  the  proportion  of  2  parts  to  i  of  alloy,  and  the 

molten  mass  is  then  poured  into  an  iron  mould,  which  is  rubbed  with  oil.    The  mass  on 

cooling  will  be  found  to  consist  of  two  separate  layers — the  upper,  technically  termed 


GOLD.  J07 

plafmdt  eonaiBtiiig  of  the  Bnlphnrets  of  silver,  copper,  and  antimony ;  the  lower,  an  alloy 
of  antimony  and  gold,  which  is  separated  in  a  mnffle  or  a  wind  furnaoe.  The  remaining 
gold  is  fused  with  borax,  saltpetre,  and  some  powdered  glass. 

ByUwAifiof  soipfaw.  This  procosB  does  not  aim  at  the  entire  separation  of  the  gold  from 
the  other  metals,  bat  rather  at  its  concentration  in  a  smaller  quantity  of  silver  than  was 
originAlly  present  in  the  alloy,  so  as  to  render  it  snited  for  quartation.  The  alloy, 
previoosly  granulated,  is  mixed  with  f  part  of  powdered  snlphnr,  pnt  into  a  red-hot 
graphite  cmcible,  and  covered  with  charcoal  powder.  The  crucible  is  kept  at  a  low  red 
heat  for  2k  hours,  and  then  raised  to  the  point  of  fusion.  If  the  alloy  contained  gold  in 
any  considerable  quantity,  a  layer  of  silver  separates,  which  wiU  be  rich  in  gold ;  but  if  the 
original  alloy  was  rather  poor  in  gold,  litharge  is  added  to  the  molten  mass,  the  oxygen  of 
the  litharge  causing  the  combustion  of  the  sulphur  of  a  portion  of  the  sulphuret  of 
silver,  the  metallio  idlver  combining  with  nearly  all  the  gold.  The  reduced  lead  is  ti^Lcn 
up  hj  the  sulphurets  of  the  other  metals  present. 

cufmution  praews.  The  alloy  containing  gold  having  been  either  granulated  or  rolled 
into  thin  sheets  suitably  cut  up,  is  placed  in  a  crucible,  in  this  instance  technically  termed 
a  cementation  box,  and  mixed  with  4  parts  of  pulverised  bricks,  and  i  part  each  of 
common  salt  and  dried  copperas.  The  crucible  is  then  gradually  raised  to  a  cherry-red 
beat.  Chlorine  is  evolved  in  this  operation  by  the  action  of  the  sulphate  of  iron  upon  the 
common  salt ;  there  is  consequently  formed  chloride  of  silver,  which  is  absorbed  by  the 
polTcrised  bricks,  while  the  gold  is  left  unattacked.  After  cooling,  the  mass  is  boiled  in 
vater  in  order  to  obtain  the  gold.  Here  must  be  mentioned  Mr.  F.  B.  Miller's  process  of 
{wssing  chlorine  into  molten  gold  in  order  to  eliminate  the  base  metals  which  render 
it  brittle,  while  the  silver,  converted  into  chloride,  floats  to  the  surface. 

QButattoB.  This  process  has  obtained  its  name  from  an  opinion  that,  to  ensure  success, 
there  should  be  three  times  more  silver  in  the  alloy  than  gold,  i.e,,  the  gold  should  amount 
to  a  quarter  of  the  entire  alloy.  But  Dr.  M.  von  Pettenkofer  has  proved  that  if  the 
amount  of  silver  be  double  that  of  the  gold,  the  separation  of  the  two  metals  will 
be  complete,  provided  sufficiently  strong  nitric  acid  be  employed,  and  the  boiling  con- 
tinued for  a  length  of  time.  Practically  this  method  is  as  follows: — There  is  added 
to  the  gold  a  sufiicient  quantity  of  silver,  and  the  two  metals  are  smelted  together.  The 
alloy  is  next  granulated,  placed  in  a  platinum  vessel,  and  boiled  with  nitric  acid  of  1*320 
sp.  gr.,  care  being  taken  that  the  acid  is  free  from  any  chlorine.  The  sUver  being  dis- 
Bohed,  the  gold  is  left  behind,  and  further  refined  by  fusion  with  borax  and  saltpetre  in  a 
emcible. 

^!?Si2iJte^^*  This  method  of  refining,  which  has  been  briefly  alluded  to 
onder  Copper,  is  preferable  to  any  of  the  foregoing  on  account  of  its  perfection, 
cheapness,  and  simplicity.  By  this  method  almost  any  aUoy  containing  gold  in 
addition  to  copper  and  silver  can  be  treated,  but  the  quantity  of  gold  should  not 
exceed  20  per  cent,  nor  that  of  the  copper  10  per  cent,  while  the  best  proportions, 
according  to  Dr.  Pettenkofer's  researches  are,  that  in  16  parts  of  the  alloy,  the  gold 
should  not  exceed  4  or  be  much  less  than  3  parts,  and  the  rest  copper  and  silver. 
Usually  the  alloy  intended  for  this  mode  of  operation  is  first  granulated,  or  if 
it  happens  to  be  in  the  shape  of  silver  coins — Mexican  dollars,  for  instance — they  are 
cut  to  pieces.  Formerly,  platinum  vessels  were  employed  in  the  boiling  of  the  alloy 
with  thoroughly  concentrated  sulphuric  acid  (sp.  gr.  1848),  but  cast-iron  vessels,  or 
sometimes  hard  porcelain  vessels,  are  now  employed,  the  proportion  being  2  molecules 
of  acid  to  I  molecule  of  the  alloy.  The  heating  is  continued  some  twelve  hours, 
Qutil  the  copper  and  silver  are  completely  dissolved.  The  sulphurous  acid  evolved 
is  employed  in  the  manufacture  of  sulphuric  acid,  or  is  absorbed  by  a  soda  or 
lime  solution  to  form  sulphite  or  bisulphite  of  soda  or  bisulphite  of  lime.  The  solu- 
tion of  mixed  sulphates  of  silver  and  copper  is  poured  into  leaden  pans,  and 
becoming  solidified  on  cooling,  the  pasty  mass  iJs  dug  out  with  iron  spades,  and  put 
into  leaden  tanks  filled  with  boiling  water,  in  88  parts  of  which  i  part  of  sulphate 
of  silver  is  soluble.  The  silver  is  precipitated  from  this  solution  by  strips  of  copper, 
and  the  solution  of  sulphate  of  copper  obtained,  having  been  deprived  of  its  excess 
of  free  add  by  the  addition  of  oxide  of  copper,  is  further  treated  for  blue  vitriol.  The 


#     —  

Persulphate  of  iron,  2Fea3S04. 
Ohloride  of  iron,  FosClG. 


io8  CHEMICAL   TECHNOLOGY. 

gold  which  has  remained  as  a  dark,  insoluble,  spongy  mass,  is  first  boiled  with  a 
solution  of  carbonate  of  soda,  next  with  nitric  acid,  to  free  it  from  any  adhering 
oxide  of  iron,  snlphuret  of  copper,  sulphate  of  lead,  and  other  impurities ;  and  after 
having  been  dried,  is  melted  with  the  addition  of  saltpetre.  By  this  process  it  has 
become  possible  to  extract  the  i-ioth  to  i-i2th  per  cent  of  gold  contained  in  old  silver 
coins ;  therefore  this  method  of  refining  has  come  largely  into  use,  as  within  the  last 
thirty  years  nearly  all  European  States  have  recoined  the  silver  money  in  circulation. 
Still  Dr.  von  Pettenkofer  has  observed,  that  nearly  all  the  gold  obtained  by  this  process 
contains  silver  and  platinum,  in  the  proportion  of  97  o  gold,  2*8  silver,  and  0*2 
platinum.   These  metals  are  eliminated  by  fusion  with  saltpetre  and  bisulphate  of  soda. 

At  Paris,  Frankfort,  London,  and  Amsterdam,  this  method  of  refining  is  carried  on  to  a 
large  extent  by  private  firms.  Acoording  to  the  Paris  custom,  the  refiners  return  to  their 
olients  aU  the  silver  and  gold,  retaining  only  the  copper,  and  being  paid  at  the  rate  of 
from  5  to  5i  francs  per  kHo.  of  refined  metal ;  but  if  the  aUoy  oontaLos  less  than  i-ioth 
of  gold,  the  refiners  retain  i-2oooth  of  that  metal,  paying  a  premium  of  f  franc  per 
kilo,  of  refined  metal  to  their  client.  If  the  client  desires  all  the  gold  and  silver  to  be 
returned  to  him,  the  refiner  charges  2  francs  and  10  to  68  centimes  per  kUo.,  according  to 
the  market  price  of  silver,  and  retains  all  the  copper.  Usually,  however,  a  charge  of 
5  francs  per  kilo,  is  paid  to  the  refiner.  The  value  of  the  silver  annually  refined  for  gold, 
at  and  near  Paris,  amounts  to  about  £5,500,000. 

chsmioAUyPtaxaOou.  In  order  to  obtain  perfectly  pure  gold,  that  of  commerce  is  dissolved 
in  nitro-hydroohlorio  acid,  the  solution  evaporated  to  dryness,  the  residue,  chloride  of  gold, 
dissolved  in  water,  and  that  solution  precipitated  by  a  solution  of  sulphate  of  iron : — 

Chloride  of  gold,  2(Au0l3)  \        .^,       f  ^^^^'  ^^''• 
Sulphate  of  iron,  6FeS04  J       ^^^ 

According  to  Mr.  Jackson,  gold  may  be  readily  obtained  in  a  yellow  spongy  mass,  by 
adding  carbonate  of  potassa  and  an  excess  of  oxalic  add,  to  a  concentrated  solution 
of  chloride  of  gold,  and  rapidly  heating  tJiis  solution  to  the  boiling-point : — 

Chloride  of  gold,  2(AuCl3)l        .,,      12^^fjn^JL«  a^^  firm 

According  to  Mr.  Reynolds,  peroxide  of  hydrogen  precipitates  gold  from  its  add  solution 
in  beautifully  lustrous  metallic  spangles : — 

Chloride  of  goM,2(AuC10     1      ^.^^      f  nSocmoric  add,  6C1H. 
Peroxide  of  hydrogen,  sHaOa  J      ^  ( Oxygen,  60. 

Sometimes  gold  is  predpitated  by  chloride  of  antimony  or  chloride  of  arsenic.  The 
metallic  gold  obtained  or  predpitated  by  any  of  the  above  processes  is  next  fused  with 
borax  in  a  graphite  crudble. 

piopattiM  of  ooUL  The  peculiar  colour  of  gold  is  too  well  known  to  require  description. 
The  richness  of  that  colour  is  very  much  impaired  by  even  small  quantities  of  other 
metals.  Many  of  the  Australian  sovereigns,  for  instance,  are  of  a  pale  greenish 
yellow,  due  to  the  presence  of  a  small  quantity  of  silver.  A  small  quantity  of  copper 
gives  a  red  colour  to  the  gold.  Gold  assumes  a  very  high  polish ;  is,  when  un- 
alloyed, but  slightly  harder  than  lead,  and  yet  is  the  most  malleable  and  ductile  of 
all  metals.  Its  absolute  strength  is  equal  to  that  of  silver.  The  specific  gravity  of 
gold  varies  from  19*25  to  19*55,  ^^^^  ^^^^  ^9'6»  according  to  the  mode  of  mechajiical 
treatment.  Its  co-efficient  of  expansion  by  heat  =  682  per  100"  C,  and  its  melting- 
point,  according  to  Dr.  Deville,  is  1037°.  Dr.  Van  Riemsdgk,  however,  fixes  the 
melting-point  at  1240°,  the  metal  being  molten  in  quantities  of  several  kilos,  in  an 
atmosphere  of  pure  dry  hydrogen.  Molten  gold  exhibits  a  sea-green  colour.  The 
great  value  of  gold  is  in  a  considerable  measure  due  to  its  not  being  acted  upon  by 
air,  water,  ordinary  adds,  and  alkalies ;  but,  on  the  other  hand,  even  very  smali 


OOLD.  xog 

quantities  of  lead,  antimony,  and  bismuth  impair  its  malleability  to  snoh  an  extent 
as  to  render  it  nnfit  for  use  either  as  coin  or  for  ornamental  purposes.  The 
following  metals  have  the  same  effect,  but  to  a  less  extent:  arsenic,  zinc,  nickel,  tin, 
platinum,  copper,  and  silver ;  the  two  latter  being  the  only  metals  suitable  to  alloy 
with  gold  to  make  it  sufficiently  hard  to  resist  wear  and  tear.  Gold,  of  all  the 
metals,  is  most  readily  affected  by  mercury,  even  to  such  an  extent  that  the  mercury 
present  in  the  imperceptible  perspiration  of  such  individuals  as  have  been  treated 
medicinally  with  calomel  for  some  length  of  time,  is  sufficient  to  act  very  perceptibly 
upon  their  jewellery,  while  gold  coins  kept  for  some  days  in  their  pockets  become 
Uanehed.  Gold-leaf  imparts  to  transmitted  light  a  blue-green  hue. 
AiioTiof  oou.  Pure  gold  is  used  only  for  certain  chemical  processes,  and  beaten  into 
leaf  for  gilding;  the  Staffordshire  potteries  consuming  for  this  purpose  alone 
;£6o,ooo  worth  annually.  All  other  gold,  be  it  used  for  jewellery  or  for  coinage,  is 
always  alloyed  with  copper  or  silver  to  produce  the  degree  of  hardness  requisite  for 
kammering,  stamping,  &c.  Generally  such  alloys  are  considered  as  consisting  of  so 
many  carats  to  the  unit,  the  pound  or  half-pound  being  divided  into  24  carats,  each  of 
whidi  contains  12  grains.  What  is  .termed  18  carat  gold  is  a  unit  of  24  carats  of  alloy, 
containing  18  carats  gold  and  6  of  silver  or  copper.  If  the  latter,  the  alloy  is  termed 
red;  while  if  silver  is  used,  it  is  termed  white  ;  and  if  both  metaU  are  alloyed  with 
the  gold,  the  caratation  is  termed  mixed.  In  most  countries  there  are  legally  fixed 
certain  standards  for  gold  jewellery.  In  this  country,  16,  18,  and  22  carat  gold  is 
stamped,  or  as  it  is  termed  HaU  marked;  in  France,  18,  20,  and  22  carat;  in 
Germany,  8, 14,  and  18  carat,  and  also  under  the  term  of  Jovjou  gold,  a  6  carat  gold, 
used  for  jewellery,  to  be  electro-gHt  Among  the  coined  gold  of  European  states  the 
tenn  carat  is  almost  everywhere  replaced  by  the  expression  of  so  many  parts  fine  per 

miUe.  Exceptionally  fine  gold  coins  are  the  Austrian  ducats,  23  carats  9  grains,  ^^^ 

of  gold;  the  Dutch,  or  more  correctly  Holland,  ducats,  /,^,  or  23  carats  6  to  6*9 
grains  gold.  Neither  of  these  coins  are  at  present  a  legal  tender  in  Austria  or  Holland, 
but  they  are  continually  made  at  the  Utrecht  Mint,  having  been  for  many  years  the 
dreolating  medium  in  the  North  Baltic  and  White  Sea  ports,  as  well  as  in  the  Black 
Sea,  Levant,  and  Egypt  Originally  they  were  coins  of  the  Holy  Boman  Empire 
(Germany).  The  English  sovereigns  and  half-sovereigns  are  coined  from  ^|  or 
aa  carat  gold ;  or  in  thousands  »  ^^o^ ;  the  Prussian  Friedrich  d'Or  =  ^^vS ; 
"Wilhehn  d'Or  =  21I  carat ;  the  20-fiunc  pieces  of  France,  Belgium,  Switzerland,  and 
Italy  =  21  carat  7I  grain,  or  .^^.  According  to  the  Vienna  Treaty  of  1857,  the  current 
gold  coins  of  Germany  are  made  in  1000  parts  of  900  of  gold  and  zoo  of  copper, 
the  relative  value  of  siLver  to  gold  being  taken  as  x :  15*3,  or  i :  X5'5. 

cotovoc  ooia.  Ab  all  gold  alloys,  commercially  or  industrially  used,  exhibit  colours 
different  from  that  of  pure  gold,  it  is  customary  to  produce  superficially  on  such 
ftUo^  the  deep  yellow  of  fine  metal  by  boiling  in  a  solution  of  common  salt,  saltpetre, 
and  hydrochloric  acid ;  the  effect  is  the  evolution  of  some  chlorine,  which  dissolving 
i  imall  quantity  of  the  gold,  again  deposits  it  as  a  film  of  very  pure  gold.  Electro- 
(pUing  is,  however,  frequently  substituted  for  this  colouring  process. 

'**VooiIl'*'**"  Jewellers  and  goldsmiths  generally  use  touch-needles  made  fi^m 
buying  gold  alloys.  The  resistance  of  the  streak  made  upon  the  touchstone  to  the 
action  of  dilute  nitro-muriatic  acid  is  the  test  of  the  fineness  of  the  gold ;  but  it  is 
clear  that  this  method  is  only  approximative,  and  it  cannot  be  relied  on,  as  jewellery 


no  CHEMICAL  TECHNOLOGY. 

is  often  snperficially  coated  with  a  film  of  pure  gold.  The  most  reliable  test  is 
afforded  by  cupellation,  for  which  purpose  the  gold  alloy  to  be  tested  is,  according  to 
its  colour,  fused  with  twice  or  three  times,  or  an  equal  weight  of  silver,  and  about 
ten  times  its  weight  of  lead.  This  compound  alloy  is  submitted  to  cupellation 
in  a  muffle.  The  button  which  remains  on  the  cupel  is  first  flattened  on  an  anvil, 
next  annealed,  and  rolled  into  a  thin  strip,  and  then  boiled  with  strong  nitric  acid  to 
dissolve  the  silver,  the  remaining  gold  being  washed  with  boiling  water,  dried, 
re-ignited  in  the  muffle,  and  finally,  when  cold,  weighed. 

Appucations  of  Gold.  It  is  uot  uecessaiy  to  speak  of  the  well-known  uses  of  gold,  the 
most  extensive  being  its  application  to  coinage,  and  next  that  to  gilding  and  jewellery. 
Gold  in  sheets  I  inch  thick  has  been  used  to  cover  the  large  dome  of  Isaac's  Church, 
at  St.  Petersburg,  while  three,  at  least,  of  the  countless  crosses  on  tlie  domes  of  the 
Moscow  churches  are  made  of  solid  gold  ;  a  portion  of  one  of  the  domes  of  a  ohurch 
in  the  Kremlin  is  likewise  plated  with  gold. 

QOdinc.  This  is  done  either  with  gold-leaf,  or  by  means  of  the  cold  process,  the 
wet  process,  fire-gilding,  or  electro-gilding. 

oflding  with  Gold-leaf.  Gold-leaf,  applied  in  gilding  on  wood  and  stone,  is  prepared  in 
the  following  manner : — Fine  gold  is  molten  and  cast  into  ingots,  which  are  hammered 
and  rolled  into  thin  sheets  about  an  inch  in  width,  technically  termed  ribbon.  The 
ribbon  is  cut  into  small  pieces  an  inch  in  length,  which  are  placed  between  pieces  of 
parchment,  and  beaten  out  to  a  moderate  tliinness.  Goldbeaters*  skin— the  exteiior 
membrane  of  the  intestina  crassa  of  oxen — ^is  then  substituted  for  the  parchment 
and  the  hammering  continued  until  the  metal  is  of  extreme  tenuity.  Tlie  refuse  gold 
of  this  operation  is  used  for  the  preparation  of  bronze-gold  for  painters.  The 
articles  to  be  gilded  with  gold-leaf  are  first  painted  over  with  a  suitable  vaTnish  or 
size,  and  the  gold-leaves  pressed  on  gently  mth  a  piece  of  soft  cotton-wool.  Iron 
and  steel,  as,  for  instance,  swords,  gun-barrels,  Ac,  are  first  bitten,  as  it  is  termed, 
with  nitric  acid,  next  heated  to  about  300°,  and  then  covered  with  gold-leaf. 

GUdizi£by  tiu  Cold      For  this  purpose  fine  gold  is  dissolved  in  aqua  regia ;  clean  linen  rags 

^^"^•^^  are  soaked  in  this  solution,  and  then  burnt  to  tinder,  consisting  of 

carbon  and  very  finely  divided  gold.    This  tinder  is  rubbed  on  the  article  to  be  gilded 

with  a  cork  moistened  in  brine ;  the  metallic  surface  to  be  gilded  should  be  well  polished. 

GiidinfT  by  the  This  procesB  is  carried  out  by  placing  the  article  to  be  gilded  in  either  a 
Wet  Way.  dilute  Bolution  of  chloride  of  gold  in  ether,  which  rapidly  evaporates,  or  in 
a  boiling  dilute  aqueous  solution  of  the  same  salt,  and  adding  to  it  carbonate  of  soda  or 
potassa  solution.  Iron  or  steel  should  be  first  superficially  coated  with  a  fi^y"  of  copper 
by  immersion  in  a  dilute  sulphate  of  copper  solution ;  or  these  metals,  after  being  bitten 
with  nitric  acid,  are  painted  over  with  a  solution  of  chloride  of  gold  in  ether.  A  solution 
of  chloride  of  gold  in  solution  of  pyrophosphate  of  soda  Has  lately  been  suggested  as  a 
suitable  bath. 

Fire-giiding.  Articles  of  bronze,  brass,  copper,  silver,  especially  buttons  and  ornaments 
of  military  uniforms,  are  gilt  with  an  amalgam  of  gold  and  mercury,  2  parts 
of  the  former  and  i  of  the  latter  being  applied  by  means  of  a  solution  of  nitrate  of 
mercury.  The  articles  being  next  heated  in  a  muffle,  the  volatile  metal  escapes,  leaving 
an  adhering  film  of  gold,  which  may  either  remain  dull  or  be  polished,  the  colour  being 
preserved  in  the  former  case  by  a  momentary  immersion  in  a  fused  mixture  of  nitre,  alum, 
and  common  salt,  and  immediately  after  in  cold  water.  If  it  be  desired  to  leave  only 
some  portions  of  the  gilding  dull,  the  portions  to  be  afterwards  polished  are  covered  with 
a  mixture  of  chalk,  sugar,  gum,-  and  sufficient  water  to  form  a  paste.  The  rationale  of 
the  action  of  the  fusing  mixture  is  that  chlorine  gas  is  evolved,  which,  as  the  term  nms, 
bites  the  gold.  If  it  is  desired  to  impart  a  red-gold  colour,  a  paste  of  wax,  bolus,  basic 
acetate  of  copper,  and  slum  is  spread  on  the  gilding,  and  the  article  held  over  a  dear 
fire,  the  result  being  the  reduction  of  the  copper,  which  combines  with  the  gold.  As  the 
use  of  the  so-called  quicksilver-water  (nitrate  of  mercury)  is  very  injurious  to  the 
operatives,  M.  Masselotte,  of  Paris,  coats  the  articles  with  mercury,  afterwards  with  gold, 


MANGANESE  AND  ITS  PREPARATIONS.  Iii 

ind  again  with  meronry,  by  means  of  galvaniBm.  Finally,  the  meronry  is  volatilised  by 
ignition  in  a  moifle,  bo  arranged  that  the  yapours  escape  only  in  the  flue.  According  to 
H.  H.  Strove,  so-called  lire-^t  articles  are  not  really  covered  with  a  simple  film  of  gold, 
bat  with  an  amalgam  of  gold  and  13 '3  to  i6'g  per  cent  of  mercury.  Electro  gilding  will 
be  treated  in  a  separate  section. 

(kHibK'kPiapie.  The  preparation  which  bears  this  name  was  discovered  by  Dr.  Gassins,  at 
Leyden,  in  the  year  1683.  ^^  ^  prepared  by  adding  to  a  solution  of  chloride  of  gold  a 
eertain  quantity  of  sesquichloride  of  tin.  Dr.  Bolley  prescribes  the  following  process : — 
First,  io'7  parts  of  the  double  chloride  of  tin  and  ammonium  are  digested  with  pure 
metallic  tin  until  the  metal  is  quite  dissolved,  18  parts  of  water  are  then  added,  and  the 
liquid  mixed  with  the  gold  solution  previously  diluted  with  36  parts  of  water.  The  result 
w  the  throwing  down  of  a  purple  or  black-coloured  precipitate,  about  the  chemical 
constitution  of  which  nothing  is  certainly  known.  Well  prepared  Cassius's  purple  should 
contain  39*68  per  cent  of  gold. 

saMaoiOiM.  The  doublo  salts  of  chloride  of  gold  and  sodium  (AuClsNaCl  +  zHO),  and 
the  corresponding  potassium  salt  (aAuCljjKCl-i-sHO),  are  employed  in  photography  and 
medicine. 

Manganese  and  its  Prepa&ations. 

HanguiMe.      Of  all  the  OTes  of  manganese  met  with  in  various  degrees  of  oxidation, 
only  the  peroxide,  mineralogically  known  as  pyrolnsite,  polianite,  and  technically  as 
glass-makers'  soap,  is  industrially  of  mnch  importance.    When  perfectly  pure  this 
mineral  consists  of  63 '64  per  cent  of  manganese,  and  36*36  per  cent  of  oxygen,  its 
formola  being  MnO^;  but  the  ore,  as  met  with  in  commerce,  frequently  contains 
baryta,  silica,  water,  and  sometimes  oxides  of  iron,  nickel,  cobalt,  and  lower  oxides 
of  manganese^  viz.,    Braunite,  Mns03 ;    Manganite^  Mn203,HaO ;    Hausmannite* 
MQ3O4 ;  and  various  other  minerals,  as  potassa  compounds,  lime,  &c.    In  Germany, 
the  ore  is  purified  by  most  ingeniously  contrived  machinery,  which  might  be  very 
advantageouslj  applied  to  a  great  many  other  metallic  ores  and  phosphatic  minerals. 
Manganese  is  industrially  employed  in  making  oxygen,  the  preparation  of  bromine  and 
iodine,  glass-making,  colouring  enamels,  for  producing  mottled  soaps,  in  puddling, 
iron,  and  in  dyeing  and  calico-printing,  for  preparing  permanganate  of  potassa ;  but 
the  largest  consumers  are  the  manufacturers  of  chlorine.   The  bulk  of  the  manganese 
of  commerce  is  derived  from  Germany,  which  supplies  about  700,000  cwts.  to  Europe 
umoally.    It  is  found  also  very  largely  and  of  excellent  quality  in  Spain,  as  well 
as  in  Italy,  Greece,  Turkey,  Sweden,  and  British  India. 

'*riif^S!?''      The  value  of  manganese  for  technical  purposes  depends — i.  On 

the  quantity  of  oxygen  it  is  capable  of  yielding,  or  the  quantity  of  chlorine  it  will 

evolve,  not  taking  into  account  the  O  of  the  MuO.    2.  On  the  nature  and  quantity 

of  the  substances  soluble  in  acids,  such  as  the  carbonates  of  lime  and  baxyta,  protoxide 

of  iron,  which,  not  yielding  chlorine,  saturate  a  certain  quantity  of  hydrochloric 

acid.    But  even  if  these  impurities  are  absent,  it  may  happen  that,  of  two  samples  of 

manganese,  one  requires  more  acid  than  the  other  to  evolve  the  same  bulk  of  chlorine 

gas,  as,  for  instance,  when  one  of  the  samples  contains  in  addition  to  peroxide  of 

manganese  (MnOa)  also  the  sesquioxide  (Mn^Os),  especially  if  the  latter  is  present 

as  hydrate.    3.  On  the  quantity  of  water,  which  may  amount  even  to  15  per  cent.      , 

According  to  the  experiments  of  Dr.  Fresenius,  the  most  suitable  temperature  for  drying 
a  weighed  sample  of  manganese,  in  order  to  estimate  the  water  it  contains,  is  120°,  no 
water  of  hydratation  being  expelled  at  that  heat ;  but  for  commercial  analysis  the  drying  of 
a  sample  at  100°  is  quite  sufficient,  provided  it  be  kept  at  that  heat  for  some  hours  con- 
secutively. Among  the  many  methods  proposed  for  testing  manganese,  that  originally 
invented  by  IXrs.  Thomson  and  Berthier,  and  improved  upon  by  Drs.  Will  and  Fresenius, 
is  based  on  the  fact  that  a  molecule  of  peroxide  of  manganese  treated  with  sulphuric 
acid  is  capable  of  converting,  by  the  0  given  o£F,  i  molecule  of  oxalic  acid  into  2  molecules 
of  CO,. 


1X2  CHEMICAL  TECHNOLOGY. 

,^       .,.  %jt  r\  \         /I  niol.  of  Sulphate  of  protoxide  of  mm- 

I  mol.  Peroxide  of  mangMiese,  MnOa]    ^      f  ganese,  MnSOa. 

I  mol.  Sulphtirio  awd,  H^804  f  «»v®  1  «  mols.  of  Carbonio  isid,  2C0j.     * 

I  moL  Oxaho  aoxd,  03HaO4  )  {  ^  j^^^  ^^  Water,  aHaO. 

From  the  weight  of  COa  evolyed  is  determined  the  quantity  of  peroxide  of  manganese  con- 
tained in  the  sample.  The  operation  is  performed  in  the  apparatus  shown  in  Fig.  56.  The 
flasks  A  and  b  are  fitted  with  perfectly  tight-fitting  corks,  perforated  for  admitting  the  glius- 
tubes,  as  seen  in  the  woodcut.    In  the  flask  a  is  placed  the  mixture  of  proTiously  dried 

manganese  and  oxalic  acid,  with  enough  water  to  fill  about  one-third  of 
the  flask.  The  flask  b  is  about  half -filled  with  strong  sulphuric  acid; 
the  end  of  the  tube  c  is  plugged  with  a  piece  of  wax  and  the  apparatus 
weighed.  Next  some  air  is  sucked  out  of  b,  by  means  of  the  tube  d, 
so  as  to  cause  a  small  quantity  of  add  to  run  oyer  into  a  ;  thereupon  the 
evolution  of  CO2  sets  in,  and  the  escaping  gas  passing  through  ttie  add 
in  B  is  dried.  The  suction  having  been  repeated,  the  wax  plug  at  e, 
as  soon  as  the  evolution  of  GOa  ceases,  is  for  a  moment  removed,  and 
the  suction  again  repeated  to  remove  all  the  COa  from  the  apparatus. 
The  plug  of  wax  is  now  replaced  and  the  apparatus  again  weighed; 
the  loss  of  weight  gives  by  cedculation  the  quantity  of  peroxide  of  man- 
ganese contained  in  the  sample,  if  one  holds  in  view  that  a  molecules 
GOa,(COa»88)  stand  to  z  molecule  MnOa  as  the  quantity  of  carbonio 
add  found  to  x»  If  2*98  grms.  of  dried  manganese  are  taken,  and  the 
quantity  of  COa  divided  by  3,  the  centigrammes  of  COa  lost  express  the 
proportion  per  cent  of  pure  peroxide  of  manganese  contained  in  the  sample ;  to  i  part  of 
manganese  i^  parts  of  neutral  oxalate  of  potassa  should  be  taken  for  the  experiment.  If 
the  sample  of  manganese  happens  to  contain  carbonates,  it  has,  previously  to  being  tested, 
to  be  treated  with  very  dilute  nitric  add,  and  of  course  well  washed  wiitt  distilled  water 
and  afterwards  dried.  For  other  methods  of  testing  manganese,  the  reader  is  referred  to 
Mr.  Grookes'B  work  on  "  Select  Methods  in  Chemical  Analysis.'* 

PeBMANGANATE  of  P0TA88A. 

pwmaoguutto'ofPotMM.  This  Salt  (KMn04),  used  for  disinfecting,  bleaching,  and 
other  oxidising  purposes,  and  constantly  employed  in  chomi<al  laboratories,  owes  its 
effidency  to  the  fact  that,  in  contact  with  dilute  sulphuric  acid,  it  yields  protoxide  of 
manganese  and  oxygen  (Mna07=2MnO-|-50).  The  permanganate  of  potassa  is  for 
technical  purposes  prepared  in  the  following  manner : — 500  kilos,  of  caustic  potassa 
solution  at  45°  B.  (=i'44  sp.  gr.)  are  added  to  105  kilos,  of  chlorate  of  potassa 
and  the  mixture  evaporated  to  dryness,  there  being  gradually  added  zSo  kilos, 
of  powdered  manganese,  and  the  heating  continued  to  the  fusion  of  the  mass,  which  is 
stirred  until  cold.  The  powder  thus  obtained  is  heated  in  small  iron  crudbles  to  a 
red  heat,  and  when  semi-fluid  is  cooled ;  the  mass  is  next  broken  up  and  put  into  a 
large  cauldron  filled  with  hot  water,  and  left  standing  for  about  an  hour.  The  dear 
liquid  having  been  decanted  from  the  sediment,  hydrated  peroxide  of  manganese,  is 
evaporated  to  cryistaUisation ;  180  Idles,  of  manganese  yield  98  to  100  kilos,  of  crys- 
tallised permanganate.    Approximately  the  process  may  be  eluddated  as  follows : — 

a.  By  the  fusion  of  the  potasdum  manganate  and  chloride  of  potasdum : — 
6MnOa+2KC103-f  i2K0H=  (^KJiSjiO^) +KCI+6H4O ; 

fi.  During  the  solution  of  the  fused  mass  in  water,  the  manganate  of  potasdum  is 
converted  into  hydrate  of  potassa,  hydrate  of  peroxide  of  manganese,  and  perman- 
ganate of  potassa:— 3KaMn04-f6HaO=4KOH-faKMn04-fMnOa+4HaO.  Conse- 
quently one-third  of  the  manganic  add  is  lost  by  the  formation  of  peroxide  of 
manganese.  This  also  occurs  when,  according  to  M.  Tesd6  du  Motay's  plan,  the 
converdon  of  manganate  of  potassa  into  permanganic  add  is  effected  by  sulphate  of 
magnesia ;— 3K«Mn04-f  2MgS04=2KMn04+MnOa+2KaS04-f  2MgO.  Dr.Staedeler 
therefore  suggests  that  the  manganate  of  potassa  should  be  converted  into  perman- 


ALUMINIUM.  113 

ganate  by  chlorine,  according  to  the  formula : — K2Mn04+Cl=KGl-|-EMn04.  For 
disinfectiDg  purposes  a  mixed  permanganate  of  potassa  and  soda,  or  even  the  latter 
alone,  is  nsnal ;  the  well-known  Condy's  fluid  is  a  solution  of  this  salt  in  water 
eontaining  per-sulphate,  not  proto-sulphate  of  iron.  Permanganate  of  potassa  is 
mod  to  some  extent  in  dyeing,  and  for  staining  wood. 

Alumuvium. 
(Al=Z7-4;  Sp.  gr.=2-5). 

tafcnuonof  AfauniniimL      Aluminium,  discovered  at  Gottingen,  in  1827,  ^7  ^-  Wohler, 

belongs  in  the  shape  of  its  oxide  to  the  most  widely  dispersed  as  well  as  the  most 

commonly  occurring  materials  on  our  globe.    The  properties  of  this  metal  were  more 

pirticnlarly  studied  in  1853  ^y  ^-  I^eville,  who  found  that  aluminium  is  far  less 

readily  acted  upon  in  the  molten  state  by  oxygen,  in  the  cold  by  dilute  adds  and  by 

boiling  water,  than  was  at  first  thought  to  be  the  case,  and  this  eminent  author's 

researches  gave  rise  to  the  production  of  this  metal  for  industrial  purposes,  two 

manufactories  existing  in  France,  viz.,  at  Salyndres  and  Amfreville,  and  one  in 

England,  at  Washington,  county  Durham. 

Alnminium  is  obtained  from  the  double  chloride  of  aluminium  and  sodium  by  the  aid 
of  the  latter  alkaU-metal,  which  is  prepared  for  this  and  other  purposes  by  the  ignition  of 
a  mixture  of  zoo  parts  of  calcined  so(&,  15  parts  of  chalk,  and  45  parts  of  small  coal. 
GUoridd  of  aluminium  is  best  prepared  from  bauxite,  native  hydrate  of  alumina,  which, 
baving  been  previously  mixed  with  common  salt  and  coal-tar,  is  next  heated  in  an  iron 
retort  with  chlorine  gas,  the  result  being  the  formation  of  carbonic  oxide  and  the  double 
diloiide  of  aluminium  and  sodium,  which  volatilises,  and  is  condensed  in  a  reservoir  lined 
vith  glazed  tiles.  The  salt  so  obtained  contains  iron,  and  consequently  the  aluminium 
dfiuTed  from  it  is  alloyed  with  that  metal.  The  double  chloride  of  iduminium  and  sodium 
is  eonverted  into  metallic  aluminium  by  being  heated  in  a  reverberatory  furnace  with 
flodiun ;  while  the  aluminium  is  set  free,  a  slag  is  formed  consisting  of  the  double  salt 
vith  excess  of  chloride  of  sodium.  Professor  H.  Rose,  at  Berlin,  first  used  cryolite  for 
ha  experiments  on  aluminium,  the  mineral  bearing  that  name  being  a  compound  of  the 
double  fluorides  of  aluminium  and  sodium  (AlaFl^-f  6NaFl).  This  mineral  being  treated 
at  a  high  temperature  with  sodium  yields  aluminium  and  fluoride  of  sodium,  and  the 
latter  treated  with  quick-lime  yields  caustic  soda  and  fluoride  of  calcium. 

PKpMtiea  of  ATliinfntnm.  The  colour  of  this  metal  is  intermediate  to  those  of  zinc  and 
tin ;  its  hardness  exceeds  that  of  tin,  but  is  less  than  that  of  zinc  and  copper,  and 
about  the  same  as  that  of  fine  silver ;  it  is  a  very  sonorous  metal,  rather  brittle, 
naUeable  to  some  extent,  readily  rolled  into  thin  sheets,  and  may  be  beaten  into  leaf; 
on  tbe  other  hand,  it  is  not  ductile.  Aluminium  does  not  rust  by  exposure  to  air,  and 
it  may  be  even  heated  to  redness  without  suffering  much  oxidation.  When  fused, 
however — ^it  melts  at  700** — ^it  oxidises  so  much  as  to  necessitate  the  use  of  a  flux — 
best  chloride  of  potassium — ^to  absorb  the  alumina  which  is  formed.  It  is  very 
tBadily  and  rapidly  dissolved  by  hydrochloric  acid  and  solutions  of  caustic  potassa 
Uid  soda,  hydrogen  being  copiously  evolved ;  but  the  metal  is  not  in  the  least  acted 
i^pon  by  nitric  acid.  It  does  not  amalgamate  with  mercury.  With  tin  it  yields  an 
>Uoy  of  considerable  hardness,  yet  to  some  extent  malleable ;  with  copper  in  the 
proportion  of  90  to  95  per  cent  of  copper  and  10  to  5  per  cent  of  aluminium,  it  forms 
alnminium-bronze.  This  alloy,  in  colour  similar  to  gold,  is  used  for  artificial  jewel- 
lay  and  small  ornaments.  Aluminium  does  not  alloy  with  lead.  The  aluminium  of 
ocmmerce  is  never  quite  pure,  always  containing  silicium,  found  by  Dr.  Ranunelsberg 
wan  to  10-46  per  cent,  and  frequently  present  to  07  to  37  per  cent ;  while  tlie 
quantity  of  iron  varies  from  i'6  to  7*5  per  cent. 

1 


114 


CHEMICAL   TECHNOLOGY. 


Appikations.  Alnminiam  is  now  not  bo  much  in  nse :  when  first  introdneed  alTunimnm 
jewellery  waB  the  order  of  the  day.  The  metal  is  at  present  more  nsefolly  employed  for 
email  weights,  light  tabes  for  optical  instmments,  and  to  some  extent  for  surgioal  instm- 
ments.  The  price,  howerer,  of  this  metal,  £5  12s.  per  kilo.,  is  too  high  to  admit  of  ita 
extended  nse;  while  great  lightness,  combined  with  oomparatiye  strength,  are  its  only 
prominent  qualities. 

Magnesium. 
(Mg=24;  Sp.gr.  1743). 

Macnednm.  As  an  oxide,  and  in  combination  with  chlorine  and  bromine,  as  well  as 
with'other  metalloids,  magnesiom  is  found  in  very  large  quantities,  for  instance,  in 
sea- water  and  camallite,  as  sulphate  of  magnesium,  ad  kieserite,  shoenite,  kainite,  in 
rocks  as  a  pure  carbonate,  and  as  magnesian  limestone;  further  as  a  silicate  in 
meerschaum.  Metallic  magnesium  has  but  limited  commeifcial  applications.  It  is 
silvery- white  in  colour,  somewhat  affected  by  the  oxygen  of  the  air,  but  not  more  so 
than  zinc ;  fuses  at  about  the  same  temperature  as  that  metal,  and  when  heated  a 
little  above  this  point,  bums  with  an  intensely  brilliant  white  light,  and  in  oxygen 
gas  the  combustion  is  attended  with  a  light  almost  equal  to  bright  sunlight.  Magne- 
sium may  be  readily  drawn  into  wire ;  it  is  at  the  ordinary  temperature  of  the  air  as 
malleable  as  zinc,  and  boils  and  distils  over  at  about  the  same  temperature  as  that 
metaL  Magnesium  is  at  present  only  applied  to  yield  an  intense  light  in  photography, 
and  for  signals ;  for  this  latter  purpose  it  was  extensively  used  in  the  Abyssiiiian 
campaign  (1868).  It  has  been  suggested  to  alloy  magnesium  instead  of  zinc  with 
copper. 

Magnesium  is  prepared  by  a  process  very  similar  to  that  of  aluminium  manufacture: — 
Sodium  is  ignited  with  either  chloride  of  magnesium — ^Bunsen,  Deville,  and  Gamm 
methods— or  the  double  fluoride  of  magnesium  and  sodium — Tissier's  plan — or  the  double 
chloride  of  magnesium  and  sodium — Sonstadt's  method.  Dr.  H.  Sdiwarz  employs  the 
double  chloride  of  calcium  and  magnesium,  and  M.  Beichardt  camallite,  double  chloride 
of  magnesium  and  potassimn.  Several  other  suggestions  have  been  made  as  to  the  mode 
of  preparing  this  metal,  but  it  does  not  appear  that  they  are  available  in  practice.  Mag- 
nesium is  manufactured  on  the  large  scide  by  the  Magnesium  Metal  Company  at  Man- 
chester, and  the  American  Magnesium  Company  at  Boston,  the  English  finn  producing 
i^ut  20  cfrts.  annually. 

Elbctbo-Metallurot. 

AvpHMttonoroiaTMiiim.  It  is  one  of  the  most  prominent  properties  of  the  oontiniious 
electric  current,  that  it  is  capable  of  decomposing  compound  substances  in  such  a 
manner  as  to  cause  the  constituents  to  be  deposited  on  or  near  the  place  where  the 
current  leaves  the  body  to  be  decomposed ;  this  property  is  termed  deetrolytU^  the 
body  decomposed  being  termed  electrolyte^  and  the  places  where  the  electric  current 
enters  and  leaves  deotrodes ;  the  positive  pole  of  the  battery  being  named  anode^  and 
the  negative  cathode.  The  constituents  of  the  body  decomposed  by  electricily  are 
termed  ions  (from  imv,  participle  of  ccfu,  to  go) ;  that  deposited  or  separated  at  the 
anode  (-f  pole)  being  distinguished  as  the  anion,  and  that  making  its  appearanee  at 
the  cathode  the  cation.  An  electric  current  strong  enough  to  decompose  a  molecule 
of  water  is  also  capable  of  decomposing  a  molecule  of  a  binary  compound ;  accordingly 
the  quantities  by  weight  of  a  body  decomposed  by  the  electric  current  are  propor- 

Kieeinijtie  Law.  tional  to  the  xjhemical  equivalents.  The  main  laws  of  electrolysis 
were  discovered  by  Faraday,  who  was  the  first  to  show  that  the  constituents 
attracted  by  the  anode  (+  pole)  are  electro-negative,  and  those  by  the  cathode 


ELECTRO-METALLUBar.  115 

(~  pole)  electro-poaitiTe.  As  water  is  a  common  solvent,  it  frequently  occurs  that 
dnzing  electrolysis  its  elements  are  secondarily  decomposed.  For  instance,  sulphate 
of  copper  gives,  at  the  anode  oxygen  gas,  and  at  the  cathode  metallic  copper,  because 
the  oxide  of  copper  appearing  at  this  pole  is  at  once  de-oxidised  by  the  simultaneous 
appearance  of  hydrogen :  the  oxygen  set  free  at  the  positive  plate  combines  with  the 
zinc,  forming  an  oxide,  converted  by  the  acid  into  sulphate  of  zinc;  so  that  for  every 
equivalent  (63*4)  of  copper  deposited,  one  equivalent  (65*2)  of  zinc  is  dissolved.  If, 
instead  of  sulphate  of  copper,  suitable  solutions  of  gold,  silver,  &c.,  are  employed, 
the  electro-deposition  of  these  metals  can  be  .effected. 

OMtntypiiig.  The  following  are  the  chief  technical  applications  of  electrolysis : — 
Electrotyping.  It  has  just  been  said  that  the  copper  separated  electrolytically  from 
the  sulphate  of  that  metal  is  deposited  in  a  coherent  state,  and  if  the  operation  is 
continued  for  some  time  the  layer  of  metal  may  become  sufficiently  thick  to  admit  of 
being  detached  from  the  form  upon  which  it  was  deposited.  This  principle  of  electro- 
typing  was  discovered  in  1839,  simultaneously  at  St.  Petersburg  by  Dr.  Jacobi,  and 
at  Liverpool  by  Mr.  Spencer;  among  those  who  have  laboured  to  improve  this  art, 
are  Messrs.  Becquerel,  Eisner,  Smee,  Ruolz,  Elkington,  and  many  others.  The  metallic 
solution  applied  for  the  preparation  of  casts  to  be  electrotyped  is  always  a  saturated 
solution  of  sulphate  of  copper,  and  the  form,  technically  termed  the  pattern  or 
matrix,  upon  which  it  is  desired  to  deposit  the  copper,  should  not  consist  of  any 
metal,  such  as  zinc,  tin,  or  iron,  acted  upon  by  a  solution  of  sulphate  of  copper. 
The  matrix  is  usually,  if  it  be  a  metal,  made  of  copper ;  but  more  frequently  it 
eonaista  of  gypsum  or  gutta-percha.  In  order  to  render  the  electric  current  uniformt 
the  zino  plate  of  the  battezy  is  amalgamated  by  dipping  it  in  hydrochloric  or  dilute 
sulphuric  add,  and  then  rubbing  mercury  over  the  surface  with  a  brush  or  piece  of 
soft  rag. 

■•pmdoction  of  Copper-  The  engraved  oopper-plate  to  be  reproduced  is  placed  at  the 
Plate  BngnTinst.  bottom  o£  a  wooden  trough  liaed  "with  resin  or  aaphalte.  Above  the 
plate  is  fixed  a  wooden  frame,  on  which  is  strained  a  sheet  of  bladder  or  parchment,  to 
serve  as  a  diaphragm ;  and  on  the  top  of  the  frame  a  plate  of  zinc  is  placed,  and  oon- 
neeied  with  tiie  oopper-plate  by  a  strip  of  lead.  A  saturated  solution  of  sulphate  of 
eopper  is  poured  into  the  bottom  of  the  trough,  and  in  order  to  maintain  the  saturation  a 
few  oiystals  are  added.  Above  the  porous  diaphragm  a  concentrated  solution  of  sulphate  of 
aine  is  placed.    This  plan  is  also  pursued  in  electrotyping  woodcuts,  stereotype-plates,  Ae, 

Dcporiiioa  of  Mouia.  To  reproduce  medals  and  other  small  objects  a  weak  current  only  is 
required.  The  plate  or  object  on  xrhieh.  it  is  desired  to  cause  the  deposition  to  take  place 
ia  suspended  vertically  from  the  cathode,  and  a  plate  of  the  metal  to  be  deposited  from 
the  anode ;  in  proportion  as  the  metal  is  precipitated  at  the  cathode,  it  is  dissolved  at  the 
anode,  leaving  the  concentration  of  the  fluid  unchanged.  Such  substances  as  are 
non-conductors,  wax,  paraffine,  and  gypsum,  are  first  superficially  coated  with  some 
eonducting  material,  as  graphite,  silver,  or  gold-bronze.  Gutta-percha  is  an  excellent 
material  for  easts,  owing  to  its  becoming  plastic  in  boiling  water.  According  to  M.  von 
Kobell,  a  tough  malleable  copper  is  obtiuned  by  adding  to  the  copper  solution  some 
sulphate  of  soda  and  sulphate  of  zinc.  Unless  a  rather  weak  current  is  applied,  the 
copper  is*  separated  from  its  solution  in  a  spongy  state ;  on  no  account  should  the 
eorrent  be  strong  enough  to  decompose  wata. 

"Sd'Sffflrw?"*  ^  order  to  apply  a  coating  of  gold  or  silver  to  copper,  brass, 
bronze,  or  other  metallic  alloy,  the  surface  should  be  first  very  thoroughly  cleaned  by 
boiling  in  a  caustic  soda  solution.  Smee's  battery — a  platinised  silver  plate,  and  a 
plate  of  amalgamated  zinc — ^is  now  generally  used,  the  elements  being  placed  in 
leaden  vessels  lined  with  asphalte.  The  solution  of  gold  or  silver  in  cyanide  of 
potassium  is  employed  as  the  decomposition  liquid,  in  which  the  objects  to  be  silvered 
or  gilded  are  suspended  by  a  wire  connected  with  the  negative  pole  of  the  battery ; 

I  2 


1x6  CHEMICAL   TECHNOLOGY. 

and  to  another  wire,  oonnected  to  the  poeitive  pole  of  the  battery,  is  fastened  a  piece 
of  platinitm,  which  is  also  immersed  in  the  liquid  of  the  decomposition-cell.  The 
whole  process  only  lasts  a  few  minutes,  the  cathode  during  the  time  being  moved 
backwards  and  forwards  by  hand  to  render  the  deposit  uniform.  Plates  of  gold  or 
silver  are  generally  used  instead  of  platinum  at  the  anode,  and  become  gradually 
dissolved  by,  and  maintain,  the  cyanide  solution  at  a  constant  strength. 

ooid  Bointioii.  100  gnus.  of  Cyanide  of  potassium  are  dissolved  in  i  litre  of  distilled 
water,  and  7  grms.  of  very  fine  gold  in  nitro-hydrochloiic  acid,  this  solution  being 
evaporated  to  dryness  on  a  water-bath,  the  residue  dissolved  in  distUled  water, 
and  to  the  solution  some  cyanide  of  potassium  added ;  or  the  gold  salt  obtained  on 
evaporation  may  be  dissolved  in  distilled  water,  and  the  solution  carefully  precipitated 
with  sulphate  of  iron,  the  finely-divided  gold  being  collected  on  a  filter,  next  washed 
with  distilled  water,  and  finally  dissolved  in  cyanide  of  potassium. 

BUver  Boiation.  This  solution  is  prepared  by  dissolving  well- washed  chloride  of  silver 
in  the  above  solution  of  cyanide  of  potassium,  so  as  to  obtain  a  saturated  solution  of 
cyanide  of  silver,  afterwards  to  be  diluted  with  an  equal  bulk  of  water. 

Copper,  bronze,  brass,  iron,  and  steel,  can  be  eleotro-plated  directly ;  but  poliBhed  steel, 
tin,  and  zino,  have  to  be  first  coated  with  a  film  of  copper.  German  or  nickel-silver  is  now 
generally  eleotro-plated.  The  thickness  of  the  film  of  silver  may  vaiy  from  i-42nd  to 
1.450th,  or  even  to  i -9400th  of  a  millimetre,  corresponding  to  1*240  grms.  of  silver, 
on  I  square  metre  of  surface.  Frequently  the  best  electro-plated  ware  made  in  this 
coxmtry  is  afterwards  coated  with  a  very  thin  film  of  palladium  to  prevent  the  silver  being 
a£Feoted  by  sulphuretted  fumes. 

oopper  Solution.  For  the  purposo  of  electro-coppering,  a  solution  of  oxide  of  copper 
in  cyanide  of  potassium  is  the  most  suitable  fluid ;  this  solution  is  prepared  by  first 
decomposing  a  solution  of  sulphate  of  copper  in  water,  with  the  aid  of  caustic 
potsAsa  and  grape  sugar,  so  as  to  obtain  a  precipitate  of  suboxide  (red  oxide)  of 
copper,  which,  having  been  collected  on  a  filter,  and  well  washed,  is  next  dissolved  in 
a  solution  of  cyanide  of  potassium.  For  the  purpose  of  electro-coppering  iron  and 
.steel,  M.  Weil,  of  Paris,  prepares  a  fluid — ^350  grms.  of  cupiic  sulphate,  1500  gnns.  of 
potassio-tartrate  of  soda  (sal  seignette),  and  400  to  500  grms.  of  caustic  soda  dissolved 
in  10  litres  of  water. 

M.  Oudiy's  method  of  depositing  copper  on  iron  eandelabras,  gas  lamps,  fountain 
ornaments,  Ac,  is  in  some  particulars  quite  different,  the  copper  not  being  immediately 
deposited  on  the  iron,  which  is  first  coated  with  an  impermeable  layer  of  a  kind  of  red- 
lead  paint,  graphite  being  afterwards  rubbed  in  for  the  purpose  of  rendering  the  surface  of 
the  object  a  conductor.  To  obtain  a  coatiog  of  copper  i  mUlim.  in  thickness,  such  articles 
as  candelabra  are  left  in  the  solution  for  4^  days ;  the  ornamental  fountains  of  the  Place 
la  Concorde,  Paris,  have  been  for  a  period  of  two  months  in  the  solution. 

zinc  and  Tin  Solution.  To  coat  irou  with  zuic,  a  solutiou  of  the  sulphato  of  the  latter 
metal  may  be  used,  but  the  so-called  galvanised  iron  of  commerce  is  made  by  a 
different  process,  viz.,  by  placing  the  iron  to  be  coated  in  a  bath  of  molten  zinc 
covered,  for  the  purpose  of  preventing  oxidation,  with  a  layer  of  molten  tallow  or 
paraffin.  For  the  purpose  of  electro-tinning,  a  solution  of  tin  in  caustic  soda  is 
employed,  the  anode  being  of  tin. 

^  A  so-called  electro-steeling,  really  a  deposit  of  iron  on  the  copper  plates  used  for  engra- 
ving, is  effected  by  M.  Meidmger  in  the  following  manner : — The  bath  is  a  solution  of  sul- 
phate of  iron  and  chloride  of  ammonium ;  to  the  copper  pole  of  tiie  battery  a  plate  of 
iron,  and  to  the  zinc  pole  the  engraved  copper-plate,  are  connected.  These  steeled  plates 
serve  for  as  many  as  5000  to  15,000  impressions.  This  method  has  been  applied  to 
stereotyping  with  great  success,  and  indeed  the  deposition  of  iron  eleetrolytically  is 
a  valuable  addition  to  technology. 


ELECTRO-METALLURGY.  117 

[  hj  otifwtam.  This  process  is  based  npon  the  fact  that,  under  oertain  conditions,  the 
Ribstanoefl  separated  at,  combine  with  the  electrodes,  the  consequence  being  that  the 
electrode  is  gradually  corroded  and  destroyed.  The  copper-plate  intended  to  be  etched  is 
nmformly  covered  with  a  mixture  of  4  parts  of  wax,  4  of  asphalte,  and  i  of  black  pitch ; 
the  design  is  then  drawn  or  rather  scratched  with  proper  tools  through  this  non-con- 
dneting  layer,  and  the  plate  attached  to  the  anode  of  a  galvanic  battery,  and  placed  in 
s  solution  of  sulphate  of  copper,  containing  also  a  copper-plate  connected  to  the  negative 
electrode  of  the  battery.  On  this  plate  is  deposited  the  copper  of  the  solution,  while  the 
oxygen  of  the  decomposed  water,  with  the  sulphuric  acid,  act  upon  the  portions  of  metal 
not  covered  with  the  protective  layer  and  produce  the  etching. 

ibwiMhniiiy,  Or  galvanic  painting,  consists  in  depositiDg  thin  films  of  oxide  of  lead  in 
ft  coherent  state  on  metal  plates,  thus  producing  Nobili's  colours.  The  oxide  of  lead  is,  for 
this  purpose,  best  dissolved  in  caustic  potassa  or  soda  solutions.  In  England,  this  method 
of  ornamenting  is  not  much  applied ;  but  at  Nuremburg,  where  toys  are  largely  manuf ac- 
tnred,  this  process  is  very  simply  carried  out  by  placing  the  metallic  object,  previously 
connected  witii  the  cathode  of  a  battery,  in  a  concentrated  solution  of  oxide  of  lead  in 
cftostie  potassa,  while  to  the  anode  is  afi^ed  a  piece  of  platinum  foil. 

ihrt>»8uiB04jpius.  For  the  purpose  of  reproducing  printing-types  by  galvanic  means, 
ft  wax  impression  of  the  type  is  placed  in  the  deposition-cell.  This  operation  is  also 
employed  for  the  reproduction  of  woodcuts,  gutta-percha  being  used  as  a  mould. 

etnhovH»»j'  By  this  name  is  understood  a  process  for  reproducing  woodcuts,  but  it  is 
now  altogether  obsolete,  having  been  superseded  by  electro-typiog.  A  further  disadvantage 
wis,  that  the  glyphographic  plates  could  not  be  printed  from  the  same  matrix  as  type. 

Oftnuogmghj.  At  the  suggestion  of  Dr.  von  Eobell,  the  reproduction  of  some  kinds  of 
dnwingB  and  pictures  has  been  tried.  In  order  to  enable  exact  copies  to  be  printed  from 
plates  deotrolytically  obtained  from  the  original  drawings  ;  but  this  method,  of  very  difficult 
ftod  costly  execution,  is  superseded  by  photography. 


(ii8) 


DIVISION  II. 
obude  matxrialb  and  fb0du0t8  of  oukmioal  imdu8tby. 

Carbonate  of  Potassa. 

(KaG03=i38'2 ;  in  loo  parts,  68*2  potassa  and  31*8  parts  oarbonio  add.) 

^'^^'^^'udStlL****"  ^®  substance  known  in  chemistry  as  carbonate  of  potassa  is 
generally  termed  potash,  because  it  was  formerly  obtained  from  wood-ash,  which, 
after  lixiviation  with  water,  was  evaporated  to  dryness  in  cast-iron  pots.  Potassa 
occurs  native  in  considerable  quantities,  but  never  free,  being  combined  with  silica  in 
many  minerals,  also  in  combination  as  chloride  of  potassium,  sulphate  of  potassa, 
and  in  various  plants  with  organic  acids.  The  following  are  the  sources  whence 
potassa  is  industrially  obtained. 

I.  The  salt  minerals  of  Stassfrirt  and  Kalucz ;  products — 
.  .  camallite,  sylvin,  kainite,  and  schoenite. 

Ittorganio  sources  ^       jj   Feldspar  and  similar  minerals. 

m.  Sea-water,  and  the  mother-liquor  of  salt  works. 

IV.  Native  saltpetre. 

V.  The  ashes  of  several  plants. 

VI.  The  residue  of  the  molfiisses  of  beet-root  sugar  after 
distillation. 

VJLl.  Sea- weeds,  as  a  by-product  of  the  manufacture  of  iodine. 

,  Vm.  The  suint  of  the  crude  wool  of  sheep. 


of  Potassa. 


B.  Organic  sources  of 
Potassa. 


wJSSSt^sJitMSSS.  ^'  '^®  ^®^  abundant  salt-rocks  near  Stassfurt,  in  Prussia,  and 
Kalucz,  in  Hungary,  chiefly  yield  camallite,  sylvin  (CIK),  and  kainate,  a  compound 
of  sulphate  of  potassa  and  magnesia  with  chloride  of  magnesium.  Camallite,  so 
named  in  honour  of  Camall,  a  Prussian  mining  engineer,  consists,  in  100  parts, 
leaving  the  bromine  out  of  the  question,  of — 

Chloride  of  potassium    27 

Chloride  of  magnesium 34 

vva«eraa*     •••     •••     •••     ••■     •••     39 

100 
Fonnula— KCL,  Mg  |  ^^-f  6HaO.    This  salt  is  applied  in  the  manufacture  of— 

a.    Chloride  of  potassium. 
p.    Sulphate  of  potassa. 
7.    Potash  (carbonate). 


CARBONATE  OF  FOTASSA. 


rrg 


•L  IV«p«ntion  of  Chloride  of  Potossiimi. — Aocording  to  the  prooess  origmallj 
i»toiit«d  (t86i)  by  Hr.  A.  Frank,  the  abrauia  B&lta  oie  ignited  in  a  reverberateiy 
taioaee,  with  or  withont  the  aid  of  b.  cmrrent  of  steam,  and  next  lixiviated  with  water, 
the  resulting  liqnor  jielding  chloride  of  potaBsinm.  The  rationaU  of  this  prooess 
is: — I.  That  the  camsllito  of  the  abraiuii  salts  is  separated  by  the  action  of  the  water 
into  chloride  of  potaaaiDm  and  chloride  of  magneaiom.  2.  The  latt«T  salt  on  being 
ignited  in  a  current  of  ateam  is  decomposed  into  hydrochloric  acid,  which  escapes, 
and  magnesia,  which  is  practioaUj  insoluble  in  water,  and  which  consequently  remains. 
Hiii  process  is  not  found  to  answer  well  on  the  large  scale,  because  the  abranin 
Mhs  contain  other  chlorides,  the  chloride  of  sodiont  and  tachydrite,  by  the  presence 
of  which  the  deeompoaitiou  of  the  camallite  is  hindered.  Dr.  GrQneberg.  tberefore, 
mggseted  that  the  abranm  salts  ahonld  be  first  mechanically  purified,  that  is  to  say, 
the  different  components  of  the  abraum  salts  shonld  be  separated  from  each  other 
■eoording  to  thdi  liiying  specific  gravity,  which  for — 

Camallite  is=r6i8 

Chloride  of  sodium  is  =  a'aoo 

Kieserite  i8  =  3'5i7 

The  abrkinn  ealt  having  been  ground  to  a  coarse  powder  is  passed  throngh  sierea, 
tod  treated  as  minerals  are  in  metsUurgical  processes,  with  the  difference  that,  instead 
of  water,  which  of  oonrBe  would  dissolve  tJie  salts,  a  thoroughly  ccmcentrated  solution 
of  chloride  of  magnesium  is  applied,  this  solution  not  acting  upcm  the  salts,  and  being, 
nuir«over,  obtained  as  a  by-product  in  enormonsly  targe  quantitiea.  The  above- 
nenlioneci  salts  settle  in  layers  according  to  their  densities,  the  camallite  forming 
the  upper,  and  the  kieserite  the  lowest  layer.  The  camallite  is  at  once  applied  to 
the  pieparatioQ  of  chloride  of  potassium  1  the  middle  layer  of  common  salt  is  so  free 
from  other  foreign  salts  as  to  be  fit  for  domestio  nse ;  the  kieserite,  after  baring  been 
•uhed  with  cold  water  t«  remove  any  adhering  chloride  of  sodium,  is  applied  to  the 


Fia.  57. 


Fio.  jB. 


nann&ctnre  of  Butphate  of  potassa,  to  be  presently  described.  However,  the  greater 
umber  of  mann&cturets  at  Stassfuri  prefer  another  plan,  applying  the  fire  following 
Dperktionslo  the  abranm  salts  as  delivered  from  the  salt  qnarries: — i.  Lisiviation 
of  the  camallite  with  a  limited  qnantity  of  hot  water,  sufficient  to  diaaolve  the 
chlorides  of  polassiiim  and  magnesiiun,  leaving  the  bulk  of  the  common  salt  """I 
1  sulphate.      1.    Crystalliaing  the  chloride  of  potassium   by  artificially 


CHEMICAL  TECmiOLOaY. 

Evaporstiug  and  cooling  the  motber-liqiior  to  produce  a  Becond  jield 
of  dystollised  chloride  of  potsBsiiiiii.  4.  Again  evapomtiiig  and  oooliog  the  mother- 
liquor,  which  yieliB  the  double  salt  of  the  ohioridea  of  potaadnm  and  magneainm, 
01  artifici&l  oaraallite,  which  is  next  treated  in  the  same  manner  as  the  native  smlt- 
5.  Washing,  drjing,  and  packing  the  chloride  of  potassium. 

I.  The  comftllite  is  pntinto  out-iron  liiiviationTesselBand'mixed  with  tbree-tonithsot 
its  weight  of  water,  preriouel;  employad  for  the  washing  of  ornde  ohloride  of  polaasinm, 
and,  therefore,  contaimng  a  large  ^nantity  of  common  salt  and  soma  ohloride  ol 
potaBsintu :  steam,  at  izo",  and  at  a  preBsare  of  30  lbs.  to  the  aqnore  inch,  is  forced 
throogb  the  perforated  circnlarlj'  bent  tube,  t  (Fig.  59)  at  the  bottom  of  the  vessel  In 
Ur.  Donglaa'B  woilu  the  lixiviation  vessels.  Figs.  57, 
Fio.  59-  5S,  and  59,  have  a  cnbical  cupaoit?  of  xo  tons.     Tb^ 

are  closed  with  a  tightly&ttiug  lid,  an  opening  being 

cut  for  the  escape  of  surplns  Bteam.  The  stirrer,  c,  is 
kept  in  motion  by  steam  power.  When  the  admission 
of  steam  and  the  stiniog  has  been  oontiDned  abont 
three  hours,  the  contents  of  the  vessels  are  left  at  rect 
tor  two  dajB,  after  which  the  satnrated  solution  has  a 
density  of  33°  B.  =  i-i36  sp.  gr.,  and  is  forced  bj  steam 
pressure  Into  crygtallising  vesMlx;  the  residne  in  tlw 
^KiviatioD  vesseb,  amounting  to  about  one-third  of  the 
weight  of  the  camallite,  is  agun  treated  as  described. 

a.  The  oi7BtaUiBation  veBsels  are  of  wood  or  sheet- 
iron,  1-20  meb^B  diameter,  by  15  to  eg  metres  height. 
The  chloride  of  potaasiom  crjBtftiliaes  in  combinatioD 
with  common  salt,  and  is  strongly  impregnated  with  the 
very  soluble  and  highly  deliqueeceut  ohloride  of  mag- 
neainm ;  the  salt  deposited  at  the  sides  of  the  veeael 
oontaina  npwarda  of  70  per  cent  of  chloride  of  potaasinm,  while  that  collected  at  the 
bottom  oODtainl  only  55  per  oent.  If  shallow  vessels  are  employed,  the  saline  solntioi) 
cools  more  rapidly,  and  a  finer  grained  salt  is  obtained,  mixed,  bowerei,  with  itnpnritiea, 
and  requiring  more  washings,  au  operation  which,  with  the  coarse  salt,  has  only  to  be 
performed  once  to  yield  80  per  cent  chloride  of  potassium.  Most  of  the  chloride  of 
potassium  sold  by  the  manufaiiturers  oontoins  So,  and  in  some  cases  S5  and  90,  per  cent 
of  tfaepure  salt. 

3.  The  eraporation  of  the  first  mother-liquor  is  carried  on  ia  iron  pans  of  Tariona 
■izes.    As  by  the  evaporation  common  «^t  ia  largely  deposited,  which  has  a  tendency  to 

Fio.  Go. 


cake  at  tbe  bottom  of  the  pans,  and  cheek  the  onudnotion  of  heat,  the  pans  are  set  so  a* 
toreceiTB  the  action  of  tbe  flame  only  on  the  aides  (Fig.  Gi),  and  the  hquid  kept  conttaotly 


CARBONATE  OF  POTASSA.  X2i 

Btimd.  When  fhe  Hqnor  has  been  reduced  to  about  two-thirds  of  its  bnlk,  with  a  density 
of  33**  B.B  1*298  sp.  gr.,  it  is  run  into  the  crystallising  vessels.  The  mass  remaining  in 
the  eraporating  pan,  consisting  of  60  to  65  per  cent  common  salt,  6  per  cent  chloride  of 
potassiiim,  and  30  per  cent  donble  sulphates  of  magnesium  and  potassimn,  is  used  as  manure. 
Steam-heated  evaporating  pans,  represented  in  Fig.  60/  are  employed  by  some  manu- 
fsetnrers ;  the  four  steam-tubes,  t,  are  placed  parallel  to  the  sides  of  the  vessel,  and  open  in 
II,  the  waste  steam  being  carried  off  by  the  tube  t'.  As  might  be  expected,  the  concen- 
tration of  the  liquor  is  more  rapidly  p^ormed  by  means  of  steam,  but  the  crystallisation 
of  the  second  crop  of  salt  is  poorer,  yielding  only  50  to  60  per  cent  chloride  of  potassium, 
and  requiring  two  to  three  washings  to  accumulate  80  per  cent  pure  potassium  salt. 

4  and  5.  The  second  mother-Uquor  is  again  concentrated  by  evaporation  to  35**  B. 
a  Bp.  gr.  1*299,  yielding  a  saline  mass  similar  to  the  residue  of  the  first  evaporation,  and 
to  which  it  is  added  and  used  as  a  manure.  On  being  submitted  to  crystallisation,  this 
last  liquor  yields  artificial  carnallite,  treated  as  the  salt  obtained  from  the  native  deposit, 
giTing,  however,  with  less  labour  80  to  90  per  cent  chloride  of  potassium.  The  chloride 
of  potasflimn,  after  washing  with  pure  water,  is  dried  either  in  rooms  heated  by  steam,  or 
in  a  moderately  heated  reverberatory  furnace.  The  dry  salt  is  then  packed  in  casks, 
each  containing  about  500  kilos. 

fi.  The  preparation  of  sulphate  of  potassa  may  be  effected : — 

a.  From  chloride  of  potassium  and  sulphuiio  aoid. 

b.  By  Longmaid's  (see  Soda  Manufacture)  roasting  process,  viz.,  the  calcination 

of  chloride  of  potassium  and   sulphuret   of  iron,   and  in  metaUurgical 
processes  where  chloride  of  potassium  is  used  instead  of  chloride  of  sodium. 

e.  From  chloride  of  potassium  and  kieserite. 

d.  From  kainite. 

The  conversion  of  chloride  of  potassium  into  the  sulphate  of  potassa  by  double 
decomposition  with  sulphate  of  soda  is  not  practicable  on  the  large  scale,  as  the  two  salts 
have  a  tendency  to  form  double  salts ;  therefore,  the  methods  a  and  b  are  practically 
available  only  under  certain  peculiar  conditions.  A  small  quantity  of  chloride  of  potassiTmi, 
obtuned  in  Scotland  as  a  by-product  of  the  preparation  of  kelp,  is  converted  into  sulphate 
of  potassa  by  the  means  in  use  for  the  manufacture  of  soda  (quod  vide).  The  leading 
points  in  the  manufacture  of  sulphate  of  potassa  by  the  aid  of  the  sulphuric  acid  contained 
in  kieserite  are  the  following : — First  schoenite  and  carnallite  are  prepared  by  dissolving 
ebloride  of  potassium  and  Ueserite  in  boiling  water,  and  crystallising  the  solution  thus 
obtained : — 

4  mols.  Kieserite  1  =»  /  ^  mols.  Schoenite. 

3  mols.  Ohloride  of  potassium  J         ( i  moL  Oamallite. 

The  schoenite  and  artificial  carnallite  are  separated  by  crystallisation,  and  the  former 
decomposed  by  chloride  of  potassium : — 

'4  mols.  of  Sulphate  of  potassa. 


4  mols.  Schoenite 

3  mols.  Chloride  of  potassium 


2  mols.  of  Schoenite. 
^  I  mol.  of  Carnallite. 


The  sulphate  of  potassa  crystallises  first,  and  is  simply  purified  by  washing  with  water. 
As  kainite  is  found  in  very  large  quantities  among  the  salme  deposits  near  Stassfurt,  it  is 
also  used  for  the  preparation  of  sulphate  of  potassa ;  by  a  simple  washing  with  water, 
the  chloride  of  magnesium  contained  in  the  kainite  is  removed,  and  the  salt  thus  converted 
into  schoenite : — 

-Chloride  of  magnesium}  =*  Schoenite. 

The  sohoenite  is  then  employed  in  the  manufacture  of  sulphate  of  potassa  by  being 
treated  witii  chloride  of  potassium ;  the  sulphate  of  potassa  thus  obtained  is  used  either 
in  alum  or  potassa  mani^acture,  or  as  a  potassa  manure. 

7.  Preparation  of  Carbonate  of  Potassa  or  Mineral  Potash. — Very  many  suggeetions 
have  been  made  for  converting  by  simple  means  ohloride  of  potassiiun  and  sulphate 
of  potassa  into  carbonate  of  potassa,  industrially  known  as  potash ;  bnt  most  of 
the  plans  proposed  are  unfit  for  use  on  the  large  scale,  and  even  the  method  adopted 
by  Leblanc  for  soda  manufacture  has  not  been  in  every  case  successful  when  applied 
to  the  production  of  chloride  of  potassium.    At  Kalk,  on  the  opposite  bank  of  the 


Z2a  CHEMICAL  TECHNOLOOY. 

Khine  to  Cologne,  a  process,  said  to  be  based  npon  Leblanc's  method,  is  snccessfblly 
in  operation,  but  the  real  arrangements  are  carefully  kept  secret,  no  one  being  allowed 
to  visit  the  works ;  however,  it  is  stated  that  snlphate  of  potassa  containing  schoenite 
is  mixed  with  chalk  and  small  coals,  and  calcined,  the  calcined  mass  being  lixiviated 
when  cool,  and  yielding  carbonate  of  potassa  in  solution,  and  a  residue  of  sulphide 
of  calcium. 

""^^fro^rKo?^"*  ^-  Potassa-salts  from  feldspar.  It  has  been  found  by  the 
analysis  of  minerals  entering  largely  into  the  constitution  of  rocks,  that  potassa  is 
present  in  considerable  quantities.  The  following  may  be  taken  as  instances: — 
Orthodase,  or  potash  feldspar,  contains  from  lo  to  i6  per  cent ;  potash  mica,  8  to  lo 
per  cent ;  trachyte,  glaukonite,  phonoUthe,  7  to  8  per  cent ;  porphyry,  granulite,  and 
mica  schist,  6  to  7  per  cent ;  granite,  syenite,  gneiss,  5  to  6  per  cent ;  dolerite,  basalt, 
kaoHn,  and  clay,  i  to  2  per  cent. 

Before  the  discoveiy  of  the  potassa-salt  deposits  at  Stassfurt,  Ealuos,  and  elsewhere, 
there  were  many  suggestions  made  as  to  the  obtaining  of  the  potassa  on  the  large  seale ; 
but  at  present  tms  branch  of  industry  lies  dormant,  notwithstanding  the  theoretical  value 
of  Mr.  Ward's  (1857)  suggestion  that  feldspar  should  be  mixed  with  fluor-spar,  both  finely 
pulverised — ^the  fluorine  being  equal  in  quantity  to  the  potassa  contained  in  the  fluor-spar 
— a  mixture  of  chalk  and  hydrate  of  lime  added,  the  mass  ignited  in  kilns  or  gas-retorts, 
and  finally  treated  with  water  to  yield  caustic  potassa  and  a  residue,  which,  after  another 
calcination,  yields  excellent  hydraulic  lime. 

**»^-^g,f«"»  in.  Dr.  Usiglio  found  that  the  water  of  the  Mediterranean  contains  in 

10,000  parts  by  weight  5*05  parts  of  potassa ;  and  after  the  removal  of  the  more 

readily  ciystsllisable  salts  left  by  the  spontaneous  evaporation  of  the  water  by  the 

sun's  heat,  this  natural  mother-liquor  is  applied  to  the  preparation  of  potassA-salts, 

according  to  the  following  method : — 

The  process  now  in  use  near  Aigues  Mortes,  and  other  localities  in  proximity  to  the 
Mediterranean,  was  invented  by  Professor  Balard,  the  discoverer  of  bromine,  and  yields 
from  I  cub.  met.  of  mother-liquor,  equal  to  about  75  cub.  mets.  of  sea-water,  at  28^  B. 
B  1*226  sp.  gr.,  40  kilos,  of  sulphate  of  soda,  120  kilo%.  of  refined  common  salt,  and 
10  kilos,  of  chloride  of  potassium.  It  has  been  found,  however,  that  this  method  is  rather 
costly,  and  the  mother-liquor  is  generally  left  to  spontaneous  evaporation,  yielding  the 
three  following  kinds  of  salt:— a.  The  first  salt  separated  from  a  liquor  of  32**  B. 
B  1*266  sp.  gr.,  only  impure  common  salt.  h.  The  second  salt  separated  from  a  fiquor, 
32**  to  35^  B.  B  1*266  to  1*299  Bp*  gr.,  consisting  of  equal  parts  of  common  salt  and  Epsom- 
salt,  and  termed  mixed  salt.  e.  The  third  sidt,  35"  and  37**  B.  «  1*299  to  1*321  sp.  gr., 
termed  summersalt.  The  second  salt  having  been  dissolved  in  fresh  cold  water,  tiie 
solution  is  placed  in  Garry's  ioe-making  machine,  and  yields  sulphate  of  soda  by  an 
exchange  of  its  constituents.  The  third  salt  is  dissolved  in  boilmg  water,  yielding  on 
cooling  half  its  potassa  as  kainite.  The  mother-liquor,  containing  camallite,  common 
salt,  and  bitter,  or  Epsom-salt,  yields  sulphate  of  soda,  and,  when  treated  with  chloride 
of  magnesium,  all  its  potassa  as  camallite,  which,  by  being  washed  with  water,  yields 
chloride  of  potassium.  In  this  way  it  has  become  possible  to  obtain  45  per  cent  of  the 
potassa  of  the  mother-liquor  as  chloride  of  potassium,  and  55  per  cent  of  schoenite,  which 
is  converted  into  sulphate  of  potassa. 

aS!?o?p?1^  rV.  The  residue  left  from  the  ignition  of  the  organic  matter,  or  wood, 
as  it  is  usually  termed,  of  plants,  contains  those  mineral  substances  which  the  plant 
has  taken  from  the  soil,  chiefly  potassa,  soda,  lime,  magnesia,  smsll  quantities  of  the 
protoxides  of  iron  and  manganese,  combined  with  phosphoric,  sulphuric,  silicic,  and 
carbonic  acids,  and  also  with  the  haloids.  These  combinations  are  not,  however,  the 
same  as  those  existing  in  the  living  plant,  because  the  high  temperature  of  the 
ignition  has  the  effect  of  changing  the  affinities.  Plants  growing  near  the  sea  gene- 
rally contain  large  quantities  of  soda,  while  those  inland  contain  generally  more 
potassa.  The  quantity  of  ash  varies  not  only  for  different  kinds  of  plants,  but  for 
various  parts  of  the  same  plant,  verj'  succulent  plants  and  the  most  succulent  parts 


CARBONATE   OF  P0TA88A,  133 

genenDy  yield  the  largest  quantity  of  ash ;  herbs  yield  more  ash  than  shrubs,  shrubs 
more  than  trees,  and  the  leaves  and  bark  of  these  more  than  the  wood.  It  is  evident 
(hat  the  inorganic  matter,  chiefly  alkaline  salts,  being  contained  in  the  juice  of 
plants  in  «  soluble  state,  the  quantity  must  of  necessity  be  greatest  in  the  juicy 
and  succulent  parts. 

Dr.  B6ttg0r  found  the  ash  of  beeoh-wood  to  contain — 

21*27  V^  <)^^t  of  soluble  salts, 

7873    »i    M     of  insoluble  salts. 
The  soluble  salts  were  found  to  be —  . 

Carbonate  of  potassa     . .     ..  15*40  per  cent 

Sulphate  of  potassa       . .  2*27    „    „ 

Carbonate  of  soda 3*40    ,,    „ 

Chloride  of  sodium        . .     . .  0*20    „    „ 


21*27  per  cent 

The  value  of  an  ash  for  the  manufacture  of  potash  is  chiefly  dependent,  in  the  first 
place,  upon  the  quantity  of  potassio  carbonate  it  will  yield,  upon  the  abundance  of  the 
wood  or  other  vegetable  product,  and  the  cost  of  labour.  The  undermentioned  woods 
jield,  on  an  average,  for  1000  parts,  the  following  quantities  of  potash — 

Pine o'45         Beech-bark 6*00 

Poplar o'75         Dried  ferns 6:26 

Beech 1-45  Stems  of  maize  (Indian  com) . .     . .  17*50 

Oak i'53         Bean-straw 20*00 

Box-wood 2*26         Sxmflower-stems        20*00 

Willow 2*85         Nettles 25*03 

Elm 3'go        Vetch-straw        27*50 

Wheat-straw      3*go         Thistles       35*37 

Bark  from  oak-knots        4*20  Dried     wheat-plant     previous     to 

CotUm-grwaa{EriophoriunvaginiUuim)  5*00            blooming 47*00 

Bashes 5*08         Wormwood 73*oo 

Vine-wood 5*50        Fumitory , .  79*00 

Barley-straw      5*80 

According  to  M.  Hoss,  1000  parts  of  the  following  kinds  of  wood  yield — 

Ash.  Potash.  Ash.  Potash. 

Pine        3-40  0*45         Willow     28*0           2*85 

Beech     5*80  1*27         Vine 34*0           5*50 

Ash i2'2o  0*74  Dried  ferns      . .     . .  36*4           4*25 

Oak 13*50  1*50  Wormwood      ..     ..  97*4  73*00 

Ehn 25*50  3*90  Fumitory         ..     ..  219*0  79*90 

The  preparation  of  potash  from  vegetable  matter  is  effected  in  three  operations,  viz. : — 

a.  The  liziviation  of  the  ash. 

b.  The  boiling  down  of  the  crude  liquor. 
e.  The  calcination  of  the  crude  potash. 

The  combustion  of  the  vegetable  matter  should  be  so  conducted  as  to  prevent  its 
becoming  too  violent  and  giving  rise  to  the  combustion  of  some  of  the  reduced  potassa- 
■alt ;  nor  should  too  strong  a  current  of  air  be  admitted  for  fear  of  the  ash  being  mechani- 
eaUy  carried  off.  A  distinction  is  made  abroad — ^no  potash  from  wood  or  other  vegetable 
inatter  being  produced  io  the  United  Kingdom,  nor  wood  used  as  fuel  in  sufficient  quanti- 
ties to  yield  ash  for  the  preparation  of  potash — between  the  ash  obtained  by  the  com- 
biutlon  of  the  refuse  wood  of  forests  and  the  ash  from  wood  used  as  fuel,  the  f orziier 
being  termed /oreft-  and  the  latter /ueZ-ash.  As  ash  from  other  fuel  than  wood  may  be 
Biixed  with  fuel-ash,  a  sample  may  be  roughly  tested  by  liziviation,  and  the  density  of  the 
hqiior  taken  by  the  areometer,  the  hi^er  the  specific  gravity  the  larger  the  quantity  of 
•okble  salts.  Formerly  ^e  forest-aeh  was  purposely  prepared,  and  sold  to  potash- 
Ixnlers.  There  is  still  known  in  Eastern  Prussia  and  Sweden  a  material  termed  okras  or 
oekm ,  holding  a  position  intermediate  to  crude  ash  and  potash. 

a*  The  liziviation  of  the  ash  effects  the  separation  of  the  soluble  from  the  insoluble  saline 
"Batter,  the  former  amounting  to  about  25  to  30  per  cent  of  the  entire  weight  of  the  ash. 
^s  operation  is  carried  on  in  wooden  vessels  shaped  like  an  inverted  truncated  cone,  and 
provided  with  a  perforated  false  bottom,  which  is  covered  with  straw  ;  in  the  real  bottom 
*  tap  is  fized  for  removing  the  liquor.     If  the  liziviation  is  systematically  carried  on, 


134  CHEmCAL   TECHNOLOGY. 

■ereral  of  these  TeaaelB  ue  placed  together,  forming  what  is  termed  b  batter]',  uid  nnder 
•Mh  •  tank  to  reoeive  the  Ui^nor.  The  aeh  to  be  lijdfiated  ia  flrtt  Bitted  bom  the  oomm 
purtiale*  ol  ehaiooal,  next  put  into  a  mauM  sqaore  water -ti^bt  wooden  box,  and  thoroaghl; 
eatorated  with  water  lor  at  least  twenty -fooi  honis.  B;  this  prooeediug  the  lixiiiatiou  is  - 
greatly  asusted,  and  the  eilioate  ol  potassa  to  some  extent  decomposed  by  the  aotion  ot 
the  oorbonia  add  of  the  atmosphere.  The  next  step  is  to  tranafer  the  wet  ash  to  the 
lillTiation  Tessel,  oare  being  taken  to  pieas  it  tightly  down  on  to  the  false  bottom  ;  oold 
vater  is  then  ponred  in,  until  the  liqnor  begins  to  rnn  otT  at  the  tape  left  open  for  that 
purpose.  The  liquor  which  runs  oS,  after  the  water  has  remained  sDine  little  time  in 
oontaot  with  the  ash,  ia  foond  to  contain  abont  30  per  eent  of  salable  salts,  afterwards 
deeieasing  to  about  10  per  cent,  when  hot  water  is  employed  to  complete  the  lixiviation. 
The  insoluble  resldne  left  in  the  lixiTiation-tub  is  of  volne  as  a  mannre,  on  aoconnt  of  the 
phosphate  of  lima  it  contains,  and  is  also  med  in  makiog  green  bottle-glass,  and  for 
building  np  saltpetre-beda. 

(.  Boiling  down  the  liquor.  The  liqnor  obtained,  by  liiiTiation  is  ot  a  brown  ooloui, 
owing  to  organic  matter,  hmmn  or  nlmine,  whioh  the  carbonate  ot  potasaa  has  dissolved 
from  the  small  chips  of  imperfectl;  bnmt  charcoal.  The  evaporation  is  carried  on  in 
large  shallow  iron  pons,  fresh  liqnor  being  from  time  to  time  added,  and  the  operatioa 
oonCinned  until  a  sample  of  the  hot  conoentiated  hqaor  exhibits  on  cooling  a  crystalline 
Bohd  mass.  When  tble  point  is  reached  the  fire  is  gradually  extinguished,  and  as  soop  as 
the  contents  of  the  pan  are  sufficiently  cold  to  handle,  the  solid  salt  mass  is  broken  np ; 
its  colour  is  a  deep  biown.  This  crude  produo^,  containing  about  6  per  eent  water,  is 
known  in  the  trade  as  omde,  or  lump.potoshi^  It  is  evident  that  thU  method  of  boiling 
down  may  eangs  cousiderabie  damage  to  the  iron  pans,  therefore  in  many  instancee  tho 
operation  is  oonduoted  in  a  somewhat  3iSerent  manner.  The  liquid  is  kept  stirred  with 
iron  rakes,  and  the  salt,  instead  of  forming  a  hard  solid  mass,  is  obtained  as  a  graaolar 
powder,  containing  apwards  of  iz  per  cent  water.  Some  manutactorerG  first  separate  the 
sulphate  of  potash,  which,  being  less  soiuble,  crystallises  before  the  carbonate,  a  deli- 
qnesceut  salt,  is  separated  from  the  liquor ;  in  most  coses,  however,  this  operation  is  only 
carried  on  where  the  solphate  ol  potash  is  required  for  alnm-making.  The  pearl-ash  or 
potash  of  oommeroe  almost  invariably  contains  a  large  quantity  of  sulphate  of  potash. 

c.  In  order  to  expel  all  the  water  and  to  destroy  the  organic  matter,  the  saline  maas  is 
calcined,  and  as  this  operation  was  formerly  performed  in  cast-iron  pots,  the  salt  has 
obtained  the  name  of  potash.  A.  aalclning  furnace.  Fig.  62,  is  now  nsed,  distingnished 
bom  orditiai;  reverbejatoiy  furnaces  by  being  provided  wiUi  a  doable  flre-plooe.     These 

Fto.  6*. 


hearths,  one  of  which  is  exhibited  in  section  at  t,  Fig.  63,  are  placed  at  right  ta^ee  to 
each  other,  and  the  flame  and  smoke  meeting  in  the  oontre  of  the  fnmaca,  pass  oO  at  o, 
the  work-hole,  into  the  chimney,  K.  Wood  is  used  as  fuel,  and  aa  the  heating  of  the 
fumaoes  requires  a  very  large  quantity,  they  are  only  in  use  when  a  sufficient  sopplr  of 
erode  potash  is  ready  tor  being  operated  npon.  The  fomaoe  is  (horonghly  heated  in 
about  five  to  six  hours,  care  being  taken  to  Are  gradually,  and  to  bring  the  interior  ot  the 
tnnuuie  to  nearly  red  heat,  so  that  the  vapour  due  to  the  combustion  of  the  wood  may  not 
oondense  inside  the  furnace,  bat  be  carried  oti  by  the  flne.  The  crude  potash,  brokem  up 
to  egg-siied  lamps,  is  next  plaped  in  such  quantities  at  a  time  as  ma;  soit  the  siae  of  tht 
ealcining  hearth ;  for  instance,  if  the  hearth  is  roomed  to  contain  3  cwts.,  that  qaantity  is 
divided  into  three  portions  and  put  in  at  intervals  of  a  few  minutes.  The  first  effeet  ot 
the  heat  is  to  expel  the  water  from  the  potash,  the  escape  of  the  steam  being  promotod  by 


4- 

5- 

6. 

7- 

8. 

68'0 

69-9 

386 

490 

5084 

5-8 

31 

4-3 

— 

12*14 

I5'3 

141 

38-8 

405 

17*44 

8-1 

2*1 

91 

lO'O- 

580 

— 

8-8 

5*3 

— 

io-i8 

2*3 

2-3 

3-8 

— 

3*6o 

CARBONATE  OF  POTASSA.  125 

■tining  the  mass  with  iron  rakes.  In  about  an  honr  all  the  water  is  driven  off,  and  the 
mass  takes  fire  in  consequence  of  the  burning  of  the  organic  matter,  the  salt  at  first  being 
blackened,  but  gradually  becoming  white  as  the  carbon  bums  off.  As  soon  as  this  stage 
is  reached,  the  potash  is  removed  to  the  cooling-hearth,  and  when  cold,  packed  in  well- 
made  wooden-casks,  which,  as  this  salt  is  very  nygroscopic,  are  rendered  as  air-tight  as 
poBslble.  The  heat  of  the  furnace  has  to  be  well  regulated  to  prevent  the  potash 
becoming  semi-fused,  in  which  case  it  would  attack  the  siliceous  matter  of  the  fire- 
bricks; the  workmen  from  time  to  take  a  small  sample  to  test  how  far  the  oaloination  is 
complete. 

We,  in  Europe,  obtain  a  considerable  quantity  of  potash  from  the  United  States  and 
Canada,  known  as  American  potash,  of  which  there  are  three  different  kinds,  viz. : — 
X.  Potash  prepared  as  described.  2.  Pearl-ash,  or  potash,  purified  by  lixiviation,  decan« 
tation  from  sediment,  boiling  down,  and  the  calcination  of  the  salt  thus  obtained. 
3.  Stone-ash,  a  mixture  of  uncalcined  potash  (potassic  carbonate),  and  caustic  potash 
obtained  by  treating  the  crude  potash  liquor  with  caustic  lime,  and  boiling  down  the  mass 
to  diyness ;  this  article  has  the  appearance  of  the  crude  caustic  soda  of  this  country,  but 
is  usually  coloured  red  by  oxide  of  iron;  the  lumps,  stone-hard,  are  from  6  to  10 
eentims.  in  thickness,  and  contain  upwards  of  50  per  cent  caustic  potash.  The  under- 
mentioned analyses  exhibit  the  varying  composition  of  the  potash  of  commerce : — Sample 
I  is  from  Kasan  (Bussia) ;  analyst,  M.  Hermann.  2.  Tuscany.  3  and  4 — the  latier  of 
a  reddish  colour — from  North  America.  5.  Bussia.  6.  Vosges  ^France) ;  analyst  of 
2, 3, 4, 5,  and  6,  M.  Pesier.  7.  Helmstedt,  in  Brunswick ;  analyst,  M.  Lmipricht.  8.  Bussia ; 
anaiyst,  M.  Bastelaer. 

I.  2.         3. 

Carbonate  of  potash     . .  78-0  74*1  71*4 

Carbonate  of  e^a  . .     . .     —  3*0  2*3 

Sulphate  of  potash       . .  17-0  13*5  14*4 

Chloride  of  potassium  . .    3*0  0*9  3*6 

Water       —  7*2  4*5 

Insoluble  residue    ..     ..    0*2  o-i  2*7 

The  calcined  potash  varies  in  colour,  being  either  white,  pearl-grey,  or  tinged  with 
yellow,  red,  or  blue.  The  red  colour  is  due  to  oxide  of  iron,  the  blue  to  the  manganates 
of  potash,  a  hard,  Ught  porous,  non-crystalline  mass,  never  entirely  sc^uble  in  water. 
Ponnerly,  a  large  quantity  of  potash  was  obtained  from  the  residues  of  wine-making,  and 
eaUed  vinasse,  the  semi-liquid  left  after  the  alcohol  has  been  distilled  from  the  wine,  and 
eontaining,  among  other  substances,  argol,  or  crude  bitartrato  of  potash ;  it  was  boiled 
down,  and  next  calcined,  yielding  a  kilo,  of  very  good  potash  for  every  hectolitre  of  vinasse. 
The  large  quantity  of  potash  thus  formerly  produced  may  be  judged  from  the  fact  that 
19  of  the  wine-produdng  departments  of  France,  those  only  whore  largo  quantities  of 
iHue  are  converted  into  alcohol,  technically  termed  trois  six  and  cinq  huit,  yield  annually 
about  9  to  10  million  hectolitres  of  vinasse,  at  the  present  time  employed  for  the  prepara- 
tion on  Uie  large  scale  of  cream  of  tartar,  glycerine,  and  tartaric  acid. 

pDtMhftomMoiMMi.  V.  Of  late  years,  the  manufacture  of  potash  salts  from  the 
vinasse  left  after  the  distillation  of  fermented  beet-root  molasses  has  been  added  as  a 
sew  branch  of  industry  by  M.  Dubrunfaut,  and  introduced  into  Germany  by  M. 
Vamhagen,  in  the  year  1840,  at  Mucrena,  Prussian  Saxony. 

Beet-root,  on  being  subjected  to  ignition,  yields  an  ash  containing  a  large  percentage  of 
potash,  a  fact  first  observed  in  the  early  part  of  this  century  by  M.  Mathieu  de  Dombasle, 
a  celebrated  French  agriculturist,  who  discovered  that  100  lalos.  of  dried  beet-root  leaves 
yield  X0-5  kilos,  of  ash,  containing  5*1  kilos,  of  potash ;  but  this  author's  idea  that  the 
leavee  might  be  cut  off  and  gathered  for  the  purpose  of  potash  manufacture,  proved 
enoneous,  in  so  far  that  the  growth  of  the  roots  was  greatly  impeded.  After  the  publica- 
tion of  M.  Dubrunfaut's  researches  on  this  subject,  in  1838,  the  vinasse  of  the  beet-root 
molasses  distillation  was  evaporated  to  dryness,  next  calcined,  and  the  calcined  mass 
refiued  for  the  production  of  potash  and  other  Salts  of  that  base,  an  industry  which  has 
obtained  a  great  development,  as  may  be  judged  from  the  fact  that  the  quantity  of  these 
materials  produced  on  the  European  continent  in  1865  amounted  to  240,000  cwts. 

The  reader  who  desires  details  on  this  subject,  is  referred  to  the  work,  **  On  the  Manu- 
iftetnre  of  Beet-Boot  Sugar  in  England  and  Irehuad,"  by  Wm.  Grookes,  F.B.S.,  <ftc.,  p.  250 
etBeq. 


Soda       ...     . 
Liime 
Magnesia 
Carbonic  acid 


2. 

3 

4767 

5038 

"•43 

8-29 

360 

312 

010 

018 

27-94 

28*70 

126  CHEMICAL  TECHNOLOGY, 

The  molasses  from  beet-root  sugar  consists,  previous  to  the  fermentation  and  dis- 
tillation, of  the  undermentioned  substances,  as  recorded  by  the  several  analysts  whose 

names  are  subjoined  '.-* 

Brmmer.    Fricke.    Lunge.    Heidenpriem. 

Water    i5"2  180        18-5        190    197 

Sugar    490  480        507        469    49-8 

Salts  and  organic  substances        358  34*0        30*8        34*1     30*5 

The  following  analyses  by  M.  Heidenpriem  exhibit  the  average  composition  of  the 

ashes  of  molasses : — 

•  I. 

Potassa 5172 

800 

504 
018 

28*90 

The  remainder  of  the  100  parts  consists  of  phosphoric  and  silicic  acids,  chlorine, 
oxide  of  iron,  &c.  The  quantity  of  ash  amounts  to  10  or  12  per  cent.  According  to 
Dubrunfaut  the  alkalimetrical  degree  of  the  ash  of  beet-root  sugar  molasses  is  a 
constant,  as  the  ash  obtained  from  100  grms.  of  molasses  neutralises  on  an  average 
7  grms.  of  sulphuric  acid  (H2SO4). 

The  molasses  is  generally  treated  in  the  following  manner : — ^It  is  first  diluted  with 
either  water  or  vinasse  to  8*  or  ii**  B.  =  1*056  or  1*078  sp.  gr.,  and  mixed  with  0*5  to 
I '5  per  cent  of  a  pure  mineral  acid,  the  object  of  this  addition  being  not  sunply  the 
neutralisation  of  the  alkali,  but  also  the  conversion  of  dextrine  and  such  unfennentable 
sugar  into  fermentable  sugar.  Formerly,  sulphuric  acid  was  used,  but  upon  the 
recommendation  of  M.  Wurtz,  hydrochloric  acid  is  now  generally  employed,  the 
advantage  being  the  formation  of  readily  soluble  chlorides,  instead  of  comparative 
insoluble  alkaline  sulphurets,  the  action  of  the  organic  matter  present  in  the  molaases. 

The  diluted  molasses  is  next  mixed  with  yeast,  left  to  ferment,  and  the  alcohol 
distilled  off;  the  residue  is  a  liquid  of  about  4**  B.  density  [» 1*027  ^P-  S'-]  containing 
undecomposed  yeast,  ammoniacal  salts,  various  organic  substances,  and  all  the  inorganic 
salts  of  the  beet-root  juice.  The  potassa  is  present  in  this  liquid  as  nitrate  chiefly, 
although  by  the  addition  of  hydrochloric  acid  a  portion  of  this  salt  is  decomposed, 
red  nitrous  fumes  sometimes  being  seen  in  the  fermentation  room.  Evrard  suggests 
that  the  saltpetre  should  be  separated  from  the  beet-root  molasses  by  evaporation, 
and  further  purified  by  the  aid  of  the  centrifugal  machine.  The  acidity  of  the 
vinasse  is  neutralised  by  chalk,  and  afterwards  it  is  evaporated  to  dryness  in  an  iron 
vessel,  the  total  length  of  which  is  20*3  metres,  by  an  average  width  of  1*6  metre, 
extended  at  the  top  to  2  metres,  the  depth  being  034  metre.  Tlie  vessel  is  muade  of  stout 
boiler  plate,  strengthened  by  stays  and  angle  irons,  and  is  divided  into  two-divisions, 
the  larger  of  which  has  a  length  of  14*3  metres,  and  is  the  real  evaporating  pan, 
while  the  other  is  used  as  a  calcining  furnace,  and  covered  with  an  arch  of  fire- 
bricks o'6  metre  high.  The  fire-place  is  1*3  metre  wide,  and  the  fire-box  has  a 
surface  of  3*3  square  metres.  The  evaporation  is  effected  by  surface  heating,  that 
is  to  say,  the  flame  and  hot  gases  from  the  burning  fuel  after  passing  across  the  fire- 
bridge are  conducted  over  the  surface  of  the  vinasse,  the  calcining  pan  being  nearest 
to  the  fire,  while  the  evaporating  pan  is  at  its  other  extremity  in  contact  with  the 


CARBONATE  OF  POTASSA. 


"7 


floe  or  chimney.  The  viDBsse,  having  been  run  off  from  the  still,  is  kept  in  cisterns, 
from  which  it  is  forced  by  means  of  a  pump  into  a  reaervoiT  bo  placed  as  to  admit  of 
the  liquid  nmning  in  a  constant  stream  into  the  eraporating  pan.  At  a  first  operation 
both  the  evaporatiiig  and  the  calcining  pan  are  filled  with  vinasse,  but  afterwards 
(be  latter  is  filled  regularlj  with  concentrated  thick  liquor,  which  is  simply  carbonised, 
the  organic  matter  being  only  destroyed. 

The  daily  average  of  carbonised  vinasse  is  about  5  to  5I  owts.    The  composition 
of  that  substance  may  be  gleaned  from  the  foUowing  approximative  analysis : — 
Insoluble  matter  =23      per  cent. 

Sulphate  of  potassa  =  1107      „ 

Chloride  of  potassiom  =  11*61      „ 

Carbonate  of  potaasa  =  3140      „ 

Carbonate  of  soda  =  23'26      „ 

Silicic  add  and  hyposulphite  of  potassa  =  traces      „ 

9934  ■. 
la  Oennany,  the  calcined  vinasae  is  generally  sold  to  saltpetre  manufacturers,  but 
in  Belgium  and  France  this  material  is  calcined,  lixiviated,  and  the  Halts  it  contains 
Mpuately  obtained.  For  this  purpose  the  vinasse  is  first  evaporated  to  38°  or  40° 
B'  |i  33  to  1-35  sp  gr )  and  next  carbonised  and  calcmed  in  a  &mace  constructed 
u  exhibited  m  Fig  63  v  la  a  reservoir  containing  the  concentrated  vmasee  which 
by  means  of  a  tube  ts  gradnally  ran  into  the  furnace  of  which  a  is  the  fire  place,  m 
the  calcination  qiace  desbned  to  contam  the  concentrated  or  carbonised  vinasse, 
Fia  63 


vhich  is  evaporated  to  dryneas  and  calcined  in  m;  a  dixir  is  fitted  to  each  cora- 
partment,  and  at  P,  the  end  of  the  furnace  opposite  to  the  fire-place.  The  air  required 
br  the  cftkinBtion  is  admitted  partly  through  the  ash-pit.  partly  tbrongh  the 
openings,  B,  in  the  brickwork.  The  thiddsh  liquid  vinasse  admitted  into  m'  ia 
cmstantly  stirred,  and.  as  soon  as  it  is  quite  dry,  it  is  shovelled  across  the  brickwork 
lidge,  a',  into  the  calcining  E^ace,  u,  core  being  taken  to  again  fill  u'  with  concen- 
trated vinasse.  The  organic  matter  of  the  aaline  masa  soon  takes  fire,  emitting 
Doiions  fames.  The  calcination  is  greatly  aided  by  the  access  of  air  at  b,  and  also 
to  some  estent  by  the  nitrate  of  potassa  present.  The  temperature  has  to  be  regulated 
to  prevent  the  aalta  becoming  fased  and  fanning  a  hard  compact  mass,  in  which  case 
the  sulphate  of  potassa  would  be  reduced  to  sulphufet  of  potasainm,  a  salt  which 


•••         ••• 


a. 

6. 

c. 

d. 

26'22 

19-82 

17*47 

13*36 

12-95 

988 

2*55 

3*22 

15-87 

20-59 

18-45 

i6'62 

0-13 

0-15 

o-i8 

0"2I 

2552 

19-66 

19-22 

1654 

2340 

2990 

4213 

5005 

128  CHEMICAL  TECHNOLOGY. 

conld  not  be  removed.  The  calcined  vinasse,  technically  teimed  9alint  contains, 
when  removed  from  the  furnace,  10  to  25  per  cent  of  insoluble  substances,  viz., 
carbonate  and  phosphate  of  lime,  more  or  less  charcoal,  and  in  addition,  3  to  4  per 
cent  moisture ;  the  remainder  consists  of  carbonates  of  potash  and  soda,  sulphate  of 
potassa,  chloride  of  potassium,  and  sometimes  cyanide  of  potassium  in  considerable 
quantify.  The  relative  quantities  of  potassa  and  soda  are,  of  course,  not  at  all 
constant,  but  vary  according  to  the  soil  on  which  the  beets  have  grown ;  it  has  been 
observed  in  France  that  the  molasses  obtained  from  beets  grown  in  the  D^partement 
du  Nord  are  less  rich  in  potassa  than  those  grown  in  the  D6partements  de  TOise  et  de 
la  Somme.    The  average  composition  of  the  salin  is : — 

7  to  12  per  cent  of  sulphate  of  potassa. 

18  to  20        „        of  carbonate  of  soda. 

17  to  22        „        of  chloride  of  potassium. 

30  to  35        „        of  carbonate  of  potassa. 
The  complete  composition  of  the  saHn  may  be  gathered  from  the  following 
tabulated  results : — 

Water  and  insoluble  matter ... 

Sulphate  of  potassa       

Chloride  of  potassium   . . . 

Chloride  of  rubidium    

Carbonate  of  soda 

Carbonate  of  potassa 

lOO'OO    lOQ-QO    lOO'OO    lOO'OO 

The  method  of  separating  the  soluble  salts  from  each  other,  invented  by  M.  Kuhl- 
mann,  is  generally  executed  as  foUows : — ^The  saline  mass  is  first  broken  up  and 
granulated  by  the  aid  of  grooved  iron  rollers,  after  which  it  is  placed  in  lixiviation- 
tanks,  each  containing  264  cwts.,  and  arranged  precisely  in  the  same  manner  as 
those  in  use  in  soda  works.  The  liquor  tapped  from  tlie  tanks  has  a  sp.  gr.  of  1*229 
(=  27''  B.) ;  the  insoluble  residue  is  used  as  manure.  The  liquor  having  been  col- 
lected in  a  large  reservoir,  capable  of  containing  some  210  hectolitres,  is  concentrated 
by  waste  heat  [ctbgangiger  wUrme)  to  a  density  of  126  (=  30**  B.) ;  on  cooling,  the 
greater  part  of  the  sulphate  of  potassa  crystallises,  and  is  removed,  care  being  taken 
to  wash  off  the  adhering  mother-liquor. '  The  sulphate  thus  obtained  contains  80  per 
cent  pure  potassic  sulphate,  the  rest  being  carbonate  of  potassa  and  organic  matter : 
this  material  is  converted  into  potash  by  Leblanc's  process.  The  liquor  at  30*^  B.  is 
next  poured  into  evaporating-pans,  each  capable  of  containing  90  hectolitres,  and 
concentrated  by  means  of  heat  and  a  steam  pressure  of  3  atmospheres  (=  45  lbs.  to 
the  square  inch)  to  a  density  of  42''  B.  (=  1*408).  By  this  operation  a  mixture  of 
carbonate  of  soda  and  sulphate  of  potassa  is  separated,  which  frequently  exhibits 
30  alkalimetrical  degrees ;  the  liquor  is  transferred  from  the  evaporating-pans  to 
crystallising  vessels,  in  which  it  is  cooled  down  to  not  less  than  30*.  K,  by  careless- 
ness, the  temperature  should  fall  below  30**,  the  chloride  of  potassium  crystals  become 
mixed  with  a  layer  of  carbonate  of  soda.  The  liquor  at  a  temperature  of  30**,  and 
having  a  density  of  42""  B.,  is  again  transferred  to  evaporating-pans,  each  capable  of 
containing  20  hectolitres,  and  evaporated 

In  winter  to  a  sp.  gr.  of  1494  (=  48*^  B.),  and 
In  summer  to  a  sp.  gr.  of  1*51  {=  49°  B.) 


CARBONATE   OF  POTASSA.  129 

By  this  operation  sodic  carbonate  separates,  the  first  and  purer  portions  of  which 
are  of  82  alkalimetrical  degrees,  and  the  last  of  50°  only.  After  the  separation  of 
the  salt,  the  remaining  liquor  is  poured  into  small  crystallising  vessels,  each  capable 
of  holdiog  2i  hectolitres,  and,  having  been  left  standing  for  some  time,  yields  in  each 
vessel  about  130  kilos,  of  a  crystalline  salt,  mainly  composed  according  to  the 
fonnnla  (EaCOs-hNaaGOj+izHaO).  The  remaining  mother-liquor,  when  evapo- 
rated to  dryness  and  calcined,  yields  a  semi-refined  potash,  tinged  with  red  by  oxide 
of  iron.  This  product  is  again  lixiviated  with  water,  and  the  liquor  having  been 
concentrated  to  1*51  to  1*525  sp.  gr.  (=  49''  to  50"^  B.),  deposits  a  large  quantity  of 
snlphate  of  potassa  and  carbonate  of  soda.  The  mother-liquor  having  been  again 
evaporated  and  calcined,  yields  a  potash  consisting  in  100  parts  of — 

Carbonate  of  potassa 9i'5 

Carbonate  of  soda      5*5 

Chloride  of  potassium  and  sulphate  of  potassa     3*0 

lOO'O 

The  carbonate  of  soda  possessing  a  strength  of  80  to  85  alkalimetrical  degrees  is 
refined  by  being  washed  with  a  very  concentrated  aqueous  solution  of  sodic  carbonate, 
and  thus  brought  to  a  strength  of  fiilly  90  alkalimetrical  degrees. 

The  sulphate  of  potassa,  chloride  of  potassium,  and  the  double  salt  of  the  two 
earbonates,  are  purified  and  re-crystallised.  The  following  analyses  exhibit  the  com- 
position of  refined  potash  obtained  from  beet-root  sugar  molasses : — 

a«  6.  c. 

Carbonate  of  potassa     ^73 

Carbonate  of  soda 644 

Sulphate  of  potassa       2*27 

Chloride  of  potassixmi    100 

Iodide  of  potassixmi       o'02 

T¥  wHiCi  •••        •■•        •••        «••        ■■•        ■••  JL  39 

Insoluble  substances      0*12  —  — 

a  and  fr  are  from  Waghansel  m  Baden ;  c  is  doubly  refined  French  potash.  The 
crude  potash  from  beet-root  sugar  works,  a  product  not  to  be  confused  with  saJin, 
is  composed  as  follows : — 

Carbonate  of  potassa  ... 
Carbonate  of  soda 
Sulphate  of  potassa     ... 
Chloride  of  potassium ...      19*6 

fi  is  French  product ;  b,  from  Valenciennes ;  e,  from  Paris ;  d,  Belgian ;  f ,  from 
Uagdebuig,  Prussia. 

p«*-jjHjtaft«m  Yi  Potassa  salts  are  obtained  in  large  quantities  from  various  sea- 
^^ds,  as  a  by-product  of  the  manufacture  of  bromine  and  iodine.  The  three 
following  methods  are  employed  for  th's  purpose : — 

0.  The  old  calcination  method,  consisting  in  a  complete  reduction  of  the  weeds  to 
*^  and  the  methodical  lixiviation  of  that  product,  so  as  to  obtain  various  salts 
ty  crystaUisation. 

^.  The  carbonisation,  or  Stanford's  method,  consisting  in  the  dry  distillation  of  the 
^«eds  to   convert   them  into  a  carbonaceous  mass,  afterwards  lixiviated,  while 


94*39 

893 

traces 

5-6 

028 

22 

2*40 

15 

01 1 

— 

176 

— 

a. 

h. 

e. 

d. 

e. 

53*9 

790 

760 

430 

329 

231 

14*3 

16*3 

17*0 

i8-5 

29 

39 

119 

47 

140 

196 

2-8 

416 

180 

160 

130 


CHEMICAL    TECHNOLOGY. 


products  lire  simultaneously  obtained,  the  sale  of  which  considerably  lessens  the  cost 
of  the  preparation  of  the  potassa  salts. 

e.  A  third  mode  of  treatment,  that  of  Kemp  and  Wallace,  consisting  in  boiling  the 
weeds  with  water,  evaporating  the  solution,  and  carefolly  incinerating  the  residue. 

The  oldest  method  is  still  the  most  generally  employed  in  France,  on  tiie  coasts 
of  Brittany  and  Lower  Normandy,  especially  in  the  neighbourhood  of  Brest  and 
Cherbourg,  and  in  Scotland  and  Ireland. 

The  process  is  mainly  conducted  as  follows : — ^After  drying  in  the  air,  the  plants  are 
incinerated,  the  result  of  which  is  the  formation  of  a  black  semi-fused  mass,  which 
in  France  is  termed  Varech  or  Vraief  and  in  England  and  Scotland  is  known  as  kdp. 
A  distinction  is  made  between  the  kelp  obtained  by  the  incineration  of  the  weeds, 
Fucus  8erratu9  and  Fucus  nodostUt  found  on  rocks  near  the  sea  coast,  and  the  kelp 
obtained  from  the  plant  botanically  known  as  Laminaria  digitataf  thrown  upon  the 
coast  during  the  storms.  The  latter  is  richer  in  potassa  salts,  but  contains  much 
less  iodine ;  it  is  found  plentifully  on  the  western  coast  of  Scotland  and  Ireland, 
while  on  the  eastern  coast  of  the  British  Isles  the  other  weed  is  ihe  chief  source 
of  kelp,  having  an  average  composition  of : — 

Insoluble  matters  ... 

Sulphate  of  soda  ... 

.  Chloride  of  potassium 


Chloride  of  sodium 

Iodine     

Other  salts     


57000 
10*203 

13476 
16018 

o*6oo 

2703 

lOO'OOO 


The  best  kelp  met  with  in  commerce  is  that  from  the  island  of  Rathlin,  the  value 
at  Glasgow  amounting  to  My  ids.  to  ^10  ids.  per  ton  of  22  jr  cwts. ;  while  Galway  kelp 
is  valued  at  only  £2  or  ^3  per  ton,  owing  to  the  large  quantity  of  salt  it  contains. 
22  tons  of  moist  sea-weed  yield : — 

Medium  kelp i  ton 

Chloride  of  potassium 5  to  6  cwts. 

Sulphate  of  potassa     3  cwts. 

The  Scotch  mode  of  treating  kelp  is  briefly  the  following: — The  material  is 
first  broken  into  small  lumps,  and  put  in  large  iron  cauldrons,  hot  water  being 
added  to  exhaust  all  the  soluble  matter.  This  operation  follows  the  method  of 
the  manufiEusture  of  soda  from  common  salt,  to  be  presently  considered.  The  water  is 
first  made  to  act  upon  nearly  exhausted  kelp,  and  at  last  with  quite  fresh  kelp, 
until  a  liquid  is  produced  mn-rlriTig  36°  to  40°  Twaddle  =  i'i8  to  1*20  sp.  gr.  The 
insoluble  residue  contains  cMefly  silica,  sand,  carbonate  of  Hme,  carbonate  of 
magnesia,  its  sulphates  and  phosphates,  and  particles  of  charcoal,  and  is  used 
for  bottle-glass  manufacture.  The  liquor  from  the  kelp  is  evaporated  in  large  cast-iron 
semi-globular  cauldrons  by  the  direct  action  of  a  coal  fire,  and  contains  chiefly 
chloride  of  potassium,  a  comparatively  small  quantity  of  chloride  of  sodium,  sulphate 
and  carbonate  of  potassa,  carbonate  of  soda,  some  iodide  of  potassium,  sulphuret  of 
potassium,  and  dithionite  of  potassium  and  sodium.  The  mode  of  separating  these 
salts  from  each  other  is  based  upon  their  varying  solubility  in  water,  and  is  therefore 
Conducted  by  alternate  evaporation  and  cooling.     As  the  sulphate  of  potassa  is 


CARBONATE  OF  POTASSA.  131 

the  least  soluble,  it  faUs  to  the  bottom  of  the  cauldron  during  the  first  evaporation, 
and  is  collected  by  the  workmen  by  means  of  perforated  ladles,  and  brought  into  the 
trade  as  plate  sulphate.  After  this  salt  has  been  collected  the  liquid  is  run 
into  coolers,  in  which  the  greater  bulk  of  the  chloride  of  potassium  crystallises ;  the 
mother-liquor  from  these  crystals  is  again  transferred  to  the  evaporator,  and  by 
the  continued  application  of  heat,  and  consequent  concentration  of  the  liquid,  the 
common  salt  is  separated.  It  should  be  borne  in  mind  that  common  salt  is  scarcely 
more  soluble  in  hot  than  in  cold  water,  while  the  solubility  of  most  other  salts 
is  greatly  increased  by  a  higher  temperature;  it  is  therefore  possible  to  push 
the  evaporation  and  concentration  to  the  point  of  incipient  precipitation  of  the 
cUoride  of  potassium,  the  common  salt  being  then  ladled  out  of  the  cauldron, 
and  the  liquid  again  run  into  the  coolers  in  order  to  obtain  another  deposit  of 
chloride  of  potassium,  always  more  or  less  contaminated  with  common  salt.  This 
operation  is  repeated  four  times ;  the  first  crop  of  chloride  of  potassium  contains 
from  86  to  90  per  cent  of  this  salt,  the  remainder  is  chiefly  sulphate  of  potassa ;  the 
second  and  third  crop  yield  a  very  pure  salt,  96  to  98  per  cent  of  chloride  of 
potassium ;  the  fourth  crop  contains  some  sulphate  of  soda  mixed,  with  the  chloride 
of  potassium.  The  liquor  left  after  the  fourth  crystallisation  having  a  sp.  gr.=i'33  to 
1-38  =  66'' to  76''  Twad.,  and  containing  among  other  compounds  sulphate  of  soda, 
solphurets  and  hyposulphites  of  the  alkalies,  alkaline  carbonates,  and  iodide  of 
potassium,  is  not  submitted  to  further  evaporation,  but  having  been  poured  into 
shallow  vessels  placed  in  the  open  air  is  mixed  with  dilute  sulphuric  acid,  sulphu- 
retted hydrogen  and  carbonic  acid  gases  being  largely  evolved,  while  in  consequence 
of  the  decomposition  of  the  polysulphurets  and  hyposulphites,  a  thick  foam  of  pure 
sulphur  appears  on  the  surface  of  the  liquid.  This  sulphur  is  ladled  off,  and  after 
having  been  washed  on  filters  and  dried,  is  sold.  Almost  as  soon  as  the  evolution  of 
gas  ceases,  there  is  added  to  the  liquid  more  sulphuric  acid  and  some  manganese, 
and  the  mixture  treated  for  the  preparation  of  iodine  {quod  vide).  In  order  to  guard 
against  loss  of  valuable  substances  by  volatilisation  during  the  crude  and  imperfect 
mode  of  incineration,  it  has  been  tried  to  simply  carbonise  the  weeds  (Stanford's 
method).  The  weeds  are  first  dried  and  strongly  pressed  into  the  shape  of  peat 
Uocks ;  these  are  submitted  to  dry  distillation  in  retorts  arranged  similarly  to  those 
in  gas-works.  The  products  of  the  dry  distillation  collected  in  the  usual  manner 
contain  in  100  parts  of  fresh  Veed : — 

68*5  to  72*5  parts  of  Ammoniacal  liquor,  , 

40      „        Tar, 
70  to  75      „        Carbonised  weed,  or  coke-weed, 
2'o  to  2*5      „        Illuminating  gas. 

The  coke  contains  33  per  cent  carbon,  the  remainder  consisting  of  alkaline  and 
earthy  salts;'  the  volatile  products  of  the  distillation  are  treated  for  parafi&n, 
photogen,  acetic  acid,  and  ammoniacal  salts,  the  gas  being  used  for  lighting 
purposes.  Although  Mr.  Stanford's  mode  of  treatment  is  undoubtedly  rational, 
there  are  difficulties  in  its  practical  execution  which  have  prevented  its  adoption  in 
Scotland  as  well  as  in  France.  The  quantity  of  potash  salts  obtained  from  sea- 
weeds in  the  year  1865  amounted,  according  to  M.  Joulin,  to  a  total  of  2,700,000 
kilos.,  of  which  the  United  Kingdom  produced  1,200,000  kilos.,  the  remainder 
being  produced  by  France. 

Since  the  production  of   chloride  of  potassium  at   Stassfurt  and  Kalucz  has 

K  2 


132  CHEMICAL  TECHNOLOGY. 

become  so  extensive,  the  prodnction  of  potassa  salts  from  sea-weeds  is  of  little 
consequence. 

FotuflftBaiuiromBaiiit  VII.  The  fact  is  Well  known  that  sheep  while  browsing 
abstract  a  considerable  amount  of  potassa,  which,  after  having  passed  into  the  blood 
and  tissues,  is  sweated  through  the  skin,  and  deposited  on  the  wool  aa  saint 
Professor  Chevreul's  researches  have  proved  that  suint  constitutes  nearly  the  third 
part  of  the  weight  of  crude  merino  wool,  while  the  soluble  portion  of  the  saint 
consists  of  the  potassa  salts  of  a  fatty  acid,  potassic  sudorate  {tuintate  de  potaste). 
According  to  Messrs.  Reich  and  Ulbricht,  the  fatty  acids  of  suint  are  compounds  of 
oleic,  stearic,  and  probably  palmitinic  acids.  The  better  wool  contains  more  saint 
than  the  coarser  kinds ;  on  an  average  the  quautity  of  suint  amounts  to  15  per  cant 
of  the  weight  of  the  fleece. 

Since  the  year  i860,  and  based  upon  the  researches  of  MM.  Maxmidne  and 
Bogelet,  the  manufacture  of  potash  salts  frt)m  the  wash-water  of  the  crude  wool  has 
become,  in  the  centres  of  the  French  woollen  manufacture  (Kheims,  Elbceuf,  Fourmies) 
an  industrial  branch.  The  wash- water  is  valued  according  to  its  degree  of  concen- 
tration ;  1000  Idlos.  of  wool  yielding  a  liquid  which,  according  to  M.  Ohandelon,  has 
a  sp.  gr.  of  103,  is  paid  for  at  the  rate  of  5  francs  48  cents. ;  at  a  sp.  gr.  of  105,  at 
the  rate  of  10  francs  45  cents.;  sp.  gr.  1*25,  18  francs  47  cents.  The  liquid  is 
evaporated  to  dryness,  the  carbonaceous  residue  put  into  gas  retorts,  and  heated  to 
redness,  the  result  being  the  formation  of  carburetted  hydrogen  gas  and  ammonia* 
which  having  been  eliminated,  the  gas  is  used  for  illuminating  purposes.  The 
coke  left  in  the  retorts  is  lixiviated  with  water  to  obtain  the  soluble  salts,  chloride  of 
potassium,  carbonate  and  sulphate  of  potassa,  which  are  separated  from  each  other 
by  methods  already  described. 

The  residue  left  after  the  lixiviation  with  water  contains  earthy  matter  mixed  with 
charcoal  so  very  finely  divided  that  it  can  be  used  as  black  paint.  According  to 
MM.  Maumen6  and  Rogelet,  a  fleece  weighing  4  kilos,  contains  600  grms.  of  suint^ 
capable  of  yielding  198  grms.  of  pure  carbonate  of  potassa ;  according  to  M.  Fuchs, 
however,  the  quantity  of  suint  only  amounts  to  300  grms.,  containing — 

Sulphate  of  potassa     7*5  grms.  =        2*5  per  cent 

Carbonate  of  potassa i33'5      »      =  44*5    u 

Chloride  of  potassium 9*0      „      =        3'o 

Organic  matter     1500      „    '  =  50*0 


If      » 


3000     „      =    1000    „      „ 

It  appears  that  the  woollen  industry  of  Kheims,  Elboeuf ,  and  Fourmies  consomes 
annually  27  million  kilos,  of  wool,  the  produce  of  6,750,000  sheep.  According  to 
MM.  Maumen6  and  Rogelet  this  quantity  of  wool  will  yield  1,167,750  Idlos.  of 
potash,  representing  a  money  value  of  ^80,000  to  ^£90,000.  According  to  M.  P.  Havrez, 
at  Verviers,  Belgium,  suint  is  more  advantageously  worked  up  for  the  manufBu^ore  of 
earbonate  of  potassa  and  yellow  prussiate  of  potassa  than  for  carbonate  of  potassa 
alone.  Suint  has  been  recently  (1869)  chemically  investigated  by  MM.  Marker  and 
Schulze  (see  Joum.  fiir  Prakt.  Chemie,  voL  103,  pp.  193 — 208).  It  is  dear  that 
the  production  of  potash  from  the  wash-water  of  sheep's  wool  can  only  be  carried  oat 
in  the  centres  of  woollen  industry ;  the  sheep-fanners  will  always  do  better  to  retain 
the  wash- water  and  potash  compounds  it  contains  to  the  soil  from  which  the  ftnimala 
have  taken  it    In  an  industrial  point  of  view  the  extensive  importation  of  foreign 


CARBONATE  OF  POT  ASS  A.  133 

wool,  especially  from  Australia  and  the  Cape,  is  of  great  importance.  In  1868  there 
were  imported  into  the  United  Kingdom  from  those  countries  63  million  kilos,  of 
wool,  containing  one-third  of  its  weight  of  suint,  from  which  hetween  7  and  8  kilos, 
pure  potash  could  have  been  obtained,  representing  a  money  value  of  about  £260,000. 

IVeparation  of  Purified  Potash. — The  potash  formerly  obtained  by  the  lixiviation 
of  wood-ash  was  mainly  a  mixture  of  carbonate,  sulphate  of  potassa,  and  chloride  of 
potassium,  the  value  of  each  of  these  salts  being  of  course  very  different.  At  the 
present  time,  in  consequence  of  the  production  of  pure  carbonate  of  potassa  from 
rinasse,  it  has  become  necessary  to  treat  the  crude  liquor  obtained  by  the  lixiviation 
of  wood-aah  methodically,  so  as  to  obtain  the  salts  separately  in  as  pure  a  state  as 
possible. 

The  carbonate  of  potassa  used  in  chemical  and  pharmaceutical  laboratories  was 
formerly  obtained  by  the  ignition  of  cream  of  tartar  or  a  mixture  of  that  salt  with 
nitre,  as  well  as  by  the  ignition  of  acetate  of  potassa ;  at  the  present  time  it  is  pre- 
pared by  the  careful  ignition  of  nitrate  of  potassa  with  an  excess  of  charcoal,  or  by 
the  ignition  of  bi-carbonate  of  potassa.  In  England  carbonate  of  potassa  is  manu- 
&ctared  on  the  large  scale,  the  pure  salt  being  used  in  the  Tnanufacture  of  flint-glass, 
tins  glass  owing  its  great  superiority  and  perfect  want  of  colour  to  the  application  of 
very  pure  materials  in  its  manufeusture.  The  preparation  is  pure  crystallised  car- 
bonate of  potassa,  containing  from  16  to  18  per  cent  water,  equal  to  somewhat  less 
than  2  molecules,  the  second  molecule  being  partly  expelled  by  the  heat  applied  in  the 
manufacture.  This  salt  is  met  with  in  the  trade  in  small  cubical  crystals;  the  raw- 
material  used  in  its  preparation  is  American  pearl-ash,  which,  after  having  been 
mixed  with  sawdust  for  the  purpose  of  converting  the  caustic  alkali  and  sulphuret  of 
potassium  into  carbonate  of  potassa,  is  ignited  and  fused  in  a  reverberatory  furnace, 
constructed  like  those  used  in  the  manufacture  of  soda.  When  cold  the  fused  mass 
is  treated  with  water,  and  the  clear  liquor  having  been  decanted  from  the  sediment, 
la  evaporated  to  dryness  in  a  reverberatory  furnace ;  the  greyish-black  mass  thus 
obtained  is  again  lixiviated  with  water,  and  the  operation  repeated.  The  white 
nline  mass  from  the  third  ignition  is  again  dissolved  in  water,  and  gently 
evaporated  until  the  sulphate  of  potassa  crystallises  out;  the  mother-liquor 
left  is  next  evaporated  until  a  sample  yields  on  cooling  a  salt  of  the  composi- 
tion mentioned  above.  If  this  salt  is  further  ignited  all  the  water  is  expelled,  and  a 
^  white  granular  mass  left.  The  specific  gravity  of  carbonate  of  potassa  solutions 
^  15*"  IB,  according  to  Dr.  Gerlach— 


Peroentage. 

Sp.gr. 

Percentage. 

Sp.gr. 

I 

I 'cog 

30000 

I '3010 

2 

1018 

35000 

1-3580 

4 

1036 

40000 

1*4180 

5 

1045 

45000 

1*4800 

10 

1092 

50000 

15440 

15 

i'i4i 

51000 

1-5570 

20 

1192 

52000 

1-5704 

25 

1245 

52024 

1-5707 

^^MittepotMn.  Preparation  of  Caustic  Potassa. — Caustic  potassa,  hydroxide  of 
potassium,  KHO,  consists  in  100  parts  of  83*97  of  potassa  or  dry  oxide  of  potassium, 
*Qd  1603  of  water.    Caustic  potassa  is  prepared  on  the  large  scale  in  England. 


134  CHEMICAL  TECHNOLOGY. 

The  raw  material  for  this  preparation  is  always  a  crude  carbonate  of  potassa 
obtained  from  chloride  of  potassium,  camallite  from  Stassfurt,  vinasse,  or  any 
other  source.  The  crude  carbonate  is  lixiviated  with  water,  and  the  liquor  rendered 
caustic  with  quick-lime.  A  more  advantageous  method  of  preparing  caustic 
potassa  is  to  mix  sulphate  of  potassa  with  limestone  and  small  coal,  in  sujQiciently 
large  quantities,  and  to  ignite  this  mixture  in  a  furnace.  The  crude  material  is, 
after  cooHng,  lixiviated  with  water  at  50^,  yielding  at  once  raw  caustic  potassa 
liquor,  which  does  not  require  any  further  addition  of  lime.  The  liquor  is  put  into 
a  steam-boiler  and  evaporated  to  a  sp.  gr.  =  1-25  ;  it  is  next  evaporated  to  dryness  in 
open  pans,  the  foreign  salts  which  separate  being  removed.  Caustic  potassa  is 
employed  for  the  conversion  of  soda-saltpetre  into  potassa-saltpetre,  and  with  caustic 
soda  for  the  manufacture  of  oxalic  acid  from  sawdust.  The  following  reactions, 
yielding  caustic  potassa,  deserve  a  brief  notice : — i.  Decomposition  of  sulphate  of 
potassa  by  means  of  caustic  baryta.  2.  Conversion  of  chloride  of  potassium  into 
BUico-fluoride  of  potassium,  and  decomposition  of  that  salt  by  means  of  caustic  lime. 
3.  Ignition  of  potassic  nitrate  with  thin  sheet-copper.  The  following  table 
exhibits  the  quantity  of  potassa  contained  in  solutions  of  that  substance  of  varying 
specific  gravity : — 

Sp.  gr.  Degrees  Baum6.  Percentage  of  potassa. 

I '06  9  47 

III  15  95 

115  19  130 

119  24  l6'2 

1 23  28  195 

1 28  32  234 

i'39  41  324 

152  50  42*9 

r6o  53  467 

1-68  57  512 

Saltfetbe,  Nitrate  of  Potassa. 
(KN03=ioi'2.    In  100  pai;^,  465  parts  potassa,  and  535  parts  nitric  add.) 

Saltpetre.      TMs  Salt  is  to  somc  cxtcut  a  native  as  well  as  a  chemical  product.    The 

well-known  flocculent  substance  often  observable  on  walls,  especially  those  of  stables, 

is  composed  in  a  great  measure  of  nitrates;   a  similar  phenomenon  is  seen  in 

subterraneaa  excavations,  and  even  in  many  localities  the  surface  of  the  soil  is  covered 

with  an  efflorescent  saline  deposit,  consisting  largely  of  nitrate  of  potassa.    These 

deposits  are  most  common  in  Spain,  Hungary,  Egypt,  Hindostan,  on  the   banks 

of  the  Ganges,  in  Ceylon,  and  in  some  parts  of  South  America,  as  at  Tacunga  in  the 

State  of  Ecuador ;  while  in  Chili  and  Peru  nitrate  of  soda,  so-called  Chili  saltpetre, 

is  found  in  very  large  quantities  under  a  layer  of  clay,  the  deposit  extending  over  a 

tract  of  land  some  150  miles  in  length. 

ooeamnce  of  NatiT*  Although  native  saltpetre  is  met  with  under  a  variety  of  oonditions, 
saitpetK.  jT^Qy  ^  agree  in  this  particular,  that  the  salt  is  formed  under  the 
influence  of  organic  matter.  As  already  stated,  the  salt  covers  the  soil,  forming  an 
efflorescence,  which  increases  in  abundance,  and  which  if  removed  has  its  place  supplied 
in  a  short  time.  In  this  manner  saltpetre,  or  nitre  as  it  is  sometimes  called,  is  obtained 
from  the  slimy  mud  deposited  by  the  inundations  of  the  Ganges,  and  in  Spain  from  the 
liziviation  of  ihe  soil,  which  can  be  afterwards  devoted  to  the  raising  of  com,  or  arranged 


SALTPETRE,  NITRATE  OF  POTASSA.  X35 

in  saltpetre  beds  for  the  regular  production  of  the  salt.  The  chief  and  main  condition 
of  the  formation  of  saltpetre,  which  succeeds  equally  in  open  fields  exposed  to  strong 
Bimlight,  under  the  shade  of  trees  in  forests,  or  in  caverns,  is  the  presence  of  organic 
matter,  vias..  Humus,  inducing  the  nitre  formation  by  its  slow  combustion  ;  the  collateral 
conditions  are  dry  air,  little  or  no  rain,  and  the  presence  in  the  soil  of  a  weathered 
erystalline  rock  containing  feldspar,  the  potassa  of  which  favours  the  formation  of  the 
nitrate  of  that  base.  All  the  known  localities  where  the  formation  of  nitre  takes  place 
naturally,  including  the  soil  of  Tacunga,  formed  by  the  weathering  of  trachyte  and 
tnfstone,  are  provided  with  feldspar.  The  nitric  acid  is  due  to  the  slow  combustion  of 
nitrogenous  organic  matter  present  in  the  humus,  it  having  been  proved  that  the  nitric 
add  constantly  formed  in  the  air  in  enormously  large  quantities  by  the  action  of 
electricity  and  ozone,  as  evidenced  by  the  investigations  of  MM.  Boussingault,  Millon, 
Zabelin,  Schonbein,  Froehde,  Bdttger,  and  Meissner,  has  nothing  whatever  to  do  with 
the  formation  of  nitre  in  the  soil,  a  fact  also  supported  by  Dr.  Goppelsrdder*s  discovery 
of  the  presence  of  a  small  quantity  of  nitrous  add  in  native  saltpetres. 

MaajojNWjiiitog      The  mode  of  obtaining  saltpetre  in  the  countries  where  it  is  naturally 

fonaed  is  very  simple,  consisting  in  a  process  of  lixiviation  with  water,  to  which 

fi^uently  some  potash  is  added  for  the  purpose  of  decomposing  the  nitrate  of  lime 

occuizing  among  the  salts  of  the  soil,  the  solution  being  evaporated  to  crystallisation. 

Soils  yielding  saltpetre  are  termed  Gay  earth  or  Gay  saltpetre.    The  process  by 

which  nitrate  of  potassa  is  naturally  formed  is  imitated  in  the  artificial  heaps 

known  as  saltpetre  plantations,  formerly  far  more  general  than  at  the  present 

time,  it  having  being  found  that   the   importation  of  Indian  saltpetre,  and  the 

manufacture  of  nitrate  of  potassa  by  conversion  from  nitrate  of  soda,  are  cheaper 

sources.  Thus,  saltpetre  beds  are  to  be  met  with  only  under  peculiar  conditidhs,  as, 

for  instance,  in  Sweden,  where  all  landed  proprietors  are  required  to  pay  a  portion 

of  their  taxes  in  saltpetre. 

The  mode  of  making  these  plantations  may  be  briefly  described  as  follows  : — Materials 
eontaining  much  carbonate  of  lime — for  instance,  marl,  old  building  rubbish,  ashes,  road 
scrapings,  stable  refuse,  or  mud  from  canals  —is  mixed  with  nitrogenous  animal  matter, 
all  lands  of  refuse,  and  frequently  with  such  vegetable  substances  as  naturally  contain 
nitrate  of  potassa,  such  as  the  leaves  and  stems  of  the  potatoe,  the  leaves  of  the  beet, 
Bunflower  plants,  nettles,  &o.  These  materials  are  arranged  in  heaps  of  a  pyramidal 
Bbape  to  a  height  of  2  to  2i  metres,  care  being  taken  to  make  the  bottom  impervious  to 
water  by  a  well  puddled  layer  of  day,  the  heap  being  in  all  directions  exposed  to  the 
action  of  the  atmosphere,  the  circulation  of  which  is  promoted  through  the  heap  bv 
layers  of  straw.  The  heap  is  protected  from  rain  by  a  roof,  and  at  least  once  a  week 
watered  with  lant  (stale  urine).  The  formation  of  saltpetre  of  course  requires  a  considerable 
length  of  time,  but,  when  taught  by  experience,  the  workmen  suppose  a  heap  ripe,  the 
watering  is  disoontinued,  the  salt  containing  saltpetre  soon  after  efflorescing  over  the 
nirface  of  the  heap  to  6  to  10  oentims.  in  thickness ;  this  layer  is  scraped  oif,  and  the 
operation  repeated  from  time  to  time  until  the  heap  becomes  decayed  and  has  to  be 
entirely  removed.  In  Switzerland  saltpetre  is  artificially  made  by  many  of  the  farmers, 
nmply  by  causing  the  urine  of  the  oattlo,  while  in  stable  in  the  winter  time,  to  be 
absorbed  by  a  calcareous  soil  purposely  placed  under  the  loose  flooring  of  the  stables, 
which  are  chiefly  built  on  the  slope  of  the  mountains,  so  that  only  the  door  is  level 
with  the  earth  outside,  the  rest  of  the  building  hanging  over  the  slope,  and  being  supported 
by  stout  wooden  poles ;  thus  a  space  is  obtained,  which,  freely  admitting  air,  is  filled 
with  marl  or  other  suitable  materiaL  After  two  or  three  years  this  material  is  removed, 
lixiviated  with  water,  mixed  with  caustic  lime  and  wood  ash,  and  boiled  down.  The  liquor 
having  been  sufficiently  evaporated,  is  decanted  from  the  sediment  and  left  for  crystalli- 
■ation;  the  quantity  of  saltpetre  varying  from  50  to  200  lbs.  for  each  stable. 

*al5j5w  tiru^''      ^®  crude  salt  from  the  heaps  is  converted  into  potassic  nitrate 

l>y  the  following  processes : — a.  The  earth  is  lixiviated  with  water,  this  operation 

^g  known  as  the  preparation  of  raw  lye.    b.  The  raw  lye  is  broken,  that  is  to 

tty*  it  is  mixed  with  a  solution  of  a  potash  salt  in  order  to  convert  the  nitrates  of 

loagnesia  and  lime  present  into  nitrate  of  potassa.    c.  Evaporation  of  this  liquor 

^  obtain  crude  crystallised  saltpetre,    d.  Refining  the  crude  saltpetre. 


"36 


CHEMICAL  TBCHNOLOOY. 


Pn^umof  jiie  ripe  earth  is  lixiviated  to  obt&in  all  the  valuable  soluble  nuitter, 
it  being  expedient  to  nae  u  little  water  as  possible  in  order  to  save  fuel  in  the 
Gubseqnent  evaporation,  for  which  the  liqnor  is  ready  when  it  contains  &om  iz  U>  13 
per  cent  of  soluble  ealts. 

Bwun^op  uu  Jiig  jf^yf  lyg^  Bometimea  known  as  soil  water,  contains  the  nitrates 
of  lime,  magnesia,  potassa,  soda,  the  chlorides  of  calcium,  magneaium.  and  potasaiiun ; 
also  ammoniacol  salts  and  organic  matter  of  vegetable  as  well  as  of  animal  orj|^. 
In  order  to  convert  the  nitrates  of  lime  and  magneaia  into  nitrate  of  potassa,  ths 
raw  l;e  is  broken  np  as  it  is  termed,  that  is  to  saj,  there  is  added  to  it  a  solution 
of  1  part  potossic  carbonate  in  2  parts  water: — 

Nitrate  of  lime.  Ca(NO})i  ]  fNitrate  of  potassa,  4KNOJ. 

Nitrate  of  magnesia,  MgiNOjlj  [■  yield  |  Carbonate  of  lime,  CaCOj. 

Carbonate  of  potassa,  2K1CO]    J  ( Carbonate  of  magnesia,  MgCOj. 

The  chlorides  of  calcinni  and  magnesiam  are  &leo  decomposed,  being  converted 
into  carbonates,  while  chloride  of  potassium  ia  formed.  The  addition  of  the  solatioa 
of  potassa  to  the  raw  I;e  is  continned  as  long  as  a  precipitate  is  formed  ;  in  order. 
however,  to  have  some  approximative  idea  of  the  quantity  of  carbonate  of  potash 
which  may  be  required  a  test  experiment  is  made  wiQi  i  litre  of  the  raw  lye. 

Sometimes  sulphate  of  potassa  is  nsed  instead  of  tbe  carbonate,  but  in  that  case 
the  magnesia  salts  of  the  raw  lye  have  first  to  be  decompoaed  by  millc  of  lime,  tut 
operation  which  has  to  be  followed  by  the  evaporation  of  the  finid.  If,  after  this, 
sulphate  of  potassa  is  added,  sulphate  of  lime  is  precipitated — 
[CalN0j)j+K.S04=2KN0j+CaS04] . 
Y^ien  chloride  of  potassium  is  used  for  the  decomposition  of  raw  tye,  the  salts  of 
magnesia  are  first  removed  by  the  addition  of  milk  of  lime ;  and  the  dear  supematAnt 
fluid  havii^  been  decanted  from  the  sediment,  there  is  added  a  mixtnre  of  equ&l 
molecules  of  chloride  of  potsssinm  and  sulphate  of  soda,  the  result  being  the  formalioti 
of  gypsum,  while  the  sodic  nitrate  generated  exchanges  with  the  chloride  of  potassium, 
carrying  over  to  the  latter  the  nitric  acid,  and  taking  up  the  chloride  to  form  eaaamm 
salt 
°°"K.''™'*'  The  clarified  raw  lye  decanted  from  the  precipitate  of  the  earthy 
carbonates  consists  of  a  solution  in  which  there  are  present  the  chlorides  of 
potassium  and  sodium,  nitrate  of  potaesm, 
carbonate  of  ammonia,  excess  of  potasde 
carbonate,  and  colouring  matt«r.  The  boiling 
down  of  this  liquid  is  effected  in  copper 
cauldrons.  Fig.  64,  so  set  in  the  furnace  aa 
to  admit  of  the  circulation  of  the  hot  air  and 
smoke  from  the  fire-place,  passing  by  e  0 
below  the  heating  pan,  and  thence  by  g  into 
the  chimney.  In  some  works  this  wasta 
heat  is  utilised  in  drying  the  saltpetre  floor. 
As  the  bulk  of  the  floid  in  the  cauldron 
decreases  by  evaporation,  fresh  lye  enters  by 
means  of  a  pipe  and  tap  from  the  pan,  d. 
About  the  third  day  the  alkaline  clilorides  begin  to  be  deposited,  and  the  workmen 
have  then  to  take  great  care  to  prevent  these  salts  from  becomingwhal  is  technically 


Fio.  G4. 


SALTPETRE,  NITRATE  OF  POTASSA.  137 

termed  bamt,  which  might  give  rise  to  serious  explosions,  and  for  this  purpose  the 
liqoid  is  stirred  with  stont  wooden  poles.  After  each  stining  the  loose  saline  matter 
is  removed  from  the  boiling  liquid  by  means  of  perforated  copper  ladles.  However, 
aB  a  hard  deposit  is  always  formed,  a  peculiar  arrangement  exhibited  in  Fig.  64, 
consisting  of  a  shallow  vessel,  m,  suspended  by  a  chain,  k,  and  weighted  with  a  piece 
of  stone,  is  lowered  into  the  middle  of  the  cauldron  to  about  6  centims.  from  the 
bottom,  the  object  being  to  catch  the  solid  particles,  which  would,  when  aggregating, 
form  an  incrustation,  previously  to  their  reaching  the  bottom  of  the  vessel ;  and  as 
no  ebullition  takes  place  at  m,  the  particles  once  deposited  remain  there,  and  can  be 
readily  removed  by  raising  the  dish  out  of  the  cauldron,  and  emptying  it  into  a  box 
placed  over  the  cauldron,  the  bottom  of  the  box  being  perforated  to  admit  of  any 
liquor  which  may  have  been  raised  with  the  solid  salt  to  return  again  to  the 
cauldron.  The  deposit  thus  removed  consists  chiefly  of  gypsum  and  carbonate  of 
lime. 

When  a  portion  of  the  impurities  contained  in  the  boiling  liquid  have  been 
removed,  the  raw  lye  still  frequently  contains  some  chloride  of  sodium,  as  this  salt  is 
not,  as  is  the  case  with  nitre,  more  soluble  in  boiling  than  in  cold  water.  The 
abmidant  crystallisation  of  the  saltpetre  is  a  sign  that  the  lye  has  been  sufficiently 
evaporated ;  in  order,  however,  to  prove  this,  a  small  sample  is  taken,  and  if  on 
cooling  the  nitre  crystallises  so  that  the  greater  part  of  the  sample  becomes  a  solid 
mass,  the  liquid  is  run  into  tanks  and  left  for  5  or  6  hours,  during  which  time 
impurities  are  deposited,  and  the  liquid  rendered  quite  clear.  As  soon  as  the 
temperature  of  the  liquid  has  fallen  to  60°,  it  is  poured  into  copper  crystallisation 
vessels ;  after  a  lapse  of  24  hours  the  crystallisation  is  complete,  and  the  mother- 
liqnor  being  separated  from  the  salt  is  employed  in  a  subsequent  operation. 
c£!^J^JS^,  The  crude  saltpetre  is  yellow-coloured,  and  contains  on  an  average 
some  2o  per  cent  of  impurities,  consisting  of  deliquescent  chlorides,  earthy  salts,  and 
water.  The  object  to  be  attained  by  the  refining  is  the  removal  of  these  substances. 
At  the  present  day  a  large  portion  of  the  refined  saltpetre  met  with  in  commerce  is 
obtained  by  the  refining  of  the  crude  saltpetre  imported  from  India.  It  may  be  noted 
that  this  importation  is  steadily  increasing,  there  being,  in  i860,  16,460,300  kilos., 
and  in  1868,  33,062,000  kilos,  of  the  salt  brought  to  England ;  and,  indeed,  the 
production  of  saltpetre  from  natural  sources  in  Europe  is  now  limited  to  very  few 
and  uumportant  localities.  ^^^^ 

The  method  of  refining  saltpetre  is  based  upon  the  fact  that  nitrate  of  potassa  is 
fu  more  soluble  in  hot  water  than  are  the  chlorides  of  sodium  and  potassium. 
600  litres  of  water  are  poured  into  a  large  cauldron,  and  24  cwts.  of  the  crude  saltpetre 
tte  added  at  a  gradually  increasing  temperature;  as  soon  as  the  solution  boils, 
36  cwts.  more  crude  saltpetre  are  added.  Supposing  the  crude  nitre  to  contain 
20  per  cent  of  alkaline  chlorides,  the  whole  of  the  nitre  will  be  dissolved  in  this 
quantity  of  water,  while  a  portion  of  the  chlorides  will  remain  undissolved  even  at 
the  boiling-point.  The  non-dissolved  salt  is  removed  by  a  perforated  ladle,  and  the 
Bcnm  rising  to  the  surface  of  the  boiling  liquid  by  the  aid  of  a  flat  strainer.  The 
orgaiuc  matter  present  in  the  solution  is  removed  by  the  aid  of  a  solution  of  glue — 
from  20  to  50  grms.  of  glue  dissolved  in  2  litres  of  water  are  taken  for  each  hundred- 
weight of  saltpetre.  In  order  that  the  saltpetre  may  crystallise,  the  quantity  of 
water  is  increased  to  1000  litres,  and  as  soon  as  this  water  is  added  the  organic 
matter  entangled  in  the  glue  rises  as  a  scum  to  the  surface  and  is  removed.    The 


138  CHEMICAL  TECHNOLOGY. 

operation  having  progressed  so  far,  and  the  liquid  being  rendered  quite  clear,  it  is 
kept  at  a  temperature  of  88^  for  about  twelve  hours,  and  then  carefully  ladled  into 
copper  crystallising  vessels,  constructed  with  the  bottom  a  little  higher  at  one  end 
than  at  the  other.  The  solution  would  yield  on  cooling  large  crystals  of  saltpetre, 
but  this  is  purposely  prevented  by  keeping  the  liquid  in  motion  by  means  of  stirrers, 
so  as  to  produce  the  so-called  flour  of  saltpetre,  which  is  really  the  salt  in  a  finely- 
divided  state.  This  is  next  transferred  to  wooden  boxes  termed  wash- vessels,  lo  feet 
long  by  4  feet  wide,  provided  with  a  double  bottom,  the  inner  one  being  perforated ; 
between  the  two  bottoms  holes  are  bored  through  the  sides  of  the  vessel  and  when 
not  required  plugged  with  wooden  pegs.  Over  the  flour  of  saltpetre  contained  in 
these  wooden  troughs,  6o  lbs.  of  a  very  concentrated  solution  of  pure  nitrate  of 
potassa  are  poured,  and  allowed  to  remain  for  two  to  three  hours,  the  plugs  being 
left  in  the  holes.  The  plugs  are  then  removed,  the  liquor  run  off,  the  holes  again 
plugged,  and  the  operation  twice  repeated,  first  with  a  fresh  6o  lbs.,  and  next  with 
24  lbs.  of  the  solution  of  nitrate  of  potassa,  followed  in  each  case  by  an  equal  quan- 
tity of  cold  water.  The  liquors  which  are  run  off  in  these  operations  are  of  course 
collected,  the  first  being  added  to  the  crude  saltpetre  solution,  while  the  latter,  being 
solutions  of  nearly  pure  nitre,  are  again  employed.  The  saltpetre  is  next  dried  at  a 
gentle  heat  in  a  shallow  vessel,  sifted,  and  packed  in  casks. 
preiMuvtion  of  Nitrate  During  the  last  twenty  years  the  preparation  of  nitrate  of 
Guii-Hatpetre.  potassa  from  Chili-saltpetre  has  become  an  important  branch  of 
manufacturing  industry.  The  product  obtained  by  any  of  the  following  processes  is 
called  *'  converted-saltpetre,"  to  distinguish  it  from  the  preceding  preparation.  The 
method  of  procedure  may  be  one  of  the  following : — 

I.  The  nitrate  of  soda  is  decomposed  by  means  of  chloride  of  potassium — 

100  kilos,  of  sodic  nitrate  \     .  .^   f  119*1  kilos,  potassa  nitrate. 

87*9  kilos,  of  potassium  chloride/  ^        \  68'8  kilos,  common  salt 

^^  MM.  Longchamp,  Anthon,  and  Euhlmann  first  suggested  this  mode  of  preparation, 
which  is  now  generally  used  on  the  large  scale,  as  the  decomposition  of  both  salts  is 
very  complete,  and  as  the  common  salt  as  well  as  the  saltpetre  can  be  utilised.  The 
chloride  of  potassium  is  obtained  by  the  decomposition  of  camallite,  or  by  means 
already  mentioned. 

Equivalent  quantities  of  nitrate  of  soda  and  of  chloride  of  potassium  are  dissolved 
in  water  contained  in  a  cauldron  of  some  4000  litres  cubic  capacity.  As  the  nitrate 
of  soda  of  commerce  (Chili-saltpetre)  does  not,  as  regards  purity,  vary  very  much 
firom  96  per  cent,  some  7  cwts.  are  usually  taken,  while  of  the  chloride  of  potassium, 
which  varies  in  purity  from  60  to  90  per  cent,  a  quantity  is  taken  corresponding,  as 
regards  the  amount  of  pure  chloride,  to  the  quantity  of  nitrate  of  soda.  The  chloride 
of  potassium  is  first  dissolved,  the  hot  solution  being  brought  to  a  sp.  gr.  =  1*2  to  1-2 1, 
next  the  nitrate  of  soda  is  added,  and  the  liquid  brought,  while  constantiy  heated,  to 
a  sp.  gr.  =  1*5.  The  chloride  of  sodium  continuously  deposited  is  removed  by  per- 
forated ladles,  and  placed  on  a  sloping  plank  so  that  the  mother-liquor  may  flow 
back  into  the  cauldron,  care  being  taken  to  wash  this  salt  afterwards,  so  as  to 
remove  all  nitrate  of  potassa,  the  washings  being  poured  back  into  the  caiddron. 
When  the  liquid  in  the  cauldron  has  been  brought  to  1*5  sp.  gr. — an  aqueous  solu- 
tion of  nitrate  of  potassa  at  15^  with  a  sp.  gr.  =i'i44,  contains  21*074  percent  of  that 
salt — ^the  fire  is  extinguished,  the  liquid  left  to  clear,  the  common  salt  still  present 
canying  down  all  impurities,  and  when  clear  it  is  ladled  into  crystallising  vessels, 


SALTPETRE,  NITRATE  OF  POTASSA.  I39 

which  being  vei^  shallow,  the  crystallisation  is  finished  in  twenty-four  hours.  The 
mother-liquor  having  been  run  ofi^  the  crystals  are  thoroughly  drained  and  covered 
with  water,  which  is  left  in  contact  with  the  salt  for  some  seven  to  eight  hours,  and 
then  ran  off;  this  operation  is  repeated  during  the  next  day ;  the  mother-liquor  and 
irashings  are  poured  back  into  the  cauldron  at  a  subsequent  operation. 

2.  Nitrate  of  soda  is  first  converted  into  chloride  of  sodium  by  means  of  chloride 
of  barium,  nitrate  of  baryta  being  formed,  and  in  its  turn  converted  into  nitrate  of 
potassa  by  the  aid  of  sulphate  of  potassa : — 

a.    85  kilos,  of  nitrate  of  soda       \  yield  |  ^30*5  Iq^os.  nitrate  of  baiyta. 
122  kilos,  of  chloride  of  barium )  ^5^*5  kilos,  of  common  salt. 


p.  130*5  Idles,  of  nitrate  of  baryta 
require  for  conversion  into 
nilxate  of  potassa 


87*2  kilos,  of  potassic  sulphate, 

or 
692  kilos,  of  potassic  carbonate. 

When  sulphate  of  potassa  is  used,  permanent- white,  baryta- white,  or  sulphate  of 
baryta  is  obtained  as  a  by-product,  while  if  carbonate  of  potassa  is  used,  carbonate  of 
baiyta  remains,  and  of  course  may  ie  readily  re-converted  into  chloride  of  barium. 
In  order  to  estimate  the  advantages  of  either  process,  the  following  points  must  be 
kept  Id  view : — a.  Taking  into  consideration  that  it  is  profitable  to  convert  native 
carbonate  of  baryta  into  chloride  of  barium — for  instance,  by  exposing  witherite  to 
the  hydrochloric  acid  fumes  produced  in  alkali  works  by  the  decomposition  of  salt — 
and  to  precipitate  an  aqueous  solution  with  dilute  sulphuric  acid  to  obtain  permanent- 
white,  it  may  be  inferred  that  it  will  also  pay  to  obtain  it  as  a  by-product,  b.  Not- 
withstanding the  complication  of  this  process,  it  is  advantageous  as  producing  a  fetr 
purer  nitrate  of  potassa. 

3.  Nitrate  of  soda  is  converted  by  means  of  potash  into  the  nitrate  of  that  base, 

pore  soda  being  obtained  as  a  by-product : — 

85  kilos.  Chili-saltpetre  ]     *  Id  i  '^''^  kilos,  of  potassic  nitrate. 

69*2  Idlos.  carbonate  of  potassa  I  ^^      153  kilos,  of  soda  (calcined). 

This  mode  of  manufeMJturing  saltpetre  was  first  introduced  into  Germany  during  the 
Crimean  War  (1854-55)  ^7  ^-  Wollner,  of  Cologne,  who  established  large  works  to 
prepare  saltpetre  in  this  way,  and  very  soon  after,  during  the  continuance  of  the  war, 
five  other  manufactories  of  potash-saltpetre  had  been  established  on  this  method. 
In  1862  the  production  amounted  to  7,500,000  lbs.  of  potash -saltpetre,  the  carbonate 
of  potassa  required  being  obtained  from  beet-root  molasses,  the  soda  resulting  as  a 
by-product  being  even  superior  to  that  produced  by  Leblanc's  process. 

4.  Nitrate  of  soda  being  decomposed  by  caustic  potassa  yields  potassic  nitrate  and 
caustic  soda. 

According  to  M.  Lunge's  description,  this  process,  first  suggested  by  MM.  Land- 
mann  and  Gentele,  afterwards  modified  by  M.  Schnitzer,  and  practically  applied  by 
U.  Kollner,  is  carried  on  in  Lancashire  in  the  following  manner : — There  is  added  to 
a  caustic  potash  lye  of  1*5  sp.  gr.,  containing  about  50  per  cent  of  dry  caustic  potassa, 
an  equivalent  quantity  of  nitrate  of  soda,  and  the  whole,  after  a  short  time,  crystal- 
lised. The  nitrate  of  potassa  having  been  separated  from  the  mother-liquor,  that 
fluid,  the  density  of  which  has  been  greatly  decreased  by  the  reaction,  is  by  evapora- 
tion again  brought  to  its  former  density,  and  ^delds  on  cooling  another  crop  of 
crystals  of  potash-saltpetre.  Usually  there  then  only  remains  a  solution  containing 
caustic  soda  with  saline  impurities ;  sometimes,  however,  a  third  crop  of  crystals  is 
obtained.    The  deposit  during  the  evaporation  is  chiefly  carbonate  of  soda  derived 


140  CHEMICAL  TECHNOLOGY. 

from  the  chloride  of  sodioin  contained  in  the  potassium  chloride  from  which  the 
canstic  potassa  is  made,  this  chloride  heing  also  converted  into  carhonate.  The 
small  quantities  of  undecomposed  chlorides  of  potassium  and  sodium  and  sulphate  of 
lime  are  retained  in  the  mother-liquor,  which  is  evaporated  to  dryness  and  ignited, 
yielding  a  dry  caustic  soda  of  a  hluish-colour.  The  crystallised  nitrate  of  potassa 
is  now  carefully  refined  to  remove  all  impurities  to  ahout  o'l  per  cent  of  chloride  of 
sodium,  converted  into  saltpetre-flour,  and  treated  as  already  described.  Notwith- 
standing that  the  various  operations  have  been  carried  on  in  iron  vessels,  the  salt 
does  not  contain  any  of  this  metal,  nor  is  the  colour  in  any  way  affected.  The  flour 
is  dried  in  a  room  2  metres  wide  by  5  metres  in  length,  built  of  brick- work,  similarly 
to  the  chloride  of  lime  rooms,  and  having  a  pointed  arched  roof  2  metres  in  height 
The  saltpetre-flour  is  spread  on  a  wooden  floor,  under  which  extends  a  series  of  hot- 
air  pipes,  keeping  the  temperature  at  70^  and  very  rapidly  efiecting  the  drying. 

Testing  the  saitpetn.  If,  whcu  perfectly  pure,  saltpetre  is  carefully  fused,  and  allowed 
to  cool,  it  becomes  a  white  mass,  exhibiting  a  coarsely  radiated  fracture ;  even  so 
small  a  quantity  as  ^th  of  chloride  of  sodiimi  causes  the  fracture  to  appear  somewhat 
granular ;  with  ^th  the  centre  is  not  at  all  radiated,  and  is  less  transparent ;  and 
with  ^th  the  radiation  is  only  slightly  perceptible  at  the  edges  of  the  fructure. 
Nitrate  of  soda  has  the  same  effect.  This  method  of  testing  the  purity  of  nitre,  due 
to  M.  Schwartz,  is  employed  in  Sweden,  where  every  landowner  pays  a  portion  of 
his  taxes  in  saltpetre  of  a  specified  degree  of  purity.  A  great  number  of  methods  of 
testing  saltpetre  have  been  suggested  by  various  authors  for  the  purposes  of  the 
manu£B.cture  of  gunpowder,  not,  however,  in  sufficiently  general  use  to  interest  the 
reader.  Werther*s  test  for  chlorine  and  sulphuric  add  is  by  solutions  of  the  nitrates 
of  baryta  and  silver;  the  silver  solution  is  such  that  each  division  of  the  burette 
corresponds  to  0004  grm.  of  chlorine,  and  with  the  baryta  solution  to  0*002  grm.  of 
sulphuric  acid.  According  to  Reich's  plan,  0*5  gim.  of  dried  and  pulverised  saltpetre 
is  ignited  to  a  dull  red  heat,  with  from  4  to  6  times  its  weight  of  pulverised  quartz ; 
the  nitric  acid  is  expelled,  the  loss  of  weight  consequently  indicating  the  quantity, 
the  sulphates  and  chlorides  not  being  decomposed  at  a  duU  red  heat.  If  the  loss 
=  df  we  have  1874  d  nitrate  of  potassa,  or  i'574  d  nitrate  of  soda. 

Qnantttftttre  Eitimatton      This  method,  duo  to  Dr.  A.  Wagner,  is  based  upon  the  &ct 

of  the  Nitric  Acid  in  o        »  x- 

BaitpetzB.  that  when  saltpetre,  or  any  other  nitrate,  is  ignited,  access  of  air 

being  excluded,  with  an  excess  of  oxide  of  chromium  and  carbonate  of  soda,  the  nitric 
acid  oxidises  the  chromic  oxide  according  to  the  formula  Cra03-f-N05=2Cr03+NOi. 
764  parts,  by  weight,  of  oxide  of  chromium  are  oxidised  to  chromic  acid  by  54  parts 
of  nitric  add,  or  of  i  of  chromic  oxide  by  07068  of  nitric  add.  The  operation  is 
performed  by  taking  from  03  to  0'4  grm.  of  the  nitrate,  mixing  it  intimately  with 
3  gims.  of  chromic  oxide  and  i  grm.  of  carbonate  of  soda,  introducing  this  mixture 
into  a  hard  German  glass  combustion-tube,  one  end  of  which  is  drawn  out,  and  a 
vulcanised  india-rubber  tube  attached  to  it,  which  is  made  to  dip  for  about  a  quarter 
of  an  inch  into  water,  while  to  the  other  open  end,  by  means  of  a  cork  and  glass  tube 
bent  at  right  angles,  an  apparatus  is  fitted  for  the  evolution  of  carbonic  add  gajs, 
which  is  made  to  pass  through  the  tube  before  igniting  it,  and  kept  passing  through 
all  the  time  until  the  tube  is  quite  cool  again  after  ignition.  The  contents  of  the 
tube  are  placed  in  warm  water,  and  after  filtration  the  chromic  acid  is  estimated  by 
Rose's  method.  This  process  of  estimating  nitric  acid  has  been  found  to  yield  very 
accurate  results. 


SALTPETRE,  NITRATE  OF  POTASSA.  141 

UMocaattpatn  This  salt  is  employed  for  many  purposes,  the  most  important 
bemg: — i.  The  manufacture  of  gunpowder.  2.  The  mannfactnre  of  snlphuiic  and 
nitric  acids.  3.  Glass-making,  to  refine  the  metal  as  it  is  termed.  4.  As  oxidant  and 
flux  la  many  metallurgical  operations.  By  the  ignition  of  i  part  of  nitre  and  2  of 
irgol,  in  some  cases  refined  argol  (cream  of  tartar),  hlachjiux  is  formed  consisting  of 
in  intimate  mixture  of  carbonate  of  potassa  and  finely  divided  charcoal.  The 
ignition  of  equal  parts  of  saltpetre  and  cream  of  tartar  gives  white  flux^  consisting  of 
a  mixture  of  carbonate  of  potassa  and  undecomposed  saltpetre;  both  these 
mixtures  are  often  used.  Black  flux  may  also  be  made  by  intimately  mixing 
carbonate  of  potassa  with  lamp-black  and  white  flux.  5.  When  mixed  with 
common  salt  and  some  sugar  in  the  salting  and  curing  of  meat.  6.  For  preparing 
floxing  and  detonating  powders.  Baum6's  fluxing  powder  is  a  mixture  of  3  parts  of 
nitre,  i  of  pulverised  sulphur,  and  i  of  sawdust  from  resinous  wood ;  if  some 
of  this  mixture  be  placed  with  a  small  copper  or  silver  coin  in  a  nutshell  and 
ignited,  the  coin  is  melted  in  consequence  of  the  formation  of  a  readily  fusible 
metallic  sulphuret,  while  the  nutshell  is  not  injured.  Detonating  powder  is  a  mix- 
ture of  3  parts  saltpetre,  2  carbonate  potassa,  and  i  pulverised  sulphur ;  this  powder 
when  placed  on  a  piece  of  sheet-iron,  and  heated  over  a  lamp,  will  explode  with  a 
load  report,  yielding  a  large  volume  of  gas : — 


Saltpetre,  6ENO3, 

Potassic  carbonate,  2K2GO39 

Sulphur,  5S. 


'  Nitrogen,  6N. 
Carbonic  acid,  aCOa. 
Sulphate  of  potassa,  5K2SO4. 


7.  For  manure  in  agriculture.     8.  In  many  pharmaceutical  preparations.     9.  For 
the  preparation  of  Heaton  steel. 

iBdientaaiiL  This  salt,  also  known  as  cubical  saltpetre.  Chili-saltpetre,  nitrate 
of  soda,  NaNOj,  containing  in  100  parts  36*47  soda,  and  63-53  P^^^  nitric  add, 
is  found  native  in  the  district  of  Atacama  and  Tarapaca,  near  the  port  of  Uquiqne, 
in  Peru,  in  layers  termed  odUohs  or  terra  ioUtrosa,  0*3  to  I'o  metre  in  thickness,  and 
extendiug  over  more  than  150  miles,  nearly  to  Copiapo,  in  the  north  of  Chili.  The 
deposit  chiefly  consists  of  the  pure,  dry,  hard  salt,  and  is  close  to  the  surfSsice  of  the 
■oil  It  is  also  found  in  other  parts  of  Peru  mixed  with  sand,  in  some  places  close 
to  the  sur&ce  of  the  soU,  in  others  at  a  depth  of  26  metres.  Valparaiso  being  the 
great  exportation  dep6t  for  Peru,  Bolivia,  and  Chili,  both  surface  and  deep  soil  salts 
tfe  met  with  in  the  trade  of  that  important  port.  The  unrefined  Chili-saltpetre  is 
czystalline,  brown  or  yellow,  and  somewhat  moist ;  but  the  salt  sent  to  the  European 
markets  is  commonly  semi-refined  by  being  dissolved  in  water  and  evaporated  to  dry- 
IM88.    The  composition  of  a  sample  in  100  parts  is : — 

Nitrate  of  soda     9403 

Nitrite  of  soda     ...     o'3i 

Chloride  of  sodium       1*52 

Chloride  of  potassium 054 

Sulphate  of  soda 092 

Iodide  of  soda 0*29 

Chloride  of  magnesium       0*96 

Boric  acid traces 

TvaMjx*     •••     •••     •••     .*•     •••     •••     •••  X  9^ 

lOO'OO 


Ml 


CIIE3IICAL  TECHriOLOQY. 


Being  deliquescent  th.c  salt  is  not  employed  in  the  raanufiicture  of  gunpowder,  but 
may  bo  used  for  blasting  powder.  It  is  largely  used  for  the  preparation  of 
sulphuric  and  nitiio  aclda ;  for  piirifjing  caustic  soda ;  for  making  clilorine  in  the 
manufacture  of  bleaching  powders ;  for  the  preparation  of  araeniate  of  soda ;  in  the 
curing  of  meat;  glass -making;  in  the  preparation  of  red-lead :  in  large  quantities  in 
the  conversion  of  crude  pig-iron  into  steel,  by  Hargreaves's  and  bj  Heston's 
processes;  for  preparing  nitrate  of  potassa ;  and  for  the  preparation  of  aitificitl 
manures  and  compoEta,  it  being  used  nnmised  as  a  manure  for  grain  crops. 

It  may  be  seen  from  the  analysis  of  nitrate  of  soda  quoted  above  HibX  that 
salt  contains  a  small  qnontitj  of  iodine,  wliich  at  Tarapaca  is  extracted  from 
the  mother-liquor  remaining  from  tlie  re-crystallisation.  According  to  M.  L.  Kiaflt 
the  iodine  amounts  to  o-jg  grm.  in  i  kilo,  of  crude  nitrate ;  40  kilos,  of  iodine  being 
prepared  per  day.  M,  NoUner  thinks  that  the  formation  of  the  nitre  deposits  in 
Chili  and  other  parts  of  South  America  has  taken  place  nnder  the  influence  of  narioe 
plants  containing  iodine.  In  order  to  give  some  idea  of  the  large  and  increasing 
exportation  of  Chili-saltpetre,  we  quote  from  the  published  statisticB,  that  in  1830, 
18,700  cwts.,  and  in  1869,  2,965,000  cwte.,  were  shipped. 


Nrrmc  Acid. 
MittMyiMiMmtoaiiirtiig  Tj,ig  agiij  iNHOj)  is  generally  manufactured  by  decomposing 
nitrate  of  soda  by  sulphuric  acid,  and  condensing  the  vepours  set  free.  It  is  obtained 
on  the  large  scale  by  placing  in  a  cast. iron  Tesael,  a,  Fig.  65,  the  nitrate  to  be  operated 
upon,  to  which  is  added  by  means  of  a  funnel  strong  aulphnric  acid.  The  lid  is 
replaced,  and  the  Tessel  connected  by  means  of  the  clay'lined  tube,  b,  with  the  glass 
tube,  c,  dipping  into  the  large  stoneware  flask,  n,  which  serves  the  purpose  of  a 
Fta.  65. 


rweiver  This  flflhk  is  connpcled  bv  means  of  a  tubt  i  to  a  similar  vessel  d  and 
that  to  a  third  \estel,  p  ,  and  so  on,  m  order  to  completely  condense  the  vapours 
which  might  have  escaped  through  the  first,  second,  and  third  vessels.  The  iron 
vessel,  *,  is  heated  by  means  of  the  fire  placed  in  the  hearth,  f,  the  smoke  and  hot 
gases  being  carried  off  by  a  n.  At  the  outset  of  the  operation  the  damper,  d.  is 
80  regulated  as  to  shut  off  the  lower  channel,  and  cause  the  smoke  and  hot  gases 
to  pass  through  r,  heating  the  ves-sela  i>,  n',  and  d  ',  this  precaution  being  required  to 


NITRIC  ACID.  1^3 

prevent  their  cracking  by  the  hot  ncid  vaponrs  eotcring  from  a.  Ab  soon, 
however,  as  the  distillatdon  has  &irlj  commenced,  the  damper  is  altered  to  shut  off  e, 
and  pass  the  hot  air  and  gaaes  through  o.  The  nitric  acid  condensed  in  the  first 
receiver  is  aofficientlj  strong  for  immediate  use,  but  to  facilitate  the  condensatian 
■ome  wBiter  has  been  poured  through  the  openings,  b'  b",  into  the  other  receivers,  the 
add  from  nhich  is  weaker  and  known  in  the  trade  as  aquafortia. 

Very  frequently  the  distillation  of  nitric  acid  is  conducted  in  a  series  of  glass 
retorts  placed  on  a  sand-bath ;  there  are  generally  two  rows  of  retorts,  the  heating 
^paratns  being  a  galley  oven.  If  the  acid  is  to  be  pure,  the  first  condensations 
ue  collected  in  BepaiBte  receivers,  as  the  acid  first  condensed  contains  hydrochlorio 
•eid  due  to  the  chlorides  contained  in  the  nitrates  under  operation. 

The  proportion  of  materials  employed  is : — 
30  k 

i  The  bianlphate  of  soda  which  remains  may  either  be  used  for  the  preparation  of 

faming  sulphuric  acid,  or  may  be  mixed  with  common  salt,  and  ignited,  to  produce 
hydrochloric  acid  and  neutral  sulphate  of  soda,  available  in  the  preparation  of  sodic 
carbonate. 

The  nitric  add  (NHO3)  resolting  from  the  above  operation  is  a  colonrless, 
transparent  fluid,  having  a  sp.  gr.  of  i'55,  and  boiling  at  So°,  When  diluted  with 
I  water  the  boiling-point  ie  higher.  An  acid  containing  100  parte  (NHOj)  and  50 
I  puts  of  water  boils  at  i2g°,  but  if  the  dilation  with  water  is  carried  ftirther  the 
boiling-point  is  again  lowered ;  conseiinently  when  such  an  acid  is  heated  above  100'' 
I  Ibe  result  is  that  at  first  water  with  only  a  trace  of  acid  distils  over,  and  if  the  process 
!  be  contdnned  the  boiling-point  gradually  increases  until  it  reaches  130°,  when  there 
I  distils  over  what  is  termed  double  aquafortis,  sp-  gr.  =  i'35  to  1*45,  ordinary  or  single 
1        tquafortis  having  a  sp-  gr.  =  I'lg  to  1*25.      Nitric  acid,  when  in  contact  with  air, 

emibi  fumes,  owing  to  the  absorption  of  water  from  the  atmosphere. 
I  ""'jldli.'""'  Ths  stronger  acid  manufactured  as  described  is  usually  of  a  yellow 
Mlonr,  due  to  the  presence  of  hyponitric  acid.  If  a  colourless  acid  is  desired,  Ihe 
ernde  acid  mnst  be  snbmitled  to  a  bleaching  operation,  consisting  of  fhe  following: — 
I  The  coloured  acid  is  poured  into  large  glass  vessels  placed  <Fig.  661  in  a  water- 
bath,. heated  to  80°  to  90°,  and  left  in  these  vessels  as  long  as  any  coloured  vapours 

[  Fio.M. 


•re  giren  oK  The  escaping  hyponittio  add  is  eanied  by  means  of  glass  or  glazed 
wrthenwue  tubes  either  into  a  sulphuric  add  chamber  and  there  utilised,  or  into 
the  flue  of  a  chinmey,  and  thus  into  the  aii.  Any  hydrochloric  acid  present  in  the 
nitric  acid  is  also  carried  off  as  chlorine.     In  order  to  remove  any  sulphuric  acid 


144 


CHEMICAL    TECHNOLOGY. 


it  is  neceaBarj  to  distil  the  uitria  aoii  over  pore  nitrate  of  baij'ta,  whUe  the  last 
traaea  of  hydrochloric  acid  can  be  remoTed  bj  distillAtion  over  pore  nitrata  of  silver. 
ooudKuuiDDof  thaNiuk.  More  recently  improTements  have  been  made  in  the  matm- 
fftotu^  of  nitric  acid,  bearing  eqtecially  upon  the  poBBibility  of  omitting  the 
bleaching  procesB,  and  a  better  mode  of  condensing  the  vaponrH  of  the  acid.  The 
first  point  is  supplied  by  an  arrangement  introdnoed  in  the  manniactorfof  M.  Chev6, 
in  Paris.  Every  practical  chemist  knows  that  the  red  vapoors  appear  only  at 
the  outset  and  towards  the  end  of  the  distillation  of  the  nitric  acid,  and  it  is  there- 
fore only  reqaired  to  distil  fractionalljto  obtain  on  the  one  hand  a  red-coloured  add, 
the  addum  nitroio-nitrieum  or  aeidum  nttrumm  fumam  /ortittitw  of  the  phanna- 
ceatistfi,  and  on  the  other  a  colonrless  acid,  which  can  be  forthwith  delivered  to  the 
consumer.  In  order  to  practically  effect  the  fractional  distillation,  a  tap  of  porcelain 
or  hard-fired  stoneware,  conatnieted  aa  exhibited  in  Fig.  6j,  is  fixed  by  means  of  a, 
in  commnnjcation  with  the  iron  distilling  vessel,  while  the  tubes  B  and  b  are 
connected  with  two  different  receivers.    The  tap  is  bored  in  such  a  manner,  that  at 


Fia.  67. 


pleasure  either  the  communication  be- 
tween A  and  b',  or  the  communication 
between  &  and  b,  can  be  established. 

By  proper  management,  therefore,  it  ia 
possible  to  separate  the  red-colonred 
acid  entirely  and  without  any  addi- 
tional   expense,    from    the    colonrlesa 

A  second  improvement,  contrived  by  MM.  Plisson  and  Devers,  Paris,  bears  upon  the 
condensation  apparatus,  which  consista  in  their  works  of  a  battery  of  ten  peculiarly 


constructed  bottles,  uz  of  which  are  open  at  the  bottom  and  fonnel- shaped,  so  as  to  Gl 
in  the  necks  of  lai^ecaruoys,  o.  Fig.  68.  From  a  cylinder  not  shown  in  the  engraving, 
being  hidden  by  the  wall,  n,  a  stoneware  tnbe  ia  connected  with  the  bent  glass  tube,  s. 


NITRIC  ACID,  145 

which  oommunioates  wi£h  one  of  the  three  tubnlatures  of  the  first  carboy,  a, 
which  serves  to  collect  the  acid,  that,  bj  the  boiling  over  of  the  mixture  in  the  iron 
Tessel,  has  been  rendered  more  or  less  fonl.  The  carboy  a  is  provided  with  a  small 
tube,  T,  arranged  to  act  as  a  hydraulic  valve  in  such  a  manner  that,  when  the  fluid  in 
the  carboy  has  risen  to  a  height  of  some  centimetres,  any  additional  fluid  entering  a 
is  carried  off  into  th^  well- stoppered  carboy,  a'.  The  second  tubulature  of  the 
carboy  a  is  fitted  with  a  funnel  through  which  water  flows  from  the  bottle  f  into  a, 
thereby  aiding  the  condensation.  The  acid  vapours  pass  through  the  curved  glass 
tube  F,  into  the  carboy  b,  from  which,  as  likewise  from  the  carboys  b'  and  b",  the 
condensed  fluid  is  carried  by  the  tube  t  into  the  carboy  a".  Any  vapours  which 
escape  condensation  in  b  are  carried  off  to  c,  and  thence  to  d,  a  portion  of  the  acid 
being  condensed  in  each  of  the  vessels,  and  flowing  back  first  to  b  and  then  to  a". 
Any  vapour  not  condensed  in  0  and  n  is  conducted  by  the  glass  tube  o,  first  to  n', 
next  to  c",  and  finally  to  b,  where  condensation  takes  place.  Any  vapours  not  now 
condensed  are  carried  to  b",  c",  n",  and  finally  to  the  chimney  stalk.  The  Mariotte 
bottles  f'  and  f"  contain  water,  which  flows  into  the  condensing  vessels  and  dilutes 
the  acid  to  36**  B.  (=1*31  sp.  gr.=42*2  per  cent  NaOs).  In  order  to  reduce  any  pressure 
arising  in  the  vessels  a'  and  a",  a  tube  h,  and  a  similar  one  not  represented  in  the  cut, 
are  connected  with  t  and  t',  for  the  purpose  of  carrying  any  non-condensed  vapour 
into  b",  where  these  vapours  collect. 

Although  this  apparatus  appears  complicated,  the  working  is  very  readily  managed. 
The  acid  vapours  issuing  from  the  distillatory  apparatus  are  partly  condensed  in  the 
vessel  A,  and  thence  carried  to  a',  the  vapours  still  imcondensed  continuing  their 
course  to  b,  b',  b",  the  fluid  there  collected  flowing  back  to  the  general  receiver  a". 
This  i^paratus  when  once  well  put  together,  has  rarely  to  be  repaired,  saves  much 
labour,  and  produces  a  larger  quantity  of  acid  than  the  ordinary  apparatus,  this 
being  due  to  the  more  complete  condensation ;  while  by  the  ordinary  method  only 
125  to  128  kilos,  of  nitric  acid  are  obtained  from  100  kilos,  of  nitrate,  the  quantity 
obtained  by  this  apparatus  amounts  to  132  to  134  kilos.  The  following  brief  descrip- 
tion, illustrated  by  Figs.  69  and  70,  vrill  explain  the  internal  construction  of  the 
bottles  and  of  the  syphon  funnel.  In  each  of  the  carboys  of  the  lowest  row  is 
inserted  a  bent  stoneware  tube,  t.  Fig.  69,  the  opening,  o,  of  which  is  outside 
the  bottle ;  a  narrow  space,  l,  admits  the  fluid  to  the  interior  of  the  tube,  and  it 
is  dear  that  the  acid  can  only  attain  a  certain  height  in  the  carboy.  The  syphon 
fhnnel  consists  of  a  stoneware  tube  about  3  centims.  in  diameter,  the  side  of  which. 
Fig.  70,  is  perforated  in  a  longitudinal  direction ;  any  fluid  therefore  flowing  into  this 
tabe  from  £  can  only  reach  to  the  opening  o. 

otk«  suthod*  of  nitric  Add      The  following  methods,  differing  from  that  above  desoribed, 
MurateetoFe.  must  here  be  mentioned  ;  but  the  reader  ahould  not  infer  that  they 

ire  aotually  in  practice : — i.  Action  of  chloride  of  manganese  (chlorine  preparation 
reaidiies)  upon  mtrate  of  soda.  When  a  mixture  of  these  salts  is  heated  to  about  230*, 
nitroos  vapours  (NO^+O)  are  evolved,  and  there  remains  oxide  of  manganese,  which  can 
be  again  employed  in  the  manufacture  of  chlorine. 


sMnCla 

and       |-  yield 
xoNaNOj 


[  yi< 


(2MnO+3MnOa), 

loNaCl, 

ioNOa-J-0. 

By  causing  the  mixture  of  hyponitric  acid  and  oxygen  to  come  into  contact  with  water 
in  the  condensing  apparatus  nitric  acid  results,  the  excess  of  hyponitric  acid  being  decom- 
posed into  nitric  acid  and  dentoxide  of  nitrogen.  If  the  quantity  of  air  in  the  apparatus 
is  sttiSciently  large  to  oxidise  the  entire  bulk  of  the  nitrogen  deutoxide  into  nitric  acid, 
this  process  is  continuous,  but  if  there  is  not  enough  air,  the  ^utoxide  of  nitrogen  is 

L 


X46 


CHEMICAL  TECHNOLOGY. 


dissolved  in  the  nitric  acid,  any  excess  of  that  gas  escaping.  From  the  experiments  on  thid 
process  by  Dr.  Euhlmann,  who  used  clay  retorts,  it  appears  that  100  parts  of  nitrate  of 
soda  yield  from  125  to  126  parts  of  nitric  acid  at  35°  B ;  this  result  almost  agrees  with 
that  obtained  by  the  ordinary  process.  Dr.  Kuhlmann  also  instituted  experiments  with 
other  chlorides,  viz.,  those  of  calcium,  magnesium,  and  zinc,  the  result  being  the  forma- 
tion of  nitric  acid  and  chloride  of  sodium  with  lime,  magnesia,  and  oxide  of  zinc. 

2.  Action  of  certain  sulphates  upon  alkaline  nitrates.  Dr.  Euhlmann  has  proved  by  a 
series  of  experiments  that  the  sulphates,  including  only  those  having  no  acid  properties* 
decompose  the  idkaline  nitrates.  Sulphate  of  manganese  decomposes  nitrate  of  soda,  the 
result  being  the  formation  of  products  similar  to  those  when  chloride  of  manganesft 
is  employed ;  similar  reactions  take  place  when  sulphate  of  zinc,  sulphate  of  magnesia, 
and  gypsum  are  used  for  this  purpose. 

3.  From  nitrate  of  soda  and  carbon,  yielding  soda  and  nitric  add. 

4.  From  nitrate  of  soda  and  silica  or  alumina,  yielding  nitric  acid,  silicate  of  soda, 
and  soda. 

5.  From  nitrate  of  baryta  and  sulphuric  acid,  without  distillation;  the  nitric  add 
(=sio*  to  11"  B.)  decanted  from  the  sulphate  of  baryta  (permanent  white)  can  be  conoen- 
trated  by  boiling  to  25'  B. 

Dauitjof  Nitric  Add.      Accordisg  to  Eolb,  the  specific  gravity  of  nitric  add  bears  to  the 

quantity  of  concentrated  acid  contained  the  following  relation : — 


100  parte 

• 

1  oontaii 
N2O5. 

1            Density. 
1 

100  parts  contain 
NHO3.        NaOj. 

Dendty. 

• 

NHO3. 

at  o**.    at 

15^0. 

ato^ 

at  i5*C. 

10000 

8571 

I  559 

1-530 

5500 

47-14 

1-365 

1-346 

97-00 

8314 

1548 

1*520 

5099 

43-70 

1*341 

1323 

9400 

8057 

I  537 

1-509 

45-00 

3857 

1*300 

1*284 

9200 

7885 

1529 

1-503 

40*00 

34*28 

1*267 

1*251 

9100 

7800 

1526 

1*499 

33-86 

29*02 

1*226 

1*211 

9000 

7715 

1522 

1-495 

30*00 

2571 

1*200 

1185 

8500 

7286 

I  503 

1*478 

2571 

22*04 

1*171 

I-I57 

8000 

68*57 

1-484 

1*460 

23*00 

19*71 

1*153 

II38 

7500 

6428 

1465 

1-442 

20*00 

17*14 

1132 

I-I20 

6996 

6000 

.i'444 

1-423 

1500 

12*85 

1*099 

1089 

6507 

5577 

1*420 

1*400 

11*41 

9-77 

1-075 

1*067 

6000 

51*43 

i'393 

1*374 

4*00 

3*42 

1*026 

I-022 

2*00 

1*71 

1013 

I'OIO 

The  following  table  exhibits  comparativ 

e  data  of  density  and 

degrees  accordug  to 

jjaume . — 

100  parts 

contain  at 

100  parts  contain  at 

Degrees  according 
to  Baum^. 

Density. 

{ 

1 

15" 

0. 

NHO3. 

N2O5. 

NHO3. 

Na05. 

6 

1044 

6*7 

57 

7*6 

6-5 

7 

1052 

80 

6-9 

9-0 

77 

9 

1*067 

10*2 

8*7 

11*4 

9-8 

10 

1075 

11*4 

9-8 

12*7 

iO'9 

15 

i-ii6 

17*6 

15-1 

19*4 

166 

20 

i-i6i 

24*2 

20*7 

26*3 

22*5 

25 

I*2IO 

31-4 

26*9 

33-8 

28*9 

30 

1*261 

• 

39-1 

33-5 

41-5 

35-6 

35 

1*321 

480 

41*1 

50*7 

43*5 

40 

1-384 

584 

500 

61  7 

529 

45 

1-454 

722 

61 '9 

78*4 

72*2 

46 

1-470 

76*1 

65*2 

830 

711 

47 

1-485 

80*2 

68*7 

87-1 

747 

NITRIC  ACID. 

47°  B.  correspond  to  96° 

Twaddle. 

• 

46°    .. 

»» 

92° 

»» 

45°    .. 

y* 

88° 

>» 

43°    .. 

84° 

«• 

4*°    .. 

80° 

M 

38°    ,. 

70° 

»» 

34°    .. 

ff 

60° 

»t 

89°     .. 

50° 

Jt 

25°    .. 

40° 

«« 

20°    „ 

30° 

ff 

14°    .. 

20° 

»» 

7°    .. 

10° 

»> 

Titricaci 

id  of  1-52  sp.  gr.  boils  at  86" 

1-50 

99° 

1*45 

"5° 

1-42 

123° 

1-40 

"9° 

I '35 

117° 

130 

113° 

I'20 

108° 

115 

104'' 

_  ii_  - 

J.? 

_*     -_«1^ 

•              •  *     t^ 

147 


rndi«HttrieA«id.  When  in  the  preparation  of  nitric  acid  there  is  taken  for  i  mole- 
cule of  nitrate  of  potassa  i  molecule  of  snlphuric  add,  there  is  obtained  by  distilla- 
tion a  reddish-yellow  flnid,  consisting  of  a  mixture  of  nitric  and  hyponitric  acids, 
kzu)wn  as  red  fuming  nitric  acid.  When  equal  molecules  of  nitrate  of  potassa  and 
ndphuric  acid  are  taken,  only  one-half  of  the  quantity  of  nitric  acid  is  expelled, 
while  the  other  half  is  decomposed  into  hyponitric  acid  and  oxygen,  the  former  com- 
lamng  with  the  nitric  acid,  and  forming  the  fdming  nitric  acid.  When  in  the  prepa- 
nUion  of  nitric  acid  by  the  decomposition  of  the  potassium  or  sodium  nitrate,  two 
mdecoles  of  sulphuric  acid  are  employed,  all  the  nitric  acid  in  these  salts  is 
obtained,  and  there  remains  in  the  retort  bisulphate  of  either  base.  When  nitrate 
of  soda  is  employed,  it  is,  owing  to  the  easier  decomposition  of  this  salt  by  sulphuric 
^d  not  necessary  to  use  exactly  2  molecules  of  sulphuric  acid ;  1*25  to  1*50  mole- 
cules of  that  acid  have  been  found  to  be  practically  sufficient.  100  parts  of  Ghili- 
udtpetre  yield  120  to  130  parts  of  nitric  acid  at  36°  B. 

The  red  fuming  nitric  acid  is  now  generally  prepared  by  adding  to  the  ordinary 
ooDcentrated  nitric  acid  a  substance  which  effects  its  decomposition.  Sulphur 
Itts  been  employed  for  this  purpose,  but  starch  is  generally  used,  and,  according  to 
H.  G.  Bmnner's  recipe,  in  the  following  manner: — To  100  parts  of  saltpetre, 
3i  parts  of  starch  are  added,  and  placed  in  a  capacious  retort,  into  which  is  poured 
100  parts  of  strong  sulphuric  add,  sp.  gr.= i  85.  The  distillation  usually  sets  in  with- 
out the  aid  of  heat,  but  towards  the  end  of  the  operation  the  application  of  a  gentle 
beat  is  required.  100  parts  of  nitrate  of  potassa  yield  by  this  method  about  60  parts 
of  filming  nitric  add.  The  retort  in  this  operation  should  not  be  filled  to  more  than 
one-third  of  its  capadty,  owing  to  the  very  strong  evolution  of  gas  which  takes  place. 

ttaoc  HimeAdd.  The  technical  application  of  nitric  acid  is  based  on  its  property  of 
oxidation  when  in  contact  with  certain  substances,  the  acid  splitting  up  iuto  deut- 

L  2 


148  CHEMICAL  TECHNOLOGY. 

oxide  of  nitrogen,  hyponitric  acid,  and  ozone,  the  latter  forming  with  the  body 
which  caused  the  decomposition  of  the  acid  either  an  oxide  or  a  peculiar  componnd, 
while  the  hyponitric  acid,  when  organic  substances  are  present  capable  of  combining 
with  it,  forms  the  nitro-compounds,  nitrobenzole,  nitronaphthaline,  nitroglycerine, 
nitromannite,  nitrocellulose,  or  gun-cotton,  &c.  A  large  number  of  metals  are 
soluble  in  moderately  concentrated  nitric  acid,  but  the  strongest  add  fails  to 
act  upon  iron  and  lead.  Proteine  compounds,  albumen,  the  skin  of  the  hands,  silk, 
horn,  feathers,  &c.,  are  stained  yellow  by  nitric  acid,  hence  the  use  of  this  acid 
in  dyeing  silk.  If  the  acid  is  in  contact  with  these  substances  for  any  length  of  time» 
they  are  completely  decomposed,  and  partly  converted  into  picric  acid.  Starch, 
cellulose,  and  sugar,  are  converted  by  the  action  of  nitric  acid  into  oxalic  add; 
but  very  dilute  nitric  add  converts  starch  into  dextrine,  and  concentrated  add 
into  xyloidine.  Owing  to  the  property  nitric  add  possesses  of  destroying  certain 
pigments — ^for  instance,  indigo — ^it  is  sometimes  employed  in  calico  printing  to  produce 
a  yellow  pattern  on  an  indigo  ground.  This  add  is  also  used  in  dyeing  woollen 
materials ;  in  hat-making,  to  prepare  a  mercurial  solution  used  in  dressing  felt  hats ; 
in  the  manufacture  of  sulphuric  acid ;  in  the  preparation  of  lacquers ;  in  the  prepa- 
ration of  nitrate  of  iron,  a  mordant  used  in  dyeing  silk  black ;  for  preparing  picric 
add  from  carbolic  add,  and  naphthaline-yellow  from  naphthaline ;  inthemanu&ctnre 
of  nitrobenzol,  nitrotoluol,  and  phthalic  acid ;  and  for  the  preparation  of  nitrate 
of  silver,  arsenic  acid,  fulminate  of  mercury,  nitroglycerine,  dynamite,  &c. 


Technoloot  op  the  ExPLOsrvE  Compounds. 

a.  Ounpowder,  and  the  Ch^mUtry  of  Fireworks,  or  Pyrotechny. 

ononopowddrinoeneni.  The  substauce  kuowu  as  gonpowdor,  or  simply  as  powder,  is 
a  more  or  less  finely  granulated  mechanical  mixture  of  saltpetre,  sulphur,  and  char- 
coal, the  quantities  of  these  materials  being  properly  defined.  It  ignites  at  300^ 
also  when  touched  with  a  red-hot  or  burning  body,  or  under  certain  conditions  by 
friction  or  a  sudden  blow.  Powder  under  these  conditions  bums  off  rapidly  but  not 
instantaneously,  yielding  as  the  products  of  its  combustion  nitrogen,  carbonic  add, 
or  carbonic  oxide,  while  there  remains  a  solid  substance  consisting  of  a  mixture  of 
sulphate  and  carbonate  of  potassa.  When  the  powder  is  ignited  in  a  closed  vessel, 
the  sudden  evolution  of  the  large  volume  of  gases  causes  a  pressure  imj^osdble  to  be 
withstood ;  and  even  in  guns  and  large  ordnance,  in  which  one  dde  of  the  vessel  is 
formed  by  the  yielding  shot,  the  metal  forming  the  other  sides  must  possess  great 
elasticity.  In  guns  and  artillery  the  pressure  only  lasts  as  long  as  the  ball  is  inside 
the  gun,  therefore  the  slower  the  combustion  of  the  powder  through  its  entire  mass, 
the  lower  is  the  velocity  of  the  projectile. 

ManafMtnn  of  onnpowder.  It  is  cssential  that  the  materials  employed  in  the  manufcusture 
of  powder  should  be  very  pure;  the  saltpetre  should  nof  contain  any  chlorides;  the 
sulphur  should  be  free  from  sulphurous  acid,  hence  not  flowers  of  sulphur  but 
refined  roll  sulphur  is  used  ;  and  lastly  the  charcoal  requires  very  great  attention. 
The  wood  from  which  it  is  intended  to  prepare  a  charcoal  for  gunpowder  should  be 
such  as  yields  the  least  posdble  quantity  of  ash,  while  the  charcoal  should  be  soft 
like  that  used  in  pharmacy.  The  stems  of  the  hemp  and  flax  plants,  espedally  the 
former,  yield  excellent  charcoal,  but  in  oonsequence  of  the  limited  supply,  the  wood 
of  the  wild  plum  tree  (Pruntu  padus)  is  largely  used  in  Germany,  fVatnce,  and 


EXPLOSIVE  COMPOUNDS.  149 

Belginm;  and  in  England  the  lime,  willow,  poplar,  horse-chestnut,  Tine,  hazel, 
ehenj,  alder,  and  other  light  white  woods  are  employed  for  this  purpose.  All  these 
varieties  yield  on  being  carbonised— effected  in  various  ways,  in  retorts  similar  to 
those  used  in  gas-works,  in  pits  dug  in  the  earth,  by  the  aid  of  superheated  steam, 
the  wood  being  placed  in  boilers,  &g. — ^from  35  to  40  per  cent  charcoal.  The  tempe- 
ratore  during  the  progress  of  carbonisation  being  kept  as  low  as  possible,  there  is 
obtained  a  very  soft  reddish-brown  chai'coal,  known  as  charhon  toujb.  The  charcoal 
prepared  in  cylindrically-shaped  retorts  is  very  inappropriately  designated  distilled 
charcoal. 

'JRSStoMSffiSSi      These  operations  include :— 

I.  The  pulverising  of  the  ingredients.  2.  The  intimate  mixing  of  these  sub- 
Btances.  3.  The  moistening  of  the  mixture.  4.  The  caking  or  pressing.  5.  The 
gnnnlation  and  sorting  of  the  grain,  as  it  is  termed.  6.  Surfacing  the  powder. 
7.  Drying.    8.  Sifting  from  the  dust. 

pnwftriBcUM  lagndienta.      This  Operation  can  be  performed  in  three  different  ways  : — 

a.  By  means  of  revolving  drums. 

b.  By  mill-stones ;  or 
0,  In  stamping-mills. 

0.  The  pulverisation  by  means  of  revolving  drums  is  an  invention  due  to  the  French 
rerolation,  and  has  the  advantages  of  being  very  effective,  rapid  in  ezeoution,  and  of  pre- 
ventmg  the  flying  about  of  the  ingredients  in  a  fine  dust.  The  drums  are  made  of  wood, 
lined  with  stout  leather,  and  provided  with  a  series  of  projections.  The  substance  to  be 
pulverised  is  put  into  the  drum  with  a  number  of  bronze  baUs  of  about  i  inch  diameter, 
their  action  aided  by  that  of  the  projections,  when  the  drum  is  turned  on  its  horizontal 
ans  at  a  moderate  speed,  soon  effecting  a  reduction  to  a  fine  powder.  The  oharooal 
iud  sulphur  are  separately  pulverised ;  the  saltpetre  being  obtained  as  a  flour.  (See 
Saltpetre). 

h.  Qrindinff  by  the  aid  of  null-stones.  Two  heavy  vertical  stones,  similar  to  those  in 
use  for  emshing  linseed,  revolve  on  a  fixed  horizontal  stone.  This  contrivance  is  the  most 
fnqnently  used. 

e.  Stampers  are  now  employed  only  in  small  powder-mills.  Frequently  10  to  12  stamps 
made  of  hard  wood  are  placed  in  a  row,  each  stamp  being  fitted  with  a  bronze  shoe,  the 
entire  wei^t  being  about  i  cwt.  The  stamps  are  moved  by  machinery,  and  make  from 
40  to  60  beats  a  minute.  The  materials  to  be  pulverised  are  placed  in  mortar-shaped 
eanties  in  a  solid  block  of  oak  wood,  each  cavity  containing  16  to  20  lbs.  In  Switzerland 
hammers  instead  of  the  stampers  are  employed. 

HhfagtbaiBcndiMita.  The  mixing  is  performed  by  the  aid  of  drums  similar  in  size 
and  shape  to  those  used  in  the  pulverisation,  but  made  of  stout  leather  instead  of 
wood.  The  mixing  of  100  kilos,  of  the  ingredients,  aided  by  the  action  of  150  bronze 
halls,  takes  folly  three  hours,  the  drum  making  ten  revolutions  a  minute.  It  is 
Qsmd  to  moisten  the  materials  with  i  to  2  per  cent  of  water,  supplied  by  fine  jets 
legolated  by  taps. 

When  stampers  and  mill- work  are  employed,  the  sulphur  and  charcoal  are  first 
•epsrately  pulyerised  by  1000  blows,  and  saltpetre  having  been  mixed  with  these 
ingredients  in  the  proper  proportion,  the  machinery  is  again  set  in  motion,  and  at 
first,  after  every  2000  blows,  and  then  after  every  4000  blows,  the  contents  of  the 
stamp-holes  are  removed  from  the  one  to  the  other,  this  operation  being  repeated 
some  six  or  eight  times.  Where  drums  are  used  for  the  mixing  operation,  the 
moistening  takes  place  after  the  mixture  has  been  removed  to  a  wooden  trough, 
where  8  to  10  per  cent  of  its  weight  of  water  is  added,  care  being  taken  to  stir  with  a 
Wooden  spatula. 


150  CHEMICAL   TECHNOLOGY, 

^^'^vi^SS!^      ^^^s  operation,  which  in  stamping-mills  is  the  last  of  a  continnottB 

series,  is  separately  performed  where  other  machinery  is  employed.    In  the  French 

and  German  powder-mills,  the  compression  is  effected  in  a  rolling-mill,  the  roQerB 

having  a  diameter  of  o'6  metre.    The  lower  roller  is  made  of  wood,  the  npper  of 

bronze ;  between  the  two  an  endless  piece  of  stont  linen  is  arranged,  and  upon  this 

the  moist  powder  is  placed.    The  cakes  are  i  to  2  centims.  in  thickness,  with  the 

hardness  and  very  much  the  appearance  of  day-slate. 

The  operation  of  preseing  is  of  great  importance ;  the  stronger  the  pressnre  the  greater 
the  quantity  of  aotive  material  present  in  a  given  bulk,  and  henoe  the  larger  the  volume 
of  gas  given  off  by  the  ignition  of  the  powder.  In  many  English  powder-miUs  the 
pressing  is  effected  by  very  powerful  hydnialic  machines,  because,  wit^  oertain  limits, 
the  more  the  matenals  are  pressed,  the  more  slowly  the  powder  bums,  when  finished, 
while  the  temperature  of  ignition  being  lower,  the  expansion  of  the  gases  is  less.  If  the 
powder  were  finished  either  without  having  undergone  any  pressure  at  all,  or  with  only  a 
slight  pressure,  it  would  act  as  a  detonating-powder,  the  decomposition  being  instan- 
taneous throughout  its  entire  mass. 

2S°s^  StofeSSS      The  conversion  of  the  cake  into  granules  is  effected— 

1.  By  means  of  sieves. 

2.  By  means  of  peculiarly  constructed  rollers,  Congreve*s  method ;  or 

3.  According  to  Champy's  method. 

The  granulation  of  gunpowder  by  the  aid  of  sieves  is  carried  on  in  the  following 
manner: — The  sieves  consist  of  a  circular  wooden  frame,  across  which  a  piece  of  parch- 
ment is  stretched  perforated  with  holes ;  the  sieves  are  distinguished  according  to  their 
uses,  and  by  the  size  of  these  holes ;  that  employed  for  breaking  up  the  cake  having 
larger  holes,  and  bearing  a  name  different  from  the  sieves  used  to  produce  the 
granules ;  this  sieve  again  being  distingmshed  from  that  employed  for  sorting  the  powder 
into  the  variously  sized  grain  as  commercially  known.  The  sieves  are  provided  with  a 
so-called  rummer,  a  lens-shaped  disc  made  of  hard  wood,  gnaiac,  box,  or  oak-wood,  motion 
being  imparted  to  the  sieves  by  hand  if  they  are  small,  or  by  suitably  arranged  maohineiy 
if  they  are  large,  in  which  case  Lefebvre's  granulating-machine  fitted  with  eight  sieves  in 
an  octagonal  wooden  frame  is  generally  employed. 

Gongreve's  granulating-machine  consists  of  three  pairs  of  brass  rollers,  0*65  metre 
in  diameter,  provided  with  diamond-shaped  projections  2  millimetres  high,  the  projec- 
tions of  the  upper  rollers  being  coarser  than  those  of  the  others.  The  broken-up  cake  is 
conveyed  to  the  upper  rollers  by  means  of  an  endless  canvas  sheet.  The  mode  of  feeding 
this  sheet  is  somewhat  peculiar  and  ingenious :  the  loose  bottom  of  a  square  box  filled 
with  coarsely  pounded  cake  is  made  to  rise  slowly  upwards,  and  discharge  the  cake  uni- 
formly upon  tiie  sheet  through  an  opening  in  the  side  of  the  box.  The  cake  while  passing 
through  the  rollers  is  granulated,  and  then  showered  upon  two  sets  of  wire-gause  sieves  to 
which  a  to-and-fro  motion  is  imparted.  Below  these  sieves  again  is  a  frame  containing 
wire-gauze,  the  meshes  of  which  are  too  small  to  admit  of  the  passage  of  ordnance  powder, 
while  the  dust  and  cartridge-powder  readily  fall  through  upon  another  wire-gauze,  the 
meshes  of  which  retain  the  rifle-powder  but  let  the  dust  pass.  Hie  quantity  of  dust 
made  by  the  Gongreve  machine  is  very  small,  owing  to  the  fact  that  the  rollers  do  not 
crush  but  break  the  cake.  Ghampy*s  method,  by  wbioh  a  very  round-grained  powder  is 
obtained,  is  performed  in  the  following  manner : — Throng  the  hollow  axis  of  a  wooden 
drum  a  copper  tube,  periorated  with  very  small  holes,  is  carried,  and  from  these  holes 
water  spouts  in  a  fine  spray  upon  the  broken-up  powder-cake  placed  in  the  drmn,  to 
which  a  comparatively  rapid  motion  is  imparted.  Each  drop  of  water  forms  the  nnelens 
of  a  grain  of  powder,  which  is  constantly  increasing  in  size  by  being  turned  round  in  the 
midst  of  a  mass  of  damp  powder-cake;  the  rotation  of  the  dram  is  discontinued  as  soon 
as  the  grain  has  attained  a  sufficient  siee.  The  powder  thus  obtained  is  almost  perfectly 
l^obular,  but  not  of  the  same  size ;  the  sorting  is  effected  by  means  of  sieves,  the  over- 
sized grains  being  returned  to  the  drum,  as  weU  as  the  undersized  grains,  which  become 
the  nuclei  of  proper-sized  grain.  According  to  the  Berne  method,  round-grained  powder 
is  prepared  by  causing  the  angular-shaped  powder  to  be  rotated  in  stout  linen-bags;  but 
by  this  plan  much  dust  is  formed. 

ox«mi!!todSowd«r.      ^^  ^^  ^^  ^^  Operation  is  to  impart  symmetry  to  the  grain,  and 

to  separate  all  the  dust.    It  is  performed  in  drums  similar  to  those  described  above: 

5  cwts.  of  the  powder  is  polished  at  a  time,  the  drums  rotating  slowly  for  a  few  hours. 


EXPLOSIVE  COMPOUNDS.  151 

In  some  countries  the  pcliBhing  is  effected  by  placing  the  powder  in  casks  internally 
pbyided  with  qnadrangnlar  rods.  In  Holland,  Dr.  Wagner  states  that  some  black-lead 
is  added  to  the  powder  daring  this  operation  to  prevent  ignition,  but  this  is  not  generally 
done.  Hic^ily-poliBhed  powder  does  not  readily  attract  moisture,  ^d  is  to  be  preferred 
in  a  fay  damp  climate. 

ikTincuiAPowdw.  It  is  clettT  that  this  operatioii  requires  very  great  oare  in  more 
than  one  respect.  In  small  powder-works  the  powder  is  sometimes  dried  by 
exposure  to  the  heat  of  the  snn,  being  spread  out  on  canvas  sheets  stretched  in 
wooden  frames ;  or  the  diying-room  is  heated  by  a  stove.  In  large  powder-mills 
other  methods  of  drying  the  powder  are  general. 

The  quality  of  the  powder  very  much  depends  on  the  care  bestowed  upon  the  drying. 
A  too  rapid  drying  entails  the  following  disadvantages : — a.  The  powder  may  be  very  wet 
and  not  polic^ed ;  coarse  ordnance  and  ordinary  loilitary  powder  is  never  polished,  and 
hence  blackens  the  hands ;  while,  although  the  water  is  driven  off,  the  nitre  is  carried  to 
the  sor^iee  of  the  grain,  which  thereby  cakes  together,  b.  By  the  too  rapid  evaporation  of 
the  water,  channels  and  cracks  are  made  in  the  grain,  impairing  its  density,  increasing 
its  bulk,  and  rendering  it  more  hygroscopic,  c.  Lastly,  rapid  drying  entails  a  large 
unonnt  of  dust.  For  these  reasons  gunpowder,  before  being  placed  in  the  drying-rooms, 
ii  exposed  for  some  time  to  a  gentle  heat  in  a  well- ventilated  room,  the  heat  from  a  waste 
steam-pipe  being  sufficient. 

"""SaPttSdJf.*""*  Having  been  dried,  the  powder  is  sometimes  glazed,  as  it  is 
termed ;  that  is  to  say,  again  polished  in  the  manner  above  described ;  but  generally 
this  second  polishing  is  dispensed  with,  and  the  dry  powder  cleansed  from  the  dust 
which  adheres  to  it,  by  being  placed  in  bags,  made  of  a  peculiar  kind  of  woollen 
&bric,  and  arranged  in  frame-work  to  which  a  to-and-fro  motion  is  given  by 
machinery,  the  fine  dust  passing  between  the  threads  of  the  fabric  into  a  box.  The 
bss  thus  occasioned  amounts  on  an  average  to  0*143  P^^  cent,  the  dust  consisting 
chiefly  of  charcoal. 

FMv«tiMofOiiiipowd«r.  Good  powdcr  is  recognised  by  the  following  properties: — 
I.  Its  colour  should  be  slate-black ;  when  blue-black  it  indicates  that  the  powder 
contains  too  much  charcoal,  while  a  deep  black  colour  shows  the  powder  to  be  damp. 
If  the  charcoal  employed  was  the  so-called  charhon  raux,  the  colour  of  the  powder 
will  be  a  brown-black.  2.  It  should  not  be  too  much  polished  so  as  to  shine  like 
bonushed  black-lead.  Small  shining  specks  indicate  that  the  saltpetre  has  crystal- 
lised on  the  surface.  3.  The  grains  should  be  uniform  in  size,  unless,  of  course, 
two  differently  sized  powders  have  been  mixed.  4.  The  grain  should  crack  uniformly 
when  strongly  pressed,  should  withstand  pressure  between  the  fingers,  and  should 
not  be  readily  crushed  to  powder  when  pressed  between  the  hands.  5.  When  pul- 
verised the  mass  should  feel  soft ;  hard  sharp  specks  show  that  the  sulphur  has  not 
been  well  pulverised.  6.  Powder  should  not  blacken  the  back  of  the  hands  or  a 
sheet  of  white  paper  when  gently  rubbed.  If  it  does  so,  there  is  either  powder-dust 
or  too  much  moisture.  7.  "When  a  small  heap  of  powder  is  ignited  on  paper  the 
combustion  should  be  rapid,  completely  consuming  the  powder  and  not  setting  fire  to 
the  paper.  If  black  specks  remain,  the  powder  either  contains  too  much  charcoal,  or 
it  is  an  indication  that  that  substance  has  been  badly  incorporated  with  the  rest 
of  the  materials.  Yellow  streaks  left  after  the  ignition  show  the  same  defects  for 
the  sulphur.  If  no  grains  of  powder  remain,  it  is  a  proof  that  the  powder  was  not 
well  mixed ;  when  any  remaining  grains  of  powder  cannot  be  separately  ignited,  the 
flahpetre  used  was  impure.  If  the  powder  on  being  ignited  sets  fire  to  the  paper,  it 
is  a  proof  that  it  is  either  damp  or  of  very  inferior  quality. 


152  CHEMICAL  TECHNOLOGY. 

The  fact  that  different  kinds  of  powder,  although  of  the  same  weight  to  the  cobio 
foot,  do  not  have  the  same  specific  gravity,  is  shown  hy  the  following  table  :— 

X  onbio  foot 
in  pounds  weight.        Bp.  gr. 

Neisse'B  ordnanee  powder 60  177 

„           „            „      (new  mill)      ..     ..  60  r6j 

Berlin  ordnance  powder 60  X'63 

Bossian  ordnance  powder 60^  1*56 

Berne  ordnance  powder  (No.  6)       59I  1*67 

Berlin  rifle  powder  ^ew  mill) 60  1-63 

Berne  rifle  powder  (^o.  4)       6of  1*67 

Honnslow  rifle  powder      59  172 

Berlin  sporting  powder  (old  mill) 62  177 

Le  Bonchet*8  sporting  powder 59^  1-87 

Very  coarse-grained  ordinary  Dutch  powder..  60^  1-87 

Very  coarse-grained  ordinary  Austrian  powder  64 1  172 

Gunpowder  can  absorb  more  than  14  per  cent  of  moistore  from  the  air ;  if  the 
quantity  of  water  thus  taken  up  is  not  above  5  per  cent,  the  powder,  on  being  gently 
dried,  reassumes  its  former  activity ;  but  if  the  quantity  of  water  absorbed  exceeds  that 
amount,  the  gunpowder  will  not  bum  off  rapidly,  and  when  dried  the  single  grains 
become  covered  with  an  efflorescence  of  saltpetre,  of  course  impairing  the  composition 
and  active  qualities  of  the  powder.  Even  what  is  termed  dry  powder  contains  at 
least  2  per  cent  of  hygroscopic  moisture.  Powder  can  be  exploded  by  a  heavy  blow 
as  well  as  by  an  increase  of  temperature,  and  as  regards  its  explosion  by  a  blow, 
very  much  depends  upon  the  material  upon  which  it  is  placed  and  with  which  the 
blow  is  imparted.-  The  following  list  exhibits  in  decreasing  order  the  materials 
between  which  a  blow  most  readily  ignites  powder: — Iron  and  iron,  iron  and 
brass,  brass  and  brass,  lead  and  lead,  lead  and  wood,  copper  and  copper,  copper  and 
bronze.  For  this  reason  gunpowder  magazines  are  provided  with  doors  turning 
upon  bronze  and  copper  hinges,  the  locks  also  being  of  copper.  When  dry  powder 
is  rapidly  heated  to  above  300°  it  explodes.  Even  if  only  a  very  small  portion  of  the 
powder  is  thus  rapidly  elevated  in  temperature,  the  entire  quantity,  be  it  large  or 
small,  is  exploded ;  hence  a  very  small  quantity  touched  by  a  red-hot  or  burning 
body  is  sufficient  to  effect  an  explosion.  It  is  generally  held  that  the  charcoal  is  first 
ignited,  and  that  it  spreads  the  ignition  to  the  otiier  materials.  Although  Mr.  Hearder 
found  by  experiment  that  powder  does  not  ignite  when  touched  with  a  red-hot 
platinum  wire  while  under  the  receiver  of  an  air-pump.  Professors  v.  Schrotter  and 
Abel  proved  that  gunpowder  so  placed  ignited  rapidly  when  heated  by  a  spirit- 
lamp. 

Composition  of  oonpowdtt.      Gunpowdcr   oonsists  very  nearly  of  2  molecules  of  saltpetre, 
X  molecule  of  sulphur,  and  3  of  charcoal.    Accordingly  100  parts  of  powder  contain — 

Saltpetre       74*84 

Sulphur ii-aj 

Charcoal  (No.  I.) 13*32 

The  above  figures  approximately  express  the  composition  of  the  best  kinds  of  sporting 
and  rifle-powder.  Ordinary  powders,  such  as  blasting-powder,  consist  of  nearly  eqiuJ 
molecules  of  nitrate  of  potassa  and  sulphur,  with  6  molecules  of  charcoal.  Accordingly 
100  parts  contain— 

Saltpetre        66*03 

Solphur 10*45 

Charcoal  (No.  n.) 23*52 


EXPLOSIVE  COMPOXrNDS.  153 

itodaiboiflM  ^n*  Bnnsen  and  Sobisehkoff  found  the  oomposiiion  of  a  sporting 

Otmintimtivowim.  mul  liflo-powder  to  be,  in  100  parts,  as  follows : — 

Saltpetre       78*99 

Sulphur. 9*84 

Carbon 7*69 

Ch«o«do««£rtfagof.^J^,    ;•    ;:    ;:    ;;    ;;    ;;    ."'^ 

^Ash traces 

The  reeidoe  of  this  powder  after  oombustion  was  found  to  eonsist  of— 

Sulphate  of  potassa      56*62 

Carbonate  of  potassa 27*02 

Hypoenlphite  of  potassa       7*57 

Sulphuret  of  potassium 1*06 

Hydrated  oxide  of  potassa  (caustic  potassa)     . .   '  1*26 

Sulphooyanide  of  potassium        0*86 

Saltpetre 5*19 

Carbon      0*97 

Carbonate  of  ammonia )  ^^^^^ 

Sulphur I*'^®^ 

100*55 

It  appears  from  this  analyslB  that  the  residue  left  after  ignition  of  the  gunpowder 
eonsists  essentially  of  sulphate  and  carbonate  of  potassa,  and  not,  as  has  been  formerly 
stated,  of  sulphuret  of  potassium.  The  composition  of  the  smoke  of  the  powder  was 
SBoertained  to  bo- 
Sulphate  of  potassa 65*29 

Carbonate  of  potassa 23*48 

Hyposulphite  of  potassa     . .     . .      4*90 

Sulphuret  of  potassium      ....        — 

Caustic  potassa     1*33 

Sulphocyanide  of  potassium     . .      0*55 

Saltpetre        3*48 

Carbon  (charcoal) 1*86 

Sesquicarbonate  of  ammonia    ..      0*11 

Sulphur — 


100*00 

Fnnu  these  figures  it  is  clear  that  the  smoke  of  gunpowder  consists  essentially  of  the 
lame  substances  as  the  residue  from  the  combustion,  the  only  difference  being  that  the 
Rilphur  and  nitrate  of  potassa  of  the  powder  have  been  more  completely  converted  into 
snlphate  of  potassa,  while  instead  of  the  sulphuret  of  potassium,  carbonate  of  ammonia 
makes  its  appearance.  100  parts  by  volume  of  the  gaseous  products  of  the  combustion 
vere  found  to  consist  of — 

Carbonic  add       52*67 

Nitrogen 41*12 

Oxide  of  carbon 3*88 

Hydrogen      1*21 

Sulphuretted  hydrogen       ..     ..  0*60 

Oxygen. 0*52 

Protoxide  of  nitrogen — 

lOO'OO 

The  solid  residnes  of  combustion  formed  during  the  generation  of  the  gases  were  found 
tobe— 

Sulphate  of  potassa 62-10 

Carbonate  of  potassa 18*58 

Hyposulphite  of  potassa    . .     . .  4*80 

Sulphuret  of  potassium      . .     . .  3*13 

Sulphocyanide  of  potassium     . .  0*45 

Nitrate  of  potassa       5*47 

Charcoal        1*07 

Sulphur 0*20 

Sesquicarbonate  of  ammonia    . .  4*20 

lOO'OO 


154 


CHEMICAL  TECHNOLOGY. 


The  deoompoBition  of  powder  by  its  ignition  nuiy  be  represented  by  the  following 
f ormnlsd : — 


'Beddne 
o'68o 


I  grm.  of  powder 


'Saltpetre 
Sulphur 

Charcoal 


0789' 

o'ogS 

O0076 

H  0*004 

.0  0*030, 


yields  after 
combustion 


rKaS04 
KaCO, 

EaSaOs 
KaS 
KCNS 
KNO3 
0 
S 
L  (NH4)a003 


0-994 


COa 

00 

H 

SH2 

0 


Orm. 
o'oggo 
0*2010 
0*0090 

0'0002 

o'ooiS 
0*00x4 


Grm. 
0*423 
0*126 
0*032 
0*02  X 
0*003 
0*037 
0*007 
o*oox 
0-028 

C.e. 

7940 

101*71 

749 

234 
1*16 

I -00 


19310 

According  to  the  recent  researches  of  Bfr.  Craig,  and  later  investigations  of  M.  Fedorow 
(1869),  the  products  of  the  combustion  of  powder  vary  according  to  the  pressure  this 
substance  is  subjected  to  while  being  ignited.  There  has  not  hiUierto  been  found  any 
really  effective  substitute  for  gunpowder ;  fulminates  and  mixtures  containing  ohloraie 
of  potassa  ignite  too  quickly  and  cause  the  bursting  of  the  gun,  while  gun-cotton  yields 
among  its  products  of  ignition  water  and  nitrous  acid,  which  act  destructiyely  on  the 
metal,  and  also  interfere  with  continued  firing. 

M«w  undg  of  BiMtiaf       Under  the  name  of  pyronone  there  is  sold  a  new  kind  of  blasting- 
Powdw.  powder,  consisting  of  nitrate  of  soda  52*5  parts,  sulphur  20,  and 

spent  tan  27*5  parts.  It  is,  of  course,  far  cheaper  than  ordinary  powder,  but  presumably 
not  very  useful  nor  active.  Captain  Wynands,  of  Belgium,  has  successfully  introduced 
a  substance,  to  which  he  has  given  the  name  saxifragine,  consisting  of  nitrate  of  baryta 
76,  charcoal  22,  and  nitrate  of  potassa  2  parts.  Schnitzels  (1864)  wood-gmipowder  consists 
of  granulated  wood  treated  with  a  mixture  of  nitric  and  sulphuric  acids,  and  next 
impregnated  with  a  solution  of  nitrate  of  potassa ;  this  matenal  is  manufactured  at 
Edgeworth  Lodge,  Hants.  M.  Bandisch  hais  invented  a  process  by  which  this  wood- 
gunpowder  may  be  compressed  into  a  solid  substance  exerting  great  power,  and  free 
from  danger  hj  transport.  Lithofracteur,  a  white  blasting-powder  used  in  Belgium, 
is  a  substauce  sunilar  to  gun-cotton.  The  haloxylin  of  MM.  Neumeyer  and  Fehleisen  is 
ft  mixture  of  charcoal,  nitre,  and  yeUow  prussiate  of  potassa.  Callou*s  blasting  povder . 
is  a  mixture  of  chlorate  of  potassa  and  orpiment.  Nitroleum  is,  in  fact,  nitro^yeerine, 
which,  with  dynamite  and  dualin,  will  be  spoken  of  presently.  Picrate  of  potassa  is  used 
in  France  and  in  England  for  filling  shells  intended  for  the  destruction  of  armour-plated 
ships,  and  for  the  manufacture  of  picrate  gunpowder. 

Testincibestnngtti  ^  order  to  determine  the  strength  or  projectile  force  of  gunpowder, 
ofoonpoirder.  and  which  for  equality  of  composition  is  dependent  on  the  me^anical 
treatment  the  powder  has  undergone,  the  following  apparatus  are  used: — Test  mortar, 
rod  testing  machine,  lever  testing  machine,  baUistie  pendulum,  and  chronosoope.  The 
first  of  tiiese  contrivances  is  a  piece  of  heavy  ordnance,  charged  with  92  grms.  of  powder, 
and  a  ball  weighing  29*4  kilos.,  the  mortar  being  placed  at  an  angle  of  45*.  The  bore  of 
ihe  mortar  is  191  millimetres  in  diameter  by  239  in  depth.  Powder  of  good  quality  should 
propel  the  ball  a  distance  of  225  metres,  and  frequently  the  ball  is  carried  a  distance  of 
250  to  260  metres.  The  rod  gonpowder  testing  apparatus  consists  of  a  mortar  plaoed 
vertically,  and  which,  when  charged  with  22  to  25  grms.  of  powder,  lifts  a  weight  of  8  Ibe^ 
made  to  move  between  toothed  rods ;  by  the  hei^t  this  weight  is  raised,  springs  attached 
to  the  weight  fastening  in  the  notches  of  the  rods  and  holding  it,  the  quali^  of  the  powder 
is  judged. 

White  oimpowder.  In  the  year  1849  M.  Augendre  brought  out  a  new  kind  of  gunpowder, 
whi<^,  imder  the  the  names  of  German  white  and  American  white  gonpowder,  has  been 
occasionally  employed.  This  powder  consists  of  yellow  prussiate  of  potassa,  chlorate  of 
potassa,  and  cane  sugar.  These  materials,  having  been  Uioroughly  mixed  in  a  dry  state, 
can  be  used  in  powder  or  in  grains,  igniting  in  contact  with  red-hot  and  flaming  substanees, 
but  not  by  friction  nor  percussion.     This  white  gunpowder  may  be  preferred  to  the 


EXPLOSIVE  COMPOUNDS.  155 

n&tikurj  powder  for  the  foUoimig  reasoiiB:— -Beiiig  oomposed  of  nnTarying  snbstanees, 
this  powder  can  always,  by  wei^^bing  out  the  ]^roper  quantities  of  eaoli  ingredient,  be 
obtained  of  uniform  strengui  and  qua^ty.  The  ingredients  are  not  hygroscopic  to  any 
extent,  and  are  not  acted  upon  by  exposure  to  the  air.  The  manufacture  requires  but  a 
?eiy  short  time,  the  projectile  force  is  far  greater,  and  the  powder  need  not  be  granulated. 
On  the  other  hand,  this  powder  acts,  during  its  ignition,  so  very  strongly  upon  iron  and 
iteel  that  it  can  only  be  used  in  bronze  ordnance,  and  in  the  filling  of  shells,  (fee.  It 
is  more  readily  fired  than  ordinary  gunpowder,  although  less  so  than  other  mixtures 
eontaimng  chlorate  of  potassa.  Fhially,  its  manufacture  is  very  expensiye.  According 
to  the  experiments  of  J.  J.  Pohl  (x86i)  on  this  subject,  the  following  is  the  best  recipe 
for  this  powder: — 

Tellow  prussiate  of  potassa    . .     . .    28  parts 

lioaf  sugar 23    „ 

Chlorate  of  potassa 49    „ 

This  mixture  is  approximatiyely  equal  to— 

X  molecule  of  Prussiate  of  potassa, 

1         „  Sugar, 

3  molecules  of  Chlorate  of  potassa ; 

eonesponding  in  100  parts  to  28*17  of  prussiate  of  potassa,  22*78  of  sugar,  and  49*05  of 
chlorate  of  potassa.  As  no  accurate  and  reliable  analyses  of  tne  products  of  the  com- 
bustion of  this  powder  have  been  made,  and  as  these  products  wiU  vary  with  respect  to 
the  conditions  under  which  the  ignition  takes  place,  whether  in  open  air  or  in  a  dose 
fesael,  it  can  be  merely  calculated,  that  assuming  complete  combustion  to  take  place, 
100  parts  of  this  powder  will  yield : — 

Nitrogen 1*865  P&rts 

Carbonic  oxide 11*192    „ 

Carbonic  acid 17*587    m 

Water 16*788    „ 

Total  gaseous  products     . .    47*442    „ 

The  solid  residue  will  consist  of — 

Cyanide  of  potassium     . .     17*385  psits 
Chloride  of  potassium    . .     29*840    „ 
Carburet  of  iron  (FeCa)  . .      5*333    i> 

Total  non-Yolatile  products      52*558    „ 

The  bulk  of  gaseous  matter  OTolTed  by  the  ignition  of  100  gnus,  of  this  powder,  taken 
at  o*^  and  760  m.m.  Bar.,  is  as  follows : — 

Nitrogen     . .     . .  1927*0  cubic  cenUms. 

Carbonic  oxide  . .  8942*9 

Carbonic  acid   . .  8942*9 

Aqueous  vapour  20867*9 


ft 

it 


n 


40680*4 

As  the  temperature  of  combustion  is  estimated  at  2604*5**  the  quantity  of  the  gases  is 
431 162  CO. 


p'JJjJWm**'  Under  the  name  of  fireworks  we  include  certain  mixtures  of 
oombnstible  substances  employed  as  signals,  as  destructive  agents  (for  instance, 
oongreve  rockets),  and  for  purposes  of  display. 

The  various  forms  are,  according  to  the  end  in  view,  so  contrived  as  to  bom 
off  either  rapidly  or  slowly,  and  veitii  more  or  less  emission  of  gaseous  matter,  heat, 
and  light  These  mixtures  are  mainly  distinguished  as  heat-produdng,  ignition 
eommnnicators  (technically  termed  a  match),  and  light-producing.  The  principle 
of  the  rational  manufacture  of  fireworks,  applying  the  word  in  its  extended  sense,  is 
that  neither  any  excess  of  the  combustible  nor  of  the  combustion  promoting  and 
supporting  agents  should  be  employed,  and  that  unavoidable  accessory  materials, 
viz.,  such  as  are  intended  only  to  keep  the  essential  ingredients  in  a  certain  required 
shape,  the  paper  casings,  &c.,  be  in  precisely  the  quantity  required*     The  best 


i 


i5fl  CHEMICAL  TECHNOLOGY. 

proportions  of  the  oombostible  and  combustion-supporting  snbstances  can  bo  readily 
ascertained  by  theoretical  calculations ;  for  instance,  it  will  be  evident  that  a 
mixture  of  2  equivalents  of  saltpetre  end  x  equivalent  of  sulphur  (i),  or  a  mixture 
of  2  equivalents  of  saltpetre  and  3  equivalents  of  sulphur  (2),  is  in  each  instance 
wrong ;  in  the  latter,  too  much  of  tiie  combustible  body  is  used ;  and  in  the  former 
case,  too  much  of  the  supporter  of  combustion  is  employed : — 

(i).  S  can  take  up  from  2KNO3  at  most  3O,  consequently  3O  remain  inactive. 

(2).  3S  and  2KNO3  yield  either  K2S  and  2SO3,  or  a  mixture  of  K2SO4,  E«S, 
and  SO3 ;  in  each  case  some  sulphur  remaining  unbumt. 
We  have  to  bear  in  mind,  however,  that  it  is  not  always  possible  to  elucidate 
theoretically  the  decomposition  of  firework  mixtures,  as  the  affinity  of  the  substances 
which  react  upon  each  other  is  not  well  known,  and  depends  on  accessory  con- 
ditions and  comparatively  unknown  influences.  It  will  require  a  more  advanced 
knowledge  of  the  products  of  the  decomposition  of  the  different  substances  and 
their  specific  heat  before  we  can  predict  with  some  degree  of  certainty  the  best 
mixtures.  As  regards  the  existing  mixtures,  they  are  the  result  of  a  lengthy  series 
of  experiments,  really  made  by  rule  of  thumb,  though  with  a  certain  correspondence 
with  the  best  composition  theory  can  give,  that  is  to  say,  many  of  these  mixtures 
have  been  somewhat  modified  and  improved  by  modem  science. 

The  mora  flommooiriiMd  These  mixtures  consist  mainly  of  saltpetre,  sulphur,  and  charcoal, 
nnwock  Miztam.  either  in  the  same  proportions  as  those  in  use  for  gmipowder,  or 
with  an  excess  of  sulphur  and  charcoal.  Borne  mixtures  contain  instead  of  saltpetre 
chlorate  of  potassa  and  other  salts,  not  always  essential  to  tiie  combustion,  but  intended 
either  to  intenaiiy  the  light  evolved  or  impart  to  it  a  distinctive  colour,  as  in  signals 
and  Bengal  lights. 

oonpowdcr  Is  used  in  fireworks  when  it  is  desired  "that  there  should  be  projectile  foroe. 
A  slower  combustion  of  the  powder  is  obtained  parUy  by  ^e  use  of  the  so-oaUed  fiour  of 
powder,  that  is  pulverised,  not  granulated  powder,  partiy  by  compressing  the  mixture.  If, 
however,  it  is  intended  to  produce  loud  reports,  granulated  powder  is  used. 

saitpacre  and  Svipinur  lUxkinB.  This  consists  of  2  moleoules  (75  parts  by  weight)  of  saltpetre, 
and  I  molecule  (25  parts  by  weight)  of  sulphur,  and  is  used  as  the  chief  constituent  of 
such  firework  mixtures  as  are  intended  to  bxum  off  slowly  and  evolve  a  strong  light. 
However,  this  mixture  is  not  used  by  itself  for  two  reasons,  vis.,  it  does  not  derelope 
a  sufficient  degree  of  heat  to  support  its  continued  combustion,  and  does  not  possess  a 
sufficient  projectile  force,  being  capable  of  producing  in  the  best  possible  condition  of 
complete  ignition  only  z  molecule  of  sulphurous  add — 

2EN03-l-S-E^804-f  BOa+N ; 
that  is  to  say,  i  part  by  bulk  of  this  mixture  omy  yields  7*28  volumes  of  gas.    For  these 
reasons  the  saltpetre-sulphur  mixture  is  employed  with  charcoal  or  floury  gunpowder. 

ony-ooioiizMi  Mixton.  Suoh  a  mixture,  sanctioned  bv  long  use,  is  that  known  aa  grey- 
coloured  mixture,  oorndsting  of  93*46  per  cent  01  saltpetre-sulphur,  and  6*54  of  floury 
gunpowder.  This  mixture  is  the  chief  constituent  of  other  compounds  intended  to  bum 
dowly,  emitting  at  the  same  time  a  brilliant  light,  owing  to  the  fact  that  the  sulphate  of 
potassa  formed  by  the  combustion  acts  similarly  to  a  solid  brought  to  an  incandescent 
state.  All  mixtures  intended  to  emit  light,  including  coloured  li^ts,  are  prepared  upon 
the  same  principle,  that  the  salt  which  is  to  give  colour  shall  be  non-volatile  at  the  tem- 
perature of  combustion. 

Ghkntoof  PoUMMiuxtani.  This  Salt  EOIO3,  when  in  presence  of  combustible  sub- 
stances, gives  off  its  oxygen  to  the  latter  more  readily,  rapidly,  and  completely  than  salt- 
petre ;  accordingly  this  salt  is  used  in  all  mixtures  in  which  it  is  desired  to  oombine  rapid 
Ignition  with  combxurtion.  Fonnerly  a  mixture  of  80  parts  by  wdght  of  chlorate  of 
potassa  and  20  parts  of  sulphur,  was  added  to  intensify  snd  quicken  the  combus- 
tion of  mixtures  consisting  of  more  slowly  burning  salts.    A  mixture  of  sulphur,  ohar- 

FrisUon  MixtsTM.        oosl,   and   chlorate   of    potassa   constitutes   an   active   peroussion 

Pweanion  Powdm.  powder.  A  mixture  of  equal  parts  by  weight  of  black  sulphuret  of 
antimony  and  chlorate  of  potassa  is  used  for  the  purpose  of  disoharging  or<uianoe  by 
means  of  a  percussion  tube  placed  into  the  touchholo  of  the  gun.  Sir  WUliam  Armstrong 
uses  for  this  purpose  a  mixture  of  amorphous  phoBphcrus  and  chlorate  of  potassa. 


EXPLOSIVE  COMPOUNDS,  157 

mxtanforznitingttw  Thlfl  mixtnre  consists  either  of  chlorate  of  potassa  and  black  snl- 
amuf«  of  secdte-pma.  phnret  of  antimony,  or  a  componnd  containing  fulminate  of  mercury. 
The  following  is  a  good  preparation : — 16  parts  of  chlorate  of  potassa,  8  parts  of  black 
mlphnret  of  antimony,  4  of  floor  of  snlphur,  i  of  charcoal  powder,  are  moistened  with 
either  gam  or  sugar  water,  and  about  5  drops  of  nitric  acid  added.  A  small  quantity, 
teehnicaUy  known  as  the  piUf  is  placed  in  the  cartridge,  and  ignited  by  the  friction  pro- 
duced by  the  sudden  passage  of  the  steel  needle  through  it.  In  this  country  either  the 
ftbove  or  a  mixture  of  amorphous  phosphorus  and  chlorate  of  potassa  is  used.  Leaving 
the  fulmdnates  of  silyer  and  mercury  out  of  the  question,  the  explosive  bodies  and 
their  applicability  to  warlike  purposes  and  war  pyrotechny  have  not  been  sufficiently 
investigated.  Kitromannite  or  fulminating  mannite,  the  picrates  of  the  alkalies 
and  nitroglycerine,  of  which  we  shall  presently  treat  more  fuUy,  especially  deserve  notice. 
If.  Deesignolles,  who  suggests  that  instead  of  saltpetre,  picrate  of  potassa  should  be  used 
in  the  manufacture  of  gunpowder,  states  that  quite  different  products  are  formed  by  the 
ignition  of  picrate  of  potassa,  when  effected  in  the  open  air  (a),  or  under  pressure  (/3)  :— 

a.  206HaK(NOa)30=KaC03+5C+2N+NO+NOa+400a+CHN. 

\    ■      ■  „        ,.--/ 

Picrate  of  potassa. 
p.  2C6HaK(N02)30=KaC03+6C+3N+5COa+2H2+0. 

V , f 

Herate  of  potassa. 
Fulminating  aniline,  chromate  of  diazobenjBol,  obtained  by  the  action  of  nitrons  acid 
upon  aniline,  and  the  precipitation  of  the  product  by  the  aid  of  a  hydrochloric  acid  solu- 
tion of  bichromate  of  potassa,  is,  according  to  MM.  Garo  and  Qriess,  an  efficient  substitute 
for  fulminating  mercury. 

Baat-pRMbiciog  MixtoTM.  Theso  couslst  cMefly  of  floury  gunpowder  and  grey  mixtnre, 
to  which  are  added  those  organic  substances,  as  pitch,  resin,  tar,  igniting  readily,  but 
ecmsumed  more  slowly  than  any  firework.  The  heat  generated  by  the  combustion  of 
fireworks  is  much  higher  than  is  required  to  ignite  wood,  but  not  of  sufficient  duration  to 
cause  the  thorough  burning  of  the  wood,  hence  the  addition  of  tar,  Ae. 

ctkmnAtinm,  llie  salts  employed  to  produce  coloured  flames  are — ^the  nitrates  of 
baryta,  strontia,  and  soda,  and  the  ammoniacal  sulphate  of  copper.  The  so-called  cold 
fused  mixture,  composed  of  grey  mixture,  floury  gunpowder,  and  sulphuret  of  antimony, 
moiBtened  with  brandy  and  then  mixed,  produces  a  white  flame.  The  mixtures  for 
coloured  flres  used  in  artillery  laboratories  are  the  xmdermentioned,  calculated  for  100 
parts  of  each  mixture : — 

X.  Chlorate  of  potassa    .  • 

2.  Sulphur 

3.  Charcoal 

4.  Nitrate  of  baryta 

5.  Nitrate  of  strontia      ..         ..  —  457  —  —  — 

6.  Nitrate  of  soda  ....  —  —  9*8  —  — 

7.  Ammoniacal  sulphate  of  coppe^         —  —  —         27*4  — 

8.  Saltpetre  —  —  62*8  —  60 

9.  Black  sulphuret  of  antimony . .  —  57  —  —  5 
10.  Floury  gunpowder      ....          —               —              —           —               15 

It  is  hardly  necessary  to  mention  that  great  care  is  required  in  mixing  these  mate- 
rials,  and  that  each  ingredient  ought  to  be  pulverised  separately. 

According  to  M.  IHiden  a  beautiful  white  flame  edged  with  blue  is  obtained  by 
the  ignition  of  the  following  mixture  : — 20  parts  of  saltpetre,  5  of  sulphur,  4  of  sulphuret 
of  cadmium,  and  i  part  of  diarcoal.  Chloride  of  thallium  with  other  ingredients  yields  a 
beautiful  green  flame.  Magnesium  was  used  during  the  Abyssinian  war  in  various  ways 
when  a  brilliant  light  was  required.  The  chlorates  of  the  alkaline  earth  bases  and  the 
ehbrate  of  soda  would  be  preferable,  were  it  not  for  the  expense,  and  for  the  facts 
that  these  salts  are  rather  hygroscopic  and  liable  to  spontaneous  combustion.  The  car- 
bonates of  baryta  and  of  strontia  are  sometimes  used  instead  of  the  nitrate.  According 
to  MM.  Dessignolles  and  Oastelhaz,  most  hnlliant  coloured  flames  are  obtained  with  picrate 
of  ammonia  in  the  following  proportions : — 

Tellow  I  ?^*^'**®  ®'  ammonia        . .     50 


a. 

b. 

c. 

d. 

e. 

Green. 

Bed. 

Yellow. 

Blue. 

"White. 

327 

297 

— 

54'5 

— 

9-8 

17*2 

236 

20 

5-2 

17 

3-8 

x8'x 

— 

523 

— 

— 

— 

— 

Green 
Bed 


Picrate  of  protoxide  of  iron  50 

Picrate  of  ammonia  . .  48 

Nitrate  of  baryta   . .        •  •  52 

Picrate  of  ammonia  . .  54 

Nitrate  of  strontia . .        . .  46 


158  CHEMICAL  TECHNOLOGY. 

b.  Nitroglycerine. 

Nitrogiyeaiine.  TluB  substance,  aJso  known  as  fulminating  oil»  nitrolemn,  trinitrine, 
glyceiyl-nitrate,  glonoine,  was  discovered  in  1847  by  Dr.  A.  Sobrero,  while  a 
student  in  the  laboratory  of  Professor  Pelouze,  at  Paris.  Since  the  year  1862,  M.  Alfred 
Nobel,  a  Swede,  has  manufactured  this  liquid  on  the  large  scale.    The  formula  of 

nitroglycerine  is  C3H5N30g  or  /^J^^  r  ^3 »    consequently  it  consists  of  glycerine, 

H  I  ^3>  ^  which  3  atoms  of  H  have  been  replaced  by  3  atoms  of  NO^.     100  parta 

of  nitroglycerine  yield  on  combustion — 

YV  axer        •••         •««         ••• 

Carbonic  acid       

Oxygen      ...        ...        ... 

Nitrogen 

loo'o  parts. 

As  the  sp.  gr.  of  nitroglycerine  is  1*6,  i  part  by  bulk  will  yield  on  combustion — 

Aqueous  vapour    554  volumes. 

Carbonic  acid 469        ,, 

Oxygen    ,-    39        ** 

Nitrogen •    236        1, 

1298 

According  to  experiments  made  in  Belgium,  the  combustion  of.  nitroglycerine 
does  not  yield  free  oxygen,  but  a  large  quantity  of  protoxide  of  nitrogen ;  accordingly, 
the  following  equation  will  give  some  idea  of  the  mode  of  explosion : — 

Carbonic  acid,  6OO3. 


20  ] 

parts. 

58 

»» 

3*5 

>i 

185 

It 

2  molecules  of 
Nitroglycerine,  C3H5N3O9 


Water,  sHaO. 

Protoxide  of  nitrogen,  NaO. 

Nitrogen,  4N. 


M.  Nobel  states  that  the  heat  set  free  by  explosion  causes  the  gases  to  expand  to 
eight  times  their  bulk ;  accordingly,  i  volume  of  nitroglycerine  will  yield  10*384 
volimies  of  gas,  while  i  part  by  bulk  of  powder  only  yields  800  volumes  of  gas;  the 
explosive  force  of  nitroglycerine  is,  therefore,  to  that  of  powder — 

By  volume  as  13  :  i, 
By  weight  as   8:1. 

In  order  to  prepare  nitroglycerine,  very  strong  nitric  add,  density  49°  to  50**  B. 
s=  1*476  to  1*49  sp.  gr.,  is  mixed  with  twice  its  weight  of  concentrated  sulphniic 
acid.  3300  gnus,  of  this  mixture,  thoroughly  cooled,  are  poured  either  into  a  glass  flask 
or  into  a  glazed  earthenware  jar,  placed  in  a  pan  of  cold  water,  and  there  is  next 
gradually  added  500  gnns.  of  concentrated  and  purified  glycerine,  having  a  density 
at  least  of  30''  to  31''  B.  =  sp.  gr.  1-246  to  1*256,  care  been  taken  to  stir  constantly. 
According  to  Dr.  E.  Kopp*s  recipe  (1868)  the  acid  mixture  should  consist  of  3  parts 
of  sulphuric  add  at  66**  B.  =  1767  sp.  gr.,  and  i  part  of  fuming  nitric  add.  To 
350  grms.  of  glycerine  2800  grms.  of  the  add  mixture  are  added ;  and  in  performing 
this  operation  care  should  be  taken  to  avoid  any  perceptible  heating  for  fear  of 
converting  by  a  violent  reaction  the  glycerine  into  oxalic  add.  The  mixture  is  now 
left  to  stand  for  five  or  ten  nunutes,  and  afterwards  poured  into  five  or  six  times  its  bulk 


EXPLOSIVE  COMPOUNDS.  159 

of  very  cold  water,  to  which  a  rotatory  motion  has  been  imparted.  The  newly- 
formed  nitroglycerine  sinks  to  the  bottom  of  the  vess^  as  a  heavy  oUy  Uquid,  which 
ifi  washed  by  decantation ;  bat  if  not  intended  for  transport — and  experience  has 
proyed  the  transport  of  nitroglycerine  to  be  highly  dangerous — ^the  washing  may  be 
dispensed  with,  as  neither  any  adhering  acid  nor  water  impairs  the  explosive 
properties.  Nitroglycerine  is  now  generally  made  on  the  spot  in  America  and  else- 
where by  those  whom  experience  in  mining,  quarrying,  and  engineering  matters  has 
taught  the  real  vcdue  of  this  very  powerful  agent. 

Nitroglycerine  is  an  oily  fluid  of  a  yellow  or  brown  colour,  heavier  thsm  and 
insoluble  in  water,  soluble  in  alcohol,  ether,  and  other  fluids;  when  exposed  to 
continuous  cold,  not  of  great  intensity,  it  becomes  solidified,  forming  long  needle- 
shaped  crystals.  The  best  means  of  exploding  nitroglycerine  is  a  well-directed 
blow,  neither  a  spark  nor  a  lighted  body  will  cause  the  ignition,  which  even  with  a 
thin  layer  takes  place  with  difficulty,  only  part  being  consumed.  A  glass  bottle  filled  with 
nitroglycerine  may  be  smashed  to  pieces  without  causing  the  contents  to  explode.  Nitro- 
glycerine may  even  be  gently  heated  and  volatilised  without  decomposition  or  com- 
bustion, provided  violent  boiling  is  carefully  prevented.  When  a  drop  of  nitroglycerine 
18  caused  to  fidl  on  a  moderately  hot  piece  of  cast-iron  the  liquid  is  quietly  volatilised ; 
if  the  iron  is  red-hot  the  liquid  bums  off  instantaneously,  just  as  a  grain  of  powder 
would  do  under  the  same  conditions ;  if,  however,  the  iron  is  at  Uiat  heat  which 
will  cause  the  immediate  boiling  of  the  nitroglycerine,  it  explodes  with  great  force. 
Nitroglycerine,  especially  if  sour  and  impure,  is  liable  to  spontaneous  decomposition, 
which,  accompanied  by  the  formation  of  gas  and  of  oxalic  acid,  may  have  been  the 
proximate  cause  of  some  of  the  dreadful  explosions  of  this  substance,  it  being 
surmised  that  the  pressure  exerted  by  the  generated  gases  upon  the  fluid  in 
hennetically  closed  vessels  had  something  to  do  with  the  occurrences.  On  this 
account  M.  K.  list  advises  that  vessels  containing  nitroglycerine  should  be  only 
loosely  stoppered,  or  if  being  transported  provided  with  safety-valves.  Nobel 
secnrea  nitroglycerine  from  explosion  by  dissolving  it  in  pure  wood-spirit,  from 
which  it  may  be  again  separated  by  tiie  addition  of  a  large  quantity  of  water.  Mr. 
Seeley  on  this  score  observes  that: — i.  The  wood-spirit  is  expensive,  and  lost  in  the 
large  quantity  of  water  required  for  precipitating  the  nitroglycerine;  2.  Wood-spirit, 
being  volatile,  may  evaporate,  and  leave  the  nitroglycerine  unprotected ;  3.  There 
18  a  change  of  chemical  action  between  these  bodies ;  4.  The  vapour  of  wood-spirit 
is  very  volatile,  and  forms  with  air  an  explosive  mixture.  Many  suggestions  have  been 
made  as  to  rendering  nitroglycerine  safe  to  warehouse ;  among  them  may  be  noted 
the  miung  with  pulverised  glass  in  a  manner  similar  to  (bale's  process  for  gun- 
powder. Wurtz  recommends  the  mixture  of  nitroglycerine  with  equally  dense 
solutions  of  eitiier  of  the  nitrates  of  zinc,  lime,  or  magnesia,  so  as  to  form  an 
emulsion,  the  nitroglycerine  being  recovered  simply  by  the  addition  of  water.  The 
taste  of  nitroglycerine  is  sweet,  but  at  the  same  time  burning  and  aromatic;  it  is  a 
violent  poison  even  in  small  doses,  and  its  vapour  is  of  course  equally  virulent,  hence 
great  care  is  required  in  working  with  this  substance  in  localities  where,  as  in  mines 
and  pits,  the  supply  of  fresh  air  is  limited.  Instead  of  manufiEtcturing  nitroglycerine 
in  works  specially  arranged  for  that  purpose,  and  transporting  this  dangerous 
compound,  it  is  better,  as  advised  by  and  executed  under  the  direction  of  Dr.  E. 
Kopp,  at  the  Saveme  quarries,  to  have  the  quantity  required  for  daily  use  prepared 
on  the  spot  by  intelligent  workmen.    Notwithstanding  the  very  serious  accidents 


i6o  CHEMICAL   TECHNOLOGY, 

which  have  been  caused  by  the  explosions  of  nitroglycerine  in  this  conntry  as  well 
as  abroad,  and  the  consequent  prohibition  of  its  use,  there  is  no  reason  iiiiy  this 
powerful  agent  should  not  be  employed  according  to  Kopp's  suggestion.  Instead  of 
the  acid  mixture  used  ia  the  preparation  of  nitroglycerine,  M.  Nobel  suggests  the 
following: — In  3!  parts  of  strong  sulphuric  acid  of  183  sp.  gr.  is  dissolved  i  part 
of  saltpetre,  and  the  fluid  cooled  down ;  the  result  is  the  separation  of  a  salt  consisting 
of  I  molecule  of  potassa,  4  molecules  of  sulphuric  acid,  and  6  molecules  of  water, 
and  which  at  32*"  F.  is  altogether  eliminated  &om  the  fluid,  leaving  an  acid  which, 
by  the  gradual  addition  of  glycerine,  is  converted  into  glonoine,  afterwards  separated 
by  water,  as  already  described. 

Nobel's  Dyxuunite.  Under  the  name  of  dynamite,  Nobel,  in  1867,  brought  out  a  new 
explosive  compound,  consisting  of  75  parts  of  nitroglycerine  absorbed  by  25  parts 
of  any  porous  inert  matter,  as  finely  divided  charcoal,  silica.  As  evidenced  by  the 
experiments  of  Bolley  and  Eundt,  dynamite  has  the  advantage  over  nitroglycerine 
of  not  being  exploded  even  by  the  most  violent  percussion,  therefore  requiring  a 
peculiarly  arranged  cartridge.  The  explosion  is  attended  with  such  force  that 
large  blocks  of  ice  are  shattered  to  atoms.  Dynamite  bums  off  quietly  in  open 
air,  or  even  when  loosely  packed,  the  combustion  being  accompanied  by  an  evolution 
of  some  nitrous  acid;  but  when  dynamite  is  exploded  there  are  generated  only 
carbonic  acid,  nitrogen,  and  aqueous  vapour,  no  smoke  being  formed,  and  only  a 
white  ash  left.  Dynamite  is  not  affected  by  damp,  and  undoubtedly  offers  great 
advantages  as  regards  its  use  in  mining,  quarrying,  and  similar  operations,  for 
although  the  price  exceeds  four  times  that  of  powder,  dynamite  performs  eight  times 
as  much  work  with  less  danger,  and  less  labour  in  boring  blast  holes.  The  dynamite 
is  placed  in  cartridges  of  thick  paper,  and  ignited  by  means  of  a  fiisee,  which  passes 
through  the  sand  serving  the  purpose  of  a  wad.  Dynamite  can  be  transported 
without  danger  of  explosion.  Dittmar's  dualin  is  a  mixture  of  nitroglycerine  with 
sawdust  or  wood>pulp  as  used  in  paper  mills,  both  previously  treated  with  nitric  and 
sulphuric  acids. 

c.  Oun-Cotton, 

onn-ootton.  This  substaucc,  also  known  as  pyroxylin  and  falmicotton,  was  discovered 
in  1846,  simultaneously  by  the  late  Professor  Schonbein,  at  Basle,  and  by  Dr.  R 
Bottger,  at  Frankfort-on-Main.  The  mode  of  preparing  this  substance  is  as  follows: — 
Equal  parts  of  strong  concentrated  sulphuric  acid,  sp.  gr.= 1*84,  and  fuming  nitric  acid 
are  poured  into  a  porcelain  basin ;  as  much  cotton- wool  is  steeped  in  the  fluid  as  the 
acid  is  capable  of  thoroughly  moistening,  and  the  vessel  covered  with  a  glass  plate, 
and  left  for  a  few  minutes.  The  cotton-wool  is  then  removed  from  the  acid, 
immediately  transferred  to  a  vessel  containing  a  large  quantity  of  water,  and  washed 
with  care,  the  water  being  renewed  until  no  more  acid  adheres  to  the  gun-cotton, 
which  is  next  dried  in  a  current  of  warm  air,  and  finally  combed  to  remove  all  the 
lumps.  The  cotton  should  not  be  left  too  long  in  the  acid  as  it  might  become 
entirely  dissolved.  According  to  experiments  instituted  at  Paris  in  one  of  the 
powder  mills — for  in  France  no  one  is  allowed  to  manufacture  powder  or  gqn-cotton 
except  the  Government — ^the  following  are  the  conditions  under  which  the  best  results 
are  obtained: — i.  Equal  parts  of  sulphuric  and  nitric  acids  and  well  cleansed 
cotton.  2.  Time  of  immersion  in  add  mixture  from  10  to  15  minutes.  3.  The  same 
acid  may  be  used  once  again,  but  then  the  time  of  immersion  of  the  cotton 


GUN  COTTON. 


z6i 


should  be  longer.  4.  The  gun-cotton  having  been  thoroughly  washed  should  be  dried 

slowlj  at  a  gentle  heat.    5.  Impregnating  with  nitre  increases  the  strength  of  the 

gan-cotton. 

propartiM  of  onn-Gotton.      In   its   ontward   appearance  gun-eotton  does  not  differ  from 
ordinary  cotton,  neither  is  any  difference  perceptible  by  microscopic  investigation.    It  is 
insolnble  in  water,  alcohol,  and  acetic  acid,  difficultly  soluble  in  pure  ether,  but  readily 
soluble  in  ether  which  contains  alcohol,  and  in  acetic  ether.    Gun-cotton  is  liable  to  spon- 
taneous decomposition,  which  may  even  induce  its  spontaneous  combustion ;  this  decom- 
poBition  is  attended  with  the  evolution  of  aqueous  vapour  and  of  nitrous  acid  fumes,  the 
lemaining  substance  containing  formic  acid.    As  regards  the  temperature  at  which  gun- 
eotton  ignites  statements  differ;  it  has  in  some  instances  been  dried  at  90**  to  100^ 
vitbont  any  dangerous  consequences,  while  it  has  been  found  to  ignite  at  43**.    Instances 
are  on  record  of  serious  explosions  of  gun-cotton  having  taken  place  under  conditions 
which  leave  no  doubt  that  the  greatest  care  is  required  in  handling  and  warehousing 
this  substance ;  for  instance,  a  small  magazine,  fiUed  with  gun-cotton,  situated  in  the 
Bois  de  Yincennes,  Paris,  was  exploded  by  the  sun's  rays ;  and  at  Faversham  the  Le  Bouchet 
drying  rooms,  which  could  not  possibly  be  heated  above  45°  to  50*,  exploded  with  great 
Tiolence.    Gun-cotton  explodes  by  percussion,  leaving  no  residue  after  its  ignition.  Good 
Kon-ootton  may  be  burned  off  when  placed  on  dry  gunpowder  without  igniting  the  latter. 
It  is  very  hygroscopic,  but  may  be  kept  for  a  length  of  time  under  water  without  affecting 
its  explosive  properties. 

According  to  the  best  chemical  analysis,  gun-cotton  is  trinitro-cellulose, 

C6H7(NOa)305, 

consequently  it  is  cotton  considered  in  a  pure  state  as  cellulose,  C6HX0O5,  3  atoms  of 
the  hydrogen  of  which  have  been  replaced  by  3  atoms  of  hyponitric  acid.  100  parts 
of  gan-cotton  contain — 

Carbon       24*24 

Hydrogen 2*36 

Oxygen      5926 

Nitrogen     ...     • '4' '4 


The  conversion 
fonnnla: — 


of  cotton  into  gan-cotton  may 

C6Hxo05-f3HN03=C6H7(NOa)305-f3HaO ; 

— '  ^ " 


lOOOO 

therefore  be  expressed  by  the  following 


Cotton. 


Gun-cotton. 


the  sulphuric  add  being  employed  only  for  the  purpose  of  absorbing  water. 
Assuming  that  the  cellulose  is  entirely  converted  into  trinito-cellulose,  100  parts  of 
cotton  ought  to  yield  185  parts  of  gun-cotton,  and  when  the  conversion  forms  binitro- 
cellulose,  100  parts  of  cotton  ought  to  yield  155  parts  of  gun-cotton.  The  under- 
mentioned are  the  results  of  direct  investigation.     For  100  parts  of  cotton — 

Pelonze  (in  ten  experiments,  1849)  found  168  to  170  parts  of  gan-cotton. 

Schmidt  and  Hecker  (1848)  „  169 

Van  Kerckhoff  and  Renter  (1849)  „  1762 

W.  Cram  (1850)  ,.  178 

Redtenbacher,  Schrotter,  and  Schneider  (1864)     „  178 

V.  Lenk  (1862)  »  i55 

Blondeau  (1865)  »  16525 

By  the  explosion  of  gan-cotton  in  vacuo,  carbonic  oxide,  aqueous  vapour,  and 
nitrogen  are  evolved.  The  same  products,  with  the  addition  of  nitrous  acid  and 
cyanogen,  are  generated  by  the  explosion  of  gan-cotton  in  closed  vessels,    i  grm.  of 

M 


>••  •■•  ••< 


162  CHEMICAL  TECHNOLOGY. 

gun-cotton  yields,  according  to  Schmidt,  588  c.c.  gases,  these  gases  consisting  in 
100  parts  by  volume  of — 

Carbonic  oxide      30 

Carbonic  acid ... 

Marsh  gas 

Deutoxide  of  nitrogen  . . . 

Nitrogen 

Aqueous  vapour    


I  •         •  •  • 


20 
...     10 

9 


I  •         •  •  • 


I  •         *•  • 


•  •  •  94 


>•  •  •  • 


8 
23 


100 

I  part  by  weight  of  gun-cotton  is  equal  in  projectile  power  to  4*5  to  5  parts  of  gun- 
powder. 

^^'^^StS^^i^*^*^      Gun-cotton  has  not  yet  been  adopted  in  practice  as  a  good 

substitute  for  gunpowder ;  its  large  bulk,  coupled  with  the  fact  that  the  explosion  is 

attended  with  the  evolution  of  much  water  and  nitrous  acid,  render  it  inconvenient 

as  a  substitute  for  powder. 

ouMroMaof  oon-ooHon.  Gun-cctton  is  advantageously  employed  in  blasting,  and  has  been 
used  as  a  Bubetitute  for  fulminating  mercury  in  gun-caps  when  mixed  with  ohloraie  of 
potassa.  The  experiments  of  Professor  Abel,  of  Woolwich,  have  led  to  great  improve- 
ments in  the  manufacture  of  gon-cotton,  carried  into  practice  l^  Messrs.  Prentice,  of 
Stowmarket,  and  consisting  chiefly  in  mechanical  operations.  The  cotton,  either  bj 
spinning  and  weaving,  by  pulping,  or  the  aid  of  suitable  solvents,  is  brought  into  a  con- 
dition in  which  it  has  been  found  an  excellent  and  cleanly  substitute  for  gunpowder, 
having  the  advantages  of  not  giving  off  smoke,  exploding  with  less  noise,  and  not  fouling 
the  guns.  The  detailed  description  of  the  method  of  these  operations  is  not  necessary 
here.  Gun-cotton  in  many  cases  may  serve  the  purpose  of  asbestos  for  filtering  strong 
acids  and  other  concentrated  fluids  which  cannot  be  filtered  through  paper. 

couoiUon.  Maynard  employs  a  solution  of  gun-cottpn  in  ether  as  a  kind  of  glue  or 
varnish,  and  gives  it  the  name  of  collodion.  This  solution  has  the  appearance  of  a 
syrup,  and  a  thin  film  poured  on  the  skin,  leaves,  by  the  evaporation  of  the  ether,  a 
strongly  adhesive  compact  layer ;  hence  collodion  is  applied  in  surgery,  photography, 
and  as  a  waterproof  coating  instead  of  varnish,  especially  to  protect  the  compositioQ 
of  ludfer-matches  from  the  effects  of  damp.  The  film  of  pyroxylin,  deposited  after 
the  evaporation  of  ether,  is  insoluble  in  water  and  alcohol,  becomes  highly  negatively 
electric  when  rubbed  with  the  dry  hand,  and  may  be  obtained  so  thin  as  to  exhibit 
the  colours  of  the  Newton  rings.  Legray  prepares  in  the  following  manner  a  gun- 
cotton  quite  soluble  in  ether : — 80  grms.  of  dried  and  pulverised  nitrate  of  potassa 
are  mixed  with  120  grms.  of  concentrated  sulphuric  acid,  and  in  the  pulpy  acid  mass 
are  thoroughly  immersed  by  the  aid  of  a  glass  rod  or  porcehdn  spatula  4  grms.  of 
cotton,  which  is  stirred  about  for  a  few  minutes ;  next  the  vessel  containing  acid  and 
cotton  is  placed  in  a  large  quantity  of  water,  and  the  converted  cotton  washed  until 
all  the  acid  is  eliminated,  when  it  is  dried.  Soluble  cotton  may  be  made  with 
nitrate  of  soda,  17  parts;  sulphuric  acid,  sp.  gr.  =  180,  33  parts;  cotton,  I  part 
The  converted  cotton  is  soluble  in  acetic  ether,  acetate  of  oxide  of  methyl,  wood- 
spirit,  and  aceton ;  the  usual  solvent  is  a  mixture  of  18  parts  of  ether  and  3  parts  of 
alcohol. 


COMMON  SALT.  163 

Common  Salt. 

oeesR«D««.      Common  salt,  or  chloride  of  sodium,  consists  of — 

Chlorine,  CI       355  60*41 

Sodium,  Na       230  39'59 


585  loooo 

and  is  found  on  our  globe  in  the  solid,  as  rock-salt,  as  well  as  dissolved  in  sea- water 
is  enormously  large  quantities.  It  occurs  as  rock-salt  in  extensive  layers  alternating 
with  those  of  clay  and  gypsum  at  an  average  depth  of  100  metres.  The  following  are 
a  few  of  the  localities  where  rock-salt  is  met  with  in  the  tertiary  formation : — 
Wieliczka,  Poland ;  the  northern  slopes  of  the  Carpathian  mountains,  and  in  several 
districts  of  Hungary;  in  the  chalk  formation  of  Cardona,  Spain;  in  the  Eastern 
Alps,  Bavaria,  Salzburg,  Styria,  and  the  Tyrol.  Among  the  trias  formation  are  the 
salt  deposits  of  the  Teutoburg-wood,  Germany,  and  a  great  many  others,  among  them 
the  celebrated  Stassfurt  deposits.  In  England  rock-salt  is  found  in  Cheshire,  this 
county  being  also  plentifully  supplied  with  saline  springs,  the  water  of  which  yields 
on  evaporation  an  abundance  of  salt.  Petroleum  wells  are  found  with  salt  in  many 
parts  of  Asiatic  Russia,  in  Syria,  Persia,  and  the  slopes  of  the  Himalaya.  Salt 
occurs  plentifully  in  several  districts  of  Africa,  America,  and  other  parts  of  the 
world,  and  mixed  with  clay  and  marl,  forming  salt-clay.  Salt  occurs  secondarily  by 
having  been  dissolved,  at  a  depth  varying  in  Germany  from  91  to  555  metres,  by 
water,  which  carries  it  again  to  the  surface,  there  forming  salt  springs  and  salt  lakes, 
from  which  the  salt  is  obtained  by  evaporation.  Among  the  salt  lakes  may  be 
noticed  the  lake  near  Eisleben,  Germany,  the  Elton  Lake  near  the  Wolga,  Russia,  the 
Dead  Sea,  and  the  Salt  Lake  of  Utah,  United  States. 

There  can  be  no  doubt  that  the  common  salt  met  with  in  salt  springs  owes  its 
origin  to  the  solvent  action  of  water  upon  rock-salt,  and  as  rock-salt  is  largely  met 
with  in  sedimentary  geological  formations,  the  prevalence  of  this  formation  in  Ger- 

m 

many  has  there  given  rise  to  a  large  number  of  salt  springs.  Common  salt  is  also 
found  in  sea- water,  and  if  obtained  by  its  evaporation  is  often  termed  sea-salt ;  or  if 
deposited,  as  is  the  case  in  the  Polar  regions,  by  intense  cold  on  the  surface  of  ice- 
fields, it  is  known  as  rassol.  Common  salt  is  largely  obtained  as  a  by-product  of 
some  chemical  operations,  as  in  the  conversion  of  sodium-nitrate  into  potassium- 
nitrate  by  the  aid  of  chloride  of  potassium. 

''•^ffrSSaSSf.te?'^"  The  constituent  salts  of  sea- water  do  not  differ  in  any  part 
of  the  world ;  even  the  difference  in  quantity  is  very  small,  and  is  generally  due  to 
local  causes,  as  the  dilution  of  the  sea- water  by  river- water,  melting  icebergs,  &c. 
The  sp.  gr.  of  sea- water  at  17°,  varies  from  1*0269  ^  10289,  the  sp.  gr.  of  the  water 
of  the  Red  Sea  being  as  high  as  1*0306.    One  hundred  parts  of  sea- water  contain — 


Chloride  of  sodium  . . . 
Bromide  of  sodium  ... 
Sulphate  of  potassa    . . . 

Sulphate  of  lime 

Sulphate  of  magnesia . . . 
Chloride  of  magnesium 
Chloride  of  potassium... 


Pacific 

Atlantic 

German 

Bed 

Ocean. 

Ocean 

Ocean. 

Sea. 

25877 

27558 

25513 

3030 

00401 

0*0326 

00373 

0064 

01359 

01715 

01529 

0*295 

01622 

02046 

01622 

0-179 

01 104 

00614 

0*0706 

0274 

04345 

0*3260 

04641 

0404 

— ^ 

— 

0288 

34708  35519  ZAZH  4534 

M   2 


i64  CHEMICAL  TECHNOLOGY. 

The  composition  of  the  salt  contained  in  the  water  of  the  several  seas  is  shown  bj 
the  following  table : —  ^ 

i     i 


i  S'ss    i-sj    O'SS    ^-s 


Q  •  rM  «i4    CD  □  — 


OQ  * 


«L."S      .2  9.13      ^  fi. 


rlO-*^  Cffi-*^  OO-**  <X>d}-** 

lli  11^  il'-a  «^l^ 


Average  quantity  of  salt  and  water — 

Solid  salt 0-63        177        177        3-31        337        363      2230 

Water 9937      98*23      9823      9669      9663      9637      7770 

The  dissolved  solid  matter  consists  in  100  parts  of — 

Chloride  of  sodium  ...  58*25  79*39  84 70  7804  77*07  77*03  36*55 

Chloride  of  potassium    127  107  —  209  2*48  3*89  4*57 

Chloride  of  calcium  ...     —  —  —  0*20  —  —  11*38 

Chloride  of  magnesium  lo'oo  738  973  8'8i  8*76  7*86  45*20 
Bromides  of   sodium 

and  magnesium    ...     —  0*03  —  0*28  0*49  1*30  0*85 

Sulphate  of  lime      ...    778  060  0*13  3*82  2*76  4*63  0*45 

Sulphate  of  magnesia    19*68  832  4*96  658  834  5*29  — 
Carbonates  of  lime  and 

magnesia       302  3*21  0*48  0*18  o*io  —  — 

Nitrogenous  and  bitu- 
minous matter      ...     —  —  —  —  —  —  100 

One  cubic  metre  (35*3165  cubic  feet)  of  sea- water  contains  consequently  abont 
28  to  31  kilos  of  chloride  of  sodium,  and  5  to  6  kilos,  of  chloride  of  potassium. 
Chloride  of  sodium  (common  salt)  is  obtained  from  sea- water : — 

a.  By  the  evaporation  of  the  water  by  the  aid  of  the  sun's  heat. 

b.  In  winter,  by  freezing. 

c.  By  artificial  evaporation. 

Method cj^owigrfngooiniaon  xMs  mothod  of  obtaining  common  salt  from  sea-water  is 
limited  to  certain  of  the  coast-lines  of  Southern  Europe,  and  is  never  effected 
beyond  48**  N.  latitude.  The  countries  best  situated  for  this  industry  are  France, 
Portugal,  Spain,  and  the  coasts  of  the  Mediterranean.  The  arrangement  of  the 
salines,  or  salt-gardens,  is  the  following : — On  a  level  sea-shore  is  constructed  a 
large  reservoir,  which,  by  a  short  canal,  communicates  with  the  sea,  care  being 
taken  to  afford  protection  against  the  inroads  of  high  tides.  The  depth  of  water  in 
these  reservoirs  varies  from  0*3  metre  to  2  metres.  The  sea- water  is  kept  in  the 
reservoir  until  the  suspended  matter  has  been  deposited,  and  is  then  conveyed  by  a 
wooden  channel  into  smaller  reservoirs,  from  which  it  is  conducted  by  undergroond 
pipes  to  ditches  surrounding  the  salines,  where  the  salt  is  separated  from  the  water. 
The  salt  is  collected,  placed  in  heaps  on  the  narrow  strips  of  land  which  separate  the 
ditches  from  each  other,  and  sheltered  from  rain  by  a  covering  of  straw.  As  these 
heaps  are  left  for  some  time,  the  deliquescent  chlorides  of  magneaum  and  caldom 

*  According  to  the  experiments  of  Baron  Sass,  the  water  of  the  Baltic  from  the  Great 
Sound  between  the  Islands  of  Oesel  and  Moon  only  contains  0*666  per  cent  of  solid  matter, 
and  is  of  a  sp.  gr.  =s  z*0O474« 


COMMON  SALT.  X65 

are  absorbed  in  the  soil,  consequently  the  salt  is  comparatively  pure.  The  mother- 
liquor  is  used  in  the  production  of  chloride  of  potassium  (see  ante,  p.  119),  sulphate 
of  soda,  and  magnesia  salts,  the  process  employed  being  that  originally  suggested  by 
IVofessor  Balard,  and  afterwards  improved  by  Merle. 

lynMsfBf.  This  process  is  based  upon  the  fact  that  when  a  solution  of  common 
salt  is  cooled  to  several  degrees  below  the  freezing-point,  it  is  split  up  into  pure  water, 
which  freezes,  and  a  strong  solution  of  salt.  The  solution  becomes  more  con- 
centrated by  repeated  freezing  and  removal  of  the  ice,  until  at  last  a  solution  is 
obtained  which  by  a  slight  evaporation  3rields  a  crop  of  salt.  In  order  to  render  the 
product  purer,  some  lime  is  added  to  the  solution  before  evaporation  to  decompose 
the  magnesia  salts. 

BjrAitudsiETapontion.  Commou  Salt  ovaporatod  from  sea- water  by  the  aid  of  fuel, 
or  tel  ignifire,  is  chiefly  prepared  in  Normandy,  in  the  following  manner : — The  sand 
impregnated  with  salt  is  employed  to  saturate  the  sea-water,  which  is  next 
evaporated.  Very  frequently  an  embankment  of  sand  is  thrown  up  on  the  shore,  so 
as  to  be  covered  at  high  tides  only ;  in  the  interval  between  two  tides  a  portion  of  the 
salt  dries  with  the  sand,  which  in  hot  summer  weather  is  collected  twice  or  three 
times  daily.  The  sand  is  lixiviated  in  wooden  boxes,  the  bottoms  of  which  are  con- 
stracted  of  loose  planks  covered  with  layers  of  straw;  the  sand  having  been 
pat  in  the  boxes  sea-water  is  allowed  to  percolate  through  them  till  the  specific 
gravity  of  the  water  increases  to  1*14  or  to  i' 17,  the  density  being  observed  by  means 
of  thiee  wax  balls  weighted  with  lead.  The  salt  boilers  at  Avrauchin  consider  that  a 
solution  or  brine  of  i'i6  sp.  gr.  is  the  most  suitable  for  evaporation.  The  evapora- 
tion is  carried  on  in  leaden  pans,  and  during  the  process  the  scum  is  removed  and 
fresh  brine  added  until  the  salt  begins  to  crystallise  out,  when  again  a  small  quantity 
of  brine  is  added  to  produce  more  scum,  which  is  at  once  removed,  and  the  evapo- 
ration continued  to  dryness.  The  salt  thus  obtained,  a  finely  divided  but  very 
impure  material,  is  put  into  a  conical  basket  suspended  over  the  evaporating  pan, 
the  object  being  to  remove  by  the  action  of  the  steam  the  deliquescent  chlorides  of 
calcinm  and  magnesium.  The  salt  is  next  transferred  to  a  warehouse,  the  floor 
of  which  is  constructed  of  dry,  well-rammed,  exhausted  sand,  and  here  it  is 
gradually  purified  by  the  loss  of  deliquescent  salts,  the  consequent  decrease  in  weight 
amounting  to  20  to  28  per  cent.  700  to  800  litres  of  brine  yield,  according  to  the 
quantity  of  salt  contained  in  the  sand,  150  to  250  kilos,  of  salt.  A  very  similar 
method  is  in  use  at  Ulverstone,  Lancashire. 

At  Lymington  and  the  Isle  of  Wight,  sea-water  is  concentrated  by  spontaneous 
evaporation  to  one-sixth  of  its  original  bulk,  the  brine  being  then  evaporated  by  the  aid 
of  artificial  heat  In  the  neighbourhood  of  Liverpool  salt  is  obtained  by  employing 
Bea-water  in  refining  crude  rock-salt ;  in  this  way  at  least  23  per  cent  of  common 
Bait  results  as  a  by-product.  During  a  continuation  of  hot  summer  weather,  salt  is 
deposited  from  the  water  of  many  of  the  salt  lakes  in  immense  quantities,  amounting, 
for  instance,  at  the  Elton  Lake,  Russia,  to  20  millions  of  Mlos. 
BA^-Mtt.  This  mineral  is  frequently  accompanied  by  anhydrite,  clay,  and  marl, 
and  is  sometimes  found  in  what  are  termed  pockets  of  irregular  shape,  interspersed 
with  clay.  Again,  in  some  cases  saline  deposits  are  separated  by  layers  of  marl. 
With  rock-salt  other  minerals  sometimes  occur,  as,  for  instance,  brongniartine 
(Na,S04+CaSO4),  near  ViUarubia,  in  Spain,  and  the  remarkable  minerals  of  the 
salt  deposit  near  Stassfurt.  Above  the  latter  deposit  is  a  layer  65  metres  thick, 
of  bitter,  many  coloured,  deliquescent  salts,  consisting  of  55  per  cent  of  camallite. 


i66 


CHEMICAL  TECHNOLOGY. 


sylvin,  and  kainite ;  25  per  cent  of  common  salt ;  16  per  cent  of  kieserite  ;  and  4  per 
cent  of  chloride  of  magnesium.  As  this  saline  layer  contains  12  per  cent  of 
potassa  it  is  an  important  deposit  in  an  industrial  sense. 

The  composition  of  rock-salt  is  as  follows : — 

I.  White  rock-salt  from  Wieliczka;  U.  White,  and  III.  yellow  rock-salt  from 
Berchtesgaden ;  IV.  From  Hall  in  the  Tyrol;  V.  Detonating  salt  from  Hallstadt; 
VI.  From  Schwabischhall. 

n.         m.        IV. 
9985      9992      9943 


I. 

Chloride  of  sodium  loo'oo 

Chloride  of  potassium  — 

Chloride  of  calcium  — 

Chloride  of  magnesium  traces 

Sulphate  of  lime  — 


V. 

9814 
traces 


traces 
015 


007 


0-25 
012 

0'20 


VI. 

9963 
0*09 

028 


1-86  — 


lOOOO  lOOOO       lOOOO         lOO'OO  lOO'OO        ICX>'00 

The  so-called  detonating  salt,  found  at  Wieliczka  in  crystalline-granular  masses, 
has  the  property  when  being  dissolved  in  water  of  giving  rise  to  slight  detonations 
accompanied  by  an  evolution  of  hydrocarbon  gas  from  microscopically  small  cells, 
the  walls  of  which  becoming  thin  when  the  salt  is  dissolved  in  water,  give  way,  and 
cause  the  report.  If  the  solution  of  the  salt  takes  place  naturally  in  the  mine,  the 
gas  partly  escapes,  partly  becomes  condensed,  forming  petroleum,  often  met  with  in 
beds  of  rock-salt.  The  minerals  of  the  salt  deposit  of  Stassfurt  are,  according 
to  MM.  Bischof,  Eeichardt,  Zincke,  and  others,  the  following : — 


Chemical 
Formula. 


In  100  parts  are 
contained : 


100  parts  of 
water  dis- 
solve at 

isr  C. 


Synonyms 
and  Obser- 
vations. 


Anhydrite 


CaS04    100  of  Sulphate  of  lime    2*968  020  '        Karstenite. 


Boracite 


.1 


29 


Camallite 


Bed  oxide  of 
iron 

Kieserite     ... 


26*82  Magnesia 
BieOjoCla  65 '57  Boric  acid 
Mg7      10*61  Magnesium  chlo 

ride  j 

2676  Chloride  of  potas- 

KMffCl,  ,,  ®^^  VI      I        .:   Q 

4-6H  O  34'5°  Magnesium  chlo- 1  1*618 
3874  Water 

Fej03     100  of  Oxide  of  iron         3*35 
(  MffSO  4-  ®7*io  Sulphate  of  mag-' 


Almost 
insoluble  J 


I  Stassfortite. 


645 


Contains 
Bromine. 


Insoluble.  — 


H^O' 


nesia 
12*90  Water 


•  2*517 


409 


Martinsite? 


45' 1 8  Sulphate  of  lime] 

2CaS04  19*93  Sulphate  of  mag- 1 

T>  1  1.  !•*«      J   MgSOj  nesia  1 2720 

Polyhalite  ..A    j^^g^^*   ^g.^  Sulphate  of  po- 

I     2H4O  tassa 

v  5*99  Water 

*  According  to  Bammelsberg  it  is  probable  that  kieserite  is  originally  an  anhydront 
mlnerid,  a  eonclasion  which  Qeems  justified  by  the  variable  quantity  of  water  found  in 
different  analyses. 


Is  decom- 
posed while 
being  dis- 
solved 


COMMON  SALT. 


167 


Chemical         In  xoo  parts  are 
formula.  contained : 


2   • 


& 


a 


zoo  parts  of 
water  dis- 
solve at 
x8r  0. 


Rock-Bait    ...        NaCl       100  Choride  of  sodium     2*200        36*2 


Svlvin 


KCl 


100  Chloride  of  potas- 
sium 


) 


2025 


345 


Synonyms 
and  Obser- 
vations. 


Tachhydrite 


Kainite 


Schonite  or 
Pilcromerite 


21  50  Chloride  of  cal-^ 
CaCla  cium 

2MgCl2    3698  Chloride  of  mag 
12H2O  nesium 

41-52  Water 

3634  Sulphate  of  po-^ 
K.SO  tassa 

MgSO*    ^5'^  Sulphate  of  mag- 
nxcrC*}  nesia 

^ff^Q     i8'95  Magnesium  chlo- 
^  ride 

19*47  Water 

43-18  Sulphate  of  po-^ 
K2SO4  tassa 

MgS04    29*65  Sulphate  of  mag- 
6H3O  nesia 

26-97  Water. 


1-671       i6o*3 


Contains 
Bromine. 


Sylvin  is  also  found  in  large  quantities  in  the  salt  deposit  near  Kalucz,  Qalicia. 

vodeofwoikiiigBoek-Mtt.  Bock-salt,  like  other  minerals  and  according  to  its  mode  of 
occurrence,  is  either  quarried  or  mined.  If  it  happens,  however,  that  the  rock-salt 
is  mixed  with  other  minerals,  clay,  gypsum,  dolomite,  &c.,  a  solution  in  water  is 
effected,  which  is  pumped  up  from  the  mine  as  a  concentrated  brine.  In  many 
instances  rock-salt  is  wrought  in  extensive  and  deep  mines,  as  in  the  celebrated  rock- 
salt  mines  of  Wieliczka. 

vodtoiwcddiigsidt-ipdiigs.  Natural  salt-springs  sometimes  occur  which  have  been 
imitated  artificiaUy  by  boring  to  a  great  depth  into  layers  of  earth  containing  saline 
deposits.  In  this  manner  a  brine  may  be  obtained  sufficiently  concentrated  to 
be  at  once  boiled  down.  The  method  of  working  the  natural  salt-springs  is  to  form 
a  convenient  reservoir  from  which  the  saline  solution  is  immediately  pumped  up  for 
the  purpose  of  being  gradated  (see  p.  168).  The  solution  previous  to  being  boiled 
down  is  left  to  allow  the  suspended  matter  to  settle.  The  salt-springs  obtained 
by  boring  either  yield  a  native  brine,  or  the  borings  are  carried  into  solid  rock-salt 
and  water  caused  to  descend  into  the  salt  deposit.  This  artificial  brine  is  then  pumped 
up,  unless  there  is  naturally  an  artesian  formation.  The  brine  previous  to  further 
operations  is  left  for  some  time  in  reservoirs  to  deposit  suspended  insoluble  matter. 

These  saline  solutions  are  not  always  free  from  impurities ;  in  considering  their  admixture 
brine  may  be  divided  into  two  classes ;  the  first  containing  sulphate  of  magnesia  or  soda, 
with  chloride  of  magnesium ;  the  other  class  embraces  brine  containing  the  chlorides 
of  calcium  and  magnesium.  If  the  brine  happens  to  pass  through  peaty  soil  or  layers  of 
hgnile,  there  often  accrues  organic  matter^  humic,  crenic,  and  apocrenic  acids. 


i68  CHEMICAL  TECHNOLOGY. 

^^Sifrm '^Kf**""      ^''^  operation  is  duplex  and  consists  in — 

a.  Concentrating  the  brine. 

a.  By  increasing  the  quantity  of  salt. 
p.  By  decreasing  the  quantity  of  water. 

b.  The  boiling  down  of  the  concentrated  brine. 

ooaeoitimting  the  Brine.  Native  brines  or  salt-springs  seldom  contain  enough  common 
salt  to  make  it  profitable  to  boil  them  down  at  once ;  it  is  consequentiy  necessary  to 
enrich  the  brine,  and  this  may  be  done  either  (a)  by  dissolving  in  it  rock-salt 
or  crude  sea-salt,  neither  being  suited  for  culinary  and  many  other  purposes  unless 
refined,  or  (/3)  by  decreasing  the  quantity  of  water  without  the  use  of  fuel 

Eazioiiiiig  by  onMUtion.  The  enriching  or  concentration  of  a  brine  by  decreasing  the 
quantity  of  water  it  contains  is  called  a  gradation  process,  and  may  be  proceeded 
with  by  freezing  off  the  water  in  winter  time,  or  more  generally  by  evaporating  the 
water  by  a  true  gradation  process ;  either — a.  Gradation  by  the  effect  of  the  sun's 
rays.    b.  Table  gradation,    o.  Roof  gradation,    d.  Drop  gradation. 

Gradation  by  means  of  the  sun's  rays  is  obviously  the  same  method  of  procedure  as 
that  described  under  the  treatment  of  sea-salt.  Table  gradation  has  been  only  experi- 
mentally tried  at  Beichenhall,  and  consists  simply  in  causing  the  brine  to  flow  slowly 
from  a  reservoir  down  a  series  of  steps,  constructed  so  as  to  give  as  much  suriace  as  pos- 
sible, and  thus  hasten  the  evaporation.  Boof  gradation  is  effected  by  utilising  the  roofs 
of  the  large  timks  containing  the  brine  as  evaporation  surfaces,  by  causing  the  contents  of 
the  tanks  to  flow  in  a  thin  but  constant  stream  over  the  roofs,  which,  of  course,  are 
exposed  to  the  open  air. 

vegsotamdAtioa.  This  operation,  also  known  as  drop  gradation,  is  carried  on  by 
means  of  the  following  apparatus,  termed  gradation  house,  and  consisting  of  a  frame- 
work of  timber,  fitted  with  faggots  of  the  wood  of  Prunta  tpinoiay  which  being 
thorny,  presents  a  large  surface.  The  entire  construction  is  built  over  a  water-tight 
wQoden  tank,  which  receives  the  concentrated  brine,  and  frequentiy  the  top  of 
the  gradation  house  is  provided  with  a  roof.  Under  the  roof  and  above  the  faggots 
a  water-tight  tank  is  placed  containing  the  brine  to  be  gradated;  this  tank  is 
provided  with  a  number  of  taps,  from  which  the  brine  trickles  into  channels  provided 
with  holes  to  admit  of  the  brine  fisdling  on  the  faggots.  These  taps  are  placed 
on  both  sides  of  the  gradation  house,  and  are  generally  connected  with  levers  to 
admit  of  being  readily  turned  on  and  off  from  below.  The  gradation  process  is  con- 
tinued until  the  brine  is  sufficiently  concentrated  to  admit  of  being  further  evai>o- 
rated  by  the  aid  of  fuel ;  the  brine  may  be  gradated  to  contain  26  per  cent  of  salt, 
but  the  operation  is  rarely  carried  so  far. 

The  gradation  process  not  only  serves  the  purpose  of  concentration,  but  also  that 
of  purifying  the  brine,  as  some  of  the  foreign  salts  are  deposited  on  the  &ggots,  this 
deposit  of  course  varying  in  composition  according  to  the  constituents  of  the  brine, 
but  chiefly  consisting  of  carbonate  of  lime,  with  the  sulphates  of  potassa,  soda,  and 
magnesia.  The  deposit  has  in  some  instances  been  used  as  manure.  In  the  tanks 
where  the  gradated  brine  is  collected  another  slimy  deposit  is  gradually  formed,  con- 
sisting of  gypsum  and  hydrated  oxide  of  iron.  As  in  the  present  day  the  brine 
obtained  from  bored  wells  is  generally  sufficiently  concentrated  to  be  at  once  boiled 
down,  gradation  is  less  frequent,  being  a  very  slow  process  and  involving  a  loss  of 
the  salt  carried  off  by  the  wind. 

Boiling  down  the  Brine.  The  object  is  to  obtain  witii  the  least  possible  expenditure  of 
fuel  the  largest  quantity  of  pure  dry  salt.    Formerly  the  evaporation  was  carried  on 


COMMON  SALT.  169 

in  large  cauldrons,  but  at  the  present  time  evaporating  vessels  are  constmcted  of 
well  rivetted  boiler-plate,  the  shape  being  rectangular,  the  length  10  metres,  depth 
0*6  metre,  and  width  from  4  to  6  metres.  These  pans]  are  supported  by  masonry, 
which  also  serves  to  separate  the  flues.  Over  the  pans  a  hood  is  fixed  and  con- 
nected with  a  tube  carried  to  the  outside  of  the  building  to  afford  egress  to  the 
steaoL  The  brine,  concentrated  to  contain  from  18  to  26  per  cent  of  salt,  is  poured 
into  the  pans  to  a  depth  of  0*3  metre. 

The  boiling  down  process  is  in  many  salt  works  conducted  in  two  different  opera- 
tioDs: — 

a.  The  evaporation  of  water  to  produce  a  brine  saturated  at  the  boiling-point. 

b.  The  boiling  down  of  the  saturated  brine  untU  the  salt  crystallises  out. 

The  boiling  down  is  generally  carried  on  for  several  weeks,  the  scum  being 
removed,  and  also  the  gypsum  and  sulphate  of  soda  deposited  at  the  bottom  of  the 
pan,  with  perforated  ladles.  As  soon  as  a  crust  of  salt  is  formed  on  the  surface  of 
the  liquid,  a  temperature  of  50"  is  maintained.  At  this  stage  the  salt  is  gradually 
deposited  at  the  bottom  of  the  pan  in  small  crystals,  and  being  removed,  is  put  into 
conical  willow  baskets,  which  are  hung  on  a  wooden  support  over  the  pan  to  admit  of 
the  mother-liquor  being  returned  to  it.    Finally,  the  salt  is  dried  and  packed  in  casks. 

The  quantity  of  mother-liquor  collected  after  boiling  for  some  two  or  three  weeks  is, 
compared  with  the  quantity  of  brine  evaporated,  very  small ;  it  was  formerly  thrown  away 
or  used  for  baths,  but  is  now  employed  for  the  preparation  of  chloride  of  potassium,  the 
nlpbates  of  soda  and  magnesia,  artificial  bitter  water,  and  in  some  instances  for  pre- 
pazing  bromine.  It  is  evident  that  by  the  boiling  down  all  the  salt  contained  in  the  brine 
is  not  reduced  as  dry  refined  salt,  a  portion  being  retained  among  the  early  deposit  formed 
at  the  bottom  of  the  pan,  another  portion  remaining  in  the  mother-liquor,  and  finally 
some  loss  accmes  from  the  nature  of  the  operations,  amounting  generally  from  4  to  9*25 
per  cent.  As  in  some  countries  salt  is  an  article  upon  which  an  excise  duty  is  levied,  in 
order  that  it  may  be  employed  duty  free  for  certain  industri^  purposes,  it  is  mixed  in 
Tuioufl  proportions  with  substances  rendering  it  unfit  for  culinary  use. 

rnpotiM^^oommon  Chloride  of  sodium  crystallises  in  cubes,  the  size  of  the  crystals 
determining  the  varieties  known  in  the  trade  as  coarse,  medium,  and  fine  grained 
salt,  and  depending  upon  the  rate  of  evaporation  of  the  brine,  a  slow  evaporation 
producing  very  coarse  salt.  Perfectly  pure  common  salt  is  not  hygroscopic,  but  the 
ordinary  salt  of  conmierce  contains  small  quantities  of  the  chloride  of  magnesium 
and  sodium.  Usually  salt  contains  from  25  to  5 '5  per  cent  water,  not  as  a  constituent, 
but  as  an  intermixture;  hence  the  phenomenon  called  decrepitation,  due  to  the 
breaking  up  of  the  crystals  by  the  action  of  the  steam  when  salt  is  heated.  Ignited 
to  a  strong  red  heat  chloride  of  sodium  fuses,  forming  an  oily  liquid,  and  at 
a  strong  white  heat  is  volatilised  without  decomposition.  Common  salt  is  readily 
soluble  in  water,  and  is  one  of  the  few.salts  almost  equally  soluble  in  cold  and  in  hot 
water;  100  parts  of  water  at  12^  dissolve  35*91  parts  of  common  salt. 

In  order  to  express  the  quantity  of  salt  contained  in  a  brine,  it  is  usual  to  say  the 
brine  is  of  a  particular  fineness,  strength,  or  percentage ;  for  instance,  a  brine  at 
15  per  cent  contains  in  100  parts  by  weight  15  parts  of  salt  and  85  parts  of  water. 
The  QrSdigheit  or  degree  9f  a  brine  means  the  quantity  of  water  which  holds  in  solution 
I  part  by  weight  of  salt ;  a  brine  of  15*6  Grddigheit  contains,  therefore,  i  part  by 
weight  of  conmion  salt  in  156  parts  of  water.  The  poundage  (PJUndigkeit)  of  a 
brine  indicates  in  pounds  the  quantity  of  salt  'contained  in  a  cubic  foot  of  brine. 
The  following  table  shows  the  percentage  of  salt  contained  in  brines  of  the  several 
specific  gravities: — 


lyo 


CHEMICAL  TECHNOLOGY, 


Salt  per  oent. 

Sp.gr. 

Salt  per  cent. 

Sp.  gr. 

Salt  per  oent. 

Sp.gr, 

I 

10075 

7*5 

10565 

16 

I'I206 

1*5 

10113 

8 

I  0603 

17 

I  1282 

2 

10151 

8-5 

I  0641 

18 

I  1357 

2'5 

1-0188 

9 

10679 

19 

11433 

3 

ro2z6 

9*5 

I  "0716 

195 

11510 

35 

10264 

10 

10754 

20 

11593 

4 

1030a 

10*5 

I  0792 

21 

11675 

45 

10339 

II 

I  0829 

22 

11758 

5 

10377 

"•5 

10867 

23 

1*1840 

55 

10415 

12 

10905 

24 

1*1922 

6 

10452 

13 

10980 

25 

12009 

6-5 

1*0490 

14 

1*1055 

2639 

12043 

7 

10526 

15 

11131 

t7M8of  Common  ^*  ^®  ^^^  neoessary  to  enter  into  particulars  on  this  subject.  Salt  is  used 
Bait.  as  a  necessary  condiment  to  food ;  a  man  weighing  75  kilos,  contains  in  his 
body  0*5  kilo,  of  common  salt,  and  requires  annually  775  kilos,  to  maintain  this  supply. 
Common  salt  is  used  in  agriculture,  and  is  as  necessai^  for  cattle  and  horses  as  for  man. 
It  serves  industrially  in  the  preparation  of  soda,  chlorine,  sal-ammoniac,  in  tanning, 
in  many  metallurgical  processes,  the  manufacture  of  aluminium  and  sodium.  Further, 
it  is  employed  in  the  glazing  of  the  coarser  kinds  of  pottery  and  earthenware,  from  the 
fact  that  when  common  salt  is  fused  with  a  clay  containing  iron,  the  sodium  is  oxidised 
at  the  expense  of  the  iron,  and  forms  soda,  which,  combining  with  the  alumina  and  silica, 
supplies  a  glaze,  while  the  iron  combining  with  the  chlorine  is  volatilised.  The  uses  of 
common  salt  for  the  preservation  of  wood,  for  curing  meat,  preserving  butter,  cheese,  Ac, 
are  too  well  known  to  require  explanation.  Among  the  salt-producing  countries  of 
Europe,  England  takes  the  lead,  producing  annually  32,400,000  cwts.,  while  Germany 
only  produces  10,  and  Russia  20  million  cwts. 

Manufactube  of  Soda. 

(Soda  or  Sodium  carbonate,  Na2C03=io6.    In  100  parts,  58*5  parts  soda  and 

41 '5  parts  carbonic  acid.) 

BodA.      All  the  soda  commonly  used  is  derived  from  the  three  undermentioned 

sources : — 

a.  Natural  or  native  soda; 

p.  From  plants ; 

y.  Chemical  production. 

a.  Native  Soda, 
o«iu«n«Mjf  NatiT.  Soda  is  found  in  many  mineral  waters,  as  at  Kaxlsbad,  where  the 
waters  yield  annually  133)700  cwts.  of  carbonate  of  soda,  and  at  Burtscheid,  Aix*la- 
Chapelle,  Vichy,  and  the  Geyser,  in  Iceland.  Soda  occurs  as  an  efflorescence  on 
some  kinds  of  rocks,  chiefly  of  volcanic  origin,  as  trass  and  gneiss.  Sesquicarbonate 
of  soda,  C308Na4-|-3H20,  is  met  with  in  large  quantities  in  the  water  of  the  so-called 
soda  lakes  of  Egypt,  Central  AMca,  the  borders  of  the  Caspian  Sea  and  Black  Sea, 
in  California,  Mexico,  and  elsewhere.  During  the  hot  suipmer  season  a  portion  of 
the  level  country  of  Hungary  is  covered  with  an  efflorescence  of  carbonate  of  soda, 
locally  known  as  Szikso,  which  is  collected  and  brought  to  market.  The  Egyptian 
name  for  soda  is  Tro-Na,  hence  the  Germsm  term  Natron.  The  soda  locally  known 
in  Columbia  as  Urao  is  obtained  from  a  lake,  La  Lagunilla,  distant  48  miles  from 
the  town  of  Merida.    During  the  hot  season  the  urao  crystallises  from  the  water, 


•  SODA.  ryr 

and  is  gathered  from  the  bottom  of  the  lake  at  a  depth  of  3  metres  by  divers,  with 
great  risk  of  their  lives ;  the  annual  quantity  collected  amounts  to  1600  cwts.  When 
he  Spaniards  were  in  possession  of  this  territory  the  urao  was  a  government 
monoply,  and  was  brought  to  Venezuela  for  the  preparation  of  Mo  or  inspissated, 
tobacco  juice.  Very  recently  an  inexhaustible  supply  of  native  soda  has  been  found 
in  Virginia.* 

Various  theories  have  been  proposed  to  explain  the  origin  of  native  soda,  but  here 
ts  in  other  instances  it  is  best  to  bear  in  mind  that  a  posse  ad  esse  nan  valet  eonclusio. 
Native  soda  is  rarely  exported  from  the  countries  where  it  is  found  and  collected) 
excepting  the  Eg3rptian  Tro-Na,  which  is  brought  to  Venetia  for  glass  mnlHTig 
purposes  and  met  with  in  the  trade  in  the  shape  of  bricks  made  up  with  sand. 

p.  Soda  from  Plants,  or  Soda-ash. 

"^JldSpm'SJet w^  When  treating  in  a  former  chapter  of  potassa  we  saw  that  the 
ash  of  plants,  especially  of  those  grown  at  a  considerable  distance  from  the  sea, 
contains  carbonate  of  potassa;  likewise  that  plants  grown  near  the  sea-shore  and  in 
the  localities  known  as  salt  steppes  yield  an  ash  which  contains  more  or  less  soda 
in  the  living  plant  combined  with  sulphuric  and  organic  acids,  and  which  imder  the 
influence  of  the  carbonate  of  lime  is  during  the  tgnition  of  the  plant  converted  into 
carbonate  of  soda.  In  addition  to  the  species  of  Fitcus  growing  in  the  sea  itself, 
the  genera  known  as  Salsola,  Atriplex,  Salicortiiay  &c.,  are  employed  for  the 
preparation  of  soda,  and  until  lately  were  largely  cultivated  for  this  purpose.  The 
process  of  obtaining  soda  from  these  plants  simply  consists  in  burning  them  in  pits 
dug  in  the  sand  near  the  sea-shore,  the  heat  of  the  combustion  becoming  so  intense 
as  to  cause  the  ash  to  flux,  so  that  after  cooling  the  material  forms  a  hard  slag-Hke 
niass,  termed  in  the  trade  crude  soda  or  soda-ash,  the  quantity  of  carbonate  of  soda 
it  contains  varying  from  3  to  36  per  cent.  This  new  material  is  refined  by  exhausting 
with  water,  and  evaporating  the  liquor.  From  the  diflerent  plants  and  modes  of 
preparation  employed  we  obtain  the  following  distinctions  in  kind: — 

a.  Barilla,  from  Alicante,  Malaga,  Garthagena,  the  Canary  Islands,  and  the  Barilla 
soda  {SaUola  soda)  produced  on  the  Spanish  coast ;  contains  on  an  average  from  25  to  30 
per  cent  of  carbonate  of  soda. 

b.  Salicor,  or  soda  from  Narbonne,  obtained  by  the  ignition  of  the  Salieomia  anniui, 
planted  purposely,  and  gathered  when  the  seed  is  ripe ;  contains  about  14  parts  of  carbonate 
of  soda. 

c.  Blanquette,  or  soda  from  Aignes-Mortes,  prepared  from  the  plants  growing  wild  on 
the  tract  of  comparatively  barren  land  lying  between  Aigues-Mortes  and  Frontignan,  viz., 
the  Salieomia  Europeay  SaUola  tragus,  Salsola  kali.  Statics  limonium,  AtripUx  por- 
tttlaeoides.    This  soda  only  contains  from  3  to  8  per  cent  of  sodic  carbonate. 

d.  Araxes  soda,  of  about  the  same  value  as  the  preceding,  is  largely  used  in  Southern 
Bxisaia,  and  is  obtained  from  plants  of  the  mountain  plateau  of  the  Araxes  in  Armenia, 
where  the  soda  is  prepared. 

e.  Of  less  value  even  than  the  preceding  is  the  Varec  soda,  obtained  on  the  coasts  of 
Kormandy  and  Brittany  from  the  go^non,  Fitcus  vesiculosus.' 

/.  Kelp  is  obtained  in  Scotland  and  the  Orkneys  by  the  combustion  of  various  sea- weeds, 
the  Fucus  serraius,  F.  nodosus,  Laminaria  digitata,  and  Zostera  marina.  Notwithstanding 
that  480  cwts.  of  dried  plants  only  yield  20  owts.  of  kelp,  containing  no  more  than  from 
50  to  100  lbs.  of  Bodio  carbonate,  20,000  people  are  occupied  in  the  Orkneys  alone  in  the 
preparation  of  kelp. 

g.  Among  the  varieties  of  soda  derived  from  plants  may  be  mentioned  that  obtained 
in  considerable  quantity  from  the  vinasse  of  beet-root,  but  this  soda,  according  to 
^sandier's  analysis,  always  contains  carbonate  of  potassa. 

■ 
•  See  ♦•  Chemical  News,"  vol.  xri.,  p.  129. 


1731  CHEMICAL  TECHNOLOGY. 

y.  Soda  prepared  by  Chemical  Processes. 

^'^^^iSS^^  M.  Leblanc,  the  inventor  of  the  successful  method  of  conyerting 
common  salt  into  carbonate  of  soda,  may  indeed  be  considered  as  an  immediate 
benefactor  to  his  countrymen,  who,  until  the  latter  half  of  the  last  century,  annually 
paid  20  to  30  millions  of  &ancs  to  Spain  for  barilla.  The  war  which  broke  out  in 
1792  terminated  the  importation  of  soda,  potash,  and  saltpetre  into  France,  and 
hence  the  Oomit6  du  Salut  Public  decreed  in  1793,  amongst  other  measures,  that 
all  soda  manufacturers  should  give  the  fullest  particulars  of  their  mode  of  working, 
and  the  processes  they  imagined  might  be  used  on  the  large  scale  to  obtain  soda 
equally  good  and  cheap  as  that  from  barilla  without  the  use  of  that  or  any  similar 
material.  The  manufacturer  Leblanc  was  the  first  who  sent  in  full  particulars  on 
this  subject,  and  his  process  was  declared  by  the  committee  to  be  the  best  and  most 
suitable,  the  verdict  standing  unshaken  to  the  present  day,  which  witnesses  the 
improvement  of  the  recovery  of  the  sulphur  from  the  soda  waste. 

LebiMM'i  Proeeu.      This  now  cousists  in  the  following  stages : — 

a.  The  preparation  of  sulphate  of  soda  from  salt  by  the  aid  either  of  sulphuric 

acid  or  sulphates,  or  by  the  roasting  of  common  salt  with  iron  pyrites  or 
other  native  metallic  sulphurets. 

b.  Conversion  of  the  sulphate  iiito  crude  soda  by  roasting  with  a  mixture  of 

chalk  and  small  coal. 

o.  Conversion  of  the  crude  soda  into  refined  soda  or  caustic  soda  by  lixiviation 
and  evaporation. 

d.  Becoveiy  of  the  sulphur  from  the  soda  waste. 
Deeo^^^uxwee.  ^'  ^®  ^^^  usual  mode  of  converting  common  salt  into  sul- 
phate of  soda  is  by  the  action  of  sulphuric  acid.  The  condensation  of  the  hydro- 
chloric acid  gas  is  generally  effected  by  a  method  introduced  in  1836  by  Mr.  Gossage, 
and  consisting  in  tiie  use  of  a  contrivance  known  as  coke-  or  condensing-towers. 
These  are  square  buildings  from  12  to  14  metres  in  height,  by  an  interior  width  of 
1*3  to  1*6  metres,  constructed  of  stone  not  acted  upon  by  hydrochloric  acid,  the 
joints  being  cemented  with  a  mortar  made  of  coal-tar  and  fire-clay.  To  nearly  the 
top  these  buildings  are  divided  by  a  wall,  each  compartment  thus  formed  being 
fiUed  with  pieces  of  coke  resting  on  a  perforated  stone  floor.  Water  is  caused  to 
flow  constantiy  from  the  top  of  the  tower  on  to  the  coke.  The  hydrochloric  acid  gas 
resulting  from  the  decomposition  of  the  salt  by  sulphuric  acid  is  conducted  by  means 
of  stoneware  tubes  to  the  bottom  of  the  first  compartment  of  the  condensing-tower, 
and  there  meeting  with  the  moist  coke  is  condensed  to  within  95  per  cent  of  the 
entire  quantity,  the  other  compartment  of  the  condensing-tower  being  usually  in 
direct  connection  with  the  chimney -shaft  of  the  alkali- works.  The  decomposition- 
fumaces  at  first  in  use  were  reverberatoiy  furnaces  so  constructed  that  the  smoke 
and  gases  from  the  combustion  of  the  coals  and  the  hydrochloric  acid  gas  passed  off 
together,  and  as  a  consequence  the  hot  gases  were  not  in  the  best  condition 
for  condensation.  The  furnace  now  in  general  use  is  that  invented  in  1836  by 
Gossage,  and  improved  in  1839  by  Gamble,  who  was  the  first  to  arrange  the  two 
phases  or  stadia  of  the  decomposition  in  the  separate  compartments,  o  and  k,  of  the 
furnace  exhibited  in  Fig.  71.  This  arrangement  has  been  used  for  a  very  long 
period,  the  alkali  manufacturers  employing  a  reverberatoiy  furnace  which  could  be 
put  into  communication  at  pleasure  with  a  kind  of  muffle,  the  bottom  consisting  of  a 
stout  cast-iron  plate,  the  flame  from  the  furnace -grate  being  made  to  play  against 


SODA. 


>73 


Ihis  mnffle  previously  to  entering  the  chimney.  The  mufQe  commtmlcated  with  a 
(xodeiuiiig  appaiSitDB,  h  h'.  According  to  this  plan  of  worldiig,  &e  common  salt 
WW  pUeed  in  o,  and  well  warmed  eulphuric  acid  made  to  flow  over  it ;  a  very  strong 
and  violent  reaction  took  place,  and  half  or  nearly  two-thirds  of  the  hydrochloric 
acid  formed  was  readily  condensed,  as  it  was  not  mixed  with  the  hot  gases  of  the 
combnalion.  The  prodnct  resulting  from  thia  mode  of  operation  was  a  mixture  of 
Wsiilphate  of  Boda  and  common  salt,  zNaCl+HiS0i=NaH80(+Naa+HCl. 
This  mixture  was  nest  shovelled  into  the  reverheratory  furnace,  B,  the  moffle  being 
»guD  charged  with  salt  and  acid.  By  the  intense  heat  of  the  reverberalory  fnmace 
the  mixture  of  hisnlphate  of  soda  sjid  common  salt  was  converted  into  neutral 
sulphate,  NaHS04+NaCl=Na,S04+HCl;  the  hydrochloric  acid  gas  evolved  in 
this  operation  was,  however,  condensed  with  difficulty,  in  conaeqnence  of  being 
mixed  with  nitrogen,  carbonic  acid,  and  carbonic  oxide ;  and  besides  the  condensing- 

Fio.  71. 


towers  other  and  complicated  apparatus  were  required  to  prevent  the  escape  of  acid 
fnmes  into  the  air.  These  defects  have  been  remedied  in  the  constrootion  of  an 
improved  decompodtion-famace. 

Rnimnipniiini.raiua.  This  fomaee  consists  of  two  muffles,  one  of  oast-iron,  the 
Other  of  fire-bricks;  the  interior  of  the  former  is  a  segment  of  a  hollow  sphere  of 
g  feet  or  274  metres  diameter,  and  i  foot  g  inches  or  0*52  metre  deep,  resting  on 
brick-work.  A  cast-iron  lid  is  provided,  in  shape  also  a  segment  of  a  sphere,  having 
a  depth  in  the  centre  of  i  foot  or  030  metre  ;  in  this  Lid  are  arranged  two  openings 
with  suitable  doors,  through  one  of  which  the  common  salt  is  introduced,  while  the 
other  communicaleB  with  the  second  mnfSe.  The  hearth  is  placed  obliquely,  the 
flames  first  playing  on  the  lid,  and  then  passing  under  the  muffle ;  accordingly  the 
hjdrochlorio  acid  gas  is  niunixed  with  other  gases,  and  its  temperature  being  com- 
paiatiTely  low,  condensation  is  more  readily  efiected.  The  second  or  brickwork  muffle 
CDcloaee  a  space  of  30  feet  or  9*14  metres  inlength,  by  9  feet  or  274  metres  in  width; 
under  the  floor  of  this  room  a  series  of  flues  or  channels  ore  built,  while  (he  top  is 
formed  of  a  double  vault  to  admit  the  circulation  of  the  flames,  which  are  next  con- 

dncted  through  the  channela  under  the  floor. 


174 


CHEMICAL  TECH}10L0GY. 


The  mode  of  operation  is  as  follova : — Into  tlie  iron  mufSe,  prerionaly  well  heated. 
half  a  ton  of  conunou  salt  is  introduced,  b>  which  isadded  sulphnric  acid  of  17  sp.gr.. 
the  qnantdty  of  the  aeid  being  regulated  so  as  to  leave  i  to  3  per  cent  of  salt  imde- 
coniposed  in  order  to  obtain  a  perfectly  neutral  aulphato.  lOo  parte  of  salt  reqoire 
for  their  complete  decomposition  1)5  parts  of  an  acid  at  60°  B.  =  17  sp.  gr.,  or 
104  parts  of  an  acid  at  55°  B.  =  1  '6z  ep.  gr.  The  mixture  of  acid  and  salt  is  occasion- 
ally well  stirred,  and  after  the  lapae  of  i|  hours  has  become  sufficiently  dry  to  be 
raked  over  into  the  brick-work  compartment  of  the  oven,  which  is  kept  at  a  bright 
red  heat  to  assiBt  the  expulsion  of  the  hydrochloric  acid  gas.  If  it  is  desired  to 
obtain  a  concentrated  hydrochloric  acid  solution,  the  escaping  gas  must  be  cooled 
down  before  entering  the  condensing- towers.  There  is  generally  a  valve  or  damper, 
by  which  the  communication  between  the  two  mufSes  may  be  closed,  in  order  that 
the  hydrochloric  acid  gaa  evolved  in  each  may  be  separately  collected  and  condensed. 
With  these  contrivances,  and  well  constructed  condensers  supplied  plentifully  with 
water,  the  preparation  of  sulphate  of  soda  may  be  carried  on  without  any  inconveul- 
enoo  to  the  neighbourhood  in  wiiich  the  works  are  situated.  For  more  than  twenty 
years  Messrs,  Tennant,  of  Glasgow,  have  employed  this  iiind  of  fumaee,-  decomposing 
500  tons  of  common  salt  per  week  without  receiving  any  complaints.  On  the  Conti- 
nent, alkah  works  are  legnHy  compelled  to  have  the  decomposition-furnaces  con- 
stmoted  according  to  a  plan  first  brought  out  in  Belgium,  and  which  is  very  similar 
to  the  furnace  already  described.  The  assertion  of  Dr.  Wagner,  in  his  original  text, 
concerning  the  many  complaints  now  arising  in  England  in  reference  to  .the  escape 
of  hydrochloric  acid  fumes  firom  alkali-works,  is  altogether  unfoonded,  the  fact  being 
that  according  to  the  published  reports  of  the  Inspector,  Dr.  Angus  Smith,  under  the 
Alkah  Act,  nearly  all  the  manniacturers  condense,  instead  of  95  per  cent  of  the 
hydrochloric  acid,  as  required  by  the  Act,  from  97  to  9S-5  per  cent. 

""'"^ilaiSsSi?'"'*  *■  ^  order  to  convert  the  sulphate  of  soda  into  crude  or 
raw  Bodic  carbonate,  the  former  salt  is  mixed  with  chalk,  or  sometimes  with 
slaked  lime  and  small  coal,  and  this  mixture,  fused  in  a  reverberatory  furnace. 
According  to  Leblanc'a  directions,  the  proportions  are — 

Sulphate    loo  parts 

Cliatk 100     „ 

Slaked  lime       50     „ 

fant  the  quantities  as  employed  in  ten  diHerent  works  vary  for  100  parts  of  sulphate 
firom  go  to  121  parts  of  clulk,  and  the  quantity  of  small  coal  from  40  to  75  parts. 


In  some  alkali-works  for  a  portion  of  the  chalk  is  substituted  the  desulphnrised  and 
lixiviated  soda  waste.  The  reverberatory  furnace  generally  used  in  English  alkali- 
works,  and  technically  known  as  a  h/tlUiig /i/i-iiner,  is  sliowu  in  J'ig.  72,  and  that 


tmplojed  in  Germany  in  Fig.  73.  In  England,  the  materiola  having  been  first 
lieated  on  the  npper  stage  of  the  furnace  by  the  waste  heat,  only  remain  in  ths 
tcorkitig  furnace  (see  Fig.  ^z)  for  about  half-an-hour ;  in  Oennan  works  the  mixture 
of  sulphate,  chalk,  and  small  coal  is  strongly  heated  in  h,  see  Fig.  73.  nntil  the  ma«s 
becomes  fluxed  and  paety,  and  lambent  flames  of  burning  carbonic  oxide  are  ejected 
from  the  Btirface.  When  this  is  seen  the  semi-Snid  mass  is  removed  from  the 
ftmiace  throngh  the  openings  p  p.  and  transferred  to  an  iron  car,  c,  -where  it  is  left 

It  is  difficult  to  say  whether  the  English  or  Continental  method  is  the  more 
preferable ;  viewed  from  a  theoretical  point  of  view,  it  would  appear  that  the  English 
method  is  the  better  of  the  two.    As  in  English  works,  a  smaller  quantity  of 


instenals,  only  about  7  cwts.,  while  in  coulinenlal  works  firom  30  to  70  cwta.,  is 
operated  npoa  at  a  time,  the  labour  is  lighter ;  the  materials,  too.  are  not  exposed  to 
u  intense  heat  for  a  long  period ;  thus  a  loss  of  soda  by  the  volalilisation  of  the 
todinm  is  less  likely  to  occur.  According  to  Wright's  investigations  (18G7),  the  loss 
of  soda  by  the  conversion  of  the  sulphate  amounts  to  20  per  cent  of  the  sodium  con- 
liined  in  the  sulphate,  as  shown  by  the  following  figures : — 

Undecomposed  3nlphat«    

Insoluble  sodium  compounds 

Volatilisation  of  the  sodium     , 

Sodium  retained  in  the  waste 

Loss  occasioned  hy  the  evaporation  of  the  liquors 


.-.    349 


361 
656 


*imh^^Jr£  ^  'S53  Elliot  and  Russell  suggested  a  contrivance  which  dis- 
pensed with  the  gtirring  of  the  materials  by  manual  labour,  and  consisted  of  a  cyUn- 
drical  T«0sel  made  to  rotate  on  a  horizontal  axis.  Stevenson  and  Williamson  im- 
proved apon  this  idea,  and  according  to  their  plan  of  working  (see  Fig.  74)  the 
Enixture  of  sulphate,  chalk,  and  small  coal  is  placed  in  the  iron  cylinder,  a,  lined 
with  fire-clay.  Ribs  or  rails,  e,  cast  on  the  cylinder,  nm  on  the  wheels,  c,  receiving 
notion  from  machinery  with  wliich  they  gear,  and  causing  the  cylinder  to  rotate. 
The  heated  air  of  the  hearth,  n,  flaws  through  the  opening  r  into  the  cylinder,  and 
passing  through  f.  reaches  the  vaulted  compartment,  o,  and  is  carried  ofi'  by  the  flue, 
X.  to  the  chimney.  The  interior  of  the  cylinder  having  been  heated  to  redness,  the 
"Mteriols  are  allowed  to  fall  into  it  from  the  waggon,  j,  through  the  funnel  H. 
After  the  lapse  of  ten  minutes  the  cylinder  is  caused  tomeke  a  half  revolution. and  is  then 
left  (or  five  minutes,  the  operation  being  coiitinned  until  the  masii  inside  the  cylinder 


176  CHEMICAL   TECEHOLOQY. 

ioMSi,  which  takes  pUce  in  about  half -an -hoar.  The  cylinder  is  then  set  contina- 
ouBly  in  motion  so  as  to  make  one  revolution  eveiy  three  minutes.  The  progress 
from  time  to  time  is  watched  through  a  door-way  constructed  in  the  cylinder,  and 
Ks  soon  as  the  operation  is  complete  the  molten  mass  is  run  off  through  the  opening  b'. 
There  can  he  no  doubt  tliat  the  rotat«ry  furnace  is  a  great  improvement,  and  one 
which,  besides  saving  labour,  prevents  a  loss  of  soda  by  volatilisation.  A  cylinder 
II  feet  long  and  75  feet  in  diameter  converts  in  two  hours  14  cwts.  or  yew  kilos,  of 
sulphate  at  an  expenditure  of  only  as.  id. 


Fio.  74. 


The  composition  of  the  omde  or  hall  soda  is  approiimatsly  :— 
Carbonate  of  soda    . . 
Solphnret  of  ealeinm 
Caustic  lime 
Carbonate  of  lime 
Foiei^  Bubstanses   . . 


[1  glass  making,  soap  botUug. 


In  thig  oonntty  large  quantities  ol  soda-ash  ate  used  i 
bleaching,  and  other  operations. 

''''cmfcBn^*'  "■  Conversion  of  crude  into  refined  soda  by  lixiviation  and 
evaporation,  a.  Lixiviation  of  the  crude  soda.  When  the  cmde  soda  is  acted  upon 
by  water  there  results  a  solution  containing  chiefly  carbonate  of  soda,  and  a  mass 
remaining  osdissolved  known  as  soda  waste.    100  parts  of  raw  soda  yield : — 

Soluble  matter    45-0  parts 

Soda  waste 587    „ 

1037    .. 

As  a  mle  English  ball  soda  has  a  deeper  colour,  and  contains  more  carbon  t)uu> 
the  soda  of  continental  manufacture.  Ball  soda,  previously  to  being  lixiviated,  is 
usually  exposed  for  at  least  two  and  sometimes  for  ton  days  to  the  action  of  the  air,  lo 
gain  in  porosity,  and  hence  be  more  readily  acted  upon  by  the  water. 

Of  the  several  methods  of  lixiviation  proposed,  and  in  more  or  less  suooessfol  dm 
on  the  large  scale,  may  be  mentioned  the  following : — The  method  of  lixiviation  by 
simple  filtration  is  not  to  be  recommended  on  account  of  the  great  labour  it  requires, 
but  the  process  consists  in  putting  the  crude  soda,  previously  broken  np  into  lumps 
of  suitable  size,  into  tanks  provided  with  a  perforated  fidse  bottom,  upon  which  the 


cnide  gods  is  placed,  water  being  poured  on.    This  urongemetit  ia  represented  in 

Kg.  75,  A.  B,  c.  D-    The  perforated  false  bottom  is  about  25  centdma.  from  the  bottom 

of  the  tanks.    The  wooden  channel,  k,  suspended  from  the  ceilmg  of  the  shed  bj 

Ok  iron  bonds,  t  f',  eonvejs  water, 

vhiclib;  means  of  the  pli^,  {.  t',  and 

1",  can  be  let  into  the  tanks,  these 

being  proTided  with  taps,  r,  r',  and 

/',  by  which  the  liquid  can  be  nm  off 

into  the  channel,  E*.  To  illustrate  the 

mdui  operandi  three  tanks,  *,  a,  c, 

ire  sofficieDt :  A  is  filled  with  fresh 

ball  Boda,  B  with  ball  soda  once, 

and  c  with  ball  soda  twice  lixiviated. 

We  then  begin  by  filling  each  tank 

with  the  liquor  which  has  been  used 

for  washing  the  soda  waste  the  last 

time  before  throwing  it  aside ;  this  Uqnid  remains  in  each  tank  for  a  period  of  eight 

hnnTB,  and  the  alkaline  ley,  which  then  marks  30°  B..  is  run  oS  from  a,  and  the 

operation  repeated  with  weaker  liquors  in  b  and  c,  the  leys  bemg  all  conveyed  to  a 

Wge  reservoir,  the  contents  of  which  mark  35°  B.     Fresh  liquor  is  poured  mto  a 

and  B,  and  into  d,  which  is  filled  with  bail  soda,    B7  this  arrangement  a  constant 

supply  of  ley  at  25°  B.  is  kept  up. 

Desormes's  lixiviatiun  apparatus.  Fig.  76,  consists  of  a  series  of  twelve  to  fourteen 
tanks,  of  which  only  live,  a,  b,  c,  d.  e.  are  exhibited  in  the  woodcut.  By  means  of 
the  bent  tubes,  fitted  about  15  ccntima.  from  the  bottom  of  each  tank,  the  liquor 
flows  into  the  next  lower  tank  of  the  series,  and  so  to  the  tanks,  r  f',  called  the 
clearing  or  settling  tanks,  of  which  there  are  sis  connected  together  by  tubes.  The 
btll  soda  to  be  lixiviated  ia  ground  to  powder,  and  placed  in  the  perforated  sheet- 
iton  vessels,  e  e.  d  d,  and  so  on.     d  t  the  commencement  the  tanks  are  filled  with 

Fio.  76. 


warm  water,  and  two  perforated  vessels  placed  in  e  filled  with  50  kilos,  of  ball  soda ; 
after  twentj-five  minutes  these  vessels  are  removed  to  d,  and  oUiers  filled  with  fresh 
soda  placed  in  E.  In  this  manner  the  operation  proceeds,  so  that  after  eight  hours, 
when  fourteen  lixiviation  tanks  are  worked,  there  are  fotmd  in  a  perforated  vessels 
which  have  been  gradually  removed  from  the  lowest  to  the  highest  tank,  a,  two 


•78 


CHEMICAL  TBCnSOLOOT. 


vessels.  //,  having  been  removed  firam  that  tenli  and  placed  apon  die  shelf,  k,  \f> 
drain,  where  having  remained  for  about  half-an-honr  the^  are  removed,  the  contents 
emptied,  and  other  veasela  placed  to  drain.  Each  time  that  two  of  the  perforated. 
vessels  filled  with  ball  Boda  are  placed  in  the  lowest  tank,  there  is  ponied  into  ths 
uppermost  as  much  water  as  correspanda  with  the  bnik  of  the  fresh  soda ;  this  water 
displaces  the  heavy  \ej  which  runs  through  the  tube  from  a  to  B,  and  so  on,  tmtil  ait 
last  the  concentrated  and  nearlj  saturated  liquor  runs  from  B  iuto  f  f,  where  any 
suspended  matter  is  deposited.  The  temperature  of  the  liquor  in  these  tanks  shonld. 
be  from  45°  to  50°;  but  not  h^her,  in  order  to  prevent  anjr  dectnnpoBition  of  the 
sulphide  of  calcium.  The  liziviatiou  tanks,  as  well  as  the  clearing  tanks,  are 
provided  with  steam  pipes  for  the  purpose  of  keeping  the  liquor  sufficiently  heated, 
and  to  prevent  any  soda  ciTstallising  ont  by  cooling.  It  is  almost  evident  that  this 
method  of  Uxiviation  is  the  best  which  can  be  adopted,  as  the  concenbated  liqnor 
cannot  adhere  to  the  solid  substance  which  it  is  intended  to  dissolve,  because  in 
consequence  of  its  high  sp.  gr.  the  liquor  sinks  to  the  bottom  of  the  tank.  Fig.  77 
represents  two  liziviation  tanks  drawn  ta  a  larger  scale,  and  of  a  somewhat  diSerent 
arrangement.  Es«h  tank  is  divided  into  three  compartments  by  means  of  a  doable 
partition  wall,  commnnit^tion  between  the  two  compartmenta  being  provided  by  tba 

Fio.  77. 


M33f 


V^.  i^lifl 


holes  a  and  b  and  the  space  between  the  partition  plates  reoeiving  the  steam  pipes, 
hh.  g  g  are  the  tubes  for  conveying  the  liquor,  and  n  n  the  perforated  vessels,  to 
which  are  rivetted  iron  bars  serving  the  pnrpose  of  handles.  Mr,  James  Shanks,  of 
St.  Helen's,  was  the  first  to  found  a  rational  and  economical  plan  of  lixiviation,  on 
what  is  termed  methodical  filtration,  based  upon  the  fact  that  a  solution  becomes  more 
dense  the  more  saline  matter  it  has  in  solution,  and  that  a  colnmn  of  weak  ley  of  a 
oertain  height  equilibrates  a  shorter  column  of  a  stronger  ley.  In  accordance  with 
this  principle,  the  tanks,  four  or  eight  in  number,  are  placed  as  shown  in  Fig.  78, 
and  through  them  water  is  caused  to  flow,  exhausting  the  crude  soda  in  its  passage, 
and  becoming  consequently  denser  in  each  consecutive  tank  of  the  series ;  hence, 
the  level  of  the  Uqnid  is  lowered  in  each  tank  from  the  first,  which  contains  pure 
water,  to  the  last,  from  which  a  saturated  ley  runs  off.  The  length  of  the  <*iifc»  is 
2*6  metres  \ij  2  metres  in  depth ;  p  is  a  perforated  false  sheet-iron  bottom  Bapp<»ted 
by  iron  bars.  From  the  bottom  of  each  tank  an  open  tube,  t,  the  lower  opening 
being  cnt  diagonally,  and  at  the  top  a  smaller  tube,  I,  soldered  on,  connect  the  tanks. 
The  water  pipes,  r  r  r  r,  fitted  with  taps  are  placed  to  admit  of  water  being 
supplied  to  each  tank ;  by  means  of  the  taps,  r  b',  the  ley  can  he  run  ofiT  into  tba 
f.    Four  lixiviations  as  a  mle  suffice.    The  working  is  as  fbllowa :— The 


fint  tank  contains  boll  sods  already  three  times  lixiviated;  the  liquor  added  to  it  is  a 
verj  weak  soda  solation  from  a  former  operation,  which  percolates  into  the  second  tank. 
The  liquid  there  meeta  with  soda  which  lias  been  twice  submitted  to  the  lixiviation 
process,  and  nest  flows  over  into  the  third  tank,  the  solid  contents  of  which  have 
been  only  once  preidously  lixiviati>d.    Finally,  the  lye  arrivee  in  the  foorth  took,  in 


Fio.  78. 


I    I    I 


*hich  fresh  ball  soda  has  been  placed,  and  &om  this  tank  flows  into  a  large  re 
The  first  tank  having  been  cleared  of  soda  waste  is  now  filled  with  fresh  hall  soda, 
Mid  the  succession  of  the  operation  reversed  by  the  aid  of  taps  fitted  to  the  tnbes 
connecting  the  tanks.  The  larger  the  nnmber  of  tanks  the  more  rapidly  within 
certain  limits  a  given  weight  of  erode  soda  can  be  exhausted.  The  density  of  the 
ley  ought  to  be  from  i'27  to  i'z86,  a  cubic  foot,  or  O'OzS  cubic  metre,  containing 
from  4*5  to  495  kilos,  of  solid  matter.  The  advantages  of  this  mode  of  lixiviation 
ore — I.  That  the  carriage  of  the  crude  soda  from  one  tank  to  another  i&  dispensed 
with,  and  consequently  much  labour  saved.  3.  The  soda  being  always  covered  with 
liquid  cannot  cake,  3.  As  the  current  is  always  downwards  the  most  concentrated 
{■ortion  of  the  flnid  is  conveyed  forward,  and  consequently  less  water  is  required. 

4.  By  the  continuity  of  the  operation  any  reaction  between  the  alkali  and  the 
insoInUe  calcium  snlphuret  is  prevented,  or,  in  other  words,  the  formation  of  soluble 
alksline  and  other  snlphurels,  entailing  a  loss  of  soda,  is  reduced  to  a  minimnm. 

5.  The  high  degree  of  concentration  of  the  ley  effects  a  considerable  saving  in  the 
expenae  of  the  evaporation. 

The  nature  of  the  ley,  after  the  suBpended  matter  has  been  deposited,  greatly 
depends  npon  the  condition  of  the  ball  soda  employed,  the  duration  of  the  process, 
■ndthe  temperature  of  the  water;  it  is,  therefore,  difficult  to  make  any  general 
diservation.  Kynaston,  Schenrer-Kestner,  and  Kolh  have  proved  that  ball  Boda 
dace  not  contain  caustic  soda,  and  that  consequently  the  presence  of  this  substance 
in  the  ley  ie  due  to  the  action  under  water  of  the  lime  upon  the  sodic  carbonate. 
Solpliuret  of  calcium  can  only  be  present  in  the  dry  hall  soda  in  Tery  small  quantities, 
bit  Bulphnret  of  sodium  may  exist  in  the  ley  to  a  greater  extent  than  caustic  soda, 
the  quantity  varying  with  the  mode  of  lixiviation.  Conunonly,  only  monosolphuret 
of  sodium  is  present  in  the  ley ;  even  if  a  polysulphuret  were  temporarily  formed  it 
WDold  be  immediately  converted  into  monosulphuret  by  the  presence  of  the  caustic 
tods.  The  dry  ball  soda  contains  peroxide  of  iron,  converted  into  sulphnret  of  iron 
V  the  action  of  the  water ;  this  snlphuret  dissolving  in  the  sulphuret  of  sodiom 
cuses  the  greeu-  or  yellow-brown  colour  of  the  ley.    The  quantity  of  water  employed 


i8o  CHEMIGAL  TEGHNOLOOY. 

in  the  lixiviation  has  no  effect  upon  the  causticity  of  the  ley,  but  the  qnantity 
of  sulphuret  of  sodium  increases  with  the  quantity  of  water,  the  duratioQ  of 
the  lixiviation,  the  temperature,  and  the  concentration;  this  is  owing  to  the 
increased  solubility  of  the  sulphuret  of  calcium,  which,  when  in  contact  with  water, 
is  converted  into  hydrosulphuret  of  calcium  and  hydrate  of  lime,  the  former  yielding 
with  caustic  soda  the  more  sulphuret  of  sodium  the  higher  the  concentration  of  the 
ley.  The  same  reasoning  holds  good  for  carbonate  of  soda,  which  is  also  converted 
into  sulphuret,  but  only  in  veiy  dilute  solutions,  at  a  higher  temperature  after  a 
lengthened  contact. 

According  to  Eolb's  researches,  ball  soda  should  be  lixiviated  rapidly,  with  but  a 
small  quantity  of  water,  and  at  a  low  temperature.  If  it  were  possible  it  would  be 
a  great  improvement  to  contrive  an  apparatus  in  which  ball  soda  could  be  lixiviated 
in  a  few  hours  with  only  so  much  cold  water  as  would  yield  a  very  concentrated  ley ; 
the  liquors  obtained  under  such  conditions  would  be  free  from  sulphuret  of  sodium. 

The  following  analysis  will  give  some  idea  of  the  composition  of  the  crude  ley. 

The  sample  was  obtained  from  the  alkali- works  of  Matthes  and  Weber,  at  Duisburg, 

the  sp.  gr.  =  1*25,  i  litre  containing  3139  grms.  of  solid  saline  matter,  consisting  in 

100  parts  of — 

Carbonate  of  soda 71250 

Caustic  soda    24*500 

Common  salt 1*850 

Sulphite  of  soda      0*102 

Hyposulphite  of  soda     0369 

Sulphuret  of  sodium      0235 

Cyanide  of  sodium 0087 

ArgiQaceous  earthy  matter' 1*510 

OlxlOof  «•«        •••        •«•        •••        •••        •••        •••  UX  00 

«LrCJU    •••         ■••         •••         ■••         •«•         •••         •■•         «••  liXc&C*wD 


100*089 
Another  crude  ley  from  some  works  near  Aix-la-Chapelle  was  of  a  sp.gr.  =  1252, 
and  contained  311  grms.  of  solid  matter  per  litre. 

STtpontion  of  om  Ley.  /3.  The  clarified  liquor  contains  essentially  carbonate  of  soda 
and  caustic  soda,  with  common  salt  and  other  soda  salts  in  smaller  quantities.  Owing 
to  the  presence  of  the  double  sulphuret  of  iron  and  sodium,  the  ley  is  coloured 
during  the  evaporation,  if  it  be  performed  with  the  liquor  immediately  from  the 
lixiviation  tanks ;  to  prevent  this  result  it  is  necessary  that  the  leys  should  stand  for 
a  considerable  tiii^e  in  the  clearing  reservoirs  to  effect  a  slow  oxidation  of  the  com- 
pound salt,  more  rapidly  attained  by  forcing  a  current  of  air  through  the  ley,  as 
suggested  by  Oossage.  Bleaching-powder  and  nitrate  of  soda  are  used  as  oxidising 
agents ;  a  lead-salt,  oxide  of  copper,  and  spathose  iron  ore  have  been  employed.  As 
Kolb*8  researches  have  proved  that  monosulphuret  of  iron  is  insoluble  in  caustic  and 
in  carbonate  of  soda  solutions,  an  addition  of  sulphate  of  iron  will  have  the  effect  of 
converting  the  double  sulphuret  of  iron  and  sodium  into  monosulphuret  of  iron  and 
sulphate  of  soda,  the  former  salt  settling  rapidly  and  yielding  a  clear  coloarless 
liquid,  and  on  evaporation  a  colourless  salt. 

The  ley  is  treated  in  either  of  the  two  following  ways  : — 

a.  Evaporated  to  dr3Tie8s,  tiie  result  being  a  homogeneous  product  which  contains 
unaltered  all  the  constituents  of  the  ley,  including  the  caustic  soda. 


p.  The  ley  is  evaporated  to  a  certain  degree  of  concentration,  the  aapersatiirated 
solntion  dcpoaiting  on  cooling  carhonate  of  soda  aa  a  crystalline  powder,  containing 
imolecnle  of  water,  Na^COj+HjO;  the  salt  is  gradnally  removed  from  the  liquor 
by  perforated  ladles.  During  the  evaporation  fresh  ley  is  nm  into  the  pan  from,  a 
regervoir  at  a  higher  level,  and  in  this  way  the  operation  is  continued  for  Beveral 
aonthB.  It  is  clear  tbat  by  conducting  the  evaporation  in  this  manner,  the  carbonate 
of  Boda  collected  becomes  gradually  less  and  less  pure,  being  mixed  with  chloride  of 
Bodinm  and  solphate  of  soda ;  at  last  a  mother-ley  is  left,  containing  chiefly  caustic 
uda  uid  solphnret  of  sodium,  and  in  a  concentrated  solntiaD  of  these  substances  the 
other  salts  are  insoluble.  The  crystalline  carbonate  of  soda  is  first  drained,  anopera- 
tioii  sometimes  performed  in  centrifugal  turbines,  and  then  calcined  in  a  reverbera- 
tory  fomace  to  oxidise  any  snlphuret  of  sodium  that  might  be  present ;  after  this 
caldnstion  the  salt  constitutes  the  calcined  soda  of  conunerce.  The  quality  of  the 
(omiDertial  article  varies  consideiablj,  the  difference  being  partly  due  to  the  care 
taken  in  the  evaporation.  The  first  crop  of  salt  is  always  the  best,  that  is  to  say, 
contains  the  largest  percent^e  of  sodic  carbonate,  somelintes  amounting  to  90  per 


cent    When  the  ley  la  lo  1  j   rut  i  tu  in  tl       1     siti  1   is  carridd  on  in  a 

rtverberatory  fnmace.  Fig.  jg.  The  hearth  is  floored  witli  fire-bricks,  on  to  which  a 
thick  coating  of  carbonate  of  soda  is  well  rammed.  The  fnel  burning  in  a  is  coke ; 
IS  soon  aa  the  furnace  has  become  thoronghly  red-hot,  ley  previously  evaporated  to 
]]°  B.  in  the  pans  n  and  e,  is  ran  into  the  furnace,  effecting  a  very  rapid  evapo- 
ntion  to  dryness,  care  being  taken  to  stir  the  saline  mass  to  keep  the  salt  in  a 
pulvemlent  state.  By  means  of  the  dampers,  f  o,  and  the  flues,  o  c',  the  hot  air  and 
fiime  of  the  burning  fuel  may  be  conducted  under  the  pans  n  and  b  or  into  the 
chimney.  The  composition  of  soda  thus  evaporated  to  dryness  is,  according  to  the 
uulyais  of  two  samples  by  Mr,  J.  Brown,  as  follows: — 

L  n. 


.     ...    68-907 

65-513 

Caustic  soda     

.     ...     14-433 

16072 

Sulphite  of  soda      

.    ...      7018 

7-812 

Hyposulphite  of  soda     ... 

2-23« 

2 '34 

Sulphuret  of  sodium 

.  ...     ran 

I-54I 

Chloride  of  Bodium 

3-972 

3*852 

Alnminate  of  soda  

.   ...    1016 

1-233 

Silicate  of  soda 

1-030 

O'Soo 

Insoluble  mattor     

0-814 

0974 

i82  CHEMICAL   TECHNOLOGY, 

The  salt  is  next  calcined,  and  the  salphoret  of  sodium  converted  into  snlpfaite  of  aoda, 
a  portion  of  the  caustic  soda  being  converted  into  carbonate  of  soda.  The  otklcined  salt 
is  now  read;  for  the  market ;  but  in  some  of  the  large  alkali-works  near  Newcastle-on- 
Tyne  it  is  re-dissolved  in  water,  treated  with  carbonic  add,  and  again  evaporated.  A 
better  product  results  from  another  method,  namely,  evaporating  the  ley  to  a  known 
degree  of  concentration,  and  obtaining  small  crystals  of  soda-salt  (NaaCO^+ H^O).  In 
this  case,  as  regards  the  methods  of  evaporation  employed,  the  two  followmg  are  most 
general: — Heat  is  brought  to  bear  on  ihe  surface  of  the  liquid  contained  in  shallow 
rectangular  iron  pans  fitted  to  the  hearth  of  a  reverberatory  furnace ;  the  liquid  rapidly 
boils  at  the  surface,  and  a  saline  crust  is  formed,  which  is  constantly  broken  up  and 
collected  with  iron  rakes  by  the  workmen.  Now  and  then  the  salt  deposited  at  the  bottom 
is  removed  and  placed  on  a  sloping  ledge  to  drain.  This  method  of  evaporation  is  eoono- 
mical,  but  attended  with  the  disadvantage  that  the  ley  is  constantly  in  contact  with  the 
carbonic  and  sulphurous  acid  gases  arising  from  the  combustion  of  the  fuel,  the  conse- 
quence being  that  a  portion  of  the  caustic  soda  is  converted  into  carbonate  and  sulphite 
of  soda,  the  latter  by  the  subsequent  calcining  operation  being  converted  into  sulphate. 
By  the  second  plan  of  evaporation  the  heat  is  conveyed  to  the  bottom  of  the  pans,  but 
then  many  precautions  are  required  to  prevent  the  bottom  being  burned  in  consequence  of 
the  settling  down  of  a  saline  mass  not  conducting  heat.  Mr.  Gamble,  at  St.  Helens, 
employs  a  pan  of  a  peculiar  form,  the  section  being  like  that  of  a  boot ;  it  is  heated  by  the 
waste  heat  of  the  soda  furnace,  and  the  inclination  of  the  sides  of  the  pan  greatly  assistB 
the  removal  of  the  salt,  which,  having  been  drained,  is  calcined,  yielding  a  grey-coloured 
salt,  afterwards  purified  by  solution  with  the  aid  of  steam  in  a  small  quantity  of  water, 
decanting  the  clear  solution,  and  again  evaporating  it.  Balston  obtains  a  purer  product 
by  washmg  the  impure  ^bonate  with  a  cold  saturated  solution  of  pure  carbonate  of  soda, 
the  chloride  and  sulphuret  of  sodium  and  the  sulphate  being  thus- removed.  As  already 
stated,  the  evaporation  is  not  always  continued  to  dryness,  but  to  a  degree  of  concentra- 
tion determined  by  experience.  By  varying  the  relative  bulk  of  the  Uquid  a  more  or  less 
pure  product  may  be  obtained;  when,  for  instance,  the  ley  of  the  lixiyiation  tanks 
(r=  1*286  sp.  gr.)  is  evaporated  to  y^^ths  of  its  bulk  and  the  sidt  separated  removed,  this 
salt  corresponds  to  a  purified  soda  salt  of  57  per  cent ;  by  evaporating  the  remaining 
liquid  to  |ths  of  its  bulk,  a  salt  of  50  per  cent  is  obtaineid.  When  the  mother-liquor  is 
evaporated  to  dryness,  a  very  caustic  and  impure  salt  is  obtained.  Euhlmann,  at  Lille, 
employs  pans  which  are  graduated  so  that  the  bulk  of  the  liquid  may  be  readily  ascer- 
tained for  the  purpose  of  fractioned  evaporation.  The  purification  of  the  crude  ley, 
containing  sulphuret  of  iron  dissolved  by  sulphuret  of  sodium,  may  be  effected,  as 
suggested  by  Gossage,  in  1853,  by  filtering  the  liquid  through  a  coke-tower  (one  of  the 
towers  used  for  condensing  hydrochloric  acid),  a  current  of  air  being  forced  upwards  to 
assist  in  oxidising  the  sulphuret  of  sodium. 

The  composition  of  refined  soda,  according  to  Tissandier's  analyses,  is: — 

I.  2.  3.  4.  5. 

Moisture 2*22  3*11  1*15  x*oo  0*40 

Insoluble  matter      . .     . .  0-12  0*22  0*08  —  0*06 

Chloride  of  sodium  . .     ..  12*48  6*41  3'28  2*11  0*99 

Sulphate  of  soda     . .     . .  8*51  3*25  2*15  1*50  0*35 

Carbonate  of  soda   . .     . .  76*67  87*01  92'34  95*39  98*20 

100*00      100*00      xoo'oo      xoo'oo      100*00 
The  composition  of  soda,  containing  caustic  soda,  is : — 

I.  a.  3-  4- 

Moisture 2*10  1*50  2*48  1*38 

Insoluble  matter       ..     ..      0*12  cii  0*21  0*09 

Chloride  of  sodium  ..     ..      4*32  2*43  3*50  4*11 

Sulphate  of  soda      . .     . .      8'8o  1*62  2*15  2*50 

Carbonate  of  soda     . .     . .  82*47  88*09  84*54  81*67 

Caustic  soda      2*11  6*25  7*12  10*25 

100*00   lOO'OO   XOO'OO   xoo*oo 

In  order  to  obtain  crystallised  soda,  Na2003-{-ioH20,  with  63  per  cent  of  water, 
a  saturated  solution  of  calcined  soda  in  hot  water  is  poured  into  large  iron  vessels, 
and  yields  crystals  on  cooling.  The  calcined  soda  is  generally  dissolved  in  oonical 
vessels  (Fig.  80),  made  of  boiler-plate,    c  is  a  steam-pipe,  b  a  water-pipe,  n  aper- 


SODA. 


183 


(orated  Teasel  to  eont&m  the  c&ldned  eoda  to  be  dissolved.  The  boiler  is  tliree- 
fbmtlia  filled  with  water,  the  perforated  vessel  filled  with  soda  is  then  lowered  into  the 
liquid,  and  the  steam  turned  on.  The  soda  is  nipidlj  diBsolved,  and  when  the 
■dntioii  marks  30°  to  32°  B.  it  is  run  into  the  crTStallieing  vessels ;  the  crystaUiaa- 
Uon  is  complete  in  five  to  six  days  in  moderately  cool  weather.  The  crjstala  are 
broken  up,  and  again  dissolved  in  water  in  the  vessel  k  (Fig.  81),  heat«d  by  the  fire 
■t  c.  on  are  fines  carrying  flame  and  heated  air  round  the  vessel ;  s  is  a  water-pipe. 
The  vessel  having  been  filled  with  crystals,  a  Email  quantity  of  water  is  added,  and 
■ssoonasthe  salt  is  completely  dissolved,  thefireisextingnished,  the  liquid  being  left 
to  settle.    The  clear  liquid  is  next  syphoned  into  a  reservoir,  and  from  this  poured 

Fio.  80. 


intocast-iron  ciygtallisiug  vessels.  After  seven  or  eight  days  the  mother-liquor  is 
removed,  and  the  crystals  are  detached  from  the  surface  of  the  iron  by  placing 
Ibe  cryBtallisiiig  vessels  for  a  few  moments  in  hot  water,  tbe  result  being  that  by  the 
incipient  fomon  of  the  oiystals  in  their  water  of  crystallisation,  they  are  loosened 
from  the  metal  to  which  they  adhere.  After  draining,  the  salt  is  dried  in  rooms 
heated  to  15°  to  18°,  and  then  packed  in  casks.  Although  a  crystalline  salt  is  gene- 
rally purer  than  a  non -crystallised  mass,  yet  the  large  quantity  of  water  contained 
in  ctystalUsed  carbonate  of  soda  is  an  impediment  to  its  extensive  use,  both  on 
account  of  expense  of  carriage  and  the  weakness  of  the  alkali.  In  this  country, 
however,  owing  to  the  great  facility  of  water  carriage,  crystallised  carbonate  of  soda 
is  very  largely  used. 

Tttrnitt  LdiiuiyFniMa.  The  prooess  of  M.  Leblanc  has  been  best  elucidated  by  the 
mere  recent  researchea  of  Gossage  and  Schenrer-Eestner.  Formerly  it  was 
utnmed  that  when  a  mixture  of  snlphate  of  soda,  carbonate  of  lime,  and  carbon 
were  calcined,  the  carbon  while  yielding  carbonic  oxide  converted  the  sulphate  of 
aoda  into  solphnret  of  sodinm,  in  its  turn  decomposed  by  the  carbonate  of  lime,  the 
result  being  the  formation  of  carbonate  of  soda,  oxysulphnret  of  calcium,  and 
•he  evolution  of  a  portion  of  the  carbonic  acid;  (a)  NaiS04+2C=NaiS-faC0j; 


i84  CHEMICAL   TECHNOLOGY. 

08)  2Na«S+3CaC03=2NaaC03+CaO,2CaS+COa.  According  to  Unger  the  car- 
bonate of  lime  loses  its  carbonic  acid  as  soon  as  snlphuret  of  sodinm  is  fonned, 
there  remaining  a  mixture  of  caustic  lime,  snlphuret  of  sodium,  and  carbon,  which 
becomes  converted  into  oxysulphuret  of  calcium,  and  caustic  soda,  the  latter 
by  taking  up  the  carbonic  oxide  resulting  from  the  combustion  of  the  carbon 
becoming  sodium-carbonate ;  this  view  appears  to  be  nearest  the  truth,  but  as  proved 
by  Scheurer-Kestner,  Dubrimfaut,  J.  Eolb,  and  Th.  Petersen,  it  is  not  necessary  to 
assume  the  existence  of  oxysulphuret  of  calcium  for  the  purpose  of  explaining  the 
fact  that  the  snlphuret  of  calcium  does  not  act  upon  the  sodium-carbonate,  because 
snlphuret  of  calcium  is  almost  insoluble  in  water,  12*5  parts  of  water  dissolving  at 
1 2*6°  only  I  part  of  snlphuret  of  calcium.  This  view  is  also  confirmed  by  the 
results  of  experiments  made  by  Pelouze.  During  the  formation  of  soda  in  the  cal- 
cining furnace  the  carbon  is  only  converted  into  carbonic  acid,  viz. : — 

a.  5Na2S04+ioC=5NaaS+ioCOa. 

/8.  5Na2S+7CaC03=5NaaG03+5CaS+2CaO+2COa. 

However,  as  there  is  formed  during  the  calcination  process,  especially  towards  the 
end  of  this  operation,  a  not  inconsiderable  quantity  of  carbonic  oxide  which  bums 
off  with  a  bluish  flame,  this  substance,  although  a  secondary  product,  has  to  be  taken 
into  account  in  the  formula ;  moreover,  the  formation  of  this  gas  is  important,  for  as 
soon  as  it  makes  its  appearance  the  chief  reaction  is  being  completed,  proving 
the  heat  to  be  at  its  proper  degree. 

The  researches  of  Ungor  have  xmdoubtedly  proved  that  when  the  sulphate 
is  reduced  by  carbon  there  is  only  carbonic  acid  and  not  a  trace  of  carbonic  oxide 
formed,  so  that  carbonic  oxide  is  the  result  of  the  action  of  the  excess  of  carbon 
upon  the  carbonate  of  lilne ;  this  reduction  of  the  carbonate  of  lime  by  carbon  takes 
place  at  a  much  higher  temperature  than  that  at  which  the  sulphate  is  reduced, 
therefore  the  formation  of  carbonic  oxide  takes  place  after  that  of  the  carbonate 
of  soda.  Consequently  there  must  be  distinguished  three  phases  in  the  formation  of 
soda,  viz. : — 

a.  The  reduction  of  the  sulphate,  with  evolution  of  carbonic  acid  gas — 

(Na«S04+2C=NaaS+2C0a). 

/3.  Double  decomposition  of  the  newly  formed  snlphuret  of  sodium  and  carbonate 
of  lime  {Na2S+CaC03=Na,C03+CaS). 

y.  The  reduction  of  the  excess  of  carbonate  of  lime  by  the  carbon — 

(2CaC03+2C=2CaO+4CO). 

During  the  lixiviation  the  presence  of  caustic  lime  aids  the  formation  of  caustic 
soda.  According  to  theory,  100  parts  of  sulphate  only  require  20  of  carbon,  but  it 
is  the  practice  to  employ  an  excess  of  carbon,  as  much  as  40  to  75  per  cent,  to  pro- 
vide against  incomplete  mixture,  the  combustion  of  carbon  without  effect,  and 
because  of  the  necessity  of  obtaining  the  reaction  of  the  carbonic  oxide  in  order 
that  the  progress  of  the  operation  may  be  observed,  as  experience  has  proved  that  the 
mass  should  not  be  removed  from  the  furnace  until  this  combustion  is  nearly  over. 

utiuaation  of  8od»  WMte.  The  greater  part  of  the  soda  now  employed  is  obtained  ly 
Leblanc's  process,  which,  while  it  admits  of  lixiviating  the  soda  readily  and  com- 
pletely, is  defective,  inasmuch  as  the  residue,  or  waste  as  it  is  technically  called, 
contains  nearly  all  the  6ulx>hur  used  in  the  manufacture ;  and  that  this  is  not  a  slight 
loss  may  be  inferred  from  Oppeuheim's  statement,  that  in  the  alkali  works  at  Dieuze, 


I 


SODA.  185 

Lomdne,  the  accnmulated  waste  contains  an  amount  of  snlphnr  valued  at  £150,000. 
For  ereiy  ton  of  alkali  made  there  is  accnmulated  i|  tons  of  waste,  containing 
80  per  cent  of  the  sulphur  used  in  the  manufacture ;  and  this  waste,  until  lately 
thrown  on  a  refuse  heap  in  some  field  adjacent  to  the  works,  often  proved  a  nuisance 
in  hot  weather,  giving  rise  to  fumes  of  sulphuretted  hydrogen.  For  the  last  forty 
jears  much  time  and  money  have  been  spent  in  trying  to  recover  the  sulphur, 
but  not  until  1863  '^^^^  ^^7  attempt  successful.  Three  different  processes  are  now 
resorted  to,  viz. — Guckelberger's,  modified  and  practised  by  Mond ;  Schafiher's  plan; 
and  the  process  invented  by  M.  P.  W.  Hofmann,  at  Dieuze.  Since  the  first  suc- 
ceasfol  experiment  the  methods  have  been  so  rapidly  improved  that,  at  the  Paris 
Exhibition  of  1867,  no  fewer  than  nine  samples  of  recovered  sulphur  were  sent  in. 
All  the  methods  mentioned  above  are  based  upon  the  same  principle — ^the  conversion 
of  the  insoluble  sulphurets  of  calcium  contained  in  the  waste  into  soluble  compounds 
by  the  aid  of  the  oxygen  of  the  atmosphere ;.  the  lixiviation  of  the  oxidised  mass, 
and  precipitation  of  the  sulphur  contained  in  the  leys  by  a  strong  acid,  practically 
hydrochloric  acid. 
"^^'wSwon pt^s^*"  ^-  Schaffiier's  plan  for  the  regeneration  of  sulphur  from  soda 
waste  involves  the  foUowiug  operations : — 

a.  Preparation  of  the  liquor  containing  sulphur. 
p.  Decomposition  of  the  liquor, 
y.  Preparation  of  the  sulphur. 

a.  The  soda  waste  is  submitted  to  a  process  of  oxidation  by  the  action  of  the  air, 
and  for  this  purpose  is  placed  in  large  heaps,  where  heating  takes  place,  together 
with  the  formation  of  polysulphurets  and  subsequently  hyposulphites.  After  a  few 
weeks  the  interior  of  the  heap  assumes  a  yeUow-green  colour,  when  the  material 
is  ripe  for  lixiviation ;  the  heap  is  then  broken  up  into  large  lumps,  which  remain  for 
another  twenty-four  hours'  oxidation.  These  lumps  are  next  submitted  to  lixiviation 
with  cold  water,  and  a  concentrated  liquor  obtained.  After  this  process  follows 
another  oxidation,  effected  by  placing  the  lixiviated  residues  in  a  pit  dug  in  the  soil 
to  a  depth  of  i  metre,  and  situated  close  to  the  lixiviation  tanks ;  by  this  burying  the 
heat  generated  by  the  oxidation  suffers  less  dissipation  than  when  the  material  is  ex- 
posed on  all  sides  to  currents  of  air.  The  second  oxidation  proceeds  more  rapidly  than 
the  first  in  consequence  of  the  greater  porosity  of  the  mass,  so  that  beside  poly- 
sulphurets more  hyposulphites  are  formed.  Instead  of  effecting  the  second  oxida- 
tion by  burying,  the  waste  may  be  left  in  the  lixiviation  tanks,  and  the  oxidation 
accelerated  by  forcing  the  hot  gases  from  a  chimney  under  the  perforated  bottom  of 
the  tank ;  by  these  means  both  time  and  labour  may  be  saved,  the  oxidation  being 
complete  in  8  to  10  hours.  According  to  the  quality  of  the  alkali  waste,  this  process 
of  oxidation  may  be  repeated  three  to  four  times ;  the  gases  accompanying  the  smoke 
of  burning  fuel  are  exceedingly  well  suited  for  effecting  the  decomposition  of 
the  sulphuret  of  calcium  in  such  a  manner  as  to  cause  the  formation  of  poly- 
sulphurets and  hyposulphites.  The  liquors  resulting  from  the  first  lixiviation  con- 
tain chiefly  polysulphurets  and  hyposulphites ;  but  the  liquors  obtained  after  the 
second  and  third  oxidation  contain  essentially  hyposulphites;  all  the  liquors  are  col- 
lected in  one  reservoir. 

/3.  The  decomposition  of  the  lixiviation  liquor  by  means  of  hydrochloric  acid  is 
carried  on  in  a  closed  apparatus  of  cast-iron  or  stone,  and  is  based  upon  the  fact  that, 


i8S  CBBKICAL  TBOBSOLOaT. 

liyposnlplutea  when  treated  nitli  hydrocMorio  add.  evolve  snlidimrotia  add  gig, 
salpIiiirbeiiigprecipitated(CaSi03+2HCl  TieMs  CaCli+SO,+^HtO),  andiron 
tiiB  reaction  exerted  bj  sQlphtizoaB  add  apon  the  poljmlphimt,  which,  wMl« 
sulphur  ia  depoaited,  is  agam  converted  mto  hj'posnlpHte  of  lima — 

(3CaSj+3SO,=3CaS,Oj+  S«). 
The  liquor  is  teEted  by  titratiou  to  detennine  the  quantity  of  polyralphiuet  and  of 
hypoBolphitas  contcuned,  and  according  to  the  result  the  reddoe  is  more  or  less 
oxidised. 

The  appBTBtm  generally  employed  in  the  deoompontion  ia  shown  in  Fis.  81 ;  &  and  b 
are  the  veHgela  to  oonUia  the  hqnor ;  I  ie  the  pipe  by  which  the  liqnor  u  oonveyed  to 
k  or  fi,  regolated  by  a  piece  of  eiastia  tabiug  enteriim  at  c^  into  1,  or  q'  into  b.  t  and  t* 
are  euihenware  tnbee  by  which  the  hydrot&lorio  acid  is  introdaeed.    c  and  d  are  glaas 


tube*,  e  is  fitted  to  the  top  of  t,  and  has  a  longer  leg  dipping  into  the  fluid  at  a ;  the  revaraa 
ia  the  case  for  d,  the  short  leg  of  which  is  fitted  to  b,  while  the  longer  leg  dipa  into  the 
fluid  in  ±.  The  tap,  a,  is  oloaed  when  the  gasea  shoiild  enter  throngh  e  into  the  flnid 
oontuned  in  a,  bat  tbe  tap,  b,  is  shnt,  and  a  opened,  when  the  gase«  passing  throngh  d  are 
to  enter  the  flnid  contained  in  1.  The  excess  of  gas  Is  carried  off  by  the  tube  a.  Aa  soon 
as  the  decomposition  by  the  action  of  the  hydrochloric  acid  is  efTeoted,  steam  ia  injected 
throngh  the  valves,  vV,  to  expel  the  last  traeea  of  solphnrona  aoid  from  the  liqncr. 
The  liquor  and  finely  di^ed  solphni  are  rnn  off  at  0  and  o',  care  being  taken  to  let  Uia 
chloride  of  ealdnm  solution  ran  oD  by  removing  the  wooden  ping,  p.  In  order  to  ascertain 
whether  ^  the  anlphnrons  add  is  e^nlled,  the  woodem  taps,  k  A',  are  opened,  the  imeU 
of  the  gaahdug  a  snfBoient  indioatioD  of  itspresenoe.  The  taps,/ and/,  are  employed 
aa  test  cooks  to  ascertun  the  piogrcBa  of  the  operation,  and  aUo  to  see  whether  the 
vesBels  are  properly  filled  with  Uqnor. 

The  BiQphnr  obtained  by  this  process  ia  flne-grained,  and  mixed  with  aome  gypmim, 
ebiefly  dne  to  the  snlphnrio  acid  contained  in  the  hydrochloric  add.  The  salpbnr  and 
chloride  of  oaldom  Uqnor  are  oondaoted  by  the  spout,  0,  to  a  vessel  with  a  false  bottom, 
perforated  and  covered  with  a  flannel  doth,  throngh  which  the  Uqnor  passea,  the  sulphnr 
being  retained. 

y.  The  snlphnr  is  prepared  for  the  market  by  a  very  simple  procesa.  It  is  mixed 
with  anSdent  water  to  conslitate  a  pasto,  which  ia  pnt  into  a  east-iron  veasel,  and 
steam  at  a  pressure  of  i|  atmospheres  admitted  to  melt  the  salphnr,  the  water 
taking  np  ai^  adhering  chloride  of  caldnm  solution,  and  also  the  gypnim.  The 
molten  snlphtir  collects  in  the  bottom  of  the  vessel,  and  is  tqiped  off  into  moulds; 
the  supernatant  liquor  does  not  mix  with  the  Hulphor  owing  to  the  greater  apedfic 
weight  of  the  latter.   In  order  to  perfeotlj  Batnrate  any  &ee  add  which  might  still  be 


present  some  nilk  of  lime  is  added ;  bf  this  addition  anoQier  end  is  gidned,  vis., 
the  remoTal  of  suy  aisenic,  in  the  Gjllowing  maimer: — If  daring  the  melting  process 
u  exeeas  of  lime  be  present,  aulphnret  of  calcium  is  formed,  uid  this  enlphnret 
diwolves  an;  snlphoret  of  arsenic  which  is  thus  removed  to  the  supernatant  liquor. 
The  advantages  of  melting  and  puri^di^  the  snlphor  b;  the  above  process  are— 
the  ralphnr  meed  not  first  be  oarefnll;  washed  and  dried,  foel  is  saved,  the  sulphur 
freed  from  arsenic,  and  brought  to  the  best  state  for  pouring  into  moulds.  Figs.  85 
and  84  rqresent  the  melting  vessel ;  the  cast-iroo  cylinder,  b,  is  snrronnded  bj  a 
crought-iton  cylinder,  a.  and  the  whole  inclined  to  admit  of  the  molten  enlphnr 


Fio.  83. 


collecting  at  the  lowest  part  of  b.  The  solphnr  paste  is  kept  stirred  by  an  apparatus 
IB  gearing  at  n  with  some  motive  power.  The  paste  is  poured  into  b  at  m ;  at 
atteun  ia  introduced,  passing  at  o  into  the  inner  cylinder,  and  let  off,  when  the 
melting  is  finished  through  d  and  the  valve,  v ;  the  molten  solphor  is  run  off  at  z ; 
« is  a  safety  valve.  By  this  process  50  to  60  per  cent  of  the  snlphnr  contained  in 
the  soda  waste  is  recovered,  for  every  owt.  recovered  2  to  21  cwts.  of  hydrocblorio 
add  being  employed.  If  this  acid  were  too  expensive,  the  residues  of  chlorine 
unnofacture  might  be  used,  these  residues  coansting  mainly  of  chloride  of  manganese, 
ftee  hydrochloric  acid,  and  chloride  of  iron ;  the  first  Bl«p  would  then  be  to  free 
these  residaes  from  tbe  chloride  of  iron  by  means  of  the  lixiviated  soda  waste 
added  ia  small  ^nantitieB  at  a  time ;  sulphuretted  hydrogen  would  be  ^ven  o3^  and 
FeiC1«  reduced  to  FeCU,  the  changed  colour  indicating  the  end  of  the  reaction. 
The  diriy  grey-coloured  sulphur  from  this  reaction  should  be  bnmt  in  the  pyrites  or 
nlphur-bnzning  furnace.  The  prepared  residue  would  now  be  fit  for  employment 
IS  a  substitute  for  hydrochloric  add.  Should,  however,  some  monoenlphmet  of 
calcium  be  present  in  the  soda  waste  liquor — not  a  very  likely  occurrence — some 
hydrochloric  acid  must  be  added  before  osing  the  reddnes. 
■ubTiiMhodiiii  Among  the  many  methods  which  have  been  proposed  for  the 
^^^Dissda,  preparation  of  soda  thefollowingespeciaUydeserve  notice.  According 
to  Eopp's  methods  of  soda  manofikctore  sulphate  of  soda,  oxide  of  iron,  and  carbon 
are  snLelted  together  in  an  ordinary  soda  fomaee: — 


x88  CHEMICAL   TECHNOLOQT. 


The  crnde  soda  absorbs  from  the  air  water,  oxygen,  and  carbonic  acid,  becoming 
converted  into  carbonate  of  soda  and  an  insoluble  residue  of  sulphuret  of  iron 
containing  sodium,  Fe^Na^Sa : — 


The  lixiyiation  is  effected  with  warm  water  at  30°  to  40°;  the  liquors  yield  after 
twenty-four  to  twenty-eight  hours,  without  any  previous  concentration,  a  large  crop 
of  beautifully  crystallised  soda.  The  insoluble  residue  of  the  lixiviation  is  dried 
and  roasted  to  produce  sulphurous  acid,  employed  in  the  manufacture  of  sulphuric 
add,  used  in  its  turn  for  the  conversion  of  common  salt  into  sulphate  of  soda.  Thus 
the  cycle  of  changes  in  the  sulphur  is  complete: — 


f^if'^s,!  y,^. 


faFcaO, 
Na^S04 
USOa 


The  sulphate  of  soda  present  in  the  calcined  residue  is  removed  by  liziviation. 

It  cannot  be  denied  that  this  process  presents  certain  advantages. 

Diwd  ooDTenion  of  "^  P^*°  ^^'  *^®  direct  converBion  of  common  salt  into  soda  has  long 
Common  Salt  been  sought,  but  hitherto  not  suocessfuly  carried  into  practice.  When 
into  Soda.  ^  concentrated  solution  of  bicarbonate  of  ammonia  is  mixed  ^th 
strong  brine,  or,  better  still,  the  pulverised  bicarbonate  stirred  through  a  concentrated 
solution  of  salt,  and  this  mixture  left  to  stand,  the  result  will  be  that  after  some  hours 
bicarbonate  of  soda  will  be  deposited  in  crystalline  state,  the  supernatant  liquid  being  a 
solution  of  sal-ammoniac.  As  bicarbonate  of  soda  on  being  gradually  heated  to  redness 
loses  a  portion  of  its  carbonic  acid,  and  is  converted  into  monocarbonate  of  soda,  this 
process  has  been  suggested  as  suited  for  the  manufacture  of  soda,  'and  has  been 
tried  by  Dyar  and  Hemming  in  England.  SohloBsing  and  Bolland  in  1855  took  out  a 
patent  for  some  improvements  on  this  method  of  soda  manufacture,  of  which  the 
foUowing  is  an  outline: — The  first  operation  consists  in  the  action  of  ammonia  and 
carbonic  acid  upon  a  concentrated  salt  solution ;  to  xoo  parts  of  water  30  to  33  parts  of 
common  salt,  8i  to  10  of  ammonia,  and  carbonic  acid  in  excess  are  taken.  The  next 
step  is  the  separation  of  the  bicarbonate  of  soda,  which  is  effected  by  a  centrifugal 
machine.  The  third  stage  is  the  calcination  of  the  bicarbonate  of  soda  in  cylindrical 
iron  vessels,  the  carbonic  acid  gas  given  off  being  collected.  The  fourth  and  fifth 
operations  aim  at  the  recovery  of  the  carbonic  add  and  ammonia  from  the  liquid  drained 
from  the  bicarbonate  of  soda  while  in  the  centrifugal  machine.  The  liquid  is  heated  in 
a  boiler,  the  result  being  the  escape  of  the  ammonia  and  carbonic  add,  which  are  con- 
ducted to  a  cylinder  filled  with  coke,  through  which  a  cold  aqueous  solution  of  car- 
bonate of  ammonia  trickles,  causing  the  condensation  of  the  ammonia,  the  carbonie 
acid  escaping  into  a  gasholder.  Next,  milk  of  lime  is  added  to  the  liquid,  and  the  heating 
being  contiaued,  all  the  ammonia  is  expelled.  Lastiy,  the  dear  supernatant  liquid  is 
evaporated  to  recover  the  common  salt.  According  to  Heeren's  researches  on  this  subject, 
this  process  is  more  suited  for  the  preparation  of  bicarbonate  of  soda ;  it  is  stated,  how- 
ever, that  the  researches  of  Marguerite  and  Bourdiyal  have  resulted  in  improvements  on 
this  method  which  may  in  future  lead  to  its  being  advantageously  adopted  in  some 
localities  for  the  manufacture  of  soda. 

Soto  from  cryouta.      Cryolite  (AlaFl€,6NaFl)  is  largely  employed  for  the  manufacture 
of  soda  by  decomposing  the  mineral  by  ignition  with  lime: — 

I  mol.  of  Cryolite )  (6  mols.  of  Fluoride  of  caldum. 

6  mols.  of  lime    J    -^         1 1  mol.  of  ALuminate  of  soda. 

This  last  compound  being  soluble  in  water  is  decomposed  by  carbonic  add,  and 
alumina  precipitated,  soda  remaining  in  solution.     100  kilos,  of  cryolite  yield — 


SODA.  iSg 

Dry  caustic  soda    44   kilos. 

Calcined  soda 75      „ 

Ciystallised  carbonate  of  soda    ...  203      „ 
Bicarbonate  of  soda     ii9'5    n 

Banxite  (see  nnder  Alumina),  on  ignition  with  snlphate  of  soda  and  carbonaceous 
matter,  yields  in  a  similar  manner  soda  and  alumina. 

BodafromNitnie      ^7  ^^^  oonversion  of  nitrate  of  soda  into  nitrate  oj  potassa  by  the  aid 
of  Soda.        of  carbonate  of  potassa  (see  under  Saltpetre)  not  inconsiderable  quantities 
of  ft  strong  solution  of  soda  are  obtained ;  the  sodium  of  the  sodium  nitrate  may  be 
converted  by  any  of  the  following  means  into  soda  or  caustio  soda: — 

a.  By  igniting  nitrate  of  soda  with  carbonaceous  matter. 

h.  By  igniting  nitrate  of  soda  with  silica,  and  decomposing  the  silicate  of  sodium 

by  carbonic  acid. 
e.  By  igniting  nitrate  of  soda  with  manganese. 
d.  By  the  decomposition  of  nitrate  of  soda. 
a.  By  means  of  carbonate  of  potassa;  or, 
p.  By  means  of  caustic  potassa. 
In  the  latter  case,  besides  nitrate  of  potassa,  caustic  soda  is  formed. 

cmtiesoda.  This  substance,  sodium  hydroxide  (NaHO),  is  met  with  in  commerco 
as  a  highly  concentrated  solution,  or  more  frequently  as  a  solid  mass,  fused  hydrate 
of  soda,  consisting  in  loo  parts  of  77*5  parts  of  soda  and  22*5  parts  water.  For 
many  years  a  moderately  strong  solution  of  caustic  soda  was  prepared  by  treating 
a  carbonate  of  soda  solution  with  caustic  lime,  but  Dale  was  the  first  to  use  this 
solution  instead  of  water  in  his  boilers,  and  thus  concentrate  the  lye  to  a  sp.  gr.  of 
124  to  1*25,  after  which  the  ley  was  further  evaporated  in  cast-iron  cauldrons  to  a 
sp.  gr.  of  I '9,  at  which  point  it  solidifies  on  cooling. 

Instead  of  using  caustic  lime,  caustic  soda  is  now  directly  produced  by  simply 
increasing  the  quantity  of  small  coal  added  to  the  mixture  of  sulphate  and  chalk, 
the  crude  soda  being  at  once  lixiviated  with  water  at  50°.  After  the  liquor  has 
cleared,  it  is  rapidly  concentrated  to  1*5  sp.  gr.,  when  carbonate,  sulphate,  and 
chloride  of  sodium  are  deposited,  the  liquor  assuming  a  brick-red  colour,  due  to  a 
peculiar  compound  of  double  sulphuret  of  sodium  and  sulphuret  of  iron.  The  ley 
is  next  strongly  heated  in  large  cast-iron  cauldrons,  and  there  is  added  3  to  4  kilos, 
cf  Chili-saltpetre  for  every  100  kilos,  of  caustic  soda  required;  by  this  operation  the 
nitrate  of  soda  reacts  upon  the  sulphuret  of  sodium  and  cyanide  of  sodium  present, 
causing  an  abundant  evolution  of  ammonia  and  nitrogen.  This  somewhat  com- 
plicated process  may  be  elucidated  by  either  of  the  two  following  formulsB : — 
a.  2Na2S+2NaN03+i3laO=2NaaS04+2NaHO+2NH3. 
p.  5NaaS+8NaN03+4HaO=5Na^S04H-8NaHO+8N. 

According  to  Pauli,  the  kind  of  reaction  depends  chiefly  on  the  temperature  of  the 
heated  ley ;  at  155°  ammonia  is  largely  evolved ;  above  155°  and  with  greater  con- 
centration of  the  ley  nitrogen  is  given  ofif.  As  for  every  ton  of  caustic  soda  produced 
this  process  absorbs  075  to  i  cwt.  of  nitrate  of  soda,  the  ley  is  in  some  works  oxidised 
by  filtering  it  through  a  colunm  of  coke,  or  by  forcing  air  through  it  in  minute  jets. 

HewifttiuKUof  ouutie  Among  these  is  the  decomposition  of  sulphate  of  soda  by  means  of 
8od«  MAnaiMtiin.  oaustlc  baryta,  a  rather  exi)en8ive  process,  baryta  white  or  permanent 
white  being  a  by-product.  Ungerer  uses  caustic  strontia  instead  of  caustio  baryta.  Caustic 
foda  may  be  prepared  by  treating  cryolite  for  sulphate  of  alumina  (see  Alum),  or  by 
igniting  nitrate  of  soda  with  manganese ;  or  by  decomposing  silico-fluoride  of  sodium 
or  fluoride  of  sodium  with  caustic  lime.  In  England  very  pure  caustic  soda  is  prepared 
from  sodium  by  carefully  oxidising  the  metal  with  pure  water  in  bright  iron  or  silver 
vessels. 


igo  CHEMICAL  TECHNOLOGY. 

According  to  Daiton's  researches  :*— 

A  oauBtic  soda  liquor  of  the  Contains  percentage  of  canstiff 

undermentioned  sp.  gr.  soda  (NaHO.) 

2'oo  77*8 

185  636 

172  53*8 

X'63  46-6 

i'47  340 

144  310 

1*40  29*0 

1*36  26*0 

i'32  230 

I29  19*0 

1*23  160 

i'i8  13*0 

112  90 

106  4*7 

Canstio  soda  is  largely  used  in  soap  making,  paraffin  and  petroleum  refining,  and  thf 
preparation  of  silioato  of  soda  and  artificial  stone  by  Bansome  and  Sims's  method. 

BicaiboiiAto  of  Soda.      This  substancc,  NaHGOs,  called  erroneously  carbonate  of  soda 

in  many  of  the  London  shops,  consists  in  100  parts  of  369  soda,  1073  water,  and 

52*37  carbonic  acid,  and  is  prepared  by  passing  a  current  of  washed  carbonic  acid 

gas  through  a  solution  of  carbonate  of  soda.    If  the  solution  is  concentrated  the 

bicarbonate  is  deposited  as  a  powder,  but  from  a  dilute  solution  large  ciystals  are 

obtained.    It  is,  however,  more  advantageous  to  cause  the  carbonic  acid  to  act 

upon  crystallised  and  effloresced  carbonate  of  soda ;  a  suitable  mixture  consists  of 

I  part  of  crystallised  and  4  parts  of  effloresced  carbonate  of  soda.    The  sources  of 

carbonic  acid  may  differ,  but  in  this  country  the  gas  is  generally  prepared  by  the 

action  of  weak  hydrochloric  acid  upon  chalk  or  limestone;  of  course  the  carbonic 

acid  evolTed  during  the  fermentation  of  wort,  or  must,  may  be  applied. 

When  carbonic  acts  upon  crystallised  carbonate  of  soda  there  is  first  formed 

sesquicarbonate  of  soda ;  the  9  equivalents  of  water  which  are  displaced  from  each 

equivalent  of  crystallised  carbonate  of  soda  are  collected  in  a  reservoir,  and  this 

liquid  having  of  course  dissolved  a  portion  of  the  bicarbonate  is  employed  at  a 

future  operation  for  moistening  the  crystallised  soda  carbonate.    The  bicarbonate 

is  dried  at  40^  in  a  current  of  carbonic  acid  gas.    The  preparation  of  the  bicarbonate 

by  withdrawing  from  the  monocarbonate  by  the  aid  of  an  acid  one-half  of  the  soda 

it  contains  has  been  suggested;  for  this  purpose  28 i  parts  of  crystallised  sodic 

carbonate  are  dissolved  in  twice  their  weight  of  warm  water,  and  4^,  parts  of 

sulphuric  acid  added,  care  being  taken  not  to  move  the  vessel.    Being  left  to  stand 

for  several  days  the  bicarbonate  is  deposited  in  crystals.      It   has   been  seen 

that  when  a  solution  of  common  salt  is  treated  with  bicarbonate  of  ammonia,  the 

result  is  the  formation  of  bicarbonate  of  soda  and  sal-ammoniac,  which  remains  ib 

solution.    Bicarbonate  of  soda  crystallises  in  monoclinical,  tabular  crystals ;  has  a 

weak  alkaline  reaction ;  loses  its  carbonic  acid  at  70°,  and  becomes  monocarbonate 

of  soda ;  and  by  exposure  to  dry  air  is  gradually  converted  into  sesquicarbonate. 

The  bicarbonate  is  employed  generally  in  the  preparation  of  effervescing  drinks,  and 


IODISE  AND  BBOMDIS.  igi 

«ith  fardxochloric  or  phosphoric  sdd  in  makiiig  bread  withont  fementatioiL  Iho 
farther  oacfl  of  this  scdt  are — the  precipitation  of  the  alumins  from  Bodinm-alnminikta 
solntiotia,  for  the  preparation  of  baths,  for  gilding  and  platinising,  and  for  puri^ring 
and  cletmaing  silk  and  wool,  i  grm.  of  the  bicarbonate  fields,  when  completel7 
decomposed  bj  an  acid,  about  270  c.c.  of  carbODic  add  gaa  =  0-51  grm.  by  weight. 

The  total  prodoction  of  Boda  in  Europe  amoonted  in  1870  to  11,850,000  cwts.,  of 
which  Qreat  Britain  produced  6,350,000  cwts. 

PnXFAnATION   OF  lODINB  AND  BbOHINE. 

PiumManai  loUu.  This  element  occnrs  in  sea-water,  from  which  it  is  taken  ap  by 
Tarions  sea-weeds ;  from  these  sea-weeds  iodine  is  derived  indnstTiallj.  Chili-salt- 
petre and  some  aaline  springB  (for  instance,  the  Solza,  Sodiem  Weimar)  contain 
iodine  in  conaiderable  quantity.  Although  iodine  is  fonnd  in  the  mineral  kingdom 
(for  instance,  in  the  iodide  of  lead  and  phoephorites  of  Amberg,  Bavaria,  and  Diez  on 
the  I^hn),  it  ia  not  in  this  case  indnstriallj  important.  The  chief  seat  of  iodine 
mannfactnre  is  at  Glasgow,  where  there  are  twelve  bctoriea ;  there  are  two  iodine 
fiKtoriea  in  Ireland,  and  two  at  Brest,  in  France. 

rnpudkn  bm  ittf.  In  Order  to  obtain  iodine  from  sea-weeds,  the  latter  are  first  con- 
Terted  into  kelp,  that  is  to  eay,  they  are  incinerated,  the  prodnet  broken  to  pieoes 
and  lixiviated  with  water,  leaving  an  insoluble  residne  of  30  to  40  per  cent,  and 
yielding  to  the  liquid  60  to  70  per  cent.  This  solntion,  having  a  ftp.  gt.  at 
I'lS  to  i'2o,  contains  chlorides,  sulphates,  and  otrbonates  of  alkalies,  snlphuret 
of  potasainm,  iodide  of  potaaainm,  and  hyposulphites  of  alkalies ;  by  evaporating 
ind  cooling  the  lienor,  the  sulphate  of  potassa  and  chlorides  of  potassiom  and 
sodium  are  removed.  To  the  remaining  mother-liquor,  previously  poured  into 
shallew  open  vessels,  dilute  sulphuric  add  is  added,  the  result  being,  that  while  a 
strong  evolution  of  gases,  solphoretted  hydrogen,  and  carbonic  add  takes  place, 
there  is  formed  a  thick  sewn  and  a  deposit  of  snlphur  at  the  bottom  of  the  vessel; 
the  sulphur  when  washed  and  dried  is  sold.  When  the  evolution  of  gas  has 
completely  ceased,  more  sulphuric  add  ia  added,  and,  according  to  Wolloston's 
nelhod,  the  required  quantity  of  manganese ;  this  mixtnre  is  poured  into  a  large 
leaden  distilling  apparatus,  c.  Fig  85.    By  this  means  the  iodine  is  set  free,  carried 

Fie.  S5. 


'*'''  in  the  state  of  vapour  to  the  receivers,  b,  b',  b",  and  condensed  as  a  aditl 
^fTStalline  mass.  In  I^terson's  large  iodine  works  at  Glasgow  this  operation  & 
buried  on  in  a  cast-iron  hemispherical  vessel  of  13  metres  diameter,  the  cover 


rga  OaSMlCAL  TBCHHOLOQT. 

being  a  leaden  dome,  to  which  are  fitted  two  earthenware  etinheads,  connected 
by  meanfi  of  porcelain  tubing  with  two  earthenware  receiTere.  Fig.  85,  aueh 
COiiBigting  of  4  to  5  parte.  At  Cherboorg.  iodine  is  obtained,  according  to  Batraat'H 
plan,  by  passing  clilorine  gas  into  the  mother-li(|nor;  by  this  plan  the  iodine  ie  sepa- 
rated &om  the  iodide  of  magnesimn,  the  latter  taking  np  chlorine  ingtead— 

(MgI.+Cl,=  MgCU+I,). 
A  more  recent  method,  by  which  all  the  iodine  present  in  the  mother-liquor  is  ebttuned, 
comdatB  in  distilling  the  liquor  with  chloride  of  iron — 

(2NaI+Fc,Clfi=al+2NaCl+2FeCl,).. ' 
Ab  iodine  ia  only  very  elightly  soluble  in  water,  i  part  of  iodine  requiring  55Z4  puis 
of  water  at  10°  to  12°  for  its  solution,  that  ia,  i  grain  of  iodine  to  izonncea  of  water, 
it  is  carried  over  with  the  steam  and  deposited  at  the  bottom  of  the  receiver  in  the 
form  of  a  black  powder.  .When  it  dine  ia  prepared  by  the  aid  of  chlorine,  the 
quantity  of  gas  should  be  exactly  aufGcient  to  decompose  the  iodide  of  magnesiaiii, 
for  if  the  quantity  of  chlorine  be  too  email  no  iodine  is  separated,  and  if  too  largB 
chloride  of  iodine  is  formed  and  free  bromine,  both  of  which  being  volatile  escape. 
The  iodine  when  removed  from  the  reoeivers  is  drained  on  porons  bricks  or  tiles, 
and  dried  between  folds  of  blottu^-paper.  It  need  hardly  be  said  that  the  iodine 
Fio.  86.  should  not  come  in  contact  with  a 

metallic  snr&ce.  The  iodine  thus 
obtained  has  to  be  purified  by  sub- 
limation, an  operation  carried  on  in 
the  apparatos  represented  in  Fig.  86, 
consisting  of  stoneware  reCorta,  cc, 
placed  in  the  aand-bath,  b,  heated 
as  ehown  in  the  vroodciit>  Each  of 
these'  retorts  is  filled  with  upwards 
of  40  lbs.  of  crude  iodine,  ind 
entirely  surrounded  by  sand  in  order 
to  prevent  the  sublimation  of  any 
iodine  in  the  necks  of  the  retorts. 
These  are  then  connected  with  the 
a  which  the  cTyatalline  iodine  ia  deposited,  the  tubes,  a  ft, 
a  b,  being  for  the  pnrpoae  of  carrying  off  the  watery  vapour.  1  ton  of  kelp  yields  00 
an  average  4*07  kilos,  of  iodine. 

siutDFiiuidHoiidi.  In  ,862  Mr.  Stanford  Buggasted  that  the  Bea-weeda  shonld  not 

taJSc^bSSdSi.iiSi'  be  calcined,  bat  aimplj  distilled  with  Buperheated  steam,  so  »  to 
prevent  volatiliBation  of  the  iodine,  while  the  tarry  and  gOBeous  produots  ahonld  be  sep^ 
rately  ntilised.  This  clu-boDiBed  aea-weed,  when  aaite  oold,  ia  liijviated  with  water,  tui  i 
the  solution  treated  for  iodine  and  chloride  of  potasaiam  (see  p.  130].  The  yolalde  pt^ 
dnctB  of  the  diatillatjon  are  illununatiDg  gas,  acetic  acid,  ammonia,  mmeral  oil,  MM 
paraffin,  M.  Morido,  of  Nantes,  has  modified  this  process;  be  prepares  by  evspoiaUng 
the  liquor  from  the  lisiviation  oi  the  carbonised  sea- weed,  aulpbate  and  cblonde  01 
potassium,  Ac  The  niother-Uquor  ia  treated  with  chlorine  or  hj-ponitrio  acid,  and  than 
with  benzine,  in  an  apparatos  so  arranged  that  the  benzine  directlj  gives  up  the  "™?|J* 
has  dissolved  to  soda  or  potassa,  the  benzine  thns  acting  as  a  coiitmuons  aolvent.  11" 
liquor  containing  iodine  is  treated  for  the  aepacatiou  of  iodins  in  the  naual  manner. 
Pni>«tioDDM»iin.t,om  Crude  Cbili-aaltpetre  contains  on  an  avernHO  0-059  *" J"'" 
Chm-s.ii».ir».  per  cent   of  iodine.      According   to   Nollner,   tho  iodine  oo«oi» 

from  the  formation  of  the  ChiK. saltpetre  in  tiie  piesonce  of  deoajing  sea.«e«i» 
from  shallow,  staKnant,  inland  seas,  which  have  dried  np,  Tlie  mother.LiiuoK, 
left  after  the  refining  of  the  salt,  or  from  its  UMi  for  the  conversion  of  cMonde  m 
potttHsinm  into  nitrate  of  potassa,  and  containing  o-i8  to  o'36  per  cent  of  lodme,  are 


IODINE  AND  BROMINE,  193 

treated  with  snlphtiroaB  acid  until  the  iodine  separated  begins  to  re-dissolye.  More 
recently  nitrons  acid  has  been  nsed  instead  of  snlpliurons  aoid.  The  iodine  thus  obtained  is 
refined  bj  sublimation,  while  that  remaining  in  the  residual  saline  matter  is  removed  ty  a 
farther  treatment  with  chlorine. 

PropddM  aiid  uu«  of  Iodine.  Iodine  (1=127;  Sp.  gr.=4-94)  is  a  black-grey  coloured 
crystalline  substance,  with  a  metallic  appearance  not  unlike  graphite.  On  being 
heated  iodine  is  converted  into  vapours  which,  according  to  Stas,  when  concentrated 
exhibit  .a  blue  colour,  and  a  violet  in  a  more  dilute  state.  Iodine  fuses  at  115°, 
and  boils  above  200°.  It  is  somewhat  soluble  in  water,  readily  so  in  alcohol, 
ether,  hydriodic  acid,  iodide  of  potassium  solution,  sulphide  of  carbon,  chloroform, 
benzol,  aqueous  solution  of  sulphurous  acid,  and  solution  of  hyposulphite  of  soda. 
A  solution  of  iodine  imparts  a  violet  colour  to  starch.  Adulteration  of  iodine 
with  either  pulverised  charcoal  or  graphite  may  be  at  once  detected  by  treating 
a  sample  with  alcohol  or  a  solution  of  hjrpdl^Jphite  of  soda,  in  ea6h  of  which 
the  iodine,  if  pure,  ought  to  dissolve  completely,  leaving  no  residue  on 
sublimation.  Sometimes  the  weight  of  iodine  is  fraudulently  increased  by  the 
addition  of  water.  Iodine  is  largely  nsed  in  photography  combined  as  iodide 
of  potassium ;  for  the  preparation  of  other  iodine  compounds,  for  instance,  iodide 
of  mercury ;  also  in  the  preparation  of  some  of  the  tar  colours,  iodine  violet, 
iodine  green,  and  cyanine  blue,  the  latter  a  compound  from  iodine  and  lepidin,  a  vola- 
tile base.  The  total  production  of  iodine  in  Europe  and  Chili  amounted  in  1869  to 
3453  cwts.,  more  than  half,  or  1829  cwts.,  being  produced  in  Scotland  and  Ireland. 

Pdeptzation  of  Bromine.  The  element  kuowu  as  bromine  occurs  to  a  small  extent  in  sea- 
water,  a  litre  containing  0061  grms.  bromine.  The  mother-liquors,  however,  ,of 
many  salt  works  (for  instance,  those  at  Schonebeck,  near  Magdeburg,  and  the 
hquors  left  from  many  of  the  Stassfurt  salts)  are  so  rich  in  bromine,  that  its  prepara- 
tion is  worth  the  cost  and  trouble.  In  order  to  avoid  as  much  as  possible  the 
admixture  of  chlorine,  there  is  added  to  the  mother-liquor  dilute  sulphuric  acid ; 
this  mixture  is  heated  to  120°,  and  tlie  hydrochloric  acid  set  free  by  the  sulphuric 
uid  evolved,  while  the  less  volatile  hydrobromic  acid  is  left  in  the  liquor,  from 
which,  on  cooling,  sulphates  are  deposited.  The  decanted  liquor  is  distilled  after  the 
addition  of  more  sulphuric  acid  and  some  manganese.  Two  Woulfe's  bottles  serve 
as  receivers ;  in  the  first  are  condensed  water,  bromine,  bromoform,  and  bromide  of 
carbon,  while  any  bromine  vapours  which  pass  over  to  the  second  bottle  are 
absorbed  in'the  caustic  soda  it  contains.  The  ley  contained  in  this  vessel  is  evapo- 
lated  to  dryness,  the  residue  ignited  in  order  to  convert  bromate  of  soda  into 
bromide  of  sodium ;  the  saline  mass  being  then  mixed  with  sulphuric  acid  and  man- 
ganese and  distilled,  yields  pure  bromine,  best  preserved  under  strong  sulphuric  acid. 

According  to  Leisler's  patent  (1866)  bromine  is  separated  from  the  mother-Uquor  left  by 
operations  with  kainite,  or  camallite,  or  from  the  water  of  the  Dead  Sea)  containing, 
aeeording  to  Lartet^s  analysis,  in  i  litre,  taken  from  a  depth  of  300  metres,  7*093 
gnns.  =o*7  per  cent  of  bromine)  by  adding  bichromate  of  potassa  and  an  acid ;  heat  being 
applied,  the  bromine  is  volatilised  and  collected  in  a  condenser  filled  with  metallic  iron. 
From  the  bromide  of  iron  thus  formed,  either  the  element  itself  or  any  of  its  compounds 
ipay  be  obtained.  The  apparatus  employed  by  this  patentee  is  a  distilling  apparatus ;  the 
add  is  hydrochloric  diluted  with  four  times  its  bulk  of  water ;  to  100  parts  by  bulk 
of  the  bromine  fluid,  i  part  by  bulk  of  acid  is  added.  The  bichromate  is  added  in  a 
^turated  aqueous  solution.  The  bromide  of  iron  formed  becomes  dissolved  by  the 
aqueous  vapour,  and  condensed  in  the  receiver.  Bromine  is  the  only  metalloid 
fluid^  at  ordinary  temperature.  Seen  in  thick  layers  its  colour  is  a  deep  brown-red, 
hut  in  thin  layers  a  hyadnth-red ;  its  odour  is  strong  and  similar  to  that  of  chlorine 
gas.  The  aqueous  solution  of  bromine  —  i  part  requiring  30  parts  of  water  for 
its  solution — is  of    a  yellow-red  colour  when   freshly  made,  but  like  chlorine- water 


194  CHEMICAL  TECUlfOLOGY, 

does  not  keep  well,  and  is  soon  converted,  especially  if  exposed  to  light,  into  a  colourless 
solution  of  weak  hydrobromio  acid.  loo  parts  of  bromine  water  contain  at  15^,3*226  parts 
of  bromine;  bromine  forms  with  water  a  solid  hydrate  at  0°.  It  is  readily  solable 
in  ether,  alcohol,  chloroform,  and  hydrobromic  acid.  It  yields  with  an  aqueons  solution 
of  sulphurous  acid  hydrobromic  acid — 

{S02+H20+2Br=S03+2BrH). 

Bromine  boils  at  63°,  giving  off  deep  red  vapours;  at  —7*3°  it  becomes  a  lead-grey 
coloured,  foliated,  graphite-like  mass.  Bromine  acts  upon  colouring  matters,  dyes,  and  the 
colours  of  flowers  as  does  chlorine,  while  organic  matters,  especially  those  of  animal 
origin,  are  coloured  brown.  It  is  used  in  combination  as  bromides  of  potassium, 
ammonium,  cadmium,  and  hypobromite  of  potassa,  for  photographic  purposes  and  io 
medicine;  and  further  as  bromides  of  ethyl,  amyl,  and  methyl,  for  the  preparation 
of  some  of  the  tar  colours,  Hofmann's  blue,  and  the  preparation  of  alizarine  from 
anthracen.  Bromine  is  also  used  as  a  disinfectant,  and,  according  to  Beichardt,  may  with 
advantage  be  substituted  for  chlorine  in  the  preparation  of  ferricyanide  of  potassium. 
Since  the  year  1866  bromine  has  been  manufactured  at  Stassfurt,  now  the  chief  bromine 
producing  locality.  The  total  annual  production  of  bromine  in  Europe  and  America 
amounts  to  11 50  cwts.,  of  which  400  cwts.  are  obtained  at  Stassfurt  and  300  cwts. 
in  Scotland. 

SULPHTTR. 

suiphmr.  .  In  Combination  witli  coals,  rock-salt,  and  ii'on,  sulphur  is  tlie  mainstay  of 
present  industrial  chemistry.  It  is  often  fonnd  native  between  gypsum,  clay,  and  marl  in 
tertiary  deposits,  more  rarely  in  veins  between  crystalline  rocks  of  the  schistose  and 
metamorphic  varieties,  and  not  unfrequently  in  coal  and  lignite  deposits.  Sulphur 
is  an  almost  constant  product  of  active  volcanoes,  being  sublimed  and  deposited  on 
surrounding  objects.  The  largest  sulphur  deposits  in  Europe  are  met  with  in 
Sicily.  It  is  also  found  in  Egypt  on  the  banks  of  the  Eed  Sea,  especially  near  Suez ; 
at  Corfu,  one  of  the  Ionian  Islands ;  near  the  Clear  or  Borax  Lake  in  California ;  on 
the  slopes  of  the  Popocatepetl,  in  the  province  of  Puebla,  Mexico,  where  yearly 
2000  cwts.  of  sulphur  are  collected.  Frequently,  sulphur  is  deposited  from  the  sul- 
phuretted waters  of  mineral  springs ;  for  instance,  the  waters  of  Aix-la-Chapelle. 
Sulphur  occurs  in  combination  with  metals,  as  in  iron  pyrites,  FeS2,  with  533 
per  cent  of  sulphur ;  this  mineral  often  contains  thallium.  The  quantity  of  sulphur 
contained  in  the  following  minerals  is,  from  100  parts: — ^Iron  pyrites  (FeSj),  53*3; 
copper  pyrites  (Fe2Cu6S6),  349  ;  magnetic  iron  pyrites, mundic  (FcySg,  or, according 
to  Th.  Petersen,  FeS),  395  ;  galena  (PbS),  13*45  J  hlack-jack  (ZnS),  330;  Meserite 
(MgS04-|-H20),  23-5  ;  anhydrite  (CaS04),  235  ;  gypsum  {CaS04-i-2HaO),  186 ;  gas 
coal,  10.  According  to  Dr.  Wagner,  the  quantity  of  sulphur  present  in  the  coals 
used  in  the  London  gasworks  annually,  amounts  to  200,000  cwts.,  equal  to  612,500 
cwts.  of  sulphuric  aoid. 

'Although  sulphur  occurs  native  as  sulphuretted  hydrogen  and  sulphurous  acid, 
especially  near  active  volcanoes,  this  is  not  of  much  industrial  use.  The  regenera- 
tion of  sulphur  from  soda- waste  is  decidedly  one  of  the  most  important  items  in  the 
sulphur  industiy. 

*°*^*^^'Sw"**°*°*  According  to  the  comparative  richness  of  the  raw  material,  the 
sulphur  is  separated  from  its  concomitant  impurities  by  melting  or  by  distil- 
lation. When  the  raw  material  is  rather  rich  it  is  simply  submitted  to  a  process  of 
melting  in  a  cast-iron  cauldron,  b  (Fig.  87),  heated  by  a  gentle  coal  or  charcoal  fire 
placed  in  a.  During  the  melting  the  mass  is  stirred  with  an  iron  rod,  and  as  soon 
as  the  sulphur  has  become  quite  fluid,  the  gangue  and  small  stones  are  removed  by 
means  of  the  ladle,  c.  This  done,  the  sulphur  is  poured  into  a  wooden  or  sheet-iron 
vessel,  D,  thoroughly  wetted  with  water  to  prevent  the  adhesion  of  the  sulphur  to  the 


SULPHUR. 


"95 


sides.  The  aDlphnr  when  cold  and  solid  is  broken  into  large  lumps  and  packed  in- 
casks  ready  for  the  market.  The  stones  and  gangue  are  placed  in  heaps,  or  more 
coznmonly  introduced  into  a  shaft  furnace  (Fig,  88),  and,  a  portion  of  the  snlphur 
being  sacrificed  U)  serve  as  fuel,  the  greater  part  of  the  element  is  eliminated  by  the 
following  plan : — A  small  portion  of  the  crude  sulphur  is  ignited  in  the  lower  part  of 
the  furnace,  and  the  shaft,  f..  filled  with  large  lumps  of  the  earthy  sulphur  ore.  &om 


The 


which,  rapidly  ignited  superficiallj,  the  molten  sulphur  tncklcs  donn 
openings,///  give  access  to  the  air  required  for  the  combustion  of  a  portion  of  the 
snlphur.  The  sulphur  collects  in  the  lower  part  of  the  furnace  and  is  tapped  off 
by  the  channel  g  into  wooden  or  sheet-iron  vessels  A  for  bftter  method  of  pre- 
paring anlphnr  from  the  ore  is  by  distillation,  the  apparatus  liemg  tliat  exhibited  in 
Pig.  89.     A  is  a  cast-iron  cauldron,  which  is  filled  with  raw  luatennl,  and  rovered 


Fio.  89. 


with  a  tightly-iitting  iron  hd  Tht,  ilui «  aro  so  coustructod  as  to  heat  llie  vessel  11 
geotly.  The  vapours  of  sulphur  are  carried  by  the  tube  m  into  the  condenser,  n. 
whence  the  molten  snlphurruns  off  into  the  vessel  k.  The  previously  warmed  ore  is 
readily  admitted  to  a  by  lifting  the  damper,  p.  From  a  suggestion  made  by  E.  and 
P.  Thomas,  sulphur  is  obtained  &om  its  ores  by  the  a|)plication  of  superheated 
*teamat  130°,  this  mode  of  working  being  the  same  as  that  employed  by  M.  Schaffner 
fiir  purifying  the  sulphur  recovered  from  soda-waste.  In  passing,  it  may  be  men- 
tioned that  very  recently  the  estraction  of  sulphur  from  its  ores  has  been  attempted 


196  CHEMICAL  TECHNOLOQY. 

by  the  aidof  Bolveutg,nz.,Eulphideof  carboD  aud  a  lijjlit  coal-tar  oil  of  sp.  gr.  =o'SS. 
M.  Mine's  analyses  of  several  samples  of  crude  Sicilian  sulphur  obtained  by  smelting 


Sulphur  (Bolnble  in  CSi)  ..     ..  go-i  961 

Corbouaceoas  matter        ..     ..  r'o  05 

Sulphor  {iDBolnbla  in CSi)       ..  x-o  — 

SiliceoDe  atmd 3'3  l'5 

Limestone (aometimra  creleslin)  4'i  1*8 

The  bottom  portion  of  (be  blocks  of  crude  sulphiu 
foreign  substances.    The  crude  sulphur  is  refined  in 
of  esjtby  matter;  and  after  this  process  it  is  brought  into  commerce  i 
rolls  or  in  powder. 

Limj-a  BiOniif  AppumiDi.  Tlic  apparatus  for  refining  sulpliur,  invented  by  Michel  and 
improved  by  Lamy,  at  MarseilleB,  consiata  mainly  of  two  cast-iron  cjlindera,  b 
(Fi<;.90l.  nsed  aA  retorts,  and  a  large  brick -work  condpnsing-room,  a.    The  cylinder  s 


3- 
913 

4- 
900 

s 

88 

7 

07 

3'3 

2'8 

5 

7 
5 

1-5 

2 

S 

0-3 

often 

contains 

25  per  cent  of 

order 

to  pJiTti' 

nate  all  traces 

into 

Mmmerce  in 

sticks  or 

is  directly  beat«d  by  the  fire,  the  smoke  of  trhicli  is  carried  off  by  tbe  chimnry,  E. 
The  flues,  c,  however,  Eurroundn,  where  the  crude  sulphur  nndergoesa  partial  refining' 
and  wlie&ce  it  flows  by  the  tobe  f  into  the  cylinder  b.    The  cylinder  b  is  in  commn- 


SULPHUR,  197 

nication  with  the  vaulted  room,  o.  At  the  bottom  of  this  room  is  placed  a  cast-iron 
plate  in  which  a  hole  is  bored,  and  fitted  with  a  conical  plug,  j,  connected  with  a  rod, 
H,  80  as  to  admit  of  being  shut  and  opened  for  the  purpose  of  tapping  sulphur  into 
the  cauldron,  l,  whence  it  is  ladled  over  into  the  moulds  placed  in  m.  n  is  a  box  for 
the  roll  sulphur  when  it  has  become  cold. 

BoDSBiiihiir.  If  it  is  iutended  to  prepare  roll-sulphur,  the  mode  of  proceeding  is  the 
following: — ^Each  of  the  cylinders  is  filled  with  crude  sulphur,  the  lids  firmly 
fastened,  and  the  joints  luted.  Heat  is  at  first  applied  to  only  one  of  the  cylinders, 
and  not  until  half  of  its  qpntents  are  distilled  off  is  the  second  cylinder  heated. 
Gradually  the  heat  at  d  increases  to  such  an  extent  as  to  melt  the  crude  sulphur;  by 
this  fusion  the  heavier  earthy  impurities  settle  down,  while  any  moisture  present  is 
driven  off.  When  the  distillation  of  the  contents  of  the  cylinder  first  heated  is 
finished,  that  cylinder  is  filled  with  liquid  sulphur  from  n  by  means  of  the  tube  f. 
The  quantity  of  sulphur  treated  iu  twenty-four  hours  yields  1800  kilos,  pure  material 
collected  in  g.  The  temperature  of  this  room  being  112°,  the  sulphur  is  there  kept 
in  a  molten  state,  and  as  soon  as  a  sufficient  quantity  has  collected  at  the  Jbottom,  it 
IB  tapped  off  into  l,  and  cast  in  the  moulds.    When  it  is  desired  to  prepare  flowers 

lowenof  sniphnr.  of  sulphur,  the  modo  of  operation  is  the  same,  but  the  temperature  of 
0  should  be  kept  at  or  rather  below  110°.  This  is  effected  by  making  the  distillation 
intermpted  instead  of  continuous,  so  that  in  twenty-four  hours  there  are  only  two 
distillations  of  150  kilos,  each.  As  soon  as  a  sufficient  quantity  of  flowers  of  sulphur 
has  been  condensed  in  the  room  o,  the  door  of  the  room  is  opened  and  the  sulphur 
removed. 

Dujardin  improved  upon  this  apparatus  in  1854.  By  this  process  of  distillation 
ofsulphur  a  lossof  11  to  20  per  cent  is  incurred,  partly  due  to  combustion  of  a 
portion  of  the  sulphur.  The  residue  left  in  the  cylinders  and  vessel  d  is  known  as 
Bulphur-slag.  The  ordinary  flowers  of  sulphur  of  commerce  always  contain  some 
sulphuric  and  sulphurous  acids,  which  can  be  removed  by  carefully  washing  with 
water.  Sulphur  so  treated  and  gently  dried  is  known  in  pharmacy  as  washed  flowers 
ofsulphur,  Flares  sulphuris  loti. 

''"TJJS'wiw?^^"      Where  fuel  and  labour  are  cheap,  and  a  good  quality  of  iron  or 

other  pyrites  is  found  in  abundance,  sulphur  may  be  prepared  by  the  following 

process : — 

I.  From  iron  pyrites,  FeSa.    As  this  mineral  consists  in  100  parts  of  467  of  iron 

^^  53*3  of  sulphur,  it  is  clear  that  if  half  of  the  latter  be  removed  by  distillation, 

there  will  be  left  a  compound  of  iron  and  sulphur  yielding  green  copperas  after 

oxidation.    Accordingly  iron  pyrites  might  by  distillation  lose  2665  parts  of  sulphur, 

and  the  residue  still  be  fit  for  making  green  copperas ;  but  if  this  quantity  were  to  be 

driven  off  in  practice,  the  temperature  would  require  to  be  raised  so  high  as  to  melt 

the  remaining  monosulphuret  and  lead  to  the  destruction  of  the  fire-clay  cylinders. 

The  quantity  of  sulphur  actually  distilled  off  on  the  large  scale  is  only  13  to  14  per 

*5ent,  leaving  a  pulverulent  residue  which  does  not  attack  the  fixe-clay  cylinders. 

The  process  thus  briefly,  outlined  is  carried  on  in  the  following  manner : — The  pyrites 
18  put  into  conical  fire-clay  vessels,  a  a.  Fig.  gi,  placed  in  a  somewhat  slanting  position  in 
the  furnace ;  the  lowe^  and  narrower  portion  of  these  vessels  is  fitted  with  a  perforated 
diaphragm  preventing  any  pyrites  falling  down  6,  while  the  volatilised  or  fluid  sulphur 
can  pass  readily  through  the  holes  into  a  receiver,  c,  filled  with  water.  After  the  vepsels 
AA  have  been  filled  with  pyrites,  the  fire  is  kindled  and  the  distiUatioii  set  in  progreKs. 
The  sulphur  collected  in  the  receiver  has  a  grey-green  colour,  and  is  purified  by  being 
re-molted,  after  which  it  is  sent  into  the  market  in  coarsely  broken  up  lumps.    In  order  to 


198  CHE3IICAL   TECHNOLOGY. 

free  tbJB  kind  e(  sulphur  from  sulphiiret  of  arsemo,  it  IB  Hnbmitteil  to  distiUation,  the 
reaidae  being  used  in  veterinary  practice.  Ilie  dark  colour  of  the  aulpbnr  obtained 
from  pjrites  is  dne  to  an  adnuitoie  of  thalUoni  far  more  than  to  the  preeeuee  of 
Mr.  W.  Crookee  found  i 


sulpbnr  obtained  from  Spanish  pyriteB  u 
much  KB  o'2g  per  cent  of  thallinm. 
PifcantisnofBiiipbiubT  »■  Sulphur  may  b« 
BouUDf  CDfpu  ptium.  obtained  by  the  roMt- 
ing  ol  copper  pyritei,  and  in  this  nj 
beoomea  a  by-pcodnot  of  emelting  copper 
oree.  Formerly  this  operation  was  earned 
on  in  peooliarly  conBtrucled  furnaces  in 
the  copper-smelting  irorke  of  the  Loirer 
Hortz,  Germany ;  at  the  present  time 
golpbiu'  from  this  sonrca  ie  only  obtained 
at  Agordo  in  Italy,  Wicklow  in  Ireland, 
and  at  Uuhlbacb,  Salzburg,  Austria. 
sgp^^^^Jjij^^^jj'  3,  Since  Laminj'B 
'luiiiiiactiire.  miilnre  baa  been  em- 
ployed in  purifying  eoal-gaa,  flolphni  bia 
to  Bome  eitent   been  obtained  ae  a  by. 

■  r^^^^^K  .  prodnct.    Lamtng'a  miiture  Ib  bydnttd, 

'     ^Ij^H^Bi  or  any  soft  porous  peioiide  of  iron  miied 

^ — .'  ■  '■'^''^I'lriii- 1  JK  nitb  aawdnst ;  andin  thiB  miiture  Bulphnr 

may  ooeumulate  to  upwards  of  40  per  cent 
jFeiOj  +  HjS-aPeO  +  HiO  +  S).  Accord- 
ing to  Hill's  patent  the  anlphnret  of  iron 
is  calcined  to  obtain  BOlphnronB  add. 
which  is  employed  in  the  preparation  ol 
Bolphuric  acid. 

sijpiiDriromHiidiWBiu.  4.  'WehaToalietdj 
Been,  while  treating  of  the  mano&ctnre  of 
soda  {ride  p.  185)  that  several  procesMi 
duetoMM.Schaffner.Guckelborger.Mond, 
P.  W.  Hofmann,  and  others,  are  in  nae  for  tho  regeneration  of  sulphur  from  soda  wisla; 
and  that  the  quantities  recuvered  are  not  amall  ma;  be  inferred  b'om  the  fact  that  tho 
Anstrian  Association  for  chemical  and  metallurgical  products,  under  the  management  of 
M-  SchaSner.  at  Ana^ig,  produces  annually  4;o,ooo  kilos,  of  sulphnr  in  this  manner. 

iht  Boinll"n"A  s"iRir''i"ii         5"  O^^ii^"  fi''»'  made  the  obserTation  that  when  one-third  of 
H;iin>KD  upnn  siiirJjup>n'<  '\c\i.  BulphuTetted  hydrogen  is  burned  off,  and  the  sulphurous  acid 
produced  conveyed  with  another  one-third  o(  enlphnretted  hydrogen  into  a  leaden  or  bliek 
chamber,  where  moisCnre  abounds,  nearly  all  the  sulphnr  is  regenerated : — 
Sulphnrong  acid.  BOi  I     ■  , .   j  Sulphnr,  33. 

Sulphuretted  by.lrogen,jH,S(  ^^'^  1  Water,  iH,0. 
By  this  reaction,  by  which,  however,  nearly  half  the  snlphur  is  lost  in  the  formation  of 
peutatbionic  acid,  it  boa  been  frequently  attempted  to  obtain  snlphur  from  gypanm, 
heavy  spar,  and  soda  wnate.  The  process  is  briefly  as  follows : — -For  instance,  heavy  spar, 
native  sulphate  of  baryta,  is  reduced  to  sulphuret  of  barinm,  which  is  treated  with  hydro- 
chloric acid,  sulphnrclted  hydrogen  and  chloride  of  barium  of  ooorse  being  fomted. 
Either  aportionof  the  gas  iabnrnt  and  to  the  products  of  the  combuatioti,8nlphuionB  odd 
and  water,  the  rest  of  the  gaa  added,  or  the  sulphuretted  hydrogen  is  conveyed  into  water 
to  which  Bnlphiirons  acid  is  simultaneouBly  conveyed  from  the  combustion  or  roaBting  o( 
iron  pyrites,  Mr.  Oosaage  long  since  proved  that,  by  conveying  snlpburetted  hydrogen  inW 
chloride  of  iron,  the  sulphnr  of  the  gas  ia  deposited.  Snipbnr  may  be  obtained  hj 
a  aimilar  reaction  as  a  by-product  of  the  manufacture  of  iodine  and  pctoeaa  aalta  from 
kelp.  At  Paterxon's  iodine  factory  at  Glasgow,  2000  cwts.  of  thie  anlphnr  ore  obtained 
annually.  According  to  E.  Kopp  the  incomplete  combnation  of  sulphoietted  hydrogen 
yields  Bolphur  economically  (Hi3-HO  =  HiO-hS). 
luS'.m'SVllh.Uii.lM  ^'  ^^^^  sulphuTona  acid  gas  ia  conveyed  over  red-hot  chorooal, 
A«dDiiCbuD«i."  the  latter  ia  converted  into  carbonic  acid,  white  snlphur  ia  set  free. 
By  this  reaction  the  aniphllrons  acid  from  the  roasting  of  zinc  orea  (black-jack)  is  con- 
verted into  sulphnr  in  large  quantities  at  Burbeck,  near  Essen,  Prussia. 
Br  uaUis  "I  snipbuRtuj  7'  When  snlphnretted  hydrogen  is  paased  throngh  red-hot  tabes, 
Ujiiri«,^u.  it  ij  decomposed ;  but  thia  reaction  U  not  industrially  applicaUe  to 

tho  preparation  o(  snlphur. 


SULPHUR.  199 

piepertiamndUiM       The  yellow  ooloux  of  sulphur  is  generally  known  ;  at  loo"*  this  colour 
ofsniphur.        deepens  and  nearly  disappears.      At  —50°,  sulphur  is  very  brittle  and 
readily  pnlverised,  becoming  by  the  friction,  especially  in  warm  and  dry  weather,  so  highly 
electric  as  to  cause  the  particles  to  adhere  strongly  to  each  other.    The  sp.  gr.  of  this 
element  varies  from  1*98  to  2-06.    It  melts  at  115'',  forming  a  thin  yellow  liquid,  which,  at 
160*",  becomes  thick  and  assumes  an  orange-yellow  colour  ;  when  heated  to  220°,  sulphur 
is  a  tough,  red,  semi-solid ;  between  240°  and  260°  the  colour  becomes  red-brown,  but 
being  heated  aboye  340°,  the  sulphur  is  again  somewhat  fluid,  and  at  last  boils  at  420°  without 
baring  lost  its  deep  colour,  which  also  characterises  the  vapours.    When  sulphur  heated 
to  230°  is  suddenly  poured  into  cold  water,  it  remains  soft  and  so  plastic  that  it  may  be 
advantageously  employed  for  obtaining  impressions  of  medals,  woodcuts,  and  engraved 
plates,  these  impressions  as  the  sulphur  again  hardens  after  a  few  days  serving  as 
moulds.    On  being  heated  in  contact  with  air,  sulphur  bums,  forming  sulphurous  acid. 
It  Lb  insoluble  in  water,  very  slightly  soluble  in  absolute  alcohol  and  ether,  and  rather 
more  soluble  in  warm  fixed  and  volatile  oils,  forming  the  so-called  sidphur  balsam.    The 
best  solvents  for  sulphur  are — sulphide  of  carbon,  coal-tar  oil,  benzol,  and  chloride  of 
Bolphur.*    It  also  dissolves  in  boiling  solutions  of  caustic  soda  or  potassa,  in  hot  solutions 
of  Bulphurets  of  calcium  and  potassium,  in  the  solutions  of  certain  sulpho-salts ;  for 
instance,  the  compound  Sb2S3,Na2S,  which  is  converted  into  Sb2S5,Na2S,  and  in  solutions 
of  aUudine  sulphites,  converted  thereby  into  hyposulphites. 

Sulphur  is  used  in  the  manufacture  of  sulphuric  acid,  gunpowder,  fireworks,  for  sulphuring 
bops  and  vines  as  a  preservative  against  some  diseases  of  these  plants ;  the  quantity  of  sulphur 
lued  for  the  purpose  of  sulphuring  vines  in  France,  Spain,  and  Italy,  amounted,  in  1863, 
to  850,000  owts.  of  Sicilian  sulphur,  being  about  from  20  to  25  .per  cent  of  the  entire 
production.  It  is  further  employed  in  the  manufacture  of  sulphurous  acid,  sulphites,  and 
hyposulphites,  sulphide  of  carbon,  cinnabar,  mosaic  gold  or  bisulphide  of  tin,  and  other 
metallic  sulphurets,  ultramarine,  various  Cements,  and  for  vulcanising  and  ebonising 
india-rubber  and  gutta-percha. 

The  greater  part  of  the  total  sulphur  production  of  Europe  comes  from  Sicily,  whence, 
in  1868,  4,052,000  cwts.,  in  value  about  £1,500,000,  were  exported.  The  total  sulphur 
production  of  Europe  in  1870  amounted  to  7,012,500  cwts.,  but  in  this  quantity  the 
solphur  recovered  from  soda  waste  is  not  included. 

SULPHUROCS    AND   HyPOSULPHUROUS   AcIDS. 

M»inirouAeiiL       Thls  acid  (SO^,  or  hydrated  H2SO3)  may  be  obtained — 

a.  By  oxidation  of  sulphur ; 

b.  "By  reduction  of  sulphuric  acid  ; 

e.  By  a  combination  of  the  processes  a  and  b. 
The  preparation  of  sulphurous  acid  by  tlie  oxidation  of  sulphur  may  be — a.  By 
burning  brimstone  in  the  air ;  /3.  By  roa.sting  or  calcining  iron  and  copi)er  pyrites,  or 
the  product  of  Laming's  mixture  from  the  purifiers  of  gas-works ;  y.  By  igniting  a 
mixture  of  manganese  and  sulphur.  The  preparation  of  sulphurous  acid  by  roasting  sul- 
phurets, when  coupled  with  metallurgical  operations,  is,  especially  since  Gerstenhofer's 
fomace  has  been  more  generally  introduced,  the  most  advantageous  plan  of  obtaining 
this  acid,  and  also  where  the  acid  is  required  for  the  manufacture  of  sulphuric  acid. 
When,  however,  sulphurous  acid  is  reqiiiied  for  the  purpose  of  preserving  food, 
aad  as  a  raw  material  in  the  preparation  of  wines,  hops,  &c.,  it  should  not  be 

« 

*  According  to  Cossa  (1868)— 

100  parts  of  sulphide  of  carbon  dissolve  at 
100    ,,  ,,  ,,  ,, 

^00    ,,  ,,  ,,  „ 

100    „  benzol  „  „ 


»i  »»  It  ji 


100 

100     „  ether  „  „ 

100    „  chloroform    „  „ 


, ,  «>UU.UAV>  ,  , 


15  0* 

31*15  parts  of  sulphur. 

38*0° 

94*57     » 

48-5° 

146-21     „                „ 

260' 

096     „ 

yi-o" 

4*37     M 

ZS'S" 

0-97     „ 

22-0* 

1*20     ,,                „ 

1300"* 

85-27    M 

100    „  aniline 

According  to  Pelouze — 

100  parts  of  coal-tar  oil,  sp.  gr.  0*88,  dissolve,  at  130-0 ',    43-0  parts  of  sulphur. 


Sulphuric  acid,  2H2SO4 
Copper,  Cu 


200  CHEMICAL    TECHNOLOGY. 

made  from  pyrites,  but  from  sulphur,  as,  when  obtained  from  pyritea,  it  is  always 
mixed  with  arsenious  acid.  The  Laming's  mixture  saturated  with  sulphur  from 
gafl- works  is  largely  used  in  the  preparation  of  sulphurous  acid  in  sulphniic  acid 
works  in  and  around  London.  The  ignition  in  close  vessels  of  metallic  oxides  and 
sulphur  can  only  be  advantageously  used  for  the  preparation  of  sulphurous  add 
under  certain  conditions.  The  oxides  chiefly  used  for  this  purpose  are  those  of 
manganese  and  copper ;  the  former  yields,  according  to  the  weight  of  the  materials 
employed,  either  only  half  the  weight  of  the  sulphur  in  the  shape  of  stilphuroiis  acid, 
or  the  whole  of  the  sulphur  may  be  converted  into  acid.  Sulphurous  acid  is  some- 
times prepared  by  heating  a  mixture  of  sulphate  of  iron  and  sulphur — 

(FeS04-h2S=FeS+2S02). 
When  sulphate  of  zinc  is  calcined  it  yields  sulphurous  acid  and  oxygen — 

(ZnS04=:  SOa+O+ZnO) . 
Kieserite  (MgS04+H20),  mixed  with  charcoal  3delds  all  its  sulphuric  add  as 
sulphurous  acid. 

The  preparation  of  sulphurous  add  by  the  reduction  of  sulphuric  acid  is  very  frequent ; 
sulphuric  add  is  reduced  by  being  strongly  heated  in  contact  with  certain  metals ;  for 
instance,  copper,  mercury,  and  silver : — 

[Sulphate  of  copper,  GUSO4, 
yield  •  Sulphurous  add,  SO2, 
.(Water,  2HaO. 
A  small  quantity  of  sulphuret  of  copper  is  also  formed.    The  dilution  of  sulpharous 
add  with  carbonic  acid  and  carbonic  oxide  does  not  interfere  with  its  intended  use. 
Sulphuric  add  is  decomposed  and  reduced  by  being  boiled  with  charcoal-dust,  sawdust, 
wood-shavings,  &c. 

[  Sulphurous  add,  2SO2. 
-  yield  ■  Carbonic  acid,  CO2. 
(Water,  2HaO. 
This  mode  of  operation  may  be  made  continuous  by  keeping  up  a  supply  of  sulphnrie 
acid  and  sawdust  in  the  glass  retort,  as  the  decomposition  of  both  these  substances  is 
complete,  yielding  sulphurous  acid,  water,  and  carbonic  add.    When  the  vapours  of 
sulphuric  acid  are  passed  through  red-hot  glass  or  porceladn  tubes,  the  result  is  the 
formation  of  sulphurous  acid,  oxygen,  and  water  (HaS04  »  SOa + 0 + H2O) .    The  redaction 
and  decomposition  of  sulphuric  acid  by  the  aid  of  sulphur  may  be  viewed  as  a  combined 
process  of  preparing  sulphurous  acid  by  oxidation  and  reduction : — 

Sulphuric  add,  2H2SO4)     .^j    f  Sulphurous  add,  3SO21 
Sulphur,  S  ;  y^®^^  1  Water,  2H2O. 

In  practice,  however,  this  operation  is  very  difficult,  owing  to  the  fact  that,  long  before 
the  reaction  begins  to  take  place,  the  sulphur  is  molten,  while  as  soon  as  the  reaction  sets 
in  it  becomes  very  tumultuous,  and  with  the  sulphurous  acid  gas  vapours  of  sulphur  are 
carried  over,  which  solidify  and  obstruct  the  passage.  At  the  ordinary  temperature  and 
pressure  of  the  atmosphere,  sulphurous  add  is  a  gas  having  a  pungent  odour,  and  a 
sp.  gr.s=2'2i.  This  gas  dissolves  readily  and  in  large  quantity  in  water,  i  volume 
absorbing  at  18^,  44  volumes  of  gas.  It  is  even  more  soluble  in  alcohoL  When  water  is 
present  sdl  the  higher  oxides  of  nitrogen  give  up  some  of  their  oxygen  to  the  sulphurooB 
add,  converting  it  into  sulphuric  acid,  the  oxides  forming  deutoxide  of  nitrogen. 
Chlorine  also  converts  moist  sulphurous  acid  gas  into  sulphuric  add,  and  siimltf 
results  obtain  with  iodine.  The  mixture  of  sulphurous  add  and  sulphurekted  hydrogen 
causes  their  mutual  decomposition,  water  being  formed,  and  sulphur  deposited.  Sulphu- 
rous acid  is  chiefly  employed  in  preparing  sulphuric  acid,  in  the  manufacture  of  paper,  M 
so-called  antichlorine,  in  the  preparation  of  madder  by  E.  Eopp's  process,  the  prepara- 
tion of  hyposulphite  of  soda,  and  the  manufacture  of  sulphate  of  ammonia  from 
lant  (stale  urine).  Sulphurous  add  is  employed  according  to  Laminne's  patent  for  the 
purpose  of  decomposing  alum-shale  in  the  manufacture  of  alum. 

It  is  further  employed  in  some  metallurgical  processes,  for  preserving  food,  bleaching 
syrups,  silk,  wool,  sponges,  feathers,  glue,  isinglass,  and  other  animal  substances,  whieh 
do  not  admit  of  being  treated  with  chlorine,  and  for  bleaching  straw  hats,  willow 
and  wicker  baskets,  gum  arabic,  &o.  The  bleaching  property  of  sulphurous  add  may  be 
considered  as  due  to  two  entirely  different  causes;  in  some  instances  the  pigm^it  is  only 


Sulphuric  acid,  2H2SO4 
Charcoal,  C 


SULPHUR,  20I 

masked,  not  deetroyed,  as  snlphnrons  add  enters  with  some  pigments  into  a  oolonrless 
eombination ;  in  other  instances,  howeyer,  a  real  decomposition  of  the  pigment  takes 
place.  The  former  condition  obtains  with  most  of  the  bine  and  red  flowers  and  froits ;  a 
red  rose  bleached  by  snlphnrons  acid  has  its  colonr  restored  by  immersion  in  very  dilnte 
solpbnrio  acid,  ^e  pigments  of  yellow  flowers  are  not  affected  by  solphnrons  acid ; 
it  also  does  not  at  first  act  npon  indigo  and  carmine  and  the  yellow  colonr  of  raw  silk,  bat 
by  the  combined  and  continned  action  of  this  acid  and  direct  snnlight,  the  oxygen  of  the 
acid  acts  as  ozone  and  determines  the  bleaching.  The  avidity  of  snlphnrons  acid  for 
oigrgen  may  be  utilised  in  extingnishing  fires,  especially  in  the  case  of  the  soot  of 
chimneys  catching  fire,  which  may  be  very  readily  subdued  by  throwing  a  few  ounces 
of  flowers  of  sulphur  into  the  fireplace  or  stove. 

soipfaite  of  LioM.  Neutral  sulphite  of  lime  (SGa203+H20),  containing  in  roo  parts 
41  parts  of  sulphurous  acid,  deserves  attention  as  a  cheap,  commodious,  and  very  efficient 
substance  for  the  development  of  sulphurous  acid,  the  gas  being  readily  set  free  by  the 
action  of  hydrochloric  or  sulphuric  acid.  Bisulphites  of  lime  and  soda,  the  former 
in  solution,  theiatter  as  a  solid  dry  powder,  are  largely  produced  in  some  of  the  beet-root 
sugar  manufacturing  countries. 

Hypomipiiita  of  Soda.  This  Salt  (SaNaaOs+sHaO)  is  largely  used  in  photography,  in 
metallnrgy,  as  a  mordant  in  calico-printing,  and  as  antichlor  in  paper-making. 
Hyposulphite  of  soda  may  he  prepared  by  sevend  methods.  According  to  Anthon,  4 
parts  of  calcined  sulphate  of  soda  are  mixed  with  i  to  li  parts  of  charcoal  powder, 
the  mixture  is  moistened  and  placed  in  an  iron  crucible,  and  calcined  at  red  heat  for 
6  to  10  hours ;  the  cooled  mass  broken  into  small  lumps  is  again  moistened  with 
water  and  then  exposed  to  the  action  of  sulphurous  acid ;  the  resulting  product  iff 
dissolved  in  water,  filtered,  concentrated  by  evaporation,  and  left  to  crystallise. 
AccardiDg  to  £.  Kemp's  method,  carried  out  industrially  by  Max  SchajQ&ier  at  Aussig,. 
hyposulphite  of  lime  is  first  prepared  by  causing  stilphurous  acid  to  act  upon 
sulphuret  of  calcium  (soda  waste).  The  lixiviated  mass  is  treated  with  sulphate  of 
soda,  the  result  being  the  formation  of  soluble  hyposulphite  of  soda  and  practically 
insoluble  sulphate  of  lime.  Very  recently  the  pentathionic  acid  (SsOj.HaO), 
obtained  in  large  quantity  as  a  by-product  of  the  reaction  between  stilphuretted 
hydrogen  and  sulphurous  acid  in  preparing  sulphur,  has  been  converted  into  hypo- 
sulphite of  soda  by  boiling  with  soda  lye  (2S503,HaO+3HaO=5SaOa,HaO). 

As  hyposulphite  of  soda  possesses  the  property  of  readily  forming  with  oxide  of  silver 
a  soluble  double  salt,  hence  dissolving  easily  such  insoluble  compounds  as  chloride  and 
iodide  of  silver,  it  is  employed  in  photography  and  in  the  hydrometallurgical  extraction  of 
silver.  Being  a  solvent  for  iodine  it  is  used  in  chemistry  for  purposes  of  volumetrical 
analysee.  A  mixed  solution  of  sulphite  and  hyposulphite  of  soda  dissolves  malachite  and 
blue  copper  ore,  forming  hyposulphite  of  protoxide  of  copper  and  sodium.  Stromeyer 
has  applied  this  reaction  to  the  hydrometallurgical  extraction  of  copper.  Hyposulphite 
of  soda  is  also  used  for  preparing  antimonial  cinnabar  and  aniline  green ;  the  hyposul- 
phites of  lead  and  copper  have  been  proposed  as  a  paste  for  lucifer  matches.  The 
property  possessed  by  hyposulphite  of  soda  of  fusing  at  a  comparatively  low  temperature 
in  its  water  of  crystallisation,  and  of  readily  solidifying  on  cooling,  has  been  utilised  by 
Fleck,  in  the  seiding  of  glass  tubes  containing  explosive  compounds  to  be  used  under 
water  in  torpedoes.  The  enormous  consumption  of  hyposulphite  of  soda  may  be  readily 
inferred  from  the  fact  that  the  chemical  factory  near  Aix-la-Ohapelle  produces  2000  cwts., 
and  the  factoiy  at  Aussig,  Austria,  6000  cwts.  of  this  salt  annually. 

Manufacture  of  Sulphuiuo  Acid. 

Sulphuric  acid,  HaS04,  consists  in  100  parts  of  81  parts  of  anhydrous  sulphuric 

add  and  18-5  parts  of  water, 
soipbozk  Add.      There  are  in  the  trade  two  distinct  varieties  of  this  acid : — 
a.  Fuming,  or  Nordhausen  sulphuric  acid  (oil  of  vitriol),  obtained  by  distillation 

from  sulphate  of  iron,  bisulphate  of  soda,  sulphate  of  peroxide  of  iron,  or  by  the 

decomposition  of  sulphate  of  soda  by  means  of  boric  acid  in  the  preparation  of 

borax. 


ao2  CHEMICAL  TECHNOLOOY. 

b.  Ordinarr  sulphuric  add,  known  abrotkd  as  l^ngli»)i  eulphoric  acid,  prepared  by 
the  osidadon  of  sulphurous  acid  by  moons  <^  nitrous  acid,  or,  very  rarely,  separated 
from  native  sulphates.  ' 

FuiDini  bdwikid  ixid.  At  a  red  heat  all  sulphates,  except  those  of  the  alkalies  and 
alkaline  earths,  are  decomposed,  and  therefore  may  be  employed  in  the  preparation 
of  filming  sulphuric  acid;  but  on  account  of  its  cheapness  sulphate  of  iron  is  pre- 
ferred. This  salt,  on  eitposure  to  red  heat,  is  decomposed  into  anhydrous  snlphunc 
acid  and  eolphucons  acid  :— 

[Peroxide  of  iron.  Fe,Oj, 
Sulphate  of  iron,  2E'eS04,  yields  J  Snlphuric  acid.  SOj. 
(sulphurous  acid,  SO,. 

Anhydrous  sulphuric  acid  would  indeed  be  obtained  from  sulphate  of  iron  if  it 
were  possible  to  procure  the  salt  perfectly  auhydioos.  but  as  this  cannot  be  dooe 
without  decomposition,  some  water  is  always  retained,  the  result  being  the  compound 
Imown  as  fuming  sulphuric  acid,  th&t  is  t^)  say,  a  mixture  of  anhydrous  and  ordinary 
add  (H1SO4),  the  former  in  very  variable  quaotitira. 

Fnming  Bnlphnrio  add  ia  prepared  on  the  large  scale  in  the  following  manner;— Th« 
solution  of  Buipfaate  of  iron  ia  flrst  evaporated  to  drynesB,  and  dried  in  open  veuali 
ai  much  as  possible.  The  dry  saline  mass,  vitriol'Stone  it  is  termed  in  Oermany.  ia  next 
transferred  to  fire-clay  flasks,  1,  Fig.  93,  placed  in  a  g^ey  furnace,  the  neoks  paenng 
throngh  the  wall  ol  the  fomaee,  and  being  properly  secored  to  the  neclis  of  the  recaiveis, 
BB.  bito  eaoh  of  the  flasks  2';  lbs.  of  vitnol-stone  are  pnt ;  on  the  Qrst  apphoation  of 
heat  only  snlphuioas  add  and  weak  bydrated  stUphuria  add  oome  over,  and  are  nmaUy 


allowed  to  escape,  the  receivers  not  being  securely  luted  antil  white  yspomfi  of  mnhydioDs 
aolphurio  acid  are  seen-  Into  each  of  the  receiving  flasks  30  grms.ol  water  are  poured,  uid 
the  distillBtian  continued  tor  24  to  36  hour^.  The  retort  flasks  are  then  agdn  filled  with 
raw  material,  and  the  operation  repeated  foui  times  before  the  oil  of  vitriol  ia  deooed 


SULPHUR.     ,  203 

snffidentlj  strong.  The  residae  in  the  retorts  is  red  oxide  fperoxide)  of  iron,  still 
retaining  some  sulphuric  aoid.  The  quantity  of  fuming  aoid  obtained  amounts  to 
45  to  50  per  eent  of  the  weight  of  the  dehydrated  sulphate  of  iron  employed;  at 
Davidsthal,  in  Bohemia,  14  cwts.  of  Titriol-stone  yield  in  thirty-siz  hours,  54  owts.  of 
fnming  sulphuric  acid. 

It  is  preferable,  however,  to  use  sulphate  of  peroxide  of  iron  instead  of  the  dried 
protosulphate ;  the  sulphate  of  the  peroxide  can  be  readily  prepared  by  means  of  the 
peroxide  and  ordinary  sulphuric  acid.  Frequently  the  fuming  acid  is  prepared  by  passing 
anhydrous  sulphuric  aoid,  obtained  by  calcining  perfectly  dehydrated  protosulphate  of 
iron,  or,  better  still,  the  persulphate  of  iron,  into  ordinary  oil  of  Titriol.  Fuming 
sulphuric  aoid  is  now  and  then  prepared  from  the  bisulphate  of  soda  left  after  the 
preparation  of  nitric  acid  from  Ghili-Baltpetre.  In  France  calcined  sidphate  of  soda  and 
boraeio  acid  are  intimately  mixed  and  calcined,  and  the  yapours  of  anhydrous  sulphuric 
add  disengaged  are  absorbed  by  strong  ordinary  sulphuric  aoid.  Fuming  sulphuric  acid 
la  an  oily  liquid  of  a  brown-yellow  or  deep  brown  colour ;  it  emits  the  pungent  smell  of 
sulphurous  add,  fumes  on  being  exposed  to  air,  and  yields  on  being  heated  vapours  of 
auhydrio  sulphuric  aoid;  the  sp.  gr.  varies  from  1*86  to  1*92.  It  is  industrially  hardly 
Qsea  for  any  other  purpose  than  dissolving  indigo,  i  part  of  the  latter  requiring  for  its 
solution  4  parts  of  fuming  and  8  parts  of  ordinary  siUphurio  add. 

oi^grwB^tob      xhe    concentrated   sulphuric   acid    (HaS04),  oil   of  vitriol  of 

commerce,  consists  in  100  parts  of  81*5  parts  of  anhydrous  acid  and  18*5  of  water. 

The  prepartion  of  this  acid  on  the  large  scale  in  leaden  chambers  dates  from  the 

year  1746,  when  Dr.  Roebuck,  of  Birmingham,  erected  the  first  leaden  chamber  at 

Prestonpans,  near  Edinburgh. 

The  rationale  of  the  manufacture  of  sulphuric  acid  by  the  chamber  process,  in  which 
sulphurous  acid,  nitric  or  nitrous  acid,  and  water  are  employed,  is,  according  to  the  latest 
researchee  of  B.  Weber  (1866)  and  Winkler  (1867),  the  following: — The  oxidation  of  ihe 
solphurouB  aoid  to  sulphuric  acid  takes  place  in  the  leaden  chambers  under  the  influence 
of  the  vapour  of  water  at  the  expense  of  the  oxygen  of  the  nitrous  acid,  which  is  con- 
verted into  deutoxide  of  nitrogen.  It  is  necessary,  however,  that  the  nitrous  add  be  &rBt 
absorbed  in  plenty  of  water,  which  takes  up  the  free  nitrous  aoid,  and  decomposes  the 
bypomtric  acid,  a  process  greatly  promoted  by  the  presence  in  the  chamber  of  sulphurous 
acid  purposely  introduced.  The  water,  usually  in  the  form  of  steam,  because  practical 
experience  proves  that  a  certain  elevation  of  temperature  is  required,  acts  in  this  process 
as  ia  others  wherein  sulphurous  acid  efifects  reduction.  By  the  presence  of  atmospheric 
air  in  the  chamber  the  deutoxide  of  nitrogen  is  oxidised  into  hyp^tric  or  nitrous  add, 
a&d  this  aoid  again  decomposed  by  sulphurous  acid ;  if  the  conditions  are  favourable 
the  process  is  continuous.  It  occasionally  happens  that  the  nitrous  add  in  contact  with 
sulphurous  acid  and  excess  of  water  forms  protoxide  of  nitrogen,  of  course  causing  a  loss 
of  the  efficient  oxides  of  the  nitrogen.  The  formation  of  the  so-called  chamber  crystals, 
consisting  according  to  B.  Weber  of  (H2S04+Na03,S03)  only  takes  place  when  the 
process  is  not  well  managed,  and  is  chiefly  due  to  want  of  water. 

^*TiSptotei3£' ***  Although  the  use  of  leaden  chambers  is  due  to  an  Englishman, 
the  present  mode  of  manufacturing  sulphuric  acid  was  invented  (1774)  by  a  calico 
printer  at  Bouen,  and  improved  by  the  celebrated  Ghaptal.  The  apparatus 
consists  essentially  of  four  parts,  viz. — i.  A  furnace,  f,  Fig.  93,  where,  by  the  com- 
bustion of  sulphur  or  pyrites,  sulphurous  acid  is  formed ;  the  sulphurous  acid, 
carrying  with  it  the  nitrous  vapours  prepared  in  the  sulphur  burner  by  means  of  a 
peculiar  contrivance,  escapes  from  the  furnace  through  the  tube,  x.*  2.  An  apparatus 
filled  with  coke  through  which  mixed  sulphuric  and  nitric  acids  percolate.  3.  A 
number  of  leaden  chambers,  a,  a',  and  a",  wherein,  under  the  influence  of  high 
pressure  steam,  the  sulphuric  acid  is  formed.    4.  A  large  apparatus,  k,  known  as 

*  In  order  to  convert  z  kilo,  of  sulphur  into  sulphuric  acid,  the  following  quantities  of 
air  are  required: — 

When  the  sulphur  is  present  in  free  state,  5275  litres  of  air,  containing  4220  litres 

of  nitrogan. 
When  the  sulphur  is  present  as  pyrites,  6595  litres  of  air,  containing  5276  litres  of 
nitrogen. 


204  CHEMICAL  TBCBNOLOGY. 

Gay-Lnssac's  condenseF,  Med  with  coke,  through  which  Bulpfauric  acid  x>f  66°  B. 

(=i'84Bp.  gr.)  percolates,  the  ^m  being  to  take  up  the  nitric  and  hjponitric  ocida,  not 
the  deutozide  of  nitrogea  as  was  believed  before  Winkler  elacidated  this  point. 


from  the  gases  which  flow  into  the  last  chamber  previously  to  being  discharged. 
The  fomsce  or  burner,  as  it  is  technicallj  caUed  (see  Fig.  94),  is  boUt  of  bricks :  at  a 
height  of  So  centims.  from  the  floor  a  stout  caat.iron  plate  is  placed  so  as  to  have 
a    slight  inclination   towards   the 
^*-  94-  front.     The  walls  are  also  covered 

with  heavf  cast-iron  plates.  In 
front  of  the  burner  are  three  or  six 
large  openings,  p.  p*.  p",  which  can 
be  closed  by  iron  doors  fitted  with 
wooden  handlea.  On  the  bed  or 
bottom  plate  three  iron  rails  or 
ledges,  each  10  centims,  high,  are 
placed  to  divide  the  bottom  of  the 
furnace  into  three  or  six  compart- 
ments. At  H,  h',  and  a"  are  the 
holes  for  the  necessary  supply  of 
air.  On  the  top  plate  is  firmly 
fixed  the  tube,  t.  which  conveys 
the  gases  generated  in  the  burner  to  the  leaden  chamber  of  eacli  section  or  com- 
partment. The  burner  is  charged  with  abont  50  kilos,  of  Riitpbur;  this  is  kindled 
at  the  top,  the  draught  of  air  throngb  h.  h'.  and  h"  being  ijt(i  regulated  as  to  GMIbc 

/ 


SULPHUR. 


205 


the  snlphnr  to  be  burnt  off  without  becoming  sublimed,  for  if  any  sulphur  were 
volatilised  it  would  cause  the  sulphuric  acid  to  be  turbid  and  mOky.*  Not  only 
does  the  burner  supply  sulphurous  acid,  but  also  the  nitric  acid  or  nitrous 
▼apours  required  in  the  leaden  chamber;  these  are  generated  from  a  mixture  of 
nitrate  of  soda  and  sulphuric  acid  at  52°  B.  ( =  1-56  sp.  gr.)  placed  in  the  cast-iron 
pot,  N,  which  when  filled  is  placed  on  the  burning  sulphur. 

The  construction  and  arrangement  of  the  denitrificateur  is  shown  in  Fig  95.     At  a 
is  placed  an  iron  grating  covered  with  thick  perforated  sheet  lead ;  the  vapours  and 
gases  generated  in  the  burner  pass  through  m  into  the 
space  immediately  below  o,  upon  which  a  column  of  ^^^'  95' 

coke  is  placed,  and  kept  saturated  with  sulphuric 
add  strongly  charged  with  nitric  acid,  obtarued  by  the 
condensation  of  the  gases  from  the  last  chamber.  This 
add  is  forced  by  means  of  compressed  air  from  the 
vessel  T  into  the  Maiiotte  bottle,  v,  and  passes  thence 
through  T  into  h,  thence  by  t'  to  the  coke,  over  which 
it  is  delivered  in  fine  jets  by  means  of  a  perforated 
plate  fitted  to  the  lower  part  of  the  cover  a.  The  acid 
coming  in  contact  with  the  warm  gases  from  the 
chamber  yields  to  them,  in  the  state  of  vapour,  all  the 
nitrous  compounds  dissolved  in  the  sulphuric  acid,  and 
charged  with  these  vapours  the  gases  pass  through 
m.  Fig.  93,  into  the  leaden  chambers.  The  denitrified 
solphuric  add  runs  off  through  the  tube  t  into  a  reservoir. 

The  formation  of  sulphuric  acid  takes  place  in  the  leaden  chambers  or  chamber.  In  many 
eftB68,  especially  abroad,  only  one  large  chamber  is  worked,  which  is  then,  as  shown  in  Fig.  93, 
divided  by  the  leaden  plates  a  a',  technically  termed  curtains,  into  three  or  more  compart- 
inents,  these  curtains  reaching  to  the  bottom  into  the  acid  ooUeoted  there.  If  several 
chambers  are  worked,  communication  is  maintained  by  means  of  leaden  tubes.  The 
tubes,  vv'  v'\  convey  steam  to  the  chambers.  The  chambers  are  not  nsnally  aJl  of  the 
same  size,  one  being  considerably  larger  than  the  others ;  in  the  largest  most  of  the  add  is 
generated.  The  gases  and  vapours  contained  in  the  last  chamber  being  almost  free  from 
solphurous  add,  and  consisting  mainly  of  atmospheric  air  and  nitrous  vapours,  are 
conveyed  through  t'  to  the  leaden  reservoir,  n,  where  the  last  traces  of  sulphuric  acid  are 
deposited.  The  action  of  Gay-Lussac^s  condenser,  k,  is  based  upon  the  fact  that  concen- 
trated sulphuric  add  absorbs  and  combines  vrith  nitrous  acid.  The  apparatus  consists 
esBentially  of  a  column  of  coke  8  to  10  metres  in  height,  through  which  strong  sul- 
phnrie  add,  62**  or  64°  B.,  percolates,  the  flow  being  regulated  by  the  apparatus  shown  in 
Fig.  95.  The  acid  saturated  vrith  nitrous  acid  is  conveyed  by  the  tubes  hh  into  a 
reservoir,  o,  from  which  it  is  again  forced  by  means  of  the  monte-add  to  the  Mariotte 
flask,  M.  By  the  tube  t'",  the  gases  are  conveyed  to  the  chimney  stalk  of  the  works.  As 
regards  the  cubic  oapadty  of  the  leaden  chambers,  each  20  kilos,  of  sulphur  consumed  in 
twenty-four  hours  requires  30  cubic  metres  (about  100  cubic  feet)  capacity;   as  this 


*  Aecording  to  theory,  i  molecule  of  sulphur  requires  only  3  molecules  of  oxygen,  viz., 
2  to  form  sulphurous  acid,  and  i  to  convert  the  latter  into  sulphuric  add ;  that  is  to 
say,  I  kilo,  of  sulphur  requires  1500  grms.  =:  1055  litres  of  oxygen  s  5275  litres  of  air, 
in  whidi  4220  litres  of  nitrogen  are  contained.  In  order  to  regulate  this  supply  of  air 
numy  contrivances  have  been  adopted,  among  them  the  anemometer  invented  by  Combes ; 
this  is  fitted  to  the  sulphur  burner  by  means  of  a  tube,  through  which  the  air  supplied 
has  to  pass.  In  England  reliance  is  placed  upon  the  skill  of  the  workmen  who  regulate 
the  draught,  as  it  is  termed,  dmply  by  the  slides  in  the  doors  of  the  burners. 

The  air  discharged  from  ^e  chambers  should  not  contain  more  than  2  to  3  per  cent  of 
oxy^n.  By  careful  management  and  with  good  apparatus  the  maker  may  succeed  in 
obtaining  from  100  kilos,  of  sulphur  306  kilos,  of  strong  acid  at  1*84  sp.  gr. ;  but  the 
nsnal  quantity  from  100  kilos,  of  sulphur  is  seldom  more  than  280  to  290  kilos. 


ao6  CHEMICAL  TECHN0L007. 

qiuntit7  of  nilphar  oorregponds  to  Co  kilos,  of  hydisted  snlphario  add,  a  ebunW  el 
the  oapacit;  meatioDed  yields  1-5  kiloa.  ol  snlphnric  acid  p«r  boor.  One  btrndied  paiU 
of  Bolphnr  require  from  6  to  8  parte  of  nitrate  of  soda,  bat  if  pyrites  is  employed  tliis 
quantity  ia  often  inoTeased.  Also  when  pyrites  is  bnmt  larger  ohambers  are  used.  Latdf 
Qay-Lnasao's  condenser  has,  in  many  oases,  fallen  into  diBose,  on  acoonnt  of  the  low  pdee 
of  Chili- saltpetre,  and  the  expense  of  keeping  the  apparatus  in  worlung  order. 

"""^  ^bJSJS^ISF'"'"  InBteftd  of  sulphur  native  minerals  contaimsg  that 
element  are  frequently  em^jed  for  the  preparation  of  eulphurons  acid.  Among 
these  minerals,  iron  pyrites,  biaulphuret  of  iron.  FeSj,  containing  53'5  per  cent 
of  sulphur,  is  the  most  largely  nsed.  The  pyritea  are  calcined 
_  °'  0"'  in  peculiarly  constructed  kilns,  built  with  fire-bara,  the 

spaces  between  which  may  be  a4iaated  by  means  of  a  key, 
and  the  admission  of  the  air  required  for  combostion  regn- 
'    '  '     lated  with  great  nicety.     The  best  pyrites  oven  known  on 

the  Continent  is  Gerstenhofei's,  invented  in  1864 ;  the  prin- 
ciple of  this  oven,  Fig.  0,  is  lliat  the  pyrites  is  made  to 
foU  throngh  anA  meet  the  colomn  of  heated  air  sup- 
porting the  combustion.  In  order  to  prolong  the  faU  of 
the  powdered  pyrit«s,  terraces  or  banks  are  built  at  intervals 
in  the  shafts.  The  broken  np  pyrites  falls  through  the 
funnels  a,  provided  with  grooved  rollers  to  pulverise  it,  on  to 
:  the  bonks  e,  from    one    terrace,  aa  they  are  termed,  to 

'  another.    Aa  the  fomace  has  been  previously  made  red-hot. 

^        *"    ,   **  "        the  sulphur  ore  ignitea  and  bums  oS,  aided  by  a  moderate 

blast  at  c.  The  sulpburous  acid  formed  ia  discharged  by  the  channels  d  into  the 
sulphuric  acid  chambers,  sometimes  being  first  conveyed  to  an  ante-room,  where 
the  dtist  of  the  pyrites  mechanically  mixed  witli  the  gases  is  deposited. 

The  nitrous  acid  vapours  are  generated  in  a  manner  similar  to  that  used  lor 
sulphur.  It  will  be  seen  that  when  pyrites  is  burnt,  a  far  larger  qoantity  of  air  is 
required  for  the  same  quantity  by  weight  of  sulphur,  amounting  for  i  kilo,  of  pyrites 
to  6595  litres  of  air.  Tliis  excess  is  due  to  the  oxidation  of  the  ir<m  of  the  pyrites. 
and  the  large  bulk  of  nitrogen  accompanying  the  excess  of  oxygen 

(iFeSa-t-iiO=4SOj+Fej03). 
According  to  Fortman,  the  gases  from  the  pyrites  burners  also  contain  v^wiub  of 
anhydrona  snlphnric  acid.  Among  the  substances  found  in  the  Bne  dnst  of  the 
pyrites  burners  are  selenium  and  thallinm.  Carstanjen  found  thallimu  to  the  amomit 
of  3'5  per  cent  in  the  flue  dnst  of  a  snlphuiic  acid  works  near  Berlin,  where  > 
pyrites  from  Mezzen  was  used. 

.  ts  the  acid  formed  in  the  leaden  chamber*  has  acquired  a  sp.  gr,  ol 
=  104'  !rwaddle,it  is  run  off  into  a  reservoir,  and  is  freqaeutly  used  in  that  state 
atton  for  the  purpose  of  preparing  artificial  manures  or  superphosphates  u> 
alkali  works,  for  the  preparation  of  nitric  acid,  and  for  other  purposes.  This  add  ma;  be 
freed  from  arseiUD  by  treating  with  sulphuretted  hydrogen. 

'sSJSSrtS'idi  This  operation  is  effected  in  two  different  stages,  Ike  first  being  car- 
ried on  in  leaden  pans,  the  latter  in  platinum  or  glass  retorts.  Weak  and  cold  sul- 
phnric  acid  does  not  act  powerfully  on  lead,  but  as  soon  as  the  add  becomes  conceo' 
trated,  and  especially  when  hot,  the  lead  is  dissolved,  snlphnroos  acid  given  off,  aad 
snlphate  of  lead  formed.  Many  snlphnric  add  makers  concentralo  their  add  b> 
60°  B.=i7i  sp.  gr.,  in  leaden  pans;  others,  however,  concentrate  in  leaden  pans  to 
55°B.=  r59  sp.gr.  only. 


SULPHVB. 


ao7 


otooDtiuiaatitHAaFiiB.  The  pRUB  employed  for  this  purpose  are  rectAngnlor  in 
aliape,  rather  shallow,  bnt  long  ajid  wide,  and  supported  bj  iron  plates,  so  that  the 
fire  sbftU  not  strike  the  bottom  directly.  The  modes  of  placing  and  conatruction  are 
shown  in  Fig.  97 :  the  acid  is  more  stronglj  heated  in  the  pan,  m,  while  in  n  it  ia  only 


affected  by  the  hot  air  The  depth  of  the  acid  m  the  pans  vanes  £rom  24  to  36 
centime.  As  soon  ks  the  acid  is  of  about  171  sp  gr  ,  it  is  furtlier  deprived  of  its 
excess  of  water  in  plasa  porcelain  or  platinnm  vessels 

Fiiuniim  Bttcrta.  Platmnm  retorts  are  now  very  frequently  emplojed,  although  it  is 
dear  that  these  vessels,  considering  the  high  pnce  of  platmum,  are  expensive, 

Pio.  98. 


Messrs.  Johnson, 
among  the  best  makers  of  these 


the  price  depending  upon  the  weight  size  i 
Mfttthey,  and  Co.,  Hatton  Garden,  London  1 
and  other  platinum  apparatus. 

Fig.  9S  is  an  enlarged  view  of  the  platinum  retort,  represented  together  with  the 
leaden  pans  in  Fig.  97.    The  hearth  communicates  with  a.    By  means  of  the 


attains  to  310"  to  320",  Btrong  acid  ci 


i  e 


ao8  .  CESmCAL  TECHSOLOQY. 

Hfphon,  X,  the  acid  from  »  crji  be  transferred  to  b  ;  the  longer  leg  of  x  dipping  iolo  a 
leaden  veasel,  which  admits  of  being  lowered  to  d  by  the  aid  of  the  pulley.  The  acid  then 
runs  from  the  spnut  c  iuto  tlie  chaimel  d,  and  thence,  through  the  funnel-tube,  iolo 
the  retort,  b.  The  head,  c,  comraunicateH'  by  meaos  of  tabing.  not  shown  in  the  cut, 
with  a  worm,  where  the  water  and  very  weak  acid  mechanically  carried  over  with 
the  steam  are  condeiiBed.  When  the  temperature  of  the  acid  in  the  plalinnin  Btill 
T,  and  is  coudeneed  in  the  worm. 

In  order  to  withdraw  the  acid  froni 
the  Btill.  when  concentrated  to  178  to 
i-So  ( =  63°  to  66°B.},  theBroant  sjThon, 
F%.  99,  ia  Qscd.  It  iaauuleof  pUtinnin: 
the  enter  leg  has  a  length  of  sbonl 
5  metiCB,  and  is  snnoanded  by  a  ooppa 
tube  15  centime,  wide  by  36ceiitiiDB.  long, 
which  oan  bo  filled  at  a  from  the  tank  H 
(Bee  Fig,  97)  with  cold  water,  the  outlet 
for  the  hot  water  being  at  b.  Id  order 
to  increase  the  Bnrfoce  the  main  BjpkoD 
tnbe  Ib  divided  into  fonr  narrower  tobn. 
The  Ryphon  is  filled  with  snlphuic 
acid  by  d  and  t  after  dosing  the  tap  t. 
The  very  hot  acid  oools  wflle  floiriiig 
through  the  platinum  tnbes,  and  is  oollectad  in  jarE,  k,  a',  a". 
"SSntS'iSt'"  When  glass  retorts  of  good  quality  and  sufficiently  large  size  can  be 
obtained  at  a  cheap  rate,  they  are  very  frequently  employed,  being  placed  to  tbe 
number  of  ten  or  more  (Fig.  100)  in  saod-baths.    The  retorts  are  connected  Ja 

Via. 


earthenware  balloons,  in  which  the  acid  fames  are  condensed.  70  per  cent  of  tbe 
strong  snlphiuic  acid  sold  in  this  country  is  concentrated  in  glass  retorts.  Verf 
recently  cast-iron  vessels  have  been  used  for  concentrating  sulphuric  add, 
onumiuiodiiitsaiptiuie  Many  methods  of  pteparjng  Bulpbnrio  acid  have  been  sn^erted, 
Add  Humiutan.  ),□(  hitiierto  noue  have  anywhere  snperseded  the  prooesa  genenUj 
adopted.  For  this  reason  it  ig  oecewiary  to  mention  a  few  only  of  the  reaotiona  apeD 
which  these  methods  are  baaed.  Hohner  oiidiseB  snlphnrooB  add  with  chlorine,  care  being 
taken  that  steam  is  present  at  the  time  ;~ 

SnlphuronB  acid,  SOj    1  (o  1   u     ■  a    r,  an 

1  T»  ^  J      -  .  t   f  Snli>hunc  acid.  H>SO>. 


SULPHUR. 


2og 


Per80z*8  method  is  baaed  upon  the  following  reactions : — i.  Oxidation  of  stilphurons 
acid  by  means  of  nitric  acid,  the  latter  being  heated  to  ioo°  and  dilated  with  fonr  to  six 
times  its  bnlk  of  water.  2.  The  yaponrs  of  hyponitric  acid  are  again  converted  to  nitric 
acid  hy  the  oxygen  of  the  air  and  steam.  In  this  process  the  leaden  chambers  are  replaced 
by  a  series  of  large  stone- ware  Woolfe's  bottles.  Although  enormous  quantities  of  gypsum 
are  found  native,  all  attempts  to  prepare  sulphuric  acid  from  this  mineral  on  an  industrial 
scale  have  failed.  Gypsum  is  decomposed,  by  superheated  steam  and  at  red  heat,  into  sul- 
phuric acid,  oxygen,  and  sulphurous  acid,  leaving  caustic  lime  in  the  retort.  Shanks 
mixes  gypsum  with  chloride  of  lead  and  water  at  about  60°. 

f  Chloride  of  calcium,  CaCla, 
■  yield 


Gypsum,  CaS04-f2H20 
Chloride  of  lead,  PbCl^ 


Sulphate  of  lead,  PbS04, 
Water,  2H2O. 

The  chloride  of  calcium  solution  having  been  withdrawn  from  the  precipitate  of 
sulphate  of  lead,  the  latter  is  heated  with  hydrochloric  acid : — 

Sulphate  of  lead,  PbS04  )     .^, ,    ( Chloiijie  of  lead,  PbClj, 
Hydrochloric  acid,  2CIH  f  ^^^^   I  Sulphuric  acid,  H2SO4. 
PropertiM  of  Sulphuric  Acid.       The  most  highly  concentrated  sulphuric  acid  contains  18*46  per 
C€fnt  of  water;  its  formula  is  H2SO4;  sp.  gr.  =  1*848.    In  a  perfectly  pure  state  it  is  a 
eolourlees  Uquid,  but  commonly  is  more  or  less  yellow  or  brown,  owing  to  the  presence  of 
organic  matter.    It  destroys  many  organic  substances,  leaving  a  carbonaceous  residue. 
This  sulphuric  acid  does  not  fume  on  exposure  to  air ;  it  is  very  hygroscopic,  and  when 
left  exposed  to  air,  gradually  absorbs  fifteen  times  its  bulk  of  water.     When  mixed  with 
water  great  heat  is  evolved.  The  boiling-point  of  the  most  highly  concentrated  acid  is  338°. 
The  following  table  gives  the  quantity  of  anhydrous  sulphuric  acid  contained  in 
sulphuric  acid  at  15*5°  C. : — 


Hydrated      0 

Anhydro 

Sulphuric  acid.  ^^'  ^'' 

acid. 

100            ] 

[•8485 

81-54 

99            3 

[•8475 

80*72 

98            1 

[•8460 

79*90 

97            3 

f-8439 

7909 

96            1 

[•8410 

78*28 

95            J 

[•8376 

77*40 

94            3 

[•8336 

7665 

93             3 

t'8290 

75-83 

92            ] 

[•8233 

75*02 

91             ] 

[-8179 

74*20 

90            ] 

C-8II5 

73*39 

89            1 

f8043 

72-57 

88            ] 

[•7962 

71*75 

87            ^ 

[•7870 

70*94 

86             ] 

^7774 

70*12 

85             ] 

17673 

69-31 

84            : 

17570 

68*49 

83             ^ 

[•7465 

6768 

82            1 

C7360 

66*86 

81             ] 

[•7245 

66*05 

80            : 

t*7I20 

65*23 

79            3 

c-6993 

64*42 

78            ] 

[*6870 

63*60 

77            ^ 

[•6750 

6278 

Hydrated      q^  _ 
Sulphuric  acid.  "P'  ^• 


76 

75 

74 

73 

72 

71 
70 

69 
68 
67 
66 

65 
64 

63 
62 

61 

60 

59 
58 

57 
56 
55 
54 
53 


•6630 
•6520 

•6415 
•6321 

■6204 

*6o90 

•5975 
*5868 

•5760 
•5648 
•5503 
•5390 
•5280 

•5170 
*5o66 

'4960 

*486o 

•4760 

*466o 

-4560 

*446o 

•4360 

4265 

•4170 


Anhydrous 
acid. 

61*97 

61-15 

.  60*34 

59*55 
58-71 

57*89 
57-08 
57*26 

55*45 
54*63 
53-82 

53 'oo 
52*18 

51-37 

5055 

49-74 
48*92 

48*11 

47*29 

46-58 

45*68 

44-85 
45-03 
43*22 


ComparatiTe  degrees  of  Baum6  and  Twaddle,  with  the  corresponding  sp.  gr.  :- 


Degrees  Banm6. 
66 

63 
60 

57 
50 

45 
40 

35 
30 

25 


Degrees  Twaddle. 
168 

154 
140 

130 
104 

88 

76 

62 

52 

42 


Sp.gr. 

1*84 
1*77 
1*70 
1*65 
1*52 

1*44 
1*38 

1*31 

1*26 

1*21 


aio  CHEMICAL  TECHNOLOOY. 

The  Tender  dsBiroiis  of  mura  inforuiatioii  aa  to  the  specifio  grBvities  indicated  bj 
Banmi'B  hydrometerB  is  referred  to  the  "  Chemical  News,"  toI.  ixiv.,  p.  28,  el  teq. 

The  oaeB  of  Bnlphuric  acid  are  so  Dnmereua  that  it  voiild  be  im]>osiiible  to  meution  all 
of  them,  sulphuric  acid  being  to  chemical  induBtr;  what  iron  is  to  the  meohatiica], 
Bnlphuric  acid  is  employed  in  prepaiing  a  great  many  other  acids,  among  them  nitrio. 
hyi^iwhloric,  Bitlphtuoua,  carbouic,  tartaric,  citric,  phosphoric,  ateoiic,  oleic,  and  palmitic. 
Fnrther,  snlphmic  acid  is  nsed  ia  making  superphosphates,  soda,  Bolpbate  of  ammonia, 
alum,  anlphatea  of  copper  and  iron,  in  paraffin  and  petrolemn  refining,  silier  refining, 
manufacture  of  garnncine,  garanceoi,  and  other  madder  preparations,  manufacture  of 
glucose  from  starch,  to  di^BoWo  indigo,  dc. 


Sdlphide  of  Caruo^. 
sniiiiiida  of  cuboB.  This  compound,  consisting  in  loo  parts  of  158  ports  of  carbon 
and  84-2  of  gutphnr,  formula  CSj,  was  discovered  in  1796  by  Lampadius;  at  Frei- 
burg. It  ia  obtained  by  canainB  the  vapour  of  sulphur  to  pass  over  red-hot  coals,  or 
hy  distilling  an  intimate  mixture  of  native  metallic  sulphurcts  with  charcoal  or  coke. 
The  largest  quantity  of  sulphide  of  carbon  is  obtained,  according  to  Sidot  and 
W.  Stein,  at  not  too  high  a  red  heat,  that  is  to  say,  at  what  is  termed  in  gas-works 
orange-red  heat. 

Sulphide  of  carbon  is  best  manu&ctured   by  means  of  Peroucel's  apparatus 
(Fig,  ioi|.    A  is  a  fire-clay  gas-retort,  supported  on  the  fire-clay  block  b  ;  e  and  k 


lire  openings,  one  being  that  of  a  porcelain  tube  firmly  cemented  into  the  cover  of  >, 
serving  fur  the  introduction  of  sulphur ;  the  other  opening  is  for  the  introduction  of 
pieces  of  coke,  with  which,  before  the  operation  commences,  the  retort  is  filled- 
The  vapours  of  the  sulphide  of  carbon  pass  through  the  tubes  h  and  1  into  tbe 
vessel  J,  wherein  p&rt  of  the  sulphide  iscondensed  and  flowsthronghK  into  the  flask,  t. 
filled  with  wat£r,  thence  through  m  into  0,  finally  being  runoff  by  the  tap.  k.  Any 
vapours  not  condensed  in  j  pass  Uirough  p  p  into  the'  worm,  t,  the  condensed  sulphide 
being  collected  in  s.  The  crude  sulpliide  of  carbon  is  rectified  by  re.distilWion 
over  zinc  or  over  bichloride  of  mercury  by  means  of  steam  or  a  water-bath.  If  the 
bichloride  is  employcil.  the  crude  sulphide  should  remain  in  contact  with  the  salt  for 
at  least  twenty-four  hours  before  re -distillation.  With  the  apparatus  described,  the 
retort  being  21  metres  in  heiglit  and  03  metre  in  diameter,  2  cwts.  of  crude  sulphide 


HYDROCHLORIC  ACID.  2ii 

of  carbon  may  be  prepared  in  twelve  hours.  The  quantity  of  sulphide  resulting 
from  a  given  weight  of  materials  is  always  much  less  than  the  quantity  theoretically 
obtainable ;  this  is,  of  course,  partly  due  to  an  unavoidable  loss  of  liquid,  and  probably 
to  the  formation  of  monosulphide  of  carbon  (GS),  a  compound  corresponding  to 
carbonic  oxide.  Crude  sulphide  of  carbon  contains  usually  lo  to  12  per  cent  of 
sulphur  in  solution,  and  also  sulphuretted  hydrogen.  To  purify  the  crude  sulphide, 
bleaching-powder  solution  is  added  to  the  liquid  in  the  retort,  into  which  steam  at  15  lbs. 
pressure  is  forced  to  effect  the  reaction  between  the  chloride  of  lime  and  the  impuri- 
ties present  in  the  sulphide  of  carbon.  Sulphide  of  ccu'bon  is  usually  kept  under 
water.  When  pure,  sulphide  of  carbon  is  a  colourless  liquid,  strongly  refractive, 
exhibiting  extremely  bright  colours  when  in  the  sunlight.  Its  odour  somewhat 
resembles  that  of  chloroform;  the  taste  is  aromatic.  Its  sp.  gr.  =  1*2684;  the 
boiling-point  is  46' 5^,  consequently  the  liquid  is  very  volatile  at  the  ordinary  tempe- 
rature of  the  air. 

caxboD.  Sulphide  of  carbon  does  not  combine  with  water  or  spirits  of  wine.  It  is  not 
soluble  in  every  proportion  in  water  (see  "Chemical  News,"  vol.  xxiv.,  p.  34) ;  in  ether 
and  chloroform,  however,  it  is  freely  soluble.  Sulphide  of  carbon  is  an  excellent 
solvent  for  resins,  essential  and  fixed  oils,  caoutchouc,  gutta-percha,  camphor, 
sulphur,  phosphorus,  and  iodine.  It  is  highly  inflammable,  burning  with  a  red-blue 
flame ;  the  products  of  complete  combustion  are  sulphurous  and  carbonic  acids.  The 
vapour  of  sulphide  of  carbon  with  oxygen  or  air  constitutes  an  explosive  mixture  ; 
the  light  given  by  a  mixture  of  deutoxide  of  nitrogen  and  sulpliide  of  carbon  is 
very  intense,  and  has  been  employed  in  photography.  To  Mr.  Fisher,  of  Birmingham, 
is  due  the  honour  of  having  first  prepared  sulpliide  of  carbon  for  industrial 
purposes.  At  the  present  day  these  purposes  are  very  varied,  but  consist  chiefly  of 
the  vulcanisation  of  caoutchouc,  the  extraction  of  fat  from  bones,  and  oils  from  oil 
seeds  and  olives,  the  extraction  of  sulphur  from  its  concomitant  rocks,  and  of  fat 
from  crude  wool.  Sulphide  of  carbon  is  also  used  in  electro-plating  to  obtain  by  its 
addition  to  the  silver-bath  a  bright  and  polished  surface.  It  is  highly  valued  for 
killing  vermin  in  corn. 

chiozidA  of  soiphor.  Chlorido  of  sulphuT  (CI2S3),  important  only  in  its  technical  use 
for  the  vulcanising  of  caoutchouc,  is  an  oily  fluid,  sp.  gr.  i'6o,  of  a  brown  colour, 
fuming  on  exposure  to  air.  It  boils  at  144°.  On  being  mixed  with  water  it  is 
decomposed,  yielding  sulphurous  and  hydrochloric  acids,  a  very  small  quantity  of 
sulphuric  acid,  and  sulphur.  Chloride  of  sulphur  converts  rape -seed  oil  into  a  mass 
resembling  caoutchouc,  and  linseed  oil  into  a  varnish.  Chloride  of  sulphur  is 
prepared  bypassing  chlorine  gas  over  sulphur  heated  to  125''  to  130° ;  the  product  is 
rectified  by  distillation.  - 

Hydrochloric  Acid  and  Glauber's  Salt,  or  Sulphate  of  Soda. 

Hydnehiotie  Add.  The  Commercial  article  known  as  hydrochloric  or  muriatic  acid, 
or  spirits  of  salt,  is,  as  has  been  explained  in  the  manufacture  of  soda,  a  solution 
of  the  gas  given  off  during  the  decomposition  of  common  salt  by  sulphuric  acid. 
In  order  to  effect  this  condensation,  the  gas  is  conveyed  to  the  coke  columns,  or  in 
many  instances  is  prepared  and  condensed  by  the  aid  of  the  apparatus  shown  in 
section  in  Figs.  102  and  103,  and  in  plan  in  Fig.  104.  This  apparatus  consists  of 
several  cast-iron  cylinders,  17  metres  long  by  07  metre  diameter,  closed  similarly 

p  2 


Ill  CHEMICAL  TECHNOLOGY. 

to  gas  retorts  by  lids  luted  with  clay.  One  of  the  lide  ie  prorided  with  ui  opening, 
o,  into  which  is  fitted  the  stoneware  or  leaden  pipe,  a.  conveying  the  bydrochloTte 
acid  to  the  condensing  apparatus.  The  other,  or  posterior  lid,  is  also  provided  with 
an  opening,  d,  through  which  is  passed  the  tnbe  of  a  leaden  funnel,  bo  that  afi«i 
the  retort  u  filled  with  salt,  sulphuric  acid  may  be  poured  in.    The  c 


the  fnmace,  in  which  two  rotorts  are  usunUy  plated,  allows  the  flame  of  the  fire  tt 
o  to  play  ronnd  tho  cylindt^rs  before  rencliing  the  flue  leading  to  the  chimney,  r, 
B  is  an  arch  covering  the  furnace.  The  first  stage  of  the  operation  is  to  fill  each 
cylinder  with  15a  kilos,  of  salt  or  cliloride  of  potassium,  in  locahties  where  the  latter 
is  ahundant.     The  lids  or  covers  are  next  luted  on,  and  the  fire  kindled.    Ihe 


required  quantity  of  strong  sulphuric  acid  is  now  poured  into  the  retort,  and  tbo 
funnel  having  been  withilrawn  from  d,  the  hole  is  closed  by  a  clay  plug.  As  eoon 
as  the  reaction  is  over,  the  180  kilos,  of  sulphate  of  soda  produced  are  removed,  and 
the  operation  repeated.    The  condensation  apparatus.  Figs.  102  and  104,  consistB  oi 


GLAUBER'S  SALT.  213 

rows  of  Woolfe'B  bottles  partlj  filled  with  water,  care  being  taken  to  plfice  the  first 
pair  of  these  bottles  in  a  tank  of  cold  water.    The  condensation  of  the  last  portions 


of  the  hydrochloric  acid  gas  is  effected  either  by  the  aid  of  coke  columns,  or  in 
leaden  chambers,  into  which  fine  jets  of  cold  wat«r  nre  injected  on  all  aides. 

"'"''^  oi^rdiiidiiortd  Crude  commercial  hydrochloric  acid  is  commonly  a  yellow 
liquid,  this  colour  being  dae  to  chloride  of  iron.  It  hoa  a  caustic  sour  taste,  and 
fumes  on  exposure  to  air.  At  20°  water  is  capable  of  absorbing  475  times  its  own 
bnlk  of  hydrochloric  acid  gas :  a  saturated  solution  contains  4285  per  cent  of 
gas,  the  sp.  gr.  being  =  I'zi.  The  following  table  shows  the  sp.  gr.  of  hydrochloric 
add  at  Tarioos  degress  of  concenlration.  and  the  quantity  of  pure  acid  <reat 
gas)  contained  8(70°: — 

Specific    Degrees 

graTiQr.     Banm£.     ' 


Degrees 

Peroentage 

Specific 

Degrees 

Degrees 

PercentBgfi 

Twaddle. 

or  acid. 

grsTity. 

Baum£. 

Twaddle. 

of  acid. 

42 

4285 

10 

'45 

2o 

20  2O 

40 

4080 

09 

12 

18 

18  18 

38 

38S8 

08 

II 

16 

1616 

36 

3636 

07 

10 

14 

1414 

34 

34*34 

06 

9 

12 

1212 

3» 

3232 

05 

8 

10 

1010 

30 

3030 

04 

6 

8 

8-o8 

28 

2828 

03 

5 

6 

606 

26 

2626 

02 

3 

4 

404 

24 

24-24 

01 

2 

2 

2-02 

155 


Vmmit  H^^mjdwk  HydrocUoric  acid  is  very  largely  employed  in  the  manufacture 
of  chlorine,  sal. ammoniac,  chloride  of  antimony,  glue,  pbosphoms,  in  the  prepara. 
tion  of  carbonic  acid  for  the  manufacture  of  artificial  mineral  waters,  in  beet. root 
sugar  works,  bleach  works,  hydro-metallurgy,  and  alone  or  mixed  with  nitric  acid 
for  dissolving  various  metals. 

•uutwisiut.  Sulphate  of  soda,  or  Glauber's  salt,  consists  in  100  parts  of  193  soda, 
247  anlphimc  acid,  and  56  water ;  formula,  NajSOj+ioHjO;  anhydrous,  NoaSO^. 
in  too  parts — soda,  436;  sulphuric  acid,  56'4.  It  is  prepared  as  described  under 
hydrochloric  acid  by  decomposing  common  salt  with  sulphnric  acid.  It  is  also 
found  native  as  Thenardite  (Na,S04).  Brogniartine  or  GlanberiU  {NsiSOi+CaSO^I. 
and  it  occurs  in  sea-water  and  some  mineral  waters,  as  in  those  of  Pijltna  and 
Carlsbad. 


214  CHEMICAL   TECHNOLOGY. 

Sulphate  of  scMla  is  indirectly  obtained  by  yarioos  processes,  among  which   are — 

1.  The  doable  decomposition  of  common  salt  and  sulphate  of  magnesia  or  Ideserite  from 
the  mother-hquor  of  sea-water,  or  of  salines  when  exposed  to  a  low  temperature  either 
naturally  in  water  or  artificially  by  the  assistance  of  Oarr^*s  ice-making  machine. 

2.  Longmaid's  process  of  roasting  snlphnret  of  iron  or  copper  with  common  salt.  3.  Cal- 
cination of  Ideserite  or  magnesian  sulphate  with  common  salt.  4.  Kuhlmann's  process, 
the  calcination  of  sulphate  of  magnesia  and  nitrate  of  soda,  hyponitric  add  and  sulphate 
of  soda  being  formed.  5.  As  a  by-product  of  paraffin  and  petroleum  refining.  The 
sulphate  of  soda  of  the  alkali  works  contains  on  an  average  93  to  97  per  cent  of  the  pure 
salt,  the  remainder  being  chiefly  chloride  of  sodium. 

usM  of  soiphate  ^^^^  ^^  ^  extensively  employed  in  the  manufactures  of  soda,  ultra- 
of  Soda.  marine,  and  glass.  In  the  last  case  the  sulphate  is  mixed  with  coal  and 
silica,  and  calcined,  its  sulphuric  acid  being  reduced  to  sulphurous  acid,  which  is  Tolatilised, 
while  a  silicate  of  soda  is  formed.  Sulphate  of  soda  when  thus  employed  should  be 
purified  from  all  traces  of  iron  by  being  dissolved  in  water,  some  lime  added  to  the 
solution,  and  the  clear  liquid  evaporated  to  dryness.  Sulphate  of  soda  is  used  in 
metallurgy  in  the  treatment  of  some  kinds  of  antimonial  ores,  the  sulphuret  of  antimony 
found  near  Bouc  and  Septemes,  France,  &q.  It  is  also  employed  in  certain  processes  of 
wool-dyeing. 

BiBniphate  of  Soda.      ThiB  Salt  (NaHS04)  is  obtained  in  large  crystalB  when  i  molecule 

of  sulphate  of  soda  and  i  molecule  of  sulphuric  acid  are  dissolved  in  water  and 

the  solution  left  to  evaporate  slowly.    One  of  the  chief  uses  of  the  bisnlphate  is  in 

a  mixture  with  abramn  salt   containing   chloride  of  magnesium,  employed  for 

removing  zinc  from  lead.     As  a  by-product  sulphate  of  soda  is  obtained  in  the 

manufacture  of  nitric  acid  from  nitrate  of  soda  and  sulphuric  acid,  and  by  heating 

cryolite  with  sulphuric  acid. 

Bleachino-Powdeb  and  Hypochlobites. 

Chlorine.  It  is  oue  of  the  most  valuable  properties  of  chlorine  that  it  destroys 
organic  pigments  and  miasmata,  and  is  hence  useful  as  a  bleaching  agent,  and  as  a 
disinfectant.  It  is  also  employed  as  an  oxidising  agent  in  the  extraction  of  gold 
from  pyritical  ores. 

At  the  ordinary  temperature  and  pressure  of  the  atmosphere  chlorine  is  a 
greenish-yellow  gas,  its  sp.  gr.  =  133;  it  possesses  a  peculiarly  disagreeable, 
irritating  odour,  and  is  very  soluble  in  water,  i  volume  absorbing  25  volumes  of 
gas,  forming  the  well-known  V?^t/fi(  chlorii^  or  acidum  muriaticum  oxygenatum  aqita 
solutum  of  the  pharmaceutists,  and  the  chlorine  water  of  the  scientific  chemist. 
The  bleaching  property  of  chlorine  gas,  possessed  also  by  its  solution,  is  due  to  the 
great  affinity  of  clilorine  for  hydrogen,  so  that  the  chlorine  while  seizing  upon  the 
hydrogen  of  the  organic  body  in  most  instances  causes  the  simultaneous  decom- 
position of  water,  and  by  the  formation  of  ozone  destroys  the  organic  colouring 
matter,  hydrochloric  acid  being  at  the  same  time  formed,  a  fact  requiring  attention 
in  die  use  of  chlorine  as  a  bleaching  agent.  When  linen,  or  rather  flax,  raw  cotton, 
and  paper  pulp  are  bleached  by  clilorine,  the  fibre,  really  cellulose,  is  not  acted  upon, 
but  only  the  colouring  matter  is  oxidised  by  the  ozone  formed.  Chlorine  cannot  be 
used  to  bleach  animal  matters,  or  such  as  contain  nitrogen,  these  becoming  yellow 
by  its  action.  Chlorine  is  not  suited  for  transport  either  as  gas  or  in  aqueous 
solution,  therefore  one  of  its  combinations  with  oxygen  and  a  base,  viz.,  a  hypo- 
chlorite, is  used.  Hydrated  oxide  of  calcium  or  slaked  lime  is  the  chief  constituent 
of  bleaching-powder.     Usually  the  alkali  manufacturers  prepare  bleaching-powder. 

PreparaUon^o^BieacMng-  Bleachiug-powdcr  is  prepared  on  the  large  scale  in  the 
following  manner : — In  works  where  soda  and  chloride  of  lime  are  to  be  manu- 
factured simultaneously,  the  chlorine  is  obtained  by  mixing  the  common  salt  to  be 


BLEACHINQ'POWDER.  215 

converted  into  sulphate  of  soda  by  the  action  of  sulphuric  acid 'with  perojdde  of 
manganese,  heat  being  applied. 
The  process  is  as  follows : — 


Common  salt,  2NaCl, 
Peroxide  of  manganese,  MnOs, 
Sulphuric  acid,  2H2SO4 


yield 


Glauber's  salt,  Na^SO^, 
Sulphate  of  manganese,  MnSO^, 
.Chlorine,  2CI,  and  2H2O. 


In  some 'works  chlorine  is  prepared  by  the  reaction  of  hydrochloric  acid  and 

manganese,  and  sometimes  with  the  addition  of  sulphuric  acid.    In  the  first  instance 

only  half  the  chlorine  contained  in  the  hydrochloric  acid  is  given  up,  because  the 

other  half  forms  chloride  of  manganese ;  for — 

(Chlorine,  CU. 
yield       Manganic  chloride,  MnCl^, 
I  Water,  2H2O. 

In  the  second  instance  all  the  chlorine  contained  in  the  hydrochloric  acid  is 
obtained — 


Manganese,  MnOa, 
Hydrochloric  acid,  4CIH, 


Manganese,  MnO^, 
Hydrochloric  acid,  2CIH, 
Sulphuric  acid,  H2SO4, 


Sulphate  of  manganese,  MnS04, 
.  yield  \   Chlorine,  Cl^, 
Water,  2HaO. 


As  proposed  by  Clemm,  a  chloride  of  magnesium  solution,  as  largely  obtained  at 
Stassfurt,  may  be  employed  by  concentrating  the  solution  to  44°  B  (=1-435  SP-  gr). 
and  adding  manganese,  so  that  to  i  mol.  of  MnO^,  2  mols.  of  MgCl^  are  taken.  The 
cooled,  solid  mass,  when  exposed  to  the  action  of  superheated  steam  at  200°  to  300°, 
yields  chlorine  gas. 

'*^3tSi?Mi^2SeI°*      '^^  following  methods  are  selected  as  being  the  most  scientific 
and  interesting: — 

1.  Mac  Dougal,  Kawson,  and  Shanks's  process,  consisting  in  the  decomposition  of 
chromate  of  lime  by  hydrochloric  acid,  the  result  being  the  formation  of  chloride  of 
chromium,  chloride  of  calcium,  and  the  evolution  of  free  chlorine — 

(2CaCr04-fi6HCl=CraCl6-f2CaCl2+3H20+6Cl). 
158  parts  of  chromic  acid  3deld  106  parts  of  chlorine.    The  chloride  of  chromium  is 
again  precipitated  with  carbonate  of  lime,  and  by  ignition  converted  into  chromate  of 
lime.     Only  three-eighths  of  the  chlorine  contained  in  the  hydrochloric  acid  is  given 
up,  while  manganese  yields  one-half. 

2.  Schlosing's  method  consists  in  acting  upon  manganese  with  a  mixture  of  hydro- 
chloric and  nitric  acids,  the  degree  of  concentration  of  the  acids  being  so  regulated  by 
the  addition  of  water  that  the  mixture  yields  only  chlorine,  whUe  nitrate  of  protoxide 
of  manganese  is  formed ;  this  salt  being  calcined  yields  manganese,  peroxide,  and 
nitric  acid.  The  nitric  acid  aids  the  oxygen  of  tlie  air  in  decomposing  the  hydro- 
chloric acid.  The  nitrate  of  manganese  begins  to  decompose  at  150°,  and  the  decom- 
position is  completed  at  175°  to  180**,  yielding  much  peroxide,  in  some  cases  even 

93  P^'  cent. 

3.  Vogel's  method  of  decomposing  chloride  of  copper  by  heat.  3  mols.  of 
chloride  yield  i  mol.  of  chlorine  ;  according  to  Laurens  the  process  is : — 

2CuCla=Cla+Cu2Cla. 
The  chloride  in  crystalline  state  is  mixed  with  haK  its  weight  of  sand,  and  heated  in 
earthenware  retorts  to  200°  to  300°,  yielding  chlorine  gas,  while  the  remaining  proto- 
chloride  of  copper  is  re-converted  into  percliloride  by  the  action  of  hydrochloric 
acid.    Mallet  has  constructed  a  peculiar  rotating  apparatus  for  the  decomposition  of 


2i6  CHEMICAL   TECHNOLOGY. 

this  salt,  the  same  apparatus  serving  to  prepare  oxygen.     loo  kHos.  of  capric 
chloride  yield  6  to  7  cubic  metres  of  chlorine  gas. 

4.  P61igot's  method.  When  3  parts  of  bichromate  of  potassa  and  4  parts  of  con- 
centrated hydrochloric  acid  are  gently  heated,  the  fluid  yields  on  cooling  crystals  of 
bichromate  of  chloride  of  potassium,  KCl,0r03 ;  at  100°  this  salt  yields  chlorine. 

5.  Dunlop's  process  is  followed  at  Mr.  Tennant's  works,  Glasgow.  Sulphuric  acid 
is  made  to  act  upon  a  mixture  of  3  mols.  of  common  salt,  and  i  mol.  of  nitrate  of 
soda,  the  result  being  the  formation  of  chlorine  and  hyponitric  acid.  The  latter  is 
absorbed  by  passing  the  mixed  gases  through  strong  sulphuric  add. 

6.  Mr.  Walter  Weldon's  process  is  performed  by  means  of  an  apparatus  eomprising 
fiye  yesselB  arranged  at  snccesBiye  eleyations,  so  that  after  haying  been  pimiped  up  to  tiie 
highest  of  them,  the  liquor  operated  upon  can  afterwards  descend  to  all  the  others  by  its 
own  gravity.  The  lowest  of  these  yessels  is  a  well,  which  is  furnished  with  a  mechanical 
agitator.  The  slightly  acid  chloride  of  manganese  liquor  with  which  the  process  com- 
mences runs  from  the  stills  in  which  it  is  produced  into  this  well,  and  is  there  treated  with 
finely  divided  carbonate  of  Hme,  the  action  of  which  is  facilitated  by  the  energetie 
agitation.  When  the  neutralisation  of  the  free  acid  which  is  at  first  contained  in  this 
liquor  and  the  decomposition  of  the  sesquichloride  of  iron  and  sesquiohloride  of  aluminium, 
which  are  also  at  first  contained  in  it,  are  completed,  the  liquor  is  pumped  up  into 
settling  tanks,  placed  nearly  at  the  top  of  the  apparatus,  and  known  as  the  "  chloride  of 
manganese  settlers.'*  It  now  consists  of  a  quite  neutral  mixed  solution  of  chloride  of 
manganese  and  chloride  of  calcium,  containing  in  suspension  considerable  quantities  of 
sulphate  of  lime,  and  small  quantities  of  oxide  of  iron  and  alumina.  These  solid 
matters  rapidly  deposit  in  the  chloride  of  manganese  settlers,  leaving  the  bulk  of  the 
liquor  perfectly  bright  and  clear,  and  of  a  faint  rose-colour.  The  next  step  is  to  run  off 
the  clear  portion  of  the  contents  of  the  settlers  into  a  vessel  immediately  below,  called 
the  oxidiser.  This  is  usually  a  cylindrical  iron  vessel  about  12  feet  in  diameter,  and  about 
22  feet  deep.  Two  pipes  go  down  nearly  to  the  bottom  of  the  oxidiser,  a  luge  one  for 
conveying  a  blast  of  air  from  a  blowing  engine,  and  a  smaller  one  for  the  injection  of 
steam.  The  latter  is  for  the  purpose  of  raising  the  temperature  of  the  contents  of  the 
oxidiser  when  necessary;  for  sometimes  the  chloride  of  manganese  liquor  reaches 
the  oxidiser  sufficiently  hot — between  130°  and  160°  or  170°  F.  Immediately  above  the 
oxidiser  is  a  reservoir  containing  milk  of  lime.  The  oxidiser  having  received  a  charge  of 
clear  liquor  from  the  settlers,  and  this  liquor  having  been  heated  up  to  the  proper  point,  if 
it  was  not  already  hot  enough,  blowing  is  begun,  and  milk  of  lime  is  then  run  into 
the  oxidiser  as  rapidly  as  possible,  until  the  filtrate  from  a  sample  taken  at  a  tap  placed 
nearly  at  the  bottom  of  the  oxidiser,  ceases  to  give  a  manganese  reaction  with  solution  of 
bleaching-powder.  A  certain  quantity  of  milk  of  lime  is  then  added,  and  the  blowing 
continued  until  peroxidation  ceases  to  ^vance.  That  point  is  usually  attained  when 
from  about  80  to  85  per  cent  of  the  manganese  present  has  become  converted  into 
peroxide.  The  contents  of  the  oxidiser  are  now  a  thin  black  mud,  consisting  of  solution 
of  chloride  of  calcium  containing  in  suspension  about  2  lbs.  of  peroxide  of  manganese 
per  cubic  foot,  these  2  lbs.  of  peroxide  of  manganese  being  combined  with  varying  quan- 
tities of  protoxide  of  manganese  and  lime.  This  thin  mud  is  now  run  off  from  the 
oxidiser  into  one  or  other  of  a  range  of  settling  tanks  or  "  mud  settlers,"  placed  below  it, 
and  is  there  left  at  rest  untU  it  has  settled  as  far  as  it  will,  usually  until  about  one-half  of 
its  volume  has  become  clear.  The  clear  part  is  then  decanted,  and  the  remainder, 
containing  about  4  lbs.  of  peroxide  of  manganese  per  cubic  foot,  is  then  ready  to  be  used 
in  the  stills.  There  it  reacts  upon  hydrochloric  acid,  liberating  chlorine,  with  repro- 
duction of  exactly  such  a  residual  solution  as  was  commenced  with.  With  that  sointicai 
the  round  of  operations  is  begun  again ;  and  so  on,  time  after  time,  indefinitely. 

Apparatw^fo^PrepMiiiij      When  hydrochloric  acid  and  manganese  are  used,  the  apparatus 

is  that  delineated  in  Fig.  105.    It  consists  of  a  large  stoneware  jar,  a,  provided  with 

an  opening,  a,  over  which  an  air-tight  cap  is  fitted  when  the  apparatus  is  at  work,  and 

by  which  the  jar  is  filled  with  manganese  and  acid ;  h  is  another  opening  fitted  with 

a  leaden  or  cartlienware  gas  tube ;  c  is  a  tube  serving  to  run  oflf  the  spent  manganese 

liquor,    b  is  a  wooden  box  into  which  steam  is  admitted  for  the  purpose  of  heating 

A  and  its  contents  sufficiently  to  promote  the  reaction  between  the  hydrochloric  acid 

and  the  manganese. 


BLEACBWaPOIFDEB. 


"7 


When  ahloTine  ii  prepured  from  a  miitiire  of  common  salt,  gnlphorio  acid,  Mid  man- 

gueae.  the  apparatiu  is  reqnired  to  withstand  more  heat,  and  is  therefore  oonBtmoted 
(ntireJy  of  metal.  ao,Pig.  106,  is  a  shallow  iron  pan,  fitted  with  the  tnbe  6  (or  the  pnrpose 
cf  smptjing  the  oontents  of  the  leaden  cjlinder,  dd.  This  iron  Teesel  serves  aa  the  lower 
part  of  the  leaden  cylinder,  dd,  the  top  of  whioh  is  previded  with  an  opening  for  a 
fonnel  sjphon-tabe  for  the  intiodnction  oi  the  aoid,  and  another  opening,  /,  (or  the  jnan- 
gueH.    The  entire  apparatna  stands  on  a  Qne  leading  from  a  (nmace. 


'>»^a'iii«  Appunui.  The  ehlerine  passes  from  the  generator  throngh  the  tube,  u, 
K%.  107,  into  a  room  oonstmotod  of  large  blooks  and  slabs  of  eandstone  joined  b;  means 
of  asphalt  oement,  or  a  miitnre  of  coal-tar  and  fire-cla;.  Sometimes  the  room  is  built 
of  brieks  laid  in  a  similar  cement,  the  interior  being  lined  with  asphalt ;  leaden  chambers 
also  are  nsed  for  thiB  pnrpoBe.  The  room  ia  fitted  with  several  ahelrea  npon  which  slaked 
time  ii  plaoed  in  lajera  o(  three  to  (onr  inches  and  more  in  thickness.    The  chlorine  gas 


ii  teadily  abtorbed;  best  being  erolTed.  Care  is  to  be  taken  tbat  the  temperature  does 
not  exceed  25°,  because  then  oblorate  ol  lime  is  formed ;  this  is  prevented  by  admitting 
the  gas  slowfy.  As  soon  as  the  absorption  ceases,  the  bleaching'powder  is  removed  with 
rakes  from  the  shelves,  and  fresh  lime  intrednced.  Frequently  the  chloride  o(  time  is 
lomewbat  diluted  by  an  admixttire  of  elaked  lime. 

When  it  ia  desired  to  prepare  a  aolntion  of  chloride  of  lime,  the  apparatna  shown  in 
Fig.  loS  is  employed.  Two  or  four  earthenware  vessels,  i,  about  2  hectohtres  capacity, 
•re  placed  in  the  leaden  trough,  a,  the  bottom  of  whioh  is  protected  by  a  cast-iron  plate 
and  a  stoneware  slab,  r,  from  the  direct  action  of  the  fire  at  ».     "  '" 


2l8 


CHEMICAL  TECHNOLOOT. 


trated  solation  of  chloride  of  calcium  Beiring  the  pnrpoBeot  abatli,such  a  BolDtion  boUing 
at  i79'5°.  Bj  the  syphon  Jiuinel,  k,  the  hjdroohiorio  Mid  ia  ponied  into  t.  i  is  ■  per- 
forated cietem  filled  with  manganese.  » ia  the  leaden  gaa  tabo.  The  chlorine  being  firtt 
washed  in  b,  pasBSB  throngh  n  into  r,  filled  -nitb  pieces  of  tnanganOBe,  to  deeompou  ui; 
Tsponrs  of  hydrochloric  acid  carried  otot,  and  laetl;,  the  chlorine  pasdug  throngh  » 
reaohes  the  abBorption  Teasel,  s.  This  Tesael  is  a  lead-lined  wooden  cask,  fitted  with  an 
axle  bearing  spokes  to  whieh  are  fastened  gntta-peroha  floats.  The  bearing  and  phunmer. 
blocks  of  the  ails  are  made  of  gnaiaonni  wood  and  ebonite.  The  aile,  o,  gears  with  a  Bait, 
able  motive  power,  the  purpose  being  to  keep  the  milk  of  lime  in  coatinnovw  motion  while 
the  gas  is  being  admitted. 

Fro.  loS. 


The  chlorine  gaa  enters  above  the  level  of  the  flmd,  which  is  kept  constantly  atirred.  Id 
assist  in  the  absorptioii  From  the  Teasel  wherem  the  absorption  tl^es  plaoe  a  small  tnbe 
leads  into  another  yessel  filled  with  water  to  a  depth  of  iS  to  24  centuns  ,  a  tnbe  fitted 
to  this  Teasel  leads  into  the  open  air  to  conTe;  away  anT  onabsorbed  ohlonne.  &b  in  the 
preparation  of  solid  chloride  of  lime,  it  is  here  necesaary  to  gnard  against  an  incresM  in 
temperature  and  also  satoratioQ;  Schlieper  has  proved  that  too  oonoentrated  solntions 
evolve  oxygen,  while  too  dilate  solutions  yield  ohlorata  of  lime. 

""ptSf^^BrJSS?"  -^  '^^  chlorine  required  for  the  preparatioii  of  chloride  of 
lime  is  generallj  obtained  b;  the  aid  of  manganese  and  hydrochloric  acid,  the  resi- 
dnes  consist  chiefly  of  free  acid  and  protochloride  of  manganese.    The  principal 

suggeationB  ae  to  the  utilisation  of  these  substances  are : — 
a.  Those  aiming  at  the  regeneration  of  peroxide  of  manganese ;  and 

0.  Those  not  proceeding  with  this  view.    The  former  are  of  course  the  more 

important. 
DmiiiiF'i  PnmH.  This  process  ia  one  of  the  oldest  and  the  best,  excepting  perbapa, 
Batmain's,  in  which  the  chloride  of  manganese  ia  neutraliaed  with  the  ammoniaoal  nter 
of  gai-works,  the  sapematant  liqnor  being  employed  tor  preparing  sal-ammoniac,  irtiile 
the  precipitate  ia  ignited  in  a  reverberatory  fomace  and  converted  into  peroride  of 
manganese.  Dnnlop'a  process,  as  practiaed  at  Tennant'a  works  at  Glasgow,  is  based  upon 
the  fact,  first  observed  by  Forchhammer,  that  carbonate  of  manganese,  when  heated  la 
260°,  is  converted  into  peroride  of  manganese  ;  that  is,  the  carbonic  acid  is  driven  off, 
and  the  compoond,  xUsOi-i-MdO,  obtained.  The  proceaa  oonaiats  in  the  foUowiog 
operations : — 

1.  Converaion  of  the  ohloride  of  manganese  into  carbonate  of  manganese. 
3.  Conversion  of  the  carbonate  into  peroxide  of  manganese. 

To  the  chlorine  preparation  residoes.when  they  have  become  clear,  either  chalk  or  milk 
of  lime  ia  added  to  nentraliao  the  exccaa  of  acid  and  precipitate  the  oride  of  iron.  Thil 
precipitate  haring  settled,  the  clear  liquid,  a  rather  pare  solution  of  protocblorideof  maa- 
ganeae,  is  poured  into  shallow  troughs  and  intimately  mixed  with  finely  powdered  etulk. 
The  magma  thus  formed  ia  transferred  for  further  deoompotitioQ  to  a  large  eOBt-iron 
tronnh,  sy  metres  long  by  3  metres  wide.     Parallel  to  the  length  of  this  vessel,  a  stent 


wionght-uoD  axle  is  corned,  to  which  a 


I  fitted  ci 


1  branches  serving  aa  stiiref. 


BLEACHING-POWDER,  219 

The  axle  passing  through  stuffing  boxes  at  each  end  of  the  trongh,  gears  with  a  motive 
power,  whereby  the  stirrers  are  caused  to  keep  the  chalk  constantly  suspended  in  the 
manganese  solution.  High  pressure  steam  is  conveyed  into  the  trough  and  aids  decom- 
position. The  carbonate  of  manganese  obtained  is  freed  by  washing  from  chloride  of 
caldum,  and  having  been  well  drained,  is  calcined  in  a  peculiarly  constructed  furnace,  in 
which  the  carbonate  is  first  dried  on  a  higher  stage,  and  then  is  transferred  to  a  lower  and 
hotter  stage,  where  oxidation  is  commenced.  The  oxidation  is  completed  at  the  lowest 
stage  of  the  furnace,  to  which  plenty  of  air  is  admitted.  The  fire-place  is  constructed  to 
pdmit  of  the  regulation  of  the  heat  with  great  nicety,  because  too  high  a  temperature  would 
cause  the  formation  of  protosesquioxide,  and  too  low  a  temperature  would  leave  the 
carbonate  undecomposed. 

G«tt7^pn)O0«.  In  this  process  the  residues  are  converted  into  nitrate  of  manganese, 
which  is  next  decomposed  by  heat.  The  residues  are  evaporated  to  the  consistency  of  a 
symp,  and  mixed  with  nitrate  of  soda : — 

To  76  kUos.  of  protoidOoride  of  manganesej  ^^  ^^^  ^^  ^.^^^^^  ^,  ^^  ^  ^^^ 
and  to  95  kilos,  of  sulphate  of  manganese  J 
The  mixture  is  dried,  and  then  heated  to  a  dull  red  heat  in  an  iron  retort,  the  fumes  of 
nitric  acid  given  off  being  used  in  the  manufacture  of  sulphuric  acid.  The  residue  in  the 
retort  consists,  according  to  the  salt  of  manganese  employed,  of  peroxide  of  manganese 
and  chloride  of  sodium  or  sulphate  of  soda ;  it  may  be  lixiviated  with  water  to  obtain  the 
peroxide  of  manganese  in  a  pure  state  if  sulphate  of  soda  is  present. 

Hotnuiui'i  proeeas.  The  procossos  of  regenerating  manganese  by  the  application  of  soda 
waste  are  more  important  than  the  preceding.  In  Hofmann's  process  the  protochloride 
of  manganese  is,  by  tihe  addition  of  the  yellow  ley  obtained  from  the  lixiviation  of  soda 
waste  converted  into  sulphuret  of  manganese.    The  precipitate,  consisting  of — 

Sulphuret  of  manganese     55 'oo 

Sulphur 40*00 

Protoxide  of  manganese     5*00 

100*00 

is  dried  and  calcined,  the  sulphurous  acid  given  off  being  led  into  the  sulphuric  acid 
chambers.    The  remaining  residue,  consisting  of — 

Sulphate  of  manganese 44*5 

Peroxide  of  manganese 18*9 

Protoxide  of  manganese        36*6 


ioo*o 

is  next  mixed  with  nitrate  of  soda  and  heated  to  300^,  yielding  sulphate  of  soda  and 
nitrate  of  manganese,  the  latter,  however,  being  at  once  decomposed  into  peroxide  of 
manganese  and  hyponitric  acid : — 

a.  MnS04+2NaN03=Mn(N03)2+NaaS04; 
p.  Mn(N03)  +  MnOa+2N02. 

After  the  mass  has  cooled,  the  sulphate  of  soda  is  removed  by  lixiviation,  the  residue 
yielding  a  material  free  from  iron,  and  according  to  the  inventor,  equal  to  native  manganese. 

Wddon's  Froisen.  To  the  residue,  consisting  of  protochloride  of  manganese,  are  first 
^ded  for  every  molecule  of  that  salt  2  molecules  of  hydrate  of  lime.  Into  this  magma,  con- 
sisting of  hydrate  of  protoxide  of  manganese,  hydrate  of  lime,  and  chloride  of  calcium,  air 
is  forced,  tiie  effect  being  that  the  manganese  is  rapidly  higher  oxidised,  and  forms 
ealciom-manganite  (CaMn03,  or  MnOa.CaO),  which,  having  subsided,  and  the  supernatant 
chloride  of  calcium  solution  being  run  off,  is  ready  for  chlorine  making  by  the  addition  of 
hydrochloric  acid.  The  same  process  is  repeated,  and  even  a  change  of  vessels  is  not 
required.    (See  p.  216.) 

oocr  Methods  of  utuiiing  /3-  Utilisation  of  the  residues  without  regeneration  of  the 
tha  BMidaei.  peroxide  of  manganese.    M.  Schaffner,  at  Aussig,  precipitates  the 

protochloride  of  manganese  with  lime,  dries  the  precipitate,  and  calcines  it  in  a  rever- 
beratory  furnace,  obtaining  protosesquioxide  of  manganese,  employed  with  iron  ore  in  the 
blast  furnace.  The  solution  of  chloride  of  calcium  simultaneously  obtained  is  precipi- 
tated by  sulphuric  acid,  yielding  the  material  known  as  anruUine;  that  is  to  say,  the 
gypsum  used  in  paper  manufacture.  In  the  process  of  soda-making  from  sulphuret  of 
sodium  and  iron,  as  suggested  by  Malcherbe  and  improved  upon  by  Eopp,  for  the  oxides 
snd  carbonate  of  iron,  the  corresponding  manganese  compounds  may  be  substituted. 
Carbonate  of  manganese  may  be  used  to  convert  sulphuret  of  sodium  into  soda,  and  may 
also  serve  for  the  preparation  of  permanganates.    A.  Leykauf  suggests  that  the  residues 


220  CHEMICAL  TECHNOLOGY. 

of  chlorine  manofaotnre  shonld  be  employed  to  form  a  yiolet-eolonred  paint,  known  as 
Nuremberg- violet,  a  compound  of  ammonia,  oxide  of  manganeee,  and  phosphoric  add. 
In  England  the  residues  are  frequently  employed  in  tiie  purification  of  coal-gas  and  as 
disinfectants. 

'^iSidSiSS^!*"      When  chlorine  gas  and  slaked  lime  (hydrated  oxide  of  calcium, 

CaEEsOa)   are  brought  in  contact,  a  portion  of  the  oxygen  of  the  lime  combines 

with  the  chlorine,  forming  hypochlorous  acid,  which,  combining  with  the  nndecom- 

posed  lime,  forms  hypochlorite  of  lime,  while  another  equivalent  of  chlorine  combines 

with  the  deoxidised  lime  (calcium)  forming  chloride  of  calcium : — 

Hydrate  of  lime,  zCaH^Oa,!     -  „  {^^f""^^  of  lime  Ca(aO)^ 
Chlorine.  2CI,,        ^  *' J  3^  jmte"  1^0     "^    ^^' 
This  bleaching-powder  consists  in  100  parts  of : — 

Hypochlorite  of  lime      49'3i 

Chloride  of  calcium 38*28 

Y*aiiei&  •••     •••     •••     ••«     •••     «••     ■•■     ••■     •••     12  4' 


lOO'OO 


or  of- 


v^nLo^me  •••  •••  ••■  •••  •••  •••  ■•■  ••■  40  QO 

1  Jl  lIlH   a, a     ««a     ,,,     aaa     •••     •••     •••     ■•■     •■•    3    ^^7 

TvaL6r**a  •■•  •••  •••  •••  •••  ••■  •••  ■■•  12  41 

1 0000 
A  bleaching-powder  of  this  theoretical  composition  does  not  and  cannot  occur  in 
the  trade ;  a  good  sample,  containing  26*52  per  cent  of  active  chlorine  was  composed 
as  follows : — 

Hypochlorite  of  lime       2672 

Chloride  of  calcium 25*51 

I  iiiii.e  •••  •••  •••  •••  •••   •••   •••   ••■  ■••  23  03 

Water  of  composition  and  moisture      2472 

lOO'OO 

This  analysis  may  be  more  intelligible  by  the  following  arrangement : — 

Hypochlorite  of  lime      2672 

Active  chloride  of  calcium 
Excess  of  chloride  of  calcium. 
Hydrate  of  lime        


2072 

479 
3046 


Water  of  composition  and  moisture      i7'3i 

lOO'OO 

According  to  Dr.  Fresenius  (1861),  bleaching-powder  is  a  mixture  of  i  molecule  of 
Ca(C10)2  and  2  molecules  of  basic  chloride  of  calcium,  CaCl2,2CaHa0a+2Ha0. 

*'«»p«***^,JJ™*****^*  Bleaching-powder  is  a  white,  rather  moist  powder,  consistiBg 
of  hypochlorite  of  lime,  chloride  of  calcium,  and  excess  of  slaked  lime.  10  parts  of 
water  dissolve  the  bleaching  material,  leaving  the  excess  of  lime ;  the  chlorine 
contained  in  the  chloride  of  calcium  also  acts  as  a  bleaching  agent,  as  on  adding  sn 
add  to  the  bleaching-powder  the  hypochlorous  add  set  free  reacts  upon  the  hydro- 
chloric add  evolved  from  the  chloride  of  caldum,  forming  water  and  chlorine : — 

(glo+g|=glo+g}) 


BLEACHINQ-POWDER.  221 

The  bleaching  power  of  chloride  of  lime  does  not  come  immediately  into  play 
unless  an  acid  is  added ;  this  property  is  turned  to  account  in  the  producing  of  white 
patterns  upon  fjeibrics  dyed  turkey-red,  by  printing  the  pattern  in  a  thin  paste  of  tar- 
taric acid,  the  fEibiic  being  afterwards  immersed  for  a  few  minutes  in  a  solution  of 
hjpochlorite  of  Hme.  Instead  of  employing  acids  for  setting  the  chlorine  free  from 
chloride  of  lime,  sulphate  or  chloride  of  zinc  may  be  substituted,  the  result  being 
that  gypsum  and  oxide  of  zinc  are  precipitated,  yrhile  hypochlorous  acid  remains  in 
solution.*  The  yarious  industrial  uses  of  bleaching-powder  have  already  been  men- 
tioned. Chloride  of  lime,  as  bleaching-powder  is  generally  termed  in  this  country, 
is  sometimes  used  for  the  preparation  of  oxygen,  i  Idlo.  (of  the  formula  Ca(G10)2), 
yielding  132*2  grms.=92'4  litres  of  oxygen. 

cuoriBMtiy.  As  the  value  of  a  sample  of  chloride  of  lime  depends  upon  the  quantity 
of  the  really  active  chlorine  and  hypochlorous  acid  it  contains,  methods  have  been 
devised  for  ascertaining  with  a  greater  or  less  degree  of  accuracy  the  quantity  of 
these  active  agents.  Formerly  the  test  was  the  discolouration  of  a  certain  quantity 
of  indigo  solution  by  a  certain  quantity  of  bleaching-powder  solution,  as  compared 
with  the  action  of  chlorine  upon  indigo,  but  it  is  clear  that  this  method  could 
not  yield  accurate  results. 

o«^LM«giaiflKWMtite  Tj^g  eminent  savant  makes  use  of  the  oxidising  action  of 
chloride  of  lime  upon  arsenious  acid,  a  volume  of  dry  chlorine  gas  dissolved  in 
water  being  employed.  The  solution  of  chlorine  is  poured  into  a  graduated  tube 
divided  into  100  parts,  each  of  these  divisions  corresponding  to  one-hundredth  of 
chlorine.  A  solution  of  arsenious  acid  in  dilute  hydrochloric  acid  is  also  prepared, 
the  strength  of  the  solution  being  such  that  equal  bulks  of  the  two  liquids  suffer 
mutual  decomposition: — 

Arsenious  add,  Asa03,' 

.  yield 


Water,  2H3O, 
Chlorine,  2CI2, 


Arsenic  acid,  Asa05, 
Hydrochloric  acid,  4CIH. 


Water  is  decomposed ;  its  oxygen  combines  with  the  arsenious  acid,  forming  arsenic 
acid,  while  the  hydrogen  combines  with  the  chlorine.  Usually  i  litre  of  dry  chlorine 
gas  is  dissolved  in  i  litre  of  distilled  water.  The  normal  solution  of  arsenious  acid 
is  so  prepared  that  it  is  entirely  decomposed  by  the  chlorine  water  to  arsenic  acid. 
The  test  is  carried  out  as  follows : — Take  10  grms.  of  the  sample,  and  triturate  with 
distilled  water,  adding  sufficient  of  the  latter  to  make  up  a  litre.  Next  take,  by 
means  of  a  graduated  pipette,  10  c.c.  of  the  arsenious  acid  solution,  and  pour  it 
into  a  beaker,  adding  a  drop  of  indigo  solution  to  impart  a  faint  colour ;  next  add, 
hy  means  of  a  burette,  sufficient  of  the  bleaching-powder  solution  to  cause  the 
colour  nearly  to  disappear,  then  add  more  of  the  indigo  solution,  and  again  bleaching- 
powder  solution,  until  the  fluid  becomes  quite  colourless.  The  normal  arsenious 
acid  solution  is  prepared  by  dissolving  44  grms.  of  this  add  in  32  grms.  of  hydro- 
chloric add,  the  liquid  to  be  diluted  to  i  litre.  If  10  grms.  of  bleaching-powder  con- 
tain I  litre  of  chlorine  gas,  it  is  of  100  degrees  strength. 

Pnot'B  T«rt.      Penot  has  modified  Gay-Lussac's  method  in  the  following  particulars : — 
For  the  arsenious  acid  solution  he  substitutes  arsenite  of  soda,  and  for  the  indigo 

*  Explosions  have  oconrred  from  bleaching-powder  being  kept  in  too  tightly  dosed 
vessels,  due  to  spontaneous  deoompodtion,  (Ca(C10)2+CaCl2=2Ga0l2+02).  As  a  pre- 
vention it  is  suggested  that  the  powder  should  be  ground,  packed  in  casks,  and  strongly 
pressed  into  a  hard  mass. 


222  CHEMICAL   TECHNOLOGY, 

solution  a  colourless  iodised  paper,  which  is  turned  blue  by  the  smallest  quantity  of 
free  acid.  The  paper  is  prepared  in  the  following  manner: — i  grm.  of  iodine* 
7  grms  of  carbonate  of  soda,  3  grms.  of  starch,  and  \  litre  of  water  are  mixed.  When 
the  solution  becomes  colourless,  it  is  diluted  to  i  a  litre ;  in  this  fluid  white  paper  is 
soaked.  The  arsenical  fluid  is  prepared  by  dissolving  444  grms.  of  arsenious  acid, 
and  13  grms.  of  crystallised  carbonate  of  soda  in  i  litre  of  water.  This  solution  is 
poured  by  means  of  a  burette  into  the  solution  of  the  chloride  of  lime  intended  to 
be  tested  (10  grms.  of  the  sample  to  i  litre),  the  completion  of  the  reaction  being 
known  by  the  paper  remaining  uncoloured.  Mohr,  again,  has  modified  this  process,  in 
not  however  very  essential  particulars. 

Dr.  w»gnert  Mathod.  TMs  test,  discovered  in  1859,  is  the  so-called  iodometrieal 
methodf  and  is  based  upon  the  fact  that  a  solution  of  chloride  of  lime  separates  the 
iodine  from  a  weak  (i  to  10)  and  slightly  acidified  iodide  of  potassium  solution,  the 
iodine  being  quantitatively  estimated  by  means  of  hyposulphite  of  soda : — 


Iodine,  2I, 

Hyposulpliite  of  soda,  2NaaSa03+5H30, 


yield 


\  [Iodide  of  sodium,  2NaI, 

'  Tetrathionate  of  sodium,  NaaS406i 
.Water,  sHaO. 

The  test  is  thus  executed : — 100  c.c.  =  i  grm.  of  bleaching-powder  solution* 
obtained  by  dissolving  10  grms.  of  chloride  of  lime  in  i  litre  of  water,  are  mixed 
with  25  c.c.  of  solution  of  iodide  of  potassium  acidified  with  dilute  hydrochloric 
acid.  The  ensuing  clear,  deep  brown  coloured  solution  is  treated  with  hypo- 
sulphite of  soda  solution  until  quite  colourless.  The  hyposulphite  of  soda  solution 
is  composed  of  24'8  grms.  of  that  salt  to  i  litre  of  water ;  i  c.c.  of  this  solution  neu- 
tralises 0*0127  grms.  of  iodine  and  0003 5 5  grms.  of  chlorine. 

ahioromatiiiwiDagnes.  The  Strength  of  bleaching-powdcr  is  indicated  in  England, 
Russia,  America,  and  Germany  by  degrees  corresponding  to  the  percentage  of  active 
chlorine ;  but  in  France  the  degrees  denote  the  number  of  litres  of  chlorine  gas  at  o" 
and  760  millimetre  Bar.,  which  i  kilo,  of  bleaching-powder  can  evolve.  The 
following  table  compares  the  chlorometrical  degrees  of  France  and  EIngland : — 

French.  English. 

63  2002 

65  2065 

70  2224 

75  23-83 

80  2542 

85  2701 

90  2860 

100  31*80 

105  3336 

no  3495 

115  3654 

120  3813 

125  3972 

*i26  4004 

The  percentage  is  calculated  by  multiplying  the  French  degrees  by  the  coefficient 
0-318,  a  litre  of  chlorine  gas  =  355  criths,  weighing  3-18  grms. 


CHLORATE  OF  POTASSA.  223 

AikaUae  HypoohioritM.  A  solution  of  hypochlorite  of  potassa  is  known  in  commerce 
under  the  name  of  Eau  de  Javelle,  while  the  corresponding  soda  solution  is  known  as 
£au  de  Laharraque\  these  solutions  are  prepared  by  passing  chlorine  gas  into  a 
solution  of  either  caustic  (i),  or  carbonated  (2)  alkali: — 

(i).  2NaOH+Cla=NaOCl+NaCl+HaO: 

(2).  2NaaC03+Cla+HaO=NaOCl+NaCl+2NaHC03 ; 

or  by  exhausting  bleaching-powder  with  water,  and  precipitating  the  solution  with  sul- 
phate or  carbonate  of  soda  solution,  sulphate  or  carbonate  of  lime  being  thrown  down, 
while  the  hypochlorite  and  chloride  of  the  alkali  remain  in  solution. 

Hypochlorite  of  alamininm,  or  Wilson's  bleaching  liquor,  is  obtained  by  miring  chloride 
of  lune  solution  with  sulphate  of  alumina ;  its  action  is  by  evolving  oxygen,  leaving 
chloride  of  aluminium  in  solution.  Hypochlorite  of  magnesia  (Bamsay's  or  Gronville's 
bleaching  liquor)  is  obtained  by  adding  sulphate  of  magnesia  to  a  solution  of  bleaching- 
powder  ;  the  result  is  the  formation  of  a  very  energetic  bleaching  compound,  which,  espe- 
eially  for  the  purpose  of  bleaching  finely  woven  fabrics,  as  muslins,  <&c.,  is  preferable  to 
chloride  of  lime  on  account  of  the  absence  of  caustic  lime.  Yarrentrapp's  bleaching  salt, 
or  hypochlorite  of  zinc,  is  another  energetic  bleaching  compoxmd  obtained  by  treating  a 
solution  of  chloride  of  lime  with  sulphate  of  zinc,  the  result  being  the  precipitation 
of  sulphate  of  lime,  while  hypochlorite  of  zinc  remains  in  solution ;  chloride  of  zinc  may 
be  employed,  but,  of  course,  the  solution  then  retains  chloride  of  calcium.  Hypochlorite 
of  baryta  is  sometimes  used,  hypochlorous  acid  being  obtained  by  the  addition  of 
very  dilute  sulphuric  add. 

cbknataof  potawa.  TMs  Salt  (EGIO3)  cousists  in  100  parts  of  38'5  of  potassa  and 
6i'5  of  chloric  acid ;  its  crystals  are  rhombic  and  tabular  in  form.  It  formerly  was 
prepared  by  passing  chlorine  gas  into  a  concentrated  solution  of  carbonate  of 
potassa,  the  result  being  the  formation  of  chlorate  of  potassa  and  chloride  of 
potassium.  As  the  chlorate  is  the  least  soluble  it  crystallises  first,  while  by  evapo- 
ration the  mother-liquor  yields  chloride  of  potassium.  The  chlorate  is  then  washed 
with  cold  water,  and  purified  by  re-crystallisation.  100  kilos,  of  carbonate  of 
potassa  yield  in  this  manner  9  to  10  kilos,  of  the  chlorate.  At  the  present  day, 
however,  chlorate  of  potassa  is  prepared  by  a  method,  the  suggestion  of  the  late 
Dr.  Graham^  Chlorine  is  caused  to  act  at  a  high  temperature  upon  mKWx  of  lime,  with 
the  result  of  the  formation  of  chlorate  of  lime  and  chloride  of  calcium,  the  chlorate 
of  lime  being  afterwards  decomposed  by  chloride  of  potassium.  The  method  by 
which  chlorate  of  potassa  is  prepared  on  the  large  scale  according  to  this  plan  is  the 
following : — i  mol.  of  chloride  of  potassium  and  6  mols.  of  hydrate  of  lime,  having 
been  mixed  with  water,  are  submitted  to  the  action  of  chlorine  gas ;  the  solution  yields 
on  evaporation  crystallised  chlorate  of  potassa,  while  chloride  of  calcium  remains. 

This  operation  is  carried  on  by  the  aid  of  the  apparatus  illustrated  in  Fig.  109.  b  b  are 
earthenware  jars,  placed  in  a  chloride  of  calcium  bath,  and  filled  with  a  mixture  for 
evolving  chlorine  gas.  This  gas  is  conveyed  through  the  leaden  tube,  f  f,  to  the  vessel,  c, 
wMch  is  placed  in  cold  water  for  the  purpose  of  condensing  any  aqueous  vapours.  From 
0  the  gas  passes  through  the  leaden  tube  g  into  the  absorption  vessel,  ▲,  in  which  the 
iniztaie  of  lime  and  water  has  been  placed,  e  is  an  iron  stirrer  covered  with  lead ;  ^,  a 
portion  of  the  tube  for  carrying  off  the  non-absorbed  chlorine ;  d,  a  tube  closed  with 
a  plug  during  the  operation,  and  intended  for  tapping  off  the  contents  of  the  vesseL  The 
nulk  of  lime  is  poured  into  the  vessel  at  50**  to  60^  C,  while  sometimes  steam  is  injected 
for  the  purpose  of  keeping  up  the  temperature,  which  rises  as  soon  as  the  reaction  00m- 
niences  nearly  to  the  boiling-point.  A  smiUl  quantity  of  hypochlorite  of  lime  is  always 
formed.  As  soon  as  no  more  chlorine  is  absorbed  the  fluid  is  tapped  off  into  a  lead-lined 
tank,  and  after  the  suspended  matter  has  been  deposited,  is  syphoned  over  into  a  leaden 
^sporatin^  pan  and  concentrated  to  35°  to  30"*  B.,  any  hypocUorite  of  lime  being  thus 
<K>nverted  mto  chlorate.  To  the  evaporated  and  concentrated  solution  there  is  added 
a  hot  solution  of  chloride  of  potassium,  after  wluch  the  evaporation  is  continued  to  crys- 
taUisation.    According  to  theory,  2\  parts  of  Ume  require  i  part  of  chloride  of  potassium ; 


CHEMICAL  TBCHNOLOar. 


hj  first  preparing  chlorate  of  lime,  and  boiling  a  Bolatiou  of  this  eblorate,  adding  lo  tfa« 
concentrated  fluid  chlorate  of  potasaiom  to  obtain  chlorate  of  potaaaa.  Chlorite  of 
potaosa  is  not  altered  by  eiposore  to  air,  ia  soluble  in  iG  parts  of  water  at  IS'S",  in  B  ptrti 
of  water  at  35°,  and  in  1-6  parts  of  water  at  100°.  On  being  heated  to  fosion,  this  ult 
yields  oxygen ;  it  incantioiiHl;  rabbed  in  a  ■aortar  with  combuetible  sabstimces,  u 
solphnt  or  phoepboms,  vioIeDt  eiploEiona  will  euene.    i  kilo,  of  the  chlorate  yields,  wlwa 

Flo.  log. 


heated  with  either  o  5  kilo  of  manganese  or  i  kilo  of  onde  of  iron  or  better  still,  with 
k  small  qnantity  of  oiide  of  aopper  (see '  Chemical  News  vol  iiir  p  85)  3giigniii.' 
373-5  litres  of  oxygen  Chlorate  of  potasw  is  ohieflj  employed  10  pyrotechny  for  the  pre- 
puation  of  white  powder  aa  an  mgredient  in  the  explosive  mixture  for  the  eartridgs 
of  needle-guns,  as  an  oxidising  agent  in  cahco-printing,  and  in  the  preparation  of  Huhos 
black.  Perehlorate  of  potassa  fECliO^)  is  now  more  frequently  nsed  in  pyroteehnj. 
being  less  dangerous  to  manipnlate,  and  owing  to  the  targe  qoaotity  of  oxygni,  emitting 
more  intense  light. 

AlKALIUETRY. 

AUoJiBatiT.  The  poUah  met  with  in  commerce,  no  matter  from  what  ■om'cs  it 
is  obtained,  Is  always  a  mixture  of  carbonate  of  potassa  with  other  salts  of  potaffl* 
and  soda ;  and  again  the  carbonate  of  soda  of  commerce  is  a  mixtnre  of  the  or- 
bonatA  with  other  eoda  salts,  chiefly  enlphate  and  chloride.  The  value  of  ather  of 
the  salts  of  conree  depends  chiefly  apon  the  quantity  of  pure  carbonate  present  is  1 
given  sample.  The  quantitative  determination  may  be  effected  by  either  of  two  rapid, 
yet  sufficiently  accnrate,  methods : — 

a.  The  estimation  of  the  qnantitr  of  acid  required  to  nentralise  the  alkiliiw 

carbonate ; 

b.  The  determination  of  the  qnantit;  of  caibonic  add  evolved  by  the  additioD  of 

a  strong  acid. 
It  ia  clear  that  these  methods  can  be  applied  only  when  i 
alkaline  carbonate  is  present. 

ToiuiHUiaiiinhMi.       This  method,  invented  by  Descroizilles  and  ii 
Lnssac,  is  based  npon  the  measurement  of  the  quantity  of  sulphui' 


mproved  by  0*y- 
c  acid  required  U 


ALKALIMETRY.  225 

expel  the  carbonic  acid  from  a  certain  quantity  of  carbonate  of  potassa,this  measnre- 
xnent  giving  the  quantity  of  pure  salt.  The  best  sulphuric  acid  is  prepared  by 
mxxng  100  grms.  of  pure  sulphuric  acid,  sp.  gr.  =  i'842,  with  1000  grms.  =  1000  c.o. 
^  I  litre  of  distilled  water;  or,  instead  of  weighing  the  acid,  54268  c.c.  maybe 
mixed  with  a  litre  of  water.  50  c.c.  of  this  normal  acid  solution  suffice  for  converting 
4807  grms.  of  potassa into  sulphate  of  potassa.  The  burette  of  50  c.c.  capacity  and 
graduated  to  half  a  c.c,  is  filled  with  test-acid ;  next  4807  grms.  of  potassa  are 
weighed  out  and  dissolved  in  boiling  water.  Some  litmus  tincture  is  now  added 
and  the  test-acid  poured  from  the  burette  into  the  potash  solution  until  the  colour  is 
a  wiue-red.  Supposing  60  demi-c.c.  to  have  been  used  in  saturating  the  potash,  and 
deducting  i  c.c.  for  possible  excess,  the  sample  contains  potash  of  59  i''.  The 
quantity  of  potassa  per  cent  is  calculated  by  multiplying  the  quantity  found  by  1*47. 
Potash  of  50°  contaioB  50  X  147  =  75 '5  per  cent  carbonate  of  potassa. 
Mdu'iUMhod.      Mohr  substitutes  for  the  sulphuric  acid  crystallised  oxalic  acid — 

(CaHa04,2HaO=l26;  ^  mol.  =  63)! 
because: — i.  It  is  as  strong  as,  and  similar  to,  sulphuric  acid  in  its  action  upon 
litmus;  2.  Being  neither  deliquesCsi|^t  nor  efflorescent,  it  can  be  readily  weighed  off 
in  a  dry  state  with  accuracy;  3.  Its' aqueous  solution  is  not  liable  to  become  mouldy 
by  keeping,  as  are  the  solutions  of  citric  and  tartaric  acids ;  4.  It  is  not  volatile 
when  in  hot  water.  To  prepare  the  normal  acid  liquor,  63  grms.  of  oxalic  acid  are 
dissolved  in  a  litre  of  water ;  on  the  other  hand,  there  is  prepared  a  corresponding 
Bolution  of  caustic  potassa  so  titrated  that,  on  being  mixed  with  an  equal  bulk  of  the 
add  solution,  the  last  drop  of  the  alkaline  solution  restores  the  blue  colour  of  the 
previously  reddened  litmus,  provided  the  liquor  does  not  contain  carbonic  acid  in 
solution.  For  alkalimetric  purposes  6*911  grms.  of  potash  or  532  grms.  of  soda  are 
weighed  out,  these  quantities  being  equal  to  ^a  molecule,  and  as  the  test-acid  contains 
in  xooo  C.C.  i  molecule  of  oxalic  acid,  icx)  c.c.  will  exactly  neutralise  the  quantity  of 
allcali.  Some  litmus  tincture  is  mixed  with  the  alkaline  solution,  to  which  the 
oxalic  acid  solution  is  added  in  a  slight  excess  (5  to  6  c.c),  the  solution  being 
boiled  to  expel  all  the  carbonic  acid.  There  is  now  added  by  means  of  a  pipette 
divided  into  tenths-cc,  just  sufficient  caustic  alkali  to  turn  the  litmus  blue ; 
the  number  of  c.c.  of  alkali  solution  employed  is  deducted  from  the  number  of  c.c.  of 
acid  solution  employed,  the  difference  giving  the  percentage  of  pure  carbonate  of 
potassa  contained  in  the  sample.  For  instance,  if  345  grms.  of  the  potash  =  ^^o  mole- 
cule, require  36  c.c.  of  the  acid  and  3  c.c  of  the  alkaline  liquor,  there  will  be  33  c.c. 
test-add  =  66  per  cent  carbonate  of  potassa,  as,  instead  of  «V  mol.,  ^a  mol.  having 
been  employed,  the  number  of  c.c  of  test- acid  must  be  doubled. 

These  instances  of  alkalimetric  processes  will  suffice  for  the  purposes  of  elucidation ; 
but  the  reader  will  find  fuller  explanations  in  works  on  volumetric  analysis.  However,  it 
18  still  to  be  observed  that  as  potash  is  a  very  hygroscopic  substance,  it  is  necessary  to 
estimate  the  water  it  contains,  or  at  least  to  dry  the  sample.  As  6*29  grms.  of  commercial 
potash  and  4*84  grms.  of  soda  contain  when  pure  exactly  2  grms.  of  carbonic  acid,  every 
2  oentigrms.  loss  equals  z  per  cent  of  carbonate.  Supposing  the  loss  of  weight  to  amount 
to  164 centigrms.  the  sample  will  contain  >}«  =  82  per  cent  of  carbonate  of  potassa  ;  for 
scientific  purposes  it  would  answer  to  say  that  such  a  sample  consists  in  100  parts  of : — 

Carbonate  of  potassa 82 

Foreign  salts      8 

Water 10 

100 


/ 


226  CHEMICAL  TECBNOLOOr. 

For  oommeroial  purposes,  however,  at  least  abroad,  the  value  {titre)  of  a  sample 
of  potash  expresses  the  percentage  of  anhydrous  salt ;  for  instance,  by  potash  at  -jVo 
is  meant  potash  containing  60  per  cent  of  real  carbonate  when  in  a  dry  state. 
But  if,  by  having  taken  up  moisture,  100  lbs.  have  increased  in  weight  to  105  or 
109  lbs.,  the  expression  -jV^  or  -1%%  is  equivalent  to  saying  that  the  amount  of  money  that 
would  buy  ^%  of  dry  material  will  also  buy  j%%  and  j\°^  of  the  moist  salt ;  the  purchaser, 
therefore,  does  not  pay  for  water,  and  all  that  he  has  to  do  is  to  ascertain  the  quantity  of 
water  present  in  the  sample.  In  France  the  quantity  of  soda  contained  in  a  sample  ii 
usually  expressed  in  degrees  indicating  the  percentage  of  carbonate  of  soda,  and  in 
England  the  percentage  of  caustic  soda ;  thus,  as  100  parts  of  carbonate  of  soda  oontaia 
58*6  of  soda  and  41*4  of  carbonic  acid,  it  follows  that 

80°  French  are  equal. to  46*9"  English. 
86'       „        „      „  50-5°  „ 

96*       »        M      M  52-8*  „ 

SSJiSfg' thifv^?      ^  ^^®  preceding  methods  of  testing  potash  no  notice  is  taken  of  the 
of  Pouah.  soda  contained  m  the  samples,  nor  is  the  quality  of  the  potassa  salts 

considered.  It  is  clear  that  these  determinations  require  a  full  analysie,  which,  by 
Gruneberg's  method,  is  executed  in  the  following  manner : — The  carbonate  of  potassa 
is  estimated  by  Gay-Lussac's  method,  the  chlorine  by  the  aid  of  nitrate  of  silver,  the 
sulphuric  acid  by  nitrate  of  lead,  and  the  quantity  of  any  free  caustic  potassa  is  deter- 
mined by  means  of  tartaric  acid.  All  the  chlorine  is  calculated  as  chloride  of  potasdom, 
all  the  sulphuric  acid  as  sulphate  of  potassa,  and  the  rest  of  the  potassa  as  carbonate; 
the  quantity  thus  found  is  deducted  from  that  found  alkalimetrically,  and  the  remainder 
is  calculated  to  be  carbonate  of  soda  in  the  proportion  of  69'!  to  53*0. 

fl 

Ammonia  and  Ammoniacal  Salts. 

Ammonia.  Ammonia  occurs  in  the  atmosphere.  Ammoniacal  salts  are  met  with  in 
a  few  minerals  and  in  volcanic  districts.  But  the  bulk  of  the  ammonia  and 
ammoniacal  salts  industrially  used,  is  obtained  from  tlie  dry  distillation  of  coals, 
hones,  and  animal  substances,  also  by  the  distillation  of  lant  (stale  urine),  by  the 
action  of  steam  on  some  cyanogen  compounds,  and  as  a  product  of  the  blast-fomaoe 
process. 

The  following  sources  of  ammonia  are  technically  available : — 

1.  Native  carbonate  of  ammonia, 

2.  Preparation  of  ammoniacal  salts  with  boracio  acid, 

3.  Volcanic  sal-ammoniac, 

4.  Ammonia  from  nitric  acid  in  the  purifying  of  caustic  soda, 

5.  „  „      deutoxide  of  nitrogen  and  nitrous  acid, 

6.  „  „     the  nitrogen  of  the  air, 
,7.          „          „     certain  cyanogen  compounds. 

8.  Coals  yield  ammonia : — 

a.  By  the  dry  distillation  for  the  purpose  of  gas  manuf^Mtuie, 

b.  By  the  coking  of  coals, 
€,  By  the  use  of  coals  as  fuel ; 

9.  Ammonia  from  lant, 

ID.        „  „    the  dry  distillation  of  bones, 

II.        „  „   beet-root  juice. 

Ammonia,  NH3,  consists  of  i  volume  of  nitrogen  and  3  volumes  of  hydrogen,  con- 
densing to  2  volumes  of  ammonia  gas,  a  colourless  gas  of  a  peculiar  and  well-known 
odour  and  sharp  biting  taste.  At  15°  water  absorbs  727,  and  at  0°  1050  times  its 
own  bulk  of  this  gas,  the  solution  being  known  as  liquid  ammonia,  or  spirit  of  sal- 
ammoniac,  the  sp.  gr.  of  which  is  0824  (=31*3  per  cent  NH3).  Usually,  however,  a 
weaker  and  more  stable  liquid  ammonia  is  prepared  for  pharmaoeutical  and  technical 
purposes,  having  a  sp.gr.  =  0960  (=  975  per  cent  NH3V  The  following  table 
shows  the  specific  gravity*  of  liquid  ammonia,  and  the  percentage  of  ammonia 
contained : — 


A.  Inorganic 
sources. 


p.  Organic 
sources. 


AMMOmA, 

Bp.gr. 

NH3  per  eent. 

Bp.gr, 

0-875 

3250 

0959 

o'8z4 

31-30 

o'96i 

o'qoo 

2600 

0963 

0905 

2539 

0965 

0925 

19-54 

0968 

0932 

ir52 

0970 

0*947 

1346 

0972 

0-951 

IZ'OO 

0-974 

0953 

11-50 

0976 

0955 

II'OO 

0-978 

0957 

10-50 

227 


KH5  per  cent. 
100 

95 
90 

8-5 
8-0 

7'5 
70 

6-5 
6-0 

55 


Ammoma  gas  is  very  solable  in  alcohol.  The  spirittu  ammoniaei  eawtiei  Dzondii  of 
the  Prussian  FharmaoopoBia  is  a  solution  of  ammonia  gas  in  alcohol  of  o'Sao  sp.  gr. ;  the 
ammoniaoal  solution  containing  10  per  cent  of  real  NH3,  and  having  a  sp.  gr.  of  0*808  to 
0'8io.  The  liquor  ammonii  vinosus  is  a  mixture  of  i  part  of  liquid  ammonia  (at  10  per 
eent  NH3)  and  2  parts  of  strong  alcohol.  Liquid  ammonia  is  industrially  employed  for 
the  extraction  of  the  lichen  (orchil)  pigments,  in  the  preparation  of  carmine,  the  manu- 
facture of  snuff,  the  purifying  of  coal-gas,  for  the  removal  of  carbonic  acid  and  sulphuretted 
hydrogen,  for  the  saponification  of  fats,  the  preparation  of  ferrocyanide  of  potassium 
according  to  Oelis's  plan  with  the  aid  of  sulphide  of  carbon,  for  the  extraction  of  chloride 
of  silver  from  its  ores,  as  antichlor  in  bleach-works,  and  in  the  manufacture  of  pigments 
and  dyes.  As  regards  the  use  of  liquid  ammonia  for  the  extraction  of  copper  from 
pjritioal  ores,  Barruel  stated  (1852)  that  the  copper  might  be  dissolved  by  simply  impreg- 
nating  finely  pulverised  ore  with  liquid  ammonia,  and  forcing  air  through  the  mixture, 
the  metal  being  obtained  as  black  oxide  of  copper  after  the  ammonia  is  distilled  off. 
This  process,  however,  has  not  been  found  to  answer  on  the  large  scale.  The  researches 
of  von  Hauer,  Schonbein,  Tuttle,  and  others,  have  proved  that  the  oxidation  of  the 
ammonia  is  simultaneous  with  the  oxidation  of  the  copper,  and  that  the  nitrous  acid  thus 
formed  is  the  active  agent.  Moreover,  the  experiments  of  Liebig  and  Way  have  proved 
that  even  if  the  operation  were  carried  on  in  air-tight  vessels,  the  ammonia  could  not  be 
entirely  recovered,  owing  to  the  fact  that  the  ores  absorb  ammonia,  and  render  it 
insoluble,  thereby  preventing  its  action  on  the  copper.  But  if  the  copper  ore  be 
tolerably  pure  malachite  or  lazulite,  only  containing  Hme  or  carbonate  of  that  base,  liquid 
ammonia  may  be  successfully  employed.  Liquid  ammonia  is  used  in  Garry's  ice-making 
machine.  The  rationale  of  this  machine  is  that  ammoniacal  gas  being  expelled  by  heat 
from  its  aqueous  solution,  is  again  condensed  and  liquefied  by  pressure  and  cooling ;  the 
retort  in  which  the  ammoma  is  heated  being  next  cooled  by  water,  a  vacuum  is  created, 
and  as  a  consequence  the  ammonia  contained  in  the  condenser  volatilised,  returned  to  the 
retort,  and  again  taken  up  by  the  water  present.  On  again  resuming  the  gaseous  state, 
the  ammonia  absorbs  a  great  amount  of  heat,  causing  a  diminution  in  temperature 
sufficient  to  freeze  water.  Carry's  ice-machine  yields  10  kilos,  of  ice  for  every  kilo,  of  coal 
consumed  as  fuel.  Although  Foumier  has  suggested  that  ammoniacal  gas  might  be 
usefully  employed  in  testing  the  joints  of  gas-fittings  in  houses,  this  is  more  readily 
effected  by  the  use  of  a  hand  air-pump.  The  application  of  ammonia  as  a  source  of 
motive  power  has  been  tried,  but  it  is  not  at  present  likely  that  it  will  supersede  steam. 

PJniMttM^oMjqnid  gy  decomposing  with  canstic  lime  either  chloride  of  ammonimn 
or  sulphate  of  ammonia,  ammoniacal  gas  is  set  free,  and  can  be  absorbed  by  water, 
carej>eing  taken  that  the  lime  is  in  excess.  When  carbonate  of  ammonia  is  prepared 
on  the  large  scale  by  sublimation  of  a  mixture  of  chalk  and  sal-ammoniac,  a 
large  quantity  of  ammoniacal  gas,  14  parts  for  each  100  parts  of  carbonate  of 
ammonia,  is  obtained  and  may  be  utilised.  Wagner  has  been  the  first  to  observe 
that  the  technical  preparation  of  liquid  ammonia  might  be  combined  with  the 
preparation  of  baryta-white  by  precipitating  a  solution  of  sulphate  of  ammonia 
^th  caustic  baryta  water ;  the  clear  supernatant  liquor  will  be  a  solution  of  caustic 
ammonia. 


Q2 


CHEMICAL  TECHNOLOOY. 


red -lead. 


the  large  eaale  ie  effected  bj  mesni  ef  the 
-iron  distilling  veseel  placed  in  a  biickvoik 
ed  a  lid  secured  to  the  flange  bj  meana  of 
The  lid  carriee  an  iron  tnbe,  m,  leading  to  th« 


328 

The  preparation  ot  Uqnid  a 
SppaiatQB  shown  in  Fig.  i^o. 
furnace.    To  the  neck  of  the  vi 

bolts  and  nuts,  an  ,     , 

irasfa  Teasel,  n,  of  wrought-iron.  This  vessel  is  aurrounded  b;  cold  water  contained  in  a 
iTOodon  tank,  and  is  provided  with  a  wide  tube,  o.  tbrongh  trhieh  nt  pasMB.  The  iFash 
vessel  ia  filled  with  only  so  ntuoh  water  as  will  close  the  tubes  n  and  a  h;draulieallj. 
as  daring  the  operation  a  large  quantit;  of  water  is  distilled  over  from  k.  loo  paits  of 
Blaked  lime  are  mixed  witb  a  sufficient  qnaotitj  of  water  to  form  a  thin  milk  ol  lime, 
which  is  poured  into  i ;  the  lime  solution  having  become  quite  cold,  there  ia  added  loo 
ports  of  pulverised  sal-ammoniac  or  snlphale  of  ammonia,  being  tJioronghlv  miied  bj 
stirring  with  an  iron  rod.     The  lid  being  screwed  on  a,  the  fire  ig  lighted  in  c ;  tlia 


mercurial  gauge,  b,  shows  the  course  of  the  operation.  The  ammouiacal  gas  prooeeda 
from  the  woah  veatiel,  b,  through  the  tnbe  t  into  the  condensing  apparatus,  a.  invented 
by  Bruunqnell,  and  highly  useful  for  this  and  for  similar  purposes  where  it  ia  desired  to 
work  nnder  a  low  pressure.  This  apjiaratua  consists  of  a  large  tank  or  box  in  which 
four  shallow  boxes,  a',  a",  a'",  a"",  are  placed  bottom  upwards,  the  aides  ot  the  bo»(» 
being  perforated  with  small  slits.  The  oatet  tank  is  filled  with  water.  When  am- 
moniacal  gaa  eutera  through  t  into  a"",  it  forms  a  large  babble,  similar  to  an  air  babbi* 
nnder  ice,  and  reaching  one  of  the  small  slits  rises  into  a'",  and  ho  on,  the  bubbl* 
becoming  smaller  and  smaller  aa  the  water  gradually  absorbs  the  gas.  The  box  or  tank. 
D,  ia  placed  in  a  large  tank,  not  represented  in  the  cut.  filled  with  cold  water  constantl; 
renewed.  The  stiB,  A,  is  of  sufficient  capacity  to  contain  20  kiloa.  of  Bolphala  ot 
ammonia,  and  80  litres  of  water.  The  operation  is  continued  until  the  bottom  o(  the 
Btill  becomes  red-hot.  The  water  contained  in  a  is  used  at  a  subBeqnent  operation  for 
tailing  with  the  lime.  The  preparation  of  liquid  ammonia  directly  from  gas  liquor,  tbe 
ammoniacal  water  of  gas  works,  will  be  mentioned  presently.  The  application  of  the 
property  of  chloride  of  calcium  to  abaorb  ammonia  and  deliver  it  up  on  the  application 
of  heat  has  been  atti-'nipted  indastriaUy  by  Knab  for  the  storing-np  of  ammonia.  Btrcog 
liquid  ammonia  only  contains  15  per  cent  NHj,  and  Knab's  preparation  50  per  cent;  » 
regards  transport  this  may  not  be  an  uninteresting  fact,  but  chloride  of  calcimn  i>  a 
very  deUqnescent  salt. 

iBom^csoiiroi.oi  Before  proceeding  to  describe  the  preparation  of  ammoniacal 
salts  &oni  bones,  coals,  lant.  I.e..  we  must  first  enimierat«  the  inorganic  sources  of 
ammonia  of  industrial  uuportiinoe. 

I.  Native  carbonate  of  ammonia,  met  with  in  brgc  quantities  in  the  goano  depodti  c' 
South  America,  was  imported  into  Germany  aa  a  commercial  article  in  1848.  On  being 
AoalyLicd  thiij  substauco  waa  fonud  to  consiBt  of— Ammonia,  zo'44 ;  carbonic  acid,  54'jJ  • 


AMMONIA.  229 

▼ater,  21*54 ;  and  insoluble  matter,  21*54  parts.  It  is,  therefore,  a  bicarbonate  of  ammonia 
(NH4)HC03. 

2.  The  preparation  in  Tnscanj  of  native  sulphate  of  ammonia  as  a  by-produot  of  the 
preparation  of  boracio  acid  has  reoently  become  important.  The  suffioni  contain,  in 
addition  to  boracic  acid,  sulphates  of  potassa,  soda,  ammonia,  rubidium,  &0, ;  and  that 
the  quantity  of  these  substances  is  by  no  means  small  may  be  inferred  from  Travale's 
researches,  from  which  it  appears  that  four  suffioni  yielded  within  twenty-four  hours 
5000  kilos,  of  saline  matter,  consisting  of  150  kilos,  of  boracic  acid,  1500  kilos,  of  sulphate 
of  ammonia,  1750  kilos,  of  sulphate  of  magnesia,  750  kilos,  of  the  protosulphates  of 
iron  and  manganese,  &o.  The  ammonia  is  probably  due  to  the  decomposition  of  nitrogenous 
organic  matter,  occurring  largely  in  the  Tuscan  mountains,  the  soil  near  the  lagoons  being 
impregnated  with  sulphate  of  ammonia.  In  combination  with  the  sulphates  of  soda, 
magnesia,  and  iron,  sulphate  of  ammonia  forms  the  mineral  Boussingaultite,  discovered 
byBechi 

3.  The  ammoniacal  salts  due  to  volcanic  action  are  of  no  or  of  little  value  to  industry. 
Maicagnin,  sulphate  of  ammonia,  is  met  with  on  Vesuvius  and  Etna ;  sal-ammoniac  is 
sometimes  also  found  on  Etna,  as  in  the  years  1635  and  1669,  in  such  large  quantities 
as  to  become  temporarily  an  article  of  commerce  at  Catania  and  Messina. 

4.  Ammonia  is  formed  during  many  inorganic  chemical  operations,  but  rarely  in 
quuitities  rendering  its  preparation  or  recovery  commercially  available.  Ammonia  is, 
for  instance,  set  free  in  the  preparation  of  caustic  soda  (see  page  189),  and  the  purifi- 
cation of  caustic  soda  by  means  of  nitrate  of  soda ;  the  quantity  of  ammonia  set  free  in 
this  case  is  so  large  that  it  would  be  commercially  worth  trying  to  condense  the  gas  in  a 
eoke  scrubber  or  condenser.  When  arseniate  of  soda  is  prepared  by  dissolving  arsenious 
acid  in  a  caustic  soda  solution,  evaporating  this  liquid  to  dryness,  and  igniting  the  residue 
^th  nitrate  of  soda,  ammonia  is  disengaged  in  large  quantity. 

5.  Under  the  heading  '*  Ammonia  as  a  by-product  of  the  manufacture  of  sulphuric 
acid,'*  there  is  in  the  original  German  text  a  description  of  a  mere  suggestion,  embodied  in 
a  provisional  specification  of  an  English  patent,  for  the  utilisation  of  the  waste  nitrous 
vapours  of  sulphuric  acid  manufacture  in  the  preparation  of  ammonia,  by  passing  these 
Tapours,  with  steam,  through  red-hot  tubes  or  retorts  filled  with  charcoal,  the  ammonia 
thus  formed  being  absorbed  by  sulphuric  acid.  This  process  could  never  be  available  but 
in  badly  arranged  sulphuric  acid  works,  because  in  well  managed  works  the  escape  of 
nitrous  fumes  is  so  very  small  that  it  certainly  would  not  pay  to  convert  them  into 
Ammonia. 

6.  Of  the  many  unsuccessful  attempts  made  to  directly  convert  the  nitrogen  of  the 
atmosphere  into  ammonia,  it  will  only  be  necessary  to  mention  Fleck's  suggestion,  to 
pass  a  mixture  of  nitrogen,  oxide  of  carbon,  and  steam  over  red-hot  hydrate  of  lime, 
whereby  ammonia  and  carbonic  acid  are  formed : — 

7.  Perhaps  the  indirect  application  of  atmospheric  nitrogen  for  the  preparation  of 
ammonia  is  of  more  importance.  Margueritte  suggests  that  cyanide  of  barium  should  be 
prepared,  and  its  nitrogen  converted  into  ammonia  by  the  aid  of  a  current  of  superheated 
steam  at  300**.  According  to  the  description  of  this  process  in  an  English  patent,  not 
however  in  practice,  native  carbonate  of  baryta  is  calcined  with  some  30  per  cent  of  coal- 
tar,  for  the  purpose  of  rendering  the  mass  porous  as  well  as  more  readily  converted  into 
caoetic  baryta  at  a  lower  temperature.  The  carbonaceous  mass  is,  after  cooling, 
placed  in  a  retort,  and  kept  at  a  temperature  of  300°,  while  air  and  aqueous  vapour 
ftre  forced  in,  the  result  being  the  formation  of  ammonia  in  considerable  quantity,  and 
carbonate  of  baryta,  which  is  again  used.  Ammonia  is  evolved  from  ball  soda  while 
cooling,  during  the  formation  of  cyanogen  and  cyanide  of  potassium  in  blast  furnaces, 
ud  thg  formation  of  sal-anmioniao  in  the  process  of  iron  smelting. 

^^toilSSi?' **'  Industrially  speaking,  the  organic  sources  of  ammonia  are  far 
more  important  than  the  inorganic.  Among  the  ammonia-yielding  organic  sub- 
stances coal  (8)  takes  the  first  place ;  the  average  quantity  of  nitrogen — 075  per 
centr-contained  in  coal  is  converted  into  ammonia  during  three  different  processes 
employing  this  valuable  mineral,  viz. : — 

«•  By  the  dry  distillation  of  coals  for  the  manufacture  of  illuminating  gas,  ammonia  is 
obtained  in  the  so-called  gas-,  or  anmioniacal  gas-water,  the  liquid  mainly  consisting  of 
an  aqueous  solution  of  sesquicarbonate  of  ammonia.    The  importance  of  this  source 


230  CHEMICAL  TECHNOLOGY. 

of  ammonia  production  may  be  inferred  from  the  fact  that  the  one  million  tons  of  Mk 
yearly  carbonised  by  the  London  gas-works  will  vieldi  supposing  all  the  nitrogen  to  be 
conTerted  into  sal-ammoniao,  9723  tons  of  that  salt. 

/3.  Ammonia  is  also  formed  when  coal  is  converted  into  ooke  in  coke  ovaiB«  Yery 
recently  the  utilisation  of  this  source  of  ammonia  has  been  suocessfnly  carried  on  st  the 
large  coking  establishment  at  Alais,  B^partement  du  Gard,  France,  and  also  at  the  ooke 
oyens  belonging  to  the  Soeieti  de  CarbonUatUm  de  la  Loire ^  near  St.  Etienne,  whezB,  ia 
oyens  constructed  according  to  Knab's  method,  large  quantities  of  ammoniacal  salts  are 
produced. 

y.  Ammonia  is  produced  during  the  combustion  of  coal  as  fuel,  a  portion  of  the  nitrogen 
contained  in  the  coals  being  eliminated  as  anunonia ;  but  this,  it  should  be  borne  in  mind, 
is  a  consequence  of  imperfect  combustion,  and  consequently  of  loss  of  fuel ;  and  althougit 
a  series  of  experiments  have  been  made,  and  iqpparatus  devised  for  .collecting  and  con- 
densing the  ammonia  evolved  with  the  smoke,  tibe  industrial  production  from  this  aoutee 
has  hiUierto  been  very  limited. 

^"SSSSti?*  'T^  is  the  most  important  source  of  ammonia  production.  By 
the  dry  distillation  of  coals  for  the  purpose  of  gas  manufacture  there  are  formed,  in 
addition  to  permanent  gases,  various  vapours,  some  of  which  on  cooling  yield  tar 
and  ammoniacal  liquor,  consisting  chiefly,  as  before  stated,  of  a  solution  of  aesqui' 
carbonate  of  ammonia,  but  containing  sulphuret  and  cyanide  of  ammonium,  sulpho' 
cyanide  of  ammonium,  and  sal-ammoniac,  and  being  coloured  by  tony  natter. 

It  is  obvious  that  the  quantity  of  ammonia  contained  in  this  liquor  is  not  always 
constant,  but  depends  upon  several  conditions ;  for  instance,  the  quantity  of  nitrogen 
contained  m  the  gas  coals,  the  hygroscopic  moisture  of  the  coals,  and  the  degree  of 
heat  applied  to  the  retorts.  The  nearer  the  retorts  are  kept  to  a  bright  orange-red 
heat,  and  the  longer  the  distillation  is  continued,  the  larger  the  quantity  of  amjuonia 
formed ;  for  at  a  lower  temperature,  of  course  always  above  red  heat,  there  may  be 
formed  aniline,  chinoline,  lepidine,  and  cyanogen  compounds.  Taking  the  average 
quantity  of  the  hygroscopic  moisture  of  coals  at  5  per  cent,  and  the  nitrogen  al  an 
average  of  075  per  cent,  100  kilos,  of  coal  would  yield,  under  the  most  fiftvourttUe 
conditions,  ogi  kilo,  of  ammonia.  According  to  Dr.  A.  W.  Hofinann's  report  (1863), 
coal  yields,  when  distilled,  only  one-third  of  its  nitrogen,  two- thirds  being  retained  in 
the  coke ;  but  no  accurate  experiments  have  been  made  on  this  subject.  It  has  been 
practically  ascertained  on  the  large  scale,' that  z  cubic  inetre  (=220-096  gallons)  of 
gas-water  yields  at  least  50  kilos,  of  dry  sulphate  of  ammonia.  The  ammonia  of  the 
gas-water  may  be  utilised  in  various  ways.  Where  fuel  is  cheap,  and  crude  sulphate 
.  of  ammonia  or  crude  sal-ammoniac  marketable  article,  the  gas-water  may  be  at  once 
neutralised  by  an  acid,  and  the  liquid  thus  obtained  evaporated.  This  is  done  in  a 
sal-ammoniae  factoiy  at  Liverpool,  where,  during  the  colder  season  of  the  year, 
300  cwts.  weekly  of  this  salt  are  prepared.  Generally,  however,  the  gas-water 
is  submitted  to  a  process  of  distillation,  and  the  ammonia  evolved  converted  into  sul- 
phate, as  in  Mallet's  apparatus,  or  into  sal-ammoniac,  as  in  Rose's  apparatos. 

xanrt'B  AppuRtai.  This  apparatus,  in  use  in  many  of  the  large  gas-works,  is  shown  in 
vertical  section  in  Fig.  iii.  The  plan  of  action  is  to  force  steam  into  large  vessels 
filled  with  gas-water,  the  effect  being  the  volatilisation  of  the  carlxMiate  of  ammonis* 
Sometimes  lime  is  added.  The  volatilised  ammonia — of  course  if  lime  is  added 
caustic  anunonia  is  evolved — is  next  convey.ed  into  an  acid  liquor,  and  thus 
converted  into  sulphate  of  ammonia.  The  apparatus  consists  of  two  cylindrical 
boiler-plate  vessels,  a  and  b.  a  is  heated  directiy  by  the  fire,  and  is  provided  with  a 
leaden  tube,  e,  dipping  into  the  liquid  contained  in  b,  this  vessel  being  placed 
to  catch  the  waste  heat  from  the  fire,  b  and  e  are  man-holes ;  a  and  a  stirrers.  By 
means  of  the  tube  d  the  fluid  from  b  can  be  run  off  into  ▲.    Oas- water  is  poured 


AMMONIA. 


»3t 


into  both  Teasels  and  lime  added ;  uumouia  is  set  free,  while  carbonate  of  lime  and 
lalphnret  of  calcium  are  formed,  and  of  course  remain  in  the  vessels  after  the  vola- 
tilisation of  the  ammonia.  The  vessel  n  ia  alao  filled  with  ammoniacal  water,  and 
when  the  operation  ia  in  progress  thia  water,  already  warmed,  ie  riio  h;  the  aid  of 
the  tube  A  from  D  into  B.  K  is  a  gas-water  tank,  from  which  n  is  filled  hy  means  of  jr. 
The  ammonia  eet  free  in  i.  ia,  with  the  steam,  coureyed  by  the  pipe  e  into  b. 


thence  through  e'.  into  the  wash-veaael,  c,  and  thence  again  throng  c",  into  the  first 
condenser,  n.  Tlie  partially  condensed  vapour  now  pasaea  into  the  condensing 
vessel.  K,  the  worm  of  which  is  anrroimded  by  cold  water.  The  dilute  ammonia  is 
collected  in  o,  and  forced  hj  means  of  the  pump  r  into  c,  whence  it  is  occasionally 
syphoned  into  either  a  or  B.  The  non-condensed  unmoniacal  gas  is  carried  from  o. 
through  a  series  of  WonUe'e  bottles,  tho  first  bottle,  h,  containing  olire  oil  for  the 


J32 


CHEMICAL  TBCBNOLOar. 


purpose  of  absorbing  an;  hydrocarbons  mixed  with  the  goa ;  the  bottle  I  oantains 
csustic  Boda  ley,  in  order  to  purify  the  ammonia  and  retain  impurities ;  the  bottle  k 
is  half-filled  with  distilled  water.  The  ammoniacal  gas  having  passed  through  s, 
is  conveyed  to  tlie  large  lead-lined  wooden  tank,  l,  filled  with  dilute  solpburio  acid  if 
it  Is  intended  to  prepare  sulphate  of  ammonia,  or  with  water  for  maV'T'g  liquid 
ammonia.  The  vessel  l  is  placed  in  a  tank  of  water ;  t  is  a  amaU  pipe  for  introdn- 
cing  acid ;  while  the  tube  leading  to  u  aerres  to  carry  off  any  unalsorbed  wmucmia, 
u  being  also  filled  with  acid. 

BsH'i  ippuitu.  In  the  monnfaotars  of  liquid  aramonia  the  apparatus  devised  by  Hr. 
Rose,  and  shown  in  Fig.  :ii,  may  be  adyaBtageoos^  employed.  It  oonaiBta  of: — i,  a 
boiler ;  B  and  c,  tvo  veBsels  in  which  the  gas-water  is  warmed  by  the  aid  of  the  tubes, 
«  and  /,  through  wbiob  and  g  the  steam  and  ammonia  gas  evolved  io  a.  pass  to  the 
absorption  vessels,  d,  b,  and  r,  tbe  connection  between  b  and  i  being  foimed  by  the  gas- 
filters,  a  and  h.   The  ammoniaoal  water  can  be  run  into  &  by  means  of  the  tubes,  I  and  », 


each  of  which  is  fitted  with  a  tap  or  stopcook  \  ih  filled  two  thuds  with  gas-water  and 
one  third  with  elaked  hme  The  oylmdncal  sheet  iron  gsa  filters  o  and  h  are  filled  with 
freshly  burnt  charcoal  to  retain  any  empyrenmatical  mattei  which  might  be  carried  over 
by  the  gas  The  absorption  vessel  d  is  filled  with  hydrochlonc  acid  while  pore  *>tm 
IS  ponred  mto  a  snd  r  When  a  is  filled  and  the  rest  of  the  apparatus  put  in  working 
order,  the  fire  is  kindled,  iiie  ammoniacal  gas  evolved  in  i  passes  with  the  steam  to  b  and 
c,  where  a  portion  of  the  steam  is  condensed  and  retained  as  water  in  e  and  /.  Into  tbe 
boiler,  k,  is  fitted  a  tube,  b,  containing  a  thermometer,  Bnrronnded  by  brass  fittings  lor  tbe 
better  conduction  of  the  heat;  when  this  thermometer  indicates  gi"  to  94°,  the  tap  A  is 
opened,  and  the  tap,  t,  open  np  to  this  time,  shut  in  order  to  cause  tbe  gas  to  pass  into  the 
hydrochloric  acid  contuned  in  d,  imtil  the  vessels  0  and  a  have  been  filled  with  fresh 
charcoal,  an  operation  which  is  reqnired  at  the  beginning  of  the  working  as  well  ai  when 
the  temperature  in  a  has  risen  to  g6°,  g8°,  and  100°.  This  having  been  done,  the  tap  A  i* 
again  opened.  When  the  temperature  has  reached  103°,  talnng  the  boiling-point  o( 
the  liquid  at  100°,  all  the  ammonia  is  eipelled,  and  the  liquid  is  then  run  ofT  by  opening 
tbe  stopcock,  a.  Fresh  lime  having  been  put  into  tbe  boUer,  the  operation  is  repealed. 
When  the  temperature  in  a  reaches  103',  the  hquid  in  b  becomes  heated  to  90°,  and  that 
in  c  to  from  35°  to  30°.  Tbe  vessel  i  contains  from  120  to  150  htres  of  water,  which  is  eon- 
verted  into  liquid  ammonia  of  a  sp.  gr.  =  D'gio  to  o'gzo.    c  and  n  are  gloss  safety  tnbce. 

l.niiB>'>  Appumtiu.  This  spparatns,  also  intended  for  the  utilisation  of  gas- water,  is  shown 
in  Fig.  113;  a  is  the  boiler ;  h  the  gas  tube  connected  with  the  worm,  f,  which  is  placed  iu 
a  tai^,  d,  fiUed  with  gas  liquor,  ran  into  a  by  means  of  the  tube  e.    The  tnbe  /  is  so  fitted 


Id  a  H  to  kdndt  of  diaohBrgiag  the  waste  liqnor  Tesdll;.  Ii  mpreBentB  a  Etirm  fitted  to 
the  boiler  bj  a  stuffing  box,  and  being  intended  to  rake  np  tbe  lime  and  prevent  it  getting 
caked  to  the  bottom  of  a  ;  hi,  a  tnbe  intonded  for  rmmiug  gBs-liqaor  into  d,  from  a  tank 
pUeed  at  t,  bigW  level ;   i,  a  tube  proTided  nith  a  tap  and  fitted  to  the  Dover  of  J, 


to  Bonve;  an;  gas  or  v^jours  from  d  into  the  vorm.  k  represents  a  iruh  veuel,  some- 
times  Sited  simply  irith  water,  at  others  with  milk  of  lime.  The  gas  and  vapoors  having 
pused  through  it,  are  conveyed  to  tbe  absorption  vessel,  I.  The  tube,  tn,  through  which 
tbe  gag  pwBee,  is  fonnel-ah^ed,  and  opposite  to  the  mouth  of  the  funnel,  at  tbe  bottom  of 
tbe  tank,  a  thick  dim  of  lead  ia  fiied,  beoause  at  this  spot  the  action  of  the  gas  would  sooa 
f*"  sway  the  leaden  lining  of  the  vessel,  o  is  a  smaller  wooden  tank,  also  lead-lined, 
uto  whidi  sulphuric  acid  is  ponred,  and  whesoe  it  runs  into  I  through  tbe  stoneware 
■Tpbou,  p.  Any  vaponrs  given  off  are  caught  by  the  bood,  r,  and  tbenee  conveyed  by  a 
tnbe  into  tbe  ohimney,  ^e  saline  rnatter  deposited  in  I  is  removed  by  a  leaden  pail,  a* 
*bown  In  the  cat ;  when  this  pail  is  filled  it  is  drawn  np  by  means  of  the  chain  uid 
Pii%  dded  by  the  ooonter  weight,  i.    Tbe  salt  (sulphate  ol  ammoaia]  is  pUoed  in  the 


234  CBEMICAL  TECSNOLOaV. 

boaket,  u,  (rom  vhiali  tlie  mother-liquor  adhering  to  the  salt  draiaa  again  into  the  tank,  L 
Evaporation  ia  tberefoie  oimeceBBary  with  this  apparatoa. 
uunoiiii  bimi  LuL  g.  Lant,  or  stale  urine,  is  a  veiy  important  eotizce  of  aMmonia- 
WheneTer  lutrc^enona  organic  bodies  are  decajisg,  ammonia  is  always  fonned; 
when  the  organic  substance  is  a  proteine  compound,  there  is  formed  carbonate  of 
ammonia  as  well  as  sulphnret  of  ammonium ;  but  when  the  organic  substance  con- 
taina  no  sulphur,  onl;  carbonate  of  ammonia  is  formed,  as  is  the  case  witb  the  nrea, 
CH^NiO,  contained  in  urine,  the  nrea  bj  taking  up  the  elements  of  the  water  being 
converted  into  carbonate  of  ammonia.  Lant  is  freqnentlj  employed  without  further 
preparation  for  various  purposes,  on  account  of  the  carbonate  of  amipn""  it 
contains,  as.  far  instance,  in  washing  wool  and  removing  the  fat  from  flannel 
and  other  woollen  fabrics. 

The  apparatoa  exhibited  in  Fig.  T14,  oontrired  bjFigaera,  and  until  lately  in  operation 
at  a  large  eatabliahment  for  the  ntiliaatioD  of  the  contents  of  tlie  latrines  and  oloaec  of 
Paris,  consists  of  a  ateam -boiler,  w.  the  steam  generated  in  which  is  conveyed  to  two  larga 
iron  cyiindeiB  filled  with  lant.  The  oacbonate  of  ammonia  eipelled  is,  inth  the  steam, 
condensed  in  a  leaden  worm ;  the  cooled  liquid  ia  conveyed  to  a  tank  filled  with  add,  and 


thns  converted  into  carbonate  of  ammonia.  The  arrangement  of  the  apparatos  ia  h 
follows:— The  wooden  veuet,  a,  eontsins  some  250  hectolitreB  of  lant,  and  is  Blled 
by  means  of  the  tube  h.  0  and  0'  are  two  cylindrical  aheet-iron  vessels  of  100  heotolitrss 
capacity ;  f  and  p*  are  similar  veaaels,  the  nee  of  which  will  be  presently  explained.  At 
the  commencement  of  the  operation  the  boiler,  w,  is  filled  with  aboat  130  bectoiitres  of 
exhausted  lant,  taken  from  the  veaaela  c  and  c'.  The  lant  in  a.  warm  in  conaequenoe  of 
having  served  for  cofidensation,  is  conveyed  W  0  by  a  tube,  and  thence  by  the  tube  h"  to 
<f,  cold  lant  being  poured  into  a..  Tbe  boiler,  w,  ia  fitted  with  three  tabes,  viz.,  T, 
the  steam  pipe,  m,  a  safety  tnbe,  brought  to  within  a  few  centinietres  from  the  bottom  of 
the  boiler,  and  carried  above  the  roof  of  the  shed,  and  n  a  smaller  safety  tube;  v  is  a  tabs 
fitted  with  a  stopcock.  The  steam  evolved  in  w  ia  carried  bv  t  into  c',  evolving  from  the 
liquid  therein  the  carbonate  of  ammonia  it  holdain  solution.  The  carbonate,  with  the  steam 
passes  through  t  into  the  veaael,  p,  which  serveB  to  retain  any  liquid  carried  over  from  c'. 
The  carbonate  of  anunonia  vapour  now  passes  from  r  through  the  tnbe  t*  to  c,  and 
taking  up  in  that  vessel  more  carbonate  of  ammonia,  is  conveyed  through  the  tube  t'  into 
p*  (which  again  serves  the  purpose  of  i).  and  thence  tbrongh  t"  into  the  leaden  wonn  of 
the  condensing  apparatus.  The  condensed  liquor,  a  more  or  less  concentrated  solution  of 
carbonate  of  ammonia,  is  run  through  t"  into  a.  s  wooden  vessel,  lead  lined,  and  fiBed 
with  a  sufficient  quantity  of  aulphoric  acid  to  aaturale  the  carbonate  of  ammonia.  The 
whole  operation  lasts  about  twelve  houre ;  after  this  time  the  waste  liquid  in  the  boHer  ii 


AMMONIA. 


335 


Btilphftte  of  ammoniii,  and  at  each  operstioii  aoo  Wloa.  of  that  salt  are  obtained  by  tbs 

working  of  one  of  the  apparatns  just  deeeribed.  It  is  itated  tbat,  from  the  8oo,oot^ 
onbio  metres  of  nrina  yearlj  mn  waste  in  Faris  alone,  there  eoold  be  obtained,  b; 
proper  treatment,  7  to  800,000  kiloB.  of  Bolphate  of  ammonia. 

i>UKmi>  iniK  bohh.  10.  By  the  destructive  distilliition  o£  bjuidbI  substances,  such  es 
bonea,  hoofs  oF  horses,  refuse  horn,  skills,  hides,  decayed  meat,  Ac.,  there  is  obtained 
a  series  of  products,  among  which  carbonate  of  ammonia  prevails,  with  cyanogen 
compounds,  snlphnret  of  ammonium,  ssd  tarrj  matter — a  very  complex  liquid  con- 
tunisg  pyrrol,  bases  of  the  ethylamin  series,  pyridin,  CJH5N,  picolin,  C^^N,  lutidin, 
C^H,N,  and  colUdin,  CgHuN.  The  organic  matter  of  these  substajices  contains 
from  13  to  18  per  cent  nitrogen ;  the  organic  matter  of  bones  contains  18  per  cent  of 
nitrogen,  and,  as  the  organic  matter  amounts  to  about  one-third  of  the  weight  of  the 
bonea,  these  contain  about  6  per  cent  of  nitrogen.  Buffalo  horn  contains  17,  waste 
wooUen  fiibrics  10,  and  old  leather  67  per  cent  of  nitrogen. 

It  is  evident  that  the  quantity  of  ammonia  in  the  products  of  the  dry  distUlation 
of  aniniftl  substances  depends  upon  the  kind  and  condition  of  these  materials,  and 
upon  the  temperature  at  which  the  operation  takes  place.  The  carbonate  of 
ammonia  is  obtained  in  the  condensers  as  a  solid  saline  mass,  the  crude  ml  comu 
eervi,  or  in  aqueous  solution  |so  called  ipiritui  corau  eervi),  floating  on  the  surface  of 
the  t«r.  At  the  present  time  the  manufacture  of  ammonia  and  its  salts  from  tlie  pro- 
ducts of  the  dry  distillation  of  animal  substances  is  a  matter  of  but  limited  indus- 
trial importance,  owing  to  the  extended  coal-gas  manufacture.  Indeed,  dry  distilla- 
tion is  now  only  carried  on  for  the  purpose  of  obtaining  animal  charcoal,  and  tlie  occur- 
rence of  anunoniacal  products  is  rather  considered  aa  a  necessary  but  unavoidable 
evil.  A  large  quantity  of  animal  matter  is  used  for  the  manufacture  of  phosphorus 
and  of  prUBsiates,  and  in  these  operations  the  manu&cture  of  anunoniacal  salts 
is  either  altogether  out  of  the  question  or  effected  only  on  a  limited  scale. 

_  The  apparatos  aeed  for  the  deBtmctive  distillation  of  animal  matter  in  in  some  respeeta 
dniilar  to  a  coal-gas  oven.  Fig.  115  exhibits  the  conBtraction  in  general  nse  for  what  is 
termed  animal  charcoal  burning.    The  retorts  intended  to  contain  the  bones  are  set  in 


IniBaaei  and  fitted  at  the  end  farthest  from  the  mouth  with  tnbes,  e 
'*itb  leaden  chambers,  b,  0,  &e.  In  these  chambers  the  vaponis  are  condensed,  forming 
a  soEd  laline  mass,  which  is  pnrified  by  aublimation  in  tha  iron  vessels,  d  d,  fitted  with 
leaden  oovers.  If,  instead  of  booes,  other  animal  matters,  for  inatanoe,  horn,  woollen 
tags,  hair,  and  leather-cuttings,  are  operated  upon,  the  result  is  that,  instead  of  solid 


aafi 


CBSmCAL  TECBNOLOOr. 


ot  BHt-Hwrt  aogu 


carbonate  ot  unnoma,  an  ammoniBOal  flnid  of  13°  to  15*  B.  ia  obtained,  wtiloti  may  b» 
ntiliBed  in  varioQB  ways.  Where  the  motheT-liqnors  of  aalt-works  ore  readily  obtun&ble, 
the;  may,  eepedally  U  rich  in  chloride  of  magneaiiim,  be  employed  lor  the  preparation  of 
Bal-ammoniaD  by  naing  the  hartBhom-Bpirit  (crade  carbonate  of  ammonia  BcJation)  for  tb« 
precipitation  of  the  ohloride  of  magneeium  Bolation. 

iS:^"*  When  the  beet-root  juice  is  boiled,  ammonia  ia  evolved  in 
large  quaittities,  and  maj  be  utilised  in  the  preparation  of 
8nlphat«  of  ammonia.  The  ammonia  jielded  by  tte  juioe  ia  the  prodoct  of  the 
decompositiou  of  the  aapartia  acid  and  betain  present  in  the  rooto.  According  tO' 
Renard,  a  beet- root  sngar  manufactory  nhidi  yearly  consumes  200,000  cwta.  of  beets 
might  thus  obtain  887  cwts.  of  sulphate  of  ammonia. 

'SS^iSlS:"  Sal-ammoniac,,  chloride  of  ammoninm.  NH/1,  cmuists  in  100 
parts  of^ 

Ammonia,  3183  Ammonium,  3375 

Hydrochloric  acid,  6822  Chlorine.       66'25 

From  the  thirteenlh  to  the  middle  of  the  eighteenth  centuiy  Uiis  salt  was  imported 
into  Europe  exclusively  from  Egypt,  where  it  was  obtained  by  the  combustion  of 
camel's  dtmg.  The  camel  feeds  elmoat  exclosivelyupon  plants  containing  salts,  and 
the  sal-ammoniac  is  sometimes  found  ready  formed  in  the  animal's  stomach.  The 
sal-ammoniac  having  sublimed  with  the  soot  from  the  ctanbuslion  of  the  dung,  va» 
collected  and  refined  hy  a  second  sublimation. 

In  localities  where  dtmg  is  used  as  fuel,  it  has  been  tried  to  obtain  sal-anunoniac 
by  combustion  with  common  salt.  The  first  sal-ammoniae  manufactory  in  Germany 
was  established  by  Graveuhorat  Brothers,  at  Brunswick,  in  1759.  We  have  already 
^een  bow  crude  sal-ammoniac  may  be  prepared  horn  gas-water  or  by  other  means. 

The  salt,  no  matter  whence  derived,  is  purified  hy  sublimation  in  cast-iron  caul- 
dons,  w,  Fig.  116,  lined  withfire-clay.    AsHoonaathe  crude  sal-ammoniac  is  put  into 


FlQ. 


these  vessels  and  tightly  rammed,  heat  is  applied,  at  first  gently,  so  as  to  drive  ofl 
any  moistDie.  This  effected,  iron  lids,  f,  o,  h,  ore  luted  to  the  cauldrons ;  the  Uds 
can  be  readily  moved  by  means  of  the  pulleys  and  chains  provided  with  eonnter- 
weights,  B.  c.  n.  Instead  of  iron  covers  lead  hoods  sometimes  are  employed,  tha 
opening  of  which  is  temporarily  closed  with  an  iron  disc.  The  hoods  or  covers  oie 
always  securely  fiistened  to  the  cauldrons,  to  prevent  them  being  forced  off  by  the 
pressors  of  the  vapours.  The  temperature  has  to  be  regulated  during  the  proceM 
Vith  great  nice^,  for  Un  low  a  degree  of  heat  yields  a  loose  salt,  and  with  too  hi^ 


a  degree  of  heat  the  oiganic  matter  present  in  the  cnide  Bal-ammoniac  is  liable  to 
give  off  empjTeninatic  matter,  Bpoiling  the  appearance  of  the  sublimed  salt  and 
interfering  with  iia  good  qualitj.  Experience  has  proved  that  it  is  expedient  to 
have  the  sablimation  veHsels  of  rather  Urge  size,  2l  to  3  metres  interior  diameter. 
'Wb^n  the  anblimed  sal-ammoniac  cake  has  attained  a  thickness  of  6  to  12  centims. 
the  operation  is  discontinued  and  the  cake  removed.  The  furnace  is  provided  with 
an  oven  for  drying  the  sal-ammoniac,  this  oven  being  shut  with  a  door,  b,  movable 
by  meane  of  a  chain  mnning  over  a  pnllej,  and  aided  bj  a  counterpoise.  At  the 
present  day  sal-ammoniac  is  often  sublimed  in  earthenware  vessels  or  large  glass 
flasks,  the  crude  salt  being  first  mixed  with  20  to  30  per  cent  of  its  weight  of 
powdered  animal  charcoal,  then  dried  over  a  good  fire,  and  next  put  into  the  stone- 
ware sablimation  vessels,  b  and  m,  Fig.  117,  placed  in  two  rows  over  the  fire  place,  o. 


ings  are  Biirroonded  by  an 

■  tnge  npon  which  rest  the 

condcnEed.     When  glass 

30  centims.  diameter. 


Each  of  these  vessels  is  50  centima.  in  height;  the  openini 
iron  plat«  properly  fitted  to  the  nock  and  provided  « 
earthenware  vessels  wherein  the  sublimed  sal-a 
flasks  are  nsed,  the  height  of  these  vesBels  is  60  centims.  I 
Sixteen  of  these  flasks,  each  charged  with  9  kilos,  of  the  miitnre  of  sal-ammor 
charcoal,  are  placed  upon  a  furnace  in  cast-iron  pots,  which  are  filled  with  sand. 
The  cover  is  in  this  case  a  leaden  plate.  The  aublimatiou  is  ewefullj  conducted, 
and  goes  on  slowly,  lasting  about  iz  to  16  hours.  After  this  time,  the  leaden  plates 
are  removed,  bnngs  or  plugs  of  cotton-wool  inserted,  and  the  flasks  allowed  to  cool 
very  gradually,  for  as  the  salt  expands  on  cooling  the  glsaa  vessels  may  be  broken. 
Tbe  cake  of  sal-anunoniao  when  quite  cool  is  scraped  clean  with  a  knife,  and  after- 
wards presents  a  perfectly  crystalline  appearance.  When  it  is  desired  to  obtain  the 
salt  &ee  from  iron,  the  cmde  salt  shonld  be  mixed,  befm^  the  subiimaticm,  with 
ftboat  5  per  cent  of  superphosphate  of  lima,  or  with  3  per  oent  of  phoephate  of 
anunonift ;  by  this  addition  any  chloride  of  iron  is  decomposed  and  left  in  the  retort 
tts  phosphate.  Tbe  sal-ammoniacof  commerce  is  met  with  either  in  crystalline  state 
or  as  a  compact  fibrous  sublimed  material ;  in  the  htter  case  the  eakes  or  discs  have 
a  meniscus  shape,  weigh  abroad  from  5  to  10,  but  in  England  usually  about  50  kilos,, 
and  exhibit  the  appearance  of  having  been  formed  in  layers.  Crystalline  sal- 
animoniac  is  obtained  by  adding  to  previously  re-cystollised  sal-ammoniac  aboiling  hot 
and  satnrated  solution  of  the  same  salt,  so  as  to  form  a  thickish  magma,  which  i» 
next  placed  in  moulds  similar  in  shape  to  those  in  use  for  making  loaf-sugar ;  after 
draining,  the  loaf  of  sal-ammoniac  is  removed,  dried,  and  packed  in  paper  ready  for 
Bal<.'.     Besides  the  use  made  of  sal-ammoniac  in  cbentical  laboratories,  by  pharma- 


238  CHEMICAL   TECHmiOGY. 

ceutists  and  veterinary  surgeons,  it  is  industrially  in  demand  for  turning,  zincing,  aid 
soldering,  in  calico-printing  and  dyeing,  in  the  manufacture  of  paints  and  pig- 
ments, in  the  preparation  of  platinum,  snufif,  and  yery  largely  in  the  preparation  of  a 
mastic — i  part  of  sal-ammoniac,  2  of  sulphur,  and  50  of  iron-filings — ^used  in  joining 
steam-pipes,  the  sockets  and  spigots  of  iron  gas-  and  water-pipes,  &c.  Sal-ammoniac 
is  also  employed  in  the  preparation  of  pure  ammonia  liquida  and  anmioniacal  salts. 
soiphftt*  of  AmmoBiA.      It  has  bceu  already  mentioned  that  sulphate  of  ammonia — 

iNH4)aS04, 
is  met  with  native  in  small  quantities  in  the  mineral  known  as  mascagnin,  in  larger 
quantities  in  the  boracic  acid  of  Tuscany,  while  it  i»  also  found  in  Boussingaultite. 

The  modes  of  preparing  this  salt  from  the  ammoniaoal  water  of  gas-works,  lant,  the 
produots  of  the  dry  distillation  of  hones,  by  the  aid  of  snlphnric  acid,  or  by  doable 
decomposition  by  means  of  gypsum  or  sulphate  of  iron,  have  been  already  given.  The 
concentration  of  the  weak  solution  by  evaporation  yields  the  crystalline  salt,  which, 
however,  when  obtained  from  Uquors  containing  tarry  matters  is  usually  of  a  deep  bro^m 
colour,  and  has  therefore  to  be  purified  by  being  dissolved  in  hot  water,  filtered  through 
animal  charcoal,  and  then  re-crystallised,  the  best  plan  being  to  evaporate  the  solution 
rapidly,  and  remove  the  salt  gradually  by  means  of  perforated  ladles.  The  salt  is  then 
drained  by  being  placed  in  baskets,  and  next  quickly  dried  on  heated  fire-clay  slabs,  in 
which  operation  any  particles  of  tar  are  decomposed.  Sulphite  of  ammonia  obtained  by 
saturating  carbonate  of  ammonia  solution  with  sulphurous  acid  gas  is,  when  exposed  to 
air,  gradually  converted  into  sulphate.  Sulphate  of  ammonia  is,  industrially  speaking, 
far  the  most  important  of  the  ammonia  salts,  because  besides  being  very  largely  used  in 
artificial  manure  mixtures,  and  by  itself  for  the  same  purpose,  it  is  extensively  employed 
in  alum  making,  and  is  the  starting-point  of  the  preparation  of  chloride  of  ammnTiiTim^ 
carbonate  of  ammonia,  liquid  ammonia,  and  other  similar  products. 

carboutte  of  Ammonia.      The  sslt  uscd  lu  pharmacy  and  industry  under  this  name  is  in 

reality  sesquicarbonate  of  ammonia,  and  composed  according  to  the  formula 

(NH4)4C308,  or  2([NH4]aC03)-f  COa. 

It  is  obtained  either  directly  fi'om  the  products  of  the  distillation  of  bones,  or  by 

subliming  a  mixture  of  chalk  and  sal-ammoniac. 

Among  the  products  of  the  dry  distillation  of  bones  is  found  a  solid  sublimate, 
essentially  impure  carbonate  of  ammonia,  purified  by  sublimation.  For  pharmaceutioal 
use  carbonate  of  ammonia  is  prepared  by  submitting  a  mixture  of  either  chloride  of 
ammonium  or  sulphate  of  ammonia  with  chalk — 4  parts  of  the  ammonia  salt,  4  of  chalk, 
and  I  of  charcoal  powder — to  a  low  red  heat.  The  product  is  a  perfectly  pure  white  saU; 
during  the  operation  a  large  quantity  of  ammoniacal  gas  is  evolved,  which  is  either 
absorbed  br  water  or  by  coke  moistened  with  sulphuric  acid.  Eunheim  decomposes  the 
sal-ammoniac  by  subliming  it  with  carbonate  of  baryta,  chloride  of  barium  being  obtained 
as  a  b^-product.  When  freshly  prepared,  carbonate  of  ammonia  is  a  transparent 
crystalhne  mass,  which,  while  absorbing  water  from  the  atmosphere,  and  evolring 
ammonia,  is  superficially  converted  into  bicarbonate  of  ammonia  (hydrocarbonate  of 

ammonia,     ^^  I  CO3).    Owing  to  the  penetrating  odour  emitted  by  this  salt,  it  is  known 

as  smelling  salts.  Impure  carbonate  of  ammonia  is  also  used  for  cleaning  woollen  and 
other  fabrics,  for  the  removal  of  grease  from  cloth,  and  further,  for  the  extraction  of  the 
orchil  pigments.  Pure  carbonate  of  ammonia,  besides  its  use  in  pharmacy,  is  an 
ingredient  of  baking  and  yeast  powders. 

Kitnta  of  Ammonia.  This  Salt,  (NH4)N03,  is  prepared  by  the  double  decomposition 
of  solutions  of  sulphate  of  ammonia  and  nitrate  of  potassa.  The  sulphate  of 
potassa  is  first  separated,  and  the  solution  of  ammonia  nitrate  having  been  con- 
centrated by  evaporation  is  left  to  crystallise,  its  crystalline  form  being  similar  to 
that  of  saltpetre.  ^Vhen  dissolved  in  water  this  salt  produces  cold»  and  is  therefore 
used  in  freezing  mixtures ;  while  the  fact  that  when  strongly  heated  it  is  converted 
into  protoxide  of  nitrogen  and  steam  (N2O+2H2O)  might  perhaps  render  it  of  use 
in  the  preparation  of  a  blasting  powder. 


SOAP.  239 

SOAP-MAKINO. 

Boft^  By  soap  we  understand  the  product  of  the  action  of  caustic  alkalies  upon 
neutral  £Bits,  and  consequently  soap  may  to  all  purposes  be  considered  to  consist 
of  stearate,  pahnitate,  and  oleate  of  potassium  or  sodium.  Although  soap  has 
been  manufactured  from  a  very  remote  antiquity,  this  industry  did  not  attain 
its  present  development  upon  scientific  and  rational  principles  until  Chevreul  pub- 
lished the  results  of  his  researches  on  the  fats,  and  before  the  discovery  of  Leblanc 
called  the  soda  industry  into  existence. 

BawMuezteisof  Soap-boiling.  The  raw  materials  used  in  soap-boiling,  as  soap  manufac- 
ture is  usually  termed  in  this  country,  are  of  two  kinds,  viz.,  fatty  substances  and 
solutions  of  caustic  alkalies.  Among  the  more  important  fatty  substances  are 
the  following : — Palm-oil,  of  vegetable  origin,  met  with  in  the  fruit  of  a  palm  tree, 
Avoira  slats  or  Elais  guianemis ;  according  to  others,  however,  this  oil  is  derived 
from  the  Cocos  hutyracea,  C.  nricifsra,  and  Arsca  oleraeea,  trees  growing  wild,  and 
also  cultivated  in  Guinea  and  Guiana.  The  colour  of  this  oil  is  a  red -yellow,  its 
consistency  that  of  butter,  while  it  possesses  a  strong  but  by  no  means  disagreeable 
odour,  similar  somewhat  to  that  of  orris  root.  When  fresh,  this  oil  melts  at  27^,  but 
by  becoming  rancid  as  it  is  termed— that  is,  by  its  decomposition  into  glycerine 
and  free  fatty  acids — its  melting-point  rises  to  31°  and  even  to  36°.  It  is  chiefly 
composed  of  palmitine  mixed  with  a  small  quantity  of  oleine.  Palmitine,  formerly 
confused  with  margarin,  is  saponified  by  the  alkalies  and  converted  into  palmitate 
of  potassa  or  soda,  wliile  glycerine  is  set  free : — 

Pabnitine  (tripalmitine),  ^^g  ^q.    I  O3]      [Glycerine,  ^3^5  jOg, 

Hydroxide  of  potassa,  3  KOK  ~ 

(caustic  potassa) 

Palmitic  acid  is  very  similar  to,  and  has  often  been  confused  with,  stearic  acid ; 
the  former  is  in  a  pure  state  a  solid  white  crystalline  mass,  which  fuses  at  62*^.  Palm- 
oil  often  contains  one-third  of  its  weight  of  this  acid  in  free  state,  and  the  quantity 
increases  with  the  age  of  the  oil.  The  red-yellow  pigment  of  the  palm-oil  not  being 
destroyed  by  its  saponification,  the  soap  made  from  this  oil  is  of  yellow  colour,  but 
if,  previous  to  saponification,  the  oil  is  submitted  to  a  bleaching  process,  that 
is  to  say,  the  pigment  destroyed  by  chemical  agents,  such  as  the  joint  action 
of  bichromate  of  potassa  and  sulphuric  acid,  the  oil  becomes  nearly  white,  and 
yields,  on  being  saponified,  a  white  soap. 

The  illipe,  or  bassia-oil,  very  similar  to  palm-oil,  is  obtained  by  pressure  from  the 
seeds  of  the  Bassia  latlfolia,  a  tree  growing  on  the  slopes  of  the  Himalaya.  At  first 
the  colour  of  this  oil  is  yellow,  but  by  exposure  to  sun -light  it  becomes  white.  Its 
odour  is  not  very  strong,  but  rather  pleasant.  At  the  ordinary  tempeiftture  of  the  air 
this  oil  has  the  consistency  of  butter ;  its  sp.  gr.  is  =  0958 ;  its  melting-point  27** 
to  30°.  It  is  somewhat  soluble  in  alcohol,  readily  in  ether,  and  easily  saponified  by 
potassa  and  soda.  In  its  saponification,  oleic  acid  and  two  solid  acids  with  a  variable 
melting-point  are  formed.  The  galam  butter  produced  by  the  Bassia  hutyracec^ 
a  tree  met  with  in  the  interior  of  Africa,  is  sometimes  confounded  with  palm-oil,  to 
which  it  is  veiy  similar,  but  of  a  deeper  red  colour.  Galam  butter  fuses  at  20°  to  21 '^^ 
and  is  in  its  properties  very  much  like  palm-oil.  Carapa  oil  and  vateria  tallow 
belong  to  the  same  class  of  fatty  substances ;  the  first,  the  product  of  the  kernel  of  a 
species  of  Persoonia,  a  palm  tree  met  with  in  Bengal  and  Coromandel,  is  a  bright 


1  Palmitate  of  potassa,  3|^^^^3'^lo. 


240  CHEMICAL  TECHNOLOGY, 

yellow  colonred  material,  which  at  18''  separates  into  an  oil  and  a  solid  fat ;  known 
as  pine-tallow,  Malabar  tallow,  and  obtained  from  the  fruits  of  the  Vdteria  indica, 
is  a  white-yellow  waxlike-tallow,  melting  at  35*.    Mafurra  tallow  is  obtained  by 
boiling  in  water  the  seeds  or  kernels  of  the  mafurra  tree  found  at  Mozambique ; 
this  seed,  very  rarely  seen  in  Europe,  is  of  the  size  of  small  cacao  beans.    Mafurra 
seed  also  occurs  in  the  Islands  of  Madagascar  and  Isle  de  K6union.  The  fat  obtained 
from  this  seed  has  a  yellow  colour,  the  smell  of  cacao  butter,  and  melts  more  readily 
than  tallow.    The  fat  of  the  seeds  of  the  Brindonia  indica^  employed  at  Goa,  instead 
of  butter,  also  for  medicinal  purposes,  and  for  use  in  lamps,  is  nearly  white ;  melt» 
at  40°,  and  is  insoluble  in  cold,  but  somewhat  soluble  in  boiling  alcohol.    Cocoa-nut 
oil,  obtained  from  the  kernels  of  the  cocoa-nut  (Cocoi  nucifera,  C.  hutyracea),  is 
largely  used  in  the  tropics,  where  the  tree  abounds.    This  oil  is  imported  into 
Europe,  and  is  also  obtained  here  by  pressing  and  by  treating  the  kernels  of 
the  imported  nuts  with  sulphide  of  carbon.    It  is  white,  has  the  consistency  of 
lard,  but  possesses  a  disagreeable  odour  and  a  somewhat  foliated  texture;   its 
melting-point  is  22°.    Chemically  considered  this  fat  consists  of  a  peculiar  substance 
termed  cocinin,  with  small  quantities  of  oleine  ;  by  saponification  the  former  yields 
glycerine  and  cocinic  acid   (cocoa-stearic  acid),  CiaH^eOa.    W.  Wicke  obtained 
in  i860,  61 '57  per  cent  of  fed;  from  the  kernels.    During  the  last  twenty  years  cocoa- 
nut  oil  has  been  largely  used  for  soap-boiling,  because  it  is  an  excellent  material  for 
the  preparation  of  so-called  fulling  soaps.    Tallow  is  obtained  by  melting  the  fatty 
matter  deposited  in  the  cellular  tissue  of  the  abdominal  cavity  of  cattle  and  sheep. 
The  hardness  of  the  tallow  depends  partly  upon  the  animals  frx>m  which  it  ift 
derived,  partly  upon  the  food  they  eat ;  if  the  food  be  fodder,  the  hardest  tallow  i» 
produced,  while  if  it  consists  of  the  refuse  from  breweries  and  distilleries  the  tallow 
is  soft.    Kussian  tallow  owes  its  hardness  to  the  fact  that  the  cattle  in  that  country 
are  for  frilly  eight  months  in  the  year  kept  on  dry  fodder.    Generally  tallow  melts  at 
37°,  and  contains  75  per  cent  of  its  weight  of  solid  fatty  matter,  stearin  (tristearin) 
and  palmitin  (tripalmitin),  the  remainder  being  olein.    If  previous  to  being  melted — 
that  is,  separated  by  the  application  of  heat  from  the  cellular  tissue  and  membranes 
in  which  it  is  enclosed — tallow  is  preserved  for  too  long  a  time,  it  obtains  a 
bad  odour,  removed  with  difficulty.    The  operation  known  as  tallow-melting  can 
be  performed  in  two  way»,  either  by  simply  applying   heat,  which  causes  the 
cellular  tissue  to  shrink  and  become  dry,  the  fat  being  expelled ;  or  the  membranes 
and  cellular  tissue  are  destroyed  by  chemical  agents,  viz.,  the  use  of  either 
sulphuric  or  nitric  acid,  or  caustic  ley.     Among  these  methods,  that  of  D'Arcet,  in 
which  sulphuric  acid  is  used,  and  the  operation  carried  on  in  closed  vessels,  is  one  of 
the  best;    the  sulphuric  add  decomposes  the  vapours  which  are  given  off  and 
destroys  their  lietidity,  while  more  tallow  and  of  a  better  quality  is  obtained.    The 
vapours  are  carried  either  into  the  furnace  or  into  condensing  apparatus.     D*Arcei 
recommends  that  to  100  parts  of  cut-up  tallow,  i  part  of  sulphuric  acid  and  50 
parts  of  water  should  be  used.    WMle  the  loss  by  the  ordinary  method  of  tallow- 
melting  amounts  to  15  per  cent,  it  is  only  5  to  8  per  cent  when  this  method  i» 
employed. 

Lard,  owing  to  its  high  price,  is  rarely  used  in  Europe  for  making  soap,  but 
is  largely  employed  in  the  United  States,  where,  especially  at  Cincinnati,  enormous 
quantities  of  lard  are  converted  into  a  solid  fat  (42  to  44  per  cent),  and  into  a  fluid  oil 
(lard  oil,  56  to  58  per  cent). 


SOAP.  *  24X 

Olive-oil  is  obtained  from  the  fruit  of  the  olive  tree,  Olea  EuropeUy  belonging 
to  the  natural  order  of  the  Jasminea,  and  largely  cultivated  in  the  whole  of  Southern 
Europe  and  the  coastlands  of  North  Africa/ 

In  order  to  obtain  an  oil  of  good  quality  it  is  essential  that  the  olives  should 
be  gathered  when  they  are  fully  ripe,  which  happens  in  the  months  of  November  and 
December.  Unripe  olives  yield  an  oil  having  a  harsh  bitter  taste,  while,  again,  over- 
ripe fruit  yields  a  thick  oil,  readily  becoming  rancid.  The  method  of  oH  extraction 
from  olives  as  carried  on  in  Southern  France  is  the  following : — The  ripe  olives  are 
first  reduced  to  pulp  in  a  mill ;  this  pulp  is  put  into  sacks  made  of  strong  canvas, 
or,  better,  of  horsehair,  and  submitted  to  pressure.  The  first  portion  of  oil  thus 
obtained  is  the  best  and  is  known  as  virgin  oil,  or  huile  vierge.  In  order  to  eliminate 
ail  the  oil  as  much  as  possible,  the  cake,  after  the  first  pressing,  is  treated  with 
boiling  water  and  again  pressed.  The  oil  thus  obtained  possesses  a  fine  yellow 
colour,  but  is  more  liable  to  become  rancid  than  the  virgin  oil.  Notwithstanding  the 
second  pressure  the  cake  retains  enough  oil  to  make  it  worth  while  to  submit  it  to 
further  operation.  Some  kinds  of  olive-oil  obtained  by  the  second  pressing  are 
employed,  under  the  name  of  Gallipoli  oil,  in  dyeing  Turkey-red.  This  oil  has  an 
acid  reaction,  consequent  upon  its  containing  free  fatty  acids,  is  turbid,  rancid,  and 
possessed  of  the  property  of  forming  with  carbonates  of  alkalies  a  kind  of  emulsion, 
which  in  dyeing  is  known  as  the  white  bath.  The  olive-oil  used  for  the  purpose  of 
gi'easing  wool  in  spinning  is  known  as  lampant-oil.  Under  the  name  of  Huil^  dtenfer  is 
understood  the  olive -oil  deposited  in  the  tanks,  where  the  water  used  for  adding  to 
the  olives  about  to  be  pressed  is  kept;  it  is  used  in  the  manufacture  of  soap. 
During  the  last  few  years  it  has  become  the  custom  to  exhaust  the  olives  with 
sulphide  of  carbon  instead  of  pressing  them. 

Fish-oil,  seal-oil,  obtained  from  tlie  tliick  skin  of  several  varieties  of  mammalia 
inhabiting  the  seas,  especially  of  tlie  colder  regions  of  the  globe,  and  belonging  to  the 
cetacea  and  phocena,  varies  somewhat  in  its  prop^Hies,  according  to  the  mode 
of  preparation  and  the  animal  from  wliicli  it  has  been  derived.  The  sp.  gr.  of  this  oil 
18  0*927  at  TiQp ;  when  cooled  to  0°  it  deposits  solid  fat ;  it  is  readily  soluble  in 
alcohol,  and  consists  of  oleine,  stearine,  and  small  quantities  of  the  glycerides 
of  valerianic  and  similar  fatty  acids.  Fish-oil,  besides  being  an  important  material 
in  Boap-makiug,  is  also  used  in  tanning,  ta\^dng,  and  leather-dressing  operations. 
Hemp-oil,  obtained  from  the  hemp-seed  (CanfuihU  «^//tt;a),  containing  about  25  per 
cent  of  oil,  is  chiefly  used  for  making  black,  green,  or  soft  soap.  When  fresh 
pressed,  hemp-oil  possesses  a  bright  green  colour,  which  in  time  becomes  a  brown- 
7ellow.  Linseed-oil,  like  the  former  a  so-called  drying  oil,  is  obtained  from  the  well- 
known  linseed  (Linum  iisitatUsimum)  containing  about  22  per  cent  of  this  oil, 
the  sp.  gr.  of  which  is  at  12^=0*9395.  This  oil  consists  chiefly  of  a  peculiar 
glyceride  which  on  being  saponified  yields  a  fatty  acid  difierent  from  oleic  acid ; 
moreover,  linseed -oil  contains  some  palmitin.  Castor-oil,  from  Bieinus  communis y 
^>ehave8  when  sapoifified  very  much  like  cocoa-nut-oil.  As  yet,  however,  this  oil  is 
not  used  in  soap-making.  Rapeseed-oil,  as  it  occurs  naturally,  does  not  yield  so 
good  a  soap  when  saponified  as  when  the  oil  is  first  converted  into  rapselaidifiy 
vbich,  according  to  A.  Miiller,  is  done  in  the  following  manner : — To  i  cwt.  of  the  oil 
is  added  i  lb.  of  nitric  acid  diluted  with  i  J  to  2  lbs.  of  water ;  next  some  iron  nails 
M«  added,  and  the  acid  fluid  is  well  stirred  through  the  oil  with  a  wooden  spatula. 
By  the  action  of  the  nitrous  acid  set  free,  the  oil  is  gradually  converted  into  a  yellow 

B 


244  CHEMICAL  TECHNOLOGY. 

fatty  mass,  which  after  having  been  left  standing  for  some  weeks  in  order  to  solidih% 
may  be  directly  saponified  with  soda.  The  oleic  acid  largely  obtained  in  the  manu- 
facture of  stearine  candles  is  a  very  important  material  in  soap-making.  This  add 
is  a  solution  of  impure  stearic  and  palmitic  acids  in  oleic  acid. 

Colophonium.  the  residue  of  the  distillation  of  oil  of  turpentine,  a  yellow  or 
black-brown  coloured  material,  is  largely  imported  from  the  United  States  for  the 
purpose  of  preparing  resin  soaps,  for  sizing  paper,  and  for  the  preparation  of  yeUow- 
soaps,  which  are  resin  and  tallow  saponified  together  in  certain  proportions. 

Lo7-  The  other  important  material  required  for  soap -making  is  the  ley ;  that  is  to 
say,  an  aqueous  solution  of  caustic  potassa  or  caustic  soda.  Ley  is  not  so  much  a 
constituent  of  soap  as  the  material  by  which  the  chemical  process  termed  saponi- 
fication is  brought  about.  Usually  the  soap-boiler  prepares  the  caustic  ley,  and 
formerly  wood-ash  or  potash  was  used  for  tliis  purpose,  but  at  present  soda  is  mora 
extensively  employed.  The  conversion  of  the  alkaline  carbonates  into  caustic 
alkalies  is  efibcted  by  means  of  quick-lime ;  but  abroad  chemical  manufacturers 
produce  caustic  soda,  and  sell  it  to  the  soap-boilers  xmder  the  name  of  soap-stone. 

The  preparation  of  soap -boilers'  ley  from  wood-ash  is  carried  on  in  the  foUoving 
manner : — The  sifted  ash  is  placed  on  a  paved  floor,  and  moistened  with  enough  water  to 
render  it  somewhat  pasty,  ^his  paste  is  then  formed  into  heaps,  constructed  with  an  in- 
dentation, into  which  the  caustic  lime  in  quantities  of  one- tenth  to  one- twelfth  of  the  weight 
of  .the  ash  is  placed.  Over  the  lime  is  next  poured  sufficient  water  to  cause  it  to  slake, 
care  being  taken  to  cover  the  lune  up  with  ash.  The  ash  and  lime  having  been  thoroughly 
mixed,  are  placed  in  a  tank,  shaped  like  a  cone  from  which  one- fourth  of  the  narrow 
part  is  cat  off,  and  fitted  near  tho  bottom  with  a  tap.  At  a  distance  of  some  five  inches 
from  the  bottom  a  false  and  perforated  bottom  is  fixed,  so  that  the  ley  can  coUect  between 
the  two  bottoms.  Under  the  tap  a  large  iron  tank  is  placed  to  receive  the  ley.  The  mixture 
of  ash  and  lime  having  been  placed  upon  a  layer  of  straw  upon  the  perforated  bottom, 
and  care  having  been  taken  to  squeeze  the  mass  together,  water  is  poured  over  it  for 
the  purpose  of  lixiviating  the  material  until  completely  exhausted.  Usually  three  differeDt 
kinds  of  ley  are  prepared  and  kept,  viz. — i.  Strong  ley,  i8  to  20  per  cent  of  alkali;  2. 
Middling  strong  ley,  8  to  10  per, cent  of  alkali;  and  3.  Weak  ley,  containing  only  i  to  4 
per  cent  of  alkali.  This  weak  liquor  is  commonly  used  instead  of  water  for  Uxiviatio^ 
a  new  ash  and  lime  mixture.  The  sodium-alnminate  obtained  by  the  decomposition  of 
cryolite  is  used  in  the  United  States  under  the  name  of  "  Natrona  refined  aaponijUr,^*  for 
soap  manufacturing  purposes.  Sulphuret  of  sodium  may  also  be  used  instead  of  caustic 
alkali. 

Theoty  of  SAponifleation.      Before  Chcvreul  published  his  researches,  it  was  supposed 

that  fats  and  oils  possessed  the  property  of  combining  with  alkalies.     Chevreul 

found,  however,  that  fats  separated  from  their  state  of  combination  as  soaps 

possessed  properties  difiering  from  those  existing  before  they  were  saponified,  the 

fact  being  that  the  substances  we  are  acquainted  with  as  oil  or  fats  are  compounds 

of  peculiar  acids,  stearic,  palmitic,  margaric,  oleic,  all  non-volatile  substances; 

while  certain  fats  which  give  ojff  a  peculiar  odour  contain  in  addition  to  these  adds 

volatile  fatty  acids,  as  butyric,  capric,  capronic,  valerianic,  &c.    The  volatile  acids 

in  the  ordinary  oils  and  fats  are  combined  with  a  sweet  material,  discovered  by 

Scheele,  and  known  under  the  name  of  glycerine. 

According  to  Berthelot's  researches  it  is  held  that  all  the  oils  and  fats  which  are 

used  in  soap-making  are  ethers  of  glycerine,  C3H8O3,  that  substance  being  viewed  as  a 

trivalent  alcohol,  ^  5  I  q^  Palmitin,  for  instance,  tlie  main  constituent  of  palm- 
oil,  is  glycerlyl-tripalmitate,  or  tiipaimitin,  that  is  to  say,  glycerine  in  which  three 
atoms  of  hydrogen  are  replaced  by  the  radical  of  palmitic  acid,  Z'A   |i    n  I  ^^' 


Tripalmitin    j^^f,k3.oW3 
and  Caustic  soda,  3NaOH, 


SOAP,  243 

tStearine  (tristearine)  and  oleine  (trioleine)  have  an  analogous  conetitiition.  Wlien 
the  fats,  take  palm-oil  for  instance,  are  saponified  with  caustic  alkalies,  say  caustic 
soda,  the  fat — ^that  is,  in  chemical  parlance,  the  ether — is  decomposed  into  alcohol,  i.e., 
glycerine,  and  sodium  palmitate,  i.e.y  soap,  according  to  the  following  equation: — 

^  [Glycerine,  ^sHs I O3, 

•^  '  ^  rC    H    O) 

V»  and  Soap,  or  sodium  palmitate,  3 1  ^^^    ^i    I  q. 

The  glycerine  formed  during  the  process  of  saponification  remains,  after  the 
separation  of  the  soap,  dissolved  in  tlie  mother-liquor  from  wliich  it  is  prepared. 
.It  is  clear  that  such  fats  as  palm-  and  cocoa-nut  oil,  whic^li  in  their  ordinary  sfcite 
contain  fatty  acids,  are  more  readily  saponitied  than  the  perfectly  neutral  fats,  viz., 
olive-oil  and  tallow ;  wliile  the  oleic  acid  derived  from  the  stearino  candle  manu- 
factories is  readily  saponified  by  carbonated  alkalies.  This  observation  applies  to 
colophonium  (resin),  which  consists  essentially  of  a  peculiar  acid,  pinic  acid,  but 
in  these  instances  no  real  saponification  takes  place,  inasmuch  as  no  glycerine  is 
formed.  The  decomposition  of  ^  fat  by  an  alkali  does  not  take  place  suddenly  and 
throughout  the  whole  of  the  fat  at  once,  in  the  manner  of  inorganic  salts,  but  passes 
through  several  stages,  the  first  being  the  formation  of  an  emulsion  of  ley  and  fat ; 
next  fat  acids  and  fat  acid  salts  are  formed,  retaining  the  rest  of  the  fatty  matter  in 
Buspension ;  gradually  tlie  free  fatty  matter  is  saponified,  and  the  fat  acid  salts  are 
converted  into  neutral  salts,  or  in  other  words,  soap. 

When  caustic  potassa  is  used,  soft  soaps  are  produced,  wliile  tlie  hard  soaps 
result  from  the  use  of  caustic  soda.    We  distinguish  soaps : — 

a.  As  hard  soaps  or  soda  soaps. 
p.  As  soft  soaps  or  potassa  soaps. 

*  According  to  the  fatty  substances  used  in  soap-boiling,  soaps  arc  distinguished  as 
tallow,  oU,  palm-oil,  oleic  acid,  cocoa-nut,  fish -oil,  and  resin  soaps,  &c.  Technically,  hard 
soaps  may  be  divided  into : — 

1.  Nucleus  Eoaps. 

2.  Smooth  soaps. 

3.  FuUing  soaps. 

The  term  nucleus  soap  designates  the  soap  that  after  having  been  mode  and 
separated  from  the  ley  by  the  aid  of  common  salt  is  boiled  down  to  a  unifr)rm  mass,  fre«» 
from  air  bubbles,  and  exhibiting  after  soHdification  small  crystalline  particles.  The 
portion  of  the  soap  which  docs  not  separate  in  that  state  assumes,  by  becoming  mixed 
with  a  large  or  smaller  quantity  of  the  impurities  of  the  ley,  a  mottled  appearance.  Tho 
soap  directly  separating  by  the  addition  of  salt  into  globules  or  nuclei  is  pure  soap,  free 
from  any  adhering  ley,  water,  or  glycerine.  Smooth  soop  is  obtained  by  boiling  for  some 
time  with  either  water  or  weak  ley,  the  soap  taking  up  a  portion  of  the  water,  and 
losing  the  crystalline  and  mottled  appearance.  In  the  preparation  of  this  soap  it  is 
first  separated  by  means  of  salt  from  the  mother-liquor  (in  saline  solutions  soap  is  in- 
soluble), but  after  that  separation  the  soap  is  boiled  with  weak  ley.  The  only  difference 
existing  between  the  two  kinds  is,  that  the  latter  contains  more  water  than  the  former. 
The  fulling  soap,  at  the  present  that  chiefly  met  with  in  commerce,  is  essentially  the 
worst  kind  of  soap,  as  an  insufficient  quantity  of  salt  is  used,  the  result  being  that  the 
entire  contents  of  the  boiling-pan  are  kept  together.  The  process  of  boiling  is  con- 
tinned.until  on  cooling  the  mass  solidifies.  The  soap  is  removed,  cut  into  bars,  and  sold. 
Soap  niade  from  cocoa-nut  oil  possesses  especially  the  property  of  being  hard  and  dry 
notwithstanding  that  it  contains  a  large  amount  of  water ;  consequently  the  use  of  cocoa- 
nut  oil,  both  alone  and  with  other  fats  to  which  it  imparts  its  property,  is  greatly  on  the 
increase.  Soaps  of  this  kind  will  produce  250  to  300  parts  of  soap  from  100  of  oil. 
chw  varkdies  ^he  German  tallow  soap  or  curd  s.  ap  is  essentially  a  mixture  of  stearate 
of  s<Mip.  of  sodsk  and  palmitate  of  soda,  and  is  commonly  prepared  indirectly  by 
first  saponifying  tallow  with  caustic  potassa,  and  next  converting,  by  meoiiK  of  common 
salt,  the  stearate  and  palmitate  of  potassa  into  the  corresponding  soda  compound. 

R  2 


244  CHEMICAL  TECHNOLOGY. 

The  soap-boiling  pan  employed  is  somewhat  conical  in  shape.  It  is  made  of  oast-iron,  and 
provided  at  the  top  with  a  high  lintel  or  bulwark  to  prevent  any  fluid  boiling  over.  Supposing 
it  to  be  intended  to  convert  lo  owts.  of  tallow  into  soap: — Into  the  cauldron  is  first 
poured  about  500  litres  of  strong  lye  at  20  per  cent  ( =  1*226  sp.  gr.) ;  next  the  tallow  is  added, 
and  a  wooden  or  iron  lid  having  been  fitted  to  the  cauldron,  the  fire  is  kindled.  When 
ebullition  sets  in,  it  is  kept  up,  with  occasional  stirring  of  the  contents  of  the  cauldron,  for 
five  consecutive  hours.  The  materials  in  the  cauldron  are  converted  into  soap-glue,  as  it 
is  termed,  a  gelatinous  masR,  which,  if  the  operation  has  been  well  conducted,  ought  not, 
upon  the  addition  of  fresh  ley,  to  become  thin,  while  it  also  should  not  flow  in  drops,  but 
similarly  to  treacle  from  a  spatula.  The  production  of  this  substance  is  promoted  by 
.addiug  oil  of  tallow  to  the  ley  gradually  and  in  small  portions  at  a  time. 

Mege-Mouries  recommends  either  yolks  of  eggs,  bile,  or  albuminous  compounds.  As  proved 
by  the  researches  of  F.  Knapp,  it  is  always  advantageous  to  first  convert  the  fat,  with  the 
requisite  quantity  of  ley,  into  an  emulsion,  and  to  leave  the  ley  either  not  heated  at  all  or 
only  to  50''  in  contact  with  the  fat,  so  as  to  saponify  first  slowly  in  the  cold  and  to  finish 
off  with  ebullition.  When  caustic  soda  ley  is  used  it  is  of  a  density  ~  10**  to  12^  B. 
(=  1*072  to  i'o88  sp.  gr.)  When  the  saponification  is  complete  the  operation  of  fitting  or 
parting  is  proceeded  with,  and  consists  in  adding  12  to  16  lbs.  of  salt  to  100  of  tallow. 
The  soap  is  kept  boiling  until  the  soap-glue  has  become  a  grayish  mass,  from  which 
the  mother-liquor  or  under-ley  readily  separates,  the  latter  being  let  off  by  a  tap ;  or,  if 
no  tap  is  fitted  to  the  cauldon,  the  soap  is  gradually  ladled  over  into  the  cooling-tank. 
The  addition  of  salt  not  only  aims  at  the  separation  of  the  soap  from  the  ley,  but  also 
at  the  partial  conversion  of  the  potassa  into  soda-soap.  If  the  soap-glue  has  been 
removed,  it  is  again  put  into  the  cauldron,  and  there  is  J^ded  a  moderately  strong  ley 
and  heat  again  applied.  The  soap  again  becomes  quite  miid,  but  consists  chiefly  of  soda- 
Boap  glue.  The  ebullition  is  kept  up,  and  during  its  continuance  fresh  ley  and  salt  are 
added  alternately.  By  continued  boiling  the  soapy  mass  becomes  more  and  more  con- 
centrated ;  as  soon  as  the  foaming  ceases,  and  the  whole  mass  is  in  a  steady  ebullition,  it 
is  again  ladled  over  into  the  cooling-taiik,  or  the  mother-liquor  is  tapped  off.  The  object 
to  be  gained  by  this  second  boiling  is  the  conversion  of  the  material  into  a  uniform  mass 
free  from  air-bubbles ;  another  is  promoted  by  beating  with  iron  rods.  The  hot  soap  is 
next  placed  in  a  wooden  box,  so  constructed  that  it  can  be  taken  to  pieces ;  upon  the 
bottom  of  this  box,  which  is  perforated,  a  piece  of  doth  is  stretched,  so  as  to  allow  of  any 
adhermg  ley  running  off.  When  the  soap  is  cool  the  box  is  taken  to  pieces,  the  soap  cut 
into  bars,  and  these  placed  in  a  cool,  dry  room.  The  cutting  of  the  soap  into  bars  is  now 
effected  by  machinery ;  formerly  it  was  performed  by  hand  with  a  peculiar  tool,  a  ooppef- 
wire  with  suitable  handles,  such  as  cheesemongers  sometimes  use.  10  cwts.  of  tallow  yield  on 
an  average  16}  cwts.  of  soap,  which  by  drying  loses  some  10  per  cent.  As  it  is  impossible, 
even  with  repeated  applications  of  salt,  to  convert  potassa-soap  completely  into  8oda-«oap, 
the  German  nucleus,  or  KernseifCy  is  always  mixed  with  a  considerable  quantity  of 
potassa-soap,  to  which  it  owes  its  peculiar  softness.  According  to  the  re8e:u-ches  of 
Dr.  A.  C.  Oudemans  (i86g)  only  half  the  potassa  is  converted  into  soda-soap. 

ouve-ou  Soap.  This  kind  of  soap,  also  known  as  Marseille,  Venetian,  or  Gastilian  soap,  is 
chiefly  prepared  in  the  southern  parts  of  Europe.  The  olive-oil  is  frequently  mixed  with 
other  kinds  of  oil,  such  as  linseed,  poppy-seed,  cotton-seed  oil,  <&c.  Two  kinds  of  ley  are 
•employed  in  the  preparation  of  this  soap :  the  first  ley  is  only  a  caustic  soda  solution, 
and  used  for  fitting  or  preparatory  boiling ;  the  other  ley  is  mixed  with  common  salt, 
and  intended  to  effect  the  separation  of  the  soap.  The  preparatory  boiling  aims  at  the 
formation  of  an  emulsion  or  the  production  of  an  itat  globtUaire,  whereby  the  contact  of 
oU  and  alkali  is  greatly  promoted,  and  a  real  soap-glue  ultimately  results.  In  order  to 
remove  the  water  from  this  m iterial  as  much  as  possible,  a  ley  containing  common  salt  is 
employed,  and  lastly  by  a  third  boiling  the  saponification  is  rendered  complete.  By  the 
use  of  the  ley  containing  common  salt  it  is  possible  to  keep  the  soap-glue  in  such  a  con- 
dition that  it  can  take  up  alkali  without  combining  with  the  water.  The  preparatory  boiling, 
or  fitting,  is  carried  on  in  large  copper  vessels,  capable  of  containing  250  cwts.,  the 
caustic  soda  employed  for  this  purpose  having  a  strength  of  6°  to  g**  B.  (»  1*041  to  1*064 
6p.  gr.)  The  ley  is  brought  to  ebullition  first,  and  the  oil  to  be  saponified  is  next 
added,  care  beiug  taken  to  stir  the  mixture  in  order  to  promote  the  reaction.  Gradually 
the  mass  becomes  thick,  and  as  soon  as  black  vapours  arise,  due  to  the  decomposition  of 
a  small  quantity  of  the  soap-glue  by  coming  in  contact  with  the  very  hot  copper,  there  is 
added  the  stronger  ley  of  20°  B.  (1*157  sp.  gr.)  If  it  is  intended  to  produce  a  blue- 
white  soap,  some  sulphate  of  iron  is  added.  As  soon  as  the  mass  has  become  sufficiently 
thick,  the  soda-ley  mixed  with  salt  is  added.  After  some  hours  the  soap  entirely  separates 
from  the  mother-liquor,  which  is  then  run  off,  and  fresh  ley  added  also  coutainiug  common 
salt.  The  final  boiling  is  then  proceeded  with,  the  ley  having  a  strength  of  20"*  to  28"  B. 
The  ebullition  is  continued  gently  until  the  alkali  is  exhausted,  when  the  mother-liquor 


80AP»  245 

is  again  nin  off,  and  fresh  ley  mixed  with  common  salt  again  added  ;  this  operation  is 
repeated  some  fonr  to  six  times,  when  the  soap  is  at  last  quite  ready.  This  stage  is 
indicated  by  the  absence  of  all  smell  of  oil  and  the  pecoliar  grain  of  the  mass,  which  is 
left  to  cool ;  but  if  sulphate  of  iron  has  been  added,  it  is  necessary  to  stir  the  soap  cou- 
tiuuoasly  until  nearly  cold,  in  order  to  produce  the  mottled  appearance  due  to  the  forma- 
tion of  sulphuret  of  iron  from  the  sulphate  by  the  action  of  the  sulphuret  of  sodium  of  the 
Boda-ley.  Mottled-soap  is  produced  in  England  by  adding  a  concentrated  solution  of 
crude  caustic  soda  containing  sulphuret  of  sodium  to  the  liquid  soap,  previously  impreg- 
nated with  sulphate  of  iron.  When  nearly  cold  the  soap  is  placed  in  wooden  boxes  and 
left  to  completely  solidify.  After  ten  to  twelve  days  it  is  ready  for  being  cut  into  bars. 
64 litres  of  oil,  =  58  to  60  kilos.,  yield  go  to  95  kilos,  of  soap.  White-oil  soap  is  prepared 
in  a  similar  manner,  but  purer  materials  are  employed.  A  good  sample  of  Marseilles 
mottled  soap  should  contain : — 

I.  n. 

Fat  adds     63  62 

Alkali 13  II 

Water 24  27 

100  zoo 

OMo  Add  Soap.  Is  obtained  from  crude  oleic  acid,  a  by-product  of'stearine  candle 
manufacture.  The  oleic  acid  produced  by  the  distillation  process  is  less  suitable  for 
803p-making  pnrpoaes.  Oleic  acid  is  sapouitiei  simply  by  being  mixed  with  a  strong 
Bolntion  of  carbonate  of  soda,  or  by  the  application  of  caustic  soda.  In  the  use  of  the 
carbonate  of  soda,  however,  there  is  the  disadvantage  of  the  effervescence  due  to  the 
evolution  of  carbonic  acid,  and  consequent  boiling  over  or  spiUiug  of  the  materials. 
Pitman  uses  the  carbonate  of  soda  in  a  dry  state.  Heat  is  best  applied  by  Morfit's 
arrangement,  in  which  steam  is  passed  through  a  system  of  pipes  moved  by  machinery 
and  acting  as  stirrers.  Besin  is  sometimes  added.  As  soon  as  the  mass  has  acquired 
sufficient  consistency,  and  the  effervescence  ceases,  the  soap  is  put  into  moulds  to  cool 
and  solidify.  When  caustic  soda  is  used,  half  the  ley  (sp.  gr.  i'i5  to  1*20  =  20°  to  25°  B.) 
Ib  first  poured  into  the  cauldron  and  brought  to  ebullition,  next  the  oleic  acid  is  added, 
and  as  soon  as  the  soap-glue  is  formed,  the  other  half  of  the  ley  is  put  in,  and  the  ebul- 
lition continued  until  the  soap  is  formed.  The  separation  from  the  mother-liquor  is 
greatly  promoted  by  the  addition  of  some  salt.  The  soap  is  poured  into  moulds  to 
cool  and  solidify.  In  order  to  impart  greater  hardness  to  the  soap,  some  5  to  8  per 
<'6ut  of  tallow  is  added  to  the  oleic  acid.  100  kilos,  of  oleic  acid  yield  from  150  to 
160  kiioB.  of  soaps,  which,  when  weU  made,  consists  in  100  parts  of — 

Fat  acids 66 

Soda 13 

Water " 21 


100 


BdiaTBiiaw  9<Mip«.  Colophonlum  and  ordinary  fir-tree  resin  combine  at  boiling  heat  more 
'^ftdily  with  alkalies  thsdi  fats  and  oils ;  but  the  compounds  obtained  by  treating  resins 
uone  with  alkalies  are  not  soaps  in  a  chemical  sense,  nor  have  they  the  appearance  or 
properties  of  soap.  When  tallow  is  saponified  with  a  portion  of  resin,  a  true  soap  is 
obtained.  In  England  resin-tallow  soap  is  manufactured  very  largely  by  first  preparing  a 
tallow-soap,  and  when  this  is  ready  adding  to  it  about  50  to  60  per  cent  of  the  best  resm 
proriously  broken  into  small  lumps.  The  mass  is  thoroughly  stirred,  and  after  the  resin 
UM  become  incorporated  with  the  tallow,  the  mother-liquor  or  under-ley  is  run  off,  and 
the  Boap-making  finished  by  boiling  with  a  quantity  of  fresh  ley  at  7°  to  8'*  B.  The  inso- 
mble  alumina  and  iron  soaps  having  been  removed  as  scum  from  the  top  of  the  liquid, 
^  hot  soap  is  poured  into  moulds  made  of  wood  or  sheet-iron  ;  sometimes  palm-oil  is 
•dded  in  order  to  improve  the  colour,  of  the  soap.  Usually,  palm-oil  is  not  saponified 
uone,  but  is  added  to  tallow ;  by  treating  a  mixture  of  2  pa^s  of  tallow  and  3  parts  of 
Pum-oil  with  potassa  or  soda-ley  in  the  ordinary  manner,  and  by  mixing  this  soap  with  a 
nnn  soap  prepared  from  i  part  of  resin  and  a  proper  quantity  of  potassa-ley,  the  German 
pabn-oil  soap  is  obtained. 

^oUbig'Softpi.  As  it  is  possible  to  incorporate  soda-soaps  with  a  certain  quantity  of  water 
witboat  impairing  the  appearance,  the  soap-boilers  at  the  present  day  only  prepare  so- 
«jflfid  fulling-Boaps,  that  is,  such  as  are  not  completely  separated  from  the  under-ley  by 
"»  aid  of  salt.  These  soaps  contain,  in  addition  to  water,  glycerine  and  the  salts 
ezistiiig  in  the  nnder-ley.  It  is  owing  to  the  large  amount  of  water  contained  that  the 
Boap-boiier  is  enabled  to  sell  cheap  soaps  notwithstanding  the  very  greatly  increased  price 


346  CHEMICAL  TECHNOLOGY, 

of  fatty  substanoes.  Soap  of  this  kind  (in  Germany  known  as  Esohweger  soap)  appears 
when  freshly  made  quite  hard  and  dry,  though  containing  such  a  large  quantity  of  water. 
It  is  possible  to  make  from  loo  kilos,  of  fatty  matter  300  kilos,  of  good,  bright,  hard  soap. 

The  manufacture  of  cocoa-nut  oil  soap  resembles  that  of  the  other  kinds  of  soap. 
With  a  weak  ley  cocoa-nut  oil  does  not  form  the  emulsion  common  to  other  soaps, 
but  swims  on  tlie  surface  as  a  clear  fat ;  when,  by  boiling,  the  ley  has  reached  a 
proper  consistence,  the  oil  suddenly  saponifies.  A  strong  soda-ley  is  used  in  the 
preparation  of  this  kind  of  soap.  Cocoa-nut  oil  in  saponifying  does  not  separate 
from  the  under-ley,  therefore  potash-ley  is  never  employed.  To  prevent  the  separa- 
tion of  the  soap  from  tlie  mixing,  the  quantiiy  of  caustic-ley  used  must  be  accurately 
measured.  Pure  cocoa-nut  oil  soap  hardens  quickly.  It  is  white,  like  alabaster, 
shiny,  soft,  and  easily  lathered ;  it  has,  however,  a  peculiarly  unpleasant  smell, 
which  cannot  be  entirely  masked  by  any  perfume.  Cocoa-nut  oil  is  seldom  used 
alone,  but  usually  as  an  addition  to  palm-oil  and  tallow.  This  kind  of  soap  can  be 
made  without  boiling,  by  merely  heating  to  80^  C,  by  means  of  steam,  to  melt  the 
&t8,  a  strong  soda-ley  being  added,  and  the  mixture  quickly  stirred.  This  is  known 
as  the  "  cold  method,"  and  soap  can  be  thus  prepared  in  large  quantities  in  a  short 
time,  and  is  generally  hard  and  dry.  When  exposed  to  the  air  for  a  month  or  so, 
the  soap  loses  considerably  in  weight,  and  becomes  effloresced  superficially.  B.  Unger 
(1869)  prepares  a  soap  in  the  following  manner : — He  saponifies  palm-oH  with  soda- 
ley  and  salt  as  usual.  The  product  is  palmitate  of  soda.  At  the  same  time  cocoa- 
nut  oil  is  saponified  by  means  of  carbonated  and  caustic  soda-ley;  this  is  added  to  the 
palm-oil  soap,  and  they  are  boiled.  As  a  rule  there  are  taken  2  parts  of  palm-oil  to 
I  part  of  cocoa-nut  oil ;  and  to  100  parts  of  the  latter  there  are  added  14-3  parts  of 
caustic  soda  (Na^O)  and  12*8  parts  of  carbonate  of  soda.  According  to  Unger  s 
experiments,  this  soap  contains  5  mols.  palmitate  of  soda,  i  mol.  carbonate  of  soda, 
and  X  mol.  water.  The  "  marbling "  or  "  mottling  "  is  eflfected  in  the  following 
manner : — Colouring  matters,  oxide  of  iron,  brown-red,  Frankfort-black,  are  mixed 
with  a  small  portion  of  soap  ;  this  is  poured  into  the  rest  of  the  soap,  with  which  it 
forms  layers  of  unequal  thickness.  The  entire  mass  is  now  stirred,  and  by  this 
means  a  marbled  or  grained  appearance  imparted. 

Soft-soap.  As  before-mentioned,  potash  forms  with  fats  and  oils  only  a  sofi-goap, 
wliich  does  not  dry  when  exposed  to  the  air,  but  on  the  contrary  absorbs  water, 
remaining  constantly  like  a  jelly.  As  a  rule,  these  so-called  soaps  are  impure  solu- 
tions of  oleate  of  potash  in  an  excess  of  potash-ley,  mixed  with  the  glycerine  sepa- 
rated in  the  saponification.  Soft-soaps  can  be  prepared  only  with  potash-le3r8, 
altliough  in  practice  i  part  of  soda-ley  is  substituted  for  a  part  of  the  potash  to  assist 
in  somewhat  hardening  the  soap.  There  is  no  separation  of  the  soap  from  the 
under-ley,  which  contains  all  the  impurities ;  consequently  these  are  disseminated  in 
the  soap. 

In  consequence  of  tlie  solubility  and  cleansing  properties  of  soft-soap,  its  use  is 
preferred  to  that  of  soda-soap  in  the  manufacture  of  cloth  and  wooUen  articles.  It 
>vill  have  been  seen  that  the  difference  in  manufacturing  hard-  and  soft-soaps 
ojnsistsin  employing  potash-ley  for  the  latter,  and  soda  for  the  former.  Wood-ash 
is  not  used  in  prepai-ing  the  potash-ley,  but  always  pure  potash;  the  preparation 
follows  the  usual  method  with  caustic  lime.  The  fats  used  are  mixtures  of  the 
vegetable  and  animal  oils,  as  the  fish-oil  known  as  "  Southern,"  with  rape,  hemp,  and 
linseed  oils.    The  particular  oil  used  varies  according  to  the  time  of  the  year  and 


SOAP.  247 

Inarket  price:  in  winter  the  soft  oils  are  employed;  i\\  summer  the  firmer  oils. 
Soft-soap  is  generally  used  for  falling  and  scouring ;  but  abroad  it  is  sometimes  used 
for  wasliing  linen,  to  which  it  imparts  a  most  disagreeable  fishy  odour,  hardly 
concealed  by  any  amount  of  perfume.  The  best  soft-soap  is  made  from  hemp -seed 
oil,  this  oil  imparting  a  green  tinge,  which,  however,  can  be  imitated  by  adding  indigo 
to  inferior  soaps.  Summer  soap,  as  it  is  termed,  contains,  owing  to  the  fat  employed, 
more  palmitate  of  potash  in  proportion  to  oleate  than  the  winter  soap.  Sometimes 
saponification  is  effected  with  a  mixture  of  hemp-  and  pahn-oil  or  tallow,  of  train-oil 
and  tallow,  &c. 

The  boiling  of  the  soft-soap  commences  witli  a  strong  ley  containing  8  to  10  per 
cent  potash,  by  which  an  emulsion  is  formed.  The  scum  is  dashed  about  with  a 
stick,  the  beating-stick,  and  by  this  means  all  the  alkali  is  caused  to  be  taken  up.  A 
fresh  ley  is  tlien  added,  and  the  boiling  continued,  until  the  soap  upon  cooling 
stiffens  into  a  clear  tough  mass.  When  the  soap  contains  too  much  caustic  alkaU, 
which  can  be  ascertained  by  the  taste,  more  oil  is  added.  The  dear-hoiling  now 
commences,  during  which  the  excess  of  water  is  removed.  To  avoid  lengtliy  evapo- 
ration a  coucentrated  ley  is  employed,  and  the  soap,  instead  of  bubbling  up,  has  its 
surface  covered  ^vith  blisters  as  large  as  the  hand ;  these  blisters  are  termed  leaves. 
When  the  boiling  is  finished — ascertained  by  placing  some  of  tlie  soap  to  cool  on  a 
glass  plate,  from  which,  if  fiim,  it  can  be  separated — the  soap  is  cooled,  and  stored 
in  barrels. 

Soft-soap  will  take  up  a  considerable  quantity  of  water-glass  solution  without 
alteration.  Kecently,  for  fulling,  there  has  been  added  to  the  soft-soap  a  solution  of 
sulphate  of  potash,  or  a  mixture  of  alum  and  common  salt,  and  also  potato-starch. 

variom  otibPr  Boapi.  Another  Boap  is  prepared  from  hog's-lard,  and  when  scented  with  oil 
of  almonds  or  essence  of  mirbane  (nitrobeuzol)  is  sold  as  almond-soap,  and  as  a  cosmetic. 
A  soap  is  mode  from  the  grease  of  sheep's-wool.  The  so-called  bone-soap  is  nothing  more 
than  a  mixture  of  the  usual  hard  or  cocoa-nut  oil  soap  with  the  jelly  from  bones.  The  bones 
are  first  treated  with  muriatic  acid  to  separate  the  phosphate  of  calcium.  A  variety  of 
bone-Boap  is  the  Liverpool  common  soap.  Flint-soap  is  an  oil-  or  tallow-soap  with  which 
nhceous  earth  is  mixed.  When  powdered  pumice-stone  is  substituted  for  the  siliceous 
earth,  the  soap  is  called  jmmic£-soap.  In  America  as  well  as  in  England  a  water-glass 
solution  is  substituted  for  the  siliceous  earth,  although  according  to  Seeber  the  result  is 
not  BO  efficacious.  Cocoa-nut  oil  soap,  however,  containing  24  per  cent  silicate  of  soda 
and  50  per  cent  water,  is  very  firm.  In  the  United  States  water-glass  is  added  to  the  soap 
when,  still  hot  from  the  boiling-pan,  it  is  poured  into  the  moulds.  The  water-glass 
Bolution  is  of  a  density  =  35°  B.  (=  1*31  sp.  gr.) ;  the  proportion  of  soap  is  60  per  cent. 
This  kind  of  water-glass  soap  generally  sets  hard.  Recently  cryolite  and  aluminate  of  soda 
have  been  employed. 

Toilet  SMpa.       On  accouut  of  the  reduction  in  tlie  duty  toilet  soaps  are  now  very 
largely  in  demand.    They  are  generally  made  by  re -melting  and  perfuming  common 
soap.     English  toilet  soap  is  considered  the  best,  as  that  of  France  and  Germany 
being  perfumed  while  cold  is  not  so  equable  a  product. 
There  are  three  modes  of  preparing  toilet  soap,  viz. — 

1.  By  re-melting  raw  soap; 

2.  By  the  cold  perfuming  of  odourless  soap ; 

3.  By  direct  preparation. 

I.  In  the  method  of  re-melting,  good  raw  soap  is  scraped,  into  a  boiling  pan,  and 
after  melting  and  skimming  the  perfume  is  added.  The  soap  is  then  cast  in  moulds 
of  the  required  form.  2.  In  the  method  of  perfuming  in  the  cold,  odourless  soap  is 
cut  into  fine  shreds  by  a  machine ;  the  perfume  is  then  added,  and  the  soap  is  passed 


248  CHEMICAL  TECHNOLOGY. 

between  rollers,  the  sheets  or  bars  tlius  formed  being  cut  into  tablets.  Strave,  of 
Leipsic,  has  invented  a  machine  by  means  of  which  soap  is  stamped  into  the  shape 
required.  3.  The  direct  preparation  of  toilet-soap  consists  in  colouring  and  scenting 
pure  white  common  soap  without  an  intervening  cooling.  The  colouring  materials 
are — for  red,  cinnabar,  coralline,  and  fuchsine;  the  violet  tar  colour  for  violet;  for 
blue,  ultramarine ;  for  brown,  a  solution  of  raw  sugar  or  carameL  Windsor  soap 
is  prepared  in  the  following  manner: — 40  pounds  of  mutton  tallow  and  15  to  20 
pounds  of  olive-oU  are  mixed  with  soda-ley  marking  19°,  making  a  soap  of 
15°;  finaUj,  with  ley  marking  20°,  when  the  soap  is  of  the  consistency  of  marrow. 
The  excess  of  ley  is  then  neutralised.  When  the  soap  is  set  it  is  allowed  to  stand 
six  to  eight  hours,  and  during  this  time  most  of  the  under-ley  separates.  It  is 
then  placed  in  a  flat  form,  and  pressed  until  no  fluid  exudes.  It  is  scented 
with  cumin  oil,  bergamot,  oil  of  lavender,  oil  of  thyme,  &c.  Moist  sugar  is  used 
to  impart  the  brown  colour.  Hose  soap,  savon  h  la  rose,  is  manufactured  by 
melting  the  ingredients  of  three  parts  of  oil-soap  with  two  parts  of  tallow-soap 
and  sometimes  water ;  the  perfume  is  attar  of  roses,  oil  of  roses,  or  gilliflower 
water,  the  colouring  matter  being  generally  cinnabar.  Shaving-soap  must  not 
contain  free  alkalies.  It  is  sometimes  prepared  by  boiling  fat  acids  with  a 
mixture  of  the  carbonates  of  soda  and  potash.  Lather-soaps  have  in  equal 
volume  only  half  the  substance  of  the  other  soaps.  Palm-  or  olive-oil  soap  is  melted 
with  an  addition  of  one-third  to  one-eightli  the  volume  of  water,  and  tlie  mass  stirred 
imtil  it  has  increased  to  double  the  volume.  It  is  then  placed  in  a  mould.  It 
should  be  remarked  that  the  oil-soaps,  and  not  tallow-soaps,  are  the  true  for- 
matives  of  the  lather-soaps. 

Tnuuparent  Soap.  Ordinary  dry  tallow-soap  is  cut  into  splinters  and  heated 
with  an  equal  weight  of  alcohol,  in  which  the  soap  dissolves.  The  mixture  is 
allowed  to  cool ;  therewith  all  impurities  are  thrown  down,  and  the  clear  fluid  is 
placed  in  the  moulds,  where  it  has  to  remain  three  to  four  weeks  to  harden. 
Tincture  of  cochineal  and  aniline  red  are  employed  for  colouring  transparent 
soaps,  and  also  Martin's  yellow.  The  perfume  is  chiefly  oil  of  dnnamon,  sometLmes 
oil  of  thyme,  oil  of  marjoram,  and  sassi£ras-oil.  Glycerine-soap  is  prepared  from 
an  alcoholic  solution  of  ordinary  soap,  to  which  glycerine  is  added.  Or  5  cwts.  of 
soap  with  an  equal  quantity  of  glycerine  are  heated  by  steam  in  a  copper  vesseL 
The  mixture  is  placed  in  moulds,  and  allowed  to  set  in  the  usual  manner.  A  solution 
of  soap  hi  an  excess  of  glycerine  (35 :  30)  forms  fluid  glycerine-soap,  which  is  of  a 
clear  honey  consistency.    Both  varieties  are  perfumed  with  essential  oils. 

um8  of  Soap.  Soap  is  used  for  cleansing  purposes  in  washing,  in  bleaching  eloth  tnd 
woollen  materials ;  for  the  preparation  of  Uthographic  tints,  <tc.  The  cleansing  proper- 
ties of  soap  are  due  to  the  alkaUes  it  contains.  The  alkali,  although  combined  with  the 
fat  acids,  loses  none  of  these  properties,  which  are  in  fact  included  in  the  combination  of 
the  alkali  with  the  fatty  Babstances  of  the  dirt  to  be  removed.  The  explanation  of  the 
action  chemically,  according  to  Chevreul,  is  the  following : — The  neutral  salts  formed  by 
the  alkalies  and  the  fat  acids,  stearates,  palmitates,  and  oleates  are  decomposed  by  the 
water,  whereby  insoluble  double  fat  add  salts  are  separated,  while  the  alkali  is  set  free. 
By  means  of  the  free  alkaH  the  impurities  clinging  to  the  materials  are  removed,  snd 
ts^en  up  by  the  fat  acid  salts,  the  suspended  dirt  being  thus  contained  in  the  lather. 

so«p  Tasta.  The  greater  the  quantity  of  fat  adds  combined  in  the  soap,  the  higher  is  its 
value.  A  normal  soap,  besides  alkaline  fat  acids,  should  only  contain;  free  water,  the 
quantity  of  which  gives  a  means  of  estimating  the  value  of  the  soap.  It  is  in  the  power 
of  the  soap-maker  to  manufacture  300  parts  of  a  good  hard  soap  out  of  100  parts  of  fat 
When  too  small  a  quantity  of  water  is  contained  the  soap  becomes  too  hard,  and 


SORACIC  ACID.  240 

noflh  labour  ia  lost  in  obtaming  a  lather.  If,  on  the  other  hand,  water  is  held  in  too  large 
a  qaantity  there  is  a  great  loss  of  material.  The  degree  of  hardness  of  the  soap  forms, 
therefore,  another  means  of  estimating  its  yalue.  Many  soaps  contain  2  to  3  per  cent 
glyceiine.  But  the  proportion  of  water  and  the  hardness  of  a  soap  are  not  the  only 
means  of  estimation,  there  still  remains  the  estimation  of  the  nentrekl  fat  acid  alkalies, 
the  free  alkali,  common  salt,  or  unsaponified  fat  in  the  residue  left  after  the  drying  of  the 
soap.  According  to  W.  Stein,  the  presence  of  free  alkali  may  be  ascertained  by  means  of 
oaiomel,  or  according  to  Nasohold,  by  nitrate  of  protoxide  of  meroory.  Uncombined  fat 
retards  the  formation  of  a  lather,  and  after  a  time  imparts  to  the  soap  a  rancid  odour. 
Bat  the  worth  of  a  soap  can  only  be  accurately  ascertained  by  means  of  chemical 
analysiB. 
laMiabie  Soup.  All  soaps  that  havo  not  potash  or  soda  for  a  base  are  insoluble  in  water. 
Many  of  the  insoluble  soaps  are  of  technical  importance. 

C^cium-soap  plays  an  important  part  in  steanne-wax  manufacture.  It  is  made  either 
directly  by  saponifying  fat  with  hydrate  of  lime,  or  by  treating  soluble  soap  with  a  solu- 
tion of  a  salt  of  lime ;  this  soap  is  formed  to  some  extent  when  ordinary  soap  is  dissolved 
in  hard  water.  Barium-  and  strontium-soap  are  similar  to  calcium-soap.  Magnesium- 
soap  is  made  directly  with  difficulty ;  it  may  be  obtained  indirectly  by  dissolving  ordinary 
soap  in  sea-water.  Aluminium-soap  is  without  doubt  an  insoluble  soap ;  argillaceous 
earths  will  not  saponify  fat  unless  aluminate  of  soda  or  potash  is  present.  Aluminium 
Boap  is  used  in  waterproofing.  According  to  Jarry,  wood  impregnated  with  oleate  or 
etearate  of  aluminium  is  impervious  to  moisture.  Lately  many  materials  have  been  ren- 
dered waterproof  by  being  dipped  into  a  solution  of  acetate  of  aluminium,  and  then  into 
a  soap  solution,  aluminium  soap  being  thus  formed. 

Manganese-soap  is  prepared  by  the  addition  of  sulphate  of  manganese  to  ordinary  soap, 
or  by  boiling  carbonate  of  manganese  with  oleic  acid.  It  is  usually  applied  as  a  siccative. 
Zinc-soap  is  prepared  by  the  double  decomposition  of  sulphate  of  zinc  and  soap,  or  by  the 
saponification  of  zinc- white  with  olive-oil  or  fat,  forming  a  yellow-white  mass.  Zinc-soap 
is  used  as  an  oil-colour,  and  also  as  zinc-plaster.  Lead-soap  or  lead-plaster  is  made  by 
adding  white-lead  to  oHve-oil,  or  acetate  of  lead  to  soap  solution.  Tin-soap  is  prepared 
by  the  double  decomposition  of  chloride  of  tin  with  soap.  Copper-soap,  formed  by  the 
addition  of  sulphate  of  copper  solution  to  soap,  is  soluble  in  ether  and  oil,  less  so  in  alcohol ; 
it  is  used  in  preparing  water-colours.  It  may  be  made  by  boiling  oleic  acid  with 
carbonate  of  copper.  Mercury  or  quicksilver-soap  is  prepared  from  chloride  of  mercury 
and  soap ;  it  is  difficult  to  dry ;  is  white,  but  when  exposed  to  air  and  light  turns  grey. 
Mercury-soap  was  formerly  known  as  quicksilver-soap  and  quicksilver-plaster.  Silver, 
gold,  and  platinum-soaps,  are  severally  prepared  by  double  decomposition ;  but  they  are 
not  much  used.  Gold-soap  is  employed  in  gilding  porcelain ;  and  silver-soap  for  dark- 
ening the  hair. 

Boric  ob  Boracic  Acid,  and  Borax. 

Bofacic  acid  occurs  native  as  sassolin,  H3BO3 ;  in  100  parts : — 

Anhydrous  boracic  acid,  B2O3     56*45 

w aiier       *••     .«•     ...     •••     ...     ...     «..     ...       43  5 5 


xoooo 


and  further  in  the  foUowing  minerals : — 

^''^**?ji"Lf^™l,?r:t^*''''™  "^^  \  ^tJ»  62-5  per  cent  Boracic  acid, 
cmonae  01  magnesium    )  **  *^ 

Bhodicite,  or  borate  of  calcium    .. 

Hayescine,  Tiza,  or  borate  of  lime 

Hydroboracite 

Tincal  or  borax,  borate  of  soda 

Datholite)  or  boro-silicate 

Botryolite  ... 

Axinite 

Tourmaline 


...     ... 


•.•     ..• 


...     ...     ...     ••*     .*•     •.• 


...     ...     ...     ...     ...     ... 


...     ...     ...     ...     ... 


•  »» 

30  to  45 

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30  to  44 

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t> 

47 

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t1 

3653 

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if 

18 

f» 

»> 

.  2035 

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2  to  66 

91 

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2  to  II'8 

iy 

2y)  CHEMICAL   TECHNOLOGY. 

Boracic  acid  is  found  also  in  small  quantities  in  many  mineral  waters  and  in  sea- 
water.  Larderellito,  or  borate  of  ammonia,  and  lagonite,  or  borate  of  iron,  are  both 
found  in  very  small  quantities  in  Tuscany,  but  are  interesting  to  mineralogists  only. 

Boracic  acid  is  found  as  sassolin  in  many  volcanic  regions  mixed  with  sulphur, 
and  in  thje  hot  springs  of  Sasso,  in  Tuscany,  and  also  between  Volterra  and  Massa 
Maritima  in  the  clefts  and  rents  of  the  volcanic  formation  of  rock.  Hofier  and 
Mascagni  (1776),  first  mentioned  the  occurrence  of  boracic  acid  in  the  waters  sub- 
jected, in  the  clefts  of  the  rock,  to  the  sulphurous  exhalations.  The  little  pools 
formed  in  these  clefts  are  variously  known  as  fwnmecki^  fumaroles^  ioffiioniy  and 
mofetti.  The  boracic  acid  deposits  in  some  cases  cover  an  extent  of  six  miles. 
Since  18 18  artificial  soffioni  have  been  constructed,  and  the  benefit  derived  by  the 
country  from  the  introduction  of  the  industry  is  immense.  The  first  artificial  lake 
was  situated  near  Monte  Cerboli,  and  the  product  was  ioc  some  time  known  as 
Larderellito,  from  the  owner's  name,  Larderel.  The  production  from  these  works 
nlone  amounted  in  1839  to  717,333  kilos.,  and  in  1867  to  2,350,000  kilos.  The 
increase  has  been  greatest  since  1854,  owing  to  the  energy  with  which  Grazzeri  and 
Durval  entered  upon  the  construction  of  the  artificial  soffioni. 

The  soil  of  the  natural  lakes,  or  beds  of  the  natural  soffioni,  are  of  a  slimy 
formation,  and  have  a  peculiar  seething  movement  due  to  the  escape  of  the 
sulphurous  vapours  from  tlie  fumaroles  or  vents.  According  to  Payen,  this  vapour 
or  steam  may  be  considered  as  condensed  and  as  non-condensed,  the  former  con- 
taining besides  water,  sulphate  of  lime,  sulphate  of  magnesia,  sulphate  of  ammonia, 
ddoride  of  iron,  hydrochloric  acid,  organic  substances,  a  fishy-smelling  oil,  day, 
sand,  and  a  small  quantity  of  boracic  acid.  The  non-condensed  vapour  consisted  of— 

Carbonic  acid    0*5730 

Nitrogen     03480 

Oxygen       0*0657 

Sulphuretted  hydrogen    0*0133 

Payen  is  of  opinion  that  the  vapours  contain  no  boracic  acid,  while  C.  Schmidt 

tliinks  otlicrwise,  as  tlie  vapours,  when  condensed  without  contact  with  the  water 

of  tlie  soffioni,  yield  boracic  acid.    The  condensed  vapours  contain  0*1  per  cent 

boracic  acid. 

Theory  of  the  Formation      Dumas  and  Paveu  fouud  au  explanation  of  the  formation  of 

of  the  ,         .     ,  .  . ,  ,        ,  ,        .        ,  ,  .  . 

Nathre  Bor&do  Add.  volcamc  boracic  acid  upon  the  hypothesis  that  there  exists  m 
the  interior  of  the  volcano  or  beneath  the  under-crust  of  the  earth  a  layer  of  sulphide 
of  boron  (BaS3),  which  under  the  action  of  the  mineral  waters  becomes  converted 
into  boracic  acid  and  sulphuretted  hydrogen.  P.  Bolley  gives  the  action  as  similar 
to  that  occurring  in  the  formation  of  sal-ammoniac,  a  very  common  mineral  in 
volcanic  regions.  Professor  Becchi,  of  Florence,  found  nitride  of  boron  (BN)  in 
one  of  the  imdcr-strata,  from  which  he  prepared  artificiaDy  by  means  of  steam 
ammonia  and  boracic  acid.  Also  Warrington  (1854)  and  Popp  (1870)  attributed  the 
appearance  of  boracic  acid  and  ammonia  in  volcanoes  to  the  decomposition  of  nitride 
of  boron  by  evaporation.  Recently  (1862)  Becchi  has  obtained  boracic  acid  by  the 
decomposition  of  borate  of  calcium  in  a  stream  of  superheated  steam. 

"^BiS^^AdS  °'      T^®  °^ost  general  method  of  obtaining  boracic  acid  is  by  the  evapoia- 
tion  of  the  water  of  the  natural  or  artificial  soffioni.    The  water  is  either  naturally  or 


BORACIC  ACID. 


251 


artificially  introduced  into  the  natursd  fumaroles,  as  these  sometimes  do  not  re- 
supply  themselves  with  sufficient  rapidity.  As  soon  as  the  water  has  absorbed  a 
considerable  quantity  of  the  vapours  it  is  removed  and  placed  in  a  large  mason- 
work  cistern;  this  cistern  is  imbedded  in  the  soil  near  the  fumaroles,  and  the 
natural  heat  is  sufficient  to  cause  evaporation.  The  vapours  are  condensed  in  a 
wooden  chimney.  The  separated  impurities,  gypsum,  &c.,  remain  in  the  cistern.  As 
goon  as  the  solution  is  of  a  sp.  gr.  =  107 — I'oS  at  80°,  it  is  poured  into  leaden 
crystallising  vessels  where  the  boracic  acid  crystallises  out.  The  mother-liquor  is 
evaporated  to  dryness.  It  should  be  remembered  that  the  entire  operation  is  con- 
ducted with  the  assistance  of  the  natural  heat  of  the  fumaroles  only.  Occasionally 
the  boracic  acid  is  only  present  in  the  natural  waters  to  0002  of  a  part ;  and  in 
these  cases  fuel  must  be  used  in  the  evaporation,  which  therefore  entails  the  expense 
of  carriage,  as  fuel  is  very  scarce  near  the  soffioni.  Charcoal  is  generally  used. 
But  by  this  means  an  acid  is  obtained,  containing  about  70  to  80  per  cent  hydrated 
boracic  acid,  with  10  per  cent  impurities.  Clouet  removes  the  impurities  by  treat- 
ment with  5  per  cent  of  ordinary  hydrochloric  acid.  Boracic  acid  for  pharma- 
ceutical purposes  may  be  prepared  by  dissolving  i  part  of  borax  in  4  parts  of 
boiling  water,  and  decomposing  the  solution  with  one-third  part  of  sulphuric,  or 
better  with  half  part  of  hydrochloric  acid  of  1*2  sp.gr.  The  acid  separates  on 
cooling,  and  can  be  purified  by  crystallisation. 
In  100  parts  of  commercial  boracic  acid  from  Tuscany,  H.  Vohl  (1866)  found : — 


!••  •••  ••• 


Boracic  acid 
Water  of  crystallisation ... 
T I tt ler         ...  ^...     •■*     ... 

Sulphuric  acid 

Sihcic  acid        

omiu  a*.      ...     •■*     ...     ... 

Oxide  of  iron 

iVotoxide  of  manganese... 
Alumina 

1  illlH?  ...      ...      ...      ...      ... 

Magnesia 

A  OlttOn  ...         .a.        ...        ... 

Ammonia 

OUUn    ...        ...        ...        ...       ... 

Chloride  of  sodium 

Organic  substances  and  loss 


I. 

2. 

3- 

4- 

5- 

451996 

47  63  20 

48-2357 

452487 

48*1314 

34-8916 

356983 

37-2127 

349010 

38*0610 

45019 

2-5860 

10237 

4-4990 

1*5240 

96135 

7*9096 

8*4423 

95833 

7*8i6i 

08I2I 

1*2840 

06000 

0-2134 

o*o86i 

02991 

05000 

0*1000 

0*7722 

0-4154 

01 266 

0'i63i 

00920 

0*1030 

0-0431 

00031 

traces 

traces 

traces 

traces 

05786 

00802 

00504 

0-I359 

0*1736 

00109 

03055 

0-5178 

traces 

traces 

06080 

traces 

traces 

traces 

traces 

oi8oi 

0-2551 

0-5178 

0*6140 

0-4134 

29891 

3-5165 

35169 

37659 

3*0890 

00029 

traces 

traces 

traces 

traces 

01012 

00595 

00401 

01671 

0*032 1 

0*0918 

OOIOI 

OOIOI 

-^— 

00449 

lOO'OOOO    lOO'OOOO    lOOOOOO    lOOOOOO    lOO'OOOO 


^JiKSSc*5iS"**  Pure  boracic  acid  crystallises  in  mother-of-pearl-like  leaves, 
which  at  loo""  C.  lose  half  their  water  of  crystallisation  without  melting,  the  other 
half  being  driven  off  at  a  red-heat.  After  cooling  the  anhydi*ous  acid  ax>pears  as  a 
hard,  transparent,  brittle  glass  of  183  sp.  gr.  i  part  boracic  acid  dissolves  in  25  6 
parts  water  at  15""  C,  and  in  2*9  parts  at  100°  0.  At  8°  a  saturated  solution  has  a 
Bp.  gr.  of  1*014.    ^^  imparts  a  green  colour  to  the  flame  of  the  spirit-lamp.    In  a 


25a  CHEMICAL  TECHNOLOGY. 

chemical  point  of  view  it  is  similar  to  silicic  acid,  Boracic  acid  is  largely  used  in 
the  preparation  of  borax,  for  glazing  porcelain,  and  mixed  in  a  weak  aqaeons  solu- 
tion witli  sulphuric  acid  in  the  preparation  of  the  wicks  of  stearine  and  paraffin 
candles.  It  is  also  used  for  colouring  gold,  for  decorating  iron  and  steel,  in  the 
preparation  of  flint-glass,  and  artificial  precious  stones.  In  1859  boracic  acid  was 
used  in  the  preparation  of  hydrated  oxide  of  chromium,  known  under  the  name  of 
Pannetier's-green,  Vert-Guigtwt,  &c. 

Bonx.      Borax,  or  bi-borate  of  soda,  when  anhydrous  according  to  the  formula 
Na2B407,  contains  in  100  parts : — 

Anhydrous  boracic  acid  (B2O3)      69*05 

Soda  (Na^O)      30'95 


100:00 

It  is  found  native  in  Alpine  lakes,  on  the  snow-capped  mountains  of  India,  China, 
Persia,  in  Ceylon,  and  Great  Thibet.  It  is  found  in  large  quantity  at  Potosi  in 
Bolivia,  where  the  Borax  LakSj  according  to  Moore's  analysis  (1870)  contains  in  i  litre 
of  its  water  (sp.  gr.  =  1*027),  3*96  grammes  of  borax.  Pyramid  Lake,  Humboldt  Co., 
Nevada,  yields  also  large  quantities.  By  the  heat  of  the  sun  the  water  of  the  borax 
lakes  is  evaporated  and  the  borax  crystallises  out.  and  is  gathered  and  brought  into 
commerce  under  the  name  of  Tincal.  It  appears  in  small  six-sided  crystals,  more  or 
less  smooth.  The  Clear  Lake  in  California,  to  the  north  of  San  Francisco,  yields 
daily  2000  kilos,  of  borax. 

Formerly  tincal  was  purified  by  washing  in  water  containing  soda  to  free  the 
borax  from  adhering  fatty  substances  which  combine  with  the  soda  to  form  an 
almost  insoluble  soap.  After  the  borax  has  been  well  washed  it  is  dissolved  in 
boihng- water ;  for  each  100  parts  of  refined  salts  there  are  12  parts  of  carbonate  of 
soda.  The  solution  is  next  filtered,  and  then  evaporated  to  18°  to  20°  B.  It  is  now 
placed  in  wooden  crystallising  vessels  lined  with  lead,  where  it  is  necessary  to  allow 
the  fluid  to  cool  gradually.  Anotlier  method  is  to  place  the  tincal  in  cold  water,  and 
to  stir  in  i  per  cent  of  caustic  lime.  The  fatty  substances  are  thus  removed,  com- 
bining with  the  lime  to  foi-m  an  insoluble  calcium  soap.  2  per  cent  of  chloride  of 
calcium  is  added  to  the  fluid,  which  is  next  evaporated,  and  set  to  crystallise. 
Clouet  recommends  the  powdering  of  the  tincal,  which  is  next  mixed  with  10  per 
cent  nitrate  of  soda,  and  calcined  in  a  cast-iron  pan,  the  fatty  substances  being  thus 
destroyed.  The  calcined  mass  is  dissolved  in  water,  and  the  solution  evaporated  to 
crystallisation. 

Borax  from  Borade  Add.  In  1818  the  manufacture  of  borax  from  boracic  acid  was  com- 
menced,  and  since  that  time  borax  has  sunk  to  three-fourths  its  former  price.  Both 
according  to  the  proportion  of  water  and  the  crystalline  form,  there  may  be  oonsi- 
dered  two  varieties  of  borax,  i.  The  ordinary  or  prismatic  borax;  2.  Octahedral 
borax.    The  prismatic  borax  (NaaB407+ioH20)  contains  in  100  parts : — 

Boracic  acid        36*6 

outiiw       •••      •••      ••■      ■••      •••      (■•      •••      •«•      •••      102 

Water  of  crystallisation    47*2 

1000 


BORACtC  ACID. 

Tlie  octahedral  borax  (NaaB^Oj+sHjO)  contains  in  lOO  parts  :■ 
Boracic  acid  [ 


6936 
3064 


Prismatio  borax  is  maunfaotored  in  the  following  miuiner:-'Tbere  are  dissolved  iu  a 

I   lead-lined  Tassel  k  Fig  118  26cnts  of  cr^'stalliBed  carbonate  of  xodniu  aboat  1300  litres 

ol  aater,  beated  b^  meaos  of  Btoam    to  the  boilinf;- point.    The  boiler,  c,  it  for  tbe 

pDipoae  only  of  geoeratlng  steam  which  is  passed  b;  the  pipe,  c,  and  tbe  rose,  in,  into  «. 


By  means  of  the  large  taps,  b  and  r,  tbe  fluid  may  be  removed  from  1.  Through  tho 
tabs  a  tbe  snbstanees  thrown  down  from  the  Rolntion  con  be  removed.  Boracio  acid  is 
added  in  qaantities  of  S  to  10  lbs.  after  the  solntion  has  been  heated  to  the  boiling-point. 
Besides  carbonic  acid  a  small  qaanlity  of  carbonate  of  ammonia  is  developed,  and  piMses 
by  o  into  tbe  vessel  q,  containing  dilate  sulphario  acid,  by  which  it  is  absorbed.  To 
Mtnrate  the  solntion  of  26  cwts.  of  eoda.  24  cwts.  of  crude  boracic  add  are  necessary. 
Tbe  boiling  saturated  solution  marks  zi"  to  ix"  B.,  and  has  a  temperature  of  :04°.    If 


354 


ClIF.mCAL  TECIWOLOay. 


the  Bolotion  is  -too  strong.  irateT  in  oddoil;  if  ton  vcnk,  a  amall  qoftnti't;  of  cnjo 
borax,  to  bring  it  to  21°  B,  The  Rolution  is  alloweil  tn  nlnuJ  in  *  until  all  insolnble  «ab- 
Btnnoes  are  deposited.  Tho  cIkbt  ley  is  condaoted  by  munua  of  tbe  tap.  r,  into  the  crvs- 
tallisiug  Teasoia,  p  p,  th^  mud  or  deposit  beiug  received  into  K.  The  eryatailising  vesa^ 
are  of  wood  lined  vitb  lead.  Tho  crystnllinntioD  ia  oomplete  ui  two  to  three  dayi,  and 
the  mother-liqnoT  is  driLwii  off  into  tbo  vessel  a.  The  cry^ttiis  >Lre  placed  to  drain  on  ibe 
inclined  plane,  u.  The  luotber-liqaor  ia  rDtoinod  for  the  dilation  of  a  fresh  qaontit;  i>[ 
Boda.  ^ter  three  or  fonr  oporatioas,  tlie  motber-UqaoT  coataina  Eofficient  Bnlphote  of 
soda  to  admit  of  proGtablo  crystaUiuation  ;  aud  the  ley  is  allowed  to  cool  at  30°.  As  tbe  ^ 
eolnbility  of  auipbate  of  soda  baa  reached  the  maximum  at  a  temperatnre  of  33°,  it  is  clear 
that  the  cryadUllsalion  of  tbo  Balpbate  commoncos  at  the  completion  of  that  of  111* 
borai.  After  the  crj-Btalliaatioii  of  the  aulphntii  of  stnia,  the  motber-linuor  is  evaporated 
to  dryness,  and  tlie  saline  residue  ia  sold  to  tho  glasG-iuanufactnrer. 

Purityim  Urn  Dom.  The  crude  borax  to  be  purified  is  placed  in  a  lond-Unod  wooden 
cistcni,  A.  Fig.  119,  heat«d  by  steam.  The  borax  is  auapendud  in  a  wire  sieve 
ijiiraedia(«ly  under  the  Hurface  of  the  water  with  which  a  is  filled.  To  100  ports 
of  borax,  5   parts   of  crystallised   carbonate  at  soda  are  added,  and   the  liquid 


IB  Btrengthened  horn  time  tb  time  till  it  muba  32°  B.  'When  the  solution  i* 
settled  it  is  removed  by  the  tap  to  the  cooler,  e.  To  prevent  loss  of  ley,  the 
floor  Buder  b  ia  stippled  with  waterproof  cement,  and  sloped  towards  a  ;;ult.'i 
Tho  crystallising  vessel  ie  of  tJiick  timbers,  h  k  h,  lined  stonily  with  lend :  il"* 
vessel  is  filled  with  ley  to  witliin  nn  inch  of  the  edge,  the  cover  l>ciii<;  then  pliiceil  on- 
Tha  steam  condenses  on  tho  cover,  which  when  removed  is  found  covered  wiih 
small  cryetalB,  the  larger  crystals  falling  to  the  bottom  of  tlic  veisel.  To  hasten  Uj0 
cooling,  spaces  are  left  in  timbers,  e ;  but  the  crystallisation  is  not  effected  aodiT 
16  to  z8  days.  After  this  time  the  ley  still  has  a  temperature  of  27°  to  28°  C,  Viben 
quite  cool  the  foreign  substances  separate  from  tho  borax.  The  vessel,  b,  contains 
tlie  large  borax  crystals  from  which  tbe  adhering  mollier-liqnor  is  Eepnnilcd  by  i 
PiHinge.  If  tlie  crystals  are  not  thus  carefully  treated,  they  split  into  thin  leaves; 
for  this  reason  also  the  cooling  should  bo  gradual.  The  crystals  are  dried  on 
n  wooden  tabic,  linolly  sorted,  and  packed.' 

In  England  borax  is  prepared  from  horacio  acid  in  the  following  manner: — The 
crude  borocic  acid  is  mixed  with  half  its  woiglit  of  calcined  soda  and  sulmiill"! 
to  the  action  of  heat  in  a  muffle-oven.  The  animoiiin,  wliich  as  sulphato  i^-  nn 
iuiporlant  constituent  of  crude  boracic  acid,  is,  with  carlxinic  acid,  given  off  darin;! 
tlio  process,  and  passes  through  a  tube  to  a  condensing  ehnnibcr.  The  melted  mass 
is  removed,  and  lixivi&tcd  in  an  iron  pan ;  tlie  suspended  matter  is  allowed  to  sctit. 


BORACIC  ACID.  255 

Bhd  the  clear  liqnor  is  pot  into  smaller  vessels  to  cool,  in  wliich  beautiful  cr}'stal9 
form.  It  has  already  been  mentioned  that  this  manufacture  had  its  origin  in 
France,  where  sulphuric  vapours  were  employed.  A  mixture  of  calcined  Glauber 
salts  and  boracic  acid  were  placed  in  a  retort  and  subjected  to  distillation,  the 
residue  on  lixiviation  and  crystallisation  yielding  borax.  Kohuke  substitutes 
caustic  soda  for  the  carbonate  of  soda,  tlie  borax  ciystallising  from  a  very  alkaline 
solution. 

Becantly  borax  has  been  obtained  from  native  borate  of  oalcinm)  tiza  or  borocalcitc, 
(formula,  according  to  Wohler,  Na2B407  +  2GaB407+i8HaO),  which  occurs  in  large  quau- 
iitids  at  Tarapaoa  in  Fora,  and  in  Western  Africa.  Treatment  with  sulphuric  acid  gives 
only  onsatisfaotory  results,  and  hydrochloric  acid  is  therefore  employed.  The  acid 
is  poured  upon  the  mineral  to  two'thirds  of  its  weight  with  twice  the  quantity  of  water, 
and  the  whole  heated  to  the  boiling-point,  and  allowed  to  digest.  The  heat  must  be  maiu- 
talned  to  the  completion  of  the  digestion,  and  the  water  lost  by  evaporation  re-supplied. 
Tho  clear  hquor  is  then  decanted,  and  on  cooling  the  boracic  acid  cryatallises  out, 
the  mother-liquor  retaining  chloride  of  sodium,  chloride  of  calcium,  with  a  slight  excesH 
of  hydrochloric  acid.  Stassfurt  boracite  or  Stassfurtite,  is  also  becoming  largely  used  in 
the  preparation  of  borax. 

The  prismatic  borax  is  colourless  and  forms  transparent  crystals  of  175  sp.  gr., 
dissolved  in  12  parts  cold  and  2  parts  boiling  water,  the  solution  having  a  weak  alkaline 
reaction  upon  test-paper,  although  borax  is  an  acid  salt.  By  exposure  to  the  air  it  loses 
water.  At  a  moderate  heat  it  separates  into  a  spongy  mass  known  as  calcined  borax,  and 
at  a  red-heat  assumes  a  glassy  appearance ;  in  this  condition  it  is  used  as  a  blowpipe 
fiox. 

Octahedral  Borax.      Octahedral  borax  (NaaB40^+5HaO),  is 'prepared  in  the  following 

manner: — Prismatic  borax  is  dissolved  in  boiling  water  till  tlie  solution  marks 

30*'  B.=  i'26o  sp.  gr*    This  solution  is  then  allowed  to  cool  very  slowly.    When  tlie 

temperature  has  fallen  to  79°  C,  the  octahedral  crystals  begin  to  form,  the  formation 

continuing  tiU  the  temperature  reaches  56°.    After  tliis  the  motlier-ley  yields  only 

prismatic  crystals.     Unless  great  care  be  taken,  a  mixed  crystallisation  results. 

13nran  recommends  the  preparation  of  octahedral  borax  by  evaporating  a  borax 

Bolntion  to  32^B.=i"282  sp.  gr.,  when  it  is  removed  to  a  crystallising  vessel.   Wlien 

10  cwts.  of  borax  are  operated  upon,  the  process  will  take  six  days  to  complete.   The 

prismatic  and  octahedral  salt  crystallises  in  distinct  layers  tliat  can  be  separated 

mechanically.     Indian  borax  and  Chinese  half-rciined  borax  sometimes  contain 

octahedral    crystals.      Octaliedral    borax    is    kno\\'n  in  French  commerce  under 

the  names  of  calcined  borax,  jeweller's  borax,  surface  borax,  &c.    It  is  distinguished 

from  prismatic  borax  by  its.  crystalline  form  and  the  proportion  of  water  contained, 

by  its  sp.  gr,=i-8i,  and  its  greater  hardness.    While  tlie  prismatic  borax  remains 

nnafiected  in  transparency  by  exposure  to  air,  the  octahedral  borax  rapidly  becomes 

opaque,  and  absorbing  five  equivalents  of  water  is  converted  into  the  prismatic  salt. 

VMS  of  Bonx.  The  uses  of  borax  are  very  numerous.  Molten  borax  has  the  property,  at 
high  temperatures,  of  fluxing  metallic  oxides,  vitrifying  with  them  into  coloured  trauRua- 
rent  glasses ;  for  instance,  with  protoxide  of  cobalt  a  blue  glass  is  formed,  and  with  oxide 
of  chromium  a  green  glass.  This  property  is  of  great  utility  in  chemical  analysis,  as  the 
various  metallio  oxides  may  be  thus  distinguished  in  the  blowpipe  flame.  It  is  also  used 
for  soldering  metals;  and  is  a  constituent  of  Strass^  used  in  glass-manufacture  and 
enamelling.  It  is  used  extensively  in  glazing  the  finer  kinds  of  earthenware,  and  for 
separating  metals  from  their  ores.  Borax  forms  xvith  shellac  in  proportion  of  i  part  to 
5  parts  a  peculiar  varnish,  soluble  in  water,  and  used  when  mixed  with  aniline  black 
to  stiffen  felt  hats.  With  casein  it  gives  a  fluid  resembling  a  solution  of  gum-arabic,  for 
which  it  is  often  substituted.  Borax  is  made  into  a  soap  for  washing  purposes,  into 
a  solution  for  cleansing  the  hair,  and  it  is  also  used  in  various  cosmetics,  &c.  It  is 
largely  employed  to  fix  mineral  mordants.  According  to  Clouet,  a  mixture  of  boracic 
acid  and  nitrate  of  potash  or  soda  is  in  many  cases  a  better  flux  than  borax.  He  recom- 
mends 100  parts  boracic  acid  and  100  parts  of  the  nitrate  to  be  placed  in  an  enamelled 


256  *  CHEMICAL  TECHNOLOGY. 

iron  kettle  with  zo  per  eent  water  and  heated  till  fluid.  "When  cooled,  flat  white  <n78tais 
are  formed ;  those  made  with  nitrate  of  potash  ean  be  used  for  crystal-glass  manafactnrey 
and  those  with  nitrate  of  soda  for  enamelling.  Borate  of  ehromiom  is  known  in  com- 
merce as  Vert-GiUgnet  or  Pannetier's  green. 
DUimond-Boron.  or  Wohler  and  H.  Deville  in  1857  ^^^^  ^^  ^^  ^  notice  that  boron 
Adamantiae.  forms  similarly  to  carbon  in  two  allotropic  conditions,  namely  crystalline  • 
and  amorphous.  Diamond  boron  is  prepared  in  two  ways,  either  by  the  redaction  of 
calcined  borax  with  aluminium  :— 


Boracic  acid,  B2O3, )    yi^^A^    ( Alumina,  A1203, 
Aluminium,  2A,      J    ^  ( Boron,  2B  ; 


or  by  convertingamorphous  boron  into  crystalline.  The  latter  method  gives  the  better  results 
zoo  grms.  of  anhydrous  boracic  acid  are  mixed  with  60  grms.  of  sodium  in  a  sanall  iron 
crucible  heated  to  a  red-heat.  To  this  mixture  40  to  50  grms.  of  common  salt  are  added, 
and  the  crucible  is  luted  down.  As  soon  as  the  reaction  is  finished,  the  mass,  consisting 
of  amorphous  boron  with  boracic  acid,  borax,  and  common  salt  intermingled,  is  stirred 
into  water  acidified  with  hydrochloric  acid.  The  boron  is  filtered  out,  washed  with  a 
weak  solution  of  hydrochloric  acid,  and  placed  upon  a  porous  stone  to  dry  at  the  ordinary 
temperature.  Molten  iron,  it  is  well  known,  converts  amorphous  carbon  into  crystalline 
graphitic  carbon,  and  aluminium  exercises  a  similar  action  upon  boron.  The  erystalline 
boron  is  prepared  in  the  following  manner : — ^A  small  crucible  is  filled  with  amorphoas 
boron,  in  the  centre  of  which  a  small  bar  of  aluzninium  weighing  4  to  6  grms.  is  placed. 
The  crucible  is  submitted  to  a  temperature  sufficient  to  melt  nickel  for  zi  to  2  hours. 
After  cooling  the  aluminium  will  be  found  covered  with  beautiful  crystals  of  boron.  The 
diamond  boron  is  easily  separated  from  the  graphitoid.  The  former  is  a  transparent 
tetragonal  crystal,  of  a  garnet-red  or  honey-yeflow  colour,  or,  if  perfectly  pure,  colourless. 
It  is  very  brittle,  hard,  and  lustrous ;  it  will  scratch  rubies  easily.  This  discovery  may 
in  time  be  of  great  technical  importance. 

Pboddction  cfF  Alum,  Sulphates  of  Alumina,  and  AiuMrNATEs. 

Aimn.  Alum  is  a  saline  substance,  consisting  of  sulphate  of  alumina,  sulphate 
of  potash  or  ammoziia,  and  water  of  crystallisation.  It  occurs  native  as  potash- 
alum  and  as  ammonia-alum,  being,  in  fact,  a  double  salt,  consisting  of  either  snlphate 
of  alumina  and  snlphate  of  potash,  or  sulphate  of  alumina  and  sulphate  of  ammonia. 

The  alum  known  as  potash-alum,  ^^  \  4SO4-I-24H2O,  is  found  in  alum-shale.  But 

all  natural  alums  are  of  more  mineralogical  than  technical  interest,  the  alums  of 

commerce  being  always  artificially  prepared.    We  shall,  therefore,  pass  on  to  the 

consideration  of  Uie  latter. 

"^SSSiirtwe""*      T^®  manufacture  of  alum  grounds  itself  on  the  formation  of  sulphate 

of  alumina  and  aluminate  of  soda  from  the  various  alum-ores.     These  ores  or 

earths  necessitating  different  methods  of  treatment,  may  be   divided  into  four 

groups,  viz ; — 

z.  Those  which  contain  alumina,  potassa,  and  sulphuric  acid  in  such  proportions  that 
the  addition  of  an  alkaline  salt  is  not  requisite.  To  this  group  belongs  alum-stone,  and 
several  varieties  of  alum-shale. 

2.  Those  in  which  the  sulphate  of  alumina  is  alone  present,  necessitating  the  addition 
of  alkali  salts  in  large  quantities.  To  this  group  belong  the  alum-shale  and  alum-earthB 
found  in  the  brown-coal  formation, 

3.  Those  in  which  alumina  only  is  contained,  and  to  which  both  sulphuric  acid  and 
alkali  salts  must  be  added.  To  this  group  belozig — «.  Clay ;  j3.  Cryolite ;  7.  Bauxite ; 
S.  Befuse  slack. 

4.  To  the  fourth  group  belong  those  materials,  such  as  felspar,  contaizdng  alnmins 
an4  potash  in  sufiicient  quantity,  but  needing  the  addition  of  sulphuric  acid. 


•  Graphitic  boron  is  by  a  later  discovery  of  Wohler's  (1867)  resolved  into  boracic 
aluminium ;  formula,  AIB^p 


ALUM.  257 

'toSS^SoHlt^T  ^'*«  Group. — ^Alum-stone  or  alimite  occurs  only  in  volcanic 
regions,  and  is  the  product  of  the  action  of  the  sulphurous  vapours  upon  sub- 
stances rich  in  felspar.  It  is  found  at  Tolfia,  near  Civita-Vecchia,  and  in  large 
quantities  at  Muszag,  in  Hungary.  The  crystallised  alum-stone  consists  of  sulphates 
of  potash  and  alumina  with  hydroxide  of  aluminium,  according  to  Al.  Mitscherlich — 

K,S04+Ala(S04)3-f2(Ala03,3H«0). 

Alnm-stone  loses  its  water  at  a  red-heat,  the  product  of  the  calcination  being  influenced 
by  water,  while  unbornt  s^om-stone  is  not.  At  a  strong  red-heat  the  sulphate  of  alumina 
Beparates  into  alumina,  sulphurous  acid,  and  oxygen,  and  the  sulphate  of  potash  is  also 
decomposed.  The  mineral  is  calcined  in  lime-kilns  in  the  ordinary  manner.  The  calcined 
alnm-stone  is  lixiviated  with  boiling  water,  the  supernatant  liquor  decanted,  and  the 
alom  crystaUised  out.  Boman,  rook,  or  roche  alum  is  prepared  in  a  similar  manner,  the 
red  oolour  being  due  to  peroxide  of  iron. 

PnpMBtionaf  Ainmtrom      2nd  Oroup. — This  modc  of  preparation  yields  the  greatest 

•adAinm-Mrtiu.       amouut  of  alum  with  as  much  facility  as  from  alum-stone. 


Alum-shale  or  schist  is  a  sulphurous  iron  pyrites,  found  under  beds  of 
clay  in  Upper  Bavaria,  in  Prussia,  near  Diisseldorf,  Saxony,  Bohemia,  Belgium,  &c. 
Only  very  inferior  kinds  require  an  addition  of  alkali  salts. 

Aiaaxartiia.  Alum-earth  is  more  or  less  a  mixture  of  sulphurous  iron  pyrites  with 
various  bituminous  matters.  The  sulphur  is  present  partly  in  free  state,  partly  as 
iron  and  vitriol  pyrites;    the  iron  is  present  partly  as  sulphuret,  partly  as  iron 

hnmate. 

pvtpMmUoaof  Alum.      The  preparation  of  the  alum  may  be  considered  in  the  following 

six  operations : — 

aoMUagtiMAiiiin-iiuth.  I.  The  roasting  of  the  alum  earths  is  the  easiest  of  the  opera- 
tions. The  greater  part  of  the  alum  manufactured  is  produced  by  precipitating 
nlphate  of  alumina  with  a  solution  of  alkali  salts.  It  is  not  always  necessary  the  schist 
should  be  burnt  to  concentrate  the  sulphate  of  alumina,  a  lengthy  weathering  being 
sufficient.  The  action  may  be  explained  as  follows  : — By  the  weathering  the  bisulphide 
of  iron  absorbs  oxygen,  to  form  sulphate  of  iron,  which  separates  into  protoxide  of  iron 
and  sulphuric  acid,  the  latter  acting  upon  the  alumina  forming  an  equivalent  quantity  of 
sulphate  of  alumina.  Or  by  roasting,  the  bisulphide  is  decomposed  to  monosulphide 
and  sulphur,  which,  with  the  sulphur  of  the  alum-earth,  gives  rise  to  sulphurous  acid, 
and  this  acting  upon  the  alumina  produces  sulphite  of  alumina  and  also'the  sulphate.  The 
roasting  or  mJcination,  however,  should  not  take  place  with  earths  that  have  been 
snbjeeted  to  less  than  a  year's  weathering,  as  there  is  found  to  be  in  practice  a  loss  of 
one-sixth  of  the  sulphate  of  alumina. 

UxMatioa.  2.  The  Uxiviatiou  of  the  calcined  alum  earths  is  efiFected  in  a  lixiviation 
eistem  in  which  the  earth  is  placed.  These  tanks  stand  in  rows  of  Ave,  the  best  arrange- 
ment being  to  build  them  on  a  slope  near  the  calcination  heaps.  Each  vessel  has  a 
length  of  6  to  7  metres,  is  5  metres  broad,  and  about  1*3  metres  in  height.  They  are 
three-parts  filled  with  the  burnt  earth,  and  completely  with  water ;  the  lixivium  flows 
from  the  highest  tank  to  the  lowest.    If  the  ley  is  not  of  i'i6  sp.  gr.  fresh  shale  is  added. 

STtponuon  of  Um  Ler.  3  •  The  concentration  of  the  raw  ley  by  evaporation  is  accomplished  in 
leaden  pans.  These,  however,  deteriorate,  crack,  are  easily  melted,  and  their  place  is  now 
generally  supplied  by  cisterns  of  masonry.  But  most  to  be  preferred  is  Bleibtreu's 
method  of  heating  with  gas,  introduced  in  the  alum-works  on  the  banks  of  the  Bhine. 
The  treatment  of  the  raw  ley  while  being  concentrated  depends  upon  its  condition  and 
upon  the  sulphate  of  iron  it  contains.  As  sulphate  of  iron  is  commonly  present  in  large 
quantities  in  the  raw  ley  or  Uquor,  many  of  the  German  alum-works  are  also  vitriol-workR. 
^en,  however,  the  quantity  of  sulphate  of  iron  is  too  small  to  admit  of  being  advantage- 
ously treated  for  the  preparation  of  sulphate  of  iron,  the  Uquor  is  at  once  evaporated 
until  it  has  attained  a  sp.  gr.  of  1*40.  During  the  ebullition  basic  sulphate  of  iron  is 
deposited,  the  liquor  becomes  of  yellow-red  colour,  assumes  a  somewhat  slimy  condi- 
tion, and  has  to  be  rendered  clear  before  alum  is  obtained  from  it.  This  clearing  is 
effected  by  pouring  the  liquor  into  large  wooden  water-tight  tanks ;  the  liquor  having 
deposited,  the  suspended  matter  is  tapped  or  syphoned  oft  from  the  sediment,  and  trans- 
ferred to  the  precipitation  tanks. 


258  CHEMICAL   TECHNOLOGY. 

Ahiin-Fionr.  4.  The  precipitation  of  floor  of  alum  is  effected  in  case  it  is  desired  to 
make  potash-alum  by  the  addition  to  the  liqnor  of  a  potash  salt,  or  of  an  ammonia  salt 
if  it  is  desired  to  make  ammonia-alnm.  The  solution  of  the  alkaline  salt  is  called  the 
precipitant ;  by  the  combination  of  the  sulphate  of  alumina  contained  in  the  liquor  with 
the  precipitant  alum  is  formed,  and  deposited  as  a  solid  salt,  care  being  taken  to  preyent 
the  formation  of  large  crystals  by  keeping  the  liquid  stirred.  By  this  means  the  alum^  is 
deposited  as  a  crystalline  powder  or  so-caJled  flour  of  alum,  which  by  being  washed  with 
cold  water  can  be  freed  from  any  adhering  mother-liquor.  The  precipitation  was  formerly 
effected  by  the  addition  of  wood-ash  ley  or  lant ;  at  the  present  day  chloride  of  potassium 
obtained  either  from  kelp,  camallite,  or  beet-root  molasses,  and  sulphate  of  potassa 
derived  from  the  decomposition  of  kainite,  are  employed  for  this  purpose.  Chloride  of 
potassium  is  useful  only  when  the  solution  contains  large  quantities  of  ^sulphate  of  iron, 
which  being  converted  into  chloride  of  iron  forms  sulphate  of  potassa.  *  Potash  can  only 
be  used  when  the  ley  contains  enough  free  sulphuric  acid  to  combine  with  the  salt,  for 
otherwise  a  portion  of  the  sulphate  of  alumina  would  become  precipitated  as  insoluble 
alumina.  The  ammonia  salt  made  use  of  is  generally  sulphate  of  ammonia ;  100  parts  of 
sulphate  of  alumina  require  for  precipitation — 

Chloride  of  potassium       . .     . .     , .     . .    43*5  parts, 

Sulphate  of  potassa 50*9     „ 

Sulphate  of  ammonia        47*8     „ 

The  liquor  coTering  the  alum-flour  is  somewhat  of  a  green  colour,  and  contains  little 
alum,  but  chiefly  proto-perchloride  of  iron,  sulphates  of  iron,  sulphate  of  magnesia,  or 
chloride  of  magnesiimi,  dependent  upon  whether  the  precipitation  was  effected  by 
sulphates  or  by  chlorides.  This  liquor  is  used  for  m^ng  impure  alum,  sulphate  of  iron, 
or  is  employed  in  the  preparation  of  sulphate  of  ammonia. 

washinir  and  5-    The  floury  alum  is  generally  waphed  in  the  hydro-extractor  or 

Re^ryBUiiiaaUon.  centrifugal  machine  and  the  liquor  obtained  again  used  for  preparing 
alum.  The  washed  floury  alum  is  (6)  converted  into  large  crystals  by  re-crystallisation, 
the  alum  at  the  same  time  being  pnrifled.  For  this  purpose  the  alum  flour  is  dissolved  in 
40  per  cent  of  its  weight  of  boiling  water,  the  operation  being  carried  on  in  wooden  lead- 
tined  tanks.  The  hot  solution  is  run  into  crystallising  vessels,  where  the  crystallisation 
is  finished  according  to  the  temperature  of  the  air  in  eight  to  ten  days.  From  this  operation 
hardly  any  mother-Uquor  remains,  the  vessel  being  almost  entirely  filled  with  alum  crystals. 

^'^'SJS^SS.^""      3r<l  Group. — ^The  manufacture  of  alum  and  of  sulphate  of  alumina 

from  such  materials  as  contain  only  almuina,  to  which  consequently  sulphuric  add 

and  alkaline  salts  have  to  be  added,  has  come  largely  into  practice  in  England.   The 

materials  employed  are : — a.  Claj ;  /3.  Cryolite ;  y.  Bauxite ;  1^.  Blast-furnace  slag. 

a.  Preparation  of  Alum  from  Clay, — The  clay  to  be  employed  for  this  purpose  should 
be  as  free  as  possible  from  carbonates  of  lime  and  iron.  It  is  first  gently  heated  in 
contact  with  air,  partly  with  the  view  of  dehydratation,  partly  for  the  purpose  of  converting 
any  iron  into  oxide,  -and  lastly  to  render  the  clay  more  readily  soluble  in  acids.  By 
dehydratation  the  clay  becomes  porous  and  fit  to  take  up  sulphuric  acid  by  capil- 
larity. The  gently  ignited  and  powdered  clay  is  gradually  piit  into  sulphuric  acid  of  50*"  B. 
(=  1*52  sp.  gr.)  contained  in  a  leaden  pan,  and  heated  nearly  to  the  boiling-point.  The 
mass  effervesces  and  becomes  thick,  and  is  next  transferred  to  iron  tanks,  where  it 
solidifies.  It  is  afterwards  lixiviated  with  water,  or  better,  with  the  liquor  obtained  by 
washing  the  alum-flour.  The  lixivium  having  become  clear  by  standing  is  syphoned  off 
from  the  sediment,  and  boiled  with  a  Fufllcient  quantity  of  bisulphate  of  potash  or 
sulphate  of  ammonia  from  gas -liquor.  The  hot  solution  is  transferred  to  a  shallow 
leaden  pan,  and  kept  stirred  for  the  purpose  of  converting  the  alum  on  solidifying  into 
flour.  The  flour  is  washed,  dried,  and  is  then  converted  into  large  crystals  as  dei^cribed 
above.  The  product  known  in  the  trade  as  alum-cake  is  the  result  of  the  action  of 
sulphuric  acid  upon  clay ;  it  is  met  with  in  a  pulverised  state,  is  used  more  eBi>ecially 
ill  the  manufacture  of  inferior  kinds  of  paper,  and  contains  from  13  to  17  per  cent  of 
;ilumina. 

'^'Iromci^ou^I""  ^-  Since  the  year  1857  ^^^"^  *"^^  sulphate  of  alumina  have  been 
l>reparcd  along  Tvitli  soda,  from  the  mineral  known  as  cryolite  or  Greenland  spar, 
AlaFlfi-f  6NaFl,  and  consisting  in  100  parts  of — 

Fluorine 54*5 

Aluminitun • 13*0 

OOvUlUll...        ...        ...        ...        •..        •«■        •••         ■«•        3      J 


ALVM,  259 

The  following  are  fhe  methods  employed  for  this  purpose  :-^ 

a.  DecompoHtion  of  Cryolite  by  Ignition  with  Carbonate  of  Lime  according  to  Thomsen^s 
Method. — I  moleoTile  of  cryolite  is  ignited  with  6  molecules  of  carbonate  of  lime,  carbonic 
add  escapes,  and  soluble  lUununate  of  soda  and  insoluble  fluoride  of  calcium  are  formed 
(Al3Fl6,6KaFl)+6CaC03»Ala03,3Na30+6CaFl+6G02.  From  the  ignited  mass  the 
aluminate  of  soda  is  obtained  by  liziviation  with  water,  and  into  the  solution  carbonic 
acid  gas  is  passed.  The  result  is  the  precipitation  of  hydrated  gelatinous  alumina 
and  carbonate  of  soda,  which  remains  in  solution.  If  it  be  desired  to  obtain  the  alumina 
as  an  earthy  compact  precipitate,  bicarbonate  of  soda  is  used  as  a  precipitant  instead  of 
carbonic  acid.  While  the  clear  liquor  is  boiled  down  for  the  purpose  of  obtaining 
carbonate  of  soda,  the  precipitated  alumina  is  dissolved  in  dUute  sulphuric  acid ;  this 
■elation  is  eyaporated  for  the  purpose  of  obtaining  sulphate  of  alumina  (so-called  concen- 
trated alum),  or  the  solution  setter  having  been  treated  with  a  potassa  or  ammonia  salt  is 
oonverted  into  alum.  100  lbs.  of  cryolite  yield  33  lbs.  of  alumina,  which  require  go  lbs.  of 
sulphuric  acid  to  yield  a  neutral  solution ;  100  lbs.  of  oryoUte  will  therefore  yield  305  lbs. 
of  alum,  and  may  give  in  addition  : — 

Calcined  soda 75*0  lbs.,  or 

Crystallised  carbonate  of  soda     . .     . .  203*0  „     or 

Caustic  soda 44*0  ,,     or 

Bicarbonate  of  soda       ii9'5   t« 

6.  Deeomponticn  of  Cryolite  mtk  Caustic  Lime  by  the  Wet  Way  (Sauenoein^s  Method), — 
Very  fin^y  ground  cryolite  is  boiled  with  water  and  lime,  the  purer  the  better,  and  as  free 
from  iron  as  possible,  in  a  leaden  pan.  The  result  is  the  formation  of  a  solution  of 
almoinate  of  soda  and  insoluble  fluoride  of  calcium, 

(AlaFl6,6NaFl)  +  6CaO = Ala03,3NaaO  +  eCaFla. 
When  the  fluoride  of  calcium  has  been  deposited,  the  clear  liquid  is  decanted,  and  the 
sediment  washed,  the  first  wash-water  being  added  to  the  decanted  liquor,  and  the  second 
and  third  wash-waters  being  used  instead  of  pure  water  at  a  subsequent  operation.  In 
order  to  separate  the  alumina  from  the  solution  of  aluminate  of  soda,  there  is  added  to  the 
liquid  while  being  continuously  stirred,  very  finely  pulverised  cryolite  in  excess,  the  result 
of  the  decomposition  being  exhibited  by  the  following  formula : — 

(Ala03,3KaaO)  +  (AlaFl6,6NaFl)  =  2AI2O5 + i2NaFl. 
^en  no  more  caustic  soda  can  be  detected  in  the  liqmd — a  small  quantity  of  which 
shoold,  after  filtration,  yield,  upon  the  addition  of  a  solution  of  sal-ammoniac  and  appli- 
cation of  heat,  a  precipitate  of  alumina — it  is  left  to  stand  for  the  purpose  of  becoming 
dear.  The  clarified  solution  of  fluoride  of  sodium  is  then  drawn  off,  and  the  alumina 
treated  as  above  described.  The  solution  of  fluoride  of  sodium  having  been  boiled  with 
caustic  lime  yields  a  caustic  soda  solution  which,  having  been  decantedfromthe  sediment  of 
fluoride  of  calcium,  is  evaporated  to  dryness.  Recently  the  fluoride  of  calcium  obtained 
as  a  by-prodact  of  the  cryolite  industry  is  used  in  glass-making. 

c.  The  decomposition  of  cryolite  by  sulphuric  acid  yields  sulphate  of  soda,  convertible 
into  carbonate  by  Leblanc's  process,  and  sulphate  of  alumina  free  (^om  iron.  238  parts 
of  cryolite  require  for  decomposition  240  parts  of  anhydrous  or  321  parts  of  ordinary  sul- 
phuric acid.  The  resulting  compounds  are  sulphate  of  alumina,  sulphate  of  soda,  and 
hydrofluoric  acid : — 


AlaFle.eNaFl, 
6H2SO4, 


(Ala(S0.)3. 
yield  -  3Na2S04. 
1 12HFI. 

This  method  of  decomposing  cryolite  is,  however,  by  no  means  to  be  recommended,  as 
owing  to  the  liberation  of  hydrofluoric  acid,  peculiarly  constructed  apparatus  are  required ; 
while  the  sulphate  of  soda  has  to  be  converted  into  carbonate  of  soda.  Persoz  suggests 
that  cryolite  should  be  treated  in  platinum  vessels  with  three  times  its  weight  of  strong 
sulphuric  acid,  to  be  recovered  with  the  hydrofluoric  acid  by  distillation.  The  solid 
residue  should  be  treated  with  cold  water  in  order  to  dissolve  the  larger  part  of  the 
bisulphate  of  soda  contained  in  the  saline  mass,  from  which  the  anhydrous  sulphate 
of  alumina  is  extracted  with  boiling  water,  and  converted  by  the  addition  of  sulphate  of 
potassa  or  ammonia  into  alum  free  horn.  iron.  The  solution  of  bisulphate  of  soda  having 
been  evaporated  to  drj^ess,  is  employed  for  the  preparation  of  fuming  sulphuric  acid, 
Glauber's  salt  remaining  as  a  residue. 

^**SS?BJu^tJ^°™  t'  ^^  some  parts  of  Southern  France,  in  Calabria,  near  Belfast,  Ire- 
land, and  other  parts  of  Europe,  a  mineral  occurs  consisting  essentially  (60  per  cent) 
of  hydrated  alumina  of  greater  or  less  purity,  termed  bauxite,  from  the  fact  of 
having  been  first  found  in  tlie  commune  of  Baux,  in  France.    In  order  to  prepare 

8  2    - 


26o  CHEMICAL  TECHNOLOGY. 

alum  and  sulphate  of  alumina  from  this  mineral  it  is  first  disintegrated  hj 
being  ignited  with  carbonate  of  soda,  or  with  a  mixture  of  sulphate  of  soda  and 
charcoal ;  in  each  instance  the  lixivdation  of  the  ignited  mass  yields  aluminate  of 
soda,  from  wliich,  by  processes  already  described  imder  Cryolite,  alum,  or  sulphate  of 
alumina,  and  soda  are  prepared. 

£rS^ll!IIt-FamaiJ"sSig.  ^'  "^ '  Lurmaun  recommends  that  the  slag  be  decomposed  by 
means  of  hydrochloric  acid.  From  the  resulting  solution  of  chloride  of 
aluminium  the  alumina  is  precipitated  by  carbonate  of  lime,  any  dissolved 
silica  being  precipitated  at  the  same  time.  The  alumina  is  dissolved  in  sulphuric 
acid,  leaving  the  silica.  loo  kilos,  of  slag  containing  25  per  cent  of  alumina 
yield  180  Hlos.  of  alum  and  31  kilos,  of  silica. 

Aimn  from  Felspar.  ^th  Group. — The  manufacture  of  alum  from  minerals,  (for  instance, 
felspar)  containing  alumina  and  potassa,  is  not  of  any  industrial  importance: 
we  therefore  refer  the  reader  to  what  has  been  said  (see  page  122)  on  the  Prepara- 
tion of  Potassa  Salts  from  Felspar. 

proptttieB  of  Alum.      Potash-alum,  "^  I  4SO4+  a4HaO,  or  KaS04+ Al^  (804)3+ 24HaO, 

consists  in  100  parts  of : — 

Potassa       ...     • •• 9*95 

Alumina      10*83 

Sulphuric  acid 33'7i 

\f  ater..*     •••     •••     •••     ...     ...     •••  45  5^ 

100*00 

crystallises  readily  in  regular  octahedra,  loses  at  60°  18  mols.  of  water,  and  fuses  at 
92°  in  its  water  of  crystallisation,  yielding  a  colourless  fluid  which  retains  its  state  of 
aggregation  for  some  time  after  cooling  before  solidifying  into  a  crystalline  mass.  At 
a  temperature  a  little  below  red  heat  alum  loses  all  its  water,  becoming  converted 
into  burnt-alum,  alumen  ustum,  a  white,  porous,,  readily  friable  mass.  Wlien 
ignited  with  carbonaceous  matter,  air  being  excluded,  potash-alum  forms  a  pyro- 
phoric  compound : — 

loo  parts  of  water  at    0°    dissolve    39  parts  of  potash -alum. 
»»  i>  20  ft         15  ^  »»  »' 

„  100''  „  3600  „  „ 

The  Bolution  of  almu  in  water  (the  salt  is  insolublo  in  alcohol)  has  an  astringent  swert 
taBte,  and  possesses  an  acid  reaction  so  strong  that  when  alum  is  heated  with  common 
Bait  hydrochloric  acid  is  evolved ;  while  a  concentrated  solution  of  alum  deBtroys  the  bloe 
colour  of  many — not  of  all — artificial  ultramarines. . 

AmmoniaAinm.       This  salt,   r^^^\  4S04-»-24H20,  or  (NH4)2S04+ Ala(S04)3+24HO,oon. 
sists  in  zoo  parts  of : — 

Ammonia       S'Sg 

Alumina ..  11*90 

Sulphuric  add       35*io 

Water      48*11 

100*00 

Ammonia-alum  is  now  far  more  extensively  manufactured  than  potash-alum.  ^Vlien 
ammonia-alum  is  strongly  heated,  sulphate  of  ammonia,  water,  and  sulphuric  acid  are 
driven  off,  and  alumina  remains. 


ALVM.  261 

100  parts  of  water  at  o^  dissolve  5*22  parts  of  ammoma-alafQ. 
If  »  20^       „      13-6(5  „  „ 

»»  »»  4®        f»      27*27  „  ,, 

„  „  ICO**       „    421-90  „  „ 

soJaAium.      The  formula  of  this  salt  is — 

j^}  4S04+24HaO,  or  NaaS04+Ala(S04)3+24HaO, 
containing  in  100  parts : — 

fti^v' u&       •••       ••«       •••       •••       •«•       •••         u  o 

Alumina       11*2 

Sulphuric  acid    34*9 

w auei^  •■•  ••■  •••  •■■  ••>  ••>  47 

lOO'O 

It  is  as  readily  prepared  from  sulphate  of  alumina  and  sulphate  of  soda  as  the  alums 
already  mentioned,  but  its  solubility  prevents  tlio  sf])aration  from  the  mother-liquor, 
while  its  solution  when  boiled  loses  the  property  of  crvstallising.  As  iron  cannot  be 
removed  from  this  salt  by  re-crystallisation,  the  materials  it  is  obtained  from  should  be  free 
from  that  metal.  The  solutions  should  be  mixed  cold,  and  gently  evaporated  at  a 
temperature  not  exceeding  60''. 

Neutral  or  cubical  alum  (K2S04+Al203,2S03)  is  obtained  either  by  adding  to  an  alum 
solution  so  much  carbonate  of  potassa  or  soda  as  will  begin  to  separate  the  alumina,  or  a 
solution  of  alum  is  treated  with  gelatinous  alumina.  By  boiling  12  parts  of  alum  and  i  part 
of  slaked  lime  in  water,  the  same  salt  is  obtained.  This  neutral  salt  is  often  preferred 
in  dyeing  and  calico  printing,  as  it  does  not  affeet  certain  colours.  When  ammonia-alum 
is  similarly  treated,  it  also  yields  a  neutral  alum.  Blesser  (a)  and  Schmidt  {b)  found  the 
following  to  be  the  composition  of  cubical  alum  in  100  parts : — 

a.  h. 

Sulphuric  acid 34*52  33*95 

Alumina      iz'86  11*48 

Potassa       9*44  9*^4 

Water 45*27  45*6i 

101*09  100*08 

Al  ) 
Insoluble,  or  basic  alum,    -^  \  2SO4,    is  obtained  by  boUing  a  solution  of  ^um  with 

hydrate  of  alumina ;  it  is  a  white,  iuBoluble  powder,  and  as  regards  its  composition 
■imilftr  to  alum-stouc.    Basic  alum  is  soluble  in  acetic  acid. 

SKiphflte  of  Aiamiiw.       The    activB    principle    of   alum   is    evidently  the  sulphate  of 

alnmina,  not  the  sulphates  of  potassa  and  ammonia,  the  object  ef  the  preparation  of 

the  doable  salt  being  simply  the  obtaining  of  a  defmite  compound,  wliich,  while  it 

readily  crystallises,  can  be  obtained  in  a  pure  state,  especially  free  from  iron,  a  very 

injnrioas  ingredient  in  alum  used  in  dyeing  and  calico-printing.     However,  at  the 

present  day,  with  improved  methods  of  manufacture,  sulphate  of  alumina  is  largely 

prepared,  and  of  excellent  quality.    It  is  often  sold  under  the  name  of  concentrated 

alum ;  and  occurs  in  the  trade  as  square  cakes.    It  is  white,  somewhat  transparent, 

and  may  be  cut  with  a  knife;  is  readily  soluble  in  water,  contains  always  free 

Bulphuric  acid,  and  also  to  some  extent  potassa-  and  soda-alum. 

In  the  pure  state  this  salt  has  the  formula,  Al^ (804)3+181120,  and  contains  in  100 

part»~alumina,   1878;    sulphuric  acid,  38-27;    water,  4295;   total,   100.      That 

the  composition  of  this  salt  as  met  with  in  commerce  varies  gi-eatly  may  be  inferred 

from  the  following  results  of  Varrcntrapp's  analyses  of  different  samples  of  this 

Bait: — 

I.  2.  3.               4- 

Alumina 15*3  12*5  15*1  130 

Sulphuric  add       ...    380  30*6  380  340 


262  CHEMICAL  TECHN0L007. 

According  to  the  formula,  the  quantity  of  sulphuric  acid  in  these  samples  should 
have  been — 

I.  2.  3.  4. 

358  29-2  433  305 

The  quantity  of  water  even  varies  between  56  and  48  per  cent  for  different 
parts  of  the  same  cake.  Weygand  found  a  sample  of  this  salt  prepared  at  Schwemaal 
to  contain — alumina,  15*57 ;  sulphuric  acid,  38' 13  ;  o^de  of  iron,  1*15 ;  potassa^ 
0*62;  water,  4579  parts.  The  sulphate  of  alumina  prepared  from  cryolite  at 
Harburg  contains  about  5  per  cent  of  sulphate  of  soda.  The  results  obtained  in 
the  analyses  by  H.  Fleck  of  various  samples  of  sulphate  of  alumina  are: — 

Sulphate  of  alumina     47'35  ^o'So  5^*63 

Sulphate  of  soda    4*35  1*24  077 

Free  sulphuric  acid      073  0*27  — 

Water      4737  47*47  4^*94 

^ii^^_i_^__A  ^^^^___^_  ^_^^__^^.a 

99-80  9978  9934 

Sulphate  of  alumina  is  prepared  either  from  clay,  cryolite,  or  bauxite  by  methods 
already  described.  When  clay  is  employed,  the  iron  has  to  be  removed  from  the  dilute 
solution  of  the  sulphate  of  alumina  by  precipitation  as  Berlin  blue  by  means  of  ferro- 
cyanide  of  potassium.  When  cryolite  is  used,  the  alumina,  separated  from  the  eoluticm 
of  alnminate  of  soda  by  carbonic  acid,  or  powdered  cryolite,  is  put  into  sulphuric  acid, 
contained  in  a  wooden  lead-lined  tank,  and  heated  to  80°  to  90°,  the  addition  of  the  alumina 
to  the  acid  being  continued  until  solution  ceases  to  take  place.  The  solution  having  been 
clarified  by  standing  for  some  time  is  next  evaporated  in  a  copper  vessel  until  the  salt 
fuses ;  it  is  then  oast  into  moulds.  With  due  care  sulphate  of  idumina  may  be  used  in 
dyeing  and  calico-printing,  but  it  cannot  be  altogether  substituted  for  alum,  owing  to  its 
variable  composition. 

Aiami&atfl  of  Soda.  Aluminatc  of  soda  is  now  prepared  on  the  large  scale,  as  it  has 
been  found  to  be  a  useful  form  of  soluble  alumina,  especially  in  dyeing  and  calico- 
printing.  The  preparation  of  this  compound  is  based  upon  the  solubUily  of  hy- 
drate of  alumina  in  caustic  potassa  or  soda-ley,  and  the  ready  decomposition  of 
the  solution  by  carbonic  and  acetic  acids,  bicarbonate  and  acetate  of  soda,  sal- 
ammoniac,  &c. 

Aluminate  of  soda  was  first  brought  under  the  notice  of  dyers  by  Macqner  and 
Haussmiann  in  18 19,  but  owing  to  the  preparation  being  too  expensive  it  did  not  come 
into  industrial  application  until  comparatively  recently.  We  have  already  described 
the  mode  of  manufacturing  aluminate  of  soda  from  cryolite ;  but  in  Germany — the 
chief  seat  of  cryolite  industry — ^this  salt  is  not  made  on  the  large  scale;  in  France 
it  is  manufactured  by  Merle  and  Ck>.,  at  Alais,  and  in  Elngland  at  the  Washington 
Chemical  Works.  In  France  bauxite,  containing  60  to  75  per  cent  of  alumina,  and 
from  12  to  20  per  cent  of  oxide  of  iron,  is  the  raw  material,  and  is  treated  with 
caustic  or  carbonate  of  soda.  If  caustic  soda  is  used  the  pulverised  mineral  is 
boiled  with  a  solution  of  the  alkali ;  while  if  the  carbonate  is  employed  the  mixture 
is  ignited  in  a  reverberatory  furnace.  In  either  case  aluminate  of  soda  is  produced, 
dissolved — ^in  the  case  of  ignition  the  semi-fused  mass  is  lixiviated  with  water-^nd 
evaporated  to  dr3mess.  The  salt  met  with  in  commerce  is  a  white  powder  with  a 
green-yellow  hue,  dry  to  the  touch,  and  consisting  of— 

Alumina    •••     •••     •••    •••     •••     •••    •••    4^ 

ooua  •••     .••     •••     ••■     •••     •••     •••     ■.•    44 

Chloride  of  sodium  and  Glauber's  salt...      8 

100 


ALUM.  263 

The  formula,  -^  I  Oe  would  require : — 

Alumina     5279 

Soda 47*21 

lOOOO 

Alnmlnate  of  soda  is  equally  soluble  in  cold  and  hot  water.  Exposed  to  air  it  absorbs 
moisture  and  carbonic  acid,  and  consequently  on  being  dissolved  in  water  the  salt  so 
changed  yields  a  turbid  solution,  owing  to  alumina  being  suspended.  The  aqueous  solution 
of  this  salt  is  not  stronger  than  10°  to  12°  B.,  —  1*07  to  1*09  sp.  gr.  According  to  Le 
Chatellier,  Deyille,  and  Jacquemart,  sulphate  of  alumina  is  the  starting-point  of  the 
preparation  of  the  aluminate  of  soda  by  precipitating  from  the  sulphate  ihe  alumina, 
and  re-dissolving  the  latter  in  caustic  soda  ley.  Aluminate  of  soda  is  used  in  dyeing 
and  calico-printiag ;  further,  for  the  preparation  of  lake  colours,  induration  of  stone, 
and  the  manufacture  of  artificial  stone,  and  for  the  saponification  of  fats  in  stearine 
candle  manufacture,  an  alumina  soap  being  first  formed,  which  is  decomposed  by 
acetic  acid  into  acetate  of  alumina  and  free  fatty  acid.  Aluminate  of  soda  is  largely 
used  in  the  preparation  of  an  opaque,  milky-looking  glass,  or  semi-porcelain.  Aluminate  of 
Boda  is  a  by-product  of  BsJard's  method  of  soda  manufacture  from  bauxite,  Glauber's 
salt,  and  coal ;  this  by-product,  or  rather  product  of  the  second  stage  of  the  process,  is 
decomposed  by  carbonic  acid  into  carl)onate  of  soda  and  alumina,  which  is  thrown  down. 
The  Pennsylvania  Salt  Manufacturing  Company  at  Natrona,  near  Pittsburg,  manafacture 
large  quantities  of  aluminate  of  soda,  which  is  used  in  soap-boiling  under  the  name  of 
natrona  refined  saponijier, 

c«Mof  Aimnando*  Owing  to  the  great  affinity  of  the  alumina  contained  in  alum  for 
Sulphate  oi  AiamiiM.  textile  fibres,  especially  wool  and  cotton,  alum  is  largely  used  as  a 
mordant  in  dyeing,  except  when  the  tar  colours  are  employed.  Again,  owing  to  the 
affinity  of  alumina  for  many  pigments,  alum  is  employed  in  the  preparation  of  the  lake 
colours,  combinations  of  active  colouring  principles  with  alumina.  It  is  also  used  in  the 
melting  of  tallow ;  for  hardening  gypsum ;  is  found  in  the  preparation  used  for  sizing 
hand-made  paper,  the  alum  in  this  case  forming  with  the  glue  or  size  an  insoluble  com- 
pomid.  Alum  with  resin  is  employed  for  the  same  purpose  in  machine-made  paper,  an 
almnina-pinate  being  formed.  It  is  very  largely  used  for  the  preparation  of  acetate  of 
alomina,  and  with  common  salt  in  the  tawing  of  leather.  Alum  is  employed  in  clarifying 
turbid  fluids,  more  especially  water ;  in  this  case  the  alum  takes  up  the  alumina  suspended 
in  the  water,  and  forming  an  insoluble  (basic)  alum  carries  down  organic  and  other 
niBpended  impurities.  A  boiling  solution  of  alum,  common  salt,  and  nitrate  of  potassa 
is  used  by  jeweUers  for  the  purpose  of  colouring  gold,  that  is  to  say,  to  produce  a  film  of 
pare  gold  on  the  alloy,  the  copper  of  which  is  dissolved  by  the  boiling  solution. 

Aeaute  of  AimnJaa.  This  Salt  is  prepared  by  double  decomposition  ;  generally  sulphate  of 
alumina  and  acetate  of  lead  are  used,  and  occasionally  the  acetates  of  baryta  and  lime. 
The  liquor,  separated  by  filtration  from  sulphate  of  lead,  is  gently  evaporated  to  dryness  ; 
the  dry  salt  is  gelatinous,  and  does  not  crystallise,  is  very  hygroscopic,  and  possesses  a 
strongly  astringent  taste.  When  a  solution  of  acetate  of  alumina  is  evaporated  in  con- 
tact with  air,  acetic  acid  is  driven  off,  and  a  basic  acetate,  insoluble  in  water,  formed. 
Commercially  pure  acetate  of  alumina  is  rarely  used,  as  the  so-called  red-liquor,  mordant 
fouget  consists  of  a  milture  of  alum,  acetate  of  potassa,  and  sulphate  of  potassa.  When 
it  is  desired  to  prepare  neutral  acetate  of  alumina  from  alum,  to  100  parts  of  acetate  of 
lead  62*6  parts  of  alum  are  required  for  complete  mutual  decomposition ;  but  it  is  more 
advantageous  to  convert  a  solution  of  alum  into  insoluble  alumina  by  means  of 
carbonate  of  soda,  and  to  treat  with  acetic  acid.  Acetate  of  alumina  is  not  an  ordinary 
article  of  commerce,  as  the  salt  is  usually  prepared  by  the  consumers.  Besides  being 
largely  used  in  dyeing  and  calico-printing,  acetate  of  alumina  is  employed  for  water- 
proofing woollen  fabrics.  Among  the  salts  of  alumina  employed  industrially  are — hypo- 
tnlplute  of  alumina,  suggested  by  E.  Eopp  as  a  mordant  for  cotton ;  hypochlorite  of 
alnmina,  known  as  Wilson's  bleaching-liquor,  and  used  in  bleaching-works ;  sulphite  of 
alumina,  for  the  purpose  of  purifying  beet-root  juice ;  oxalate  of  alumina,  suggested  by 
I^t  and  Brown  for  the  preservation  of  stone,  marble,  dolomite,  Ac. 


264  CHEMICAL  TECHN0L007. 

Ultramabine. 

xTttnmaxine.  Under  this  name  is  now  understood  an  artificial  blue  pigment, 
formerly  and  still  obtained  in  small  quantities  from  the  lapis  lazuli.  The  qnantitr 
of  artificial  ultramaiine  manufactured  in  Europe  amounts  to  i8o»cxx>  cwta.  annually. 
Lapis  lazuli  is  a  scarce  mineral,  possessing  a  beautiful  blue  colour.  The  sp.  gr. 
varies  from  275  to  2*95.  The  coarser  pieces  of  this  mineral  are  pulverised,  heated 
to  redness,  and  immediately  dipped  into  water,  then  very  finely  ground,  and  the 

NaiiTB  uitmuaiine.  powder  treated  with  dilute  acetic  acid  to  eliminate  carbonate  of 
lime.  The  powder  is  next  well  incorporated  with  a  mixture  of  equal  parts  of  resin, 
wax,  linseed-oil,  and  Burgundy -pitch ;  this  paste  is  kneaded  under  water  until  no 
more  blue  pigment  remains  suspended.  The  quantity  of  ultramarine  obtained 
amounts  to  2  to  3  per  cent.  This  natural  ultramarine  is  liighly  prized  for  ita  extreme 
beauty,  softness  of  colour,  and  durability,  not  being  affected  by  light,  oil,  and  lime. 
Chemical  analysis  of  the  lapis  lazuli  first  gave  the  clue  to  the  true  composition  ai 
this  material,  and  led,  after  many  unsuccessful  attempts,  to  the  preparation  of  artificial 
ultramarine,  not,  however,  by  any  means  equal  to  the  native  pigment,  although  it 
has  driven  smalt  and  other  blue  pigments  nearly  out  of  the  market.  Lapis  lazuli 
consists  in  100  parts  of — silica,  45*40 »  alumiua,  31*67;  soda,  9*09;  sulphuric  add, 
589;  sulphur,  095;  lime,  3*52;  iron,  086;  chlorine,  0*42;  and  water,  01 2. 

Artifidiiiuitnmwine.  Gmelin  first  made  artificial  ultramarine  on  a  very  small  scale  in 
1822 ;  but  not  before  1828  was  ultramarine  industriaUy  obtained  by  Guimet,  at 
Lyons.  In  Germany  the  first  manufactories  of  ultramarine  were  established  at 
WermelsMrchen,  in  1836,  by  Dr.  Leverkuss,  and  at  Nuremberg,  in  1838,  by  MM. 
Zeltner  and  Leykauf :  the  manufacture  of  artificial  ultramarine  in  England  is  of 
very  recent  date,  and  is  still  on  a  very  limited  scale.  France  and  Germany  are  the 
countries  where  this  industiy  is  most  developed.  Of  late  years  the  process  of 
manufacture  has  been  improved  by  R.  Hofimann,  the  manager  of  a  factory  at 
Marienberg,  in  Hessen;  Wilkins,  at  KaiBerslautem ;  Fiirstenau,  at  Coburg;  and 
Gentele,  at  Stockholm. 

Bawibteriaiii.  Thesc  are — I.  Silicate  of  alumina  as  free  as  possible  from  iron,  a 
good  china  clay,  the  kaolin  of  Cornwall  being  esteemed  the  best;  2.  Calcined  sul- 
phate of  soda;  3.  Calcined  soda;  4.  Sulphuret  of  sodium,  as  a  by-product  of  the 
manufacture  ;  5.  Sulphur ;  6.  Pulverised  charcoal,  or  pit-coal. 

Porcelain,  or  china-clay,  is  generally  used,  or  a  white  clay,  the  composition  of 
which  is  nearly  the  same.  Small  quantities  of  lime  and  magnesia  have  no  injurious 
effect,  but  the  oxide  of  iron  should  not  exceed  i  per  cent.  The  composition  of  the 
clay  should  approach  as  nearly  as  possible  to  the  formula  SiaPjAla ;  the  silica  may 
be  combined  or  partly  free.  The  clay  is  washed  with  water  and  treated  in  the  same 
manner  as  for  the  making  of  porcelain ;  it  is  next  dried,  ignited,  and  ground  to  a 
very  fine  powder.  The  sulphate  of  soda  should  not  contain  any  free  acid,  lead,  or 
iron.  If  the  sulphate  does  not  possess  the  requisite  qualities  it  is  dissolved  in 
water,  milk  of  lime  being  added  to  neutralise  the  acid  and  to  precipitate  oxide  of 
iron.  The  clear  solution  is  left  to  crystallise ;  and  the  crystals  are  ignited  in  ft 
reverberatory  furnace  and  then  pulverised  by  millwork.  The  clear  solution  is  in 
some  cases  evaporated  to  dryness  and  ignited  in  iron  vessels.  Barium,  but  not 
potassium  salts,  form  ultramarine  (see  "  Chemical  News,"  vol.  xxiii.,pp.  119, 142.204). 
The  calcined  soda  is  obtained  from  the  alkali  works,  and  should  contain  at  least  90  per 


VLTRAMARINM.  265 

• 

cent  of  carbonate  of  soda ;  it  is  also  finely  pulverised.  Very  recently  canstic  soda 
has  been  snbstitated  in  some  ultramarine  works.  Sulphuret  of  sodium  (NsaS)  is 
Qfinally  a  by-product  of  the  process  of  making  ultramarine,  and  is  obtained  either 
in  solution  or  as  a  dry  powder.  The  sulphur  is  used  very  finely  pulverised.  The 
carbonaceous  matter  employed  is  also  in  a  very  fine  powder.  Its  use  was  introduced 
by  Leykauf  for  the  purpose  of  deoxidation.  In  order  to  have  the  carbon  in  as 
finely  divided  state  as  possible  it  is  ground  to  a  pulp  with  water  under  granite  stones ; 
the  pulp  is  lixiviated,  and  the  fine  powder  obtained  dried  and  passed  through  a  sieve : 
in  some  cases  resin  $nd  pitch  is  employed.  For  those  ultramarines  not  to  have  their 
colour  discharged  by  alum,  pure  silica,  either  as  fine  glass,  sand,  or  pulverised 
quartz  is  used.  Several  substances  are  used  to  reduce  the  depth  of  colour  of 
ultramarine,  viz. — ^gypsum,  sulphate  of  baryta,  baryta-white,  and  flour ;  the  last  is 
employed  in  making  up  washing-blue. 

Mairafactan  oQUttnuiuriM.      The  mcthods  of  ultramariuo  preparation  may  be  classified, 
according  to  the  crude  materials  employed,  as  the  three  following : — 

a.  Preparation  of  Sulphate,  or  Glauber's  salt  ultramarine. 
/3.  „  „     Soda-ultramarine. 

7.  „  „     Silica-ultramarine. 

a.  Preparation  of  SuXphate-  Ultramarine. — This  ultramarine  is  prepared  according 
to  the  Nuremburg  process  from  kaolin,  sulphate  of  soda,  and  charcoal ;  the  pre^ 
paiation  consisting  in  two  distinct  stages,  viz : — 

a.  Preparation  of  green  ultramarine. 

h.  Conversion  of  green  into  blue  ultramarine. 

a.  Preparation  of  Green  Ultramarine. — ^In  order  to  obtain  a  most  intimate  mixture  of 
the  dry  and  finely  pulverised  materials,  small  quantities  are  weighed  off,  mixed  in 
wooden  troughs  by  means  of  shovels,  and  several  times  passed  through  sieves.  If  solutions 
of  Glauber's  salt,  soda,  and  sulphide  of  sodium  are  used  instead  of  powders,  the  kaolin  is 
mixed  with  these  solutions,  and  the  whole  evaporated  to  dryness,  gently  ignited  in  a 
reverberatory  furnace,  and  then  pulverised  and  sifted.  The  quantities  of  the  crude 
materials  vary,  but  the  following  conditions  have  to  be  complied  with :  — i.  Soda,  whether 
sulphate  or  caustic,  must  be  present  in  such  quantity  that  it  can  saturate  half  of  the 
silica  of  the  clay  (kaolin).  2.  There  must  be  sufficient  soda  remaining  to  form  with  the 
sulphur  a  certain  quantity  of  polysulphuret  of  sodium.  3.  There  ought  to  remain 
enough  sulphur  and  sodium  to  form  another  sodium  sulphuret  (NazS),  i^ter  deducting 
from  the  whole  mixture  as  much  green  ultramarine  as,  according  to  its  composition  as 
proved  by  recent  analysis,  the  silica  and  alumina  present  are  capable  of  forming.  The 
following  figures  will  give  an  idea  of  the  proportions : — 

I.  n. 

Kaolin  (dried) too  100 

Calcined  Glauber's  salt . .  83 — 1 00  41 

Calcined  soda —  41 

Carbon  (char-  or  pit-coal)           17  17 

Sulphur —  13 

For  TOO  parts  of  calcined  soda  80  parts  of  calcined  Glauber's  salt,  and  for  100  parts  of 
the  latter  69  of  dry  sulphuret  of  sodium  are  taken. 

It  is  usual  to  have  a  large  quantity  of  this  mixture  prepared  for  use.  If  this  mixture  is 
ignited  without  access  of  air,  a  white  mass  is  obtained,  which,  having  been  treated  with 
water,  is  a  light,  somewhat  flocculent,  white  substance,  to  which  Bitter  has  given  the 
name  of  white  ultramarine.  It  becomes  green  by  exposure  to  air,  and  blue  by  being 
calcined  in  contact  with  air.  The  mixture  is  well  rammed  into  fire-clay  crucibles,  placed 
in  furnaces  similar  in  construction  to  Ihose  used  for  burning  porcelain,  being  raised  and 
maintained  at  a  high  temperature  with  a  very  limited  supply  of  air.  liiis  operation  lasts 
seven  to  ten  hours,  and  is  completed  at  a  bright  white  heat.  The  furnace  is  closed  and 
slowly  cooled ;  on  removing  the  crucibles,  the  contents  appear  as  a  semi-fused  grey-  or 
yellow-green  mass,  which  is   repeatedly   treated  with  water.    The  ultramarine  thus 


266  CHEMICAL  TECHNOLOGY. 

obtamed  is  in  porons  lumps,  which  are  pnlyerised  to  an  impalpable  powder ;  this  is 
washed,  dried,  and  again  ground,  then  sifted,  and  finally  packed  in  boxes  or  casks,  and 
sent  iQto  the  market  as  green  ultramarine,  consisting,  according  to  Stolzel*a  analysis 
{1855),  in  100  parts,  of — 

AlT7-minft 30*11 

Iron 0*49  (peroxide  of  iron,  07) 

Calcium 0*45 

Sodium 19*09  (soda,  25*73) 

Silica      37*46 

Sulphuric  add      0*76 

Sulphur 6'o8 

Chlorine 0*37 

Magnesia,  potassa,  phosphoric  acid  « .  traces 

94-81. 
Oxygen 5*ig 

100*00 

Green  ultramarine  is  a  pigment  of  comparatiyely  inferior  value,  owing  to  its  being  less 
brilliant  than  the  green  copper  pigments. 

5.  Conversion  of  Oreen  into  Blue  Ultramarine. — This  operation  may  be  variously  effected, 
generally  by  roastiug  the  green  ultramarine  and  sulphur  at  a  low  temperature  with  access 
of  air,  BO  as  to  form  sulphurous  acid,  while  a  portion  of  the  sodium',  is'oxidised  into 
soluble  sulphate  and  afterwards  washed  out ;  but  the  sulphur  originally  present  in  the 
green  ultramarine  remains  combined  with  a  smaller  quantity  of  sodium.  The  roasting 
may  be  variously  carried  out,  but  very  frequently  the  apparatus  consists  of  a  fixed  iron 
cylinder  similar  to  a  gas-retort,  provided  with  a  stirring  apparatus,  by  means  of  wbich 
the  mixture  of  green  ultramarine  and  sulphur  (25  to  30  lbs.  of  the  former  to  ilb.  of 
sulphur)  is  submitted  equally  to  the  source  of  heat.  The  addition  of  sulphur  is 
repeated  until  the  desired  blue  colour  is  produced ;  but  in  some  works  this  calcination  is 
interrupted  by  repeated  Hxiviation,  the  object  being  to  produce  a  superior  article. 
Muifle-ovens  and  a  kind  of  reverberatoiy  oven  are  also  used  for  this  operation.  The 
sulphurous  acid,  which  is  evolved  in  large  quantities,  is  now  generally  employed  in 
making  sulphuric  acid,  sometimes  a  co-product  of  ultramarine  manufacture,  and  used 
for  the  preparation  of  the  sulphate  of  soda  required.  The  ultramarine,  when  quite  blue, 
is  pulverised,  lixiviated,  dried,  and  finally  separated  into  various  qualities  known  in 
the  trade  as  No.  oo,  i,  2,  3,  <!ko. 

'"^SSlrinel!*^  P'  -^  manufactured  in  France,  Belgium,  and  some  parts  of 
(Germany,  this  ultramarine  is  either  pure  soda-ultramarine  or  a  mixture  of  soda-  and 
sulphate-ultramarine.    The  materials  and  proportions  are — 

I.  n.         m. 

Kaolin       100  100  100 

ouipnaii6   •••     •••     •••     •••     •••     •••  ^^  4^  "" 

oocLa  •••     •••     •••     •••     ■••     •••     •••  100  4^  9^ 

Carbon  (charcoal  or  pit-coal) 12  17  6 

Sulphur    60  13  100 

JLM)Sin*«a    •••    •••    ••■    •••    •••    •••      "^  ^'-~  O 

The  ignition  takes  place  either  in  crucibles,  or,  better,  in  a  reverberatoiy  furnace; 
the  result  is  the  formation  of  a  brittle  and  porous  green  substance,  which  absorbs 
oxygen  very  rapidly,  so  that  daring  the  cooling  of  the  mass  in  the  oven,  the  greater 
part  is  converted  into  blue  ultramarine.  The  complete  conversion,  after  the  addition 
of  sulphur,  is  obtained  by  heating  in  a  large  muffle  to  redness,  the  product  being 
distinguished  from  the  foregoing  by  a  greater  depth  and  beauty  of  colour.  By 
increasing,  within  certain  limits,  the  quantities  of  soda  and  sulphur,  the  formation 
of  blue  ultramarine  may  be  at  once  obtained,  the  product  containing  10  to  x 2  per 
etnt  of  sulphur. 


ULTRAMARINE.  267 

**'»g;^2jJ["P*'  .  SiHea-nltxamarine  is  really  soda-ultramarine  in  the  prepara- 
tion of  which  silioa  to  the  amount  of  5  to  10  per  cent  of  the  weight  of  the  kaolin  is 
added.  The  calcination  at  once  yields  blue  ultramarine,  and  further  treatment  with 
sulphur  is  therefore  unnecessary. 

This  ultramarine  is  not  acted  upon  by  a  solution  of  alum,  and  may  be  recognised 
by  its  peculiar  red  hue,  the  intensity  of  which  is  increased  by  an  increase  of  siHca. 
Notwithstanding  the  superiority  of  the  ultramarine  obtained  by  this  process,  its  pre- 
paration is  disadvantageous  owing  to  the  tendency  of  the  mixture  of  crude  materials 
to  fuse  during  ignition. 

ooBitttiitkaof  nttnmuiiM.      Since  1758  the  chemical  constitution  of  ultramarine  has 

been  the  object  of  a  series  of  researches.    The  latest  experiments  are  those  of 

W.  Stein,  who  comes  to  the  condusion  that  ultramarine  consists  chiefly  of  a  white 

mass,  with  which  black  sulphide  of  aluminium  is  most  intimately  and  molecularly 

incorporated,  the  blue  colour  being  due,  not  to  chemical  composition,  but  to  the 

optical  Telation  of  its  component  substance.    Green  ultramarine  contains  less  soda 

than  the  blue  pigment,  and  that  again  less  than  the  white  (so-called)  ultramarine. 

The'  quantity  of  sulphur  contained  in  blue  ultramarine  is  less  than  that  in  green. 

Propetties  of  xntnauuiiM.  Artificial  ultramarine  is  an  impalpable  powder  of  a  fine  blue 
eolonr,  entirely  insoluble  in  water,  and  when  washed  with  distilled  water  leaving  no 
residue  on  evaporation  of  the  filtrate.  It  is  not  acted  upon  by  alkalies,  but  is  highly 
sensitive  to  the  action  of  even  very  dilate  acids  and  acid  salts,  sulphuretted  hydrogen  being 
evolved  and  the  eolonr  discharged.  Native  ultramarine  obtained  from  lapU  lazuli  is  not 
thus  decomposed  by  weak  acid  solution.  There  sometimes  accidentally  occurs  in  soda 
furnaces  a  more  or  less  blue  ultramarine  which  exhibits  the  same  resistance  to  adds.  That 
kind  of  ultramarine  commercially  termed  add  proof  is  manufactured  with  the  addition 
of  silica,  as  described,  but  it  really  only.resists  the  action  of  alum-salts.  Ultramarine  is 
now  largely  used  for  the  purposes  to  which  smalt,  litmus,  and  Berlin-blue  were  applied ; 
that  is  to  say,  ultramarine  is  employed  as  a  paint,  as  a  pigment  in  stereochromy,  for 
paper-hangings,  calico-printing  with  albumen  as  fixing  material,  for  colouring  printing- 
ink,  for  the  bluing  of  Imen  and  cotton  fabrics,  paper,  stearine,  and  paraffine-candles  and 
lump-sugar.  For  1000  owts.  of  sugar  2}  lbs.  of  the  pigment  are  employed,  a  quantity  so 
small  as  to  be  perfectly  innocuous ;  furUier,  ultramarine  does  not  contain  anyuiing  inju- 
rious to  health.  Green  ultramarine  is  a  dTill-coloared  powder  used  by  waU-paper 
stainers,  and  is  sometimes  mixed  with  indigo-carmine  and  a  yellow  pigment  to  improve 
the  colour. 

Adulterations  of  ultramarine  with  Berlin-blue,  smalt,  and  other  blue  pigments  do  not 
now  occur,  as  ultramarine  is  a  cheaper  material ;  but  to  obtain  lighter  iants  ultramarine 
is  sometimes  mixed  with  chalk,  kaolin,  alabaster,  and  chiefly  with  sulphate  of  baryta. 


DIVISION  m. 

TECHROLOOY  OF  GLASS,  CERAMIC  WARE,  GYPSUM,   LIME,   AND  MOBTAS. 


Glass  Manufacture. 
Definition  tad  G«B«ni  Glass  is  EH  amorphoiis  composition  of  yarious  sOicates  obtained 

PropfltUOT  ox  OlMB.  *■  *  ^ 

by  a  process  of  siaelting,  alkaline  and  caldQm  silicates  being  the  chief  constituents. 
That  which  is  termed  water-glass — ^vi;8.,  a  silicate  of  potassa  or  soda — of  course  con' 
tains  no  other  silicates ;  but  real  glass  contains  other  bases  in  addition  to  soda 
and  potassa,  either  alkaline  earths,  as  lime,  baryta,  strontia,  or  other  more  or  less 
basic  bodies,  as  magnesia,  alimiina,  or  metallic  oxides, — ^those  of  lead,  bismuth,  zinc, 
thallium,  protoxides  of  iron  and  manganese,  while  in  the  case  of  optical  or  fine 
crystal  glass  boracic  acid  or  borax  is  substituted  for  a  portion  of  the  silica. 

Glass  is  generally  transparent ;  when  opaque  it  is  either  white  or  coloured.  Glass 
is  not  acted  upon,  in  the  common  acceptance  of  the  term,  by  either  water,  acids,  or 
alkalies.  It  is,  as  has  been  said,  amorphous,  for  as  soon  as  it  becomes  crystalline  it 
ceases  to  be  glass.  The  amorphism  of  glass  is  due  to  its  composition ;  simple  sili- 
cates have  a  tendency  to  crystallise,  and  are  hence  unfit  for  glass  manufacture. 
Owing  to  its  amorphism  glass  exhibits  a  conchoidal  fracture.  When  blown  to  reiy 
thin  laminsB  or  drawn  into  thread,  glass  possesses  a  remarkable  degree  of  elasticity. 
As  regards  the  chemical  and  physical  qualities  of  glass,  much  depends  upon  the 
constituent  silicates;  the  alkaline  silicates  render  glass  soft  and  contribute  to 
its  ready  fusibility.  Silicate  of  potassa  glass  is  less  bright  and  glossy  than  glass 
in  which  silicate  of  soda  prevails,  but  the  latter  silicate  imparts  a  blue-green  coloor. 
Silicate  of  calcium  renders  glass  harder,  brighter,  but  less  readily  fosible.  Silicates  of 
lead  and  bismuth  render  glass  very  fusible,  impart  to  it  a  high  degree  of  lustre,  and 
greatiy  increase  the  re^rangibility ;  they  are  therefore  used  in  making  glass  for 
optical  purposes.  Silicates  of  zinc  and  baryta  impart  similar  properties ;  the  fonner 
has  the  property  of  reducing  the  blue-green  colour  due  to  silicate  of  soda.  Silicates 
of  iron  and  manganese  render  glass  readily  fusible  and  impart  colour  to  it  Silicates 
of  other  metallic  oxides  are  only  of  secondary  importance  in  imparting  colour 
to  glass. 

^^**"**^drof'<SlZ*^"*      According  to  its  chemical  composition  glass  may  be  classified 
as  follows : — 

I.  Potassium-calcium  glass,  or  Bohemian  crystal  glass,  is  quite  colourless,  veiy 
difficultiy  fusible,  hard,  and  very  difficultiy  acted  upon  by  chemicals.  Abroad, 
mirrors  are  often  made  of  this  glass,  mixed  with  any  of  the  foUowing  kinds. 

II.  Sodium-calcium  glass,  French  glass,  window-glass,  somewhat  harder  than  the 


•  • 

a-396  Sp.  gr. 

•  • 

2-487 

•  • 

2488 

•  • 

2642 

•  • 

2732 

)te 

•  3'255 

•  • 

377 

«  • 

5*44 

•  • 

5*62 

OLASS,  269 

preceding  bnt  more  readily  fusible,  exhibiting,  as  does  all  soda-containing  glass, 
a  peculiar  blue-green  hue.     Crown-glass  is  of  similar  composition. 

III.  Potassium-lead  glass,  crystal  glass,  very  readily  fusible,  soft  to  cut.  has  a 
higher  sp.  gr.  than  other  glass,  and  is  more  refractive.  Among  the  varieties  of  this 
glass  are : — i.  Flint-glass,  optical  glass,  in  addition  to  lead  often  containing  bismuth 
and  boracic  acid.     2.  Strass  used  for  preparing  imitation  gems. 

IV.  Alumiuium-calcium-alkali  glass,  or  bottle-ghiss,  always  contains  oxides  of  irou 
and  manganese ;  and  sometimes  magnesium  instead  of  calcium.  The  colour  varies 
from  a  red-yellow  to  a  deep  black-green. 

The  sp.  gr.  of  glass  depends  upon  its  composition.  The  alkali-calcium  glass  is  the 
lightest,  next  follows  aluminium-calcium-alkali  glass,  while  thallium  glass  ia  the 
heaviest,  as  may  be  seen  in  the  following  table : — 

Bohemian  crystal  glass 

V^xUWU-tUABS  ••■         •••         ••■         •«•         •■•         •.■         •■• 

Mirror-glass      

<*  mClv  W-glnSS     •••        •••       •••       •«•        ».•       ••■       ••• 

AjObiie-giass       •••     •••     •«•     ■••     •••     ■••     ■■• 

J^tjttU  glnoo  •••       •■•       ••■       •■•       •••       •••       •••2^ 

Flint-glass  (Frauenhofer's  recipe)         

,,  (Faraday's        „        ) 

Thallium  glass • 

Slowly  oooled  glass  possesses  single,  rapidly  cooled  doubly  refractive  powers ;  the 
refractive  index  of  glass  differs  considerably,  but  is  never  so  high  as  that  of  the  diamond. 
Taking  the  index  of  refraction  of  the  vacuum  of  Torrioelli  as  unity,  that  of  quartz  is 
B  1*547;  diamond,  2*506;  optical  glass  (2*52  sp.  gr.)  =  i'534  to  1*344;  flint-glass  of 
3-7  Bp,  gr.,  1*639;  thallium  glass  — 1*71  to  1*965. 
BAwacatcruunsedia  These  are: — z.  Silica,  viz.  quartz,  for  very  pure  glass,  for  other 
oiaoB-maUiig.  kiiids  saud  of  varying  quality  or  pulverised  flint  stones.  For  very 
pore  glass  the  silica  ought  to  be  free,  or  very  nearly  so,  from  iron ;  in  some  cases  the 
peroxide  of  iron  adhering  to  the  quartz  or  mixed  with  the  sand  is  removed  by  hydro- 
chloric  acid,  while  the  sand  is  always  first  ignited  and  in  some  instances  previously 
washed  to  remove  day,  marl,  humus,  &c.  Ordinary  glass  is  made  with  coarser  materials, 
the  sand  is  not  required  to  be  so  pure,  as  when  it  contains  limo,  chalk,  or  clay,  it  renders 
the  mass  more  fusible. 

2.  Boracic  acid  is  sometimes  used  as  a  substitute  for  a  portion  of  the  silica.  It 
increases  the  fusibility  of  the  glass,  imparts  to  it  a  high  polish,  and  prevents  devitrifica- 
tion.    It  is  employed  as  borax  or  as  boro-calcite,  a  native  boracic  acid. 

3.  Potassa  and  soda  are  used  in  a  variety  of  forms,  the  former  chiefly  as  potash 
(carbonate  of  potassa),  or  partly  lixiviated  wood-ash. 

Not  BO  large  a  quantity  of  soda  is  required  as  of  potash ;  10  parts  of  carbonate  of  soda 
correspond  to  13  parts  of  carbonate  of  potash.  Recently  the  soda  has  been  used  in  the  form 
of  Glauber's  salt ;  in  this  case,  so  much  carbon  is  added  to  the  siliceoas  earth  and  Glauber's 
salt  as  will  reduce  the  sulphuric  acid  of  the  sulphate  of  soda  to  sulphurous  acid,  and  the 
carbon  to  carbonic  oxide.  The  sihoic  acid  then  easily  decomposes  the  sulphurous  acid  of  the 
sulphite.  To  100  parts  of  Glauber's  salt  (imhydrous)  8  to  9  parts  of  coal  are  measured. 
An  excess  of  carbon  is  detrimental,  as  a  large  quantity  of  sulphide  of  sodium  is  formed, 
which  imparts  a  brown  tint  to  the  g^ss. 

4.  The  lime  used  in  glass-manufacture  must  be  free  from  iron.  It  is  generally 
employed  as  marble  or  chalk,  either  raw  or  burnt.  To  100  parts  by  weight  of  sand,  20 
parts  by  weight  of  lime  are  added.  In  the  Bohemian  manufacture  the  Ume  is  employed 
as  neutral  silicate  of  calcium,  Wollastonite,  Si03Ca.  Instead  of  hme,  strontia  and 
baryta  can  be  used,  the  former  as  strontianite  (SrCOj),  the  latter  as  witherite  (BaCOj). 
Fluor-spar  (CaFls),  and  aluminate  of  soda  were  at  one  time  used  in  making  milky  or 
semi-opaque  glass. 

5.  Oxide  of  lead  is  employed  in  most  cases  in  the  form  of  minium  or  peroxide,  giving 
up  some  of  its  oxygon  to  form  a  lower  oxide,  and  purif}dng  the  glass.  The  lead  gives  the 
glass  a  higher  specific  gravity,  greater  brittleness,  transparency,  and  polish.    It  must  be 


270  CHEMICAL  TECHNOLOOY. 

Iree  from  oxide  of  copper  and  tin,  the  former  imparting  a  green  colour,  and  the  latter 
opacity  to  the  glass.    White-lead  is  as  e£Bloaoioiis  as  red-lead,  provided  no  heavy-gpar  be 
present. 

6.  Oxide  of  zinc  is  always  added  as  zinc- white.    When  the  colour  is  not  of  importance, 
zinc-blende  with  sand  and  Glauber's  salts  may  be  used. 

7.  Oxide  of  bismuth  is  only  added  in  small  quantities  in  the  preparation  of  glass  for 
optical  instruments.    Bismuth  may  be  employed  either  as  oxide  or  nitrate  of  the  oxide. 

The  natural  silicates  are  only  employed  alone  in  the  manufacture  of  bottle-glass ;  some 
of  the  preceding  additions  are  requisite  in  clear  glass  manufacture. 

BiAaohing.  Coloured  glass  as  it  occurs  in  the  first  processes  of  manufacture  may  have  the 
colour  disguised  by  mechanical  mixture  with  white  glass,  or  the  colour  may  be  msoharged 
by  chemical  agents.  Such  agents  are  usually — ^braunite,  arsenious  acid,  saltpetre,  and 
minium  or  red-lead. 

X.  Braunite,  MnOat  ^fts  long  been  used  as  material  for  glass-clearing.  This  oxide  of 
manganese  is,  however,  used  only  in  small  quantities ;  too  mnch  imparts  a  yiolet  oar 
ametiliyst-red  colour  to  the  glass;  while  an  excessiye  amount  renders  the  glass  dark 
coloured  and  opaque.  The  violet-coloured  glass  is  generally  prepared  with  silicate  of 
manganese  by  the  addition  of  braunite  to  colourless  glass.  The  action  of  braonite 
in  clearing  glass  or  rendering  it  colourless  has  been  variously  explained.  It  may  be  con- 
sidered that  there  arises  in  the  molten  glass  the  colours  complementary  to  white,  that  is, 
the  green  from  silicate  of  iron  and  the  violet  from  silicate  of  oxide  of  manganese ;  this  view 
is  supported  by  the  experiments  of  Edmer,  who  obtained  a  colourless  glass  from  a  mix- 
ture of  red  and  violet  glasses ;  and  further  by  those  of  Luokow  who  obtained  a  colourless 
glass  by  the  melting  together  of  a  glass  strongly  tinted  red  by  protoxide  of  manganese 
with  oxide  of  copper.  The  glass-blowers  of  the  Bavarian  Waldenses  assert  that  a  rose-red 
quartz  there  found  is  equalled  by  no  other  quartz  in  the  production  of  the  best  czystal  or 
dear  glass.  Yon  Fuchs  says  that  this  quartz  contains  x  to  1*5  per  cent  of  oxide  of 
titaniu|n,  which  similarly  to  braunite,  effects  the  chromatic  neutriJisation.  Eohn 
employs  for  this  purpose  protoxide  of  nickel  or  oxide  of  antimony.  Oxide  of  zinc  has 
lately  been  employed  to  remove  or  mask  the  green  colour  of  Glauber's  salt  glass,  also 
imparting  a  higher  polish.  2.  Arsenious  add  effects  the  removal  of  colour 'by  chemical 
means  only  from  glass  containing  carbon  or  silicate  of  iron :  in  glass  containing  carbon — 

Arsenious  acid,  AS2O3  \     .       ]  Arsenic,  Asa* 
Carbon,  3O  /    ^^®    I  Carbonic  oxide,  3 GO ; 

in  glass  containing  protoxide  of  iron : — 

Protoxide  of  iron,  6FeO,  )     .        f  Oxide  of  iron,  sFcaOj, 
Arsenious  add,  As^Oj,      j    ^        ( Arsenic,  As^. 

The  arsenious  add  is  reduced  by  the  carbon  and  protoxide  of  iron  at  a  dull  red  heat* 
while  the  arsenic  is  volatilised. 

3.  Saltpetre  is  added  chiefly  as  Chili-saltpetre  or  nitrate  of  soda.  In  the  manufaetore 
of  lead-glass  (flint-glass)  nitrate  of  lead  is  substituted  for  the  nitrate  of  soda.  Nitrate 
of  barium  has  recently  been  employed  to  discharge  the  colour  of  glass ;  its  action  is  similar 
to  that  of  arsenious  acid. 

4.  That  minium  serves  to  render  glass  colourless  has  already  been  noted.  Chambland 
states  that  glass  may  be  whitened  by  forcing  through  it  while  molten  a  stream  of  air. 

utiiiMUon  of  liofuM      The  materials  of  glass  manufacture  are  never  mdted  alone,  bnt 
Gijus.  always  with  nearly  the  third  part  of  prepared  or  finished  glass.    For 

this  purpose,  pieces  of  broken  glass,  flaw  glass,  the  hearth  droppings,  and  the  ^asa 
remaining  adherent  to  the  blowers'  pipes  may  be  utilised, — serving  a  purpose  in  the 
manufacture  of  glass  similar  to  the  rags  in  paper-making.  Thus  there  is  only  a  veiy 
small  loss  of  materials.  At  each  re-melting,  however,  a  portion  of  the  alkali  of  the  frag- 
mentary glass  is  volatilised,  and  must  be  replaced  by  the  addition  of  an  alkaline  salt. 

Tb«Meiuai{Ve«8ei.      The  vessels  iu  which  the  glass  is  melted  are  placed  immediately 

upon  the  hearth,  and  are  made  of  difiiculty-fasible  clay  and  powdered  chamotte- 

stone.    They  are  usually  06  metre  in  height,  the  walls  being  9  to  12  centimetres 

thick.    They  are  dried  in  a  temperature  of  12''  to  15°,  and  then  placed  in  a  chamber 

heated  to  30°  to  40°.    After  remaining  about  a  month,  the  vessel  is  put  into  the 

tempering  or  annealing  oven,  heated  to  50° ;  it  is  next  removed  to  the  ordinary 

melting-oven,  and  gradually  heated  to  the  melting-point  of  glass,  at  wliich  it  remains 

for  three  to  four  hours.    When  a  new  pot  is  first  used  for  glass-melting,  the  alkaline 

constituents  of  the  glass  act  upon  the  clay,  forming  a  rich  clay  glaze  or  glass,  which, 

if  fdlowed  to  mix  with  the  ordinary  glass,  would  be  highly  detrimental.     Conse- 


0LA3S.  a;  I 

qnentl;  broken  glass  and  refuse  are  first  melted  in  the  TeEBel,  and  the  glaze 
imparted,  termed  technically  the  lining,  is  a  sufficient  protection  to  the  glass  in 
after  practice.  The  shape  of  the  melting  vessels  varies.  For  melting  with  wood  or 
gas  the  conical  form,  Fig.  izo,  is  employed.  When  coal  is  used  as  fuel,  the  vessel 
takes  the  covered  form,  Fig.  izi.     Fig.  122  represents  a  rather  peculiar  form;  tlie 


Pro. 


glass  constitaents  are  melted  in  a,  the  clear  molten  glass  passing  by  tlie  aperture  in 
the  central  wnll  iiit«  a.  The  glass  in  b  is  thus  always  free  from  glnss-gall  or  impu- 
rities, whicli  remain  behind  in  a.  In  the  manufacture  of  looking-glasses,  large 
qnadraugnlar  vessels,  P'ig.  123,  are  employed  for  refining  piirpoaea. 
TtaQiMtomn.  The  glass  ovens  are  respectively — i.  The  melting  oven;  z.  The 
tempering-  or  annealing-ovens,  used  in  the  aiW-manufactuie.  .  The  melting-oven 
can  only  be  made  of  fire-proof  clay.  It  is  buiit  of  a  miixture  of  white  clay  and  bnrnt 
clay  of  the  same  kind.  Ordinary  mortar  and  cements  are  useless  for  this  purpose 
on  account  of  their  fusibility,  therefore  the  same  clay  as  is  used  for  building  is  also 
used  for  binding.  The  oven  must  be  built  on  dry  ground ;  if  built  on  damp  ground 
it  is  difficult  to  maintain  the  lower  parts  at  a  constant  heat,  reqniringa  larger  supply 
of  fuel.  The  arch  is  closed  with  a  single  piece  of  flre-proof  clay  weighing  800  to 
1000  cvrta.  After  building  the  oven  is  dried  for  four  to  six  months  at  a  temperature 
of  12°  U)  15° :  a  low  fire  is  then  lighted,  and  the  temperature  gradually  increased  for 
about  a  month  until  the  oven  is  fit  for  actual  work.  The  arch  is  further  covered 
with  massive  backstones,  and  these  again  are  covered  to  a  thickness  of  5  to  6  inches 
withalime-mortar.  Whenmiich  in  use,  and  if  not  built  of  very  good  clay,  an  oven  will 
not  remain  in  working  orderfor  longer  than  il  to  i|  years;  butif  fire-clay  is  used,  and  . 
only  easily -fusible  lead-glass  is  manufactured,  the  oven  may  last  for  four  to  five  years. 
The  oven  contains  six  or  eight  to  ten  melting-pots,  which  must  all  be  raised  to  the 


CHEMICAL    TECHHOLOQY. 


Bame  temperatare.  Further,  I 
The  tumexed  woodcut,  Fig.  124 
aectiou  showing  the  melting-o 


melting-ovea  is  placed  over  half  the  fire-raMn. 
a  gTousd  plan  of  a  coia|ilete  ovea  Fig  115  is  & 
I  and  work-holes;    Fig    126    a  vertical  eecvm 


throug_  ili_  l_L^ flj.UT'U,  Pig.  127  a  vertical  i.-Mi-!  ••' ''i-    li-adth.    In  tha 

groimd  plan,  Fig.  134.  00  is  the  flue;  occare  the  melting-pota ;»  n,  pots  contRining 
glssB^  another  stage  of  preparation ;  ddit,  tlie  work-holea  ;  bh,  the  banks ;  li,  irsnn- 
ing  and  cooling  ovens:  h'k,  tempering  ovens ;  «  e,  the  breast  walla ;  //,  the  splint 
walls  1    1 1  are  small  hearths  to  increase  tlie  heat  in  the  ten^ring  oven  when 


required.  In  Fig.  135  I  is  the  flue;  y  y  are  blocks  of  stone,  bearing  the  troodi^D 
frame-work,  z  z,  on  wliioh  the  wood  used  as  fuel  is  placed  to  dry.  Fig.  126  sIipts 
the  bank,//,  on  wliich  die  melting-pots,  ft  ft  ft,  stand ;  orer  these  pots  are  the  wor!;- 
holoa  ;  n  »  are  the  side  chambers.  In  Y\g.  127,  h  b  is  the  k?y -stone  ;  nl  axe  the 
banks :  g  the  flue,  altliongh  in  most  glass-ovens  there  are  no  ftues.     llic  fliune  from 


OLASS.  373 

the  fuel  bnniing  in  both  gTHtea,  m  in,  Fig.  126,  after  heatuig  the  meitiiig  oren, 
puses  by  the  tempering  rooma,  and  finally  to  the  chimney- Btalk. 

Siemens'a  gas-oven  has  lately  found  eitensiTo  use.    At  the  Paris  Intemitionttl 
BibitAtion  of  1S67  this  oven  obtained  the  gold  medal.     It  coneista  of  two  parts,  the 


generator.  Fig.  13S,  and  the  melting  oven,  Fig.  izg.  These  parts  are  separate,  and 
eu  be  jo  or  more  metres  from  each  oilier,  being  connected  by  a  large  gas-pipe.  The 
tael,  brown  coal,  turf,  stone  coal,  or  wood,  is  placed  in  the  generator  at  a,  Fig.  iz8. 


ud  Ealla  on  the  sloping  1 
ascends  at  a  temperaton 
I^pe,  V,  4  to  s  metres  in 


,  a  mixture  of  carbonic  oxide  and  nitxogen, 
and  flows  ont  of  tbo  generator  by  a  large 
iveyed  thence  by  a  tiorizontal  pipe  to  the 


174 
melting  o' 


CHEMICAL  TECHNOLOGY. 


aUaline  conatilaenta  were  added  a 
Fio,  ii8. 


The  Tipper  chambers  of  the  melting  oven  are  similu'  to  thoEe  of  th« 
nsnal  orena.  p  p  are  the  melting-pots.  The  gns  first  passes  into  the  first  system  of 
regenerators,  the  atones  of  which  are  raised  to  a  red-heat,  and  passes  thence  to  the 
melting  room,  where  it  meets  with  air  heated  in  hke  manner.  The  prodocts  of  com- 
bustion then  pass  to  the  second  regenerating  sjstem,  the  stones  of  which  are  cold 
nntil  heated  by  the  passing  gases.  The  waste  gas  is  finally  conducted  to  the 
chimney-stalk.  When  stone-coal  is  used  in  the  generator,  lead-glass  may  be  melted 
in  the  oven  in  open  vessels  witliout  reduction.  The  saving  of  fuel  in  comparison 
with  the  old  system  is  about  30  to  50  per  cent, 

Fonnertf  manufactured  glass  was  only  an  imitation  of  erystalliiM 

siliceoas  earths,  the  chemical  action  being  but  little  known.    The 

'  ■"   ■"        flnies,  and  to  this  day  retain  that  name.     Hoverer, 

most  of  the  results  attending  the  Taristiont 

of  temperature  were  known,  and,  in  lact,  the 

chief  practioal  detail. 

Of  especial  importanoe  In  glass  mannfaetnTe 
is  the  knowledge  of  the  beharionr  of  glaca 
in  the  fire.  At  the  maximom  temperatDrc  of 
glasB-melting  ovens,  1200°  to  1250°  C,  the 
glass  forms  a  thin  fluid  of  the  consistency  of 
syrup.  This  condition  ia  essential  to  tha 
refining  of  the  gloss,  as  the  thinness  of  tha 
fluid  admits  of  the  settlement  of  foiei^ 
substances  to  the  bottom,  or  of  their  floating 
to  the  snrface  of  the  glass  contained  in  the 
melting-pot.  In  this  condition  also  the  dear 
molten  glaes  can  be  ran  off.  At  a  red-heat 
glass  is  exceedingly  ductile  and  flexible :  opoo 
UiiB  qoality  depends  its  application  in  maao- 
faclnie.  Two  pieces  ot  glass  raised  to  a  red 
heat  can  be  welded  into  one  piece  by  mere 
pressure.  Glass  as  a  fine  thread  is  generally 
flexible,  and  may  be  spun.  Undoubtedly  glass 
will  be  used  as  a  spinning-Sbre  at  some 
future  time ;  even  now,  in  the  International 
Eihibition  of  1871,  there  are  several  articles 
of  habiUment  made  of  spun  glass,  exhibited  by 
an  Austrian  firm.  Bmnfaut.  of  Vienna,  in  i86g, 
prepared  glass- wadding,  feathers,  bows,[aToiirt, 
nets.  &c.  Glass  fibre,  according  to  the  mea- 
surement of  Fr.  Kick,  of  Fra^e,  can  be  spun  to 
a  diameter  of  0006  and  0011  millimetres. 
When  glass  is  allowed  to  cool  extremely  slowly  it  loses  its  transparency,  and  is  transfoimed 
into  an  opaque  moss  known  as  R^anmoi's  porcelain.  The  chemical  action  taking  place  when 
glass  is  rendered  opaque  is,  in  spite  ot  numerous  researches,  still  unexplained.  On  the  other 
hand,  glass  cooled  too  suddenly  acquires  pecnhar  properties.  Detonating  bnlbs  are  small 
glass  Qaaks  which  have  been  cooled  immediately  after  being  made.  IF  a  sharp  grain  ot 
sand  be  dropped  into  the  interior  ol  one  of  these  flasks  it  will  fly  to  pieces  with  eioeeaiTB 
violence,  while  the  exterior  will  bear  hard  usage  without  result.  Another  peculiarity  of 
glass  manufacture  are  glass-tears,  or  Prince  Rupert's  drops,  long  pear-shaped  drops 
of  glass,  tapering  to  a  very  slender  tail,  which  are  formed  by  dropping  molten  glass 
into  cold  water.  The  bulb  of  these  drops  ma;  be  struck  with  a  hammer ;  but  it 
only  a  small  portion  of  the  tail  be  snapped  off,  the  entire  drop  will  break  up  with  a  load 
report.  This  brittleness  is  more  or  less  the  characteristic  of  all  unannealed  glara, 
andia  probably  dae  to  unequally  cooled  layers,  which  are  conseqnently  at  different  d^;re« 
ot  tension. 

prri^ (hi Hiiaiik.  Before  the  materiak  areplaced  inthemeltingoven,  they  are  first 
subjected  to  a  tolerably  strong  heat,  not  snfBcieut,  however,  to  effect  fusion  in  the 
drying  oven.  The  benefit  of  tliis  operation  is  the  removal  of  the  carbonic  acid  and 
ivater  which  would  otlierwise  be  disseminated  in  the  melting  oven.     Some  manufac- 


GLASS. 


»7S 


turers  dispense  with  thia  portion  of  the  process,  numing  a  risk  of  tnnung  ont 
imperfect  glass  that  can  be  avoided  at  a  very  small  expense. 

ifiiuBfihiaiuiHitwtiLL  When  the  temperature  of  the  melting  oven  has  reached  the 
required  degree,  the  material  first  frite  together  and  is  then  melted.  The  oven 
mnst  be  heated  equably  thronghout.  At  the  melting-point  the  Biliceous  earth 
oombiues  with  the  potash,  soda,    lime,  alumina,  aside    of  lead,    &c.,    to    fonn 


glaas.  The  substances  not  taken  op  form  a  scnm,  known,  as  glass-gall,  upon 
the  molten  glass,  which  is  removed  by  the  aid  of  iron  shovels.  This  scam  is 
generallj  composed  of  sulphate  of  soda  and  chlorides  of  the  alkalies.  The  progress 
of  the  melting  process  ii  from  time  to  time  ascertained  by  removing  a  sample  of  the 
glass  by  the  help  of  an  iron  rod  terminating  in  a  flat  disc,  in  fact  a  large  flat  spoon. 

oni-iHiuBf.  When  the  mass  is  well  molten  it  is  "cleared,"  that  is,  maintained  for 
some  time  at  such  a  temperature  that  the  glass  remains  in  a  thinly  fluid  condition. 
Daring  this  period  the  uncorabined  substances  sctlle  to  the  bottom  of  the  melting 
TCBsel,  the  air-hubbies  disappear,  and  the  glass-gall  still  remaining  is  volatilised  or 
separated.  At  the  commencement  of  the  melting  the  disengage ment  of  the  gases 
from  the  molten  mass  causes  an  advantageons  agitation,  by  which  the  several  con- 
stituenlB  of  nnequal  specific  weight  and  different  composition  become  well  mired. 
Ait«r  the  disengagement  of  the  gases  the  lower  part  of  the  melting  vessel  ia  at  a 
lower  temperatnro  tlian  the  upper  part,  consequently  the  molten  glass  is  well  stirred 
with  the  iron  ladles  or  "  poles."  Lastly,  a  piece  of  either  arsenious  acid,  damp 
wood,  raw  tornip,  or  any  other  water -containing  substance,  is  introduced  to  the 
bottom  of  the  vessel  on  an  iron  rod,  the  end  in  view  being  the  violent  agitation  of  the 
molten  glass  by  the  steam  evolved. 

orti^wuia.  After  the  completion  of  the  clearing  follows  the  cold-stoking,  that  is, 
the  lowering  the  temperature  of  the  oven  till  the  glass  nttiuns  a  tough  fluid  consis- 
tency requisite  before  it  can  be  blown.  The  glnss  remains  at  Uiis  temperature, 
700=  to  800°  C,  during  the  rest  of  the  manufacture. 


1 


276  CHEMICAL  TECHNOLOGY. 

Tlie  length  of  the  several  processes  is  as  follows : — 

Melting     10  to  12  honrs. 

Clearing    4  to    6     „ 

Blowing    10  to  12     9t 

so  that  five  to  six  meltings  can  be  effected  in  a  week. 

Defects  in  ouua.  It  is  extremslj  difficult  to  prepare  glass  perfectly  free  from  Uemish. 
The  principal  defects  are — streaking,  threading,  running  unequally,  or  dropping,  stoningi 
blistering,  and  knotting.  Streaking  follows  from  heating  the  glass  unequally,  another 
consequence  of  which  is  the  threading  or  the  formation  of  the  striaB,  by  glazing,  into 
coloured  threads,  generally  green.  By  dropping  is  understood  the  lumps  or  globnlei 
formed  in  the  glass  by  the  glazing  of  the  clay  cover  of  the  melting  vessel,  and  its  combi- 
nation with  the  volatilised  alkalies,  the  crude  glass  thus  formed  on  the  cover  dropping 
into  the  molten  glass  contained  in  the  vessel.  Blistering  is  a  common  result  of  the  imper- 
fect clearing  of  the  glass  from  air  bubbles.  Lastly,  knotting,  another  common  defect, 
results  from  uncombined  grains  of  sand  taken  up  in  the  glass ;  the  small  particles  of  the 
oven  and  melting  vessel  detached  during  the  melting  similarly  giving  rise  to  stoning' 
Other  defects,  such  as  the  imperfect  combination  of  the  materials,  arising  from  caielees* 
ness  or  inability  of  the  workman,  need  not  here  be  noticed.  * 

Various  Kinds  of  oiass.      Glass  is  Separated  according  to  its  composition  or  method  of 

manufacture  into : — 

I.  Glass  free  from  Lead. 

A.  Plate-glass,    a.  Window  glass : — 

a.  Boiled  glass. 

p.  Grown  glass. 
h.  Plate-glass: — 
a.  Blown  plate-glass. 
p.  Cast  plate-glass. 

B.  Bottle  glass : — 

a.  Ordinary  bottle  glass. 

b.  Medicine  and  perfumery  glass. 

c.  Glass  for  goblets,  drinking  glasses,  &c. 

d.  Water  pipes  and  gas  tubes. 

e.  Retort  glass. 

0.  Pressed  or  stamped  glass. 
D.  Water  glass. 

n.  01^188  containing  Lead  {Flint-Olass).  ' 

A.  Crystal  glass. 

B.  Glass  for  optical  purposes. 
G.  Enamel. 

D.  Strass. 

III.  Coloured  Glass  and  Glass  Staining. 

IV.  Glass  Decorations. 
i>9«t«-  or  wfndAw-oiAM  The  glass  melted  in  muffles  or  vessels  is  manufactured  as  plat^ 
glass  or  as  crown-glass.  Plate-glass,' as  its  name  implies,  is  formed  in  large  or  tswsS^ 
plates ;  window  glass  is  generally  either  ordinary  bottle  glass,  or  a  finer  glass  d 
a  whiter  colour.  Becently,  thick  has  taken  the  place  of  thin  glass  for  windows,  bat 
the  colour  is  hereby  considerably  increased.  That  window  glass  should  be  prepared 
cheaply  is  an  essential  point,  consequently  crude  materials  are  employed— crude 
potash  and  soda,  wood-ash,  Glauber's  salt,  ordinary  sand,  and  broken  glass  from  the 


GLASS. 


277 


warehouses,  &c.  Plate-  or  window-glass  is  generally  composed  of  100  parts  sand, 
30  to  40  parts  of  crude  calcined  soda,  30  to  40  parts  of  carbonate  of  calcium. 
Instead  of  the  soda  may  be  substituted  an  equivalent  quantity  of  Glauber's  salt. 
Benrath  (1869)  found  in  several  kinds  of  plate-glass  the  foUowing  constituents : — 

Silicic  acid       

ooQa         •••     ■••     ■•■     ••■     •••     •••     • 

xji  me        •■•     •••     •••     •••     •••     •••     • 

Alumina  and  oxide  of  iron 


7071 

7156 

73" 

I335 

1297 

1300 

1358 

I327 

1324 

1*92 

1*29 

083 

9946 


99*09 


iooi8 


Teoii.  The  tools  ordinarily  used  by  the  glassblower  in  the  preparation  of  plate-  and 
croim-glass  are  the  following : — 

tt.  The  pipe  or  blow- tube,  Pig.  130,  is  an  iron  pipe  1-5  to  i-8  metres  in  length,  3  to  4 
centimetres  thick,  and  i  centimetre  interior  diameter,    a  is  the  mouth-piece,  made  so  as 

Fio.  130. 


sss 


to  turn  easily  between  the  lips,    c  is  a  hollow  handle  from  0*3  to  0*5  metre  in  length,    h  is 
the  part  attached  to  tilie  glass. 

6.  The  handle  or  hand  irons  are  rods  i  to  1*3  metres  in  length,  used  to  transport  the 
hot  vessels,  Ac.  e.  The  marbel.  Figs.  131  and  132,  is  a  piece  of  wood  with  semi-globular 
indentations,  which  serve  as  matrices  for  the  glass  to  be  taken  up  on  the  blower's  pipe.- 
d.  The  whip,  a  block  of  wood,  hollowed  so  as  to  form  a  long  neck  to  the  soft  semi-molten 


Fig.  i3». 


Fig.  132. 


Fig.  133. 


Fig.  134- 


K^ ;  it  is  also  used  to  remove  the  glass  from  the  pipe,  e.  Fig.  134,  are  the  shears  used 
tot  trimming  the  molten  glass,  and  to  cut  openings  during  the  blowing  of  various 
ar'iaeles. 

Plftte-glass  is  manufactured  as  crown-glass  or  as  rolled  glass. 

<^owii-cka«.  Crown-glass  is  the  oldest  kind  of  window  glass.  It  is  formed  in  the  manufao- 
toie  as  a  disc  of  glass,  generally  of  about  six  inches  in  radius  from  the  periphery  to  the 
oentre  knot  left  by  the  glassblower's  pipes,  technically  termed  the  bull's-eye.  The 
Itfgest  discs  are  scarcely  64  to  66  inches,  from  which  a  square  plate  of  22  inches  only  can  be 
eut,  the  bull's-eye  inteiiering  with  the  cutting  of  a  larger  size.  In  the  preparation  of  this 
S|tt8  three  workmen  are  employed ;  the  first  takes  so  much  molten  glass  on  the  end  of  a 
pipe  as  will  serve  for  a  single  disc,  and  passes  pipe  and  glass  to  the  second  workman,  the 
Uower.  He  blows  the  glass  into  a  large  globe  or  ball,  which,  when  finished,  he  hands  to  a 
third  workman,  the  finisher,  who  opens  the  globe  and  forms  the  sheet  or  pane.  The 
labour  is  divided  in  detail  in  the  following  manner: — The  first  workman  receives  the 
^^vm  pipe,  thrusts  it  into  the  vessel  of  molten  glass,  and  turns  it  steadily  round  imtil  he 
OMB  collected  upon  the  end  a  knob  of  glass  of  sufficient  size.  The  weight  of  this  knob  is 
t^iOBnXiy  10  to  14  pounds.  The  first  workman  imparts  somewhat  of  a  spherical  form  by 
^o»$OM  of  the  marbel  to  the  solid  glass  ball,  which  is  now  taken  in  hand  by  the  blower. 


378 


CHEMICAL    TECIiyOLOGY. 


who  by  turning  and  shifting  tbe  gt&aa  aboat,  at  tbe  same  time  blowing  throngh  tha  tabe, 
perfeota  tlie  hollow  Bpheroid.  The  glass  has  by  this  time  cooled  considerabl; ,  and  nth 
tbe  pipe  is  therefore  returued  to  the  oTen,  the  tnbo  of  the  pipe  beiug  faateued  in  a  fork  or 
book  Id  the  ceiling  of  the  oreu.  As  tbe  globe  of  glass  ia  gradnally  heated  tbe  weight  «i 
the  rod  causes  it  to  flatten  out,  aod  it  is  remoTed  by  the  finisher  aa  a  di&c  ol  nearl; 
molten  glass.  He  pliicea  the  tube  in  tbe  cavity  of  tbe  whip,  and  by  a  series  of  deiterooj 
inovementB  perfects  tbe  shape,  enlarges  the  disc  if  req^uired,  or  in  some  cases  m»kM 
a  larger  disc  bj  removing  the  partially  flattened  sphere  (rom  the  oven,  opening  the  bottom 
with  a  maul  or  iron  rod,  and  causing  tbe  glass  to  take  the  form  of  a  disc  by  means  of  the 
centrifugal  force  resulting  from  a  rapid  rotary  motion  of  the  rod.  Finally  the  discs  in 
separated  from  tbe  pipe  by  the  help  of  a  drop  of  oold  water,  and  are  next  placed  in  an 


Fio.  135. 


SuSfcJ^w  Rolled  ot  sheet  glass  is  made  by  cutting  a  glass  cylinder  or  rJ 
throughout  its  length,  and  beating  or  rolling  it  out  flat  on  a  table.  It  ia  for  U>>> 
reason  termed  sheet  glass.  Usually  this  sheet  glass  is  used  for  ground  glass,  and  >> 
further  separated  into  ordinary  sheet  or  roU-glass  and  fine  sheet  glass,  the  WW 
having  larger  dimensions. 


GLASS. 


279 


The  preparation  of  sheet  glass  is  one  of  the  most  difficult  processes  of  glass  manu- 
fiictare ;  it  may  be  considered  as  consisting  of  two  operations — 

1.  The  blowing  of  the  roll,  or  cylinder ;  and. 

2.  The  flattening. 

After  the  molten  glass  has  cleared,  and  attained  the  barely  fluid  consistency 
before  mentioned,  the  workman  inserts  his  pipe  into  the  mass,  and  by  turning  manages 
to  accumulate  on  it  a  globe  of  glass,  during  the  time  blowing  into  the  tube  to 
keep  it  clear  of  the  molten  glass.  The  glass  now  takes  the  form  a.  Fig.  135.  By 
continued  manipulation  in  the  marbel,  and  by  blowing,  tlie  enlarged  forms,  b  and  c^ 
and  finally  d,  are  obtained.  The  glass  has  by  tliis  time  cooled,  and  is  taken  to  the 
OTen  to  be  re-heated.  When  this  is  effected,  the  workman  by  means  of  his  tools,  by 
a  continued  rotation  of  glass,  and  by  blowing,  brings  the  globe  to  the  shape  repre- 
sented by  /.  He  then  opens  out  the  bottom  of  this  form  with  a  maul-stick,  and 
obtains  the  cylinder  ^,  which  is  separated  from  the  pipe  by  dropping  a  little  cold 


Fio.  136. 


Fio.  137- 


water  upon  the  neck,  o,  joining  the  two.     The  removal  of  this  neck  is  next  effected 

by  means  of  a  red-hot  iron  rod,  which  also  serves  to  open  the  cylinder  throughout 

its  length  as  shown  by  h. 

After  a  great  number  of  these  cylinders  have  been  blown,  the  operation  being  generally 
eontinned  for  three  days,  the  opening  into  plates  is  commenced.  The  cylinders  are  placed 
in  an  oven  termed  the  plate-oven,  shown  in  ground  plan  in  Fig.  136,  consisting  of  two 
chambers,  one  the  heating  room,  0,  and  the  other  the  tempering  or  annealing  room,  d. 
In  the  passage  b,  the  heated  glass  rolls  or  cylinders,  a  a  a^  are  suspended  upon  two  iron 
rods,  where  they  are  maintained  at  a  certain  heat.  The  most  important  part  of  the  plate- 
OTen  is  the  platten,  c,  made  of  a  well-rammed  fire-clay.  A  similar  plate,  d,  is  placed  in 
the  annealing  room.  When  sufficiently  heated,  the  cylinders  are  brought  to  the 
flattening  table,  c,  Fig.  137,  where  they  are  speedily  opened  out  in  the  manner  shown  in 
the  woodcut.  A  workman  stationed  at  d,  Fig.  136,  receives  the  flat  panes  of  glass,  and 
ItsDs  them  against  the  iron  bars,  «  «,  in  the  annealing  room,  whence,  having  gradually 
cooled  during  four  to  five  days,  they  are  removed  to  be  sorted  and  packed. 

n*t»<»Ma.  Plate-glass  is  either  blown  or  cast.  The  manufacture  is  very  similar  to 
that  of  table-glass  just  described.  The  materials  are  in  great  part  the  same  as  those 
employed  in  the  manufacture  of  flue  white  glass.  This  branch  of  glass  manufacture 
is  most  strikingly  illustrative  of  the  rapid  growth  of  the  industry  during  the  last 
ten  or  twenty  years.  Formerly  plate-glass  was  esteemed  an  article  of  luxury, 
whereas  now  it  is  that  most  generally  used  for  workshop  windows,  carriages,  show- 
rooms, &c.,  and  for  windows  of  private  residences.    It  far  surpasses  in  transparency 


i8o  CHEMICAL   TECEN0L0G7. 

and  elegance  the  eioall  panes  formerly  used.  By  the  Glass  Jary  of  the  IntematioMl 
Eihihition  of  Paris  of  1867.  it  was  s«rmised  that  before  ten  years  had  elapsed  plat«- 
glaBB  would  be  that  most  generally  in  the  market.  The  blowing  cf  plate-glsas  ia 
effected  with  the  same  tools  as  the  hlowing  of  table-glass;  and  the  cylinder  ia 
obt^ned  in  a  aimilar  manner.  Th«  lump  of  glass  taken  by  Uie  blower  on  his  pipe 
from  the  melting  ressel  weighe  about  45  lbs.,  from  which  a  plate  of  i'5  metres  in 
length  and  i  to  I'l  metres  breadth  by  i  to  11  centimetres  thicknessis  obtained.  But 
the  chief  method  of  making  plate-glaaa  is  by  casting.  Cast  plate-glaaa  is  always  made 
from  pnre  materials,  and  may  be  considered  as  a  soda-calcium  glass  free  from  lead. 
Potash-caldnm  glass  ia  far  more  expensive,  being  almost  a  colourless  glass.  In 
England,  Belgium,  and  Germany  the  raw  materials  used  in  manufacturing  castplste- 
glass  are — sand,  Umestone,  and  soda,  or  Glauber's  salts. 
Benrath  (1869)  fonnd  in  English  {<t)  and  in  German  (^)  plate-glass: — 

p. 

Silica 76300  78750 

Soda 16550  i3'ooo 

Lime 6-5O0  6500 

Alumina  and  oxide  of  iron     0650  1750 

1 00000  100  000 

Sp-P- 2-448  2456 

The  fc^wing  description  of  casting  the  plates  is  mainly  founded  upon  the  method 
pursued  at  St.  Gobin  and  Bavenbead.    The  manu&cture  is  included  in — 

1.  The  melting  and  clearing, 

2.  The  casting  and  cooling, 

3.  The  polishing :  including 

0.  The  rough -polishing, 
(3.  The  fine -polishing, 
y.  Finishing. 
Tilt  iMitu  ■mJ  ciMiiiii.      The  melting  and  olearing  vessels  are  of  very  different  fotm  ™d 
BJae.    The  first  is  a  oonioal  veeael  surmonnted  b;  a  cnpola  having  three  apertures,  miUag 

Fio.  138. 


an  sngle  ot  110°  with  each  other.  The  clearing  pans  are  small,  wide,  and  low  tm>«1i- 
These  vessels  are  never  in  the  same  oven.  After  the  materiBls  are  melted,  vhieh  u 
effected  in  sixteen  to  eighteen  hours,  the  molten  mass  is  poored  into  the  clearing  veMal*- 


GLASS.  281 

The  impurities  are  then  removed  with  a  large  copper  ladle,  this  process  oconpying  abont 
six  hours.  During  the  clearing  the  excess  of  soda  is  volatilised.  When  the  glass  is 
Obstins  and  Cooling,  saffioicntlj  cleared  the  casting  commences.  The  vessel  containing  the 
molten  glass  is  taken  up  by  a  crane  and  swung  to  the  casting  table,  this  table  or  mould 
being  on  a  level  with  the  cooling  or  annealing  oven.  The  casting  table  consists  of  a 
large  polished  metal  plate,  Fig.  138,  in  the  French  work  of  copper  or  bronze,  4  metres 
long,  2-15  metres  wide,  and  12  to  18  centimetres  thick.  The  plate  at  St.  Gobin  weighs 
55,000  lbs.  and  cost  100,000  francs  (£4000).  In  England  the  plates  are  of  cast-iron, 
25  centims.  thick,  5  metres  in  length,  and  2*8  metres  wide.  In  order  that  the  glass 
plate  shall  be  of  equal  thickness,  a  bronze  or  cast-iron  roller  passes  over  the  surface  on 
guides  of  the  thickness  required.  The  metal  plate  is  first  warmed  to  prevent  the  sudden 
cooling  of  the  glass.    The  operation  of  casting  includes — 

a.  The  conveyance  of  the  pan  to  the  table  ; 
5.  The  cleansing  of  the  plate  and  the  pan  ; 
e.  The  casting  and  conveyance  of  the  plate  to  the  annealing  room. 

The  cooling  room  has  two  fire-places  and  three  glass  tables.  The  temperature  is  at 
first  that  of  the  glass  plate  introduced.  So  soon  as  three  plates  are  placed  in  the  oven,  all 
the  openings  are  closed,  and  the  glass  left  for  a  day  to  cool.  The  cooled  glass  plate  is 
taken  out  of  the  annealing  oven  to  the  cutting  room,  laid  on  a  cloth-covered  table,  and 
cut  to  size  with  a  diamond. 

VaUahiag.  The  glass  plate  is  out  into  tablets.  The  under  side  of  the  plate,  where  it  has 
been  in  contact  with  the  table,  is  smooth,  while  the  upper  surface  is  wavy,  and  requires 
to  be  polished.  This  is  efFected  by  fastening  the  plate  or  tablet  to  a  bench  with  plaster- 
of-Paris,  and  grinding  the  upper  surface  smooth  with  some  sharp  powder ;  or  another 
plate  is  caused  by  machinery  to  move  above  the  former  in  such  a  manner  that  the 
surfaces  of  both  are  ground  smooth.  The  ground  plates  are  then  removed  to  the  polishing 
table,  where  a  similar  process  is  gone  through,  but  with  a  finer  powder.  Fin^y,  when 
placed  upon  the  finishing  table  only  the  finest  powder  and  leathern  pads  are  employed. 
By  grinding  and  polishing  the  glass  sometimes  loses  half  its  weight  and  thickness. 
Suppose  a  plate-glass  manufactory  to  produce  400,000  square  feet  of  glass  annually,  there 
will  be  with  this  amount  of  glass  weighing  about  16,000  cwts.,  a  loss  of  8000  cwts.,  corre- 
sponding to  2700  cwts.  of  calcined  soda,  and  a  money  value  of  more  than  £1000. 

suvwing.  After  polishing,  each  glass  tablet  intended  to  make  a  looking-glass  is  silvered, 
or  more  correctly  coated  on  one  side  with  an  amalgam  of  tin.  In  the  preparation  of  this 
amalgam  tin-foil  is  used,  but  it  must  be  beaten  from  the  finest  tin,  and  possess  a  surface 
frimiUT  to  that  of  polished  silver.  The  art  of  silvering  is  simple,  and  merely  requires 
dexterity.  The  glass  plate  having  been  thoroughly  cleansed  from  all  grease  and  dirt  with 
pntty-powder  and  wood-ash,  the  workman  proceeds  to  lay  a  sheet  of  tinfoil  smoothly 
upon  the  table,  carefully  pressing  out  with  a  cloth  dabber  all  wrinkles  and  places  likely 
to  form  air  bubbles.  He  spreads  over  it  a  quantity  of  mercury,  taking  care  that  all 
parts  are  equally  covered,  and  then  the  glass  plate  is  pushed  gently  on  to  the  surface, 
conmiencing  at  one  edge.  A  glass  plate  of  30  to  40  square  feet  requires  150  to  200  pounds 
of  mercury,  although  the  am^am  is  not  so  thick  as  a  sheet  of  the  finest  paper.  The  glass 
is  allowed  to  remain  for  twenty-four  hours.  It  is  then  removed  to  a  wooden  incline  similar 
to  a  reading  desk  to  allow  of  the  excess  of  mercury  draining  off.  As  the  amalgam 
gradually  sets,  the  incline  is  increased  till  finally  the  plate  reaches  the  perpendicular, 
when  the  process  is  finished,  and  the  mirror  removed  to  the  store-room. 

BDvwiaffby       ^®  former  method  of  coating  the  glass  with  tin-amalgam  obtains  its 

FxMipiuttoii.  name  of  silvering  by  analogy  only:  tiie  true  process  of  silvering  is  the 
following,  patented  in  1844  by  Mr.  Drayton : — ^32  grms.  of  nitrate  of  sUver  are  £ssolved 
in  64  gzms.  of  water  and  z6  grms.  of  liquid  ammonia,  adding  to  the  filtered  solution 
X08  grms.  of  spirits  of  wine  of  0*842  sp.  gr.,  and  20  to  30  drops  of  oil  of  cassia.  Call 
this  fluid  No.  x.  Another  fluid  (No.  2)  is  prepared  by  mixing  i  volume  of  oil  of  doves 
with  3  ToltmieB  of  spirits  of  wine.  The  workman  places  the  glass  plate  upon  a  table, 
earefolly  levels  it,  and  floods  it  to  a  depth  of  0*5  to  i  centimetre  with  fluid  No.  i.  He 
then  precipitates  the  silver  by  adding  6  to  12  drops  at  a  time  of  fluid  No.  2  until  the 
whole  of  the  surface  is  covered.  For  every  square  foot  of  glass  9  decigrammes  of  nitrate 
of  silver  are  required.  Liebig  recommends  an  ammoniacid  solution  of  fused  nitrate  of 
silver,  to  which  450  c.c.  of  soda-ley  of  1*035  ^p.  gr.  are  added.  The  precipitate  thrown 
down  is  dissolved  by  means  of  ammonia,  the-  volume  being  increased  to  1^50  c.c, 
and  by  water  to  1500  c.c.  This  fluid  is  mixed  shOrtiy  before  application  with  one- 
sixth  to  one-eighth  of  its  volume  of  solution  of  sugar  of  milk,  containing  10  parts 
by  weight  to  i  of  sugar  of  milk.  The  glass  is  flooded  with  this  fluid  to  about  half- 
an-inch  in  depth ;  reduction  soon  sets  in,  and  the  glass  becomes  thickly  coated. 
X  square  metre  of  glass  plate  requires  2*2x0  grms.  of  silver.     The   plate   is  then 


383 


CHEMICAL   TECHNOLOGY. 


dried,  olMited,  and  poliihed.  Lowe  emplo^B  nitrate  □{  bUtbt,  Btanh-sngu',  and  poUih ; 
A.  Mftrtin,  oitiate  of  silver,  ammonia,  and  tartaric  acid. 

FiiUniUnf.  Axicordicg  to  tlie  reaeaicbeB  of  Cod£,  platiamn  may  be  need  tor  coBting 
plate-glass.  In  Franoe,  Creanell  and  Tavemier  have  already  broaf(ht  platinised  mirTore 
before  the  public.  Hitherto  platisnm  has  been  aaed  in  ornonientiiig  porcelain,  and  the 
glasB  plates  ore  prepared  in  a  similar  manner,  the  metal  being  burnt  in,  aa  it  is  termed. 
The  platinum  is  precipitated  from  its  chloride  b;  oil  of  lavender,  the  chloride  being 
ipread  equally  over  the  glaaa  with  a  fine-haired  paint-bntsh.  The  plate  ii  then  placed 
in  a  muffle.  Cheapneaa  is  a  prominent  feature  of  this  prnceia  ;  nbile  all  faaltf  glaesea 
can  be  veiy  eoeil;  repaired,  these  by  the  old  methods  being  thiovn  aeide  an  uselesa.  In 
Paris  the  Uds  of  boxes  and  fancy  articles  aie  largely  manufactured  from  platinised  glaai. 

Boiuiaiiu.  BotUe  glass  includeB  all  kinds  of  glass  made  into  vessels  for  holding 
fioida.  It  is  made  from  cammon  green  glass,  from  fine  white  glass,  and  from 
crystal  glass.  Medicino  botUes,  ka,,  ore  made  from  common  green  glass ;  tumblers, 
or  drinking  glasses,  from  fine  white  glass;  aod  crystal  glasa  is  employed  for  the  same 
arUdes,  bat  selling  at  a  higher  price. 

The  materials  for  ordinary  bottle  glass  are  sand,  potash  oi  soda,  basalt,  &e.  For 
medicine  glass  the  materials  must  be  free  from  iron,  and  still  purer  for  the  artieles 
of  white  glass.  In  the  manufacture  of  bottle  glass  no  considerahle  amount  of  care 
is  required,  the  desiderata  being  strength  and  sufficient  resistance  to  the  action  of 
ordinary  acids.  The  processes  of  meldng  and  annealing  are  conducted  in  the 
ordinary  manner.  The  analyses  of  several  glasses  gave  the  following  results: — 
Silicic  acid    ... 


Potash 


Oidde  of 
Oxide  of 


74  7' 

1574 
877 
043 
014 


74-66 
4-32 


75"94 


7437 


7426 


(2-5« 


Sp.  gr.       a'47  2-48  a-47 

The  details  of  the  several  processes  ot  bottle  glaie  manufacture 
ol  the  rough  shape  ont  of  tough  fluid  glE 


230 


re,  after  the  making 
__    that  only  single  example*  can  l» 

Ken.  We  will  select  the  ordinarywine-bottb. 
e  glasablower,  taking  some  molten  ^»t* 
on  his  pipe,  turns  and  moulds  it  into  tb* 
shape  of  a.  Fig.  139.  By  continued  blowing 
the  englarged  form,  b,  is  obtained  ;  this  timii 
still  more  enlarged,  as  at  e,  is  placed  in  th« 
mould,  d.  The  workman  now  blows  ■haip'j 
into  the  incipient  bottle,  the  glass  Glling  oat 
the  mould  and  producing  the  sbarp  enTTe[oI 
the  shoulder  of  the  wine-bottle.  The  rod  ot 
puntil,  e,  is  now  introduced,  and  a  firm  fooling 
given  by  pressing  in  the  bottom  of  the  bottl*. 
While  the  blower  prepares  a  new  bottle,  the 
assistant  places  that  already  formed  in  the 
annealing  oven.  In  the  making  of  flasks 
and  retorts  the  flask. tongs.  Fig.  140,  an 
employed,  tbe  neck  being  allowed  to  remun 
straight,  as  at  a.  Fig.  141,  to  form  a  flask,  ot 
bent,  as  at  E>,  to  make  a  retort.  The  manu- 
facture of  a  beaker  will  bo  readily  nnderstood 
from  Figs.  142  and  143,  1,  b,  c,  being  the 
method  of  producing  a  globtilBr  body,  and 
•\f  perpeudienlar  sides.  Qlass-tnbing  is  drawn  out  aa  shown  at 
Qlass  rods  are  simitaily  made,  but  without  blowing. 


GLASS, 


283 


praaMdandcoctaiMM.  Pressed  or  cast  glass  comprises  the  many  cheap  glass  orna- 
ments, and,  indeed,  ornamental  glass-work  of  all  kinds,  now  so  general.  The  tall, 
narrow-mouthed  chimney  ornaments  are  thus  made  hy  being  blown  into  engraved 
brass  moulds,  instead  of  into  plain  moulds  as  in  the  case  of  the  bottle.  Cup-shaped 
articles  are  made  with  molten  glass  pressed  between  a  concave  and  convex  surface, 
the  surplus  glass  escaping  at  some  point  purposely  arranged.  As  a  rule  the  objects 
taken  from  the  moulds  require  but  little  polishing. 

Fio.  Z40.  Fio.  141. 


watar.gbus.  £y  water-glass  is  understood  a  soluble  alkaline  silicate.  Its  prepara- 
tion is  effected  by  melting  sand  with  much  alkali,  the  result  being  a  fluid  substance, 
first  observed  by  Von  Helmont,  in  1640. 

Fia.  142.  Fio.  143. 


i 


Fio.  144. 


It  was  made  by  Glauber  in  1648  from  potash  and  silica,  and  by  him  termed 
fluid  ffllica.  Von  Fuchs,  in  1825,*  obtained  what  is  now  known  as  water-glass 
by  treating  silicic  acid  with  an  alkali,  the  result  being  soluble  in  water,  but  not 
affected  by  atmospheric  changes. 

The  various  kind^  of  water-glass  are  known  as — 

Potash  water-glass. 

Soda 

Double 

Fixing 

Potash  water-glass  is  obtained  by  the  melting  together  of  pulverised  quartz  or 
puiifled  quartz  sand  45  parts,  potash  30  parts,  powdered  wood  charcoal  3  parts,  the 
molten  mass  being  dissolved  by  means  of  boiling  in  water.    The  solution  contains 


ft 


tt 


)f 


284  CHEMICAL  TECHNOLOGY, 

much  sulphuret  of  potassium,  which  is  removed  by  boiling  with  oxide  of  copper. 
The  addition  of  carbon  assists  in  reducing  part  of  the  carbonic  acid  to  carbonic 
oxide,  which  disappears  during  the  melting.  Soda  water-glass  is  prepared  with  pul- 
verised quartz  45  parts,  calcined  soda  23  parts,  carbon  3  parts ;  or,  according  to 
Buchner,  with  pulverised  quartz  100  parts,  calcined  Glauber's  salt  60  parts,  and 
carbon  15  to  20  parts.  Double  water-glass  (potash  and  soda  water-glass),  is 
prepared,  according  to  Dobereiner,  by  melting  together  quartz  powder  152  parts,  cal- 
cined soda  54  parts,  potash  70  parts;  according  to  Von  Fuchs,  from  pulverised 
quartz  100  parts,  purified  potash  28  parts,  calcined  soda  22  parts,  powdered  wood 
charcoal  6  parts.      It  is  farther  obtained  by  melting  tartrate  of  potash  and  soda, 

tl^  [  C4H4O6+4H2O,  with  quartz ;  from  equal  molecules  of  nitrate  of  potash  and 

soda  and  quartz ;  from  purified  tartar  and  nitrate  of  soda  and  quartz.  It  is  more 
fusible  than  the  foregoing.    For  technical  purposes  a  mixture  of — 

3  volomes  of  concentrated  potash  water-glass  solution. 
2  „  „  soda  „  „ 

is  employed.  By  the  name  of  fixing  water-glass.  Von  Fuchs  designates  a  mixtnre 
of  silica  well  saturated  with  potash  water-glass  and  a  silicate  of  soda,  obtained  by 
melting  together  3  partfl  of  calcined  soda  with  2  parts  of  pulverised  quartz.  It 
is  used  to  fix  or  render  the  colours  permanent  in  stereochromy. 

That  known  commercially  as  prepared  water-glass  is  obtained  by  boiling  the 
powdered  water-glass  with  water;  and  the  solution,  as  found  in  the  market^ 
is  known  as  of  33°  and  66*",  the  difference  being  that  the  first  100  parts  by 
weight  contain  33  parts  by  weight  of  soM  water-glass  and  67  parts  by  weight  of 
water.  It  therefore  follows  that  in  solutions  of  40°  and  66^  the  water  is  pro- 
portioned as  60  and  34  parts  respectively.  Acids,  with  the  exception  of  carbonic 
acid,  decompose  water-glass  solutions,  separating  the  sUica  as  a  gelatinous  sub- 
stance ;  it  should,  therefore,  be  kept  in  vessels  well  set  apart  from  volatile  acids. 

Water-glass  is  an  important  product  in  industry.  It  is  used  to  render  wood,  linen, 
and  paper  non-inflammable.  The  water-glass  of  33""  is  first  mixed  with  double  its 
amount  by  weight  of  rain-water,  and  is  then  treated  with  some  fire-proof  colouring 
matter,  as  clay,  chalk,  fluor-spar,  felspar,  &c.  The  material  to  be  rendered  unin- 
flammable is  painted  with  the  solution,  and  again  with  another  coat  after  the  first  has 
remained  tweniy-four  hours  to  dry.  Wood  is  thus  preserved  from  being  worm- 
eaten,  from  encrustation  of  fangi,  &c.  Another  industrial  application  of  water- 
glass  is  as  a  cement ;  in  this  it  is  equal  to  lime,  and,  indeed,  is  known  as  "  mineral 
lime."  Chalk  mixed  with  water-glass  forms  a  very  compact  mass,  drying  as  hard  as 
marble ;  no  chemical  change  is  hereby  effected ;  there  is  no  conversion  to  silicate  of 
calcium  or  carbonate  of  potash ;  the  hardening  is  entirely  the  result  of  adhesion. 
Phosphate  of  calcium  treated  with  water-glass  acts  similarly.  Zinc-white  and 
magnesia  lose  none  of  their  useful  properties  when  mixed  with  water-glass. 
Another  important  application  of  water-glass  is  in  the  painting  of  stone  and  concrete 
walls,  and  in  the  preparation  of  artificial  stone.  The  latter,  first  made  by  Hansome, 
is  daily  meeting  with  more  extended  application  in  England,  India,  and  America.  It 
is  prepared  by  mixing  sand  with  silicate  of  soda  to  a  plastic  mass,  which  is  pressed 
into  the  required  shape,  and  then  placed  in  a  solution  of  chloride  of  calcium.  By 
this  means  silicate  of  calcium  is  formed,  and  cements  the  grains  of  sand  together, 
while  the  chloride  of  sodium  is  removed  by  repeated  washings.    As  cement  for  stone. 


0LA8S.  385 

glass,  and  porcelain,  water-glass  is  especially  nsefal.  It  is  also  employed  in  the 
preparation  of  xjloplastic  casts,  made  of  wood  rendered  pnlpy  by  treatment  with 
hydrochloric  acid,  and  afterwards  impregnated  with  water-glass. 

stafMcfaramy.  An  interesting  and  important  application  of  water-glass  is  in  the  new 
art  of  mnral  and  monnmental  painting,  termed  by  Von  Fuchs  Stereochromy  {artpeoQ, 
solids  and  xP^/^>  colour).  In  this  method  of  paintLag  the  water-glass  forms  the 
foundation  or  binding  material  of  the  colour.  There  is  first  to  be  considered 
the  mortar  or  cement  ground  upon  which  the  painting  is  to  be  executed.  This 
gronnd  has  to  receive  an  under-  and  an  over-ground.  It  is  essential,  of  course,  that 
the  fundamental  groundwork  should  be  of  a  stone  or  cement  possessing  every 
reqtdsite  for  durability.  The  next,  or  under-ground,  is  made  with  lime-mortar,  and  is 
allowed  to  remain  for  some  time  to  harden.  When  well  dried  the  water-glass  solu- 
tion is  applied,  and  allowed  to  soak  well  into  the  interstices  of  the  mortar.  After  the 
under-ground  has  been  thus  prepared,  the  over-ground,  or  that  to  receive  the  painting, 
is  laid  on.  This  consists  of  similar  constituents  to  the  under-ground,  with  the 
exception  that  a  good  sharp  sand  is  used,  and  the  mixture  treated  with  a  thin  ley  of 
carbonate  of  lime.  This  over-ground  of  fine  cement  being  nicely  levelled,  and 
having  dried,  it  is  thoroughly  impregnated  with  water-glass.  When  this  is  dry,  the 
painting  is  executed  in  water-colours.  Nothing  further  is  necessary  than  to  fix 
these  colours,  which  is  effected  by  a  treatment  with  a  fixing  water-glass.  The 
colours  employed  are :  -r-  zinc- white,  chrome-green,  chrome-oxide,  cobalt-green, 
chrome-red  (basic  chromate  of  lead),  zinc-yellow,  oxide  of  iron,  sulphuret  of  cad- 
mium, ultramarine,  ochre,  &c.  Vermillion  is  not  employed,  as  it  changes  colour  in 
fixing,  turning  to  a  brown.  Cobalt-ultramarine,  on  the  contrary,  brightens  on  the 
application  of  the  fixing  solution,  and  is,  therefore,  a  very  effective  colour.  As  a 
decorative  art  stereochromy  will  doubtless  attain  great  importance,  the  paintings 
being  unaffected  by  rain,  smoke,  or  change  of  temperature. 

chTvbaoiMi.  Crystal  glass  includes  all  lead-containing  potash  glass.  Crystal 
^ass  was  first  prepared  in  England.  There  are  a  few  difficulties  in  manufacturing 
this  glass.  The  smoke  from  an  anthracite  coal  fire  is  ugurious  to  the  pure  colour  of 
the  glass,  so  that  the  melting-pot  is  provided  with  a  cover ;  but  this  addition  has  the 
disadvantage  that  the  temperature  necessary  to  melt  the  glass  cannot  easily  be 
obtained.  A  larger  proportion  of  alkali  must  therefore  be  added,  which  deteriorates 
from  the  quality  of  the  glass,  rendering  it  liable  to  after-change.  To  prevent  this  as 
much  as  possible  oxide  of  lead  is  used  to  make  the  glass  more  easily  fusible,  and  by 
this  means  a  beautifully  clear,  transparent  glass  results.  The  following  table 
will  give  some  idea  of  the  proportions  of  the  materials : — 


Sand    ... 

■••         •••         ••• 

300 

Potash 

•••         •••         ••• 

100 

Broken  glass 

•••         •••         ••• 

300 

Minium 

•««         •••         ••• 

200 

Sesquioxide  of 

manganese 

045 

Arsenious  acid 

•••     •••     ••• 

060 

The  following  mixture  is  used  in  the  glass  houses  of  Edinburgh  and  Leith : — 

Oclllvl       •••         •••         •••         •••         •••         •••  300 

Jt  otasn         •<•     •••     •••     •••     •••       100 

Minium 150 

Lead-glaze ... ...     ...        50 

And  a  small  quantity  of  sesquioxide  of  manganese  (braunite)  or  arsenious  acid. 


a. 

/*• 

5018 

51-93 

3811 

3328 

ii'6i 

13-67 

o'04 

— 

286  CHEMICAL  TECHNOLOGY, 

To  render  the  glass  fluid,  saltpetre  is  sometimes  added,  bat  in  moderate  ^antitias. 
Dumas  recommends  sand  300,  minium  200,  dry  potash  95  to  100.  On  the  supposi- 
tion that  there  is  no  loss  during  melting,  the  mixtures  contain : — 

Silica        57'4  57 

Oxide  of  lead  ...        363  36 

Potash      63  7 

locro  100 

The  whole  melting  process  is  included  in  i^  to  16  honrsw  The  glass  is  treated  in 
a  manner  similar  to  that  already  described,  but  is  more  easily  worked.  Benrath.  (a) 
and  Faraday  (P),  found  crystal  glass  by  analysis  to  consist  of: — 

Silicic  acid       

Oxide  of  lead 

■trOHtBfl         •*■       •••       ..•       •.• 

Alumina,  &c •. 

9995  9888 

According  to  Benrath  normal  ciystal  glass  has  the  formula  KjoPb^SijeOg^  (t.^., 

5KaO,7PbO,36SiO«). 

PoUflfaing.  Crystal  glass  is  either  oast  in  brass  moulds  or  is  ground.  Its  hardness  admits 
of  its  taking  a  better  polish  than  other  glasses.  The  grinding  wheel  is  of  cast-iron ;  above 
the  periphery  is  fixed  a  yessel  containing  water  and  fine  washed  sand,  which  constantly 
drops  upon  the  wheel,  assisting  in  the  cutting.  The  polishing  wheel  is  of  wood,  well 
serred.with  pumioe-powder  and  water. 

OptieiaoiMtw  The  preparation  of  good  optical  glass,  especially  in  large  dimensioiis, 
is  a  matter  of  much  difficulty.  Transparency,  hardness,  a  high  refractive  power 
with  perfect  achromatism  are  all  required,  and  must  be  obtained  at  the  outlay  of  any 
aonount  of  labour.  The  glass  must  also  be  entirely  homogeneous,  else  the  Hght 
is  not  refracted  regularly ;  threads  and  streaks  (strise)  are  the  results  of  inequality, 
and  it  naturally  follows  that  if  these  appear  to  the  unassisted  eye,  they  will 
seriously  affect  delicate  observations  when  high  magnifying  powers  are  used, 
as  in  telescopes  and  microscopes.  It  is  an  error,  however,  to  suppose  that  these 
irregularities  arise  from  impurities ;  they  are  rather  due  to  interruptions  in  heating 
and  cooling,  or  to  unequally  heating  and  cooling  during  manufacture.  This  must 
especially  be  evident  in  the  case  of  waviness  or  an  undulating  structure  of  the  glass. 
Crown-glass,  free  from  lead,  is  not  so  Kable  to  faults  as  flint-glass;  both  these 
are  employed  for  optical  purposes. 

The  Bev.  Mr.  Haroourt's  experimental  researches  as  to  the  best  optical  glass,  communi- 
cated to  the  British  Association  at  the  recent  meeting  at  Edinburgh,  by  Professor  Stokes, 
show  fully  what  has  been  accomplished  in  preparing  glass  of  this  order.  Mr.  Harcourt*B 
researches  were  chiefly  carried  on  with  phosphates,  combined  in  many  cases  with  fluorides, 
and  sometimes  with  tungstates,  molybdates,  and  titanates,  owing  to  the  difficult  fusibility 
and  pasty  consistency  of  silicate  glasses.  The  experiments  included  glasses  containing 
potassium,  sodium,  lithium,  barium,  strontium,  calcium,  aluminium,  manganese,  magne- 
sium, zinc,  cadmium,  lead,  tin,  nickel,  chromium,  lead,  thallium,  bismuth,  antimony, 
tungsten,  molybdenum,  titanium,  vanadium,  phosphorus,  fluorine,  boron,  and  sulphur. 
The  molybdlc  glasses  first  prepared  were  of  a  somewhat  deep  colour,  deteriorating  with 
age ;  but  at  length  molybdic  glass  was  obtained  free  from  colour  and  permanent. 
Titanic  acid  gave  results  much  superior  to  those  obtained  with  molybdic.  Glass  made 
with  terborate  of  lead  agreed  in  dispersive  power  with  flint-glass ;  while  a  prism  of  this 
glass  extends  the  red  and  blue  ends  of  the  spectrum  equally  with  a  prism  of  one  part  by 


GLASS. 


287 


▼olnme  ol  Blnt-gl&Ba  vith  two  of  crown-glaaB.  Notwithstuidiiig  the  great  difficnltiM 
ariaing  from  stria,  Mr.  Harconrt  finnllj  suooeeded  in  prepajmg  duos  of  terborate  of  lead 
■jid  of  a  titanic  glass,  3  inclieB  in  diameter,  almost  homogeneoTiB. 

It  IB  irell  known  that  flint-  and  crown-glass  form  an  achromalic  combination.  Flint- 
(;1&BB  ia  very  easily  rendered  fluid,  conducing  to  the  formation  of  atriie.  A  Tariation  of 
the  proportions  of  the  constituent  materials,  though  not  producing  effeots  vidble  to  the 
eye  alons,  will  strongly  striate  the  glass,  rendering  it  unflt  for  optic^  purposes.  The  con- 
Btitnents  mnst  be  eqaall;  distiibnted  througbont,  and  thie  is  a  great  difficulty.  The 
oxide  of  lead  being  of  so  mnoh  greater  weight  sinks  to  the  bottom,  while  the  lighter  con< 
Btitnents  float  *t  the  npper  part  of  the  melting  vessel.  Usually  this  is  so  much  the  case 
tbat  glaases  ol  different  specific  gravities  are  obtaiaed  from  the  nppei  and  lower  parts  of 
Uie  melting-pot.  Ltimy  has  lately  employed  thaUium  flint-glass  in  the  preparation  of 
optical  glass,  thallium  taking  the  place  of  potash.    CI.  Winkler  sabatitutes  bismatb  for  the 


Bontemps  mann&cturts  flint  glass  ii 
pared  ol — 

White  Baud    . 


the  following  manner ;- 
106    „ 


-A  glass  mass  ia  pre- 


Carbonat«  of  potassa  ...  43  „ 
and  placed  over  an  anthracite  or  stone-coal  fire  in  a  small  melting  oven,  shown  in 
Fig.  145  in  vertical,  and  in  Fig.  146  in  horizontal  aection.  The  oven  contains  only 
ODS  covered  melting  vessel,  B,  standing  on  the  banli,  \.  a  a  are  the  grate  bars  ;  a 
an  iron  rake,  enclosed  in  a  fire-clay  cylinder,  d,  and  resting  upon  the  roller,  /  After 
about  fourteen  hours  the  mass  becomes  equally  fluid ;  and  a  red-hot  rake  is  introduced 
into  the  vessel  by  which  the  several  layers  of  material  are  intimately  mixed.    In 


Fio.  146. 


about  £ve  minutes  the  mass  is  sufficiently  stirred ;  the  iron  rod  is  then  removed,  the 
clay  cylinder  remaining.  This  stirring  is  effected  several  times  without  removing 
the  clay  cylinder;  and  the  glass  is  tlien  ready  for  blowing  or  casting.  But  for 
optical  purposes  it  is,  after  the  removal  of  the  clay  cylinder,  allowed  to  cool  gradually 
during  eifjht  days  in  an  annealing  oven.     The  most  perfect  pieces  of  glass  are  then 


288  CHEMICAL  TECHNOLOGY. 

cut  from  the  interior  of  the  mass.     According  to  Damasks  analysis  of  a  earn; 
obtained  from  Guinand,  flint-glass  consists  of — 

OXJ-LCHi  •••        •••        •«•        •••        •••        •<•  42  3 

Oxide  of  lead    435 

I  i  1 1 1 1"  •••  •••  •••  •••  •••  •••    ^3 

JrOmBll  •••       •••       •••        •••       •■•  XX7 

Alumina,  oxide  of  iron,  and) 

protoxide  of  manganese    )         ^ 

lOO'O 

The  second  kind  of  optical  glass,  crown-glass  free  from  lead,  contains,  according 
to  Bontemps: — Sand,  120;  potash,  35;  soda,  20;  chalk,  15;  and  arsenious  acid, 
I  part. 

Btnai.  The  imitation  of  precious  stones  is  an  interesting  feature  of  glass  manu- 
facture, and  in  Egypt  and  Greece  it  is  an  art  that  has  attained  to  great  perfection. 
All  precious  stones,  with  the  solitary  exception  of  the  opal,  can  be  imitated 
artificially.  The  chief  constituent  of  these  artificial  gems  is  strasSj  or  as  it  tenned 
by  Fontanier,  Mayence  base ;  and  in  France  artificial  gems  are  mostly  known  ae 
Pierres  de  Strass.  This  base,  then,  is  colourless,  and  may  be  considered  as  a  boro- 
silicate  of  the  alkalies  containing  oxide  of  lead,  this  being  in  larger  proportion  than 
in  flint-glass. 

Donault-Wieland  found  colourless  strass  by  analysis  to  consist  of: — 


f!)lllCft        •••       •••       ••• 

••• 

381 

Alumina 

••• 

10 

Oxide  of  lead 

•  •  • 

530 

Potash    

••• 

7-9 

Borax                ^ 
Arsenious  acid  >     '" 

••  • 

traces 

1000 
This  analysis  gives  the  formula — 

(3KaO,6SiOa)  +3  (3PbO,6SiOa) . 

The  various  gems  are  imitated  by  the  addition  of  colouring  oxides,  the  whole  of 
the  materials  being  ground  to  a  fine  powder,  intimately  mixed,  and  melted  at  a 
strong  heat.  The  imitation  of  the  topaz  is  obtained  by  taking — strass,  1000; 
antimony,  40 ;  and  Cassius's  purple,  i  part.  The  topaz  can  also  be  imitated  with— 
strass,  1000 ;  oxide  of  iron,  i  part.  The  imitation  ruby  is  obtained  with  i  part  of 
the  topaz  paste,  and  8  parts  of  strass,  the  whole  being  melted  together  for  thirty 
hours.  A  ruby  of  less  beauty  is  obtained  with — strass,  1000 ;  peroxide  of  man- 
ganese, 5  parts.  A  good  emerald  can  be  prepared  from — strass,  1000;  oxide  of 
copper,  8;  oxide  of  chromium,  02  parts.  The  sapphire  is  obtained  from 
strass,  1000 ;  pure  oxide  of  cobalt,  15  parts.  The  amethyst  from — strass, 
1000 ;  peroxide  of  manganese,  8 ;  oxide  of  cobalt,  5 ;  Casaius*s  purple,  02. 
The  beryl  or  aqua  marina  is  imitated  by — strass,  1000;  glass  of  antimony,  7; 
oxide  of  cobalt,  0*4.  The  carbuncle  by — strass,  1000;  glass  of*  antimony,  500; 
purple  of  Gassius,  4;  peroxide  of  manganese,  4  parts.  Much  attention  has  not 
been  paid  to  the  mode  in  which  the  colouring  is  effected  by  the  metallitf 
oxides;     nor   have    experiments    been    tried    with    any    definite   result  as  to 


0LA8S.  289 

the  application  of  tnngstic  acid,  molybdic  acid»  titanic  acid,  cliromic  acid,  and  prot- 
oxide of  chromium,  &c. 

^wSJluSSal!**  Coloured  glass  may  be  considered  in  two  classes — that  coloured  as 
a  whole,  and  that  only  partially  coloured.  The  latter  is  prepared  with  such 
metallic  oxides  as  will  impart  to  the  glass  very  intense  colour ;  for  instance,  prot- 
oxide of  copper,  protoxide  of  cobalt,  oxide  of  gold,  and  oxide  of  manganese.  This 
kind  of  glass  is  termed  superfine,  and  is  prepared  in  the  following  manner : — Two 
melting yessels  are  placed  in  the  oven;  one  contains  a  lead-glass,  the  other  the 
coloured  glass.  We  will  take  as  an  example  glass  coloured  red  with  protoxide  of 
copper,  which  if  further  oxidised  imparts  a  green  colour  to  the  glass.  The  glass- 
blower  dips  his  pipe  first  into  the  red  glass,  and  collects  a  sufficient  quantity  to  blow; 
then  he  dips  this  into  the  white  glass,  and  proceeds  to  form  a  cylinder  or  roll,  as  in 
the  making  of  table  glass.  Superfine  glass  is  known  as  "  outside  "  and  "  double," 
or  ''  double  layer."  In  the  first  case  the  workman  takes  a  lump  of  white  glass  upon 
his  pipe  and  covers  it  with  the  coloured  glass  ;  or,  in  the  second  case,  he  takes  up 
only  a  small  quantity  of  white  glass,  then  sufficient  of  the  coloured  glass,  and  again 
more  white  glass.  Red  glass  may  be  obtained  with  either  Oassius's  purple,  protoxide 
of  copper,  or  oxide  of  iron  as  the  colouring  ingredient.  Cassius's  purple  is  used 
chiefly  for  ruby-red  glass.  It  was  long  thought  that  ruby-coloured  glass  could  not 
be  obtained  with  any  other  preparation  than  Cassius's  purple,  but  twenty-five  years 
ago  Fuss  showed  that  chloride  of  gold  was  effectual.  If  glass  containing  salts  of 
gold  or  protoxide  of  copper  is  cooled  suddenly,  the  colour  disappears ;  then  if  again 
gently  warmed,  not  quite  to  softness,  the  colour  suddenly  reappears  in  full  splendour. 
This  phenomenon  occurs  equally  in  atmospheres  of  oxygen,  hydrogen,  and  carbonio 
add.  In  the  preparation  of  protoxide  of  copper  glass,  lead-glass  is  taken  as  a  basis, 
to  which  3  per  cent  of  the  protoxide  is  proportioned.  The  drawback  to  the  employ- 
ment of  the  protoxide  is  the  readiness  with  which  it  becomes  oxide,  this  imparting 
a  green  colour  to  the  glass.  To  prevent  this  change  iron  filings,  rust,  or  tartar  is. 
added,  or  the  glass  is  stirred  with  green  wood.  Copper-glass,  as  has  just  been  said, 
is  colourless  on  cooling,  regaining  its  colour  during  the  process  of  annealing.  Oxide 
of  iron,  known  oommercially  as  blood-stone,  ochre,  or  red  chalk,  is  also  used  to 
impart  a  red  colour.  Yellow  and  topaz-yellow  are  obtained  by  means  ef  antimoniate 
of  potash  or  glass  of  antimony,  chloride  of  silver,  borate  of  oxide  of  silver,  and  by 
Bolphuret  of  silver.  Oxide  of  uranium  imparts  a  green-yellow.  Blue  is  obtained 
from  oxide  of  cobalt,  more  seldom  by  means  of  oxide  of  copper.  Green  results 
from  the  addition  of  chrome-oxide,  oxide  of  copper,  and  protoxide  of  iron.  Violet 
IS  obtained  from  oxide  of  numganese  (brannite)  and  saltpetre ;  black,  from  a  mixture 
of  protoxide  of  iron,  oxide  of  copper,  braunite,  and  protoxide  of  cobalt.  A  beautiful 
Uack  results  from  sesquioxide  of  iridium. 

eiMiMiiii]«.  The  delineation  of  figures  and  scriptural  events  in  coloured  glass 
dates  from  a  very  remote  period.  At  first  the  work  was  merely  mosaic,  pieces  of 
coloured  glass  being  inserted  in  leaden  firamework.  Glass  painting  was  known  in 
^^cnnany  in  the  middle  ages,  and  soon  extended  throughout  Europe.1  :Tn  the  13th 
century,  when  Gothic  architecture  became  prevalent,  glass  painting  also  became 
Biore  general,  as  until  then  the  heavy,  round-arched  windows  were  too  small  to 
admit  of  ornament.  But  it  was  not  until  the  15th  century  that  the  heavy  outlined 
fignres  were  discarded  for  the  more  mingled  colours  of  heraldic  de\'ice,  as  seen  ia 

« 

u 


290  CHEMICAL   TECHNOLOGY, 

the  churches  of  SebalduB  and  Lorenz,  of  Nuremburg,  in  the  prodtlctionB  of  the 
celebrated  Hirschvogel  family.  This  style  lasted  till  the  i6th  centnry,  when  the 
glass-maker  tried  the  effect  of  pigments  upon  glass.  Since  that  time  the  art  has 
gradually  improved,  the  improvement  at  first  being  most  manifest  in  France  and  the 
Netherlands. 

The  nature  of  glass-painting  or  staining  is  in  principle  the  following : — ^When  coloiured 
glass,  rendered  easily  fusible  by  the  metallic  oxide  it  contains,  is  finely  pulverised,  and 
laid  upon  a  plain  glass  surface  and  heated,  it  forms  a  skin,  or  *'  flash/*  as  it  is 
termed,  this  skin  or  layer  of  glass  being  said  to  be  **  flashed  on."  It  is  evident  that 
very  brilliant  effects  may  thus  be  attained.  The  near  surface  of  the  glass  receives 
the  strong  shades  and  colours,  the  other  or  distant  surface  the  lighter  tints.  White 
was  not  employed  in  the  older  glass  paintings,  but  is  now  used  in  the  flesh-tints, 
pure  white  effects,  &c.  Oxide  of  tin  and  antimoniate  of  potash  yield  a  good  white. 
For  yellow,  Naples-yellow,  or  antimony -yellow,  or  a  mixture  of  the  oxides  of  iron, 
tin,  and  antimony,  or  of  antimonic  acid  and  oxide  of  iron,  of  sulphuret  of  silver  and 
sulphuret  of  antimony,  or  chloride  of  silver  is  used ;  for  red,  oxide  of  iron,  purple  of 
Gassius,  and  a  mixture  of  oxide  of  gold,  oxide  of  tin,  and  chloride  of  silver;  for 
brown,  oxide  of  manganese,  yellow  ochre,  umber,  and  chromate  of  iron ;  for  black, 
oxide  of  iridium,  oxide  of  platinum,  oxide  of  cobalt,  and  oxide  of  manganese ;  for 
blue,  oxide  of  cobalt,  or  potassium-cobalt  nitrate ;  for  green,  the  oxides  of  chromium 
and  copper.  Two  kinds  of  colours  are  distinguished,  the  hard  and  the  soft.  The 
soft  are  called  varnish  colours,  are  not  very  easily  fluid,  forming  a  kind  of  glaze  upon 
the  glass.  These  colours  are  placed  upon  the  outer  surface.  The  hard  or  decided 
tints  are  semi-opaque,  and  are  placed  upon  the  inner  surface  of  the  glass.  The 
binding  fluid  or  vehicle  is  a  mixture  of  silica,  minium,  and  borax,  with  which  the 
colour,  being  previously  ground  to  a  fine  powder,  is  intimately  mixed.  This  mixture 
is  painted  on  the  glass  with  a  pencil,  and  the  glass  plate  is  afterwards  fired  in  a 
muffle.  Becently  volatile  oils  have  been  employed  as  a  vehicle,  viz.,  oil  of  turpen- 
tine, lavender,  bergamot,  and  cloves.  The  buming-in,  or  firing,  the  colours  was 
fonnerly  effected  by  placing  the  glass  tablet  with  dried  and  pulverised  lime  in  aa 
iron  pan  raised  to  a  red  heat.  But  recently  the  muffle  oven  has  been  employed. 
The  bottom  of  the  muffle  is  covered  to  a  depth  of  one  inch  with  dry  powdered  lime, 
upon  which  the  plate  of  glass  is  laid,  and  again  a  layer  of  hme.  The  oven  is  then 
raised  equally  to  a  dark  red  heat.  After  six  to  seven  hours  the  fire  is  gradually 
withdrawn,  and  the  oven  allowed  to  cool.  The  glass  is  taken  out,  cleansed  with 
warm  water,  and  dried. 

'^bLte?^!^^  ^7  enamel  is  understood  in.  glass  manufacture  a  coloured  or 
colourless  glass  mass  rendered  opaque  by  the  addition  of  oxide  of  tin.  It  formerly  wu 
prepared  in  the  following  manner : — An  alloy  of  15  to  1 8  parts  tin  and  100  parts  lead 
was  oxidised  by  heat  in  a  stream  of  air,  the  oxide  pulverised  and  washed.  The 
mixture  of  the  oxides  was  then  fritted  with  the  glass.  An  enamel-like  appearance 
is  imparted  to  glass  by  arsenious  acid,  chloride  of  silver,  phosphate  of  calcium, 
cryolite,  fluor-spar,  aluminate  of  soda,  and  precipitated  sulphate  of  barium.  Bone 
glass,  so-called,  is  a  milk-white,  semi-opaque  glass,  containing  phosphate  of  calciom 
in  the  shape  of  white  bone-ash,  8ombrerite,or  phosphorite.  It  is  employed  for  lamp- 
globes  and  shades,  thermometer-scales,  &c.  It  is  made  by  adding  to  white  glass 
about  10  to  20  per  cent  of  white  bone-ash,  or  a  corresponding  quantity  of  mineral 
phosphate.    After  melting  the  glass  is  generally  clear  and  transparent,  becoming 


GLASS*  291 

milk-white  and  opaque  during  the  process  of  blowing.  The  colour  is  finally 
developed  during  annealing.  A  similar  glass  to  the  preceding  is  alabaster  glass,  but 
the  latter  is  more  opaque.  It  is  also  termed  opal  glass,  rice  glass,  or  rice-stone 
C^lass,  and  Reaumur's  porcelain.  The  materials  are  the  same  as  in  the  preparation  of 
crystal  glass,  of  which  it  may  be  considered  the  scum  or  underlayer  of  impurities, 
though  it  is  really  imperfectly  prepared  crystal  glass. 

ciyoiito  oLua.      Cryolite  glass,  or  hot-cast  porcelain,  has  recently  been  manufactured 
in  Pittsburg.    It  is  a  milk-white  glass,  obtained  by  melting  together 

Silica ^7*^9  P^^  cent 

Cryolite ...     23*84 

Oxide  of  zinc     897 

Flnor-spar  or  aluminate  of  sodium  may  be  substituted  for  cryolite.    Benrath  found 
(1869)  in  such  a  milk  glass — 

Silica  ...     70*01  per  cent 

Alumina     1078 

OOCUI   ...       ...       ...       •••         ...       •••       ...       XQ  21 


>>         ft 
»»        If 


lOO'OO 

iM  oiMi.  loe  glass  is  made  by  plunging  the  mass  of  glass  attached  to  the  end  of  the 
Uower's  pipe,  still  at  a  glowing  red-heat,  into  hot  water,  in  which  the  glass  is  opened 
and  blown  out.  It  then  resembles  a  mass  of  thawed  ice,  with  a  beautifnlly  pellucid 
appearance.  It  is  also  known  as  crackle-glass ;  in  France,  as  verre  craquete.  Agate  glass 
is  obtained  by  melting  together  the  waste  pieces  of  coloured  glass. 

Hinatinan.  AstnUte.  This  Is  a  glass  resembUng  that  found  in  the  Pompeiian  excaTations, 
and  mentioned  by  Pliny.  It  possesses  a  beautiful  red  colour,  between  that  of  yermillion 
and  of  minimn,  is  opaque,  harder  than  ordinary  glass,  bears  a  high  polish,  and  has  a 
Bp.  gr.  =  3*5.  The  colour  is  lost  by  melting,  and  by  no  addition  can  be  recovered.  The 
glass  contains  no  tin  or  protoxide  of  copper  as  a  colouring  matter.  Von  Pettenkofer 
assimilated  to  this  glass  by  melting  together  silica,  lime,  burnt  magnesia,  litharge^ 
soda,  oopper-hammerings,  and  smithy  scales.  A  part  of  the  silica  in  the  mixture  is  decom- 
posed by  means  of  boracic  acid,  and  amass  is  obtained  which,  when  ground  and  polished, 
exhibits  a  dark  red  colour  of  great  beauty.  Pettenkofer  gave  to  this  glass  the  term 
astralite,  from  the  beautiful  shotte-colour  of  blue  or  dichromatic  tint  shimmering  through- 
out the  mass. 

ATutuiin  oiMi.  Ayenturin  or  avanturin  glass  was  formerly  made  only  in  the  Island  of 
Murano,  near  Venice,  but  is  now  prepared  throughout  Oermany,  Italy,  Austria,  and 
Prance.  It  is  a  brown  glass  mass  in  which  crystalline  spangles  of  metallic  copper 
according  to  Wohler  (of  protoxide  of  copper  according  to  Von  Pettenkofer)  appear 
dispersed.  Fremy  and  Glemandot  have  produced  a  glass  similar  to  aventurin  glass,  and 
which  consisted  of  300  parts  glass,  40  parts  protoxide  of  copper,  and  Sopai'ts  copper-scale. 
The  Bayarian  and  Bohemian  glass  nouses  produce  an  ayenturin  glass  rivalling  the 
original.  Von  Pettenkofer  has  prepared  aventurin  glass  direct  from  haBmatinon  by  mixing 
sufficient  iron -filings  with  the  molten  mass  to  reduce  about  half  the  copper  contained. 
Pettenkofer  surmises,  and  with  good  reason,  that  aventurin  gi&BS  is  a  mixture  of  green 
protoxide  of  copper  glass  with  red  orystiUs  of  silicate  of  protoxide  of  copper,  these  comple- 
mentary colours  giving  the  brown  tint.  This  glass  is  also  well  imitated  by  melting  a 
mixture  of  equal  parts  of  the  protoxides  of  iron  and  copper  with  a  glass  mass.  The  protoxide 
of  copper  appears  after  a  long  annealing  as  a  separate,  crystalline,  red  combination, 
while  the  protoxide  of  iron  is  lost  in  the  green  colour  it  imparts  to  the  glass.  Pelouze 
found  that  by  freely  adding  chromate  of  potash  to  the  glass  materials  spangles  of  ofide  of 
chromium  were  separated.  He  termed  this  glass  chrome-aventurin ;  it  has  been 
employed  by  A.  Wachter  in  the  glazing  of  porcelain. 

oiMa  BaUef.  Glass  relief  is  obtained  by  enclosing  a  body  of  well-bumt  unglazed  white 
clay,  moulded  to  the  required  form  between  layers  of  lead-glass,  the  result  being  similar 
in  appearance  to  an  article  in  matted  silver.  Gold  matte  is  imitated  by  employing  a  yellow 
glass.  This  branch  of  their  art  has  been  known  to  the  Bohemian  glass  manufacturers  for 
upwards  of  eighty  years. 

u  2 


aga  CHEMICAL  TECHNOLOGY. 

ni'ffre«,orR«ueai*tod       ^7  ^^'^  OT  filigree  [glass  is  understood  that  kind  of  glass  work 
Qijus.  formed  of  Tarion^y  [coloared  or  white  opaque  glass  threads,  these 

threads  being  sometimes  as  fine  as  a  single  hair.  They  axe  generally  drawn  out  from 
tubes  or  sticks  of  glass  of  various  colours,  heated  to  redness,  and  formed  into  sticks,  tubes, 
or  spirals.  Two  of  these  tubes  are  taken,  placed  together,  and  blown  out  into  a  vessel  of 
the  required  form,  which  is  characterised  by  the  conformation  of  the  glass  threads  in  the 
stick.  From  the  spiral  network  thus  formed  this  kind  of  glass  is  sometimes  termed 
reticulated. 

Miiuflore  Work.  Millifiorc  work  is  a^peculiar  form  of  mosaic  glass  work,  in  preparation 
similar  to  that  of  Petinet  glass.  Small  filigree  canes  of  different  coloured  glass  are  placed 
side  by  side  to  form  a  thick  cord  or  column,  the  cross  section  of  which  appears  of  a  parti- 
coloured grain.  These  cords  or  columns  can  be  twisted  to  almost  any  required  form,  or 
when  heated  and  drawn  out  the  glass  threads  of  various  colours  of  which  it  is  composed 
form  a  single  thread  of  very  varied  hue  and  great  beauty.  These  threads  again  can  be 
worked  into  ornaments,  or  formed  into  lumps  or  balls.  The  best  kind  of  milUfiore  work 
are  the  paper-weights,  often  sold  at  fancy  bazaars  as  Bohemian  glass  weights — these  are 
merely  lumps  or  roUs  of  the  many  coloured  glass  thread  placed  together,  heated,  and 
finally  coated  with  a  film  of  clear  white  glass  by  being  for  a  few  moments  held  in  the 
white  glass  melting-pot. 

GiMB  Pearls.  There  are  two  kinds  of  artificial  or  glass  pearls,  namely,  solid  or  massive 
pearls  and  blown  pearls.  The  first  are  known  as  Venetian  pearls,  and  those  made  in 
Venice  are  preferred,  the  export  from  this  city  in  1868  representiug  a  money  value  of 
7,755,000  francs.  The  manufacture  is  chiefly  carried  on  in  the  Island  of  Murano.  The 
pearls  are  made  from  small  glass  tubes,  either  white  or  coloured.  Oxide  of  tin  is  employed 
in  the  preparation  as  well  as  the  various  metallic  oxides  for  imparting  the  desired  colours. 

Solid  Pearls.  The  glass  tubes  are  cut  into  small  pieces  or  cylinders.  The  sharp  edges  ol 
these  cylinders  are  removed  by  placing  them  in  an  iron  vessel  brought  to  a  red  heat, 
the  beads  being  constanly  stirred  with  an  iron  spoon.  Previous  to  this  operation  ihs 
interior  or  hollows  of  the  beads  are  filled  with  powdered  charcoaL  They  are  then 
well  washed,  dried,  and  packed.  By  another  mode  of  preparation  the  pieces  of  ^aas 
tubing  are  placed  in  a  revolving  vessel  similar  to  a  coffee-roaster.  The  finished  pearls 
are  generally  strung,  the  charcoal  being  placed  in  the  interior  or  tube  of  the  bead  to 
prevent  its  closing. 

Blown  Pearls.  The  preparation  of  blown  pearls  is  quite  a  distinct  manufacture.  They 
resemble  the  real  pearl  in  form,  colour,  and  surface.  Jaquia,  a  French  paternoster  or 
rosary  maker,  in  the  year  1656,  remarked  that  when  whitings  {Cyprintu  aUmmus,  dbUtte$) 
were  washed  with  water,  a  residue  remained  consisting  of  a  beautiful  pearJiy  subsianee. 
This  was  the  foundation  of  the  manufacture  of  the  artificial  pearl.  Jaquin  scaled  the 
fish,  mixed  the  scales  with  water,  and  obtained  the  celebrated  **  Oriental  pewl^stence"  or 
** Essence  d* Orient"  a  substance  identical  with  Gmmin.  A  small  bead  of  gypsom or 
other  hardening  paste  is  coated  with  this  mixture,  dried,  and  dipped  into  molten  glass,  a 
thin  film  of  which  adheres. 

The  pearl  is  sometimes  Tound,  sometimes  pear-shaped,  or  flat.  Another  method  of 
preparing  the  pearls  is  by  means  of  beads  blown  from  glass  tubes  of  various  thicknesses. 
These  beads  or  small  bulbs  are  then  filled  with  pearl-essence.  To  prepare  this  essence, 
say  a  quantity  of  120  grms.,  4000  fish  are  necessary;  thus  a  pound  of  pearl-essence 
requires  18,000  to  20,000  fish  for  its  preparation.  The  scales  are  allowed  to  stand  about 
an  hour  in  water  to  permit  the  slimy  matter  adhering  to  them  to  settle  ;  they  are  rubbed 
down  in  a  mortar  with  fresh  water,  and  strained  through  a  linen  cloth.  Thus  prepared 
the  paste  is  ready  for  insertion  in  the  glass  beads,  a  little  ammonia  being  added  to  prevent 
decay. 

HTtfiograpby.  Hyalography,  or  the  art  of  etching  on  glass,  is  due  to  one  Heinridi 
Sohwankhardt  or  Schwandard,  an  artist  living  at  Nuremburg  in  1670.  It  oonsists  of  the 
following  operations  :— Powdered  fluor-spar  is  treated  with  concentrated  sulphuric  add  in 
a  leaden  vessel ;  gentle  heat  is  applied,  the  vessel  being  covered  vdth  the  glass  plate  to  bs 
etched  coated  with  wax,  through  which  the  design  is  traced  with  a  steel  etching-needle. 
Vapours  of  hydrofluoric  acid  (FIH)  are  evolved,  which  combine  with  the  silica  of  the 
glass,* forming  fluoride  of  silicon,  SiFl^,  and  volatilising.  The  plate  is  afterwards  washed 
with  warm  oil  of  turpentine.  The  first  practical  application  is  due  to  Hann,  of  Warsav, 
in  1829.  More  recently,  Bottger  and  Bromeis,  with  Auer,  of  Vienna,  have  improved  the 
processes.  The  etching-ground  used  for  engraving  on  metallic  surfaces  would  not  in  this 
ease  give  favourable  results.  Piil  recommends  a  molten  mixture  of  i  part  asphalt  and 
I  part  colophonium,  with  so  much  oil  of  turpentine  as  will  bring  the  mass  to  the  oon- 
fiistency  of  a  syrup.  Etched  glass  plates  have  been  used  by  Bottger  and  Bromeis  to  print 
from  instead  of  steel  and  copper.    In  the  press  the  glass  plate  is  backed  by  a  cast-iron 


EARTHENWARE.  293 

plate.  The  proeesB,  however,  has  not  been  practically  snocessfal ;  it  is  better  snited  to 
the  production  of  bank-notes,  &c.,  than  engravings,  the  resulting  etchings  being  hard  in 
tone.  Bat  for  purposes  of  decoration,  etched  glass  is  largely  used.  By  the  method  of 
Tessid  du  Motay  and  Mar^chal  of  Metz,  a  bath  is  made  of  250  grms.  of  hydrofluoride  or 
fluoride  of  potassium,  i  litre  of  water,  and  250  grms.  of  ordinary  hydrochloric  acid. 
Kesaler  employs  a  solution  of  fluoride  of  ammonium. 


Cebamio  or  Eabthenware  Manufacture. 

*^^"*pS£rf  "**'*^        To  the  most  important  alumina  combinations  found  nativ* 
belongs  felspar.    This  mineral  is  one  of  the  chief  members  of  the  class  containing 

gneiss,  granite,  and  porphyry.    Potash-felspar,  liW^8»  ^^^  es^' parts  of  silica* 

18  alumina,  and  i6'6  potash,  is  also  known  as  ortJioclase  or  advlaria;  when 
sodium  takes  the  place  of  potassium,  the  felspar  alhite  is  formed.  According  to 
Mitscherlich  some  felspars  contain  0*4  to  2*25  per  cent  of  barium.  When  felspar  is 
under  the  influence  of  water  and  carbonic  acid  with  changes  of  temperature,  it  loses 
its  silicate  of  potash,  which  being  washed  out,  the  potash  is  taken  up  by  plants,  and 
will  perhaps  account  for  some  portion  of  the  potash  always  present  in  their  ash  ; 
some  of  the  silicate  is  acted  upon  by  carbonic  acid,  by  which  the  silicic  acid  is  sepa- 
rated and  soluble  carbonate  of  potash  formed.  In  following  this  decomposition  to  a 
conclusion,  we  may  surmise  that  the  silicic  acid  thus  set  free  becomes  a  constituent 
of  the  opal  and  chalcedony  spar.  All  clays  are  essentially  silicate  of  alumina ;  and 
in  many  instances,  as  in  Devonshire  and  Cornwall,  the  change  from  felspar  of  the 
fine  white  granite  to  clay  by  disintegration  is  very  perceptible.  By  washing  this 
clay  to  free  it  from  quartz  and  mica  a  fine  white  clay  is  obtained,  known  as  kaolin  or 
KMiia.  or  pozeeuin  otay.  porcelain  clay.  Again,  by  washing  with  potash  ley,  whereby  the 
free  silica  is  taken  up,  there  is  obtained,  in  most  cases,  a  fine  plastic  mass,  consisting 
of  I  molecule  of  alumina,  i  molecule  of  silica,  and  2  molecules  of  water.  The 
quantity  of  free  silicic  acid  varies  between  ito  14  per  cent. 
The  weathering  of  the  felspar  may  be  formulated  thus — 

I  mol.  felspar,  SisOsKAl,  or  \^  \  Os, 
gives,  under  the  influence  of  water, 

I  mol.  porcelain  clay,  2SiOAHAl,  and 
I     „    acid  silicate  of  potash, 

the  latter  forming  a  soluble  combination  similar  to  water-glass.  Porcelain  day  occurs  in 
the  following  localities: — i.  Bavaria:  Aschaffenburg,  StoUberg,  Diendorf,  Oberedsdori. 
2.  Prussia :  Mori  and  Trotha,  near  Halle  (material  for  Berlin  porcelain  manufacture — 
decomposed  or  disintegrated  porphyry).  3.  Saxony:  near  Sohneeberg  and  Mionia. 
The  first  is  a  weathered  granite ;  the  latter,  porphyry.  4.  Eastern  Hungaiy : 
Brenditz  in  Moravia;  near  Carlsbad,  Bohemia;  Prinzdorf  in  Hungary.  5.  France: 
St.  Trieux,  near  Limoges.  6.  England :  St.  Austell,  in  Cornwall.  Weathered  granite ; 
a  mixture  of  orthoclase  and  quartz.  It  is  found  chiefly  on  Tregoning  Hill,  near  Helstone. 
7.  China.  It  naturally  follows  that  the  clay  should  contain  foreign  substances ;  and  it  is 
from  the  quality  and  quantity  of  these  substances  that  the  several  varieties  of  clay  are 
obtained,  of  course  with  due  reference  to  the  chief  constituents — silicic  acid  and  alumina^ 
The  purer  clays  contain  generally  the  following  foreign  substances: — Sand,  partly  aa 
quartz  sand,  as  silicate  of  potash,  and  partly  as  particles  or  fragments  of  undeoomposed 
minerals ;  baryta  combinations ;  carbonate  of  magnesium ;  carbonate  of  calcium  ;  oxide  of 
iron ;  sulphur  pyrites ;  and  organic  matter. 

njTjgricjnjiMj^      For  the  technical  appUcation  of  the  clays  the  important 
qualities  are  colour,  plasticity,  and  well  hardening  under  heat. 


294  CHEMICAL  TECHNOLOGY. 

Colour.  Naturally  clays  are  white,  yellow,  blue,  or  green.  Pure  clay  is  white; 
coloured  clays  are  the  result  of  several  admixtures.  White  clay  contams  but  a  small 
quantity  of  protoxide  of  iron,  and  becomes  after  burning  yellow  or  red ;  these  oolours 
originating  from  the  organic  substances  disappear  on  their  being  volatilised  after 
many  firings.  The  coloured  days  change  their  colour  during  firing,  becoming 
red  or  red-yellow.  Fine  clays  are  prepared  only  from  those  becoming  white  hj 
continued  burning. 

Fiastieity.  The  clay  should  absorb  water  readily,  forming  a  tenacious  mass,  capable 
of  taking  sharp  and  clear  impressions.  It  is  clear  that  the  plasticity  of  the  claya 
depends  in  a  great  measure  on  their  composition.  Sand  is  the  constituent  most 
prejudicial  to  plasticity,  lime  less^o,  and  oxide  of  iron  least  of  all.  Clay  pos- 
sessing a  high  degree  of  plasticity  is  said  to  he  fat  or  long^  and  when  in  the  opposite 
condition  lean,  thin,  or  sJiort.  All  shrunk  clays,  that  is,  all  days  decreased  in  volume 
by  burning,  are  said  to  be  either  drawn  or  burst.  The  amount  of  shrinkage  depends 
of  course  upon  the  quantity  of  water  the  clay  contains ;  the  same  kind  of  day  does 
not  always  exhibit  the  same  shrinkage.  Fat  clays  shrink  more  than  short  clays. 
The  diminution  in  surface  by  shrinkage  varies  between  14  and  31  per  cent,  the 
capacity  or  solid  contents  between  20  and  43  per  cent.  Clay  may  be  burnt  so  hard 
AS  to  give  sparks  when  struck  with  steel ;  but  its  property  to  form  a  plastic  mass 
with  water  is  then  wholly  lost.  Pure  day  (silicate  of  alumina)  is  by  itself  infusible, 
but  by  mixture  with  lime,  oxide  of  iron,  and  other  bases  becomes  more  or  less 
easily  fusible.  According  to  the  experiments  of  E.  Eichters  (1868)  the  refractory 
qualities  of  clay  are  least  influenced  by  magnesia,  more  so  by  lime,  still  more  by  oxide 
of  iron,  and  most  by  potash.  Fusible  clay  obviously  is  not  adapted  to  the  mana- 
fjB.cture  of  porcelain  or  such  ware  as  is  likely  to  be  exposed  to  a  high  temperature. 
A  fusible  and  a  refractory  clay,  when  heated  together,  ^ter  into  a  mass  that  does 
not  cleave  to  the  tongue.  By  the  manufacture  of  clay  ware,  then,  is  understood  the 
binding  of  certain  clays  together  by  means  of  a  suitable  flux. 

L  Kindt  of  Clay.      The  clays  employed  in  ceramic  manufacture  are — 

1.  Eefractory  clays ;  as  porcelain  and  plastic  clays. 

2.  Fusible  clays ;  as  potter's  clay. 

3.  Limey  clays;  as  marl,  loam. 

4.  Ochre  days ;  as  ruddle,  ochre. 

Of  these  porcelain  clay  is  the  most  important;  it  is  of  various  cdours,  very 
tenacious,  plastic  to  a  high  degree,  bums  white,  and  is  not  fusible  in  a  porcelain- 
oven  fire.  It  is  ordinarily  found  in  the  tertiary  formation,  almost  always  accompa- 
nied by  other  kinds  of  clay,  by  quartz-sand,  and  by  brown  coal.  For  practical 
purposes  it  is  important  to  know  that  days  of  the  same  strata  and  of  the  same 
pit  often  difler  largely  in  their  refractory  property.  This  is  not  only  the  result  of 
experience,  but  of  a  lengthy  series  of  experiments  made  by  C.  Bischof,  Otto,  and 
Th.  Richters.  The  strata  near  Elingenberg-on-the-Maine,  at  Coblenz,  Cdogne, 
Lautersheim,  and  Vallendar-on-the-Bhine,  Weisboch  in  Baden,  Bunzlau  in  Silesia, 
Schwarzenfeld  near  Schwandorf,  and  Kemnath  in  Bavaria,  in  the  province  of 
Hessen,  in  Saxony,  in  Belgium,  near  Dreux  in  France,  and  Devonshire  and  Stour- 
bridge in  this  country,  are  all  celebrated  for  this  day.  The  following  analyses  gi^ 
the  composition  of  various  refractory  clays : — 


EARTHENWARE.  995 

I                   3.                    3.                  4.  5. 

S^<5a          4750  4579  5300  63-30  5550 

Alumina    34*37  2810  27-00  23*30  2775 

Lime 0*50             2*00              1*25  073  0*67 

Magnesia 100               —                —  —  075 

Oxide  of  iron   ...  1-24             6*55              175  i-8o  2'oi 

Water        100  16*50               —  10*30  io*53 

z.  Almerode  in  KnrheBsen  (cmcible).     2.  Schildorf  near  Passan  (graphite  oraoible). 
3.  Einberg  near  Cobnrg  (porcelain  oapsole).    4.  Stourbridge.    5.  Newcastle  (fire-brick). 

The  composition  of  the  Stourbridge  fire-claj  will  be  seen  from  the  following 
analyses  by  Professor  P.  A.  Abel,  F.RS.,  Chemist  to  the  War  Department:— 


Sample. 

Silica. 

Alumina. 

Peroxide  of  Iron. 

Alkalies,  W 

I 

66*47 

2626 

663 

0*64 

2 

6565 

2659 

571 

2*05 

3 

6550 

37'35 

5-40 

175 

4 

6700 

2580 

4*90 

230 

5 

6342 

31*20 

470 

0-68 

6 

65*08 

3739 

398 

3*55 

7 

65-21 

27*82 

3*41 

356 

8 

5848 

3578 

302 

2*72 

9 

63*40 

31-70 

300 

1*90 

The  sample  No.  9,  containing  only  such  a  small  quantity  of  iron,  is  much 
superior  to  No.  i,  whose  refractory  properties  maybe  doubted.  The  clay  is  dug 
from  pits  varying  from  120  to  570  feet  in  depth.  It  is  generally  found  below  three 
workable  coal  measures,  between  marl  or  rock  and  an  inferior  clay.  The  seam 
averages  3  feet  in  thickness,  never  exceeding  5  feet,  and  the  middle  of  the 
seam  contains  the  clay  selected  for  crucibles,  &c.  Pot-clay  or  crucible-clay  only 
occurs  in  small  quantities,  and  costs  at  the  pit-mouth  55s.  a  ton,  ordinary  fire-clay 
only  realising  los.  a  ton. 

]VM«ri  day.  Ordinary  potter's  clay  also  possesses  most  of  the  properties  of  plastio 
day ;  many  varieties  form  with  water  a  similarly  tenacious  mass.  But  potter's  day 
is  highly  coloured,  retaining  the  colour  after  burning.  It  effervesces  on  the  applica- 
tion of  hydrochloric  acid  and  changes  to  marl.  It  follows  from  its  containing  large 
^  proportions  of  lime  and  oxide  of  iron  that  it  is  fosible,  and  melts  according  to 
the  quantity  of  these  constituents  at  a  higher  or  lower  temperature  into  a  dark 
coloured,  slag-like  mass.  It  is  found  in  the  last  formation,  or  entirely  on  the 
'  snr&ce  of  the  earth,  and  sometimes  in  the  tertiary  formation.  It  contains  among 
other  foreign  substances  organic  matter,  iron  and  other  pyrites,  gypsum,  &c. 

waikvfto.  Walkerite,  or  Walker's  clay,  is  a  soft,  Mable  mass,  occurring  from 
the  weathering  of  Diorite  and  Diorite  slate.  In  water  it  separates  to  a  powder,  not 
forming  a  plastic  pulp.  In  its  powdered  condition  it  is  of  use  as  an  absorbent 
of  fat,  Ac.,  whence  its  application  to  the  removal  of  grease  spots  in  books,  &c.  It  is 
found  at  Keigate  in  Surrey.  Maidstone  in  Kent,  further  at  Aix-la-Chapelle,  in 
Saxony,  Bohemia,  Silesia,  and  Moravia.  It  is  employed  in  paper-making,  and  as  an 
addition  to  ultramarine. 

vml  Marl  is  a  mechanical  mixture  of  clay  and  carbonate  of  calcium,  containing 
sand  (sand-marl),  and  other  constituents:  that  containing  lime  is  called  lime-marl; 


296  CHEMICAL   TECHNOL  «  '    J 

that  claj,  clay-maxl.  In  water  it  falls  to  powder,  and  forms  a  non-adhedTe,  pastj 
mass.  With  acids  it  effervesces,  whereby  more  than  half  the  weight  is  lost.  It  mdte 
easily.  It  is  found  in  the  lias  and  chalk  formation.  Its  chief  applicatLon  isjto  the 
improvement  of  land.  ' 

Loam.  Loam  may  be  considered  as  the  resnlt  of  the  mixture  of  clay  with  sand.  It 
is  a  clay  more  or  less  mixed  with  quartz-sand  and  iron-ochre,  also  with  lime,  when  it 
assumes  a  yellow  or  brown  colour,  changing  on  burning  to  a  red.  It  forms  unth 
water  a  slightly  plastic  mass,  and  is  not  very  refractoiy.  It  is  found  always  on  the 
surface  of  the  earth,  and  known  as  common  clay,  employed  in  the  manu&ctiire  of 
bricks,  coarse  pottery,  &c. 

There  is  sometimes,  but  very  seldom,  used  in  earthenware  manufacture,  a  nuxtme 
of  clay  and  iron-ochre  or  hydrated  oxide  of  iron  (2Fe203,3H0). 

ocnnpoiition  of  Kaolin.  Kaolin  in  puTc  conditiou,  and  only  by  means  of  washing,  freed 
from  coarse  substances,  quartz,  sand,  &c.,  is  a  mixture  of  porcelain  day  with  rodiy 
residue.  Porcelain  clay,  i.e.  the  plastic  part  of  kaolin,  is  always  of  equal  compofii- 
lion.    The  composition  of  kaolin  is  given  in  the  following  analyses : — 


Bocky  residue. 

Silica. 
1 

Alumina. 

From. 

Free. 

Combined 
with  Alumina. 

Watai 

St.  Yrieux     ... 

97 

io*9 

310 

346 

12*2 

Cornwall 

19*6 

1*2 

45*3 

240 

87 

Devonshire   ... 

4*3 

lOI 

340 

368 

127 

Passau 

45 

97 

367 

370 

12-8 

^k.U6             ...       •  •  • 

i8o 

17 

34*2 

341 

no 

Mori,  near  Halle 

43*8 

44 

21*6 

225 

75 

Kinds  of  Gia7  Wan.  Clay  waro  is  generally  separated  into  den$s  and  porous  ware.  Tha 
dense  ware  is  so  strongly  heated  that  half  its  mass  is  lost ;  its  fracture  is  glazed  aad 
conchoidal ;  it  is  translucent  and  compact,  being  impenetrable  to  vtrater ;  and  it  gives 
a  spark  when  struck  with  steel.  Porous  clay  ware  is,  in  the  mass,  not  glazed,  its 
fracture  open  and  earthy ;  and,  when  not  superficially  glazed,  water  freely  per- 
colates through  it.  It  also  clings  to  the  tongue.  The  burnt  mass,  whether  dense  er 
porous  ware,  either  remains  rough  or  is  glazed. 

The  following  are  the  essential  varieties  of  clay  ware : — 

I.  Dense  Clay  Ware,  A.  Hard  porcelain.  The  mass  equal  throughout ;  not  indflDied 
with  a  knife ;  nne-grained,  translucent,  sonorous,  and  white.  Fracture,  fine-grained  lod 
conchoidal.  Sp.  gr.  =  2*07  to  2*49.  It  may  be  considered  as  composed  of  two  sub- 
stances— namely,  as  a  natural  day  or  true  kaolin,  infusible,  and  preserving  its  whiteoeBS 
under  a  strong  heat ;  and  as  a  flux  consisting  of  silica  and  lime,  or  felspar  with  or  with- 
out gypBum,  chalk,  and  quartz.  The  glazing  is  essentially  due  to  this  flux,  and  sot 
to  oxide  of  lead  or  tin.  It  is  characteristio  of  the  manufacture  of  hard  porcelaxn  that 
the  burnings  are  included  in  one  operation. 

B.  Soft  or  tender  porcelain.  The  mass  more  easily  fluid  than  hard  porcelain.  Two 
kinds  are  known : — 

a.  French  porcelain,  a  glass-like  mass,  essentially  a  potash-alumina  silicate,  prepared 
with  the  addition  of  clay,  therefore  erroneously  termed  a  day  ware,  and  oontaining  lead 
similarly  to  crystal  glass. 

/3.  English  soft  porcdain.  The  mass  similar  to  kaolin,  plastic,  remaining  white  wken 
burnt  (pipe-day).  It  is  made  with  a  vitreous  grit,  consisting  of  gypsum,  Gonush  stone 
(weathered  pegmatite),  bone-ash  (essentially  phosphate  of  cfddum),  in  veiy  varied  pro- 
portions. The  glaze  is  obtained  by  pulverised  Gomish  stone,  chalk,  powdered  fire-eUji 
and  borax,  mostly  with,  seldom  without,  the  addition  of  oxide  of  lead.  The  glazing  i*  & 
second  process. 


EARTHENWARE.  297 

•C.  SUtne  poroelflixi,  or  bisonit  ware : — 

a.  Genxune  and  unglazed  porcelain. 

/3.  Parisian  porceliun,  or  parian.  Unglazed  siatue  porcelain  is  sixniliir  to  English 
porcelain. 

y.  Garrardf  less  translucent  than  parian,  and  sometimes  of  a  whiter  colour. 
D.    Stoneware.     Dense,  sonorous,  fine-grained,  homogeneous,  only  in  the  least,  if 
at  all,  translucent,  white  or  coloured. 

a.  Glazed  porcelain  stoneware.  Plastic,  remaining  white  after  burning,  slightly 
refra^otory  with  the  addition  of  kaolin  and  fire-clay ;  a  felspar  as  flux ;  the  glaze  contains 
borax  and  oxide  of  lead. 

/3.  "White  or  coloured  unglazed  stoneware.    Wedgwood  ware. 

y.  Common  stoneware  (salt-glazed).  No  fluxing  material  is  employed,  but  the  filing 
is  increased.    Glazed  with  siliceous  soda-alum. 

n.  Parous  Clay  Ware.  A.  Fine  Fayence  with  transparent  glaze.  The  body  earthy, 
rfjTiging  to  the  tongue,  non-transparent,  sometimes  sonorous ;  the  glaze  containing  lead, 
borax,  felspar,  <fec. 

B.  Fayence,  with  non-transparent  glaze.  The  body  of  a  yellow  burnt  potter's  clay 
or  olay-marl,  with  non-transparent  white  or  coloured  glaze  or  enamel,  containing  tin.  To 
this  class  belongs  majolica,  delf  ware,  &q. 

C.  Ordinary  potter's  ware.  The  body  of  ordinary  potter's  day  or  clay-marl,  red- 
Golonred,  soft,  and  porous.  Mostly  glazed  with  lead,  the  glaze  being  always  non-trans- 
parent. According  to  the  colour  of  the  glaze,  the  ware  is  distinguished  as  white  and 
brown. 

D.  Plate,  terra-cotta,  fire-clay  ware,  tubes,  ornaments,  vases,  <feo.  The  body  earthy; 
mostly  more  or  less  unequal ;  always  coloured,  porous,  eadly  fluid,  and  slightly  sonorous. 
Is  not  usually  glazed. 

I.  Habd  Porcelain. 

*'**"S?U£ilff***  Hard  porcelain  is  composed  of  a  mixture  of  colourless  porcelaui 
days  with  felspar  as  a  flux,  which  sometimes  is  composed  of  quartz,  chalk,  or 
gypsum.  The  porcelain  clay,  in  itself  inftisible,  and  becoming  in  the  fire  only  an 
earthy,  opaque  mass,  when  intimately  mixed  with  the  flux  material,  melts  easily  at 
a  higher  temperature  than  that  of  the  glass  oven.  The  materials  of  porcelain 
manufacture  are  not  found  native  in  such  a  conidition  that  they  may  at  once  be 
employed ;  they  must  be  ground  to  a  fine  powder,  and  this  washed  to  separate  the 
foreign  substances.  Pure  kaolin,  however,  is  not  utilisable  in  porcelain  manufacture, 
as  it  becomes  much  decreased  in  volume  on  the  application  of  heat.  It  is  therefore 
mixed  with  fine  washed  quartz  sand,  although  this  addition  somewhat  impairs  the 
plasticity.  This  mass  on  treatment  with  fire  would  be  porous,  and  it  is  for  the 
closing  of  the  pores  and  to  form  a  binding  glass  that  felspar  is  added.  The  propor- 
tions in  Berlin  porcelain,  according  to  G.  Eolbe  (1863),  are  66*6  parts  silica, 
a&'o  parts  clay,  070  part  protoxide  of  iron,  0*6  part  magnesia,  and  0*3  part  lime. 
Proportions  of  the  materials  as  employed  at — a.  Nymphenburg ;  /3.  Vienna ;  7.  Meissen : — 

a.  Kaolin  from  Passau     65 

Sand  therewith 4 

Quartz 21 

Gypsum 5 

Broken  biscuit  ware 5 

/3.  Kaolin  from  Zedlitz 34 

Kaolin  from  Passau 25 

Kaolin  from  Unghvar 6 

Quartz 14 

Felspar 6 

Broken  ware 3 

7.  Kaolin  from  Aue 18 

Kaolin  from  Sosa 18 

Kaolin  from  SeiUtz     36 

Felspar 26 

Broken  ware 2 


298  CHEMICAL  TECHNOLOGY, 

The  mixture  of  the  materials  in  the  required  proportion  takes  plaoe  in  Urge  Tail, 
whence  the  thin  pnlp  is  pumped  and  forced  through  sieres  into  another  TesseL 

Drying  the  MuB.  After  the  watsr  is  remoyed  from  the  sediment  at  the  bottom  of  the 
vat  or  tank,  the  clay  appears  as  a  slime,  which  has  to  be  dried  to  the  required  con- 
sistency. The  drying  or  evaporation  of  the  water  is  effected  in  wide  wooden  tanks 
exposed  to  a  strong  current  of  air.  This  is  a  veiy  general  method  of  drying  the 
mass,  but  can  only  be  employed  during  the  sunmier  months  on  account  of  the 
dampness  of  our  climate.  It  is  not,  therefore,  sufficiently  extensive  for  large 
manufacturers,  and  consequently  other  means  of  drying  are  resorted  to— usually 
by  means  of  absorption,  tlie  mass  being  laid  on  a  porous  layer  of  burnt  lime, 
gypsum,  &c.  Drying  by  means  of  gypsum  is  expensive,  as  it  soon  becomes 
hardened,  and  has  to  be  removed.  The  mass  can  also  be  dried  by  means  of  air- 
pressure,  being  in  this  case  placed  in  flat  porous  boxes,  under  which  a  vacuum 
chamber  is  situated.  Talbot's  apparatus  is  formed  on  this  principle.  In 
GrouveUe  and  Honor6's  system  of  drying,  the  water  is  first  partially  removed, 
by  means  of  draining  over  gypsum,  and  the  mass  is  then  put  into  firm 
hempen  sacks,  which  are  subjected  to  pressure  in  a  screw  or  lever  press.  Pressed 
clay  has  greater  plasticity  than  that  dried  by  artificial  heat;  but  the  method  is 
expensive,  as  the  sacks  soon  require  replenishing,  being  speedily  worn  out  by  the 
constant  pressure.    When  the  mass  is  dried  by  pressure  or  by  absorption,  the  water 

KneadiDjj^the  Dried  \j^  gjj  cascs  is  uot  equally  expelled,  and  there  are  also  air-bubbles, 
which  must  be  removed.  This  is  done  by  kneading  and  treading  the  mass  with  the 
feet  and  hands,  and  by  this  means  aLso  the  plasticity  of  the  mass  is  improved. 
Another  method  of  improving  the  plasticity  is  by  allowing  the  moist  day  to  stand 
tiU  it  becomes  putrid.  Stagnant  water  is  often  employed.  Brongniart  explained 
the  action  of  this  rotting,  as  it  is  termed,  to  be  that  gases  were  formed  in  the  body 
of  the  clay,  and  that  by  the  continuous  movement  caused  in  their  endeavour  to 
escape,  the  finest  particles  of  the  material  were  intimately  mixed.  Salv6tat  gives 
the  following  hypothesis: — By  the  rotting  there  is  formed  in  the  mass  a  large 
quantity  of  sulphuretted  hydrogen  gas.  This  gas  effects  the  reduction  of  the 
alkaline  sulphurets  to  sulphuret  of  calcium  under  the  influence  of  the  organic  sub- 
stances, the  sulphuret  of  calcium  being  set  free,  a  similar  action  taking  place  with 
the  carbonic  acid  in  contact  with  the  air.  The  bleaching  of  the  mass  on  exposure  to 
the  air  is  due  to  the  oxidation  of  the  black  sulphuret  of  iron  to  sulphate  of  iron, 
which  is  removed  by  washing.  The  decomposition  of  the  felspar  constituents  may 
also  ensue  from  the  long-continued  action  of  the  water.  According  to  £.  von 
Sominaruga,  of  Vienna,  the  existing  sulphates  are  decomposed  by  the  air  into 
sulphuretted  hydrogen  and  carbonated  salts,  and  these  being  removed  with  the 
water,  the  refractory  nature  of  the  clay  is  improved. 

The  MoDiding.  The  kucading  and  rotting  accomplished,  the  porcelain  mass  is  taken 
to  another  room  to  be  moulded.  This  is  effected  either  on  a  potter's  wheel  or  in  a 
mould. 

ThePottem^iieeL  The  pottcr's  whccl  cousists  of  a  vertical  iron  axis,  on  which  a 
horizontal  solid  wheel  is  fixed,  and  caused  to  revolve  by  the  feet  or  by  steam-power, 
the  motion  in  the  latter  case  being  regulated  by  the  feet.  A  lump  of  clay  is  placed 
upon  tlie  wheel,  the  thumb  being  placed  in  the  centre  of  the  lump  and  pressed  down- 
wards ;  a  hollow  is  thus  formed,  which  is  widened,  or  the  walls  continued  vertically 
according  to  the  shape  of  the  vessel  to  be  made.  The  constant  revolution  of  tbe 
wheel  easily  allows  of  the  moulder  obtaining  a  perfectly  cylindrical  form.    By  thus 


EARTHENWARE,  299 

humouring  tne  ciay,  elongating  the  vessel,  again  depressing  it,  widening  it,  and  by 
continued  manipulation  in  this  manner,  the  most  exquisite  shapes  are  produced.  To 
form  the  ridges  or  sharp  edges  of  the  vessel  a  small  piece  of  iron,  a  strip  of  horn  or 
wood,  termed  a  bridge,  is  used.  The  perfectly  formed  vessel  is  cut  away  from  the 
wheel  by  a  piece  of  brass  wire. 

***"**£& F.S?""'  -^  mould  is  first  taken  from  the  pattern  or  original  object,  which 
may  be  of  clay,  wax,  gypsum,  or  metal.  The  moulding  is  performed  with  dry 
material,  with  clay  of  the  consistency  of  dough,  or  with  fluid  clay.  The  moulds 
must  possess  a  certain  amount  of  elasticity,  and  be  porous  in  order  to  absorb  the 
moisture  expressed.  For  these. reasons  plaster-of-Paris  is  generally  used.  The 
mould  is  taken  from  the  original  article  in  parts,  which  are  trimmed  to  fit  together 
accurately ;  into  each  part  is  then  pressed  sufficient  clay  to  fill  the  indentations  of 
the  pattern,  more  clay  being  added  till  a  proper  thickness  is  obtained.  The  parts  are 
then  fitted  together,  and  the  moulds  left  for  some  time.  This  method  of  moulding 
is  sometimes  called  presswork,  and  is  adapted  to  aU  kinds  of  pottery  not  of  circular 
form.  Plates,  cups,  and  dishes  are  also  made  in  a  similar  manner.  A  leaf  of  clay 
is  rolled  out  and  pressed  between  flat  moulds.  Sometimes,  instead  of  rolling,  the 
day  is  beaten  out  with  a  wooden  hammer  covered  with  leather. 

CMiing.  Moulding  porcelain  articles  out  of  thin  pulpy  day  is  one  of  the  most 
ingenious  arts  of  the  potter.  The  fluid  clay  is  poured  into  porous  moulds,  which 
absorb  a  portion  of  the  water,  thereby  reducing  the  pulp  to  a  certain  consistency. 
The  interior  pulp  remaining  fluid  is  now  poured  out,  and  the  cast  or  coating  of  clay 
adhering  to  the  mould  allowed  to  harden.  When  sufficiently  hard  the  vessel  is  taken 
to  the  lathe  to  be  finished,  or  if  not  of  circular  form,  to  the  finishing  room,  where 
with  sharp  tools  any  required  pattern  is  cut,  or  handles,  spouts,  &c.,  which  have  been 
made  in  separate  moulds,  attached. 

^S2£H!iu^'afuSS!d£  T^®  finest  porcelain  is  finished  by  hand,  as  machinery  or 
moulds  could  not  give  sufficient  sharpness  to  the  beautiful  flowers  and  figures 
sculptured  on  vases,  &c.  The  flowers,  &c.,  are  first  prepared  in  moulds,  are  then 
attached  to  the  body  of  the  artide,  and  finally  are  finished  off  with  edged  tools.  The 
stalks  of  the  flowers  are  sometimes  formed  on  wire ;  and  the  leaf  is  first  roughly 
constructed  in  the  pahn  of  the  hand,  the  farrowing  and  veining  being  done  after- 
wards. The  texture  of  drapery  is  imitated  by  means  of  a  piece  of  tulle,  which  is 
laid  on  the  clay,  and  allowed  to  dry.  Dunng  the  burning  the  tulle  is  consumed, 
leaving  the  pattern  on  the  porcelain. 

Dryinff  tbe  Poneiftin.  After  the  porcclaiu  ware  is  formed  it  is  dried  for  some  time  at 
the  ordinary  temperature.  This  is  continued  till  the  clay  contains  no  moisture,  thai 
is,  until  its  weight  is  tolerably  constant.  During  this  diying  the  day  is  said  to  be 
in  the  green  state,  and  possesses  a  greater  tenacity  than  it  has  in  any  of  the  former 
processes. 

GUxins.  Only  very  few  articlea  of  porcelain  ware,  generally  statues  or  figures,  remain 
nnglazed;  these  are  termed  hUcuit  ware.  All  other  articles  are  glazed.  The  glazings 
employed  are  of  four  kinds :— i.  Earth  or  clay  glazings  are  transparent,  and  formed  by 
melted  silica,  almnina,  and  alkalies;  they  easily  become  fluid,  and  melt  about  the 
temperature  at  which  the  vessels  are  baked.  This  kind  of  glazing  is  used  for  hard 
porcelain.  2.  Lead  glazes  are  transparent  glazes  containing  lead ;  most  of  these  melt 
at  the  temperature  at  which  the  articles  are  burnt.  3.  Enamel  glazes  are  partly  white, 
partly  coloured  opaque  glasses  containing  oxide  of  tin  besides  oxide  of  lead.  This  kind 
of  glaze  is  easily  melted,  and  serves  to  cover  the  unequaJ  colour  of  the  under  mass.  4. 
Lustres  are  mostly  earth  and  alkali  glazes.  This  class  includes  the  ordinary  salt-glazed 
ware,  as  well  as  glazes  containing  metallic  oxides  used  to  itoitate  gold  and  silver  surfaces 
for  ornament  merely. 


30O  •  CHEmCAL  TECHNOLOGY. 

'PorabiiTGiaM.  ii  We  will  here,  however,  concern  ourselves  only  with  porcelain  glaze. 
It  is  necessary  that  this  glaze  should  melt  readily  at  the  temperature  at  which  the 
article  is  fired ;  that  it  should  he  colourless  and  opaque ;  that  it  should  fire  suffidentiiy 
hard  to  withstand  pressure,  grinding,  and  ordinary  cutting.  The  glaze  is  added  to 
the  porcelain  mass  with  a  flux,  so  that  the  melting  may  he  readily  effected.  At 
Meissen  the  glaze  used  contains : — 

i^uarvz  •••     ■••     •••     •••     •••     •••     •••     •••     •••     37  ^ 

Kaolin  from  SeiHtz    37-0 

liime  from  Pima 17*5 

Broken  porcelain 8'5 

1000 
In  the  Berlin  porcelain  manufacture  the  following  glaze  is  employed : — 

Kaolin,  from  Morle,  near  Halle 31 

^qjuanZ'SancL    •••     •••     •••     •••     •••     •••     ««•     «•«    a^ 

xjrv uBUiu   •••      •••      •••      •••      •••      •••      •••      •••      •■•      Xa 

Broken  porcelain 12 


100 
Applying  ui«:oiBM.  The  glaze  can  he  put  on  in  four  ways : — i.  By  immersion.  2.  By 
dusting.  3.  By  watering.  4.  By  volatilisation.  The  glaze  is  either  mixed  with 
the  ingredients,  or  applied  superficially  hy  one  of  the  preceding  methods.  Glazing 
zamMnion.  hy  immersion  is  employed  in  the  case  of  porcelain,  the  finer  Fayence  ware, 
and  sometimes  for  stoneware.  It  requires  some  degree  of  porosity  in  order  that  the 
glazing  pap  may  he  ahsorbed.  The  glaziug  materials  are  mixed  with  water  to  fionn 
a  thin  pulp.  The  articles  previous  to  their  immersion  are  slightly  baked  to  preTent 
the  clay  being  softened  and  running  fluid  in  contact  with  the  water  of  the  glaze. 
The  articles  are  dipped  into  the  glaze,  which  they  readily  absorb,  a  coating  or  thin 
layer  of  glaze  remaining  on  their  surface  when  they  are  removed  from  the  bath. 
The  glaze  is  removed  from  the  bottom  of  the  article  immediately  in  contact  with  the 
substance  on  which  it  stands  to  prevent  its  sticking.  Glazing  by  dusting  is  a  snr&oa 
ntutinf.  method,  and  only  used  for  costly  ware.  The  freshly  formed  and  still  damp 
ware  is  dusted  with  lead  glaze  or  minium,  a  layer  being  left  on  the  surface.  The 
powders  employed  chiefly  contain  oxide  of  lead,  which  combines  with  the  silica  and 
alumina  of  the  day  mass  during  the  firing  to  form  a  glaze.  Recently  finely-pulverised 
Wftteiinc.  ziuc  blondc  and  Glauber  salt  have  been  employed.  Watering  is  a  method 
of  glazing  employed  for  non-porous  articles,  such  as  English  porcelain,  ordinary 
pottery  ware,  and  some  kinds  of  Fayence  ware.  Glaze  of  the  proper  consistence  is 
poured  over  the  articles,  the  interior  sometimes  being  left  coated  with  a  white  glaze, 
while  the  outside  is  again  coated  with  a  coloured  glaze,  as  is  seen  in  common  brown- 
By  voiAtniuUon  or  smMiins.  ware.  Glazing  by  volatilisation  is  effected  by  conveying  into 
the  oven  a  salt  or  metallic  vapour  which  shall  form  with  the  silica  of  the  mass  an 
efiicient  glaze.  The  most  general  method  is  applied  to  ware  not  requiring  to  he 
baked  in  fire-clay  vessels.  Common  salt  is  placed  in  the  oven  with  green  wood  for 
fuel  to  form  an  irriguous  smoke.  This,  the  salt,  heated  to  redness,  receives,  and  if 
decomposed  into  hydrochloric  acid  and  soda,  the  vapours  of  which  fill  the  oven. 
The  inside  and  the  outside  of  the  vessel  submitted  to  this  process  are  thus  simulta- 
neously glazed.  Fine  stoneware  baked  in  fire-clay  vessels  may  be  glazed  by 
the  ignition  of  a  mixture  of  potash,  plumbago,  and  common  salt    During  the 


EARTHENWARE. 


301 


bakiDg  or  firing  chloride  of  lead  is  formed,  which  combines  with  the  silica  of  the 
cla7  to  form  a  thin  gloss.  This  method  of  glazing  is  in  England  termed  imearin^, 
borodc  acid  being  employed. 

'""^cS™!"*"  *  method  of  glazing  by  volatilisation,  known  as  glazing  with  flowing 
colours,  is  employed  for  porcelain.  It  essentially  consisls  in  the  ignition  of  a  mix- 
ture of  chloride  pf  calciom,  chloride  of  lead,  and  clay,  placed  in  a  small  vessel  in  the 
firing  capsule  or  firing  chamber,  and  to  which  some  metallic  oxide  is  added,  as  cobalt 
oxide.  The  oxide  is  converted  into  chloride,  and  combines  with  the  constituents  of 
the  article. 

Thac>nai>.«SMts.  Porcelain  ware  and  snperfine  earthenware  are  not  exposed, 
when  burnt,  to  tbe  free  action  of  the  flame,  as  varions  impurities,  snch  as  ashes 
sad  smoke,  would  deteriorate  the  beanty.  They  are  therefore  enclosed  in  fire- 
clay vessels,  termed  in  France  gazette*,  in  Oennany  kapteln,  and  in  Elngland 
taggert.  These  sa^^ers  are  mannfactnred  of  the  best  fire-clay,  with  which  is  mixed 
a  cement  made  from  broken  saggers.  First  into  each  sagger  is  put  a  perfectly  tme 
disc  of  the  same  material  and  upon  this  the  porcelain  ware  is  placed,  three  knobs  or 


Fia.  148. 


nuall  props  projecting  from  the  disc,  and  keeping  the  article  from  contact  with  ft 
large  surface  to  which  the  glaze  would  cause  it  to  adhere. 
TiwPowtaUi  oiBi.      Fig.  147  is  a  vertical  section  of  the  porcelain  oven,  and  Fig.  148 
the  elevation.    Theoven  is  essentially]^a  reverberatory  furnace  with  three  stages  and 


302  CHEMICAL  TECHNOLOGY, 

five  fire-rooms  supplied  with  wood  fires.    The  oven  may  be  considered  aa  a 
•  cylinder,  surmounted  by  a  cone,  in  the  apex  of  which  is  the  chimney  opemngj 
flat  vaults  by  which  it  is  divided  being  pierced  to  allow  of  communication.    Both! 
stages,  L  and  l',  serve  for  the  "  strong  firing  "  of  the  porcelain.     The  upper  stage,' 
termed  variously  the  AoM'tfZZ,  crown,  or  cowl,  serves  for  the  "  raw  burning."    At 
bottom  of  both  the  lower  stages  are  built  the  fire-places,/,  leading  by  g  into  the  o^^ 
0  is  the  ash-pit,  x  tlie  opening  to  the  ash-pit  closed  during  the  burning;  &ki 
opening  through  which  fuel  is  introduced ;  c  c  are  the  openings  admitting  of 
circulation  of  the  hot  gases,    p  is  the  door  by  which  the  oven  is  entered.     The  ore 
are  gradually  heated  first  to  glowing  heat  and  then  to  a  strong  red  heat.    At 
stage  the  openings  are  closed  and  the  oven  raised  to  a  stronger  heat,  at  which  it) 
allowed  to  remain  for  a  short  time.    This  intense  burning  lasts  about  seventeen 
eighteen  hours ;  the  oven  is  then  opened,  and  allowed  to  cool  gradually  for  three  i 
four  days. 

SmjptyinR  the  ov«n  anA      After  the  oveu  is  cooled,  the  Baggers  containing  the  ware 
Sorting  the  Ware.       removed,  and  the  ware  taken  out.    It  is  then  separated  into  U 
kinds: — a.   Superfine,  containing  no  blemished  ware,     h.   Medium,  the  ware  cJif 
inferior  in  glaze,  &c,    c.  The  chipped  and  imperfectly  glazed  ware.    d.  Waste,  or  ware 
distorted  or  cracked  as  to  be  nselesB. 

Fanity  Ware.       The  ohlcf  faults  are : — Cracking  from  the  porcelain  not  being  snffick 
plastic,  from  drying  unequally,  and  from  unequal  heating,    t'art  fusing  from  a  too 
heat.     Air-bubbles  oausing  lumps  to  appear  on  th^  surface  of  the  ware  through 
expansion  of  the  air  by  heat.    Spotting,  from  fragments  of  the  sagger  fusing  and  fi 
in  upon  the  ware.    Yellow-colouring,  horn  smoke  having  entered  the  sagger.    The 
faults  in  the  glaze  are : — ^Blowing,  the  result  of  the  development  of  gas  by  the  reaction 
the  constituents  of  the  glaze  upon  each  other ;  also  resulting  from  too  strong  a 
Shelling,  or  the  exfoliating  of  the  glaze. 

poneudn  paintiiw.      Porcelaiu  painting  is  really  a  branch  of  glass  painting,  the  cdoi 
being   glass-colours,  wliich    when  burnt   in   become    durable  and  bright, 
colours  employed,  technically  termed  muffle  colours,  are  : — 

Oxide  of  iron,  for  red,  brown,  violet,  yellow,  and  sepia, 
chromium,  for  gi'een. 

cobalt  and  potassium-cobalt-nitrite,  for  blue  and  black. 
,,        uranium,  for  orange  and  black. 
„        manganese,  for  violet,  brown,  and  black. 
„        iridium,  for  black, 
titanium,  for  yellow, 
antimony,  for  yellow, 
copper  (and  protoxide),  for  green  and  red. 
Chromate  of  iron,  for  brown. 
„        lead,  for  yellow. 
„        barium,  for  yellow. 
Chloride  of  silver,  for  red. 
Chloride  of  platinum,  for  platinising. 
Purple  of  Cassius,  for  purple  and  rose-red. 

These  colours  are  mixed  with  a  fluxing  material,  so  that  by  the  melting  a  silicate 
or  borate  may  be  formed,  3delding  a  good  glaze.  Therefore  the  oxide  of  cobalt  and 
the  oxide  of  copper  must  first  be  mixed  with  silicic  acid  and  boracic  acid,  oxide  of 
antimony  with  oxide  of  lead,  &c.,  to  form  a  blue,  green,  or  yellow  colour,  because 
there  are  few  metallic  oxides  yielding  these  colours  that  are  not  affected  ii^'uriously 
by  heat,  or  are  by  themselves  sufficiently  easily  fluid.     The  buming-in  of  the 


EARTHENWARE.  30s 


1^  ,2t'''*''>°''B  'A  effected  in  a  muffle,  F^  149,  the  opening  o,  semng  a 
J ^ Kith  the  interior,  by  which  the  degree  of  heat  may  be  ascertained,  the  opening,  m, 
miLt  **"^^  ^"'^  ^^  escape  of  the  vapours  of  the  essential  nils  [oil  of  turpentine,  oil  of 
n.^kvender,  Ac.),  with  which  the  enamel  colours  are  sometimes  ground  up.     Fig.  150 


•^ 


showB  the  method  of  heating  the  muffle.  The  heating  ia  commenced  at  a  low  tem- 
<  peratnre  and  is  gnduallf  increased  to  a  red  heat.  From  time  to  time  the  mufSe  is 
-  opened  till  the  colours  begin  to  disappear ;  then  the  muffle  is  carefully  closed,  raised 
to  a  bright  red  beat,  and  finally  allowed  to  cool  bb  slowly  as  possible. 

OniMMiam  tin  PoritiQ.  The  gold  employed  for  decorating  the  porcelain  is  diasoWed  in 
aqoa  r^a,  and  precipitated  with  either  adphate  of  iron,  mtrate  of  protoxide  of  mercury, 
or  by  oeuiH  of  oialia  aoid.  In  its  application  the  gold  mnst  be  intimately  miied  with  a 
flu,  generaU;  nitrate  of  oxide  of  biamntb.  Shell  gold  is  employed,  also  gold-bent  era' 
refnae.  The  article  to  be  gilt  mnst  be  tborongbly  freed  from  grease,  cIbb  the  gold  will  not 
adhere,  Tba  gold  powder,  flcely  gionnd  ap  with  sugar  01  honey,  or  some  sach  soluble 
nbetftnce,  ia  applied  with  a  pencil  bmeh.  The  buming-in  is  effected  in  a  muffle.  The 
gold  i»  not  melted  during  the  burning,  but  becomes  Armly  set  upon  the  article  by  means 
of  the  flui.  After  burning  the  gold  does  not  at  once  appear  bright,  but  requires 
bnmishing  with  an  agate  tool. 

EB(M  aodiu.  Bright  gilding  differs  from  the  foregoing  in  requiring  no  after  polishing 
or  bumiahing.  It  ia  effected  by  buruing-in  a  solution  of  sulpboret  of  gold  or  fulminating 
gold  in  balsam  of  snlpbnr.  When  an  article  is  gilded  with  precipitated  metallic  gold  or  a 
bright  gold  preparation,  the  gilding  is  secure  from  injury  by  handling  or  soratching  with 
the  finger-nail,  &c. 

■unrtaiudFuucLiiiif.  SilTering  and  platinisiDg  are  usually  only  in  slight  requisition. 
Uetallio  silver  is  thrown  down  from  its  solution  by  means  of  copper  or  zinc ;  the 
platinum  is  precipitated  from  its  nentral  chloride  by  means  of  boUing  with  potsah 
■nd  sugar.  The  tamiabing  of  silver  on  porcelain  by  aulphnietted  hydrogen  may, 
according  to  Bonaaeau,  be  prevented  by  placing,  before  burning,  a  thin  layer  of  gold  upon 
the  part  silvered ;  the  result  then  is  a  white  layer  of  gold-silver.  Much  care  is  not  neces- 
sary in  this  proeess.  The  silver  and  platinum  are  mixed  with  basic  nitrate  of  oxide 
of  bismuth,  painted  on  and  bnint  in,  sud  afterwards  burnished. 

iJt^DFiiuu.  Transparent  porcelain  is  used  in  the  art  of  litbopbanie,  or  making  tranapa- 
tenciea.  A  thin  and  ungtazed  pcrcelain  plate  is  pressed  into  a  flat  gypsum  mould 
bearing  the  pattern  in  high  relief.  The  Sgures  by  transmitted  light  appear  in  delicately 
nmnded  tones  of  light  and  shade.  The  applications  of  this  art  to  the  manufacture 
fo  lamp-sbades,  window  omamenta,  ^.,  are  too  wull  knownto  need  remark  here. 


304  CHEMICAL   TECHNOLOGT, 

II.  Tender  Porcelain. 
Ttaneh  Ftitte  Poredain.  Tender  or  fritte  porcelain,  is  distingiiislied  in  commense  as  of 
two  manufactures — French  and  English.  The  French  manufacture,  in  1695,  ms 
first  carried  on  at  St.  Cloud,  near  Paris,  by  Morin,  wha  employed  fl  gLassy  tdbsH 
without  the  addition  of  kaolin,  but  containing  lead,  somewhat  similar  to  ciystal 
glass.  It  can,  therefore,  hardly  be  considered  a  porcelain,  strictly  so  called,  until 
melted  with  lime  and  alumina.  Thus  fritte  porcelain  is  composed  of: — i.  A  glus 
mass  or  fritte,  obtained  from  silica  and  alkalies.  2.  Marl,  as  a  clay  constituent 
Chalk,  as  a  lime  constituent.    The  proportions  of  these  constituents  are: — 

Fritte        75        75 

Marl  ...     17  8 

Chalk        8        17 

The  fritte  is  mixed  with  the  chalk  and  marl  to  form  a  thin  pulp,  which  is  allowed 
to  remain  for  a  month  to  diy,  and  then  again  pulverised.    When  required  quidkly 
plasticity  is  obtained  by  adding  soap-  or  lime-water.     Fritte  porcelain  is  bttrnt 
in  saggers,  generally  before  glaeing.     During  the  burning  this  kind  of  poreelaiit 
softens  more  than  the  hard,  and  requires  supporting  on  every  side.    It  is  for  tloB 
reason  generally  baked  in  fire-clay  moulds.    The  ordinary  oven  is  employed.    The 
glaze  for  tender  porcelain  is  a  kind  of  crystal  glass  containing  lead.    This  glaze 
is  poured  over  the  articles,  as  they  are  non-absorbent  on  immersion.    French  porce- 
lain is  similar  to  cryolite  glass  or  hot-cast  porcelain.  (See  p.  291). 
Bngush  FMtto  poTMiain.      English  tender  porcelain  consists  of  a  plastic  clay,  so-called 
China  day  or  Cornish  stone,  a  weathered  pegmatite,  with  fire-clay  and  bone-ash.  The 
*  addition  of  the  latter  is  due  to  Mr.  Spade,  in  1802 ;  recently  phosphate  of  caldnm, 
as  apatite,  phosphorite,  staffelite,  or  sombrerite,  has  been  substituted.    The  glaze  is 
composed  of  Cornish  stone,  chalk,  fire-brick,  borax,  and  oxide  of  lead.    The  article 
must  be  baked  before  glazing,  as  the  glaze  is  so  much  more  easily  meltible  than  the 
body  of  the  article ;  and  in  this  second  firing  lies  the  difference  between  the  manu- 
facture of  tender  and  of  hard  porcelain.    In  hard  porcelain  the  melting-point  of  the 
glaze  and  the  body  are  the  same.    English  porcelain  is  far  less  solid  and  more  liable 
to  crack  than  the  hard ;  upon  the  other  hand,  English  porcelain  is  the  more  pkstiOt 
and  can  be  produced  at  a  lower  temperature  in  saggers  of  inferior  fire-resisting 
qualities,  consequently  at  a  less  expense.    The  burning  takes  place  in  a  stage  oven 
with  anthracite  coals,  the  articles  being  placed  in  saggers.    The  glaze  is  applied  by 
immersion.    Recently  boracic  acid  has  been  largely  employed  in  glazing  English 
porcelain. 

PuiuiaBdCaiTarm.  Parian  ifl  an  unglazed  statue-poroelain,  Bimilar  to  English  porcelain, 
but  more  difficultly  fusible,  contaiuing  less  flux  and  more  silica.  The  colour  is  a  veiy 
slight  yellow ;  the  eurfaoe  is  waxlike.  Parian  was  first  prepared  by  Copeland,  in  1848, 
although  the  idea  was  not  new,  as  before  this  time  Euhn  of  Meissen,  had  prepand 
statues  and  medallions  of  porcelain  in  imitation  of  marble.  The  composition  of  paiian 
is  very  variable ;  some  on  being  tested  yield  phosphate  of  calcium,  others  silicate  of  barium, 
and  again  some  contain  only  kaolin  and  felspar. 

Carrara,  so  named  in  its  imitation  of  the  marble  produced  from  Carrara  in  Tuscany,  ii 
intermediate  to  parian  and  stoneware,  is  less  transparent  than  parian,  and  sometimei 
whiter  in  colour. 


EJRTHENWABE. 


305 


m.  Stoneware. 
Unrnn.  Stoneware  difTeis  entirely  from  porcelain ;  it  is  dense,  a 
gmined ;  does  not  cling  to  the  tongue.  It  is  semi-fused  end  opaque.  Even  fine 
white  stoneware  ia  diffeient  £rom  porcelain  in  trauspareucy,  being  entirely  opaque, 
attliongh  in  some  other  respects  suaiilair.    Stoneware  is  distinguished — 

1.  As  porcelain  glazed. 

2.  As  white  or  coloured  nnglazed. 

3.  As  common  stoneware,  Ealt-glozed. 

.  The  fine  white  stoneware  is  made  from  a  plastic  clay,  burning  white,  and  not  very 
refractory.  To  the  clay  is  added  kaolin  and  fire-clay  with  a  felapar  mineral, 
generally  Cornish  stone,  as  a  flux.    The  glaze  contains  oxide  of  lead  and  borax,  and 

Fio.  151. 


is  transparent.    The  flux  is  nsed  in  the  making  of  stoneware  much  more  freely  tl 
in  porcelain,  in  the  proportion  of  more  than  half  the  weight  of  the  mass.    It  follows 
that  stoneware  can  be  burnt  at  a  lower  temperature  than  porcelain.    The  articlea 


306 


CHEMICAL  TBCHNOLOar. 


mre  fasliioaed  out  of  the  plastic  claj  in  the  some  manner  as  porcelain.    Fine  stons- 
ware  is  used  us  a  cheap  substitute  for  porcelain,  it  being  much  more  eaail;  burnt 

'Whit«  or  coloured  unglazed  stoneware,  or  Wedgwood -ware,  is  made  from  a  plastie, 
slightly  refractorj  clair,  kaohn,  fire-clay,  and  Cornish  stone,  the  latter  in  the  propor- 
tion of  half  the  weight  of  the  whole.  It  is  more  easOy  fusible  than  porcelsin, 
requiring  a  lower  temperature  in  bur&ing.  The  coloured  Btoneware  is  of  tLe  same 
compositioa  as  Uie  white,  the  colouring  being  only  superficial.  Frequently  other 
coloured  clays  are  iised  for  ornaments  in  relief.  Coloured  Wedgwood-ware  is 
known  as  Egyptian,  bamboo,  fine  salt  ware,  fine  biscuit,  &c.  , 

Common  stoneware  differs  from  the  preceding  in  containing  no  flnx,  the  clay  bdng  ■ 
semi-fused  by  the  continued  action  of  the  fire.  To  the  clay  is  added  fine  sand,  a 
pulverised  fragments  of  stoneware.  Chemical  and  pharmaceutical  utensils,  add 
tanks,  ix.,  are  made  of  this  ware,  it  being  strong  and  durable.  The  colonr  is 
generally  gray. 

Shuunn  othu.  The  OTens  for  burning  stoneware  are  so  constructed  that  the  artidei 
can  either  lie  down  or  be  placed  vertically.  Fig.  151  is  therertical  sectiou  of  such 
an  oven  through  the  line  a  b  in  Fig.  152.  Fig.  153  is  a  section  through  th«  line 
c  n,  seen  from  b.  Fig.  154  is  a  section  through  c  d,  seen  from  a.  Fig.  152  is  the 
plan  on  the  line  e  r.  Fig.  151.  u  n  is  the  arch  or  vault  of  the  oven,  built  of  clay; 
b,  the  vessel  chamber;  c,  the  fire-room;  li,  the  fire-bars;  «,  the  stoke-hole ;  X  ^ 
ash-pit ;  g,  an  air-draught ;  i  i,  a  pierced  wall ;  ft,  a  pierced  back-wall,  throng 
which  the  flame  and  hot  gases  escape  into  0,  serving  as  a  flue.  Stone-coal  is  used  ai 
fuel.    Another  form  of  oven  in  which  mineral  water  bottles  are  burnt  is  shown  in 


Fio.  153. 


Fio.  154. 


Fig.  155.  It  is  constructed  on  an  easy  slope ;  at  the  lowest  part  is  the  fire-room,  a. 
In  the  middle  of  the  burning-room  is  the  pierced  wall,  c,  technically  termed  the 
window,  tlirougii  WTiich  the  hot  gases  and  flume  escape  into  o.  The  vault  and  walls. 
B  and  E,  are  of  broken  earthenware  bound  with  mortar.  A  chimney  is  nnnecesssaiy, 
the  gases  escaping  through  the  pierced  wall,  e,  into  the  air.  The  burning  usually  takes 
about  eight  days.  The  high  temperature  at  which  common  stoneware  ia  burnt,  and 
the  nature  of  its  components,' render  glazing  unnecessary;  but  generally  a  glaze  is 
obtained  with  the  help  of  common  salt  placed  in  the  oven  during  boming.    After  tlie 


BABTHENWABE.  307 

pikci&g  of  the  salt  the  openings  of  the  oven  are  closed  for  some  time,  and  then  ft 
Kcond  quantitj  of  salt  is  introduced.  The  silica,  with  the  aBsistance  of  the  steam, 
dscompoaea  the  salt  into  hydrochloric  acid  and  soda,  witb  which  it  combines.  Thnc 
there  is  formed  on  the  snrtaoe  of  the  ware  a  glaze  of  silicate  of  eoda  and  alumina. 
The  aalt  will  take  up  more  than  50  per  cent  silica,  according  to  Ley kanf  a  experiments; 
therefore,  the  mote  ailiea  the  better  glaze.    An  oven  of  moderate  size  will  teqoirs 


80  to  100  poonds  of  salt;  the  purity  of  the  salt  is  not  a  snbject  of  mnch  eon- 
dderation.  The  glaze  is  colourless,  and  the  vessel  appears  the  colour  of  the  day. 
Stoneware  that  is  nneqnally  coloured,  one  part  brown,  the  other  gray,  has  been 
brought  to  that  state  by  the  escape  of  hydrocarbons  into  the  burning- room. 

u^H»iwsn.  Iiacqaered  ware,  known  As  Terralite  and  Sidsrolite  ware  in  northcra 
Bohemia,  and  mannfactared  by  the  firms  of  Yilleroy  and  Bach,  of  Dresden,  is  an  inter- 
mediate ware  to  fine  and  common  etoneware ;  it  has  no  glaze,  but  a  strong  snrface  coloor 
of  varnish  or  lacqaer.  Candlestieka,  bowls,  flowei-vases,  jogs,  flower-pota,  baakets, 
bntter-dishes.  fruit. dishes,  Ac,  are  formed  from  this  ware,  and  baked  in  Baggers  in  the 
nsnal  manner.  Qreat  oare  and  attention  are  required  in  bnming  the  ware.  The  ooloni 
or  bronie  is  mixed  with  vamlab  thinned  with  tnrpentine  or  Unaeed-oil,  and  applied  with 
a  penitiL  The  ware  is  then  placed  in  a  slow  oven ;  the  etherial  oils  volatiliee,  and  the 
broeie  oolonr  besomes  fixed  to  the  sarfaoe  of  the  ware. 

IV.  Faybscb  Wars. 
hrnuwan.  Fayesce  ware  (English  fine  stoneware)  derives  its  name  &:om  the 
town  of  Faenza,  in  the  Italian  States,  where  the  ware  was  akilfally  made.  In  the 
9th  century  the  Spanish  Moors  manufactured  fayence  in  the  Island  of  Majorca, 
whence  the  present  Majolica,  the  slight  alteration  in  the  manner  of  spelling  being 
accounted  for  by  Dante  in  bis  "  Tra  iiola  di  Capri  e  Mnjoliea,"  on  the  gronnd  that 
the  older  Tuscan  writers  spell  the  name  of  the  Island  "  Migolica."  The  indnstry 
devftlopedfrom  the  13th  to  the  15th  century;  from  that  to  the  17th  it  culminated, 
and  then  commenced  to  decline.  In  the  middle  of  the  i6th  century  Bernard  Falissy 
.  introduced  the  ware  known  as  Paliasy-fayence  into  France.  Pahsay'a  celebrated 
I  Piieei  natiquM  consist  of  ware  omamentated  with  fish,  froit,  vegetables,  Ac., 
nttnrally  coloured  in  enamel.  The  body  of  porous  fiiyeuce  ware  is  earthy,  and 
dings  to  the  tongne.  It  is  opaque,  with  more  or  less  plasticity,  and  little  or  no 
Booorosi^.  It  consists  generally  of  plastic  clay,  or  a  mixture  of  this  with  common 
potter's  clay.  It  differs  from  clay  ware  in  the  employment  of  finer  materials,  manipn- 
laled  with  greater  care.  Pine  white  fayeuce  is  distuict  from  common  enamelled 
byeoce.  Fine  fayence  (semi -porcelain)  consists  of  a  plastic  clay  with  pulverised 
quartz  or  fire-bricks,  with  kaolin  or  pegroatil^  and  felspar  minerals.  It  remains 
white  after  burning,  and  is  coated  with  a  transparent  glaze.  The  fayence 
ware  of  different  countries  differ  gieatly;  some  are  easily  fuaibk,  others  again  are 


3o8  CHEMICAL  TECHNOLOGY. 

burnt  at  a  high  temperature.    The  composition  of  the  glaze  is  therefore  very  taried- 
Common  lime  fgiyence  is  a  mixture  of  potter's  or  plastic  clay,  marl   (day  with 
carbonate  of  lime),  or  quartz  and  quEurtz-sand.    It  is  characterised  by  containing 
15  to  25  per  cent  of  lime,  that,  at  the  low  temperature  at  which  common  fayence  is 
burnt,  only  loses  a  portion  of  its  carbonic  acid.    The  common  fayence  ware  is  thus 
easily  distinguished  from  other  wares  by  its  property  of  effervescing  when  an  add 
is  poured  into  a  vessel  made  of  this  ware.    Its  fractui'e  is  earthy ;  the  colour,  con- 
sequent upon  its  containing  2  to  4  per  cent  of  oxide  of  iron,  a  decided  yeUow,  so  that 
an  opaque  glaze  is  employed.    The  glaze  or  enamel  contains  usually  oxide  of  tin, 
oxide  of  lead,  alkalies,  and  quartz.    The  more  oxide  of  iron  and  lime  contained  in  the 
mass,  the  lower  the  temperature  required  for  burning.    Fayence,  like  porcelain,  is 
twice  burnt,  first  without,  and  finally  witli,  the  glaze.    It  is  burnt  in  saggers ;  liie 
ware  is  placed  in  the  saggers,  and  these  are  piled  one  upon  the  other  in  the  fdmaoe, 
with  a  layer  of  fat  clay  between  each  pair.    The  articles  stand  in  the  saggers  upon 
small  tripods  in  order  to  expose  as  small  a  contact  surface  as  possible.    The  hard- 
burnt  ware  has  next  to  be  glazed.    A  thin  pulp  with  water  is  made  of  the  materials 
of  the  glaze  placed  in  a  cistern  into  which  the  articles  are  dipped.   The  glaze  usually 
consists  of  felspar  (Cornish  stone),  fire-clay,  heavy  spar,  sand,  borax,  and  borade 
acid,  crystal-glass,  soda  and  nitrate  of  soda,  white-lead,  minium,  and  smalt.    The 
composition  of  this  glaze  is  ordinarily  veiy  complicated,  but  the  essential  constitaents 
are  silica,  borade  add,  alumina,  oxide  of  lead,  and  alkali.    Recentiy  the  Peruvian 
mineral,  so-called  tiza  (borate  of  soda  and  lime),  has  been  employed.    The  addition 
of  lead  serves  to  render  the  glaze  easily  fusible,  while  the  felspar  imparts  the  soft- 
ness characteristic  of  a  lead-alkali  glaze. 

^^TSySSf*  Fayence  is  ornamented  by — i.  Painting;  2.  Casting;  3.  Printing; 
4.  Lustring.  Painting  is  usually  done  with  the  brush,  partiy  under,  and  partly  upon, 
the  glaze.  The  glazing  oven  not  attaining  so  high  a  temperature  as  the  porcelain 
oven,  the  colours  are  not  affected  by  the  heat.  The  colours  used  are  oxide  of 
chromium,  oxide  of  cobalt,  oxide  of  iron,  oxide  of  antimony,  &c.  The  rose-  and 
purple-red  colours  are  obtained  from  gold  preparations.  The  pink  colour,  carnation 
pink,  was  discovered  in  this  country,  and  is  essentially  a  protoxide  of  chromium.  Ta 
make  this  colour — 

Stannic  acid 100 

v/iiaiK     •••     ••■     •«•     •••     •••       34 

Chromate  of  potash    3 — 4 

01 1  i\-M>  ••••••         •••         •••         •••        •••  ^ 

Alumina        i 

are  well  mixed  and  allowed  to  stand  for  some  hours  in  a  strong  heat.  The  mass 
appears  as  a  dirty  rose-red  colour,  attaining  its  full  brilliancy  when  washed  with 
water  acidulated  with  hydrochloric  acid.  The  casting  consists  in  the  fayence  vessel 
receiving  a  surface  layer  of  coloured  clay  in  any  required  part,  independentiy  of  the 
colours  of  the  mass.  These  coloured  clays  or  clay-washes  are  made  of  the  ordinary 
fat  clays  and  metallic  oxides.  The  printing  is  accomplished  with  the  aid  of  a  thin 
tissue  paper,  upon  which  the  pattern  is  first  printed  from  a  copper  plate,  and  after- 
wards transferred  to  the  ware.  For  black,  a  mixture  of  forge-scale,  manganese, 
oxide  of  cobalt,  or  chrome -black  is  employed ;  for  blue,  oxide  of  cobalt  mixed  with, 
"  for  -bright  blue,  fire-brick,  and  for  less  intense  colours,  heavy-spar,  both  of  conrse 
bdng  pulverised.    This  mixture  is  burnt,  the  frit  ground,  and  mixed  with  a  flux 


EARTHENWARE.  309 

of  eqnal  parts  of  flint-glass  and  fire-clay.    Copper  plates,  in  which  the  pattern  is 

deeply  cnt,  are  charged  with  colour  mixed  with  linseed-oil;  a  transfer  is  then  taken 

on  the  fine  "  pottery  tissue"  paper,  and  laid  on  the  ware.     By  means  of  a  rubher 

the  colour  is  caused  to  leave  the  paper,  which  has  been  previously  moistened  with 

water,  and  adhere  to  the  ware.    The  paper  is  then  washed  off,  and  the  article  taken 

to  the  kiln. 

noiving  Colours.      Flowiug  colours  are  much  employed  in  ornamenting  fayence.   The 

common  feyence  or  delf  ware  is  coloured  blue  in  this  manner  by  means  of  protoxide 

of  cobalt  mixed  with  the  glaze.    When  the  vessels  are  taken  to  the  burning-kiln,  a 

mixture  of  chloride  of  calciimi,  chloride  of  lead,  and  clay  is  also  introduced  on  a  small 

plate.     The  protoxide  of  cobalt  is  converted  into  a  chloride  by  combining  with  the 

volatilised  materials,  and  in  turn  combines  with  components  of  the  material  of  the 

vessel.     By  this  means  the  articles  obtain  an  apparent  transparency  somewhat  similar 

to  the  characteristic  of  porcelain. 

.  lvium.  Some  kinds  of  ware  have  a  second  coating — a  metallic  lustre  or  glaze — given 
to  them  after  burning.  Gold  Lustre :  The  different  kinds  of  gold  lustre  are  very  similar 
and  need  not  be  detailed.  They  are  essentially  composed  of  fulminating  gold  and  balsam  of 
snlphiir,  the  latter  prepared  by  heating  linseed  oil  and  sulphur  together.  Platinum  Lustre : 
This  is  obtained  by  mixing  anhydrous  chloride  of  platinum  with  lavender  oil  or  balsam  of 
snlphnr ;  also  by  the  well-known  precipitation  of  platinum  by  sal-ammoniac.  Silver 
Lustre  is  either  a  yellow  lustre  or  a  cantharadine  lustre,  so-called  from  its  similarity  in 
appearance  to  th&  wing-case  of  the  Spanish  fly  (CantharU  veticatoria).  Salv£tat  believes 
that  chloride  of  silver  may  be  employed  as  a  yellow  lustre,  similarly  to  gold  preparations. 
The  cantharadine  lustre  is  generaUy  a  yellow  lustre,  the  difference  being  that  it  is  only  used 
iot  white  grounds,  while  the  former  is  employed  for  blue  grounds,  on  which  it  appears 
aUghtly  tinged  witii  green.  Copper  Lustre  is  both  red  and  yellow ;  it  is  used  for  Spanish 
iayenoe  and  Majolica  wares.  It  is  chiefly  formed  by  a  silicate  of  copper.  Oxide  of  lead, 
or  lead-lustre,  is  merely  a  lead-glaze.  Chloride  of  silver  mixed  with  lead-lustre  is  reduced, 
the  result  being  a  deposit  of  a  gold-yellow  or  a  silver- white  colour  according  to  the  propor- 
tion of  silver. 

^  Etnuean  vasei.  The  vases  of  the  old  Romans  were  a  kind  of  fayence  ware,  containing 
iron,  and  formed  of  a  clay  decomposed  by  quartz,  only  slightly  burnt,  sometimes 
unglazed,  sometimes  coated  with  an  easily  fusible  glaze.  These  vases  and  articles  are 
celebrated  more  for  their  beauty  of  form  than  for  any  peculiarity  in  composition,  which 
is  very  analogous  to  the  well-known  delf- ware  of  which  our  table  services  are  made. 

cky  pipM.  In  the  ^nanufacture  of  clay  pipes  there  is  employed  the  beautifully  white 
pipe-clay,  oontaining  neither  iron,  sand,  nor  carbonate  of  lime.  The  clay,  if  pure, 
always  bums  white ;  but  occasionally,  when  a  yellow  colour  appears,  the  clay  is  burned 
for  a  longer  time,  whereby  the  oxide  of  iron  colouring  the  clay  is  removed.  The  pipes  are 
formed  in  a  mould  similar  in  shape  to  the  pipe.  A  roU  of  clay  is  taken,  and  carefully 
spread  out  to  the  length  of  the  pipe.  The  mould  is  constructed  in  two  halves,  hinged 
together  Uke  a  meerschaum  pipe-case,  and  is  generally  of  iron.  The  roll  of  clay  is  placed 
on  the  lower  half  of  the  mould,  and  the  upper  half  is  then  pressed  or  screwed  down.  A 
wire  is  then  pushed  up  the  entire  length  of  the  stem.  The  pipe  is  then  taken  out  of  the 
mould,  and  set  aside  to  dry.  It  is  afterwards  taken  to  the  oven,  where  about  a  gross  of 
pipes  are  introduced  into  each  sagger.  The  saggers  are  long  clay  tubes.  Sometimes  the 
pipes  are  burnt  without  saggers.  To  prevent  the  pipe  adhering  to  the  lips  on  account  of 
the  porosity  of  the  clay,  the  end  put  to  the  mouth  is  rubbed  with  a  mixture  of  soap,  wax, 
and  lime-water. 

waurcooien.  The  Spanish  water-cooling  vessels,  or  alcarrazas^  are  made  of  a  porous, 
nnglazed  earthenware.  The  constant  evaporation  of  the  water  exuding  to  the  outer 
surface  of  the  vessel  causes  the  water  to  be  kept  cool  in  the  hottest  climates.  The  vessels 
are^  only  slightly  burnt.  According  to  Sallior,  water  can  be  cooled  15°  in  an  alcarraza,. 
while  Sevres  ware  only  permits  of  the  cooling  of  its  contents  in  a  similar  manner  some 
2*  or  3^  These  vessels  are  known  in  France  as  hydrocSrames.  In  this  country  Egyptian 
wine-  and  butter-coolers  are  very  common,  while  in  Egypt,  Spain,  Turkey,  the  Indies,  and 
Americas,  they  are  really  necessaries.  In  Bengal  these  coolers  are  made  from  the  mud  of 
the  Ganges.  In  the  Levant  they  are  termed  baldaquea ;  in  Syria  and  Egypt  collies  or 
guUieSj  while  in  many  places  they  are  also  known  as  gargoulettes. 


3IO  CHEMICAL   TECHNOLOGY. 

V.  Common  Pottebt. 

Common  Pottwy.  To  dlstiiigaish  between  the  different  kinds  of  this  ware  is  extremely 
difficult.  The  manufacture  is  entirely  distinct  from  the  preceding.  For  the  bo- 
called  white  pottery,  used  for  culinary  purposes,  ordinary  potter's  day  is  employed, 
and  for  brown- wstre  a  moderately  refractory  clay.  The  natural  days  are,  aa  a  mle, 
too  fat  to  be  used  without  the  addition  of  some  other  material,  generally  sand; 
besides  sand,  fire-brick,  chalk,  charmotte,  and  anthradte  coal-ash.  The  yessels 
are  formed  upon  a  potter's  wheel,  air  dried,  and  then  glazed.  The  employment  of  ft 
lead-glaze  was  but  a  short  time  ago  unknown  in  the  glazing  of  this  kind  of  ware. 
Ordinarily  the  mass  is  white  or  yellow,  sometimes  brown-red;  the  glaze  being 
transparent,  the  colour  of  the  body  or  mass  is  always  apparent.  Partly  because  the 
ware  is  very  easily  fusible,  and  partly  because  a  low  heat  is  used  in  the  burning,  the 
glaze  must  also  be  very  easily  fusible.  For  this  reason  a  lead-glaze,  forming  in 
aluminium  and  lead  glass  is  very  applicable,  and  is  employed  mixed  with  loam  (cky 
and  sand) .  The  materials  are  ground  and  veiy  intimately  mixed  in  a  hand-milL  The 
lead  used  is  generally  a  lead-glance.  During  the  burning  the  lead-glanoe  is  roasted, 
and  the  sulphur  is  driven  off  as  sulphurous  add.  The  oxide  of  lead  combines  with 
the  silica  and  alumina  of  the  loam,  or  mixture  of  sand  and  clay,  to  form  alnminiiun 
lead  and  silicate. 

The  glazing  of  the  air-dried  ware  can  be  performed  in  three  ways ;  either  by^  immenioa, 
by  sprinkling,  or  by  dusting.  By  immersion  the  workman's  hands  oome  into  oontMt 
with  the  lead-containing  glaze,  with  detriment  both  to  his  health  and  the  adhering  of  the 
glaze  if  his  hands  should  be  greasy.  This  method  is  not  therefore  often  employed. 
Sprinkling  is  generally  adopted.  In  dusting,  the  ware  is  first  immersed  in  a  pulp  of  fat 
clay,  and  then,  while  still  damp,  dusted  with  the  finely  pulyerised  glaze.  The  danger  of 
this  process  is  the  inhaling  of  the  fine  particles  of  glaze  floating  in  the  air  of  the  irork- 
room.  When  the  oxide  of  lead  is  properly  proportioned  to  the  sUica  of  the  clay  or  loam, 
the  resulting  lead-glass  is  not  affected  by  ordinary  organic  adds.  But  if  the  onde  of  lead 
is  not  well  combined  with  the  silica,  it  will  be  dissolved  by  boiling  vinegar.  The  experi- 
ments of  Buchner,  A.  Vogel,  Erlenmeyer,  and  others,  have  diown  that  Uie  insdability  of 
lead-glaze  is  not  so  great  as  has  been  supposed,  very  dilute  vinegar  in  some  cases  hong 
suffident  to  effect  a  solution.  The  use  of  vessels  thus  glazed  may  therefore  have  no  little 
influence  upon  the  health  of  a  family,  and  it  becomes  necessary  to  consider  if  there  is  not 
some  substitute.  All  injury  likdy  to  accrue  from  the  use  of  this  gisae  would  be  removed 
if  the  potter  would  but  re-bum  imperfect  ware,  or  employ  ovens  of  the  best  oonstmetion ; 
but  this  is  not  always  the  case.  Becently  the  preparation  of  a  glaze  free  from^  lead  has 
been  attempted,  by  employing  water-glass,  or  a  mixture  therewith  of  borate  of  lime. 
Buzning.  The  glazcd  vessehs  are  next  taken  to  the  oven.  This  is  generally  a  rerer- 
beratory  furnace,  2^  to  2f  metres  in  hdght,  and  7  to  zo  metres  in  lengUi.  At  one  end  ia 
the  fire-grate,  and  at  the  other  the  chimney.  The  vessels  are  burnt  without  aaggera,  and 
are  exposed  to  the  full  influence  of  the  flame.  The  fire  is  at  first  kept  low  for  eleven  to 
twelve  hours,  and  then  maintained  strongly  for  four  to  five  hours.  The  vessels  can  be 
removed  from  the  oven  about  eighteen  to  twenty-four  hours  after  being  burnt. 

VI.  Briok-  and  Tile-Maxino,  &o. 

Brkki.  This  manufacture  may  be  said  to  indude  brick-making,  tile-making,  tad 
the  manufacture  of  terxa-cotta  goods,  and  must  not  be  confounded  with  the  andent 
Egyptian  method  of  making  air-dried  bricks,  still  pursued  for  some  minor  puxposes. 
In  order  to  the  better  comprehension  of  the  methods  of  brick-making,  we  will  fint 
consider  the  preparation  of  the  material.    This  may  be  <Jivided  into— 

The  preparation  of  the  clays ; 
The  moulding  of  the  brick ; 
a.  By  hand, 
/3.  By  machinery ; 
The  burning  of  the  dried  brick. 


EARTHENWARE.  3" 

Tnn-cMta.  The  term  terra-cotta  ware  generally  inclades  the  hiimt,  nnglazed 
yellow  or  red  clay  ware,  and  also  tiles,  employed  in  building  and  architectural 
ornamentation.  The  preparation  of  this  ware  is  almost  entirely  mechanical,  and 
does  not  call  for  any  further  elucidation  in  this  work  than,  will  be  found  in  the 
foUowing  pages  descriptive  of  the  class  of  manufacture  to  which  it  belongs. 

Biiek  XBtaUL      Various  clays  are  used  in  brick -making.     Usually  those  only  are 
selected  that  will  form  a  brick  capable  of  bearing  a  considerable  strain.    In  the 
burning  a  test-brick  is  employed,  which  is  removed  from  time  to  time  to  see  the 
progress  of  the  fire,  to  prevent  the  over-burning  of  the  bricks;  or  the  lowering  of  the 
fire  till  the  bricks  are  sufficiently  burnt ;  but  this  brick  must  not  be  confounded 
with  another  test-brick  for  the  following  purpose.    A  brick  is  made  of  any  new  clay 
to  be  tested,  and  is  set  apart  in  an  active  kiln,  being  burnt  at  the  same  temperature 
as  the  bricks  of  this  kiln  afterwards  sent  into  the  trade.    By  the  qualities  of  this 
test-brick  the  nature  and  worth  of  the  new  clay  is  judged.    A  batch  of  bricks  should 
be  composed  of  clays  that  may  all  be  burnt  at  the  same  temperature,  else  very 
unequal  results  will  follow ;  some  bricks  will  be  under-burnt  and  some  over-burnt, 
while  only  those  bricks  to  the  clay  of  which  the  temperature  is  adapted  will  be  of  use 
oommercially.    A  brick-clay  containing  much  carbonate  of  lime  can  be  burnt  at  a 
very  low  temperature,  and  indeed  bricks  so  composed  are  very  solid,  and  have  great 
durability.    Brick-clays  often  contaiu  felspar,  mica,  hydrate  of  oxide  of  iron,  phos- 
phate of  iron,  besides  organic  matter.    When  these  are  not  in  large  quantities  their 
presence  is  not  detrimental.    Mica  and  felspar  with  oxide  of  iron  act  as  fluxes,  and 
in  known  quantities  are  useful  rather  than  pernicious.     Flint  stones,  large  pieces  of 
carbonate  of  lime  and  gypsum  interfere  with  the  easy  applicability  of  brick-clays. 
Sulphur  pyrites  render  clays  unsuited  to  the  manufacture  of  bricks,  as  the  sulphuret 
of  iron  remaining  in  the  brick  after  burning  oxidises  in  the  air  to  sulphate,  which  in 
a  short  time  weathers  out  and  renders  the  brick  brittle.    In  the  Netherlands,  in  the 
Thames  near  London,  on  the  banks  of  the  Ganges  and  Nile,  in  the  mouths  of  rivers, 
and  in  nearly  all  days  exposed  to  the  ebb  and  flow  of  water,  is  found  an  admirable 
material  for  brick-making.      Since  1852  a  mixture  of  lime,  river  sand,  and  water  ha.s 
been  extensively  used  as  a  brick  material,  and  for  other  building  purposes. 

Fnpwationof  ttwctayi.  The  excavating  of  the  olay  for  making  bricks  is  carried  on  in  the 
summer  or  spring.  The  clay  is  placed  in  not  too  high  a  layer,  and  allowed  to  weather. 
It  is  very  advantageous  if,  during  the  weathering,  a  frost  sets  in.  The  clay  is  allowed  to 
reonain  thus  exposed  to  atmospheric  influence  until  it  becomes  boggy  or  marshy.  In  this 
eondition  it  is  brought  to  a  tank  dug  in  the  ground,  4  metres  long,  2  metres  broad, 
and  z'3  metres  in  depth,  where  it  is  mixed  with  about  as  much  water  as  will  stand  to  a 
height  of  6  centimetres  in  the  tank.  So  soon  as  the  olay  is  thoroughly  saturated  it  is 
treadled,  that  is,  the  brick-maker  fastens  boards  or  wooden  shoes  to  his  feet,  and  care- 
fully treads  over  the  olay,  picking  out  all  the  flints,  <&c.,  which  resist  the  passage  of  his 
foot  to  the  bottom  of  the  layer.  This  process  is  repeated  two  or  three  times.  Sand  is 
then  added  to  the  olay.  If  the  olay  is  fat  the  mixture  is  proceeded  with ;  but  if  it  is  a 
poor  olay  it  is  advantageous  to  wash  out  a  portion  of  the  sand.  This  may  be  effected  in 
two  ways.  The  ground-tank  just  described  may  be  inundated  with  water,  and  the  sand 
allowea  to  settle  to  the  bottom ;  or  the  mixed  sand  and  clay  is  placed  in  a  large  wooden 
tub  with  a  hole  in  the  side  near  the  bottom  stopped  witl^  a  plug.  When  the  water  has 
thoroughly  impregnated  the  clay  it  is  let  off,  carrying  part  of  the  sand  with  it.  Or  the  clay 
is  stirred  with  the  water  to  a  thin  pulp,  and  allowed  to  run  out  of  the  wooden  cistern 
into  a  ground  tank,  where,  with  the  water,  the  sand  settles  to  the  bottom.  London  clay, 
being  mostly  alluvial,  has  to  be  very  carefully  treated  to  free  it  from  flint  stones,  Ac. ; 
it  is  afterwards  mixed  with  ash  or  sand. 

The  '*  treading  "  of  the  olay  is  at  the  present  time  performed  in  mills,  termed  *'  pug  " 
mills  and  **  washers."    At  the  late  International  Exhibition  (1871)  several  machines  were 


312 


CHEMICAL  TECHNOLOGY. 


exhibited  for  performing  the  whole  process  of  briok-making  oontinnonsly.    Among  thsM 

was  the  three-process  brick-makiiig  machine  of  Messrs.  Clayton,  Son,  and  Hewlett,  of 

the  Atlas  Works,  and  combining  at  one  operation  crashing,  pngging,  and  brick-maldiig. 

The  rough  clay  is  thrown  into  the  hopper  of  the  machine ;  in  this  hopper  rsTolves  a 

shaft,  upon  which  are  'keyed  several  small  kniyes  to  cnt  up  the  day  preyionsly  to  its 

being  crushed.     It  next  passes  through  a  pair  of  crushing  rollers,  and  these  effectually 

reduce  any  stones  or  hard  lumps  of  clay  which  may  enter.     The  clay,  thus  partially 

prepared,  next  passes  into  a  horizontal  pugging  or  mixing  cylinder  situated  beneath, 

where  it  is  mixed  by  the  pug-kniyes  fixed  upon  the  central  sh^t.   The  kniyes  force  the  day 

towards  the  further  end  of  the  cylinder,  where  it  is  received  by  rollers  and  forced  through 

the  dies,  forming  a  smooth  bar  of  clay  of  the  width  and  depth  of  a  brick.    This  bar  is 

cut  into  the  required  lengths  by  wires.    The  machine  is  capable  of  produdng  20,000  to 

30,000  bricks  per  diem,  and  is,  perhaps,  the  best  of  its  class.    Mr.  Bawden  has  constructed 

a  machine  in  which  no  rollers  or  crushers  are  employed,  the  clay  being  turned  out  as 

wet  and  as  soft  as  in  hand-moulding.  One  horse  will  pug  the  clay  and  mould  from  12,000  to 

15,000  bricks  per  day.  It  consists  of  a  square  pug-mill,  through  which  runs  a  vertical  shaft 

bearing  pug-knives.    On  the  top  of  this  shaft,  above  its  bearing,  is  attached  the  horse-pole, 

which  gives  motion  to  the  whole  machine.    Upon  the  lower  end  of  the  ^aft,  which 

passes  through  the  bottom  of  the  pug-mill,  is  a  wheel  having  two  cams,  on  which  two 

rocking  arms  work.    One  arm  presses  the  soft  clay  through  a  grating  into  a  six-briek 

sanded  mould,  and  the  other  arm  is  connected  to  a  slide  for  pushing  the  empty  sanded 

moulds  under  the  grate,  the  empty  mould  at  the  same  time  pushing  the  fuU  one  oat. 

Among  the  best  continental  machines  are  those  of  Henschel  of  Cassel,  and  of  Earrens. 

Moulding  th«Biiok.      The  moulding  of  the  brick  by  hand  is  a  veiy  simple  matter.    A 

mould  of  wood  or  cast-iron  sufficiently  large  to  allow  for  the  shrinkage  of  the 

material  during  burning  is  usually  employed.    Fig.  156  shows  the  plan  (b),  and  the 

section  (a),  of  the    mould.     Sometimes  it  is   made  so   that  two  bricks  can  be 

moulded  at  the  same  time,  Fig.  157.    The  moulder  takes  a  ball  of  clay  and  places  it 

in  a  sand-strewn  mould,  pressing  it  well  in.    Then  with  the  striker,  a,  Fig.  i58> 

he  removes  the  superfluous  clay.    The  mould  is  then  emptied,  and  the  brick  placed 


Fig.  156. 

amziD 


Fig.  157. 


Fig.  158. 


3 


IB 
] 


/ 


by  a  child  on  a  barrow,  to  be  taken  to  some  other  part  of  the  brickfield,  to  be  sun- 
and  air-dried.  The  air-dried  bricks  are  then  taken  to  a  kiln  to  be  burnt.  In  many 
cases  the  bricks  are  dried  by  artificial  heat  in  sheds,  the  floors  of  which  are  heated 
by  fires.  A  gang  of  labourers,  numbering  five  to  ten  persons,  can  at  the  maximum 
produce  only  1000  bricks  per  day. 

Bziek  Moniding  by  Machinery.  The  moulding  of  bricks  by  machinery  is  daily  becoming 
more  general.  A  moulder,  no  matter  how  experienced,  has  never  been  known  to  pro- 
duce more  than  6000  bricks  in  a  day,  and  a  continuity  of  this  labour  would  be  most 
improbable.  Where  there  is  a  large  demand,  it  becomes  necessary  to  produce 
30,ocx)  bricks  per  day  regularly,  and  this  can  be  done  by  machinery,  without 
employing  a  large  number  of  hands.  Further,  the  consumption  of  fuel  in  the 
machine  can  at  once  be  stopped,  or  regulated  to  meet  the  demand,  while  a  large 
number  of  workpeople  cannot  always  be  dealt  with  so  satisfactorily  to  the  well- 
meaning  employer.  But  the  machine  engrosses  a  large  capital  that  is  not  always  to 
be  invested,  whereas  a  number  of  hands  may  be  paid  from  the  result  o'  their  labour, 
if  the  demand  is  good.  It  therefore  does  not  always  happen  that  machinery  can 
compete  with  hand  labour  in  this  particular,  as  there  are,  in  this  trade  espc  ^     . . 


EASTBENWAJtE. 


313 


many  m&ken  vho  pay  as  thej  receive,  sending  oat  the  bricks  as  soon  as  they 
■re  burnt.    The  machlneB  constrncted  may  be  classed  aa  follows: — 

1.  Those  in  which  the  brick  is  moolded  or  finished  as  by  hand. 

2.  The  machines  in  which  the  monlding  proceeds  umnlerruptedlj. 

3.  Those  in  which  the  brick  is  ont  oat  of  a  cake  of  daj. 

4.  Those  in  which  a  band  or  stream  of  claj  of  the  length  and  breadth  of  thA 

brick  is  cut  bj  means  of  knives  or  wires  bi  the  lequisite  depth. 
I,  The  machines  of  the  first  class,  imitating  the  motion  of  the  monlder'a  handa 
ue  constrncted  of  an  iron  monld,  with  machinery  or  arms  having  a  to-and-fro 
motion,  somewhat  similar  to  a  shuttle  in  a  loom.  Such  a  machine  is  that  of  Carville 
of  Issy,  near  Paris  (Fig.  159).  The  brick  material  flows  from  the  pug-mill,  a,  under 
the  press  roller,  b,  which  is  supplied  with  water  from  the  reservoir,  c,  to  prevent  the 
e%  adhering.    Sand  is  next  spread  over  the  clay  from  d.    The  clay  now  arrives 

Pio.  159. 


trader  the  pressing  apparatus  worked  by  the  arm,  r,  and  counterpoise,  o.  The  bricks 
then  pass  away  on  the  endless  band  of  moulds,  i,  to  which  motion  is  imparled  by 
m«ans  of  the  revolving  arms,  11.  The  bricks  in  the  passage  of  the  moulds  over 
these  amjB  are  shot  out,  the  chain  of  moulds  passing  through  the  tank  of  water,  n, 
■nd  thus  being  elesnsed.  u  is  a  box  to  receive  the  waste  clay,  which  is  taken  to  the 
Fid.  160. 


HH 


png-miU.    Fig.  160  is  an  enlarged  view  of  the  chain  of  moulds;  mm  being  the  plan, 
and  the  bn<er  figure  the  side  view. 
,_        IL  The  second  clase  of  mactunes  are  very  similar  to  the  foregoing.     Instead 
.  ike  pressing  apparatus,  a  roller  is  snbstitutod,  which  presses  the  clay  into  the 


314 


CHEMICAL  TECHNOLOGY. 


moulds  as  they  pass  under  it.  The  moulds  sometimes  fonn  the  periphery  ci  s  hrgt 
circle  in  the  horizontal  plane,  as  by  this  means  the  operation  can  be  going  on  under 
several  rollers  at  the  same  time. 

in.  The  machines  of  the  third  class  differ  from  the  preceding  in  that  the  mould 
descends  npon  a  cake  of  clay  of  the  required  thickness.  This  kind  of  machine 
is  generally  used  in  the  mannfiacture  of  ornamental  bricks,  as  by  substitating  other 
moulds  any  desired  pattern  may  be  produced. 

IV.  The  machines  of  the  fourth  class,  in  which  a  band  of  clay  is  divided  in  cross 
section,  may  be  best  considered  under  two  subdivisionSi  the  one  containing  those 
machines  in  which  the  clay  is  forced  through  an  opening  of  the  proper  size,  the  other 
those  in  which  the  clay  is  pressed  by  rollers  into  a  band  of  the  required  dintftDsionH. 
The  separation  is  effected  either  by  a  knife  or  by  cutting  wires.  By  a  method  similar 
to  the  first  process,  drain  pipes  are  manufactured.  The  machine  of  Temsson- 
Foug^res  is  a  very  fair  example  of  the  older  system  of  rolling  the  day.  An  endles 
band,  b,  conveys  the  clay  under  the  press-roller,  a,  Fig.  i6i.  the  motion  being 

Fio.  z6z. 


rrtt 


I 


t 


6 


nS 


xn 


rf-IMEzgE^ 


S 


I 


i^E 


t 


-\ — i-r— I     I      I    \ 


I  i    I   I    rj 


iE^t 


E 


i&i 


continued  by  the  rollers,  d,  and  the  day  kept  to  the  required  breadth  by  the  gtddes, 
c.  Fig.  162  shows  the  cutting  apparatus  mounted  on  a  strong  timber  framework,  o^ 
and  also  on  wheels  for  the  removal  to  any  part  of  the  shed  or  fidd.  It  will  be 
readily  seen  from  the  woodcut  how  the  copper  or  iron  wires  kept  taut  1^  the  wei^t, 
F,  sever  the  band  of  clay. 

Fia.  162. 


Brida  from  Dried  dsy.  Pressed  bricks  are  bricks  pressed  from  dried  day  in  which  the 
natural  moisture  of  the  day  is  all  that  is  employed  to  render  the  briok  coherent.  The 
pressure  must,  therefore,  be  considerably  more  tiian  that  used  in  the  mining  of  moist 
clay  into  bricks ;  but  pressed  bricks  are  much  more  solid  and  firm  than  moist  day  bricks, 
a  smaller  number  making  a  more  secure  walL  One  of  the  most  general  maohmes 
lor  making  this  kind  of  brick  is  that  of  Nasmyth  and  liinton,  in  which  a  peenliar  form  01 


EARTSENWARE.  315 

•Mantrio  Mta  the  moal^  is  aotioD.  tba  sune  mOTSmoit  ot  the  primat^  axis  pnl- 
■  tbe  b1&7,  and  eanaes  it  to  be  toroibly  oompresMd  into  the  mould.  With  thie 
jie  and  with  that  of  Julienne,  who  baa  reoently  made  lome  improvements,  400a 

brieka  can  be  made  daily  with  the  laboiur  of  a  man  and  bo?. 
itm  Bniiiiv  c<  On  Biiiki.      The  bnming  of  the  air-dried  bricke  or  tilea  ia  canied  <m  in 

evens  or  in  kilns.    The  ovens  are  eithar  open  orene,  similar  to  a  blast  fomace, 

«r  Tsolted,  or  orans  in  which  the  burning  is  oontinnons.    The  fuel  is  paitlj  wood. 


partly  tnrf.  brown  ooal,  and  anthracite  or  stone-eoal.  From  the  many  fonns  of 
brick-kilnB  and  ovens,  the  following  are  selected  as  best  conveying  a  clear  idea  of  the 
process.      Fig.  163  is  a  stage-oven,  fuelled  with  wood,  and  consisting  of  three 


■ 

"«-■ 

H                           iti"sm 

■ 

B->« 

eluunben  lying  one  ftbore  the  other,  a,  s,  and  c.  These  floors  can  1m  heated  in  rota- 
tion. The  famaee.  d,  fed  through  the  door,  f,  gives  a  great  length  of  flame,  which 
pwMS  throu^  the  pierced  wall,  i,  into  the  chamber,  1,  and  thence  throngh  the 


3i6 


CHEMICAL  TECBNOLOGT. 


furnace,  h,  fed  throngli  the  door,  a.  The  flame  from  this  hearth  passea  to  the  npper 
chamber,  c,  passing  through  j  and  the  pierced  waJl,  k,  and  erentnall;  by  l  to  ^ 
chimney,  n.  Fig.  164  is  another  section  of  this  fumaoa.  Fig.  165  is  a  plan  of  the 
middle  stage.  This  kind  of  oven  efiects  a  considerable  saving  in  fael,  as  bricks  can  be 
burnt  in  all  the  stages.  One  of  the  most  economical  ovens  burning  wood  fuel  is  shown 
in  section  in  Fig.i66,and  in  plan  in  F^.  167.    There  are  three  fire-places,  ofwhichr 


Fia.  167. 


I 


is  the  middle  one.  The  fire-place  has  no  grating,  but  is  vaulted  in  by  a  series  of  iros 
b&iB,  000,  through  the  interstices  of  which  the  flame  passes  into  the  chamber,  bb. 
open  at  the  top.  The  bricks  to  be  burnt  are  placed  upon  the  bars  000  transverselj, 
spaces  being  left  for  the  passage  of  the  flajnc  snd  hot  gasea.  It  will  be  seen  that  Ibii 
method  of  boming  is  mnch  more  expensive  than  the  foregoing,  owing  to  lk« 
amotmt  of  heat  wasted;  while  wood  as  a  fuel  b  naturally  more  expensive  thsa 

Fig.  16S. 


stone-coal,  to  produce  the  same  amount  of  heat.  With  the  form  of  oven  designed  hr 
Carville,  and  sliown  in  Figs.  168  and  169, 80,000  bricks  can  be  burnt  with  160  hecto- 
litres of  stone-coal.  Thus,  as  i  hectolitre  of  stone-coal  weighs  80  Idloa.,  tnd 
as  100  kilos,  of  coal  cost  3  francs  12  cents.,  the  burning  oi  the  80,000  brickfl  can  b« 
effected  at  a  cost  of  400  franca  (f  16).  Stone-coal  may  be  burnt  in  the  oven  shown 
in  Fig.  170.  The  capacity  of  this  oven  is  limited  only  by  the  enclosing  walla,  bb,  et 
thick  masonry.    The  bricks  to  be  burnt  are  placed  up<m  the  sole  of  the  oven,  c, 


EARTREXWAItE.  317 

frhich  is  conetracted  to  admit  of  the  free  circolation  of  the  products  of  combnslioa. 
Fig.  171  shoiTB  the  method  of  placing  the  bricks  in  the  oven;  and  Fig.  172,  a  plan, 
the  two  hearths,  db. 


ntmi 


Fio.  I,,. 

hi 

" 

Manj  experiments  have  been  made  with  Hie  view  of  combining  the  burning  of 
lime  with  the  burning  or  baking  of  the  bricks.  Figs.  173  and  174  show  an  oven 
built  for  this  purpose.  The  sole  of  the  chamber,  a,  is  covered  with  limestone,  which 
is  bnmt  equally  with  the  bricks  placed  above  it.  The  draught  is  regulated  by 
the  dampers  in  tlie  chinmej,  b.  and  bj  the  openings,  c.  The  six  fire-rooms  are  eepa- 
nted  from  each  other  by  the  blocks  of  strong  masoniy,  d  and  o.  The  fuel  is  placed 
in  the  furnace,  e,  under  which  is  the  ash-pit,  f. 


Fio.  173. 


Pio.  174. 


H.„ 


% 


l-.i^ 


AnniiiiLt  Kn™.  The  circular  or  annular  kilns  of  Hoffinann  and  Licht,  are  much  used. 
These  (rvens  an  in  plan  in  the  form  of  a  ring,  capped  by  a  chinmey.  In  each  oven 
there  are  a  nnmber  of  chambers  in  wliicb  the  bricks  are  stacked.  One' of  these 
chambers  ia  filled  with  what  are  termed  green  bricks,  that  is  bricks  fresh  from  the 
field.  The  fire  being  applied,  the  steam  passes  off  to  the  chimney.  The  second 
chamber  is  then  filled  with  bricks ;  and  when  the  steam  has  passed  off  from  the  first 
chamber,  the  products  of  combustion  there  are  admitted  to  the  second  chamber 
through  flites  in  the  partition  wall.  Tliis  process  is  repeated  with  each  chamber  in 
succession.  As  soon  as  the  bricks  are  bnmt  the  door  and  flues  of  the  chamber  are 
opened  to  admit  the  cold  air ;  when  cold  the  bricks  are  removed,  and  green  ones  sup- 
plied in  their  place.  It  is  clear  that  by  this  means  there  need  be  no  interruption  in 
the  burning ;  and  also  that— 


3i8  CHEMICAL  TECHNOLOGY, 

a.  As  the  doors  and  fines  are  opened  in  the  chamber  in  which  die  bricks  have  beeo 
finally  burnt,  the  air  entering  is  highly  heated. 

h.  The  effect  being  to  augment  the  heat  of  the  next  chamber ;  while 

c.  This  heat  can  be  so  proportioned  out  to  the  imbnmt  bricks  as  to  render  only  a 
very  short  actual  firing  necessary. 

The  saving  of  fuel  by  the  use  of  these  kilns  mnst  be  evident.  Also  from  the  can- 
tinuity  of  the  firing,  which  in  practice  is  never  allowed  to  go  out,  the  ovens  or 
chambers  never  get  perfectly  cold,  and  are  consequently  soon  re-heated. 

Field  Bnxnimc.  In  coutrast  to  the  permanent  kiln  is  the  field-kiln,  in  which  bricks  or 
tiles  are  burnt  at  the  same  place  that  building  is  going  on,  or  where  a  sufficiency  of 
brick-clay  is  likely  to  yield  a  good  retnm.  Bricks  burnt  in  these  temporary  kilns 
are  termed  Jield-bricks.  The  fuel  employed  is  either  turf,  wood,  or  stone-coaL  When 
turf  or  wood  is  used,  the  bricks  are  stacked  similarly  to  the  method  employed  in 
ovens  in  which  these  fuels  are  the  firing  materials.  Flues  are  constructed  in  these 
kilns  of  the  bricks  themselves  set.in  a  thin  layer  of  lime ;  while  the  wind-side  of  the 
stack  is  covered  with  hurdles  thatched  with  straw.  50,000  bricks  can  thus  be  burnt 
at  one  firing.  The  flames  and  hot  gases  find  their  way  hither  and  thither  in  the 
stack,  and  finally  escape  at  the  top.  By  the  time  that  the  outer  bricks  are  hot,  the 
interior  of  the  stack  or  kiln  has  reached  a  veiy  high  temperature.  When  coal  is 
employed  tiie  bricks  are  laid  alternately  with  a  layer  of  coal,  a  layer  of  lime  serving 
as  an  outside  cover,  in  which  draught  Iioles  are  made  to  regulate  the  burning. 
When  the  kiln  is  built  the  firing  is  commenced,  and  gradually  extends  to  the 
several  layers  of  coal  untU  all  is  burnt.  The  kiln,  consequently  upon  the  consump- 
tion of  the  coal,  falls  or  sinks  together,  a  matter  of  no  importance. 

Dntoh  GUnkon.  Hollanders,  or  Dutch  clinkers,  are  a  very  hard,  Bemi-glazed  brick,  of  a 
green  or  dark  brown  colour,  aud  poBsessing  the  property  of  not  absorbing  water.  ^ 

Booflng  and  Dutch  TUes.  For  the  manufacture  of  tiles  a  better  and  more  oarefully^selectid 
day  than  that  for  ordinary  bricks  is  employed.  While  '*  treading*'  is  much  used 
in  the  making  of  bricks,  a  null  is  always  considered  necessary  for  tiles.  As  a  rule  thqr 
are  burnt  at  the  same  time  as  bricks ;  the  upper  part  of  the  oven  being  sufficiently  heated 
for  the  purpose,  owing  to  their  thumess.  When  it  is  desired  that  the  tiles  should  be  of  a 
gray  colour,  there  is  added  to  the  fire,  while  the  tiles  are  at  a  red  heat,  a  quantity  of  leaves 
and  damp  twigs.  By  this  means  large  volumes  of  smoke  are  disengaged,  and  pass  into 
the  interior  of  the  k^,  where  the  pores  of  the  tiles  absorb  the  carbon,  which  imparts  the 
gray  colour  remaining  on  cooling.  Similarly  the  dark  green  colour  results  from  the 
reduction  of  the  peroxide  of  iron  to  black  oxide  and  protoxide.  Flat  tiles  are  mostly  used 
for  paving  purposes.  Roofing  tiles  are  made  in  many  shapes ;  some  with  a  nose  or  pro- 
jectiQg  piece,  with  a  hole  through  which  a  nail  passes  to  fasten  the  tile  to  the  raften ; 
others  without  this  projection,  and  with  a  couple  of  holes  simply.  Bidge  tiles  form  the 
capping  of  pointed  roofs  and  dormer  windows,  &o. 

Drain  and  ontur  Tiiei.  The  uso  of  hollow  tilcs  and  bricks  dates  from  a  very  remote 
period.  Vaulting  tiles  are  no  more  than  hollow  bricks  or  tiles,  employed  to  reduce  the 
weight  of  upper  parts  of  large  arches  or  masses  of  brickwork ;  they  are  2Z  to  24  centi- 
metres ip.  height,  and  9  to  Z2  centimetres  in  ^anieter,  with  the  middle  hollow  and  hard- 
burnt.  A  similar  form  of  pipe  is  used  for  draining  land,  &e.  For  some  purposes,  bricks 
are  constructed  hollow  through  their  width  and  not  through  the  length.  The  advan- 
tages of  hollow  bricks  where  they  are  applicable  are : — z.  That  60  to  70  per  cent  of 
materials  are  saved.  2.  That  they  materially  reduce  the  pressure  by  decreasing  the 
weight  of  superincumbent  masonry.  3.  They  diy  more  equidly,  and  a^nit  of  good  ven- 
tilation. 4.  They  can  be  baked  at  a  lower  temperature,  with  a  saving  of  20  to  30  per 
cent  of  fuel.  5.  The  cost  of  transport  is  less  consequent  upon  the  reduced  wei^^t. 
Figs.  Z75  and  Z76  show  two  kinds  of  hollow  tiling. 

Floating  Brieka.  Floating  bricks,  or  bricks  sufficiently  light  to  float  upon  water,  are  of 
very  ancient  date.  Posidonius,  and  after  him  Strabo,  state  that  a  peculiarly  argillaceous 
earth  was  brought  from  Spain,  which  was  used  to  polish  silver,  and  from  which  bricks 
could  be  made  that  would  float  upon  water.  Further,  that  these  bricks  were  made  in 
several  parts  of  Asia,  and  on  an  island  of  the  Tyrian  Sea.    Yitruvius  Pellio  thought 


EARTHENWARE. 


3>9 


th«M  btkki  t«  be  made  of  a  veiy  light  unknown  stone ;  and  Plin;  likens  it  to  pnmiofl 
•tooe.  Bat  the  Bocrat  romained  hidden  lor  a  thonaand  years,  until  Giovanne  Fabroni,  in 
1791,  after  many  eipBiimentB,  Bnooeeded  in  prodocing  ft  brick  that  wonld  remain  on  the 
toifaoe  ol  water.  The  material  employed  was  fossil  meal,  found  near  Santafiora  in  Tos- 
cany.  It  was  oapabJe  ef  combining  with  lime  mortar,  resiHtod  water,  and  was  nnaltered 
by  ruiition  in  temperatore.  The  strength  of  these  brisks  was  scarcely  inferior  to  that 
of  ordinary  brieks,  and  greatly  more  in  tha  proportion  of  their  weight.  Fabroni,  as  an 
etperinient,  congtmoted  the  powder  magazine  of  a  wooden  ship  of  these  bricka ;  and  tha 
Twsel.  being  sat  on  &re,  sank  before  the  explosion  of  the  powder.    About  the  same  time, 

FiQ.  175,  Fio.  176. 


9% 

;^>^ 

P 

r^^^l 

S^ 

3^S^ 

asB 
ana 


Fanjei,  ol  Coiion,  Franoe,  lonnd  a  foiril  meal  poaiessing  the  properties  of  that  foond  in 
Taseany ;  and  in  1831,  the  Ubonri  of  the  Cotmt  de  Nantes,  and  of  Foomet,  a  mining 
engineer  ot  Lyoiu,  found  an  applieation  for  tbeee  brioks.  The  powder  magazioes, 
the  cooking  gsJleys,  the  hearth  of  the  steam  engine,  the  fines,  the  spirit-room  on  boud 
■hip  can  all  be  made  of  these  brieka,  and  the  chances  of  fire  rednced.  This  kind 
of  brick  is  also  nsefol  for  the  Tanits  of  ovens,  &o.,  in  which  a  high  teibperatare  is  main- 
tuned,  as  thej  are  infasibla.  Kiitzing  found  that  these  bricks  contained  immense 
numbers  of  the  microscopic  silieeous  shells  of  infusoria.  While  an  ordinary  brick 
i^bs  1-^0  kiloB.,  the  wngbt  of  an  equal  bulk  of  this  infusoria  cUy  is  only  0-43  kilos. 
Coated  with  wax  it  swam  like  a  cork.  The  attongeet  porcelain -oven  fln  was  without 
effect  upon  it.  By  the  addition  of  elay  or  lime  the  fimmess  and  tenacity  of  an  ordinaiy 
brick  was  obt^ned. 

Ordinary  porous  bricks  are  made  by  adding  to  the  clay,  coal-dnst.  aawdiut,  toif,  tan, 
Ac  Light  bricks  were  nsad  for  building  pQiposes  in  Nuremborg  in  ibe  nib  and  15th 
centarieg.  Chimnies  were  built  of  them.  In  Southern  Bavaria,  a  light  brick  made  from 
a  miitwe  of  tnrf  and  sand  lime  has  been  in  use  for  many  years. 

ntt-BHita.  Fire-bricks,  or  bricks  made  with  fire-clay,  are  employed  instead  of 
ordinarj  bricks  in  the  construction  of  fitmaces,  and  all  places  exposed  to  an 
exceedingly  high  temperature,  which  would  melt  tlie  common  brick.  These  bricks 
ciHit^  siliea  and  alumina,  but  little  or  no  lime,  protoxide  of  iron,  or  alkalies ;  while 
the  clay,  to  prevent  contraction  in  buming,  is  mixed  wiQi  already  burnt  clay,  sand, 
cai'bon  (coal,  coke),  &c. 

The  process  of  numnfacturing  fire-bricks  at  Stourbridge  ie  so  admirably  deseribed 
in  Lieutenant  Graver's  "  Report  on  Fire-clay  Ooods"  in  the  International  Exhibi- 
tioo  of  1871,  that  the  particulars  may  be  quoted  in  exUnto.  "  The  clay,"  he  says, 
"  is  firstly  exposed  in  spoil  heaps  over  as  large  an  area  as  can  be  secured,  for  from 
J  to  18  montha,  according  to  the  state  of  the  weather.  The  actioa  of  frost,  aa  with 
ordioaiy  brick  earth,  is  of  great  service  in  disint^rating  the  compact  ton^  lumps  of 
clay,  and  in  dry  weather  the  clay  is  frequently  watered.  In  very  wet  weather,  a 
3  moBtha'  exposure  will  suffice  for  its  proper  'mellowing'  or  '  ripening,'  and  it  ulti- 
niately  slacks  and  &lis  to  pieces.  When  new,  it  is  termed,  in  the  local  phraseology, 
'short  and  rough;'  after  due  exposure  it  becomes  'mild  and  tough.'  On  some  of 
the  works  the  spoil  heaps  of  clay  contain  over  10,000  tons,  and  it  is  estimated  that 
7  tons  measure  about  6  cnbic  yards.    After  sufficient  weathering,  the  clay  is  ground 


320  CHEMICAL   TECHNOLOGY. 

in  a  circular  pan  by  two  rollers  or  cylindrical  stones,  shod  with  iron  rims  2i  inches 
thick,  and  weighing  from  2  J  to  3 i  tons  a-piece.    After  being  ground,  the  clay  is  car- 
ried on  an  endless  band  to  a  '  riddle'  of  about  4  or  6  mesh  to  the  inch  for  fire-bricks, 
6  or  ID  for  fine  cement  clay,  and  12  or  14  mesh  to  the  inch  for  glass-house  pot-clsy, 
the  larger  sized  mesh  being  used  for  the  sifting  of  the  clay  in  wet  weather.  \The 
large  particles  which  will  not  pass  thi'ough  the  '  riddle  '  are  carried  back^on  an  end- 
less band  to  the  pan,  and  there  re-ground.    As  a  general  rule,  it  is  only  for  very 
large  fire-brick  lumps,  that  re-ground  pots,  crucibles,  or  bricks — ^locally  termed 
*grogg' — are  added  to  the  clay  before  grinding;   and  fire -cement  clay  is  always 
ground  pure.    After  passing  through  the  *  riddle,'  the  clay  is  tempered,  or  brought  to 
a  proper  degree  of  plasticity  by  the  addition  of  water.    It  is  then^thoroughly  stirred 
and  kneaded  in  a  circular  cast-iron  pug-mUl,  by  revohing  knives  projecting  from  a 
vertical  shaft  driven  by  steam-power.    The  clay  is  forced  down  by  the  obliquity  of 
the  rotating  knives,  and  streams  slowly  from  a  hole  near  the  bottom,  whence  after 
being  cut  by  wires  into  the  proper  forms,  it  travels  on  in  an  endless  band  to  the 
moulding  sheds.      The  bricks  are  then  moulded  by  hand  in  the  usual  manner, 
and  dried  at  a  temperature  of  60  or  70  degrees,  in  sheds  about  120  feet  long  and  30 
feet  wide,  beneath  whose  floors  run  longitudinally  two  flues.    In  fine  weather,  how- 
ever, the  sun's  heat  is  made  to  economise  fueL    The  bricks  are  burnt  in  circular- 
domed  kilns  or  cupolas,  locally  termed  *  ovens,'  where  they  remain  for  from  eight  to 
/ourteen  days,  being  fired  with  the  real  intensity  of  flame  or  white  heat,  for  about 
four  days  and  three  nights.   They  usually  require  seven  days  to  cool  down.  The  fire 
is  slowly  increased  and  gradually  lowered,  the  time  of  burning  being  regulated 
by  the  kilnman  in  charge,  who  inspects  the  baking  bricks  from  time  to  time  through 
holes  in  the  domed  roof  of  the  '.oven.'    The  chimney  stack  is  on  the  outside  of  the 
kiln,  and  the  flame  burns  with  a  down  draught,  descending  through  holes  in 
the  floor,  the  fire-holes  being  merely  openings  left  in  the  thickness  of  the  wall  of  the 
kiln,  and  protected  from  the  wind  by  buttresses  long  enough  to  allow  room  for 
the  firemen  to  attend  the  fires.    The  coal  is  of  course  obtained  from  the  pits  which 
provide  the  clay.    Most  of  the  kilns  hold  each  12,000  bricks,  but  some  are  krge 
enough  to  contain  each  30,000  or  35,000  bricks,  the  capacity  of  a  kiln  being  rou^y 
calculated  upon  the  assumption  that  ten  bricks  require  one  cubic  foot  of  space  in  the 
kiln." 

Some  analyses  of  fire-clay  were  given  when  treating  of  the  different  kinds  of  day. 
Several  analyses  of  fire-bricks  are  as  follows : — 


z. 

2. 

3. 

4- 

5- 

Silica    ... 

... 

•  ••         •t 

..     6309 

881 

8843 

693 

776 

Alumina 

... 

•  •  •         •  1 

..     2909 

4*5 

690 

295 

190 

Lime 

••• 

042 

1-2 

340 

— 

Magnesia 

... 

..      066 

— 

— 

— 

28 

Oxide  of  iron 

•  •  •         • 

..      2-88 

61 

150 

20 

03 

Potash  ... 

... 

1*92 

— 

— 

— 

— 

Soda     ... 

... 

..      0-31 

— . 

— 

— 

— 

Titanic  acic 

I  ... 

2*21 

— 

— 

— 

— 

• 

lOO'OO  lOO'O  lOOOO         .    lOO'O  1000 


I.  Clay  from  Dowlais.    2.  Brick  from  copper-smelting  furnace  in  Wales.    3.  In  Pem- 
broke.   4.  Brick  from  a  blast-furnace.    5.  Brick  from  a  reverberatozy  fomaoe. 


EARTHENWARE.  321 

Dinas  brioks  are  made  from  material  obtained  from  the  Yale  of  Neath,  in  Glamorgan- 
shire ;  but  they  haye  been  imitated  in  Germany  by  a  mixture  of  pure  quartz-sand  with 
z  per  cent  lime.  Dr.  Siemens,  F.B.S.,  says  of  these  bricks — **  Welsh  Dinas  brick,  con- 
sisting of  nearly  pure  silica,  is  the  only  material  of  those  practically  available  on  a  large 
scale  that  I  have  found  to  resist  the  intense  heat  (4000°  F.)  at  which  steel-smelting 
furnaces  are  worked."  Messrs.  Martin  Brothers,  of  Lee  Moor,  Plympton,  have  made  some 
bricks  from  the  refuse  of  kaolin,  or  china  clay,  mixed  with  quartz-sand,  carefully  selected 
and  washed.  The  kaolin  is  found  in  Cornwall  and  Devonshire,  and  is  produced  l)y  the 
disintegration  of  pegmatite  or  felspathic  granite,  xmder  the  action  of  the  atmosphere  ;  it 
then  becomes  a  basic  silicate  of  alumina.  The  following  are  some  analyses  of  these 
kaolinitic  bricks ;  they  possess  remarkably  high  refractory  power  from  the  small  quantity 
of  iron  contained : — 

Silica       75-89  75-36  73-50  76-70 

Alumina 21*61  21*47  22*70  20*10 

Peroxide  of  iron    ..     ..  1*96  1*79  1*70  1*70 

Alkalies,  waste,  &o.      ..  0*50  1*38  2*10  1*50 

Z00*00      100*00      lOO'OO      lOO'OO 

SuduryWaxe.  Sanitary  ware  is  one  of  the  largest  branches  of  stoneware  manufacture. 
Stoneware  is  admirably  adapted  for  employment  wheru  an  impermeable  and  water-tight 
body  is  desired,  as  in  drains,  sewers,  subways,  &c.  Formerly,  when  about  thirty  years 
ago  the  manufacture  of  stoneware  drains  was  commenced,  the  processes  were  all  manual, 
and  consisted  in  building  up  the  large  pipes  or  tubes  section  by  soction  on  a  strong 
potter's  wheel.  But  machinery  now  effects  the  formation  of  this  ware  with  a  great 
economy  of  time  and  labour.  The  clay  is  placed  in  a  strong  cylinder  of  iron,  in  the 
bottom  of  which  is  a  circular  opening  corresponding  with  the  solid  section  of  the  pipe  ;  an 
iron  piston,  driven  by  steam,  dcBcends,  forcing  the  clay  through  this  opening.  By  this 
means  the  pipe  is  formed :  the  socket  or  joint  is  generally  added  on  a  wheel.  Bends,  for 
the  taming  of  the  corners  of  streets,  Ac^  are  made  by  simply  bending  the  pipe  by  hand 
as  it  is  squeezed  out  of  the  machine.  Messrs.  Clayton,  Williams,  Whitehead,  and  Ainslie 
are  among  the  most  celebrated  manufacturers  of  these  machines.  Messrs.  Clayton 
recently  exhibited,  at  the  International  Exhibition,  a  small  machine  working  on  the  prin- 
ciple just  described,  that  can  be  manipulated  by  a  man  and  a  boy. 

ctadbiM.  For  crucibles  it  is  necessary  that  materials  shall  be  used  that  will  with- 
stand the  highest  temperature.  Good  crucibles  do  not  crack  on  being  rapidly  cooled, 
and  they  must  also  witlistand  the  action  of  the  fluxes  that  may  result  fiom  the 
smelting  of  metals.  The  most  common  crucibles  are  the  Hessian,  the  graphite  or 
plumbago,  and  the  English.  The  Hessian  crucible  is  made  of  i  part  clay  (of  71  parts 
silica,  25  parts  alumina,  and  4  oxide  of  iron)  and  one-half  to  one-tliird  the  weight  of 
quartz-sand.  Xhey  are  refractoiy,  remain  unaltered  by  variations  in  temperature, 
but  are  unsnited  to  some  chemical  operations  on  account  of  coarseness  of  grain  and 
porosity.  If  containing  too  large  a  proportion  of  silica,  they  become  perforated  by 
oxide  of  lead,  alkalies,  &c.  Graphite  or  plumbago  crucibles  are  made  from  i  part 
of  refractory  clay  and  3  to  4  parts  graphite.  The  Patent  Plumbago  Crucible  Company 
of  Battersea,  as  well  as  tlie  Nuremberg  manufacturers,  employ  Ceylon  graphite  and 
fire-claj.  Graphite  crucibles  will  bear  the  highest  temperature,  and  they  can  be 
made  to  almost  any  required  size.  English  crucibles  are  made  from  2  parts  of 
Stourbridge  clay  and  i  part  of  coke.  Cmcibles  containing  coal  become  reduced 
when  heated  in  contact  T^nth  metallic  oxides,  and  are  therefore  unfitted  to  the 
smelting  of  metals.  Recently  lime  and  chalk  crucibles  have  been  employed  for  this 
purpose.  Caron  has  used  magnesia  crucibles  in  the  smelting  of  iron  and  steel. 
Gaudin  employs  an  equal  mixture  of  bauxite  or  cryolite  and  magnesia.  Very  similar 
are  the  bauxite  crucibles  of  Andouin. 


3ai  CHEMICAL  TECHNOLOGY. 


Lime  and  Lime-Bubnino. 

Lim*.  Lime,  protoxide  of  calcium  (CaO= 56) ,  in  its  combination  with  caxbonic  add 
as  carbonate  of  lime  (CaC03)  is  a  substance  of  the  most  frequent  occurrence.  It 
is  a  constituent  of  bone,  of  the  shells  of  the  mollusca,  and  is  found  most  extensively 
in  the  mineral  kingdom  as  marble,  limestone,  coral,  Iceland  spar,  arragonite, 
chalk,  &c.  Its  technical  applications  are  as  marble  in  building,  in  the  manufacture 
of  artificial  mineral  waters,  as  Iceland  spar  for  optical  purposes,  as  chalk  in  colours 
and  drawing  materials,  in  the  manufacture  of  soda,  in  the  preparation  of  hjdraulie 
mortars,  building  and  plastering  materials,  &c.  Limestone,  Alpen  lime,  lias  lime, 
Jura  lime,  &c.,  is,  when  mixed  with  clay,  iron,  and  other  metallic  oxides,  used  as  a 
colour.  Lithographic  stone  is  a  yellow- white  limestone,  employed  as  its  nameimpHes, 
in  lithography.  Chalk  or  earthy  carbonate  of  lime  occurs  in  strata  in  North 
Germany,  Denmark,  France,  and  England.  To  this  class  belongs  marl-limestone, 
distinguished  by  containing  clay.  With  carbonate  of  soda,  carbonate  of  hme 
forms  Gay-Lusaite  (CaCOg+NaaCOg) ;  with  carbonate  of  baryta,  baryto-calcite 
(CaG03-|-BaG03) ;  and  with  carbonate  of  magnesia,  bitter-spar  or  dolomite 
(CaC03-f-MgC03),  the  latter  occurring  with  3  molecules  of  carbonate  of  magnesia 
to  I  molecule  of  carbonate  of  lime. 

Properties.  Carbonate  of  lime  is  not  soluble  in  pure  water;  but  if  the  water 
should  hold  carbonic  acid  in  solution,  bicarbonate  of  lime  is  formed.  When  th^ 
solution  by  means  of  evaporation  loses  half  its  carbonic  acid,  an  insoluble  carbonate 
is  formed.  In  this  manner  are  naturally  formed  stcUactites  and  stalagmitei.  The 
deposit  of  calc-sinter  upon  objects  deposited  in  caverns,  in  limestone-rock,  &c.,  is 
thus  explained.  When  carbonate  of  lime  is  ignited  to  whiteness  in  a  porcelain 
crucible,  the  carbonic  acid  is  disengaged,  and  there  remains  protoxide  of  caldnm 
(CaO)  or  caustic  lime.  100  parts  of  carbonate  of  lime  yield  56  parts  of  burnt 
lime.  The  volume  of  the  lime  undergoes  no  diminution  by  burning.  Burnt  lime  is 
the  form  under  which  lime  most  commonly  appears  in  the  market.  Carbonate  of 
lime,  heated  in  a  closed  porcelain  tube,  melts,  and  forms  a  crystalline  mass,  a 
carbonate,  afterwards  unalterable. 

LisM-BiiniBc.      The  burning  of  the  lime  is  effected — 

In  kilns. 

In  field-ovens,  and 

In  lime-ovens. 

lime-burning  in  kilns  is  accomplished  in  the  following  manner : — The  limestone, 
unless  it  has  previously  been  broken  into  small  pieces,  is  heaped  up  into  cairns  similtf 
to  the  heaps  of  wood  to  be  converted  into  charcoal.  The  kiln  is  then  covered  with 
earth  or  turf,  and  the  fire  so  placed  that  the  larger  pieces  of  lime  in  the  interior  of 
the  heap  are  burnt.  The  regulating  of  the  draught,  the  kindling,  the  coTezing,  and 
the  cooling,  are  on  the  same  principle  as  that  followed  by  the  charcoal  burner  in  the 
conversion  of  wood  into  charcoal  by  combustion.  According  to  P.  Loss,  a  kiln  of 
this  kind,  45  metres  in  height,  contains  355  cubic  metres  of  lime  as  well  as  26  cubic 
metres  of  lime-dust.  In  the  field-ovens  the  burning  is  similarly  conducted,  bat 
sometimes  on  a  larger  scale,  the  kilns  being  always  temporary.  It  is  easy  to  see 
that  the  burning  in  this  manner  is  only  of  slight  technical  importance ;  besides  the 


LI3tE. 


3»3 


great  waste,  only  a  small  qnantitj  could  be  prodnced  at  an  operation.    Therefore 
pennanentlj  constmcted  ovena  are  employed.     These  are  divided  iaUt — 

a.  Those  kilns  in  which  the  boming  is  interrupted,  or  occasionally  employed 

(the  periodica!  Idln). 

b.  Those  kilns  in  which  the  homing  is  continuous  (the  continuous  kiln). 

In  the  occasional  kiln,  after  the  burning  is  finished,  tlie  kiln  is  cooled,  and  the  time 
then  removed.  In  the  continual  kiln,  on  the  contrary,  the  calcination  is  continuous, 
the  kiln  never  being  allowed  to  cool.  It  is  so  constructed  that  the  burnt  lime  can  be 
removed  and  fresh  limestone  introduced,  without  in  the  least  interrupting  the  process. 
The  continnal  kiln  has  many  recommendationB — among  them  that  of  effecting  a 
saving  in  fuel,  as  use  can  be  made  of  the  refuse  lime  for  this  purpose.  In  a  small 
way,  where,  as  a  rule,  burning  cannot  be  constantly  carried  on,  the  small  occasional 
Mia  is,  of  course,  to  he  preferred. 
SS^T&^  ^*  occasional  or  periodic  kiln  with  interrupted  burnings  have,  or 
sometimes  have  not,  a  grated  furnace.  Figs.  177  and  178  show  two  lime-kilns  of  the 
ordinary  construction  wilhont  grated  furnaces.  They  are  built  either  on  the  slope  of 
a  h'll  or  on  the  slope  of  the  limestone  quany  itself.  As  a  rule  the  kilns  are  built 
near  one  another,  so  that  one  wall  serves  for  two  kilns.  The  height  of  the  vault 
varies  from  13  to  16  metres,  and  it  is  generally  built  of  the  largest  limestones,  while 


the  smaller  stones  and  lime-dust  are  placed  in  the  interior  of  Uie  kiln.  Through  the 
Aimace  doors,  easily  combustihle  fuel,  such  as  brushwood,  light  timber,  shavings,  &c., 
is  introduced.  The  mass  becomes  gradually  heated,  the  larger  stones  crack  and  break 
npand  the  wholemass  sinks  together.  As  the  firing  is  increased  the  lime  becomes  of  a 
brighter  colour  and  the  flames  free  from  smoke.  As  soon  as  the  lime  immediately 
under  the  stones  on  the  top  of  the  kiln  is  at  a  white  heat  the  burning  is  complete. 
The  mass  by  this  time  will  have  sunken  one-sixth.  A  burning  generally  occupies 
thirty-six  to  forty-eight  hours.  An  occasional  kiln  with  a  grated  furnace  effects  a 
quicker  and  more  complete  combustion  of  the  fuel ;  but  Ihey  are  open  to  the  objec- 
tion that  the  consumption  is  greater.  On  the  other  hand,  the  kilns  without  a  grated 
furnace  are  less  perfectly  heated.  A  IHIn  much  used  in  Hanover  is  shown  in 
Fig.  179,  and  in  plan  in  Fig.  180;  Fig,  181  shows  the  under  part  of  the  kiln  in 
vertical  section.  The  lower  room  serves  for  the  calcination  of  the  lime ;  over  this  is 
a  vaulted  chamber  3' 12  metres  in  diameter  and  11  feet  in  height,    ecce.  Figs.  180 


3*4- 


CHEMICAL    TECHNOLOGY. 


and  l8l,  are  four  stoke-lioles  for  the  introduction  of  fuel,  Btone-coal,  brown-cisL 
breeze,  Ac.  sis  the  approach  by  which  the  limestone  ia  introiluced  into  the  tana/x: 
d  the  door  by  wliiuh  entrance  ia  obtained  to  remove  the  burnt  lime.  Both  tliese 
Openings  are  closed  during  the  actual  burning,  a  ia  an  approach  to  the  "  upper 
jacket,"  as  the  upper  chamber  is  termed.  This  opening  is  necessary  as  a  draught  to 
assist  the  flame  and  hot  gases  in  their  escape  from  the  top  of  the  kiln ;  it  also  eanses  * 
more  intense  flame  in  other  parts  of  the  kiln.    Figs.  i8o  and  i8i  show  hoir  the  liiae- 


stone  is  kept  clear  of  the  heartlia.  A  piece  of  wood  is  placed  vertically  in  the  centre 
of  tlie  oven  to  direct  the  ilames  upwards  when  the  fire  is  hghted.  During  the  Cinit 
six  Jiours  Ihe  fire  is  weak ;  then  a  stronger  fire  is  obtained  until  the  yellow  lime- 
flames  spi-iiig  from  tlie  openings  in  the  vault,  and  the  oven  is  in  a  clear  glow. 

Tb«  conUnnnmi  KLimi  The  constnictjon  of  tlic  Idlns  for  continuous  burning  is  somewhat 
different  to  that  of  Uie  preceding.  Tliey  are  of  two  kinds.  In  one  the  fuel  and  the 
limestone  are  placed  in  alternate  layers ;  in  the  other  kind,  the  fnel  and 


Ftq.  i8o. 


Fra.  I  Si. 


[j.^Lrl 


are  not  in  contact,  there  buing  furnaces  for  the  former  and  separate  chambers  for  tbe 
latter.  In  eitlier,  &esh  limestone  is  added  in  proportion  aa  the  bunt  stone  if 
removed  from  the  bottom  of  the  kiln. 


LIME. 


3^5 


At    Ruderadorf,   Dear   BerUn,    a  very    efficient  kiln    is   employed,    shown   in 

section  in  Ftg.  182.    The  lining  wall  of  the  shaft   d,  la  bnilt  of  fire  bnck,  the 

counter  wall.  0.  ia  separated  from  the  lining  wall  by  a  clmmber  filled  with  ashes, 

building  refhae,  Ac.    The  outer  waJl,  b  b,  is  not  an  eseential  portion  of  the  kJn ,  it 

serres  merely  aa  a  jacket  foi  the  retention  of  the  heat  while  the  gallenea    h  and  f, 

can  be  uaed  aa  drying  rooms  for  wood,  fnel,  4c     Dunng  the  proceaa  the  under 

port,  B,  of  the  shaft  is  filled  with 

prepared  lime,  which  is  removed  by  "  '^^ 

the  dranght  hole.  a.  in  the  sole  of 

the    shaft      For    tlie    purpose    of 

Jiastening  the  descent  of  the  hnmt 

lime,  the  sides  of  the  lower  part  of 

the  shaft  are  sloped  towards  the 

draught -holes.    The  shaft  is  usually 

14*123  metres    in  height.     About 

4  metres  above  the  sole  of  the  shaft 

is  situated  the  fire  room,  h.     Three 

to  five  fire  rooms  are  in  action  in  a 

single  shaft.     The  fuel  ia  wood  or 

turf,     i  ia  the  ash-pit,  whence  the 

aahea  fall  into  e.     The  fkme  entera 

the  shaft  through  the  opening,  b.  at 

tlie    end    of   the    fire   room.     The 

freshly -burnt  lime  ia  received  in  p. 

E  K  is  a  draught  gallery  commuui- 

c&ting  wilh  H.     The  kilns  are  locally   liiio«ii   as  tlirct-,  four-,  or  live 

according  to  the  number  of  fira  rooms.    Should  the  Iriln  not  have  been  in  use  for 

Bome  time,  the  firing  is  oommeuced  by  adding  fuel,  such  as  wood,  turf,  Ac.,  to  tlie 

limestone  in  the  shaft.     ^Vhen  tJie  shaft  is  tlioivu^lily  warmed  and  a  good  draught 

oblained,  lime  only  is  introduced  into  the  shaft,    The  shaft  ia  entirely  filled  with 

limestone,  and  sometimea  the  limestone  accnmulatea  upon  tho  mouth  or  top  of  the 

kiln  to  a  height  of  13  metres. 

■ooi  In- Bundiii      When  the  locality  la  favourable  the  kilns  are  arranged  to  bum  both  lima 
uoHuidBiioki.   and  bricks  at  the  Bftme  time.     The  annular  kiln  of  Hoffmann  and  Licht, 
described  under  Brick.making,  is  the  most  snitable  for  this  double  pnrpose- 

FnpHtiaiiiLinu.  The  qnali^  of  the  burnt  lime  is  greatly  influenced  by  the  constitu- 
tion of  the  limestone  burnt  When  the  limestone  consists  chiefly  of  pure  carbonate 
of  line,  the  resulting  lime  is  what  is  termed  a  "  fat "  lime.  On  the  other  hand,  if  the 
limestone  is  of  similar  composition  to  dolomite  (CaCO^-l-MgCOjl  contaiuing 
magnesia,  the  resulting  lime  forms  a  short,  thin  pulp  with  wat«r,  aud  is  termed 
"poor."  With  lopercent  of  magnesia  the  lime  is  noticeably  poor,  and  with  25  to 
30  per  cent  almost  useless.  The  lime  on  being  taken  from  the  kiln  is  by  no  means 
found  to  be  burnt  equally.  Some  pieces  that  have  almost  escaped  the  fire  are 
merely  superficially  burnt,  and  contain  a  kernel  of  unbunit  limeatone.  Other  pieces 
exposed  to  the  full  heat  of  the  1  Jln  are  ■■  over-burnt."  The  "  over-burning  "  of  the 
lime  is  either  due  to  the  forming  of  "half-burnt"  lime  (CaCOj+CaHiOj)  by  a 
Btrong  and  sudden  ignition :  or  by  means  of  the  high  temperature  the  amaU  quantity 
of  silica  and  alumina  contained  in  the  limestone  become  sintered  over  the  surface. 


326  CHEMICAL  TECHNOLOGY. 

and  the  lime  is  thus  prevented  hy  a  coating  of  silicate  from  combining  with  ti^e 

water  to  form  a  pulp. 

Slaking  Limo.        Bumt  lime  moistened  with  water  slakes  with  great  violenr?e,  loo  parts 

by  weight  of  lime  requiring  only  32  parts  water,  or  3  vols,  of  lime  to  i  vol.  water,  to 

obtain  by  the  combination  a  temperature  of  150°.     The  result  of  the  slaking  is  a  soft, 

white  powder,  lime-meal  or  powdered  lime,  hydrate  of  protoxide  of  calcium  (CaHaOs), 

which  in  volume  exceeds  three  iiiaes  that  of  the  lime  slaked.    If  less  water  is  added 

than  is  requisite  for  the  formation  of  the  hydrate,  a  sandy  powder  is  obtamed  of 

little  value  technically.    It  is  therefore  very  disadvantageous  to  place  lime  in  baskets 

in  damp  situations.    For  technical  application  to  building  purposes,  after  the  lime 

has  been  slaked  with  one-third  of  its  weight  of  water,  an  equal  quantity  of  water  is 

added  to  the  mass  to  form  a  thin  pulp.     Slaked  lime  retains  its  water  of  formation 

with  such  obstinacy  that  at  a  temperature  of  250°  to  300°  no  loss  of  weight  occuis. 

The  hydrate  forms  a  thin  pulp  with  water,  and  from  this  pulp  by  further  dilation 

lime-water  or  milk  of  lime  is  obtained.     If  the  lime-water  be  filtered,  there  results  a 

saturated  solution  of  hydrate  of  lime,  containing  i  part  hydrate  to  778  parts  water. 

When  exposed  to  the  atmosphere,  lime-water  rapidly  absorbs  carbonic  acid,  and  is 

soon  covered  with  a  thin  film  of  carbonate.    Lime-water  has  a  strong  alkaline 

reaction,  due  partly  to  the  lime  itself,  and  partly  to  the  fact  that  most  limestones 

contain  common  salt  and  alkaline  silicates,  which,  under  the  influence  of  the  caustic 

lime,  are  converted  into  caustic  alkali. 

Uses  of  Lime.  The  technical  apphoations  of  lime  are  veiy  many.  Its  great  affinity  for 
carbonic  acid  fits  it  especially  for  the  preparation  of  the  caustic  alkalies.  Slaked  lime  u 
employed  in  the  preparation  of  ammonia  from  sal-ammoniac,  of  hypochlorite  of  ealciiim 
(chloride  of  lime),  in  the  precipitation  of  magnesia  from  the  mother-ley  of  salines ;  in  the 
purification  of  illuminating  gas  from  carbonic  acid  and  partly  from  sulpbaretted 
hydrogen ;  in  the  refining  of  sugar  and  the  separation  of  the  sugar  from  beet-root  juice;  in 
the  manufacture  of  soda;  in  tanning,  to  remove  the  hair  and  prepare  the  hide;  in 
bleaching ;  in  the  manufacture  of  stearine  candles ;  in  the  preparation  of  alum  and  sul- 
phate of  alumina  from  cryolite ;  for  neutralising  the  sulphuric  acid  in  the  preparation  of 
starch-sugar,  &c.  .One  of  the  latest  appUcations  of  lune  is  to  the  oxy-hydrogen  or 
oxy -calcium  light,  which  is  of  so  much  importance  in  signalling,  and  such  a  valuable  aid 
to  the  lecturer.  The  most  important  application  of  lime  is  doubtless  in  the  making  of 
mortar. 

Mortar. 

Mortar.  Mortar  is  a  mixture  of  sand  with  cream  of  lime,  used  in  building  as  a  binding 
material.  The  ordinary  mortar  sets  or  hardens  only  in  the  air ;  hydraulic  mortar 
sets  under  water. 

a.  Common  or  Air-setting  Mortar. 

When  slaked  lime  is  exposed  to  the  atmosphere  it  absorbs  carbonic  acid,  and  the 
mass  becomes  much  shrunken  and  cracked.  The  hydrate  of  lime  thus  formed 
on  becoming  perfectly  dry  attains  the  hardness  of  marble.  Such  a  material,  with 
certain  modifications,  is  consequently  admirably  adapted  as  a  cement  to  bind  together 
bricks,  blocks  of  stone,  &c.,  in  building.  But  as  the  contraction  or  shrinkage  would  give 
rise  to  great  unevenness  in  the  construction  of  walls,  it  becomes  necessary  to  add 
sand  or  some  similar  substance  to  the  lime-cream.  This  addition  gives  a  body  to  the 
mortar,  which  with  the  bricks  combines  into  one  coherent  mass.  Common  mortar  is 
ordinarily  made  with  slaked  lime,  an  intimate  mixture  with  sand  and  water  being 
formed.  Angular  or  sharp  sanJ  is  preferred  to  smooth,  round  sand,  as  making 
a  more  tenacious  mortar.    Round-grained  sand  yields  a  very  brittle  mortar.    The 


LIMS, 


327 


proportion  of  sand  to  the  lime  is  a  matter  immediately  affecting  the  quality  and 

hardness  of  the  mortar.    In  practice,  i  cubic  metre  of  stiff  lime-cream  requires  3  to  4 

cubic  metres  of  sand ;  but  poor,  magnesia- containing  lime,  will  only  admit  of  i  to  2i 

cubic  metres  of  sand.    When  mortar  is  employed  in  brick-laying,  the  surface  of  the 

brick  is  moistened,  the  mortar  laid  between  each  brick,  and  left  to  dry.    When  dry 

it  is  often  harder  than  the  brick  itself. 

Haid«ntDg um Mortar.  Mortar  sets  or  hardens  yery  quickly;  after  a  day  it  will  attain  a 
fimmess  that  will  last  for  centuries.  The  drying  out  of  the  water  from  the  mortar  is  not 
the  sole  cause  of  its  hardening,  as  may  be  very  easily  ascertained  by  drying  the  mortar  in 
a  water-bath  or  over  the  spirit-lamp ;  the  result  is  not  a  stone-like,  but  a  friable,  non- 
eoherent  mass.  Fuohs  aocounts  for  the  hardening  of  mortar  by  supposing  the  formation 
of  the  so-called  neutral  carbonate  of  lime  (CaCOj+OaHaOa))  a  combination  which  has  not 
been  known  to  suffer  oonyeraion  into  ordinary  carbonate  of  lime  (CaC03).  Beoent 
researches  have  shown  this  supposition  to  be  erroneous,  as  it  does  not  agree  with 
the  results  of  analyses,  which  have  yielded  a  quantity  of  carbonic  acid  incompatible  with 
the  existence  of  a  neutral  carbonate ;  20  and  even  70  per  cent  of  carbonic  acid  have  been 
found.  The  experiments  of  Alexander  Petzholdt,  A.  von  Schrotter,  and  others,  have 
proved  there  to  be  an  increase  of  soluble  silica.  The  conversion  of  quartz -sand 
iato  soluble  silica  under  the  influence  of  hydrate  of  lime,  is  not  however  a  reaction  at  all 
explanatory  of  the  hardening  of  mortar,  as  washed  chalk  instead  of  silica  forms  an 
equally  luurd  mass.  W.  Wolters  gives  the  formation  of  silicate  of  lime  as  accounting 
for  the  hardening  of  mortar.  It  is  not  seldom  in  the  analysis  of  old  mortar  from  the 
interior  of  walls  that  caustic  alkalies  are  fotmd. 

h.  Hydraulic  Mortar. 

HydzBoUe  Horur.  Limestone  containing  more  than  10  per  cent  silica  possesses,  when 
burnt  and  made  into  a  mortar,  the  peculiar  property  of  hardening  under  water. 
Lime  burnt  from  such  limestone  is  termed  hydraulic  lime,  and  the  mortar  hydraulic 
mortar. 

When  unbumt,  hydraulic  lime  is  a  mixture  of  carbonate  of  lime  with  silica  or 
a  silicate,  generally  silicate  of  alumina,  the  latter  being  insoluble  in  hydrochloric 
add.  During  the  burning,  the  hydraulic  lime  suffers  a  change  similar  to  that  taking 
place  when  a  silicate  insoluble  in  acid  is  precipitated,  during  the  application  of  heat, 
with  an  alkaline  carbonate.  After  burning,  the  lime  is  to  a  great  extent  soluble  in 
hydrochloric  acid,  and  has  lost  some  of  its  carbonic  acid.  Von  Fuchs,  Feichtinger, 
Harms,  Heldt,  W.  Michaelis,  and  A.  von  Kripp's  experiments  have  proved  that  the 
silica  of  hydraulic  lime  is  precipitated  in  a  gelatinous  condition,  and  that  con- 
stituents such  as  alumina  and  oxide  of  iron  are  of  influence  only  when,  under 
ignition,  they  have  formed  a  chemical  combination  with  the  silica. 

Hydraulic  mortars  are  made : — 

1.  With  a  thin  cream  of  lime  and  water  to  which  sand  is  added ;  or  with 

2.  A  mixture  of  ordinary  air-mortar  with  water  and  cement. 

During  the  slaking  of  the  hydraulic  lime  water  is  absorbed,  but  without  any  con- 
siderable evolution  of  heat  or  increase  in  volume.  Hydraulic  mortar  is  applied  in 
the  same  manner  as  ordinary  mortar — the  lime-cream  must  be  freshly  made,  and  the 
brick  or  masonry  work  moistened.  The  mortar  should  be  placed  thickly  between 
each  layer  of  bricks,  in  order  to  afford  a  good  firm  bed,  and  allow  for  shrinkage. 
ccniAiita.  It  follows  from  what  has  been  said  that  an  artificial  hydraulic  mortar  can 
be  prepared  from  ordinary  lime  by  the  addition  of  silica.  Such  a  preparation 
is  termed  a  cement.  A  few  natural  cements  are  found,  and  may  be  considered 
as  chiefly  of  volcanic  formation.  To  this  class  belong  tuff-stone,  tarras,  or  trass,  a 
tertiary  earth,  the  basis  of  which  appears  to  be  pumice-stone  with  small  qnantitieg 
of  basalt  and  calcined  slate,  the  pozzolano  of  Italy,  and  santorin. 


328  CHEMICAL  TECHNOLOGY. 

Tarrafl,  or  trMs,  also  oontams  magnetic  iron  in  Bmall  qtumtitieB,  aB  veil  as  titanie  ino. 
The  following  are  the  constitaente  according  to  analysis : — 

Solnble  in  Insolnble  in 

hydrochloric  acid.  hydrochloric  add. 

Silica zi'5o  37*44 

Lime      3*16  2*25 

Magnesia      2*15  0-27 

Potash 0*29  O'oS 

Soda       2'44  i'i2 

Alumina        1770  i"25 

Oxide  of  iron       irij  075 

Water 7*65  — 

56-86  42-98 

This  cement  has  been  employed  for  300  years  as  a  hydranlio  mortar,  and  is  one  of  the 
most  important  of  its  class. 

Pozzolano  is  another  tertiary  earth,  oocnrring  chiefly  at  PuzznoH,  near  Kaples,'~a8 
a  loose,  gray,  or  yellow-brown  mass,  of  partly  a  fine-grained  and  partly  an  earthy 
fracture.    It  contains  in  100  parts : — 

Silicic  acid 44-5 

Alumina       15-0 

Lime •     ,.  8*8 

Magnesia      4*7 

Oxide  of  iron      i2'o 

Potash \ 

Soda      I  5'5 

Water 9-2 

loo-o 

The  oxide  of  iron  contains  small  quantities  of  titanium.  More  Hme  most  be  added  to 
form  a  hydraulic  mortar.  The  masonry  of  the  light-room  of  the  Eddystone  Lighthoiue 
is  cemented  with  a  hydraulic  mortar  formed  from  equal  parts  of  pulyerised  pozzolano  and 
slaked  lime. 

Santorin  derives  its  name  from  the  Greek  Island  of  Santorin,  where  it  was  first  fonsd. 
It  is,  similarly  to  trass,  a  volcanic  formation,  and,  according  to  G.  Feichtinger  (1870),  con- 
sists of  a  mixture  of  cement  and  sand,  the  latter  containing  large  quantities  of  pnmiee- 
stone.  It  is  not  largely  employed  as  a  cement,  on  account  of  the  difficulty  of  separating 
the  true  cement  from  the  accompanying  sand. 

AiUfleiai  Cements.  The  high  price  of  natural  cements  consequent  upon  the  smallness 
of  Uie  quantity  found,  and  the  difficulty  of  working  them,  has  given  much  encourage- 
ment to  the  manufacture  of  artificial  cements.  Lideed,  the  use  of  natural  cements  is 
the  exception  and  not  the  rule.  Parker,  Wyatt,  and  Co.,  were  the  first  artificial  cement 
manufacturers,  and  took  out  their  English  Patent  in  1796 ;  they  may  therefore  be 
considered  as  the  founders  of  the  extensive  industry  of  the  present  day.  The 
cement  prepared  by  them,  ajid  now  in  use,  is  known  as  English  or  Koman  cement 
It  is  manufactured  by  burning  a  peculiar  clay-shale  found  above  the  chalk  fonnadoa 
in  the  Isle  of  Sheppey  and  the  Isle  of  Wight.  The  burning  is  effected  in  an 
ordinary  lime  kiln,  and  the  burnt  shale  is  afterwards  pulverised.  The  reanltiog 
red-brown  powder  eagerly  absorbs  carbonic  acid  and  water  from  the  air.  It  i« 
packed  in  casks  and  stored  ready  for  use.  When  prepared  as  a  mortar,  it  hardenB 
or  sets  in  fifteen  to  twenty  minutes. 

Michaelis  found  by  the  analysis  of  varioTis  Boman  cements : — 

I.  2.  3.  4. 

Lime       58*38  55'5o  47*83  5888 

Magnesia        500  173  2426  225 

Silicic  acid     28*83  2500  580  23 66 

Alumina 640  696  150  7*24 

Oxide  of  iroa 4*80  963  2080  797 


The  analyses  are  from  cements  free  from  water  and  carbonic  add.  No.  z  is 
Boman  cement  from  Kiidersdorf  limestone ;  2.  From  limestone  from  the  Isle  of 
Sheppey,  yellow-brown  in  colour,  coarse,  and  hard ;  3.  From  limestone  forming  the 
under  bed  of  the  lead  ores  at  Tamowitz,  of  a  blue-gray  colour,  firm,  and  of  a 
crystalline  appearance ;  4.  From  Hausbergen  limestone. 

Portland  cement,  so-named  from  the  resemblance  it  bears  when  set  to  Portland 
stone,  is  a  scaly  crystalline  powder  of  gray  colour,  and  was  first  prepared  by 
Mr.  Joseph  Aspdin  of  Leeds,  in  1824.  According  to  his  Letters  Patent,  he  prepared 
the  cement  in  the  following  manner : — ^A  large  quantity  of  limestone  was  taken  and 
pulverised;  or  the  dust  or  pulverised  limestone  used  to  mend  the  roads  was 
employed.  This  material  was  dried  and  burnt  in  a  lime-kiln.  An  equal  quantity  by 
weight  of  clay  was  added  to  the  burnt  lime,  and  thoroughly  kneaded  with  water  to  a 
plastic  mass.  This  was  afterwards  dried,  broken  in  pieces,  and  burnt  in  a  lime-kiln 
to  remove  all  the  carbonic  acid.  The  mass,  thus  transformed  to  a  fine  powder, 
is  ready  for  the  market.  It  is  known  in  commerce  as  a  gray,  or  green-gray,  sandy, 
palpable  powder.  But  Pasley  must  be  considered  the  true  founder  of  artificial 
cement  manufacture  in  England ;  he,  in  1826,  obtained  a  cement  by  the  burning  of 
river-mud  from  the  Medway,  impregnated  ^dth  the  salts  from  the  sea- water,  with 
limestone  or  chalk.  The  mud  from  the  Medway  is  probably  best  adapted  for  the 
manufacture  of  Portland  cement  on  account  of  the  sodium  salts  it  contains,  and  from 
this  supposition,  there  seems  good  ground  for  Pettenkofer's  recommendation  that 
various  marls,  burnt  after  lixiviation  with  a  solution  of  common  salt,  should  be 
tried.  At  the  present  time  the  mud  from  the  mouths  and  delta  formations  of  several 
large  rivers  is  employed  in  the  preparation  of  this  cement. 

The  manufacture  of  Portland  cements  usually  follows  this  mode.  The  raw 
materials,  limestone  and  clay  or  mud  in  equal  quantities,  are  intimately  mixed,  the 
mixture  dried  ru  the  air,  and  then  burnt  in  a  shaft-oven.  The  shaft-oven  is  generally 
14  to  30 metres  in  height,  with  a  width  of  23  to  4  metres.  At  a  height  of  i  to  1-3 
metres  from  the  ground  is  a  strong  grating,  through  which  the  lumps  of  limestone 
mostly  fall,  those  remaining  being  afterwards  broken  by  the  heat.  The  oven  is  so 
arranged  that  a  layer  of  fuel  and  a  layer  of  cement  stone  alternate.  Coke  is 
generally  chosen  as  fuel,  being  found  by  experience  best  adapted  for  the  purpose. 
After  the  mass  has  been  submitted  <to  a  red  heat  for  one  hour,  it  assumes  a  yellow- 
brown  colour,  and  at  a  higher  temperature  becomes  a  dark  brown.  Gradually  the 
lime  becomes  causticised,  and  enters  more  and  more  into  chemical  combination  with 
the  silicates.  At  a  white  heat  the  mass  becomes  gray  in  colour,  with  a  streak  here 
and  there  of  green.  If  during  the  operation  these  colours  are  shown  at  the  several 
stages,  the  resulting  cement  will  be  good  and  set  hard.  If  the  heating  is  continued, 
the  cement  will  assume  a  blue-gray  colour  and  become  quite  useless.  If  removed  at 
the  first  stage  the  mass  yields  a  yellow-brown,  light  powder ;  at  the  second,  a  gray, 
sharp  powder  tinged  with  green.  Beyond  this  stage  the  powder  is  blue-gray,  or  gray- 
white,  clear  and  sharp,  and  very  similar  to  glass-powder.  The  more  lime  the 
mixture  contains,  or,  it  might  be  said,  the  more  basic  the  mixture,  the  more  durable 
is  the  cement,  and  the  less  it  fedls  to  pieces  in  burning.  A  mixture  in  which  clay 
predominates  is  always  more  or  less  a  weaker  cement,  fJEdling  to  pieces  readily, 
or,  technically,  not  binding  well.  According  to  Michaelis,  the  addition  of  lime  or 
«Mies  prevents  the  cement  separating,  and  renders  it  more  binding ;  but  in  practice 
^  addition  would  not  be  sufficiently  economical.    The  more  intimately  the  clay 


330  -  CHEMICAL  TECHNOLOGY. 

and  lime  are  mixed,  the  larger  the  amonnt  of  lime  that  may  be  ixiMzporated.  From 
the  moment  of  stiffening  till  the  final  hardening,  the  cement,  il  set  in  the  air, 
experiences  no  change ;  but  if  in  water,  there  is  at  first  a  small  loss  of  the  more 
soluble  constituents — the  alkalies. 

Portland  cement  mixed  with  water  to  a  pulp  stiffens  in  a  few  minutes,  and  after 
the  elapse  of  a  day  sets  tolerably  hard.  After  a  month  the  cement  sets  into  a  sub- 
stance so  hard  and  firm  that  it  emits  a  sound  when  struck  by  a  hard  body.  It  is 
admirably  adapted,  when  mixed  with  sand  or  gypsum,  for  being  east  into  the 
various  architectural  ornaments,  and,  indeed,  has  from  this  property  been  termed 
artificial  stone.  Lately  Griineberg  has  made  crystallising  vessels  of  this  cement 
and  Posch  employs  it  in  constructing  reservoirs  for  hot  fluids. 

HftnnfRotare  of  ArUfleiai      The  prooefis  of  manufactnring  tme  Portland  cement  being  eonfioed 
c«m«nt  In  oennany.      to  England  by  letters  patent,  the  cements  of  this  kind  made  in  Ger- 
many may  be  considered  as  artificial  cements.    They  result  but  £rom  a  slight  vaxiation  in 
method  only,  chalk  and  clay  or  mad  being  mixed,  and  the  mixture  formed  into  bricks  or 
tiles,  then  burnt  and  ground  to  powder.     This  cement  answers  in  every  respect  the 
purposes  of  the  original  cement.     In  the  preparation  of  hydraulic  mortar  a  mixtoze 
of  chaJk  and  lime  is  also  used,  together  with  marl,  the  ashes  of  pit-coal  and  ti^,  the 
fdum-shale  and  alum-earth  resulting  from  alum  manufacture,  burnt  potter's  earth,  broken 
porcelain,  pulverised  flint,  &e*    Chaloedony  cement  is  a  mixture,  invented  by  H.  Fruhting 
(1870),  of  I  volume  of  burnt  chalcedony  with  i  volume  of  lime  and  2  volumes  of  white 
sand.    This  cement  has  a  glaze  much  resembling  polished  marble.    Although  the  prin- 
ciples of  the  hydraulic  nature  of  various  cements  and  mortars  are  known,  not  many 
experiments  have  been  made  in  verification.    The  elements  of  success  seem  to  lie  in 
a  due  regulation  of  the  heat  during  burning,  in  the  intimate  mixing  of  the  ingredients; 
the  chief  principle,  the  chemical  combination  of  the  several  substances,  is  but  Tezy 
little  known.    Of  the  various  uses  of  hydrauHo  mortars,  we  have  nothing  to  do ;  the  con- 
ditions of  applicability  are  : — i.  That  the  proportion  of  25  per  cent  of  clay  be  presoired; 
2.  That  the  clay  be  of  the  requisite  quality,  rich  in  silica,  finely  divided,  and  form  an 
intimate  mixture  with  carbonate  of  lime.    These  conditions  are  very  seldom  entirely  ful- 
filled.   Portland  cement  was  first  introduced  into  Germany  in  1850,  by  M.  Gierow,  of 
Stettin ;  and  in  1852  M.  H.  Bleibtreu,  of  Stettin,  erected  a  building  at  Bonn  in  which  thii 
cement  was  largely  employed.    Since  that  time  there  has  hardly  been  a  buildmg  in  the 
erection  of  which  Portland  cement  was  not  used. 

M.  W.  Michaelis  gives  the  following  analyses  of  Portland  cements,  the  samples  being 
free  from  water  and  carbonic  acid : — 

I.  2.  3.  4.  5.  6.  7.  8.  9. 

Lime       ..     ..  59*06  62*81  61*91  60*33  6i|64  6i74  55'o6  57*^3  55'^ 

Silidc  acid      ..  24*07  23*22  24*19  25*98  23*00  25*63  22*92  23*81  22*86 

Alumina  ..     ..  6*92  5*27  7-66  7*04  6*17  6*17  8*oo  9*38  9*03 

Oxide  of  iron  3*41  2*00  2*54  2*46  2*13  0*45  5*46  5*22  6*14 

Magnesia        ..  0*82  1*14  1*15  0*23  —  2*24  0*77  1*35       1*64 

Potash     ..     ..  0*73)  J  1 077  o*94  —  0*60  1-13  0*59  077 

Soda        ..     ..  0*87/  '  10*46  0*30  —  0*40  1*70  0*71        — 

Sulphate  of  lime  2*85  1*30  —  1*52  1*53  1^4  1*75  1*1 1  3*20 

^^  I    ..     ..     1-47         2-54       1-32        1*04        1*28        1*13        2*27  —        i-o8 

No.  I  is  Portland  cement  from  White  and  Brothers,  analysed  by  Michaelis.  No.  2  is 
Stettin  cement,  analj^sed  by  Michaelis.  Nos.  3  and  4  are  Wildauer  cements.  No.  5,  known 
as  Star  cement ;  and  No.  6,  another  Stettin  cement,  by  the  same  analyst.  No.  7  ii 
English  cement.  No.  8  cement  from  works  near  Boim,  both  analysed  by  Hopfgartner. 
No.  9  is  a  strong  and  porous  cement,  analysed  by  Feichtinger. 

An  analytic  comparison  of  German  and  English  cements  will  be  interesting.  German 
Portland  cement  has  the  same  colour  as  EngUsh  cement,  and  similarly  havens  under 
water  to  the  same  degree  of  durability.  Under  the  microscope  both  possess  the  same 
foliated  and  slaty  appearance.  The  specific  weight  is  in  both  cases  the  same.  A  peculiar 
marl,  Eufstein  marl,  is  found  in  the  Tyrol,  near  Kufstein,  yielding  an  excellent  cement,  of 
which  Feichtinger  gives  the  following  notice : — <*  Kufstein  Portland  cement  is  a  nataral 


LIME*  331 

hydranlio  lime,  tmlilce  English  Portland  oement,  which  is  an  artifloial  hydraulic  lime.  It 
is  the  prodnct  of  burning  a  marl  found  largely  in  most  Alpine  districts,  and  in  every 
applicable  condition  to  similar  to  English  Portland  cement.  The  following  is  an  analysis 
of  this  marl : — 


Constituents 


'  Carbonate  of  lime 70*64 

Carbonate  of  magnesia 1*02 


soluble     in .  Oxide  of  iron 2*58 

hydrochloric  |  Alumina 2*86 

acid                I  Gypsum 0*34 

^  Water  and  organic  substances 079 

Total  constituents  soluble  in  hydrochloric  acid. .  78*23 


Constituents 
insoluble   in 
hydrochloric 
acid. 


'Silica       15*92 

Alumina 3*08 

Oxide  of  iron 1-40 

Potash     0*55 

^Soda        0*82 


Total  constituents  insoluble  in  hydrochloric  acid     21-77 

The  quantity  of  the  insoluble  constituents  amounts  only  to  21*77  P^'  oemi,  while  most 
marls  contain  much  more  clay ;  in  practice,  however,  the  clay  is  increased  to  25  to  30  per 
«ent.  The  Kufstein  marl  differs,  too,  in  the  chemical  composition  of  the  clay,  and  as 
as  is  known,  the  constitution  of  the  clay  greatly  affects  the  qualities  of  the  cements.  A 
eompaxison  of  tiie  two  clays  will  therefore  possess  interest.    Li  100  parts  of  sUica : — 

Clay  from  Clay  from 

Kufstein  marl.      Medway  mud. 

Alumina      •     i9'34  17*0 

Oxide  of  iron 8*79  21*6 

Potash         3*45  2-8 

Soda 5*15  30 

3673  444 

These  analyses  show,  that  with  the  clay  of  the  Kufstein  marl,  a  large  quantity  of 
important  bases  enter  into  combination,  more  than  possessed  by  the  clay  of  the  Medway 
mud.  Therefore  the  clay  of  this  marl  may  be  more  readily  smelted  in  a  small  fire.  The 
Hzoall  quantity  of  magnesia  contained  in  the  Kufstein  Portland  cement  probably  is 
productive  of  good  effect ;  all  good  hydraulic  cements  contain  but  little  magnesia." 

The  mention  of  concrete,  so  largely  used  in  England  where 'a  good  weathering  mortar  is 
required,  must  be  included  in  that  of  cements.  Concrete  is  a  mixture  of  ordinary  mortar 
with  stones,  grit,  broken  brick,  tiles,  <&c.  To  the  concrete  is  generally  added  lime,  and 
then  the  whole  mixed  with  two  to  three  times  the  quantity  of  fine  sand.  Pasley  tells  us  IJiat 
a  better  product  may  be  obtained  with  i  part  of  freshly  burnt  lime,  in  pieces  not  larger  than 
the  fist,  3i  parts  of  sharp  river-sand,  and  1*5  parts  of  water,  the  whole  being  well 
inixed.  The  bricklayer  prefers  to  mix  the  dry  materials  and  then  add  water,  the  concrete 
in  this  manner  taking  a  longer  time  to  harden,  and  admitting  of  greater  care  being  taken 
to  fill  all  interstices.  The  several  uses  of  concrete  are  too  well  known  to  need  mention. 
The  employment  of  unslaked  lime  in  the  preparation  of  concrete  was  first  introduced  by 
Mr.  Smirke,  of  London,  to  whom  also  its  employment  as  a  foundation  to  brickwork 
is  mainly  due. 

H^SteifJruJi  '^^®  hardening  of  hydraulic  mortars  has  often  been  the  subject  of 
investigation.  Two  views  may  be  taken:  first,  the  mere  setting,  the  congealing  of 
the  mass  from  a  fluid  state  to  a  moderate  degree  of  hardness ;  and  then  the  hardening 
to  a  stony  state.  The  knowledge  we  possess  of  the  setting  of  these  mortars  is  chiefly 
due  to  the  experiments  of  Von  Fuchs,  Von  Pettenkofer,  Winkler,  Feichtinger, 
Heldt,  Lieven,  Schulat-Schenko,  Ad.  Kemete,  Heereen,  W.  Michaelis,  and  Von 
Schoenaich-Carolath.  The  cements  when  thus  considered  are  best  divided  in  two 
classes : — The  first  class,  of  which  Eoman  cement  is  the  type,  embraces  the  mixture 
of  caustic  lime  with  pozzuolane,  pulverised  tile,  and  brick,  and  such  hydraulic  mortar 


332  CHEMICAL  TECHNOLOGY. 

as  is  obtained  by  burning  hydraulic  lime  and  marl.  All  the  cements  contain  caustie 
lime  unacted  upon.  The  second  class  comprehends  Portland  cements,  containing  no 
fresh  caustic  lime.  M.  Von  Fuchs  has  explained  the  chemical  actions  talring  place 
during  the  hardening  of  Roman  cements  as  being  principally  the  combination  of  the 
lime  with  silicic  acid,  the  combination  giving  rise  to  the  peculiar  property  of 
hydraulic  mortars.  He  draws  this  conclusion  partly  from  the  &ct  that  from  all 
hydraulic  mortars  the  silica  can  be  thrown  down  as  an  insoluble  gelatinous  niMy  by 
the  action  of  carbonic  acid. 

A  similar  gelatinous  mass  results  from  the  combination  of  sHicic  acid  and  lime. 
Silicates  do  not  yield  when  treated  with  hydrochloric  acid  alone,  gelatinous  silica, 
but  attain  this  property  when  subjected  for  a  length  of  time  to  the  influence  of  lime 
under  water ;  the  water  also  dissolves  out  the  alkalies.  KiilUmann,  who  has  long  been 
employed  in  the  study  of  the  chemistry  of  hydraulic  cements  and  artificial  stones, 
states  that  lime  can  be  rendered  hydraulic  by  the  intimate  mixture  of  lo  to  12  per 
cent  of  an  alkaline  silicate,  or  by  treating  with  a  water-glass  solution.  Collecting  the 
results  of  these  experiments,  the  setting  of  Roman  cement  appears  due  to  the  com- 
bination of  acid  silicates  or  silica  with  burnt  lime,  forming  a  hydrated  silicate  of 
lime  intermixed  with  the  alumina  and  oxide  of  iron. 

The  hardening  of  Portland  cements  has  been  investigated  by  Winkler  and  Feich- 
tinger.    According  to  the  former,  the  chemical  action,  which  is  effected  under  the 
co-operation  of  tlie  water,  consists  of  the  separation  of  the  silicates  into  free  lime  and 
combinations  between  the  silica  and  the  calcium,  the  alumina  and  tlie  calcium.    The 
separated  lime  combines  with  the  carbonic  acid  in  the  air  to  form  carbonate  of  lime. 
The  hardened  Portland  cement  contains  the  same  combinations  as  hardened  Roman 
cement;  these  combinations  are  formed,  however,  under  the  influence  of  water  on 
opposed  conditions.    From  the  results  of  Winkler's  experiments,  it  would  appear 
that  the  silicic  acid  in  the  Portland  cements  can  be  represented  by  alumina  and 
oxide    of   iron.      Alumina    does    not   affect  the  hardness,    but  may   lessen  the 
capability  of  the  cement  to  withstand  the  action  of  carbonic  acid.     During  the 
hardening  the  influence  of  the  water  separates  the  lime,  till  finally  the  combinations 
Ca^SisOg  and  CaAla04  remain,  the  latter  being  gradually  decomposed  by  carbonic 
acid,  remaining,  however,  so  long  as  there  is  any  hydrate  of  lime  in  the  cement 
G.  Feichtinger  maintains  a  theory  differing  from  that  of  Winkler.    His  experiments 
lead  him  to  the  opinion  that  in  all  hydraulic  mortars  the  hardening  depends  upon  the 
chemical  combination  between  lime  and  the  silica,  and  between  lime  and  the  silicates 
contained  in  the  cement.    In  aU  hydraulic  cements  free  lime  is  contained ;  and  upon 
this  fact  we  may  base  the  following  experiments.    When  Portland  cement  is  bronght 
to  a  pulp  with  a  concentrated  solution  of  carbonate  of  ammonia,  and  stirred  for  a  long 
time,  no  hardening  is  traced,  the  greater  part  of  the  lime  forming  carbonate  of  lime. 
Then  let  the  excess  of  carbonate  of  ammonia  be  washed  away,  the  cement  dried, 
and  made  into  a  mortar  with  pure  water.    This  mortar  will  not  harden  unless  some 
hydroxide  of  lime  be  added,  when  it  hardens  similarly  to  fresh  mortar.    The  same 
result  may  be  obtained  by  substituting  a  stream  of  carbonic  acid  gas  for  the  carbonate 
of  ammonia;   by  this  means  27  per  cent  of  carbonate  of  lime  may  be  obtained. 
Consequently  the  views  of  Winkler  must  be  regarded  as  the  most  correct.    These 
experiments  also  show  that  in  Portland  cements  silicates  or  free  silica  are  contained; 
that,  further,  free  lime  does  and  must  exist.     Portland  cement  will  not  take  a  glaze, 
and  can  only  be  so  far  affected  by  burning  as  to  cause  the  sintering  of  the  clay  con- 
tained in  the  cement. 


GYPSUM. 


Gypsum  and  its  Preparation. 


333 


oocancnee.      Gjpsum  is  a  hydrated  sulphate  of  calcium  according  to  the  formula 

CaS04+2HaO.     loo  parts  contain : — 

Lime      32*56 

Sulphur i8"6ol  Q„,  ,  „  .^  ^  .,  ^ 

Oxygen   ^^.^^ | Sulphuric  iwid     4651 

Water    20*93 


lOOOO 


It  belongs  to  the  commonly  occurring  class  of  minerals,  and  is  found  alone  or  with 
anhydrite  {karstenite,  GaS04)  in  strata  chiefly  of  the  tertiary  formation.  The 
following  kinds  are  distinguished: — i.  Gypsum  spar,  foliated  gypsum,  glass-stone, 
isinglass-stone,  or  selenite,  possessing  a  very  perfect  cleavage,  and  allowing  fine 
lamime  to  be  separated.  2.  Fibrous  gypsum,  or  satin  spar.  3.  Froth-stone,  a  scaly 
crystalline  gypsum.  4.  Granular  gypsum,  or  alabaster,  of  coarse  or  fine-grained 
texure.  5.  Gypsum  stone,  plaster  stone,  or  heavy  stone,  a  laminated  gypsum. 
6.  Earthy  gypsum,  or  plaster  earth. 

NAtim  of  Qjvsam.  Gypsum  is  solublc  in  445  parts  of  water  at  14**  C,  and  in  420  parts 
at  205''  C;  the  solubility  is  increased  by  the  addition  of  sal-ammoniac.  ltd 
behaviour  under  the  influence  of  heat  is  important.  Graham  states  that  gypsum 
placed  in  a  vacuum  over  sulphuric  acid  and  heated  to  100°  C,  loses  half  its  water, 
fonning  the  combination  CaS04-|-HaO,  with  128  per  cent  water.  According  to 
Zeidler,  the  statement  that  this  combination  does  not  harden  wdth  water  is  incorrect. 
By  heating  to  90°  for  some  time  15  per  cent  of  the  water  may  be  expelled ;  at  I7o^ 
according  to  the  experiments  of  Zeidler,  all  the  water  will  be  given  off.  But  of 
more  importance  are  the  experiments  not  carried  on  in  vacuo.  In  the  air  gypsum 
begins  to  lose  its  water  at  loo*',  and  the  loss  is  not  complete  under  132''.  Gypsum 
from  which  all  the  water  has  been  removed  is  termed  burnt  gypsum,  or  spar-lime ; 
it  has  the  property  of  re-forming  with  water  the  same  hydrate,  then  becoming 
hardened.  Advantage  is  taken  of  this  property  in  the  application  of  gypsum  as  a 
mortar.  According  to  Zeidler,  gypsum  as  technically  employed  in  stucco-work,  &c. 
is  not  anhydrous,  but  contains  5*  27  per  cent  water.  If  gypsum  is  **  over-burnt,"  that 
is,  heated  above  204°,  it  loses  the  property  of  hardening  with  water,  probably  owing 
to  the  £Eu;t  of  its  being  converted  into  anhydrite,  which  does  not  re-form  with  water. 
The  water  of  crystallisation  of  the  gypsum  is  saline,  and  consequently  can  be 
removed  by  the  addition  of  salts ;  this  probably  accounts  for  the  hardening  of  unbumt 
gypsum  when  treated  with  a  dilute  solution  of  sulphate  or  carbonate  of  potash,  &c. 
The  hardening  in  this  follows  more  quickly  than  with  burnt  gypsum  and  pure 
water.  With  sulphate  of  potash  a  double  salt  is  formed  according  to  the  formula 
(KaS04-f  CaS04+H20) ;  gypsum  and  bitartrate  of  potash  gives  rise  to  tartar  and 
crystalline  gypsjom.  Chlorate  and  nitrate  of  potash,  as  well  as  sodium  salts,  do  not 
effect  the  hardening  of  powdered  gypsum.  Gypsum  thus  hardened,  if  re-powdered 
and  again  treated  with  sulphate  or  carbonate  of  potash  solution,  hardens  once  more. 
Technical  use  is  made  of  this  property  in  re-hardening  old  or  in  hardening  gypsum 
not  sufficiently  burnt,  by  employing  instead  of  water  a  solution  of  carbonate  of  potash. 

TiM  Boning  of  oypram.      Gypsum  is  bumt  to  effect  the  removal  of  the  water.    Lately 
many  improvements  have  been  made  in  the  methods  of  burning,  it  having  been  found 


334 


CHEMICAL  TECHNOLOar. 


that  the  good  qnalidaa  of  the  gypsum  Dminlj  depend  upon  the  prepmtico. 
is,  however,  a  choice  in  the  stone  to  be  burnt,  the  heavier  and  denser 
gTpsom  fielding  the  best  commercial  article. 

Payen,  by  experimenting  with  large  quantities  of  gypsum,  obtained  the 
tesnlls :— (a.)  The  lowest  temperature  at  which  the  gypsum  can  be " 
vantage  is  60°  C.,  a  long  time  even  then  being  required,     (b.)  A  temt 
no'" — iw>°  yields  the  best  technical  preparation.    {«.)  In  order  that  the  bt 
take  place  equally,  the  g3:p3um  should  be  first  rednced  to  powd< 
The  aim,  of  course,  is  in  all  cases  to  obtain  a  smaU  homogeneous  product 
a  large  quantity  unequally  burnt.     Small  quantities  of  gypsnm  may  be 
iron  vessel  over  a  coi^  fire :  the  operation  should  be  continued  till  no  aqneoni 
is  condensed  on  a  cold  glass  plate. 

EUu.  01  Buisini  orani.  lu  large  quantities  gypsum  is  burnt  in  an  oven  or  Idln,  I 
neoessary  precaution  being  to  avoid  arranging  the  layers  of  gypsum  with  sU 
as  will  reduce  the  gypsum  to  snlphnret  of  lime  (CaS04-|-4C— CaS-(-4COI. 


Fio.  183. 


A  very  eimple  and  veij  | 
construction  of  kiln  is  at: 
Fig.  183.  It  consists  of  * 
strong  masonry,  a,  spanned  l| 
arch,  ventilated  at  a  a  u.  1 
room  is  placed  the  gypsum  01 
fire  being  lighted  in  a  series  a 
chambers  in  the  lower  parti 
room :  brushwood  is  the  bed 
h  is  a  door  through  which  tl 
terial  is  introduced. 
(Fig.  184I  used  by  M.  Scaneg 
verj-  similar.  The  inner  w 
divided  unequaUy  by  s 


CHEMICAL  TECHNOLOQT. 


— i^pkoiitifaotfiomthefloor:  into  the  upper  port  the  gypsum  is  introduced  through  the 
^^g  Jpr  o.    The  onder  part  or  6re-room  is  in  connection  with  a  fine,  E,of  n  fnmace,  a*, 

fluneH  from  which,  driven  by  the  draught  from  ihe  gallery  c 
■mni  lo  pl*r  upon  the  arch  p.  the  hot  air  and  gases  passing  through  e 


Fio.  185. 


«  carried  thiongh 

n  c  into  the  upper 

The  aqueous  vapour  escapes  through  h. 

^  ■ .  Lately  Domesnil'a  oven,  shown  in 

^..^    at   Fig,    1S5,   and   in    sectioii 

"         Ig.  186,  boa  been  much  employad. 

jdapi^'f  Bomenhat  resembles  Scanegatty'a 

j^j-iWn  in  conatmction,  and  consislB  of 

'^         0   under  fiie-room    and    on   apper 

Jpa^  Dom  or  oysd  in  which  the  gypEUm 

JDiiJii-'  linml.    The  flre-ioom  coDtains  aa 

ill-pit,  1,  with  a  door,  a.  a  grate  or 

fid,  c, and  the  hearth,  D.   Adraught,   j 

iiU'<!^  I,  aeeiets  the  combastion.    The  hot 

^««^  Hnd  gases  pass  br  the  fines,  s,  to 

_  ^^^  he  chamber,  r.     The  walls  of  the 

!-="■  'ffen,  J,  k,  L,  are   of  solid  masonry. 

g^.et  is  a  depth,  fnmished  with  a  stair- 

j^Me,  g  h,  to  facilitate  access  to  the 

'"      pinnace,    p,  the  ohinmey,  is  of  iron 

li«*U»ie,  with  s  clack,  g,  wbioh  can  be 

^LitMjUlBled  by  the  chain  c  u.     00  are 

*, , ,  mtilating  pipes.     In  the  wall  of  the 

sC'     himing-room  are  two  openings ;  one, 

«jii^.?%,  throDgh  wbioh  admittance  to  the 

,^;,««rior  is  gained  to  place  the  lower 

yjfcjers  of  gypsum  ;  the  other,  m,  for 

:''"     ps  npper  liters  of  gypenm :  both  are 

^t-Uesed  by  doors  of  iron   plate.      An 

,  ^  nMeal  heat  is  aeeessary  in  the  bnming- 

""^  P"™'  *°^  is  maintained  by  the  pe- 

■w^^eliar  arrangemant  of  the  ohaniber  7. 

Iliil'^^'B  chamber,  closed  at  the  top  by  the 

J^^«p,  0,  ia  provided  with  twelve  open- 

'   '^Dgs,  eacbo'7  metro  high,  the  chamber 

jifr'f'itaeUbeiug  I  metreindiameter.   The 

thuinels    thns    commenced    by    the 

epemngs  in  r  are  continned  to  tbs 

nils  of  the  room  by  the  sxrangement 

of  large  blocks  of  gypsnm.    The  layers 

of  gypsum,  a,  a,  t,  are  placed  cross- 

*iae    alternately    with    intermediate 

lajeiB,  BO  as  to  facilitate  the  dranght 

hi  every  poaaible  way.     The  firing  is 

eontinaed  gently  for  four  hours,  then  strengthened  for  eight  faonrs,  when  all  the  openings 

are  closed,  and  Ave  to  six  cubic  metres  of  coarse  gypsom  powder  spread  equally  over  the 

top  of  the  burning  gypsum.    By  this  means  the  quantity  of  burnt  gypsnm  is  inersased 

without  a  further  eipenditure  of  fuel.     Aiter  standing  twelve  hours  in  the  oven  to  cool 

-*the  whole  oonteote  are  removed. 

oitadtDi  tha  onmo-  After  the  homing  the  gypsum  is  to  a  certain  extent  in  powder, 
'  bnt  if  not  BufBciently  even  it  has  to  be  ground.  The  usual  modes  of  grinding  are  in 
I  a  stomp  or  roller  mill.  After  grinding  the  gypsnm  is  sifted,  and  placed  in  some 
position  where  damp  cannot  affect  it.  Sometimes  the  grinding  and  sifting  are  cun- 
dncted  in  one  apparatus  ;  generally  the  mill  and  sieves  are  aeparnte. 
I  u™  M  onmm.  Gypsum  is  employed  industrially  in  very  many  ways.  It  is  some- 
timea  used  unbumt  in  building ;  it  is  then  difficult  to  manipulate  with  water,  but 
becomes  soluble  by  continued  moialeuing.  The  heavy  and  fast  fine-grained  gypsum, 
■  especially  the  white  powdered  gypsum,  is  used  in  building  for  architectural  purposes. 


336  CHEMICAL   TECHNOLOGY. 

From  the  alabaster  of  Voltena,  Florence  vases  were  fabricated  of  great  beanty :  the 
same  material  is  used  for  making  Roman  pearls.  The  clear  varieties  of  gypsom  are 
used  in  the  manufacture  of  cheap  jewellery,  being  ground  and  polished.  The  fibrouB 
gypsum  is  sometimes  used  for  writing  sand,  as  a  substitute  for  pounce,  &c.  Fine 
gypsum  powder  is  an  ingredient  of  porcelain  manufacture.  Unbumt  gypsom  finds 
further  application  in  the  conversion  of  carbonate  of  ammonia  into  sulphate.  Gypsum 
contains  46'$  per  cent  sulphuric  acid  and  18*6  per  cent  sulphur.  It  is  largely  em- 
ployed in  agriculture  as  a  manure,  both  burnt  and  unbumt.  It  is  generally  received 
that  the  favourable  action  of  the  gypsum  upon  vegetation  is  due  to  the  absorbed 
ammonia  which  is  again  yielded  up. 

Putridity  gives  rise  to  the  formation  of  oarbonio  aoid,  which  combines  with  the 
lime  of  the  gj'psum,  leaving  carbonate  of  lime  and  sulphate  of  ammonia.  This 
explanation  of  the  efficacy  of  gypsum-dunging,  as  it  is  termed,  is,  however,  insufficient. 
The  investigations  of  Mayer  have  shown  that  in  clayey  soils  the  oxide  of  iron,  <&€.,  affords 
larger  and  better  combinations  with  ammonia  than  the  gypsum.  The  quantity  of  gypsum 
used  is  generally  about  5  owts.  to  the  acre,  containing  and  realising  at  the  most  2^^^  cwts. 
of  carbonate  of  ammonia.    Mayer's  researches,  however,  show  that  in  an  acre  of 

Field  land       . .       . .       227  cwts., 
Chalky  soil     . .       . .       158  cwts., 

of  ammonia  were  contained.  According  to  Liebig*s  late  researches  (1863)  it  appears  tbst 
the  gypsum  gives  up  to  the  earth  a  portion  of  its  lime  in  exchange  for  magnesia  and  pot- 
ash. But  it  must  be  borne  in  mind  that  pulverised  gypsum,  as  well  as  unbumt  gypflum, 
when  brought  into  contact  with  a  solution  of  potash,  sets  into  a  difficultly  soluble  maas. 
We  must,  then,  wait  for  an  adequate  theory  until  the  several  reactions  have  been  more 
closely  studied. 

oypeiim  cwtii.  The  employment  of  gypsum  in  casting,  and  in  all  cases  where  im- 
pressions are  required,  is  very  extensive.  A  thin  pulp  of  i  part  gypsum  and  2}  parts 
water  is  made:  this  pulp  hardens  by  standing,  forming  (CaS04-|-2H20).  The 
hardening  of  good,  well-burnt  gypsum  is  effected  in  one  to  two  minutes,  and  more 
quickly  in  a  moderate  heat.  Models  are  made  in  this  substance  for  galvano-plastic 
purposes,  for  metallic  castings,  and  for  ground  works  in  porcelain  manufacture.  The 
object  from  which  the  cast  is  to  be  taken  is  first  well  oiled,  to  prevent  the  adhesion 
of  the  gypsum.  Where  greater  hardness  is  required  a  small  quantity  of  lime  is 
added :  this  addition  gives  a  very  marble-like  appearance,  and  the  mixture  is  much 
employed  in  architecture,  being  then  known  as  gypsum-marble  or  stucco.  The  gyp- 
sum is  generally  mixed  with  lime-water,  to  which  sometimes  a  solution  of  sulphate 
of  zinc  is  added.  After  diying,  the  surface  is  rubbed  down  with  pumice-stone, 
coloured  to  represent  marble,  and  polished  with  Tripoli  and  olive-oil.  Artificial 
scaliogla  work  is  largely  composed  of  gypsum.  Gypsum  is  also  largely  employed  in 
the  manufacture  of  paper. 

Hardening  of  oypnun.  There  are  Several  methods  of  hardening  gypsum.  One  of  the 
oldest  consists  in  mixing  the  bmut  gypsum  with  lime-water  or  a  solution  of  gmn- 
arabio.  Another,  yielding  very  good  results,  is  to  mix  tlie  gypsum  with  a  solution 
of  20  ounces  of  alum  in  6  pounds  of  water :  this  plaster  hardens  completely  in  15  to 
30  minutes,  and  is  largely  used  under  the  name  of  maible  cement.  Parian  cement 
is  gypsum  hardened  by  means  of  borax,  i  pai*t  of  borax  being  dissolved  in  9  parts  of 
water,  and  the  gypsimi  treated  with  the  solution.  Still  better  results  are  obtained  by 
the  addition  to  this  solution  of  i  part  of  cream  of  tartar. 

The  hardening  of  gypsum  with  a  water-glass  solution  is  found  difficult,  and  do 
better  results  are  obtained  than  with  ordinary  gypsum.  Fissot  obtains  artificial 
stone  firom  gypsum  by  burning  and  immersions  in  water,  first  for  half  a  minute,  after 


CHEMICAL  TECHNOLOGY,  337 

which  it  is  exposed  to  the  air,  and  again  for  two  to  three  minutes,  when  the  block 
appears  as  a  hardened  stone.  It  would  seem  from  this  method  that  the  augmentation 
in  hardness  is  due  to  a  new  crystallisation.  Hardened  gypsum,  treated  with  stearic 
add  or  with  paraffine,  and  polished,  much  resembles  meerschaum :  the  resemblance 
may  be  increased  by  a  colouring  solution  of  gamboge  and  dragon's  blood,  to  impart 
a  fiunt  red-yellow  tint  The  cheap  artificial  meerschaum  pipes  are  mannfiactured  by 
this  method. 


z 


(338) 


DmSION  IV. 

\'EaETABLE   FIBRES   AND  THEIR  TECHNICAL  APPLICATION. 


The  Technology  of  Vegetable  Fibre. 


Wood. 

Cotton. 

Flax. 

Paper. 

4387 

43*30 

4363 

43-87 

6-23 

640 

6-21 

612 

4990 

5030 

5016 

5001 

lOOOO 

lOO'OO 

lOOOO 

1 0000 

Vegetable  fibre  or  cellulose,  CeHzoOj,  is  the  fundamental  constituent  of  the  stmcture 
of  plants,  forming  a  large  proportion  of  the  solid  of  every  vegetable.  The  fibres  of 
the  hemp-plant,  the  nettle,  and*the  cotton-plant  are  long  and  fluffy,  and  are  iechni- 
cally  termed  spinning  fibres.  These  and  similar  fibres  are  employed  in  £Eibricatiiig 
woven  tissues,  paper,  &c.  Treated  with  sulphuric  acid,  cellulose  is  converted  into 
dextrose  or  glucose.  The  pure  cellulose  constituents  of  wood,  cotton,  flax,  and  paper 
are  nearly  equal,  as  shown  by  the  following  analyses : — 

Material  of  Cells. 

Carbon    

Hydrogen       ...     . 
Oxygen 


The  vegetable  fibre  for  use  in  spinning  must  be  firm,  pliable,  easily  divided,  and 
capable  of  withstanding  bleaching  operations,  if  required. 

Flax. 

Fbuc  The  flax  used  in  spinning  is  the  fibre  of  the  flax -plant,  Linum  usitatissimum, 
a  plant  of  the  class  PentandrisB,  order  Pentagymie,  in  the  system  of  Linnena,  and 
the  type  of  the  order  LinacesB  in  the  natural  system  of  Botany.  The  flax  is  gathered* 
tied  in  bunches,  and  dried  in  the  fields.  After  drying  the  plant  is  combed  with  an 
iron  or  flax  comb,  to  separate  the  seeds,  and  is  then  bound  in  thick  bunches.  Thm 
flax  fibre  used  in  linen  fabrication  lies  imder  the  bark  of  the  plant,  and  is  surroimded 
by  a  gummy  substance,  or  pectose  according  to  J.  Kolb,  which  must  be  removed  bf 
mechanical  means  to  fit  the  fibre  for  industrial  purposes.  This  is  done  by  "  softening* 
or  "rottening,"  by  which,  according  to  Kolb,  pectin-fermentation  is  set  np,  and  the 
pectin  converted  into  pectic  acid.  The  flax  is  kept  under  water  until  the  impurities 
float  on  the  surface,  leaving  the  fibre  intact :  this  is  the  soaking  method.  Another 
method,  dew-softening,  as  it  is  termed,  consists  in  spreading  out  the  flax  in  layers  to 
the  influence  of  the  atmosphere,  water  being  occasionally  thrown  over  the  flax. 
Both  these  methods  are  unsound,  as  the  flax  is  liable  to  become  rotten,  while  the 
impurities  are  not  thorqughly  removed. 


VEOETABLS  FIBRE. 


339 


BM-<ntrr  (taniiif .  After  vnoij  experiments  with  different  chemieiil  BubBtaacea,  an 
alkaline  bath  and  dilute  aulpliuric  acid  have  been  found  the  best  ai^ents  to  effect  the 
separation.  The  flax  is  placed  in  large  vessels  of  water  heated  to  25 — 30°  by  steam ; 
after  standing  60  or  90  hours  the  operation  is  complete.  This  mode  of  treatment,. 
uded  by  an  alkaline  or  acid  solntion.  yields  the  best  results,  tlie  value  of  tlie  process 
being — I.  That  the  construction  of  the  fibre  is  equally  affected,  rendering  the  article 
better  suited  for  manufacture.  2.  That  the  fibre  does  not  lose  weight  as  in  tlie  other 
methods,  where  10  per  cent  is  sometimes  lost.  3.  That  there  is  a  considerable  saving 
in  expense. 

The  Tttted  flax,  as  it  is  techni-  fto.  1S7. 

eally  termed,  consista  of  cellulose 
and  pectic  acid.  The  next  procesa 
is  termed  trrutching,  and  includes 
the  separating  of  the  fibre  from  the 
woody  structura  of  the  stem.  The 
machine  for  this  purpose  is  shown 
in  Fig.  187.  It  consists  of  two 
parts ;  the  upper,  b.  is  of  wood,  in 
the  form  of  two  splints,  working  on 
hinges.    Wooden  knives  are  placed 

nnder  the  splints,  and  are  arranged  to  act  npon  the  fibre  placed  ij 
upon  the  handle  c. 

Bminf  OF  BktUof  tiu  n&i.  Scotching  consintH  in  two  operations — bmiaing 
the  flax  and  beating  away  the  woody  parts  from  the  fibre.  For  the 
latter  operation  the  Belgian  batting-hammer,  Figa.  188  and  189,  is 
generally  used.  It  is  a  deeply  grooved  wooden  block,  hirnisbed  with  a 
long  curved  handle.  The  Bheaf  of  flai  is  laid  on  the  ground,  untied, 
and  spread  out,  and  ie  beaten  with  the  hammer  by  the  worlunan.  If  the  flax  is  not  enffi- 
eiently  loosened  by  batting,  it  is  Guhmitted  to  the  ewinging-bloak,  Fig.  190,  having  a  ont 


1  A  by  pressure 


Fio.  188. 


Fio.  1S9. 


at  three-fourths  of  its  height  serving  to  bold  about  a  bandfal  of  flax..  This  Sax  is  then 
beaten  with  the  lontch. blade.  Fig.  191,  a  piece  of  hard,  tongb  wood,  generally  walnut- 
wood.    Instead  of  the  swingiug.block  a  grinding -knife,  Fii;.  iqi,  a  ^oiupiinics  a^ei  on  an 


340  CHEMICAL   TECHNOLOGY. 

iron  block.  This  knife  is  formed  of  a  thin  blade,  o,  and  a  heavy  wooden  handle,  p.  A 
bunch  of  flax  is  held  in  the  left  hand,  at  an  angle  for  the  easy  nse  of  knife  with  which 
the  flax  is  beaten.  Notwithstanding  these  clarifying  processes  the  bark  still  adheres  to 
the  flax,  which  has  to  undergo  a  further  operation,  that  of  combing. 

comUng  the  Flax.  The  combing  or  hackling  of  the  flax  removes  all  the  material  detrimental 
to  the  ultimate  spinning  of  the  fibres,  and  also  equalises  their  length,  rendering  them 
smooth  and  parallel.  The  combs  ebce  made  of  zinc  or  sleel,  and  are  of  varying  degrees 
of  fineness,  the  process  commencing  with  a  coarse  comb  and  finishing  with  a  fine  one. 

Tow,  or  Tangled  Fibre.  Howovcr  carcfuUy  the  operation  of  scutching  may  be  performed, 
there  is  always  a  certain  amount  of  waste  resulting  from  the  entanglement  of  the  fibre, 
and  this  waste  is  termed  scutching-tow  or  codilla.  It  is  used  in  the  manufacture  of  ropes, 
and  for  similar  inferior  purposes.  The  flax  fibre,  before  it  is  fitted  for  spinning,  has  to 
be  boiled  in  an  alkaline  ley,  to  remove  the  dirt  and  grease. 

loo  kilos,  of  cleansed  flax  weigh  after 

Bruising       45 — ^48  kilos. 

Scutching 15 — 25    „ 

Combing      10    „ 

FiAx  Bpfnnfiig.  The  Spinning  of  the  combed  flax  into  yam  is  effected  by  hand  and 
by  machinery.  The  combed  flax  is  first  placed  in  bands  of  equal  thickness,  and 
then  stretched.  The  hand-spinning  wheel  is  universally  known.  The  mechanical 
spinning  consists  in — i.  Placing  the  fibres  in  a  parallel  series  of  equal  thickness 
and  length  throughout.  2.  These  bands  are  stretched,  the  finer  the  &biic  to  be 
woven  the  greater  being  the  stretching  required.  3.  By  further  stretching  and 
t^visting  cord  is  spun.  4.  The  fine  cord  is  still  further  stretched  and  twisted.  Tow, 
or  codilla,  is  spun  similarly  to  the  flax,  being  previously  combed  and  placed  in  bands 
of  equal  length.  Flax  yarn  is  either  used  unbleached  or  is  bleached  before 
spinning.    linen  thread  is  obtained  by  twisting  several  cords  together. 

Weaving  the  Linen  Thraadn.  By  Weaving  the  cords  parallel  to  each  other,  chain  cords  are 
spun.    Webbing,  wrappers,  and  thick  fabrics  are  made  in  this  way. 

ubiib.  Linen  is  produced  by  weaving  the  twisted  cord.  The  selvage  is  made  by 
the  return  of  the  shuttle  on  each  side  of  the  fabric.  For  coloured  fabricB 
coloured  threads  are  used  instead  of  white,  only  more  sliuttles  are  required,  one 
shuttle  to  each  colour.  Linen  damask  is  .woven  in  various  patterns,  as  well  as  drill, 
the  difference  being  that  tlie  woof  forms  the  pattern  on  drill,  while  chain-cord  is 
used  for  that  of  damask.  Batiste  is  a  fine  linen  cloth,  slightly  thinner  than 
cambric. 

Hemp. 

Hemp.  Hemp  {Cannabis  sativa)^  is  chiefly  cultivated  for  the  fibre  of  its  inner  barL 
This  fibre,  although  rough,  is  very  hard  and  firm,  and  better  adapted  for  the  manufacture 
of  sail-cloth,  canvas,  rigging,  Ac,  than  any  other.  Its  uses  for  inferior  domestic  pur- 
poses are  manifold.  The  working  of  the  hemp  stalk  accords  essentially  with  thai  of 
flax,  being  steeped  in  water,  dried  and  cru^ed  in  a  hemp  mill.  By  the  old  method 
the  husk  is  crushed  under  a  large  stone  cone,  Fig.  193,  moving  in  a  drcidar  course  aromid 
a  vertical  axis.  The  construction  of  the  new  hemp  mill.  Fig.  194,  is  more  advantageous. 
The  hemp  is  purified  by  winnowing  and  afterwards  combing.  It  is  difficult  to  spis 
on  account  of  its  length,  and  is  woven  in  two  or  three  parts.  Of  late  various  foreign  fibni 
have  been  used  as  Bubstitutes,  principally  the  following : — 

it.<  Substitutes.       a.  Stalk  Fibre, 

I.  Chinese  grass  (Chiruigras  Tschuma)^  a  fibre  from  Urtiea  8,  Boehmerianivea  and  heUrih 
phyllat  which  is  cultivated  in  China  and  the  East  Indies,  Mexico,  the  Valley  of  the  IGs- 
si>sippi,  Cuba,  the  Waldenses  in  Russia,  the  South  of  France,  and  in  Algiers.  The 
Chinese  method  of  treating  the  fibre  is  remarkable.  The  fibre  is  not  spun,  but  cut  into 
appropriately  small  pieces,  these  being  placed  end  to  end,  and  rolled  by  the  hand  until  joined 
together.    The  fibre  is  thus  rolled  quite  smooth  and  does  not  require  pressing.    It  forms 


FEOBTABLE   FIBRE.  541 

ft  beantiriil  teitnre  of  Btngoloi  brigbtness,  colled  grass  linen,  or  China  gnui  clolh.  The 
nw  material  is  oi  a  green  or  blown  colour,  bat  when  bleadied,  can  be  djed  any  colonr. 

I.  The  Great  Nettie,  Urtica  i.  dioica.  The  interior  fibrous  pith  suppliea  the  material 
for^nettle  cloth  and  muslin. 

3.  Bamie  hemp,  from  Urtica  i.  Boehmtria  ulilii,  la  of  the  nettle  Bpeciea,  and  a  nadve 
of  Borneo,  Java,  Sumatra,  and  other  ialanda  of  the  Indian  Archipelngo.  Of  late  varions 
ciperintents  aa  to  its  mode  of  maoufacture  have  been  tried  in  Germany.  It  ia  from 
one  (0  two  metrea  in  length,  of  a  delicate  golden  white,  and  not  bo  bright  and  stiff  as 

r.  Jtltea  Unaeiitima,  ia  a  native  of  the  East  Indies,  of  little 


5.  Jnta  (pout  htmp),  IB  obtained  from  a  lime  tree,  a  native  of  the  East  Indies  and 
China,  CorchUnti  rapsalam  C  lextil\K  C.  ulitoriiu,  C.  iHiquuiu.  The  fibre  for  BpinniiiR 
ia  bronn,  and  in  England  la  nacd  for  eaclicloth  and  coarne  packing  thread.  Ii  is  not  a 
material  adapted  for  purposeB  of  nautical  applioatiou,  aa  it  baa  not  auQicieut  fiimnesB  to 
irithatand  water. 

6.  Bombay  Hemp,  from  Hibisaa  eannabinui.  The  nood;  fibre  of  this  plant  ia  roasted 
•nd  aeparated  by  means  of  beating.    In  England  it  is  use  tor  cordage,  rigging,  &e. 

7.  San  Hemp,  Japan,  or  East  Indian  Hemp,  from  CrotoUiTia  jancea,  resembles  other 
hemp  in  the  length  and  finueBS  of  its  fibre. 

0.  Lraf  Fibre. 

S.  New  Zealand  Flaxes  (Ptomtum  tenax),  are  need  in  their  native  country  for 
artielea  of  domestic  use.  The  leaf  is  stiugbt,  the  fibre  tough,  and  of  a  shining  white. 
Ths  prepared  material  is  similar  to  ordinary  bemp  in  roughness  and  stifEneBS. 

g.  Aloe  Hemp  is  a  native  of  Peru,  the  East  and  West  Indies,  and  Mexico.  A. 
JiMricona,  A.  Vivipara,  A.  FaiAia,  £a.,  where  the  leaf  ia  onltivated  for  its  fibre,  which  is 
Senerally  a  yellow-white,  and  used  for  rope  making, 

ro.  Manilla  Hemp  (Feather  Fibre),  cornea  from  Miaa  texlilit,  M.  troglodytamm,  ami 
v.  fmradiiiaea,  a  native  of  the  Eaat  Indies  and  many  Islands  of  the  Indian  Archipelagu. 
It  IB  oommercialty  known  aa  a  yellow-white  or  brown-yellow  fibre,  from  t-3  to  fx 
melres  long.  The  inside  bark  is  stripped  off  from  the  bottom  upwards,  refined,  and 
eombed.  The  white  kind  is  sill^  and  bright,  and  is  used  in  the  mannfootnre  ol  damask 
fomiinre  and  varionB  fancy  articlea, 

II.  Ananas  Hemp  comes  from  the  West  Indies,  Central  and  Soath  America,  where 
th*  eommoD  Ananas  is  cnltivated,  inanoua  lativa  1.  Bromelia  ananai,  aa  well  as  other 
qtecies.    It  ia  rather  inferior  to  some  for  spinmng. 

II.  Pikaba  Hemp  is  from  ths  leaf  of  the  AOtUia  fiutifera,  a  Brazilian  pabn.  It  is 
Bsed  in  rope- making. 

I],  Coeoa-nnt  Fibre  is  a  reddiab-brown  fibrons  material,  in  which  the  cocoa-nat  shell 
Koeat  mtei/tra]  is  enveloped.  It  ia  very  atiODg  and  elaatio,  and  is  used  for  matting,  ropes, 
nnrdles,  £a. 


342  CHEMICAL  TECHNOLOGY. 

Cotton. 

cottoiL      Cotton  is  the  fruit  of  a  shrubby  plant  of  the  species  Ooisypium^  cultiTated 

in  the  tropics  and  the  Southern  States  of  America  for  manufacturing  puposes.    The 

fruit  consists  of  a  cup-shaped  caljrx,  enclosed  in  a  three-cleft  exterior  calyx,  beazing 

a  soft  white  down.    Another  species,  Oossypium  religiosum,  bears  a  yellow  down, 

used  by  the  Chinese  in  manufacture.    The  down  is  kept  separate  from  the  seed  when 

packed  for  travelling,  to  prevent  its  becoming  oily  and  unfit  for  use.    While  in  a  raw 

state,  it  is  subjected  to  an  operation  termed  ginning  in  a  saw-gin,  to  separate 

the  wool  from  the  seed.    Whitney's  saw.-gin  consists  of  i8  to  20  circular  saw-bladea, 

revolving  on  a  horizontal  axis  about  100  times  a  minute.    The  teeth  of  these  saws 

project  through  a  grating,  seize  the  wool  and  pull  it  through,  the  bars  of  the  grating 

being  too  narrow  to  admit  the  seed.    Twenty  saw-blades  will  clean  400  lbs.,  and  80 

saw-blades,  worked  by   2-horse  power,  500  lbs.,  raw  cotton  per  day.      Of  late 

the  carding  cylinder  is  sometimes  used  instead  of  the  saw-gin.     In  America  oil 

is  largely  extracted  from  the  seed,  30  lbs.  yielding  about  one  pound  of  oiL    The 

seed  is  also  used  for  manure. 

spedos  of  Cotton,  The  quaUty  of  cotton  is  decided  by  its  smoothness,  and  distinguished 
by  the  country  from  which  it  is  imported.  The  various  kinds  are : — North  American : 
Sea  Island,  or  Long  Georgia,  Orleans,  Upland,  Louisiana,  Alabama,  Tennessee,  Georgia, 
Virginia.  South  American :  Fernambac,  Bahia.  Columbian  and  Peruvian.  West 
Indian:  Domingo,  Bahama,  Barthelemy.  East  Indian:  Dhollerah,  Snrate,  Manilla, 
Madras,  Bengal.  Levant :  Macedonian,  Smyrna.  Egyptian :  Mako  or  JiimeL  Anstra- 
lian :  Queensland.    European :  Spanish  and  Sicilian. 

cott&n  Spinning.      Bcforc  being  spun  into  yam,  the  cotton  has  to  be  subjected  to  the 

following  processes : — 

1.  The  loosening  and  purifying  of  the'  raw  cotton  from  the  various  impurities,  snch  as 
sand,  grit,  Ac,  is  accomplished  by  beating  with  the  hand,  or  by  the  Wolf  machine, 
by  means  of  a  cylinder,  the  surface  of  which  is  covered  with  sharp  iron  teeth.  The 
Willow  is  similar  to  the  Wolf,  but  it  is  not  furnished  with  such  sharp  teeth.  The  fulling 
or  rolling  machine  (batteur  ^taleur),  and  the  beating  machine  (batteur  ^luckeur),  are 
both  employed.  The  beating  machine  loosens  the  cotton  that  was  not  quite  openea,  and 
allows  it  to  fall  through  a  grid  beneath. 

The  Fulling  or  Bolhng  Machine  (batteur  4taleur). — The  mechanism  of  this  machine  is 
smoother,  and  pulls  in  &e  cotton  more  quickly,  working  it  into  fibres  of  the  consistenoe 
of  flax,  which  are  drawn  over  the  roller  and  afterwards  carded.  A  new  machine  has  been 
constructed  under  the  name  of  VEpurateur,  a  step  between  the  beating  and  cleaning 
machine,  which  supplies  advantages  not  met  with  before.  The  Epurateur  is  preferabla 
for  the  manufacture  of  wadding. 

2.  The  Combing  or  Carding. — ^Before  the  cotton  is  placed  in  the  carding  machine,  it  is 
passed  under  a  wooden  roller  to  remove  the  surface  thread  and  other  small  imporitiee 
which  fall  off.  After  the  roUing  the  fibre  appears  like  a  delicate  flax.  The  next  operation 
is  the  true  carding,  in  which  two  machines  are  used,  the  coarse  comb,  a  revolving  wooden 
drum  covered  with  steel  teeth,  and  the  fine  comb,  which  finishes  the  separation  of  the 
filaments  of  the  fleece.  The  combed  fleece,  when  it  leaves  the  carding  maichine,  is  in  the 
form  of  a  loose  ribbon  band.  It  is  now  submitted  to  the  doubling  or  lapping  machine, 
to  equalise  the  length  of  the  bands,  the  carding  process  making  the  fleece  loose  and 
of  unequal  substance.  Of  late  the  fibres  are  separated  before  carding,  the  chief  dis- 
tinction being  between  the  long  fibre  of  Georgia  (Sea  Island),  and  the  finer  or  silky  fibres 
of  Florett  sUk. 

3.  The  Stretching  or  Drawing. — The  machine  effecting  this  consLSts  of  sometimeB  two 
to  six  rollers,  but  usually  two  pairs  of  small  rollers,  over  which  the  ribbons  are  drafrn 
until  they  are  of  equal  substance. 

4.  Koving,  or  unwinding  the  ribbon  into  yam,  which  may  be  considered  as  the  first 
process  of  spinning.  The  fleece  is  stretched  100  times  finer  than  it  was  before  drawing, 
and  the  more  it  is  stretched  the  finer  becomes  the  yam  for  spinning.  The  yam  is 
strained  loosely  at  first,  in  proportion  to  its  length,  and  drawn  more  tightly  as  required. 
By  this  process  yams  of  various  degrees  of  fineness  are  easily  obtained.    The  first 


VEGETABLE  FIBRE,  343 

drawing  yields  coarse  yam,  the  subsequent  drawings  famish  the  finest  and  most  delicate 
yam  for  spinning.  If  the  yam  be  too  fine  for  the  pnrpose  reqnired,  as  in  the  manufacture 
of  coarse  fabrics,  several  card  ends,  as  they  are  technically  termed,  are  placed  together 
from  the  first  drawing  and  formed  into  one  ribbon ;  this  process  can  be  continued  until 
the  required  texture  is  obtained. 

n&e  Spinning.  The  yam  (twist)  is  now  rendered  firmer  by  means  of  the  throstle  and  the 
self-acting  mule  machine,  which  has  quite  superseded  the  Jenny.    To  the  mule  machine 

Tun.  we  owe  the  yam  termed  water-twist,  which  is  very  strong  and  indispensable  in  the 
manufacture  of  corded  materials. 

Cotton  FRbiies.        Of  the  different  textures  in  which  cotton  is  employed,  we  have  those 

with  parallel  cords : — 

a.  Linen,  glazed : — i.  Calico,  cotton  and  linen  prints.    2.  Nankeen.    3.  Shirting. 

4.  Towelling  cambric.  5.  Scotch  cambric.  6.  Jaconet,  7.  Printed 
calicoes.  8.  Coloured  textures,  such  as  gingham,  cotton  bar6ge.  9.  Various 
transparent  muslins,  such  as  Zephyr,  organdi,  vapour,  corded  mull  muslin, 
toUe,  and  gauze. 

b.  Cotton  materials  with  cross  cords: — i.   Huckaback.      2.    Cotton  merino. 

3.  Drill.    4.  Bast.     5.  Satin.     6.  Fustian, 

c.  A  rough  woollen  stufif  called  beaverteen,  resembling  fustian,  a  finer  moleskin. 

d.  Other  cotton  fabrics  are: — i.  Dimity.      2.  Drill  and  fustian.      3.  Cotton 

damask.    4.  Pique. 

e.  From  the  same  manufacture  we  get  cotton  velvet  (Manchester). 

Sobcutntes  for  Cotton.  Substitutes  for  cotton  are  found  in  the  black  poplar  {Populus  nigra) 
ajid  the  aspen  (P.  treinula) ;  the  fibres  of  the  latter  are  not  so  elastic  as  some  of  the  sub- 
stitutes discovered.  The  rush  (Junctui  effusus)^  the  German  tamarisk,  and  the  thistle 
{AffrostU)^  the  Salix  pentandra^  the  Zostera  marina,  and  the  flax  tree,  supply  material  for 
manufacture.  Some  twenty  years  ago  Chevalier  Claussen  endeavoured  to  open  the 
filaments  of  flax  by  chemic^  action  by  steeping  the  fibres  in  a  bath  of  i  part  sulphuric 
acid  to  200  parts  water,  and  then  dipping  it  into  a  weak  solution  of  carbonate  of  soda. 
By  this  process  the  flax  is  changed  into  a  downy  mass  resembling  cotton  in  lightness  ;  but 
the  method  was  not  successful,  as  the  firmness  of  the  fibre  was  injured,  and  its  value 
deteriorated  in  other  ways. 

^^^SSVSriS*"      There  is  a  great  difficulty  in  detecting  cotton  in  linen  fabrics  when 

the  fibres  are  closely  interwoven.    The  old  method  of  testing  the  presence  of  cotton  in 

linen  was  by  placing  it  under  a  powerful  microscope,  but  chemical  analysis  presents 

more  reliable  methods.    The  following  tests,  recommended  by  Kindt  and  Lehnert, 

proves  the  existence  of  cotton  in  linen  by  absorption.    The  linen  containing  cotton 

fibre  is  placed  in  a  bath  of  sulphuric  acid  of  183  sp.  gr.  for  i  to  li  minutes.     The 

cotton  fibre  is  immediately  absorbed,  the  sulphuric  acid  acting  upon  it  more  quickly 

than  upon  the  linen;    the  fabric  upon    being  dried    has  a  curled  or    shrivelled 

appearance.    Other  fibres,  sheep's  wool,  silk,  and  flax,  are  now  treated  chemically, 

^d  their  smoothness  and  glossiness  are  attributable  to  chemical  agency,  which  is 

found  to  be  the  greatest  preservative  against  decay.     The  colour  test  of  Eisner  is 

naeful,  but  not  always  successful,  on  account  of  the  transition  of  the  delicate  colours 

^uig  so  instantaneous  as  to  make  it  difficult  to  form  a  decision.    As  a  colour -test 

there  may  be  taken  half  an  ounce  of  the  root  rubia  tinctorum,  macerated  in  6  ounces 

ofalcohoVat  94  per  cent  for  twenty -four  hours.    When  filtered,  the  tincture  appears  a 

clear  brown-yellow.    Pure  linen  fieibrics  immersed  in  it  become  a  dull  orange-red, 

•iid  pure  cotton  yeUow ;  the  flax  fibre  will  assume  a  yellow-red,  and  the  cotton  a 

bright  yellow,  the  fabric  appearing  not  uniform  in  colour  but  streaky.    When  the 

ffl-oric  becomes  so  unequally  streaked  as  to  make  it  difficult  to  discern  whether  it  be 

l^^cn  or  cotton,  the  following  test  will  prove  decisive : — Place  the  streaky  fabric  in  a 

solution  of  spirits  of  wine,  and  then  in  a  weak  solution  of  aniline  red,  by  which  it 


344 


CEEMICAL   TSCnSOLOOr. 


becomes  coloured,  and  finallj  let  it  renuun  one  to  three  ndnnteB  in  ft  veik 
solution  of  Bal-ammoniae ;  the  colour  of  the  cotton  fibre  yiiH  be  dissipated  mi  the 
linen  will  become  a  beantiftil  rose-red.  From  Eisner's  first  test  for  change  of  Miloni 
the  method  of  previously  colouring  the  linen  fabric  wss  established.  Cochineal  wu 
selected  for  this  purpose,  and  the  linen  placed  in  a  weak  solution,  chloride  of  lime 
being  nsed  to  prevent  the  colour  in  the  linen  numing,  while  the  cotton  contained  is 
the  &brio  changes  colour  immediatelj.  FruilcenBtein'H  oil  test  for  oncolonred  &bri(a 
can  be  recommended  for  its  simplicity  and  excellence.  The  fabric  is  dipped  in  olin 
or  rape-seed  oil ;  it  qnickly  beoomea  soaked  throngh,  and  the  enrplns  oU  is  rcmoTed 
by  blotting-paper,  the  linen  fibre  becoming  transparent,  leafing  the  cotton  opaqne. 
'When  an  unbleached  fabric  is  tested  in  this  manner  it  appears  shining  at  first,  bat 
becomes  dimmer  in  the  parts  where  the  cotton  is  present.  A  tnier  method  of 
testing,  however,  is  given  by  the  magnifying  glass.  Bottger  gives  a  test  viih 
potash.  The  linen  faibiie  is  immersed  in  a  concentrated  solution  of  potash ;  in 
about  two  minntea  it  becomes  a  deep  yellow,  the  cotton  fibre  assuming  a  light  yellow- 
Stockhardt  gives  a  spirit  test.  Linen  fabrics  are  placed  in  layets  with  lighted 
brandy ;  the  linen  fibre  extinguishes  the  flame,  while  the  cotton  acts  as  a  wick, 
absorbing  the  spirit.  This  experiment  can  be  snccessfoUy  used  with  coboied 
materials,  with'  the  exception  of  those  coloured  with  chrome-yellow,  chromate  of 
oxide  of  lead.  The  singeing  tost  requires  the  most  delicato  treatment.  The  6bre  is 
placed  in  a  glass  vessel  over  the  flame  of  the  spirit-lamp  until  it  becomes  a  li^ 
yellow;  then  by  microscopic  examination  the  cotton  fibres  will  be  fonnd  coiUd  np. 
while  the  flax  fibres  are  distended  and  clearly  separated  tram  each  other.  Hemp  tui 
flax  act  in  the  same  manner,  but  do  not  separate  so  much.    Nitric  acid  can  be  n 


^iplied  as  to  leave  the  flax  fibre  unchanged  in  colour,  while  the  hemp  immediildf 
becomes  a  pale  yellow,  and  the  New  Zealand  flaxes,  Phormium  tmax,  a  blood-nl 
The  admiztnre  of  cotton  in  linen  fiibrics  became  known  throngh  O.  Zimmenuut, 
who  tried  the  following  test :— Place  the  Maie  in  a  mixtore  of  3  parts  saltpetre  tsi 
3  parts  solphuric  acid  for  eight  to  ten  minntes,  then  wash,  dry  and  treat  with  aloohiJ 
contuning  ether.  The  cotton  so  treated  is  solable  as  collodion,  the  linen  fibre  is  n«t. 
Separation  of  Animal  and  Vegetable  Kbres  by  Means  of  Singeing. — The  mixtore  i< 
placed  near  a  bright  flame  to  singe  until  the  hair  is  consumed,  leaving  a  black  ul? 
nuBs  in  the  same  proportion  as  the  fibre,  i/it  be  mixed  with  sheep's  wool. 


PAPER.  345 

Atiimul  ind  flaxen  fibres  are  separated  hj  boiling  in  potash,  whieh  loosena  the 
filaments  of  wool  or  eilk,  leaving  the  cotton  and  linen  fibres  nnaltered.  Pobl  givea 
OB  the  following  teat ; — Hace  the  fibres  in  a  solution  of  picric  acid  for  one  minute ; 
then  oarafnllj  wash ;  the  wool  or  silk  filaments  will  have  turned  yellow,  the  cotton 
or  flax  fibre  remaining  white.  -This  can  be  applied  to  mixed  fabrics;  but  the  most 
certain  method  is  nnder  the  microscope,  where  tbq  linen  fibre  appears  in  a  cylindrical 
fbrm.  Fig.  195,  and  never  flat.  It  ie  not  elifl'nor  twisted,  and  is  cbieflj'  characterised 
by  the  narrowness  of  its  inner  tnbe.  Hemp  is  similar  to  flax  fibre,  being  easily 
broken ;  its  ends  branch  oat  stiffly,  and  its  tube  is  open.  The  fibres  in  cotton  fabrics 
are  long,  of  a  dose,  thin  testore,  like  a  twisted  bond,  as  in  Fig,  ig6.  Sheep's  wool 
nikder  the  microscope  appears  thicker  than  the  other  filaments,  having  a  {perfectly 
circular  stalk  with  tOe-shaped  Bcales,  as  seen  in  Fig.  197.    The  silken  fibre,  Fig.  19S,  ' 


is  a  slender  oolnmn,  smooth  on  the  exterior  and  easily  distingmshable  from  wool 
Fig.  200,  representing  a  mixed  silken  and  woollen  labtio,  as  it  appears  under  a  low 
power.    Wool  and  cotton.  Fig.  r99,  are  also  easily  distdngoished  from  one  another. 

Fafbr  Makiho. 
EMaretPw.      Paper  is  in  reality  a  thin  felt  of  vegetable  fibres  mechanically  and 
(Jhemically  clarified,  crashed  and  torn  into  a  pulp  suspended  in  water.    This  pnlp  la 
spread  equally  in  thin  layers,  drained,  pressed,  and  dried  into  the  compact  substance 
we  call  paper. 

Of  the  history  of  paper  we  have  the  fallowing: — In  very  ancient  times  men  engraved 
signs  apon  stone,  iron,  lead,  ivory,  wood,  Ao.,  and  by  this  means  handed  down  thdr 
Ikongbts  to  posterity.  Later,  palm  and  other  leaveB  were  need  for  this  pnrpoBe,  also 
TarioDS  barks  of  trees,  etipeaially  the  smooth  inner  bark.  The  old  Germans  wrote  npon 
faireh  bark,  and  there  is  Btil]  an  old  Pagan  poem  in  eiistenoe  written  on  thii  bark.  OUier 
lutiona  painted  with  a  brasb  on  cotton  or  tafteta.  Indeed,  abont  600  years  before 
Christ  the  Egyptians  prepared  the  Cyprus  grass,  Cypenu  papynu  or  Papymt  antiqwmim, 
tor  writing  pnrposoa.  This  gissa  grew  from  ito  3  metres  high  ;  speolmene  are  recy  rare, 
la  the  time  of  the  Boman  Empire  it  was  the  customary  loeans  of  convoying  intelligenoe, 
and  was  oonaidered  a  luxury  mitil  iioo  or  iioo,  when  its  nse  was  diaoontinued.  A  cotton 
cloth  was  then  snbstitQted  under  the  name  of  parchment,  and  was  held  in  great  favour  on 
aceonut  of  its  strength-  Spanish  paper  was  much  esteemed  nntii  imo.  About  tt  ' 
an  attempt  was  made  to  mii  cotton  with  Unen  rags.    This  was  aeoomplished  in  1; 


346  CHEMICAL  TECHNOLOGY. 

is  in  X390,  when  Mnrr  opened  a  large  paper  mill  in  Norembxirg.  Later  still  we  bave 
mention  of  a  paper  mill  by  Shakspeare  in  the  Second  Part  of  Henry  YI.,  the  plot  of  the 
play  being  laid  about  a  century  before  the  time  it  was  written.  EQstory  records  that 
Sir  John  Spielman  owned  a  paper  mill  near  Dartford  in  1588,  for  the  erection  of  whieb  be 
w%s  knighted  by  Queen  EHzabeth.  Since  this  time  the  manufacture  has  steadily 
progressed. 

Pap^^luSSLanrc.  ^®  ^^^^  materials  of  paper  manufacture  are  the  waste  rags  from 
flax,  hemp,  silk,  wool,  and  cotton.  The  linen  rags  are  mostly  in  request  for  making 
the  best  and  most  durable  white  writing  and  printing  paper.  Silk  and  woollen  rags 
are  unfit  for  this  purpose,  as  the  bleaching  material  will  not  act  upon  animal  sub- 
stances. Cotton  in  a  raw  state  requires  less  preparation  than  hemp.  Bags  are 
classes  under  different  denominations, — ^flnes,  seconds,  and  thirds,  the  latter  com- 
prising fustians,  corduroys,  stamps,  or  prints  as  they  are  technically  termed.  The 
waste  refuse  from  the  wadding  machine  used  in  cotton-spinning  is  employed  for 
scribbling  paper.  Bibulous  papers,  such  as  blotting  and  filter  papers,  are  made  from 
woollen  rags,  on  account  of  their  open  texture ;  cotton  rags,  also,  make  a  spongier, 
looser  paper  when  unmixed  with  linen. 

sutetitiito  for  Bags.  The  oonsxmiption  of  paper  in  Europe  has  more  than  doubled  within  the 
last  fifty  years,  and,  owing  to  the  inefficient  supply  of  rags,  substitutes  had  to  be  found 
in  straw  and  wood.  The  Chinese  first  used  yegetable  pulp  for  paper  manufacture.  The 
inner  bark  of  the  bamboo  is  particularly  celebrated  as  affording  a  paper  yielding  the  most 
delicate  impressions  from  copper-plate,  and  this  paper  was  originally  called  India-proof. 
The  Chinese  also  use  the  bark  of  the  mulberry  and  elm  trees,  hemp,  rice-straw,  and  wheat 
Among  the  straw  species  appears  the  maize  (Indian  com) ,  from  Uie  fibre  of  which  a  paper  is 
made  that  for  purity  and  whiteness  cannot  be  equ^ed.  Also  the  Andropogon  glycickyhm, 
or  Sorghum  saccharatunit  a  native  of  North  America,  is  used ;  in  fact  nearly  every  speeies 
of  tough  fibrous  vegetable,  and  even  animal,  substance  has  been  tried,  but  of  these  straw 
has  been  most  successfully  appUed,  in  combination  with  linen  and  cotton  rags,  when  the 
silica  contained  in  the  straw  is  destroyed  by  means  of  a  strong  alkali.  If  the  straw  is 
not  properly  prepared  the  paper  will  be  brittle,  and  unfit  for  use.  The  use  of  straw  is 
not  very  extensive,  owing  to  the  extra  expense  of  preparation,  and  its  waste  under  the 
process.  It  is  used  for  making  common  brown  paper,  but  it  is  chiefly  used  for  giving  a 
BtifEness  to  cheap  newspapers.  All  soft  woods  are  fit  for  paper-making,  such  as  the 
trembling  poplar,  linden,  aspen,  fir,  &c ;  the  pine  is  of  too  resinous  a  nature  to  be  of 
much  value.  The  preparation  from  wood  is  msuie  in  the  following  manner : — the  bark  is 
sawn  and  split  into  suitably  sized  pieces,  and  tiie  fibres  separated  by  pressure  between 
horizontal  rollers  copiously  supplied  with  a  stream  of  water.  The  water,  which  formi 
two-thirds  of  the  mass,  is  then  removed  by  further  pressure,  generally  hydraoUc  In 
1867,  Bashet  and  Machard  treated  the  woody  material  with  hydrochloric  acid.  Later,  waste 
wood  has  been  treated  chemically,  in  the  large  manufactory  of  Manayunk,  of  Philadelphia. 
The  finest  wood  is  set  apart  into  lots.  No.  i  is  used  for  making  writing  and  printing 
paper ;  No.  2,  wall  paper,  packing  paper,  and  inferior  kinds  of  printing  paper ;  Nos.  3 
and  4  for  label  and  pastiiig  paper.  Spanish  woods  are  largely  used,  on  account  of  their 
smoothness. 

Hinemi  Additions  We  find  minerals  used  in  the  present  manufacture.  A  moderate  addition 
to  the  Bags,  ^f  ^^  jximersl  body  to  the  paper  material  whitens  the  whole,  and  for  inferior 
or  ordinary  paper  is  successfully  employed.  It  is  unfit  for  very  thin  paper,  making  it 
shiny  and  brittle.  A  profitable  addition  of  mineral  matter  is  from  5  to  10  per  cent  of  the 
wei^t  of  paper,  a  greater  addition  making  the  paper  dull,  brittle,  and  hairy  to  write  upon. 
The  usual  mineoral  mixtures  in  frequent  use  at  the  present  day  are — day  free  from  ssnd, 
China  clay,  and  kaolin.  Aniline  pearl-hardening,  dissolved  into  a  pulp  resembling  dsff 
is  most  preferred,  being  not  so  expensive.  In  1850  it  was  favourably  received,  under  the 
names  of  fixed  white,  raw  white,  patent  white,  or  permanent  white.  With  100  kilos,  of 
paper  pulp  15  kHos.  of  the  paste  is  generally  employed. 

"^o'J^gJ^^P"  The  old  method  of  making  paper  by  hand  was  from  the  pulp  <rf 
waste  paper  placed  in  a  mould  of  the  required  size ;  but  this  method,  althongh  still 
used  for  writing  paper,  was  found  to  restrict  the  size  of  the  sheets,  and  different 
methods  were  tried  with  varied  success,  until  a  machine  was  invented  which,  without 
the  aid  of  moulds,  manufactured  the  paper  in  any  length. 


PAPEJt.  347 

****»j,j«g,2f«»*»«      The  Cutting  and  Sorting  of  the  Rags. — ^The  first  operation  is  per- 
formed hy  two  machines,  called  the  half-hoUander  and  the  whole-hollander.     The 
rags  are  next  treated  chemicallj  with  potash  to  rot  them.    By  the  old  method,  rags 
were  cut  into  pieces  about  4  inches  square,  by  being  drawn  across  a  sharp  knife  fixed 
upon  a  table.    Machinery  has  superseded  this  arrangement,  and  various  cutting 
machines  have  been  invented,  among  which  we  may  mention  that  of  Mr.  Davey,  in 
which  a  horizontal  knife  revolves  around  a  fixed  cylinder  cutting  the  rags  into  strips. 
Bennet's  cutting  machine  consists  of  two  knives  radiating  from  a  wheel,  and  bearing 
against  another  knife.    Some  machines  are  constructed  with  a  quantity  of  circular 
sharp-edged  steel  plates,  like  the  machine  of  Uffenheimer,  of  Vienna.    After  cutting, 
the  rags  are  cleansed  from  dust  and  other  impurities  by  the  Willow  machine.    The 
best  kind  of  sifting  machine  is  in  the  form  of  a  drum  with  the  upper  part  covered 
with  a  wire  grating.    The  rags  are  put  in  by  a  side  door,  which  acts,  as  the  drum 
revolves,  as  a  refuse  door,  castiog  off  the  sand  and  impurities,  leaving  the  rags  win- 
nowed.    They  are  next  boiled  m,  an  alkaline  ley,  or  solution  of  4  to  10  pounds 
of  carbonate  of  soda,  with  one-third  of  quick-lime  to  100  of  the  material.    The  rags 
are  placed  in  large  cylinders  slowly  revolving,  and  causing  them  to  be  constantly 
turned  over.    Into  these  cylinders  a  jet  of  chlorine  water,  with  a  pressure  of  30  lbs. 
to  the  square  inch,  is  directed.      H.  Volter  patented  in  1859  a  horizontal  steam 
cylinder,  which  receives  the  steam  from  a  tubular  guide-cock  provided  to  the  boiler, 
an  inner  cylinder  revolving  to  move  the  rags.    The  distant  end  of  the  boiler  and  the 
tubular  cylinder  draws  up,  and  the  mass  is  easily  poured  into  the  washing  machine 
when  in  a  fluid  state  (Silberman's  Washing  Hollander.)    Although  partly  cleansed  by 
the  above  method  the  rags  still  require  further  boiling. 

teHa^Efll^^SwJotoSiiiT.  The  machine  used  in  separating  and  rending  the  rags 
are: — 

1.  The  German  stamping  machine. 

2.  The  rag  mill  (rolling  hoUander). 
a.  The  half-hollander. 

p.  The  whole-hoUander. 

Formerly  the  ragd  were  rotted  before  crushing,  being  placed  in  a  stone  trough,  where  in 
two  or  tlu'ee  days  they  became  heated,  and  developed  a  strong  ammoniacal  odour. 
When  the  surface  was  covered  with  a  mould,  the  rags  were  sufficiently  decayed  for  the 
purpose  of  manufacture.  They  were  then  taken  out  in  a  brown  mass,  those  remaining 
behind  as  sediment  bdng  used  for  coarse  paper.  The  present  method  of  boiling  the  rags 
with  alkalies  is  preferable,  giving  the  paper  greater  firmness. 

Stamp  MMhine.  The  (German  stamp  machine  is  at  the  present  time  only  to  be  found  in 
smaller  manufactories.  It  is  of  the  nature  of  a  hammer.  Six  or  eight  stamp  rods  are 
fized^  into  a  strong  oak  beam,  and  work  intermittently  with  a  set  below.  Through  an 
opening  provided  with  a  fine  sieve  the  water  is  conveyed  away.  As  the  hanuners  rise 
and  fall,  the  stamp  holes  serve  for  a  water  conduit.  Three  to  five  hammers  work  in  each 
hole.  The  rags  are  mixed  with  sufficient  water  to  form  a  pulp,  and  remain  in  the 
maoldne  12  to  20  hours  and  more. 

The  HouuMier.    The  hoUauder  mill  is  fast  becoming  a  universal  fieivorite.  It  is  somewhat 

similar  in  principle  to  the  stamping  machine,  but  in  strength  and  speed  greatly  excels 

every  other  machine.    Fig.  itoi  is  a  half-hoUander ;  Fig.  202  the  vertical  section 

through  the  line  a  b.    The  chief  characteristics  of  the  hoUander  are: — i.   Speed  of 

revolution  of  the  trimming  knife.    2.  The  box  of  knife  edges  under  the  revolving 

cylinder.    3.  The  trough  and  revolving  cylinder.    4.  The  cap  or  partition  above  the 

trough  to  prevent  the  mass  being  cast  out  when  in  motion.    The  trough,  cc,  is  a  long 

oblong  cistern  of  cast-iron,  stone,  or  wood  lined  with  lead.    The  cover  rests  upon  a 


343  CHEMICAL  TECHSOLOQY. 

partition,  a;  a;,  of  equal  height  with  the  ontaide  wall.  The  machine  is  diyided  into  t«o 
parts,  the  wortdng  side  in  which  the  rags  are  torn  or  shredded  between  the  knife- 
edges  on  the  cylinder  and  those  in  the  box,  and  the  running  side  into  which  the 
shredded  rags  are  thrown  by  the  revolving  cylinder.  Under  the  cylinder  is  i 
massive  oak  block,  /,  the  craw,  its  concave  sniface  comprising  the  fourth  part  of  tli* 
circumference  of  the  cylinder.     The  ^de  y  is  a  little,  and  i  mach  inclined.    HiU- 


wAy  between  A  i  are  two  strong  beams,  I,  m,  supporting  the  metal  bearings,  in  whid 
works  the  axle,  oo,  of  the  cylinder.  From  the  roller,  n,  a  number  of  cntiera  ms 
parallel  to  the  axis.  The  knives  are  of  soft  steel,  and  in  the  whole -hollander  some- 
times bronze.  Beneath  these  a  series  of  knives  is  placed,  against  which  the  r»gs  an 
drawn  by  the  cylinder.  In  order  that  by  the  movement  of  the  cylinder  none  of  iJw 
material  should  be  thrown  oat,  a  cover  is  provided,  the  dirty  water  thrown  «p 


falling  through  the  oerea,  v  e,  and  flowing  throu^  tlio  opening,  gg.  Ckm  watv 
flows  in  from  the  top  of  the  hollander.  The  washing  finished,  the  water  ^pe  ii  ^^ 
by  means  of  a  sliding  partition,  each  partition  having  an  inn^  one  to  prsvcot  Iba 
pnlp  passing  away.  The  rags  are  poured  into  the  top  of  the  hollander  witli 
the  roquiwte  quantity  of  water.  -  The  roller  revolves  lOO  to  150  times  a  minute,  tba 


Flo.  ao3. 


kaivcB  catting  more  retkdilj  in  the  fluid.  Having  passed  the  cylinders  and  the  lower 
set  of  knives,  the  mass  flows  over  the  steep  elope  of  the  craw,  z,  while  the  roller 
contiuoes  its  work.  This  mode  has  this  advantage,  that  the  rags  have  an  tminter- 
rupted  flow,  and  that  all  parts  have  the  same  resistance  under  the  roller.  The  work 
of  the  half-bollaniier  is  of  two  hours  duration  for  soft  and  clean  logs,  a  longer  time 
being  requisite  for  coarse  and  dirty  materials. 

BiHeuiif  uuPnip.  After  this  the  mass  is  placed  is  another  machine,  the  whole- 
hollander,  and  bleached  h;  a  solution  of  chloride  of  lime,  chlorine  water,  chlorine 
gas.  or  other  bleaching  omenta.  The  lime  is  retained  in  the  machine  nntil  tlie 
rags  are  sufficientlj  bleached ;  the  pulp  is  then  let  down  into  bng  slate  cisterns  to 
•leep  before  placing  in  the  beating  machine. 

An  arrangement  for  bleaching  bj  meatia  of  chlorine  gas  is  exhibited  in  Fig.  203. 
The  gas  passes  from  the  generators,  a  a,  into  a  wooden  chamber,  a,  in  which  the 
damp  pulp  is  arranged  on  shelves.  These  shelves  have  openings  admitting  the 
chlorine  gas  as  shown  bj  the 
arrowB.  The  surplus  gas  escapes 
through  opening,  e,  to  a  reservoir, 
which  is  also  used  for  bleaching 
the  palp.  The  pulp  is  then  re- 
moved, washed  \>j  a  solution  of 
soda,  potash,  or  urine,  and  after 
standing,  worked  with  antiehlore,  a 
term  given  bj  bleachers  to  an;  salt 
thai  neutralises  the  pemicioua 
after  effects  of  chlorine  upon  the 
-  pnlp-  Bj  Una  means,  in  each  100 
kiloe.  of  half-stuff.  2'5  to  5  kilos,  of 
common  salt  is  developed  bj  the 
action  of  the  chlorine  gas  upon  the 
soda.  When  bleached  bf  chloride 
of  lime,  I  to  z  kilos,  ore  applied  to 
100  kiloB.  of  pulp.    When  greater 

smoothness  is  required,  a  little  hydrochloric  or  sulphuric  acid  is  added,  although  care 
most  be  taken  in  its  use,  for  applied  too  largely  it  destroys  the  fibre.  Orioli  employs 
hypochlorite  of  aluminium,  known  by  the  name  of  Wilson's  bleaching  preparation, 
chloride  of  aluminium  being  obtained  on  the  one  hand,  while,  on  the  other,  all  the 
bleaching  effects  arise  from  the  delivery  of  ozonised  oxygen  (AliCl60}=30+A]iCl«). 
Varrentrapp's  hypochlorite  of  zinc,  under  the  name  of  Varrentrapp's  bleaching- 
powder,  is  worthy  of  notice  as  being  extensively  used.  In  this  powder,  chloride  of 
lime,decomposedwithzinc  vitriol,  or.  better,  with  chloride  of  zinc,  isemployed.  When 
bleached  by  chloride  of  zinc,  the  mineral  add  decomposes  the  chloride  of  lime, 
therefore  no  risk  is  incurred  by  the  fibre. 

inudiiiin.  When  the  bleach  retains  chlorine,  it  is  washed  in  soda,  potash,  or  anti- 
ehlore, to  neutralise  the  adhering  hydrochloric  acid,  which  merely  washing  in  water 
would  not  eiTect.  The  chief  constituents  of  antiehlore  are  sulphite  of  soda, 
chloride  of  tin,  and  hypliosulphite  of  soda.  A  molecule  of  sulphite  of  soda 
(NajS03-|-7H,Ol  removes  i  molecule  of  clilorine  ICl,),  whilst  hydrochloric  acid 
and  sulphate  of  soda  are  formed.     A  mixture  of  sulphite  with  carbonate  of  soda 


350  CHEMICAL   TECHNOLOGY. 

is  employed  to  neutralise  the  hydrochloric  acid.  The  sulphate  of  soda  and  chlodde 
of  sodium  are  removed  by  washing.  Sulphite  of  calcium  is  greatly  approved,  and 
18  considered  to  be  as  effective  as  antichlore,  when-  applied  as  the  correspondisg 
sodium  salt.  A  molecule  of  tin-salt  (SnCl^+^HaO),  is  taken  up  by  a  molecule  cf 
chlorine  (GU),  by  which  chloride  of  iin  (SnCl4)  arises.  After  the  working  is  com- 
pleted, so  much  carbonate  of  soda  is  added  as  is  required  to  saturate  the  hydrochlorie 
acid.  A  molecule  of  hyposulphite  of  soda  (NaaSaOs-f  sHaOj,  absorbs  4  molecules  of 
chlorine,  whilst  sulphate  of  soda,  hydrochloric,  and  sulphuric  acids  are  formed. 
Some  salts  of  lime  are  also  commercially  known  as  antichlore. 

Bindog.  Notwithstanding  the  careful  chemical  bleaching,  the  pulp  has  still  a  yeUow 
tinge,  and  requires  a  colouring  matter  which  is  generally  introduced  in  the  process  of 
beating.  The  blues  generally  used  are  ultramarine,  Paris  blue,  indigo,  aniline  blue, 
oxide  of  cobalt.  With  100  kUos.  of  the  dry  paper  stuff,  0-5  to  1*5  kilos,  of  ultramarinB 
are  mixed,  according  to  the  strength  of  the  colour  required. 

Bisixig.  The  pulp  requires  sizing  to  preserve  the  colour.  It  is  guided,  as  it  issues 
from  the  hollander,  through  a  tub  of  size,  and  afterwards  carried  over  skeleton 
drums,  containing  revolving  fans  to  dry  it  as  it  passes ;  heated  cylinders  are  also 
used  for  drying.  Starch  is  used  to  give  a  thicker  consistence  to  the  size,  whidi 
is  generally  made  from  the  best  glue,  resin  being  added  in  quantities,  never 
exceeding  3  Idlos.  per  100  kUos.  of  pulp,  to  impart  the  desired  amount  of  stifihess. 

a.  Hand  Paper. 

BtndnJng the  Paper  shMta.  There  are  three  ways  of  straining  or  filtering  the  pulp:— 
First,  by  straining  through  a  brass  sieve  with  fine  slits  to  allow  the  pulp  to  pass, 
and  retaining  all  lumps  and  knots.  Secondly,  by  pressure ;  and  thirdly,  by  evaporB- 
tion.  In  the  first  operation  the  sheet  is  formed  by  a  mould  of  the  size  required, 
l)eing  dipped  into  a  tub  of  pulp  previously  strained.  The  pulp  becomes  distended  to 
a  thin  layer  and  the  water  filters  off  The  tub  is  either  round  or  of  a  quadrangnltf 
shape  made  of  wood,  lined  with  lead.  A  broad  board  running  across  the  tub 
is  called  the  bridge,  and  a  smaller  one  under  the  large  one  the  little  bridge.  The 
large  bridge  has  a  pointed  support,  technically  termed  the  donkey,  for  the  form  or 
frame  to  lean  against. 

The  sifting  machine,  technically  termed  the  knotter,  used  in  the  manufsctare 
of  hand-paper,  consists  of  an  upright  cylindrical  sieve,  in  which  an  inner  cylinder 
revolves.  As  the  whole-stuff  is  taken  from  the  tub,  the  remainder  becomes  massed 
together,  and  steam  or  other  pressure  is  employed  to  force  the  pulp  through  the  siere 
and  cylinder,  the  latter  retaining  the  lumps  and  knots.  The  paper  forms,  upon  wbich 
the  whole-stuff  is  placed,  are  constructed  with  brass  wires  to  allow  the  water  to  drain 
off,  retaining  the  pulp.    There  are  two  kinds  of  forms : — 

X.  The  Bibbed  Form.— A  square  or  oblong  frame  of  oak  or  mahogany  with  parallei  latfi 
wires  and  cross  wires  at  intervals  to  steady  them.  Lined  paper  is  made  on  this  fonSt 
and  is  not  much  glazed  on  account  of  the  time  and  expense,  being  reckoned  an  inferior 

paper. 

2.  The  YeUum  Form. — ^A  frame  of  finer  brass  wire-work.  Yellum  paper  is  made  on  this 
form,  and  has  a  delicate  even  surface  ;  it  can  be  made  to  present  any  degree  of  glosdnen 
by  pressing  and  satining.  When  held  to  the  Ught  it  appears  uniform,  not  poseessisg 
bright  and  opaque  lines  as  in  the  former  paper. 

A  ribbed  form  similar  to  the  vellum  form  is  employed  in  the  manufacture  of  paper  di»- . 
tlnguished  by  trade  marks,  coats  of  arms,  <&c.,  the  impress  of  the  wire  forming  what  ii 
termed  the  water-mark ;  bank-notes  are  made  separately  in  a  mould  in  this  way.    Ihe 
«dge  of  the  form  makes  the  edge  of  the  paper,  forms  b^mg  used  according  to  the  siie 


PAPER,  351 

leqniied ;  also  the  quantity  of  the  whole-stufiF  Tsries  in  aeoordanoe  with  the  required 
thiokneM  of  the  sheets.  Felt  is  extensiyely  used  in  the  manufacture  of  paper ;  it  is  unlike 
the  ordinary  felt  for  hats,  being  a  coarser,  looser,  white  woollen  fabric,  more  suitable  for 

roUing. 

The  work  of  the  pulp-tub  Is  divided  into  two  parts,  the  squaring  and  the  scooping ;  the 
latter  is  the  placing  of  the  pulp  in  the  mould,  the  former  the  placing  of  the  sheets 
between  felt.  The  tub  is  stirred  occasionally  with  a  pointed  stick,  technically  termed  the 
scoop  stick.  The  pulp  is  taken  out  on  the  form  in  a  sloping  position,  shaken  a  little  to 
aid  cohesion,  and  finally  placed  on  the  small  bridge.  The  next  sheet  is  placed  on  the 
large  bridge.  The  form  is  laid  in  a  sloping  position  against  the  donkey-rest  to  drain,  and 
the  paper  finally  placed  on  the  felt  to  diy  a  little,  the  empty  form  returning  to  the  tub. 
The  first  paper  sheet  is  coyered  with  felt,  on  which  the  next  is  placed ;  the  average 
number  of  sheets  manufactured  exceeding  5000  a  day. 

7nwiii(tiMP»ptr.  As  soon  as  there  is  a  sufiicient  number  of  sheets,  they  are 
made  into  a  thick  bale  and  placed  under  the  press,  the  number  of  sheets  comprising 
a  bale  being  generally  181.  Three  bales,  181X3=543  sheets;  twenty  quires  =480 
sheet  sized,  and  500  unsized.  Pressing  gives  firmness  and  glossiness,  and  by  con- 
tinued pressing  exceeding  smoothness  is  obtained. 

DiTing  tiM  Paper.  The  process  of  pressing  has  not  quite  removed  the  water  from  the 
paper,  which  has  to  be  dried  in  an  airy  chamber,  the  sheets  being  placed  separately, 
or  two  to  five  together  as  required.  An  expert  workman  can  place  800  to  900  layers 
of  two  to  five  sheets  each  in  a  day,  as  well  as  hanging  and  drying  the  sheets  and 
taking  them  off  the  cord. 

sisiM  ttie  Paper.  The  paper  is  not  durable  unless  it  is  sized,  and  is  only  used  for 
filtering,  packing,  printing,  or  scribbling  papers,  ^ing  gives  the  paper  substance 
by  filling  the  pores,  and  making  it  firmer,  stiffer,  and  harder.  Ordinary  size  dis- 
solved in  water  will  not  always  prove  effective,  and  it  is  necessary  to  add  a  solution 
of  an  aluminum  salt,  such  as  that  of  alum,  sulphate  of  alumina,  or  chloride  of 
aluminium,  to  prevent  decay.  Without  chemical  preparation  the  sheets  are  rendered 
sticky  and  have  to  be  sized  separately,  but  with  the  above  addition  80  to  100  sheets 
can  be  successfully  sized  by  hand ;  a  good  workman  can  size  40,000  to  50,000  sheets 
in  twelve  hours.    The  sheets  must  not  be  dried  too  quickly  after  sizing. 

Piepuiac  the  p»p«c  After  the  sized  paper  is  pressed  and  dried,  it  requires  further 
preparation  to  make  it  fit  for  use.  The  first  process  consists  in  the  finishing  or  trimming 
to  remove  all  the  little  specks  and  blemishes,  and  to  smooth  the  sheets.  The 
finished  sheets  are  counted  and  placed  together,  the  workman  by  continued  practice 
counting  8000  to  15,000  sheets  as  he  places  them,  and  separating  them  into  whole 
and  half  quires,  twenty -four  sheets  of  sized  and  twenty-five  sheets  of  unsized  paper 
making  a  quire ;  the  upper  and  under  quire  of  each  ream  being  placed  on  an  extra 
sheet,  known  as  outsides.  The  even  and  glazed  surface  is  mostly  obtained  by  hot- 
pressing,  when  every  sized  sheet  is  interposed  between  two  unsized  sheets;  this  is 
called  interchanging.  The  preparation  of  the  various  kinds  of  paper  is  now  accom- 
plished, with  the  exception  of  the  finest  letter  paper,  which  requires  an  extra  process 
to  give  it  a  final  gloss,  by  pressing  between  the  rollers  of  the  satining  machine.  The 
different  varieties  of  paper  are  classed  under  three  denominations : — 

ib«  Dis^nmi  Kind.      A.  Writing  and  drawing  paper,  the  smaUer  kinds  of  copy  paper,  deed 

of  Paper.  paper,  the  finer  post  and  letter  paper,  and  vellum  letter  paper. 

B.  Printing  paper  for  books,  as  distinguished  from  copy  printing,  deed  printing,  post 
and  veUum  printing,  note  and  copper-plate  printing  paper.  Silk  papers  for  valentines, 
ornamented  with  gold  or  silver,  and  printed  from  engraved  copper  plates. 

0.  The  looser  textured  papers,  such  as  unsized  parcel  paper ;  the  better  kinds  are  filter- 
||i^d  blotting-papers.  Packing  paper  is  half -sized,  and  appears  as  a  yellow  straw  paper, 
blue  sugar  paper,  and  pin  and  needle  papers. 


35a  CHEMICAL   TECHNOLOGY. 

p.  Machine  Paper, 

Mannfaetnre  of  Machine  Paper.      Mamifac taring  paper  bj  hand  requires  mnch  time  and 

labour,  and  machinery  is  found  to  be  quite  as  efficient.     Endless  paper  of  any 

breadth  can  be  made  by  machinery  with  the  same  amount  of  strength  and  firmness 

as  hand  paper.    The  straight  form  and  tlie  vibrating  machine  are  used  for  finer  papei. 

X.  It  is  requisite  that  the  machine  should  make  the  pulp  of  a  suitable  consistenoe  \ij 
diluting  it  with  water. 
a.  Purify  the  whole-stufF  from  knots. 

3.  When  free  from  knots  work  the  material  by  means  of  regulators,  dellTering  the  stuff 
from  the  form,  and  producing  by  the  uniform  flow  of  the  pulp  a  smooth  paper  Im!  of  the 
breadth  required. 

4.  Be  80  regulated  that  the  stream  of  whole-stuff  may  form  a  sharply  turned  leal 

5.  Free  the  paper  leaf  from  water,  so  that  it  only  requires  drying  in  an  aiiy  ohanibtf 
and  pressing. 

6.  For  removing  the  water,  steam  cylinders  are  principally  used. 

7.  The  finished  paper  is  out  into  sheets  by  the  paper  outtmg  machine. 

After  the  whole-stufif  is  thinned  to  a  consistence  easily  jnoved  by  waier,  it  flom 
to  the^otter,  placed  in  a  perforated  cylinder  of  sheet  brass,  which  is  supplied  with 
an  interior  mechanism  reyolving  with  greater  velocity.  One  of  the  best  knotting 
machines  is  Mannhardt  and  Steiner's,  of  Munich.  After  the  whole-staff  is 
purified  by  the  knotting  machine  it  passes  out,  and  the  whole-stufiT  reservoir  is  sup- 
plied anew.  In  course  of  time  the  consistence  becomes  altered,  sometimes  produdng 
a  thicker  sheet  than  required;  this  variation  is  obviated  by  the  regulator,  an 
essential  in  the  paper  manufactory.  A  complete  paper  machine  is  shown  in  Figs.  204 
and  205.  The  drawing  is  divided  into  two  parts;  Fig.  205  is  seen  as  the  oontinoft- 
tion  of  Fig.  204.  After  the  whole-stuff  has  passed  from  the  knotting  machine,  a,  it 
flows  into  the  small  trough,  a',  and  is  forwarded  by  the  regulators  to  the  fonn.  The 
form,  a"a"t  is  an  endless  wire  sieve,  similar  to  the  vellum  form,  the  upper  part 
extending  horizontally  over  a  number  of  copper  rollers.  The  forms  are  from  3  to 
4  metres  long,  and  i  to  16  metres  broad,  and  are  moved  by  means  of  a  band 
passing  over  pulleys.  Next  to  the  regulators,  a',  the  roUers  lie  closer  together. 
The  form  of  course  has  a  double  motion,  advancing  in  the  direction  of  the  paper 
sheet,  which  is  carried  to  a  vacant  part  of  the  wire  and  deposited,  the  form  oompletmg 
its  circuit  underneath.  Periodically  the  form  receives  a  shaking  or  vibratory  move- 
ment breadthways.  The  paper  has  sometimes  an  uneven  margin,  and  to  equalise  the 
substance  of  the  layer,  two  fine  brass  wires  are  placed  near  the  under  edge  of  the  form, 
while  leather  bands,  mm,  kept  in  place  by  the  pulley,  t,  are  placed  'on  both  sides  of 
the  form  to  keep  the  sheet  straight,  the  bands  passing  through  a  vessel  of  water,  iit 
to  cleanse  them  of  the  adhering  pulp.  The  water  in  the  cistern,  c,  cleanses  the  wire- 
work  forms.  It  is  now  necessary  to  commence  the  drying  of  the  pulp;  this  is 
effected  by  an  air-pump,  or  preferably  by  suction  apparatus  placed  in  the  box,  ddy 
over  which  the  whole  breadth  of  the  paper  sheet  passes.  After  the  paper  leaf  passes 
the  box,  it  is  pressed  under  a  wirework  cylinder,  e^,  under  which  is  a  corresponding 
cylinder ;  these  perforated  rollers  are  called  dandy  rollers.  The  paper  sheet  is  now 
somewhat  pressed  and  dried ;  the  empty  form  returns,  and  the  leaf  passes  free  frdon 
the  form  over  an  endless  felt  to  the  wet  press,  h  h,  which  consists  of  two  iron  rollers : 
one  glazing  the  paper,  the  other  passing  the  leaf  to  another  pair  of  rollers,  h'k\ 
Fig.  205,  which  press  and  dry  the  leaf.  The  paper  leaf  is  finally  submitted  to  the 
dry  press,  which  consists  of  a  larger  cast-iron  cylinder,  w,  »,  w,  interiorly  heated.to 
nearly  130''  C.  by  steam.    These  cylinders  and  the  corresponding  rollers,  u\  v\tc\  are 


covered  with  felt.  By  (he  donble 
preesing,  the  paper  becomes  dry 
and  requires  d&inping  before  the 
final  pressing.  The  press  ttie  ia 
not  so  effective  as  vv,  as  it  dries  the 
surface  uneven];,  causing  one  side 
to  be  more  glazed  tlion  the  otl  c>r 
The  finished  paper  passes  uniiir 
the  roller,  y,  t«  the  windlass,  j  and 
ie  transferred  by  means  of  the  arm 
Ic,  to  the  windlass./,  where  it  amves 
at  its  journey's  end.  It  ia  then  lut 
into  sheets  of  the  size  required  by 
the  paper- cutting  mactiius, 

Pa|«i<aUlD<  UuMnt.  When  Gnisl  sd 
bj  the  machine,  the  pnpcT  is  cut  ofF 
into  long  lengths  and  rolled  by  hand 
for  the  manufaoturerB  of  dran'ing  and 
wall  paper,  scene-paintere,  &e.  At 
tfu^ed  to  a  large  nheel  ia  a  knife 
whose  regular  Etrokes  cut  the  papor 
into  the  size  required.  The  ohpping 
maohioe  is  used  for  outting  the  edges 
of  books. 

y.  Pattehoard  and  other  Paper 
ibuni  PHUboui.    Pasteboard  ismade 
in  three  ways : — 

1.  Byplacing  the  pnlp  inn  form- 
form -board. 

2.  By  pressing  several  damp 
sheets  to  form  a  thick  card — elastic 
pasteboard. 

3.  By  pasting  together  the  fiuished 
paper  sheets — sized  pasteboard. 

t.  Form-board  is  an  inferior  kmd 
employed  for  ordinary  purposes  of 
pacldng.  bookbinding,  &c.  It  is  made 
from  waste  paper,  refaee  rags,  and  the 
coarser  parts  of  the  pulp.  Clay  01 
chalk  is  sometimes  present  to  25  per 
cent  ot  the  weight  of  this  pasteboard 
It  is  made  in  a  coarse  ribbed  form 
goes  through  the  some  process  of 
knotting  as  the  paper  sheet,  and  is 
dried  and  pressed  under  a  roller. 

3.    Elastic  pasteboard  is  of  better 
material    and    presents   a    smoother 
surface  ;  six  to    wel        lieets    f  pap 
previously  damped  are  placed  t  g  th 
and  pressed  into    ue      mpa  t  sh    t 
A  separate  and  hard      kmd    f  pa  te 
board  ia  the  th   k    lost     board  used 
for  binding  books      The  mn      laj 
b  made  ot  coarse   staff  sawdust  il 


CHEMICAL  TECHNOLOar. 


>» 


Blue, 
Yellow ; 


STARCH.  355 

Papier-machS  is  naed  for  fancy  articles,  snch  as  the  covers  for  albums,  inkstands, 
blotting-books,  paper-knives,  Ac,  as  well  as  for  the  cells  of  galvanic  batteries.  It  is 
obtained  from  old  paper  made  into  a  pulp  with  a  solution  of  lime,  and  gum  or  starch, 
pressed  into  the  form  required,  coated  with  linseed-oil,  baked  at  a  high  temperature,  and 
finally  varnished.  The  pulp  is  sometimes  mixed  with  clay,  sand,  chalk,  <ftc.,  and  other 
kinds  are  made  of  a  paste  of  pulp  and  lime,  and  used  for  ornamenting  wood,  inlaying,  <&c. 

ooioond  p»p«r.      The  papers  made  from  coloured  rags  are  the  brown  packing  paper 

and  coarse  coloured  papers,  such  as  sugar  and  pin  paper.     Coloured  pin  paper 

requires  to  50  kilos,  of  dry  pulp  the  several  undermentioned  substances : — 

Yellow  I  ^^5  kilos-  Acetate  of  lead, 

lo'45      »»    Bichromate  of  potash ; 

Igj^g  f2-o5      „     Sulphate  of  iron, 

1 105      „     Ferrocyanide  of  potash ; 

Green  l^oo 

1 1  05 

Violet      1*05      „    Extract  of  logwood ; 

Hose        600      „    Extract  of  Brazil  wood ; 

T>_«.  1 300      »     Oil  of  vitriol, 

^^ I300     „    Cliloride  of  lime. 

Ultramarine  and  aniline  blue  are  also  used  in  colouring  the  paper.  In  variegated 
papers,  chemical,  mineral,  and  vegetable  colourings  are  used  according  to  the 
required  colours.  Body  colours  are  rendered  fluid  by  a  solution  of  gum  arabic  or 
alum  in  the  size,  which  can  be  applied  by  a  brush  or  sponge  when  only  one  side  is 
to  be  coloured.  Variegated  and  tapestry  papers  are  an  important  part  of  the 
manufacture. 

PudmMnt  Paper.  Parchment,  although  made  of  animal  membranes,  is  often  con- 
founded with  vegetable  parchment  (phytopergamet).  The  latter  is  made  of 
unsized  paper  treated  with  sulphuric  acid  or  a  solution  of  chloride  of  zinc : — i  kilo, 
of  concentrated  sulphuric  acid  and  125  grms.  of  water,  in  which  the  paper  is  immersed 
80  as  to  equally  affect  both  sides.  The  length  of  time  differs  according  to  the  quality 
of  the  paper,  the  thicker  or  firmer  paper  taking  a  longer  time  to  saturate  ;  soft  paper 
will  take  five  to  ten  seconds.  It  is  then  placed  in  a  weak  solution  of  sal-ammoniac, 
rinsed  in  water  until  no  trace  of  the  acid  remains,  and  then  dried.  When  these  opera- 
tions are  effected  mechanically,  a  steam  machine  first  pulls  the  endless  paper  throuj^h 
a  vat  of  sulphuric  acid,  then  through  water,  sal-ammoniac,  and  again  water,  tlie 
paper  passing  on  over  cloth  rollers  to  dry,  and  finally  over  polished  rollers  to  press 
and  glaze  the  surface. 

P&rchment  paper,  as  a  rule,  is  of  one  colour ;  when  dipped  into  water  it  is 
rendered  soft  and  limp.  It  is  used  for  documents,  deeds,  records,  &c.,  also  for 
drawing  plans,  charts,  bookbinding,  printing,  and  cards. 

Starch. 

Starch  granules,  one  of  the  vegetable  substances  most  extensive  in  nature,  always 

appearing  organically,  are  the  foundation  which,  chemically  treated,  yield  starch  as 

commercially  known.     Starch  is  found  in  most  organic  combinations  considered  in 

chemistry  and  morphology,    and  in  which  cellulose  is  necessarily  a  component, 

being  closely  allied  to,  if  not  really  isomeric  with,  this  vegetable  substance ;   its 

formuk  is  CeHjoOj.     In  following  its  connections  it  becomes  tlie  starch   that, 

by  means   of  chemical    and  physical   agents,   in  the  preparation  of  starch   gum 

(soluble  starch-dextrine;  and  sugar  forms  one  of  Uie   most  important   substances 

2  A  2 


356  CHEMICAL  TECHNOLOOT. 

presented  to  the  consideration  of  the  technologiat.      It  seldom  appears  in  a  large 
granular  form,  bnt  presents  itself  as  a  white  glistening  powder,  which  upon  m 


ficopic  examination  seems  to  be  made  up  of  va 

centric  to  a  central  spot ;  these  lines  are  more 

extent  in  some  than  in  others,  whilst  the  tnl 

The  granules  from  different  plants  vary  in  sia 

smaller,  whilst  those  from  tropical  products  an 

gives  the  largest  dimension  of  the  grannies  as  o' 

we  gain  also  the  following  examples : — 

Starch  grannlea  tram  cloee  Potatoes 1S5 

„    ordinarj  Potatoes 140 

„    Maranta  tndica 140 

„    Beam 74 

„    Sago  palm jo 

„    loehmd  moBB 67 


rounded  bodies  with  rings  con- 
plainly  indented  and  cover  a  greiter 
erior  of  tlie  grain  appears  hollowed. 
!  and  form ;  those  from  wheat  being 
thicker  and  more  lenticnlar.  Piyea 
MI  millimetre ;  from  his  reseuches 


Pea 


50 


Fig.  206  shows,  according  to  Schleiden,  granules  of  potato  starch,  and  Fig.  207  of 
wheat  starch.  The  potato  has  a  larger  grannie,  and  sometimes  gives  a  finer  ponder 
than  wheat. 

Huua  Di  BURii.  The  usual  starch  contains  in  iia  dry  stat«  nearly  18  per  cent  irat«r. 
and  in  this  state  has  a  tendency  to  form  itself  int^i  globules;  it  has  been  proved  tbit 
exposed  to  a  damp  atmosphere  it  absorbs  33'5  per  cent  water.    Starch  is  insoluble  in 


Fio.  20G. 


0     *»°^°;^'p' 

-  V 


cold  water,  alcohol,  ether,  and  oil.  At  a  temperature  of  160°  starch  yields  dextnof- 
Starch  mixed  with  twelve  to  fifteen  times  the  quantity  of  warm  water  at  a  tempentnn 
of  55°  varies  little  in  substance ;  at  a  temperatore  of  55°  lo  58"  it  begins  to  ehaags, 
the  higher  temperature  making  the  fluid  thicker.  Lippmann  says  that  potato  stareb 
is  aiFected  at  6r5°,  wheat  starch  at  675°.  When  boiled  the  grannies  burst  andfonn* 
gelatinons  mass,  which,  largely  diluted  with  water,  can  be  made  of  a  conaistence  to  b* 
filtered  throngh  paper,  and,  when  allowed  to  cool,  sets  in  a  jelly.  A  stiffer  ftSU. 
according  to  J.  Weisner  (1868)  is  made  from  Indian  com  than  from  the  polslo  v 


STARCH,  357 

wheat.  The  longer  the  starch'is  boiled  the  stififer  the  paste  becomes,  i  part  of  starch 
separating  in  50  parts  water,  and  upon  cooling  setting  into  paste  of  a  blue  or  violet 
hue.  Dry  starch  possesses  a  specific  weight  of  1*53.  Alkalies  and  dilute  acids, 
with  lime,  tend  to  re-form  the  granules ;  when  boiled  with  2  per  miUe  of  oxalic  acid, 
the  starch  loses  its  consistence,  becoming  thin,  and  changing  into  a  soluble  substance 
called  dextrine.  Starch  treated  with  almost  any  dilute  acid,  or  with  diastase 
obtained  from  an  infusion  of  malt,  at  the  proper  temperature  is  converted  into 
dextrine,  forming  a  liquid  which  after  a  few  hours'  standing  can  be  made  into 
sugar.  Starch  is  soluble  in  the  cold  in  concentrated  nitric  acid;  water  dropped 
into  this  solution  precipitates  the  granules  as  an  explosive  combination.  Under 
the  name  of  xylodine,  or  white  gunpowder,  this  combination  has  lately  been 
employed  for  pyrotechnical  experiments.  By  boiling  starch  with  concentrated  nitric 
acid,  a  formation  of  oxalic  acid  is  obtained,  evolving  nitrous  vapours.  Starch  paste 
upon  exposure  to  the  atmosphere  becomes  sour,  forming  lactic  acid. 

sonicaa  of  starch.  But  fcw  Vegetables  yield  starch  in  large  quantities:  the  potato 
yields  20  per  cent ;  wheat  55  to  65  per  cent ;  rice  70  to  73  per  cent ;  and  the  roots  of 
Jatropha  Manihot  and  Maranta  arundinacea^  palm  pith,  and  the  Canna  coocineaj 
similar  quantities.  In  Germany  starch  is  prepared  only  from  potatoes,  rice,  and 
wheat,  the  latter  yielding  a  greater  quantity  of  gum,  and  potato  starch  being  thinner 
and  not  so  gelatinous. 

sufch  tram  Poutoy-      Fotatocs  form  an  important  material  in  the  manufacture  of  starch ; 

their  constitution  is  as  follows : — 

Newly  dug  Potatoes 

Potatoes.         dried  at  loo*^. 

Water 75'i  — 

Albumen 2*3  9*6 

Fatty  matter      0*2  0*8 

Cellulose     0*4  17 

Salts- 1*0  4-1 

Starch 21*0  83*8 

ZOO'O  lOO'O 

They  contain  28  per  cent  dry  substance,  or  23  per  cent  insoluble  substance,  and 
77  per  cent  sap.  The  starch  found  in  potatoes  is  of  cellular  construction ;  the  cell 
walls  require  breaking  up  to  fit  it  for  manufacture.  Fig.  208  shows,  according  to 
Schleiden,  a  fine  specimen  of  a  healthy  potato  under  the  microscope.  On  the  outside 
of  the  potato  a  layer  of  flat,  pressed,  brown  cells  are  found,  sometimes  appearing 
in  a  patch,  a,  forming  the  outer  skin  of  the  potato,  and  covering  the  cells,  &,  which 
sometimes  contain  a  finer  grain,  but  mostly  a  clear  fluid.  These  cells*  become 
wider  as  they  near  the  interior  of  the  potato.  The  series  of  cells,  c^  enclose  the 
inner  cells,  dy  the  pith  of  the  potato.  When  the  potato  is  dried,  the  cells  separate 
from  each  other,  as  in  Fig.  209,  a  specimen  of  a  mealy  potato.  The  starch  granules 
swell  in  each  cell,  the  cells  uniting  in  reticulated  streaks.  The  process  of  manufac- 
turing starch  consists  in : — 

X.  Triturating  the  fresh  potato. 

2.  Washing  the  starch  granules  from  the  pulp. 

3,  Purifying  and  drying  the  starch. 

The  potatoes  are  placed  in  a  grinding  cylinder,  which  form^ly  oonsiBted  of  wood,  with 
iron  plat€L  rollers  placed  hfdf  way  in  water  to  cleanse  the  pulverised  potato  pulp.  Of  late 
grinding  cylinders  with  saw-teeth  are  used  (Thierry's  machine).  The  saw-blades  have 
short  teeth,  lacerating  the  cells  to  obtain  the  starch  granules,  which  mere  gentle 
washing  and  grinding  would  not  effect ;  the  cylinder  revolves  600  to  700  times  a  midnte. 


358 


CHEMICAL  TECHNOLOQT. 


One  cylinder  with  kniveH  050  metre  in  length  and  Baw-bladea  o(  0-40  metre,  cm  piiJ 
ionrteeo  to  flltoen  batchea  in  an  honr  to  a  pulp,  which  is  afterwaida  enbrnitted  to  the 
process  of  waehing.  A  cylindrical  metal  aieve  is  genorsUy  aeei  for  eeparatine  tLe 
Btaroh  granules  from  the  potato  pulp ;  it  oontaina  a  pair  of  bmahea  slowly  relatiii*, 
vhilst  water  m  gnppUed  to  the  sieve  to  wash  the  pulp,  which  is  ground  to  a  oonsUtenc* 
that  will  admit  of  ite  readily  flowing  off,  in  order  that  fresh  pulp  may  be  received  od  tbt 
sievo.  The  Btaroh  graimleB  are  suspended  in  the  water  strained  ofl,  and  finally  settle  to  Uu 
bottom  as  a  soft  white  powder.  Laine'a  nninterraptod  cleansing  sieve  Is  now  gtnertUr 
nsed ;  it  ooueistB  of  a  Beries  of  wire-work  trameB  placed  over  a  trough.  The  pot»to  palj 
Sown  from  the  grinding  cylinder  to  a  space  nnder  the  oleaniaiig  sieve,  from  thence  ow 
two  gratings,  where  the  pulp  is  cleansed  by  a  stream  of  water  playing  all  over  it,  ths 
granules  settling  down  at  the  bottom  of  the  troogh.  The  granules  are  then  ernabcd 
between  steel  rollers  to  separate  the  starch  from  the  fibre.  80  to  100  cwta.  potato**  cm 
be  thus  prepared  in  a  day.  From  the  above  method  of  preparing  starch  from  the  poUto 
we  gain  the  general  principles  of  snch  operations.  The  stinctiire  of  the  potato  ii  sbon 
to  be  partly  chemical,  partly  meohamcal,  and  by  destroying  the  latter  we  gain  starch,  «tud 
is  separated  after  the  potato  pulp  boa  been  atanding  eight  days,  when  it  beoomet  a  wbiH 

Fio.  108. 


pasty  mass  containing  starch.  This  is  placed  in  a  coarse  sieve,  which  retains  a  gntUi 
part  of  the  fibre,  another  finer  hair  sieve  being  used  to  receive  the  starch  and  flnK 
fibre,  separated  from  each  other  by  means  of  a  cleansing;  apparatna,  which  mabei  tiM 
fibre  away,  leaving  the  starch  granoles  and  sugar  behind, 

ditUx  a<,  potu  BUnh.  The  result  of  the  washing  ia  a  milk-like  fluid,  which  setlln  at 
the  bottom  of  the  trough  as  starch  ;  it  is  then  mixed  with  fresh  water  and  allowed  to 
solidify  into  a  hard  substance,  which  is  cut  into  pieces,  poured  upon  a  linen  cloth  ptattd 
on  ahurdle,  with  a  plaster-of-Faria  vessel,  or  a  vessel  containing  gypsum,  ondemeath,  to 
dry  the  starch.  After  being  watered  and  left  to  stand  for  twenty-four  houn.  tltf 
starch  dries  to  the  thickneaa  of  3  decimetres  Dpon  the  gypsum.  Of  late  the  water  fau 
been  removed  by  a  centrifugal  machine.  The  moiat  starch  contains  33  per  oent  wata 
and  is  called  fresh  starch.  The  average  temperatoie  of  the  drying  rooms  ia  not  over  6o'- 
When  the  starch  is  dried  it  is  broken  into  pieces  by  iioD  rollers.  The  stalk  or  wbol* 
Btarch  is  made  by  boiling  to  a  thick  paate,  which  is  forced  by  maahiner?  through  a  nMU 
opening  into  a  trough,  where  it  dries  in  a  kind  of  mould. 

pnpu>uni(rt  wbHi  Biueii.  According  to  M.  O.  Dempnolf,  i86g,  the  anprepared  vbeit 
contaiuB: — 

Water lo-ji 

Gum        Has 

Starch 65-^ 

Fatly  and  woody  fibre         S-i4 


STARCH.  •  359 


From  the  constituent  parts  of  wheat  it  is  seen  that : — 

are  insoluble  in  water. 


Starch 

Gum 

Husk 


Salts 

Albumen 

Dextrine 


are  soluble. 


The  first  three  are  insoluble.,  the  gum,  however,  being  gradually  dissolved  by  the 
lactic  acid  developed  from  the  seed,  while  the  starch  and  husk  remain  unattacked. 
The  different  modes  of  preparing  wheat  starch  are,  namely : — 

A.  By  fermentation  (old  method)  of  the — 

B.  New  mode  of  treatment  without  fermentation. 

The  old  method  consists  of  the  following  operations : — 

1.  Fermenting  the  wheat. 

2.  Washing  the  starch  from  the  mass. 

3.  Washing  and  cleansing  the  starch. 

4.  Drying  the  starch. 

The  whole  wheat  is  soaked  in  water  until  soft.  The  seed  is  separated  from 
the  husk  either  by  treading  in  sacks  in  a  flat  tub  of  water,  or  by  being  placed  under 
rollers,  and  the  pulp  thinned  with  water  to  a  milky  fluid,  in  which  a  greater  part  of 
the  starch  and  gum  are  found.  After  standing  a  day  this  fluid  turns  acid ;  a  part 
of  the  gum  becomes  diluted  by  the  action  of  the  lactic  and  acetic  acids,  and  is  taken 
away  and  replaced  by  fresh  water,  the  same  process  being  gone  through  imtil 
the  fermentation  ceases,  when  the  starch  is  washed  with  water  and  dried.  In  the 
fermentating  tub  it  forms  with  the  water  a  thin,  sour  pulp.  The  time  varies 
according  to  the  temperature ;  all  the  gum  is  not  separated  until  about  twelve  to 
thirty  days.  The  sour  water  contains  acetic  acid,  lactic  acid,  butyric  acid,  succinic  acid, 
ammoniacal  salts,  and  the  mineral  constituents  of  the  wheat.  The  mass'is  then  placed 
in  a  sack  and  trodden,  the  milky  fluid  being  allowed  to  escape,  leaving  the  husk  and 
refuse  gum  behind.  The  milky  fluid  containing  starch  is  strained  tlirough  a  fme 
hair  sieve  and  washed  with  water.  Another  metliod  is  that  of  placing  the  milky 
fluid  in  a  tub  and  allowing  it  to  settle.  The  first  layer  of  tlie  sediment  is  fine 
starch,  next  a  mixture  of  starch,  husk,  and  gum,  the  last  layer  containing  but  little 
starch.  In  the  preparation  a  little  ultramarine  blue  is  added  during  the  cleansing 
process.  Of  late  the  centrifugal  machine  has  been  used  for  the  purpose  of  drying 
the  starch. 

Preparing  wheat  starch  without  fermenting : — 

According  to  E.  Martin's  treatment,  wheat  flour  is  mixed  with  wat^r  to  a  paste, 
100  parts  flour  to  40  parts  water ;  the  paste  remains  i  to  2  hours  to  affect  the  gum, 
and  is  then  washed  in  a  fine  wire  sieve  placed  over  a  tub.  The  starch  is  found  at  tlie 
bottom  of  the  tub  mixed  with  water,  and  is  placed  in  a  warm  spot  to  ferment 
slightly.  It  is  dried  in  a  mass,  and  goes  through  similar  processes  to  tlie  other 
starch,  being  made  into  stalk  and  powder  starch,  and  sold  in  packets. 

100  parts  of  wheat  flour  yield  25  per  cent  of  gum  [gluten,  gluten  granule),  witli 
33  per  cent  of  water ;  the  fresh  gluten  is  mixed  with  a  double  weight  of  flour,  the  paste 


36o  .  CHEMICAL  TECHNOLOGY. 

rolled  into  long  strips,  and  ground  into  granules,  which  become  dry  at  30  to  40^  and 

are  afterwards  sifted.    The  consumption  of  this  granular  gum  is  extensiYe,  it  being 

employed  for  food   (with  ordinary  flour  as  macaroni),  art  purposes,  and  mann- 

facture. 

^SmSSSu^stiSS!  ^      According  to  M.  J.  Wolff,  the  constituents  of  commercial  staith 

are  as  follows : — 

I.  2.  3.  4.  5.  6. 

Water    ..  17-83  15*38  14-52  17*44  14*20  17*49 

Gum     ..               —                —  o*io  traces  1*84  4*96 

Fibre     ..              0*48             0-50  1*44  1-20  377  2*47 

Ash       . .              o*2i  o*53  0*03  0-40  o*55  i-ig 

Starch  ,.  81*48  83-59  83*91  81*32  79*63  73*79 

100*00  100*00  100*00  loo'oo  100*00        100*00 

I.  The  finest  white  patent  starch  in  stalks,  of  a  bright  and  cryst^dline  appearance, 
made  from  pure  potato  starch.  2.  The  finest  blue  patent  starch,  potato  starch 
coloured  with  ultramarine.  3.  Pure  wheat  powder.  4.  Fine  wheat  starch  in  pieces. 
5.  Medium  fine  wheat  starch  in  yello\visli-white  pieces.  6.  Ordinary  wheat  starch 
in-  greyish-yellow  coarse  pieces,  tliat  upon  microscopic  examination  appear  as  a  mix- 
ture of  potato  and  wheat  starch.  Starch  is  used  for  stiffening  domestic  articles  in 
washing,  for  stiffening  paper,  and  extensively  in  linen  and  cotton  manufacture, 
in  gum,  syrups,  sago,  vermicelli,  &c.  It  is  also  a  basis  from  which  we  can  obtain 
sugar.  Potato  starch  is  preferred  for  domestic  washing,  but  where  great  stifhess  is 
requisite,  wheat  starch  is  used,  as  in  bookbinding,  &c.  In  wheat  starch,  the  paste  is 
formed  of  closely  united  gelatinous  particles,  which  are  more  widely  disseminated  in 
potato  starch,  the  latter  being  transparent  and  more  suitable  for  stiffening  fine  linen, 
ironing  smoother,  and  not  sticking.  Wlieat  starch  will  keep  fresh  upon  exposure  to 
the  atmosphere  longer  than  potato  starch,  the  latter  turning  sour  after  a  day's 
standing. 

According  to  G.  Wiesner,  1868,  maize  starch  possesses  the  highest,  wheat  the  neit, 
and  potato  starch  the  most  inferior  stiffening  qualities.  Maize  and  wheat  are  consi- 
dered the  best  for  forming  a  smooth  equal  paste.  Sugar  can  be  prepared  from 
starch  by  means  of  the  active  principle  of  malt — diastase.  From  this  sugar,  again, 
brandy  and  spirits  can  be  distilled.  According  to  the  researches  of  Liidersdorff  :— 
100  pounds  of  potato  starch  need  25*5  pounds  of  dry  malt,  and 
100  poimds  of  wheat  starch     „    905        „  „ 

to  effect  the  full  conversion  of  the  starch  into  sugar. 

£!!5h.*^"8aS'8uSS.  ^^®®  starch  is  largely  manufactured  in  England,  France,  and  Bel- 
Arrow-Root.  '  gium.  To  extract  the  gum,  rice  is  placed  in  a  bath  of  weak  soda 
solution — 287  grms.  of  caustic  soda  to  the  hectolitre.  After  standing  twenty-fonr  homji 
the  rice  grain  becomes  softened,  and  is  then  washed,  ground  between  rollers  or  rm- 
stones,  and  placed  on  a  sieve  with  brushes  to  retain  the  husk  or  bran.  The  wat^ 
strained  off  contains  the  starch,  which  is  washed,  dried,  and  manufactured  into  the  fonn 
required.  The  gum-oontaioing  alkaline  ley  being  neutralised  with  sulphuric  acid  ia  fit  ^^ 
inferior  uses.  J.  and  J.  Colman's  rice  starch  manufacture  employs  1000  workpeople,  ma 
the  result  of  their  manipulation  is  used  as  the  customary  washing  starch,  the  stiffer  and 
brighter  starch  for  ball  dresses,  window  hangings,  and  for  the  size  in  paper  mannfaetar^* 

£1  France  the  chestnut  is  used  for  the  manufacture  of  starch.  Chestnuts prodneea 
starch  possessing  the  evenness  of  potato  starch  with  the  stiffness  of  wheat  starch' 
100  parts  of  the  fresh  bitter  chestnut  give  19  to  20  per  cent  dry  starch. 

Anow-root  is  obtained  from  the  Maranta  arundinaceay  and  M.  tTuiica,  cultivated  in  tha 
West  Indies ;  it  is  very  Uke  potato  starch,  and  is  prepared  in  a  similar  manner.  Casaa^ 
starch  is  made  from  the  root  of  Jatropha  Manifwtt  or  Manihot  utilUnma,  and  M.  Aipi^ 
largely  cultivated  in  South  America,  the  West  Indies,  and  the  Brazils. 


STARCH.  361 

Cassava  is  used  as  an  article  of  consumption  both  in  Europe  and  the  tropics.  The 
root  of  the  maniocis  thoroughly  purified  from  its  poisonous  juice,  being  coarsely 
ground  to  allow  the  sap  to  escape,  and  roasted  in  an  earthenware  vessel, 
the  cassava  forming  into  granules  on  the  sides  of  the  vessel  [Cassava  sagOy  or 
Manioka),  the  prussic  acid  contained  in  the  root  becoming  volatilised.  I^om  arrow- 
root and  the  analogous  roots  containing  a  poisonous  juice,  arrow-root  derives  its 
name,  having  been  used  by  the  Indians  as  a  poison  for  the  tips  of  their  arrows.  Its 
components,  according  to  Benzon,  in  100  parts,  are — ^Volatile  oil,  0*07  parts ;  starch, 
26  parts ;  89  per  cent  of  the  starch  being  obtained  in  a  powder,  while  the  remainder 
is  extracted  from  the  parenchyma  by  boiling  water;  albumen,  i'58  parts;  gum,  06 
part ;  chloride  of  calcium,  025 ;  insoluble  fibrin,  6  parts ;  and  water,  65*5  parts. 
It  is  known  in  conmierce  in  several  varieties,  viz. : — Portland  arrow-root.  Arum 
vtdgare;  East  India  arrow-root.  Curcuma  augustifolia ;  Brazillian  arrow-root, 
Jatropha  Manihot ;  English  arrow-root,  from  the  starch  of  the  potato ;  Tahiti  arrow- 
root, Taeca  oceanica. 

smo.  Sago  is  made  from  the  soft  central  portion  of  the  stem  of  the  palm,  Bogus 
Rumphii.  According  to  J.  Wiesner,  the  Guadeloupe  sago  is  prepared  from  Eaphia 
farini/era,  and  an  East  Indian  variety  from  Caryota  urens.  The  stem  is  torn  to  fila- 
ments and  elutriated  on  a  sieve  with  water.  The  starch  obtained  is  then  washed, 
dried,  and  sifted  into  a  copper  plate,  where  it  remains  a  hard  granular  substance.  A 
greater  part  of  the  common  sago  is  manufactured  frt)m  potato  starch,  coloured  with 
oxide  of  iron  or  burnt  sugar. 

Dextrin*.  Dcxtriue,  gommeline,  moist  gum,  starch  gum,  or  Alsace  gum,  isomeric 
with  gum  arable,  and  expressed  by  the  formula,  C6H10O5,  is  formed  by  boiling 
starch  with  a  small  quantity  of  almost  any  dilute  acid,  which  thins  its  consistence, 
and  converts  it  into  a  soluble  substance  similar  to  gum  arable.  It  is  soluble  in  cold 
water,  insoluble  in  absolute  alcohol,  but  slightly  soluble  in  weak  spirits  of  wine. 
Dextrine  derives  its  name  from  dexter j  the  right,  from  the  action  of  this  substance  on 
polarised  light,  twisting  the  plane  of  polarisation  towards  the  right  hand.  Dextrine 
in  grape  sugar  is  converted  into  dextrose  by  the  action  of  dilute  acids.  Dextrine 
solution  does  not  ferment  with  yeast ;  but  a  little  yeast  mixed  with  a  large  quantity 
of  gelatinous  starch,  at  a  temperature  of  I6o^  quickly  liquefies  it,  dextrine  being  pro- 
duced, the  greater  part  of  which,  if  allowed  to  stand,  becomes  converted  into  grape 
sngar.  From  this  decomposed  dextrine  a  cheap  and  largely  employed  substitute  for 
gum  arable  is  obtained.  The  components  of  this  decomposed  dextrine,  according  to 
the  analyses  of  E.  Forster  (1868)  are : — 

I.  2.  3-  4'  5-  6. 

Dextrine.    2?*^^®      J^^f^     Gommelme.^  ^if         S?^^* 
Starch.      Deztrme.  ^""**"~*"^*  Dextrine.    Starch. 

Dextrine 72*45  70*43  63*60  59*71  49*78  5*34 

Sugar      877  1*92  7*67  576  1-42  0*24 

Insoluble  substances  13*14  i9'97  i4'5o  20*64  3080  86*47 

Water     5-64  7*68  14*23  13*89  i8*oo  7-95 

loooo      100*00       loo'oo        loo'oo        loo'oo      100*00 

Potato  starch  is  preferable  to  wheat  starch  for  the  manu£EM!tare  of  this  material, 
not  only  on  account  of  its  cheapness,  but  for  its  greater  purity  at  an  equivalent 
price. 


362  CHEMICAL  TECHNOLOGY. 

Dextrine  is  prepared  by  : — 

a.  Gently  roasting. 

b.  Carefully  treating  with  nitric  acid. 
e.  Boiling  with  dilute  sulphuric  acid. 

d.  Treating  with  malt  extract  (diastase). 

Preparing  dextrine  by  means  of  gentle  heat  is  an  easy  operation.  The  starch 
is  roasted  until  it  becomes  brown-yellow  in  colour,  in  a  large  copper  or  iron 
plate  cylinder,  similar  to  a  coffee  drum,  situated  on  one  side  of  the  oven.  Dextrine 
is  formed  at  a  temperature  of  225  to  260°.  According  to  Heuz6,  the  following  is  a 
better  method : — 2  kilos,  of  nitric  acid,  of  i'4  specific  weight,  with  300  litres  of  water, 
are  mixed  with  1000  kilos.  ( =  20  cwts.)  of  starch,  and  boiled  to  form  a  mass,  which, 
when  exposed  to  tlie  air,  becomes  dry.  It  is  sometimes  affected  at  8o%  but  it 
becomes  a  paste  at  100°  to  110°.  The  starch  changes  into  dextrine  in  an  hour  or  an 
hour  and  a  half  at  the  most ;  it  is  white  and  soluble  in  water.  Sulphuric,  hydro- 
chloric, and  lactic  acids  will  produce  dextrine;  and  by  the  addition  of  water  to  dex- 
trine, dextrine  syrup,  or  gum  syrup,  is  obtained. 

Dr.  Yogel  gives  a  simple  experiment  to  ILlastrate  the  action  of  dilute  sulphuric  add 
upon  starch.  Nearly  all  kinds  of  writing  paper  are  so  very  largely  sized  with  starch,  thai 
if  figures  or  letters  are  traced  on  the  paper  with  veiy  dilute  sulphuric  acid,  and  Uien  dried, 
the  application  of  iodine  in  a  dilute  solution  will  impart  a  blue  tinge  to  that  portion  of 
the  paper  not  affected  by  the  acid,  the  characters  remaining  white. 

Dextrine  is  extensively  used  instead  of  gum  arabic  in  printing  wall  papers,  for 
stiffening  and  glazing  cards  and  paper,  for  lip  glue,  surgical  purposes,  wines,  and  in 
the  fine  arts  it  is  applied  in  many  ways. 

SuGAB  Manufacture. 

HWosy  of  sogar.  SugBT  has  been  known  in  the  East  Indies  and  China  since  a  veiy 
remote  period.  In  Europe  honey  was  used  for  sweetening  purposes  in  the  olden 
time,  and  although  sugar  was  known  to  the  inhabitants  of  Greece  and  Italy,  the 
commercial  intercourse  with  India  being  limited,  it  was  but  little  used  until  the  time 
of  Alexander  the  Great.  After  the  conquest  of  Arabia  sugar-canes  were  propagated 
in  Western  Asia,  Africa,  and  Southern  Europe.  The  Crusaders  became  acquainted 
with  this  useful  product,  and  the  Venetians  began  to  cultivate  it  about  that  time  in 
Europe  and  Northern  Africa.  Malta,  Cyprus,  Candia,  and  Egypt,  yielded  the  first 
sugar-cane,  which  was  next  cultivated  in  Sicily,  Spain,  Portugal,  and  the  Ganaiy 
Islands,  about  1420.  In  1506,  sugar  was  cultivated  iu  the  West  Indies,  Brazil, 
Haiti,  and  in  many  islands  of  the  Indian  Ocean.  Cane  sugar,  a  substance  found  in 
the  juice  of  various  grasses,  was  first  discovered  iu  South  America.  Bitter  mentionB 
it  as  a  plant  capable  of  great  cultivation,  to  be  found  in  different  parts  of  the  globe— 
eastwards  from  Bengal  to  China ;  westwards,  the  Indies,  Nortii  Africa,  Southern 
.  Europe  to  America.  Slaves  were  imported  to  cultivate  the  sugar-canes  in  North 
America  in  1800,  when  the  first  cultivation  commenced,  and  sugar,  which  until  now 
had  been  a  curiosity  and  a  luxury,  being  chiefly  used  for  medicinal  purposes,  became 
one  of  the  daily  necessaries  of  life.  The  art  of  extracting  sugar  from  the  canes  and 
refjiing  the  raw  product  soon  became  known,  and  this  useful  article  of  food  was 
extensively  manufactured. 

Mfttnn  of  socv.      Sugar  is  known  as  cane  sugar  and  grape  sugar,  dextrose,  glucose, 
crumbling  sugar,  starch  sugar,  potato  sugar,  and  coarse  raw  sugar  or  fruit  sugar. 


SUGAR. 


3C3 


Cane  sugar  is  prepared  from  the  sugar-cane,  maize,  the  Andropogon  glycichylum,  the 
sap  of  the  sugar  maple,  the  birch,  the  sweet  turnip,  and  carrot.  According  to 
W.  Stein,  8  per  cent  of  sugar  is  found  in  the  root  of  the  madder.  The  pumpkin,  melon, 
banana,  and  most  of  the  species  of  palms  yield  sugar.  Cane  sugar  has  the  formula 
CX2H22O11.  The  crystallised  sugar,  known  as  sugar-candy  is  hdrd  and  has  a 
Bp.  gr.  of  i'6 ;  it  is  unaffected  by  exposure  to  the  air,  and  when  heated  at  a  tempera- 
ture of  180°  it  dissolves  into  a  sticky  colourless  fluid,  which  upon  rapid  boiling 
resolves  itself  into  a  pliant  uncrystallised  mass,  commonly  known  as  barley-sugar. 
At  a  very  high  temperature  it  becomes  black  and  decomposed.  At  210°  to  220*^  cane 
sugar  becomes  a  dark  brown  substance  termed  caramel,  used  in  colouring  spirits  and 
for  other  purposes.  Sugar  has  a  pure  sweet  taste,  is  soluble  in  one-third  of  its  weight 
of  cold  water ;  by  continued  boiling  it  loses  its  power  of  crystallising.  It  is  insoluble 
in  absolute  alcohol  and  ether,  but  soluble  in  dilute  alcohol,  especially  when  warmed. 
Gerlach,  1864,  gives  in  the  following  table  the  specific  weight  of  sugar  solutions 
with  the  corresponding  percentage  of  cane  sugar  at  17*5°  C. : — 


Percentage 

Spedfio 

Percentage 

Specific 

Percentage 

Specific 

Cane  Sugar. 

weight  Sol. 

Cane  Sugar. 

weight  Sol. 

Oane  Sugar. 

weight  Sol 

75 

1383342 

49 

1*227241 

24 

1-101377 

74 

1-376822 

48 

1-221771 

23 

1*096792 

73 

1*370345 

47 

1*216339 

22 

1-092240 

72 

1-363910 

46 

I-2I0945 

21 

I  08772 1 

71 

1-357518 

45 

1-205589 

20 

1*083234 

70 

1-351168 

44 

1*200269 

19 

1*078779 

69 

1-344860 

43 

1*194986 

18 

1074356 

68 

1338594 

42 

1-189740 

17 

1*069965 

67 

1-332370 

41 

1*184531 

16 

1*065606 

66 

1*326188 

40 

1-179358 

15 

1*06x278 

65 

1-320046 

39 

1*174221 

14 

1*056982 

64 

1-313946 

38 

1*169121 

13 

I  052716 

63 

•  r 307887 

37 

1*164056 

12 

I  048482 

62 

1-301868 

36 

1-159026 

II 

1*044278 

61 

1-295890 

35 

1154032 

10 

I  040104 

60 

1289952 

34 

1*149073 

9 

1035961 

59 

1-284054 

33 

1144150 

8 

1*031848 

58 

1*278197 

32 

I-I3926I 

7 

1*027764 

57 

1-272379 

31 

1-134406 

6 

I  0237 10 

56 

1*266600 

30 

1*129586 

5 

1019686 

55 

1-260861 

29 

1*124800 

4 

1015691 

54 

1-255161 

28 

1*120048 

3 

1011725 

53 

1-249500 

27 

i'"5330 

2 

1007788 

52 

1-243877 

26 

1*110646 

I 

1*003880 

51 

1*238293 

25 

1*105995 

0 

1*000000 

50 

1*232748 

A  watery  solution  turns  the  rays  of  polarised  light  to  the  right  hand.  Dilute 
sulphuric  and  muriatic  acids,  with  most  of  the  organic  and  mineral  acids,  tend  to 
convert  cane  sugar  solutions  into  a  mixture  of  dextrose  and  levulose  according  to 
the  equation : — 

C„H„Oii+HaO=C6Hia06+C6Hia06. 


Cane  sugar  or 
sucrose. 


Dextrose     Levulose. 
(glucose). 

From  the  above  it  may  be  deduced  that  cane  sugar  is  found  only  in  the  neutral 
juices  of  plants,  while  juices  like  that  of  the  grape  containing  free  acid,  tartaric, 


364  CHEMICAL  TECHNOLOGY. 

malio,  and  citric  acids,  can  yield  only  levolose  and  glucose.  By  treating  with  yeasi 
the  sogar  separates  and  produces  the  usual  alcoholic  fermentation  producta, 
alcohol,  carbonic  acid,  glycerine,  &c.  Cane  sugar  enters  into  combination  with 
the  hydroxides  of  calcium  and  barium,  forming  sacoharates,  which  in  the  preparation 
of  sugar  on  the  large  scale  are  of  great  interest.  The  sugar  solution  containing 
hydroxide  of  calcium  becomes  especially  interesting  as  being  the  origin  of  the  appli- 
cation of  lime  to  the  refining  of  cane  and  beet-root  sugars,  the  hydroxide  of  caldum 
forming  a  clear  fluid  with  a  raw  sugar  solution  containing  CiaJitaOn,  becoming  doll 
upon  standing,  the  sediment  containing  Gi^HsaOix.GaO.  Carbonic  acid  gas  has  of 
late  been  applied  to  the  sugar-lime  solution,  the  lime  thrown  down  as  carbonate  and 
the  sugar  separating  and  becoming  colourless  in  the  solution.  Preparing  cane 
sugars  with  hydroxides  of  barium  gives  rise  to  sugar  barytes,  CxsH^OnBaO,  worthy 
of  notice  as  being  insoluble  in  water  and  originating  the  method  of  extracting  sugar 
from  the  juice  of  beet-root  and  molasses  with  caustic  baryta.  Sugar  barytes  is 
decomposed  by  means  of  carbonic  acid.  An  explosive  mixture  is  formed  with  nitric 
and  concentrated  sulphuric  £tcids  and  sugar,  and  known  as  nitro-sugar.  Cane  sugar 
when  mixed  with  a  solution  of  sulphate  of  copper  with  an  excess  of  caustic  potash, 
is  at  first  but  slightly  afiected ;  a  small  quantity  of  red  powder  is  thrown  down 
after  a  time ;  but  the  liquid  long  retains  its  blue  tinge,  while  with  grape  sugar  the 
eflfects  are  much  increased. 


Cane  Sugar. 

w 

'fiSgiScSi?*  The  sugar-cane,  Saccharum  officinaruniy  is  a  plant  of  the  grass  species ; 
its  stalk  is  round,  knotted,  and  hollow,  and  the  exterior  of  a  greenish-yellow  or  blue, 
with  sometimes  violet  streaks.  It  grows  from  26  to  6*6  metres  high,  and  from  4  to  6 
centimetres  in  thickness ;  the  interior  is  cellular.  The  leaves  grow  to  a  length  of 
1*6  to  2  metres,  and  are  ribbed.  The  plant  is  grown  from  seed,  and  also  cultivated 
from  cuttings. 
A  hectare  of  land  yields  raw  sugar : — 

By  15  Months*  Ctdtivation.  In  i  Tear. 

From  Martinique 2500  kilos.  2000  kilos. 

„     Guadeloupe' 3000    „  2400      „ 

„     Mauritius     5000    „  4000 

„     Brazil    75^^    »  6000 

oomiKmentaofthe      The  BUgaT-oane  yields  the  largest  amount  of  sugar,  generally  90  per 


»» 


Sngai^cuM.  cent  juice,  containing,  according  to  Pdligot,  i8  to  20  parts  ciystalliMd 
sugar.  The  components  of  sugar-cane,  according  to  the  analyses  of  P^ligot,  Dnpny,  and 
loery,  are  as  follows : — Martinique  (a);  Guadeloupe  {b) ;  Mauritius  (c). 

(a.)                    (6.)  (c.) 

F^ligot.  Dupuy.  leery. 

Sugar     ..     ..       i8'o                 17*8  20*0 

Water    ..     ..       72*1                 72*0  6g-o 

Cellulose       ..        9*9                  9*8  10*0 

Salts      ..     ..       —                   o*4  o'7 — 1*2 

From  x8  per  cent  sugar  found  in  the  sugar-cane,  as  a  rule  not  more  than  8  per  cent 
orvstallised  sugar  can  be  realised.  The  loss  may  be  accounted  for  thus : — 90  per  cent 
juice  is  expressed  from  the  cane,  from  which  only  about  50  to  60  per  cent  can  be  clarified 
from  the  straw,  &o. ;  a  fifth  part  is  exhausted  by  refining ;  and  finally  two-thirds  of  ths 
sugar  is  obtained  by  boiling,  while  the  rest  goes  to  the  molasses.  The  z8  per  cent  sngar 
may  be  realised  in  the  following  manner : — 


SVQiB.  365 

In  the  refiue  sometimeB  lemaine     . .     6     per  cent. 

Ttj  altimtning         3-5  „ 

In  the  molasaea 3  „ 

Ae  taw  ingBi        6'5        „ 

18 

'^S'S'bJw  J^m'"  ■  ^^  preparation  of  raw  sugar  from  the  sugar-cane  consiatB  m 
first  eipreEsing,  and  then  cteanaing  and  boiling  tlie  juice. 

I.  Expreiting  the  Juice. — The  Bug&r-canes  are  crushed  in  B  presa  consieting  of 
three  hoUow  cast-iron  rollers,  aba,  I'ig.  210,  placed  horizontally  in  a  cast-iroa 
frame.  By  meanaof  the  acrewa,  i  i.thenpproximatedistance  of  the  rollers  is  adjusted. 
One  roller  ia  half  as  lai^e  as  the  others,  and  ia  moved  by  three  cogged  wheels 

Fw.  110. 


filled  on  to  the  axis  of  the  rollers.  The  augar-canes  are  transferred  from  the  alata 
gutter,  dd,  to  the  roUera,  a  e,  which  press  them  a  little,  and  from  thence  thej  are 
curied  over  the  arched  plat«,  n,  to  the  rollers,  c  b.  The  pressed  sugar-canes  fell 
over  the  gutter.  /,  the  expressed  juice  collecting  in  g  g,  and  ranning  off  through  h. 
The  middle  roller  is  tanned  the  king  roller ;  the  Hide  cylinders  are  individually  the 
nde  roller  and  macosse. 

2.  Itejining  and  Boiling  tk«  Juice. — The  expressed  juice  ia  removed  to  the  boiling- 
honse,  which  is  fitted  with  five  iron  or  copper  veaaela.  To  15,000  litres  of  expreased 
jnice  5  Ui  g  litres  of  millt  of  Ume  are  added.  The  lime  neutrahses  the  maUc  and 
other  vegetable  acids,  and  upon  boiling  forms  with  the  albumen  and  the  other  con- 
Blitaents  of  the  juice  a  thick  green  scum,  which  being  removed  the  Juice  is  allowed 
to  remain  in  two  of  the  pans  lo  evaporate.  A  freah  scum  is  formed  on  the  first  pan, 
which  returns  after  a  second  or  third  time  of  removal.  The  Juice  as  it  issuee  from 
the  press  is  received  into  the  first  pan,  in  which  hy  alow  boiling  it  becomes  a  thick 
froth,  changing  by  rapid  boiling  to  a  clear  colourless  fluid ;  in  the  third  and  fotulh 
pans  the  liquid  becomes  gradually  purer;  until  in  the  fifth  it  cryatallises.  The  finger 
IS  dipped  into  the  boiled  juice  to  test  its  consistence,  and  by  the  length  of  the 
pendant  drop,  which  ought  to  be  about  3  centimetres,  the  thiclmess  is  ascertained. 
The  boiled  Jnice  is  placed  in  a  large  open  wooden  vessel  of  about  16  centimetres 
capacity,  and  termed  the  cooler,  where  after  standing  twenty-four  hours  the  sugar 


^n  com 


366  CHEMICAL   TECHNOLOGY. 

crystallises,  the  cooler  being  provided  with  a  double  r^^'^ji^'treatiiiff  with  veut 
molasses  to  escapejeaving  the  crystals  behind.    A..     ^^^    fermentation   produd|^ 
molasses  dries  into  a  mass  commonly  known  as  mbi      ,  ^^  comhi)*'^*^^^'" 
The  molasses  passes  into  a  cistern  placed  underneath   '  -^:  .•  icITcc^able  of j^ 
taining  15,000  to  20,000  litres  of  juice,  and  after  standing  fourtetsn  da^ 
the  market.    In  the  French  and  English  colonies  sugar  is  exporte**  jT^f 
with  fire-clay  under  the  name  of  chest  or  tub  sugar. 
vaitetiMof  Sugar.      European  oommerce  deals  with  the  following  kinds  of  raw  sugar: — 

1.  West  Indian — Cuba,  San  Domingo  or  Haiti,  Jamaica,  Porto-Bioo,  Martinique, 
Guadeloupe,  Saint  Croix,  St.  Thomas,  Havanna. 

2.  American — Rio  Janeiro,  Bahia,  Surinam,  Pemambuca. 

3.  East  Indian — Java,  Manilla,  Bengal,  Mauritius,  Bourbon,  Cochin  Chioa,  8L 
Canton. 

Of  late  there  has  been  a  distinction  between  sugar  cultivated  by  slave  and  that  by  fne 
labour ;  the  latter  comes  from  Jamaica,  Barbadoes,  Demerara,  Antigua,  Trinidad,  Dominica; 
the  former  h-om  Cuba,  Havanna,  Brazil,  St.  Croix,  and  Porto  Bico. 

The  mode  of  manufacture  varies  according  to  the  nature  of  the  foreign  substances 

that  always  form  part  of  the  constituents  of  sugar,  such  as  water,  fibre,  gluten,  sand 

or  earth,  soluble  mineral  salts,  acetic  and  other  acids,  all  of  which  must  be  destroyed 

before  the  sugar  can  be  refined.    According  to  Renner  we  have  in  the  following 

sugars  from : — 

Raw  Sugar  

Slime  Sugar 

w  aier      •••  •«•     ••• 

Asn  ...     ...  •••     ••• 

table  acids,  Ac.      }      3'5— 0-5         4-5— 04 

MobMM.  The  production  of  molasses  is  due  to  the  long-continued  heating  of  the 
cane  juice,  but  the  quality  varies  according  to  the  nature  and  culture  of  the  sugar- 
canes,  the  heat  of  the  season,  &c.  By  chemical  treatment  molasses  appears  as  a 
concentrated  watery  solution  of  crystallised  sugar,  slime  sugar,  with  a  small 
admixture  of  caramel  and  mineral  salts.  It  is  a  duU  red-brown  sweet  fluid  ased 
principally  in  the  colonies  for  the  manufacture  of  rum ;  it  is  soon  converted  to 
spirit,  and  then  quickly  becomes  acetated.  Renner  gives  the  constituents  of 
molasses  as : — 


Java. 

Havanna. 

Surinam. 

In  Sugar- 
Candy. 

InBahn. 

98-6— 83-1 

97-0— 87-3 

92'3-^5*4 

996 

997 

5*5—  03 

37—  09 

4-4--  1-6 

01 

02 

61—  03 

3*5—  09 

63—  3*6 

02 

01 

2*1 —  0*2 

1-4 —  00 

2'0 —   I'2 

O'l 

— 

Caramel, gum,  vege-,      ,.^_  „.^  ^.^__  ^.^  ^.^_  ^.^ 


Raw  sugar 

•*•     ••• 

3297 

4036 

Slime  sugar 

..•     .•• 

430 

738 

Water 

.••     ..• 

1371 

i6'25 

•..     •*• 

335 

378 

Caramel,  gum, 
0 /• 

&c.  ••• 

• 

• 

4565 

32-22 

Eeflning  the  Sngar.  Sugar  refining  consists  in : — 
I.  Dissolving  and  refining.  The  raw  sugar  is  dissolved  in  water,  and  during  the 
process  of  evaporation  the  apparatus  is  connected  by  a  gutter  to  a  reservoir,  into 
which  the  sugar  flows.  It  is  then  submitted  to  a  straining  apparatus,  which  retains 
the  several  impurities.  The  refined  fluid  is  then  heated  in  a  copper  pan,  termed  the 
melting-pan,  the  water  adding  30  per  cent  to  the  weight  of  the  sugar,  and  is  after- 
wards placed  in  the  refining  pan,  a  vessel  constructed  with  a  double  bottom.  For 
the  purpose  of  clearing,  a  mixture  of  albumen  is  added  in  the  shape  of  serum  of 


SUGAR.  367 

in  uiZ'x??*^  l,ime-w%ter  and  sulphuric  acid,  an  addition  afterwards 
By  skiimning      >  -^^f^  charcoal  and  i  to  2  per  cent  blood,  and  the 

In  the  molao«  point.    The  albumen  coagulates  and  forms  a  fibrous 

n^«„»    ---'■-        As  raw  su  .,. 

"cum,  cont^Ufc.^  purities. 

^  *^>*';3  filteiing  apparatus  is  now  much  used  for  filtering  the  sugar,  charcoal 

«>^'-S'%X??J4.  *^9  ^^  Piirifying  agent. 

3.  The  vnff  ^^  of  the  clear  sugar  in  pans  placed  over  a  vacuum  apparatus, 
resembles  the  previous  boiling,  with  the  exception  that  the  fluid  is  rendered  purer, 
10  to  12  per  cent  water  remaining, 

4.  Cooling  and  crystallising.    When  the  sugar  begins  to  crystallise  on  the  surface 
^the  vacuum  pan,  generally  at  80°,  the  temperature  is  lowered  to  about  50'',  as  too 

great  heat  at  this  stage  of  the  process  exercises  an  injurious  effect  upon  the  sugcur, 
Dirhich  now  forms  an  amorphous  mass,  and  is  drained,  washed  with  clean  syrup,  and 
prepared  for  ordinary  loaf  sugar.  Sugar-candy  is  the  result  of  slow  crystallisation, 
the  crystals  by  this  means  acquiring  a  larger  size  and  more  regular  form. 

5.  The  shaping  of  the  crystallised  mass  into  the  form  of  a  sugar-loaf  is  accom- 
plished by  evaporating  the  sugar  and  placing  it  in  earthen  conical  moulds  to  solidify 
at  a  temperature  of  25°  to  30°.    After  standing  ten  minutes  the  sugar  sets  into  form. 

6.  Drying  the  sugar.  After  standing  twelve  hours  a  green-coloured  syrup  is 
obtained  from  the  crystalline  mass,  which  is  removed,  and  the  crystals  submitted  to 
a  centrifugal  process  of  drying,  then  placed  in  a  drying-stove  at  a  temperature 
of  25%  which  is  gradually  increased  to  50°.  By  thus  refining  the  raw  sugar,  the 
ordinary  loaf  sugar  is  obtained. 

PTsdaetion  of  Raw  Sugar.      The  estimated  production  of  raw  sugar  in  1870  was  55 ,000,000  cwts. , 
the  largest  instahnent  being  from  Cuba. 

Beet-Root  Sugar, 

itaicatnve.  In  the  year  1747  Marggraf,  a  chemist  of  one  of  the  Berlin  academies, 
discovered  crystals  of  sugar  in  the  red  beet.  Beta  cicla,  which  he  deemed  capable  of 
manufacturing  into  the  commercial  article.  He  found  that,  treated  with  alcohol,  the 
white  beet  yielded  6*2,  and  the  red  variety  4*6  per  cent  of  sugar.  But  the  prepara- 
tion of  beet-root  sugar  was  not  developed  until  the  close  of  the  year  1800.  Achard 
and  Hermbstadt,  of  Berlin,  tried  many  experiments  with  this  new  product  with  equal 
success,  always  finding  that  beet-root  contained  crystaUised  sugar  to  the  amount  of 
6  per  cent,  with  4  per  cent  of  molasses,  and  sometimes  a  larger  quantity  of  sugar. 
About  the  time  of  the  continental  war  native  products  were  in  request  on  account  of 
the  difficulty  and  expense  of  obtaining  foreign  articles.  The  first  Napoleon  sup- 
ported the  new  product  in  the  pursuance  of  his  "continental  system  "  of  excluding 
cane  sugar  from  the  French  markets,  and  a  trial  of  the  German  method  was  made, 
but  it  was  not  crowned  with  the  success  it  has  now  achieved  until  ten  years  after 
his  overthrow.  The  annual  production  of  sugar  in  181  i^d  not  exceed  13,000,000  lbs. ; 
the  present  yearly  consumption  of  beet-root  sugar  exceeds  15,000,000,000  lbs.,  this 
enormous  amount  being  supplied  by  more  than  eighty  manufacturers. 

siMdM  of  BceL  The  vegetable  known  as  beet-root  is  a  large  fleshy  root  of  the  beet,  a 
plant  of  the  species  Beta  maritima,  largely  cultivated  in  France,  Belgium,  and 
Portugal  for  the  production  of  sugar.  There  are  several  varieties  of  the  two  species, 
th«  white  beet  being  preferred  on  account  of  its  yielding  more  sugar,  and  also  for  its 
purity  of  colour,  the  red  beet  being  chiefly  cultivated  for  culinary  purposes.    There 


368 


CHEMICAL  TECHNOLOGY. 


is  also  the  field  beet,  commonly  known  as  the  mangold  wurzeh  which  was  first  used 
as  provender  for  cattle  about  tlie  end  of  the  last  century.  Tlie  sugar  beet  hss,  in 
course  of  cultivation,  been  improved  by  many  new  methods  of  manuring,  Ac.,  until  it 
yields  13  and  sometimes  14  per  cent  of  sugar.  In  Germany  the  following  vaiieties 
df  beets  are  principally  cultivated : — 

I.  Quendlinburg  beet,  a  slender  rose-coloured  root,  and  very  sweet ;  it  is  matured 
fourteen  days  before  any  other  kind.  2.  Silesian  beet  .is  pear-shaped,  with  bright 
green  ribbed  leaves ;  it  is  known  as  the  green-ribbed  beet,  and  does  not  produce  so 
much  sugar  as  the  former.  3.  Siberian  beet  is  pear-shaped,  with  white-green  ribbed 
leaves,  and  is  known  as  the  white-ribbed  beet.  It  does  not  yield  so  well  as  the 
Silesian  beet,  although  of  a  greater  weight.  4.  The  French,  or  Belgian  beet, 
has  small  leaves  and  a  slender  and  spiral  root,  yielding  sugar.  5.  The  Imperinl 
beet  is  slender  and  pear-shaped,  yielding  much  sugar.  The  king  beet  is  a  biennial; 
in  the  first  year  the  root  is  merely  developed,  in  the  second  it  bears  seed. 

The  following  is  a  list  of  the  countries  where  the  beet  is  cultivated  for  sugar : — 


In 

Austria 

Austria 

Bohemia        

Prussia 

Prussia  | 

Baden     

France : — 
Northern  Departments-) 
Other  „  ] 

Prance 


Beets 
According  to—    gathered 

in  cwts. 


Erause 

Burger 

Neumann 

Lijdersdorff 

Thaer 

Stolzel 


104—145 
169—193 
112— 145 

146 

180 
120^160 


Dumas  {j^S 

Boussingault       149 


The  manufacture 
of  suitable  Beets 
in  cwts. 

88—123 
143—164 
95— "3 
124 

153 
102 — 136 

168 
105 
127 


Into  Sugar 
in  poondfl. 

770—1084 

1256— 1560 
836—1160 

1088 

1336 

896—1190 

1476 

924 

1116 


•••     ••• 


827 

11-3 

o-S 

15 
01 


In  general  140  to  160  cwts.  are  cultivated,  cut,  and  cleaned,  per  acre,  there  being  four 
Magdeburg  acres  to  one  hectare,  which  usually  yields  sufficient  roots  for  three  days'  worl. 

^^fu^aStf""***  The  flesh  of  the  beet  consists  of  a  quantity  of  small  cells  con- 
taining a  clear,  colourless  fluid.  The  constituents  of  the  sugar-beet,  according  to 
chemical  analyses,  are : — 

w  &  lier       ■••     •••     •••     •••     •••     ••• 

OUgcU         •••     ••■     •••     •••     ■•■      ••• 

x^ej-iiuoBc  •••     •••     •••     ••■     •••     ••• 

Albumen,  caseine,  and  other  bodies 
jl  aifCy  ma V ver    ■•■     •••     •••     •••     ••• 

Organic  substances,  citric  acid,  pectin  and  pectic  acid, 

asparagin,  aspartic  acid,  and  betain,  a  substance  having, 

according  to  M.  Scheibler,  the  formula  OZ5H33N3O6    .  • 
Organic  salts,  oxalate  and  pectate  of  calcium,  oxalate  and  Y      37 

pectate  of  potash  and  sodium 

Inorganic  salts,  nitrate  and  sidphate  of  potash,  phosphate 

of  lime  and  magnesia J 

Near  Magdeburg,  where  the  beet  is  extensively  cultivated,  the  general  results 

give  :— 

The  greatest  sugar  production,  as  13*3  per  cent. 

That  from  inferior  beets,  as     ...      9*2        „ 

The  average  beet  yielding        ...    iia        „ 


^ 


SUGAR.  369 

The  components  of  the  beet  vary  according  to  the  time  of  the  year,  it  at  some 
periods  containing  more  water  than  at  others,  from  82  to  84  per  cent  being  the 
average.  In  the  antomn  it  does  not  contain  slime  sngar ;  in  February  and  March 
the  components  intermingle  and  some  decrease  nearly  2  per  cent,  as  shown  by 
the  following  analyses : — 

October.  Febmary. 

3*49  per  cent.  2'52  per  cent. 

8206      „  8436 

1240      ,,  io'6o 

o'oo      „  065 

075      „  063 


••■ 


Woody  fibre  and  pectin 

Water    

Sugar     

Slime  sugar  ... 
Mineral  salts... 


Organic  acid  and  extractives  i'30      „  1*24 

lOO'OO  lOO'OO 

12  J  cwts.  of  beet  yield  on  an  average  i  cwt.  of  raw  sugar. 
SMchaztmctiy.      The  measuro  of  the  amount  of  saccharine  matter  contained  in  the 
Taiions  crude  sugar  productions  can  be  estimated  either  by  the — 

1.  Mechanical, 

2.  Chemical,  or 

3.  Physical  method. 

Mcehanieai  Method.  The  middle  part  of  the  beet  is  cut  in  thin  slices  to  the  weight  of 
25  to  30  grms.  each,  and  dried.  From  the  difference  in  weight  before  and  after  drying,  the 
quantity  of  water  contained  in  the  root  is  ascertained.  The  dry  residue  is  pulyerlsed,  and 
then  treated  with  boiling  dilute  alcohol  of  a  specific  gravity  of  0*83.  By  this  means  the 
sugar  is  dissolved,  and  tbe  weight  ascertained.  The  insoluble  residue  gives  after  drying 
the  weight  of  the  cellulose,  protein  bodies,  and  mineral  constituents.  If  the  alcoholic 
solution  be  placed  in  a  vacuum  over  caustic  hme,  it  gradually  becomes  more  and  more 
concentrated,  until  after  standing  about  a  day,  the  sugar,  owiag  to  its  insolubility  in  abso- 
lute alcohol, maybe  collected  in  small  colourless  crystals,  only  absolute  alcohol  remaining. 
Good  sugar  beets  give  20  per  cent  dry  residue,  the  water  amounting  to  80  per  cent.  Of 
the  20  per  cepi,  13  per  cent  is  usually  sugar,  and  the  remaining  7  per  eent  pectin,  cellu- 
lose, protein,  and  mineral  substances.  The  higher  the  specific  weight  of  the  juice  of  the 
beet,  the  more  sugar  it  contains.  The  juice  of  a  good  beet  properly  cultivated  marks 
8**  and  sometimeB  9°  B. 

otacmieai  Method.      The  chcmical  method  is  based  upon  the  following  facts : — 

a.  The  known  proportional  solubility  of  hydrate  of  lime  in  cane  sugar. 

b.  The  capability  of  a  cane  sugar  solution  to  reduce  the  hydroxides  of  copper  to 

protoxides,  the  quantity  reduced  affording  an  estimate ;  and  the  conversion 
by  adds  of  cane  sugar  into  inverted  sugar  (a  mixture  of  levulose  with  dex- 
trose or  glucose). 

c.  The  fermentation  of  sugar,  giving  rise  to  the  formation  of  alcohol  and 

carbonic  acid,  the  amount  of  which  can  be  ascertained,  4C0a  corresponding 
to  I  mol.  of  cane  sugar,  Ci^H^^Ozi. 
The  first  of  these  methods  is  that  of  determining  the  solubility  of  hydrate  of 
lime  in  a  cane  sugar  solution.  The  fluid  containing  sugar  is  stirred  with 
hydrate  of  lime,  the  quantity  of  which  dissolved,  estimated  by  titration  with 
sulphuric  add,  determines  the  quantity  of  sugar.  The  second  method  is 
grounded  on  the  researches  of  M.  Trommer,  who  found — (i.)  That  cane  sugar 
in  an  alkaline  fluid  does  not  reduce  oxide  of  copper;  but  it  becomes  reduced 
if  the  sugar  has  previously  been  boiled  with  sulphuric  or  hydrochloric  acid, 
the  acid  converting  the  cane  into  inverted  sugar.  2.  The  quantity  of  the  reduced 
protoxide  is  proportional  to  tlie  quantity  of  sugar.    Barreswil  and  Feliling  give  a  test 

2  B 


370  CHEMICAL   TECHNOLOGY. 

based  on  this  law: — An  alkaline  solution  of  oxide  of  copper  is  made  W 
dissolving  40  grms.  of  sulphate  of  copper  in  160  grms.  of  water,  and  adding 
a  solution  of  160  grms.  of  neutral  tartrate  of  potash  in  a  little  water,  with 
600  to  700  grms.  of  caustic  soda  ley  of  a  specific  gravity  =  1*12.  The  mixtore 
should  be  next  diluted  to  11544  c.c.  at  15°.  A  litre  of  this  copper  solution  contains 
34*65  grms.  of  sulphate  of  copj^er,  and  requires  for  its  reduction  5  gnns.  of 
dextrose  or  levulose ;  or  10  atoms  sulphate  of  copper  (1247*5)  are  reduced,  by  means 
of  I  atom  of  dextrose  or  levulose  (180),  to  protoxide  (34*65:5  =  1274*5 :i80i 
or  =  693:1),  10  c.c. of  the  copper  solution  correspondLug  also  to  0050  grms.  of  diy 
dextrose  or  levulose.  Mulder  prefers  a  solution  in  which  i  part  of  oxide  of  copper 
corresponds  to  0552  part  of  dextrose  or  levulose  of  the  formula  CeHiaOg+HtO ;  by 
the  use  of  this  test-liquor,  the  amount  of  sugar  may  be  ascertained  with  great 
accuracy.  By  another  method  10  c.c.  of  this  copper  solution  are  heated  with  40  c.c 
of  water,  and  placed  in  a  sugar  solution  till  all  the  oxide  of  copper  is  reduced.  Wlien 
this  point  is  nearly  reached,  the  precipitate  becomes  redder,  and  forms  more  rapidly. 
Testing  the  filtrate  with  ferrocyanide  of  potassium  will  throw  down  a  yellow  pre- 
cipitate if  there  be  sugar  in  excess.  The  copper  salts  are  instantaneously  reduced 
by  the  sugar  in  corresponding  quantities ;  long  boiling  is  not  necessary.  100  parts 
dextrose  or  levulose  correspond  to  95  parts  cane  sugai*. 

Ferment  Teat.  The  third  method,  the  ferment  test  as  it  is  generally  termed,  is 
grounded  on  the  fact  that  a  solution  of  sugar  may  be  preserved  for  an  indefinite 
period  in  an  open  or  close  vessel ;  but  that  if  decomposing  azotized  matter  be  acci- 
dentally or  intentionally  added,  the  sugar  is  converted  first  into  dextrose  or  levulose, 
which  sufiering  vinous  fermentation  is  converted  into  alcohol  with  the  evolntioii 
of  carbonic  acid. 

I  mol.  of  cane  sugar,!     yields  by     (4  mols.  of  carbonic  acid  =  176, 
CHO  =  342,  j  fermentation  •  4  mols.  of  alcohol  =  188. 

The  estimation  of  the  quantity  of  carbonic  acid  is  easily  performed  by  means  d 
the  alkalimetric  apparatus  of  Fresenius  and  Will.  The  fermentation  being  com- 
plete, the  air  is  sucked  out  of  the  apparatus,  and  the  amount  of  carbonic  add 
estimated  from  its  loss,  which 

Multiplied  by  Va*  =  1*9432,  gives  the  quantity  of  cane  sugar. 
„  YgO  =  2*04545,  gives  the  quantity  of  dextrose, 

phyiicai  Method.  The  raw  sugar  containing  dextrose  or  dextrine  rotates  the  plane 
of  polarised  light  to  the  right  hand  in  proportion  to  the  quantity  present  A 
sugar  solution  of  100  c.c.  containing  15  grms.  of  sugar  turns  the  ray  of  polarised 
light  of  200  millimetres  length,  20**  to  the  right  Proportionally,  a  solution  of 
100  c.c.  containing  30  grms.  of  sugar,  turns  the  ray  40^  The  forms  of  polarimeters 
are  very  various,  and  this  method  of  estimation  has  received  attention  from  many 
eminent  physicists. 

^?Jffl  the  Belt.*"  The  preparation  of  sugar  from  the  beet  consists  in  the  following 
operations : — 

1.  Washing  and  cleansing  the  beet. 

2.  Obtaining  the  juice  from  the  root. 

a.  The  root  is  giouud  to  a  pulp  and  subjected  to  hydratdic  pressure. 

(5.  The  juice  is  extracted  from  the  pulp  by  means  of  a  centrifugal  machine. 

y.  According  to  Schiitzenbach,  after  the  maceration  juice  is  separated  from  the 

pulp  by  water. 
5.  The  root  is  cut  into  thin  slices  and  placed  in  a  vessel  (diffusion  apparatus)  irith 

water  at  a  certain  temperature. 


SUGAR.  37> 

3.  Refining  the  jnice  nith  lime,  and  removing  the  lime  with  carbonic  acid. 

4.  Filtering  the  juice  through  charcoal. 

5.  Boiling  the  refined  juice  for  crystallisation. 

6.  The  manufacture  of  raw  and  refined  sugar. 

o.  Raw  or  moist  aagar, 
/?.  Refined  or  loaf  engor. 
I.  Wiukimj  and  Cleanitng  the  Sat. — The  heet  when  newly  dug  requires  waahing 
and  cleansing,  which  takea  10  and  sometimes  zo  per  cent  from  the  weight  of 
the  root.  Champonnois's  waaliing  machine  is,  perhaps,  the  most  sncceBBful:  it 
CKtDsists  of  revolving  drams  of  open  iron-  or  wood-work  placed  in  a  trough  supplied 
with  water,  the  drums  making  from  8  to  40  revolulions  in  a  minute.  The  beets 
cleaased  from  all  impuritiea,  washed,  are  cnt  and  submitted  to  elutrialion  on  a  sieve. 
lYom  1000  to  izoo  cwtB.  beets  can  be  prepared  per  day  of  twenty-hour  hours  with 
ahorse  power ;  the  length  of  the  washing  drum  being  from  3-1  to  4  metres  with  a 
diameter  of  i  metre,  the  drum  making  from  30  to  40  revolutions  per  minute. 

■2.  Separating  ths  Juice  froia  the  Rout. — There  are  two  metliods  of  effecting  this; 
the  first  by  grinding  the  root  to  a  pulp,  and  then  removing  the  juice  by : — 
a.  Pressing. 
fi.  Centrifugal  force. 
y.  Maeeraliou. 
The  sugar  in  the  beet-root  is  contained  in  the  cells,  which  are  easily  opened,  but 
require  a  moderate  pressure  to  extract  the  juice  containing  the  sugar.    A  hand- 
grinding  macliine  is   sometimes  found    sufficient  for   this  purpose,  but   Thierry's 
crushing  machine,  shown  in  the  following  illustration,  I'ig.  211,  ia  generally  used. 
The  grinding  cylinder.  Fig.  ai2,  is  0-5  to  o'b  metro  in  length,  and  08  to  i-o  metre 


io  diameter,  tlie  periphery  being  set  with  250  saw-blndes.  (  (Fig.  2ii|  is  a  funnel 
to  admit  water ;  i  tho  trough  into  which  the  roots  aie  placed ;  m  tlio  cistern  to 
receive  Ihe  pulp.  The  motive  power  gears  with  a  nnd  »  ;  and  the  motion  of  the 
axis  of  r(  is  by  means  of  the  pinion,  '1,  communiealed  to  llie  ecpfiiiric.  il.  and  friction 
roller,  e,  thence  by  the  arm,  g,  and  coniiecling-rod.  h,  to  fho  phiiiger,/.  which  presses 


37i  CHEMICAL   TECHNOLOGT. 

the  roota  ^^at  the  edges  of  the  saw-bladea  concealed  b;  the  case,  u,  the  pressmi 

bemg  regulated  by  the  weight,  k.     The  cylinder  revolves  looo  to   t300  times  » 

miuute,  reducing  &om  800  to  1000  cwta.  of  beets  to  pnlp  in  twen^-foor  honre. 

The  water  from  f  ia  necesBary,  thit 

Fio.  112.  the  pulp  may  be  ground  to  ft   finer 

connstenee. 

a.  The  juice  is  obtained  bj 
pressing  the  pulp  by  mewis  of  ■ 
stone  or  iron  roller  through  a  Berin 
of  linen  cloths.  But  in  the  French 
maaufBCtories  the  hydraulic  or 
Bmmah  press  is  most  gener«Uy 
adopted.  The  pulp  h  placed  in 
sacka  or  bags  between  iron  pl&tes, 
and  subjected  to  a  pressure  of  500 
to  600  lbs.  The  expressed  juice  flows  from  the  bed-plate  into  a  pipe,  which  condada 
it  to  a  receptacle.  100  cwts.  of  beet,  with  a  pressed  residue  of  18  per  cent,  yield 
82  per  cent  good  juice, 
ThB  BHidna.  According  to  the  researches  of  M.  Wolff,  the  residue  of  the  cruaheit 
used  at  Hohenlieim  contains — 


When  the  beets  are  pressed  with 

'resh  Roi 
81-56  68-OI  67-91  65'94 


_    per  cent  i4P^''  ^*"^^  Withont 

Fresh  Boots.  Water.  Water.  Water. 


Cellulose 1-33  6-15  6-04  6-« 

Sugar      11-88  7-86  7-58  6-7 

Protein    snliatances  087  1-05  1-67  ii'c 

Other  nutritions  „  3-47  11-36  1005  143 

10  parts  of  beet  leave  232  parts  residue  and  76-8  parte  juice  ol  the  following  e< 


Water 

Residue. 
.     ..     15  61 

Juice. 
65-95 

1?) 

Carbon  bydrata   . .      . . 
Protein  substances      . , 

::  l^ 

.    . .     0-38 

063 
058 

23-10  7680 

p.  The  juice  is  now  generally  obtained  from  the  pulp  by  means  of  the  centriAigal 
macbine  to  the  extent  of  50  to  60  per  cent,  wator  being  applied  to  the  residiie  to 
obtain  n  thin  pulp  also  used  in  sugar  manufacture.  A  centrifugal  machine  i  metn 
in  diamuter  will  express  100  cwls.  per  day.  The  power  to  which  the  first  juioeiadne 
is  51  atmosplieres,  60  per  cent  j[iice  being  expressed.  The  r«mainder  of  thejuic*. 
afUr  the  addition  of  wak-r  to  the  contents  of  the  machine,  is  expressed  at  a  pressnn 
of  18  atmospheres,  the  quantity  of  water  amounting  to  50  to  60  per  cent  of  th* 
quantity  of  beds.  Of  the  roots  50  per  cent  remain,  20  per  cent  in  the  reddoe,  tai 
30  per  cent  in  tlie  clarifyiiig  vessel. 

7,  Treating  the  bcet-piilp  according  to  Schulienbach's  method  of  immersion  Hid 
maceration  in  order  to  obtain  the  juice.  The  roots  are  cleaned  and  then  cut  m 
slices  by  a  tutting  mat-liine,  Tlii'y  are  then  passed  to  a  drying  chamber  belted  to 
50°,  aud  subsequendy  ground  to  a  meal.    Four  parts  of  this  meal  are  allowed  W 


SUGAR. 


373 


macerate  in  9  parts  water,  to  which  sometimes  sulphuric  acid  is  added.  Another 
method  is  to  moisten  the  dried  heet-meal  with  milk  of  lime,  and  afterwards  contmue 
the  operation  in  a  hath  of  water  heated  to  80**.  These  methods  are  largely  used  in 
Germany,  where  in  general  practice  it  is  found  that  475  cwts.  of  green  roots  yield 
I  cwt.  of  dry  heet-meal.  The  juice  is  afterwards  treated  with  lime-water  for  the 
purposes  of  purification. 

i.  Before  any  juice  can  he  ohtained  it  is  necessary  to  open  the  cells  in  which  it  is 
confined.  This,  as  has  heen  seen,  may  he  effected  by  pressure  or  by  maceration  in 
water,  by  which  the  cells  are  broken  and  to  which  they  yield  their  sugar.  The 
action  with  each  cell  is  very  similar  to  that  of  the  dialyser  used  in  dialysis ;  the 
sngar  becomes  gradually  diffused  in  the  water,  the  insoluble  substances  remaining  with 
the  cell.  By  this  means  a  very  pure  sugar  solution  may  be  obtained  and  afterwards 
concentrated  The  diffusion  residues  are  always  very  watery,  containing  93  per 
cent  water  and  7  per  cent  dry  substances. 

oonponontiofthejaiee.  The  juicc  after  being  expressed  from  the  pulp,  if  allowed  to 
remain  exposed  to  the  action  of  the  air,  throws  down  a  dark  Haky  precipitate. 
The  more  free  acids  the  juice  contains  the  lighter  will  be  tiie  colour  of  the 
precipitate,  and  the  juice  will  appear  of  a  brown-red.  The  juice  is  not  only 
a  solution  of  sugar,  but  contains  the  soluble  constituents  of  the  beet,  in 
which  nitrogenous  and  mineral  substances  are  very  prominent.  Sugar  utfder 
fermentation  forms  lactic  acid  and  other  products ;  but  it  is  separated  from  all  im- 
purities and  refined  into  crystals.  The  usual  method  of  refining  is  to  boil  tlie 
juice  rapidly  in  copper  refining- vessels  constructed  with  doxible  bottoms.  The 
rapid  boiling  separates  the  coagulated  juice,  whilst  the  fi'ee  acid  is  neutralised 
by  the  introduction  of  dilute  milk  of  lime.  The  lime  also  serves  to  separate 
the  nitrogenous  substances  of  the  juice,  and  enters  into  a  combination  with  a 
small  portion  of  the  sugar,  forming  sugar- lime  or  calcium-saccharate.  Lime,  too, 
throws  down  from  their  salts  protoxide  of  iron  and  magnesia,  while  potash  and 
floda  are  set  free.  The  quantity  of  Hme  added  depends  upon  the  condition  of  the 
root.  As  a  rule,  to  100  pounds  of  juice,  i  to  2  pounds  of  lime  are  added,  or  to  2  cwts. 
of  roots  I  pound  of  lime.  The  insoluble  combinations  of  lime  are  separated  from  the 
juice  as  a  slime  by  filtering  in  a  filtering  press.. 

3.  De-Liming,  or  Saturating  the  Juice  with  Carbonic  Acid. — The  clear  juice  is  by  no 
means  a  pure  sugar  solution,  but,  contains  besides  free  sugar,  sugar-lime,  free  potash, 
and  soda,  sometimes  ammonia,  and  a  small  quantity  of  nitrogenous  organic  substances, 
decomposed  by  the  free  alkalies,  ammonia  being  largely  developed  by  their  evaponition. 
The  juice  also  contains  various  organic  acids  (as  aspartic  acid)  and  alkaline  salts  (as 
sulphate  and  nitrate  of  potash).  The  decomposition  of  the  sugar-lime  efl'ects  the 
removal  of  the  extraneous  substances  from  the  juice.  The  physical  method  of  puri- 
fying the  juice  is  by  filtering  it  through  animal  charcoal,  while  the  chemical  method 
is  effected  by  means  of  carbonic  acid.  The  use  of  carbonic  acid  was  first  recom- 
mended by  Barruel,  of  Paris,  in  i8n,  and  later  by  Kuhhaiann,  Schatten,  and 
Michaelis.  The  latter  obtained  the  gas  from  the  action  of  sulphuric  acid  upon 
chalk,  or  better  upon  magnesite ;  the  former  employed  the  gas  resulting  from  the 
combustion  of  charcoal  or  coke.  Lately,  Ozouf  has  prepared  carbonic  acid  gas  by 
heating  bicarbonate  of  soda.  In  the  German  manufactories  the  decomposition  of  Uie 
sugar-lime  is  effected  in  a  Kleeberger's  pan,  Fig.  213.  Tliis  apparatus  consists  of  a 
cast-iron  cistern,  b,  to  contain  the  juice.    The  carbonic  acid,  having  been  washed  in 


374  CHEMICAL  TECHNOLOGr. 

pure  water,  is  admitted  by  the  pipe,  nt,  which  dips  nearly  to  Qie  bottom  of  th« 
vessel,  B,  and  is  divided  intemaUj  by  a  partition  for  the  better  diBsemiiiatioD  af  the 
gas.  The  imabsorbed  gas  collects  in  b  over  the  jniee,  whence  it  paases  throogh  Uie 
opening,  p,  into  the  upper  chamber,  a.  When  the  Juice  sinks  thionghji  into  b,  tbe 
gae  there  collected  passes  thiough  a  into  n,  and  is  thence  re-c«ndncted  to  Iba 
reservoir.  When  the  juice  is  sufficiently  cleared,  the  carbonic  acid  cock,  o,  is  tanwd 
o£  and  the  juice  allowed  to  flow  into  a  reservoir  through  q,  where  the  carbouts 
of  lime  settles.    The  clear  juice  is  then  fit  for  cryBtallisation.    The  man-bole,  <,  i* 


provided  for  the  cleansing  of  the  apparatus  from  separated  carbonate  of  lime.  Tbt 
juice  to  he  de-limed  is  supplied  to  the  cistern,  fi,  b;  means  of  the  pipe,  i,  and  the 

ouuir uitimdi oi it»ijiiiiii«     InEtBod  of  employing  carbonic  acid  or  Buimal  obareoali  tbelimc 
Uui  joiM.  o(  the  Eugar-lime  may  be  removed  by  Ibe  addition  of  a  snlnltiiM 

or  an  acid  which  forms  with  it  an  innolublo  body,  bnt  does  not  aSect  the  sngar.  OuIh 
acid  is  suitable  far  this  purpose,  oxalate  of  limo  being  ineoluble  in  the  augai  Eolotioiii 
but  the  acid  ia  very  expensive,  and,  besides,  the  precipitate  is  too  fine,  passine  througb  th* 
filter.  Phosphoric  acid  is  aaed  for  the  purpose,  phosphate  of  lime  separating  ioU 
flakes  which  con  be  easily  temoved  by  filtering  through  a  tbin  layer  of  cluiooaL  iuj 
free  phospborio  acid  is  converted  into  pbonphate  of  ammonia,  neutraliaing  th< 
alkali,  while  the  eicess  of  ammonia  is  Tolatilised  on  the  application  of  best  to 
the  jnioe.  Oleic,  stearic,  and  hydiated  silicic  acids,  and  casein,  similaily  throw  dove 
precipitates.  Acar  ases  pectio  acid,  which  forms  vith  the  lime  an  insolabla  pectilt- 
Morgenatem  has  found  sulphate  of  magnesia  pteparod  from  the  Stassfurt  kiraeriw 
snccesafnl  in  removing  part  of  the  impurities  as  well  as  a  portion  of  the  colooring  oMUt- 
PrickenhauB  tried  hydrofluoric  acid.  In  iSii  Piouet  recommended  sulphite  of  lime: 
and  in  1829  Dubmufaut  took  ont  a  patent  for  the  employment  of  sulphnroua  Ki^ 
MelBons,  of  BmsBels,  in  1849,  employed  hyposulphurooB  acid,  which  at  100°  separaw 
the  lime  and  moat  of  the  protein  BubEtanaes,  and  disguises  for  a  time  the  eoloniilig 
matter,  the  colour,  however,  returning  on  exposure  to  air,  and  remaining  pennanent. 

PmUrini  >itii  Buyu.  About  fifteen  years  ago  Dubnmfant  and  De  Hassy  patented  ■ 
method  of  purifying  the  juice  by  means  of  oaustio  baryta,  which  forme  with  cane  mg" 
at  the  boiJing-point  the  insolnble  sacoharate,  CuHuOu.BaO;  in  practice  sofEdait 
eauatic  baryta  is  added  to  throw  down  all  the  sugar.  The  sugar-ba^ta  ia  thus  Eepe- 
rated  from  the  aupomatant  fluid  in  which  all  the  foreign  substances  remain  snapenjed ; 
and  ia  next  treated  with  carbonic  acid  to  form  carbonate  of  baryta  and  set  the  npl 
free.  The  solution  ta  then  filtered  and  some  gypsum  added,  which  gives  lise  to  tba 
double  deoomposition  of  the  carbonate  of  baryta  into  aolphate,  and  of  the  gypinni  ieto 
carbonate  of  liine. 

4.  The  FiltTation  of  the  Juice  through  Aninml  Charaml,  and  the  Ecaporalion  y 
the  Juice.~Th.o  various  apparatus  here  play  the  most  important  part. 


SVOAB.  375 

TiH  FTHer.  Besides  acting  as  a  filter,  charcoal  posBeaaes  the  property  of  removing  the 
colour  from  the  liquid  allowed  to  percolate  through  it.  Wood  charcoal  was  first  used 
for  the  purposes  of  sugar- refiuing  in  1798.  but  lately  has  given  place  to  the  employ - 
ment  of  animal  charcoal  (bone  charcoal),  whicli,  according  to  Schatten.  has  a 
tendency  to  remove  the  lime  and  salts  in  the  juice.  At  first  it  was  used  in  powder, 
but  now  it  is  employed  in  the  form  of  lumps.  The  old  melhod  consisted  in  boiling 
the  powdered  charcoal  with  the  juice,  blood  being  afterwards  added,  as  in  the  usual 
methods  of  sugar-refining. 

Fig.  214  exhibils  a  section  of  Taylor's  litter,  which  has  been  in  use  since  1825. 
The  juice  is  admitted  lo  the  upper  ciatem,  a,  by  means  of  the  pipe,  0,  and  gradually 
percolates  through  the  long  linen  bags  suspended  from  the  bottom  of  a.  in  d.  and 
contaijiing  charcoal,  a  layer  of  charcoal  being  also  placed  in  a.    The  mouth  of  each 


bag  is  kept  open  by  a  funntl  piece  show  a  at  p      Ihe  filttred  juice  is  received  into 
the  lower  cistern,  whance  it  passes  by  the  pipe  a  mto  the  reservoir. 

i>iuiiciiii'ii  nui.  Fajot  des  Charmes  employed  aniinal  charcoal  in  iSzz.  but  Dumont 
was  perhaps  the  first  to  make  its  use  successful  by  means  of  a  tiller  still  bearing 
his  name,  shown  in  vertical  section  in  Fig.  215,  and  in  plan  in  Fig.  216.  The  juice 
is  supplied  to  (he  filter,  a,  from  the  cistern,  d,  the  supply  being  regulated  hy  tho 
IxUl-cock,  d  e.  The  pieces  of  charcoal  in  a  rest  upon  the  sieve,  b  b,  the  percolating 
juice  being  received  into  the  cistern,  and  removed  hy  the  tAp,  0.  c  is  a  man-hole  for 
the  cleansing  of  the  apparatus. 

Bn»i«uiM  Pvu.      The  pans  generally  iu  use  for  evaporating  Uio  juice  t< 
are  made  sufficiently  strong  to  withstand  high  steam  and  atmosphoi 
processes  of  evaporation  are  : — 

I.  Under  the  usual  air-pressure : 

a.  In  pans  suspended  over  au  open  flie  ; 

h.  With  high  steam  pressure  ; 

c.  By  hot  air. 


o  crystallisation 
c  pressure.    The 


376  CBEUICAh  TECHNOLOar. 

n.  By  diminisbed  Bir-presBUie  or  vacnum  pooB, 

a.  By  tlie  air-pump ; 

b.  On  the  principle  of  the  Tonicelli  vacuum ; 
o.  Bj  means  of  steam  and  condensatioii ; 

d.  By  combining  the  methods  a  and  b. 
The  pans  are  constiucted  to  prevent  the  boiling  over  of  tlie  imce.    One  of  the  iD 
eSects  of  an  open  fiie  is  the  danger  of  over-heating,  or  bnming  as  it  is  called,  wbidi 


det«rioiates  the  quality  of  the  sngar  solution  in  varions  waya,  forming  canmeL 
Fig.  317  is  a  vertical  section,  and  Fig.  218  the  plan  of  an  open  pan  airangeinait. 
s  is  the  evaporating  pan,  a  the  Gre-plaoe,  c  the  aah-pit,  k  and  □  the  flue.  The  fad 
is  placed  on  the  sloping  grid,  b,  through  the  fiimace  door,  a.    The  fire-room  >• 

Fio.  316. 


arched,  the  flame  and  hot  gases  pasmng  through  the  openings,  »  »,  into  contact  witb 
the  evaporating  pan ;  1 1  admit  air  to  the  Sre-plaoe.  The  use  of  a  suspended  p*n- 
as  shown  in  Fig.  zig,  is  preferable  for  many  reasons.  When  the  juice  is  aofliriwiuj 
concentrated,  the  workman  has  only  to  pull  the  rope,  m,  to  empty  the  pan. 

The  Pecquer  eraporoting-pan  is  heated  by  steam,  the  pipes.  Figs.  2x0  and  iti. 
being  placed  horizontally  under  the  pan.  The  steam  enters  by  a  into  h,  p««« 
through  the  pipes,  and  is  conveyed  away  by  d  and  «.    The  heating  by  iteam,  tMBO" 


377 


■e  equable  and  etudlj  managed.    Wben  the  juice 
leans  of  the  lever,  nt,  ia  tilted  up,  and  the  juice 


the  advantage  of  cleanliness,  ia  mo: 
IB  auffidentlj  heated,  the  pan,  bj  n 
ran  off  by  opening  g. 

The  evaporation  b;  hot  air  is  beat  exemplified  in  the  pans  of  Brame-Chevallier 
•ud  Piclet.    That  of  the  latter  is  shown  in  Fig.  333.    The  evaporating  pan,  a,  is 


directly  over  the  fire,  tlie  products  of  the  combustion  passing  bj  the  pipes,  b.  to  the 
cliim&ej,  g.  The  steam  from  the  evaporating -pan  passes  away  through  «.  Bj 
ineaua  of  the  axis,  a,  and  sieves,  c  d,  set  in  motion  by  steam-power  gearing  with  b, 
the  jnice  is  thoroughly  exposed  to  the  bla«t  of  hot  air  generated  in  c,  and  passes 


FtO.  3ZO. 


by  the  hot  pipes,  b,  into  the  pan,  *.    By  this  eonstaat  atining  the  jnioe  ia  prenntod 
from  adheitog  to  the  pans,  and  becoming  bnint. 
VHauFia.      An  improved  evaporatioD  apparatus  was  invented  by  Howard,  in 
181Z,  in  whiob  the  juioe  was  placed  in  chamben  of  rarefi»d  lui,  01  raoonm  pans. 


378  CHEMICAL   TECHNOLOGY. 

The  lowest  boiling-point  of  tlie  clew  juice  in  the  vacuum  pans  is  46-1''  C. ;  the  nsual 
temperature  at  which  the  sugar  is  boiled  ess"  to  71-1°  C. ;  at  a  higher  temperature 


the  juice  loaes  its  power  of  crTstallisatioii,  and  fonos  caramel.    The  vacnnm  may  be 
fioauddered  as  two  distinct  apparatus: — i.  The  boiling-paiLi   su  The  apparatss  &r 

■nhfiiTfffc"'ff  tVi*  air  and  condensiiuf  the  steun  from  the  juice* 


SUGAR. 


379 


In  France,  Derome'a  apparatus  is  extcnsivelj  tised ;  but  that  wliich  we  shall 
deaeribe  meets  with  general  approval  iu  German;,  and  has  the  advantages  of  being 
simpler  in  construction  and  less  costly  to  work.  Fig,  223  is  a  perspective  view, 
and  Fig.  224  a  section  of  this  form  of  evaporating  pan.  Tlie  boiling-psjt,  b, 
consists  of  two  air-tight  hemispheres,  sarmounted  bj  a  funnel  connected  bj  the 
tube,  I,  with  the  condenser,  a.  The  apparatus  is  supplied  with  steam  by  r  »,  the 
ateam  circulating  in  the  boiling-pan  by  means  of  the  pipes,  g,  Fig.  224.  By  opening 
the  lever  valves,/)  the  juice  can  be  ran  by  means  of  the  pipe,  0,  into  the  pan, p. 
When  the  pan,  after  continued  boiling,  requires  to  be  re-fiUed,  the  pipes  I  and  w 
are  connected  to  an  air-pump.  The  manometer,  k,  shows  the  state  of  the  air-pressare, 
which  can  be  regulated  by  opening  the  pipes  conueotod  to  the  Tocnum-cliamber.  By 


means  of  the  gauge-cylinder,  o,  the  quantity  of  symp  in  the  boUing-pan  can  be 
ascertained,  the  gauge -cylinder  being  connected  to  the  boiling-pan. by  the  pipes  a 
and  t,  and  the  height  read  off  from  the  gauge-tube.  n.  The  syrup  can  be  removed, 
for  the  purpose  of  ascertaining  its  consistency,  from  the  gauge-cylinder  by  means  of 
either  of  the  three  pipes,  bed.  By  u  steam  can  be  admitted  to  the  boiling-pan  and 
condenser,  e  is  generally  of  stout  glass,  through  which  the  state  of  the  juice  can 
be  observed,  g  is  the  grease-cock,  butter  or  Sostman's  paraffin  being  generally  used 
to  prevent  the  adhesion  of  the  scum  to  the  working  parts  of  the  pan,  the  taps,  &o. 
^ia  the  man-hole.  The  condenser  consists  of  the  jacket,  b,  arranged  to  prevent  the 
mixii^  of  the  juice  with  the  water  used  for  condensation,  x  is  the  gauge.  The 
pipe  m,  conveying  water  to  the  condenser,  terminates  in  a  rose,  t  is  a  themtometer, 
showing  the  interior  temperature  of  (he  boiling-pan. 

The  air-pump  being  set  in  operation,  the  tube  e  is  opened,  and  the  gauge-cylinder 
filled  by  the  juice  rising  from  q.  By  closing  m  and  opening  <  the  juice  is  admitted 
to  the  boiling-pan.  When  this  is  half  fall  the  steam  pipe,  1,  is  opened,  the  steam 
quickly  heating  the  contents  of  the  pan  to  the  boiling'point.    The  coudouer  ia  tiien 


38o  CHEMICAL  TECHNOLOGT. 

placed  in  working ;  by  opening  the  pipe,  I,  the  steam  of  the  juice  passes  into  the 
condenser,  where  it  is  speedily  condensed,  passing  with  the  water  through  p. 
Trappe's  arrangement  is  sometimes  found  useful  in  working  the  Torricelli  Yacumn. 
The  condenser  is  io'6  to  ii  metres  above  the  pan ;  from  it  reaches  a  pipe  to  a  water 
reservoir  beneath,  the  height  of  the  water  in  this  pipe  indicating  the  degree  of 
rarefaction  in  the  pan. 

"'•'jSjS!'"**  Notwithstanding  the  first  purifying,  many  substances  still  remain 
in  the  juice,  the  carbonic  acid  treatment  not  completely  removing  the  lime,  free 
potassa  or  soda,  ammonia,  and  nitrogenous  organic  substances.  According  to 
Leplay  and  Cuisinier,  looo  hectolitres  of  juice  yield  300  kilos,  of  sulphate 
of  ammonia.  Among  the  former  decomposition  products  are  also  found 
nitrate  and  sulphate  of  potassa,  chloride  of  sodium,  &c.,  besides  levulose,  and 
humus  substances,  which  impart  a  brown  colour  to  the  juice.  The  clear  juice  is, 
therefore,  again  evaporated  to  density  of  24°  to  25°  B.,  and  afterwards  filtered  through 
animal  charcoal.  During  this  second  evaporation  the  ammonia  is  got  rid  of,  as  well 
as  the  organic  substances,  while  the  filtration  removes  the  alkaline  salts  and  the 
lime,  and  also  lightens  the  colour. 

5.  Boiling  the  Evaporated  and  Filtered  Juice  to  C)y8taUisation. — ^After  the 
second  filtering  and  evaporation  the  juice  is  technically  termed  "  thin  juice,"  and 
is  concentrated  to  "thick  juice"  by  boiling  to  the  point  of  crystallisation.  As 
a  rule,  the  juice  speedily  begins  to  seethe  and  rise  in  the  usual  manner  of  boiling 
fluids ;  but  if  the  throbs  in  this  **  dry  boiling,"  as  it  is  termed,  sound  heavy  or 
dull,  "  fat "  as  it  is  called,  it  indicates  that  some  quantity  of  free  alkali  still  is  contained 
in  the  juice,  and  a  remedy  is  found  in  the  cautious  addition  of  sulphuric  add.  The 
estimation  of  the  specific  gravity  of  the  boiled  juice  is  not  practically  available 
as  a  means  of  ascertaining  the  degree  of  concentration.  This  is  best  arrived  at 
by  noting  the  boiling-point  of  the  juice,  which  varies  for  pure  juice  from  it2°  to 
120^;  but  generally  an  empirical  test  is  employed,  a  small  quantity  of  the  juice 
being  removed  from  the  pan  on  a  stick  of  wood,  and  rubbed  between  the  fingers, 
a  little  practice  soon  enabling  the  workman  to  estimate  pretty  accurately  the 
consistence  of  the  syrup.  In  some  cases  the  juice  is  removed  in  a  ladle,  and  the 
consistency  judged  from  the  tenacity  with  which  the  juice  clings  to  the  side  of  the 
ladle  when  sharply  blown  with  the  breath.  The  juice  when  sufficiently  concentrated 
is  removed  to  t^e  cooler  to  crystallise. 

6.  Preparation  of  Moist  or  Raw  Sugar,  and  of  Loaf  Sugar. — ^When  the  juice  [ 
has  been  brought  to  such  a  degree  of  concentration  that  it  crystallises  on  cooling,  I 
the  final  processes  commence.  The  crystallisation  proceeds  gradually,  the  crystals 
forming  more  quickly  the  purer  the  juice.  The  further  the  purification  has  been 
carried,  the  easier  is  the  separation  of  the  sugar  into  molasses,  and  loaf  or 
crystallised  sugar.  The  loaf  sugar  is  again  warmed  in  a  pan  and  allowed  to  crystal- 
lise in  a  form  to  which  the  general  name  of  sugar-loaf  is  given,  variously  distin- 
guished according  to  their  size  into — 

Loaf  form,  containing  30  to   34  pounds  sugar. 

Coarse  lump  form  „  60  to   70         „ 

Inferior  form      „      120  to  150         „ 
The  forms  are  generally  made  of  day,  Fig.  225,  encircled  by  a  band  of  wood  to 
preserve  the  shape.    Sometimes  the  forms  are  of  polished  plate  iron ;  papier  maeke 
has  been  used  with  tolerable  success  for  this  purpose.     By  the  old  method  of 


SUGAR. 


381 


Fig.  225. 


boiling  the  sugar  in  an  open  pan,  the  crystals  formed  nneqnally  in  the  monld, 
and  had  to  be  removed  in  several  ways.  The  vacuum  pan,  however,  does  away 
with  this  process,  the  sugar  crystallising  evenly  in  very  large  quantities.  To 
heighten  the  whiteness  of  the  loaf  sugar,  the  manufacturer  sometimes  adds  ultra- 
marine in  quantities  of  2i  pounds  to  1000  cwts.  sugar. 

After  standing  twenty-four  hours  the  sugar  is  sufficiently  set 
to  be  removed  from  the  mould.  In  working  on  the  large  scale, 
the  moulds  are  generally  arranged  as  shown  in  Fig.  226,  the 
overflowing  syrup  falling  into  m,  whence  it  is  conveyed  by  o. 
This  syrup  is  known  in  the  trade  as  green  treacle  or  golden 
syrup. 

Diminjng  the  orystah.  It  is  YGiy  necessaiy  that  all  sugars  before  being 
moulded  should  be  thoronghly  drained  &om  all  non-crystallised  juioe, 
which  would,  if  allowed  to  remain,  injnrioosly  affect  the  oolonr, 
firmness,  and  dryness  of  the  sugar-loaf.  The  method  of  effecting 
this  drying  is  by  first  passing  a  small  quantity  of  water  through  the 
sugar;  the  water  combines  with  a  small  portion  of  the  sugar  to 
form  a  very  pure  syrup,  which  supplants  the  molasses  or  non- 
crystallised  juice  in  the  interstices  of  the  loaf.  Practically  this, 
filtering  takes  place  in  linen  cloths,  or  the  form  is  filled  with  a  layer  of  pure  juice  to  a 
thickness  of  2  to  3  inches,  water  being  added  till  a  syrup  of  the  comdBtenoy  of  honey 
is  obtained,  when  the  crystallised  sugar  is  forced  in,  and  the  form  set  aside  to  drain. 
Lately,  a  suction  apparatus,  the  invention  of  M.  Eransohutz,  has  been  employed.  This 
apparatus  consists  of   the  usual  series  of 

forms,  to  the  bottom  of  each  of  which  is  Fio.  226. 

attached  a  tube  proceeding  to  a  vacuum 
chamber,  serving  idso  as  a  reservoir  for  the 
extracted  molasses.  The  vacuum  chamber 
ia  attached  to  an  air-pump  in  the  ordinary 
manner. 

Tb«  o«ntzifaffa]  Drier.  The  labouT  and  uncer- 
tainty attending  the  above  methods  of  drying 
have  given  rise  to  the  invention  of  a  ma- 
chine by  which  the  non-crystallised  juice 
may  be  extracted  before  the  sugar  is  moulded. 
Schutzenbaoh's  machine  for  this  purpose  merely  consists  of  a  cistern,  the  bottom 
of  which  is  formed  by  fine  metal  sieves,  admitting  the  percolation  of  the  jnioe» 
the  damp  sugar  crystals  being  removed  from  the  cistern  and  placed  in  forms.  But 
the  most  effective  is  the  centrifugal  drier,  shown  in  Fig.  227,  the  invention  of  M. 
Fesca,  consisting  of  an  open  drum,  a,  of  fine  meshed  wire-work,  caused  to  revolve 
in  the  cast-iron  case,  bb,  hj  means  of  the  bevel-wheels,  cd,  gearing  with  a  motive 
power,  the  drum  making  1000  to  1500  revolutions  per  minute.  The  motion  of 
the  drum  can  be  stopped  by  means  of  the  break,  e,  and  regulated  by  the  weights  placed 
at  o.  The  sugar  containing  non-crystallised  juioe  is  poured  into  the  drum,  which  being  set 
in  revolution,  the  molasses  is,  by  centrifugal  force,  driven  through  the  sieve,  the  dry 
sugar  remaining  in  masses  of  60  to  100  pounds  weight.  The  action  of  the  machine  is 
aided  by  the  cone,  g.  By  means  of  this  apparatus,  a  hundredweight  of  sugar  can 
be  dried  in  ten  to  fifteen  minutes. 

BemoTim  the  saR»r  from      "When  all  the  syrup  has  been  removed,  the  bottom  of  the  loaf  in 
the  Form.  the  form  becomes  quite  dry  and  hard ;  the  loaf  is  now  loosened  in 

the  mould  by  means  of  a  long  knife,  so  that  when  the  mould  is  inverted,  the  sugar-loaf 
may  stand  by  itself  on  the  **  unloading  block,^'  as  the  bench  is  termed  where  this  opera- 
tion takes  place.  From  the  unloading  block  the  loaf  is  removed  to  the  drying  room, 
where,  first  at  a  temperature  of  25°  and  finidly  at  50°,  it  is  dried.  The  loaf  is  now  ready 
for  the  market  or  warehouse.  When  the  pure  juioe  is  evaporated  to  the  crystallising 
point,  the  small  granular  crystals  formed  upon  cooling  are  oommeroiaUy  known  as 
the  first  product ;  the  syrup  removed  still  contains  a  quantity^of  orystalliBable  sugar,  and 
is  further  evaporated,  the  result  being  known  as  tiie  second  product,  and  of  course 
considered  inferior  to  the  first.  In  the  same  way  a  third  and  a  fourth  product,  known  as 
after-products,  may  be  obtained.    On  an  average  100  kilos,  of  beet-root  yield : — 


CHEmCAL  TECHKOLOOT. 


First  pradnct  at  q-j  per  ce 


Foniih  prodnot.molaBsea,  Ae. . . 


And  ftgaiu,  the  sogara  of  each  refining  is  dietingnished  according  to  its  qnality,  Tit.,  U 
refined  sngar,  lamp  or  boiled  angar,  ci^staltiEed  si^ar,  rav  or  moist  sugar,  and  molasses. 
BMHuiiHH.  The  molasses  so  largely  formed  during  the  mannfa«ture  of  beet-root 
eagar  conteuns  most  of  the  foreign  substances— caram el.  salts,  aspartic  add— 
conunon  to  the  nane-sugar  molasses.  Beet  molasses  is  used  extensirely  for  sweeten- 
ing purposes,  for  (he  preparation  of  a  coarse  spirit,  and  in  many  parts  of  France 
and  Germany  aa  fodder  for  cattle.  The  quality  depends  on  the  mode  of  preparing 
the  beet.     loo  parts  of  molasses  contain  ; — 

Sugar    501  490  480  507 

Non-saccharine  matter       ...  333  358  -340  308 

"Water    ...     ; 166  15-2 


185 


loo'o 


BnitrCiDii;.  The  large,  bard  eiystlli 
formed  during  the  TBrions  stagCB  of 
BQgar  manafactilre,  are  known  as  siifBr- 
eond;.  The  oommercial  article  is  gene- 
ral!; obtained  from  cane  aogar.  tta« 
crTstola  of  beet-root  sugar  being  tc 
and  flat.  The  amomit  of  sugar 
made  from  beet  sugar  does  not  eieenl 
20  percent  of  the  entire  production.  The 
BDgar  selected  for  candy  is  mixed  nith 
3  to  4  per  oent  of  animal  charcosi, 
tbeu  cleared  viitb  white  of  egg,  aod 
Sltered.  It  is  neit  boiled  in  a  Aopper 
or  an  enamelled  iron  pan  otot  an  open 
fire  ;  whence  it  is  conveyed  to  a  cryatal- 
liaing  vesee),  the  sides  of  which  1* 
perforated  with  a  aeries  of  holes,  in  eight  or 
ten  concentric  rings,  the  distance belweea 
each  hole  laterally  being  leaa  than  Uut 
between  each  ring.  Through  these  bolM 
the  candy  cryatalliseB,  the  Blze  o(  IbA 
holee  being  adjueted  to  the  consistSDCJ  "' 
the  boiled  augor  by  meanE  of  a  paste 
made  of  fine  clay,  ashes,  and  ox-blood. 
The  temperature  of  the  diying  rooo 
is  maintained  at  75°  for  six  dnys,  when  il 
la  reduced  to  45'  or  50°,  and  in  8  to  10 
days  the  cry stalli Ballon  la  complete.  During  the  cryi.taUisalion  the  candy  must  not  be  morrf 
or  shaken,  or  the  air  allowed  to  affect  it.  Upon  the  completion  of  the  cryBtallisation,  the 
candy  ia  found  covered  with  a  miitare  of  Kjmp  and  Email  ciyetala  ;  theee  are  removed  bj 
filling  the  cryatalliaing  vessel  with  weak  tinie.water.  The  rineing  water  must  be  lokenmi, 
as  cold  water  cractcB  the  crystals,  and  hot  wat«r  makes  them,  as  it  is  lechnicalt;  teniKd. 
blind.  The  crystolliBing  veasel,  when  emptied  of  the  rinfing  water,  is  soaked  lo  remo'e 
all  sacohaiine  matter,  and  if  this  bo  not  effected  with  hot  water,  a  amootb  t^tone  is  naed  lo 
knock  away  the  adhering  cryatnls.  After  atondlng  a.  day  to  dry,  the  sngor-caudy  ia  teaij 
for  the  market.  It  ia  commercially  known  as  of  three  kinda  :— the  finett,  rclined  white. 
has  a  large  colourless  crystal ;  } ^ilnw  cand^-,  b  straw-coloured  cijstnl ;  and  brown  conclj 
ia  similar  in  colour  to  ordinary  moist  augor.  In  some  parts  of  France  a  dark  ean^ 
ja  manufactured  under  the  name  of  Sucrt  de  Buerhaxe.    Inferior  cane  sugar  is  emplejM 


SUGAR,  3^ 

for  the  brown,  boiled  sugar  for  Che  yellow,  and  refined  sugar  for  the  white  candy.  Sugar- 
candy  is  extensively  used,  the  white  principally  in  preparing  *' Liqueur/'  a  solution 
of  candy  in  wine  or  cognac,  also  in  champagne  manufacture,  and  in  all  cases  where  a 
clear  sweetening  solution  is  required  in  large  quantities.  The  yellow  candy  is  used 
for  sweetening  tea  and  co£fee  in  restaurants,  and  enters  largely  into  the  recipes  of  the 
pharmaceutist  for  affections  of  the  throat  and  chest,*  as  well  as  for  making  syrupB 
intended  as  vehicles  for  nauseous  medicines. 

The  total  annual  production  of  beet-root  sugar  amounted  in  1870  to  16,000,000  cwts., 
of  which  6,000,000  cwts.  are  due  to  France. 

Grape  Sugar. 

oimpcsncar.  GrapB  sugET,  potato  Bugor,  starch  sugar,  glucose,  or  dextrose,  is 
a  sugar  crystallisable  with  difficulty,  occurring  in  a  non-ciystallised  state  as  levulose 
or  chylariose  (yvXapiov,  syrup)  in  many  sweet  fruits,  in  the  vegetable  kingdom,  and 
it  forms  the  solid  crystalline  portion  of  honey.  It  may  be  obtained  by  any  of  the 
following  processes : — 

a.  By  the  conversion  of  starch,  dextrine,  cane  sugar,  or  some  gums  by  means  of 

dilute  acids  or  diastase. 

b.  By  treating  cellulose  and  similar  vegetable  matter  with  dHute  acids. 

c.  By  decomposing  organic  substances,  such  as  amygdalin,  salicin,  phloridzin, 

populin,  quercitrin,   gallo-tannic  acid,  &c.,  that  by  ti'eatment  with  dilute 

acids  or  synaptase  (emulsin)  are  se][)arated  into  grape  sugar  and  other 

substances. 

Grape  sugar  is  found  in  the  various  fruits  in  the  following  quantities : — 

Per  cent. 

Peach 1*57 

Apricot 1*80 

Plum 2*12 

Baspberry 4*00 

Blackberry 4*44 

Btrawberry 573 

Bilberry    - 578 

Currant        6*10 

Plum 6*26 

Gooseberry 7*15 

Cranberry 7*45  (according  to  Fresenius). 

Pear      8-02  to  io-8  (E.  Wolff). 

Apple 8*37  (Fresenius). 

„      7-28  to  8-04  (E.  Wolff) 

Sour  cherry 877 

Mulberry      g-ig 

Bweet  cherry       1079 

Grape I4'93 

Grape  sugar,  C6Hi206,H20,  crystallises  from  its  aqueous  solution  in  granulsr, 

hemispherical,  warty  masses.    It  is  less  easily  soluble  in  water  than  cane  sugar, 

and   requires  li   of  its  own  weight  of  cold  water,  while   in  boiling  water  it  is 

soluble  in  all  proportions,  forming  a  syrup  possessing  but  poor  sweetening  qualities. 

There  are  required  2i  times  more  grape  sugar  tlian  cane  sugar  to  sweeten  the  same 

volume  of  water.    At  120''  grape  sugar  loses  its  water,  and  has  the  formula  CeHi^Oe. 

At  140^  it  is  converted  into  caramel.    Heated  witli  caustic  alkalies  mclassic  acid  is 

formed,  together  with  humus-like  substances.    Treated  with  sulphuric  acid,  grape 

sugar  forms  sulpho-saccliaric  acid,  and  with  common  salt  a  soluble  compound  of 

sweetish  saline  taste.    With  caustic  potash  in  excess  a  grape  sugar  solution,  when 

heated  to  the  boiling-point,  reduces  the  hydrate  of  oxide  of  copper  to  suboxide, 

oxide  of  silver  to  metallic  silver,  aud  chloride  of  gold  to  metallic  gold.    A  mixture  of 


3?4  CHEMICAL  TECHNOLOGY. 

ferridcyanide  of  potassimn  and  potash  with  the  aid  of  heat  decomposes  grape  sogar, 
and  discharges  the  original  yellow  colour  of  the  fluid.  Under  the  influence  of  & 
ferment  grape  sugar  sufiers  many  changes,  the  product  varying  with  the  ferment  and 
method  of  treatment  employed.  Beer  yeast  decomposes  grape  sugar  into  alcohol 
and  carhonic  acid. 
100  kilos,  of  grape  sugar  give : — 

Alcohol      51*11 

Carhonic  acid    ...    4889 

There  are  also  found  under  certain  conditions  of  temperature  and  concentndon 
the  homologues  of  alcohol,  viz.,  propylic  alcohol,  hutylic  alcohol,  and  amylic  alcohol, 
and  under  all  conditions  glycerine  and  small  quantities  of  succinic  and  lactic  acid& 
TVhen  fermentation  is  eflected  in  the  presence  of  alkaline  reagents,  lactic  acid  is  formed 
without  any  disengagement  of  gas.  Ordinarily  the  formation  of  lactic  acid  is  merely 
a  stage  in  the  process  of  conversion,  the  lactic  acid  decomposing  into  hutyric  snd 
acetic  acids  with  development  of  hydrogen.  Under  certain  conditions  mannito 
'  may  he  prepared  from  grape  sugar ;  several  other  gum-like  suhstances  may  also  be 
ohtained.  If  to  a  grape  sugar  solution  a  small  quantity  of  caseine  and  of  carbonate 
of  lime  he  added,  and  the  mixture  suhmitted  to  a  temperature  of  90^,  hutyrate  of 
lime  will  he  thrown  down  after  fermentation,  carhonic  and  hydrogen  gases  being 
continuously  evolved. 
PnpMmtion  of  onpe  sngu.      Grape  sugar  may  he  prepared  from : — 

a.  Grapes. 
h.  Starch. 

0.  Wood  and  similar  vegetahle  suhstances. 
"When  grape  sugar  is  prepared  from  the  grape,  the  juice  of  the  white  grape  is 
preferred,  and  set  aside  to  clear.  The  cleared  must  is  heated  to  the  hoiling-point  with 
pieces  of  marhle,  chalk  (not  with  burnt  lime),  or  witherite  (carbonate  of  baryta)  to 
neutralise  a  portion  of  the  tartaric  acid.  It  is  then  allowed  to  stand  for  twenty-four 
hours,  and  during  this  time  the  insoluble  salts  of  lime  are  deposited.  The  must  is 
now  cleared  with  ox  blood  in  the  proportion  of  2  to  3  litres  of  hlood  to  100  litres  of 
must,  and  next  evaporated  to  26**  B.  After  remaining  a  short  time  in  a  tub  to  clear, 
the  impurities  are  removed,  and  the  must  again  evaporated— this  time  to  34"  B. 
By  these  means  a  syrup  is  produced,  from  which  the  grape  sugar  can  be  imme- 
diately ohtained.  The  syrup  is  concentrated  by  hoiling  and  run  into  crystallising 
vessels,  where  after  three  to  four  weeks  the  sugar  crystallises  out ;  it  is  separated 
from  the  non-crystallised  chylariose  in  a  centrifugal  machine.  For  experimental 
purposes  the  crystals  may  he  separated  hy  placing  the  conc^iMsrated  syrup  on  t 
heated  porcelain  or  glass  plate. 

1000  parts  hy  weight  of  grapes  give : — 

Must 800 

Syrup  ... 200 

Baw  grape  sugar      ...     140 
Pure  grape  sugar      ...  60—70 
The  preparation  of  grape  sugar  from  starch  is  an  important  hranch  of  the  sogar- 
boiler^s  art.    Dilute  sulphuric  acid  and  the  fecula  of  potato  starch  are  the  active 
agents.    The  principal  processes  are  the  following : — 

a.  The  hoiling  of  the  starch-meal  with  dilute  sulphuric  acid  is  effected  on  a  small 
scale  in  leaden  pans,  but  in  an  extensive  preparation  iron  pans  are  employed.    The 


SUGAR,  385 

reqnisite  quantity  of  water  is  first  heated  to  the  boiling-point,  and  to  this  is  added 
the  sulphuric  acid  diluted  with  3  parts  by  weight  of  water.  The  starch  is  also 
previously  brought  by  the  addition  of  water  to  a  milky  consistency.  The  liquids  so 
prepared  are  mixed,  and  the  boiling  continued  until  all  the  starch  is  converted  into 
sugar.  An  intermediate  stage,  not  usually  noticed  by  the  manufacturer,  is  the 
conversion  of  the  starch  into  dextrine,  which  in  its  turn  suffers  conversion  into 
grape  sugar.  The  entire  conversion  of  the  dextrine  into  grape  sugar  cannot  be 
ascertained  with  certainty  by  the  iodine  test,  as  sometimes  a  purple-red  tint  is 
produced,  while  in  others  there  is  no  change.  The  most  reliable  test  is  that  with 
alcohol,  founded  on  the  known  insolubility  of  dextrine  in  an  alcoholic  menstruum.  To 
I  part* of  the  solution  to  be  tested  there  are  added  6  parts  of  absolute  alcohol;  if  no 
precipitate  is  thro"v\Ti  down  there  is  no  dextrine  remaining,  and  the  conversion  has 
been  entire.  The  proportions  of  the  materials  are  generally  to  100  kilos,  of  starch 
meal — 2  kilos,  of  ordinary  sulphuric  acid  of  60°  B.  and  300  to  400  litres  of  water. 

The  conversion  of  the  starch  into  grape  sugar  is  hastened  by  the  addition  of  a 
small  quantity  of  nitric  acid. 

b.  The  separation  of  the  sulphuric  acid  from  the  sugar  solution  is  a  most  important 
operation,  for  the  colour,  purity,  and  flavour  all  depend  upon  success  in  this  stage 
of  the  process.  The  acid  is  neutralised  by  bar}i»  or  by  lime,  with  either  of  which 
it  forms  an  insoluble  salt,  deposited  at  the  bottom  of  the  neutralisation  vessels,  and 
leaving  a  clear  supernatant  syrup.  The  baryta  can  be  employed  as  carbonate 
(witherite),  and  is  witliout  doubt  the  better  neutralising  agent,  sulphate  of  baryta 
being  very  insoluble.  Lime,  although  ordinarily  used,  forms  with  the  sulphuric  acid 
a  sulphate  (gypsum)  that  is  not  perfectly  insoluble  in  water.  It  can  be  employed 
either  as  marble,  chalk,  or  caustic  lime.  The  neutralisation  is  completed  in  the 
boiling-pan  while  the  sugar  solution  is  still  hot.  For  every  kilo,  of  sulphuric  acid 
(technical  atomic  weight  =  100  to  106)  so  much  pulverised  marble  (chemical  atomic 
weight  =  100)  is  required  as  the  varying  strength  of  the  acid  may  demand.  After 
the  addition  of  the  marble  powder,  and  when  the  effervescence  has  subsided,  the 
liquid  must  be  tested  with  litmus  paper,  or,  better,  with  tincture  of  litmus;  if 
the  sugar  solution  be  neutralised  when  at  26°  B.  density,  the  following  evaporation 
will  concentrate  even  the  smallest  quantity  of  sulphuric  acid  which  may  have 
remained,  and  render  another  neutralisation  necessary.  To  ensure  perfect  neutral- 
isation it  is  useful  to  add  an  excess  of  carbonate  of  baryta  in  the  proportion  of  250 
to  500  grms.  to  every  10  kilos,  of  sulphuric  acid. 

c.  Evaporating  and  Purifying  the  Sugar  Solution, — This  part  of  the  process  is 
accomplished  first  in  a  copper  pan  over  a  slow  fire,  or  better,  by  heating  with  steam. 
The  impurities  separate  and  are  absorbed  in  the  scum,  which  is  removed  by  means 
of  ladles.  The  evaporation  is  continued  until  the  syrup  marks  is**  to  16*'  B.,  when  it 
is  passed  through  a  filter,  generally  of  animal  charcoal.  It  is  then  removed  to  a 
large  reservoir,  and,  if  a  granular  sugar  be  desired,  evaporated  to  40*  to  41°  B.,  in  flat 
pans,  from  which  it  is  taken  to  be  placed  in  the  crystallising  vessels.  These  vessels 
are  provided  at  the  bottom  with  twelve  to  twenty-four  holes,  into  which  wooden  plugs 
are  fitted,  by  removing  which,  when  the  sugar  has  crystallised,  the  molasses  are 
removed.  The  crystals  are  dried,  sifted,  and  either  pressed  into  sugar-loaf  forms 
or  packed  in  casks.    The  crystallisation  is  effected  in  eight  to  ten  days. 

20 


3- 

4- 

5- 

67*2 

75*8 

622 

91 

90 

8-8 

200 

131 

246 

37 

21 

44 

386  CHEMICAL  TECHNOLOGY. 

The  manufacture  of  grape  sugar  from  wood  and  similar  vegetable  substances  is 
only  of  value  in  relation  to  the  production  of  spirits,  and  recently  as  a  by -process  of 
the  manufacture  of  paper  from  wood. 

oompoiiiioiiof  starehBt«ar.  The  compositiou  of  starch  sugar  as  it  occurs  in  commerce 
is  very  varied.  During  inferior  seasons  the  marketable  starch  sugar  may  con- 
tain 50  per  cent  sugar,  325  per  cent  foreign  substances,  and  17*5  per  cent  water. 
G.  Schwaendler  found  by  the  analysis  of  various  samples  of  last  year's  (1870)  sugar 
the  following  percentages : — 

I.  2. 

Grape  sugar    67*5  640 

Dextrine 90  174 

Water       19-5  11-5 

Foreign  substances 40  71 

1000         1000         1000        1000         lOO'O 

UMBof  onpeBoffar.  The  sugar  prepared  from  starch,  in  addition  to  the  sugar  yielded 
really  by  the  grape,  is  largely  employed  in  wine-making  and  in  the  brewing  of  beer.  In 
the  latter  case  the  grape  sugar  is  prepared  by  means  of  diastase ;  that  its  use  is  extensive 
may  be  gathered  from  the  fact  that  to  3  cwts.  of  malt  i  owt.  of  potato  sugar  is 
employed.  It  is  also  employed  instead  of  honey  in  confectionary,  for  colomring  liqnors 
and  vinegars  brown,  in  rum  and  cognac,  beer  and  wines.  In  the  latter  cases  it  isluiown  as 
siicre-cauUur,  being  then  a  grape  sugar  that  has  been  re-melted,  sometimes  with  the 
addition  of  carbonate  of 'soda  or  caustic  soda  to  deepen  the  colour. 

Fermentation. 

Fcnnenuuoii.  Fermentation  is  a  term  applied  to  the  peculiar  changes  of  complex 
organic  substances  of  the  amylaceous  and  saccharine  type  under  the  influence  of 
certain  putrescible  nitrogenous  substances  or  ferments.  The  decomposition  of 
fermentable  organic  bodies  by  a  ferment  effects  the  separation  of  their  constituents 
into  two  or  more  combinations,  as  when  by  a  yeast-ferment  dextrose  and  levulose 
are  converted  into  alcohol,  its  homologues,  and  carbonic  and  succinic  acids ;  or  the 
molecules  of  the  original  substance  are  re-grouped,  as  in  the  conversion  of  sugar  of 
milk  into  lactic  acid  during  lactic  acid  fermentation ;  finally,  the  elements  of  the 
organic  substance  may  enter  into  combination  with  the  oxygen  of  the  atmosphere 
either  to  form  new  organic  combinations,  or  to  separate  into  its  inorganic  constituents 
carbonic  acid,  carburctted  hydrogen,  &c.  This  latter  decomposition  is  termed 
moulderitig  when  a  residue  rich  in  carbon  (humus)  remains,  but  when  only  the 
mineral  constituents  remain,  decay  is  said  to  have  been  reached.  These  terms  are 
thus  defined  more  by  custom  or  usage  than  by  direct  etymology — dictionaries  hardly 
distinguish  between  them,  but  the  difference  is  known  to  all.  If  large  quantities  of 
water  be  present  both  these  processes  are  resolved  into  putrefaction ^  in  which  chiefly 
gases — carbonic  acid,  ammoniacal,  sulphuretted  hydrogen — and  water  are  disengaged. 
But  fermentation  always  results  in  the  remaining  or  the  formation  of  other  organic 
compounds,  and  the  variety  of  fermentation  set  up  mostly  depends  on  the  state  of 
decomposition  of  the  azotised  matter  employed  as  a  ferment.  The  most  important 
ferment  is  imdoubtedly  yeast,  but  tlie  ferment  may  be  either  an  organic  substance 
(yeast)  or  a  protein  body  in  a  putrescent  state — it  is  always  a  nitrogenised  body.  In 
a  technological  work  the  varieties  of  fermentation  may  be  classed  as — 

I.  Vinous  or  alcoholic  fermentation,  including  the  changes  observed  during  the 

processes   of  wine -making,  beer-brewing,  and  the  production  of  alcoholic 

liquors  or  spirits. 


FERMENTATION.  387 

2.  Lactic  acid  fermentation,  taking  place  during  the  souring  of  millc ;  and  at  a 

higher  tem]^erature  changing  to 

3.  Butyric  acid  fermentation. 

To  these  fermentations  may  be  added — 

4.  Putrescence,  noticeable  only  in  technological  chemistry  as  a  stage  to  be 

most  carefully  avoided. 

vinoiu  yenMBtotian.  Yinous  Or  alcoholic  fermentation  is  the  result  of  the  decomposi- 
tion of  saccharine  matter,  dextrose  or  glucose,  levulose  or  chylariose,  and  lactose 
into  several  products,  principally  alcohol  and  carbonic  acid.  According  to  the 
recent  researches  of  Lermer  and  Von  liebig  (1870)  dextrine  in  the  presence  of  sugar 
is  converted  into  equal  parts  of  alcohol  and  carbonic  acid.  This  will  be  seen  from 
the  following  table,  which  gives  the  result  for  100  parts  by  weight: — 

Alcohol.        Carbonic  Acid. 
Crystallised  dextrose,  C6H14O7,  4640  +  44'40  =    90'86. 

Anhydrous  dextrose,  CeHiaOe,  51  10  +  48*90  =  loooo 

Cane-sugar,  CiaHaaOn,        53'6o  +  5146  =  10526. 

Starch-meal.  C6H10O5,  5678  +  54'3a  =  mio. 

X  mol.  dextrose,  CaH„0«  =  x8o,  gives  {  ^  -J;  f^^^'^^S^O 


2 


=  92 

=  88 


180 

Kecentiy  Pasteur  has  shown  that  lactic  acid  does  not  result  from  alcoholic  fermen- 
tation, but  that  succinic  acid  is  a  constant  product  of  this  fermentation  in  quantities 
never  less  than  06  to  07  per  cent  of  the  weight  of  the  sugar  employed.  Glycerine 
is  another  constant  production  to  the  extent  of  3  per  cent  of  the  sugar;  this 
substance  occurs  in  all  wines.  The  5  to  6  per  cent  of  substances  remaining  may 
therefore  be  thus  divided : — 

Succinic  acid      06  to  07 

Glycerine 3*2  to  3*6 

Carbonic  acid     06  to  07 

Cellulose,  fatty  substances,  &c 12  to  15 

5'6  to  65 

tcml  The  nature  of  alcoholic  fermentation  was  first  investigated  by  Cagniard- 
liatour,  while  our  present  knowledge  is  due  chiefly  to  the  researches  of  A.  de  Bary, 
J.  Wiesner,  Hoffinan,  Bail,  Berkley,  Pasteur,  Hallier,  B6champ,  Lermer.  Yeast  on 
being  introduced  into  a  fermentable  fluid  rapidly  throws  out  fermenting  arms,  as 
it  were,  until  the  fluid  is  covered  with  a  superficial  ferment,  termed  in  German 
the  Oberhe/e,  while  at  the  bottom  of  the  vessel  a  viscid  sediment  is  deposited,  known 
in  German  as  the  Unterhefe.  The  oberhefe,  or  superficial  ferment,  is  employed 
as  harm  by  the  baker,  for  the  purpose  of  leavening  his  bread  ;  while  the  unterhefe  or 
sedimentary  ferment  is  that  employed  in  the  fermentation  of  wines  and  of  Bavarian 
beers  ;  these  beers  difier  from  the  general  beers  of  England,  France,  and  Germany,  in 
not  souring  by  exposure  to  air,  this  quality  being  due  to  the  peculiarity  in  the 
process  of  fermentation,  Untergahrung,  or  fermenting  from  below,  during  which  the 
gluten,  the  substance  absorbing  the  oxygen  of  the  air,  is  removed.  In  the  distilla- 
tion of  brandy,  the  yeast  employed  is  a  mixture  of  harm  and  bottom  yeast,  as  the 

2  0  2 


388  CHEMICAL  TECHNOLOGY. 

tenns  nm  in  this  country.  Fresh  yeast  appears  as  a  grey-yellow  or  red  firoth 
of  strong  odonr,  and  with  an  acid  reaction.  Under  the  microscope  the  two  kinds  of 
yeast  are  easily  distingnished.  Tlie  superficial  yeast  or  barm  consists  of  globular  or 
ellipsoidal  ceUs  of  equal  size,  and  about  o'oi  millimetre  diameter.  They  float  partly 
alone,  partly  in  groups  in  the  fluid.  The  walls  of  the  cells  are  so  transparent  that 
the  inner  cells  can  be  seen  through  the  upper.  In  the  centre  of  each  cell  appears  a 
dark  speck  or  grain,  the  protoplasma,  sometimes  consisting  of  more  than  one  grain. 
The  bottom  yeast  or  sedimentary  ferment  also  consists  of  cells,  but  these  do  not 
cling  together  so  tenaciously  as  the  cells  of  the  barm,  and  are  generally  isolated, 
while  the  adhesion  is  merely  mechanical  between  those  tliat  do  cling  together,  a 
slight  concussion  being  sufficient  to  eflect  their  separation.  Sometimes  a  large  cell  of 
the  bottom  yeast  contains  two,  three,  or  even  four  smaller  cells,  the  dimensions  of  these 
cells  varying  greatly,  and  not  being  nearly  so  constant  as  in  the  cells  of  the  barm, 

"  I  found,"  says  Dr.  Wagner,  "  from  the  researches  of  Mitscherlich,  communicated 
to  the  Philosophical  Faculty  of  the  Universiiy  of  Leipsig.  that  the  sprouting  or  trans- 
planting of  the  cells  had  been  actually  witnessed  under  the  microscope — ^that  a  parent 
cell  had  been  observed  to  put  forth  little  cells,  which  gradually  grew  in  size.  These 
observations  had  been  made  with  barm  or  superficial  yeast,  and  I  wished  to 
ascertain  if  the  cells  of  the  bottom  yeast  or  sedimentary  ferment  were  propagated  in 
the  same  manner.  For  this  purpose  I  placed  a  sedimentary  yeast-cell,  containing  a 
germ,  under  the  microscope  in  a  bath  of  concentrated  beer-worts.  The  temperature 
varied  between  7"  to  10°.  The  cell  remained  unaltered  for  some  time,  but  finally 
there  appeared  30  to  40  small  cells.  These  cells  were  either  separated  from  the 
mother-cell  by  the  bursting  of  tlie  cell  walls,  or  had  been  introduced  as  spawn  into 
the  field  of  the  microscope  in  the  beer- worts ;  which  was  the  true  case  the  microscope 
could  not  reveal,  for  no  separated  spawn  were  visible.  An  analysis  of  the  two 
yeasts  gave : — 

Barm.         Sedimentary  Teast 

Carbon      44*37  49'76 

Hydrogen 6*04  6'8o 

Nitrogen 9*20  9*17 

Oxygen,  sulphur,  and  ash     40*38  34*^6 

"  The  barm  contained  2*5  per  cent,  the  sedimentary  yeast  5*29  per  cent  of  asL 
The  amount  of  sulphur  was  0*5  to  o'S  per  cent.  The  ash  consisted  essentially  of 
potash,  phosphoric  acid,  silica,  and  magnesia." 

According  to  the  recent  researches  of  Liebig,  Pasteur,  Lemaire,  and  others, 
alcoholic  fermentation  is  essentially  due  to  the  formation  of  yeast  cells,  and  to  the 
development  of  organic  substances.  There  are  two  cases  to  be  considered.  Yeast 
with  its  botanical  names,  Saccharomyces  cerevisia,  or  Iformiscium  eerevisia,  a 
descendant  of  the  fungi,  PenidUium  glaucum,  Ascophora  Mucedo,  A.  elegans,  and 
Periconia  hyalina,  the  spawn  of  which  is  always  occurring  in  the  atmosphere,  ferments 
either  with  a  pure  sugar  solution,  without  the  existence  of  protein  substances,  or 
iu  the  presence  of  albuminous  substances.  The  latter  case  occurs  also  when 
a  solution  of  sugar  containirg  an  albuminous  body  is  so  situated  as  to  be  partially  or 
wholly  open  to  atmospheric  influence.  The  local  ferment  floating  in  the  air  in  the  sfas|w 
of  yeast-spawn  finds  in  this  solution  a  ready  agent  for  its  extension.  But  in  the  first 
case,  where  the  sugar  solution  is  mixed  with  the  yeast,  without  the  necessary 


FERMENTATION,  389 

protein  substance  as  food  or  nourishment  for  the  cells,  the  fermentation  is  after 
a  time  exhausted,  and  is  not  again  set  up.  It  is  for  a  similar  purpose  that  during 
the  process  of  brewing  the  yeast  cells  are  fed  with  a  substance  formed  in  the  germi- 
nation of  barley.  During  this  germination  the  gluten  of  the  seed  passes  over  into 
diastase,  of  all  nutriment  that  upon  which  the  yeast  cells  flourish  best. 

The  nature  of  the  yeast  cell  is  a  most  interesting  question.  It  is  more  nearly  allied  to 
the  animal  or  to  the  vegetable  kingdom  ?  The  line  of  demarcation  is  not  always  defi- 
nite, yet  there  would  appear  some  interesting  analogies  that  should  not  be  overlooked. 
"  Plants,"  says  Professor  Williamson,  "  build  up  complex  substances  from  simple. 
iVll  the  most  complex  substances  that  we  can  get  are  made  in  the  organisms  of 
plants.  They  may  have  been  taken  over  by  animals  from  plants,  but  they  are 
formed  in  the  main  by  plants.  And  the  cliief  chemical  activity  of  animals  is 
precisely  opposite;  they  take  those  complex  substances  and  break  tliem  down, 
by  means  of  their  vital  functions,  to  the  simple  products  which  are  exhaled  and 
given  off  in  the  processes  of  animal  life.  Therefore,  the  question  whether  the 
process  which  the  yeast  carries  on  is  a  synthetical  process — a  building  up — or  whether 
it  is  in  the  main  an  analytical  process,  is  certainly  one  of  tlie  most  important  wliich 
can  guide  us.  From  what  we  know  best  regarding  the  nature  of  the  yeast  cells,  the 
food  which  we  know  they  take  in  large  quantities,  and  upon  which  they  thrive, 
is  certainly  exceedingly  complex,  and  the  products  which  they  give  off  are  exceed- 
ingly simple  in  comparison.  Their  functions  are  in  the  mom  (those  which  we  know 
best  at  any  rate)  analogous  to  those  which  take  place  in  animal  organisms,  and 
are  most  remote  from  those  which  take  place  in  vegetable  organisms." 

Among  the  most  remarkable  decompositions  effected  with  the  aid  of  yeast  cells  are 
those  described  by  Liebig  in  a  recent  paper,  in  which  it  is  stated  that  yeast  cells  will 
assimilate  tartaric  acid,  malic  acid,  and  nitric  acid ;  tlie  latter  it  deprives  of  a  portion 
of  its  oxygen,  converting  it  to  nitrous  acid. 

CoDdktoiu  of  Ai«ohoUc  or      The  Conditions  of  alcoholic  fermentation  are  the  ^eral  conditions 
vinou*  Fennanuiiou.     ©f  t^e  vegetation  of  the  yeast  plant,  with  the  distinotion  that  by  vinous 
fermentation  the  largest  amount  of  alcohol  is  obtained.    The  foUowiiig  conditions  must 
be  fulfilled  when  alcoholic  fermentation  is  the  desideratum  : — 

1.  An  aqueous  solution  of  sugary  in  the  proportion  of  i  part  of  sugar  to  4  to  10  parts  of 
water.  The  sugar  can  be  employed  as  grape  sugar,  dextrose  or  levulose,  which  is  always 
capable  of  fermentation,  or  an  uiifermentable  sugar,  cane  sugar,  or  sugar  of  milk,  may  be 
converted  by  means  of  an  acid  or  suitable  agent  into  fermentable  sugar.  However 
gradual  the  process  may  seem,  cane  sugar  \s  always  converted  into  grape  sugar  before  fer- 
mentation sets  in. 

2.  The  presence  of  yeasty  or  spawn.  In  the  first  case,  i  part  of  yeast  to  5  parts  of  sugar 
is  sufficient  to  effect  a  strong  fermentation.  If  spawn  only  is  present,  there  must  also 
be  present  substances  upon  which  the  spawn  may  feed  or  develope— protein  substances, 
phosphoric  add,  humus,  and  alkalies.  If  no  ferment  exists,  the  only  other  condition 
under  which  fermentation  is  effected  is  by  exposure  to —  ' 

3.  The  atmosphere,  which  introduces  the  before-mentioned  ferment  and  furnishes  life. 

4.  A  known  temperature,  the  limits  of  which  are  5°  and  30°  C.  As  a  rule  vinous  fermen- 
tation is  effected  between  9°  and  25°.  The  lower  the  temperature  the  longer  the  time 
required  for  the  fermentation  to  subside,  and  conversely.  At  30"  and  at  higher  tempera- 
tures, the  vinous  fermentation  easily  goes  over  into  butyric  acid  fermentation.  The 
making  of  wines  is  based  on  a  practical  acquaintance  with  alcoholic  fermentation' ;  but 
in  this  case  only  a  portion  of  the  sugar  of  the  must  goes  over  into  alcohol  and  carbonic 
acid.    The  alcohol  remains,  while  the  greater  part  of  the  carbonic  acid  escapes. 

In  beer-brewing  the  substance  forming  alcohol  is  mostly  starch,  part  of  which  goes  over 
into  uhfermentable  dextrine,  but  the  greater  into  eas^y  fermentable  dextrose.  It  is 
arranged  that  the  beer  shall  hold  a  small  portion  of  the  dextrose  unchanged  until  the  after- 
fermentation  at  a  lower  temperature,  during  which  much  of  the  carbonic  acid  is  expelled » 
the  alcohol  remaining  in  the  beer. 


390  CHEMICAL  TECHNOLOGY. 

In  the  brewing  of  beer,  only  a  part  of  the  raw  material  or  starch  employed  goes  onrar 
into  dextrose,  and  finally  into  alcohol  and  carbonic  add;  bnt  in  the  manafaetare  of 
spiritnons  Uqnors  the  given  material — starch  or  sngar — ^is  converted  into  the  greatest 
possible  quantity  of  alcohol  in  the  shortest  time,  and  afterwards  separated  by  dis^lation. 
The  aim  of  the  wine  maker  is,  of  course,  to  produce  the  greatest  quantity  of  wine ;  of  tha 
brewer,  the  mftTimnm  amoxmt  of  beer ;  and  of  the  distiller,  the  largest  yield  of  spiiii. 
The  residue  from  the  distillation  of  spirits  is  often  employed  in  making  ooneentraied  food 
for  animals. 

In  the  baking  of  bread  and  confectionary  the  lightening  or  leavening  of  the  don^  is 
effected  by  alcoholic  fermentation,  but  only  the  carbonic  add,  and  not  the  aloobol,  ii 
of  use.  Li  the  foregoing  illustrations  of  the  application  of  fermentation,  it  will  have 
been  perceived  that  the  object  is  the  generation  of  alcohol  or  of  carbonic  add,  or  of  both, 
according  to  the  requirements  of  the  case.  The  particulars  we  will  consider  under 
separate  divisions. 

Wine-Makino. 

wioe.  By  the  name  of  wine  is  generally  distinguished  an  alcoholic  fluid  prepared 
without  distillation  by  the  fermentation  of  grape-juice.  In  the  widest  meaning 
of  the  term  is  included  the  result  of  the  vinous  fermentation  of  all  natural  juices. 

The  vine  Mid  ita  chiutbUoii.  The  vine,  ViHs  vinifera,  is  generally  cultivated  id  Europe  at 
a  temperature  of  50°,  while  the  best  and  ripest  drinking  wines  are  obtained  from 
grapes  grown  at  a  temperature  of  51°  to  52°.  It  requires  an  average  temperature  of 
lo"*  to  11^  fmd  an  average  summer  temperature  of  18^  to  7ff\  but  it  is  the  sunmer's 
sun  that  forms  the  sugar.  A  climate  with  severe  winters  and  hot  summers  is  therefore 
as  favourable  to  the  cultivation  of  the  grape  as  a  temperate  climate.  England,  with  a 
mean  average  annual  temperature  of  ii**,  is  consequently  very  unsuited  to  the  growth 
of  the  vine.  The  weather  has  the  greatest  influence  upon  the  vine :  during  the 
growth  rain  is  required,  but  during  the  ripening  only  the  sun's  rays  should  reach  tiie 
grape.  The  soil  is  not  so  much  a  matter  of  consequence  if  a  quantity  of  potash  be 
present ;  but  a  warm,  loose  soil  is  the  best.  Clay  shale,-  clay  marl,  gypsum,  lime* 
and  chalk  formations  are  very  suitable  to  the  vine.  The  uses  of  the  grape  an 
numerous  in  the  highest  degree ;  it  serves  chiefly  in  the  preparation  of  must  for 
wuie,  the  preparation  of  grape  sugar,  French  brandies  or  cognacs,  wine-vinegars,  be. 
Oil  is  prepared  from  the  seeds,  and  the  lees  are  burnt  for  their  potash. 

vinugtL  The  sugar  is  found  at  an  early  stage  of  the  growth  of  the  grape.  'When 
unripe  the  grape  contains  malic,  citric,  and  tartaric  acids,  bitartrate  of  potash  and 
lime,  organic  salts  in  smaller  proportions,  and  a  littie  colouring  and  extractive 
matters.  Successive  analyses  have  been  made  of  the  grape  during  its  period  of 
growth  by  0.  Neubauer,  from  samples  obtained  from  the  Neroherg,  near  ^esbaden 
(1868),  and  have  given  the  following  results : — 

0*6  per  cent  Sugar  and  27  per  cent  free  add. 


July  27th 

o*6 

August   9th  ... 

09 

„    17th ... 

2*3 

„    28th  ... 

8-2 

September   7th 

11-9 

17th 

18*4 

„        28th 

17-5 

October  5th   ... 

i6'9 

„      12th... 

i8'6 

„     22nd... 

17-9 

}»  }< 

l»  ♦» 

»»  »» 

J»  >♦ 

•»  » 

»»  »» 

»»  >» 

n  »» 


2'9 

a 

» 

2-8 

i9 

>t 

19 

» 

11 

1*2 

» 

>i 

095 

»> 

II 

0-8 

>f 

9\ 

08 

»> 

fl 

0-9 

»» 

>l 

09 

1* 

»> 

WINE.  391 

It  appears  that  the  riper  the  grape  the  more  sugar  it  contains,  and  it  produces  a 
wine  richer  in  alcohol,  so  that  the  grapes  are  never  gathered  until  perfectly  ripe.  The 
grapes  of  the  white  vine  are  of  a  brown-yellow  when  ready  for  gathering  for  wine, 
and  the  red  and  blue  grape  must  be  extremely  dark  before  the  seed  will  separate 
from  the  fleshy  part  of  the  grape  sufficiently  for  wine-making  purposes. 

The  grapes  are  sometimes  plucked,  and  sometimes  left  on  the  stalk.  The  separation 
of  the  grape  from  the  stalk  is  effected  either  by  hand  or  by  the  aid  of  a  hurdle,  the 
openings  between  the  bars  of  which  are  only  sufficiently  wide  to  admit  of  the  passage  of 
the  grape,  or  by  a  wooden  or  brass  trellis- work,  or  finally  with  a  large  wooden  fork  0*5  to 
o'6  metres  in  length.  The  stalk  contains  much  tannic  acid,  and  it  is  therefore  necessary 
that  all  the  grapes  should  be  thoroughly  separated  before  pressure ;  but  in  some  cases 
when  the  grape  contains  too  little  of  this  acid,  a  few  stalks  are  purposely  allowed  to 
remain. 

^"**^*gI1p!m.°'  *^    After  the  grapes  are  stripped  from  the  stalks,  they  are  placed  in  a 

vat  and  stamped  with  a  wooden  maul  or  pestle  to  express  the  juice.     They  are 

generally  allowed  to  remain  for  some  time,  and  afterwards  submitted  to  a  second 

bruising,  the  maceration  being  for  the  purpose  of  softening  the  skins  and  fleshy  part 

of  the  grape.    The  whole  of  the  juice  and  grape-skins,  or  marc,  is  then  put  into  a 

butt  with  perforated  sides,  through  which  the  must  trickles  into  the  fermentation  vat 

beneath.    If  a  white  wine  is  being  operated  upon,  to  prevent  it  becoming  stringy ,  as 

the  term  runs,  from  an  insufficient  supply  of  tannic  acid,  small  quantities  of  stalks 

are  added  from  time  to  time.     This  addition  renders  the  wine  more  easily  clarified 

by  the  addition  of  white  of  egg  or  isinglass  in  a  subsequent  stage  of  the  process.  While 

the  wine  is  in  the  vat,  the  fermentation  is  allowed  to  proceed,  and  the  slight  acidity 

generated  reacts  upon  the  colouring  matter  and  aromatic  constituents  of  the  grape, 

these  being  taken  up  in  the  alcohol  set  free. 

The  wine-presses  are  of  very  various  construction.  The  most  general  is  the  beam-press, 
roughly  constructed  with  a  pole  12  to  16  metres  in  length,  and  four  to  six  oaken  cross  beams. 
These  presses  have  considerable  power,  but  they  are  tedious  to  work,  and  soon  get  dirty. 
The  lever-press  is  more  efficacious,  and  is  made  in  many  forms,  the  pressure  being  mostly 
from  below.  The  hurdle-  or  sledge-press  is  of  the  rudest  kind,  consisting  merely  of 
hurdles  and  rough  heavy  stones.  The  best  presses  are  the  screw-presses  made  of  wood 
or  cast-iron.  100  parts  of  grapes  yield  60  to  70  parts  of  mnstj  The  ripest  grapes  yield 
the  first  juice  in  the  press ;  the  results  of  stronger  pressure  are  more  acid.  The  result  of 
the  first  pressure  is  termed  the  wine  or  the  first  wine ;  then  comes  the  press  wines ;  and 
finally  the  after  wines.  The  residue  or  marc  is  sometimes  treated  with  water  to  obtain 
an  inferior  wine. 

The  Centrifugal  MMhine.      In    1862   Stcinbeis,  of  Stuttgart,  with   the  eo-operation  of 

Reihlen,    endeavoured  to  express  the  juice  of  the  grape  with   the    aid  of  the 

centrifugal  machine  instead  of  the  press.     They  were  enabled  in  ten  minutes  to 

express  the  juice  perfectly  from  100  to  120  pounds  of  grapes,  including  the  time 

required  to  fill  and  empty  the  machine.    In  1869,  Ballard  and  Alcan  obtained  equally 

successful  results,  some  of  which  were  made  comparative  with  those  obtained  by  a 

good  press : — 

Centrifugal  Machine.  Press. 

Must      79' 141  77086 

Residue 20*214  18*601 

Loss      0*645  4*3^3 

lOO'OOO  lOO'OOO 

^Tif^'MaS!**"**  Besides  the  stalk  of  the  grape,  there  are  the  outside  skin,  the 
hull,  the  seeds,  and  the  juice.  Of  the  composition  of  all  these  substances,  with  the 
exception  of  the  grape  juice,  our  knowledge  is  very  deficient.    Besides  cellulose, 


392  CHEMICAL  TECHNOLOGY. 

the  stalks  contain  mnch  tannic  add,  and  an  acid  very  sour  to  the  taste.  The  hull  of 
the  grape  contains  the  colouring  matter  and  a  small  quantity  of  tannic  acid.  The 
seed  contains  a  peculiar  acid,  oBnanthic  acid,  and  an  ether,  bearing  the  same  name, 
to  which  the  bouquet  of  the  wine  is  due. 

"**  ^S*?'  *^  ^^®  ^^^  grap«  contains  more  sugar  than  any  other  kind  of  grape. 
The  quantity  of  sugar — a  mixture  of  dextrose  and  levulose— is  seldom  less  thn 
12  per  cent,  while  it  is  sometimes  as  much  as  26  to  30  per  cent.  The  proportion  of 
add  to  sugar  is  in  good  years  and  in  a  good  grape,  according  to  Fresenius,  i :  29; 
in  average  years  and  cases,  1:16;  and  when  the  proportion  is  only  as  i  :  10,  the 
grapes  are  useless  for  the  production  of  wine.  The  proportion  between  the  add  and 
sugar  in  wine-must  from  the  same  kind  of  grape  for  different  years  is,  aecordiDg  to 
thin  eminent  chemist : — 


In  a  very  inferior  year,  1847,  as  i  :  12 
In  a  better  year,  1854,  „  i  :  16 

In  a  good  year,  1848,  „  i  :  24 


During  the  fermentation  of  the  must,  bitartrate  of  potash  is  deposited,  and  from 
this  source  most  of  the  tartar  of  commerce  is  obtained.  This  salt  is  insoluble  in 
dilute  alcohol ;  consequently  as  the  sugar  changes  into  alcohol  it  is  thrown  down. 
It  is  from  the  fiict  of  containing  tartaric  acid,  which,  by  combining  to  form  an 
insoluble  salt,  is  thus  prevented  exerting  an  unfavourable  influence  on  the  wine,  that 
grapes  possess  so  much  the  property  in  proportion  to  other  fruits  of  making  a  good 
wine.  The  malic  and  citric  acids  contained  in  currants  and  gooseberries  cannot  be 
withdrawn  in  this  manner :  hence  the  addition  of  sugar  to  wines  made  from  these 
fruits  to  veil  the  acidity ;  the  addition,  however,  giving  rise  to  the  danger  of  a  second 
fermentation,  and  consequent  acidity.  According  to  AL  Classen,  i  kilo,  of  ripe  grapes 
gave  (in  1868)  577  to  688  grms.  of  juice ;  and  i  litre  of  juice  contained: — 

Water  ... ...      860  to  830  grms. 

Sugar  (dextrose  and  levulose) 150  „  300    „ 

Pectin,    gums,    extractive    matter,' 
Protein  substances,  organic  adds,  - 
and  mineral  matters    ... ^ 


30  »>    20 


i9 


1040 to  1 150 

1000  parts  of  juice  of  ripe  (Ehine,  1868)  grapes  contained : — 

I.                 2.  3. 

Solid  matter    164*4           189*7  2046 

Sugar      149*9           162*4  1740 

Free  add 7*2               6*8  4*8 

Ash ...        2*7               3'o  4'o 

In  100  parts  of  the  ash  were  contained : — 

I.                2.  3. 

Phosphoric  add     i6'6             i6'i  14*0 

Potash     ...      642             66*3  71*4 

Magnesia 4-7               28  2*6 


WINE.  393 

C.  Neubauer  (1868)  analysed  two  kinds  of  grapes,  and  fonnd — 

Keroberger  Steinberger 

(large  grapes.)     (selected  grapes.) 

Sugar    i8'o6  24*24 

Free  acid      042  043 

Albuminous  substances      ...  0*22  01 8 

Mineral  constituents  (potash,  \  ^  ^ 

phosporic  acid,  &c.) (  ^'  ^^ 

Combined  organic  acids  and i  ^^^ 

extractiye  matter    J  ^  ^^ 

Total  of  soluble  constituents        23*28  29*22 

Water    7672  70*78 

K)000  lOO'OO 

^^  'SSSxSS.**'  ****  ^®  fermentation  of  the  grape  juice  is  spontaneous;  that  is,  it 
is  consequent  upon  the  exposure  of  the  grape  juice  to  the  atmosphere,  without  the 
addition  of  jeast  The  albuminous  matter  of  the  must  forms,  under  the  influence 
of  the  atmospheric  spawn  or  yeast  germ,  the  well-known  fangus  PenicUUum  glaucum, 
or  yeast  cells.  The  fermentation  begins  at  a  temperature  of  10  to  15^  and  is  effected 
more  or  less  rapidly  according  to  the  temperature.  Too  low  a  temperature  will 
retard  the  progress  of  fermentation,  as  also  will  the  addition  of  sulphurous  acid ; 
the  same  effect  is  obtained  by  the  addition  of  other  sulphur  compounds,  as,  for 
instance,  the  essential  oil  of  mustard,  which  contains  sulphocyanide  of  allyl.  The 
must  is  left  in  open  vats ;  bubbles  of  carbonic  acid  soon  appear,  scum  collects  upon  the 
surface  of  the  juice,  and  an  alcoholic  odour  pervades  the  wine  at  this  stage.  About 
the  seventh  day  the  fermentation  commences  to  decrease,  and  about  the  tenth  or 
fourteenth  day  the  fluid  begins  to  clear,  no  more  carbonic  acid  or  scum  appearing.  The 
yeast  cells  formed  are  carefully  removed  from  the  bottom  of  the  vessel,  and  the  wine  run 
into  casks,  where  it  undergoes  a  slight  after-fermentation.  If  there  be  much  sugar  con- 
tained in  the  grape,  and  a  small  quantity  of  azotised  matter,  the  resulting  wine  will  be 
sweet ;  but  if  the  proportion  of  sugar  be  small  and  albumen  large,  a  dry  wine  is  the  result. 

'^^"'*°*d2  Wail'*'***  After  the  principal  fermentation  the  greater  part  of  the  sugar 
of  the  must  is  found  to  be  separated  into  alcohol  and  carbonic  acid.  There  is  still 
likely  to  arise,  unless  the  temperature  be  considerably  decreased,  a  fresh  fermenta- 
tion, known  as  the  after-fermentation.  Should  this  after-fermentation  continue  too 
long,  vinegar  is  formed,  and  to  prevent  this,  the  wine,  after  the  disappearance  of  the 
bubbles  of  carbonic  acid  upon  the  conclusion  of  the  principal  fermentation,  is  at 
once  "  spigotted  off"  from  the  lees  into  casks,  the  object  being  to  cut  off  communica- 
tion with  the  atmosphere  as  much  as  possible.  The  casks  are  nearly  filled,  and  are 
bunged  loosely,  being  filled  completely  a  day  or  two  after.  Wines  casked  in  Decem- 
ber will  often  continue  fermenting  till  February  or  March.  Strong  wines  rich  in 
alcohol  can  be  kept  in  cask  until  they  have  become  quite  dear ;  but  weak  wines 
most  be  soon  bottled,  as  the  oxygen  of  the  air  is  liable  to  convert  the  hydrate  of  the 
oxide  of  ethyl  or  alcohol  into  trioxide  of  acetyl  or  vinegar. 

coutttnaiiu  of  wino.  Constituents  that  were  not  found  in  the  n^ust  axe  characteristic  of 
the  wine — the  chief  of  these  is  alcohol.  Succinic  acid  and  glycerine,  the  constant 
products  with  alcohol  and  carbonic  acid  of  vinous  fermentation,  are  also  to  be  found. 
A  "dry*'  wine,  such  as  the  French  and  Rhenish  wines,  is  one  in  which  all  the  sugar 
has  been  decomposed ;  a  ''  sweet "  wine,  on  the  other  hand,  is  one  in  which  some 
sugar  has  remained  undeconiposed  either  from  an  insufficiency  of  albuminous  matter 


394  CHEMICAL  TECHNOLOGY. 

to  nourish  tlie  yeast  cells,  or  from  the  checking  of  the  fermentation  by  exposure  to  a 
low  temperature.  A  very  sweet  and  thickly  fluid  wine  is  termed  a  "  liqueur."  Thfi 
difference  in  colour  is  due  to  three  substances — a  blue  colouring  matter,  a  brown 
colouring  matter,  and  tartaric  acid.  The  brown  colouring  matter  is  present  in  all 
light  or  white  wines,  while  the  blue  colouring  matter,  found  in  the  skins  of  purple  or 
black  grapes,  is  in  the  wine  a  red  colour,  the  change  arising  from  the  contact  with 
the  tartaric  acid.  Wines  of  the  first  year  after  growth  are  termed  new  or  "green'' 
wines.    The  average  composition  of  wines,  in  looo  parts,  is  the  following : — 

Water . .     900 — ^891 

Alcohol* 80 — ^70 

Homologues  of  alcohol  (propylic,  butylic  alcohol)*        . .  ^ 

Ethers  (acetic,  oenanthic)* , 

Essential  oils , 

Grape  sugar  (dextrose  and  levulose)  .  .• , 

Glycerine*       

Gums       

Pectin      

Colouring  and  fatty  substances \-  20 — 30 

Protein  bodies 

Carbonic  acid*       

Tartaric  and  racemic  acids 

Malic  acid 

Tannic  acid 

Acetic  acid* 

Lactic  acid  (?)*      

Saccinic  acid*        

Inorganic  salts       

Those  substances  marked  (*)  are  formed  during  the  principal  fermentation. 

The  quantity  of  alcohol  contained  in  a  wine  is  due  partly  to  the  quantity  of  sugar  and 
partly  to  the  quantity  of  albuminous  matter  contained  in  the  must.    It  is  dhiefly  ethylie 
or  ordinary  alcohol.     The  specific  weight  of  the  wine  gives  only   approximately  the 
alcoholic  contents  ;  a  better  method  of  estimation  is  by  means  of  an  alcoholometer.    Of 
these  instruments,  Geissler's  Vaporimeter  is,  perhaps,  one  of  the  best,  in  which  the 
pressure  exerted  by  the  vapour  of  the  wine  upon  a  column  of  mercury  gives  a  measure 
of  the  alcohol  contained.      The  vapour  of  absolute  alcohol  at  a  temperature  of  78*3* 
exerts  a  tension  equal  to  that  exerted  by  aqueous  vapour  at  100°.    It  is  therefore  only 
necessary  to  ascertain  the  height  of  the  column  of  mercury  and  the  temperature  to 
arrive  at  the  quantity  of  alcohol.     The  apparatus  is  shown  in  Fig.  238,  and  consistB 
essentially  of  four  purts,  viz: — i.  A  brass  vessel,  a,  half  filled  with  water,  heated  bv 
means  of  the  lamp  to  the  boilmg-point.    2.  A  bent  glass  tube,  b,  to  wbioh  a  wooden  scale 
is  fixed.    3.  A  cylindrical  glass  vessel,  o,  filled  with  mercury  and  the  wine  to  be  tested. 
4.  A  cylinder  of  sheet  brass,  in  the  upper  part  of  which  a  thermometer,  t,  is  fixed.    The 
glass  vessel,  o,  is  filled  with  mercury  to  the  mark,  a,  and  then  completely  filled  with  the 
liquid  to  be  tested.    The  boiling- vessel  is  now  affixed,  the  brass  cylinder  drawn  over  the 
mercury  tube,  and  the  thermometer  inserted.    Heat  is  applied,  and  the  water  raised  to 
the  boiling-pouit ;  the  steam  ascends  into  the  brass  oyhnder,  and  heats  the  wine  and 
mercury  to  the  boiling-point  of  water.      The  wine  expands,  and  is  partly  vaponaed, 
forcing  the  mercury  up  the  arm,  b,  which  has  been  previously  graduated  by  experiments 
with  fluids  of  known  alcoholic  contents ;  the  mercury  of  course  rises  the  higher  the  moro 
alcohol  there  is  contained  in  the  wine.     The  variable  constituents   of  the  wine,  the 
extractive  matter,  &o.,  do  not  influence  the  result.    The  carbonic  acid  must  have  been 
removed  previoudy  by  filtering  the  wine  through  freshly  burnt  Ume.    Equally  good,  U 
not  better,  results  are,  however,  to   be  obtamed  by  the  distillation  test,  effected  by 
distilling  10  o.c.  of  the  wine,  and  adding  to  the  distillate  sufficient  water  to  make  a  totsi 
of  10  e.o.,  the  specific  weight  of  the  fluid  giving  the  aloohoHc  contents  of  the  wind.   Tb6 
alcoholometer  most  generally  employed  is  the  EhuUioscope  of  Tabari^,  Fig.  229.    Wiih 
the  barometer  at  760  m.m.  water  boils  at  +100**,  and  alcohol  at  +78*3*  C.    The  nearer 
therefore  the  boiling-point  of  the  fluid  tested  approaches  78*3**,  the  greater  the  aloohoiie 
oontents.  The  wine  is  poured  into  the  vessel,  0,  and  the  oover,  e  h,  replaced.  The  fluid  ie 
heated  by  means  of  the  lamp,  l,  and  the  steam  ascends  round  the  thermometer,  1 1*,  the 
height  of  the  mercury  of  whioh  when  the  fluid  boils  varies  inversely  as  the  aloohoiie  oontents 


oftfaawiiws  tested.  ThavBuel,  mh',  is  ftDed  with  «old  water  to  huten  the  oondenututn 
«f  th«  vAponn.  II  tb«  boilinit-pomt  of  pure  water  be  takea  at  99-4°  C,  Uie  foUowiug 
boiling-poiiitB  aboir  the  qoantit;  of  aloobol  oontained  :- 


96*4°  C.  3  per  cent  alcohol. 


[°  C.    g  pw  cent  alooboi 


935   . 
919   . 


88-S   , 
88-4    „   14 


Bed  Freneb  wines  contuu  9  (o  14  percentage  b;  Tolnme  of  aloohol ;  Btugnndy,  9,  10, 
And  II  per  cent;  BoideaTii,  10,  11,  and  ll  percent.  Other  French  wines  contain  8  to  10 
peroent;  the  winea  of  the  Palatinate,  7  to  9*5  per  cen6;  Hnngarian  wines,  9  to  11  per 
«ent.  Champagne  coDtaina  9  to  11  per  cent;  Xerea,  17  per  cent;  Madeira,  17  to  23-7 
per  oent.  Acide  eiiat  in  all  wines,  and  are  generally  carbonic,  anccinic,  tartaric,  malie, 
and  Koetio  adda ;  these  acids  ate  found  partly  free,  piutly  combined  as  Bslte ;  tartaria 

FlQ.  KSS. 


Kcid,  tot  instance,  aa  erenor  tartari,  bitartrate  of  potash,  and  other  acid  tartrates.  Fanr£ 
found  an  essential  gmn,  which  he  termed  cenantbin,  and  which  with  glycerin e^flrat 
■hown  by  Paitenr  in  iSsgto  be  a  normal  constitnent  of  wine— helps  to  give  a  certain  eon- 
■iateney  to  the  wine.  Fohl  fonnd  (1863)  in  Anetrian  wines  1-6  per  oent  glycerine.  As 
wine  agM  the  glycerine  disappears.     The  oolonring  matter  of  wine  is  of  interest  in  the 


19 
tl 


396  CHEMICAL  'TECHNOLOGY. 

case  of  red  wines  only,  as  the  yellow-brown  coloor  of  some  wines  is  nndonbtedly  due  to 
oxidised  extraotive  matter.  The  coloming  matter  of  red  wines  has  receiyed  from  Mulder 
and  Maomen^  the  name  of  osnooyan,  while  it  is  commonly  termed  vfine-blue  ;  it  is  a  bind- 
substanoe  similar  to  litmus,  possessing  the  property  of  turning  red  in  the  presence  of 
acids.  It  is  insoluble  in  water,  alcohol,  ether,  oUve  oil,  and  oil  of  turpentine ;  but  soluble 
in  alcohol  containing  small  quantities  of  tartaric  or  acetic  acid.  Witii  a  trace  of  aoetie 
acid  the  solution  is  practically  blue,  turning  red  upon  the  addition  of  more  add; 
neutralised  with  alkalies  the  solution  remains  blue.  On  the  evaporation  of  a  wine  to 
dryness  the  extractiye  matter  remains,  consisting  of  a  mixture  of  non- volatile  adds,  tlii 
salts  of  organic  and  inorganic  acids,  with  osnanthin,  colouring  matter,  sugar,  protem 
substances,  and  extractive  matter,  the  nature  of  which  is  unknown.  The  quantity  of 
extractive  matter  differs  greatly,  varying  with  the  kind  of  wine  and  the  degree  of  fermen- 
tation of  the  sugar.  Fresenius  found  in  Bhine  wines  a  maximum  of  10-6,  and  a  minimnm 
of  4*2  per  cent  of  extractives  ;  Fischem,  in  the  wines  of  the  Palatinate,  icy  to  1*9  per 
cent ;  in  Bohemian  wines,  2*26 ;  in  Austrian,  2*64 ;  In  Hungarian,  2*62  per  cent.  The 
mineral  constituents  of  wines  exist  in  but  sniall  quantities — ^as  an  average  in  old 
Maderia  to  0-25  per  cent ;  in  old  Bhine  wines,  0*12  per  cent ;  and  in  old  ports,  0*235  per 
cent.    Van  Gockom,  Yeltmann,  and  Mosmann  found  in  1000  parts  of  wine : — 

Madeira 2-55  parts  of  ash. 

Teneriffe      . .     . .     . .  2'gi      „        „ 

Bhine  wine 1*93      ,,        „ 

Port      2-35      „        „ 

Pohl  estimated  the  following  number  of  parts  ash  in  100  parts  of  wine : — 

Bohemian    ..     ..  1*97  parts.  Slavonian     ..     ..  1*91  parts. 

Croatian      ..     ..  1*68    „  Styrian 1*63     „ 

Craniola       ..     ..  i'8i     „  Tyrol 1-84 

Lower  Austrian  . .  2*00    „  Hungarian  . .     . .  1*80 

The  ash  contains  potash,  lime,  magnesia,  soda,  sulphuric  acid,  and  phosphoric  aeid. 
The  "  Handworterbuch  der  Beinen  und  Angewandt^n  Chemie"  (B.  ix.,  Seite  676),  gives 
the  following  analyses  of  wine-ash,  the  first  four  being  by  Crasso,  and  the  fifth  bj 
Boussingault : — 

I.  2.  3.  4.  5. 

Ash  (per  cent) 0*26  0*34  0*41  0*29  0*18 

Potash 65-5  63-9  71*3  62-0  45-0 

Soda o*3  o*4  1-2  2*6  — 

Lime 5*2  3*4  3-4  5-1  4-9 

Magnesia 3-3  47  4*0  4-0  9-2 

Oxide  of  iron 0'7  0*4  o*i  0*4  — 

Oxide  of  manganese . .     ..     ..  0*8  07  ci  0*3  — 

Phosphoric  acid 15*4  i6'6  14*1  17-0  22*1 

Sulphuric  acid    ..     ..     ..     ..  5*2  5*5  3*6  4*9  5*1 

Silica 2'o  2*1  1*2  2*2  0*3 

Chloride  of  potassium      . .     . .  1*5  2*1  1*0  1*5  — 

Carbonic  acid     —  ,  —  -r-  —  13-3 

lOO'O  100*0  lOO'O  lOO'O  100*0 

The  bouquet  of  wines  or  their  peculiar  odour  is  due  to  oenanthic  ether  mixed  with 
the  alcohol.  According  toC.  Neubauer  {**  Chemie  des  Weines; "  Wiesbaden,  1870,  Seit^97)t 
this  oenanthic  ether  is  a  combination  of  various  substances,  of  which  caprylic  and  caproie 
acid  ethers  are  the  most  important,  and  is  a  product  of  the  fermentation  of  the  mast. 
During  the  fermentation  of  the  sugar  there  are  formed,  besides  ordinary  alcohol,  propylie 
and  butylic  alcohols,  and  succinic  acid  as  a  constant  product,  while  in  the  juice  of  the 
grape  there  occur  tartaric,  malic,  and  racemio  acids ;  these  with  acetic,  propionic,  and 
butyric  acids,  and  the  aldehydes  of  these  acids,  together  with  the  oil  of  the  seed  of  the 
grape  (oleic  and  palmitic  acids),  cannot  but  greatly  influence  the  bouquet  of  the  wine, 
which  of  course  will  vary  according  to  the  proportion  of  these  constituent^ 

Haiadtes  of  Wines.      Wlues  are    subject  to  various  causes   of  deterioration,  tenned 

maladies,  distempers,  or  diseases.     That  most  commonly  occurring  is  rcpineu  or 

viscidity y  the  cause  of  which  was  for  a  long  time  unknown.     Francois  showed  Uiat 

it  was  due  to  the  decomposition  of  the  glucose  into  azotised  matter  and  mannite. 


WIN3.  397 

and  at  the  same  time  indicated  the  proper  remedy,  the  addition  of  tannic  acid.  He 
employs  15  grms.  of  tannin  to  230  litres  of  wine.  This  is  well  mixed  with  tlie  wine, 
which  is  allowed  to  stand  for  a  few  days.  At  the  end  of  this  time  tlie  tannin  will 
have  separated  the  azotised  matter,  and  the  wine  may  be  bottled  off. 

The  touring  of  wine  is  due  to  the  conversion  of  the  alcohol  into  acetic  acid,  caused, 
according  to  Pasteur,  by  the  formation  of  the  vinegar  plant  or  MycoiUrnia  aeeti, 
which  he  found  in  all  sour  wines.  This  disease  is  very  common,  and  may  result 
from  too  small  a  proportion  of  alcohol,  too  high  a  temperature  of  the  cellars,  or 
exposure  to  the  atmosphere.  The  wine,  if  too  far  soured,  is  fit  only  for  making 
vinegar ;  but  slight  cases  can  be  remedied  by  an  addition  of  sngar.  The  formation 
of  vinegar  may  be  somewhat  delayed  by  impregnating  the  wine  with  sulphurous 
acid.  In  some  cases  the  acetic  acid  may,  by  the  addition  of  tartaric  acid,  be  removed 
as  acetic  ether ;  but  the  acetic  acid  can  never  be  neutralised  with  alkalies,  as  the 
salts  formed  are  very  easily  soluble. 

The  bittering  of  wine,  or  its  acquirement  of  a  bitter  flavour,  is  due  to  another 
eanse,  the  formation  of  a  bitter  substance,  which  developes  as  the  wine  ages,  or  at 
too  high  a  temperature.     Maumen6  suggests  as  a  remedy  the  addition  of  slaked 
lime  in  the  proportion  of  025  to  0*50  grm.  per  litre.    Bittering  is  due  also  to  the 
formation  of  brown  aldehyde  resin.    Mould  in  wines  appears  as  a  white  vegetable 
(fungus)   film  covering  the  surface,  and  arises  from  an  insufficiency  of  alcohol ; 
consequently  weak  wines  are   more  subject  to  this  malady.     The  film  of  mould 
should  be  removed  and  the  wine  used  as  soon  as  possible,  for  wine  affected  with 
this  disease  soon  turns  sour.    The  decaying  of  a  wine  is  dne  to  the  dissipation  of 
the  alcohol  and  the  decomposition  of  the  acids  of  the  wine ;  the  wdne  obtains  an 
astringent  taste,  and  a  dim,  thick  colour,  finally  turning  sour.     The  bitartrate  of 
potash  is  converted  into  carbonate  of  potash,  affecting  the  colouring  matter  and 
tannic  acid,  which  pass  over  into  humus  substances.    At  the  commencement  of 
this  decomposition  a  remedy  may  be  found  in  the  addition  of  a  small  quantity  of 
sulphuric  ether.     Caskiness,  or  the  taste  of  the  cask,  due  to  an  essential  oil  formed 
in  casks  that  have  long  stood  empty,  is  best  removed  by  the  addition  to  the  wine  of 
a  small  quantity  of  olive  oil  and  agitation ;  the  olive  oil  absorbs  the  essential  oil, 
and  brings  it  to  the  surface  of  the  wine,  whence  the  oily  matter  may  be  skimmed,  or 
the  wine  may  be  filtered  through  freshly  burnt  charcoal.    All  casks  and  vessels  that 
have  stood  long  empty  should  be  well  steamed  before  use. 

A<«iiic ^dcoa^uon  jhc  Pasteuring,.  a  term  which  usage  has  substituted  for 
X^asteurisation,  or  the  conservation  and  artificial  ageing  of  wines,  according  to 
Pasteur's  method,  is  a  great  improvement  in  the  general  treatment  of  wines  to  ensure 
their  keeping.  It  consists  essentially  in  heating  the  wine  to  60^  C,  and  for  this 
purpose  the  apparatus  designed  by  Kossignol  is  best  suited.  A  metal  cask,  t, 
Fig.  230,  contains  at  the  bottom  a  copper  vessel,  c,  with  a  trumpet-shaped  cover 
extending  in  the  open  tube,  c,  above  the  top  of  the  vessel,  t.  t  is  a  thermometer. 
Water  is  poured  into  the  vessel,  c,  until  tlie  tube,  c,  is  three  parts  full.  The  wine 
is  placed  in  th€  metal  cask,  t,  and  by  means  of  tlie  tap,  r,  and  the  tube,/,  run  off  into 
the  cask,  f,  when  sufficiently  heated.  The  water  in  tlie  copper  vessel,  c,  is  employed 
to  prevent  the  direct  heating  by  the  flame  of  the  vessel  containing  the  wine,  and 
the  consequent  burning  of  any  insoluble  matter  settling  to  the  bottom  of  the  vessel. 
Fig.  231  shows  in  detail  the  manner  of  fastening  the  vessels  together.  A  copper 
ring,  a,  encircles  the  vessel,  t,  and  beds  with  the  walls  of  this  vessel  into  tlie 


398  CBEMICdL  -TECHNOLOaT. 

india-rubber  band,  d,  into  which  it  is  pressed  b;  the  tightening  of  the  bclta,  t, 
binding  the  ring  of  angle-iron  and  lower  iron  ring.  b.  together.  The  joint  is  thnt 
rendered  water-tight.  The  vessel,  t.  is  not  quite  filled  with  wine  to  allow  tor 
eipanaion  under  heat ;  by  this  means  the  wine  is  exposed  to  a  known  quantity  ct 
aix.    Wine  should  not  be  artificially  aged  in  contact  with  tur,  as  Pasteur  has  prored 


that  such  processes  deteriorate  ths  colour  and  the  flaTonr  of  the  wine;  and  m 
ordinary  cases,  where  part  of  the  process  of  ageing  consiata  in  heating  the  winM 
for  a  short  time  in  an  open  vessel  with  a  full  exposure  to  air,  the  wine  acquires  ■ 
peculiar  boiled  flavour,  gout  de  cuit,  easily  recognisable  by  the  connoisseur.  Br 
Pasteor'a  method,  however,  neither  the  flavour  nor  colour  of  the  wine  ia  deteriortied; 
indeed,  the  latter  is  improved  by  the  expulsion  of  tlie  carbonic  arid. 

Pasteur  has  shown  tliat  most  of  the  diseases  of  wine,  acetification,  ropin««, 
bitterness,  and  decay  or  decomposition,  are  due  to  the  growth  of  different  fa- 
uents,  consisting  of  minute  vegetable  ceUs  always  esistiug  in  wines,  and  becomiiig 
active  and  destimctive  under  certiiin  conditions,  such  as  cliange  of  temperalore 
and  oxidation.  He  recommends  ("  Comptes  Rendus,"  May  ist,  2gfh;  August  Hti- 
1865),  that  these  plants  or  fungi  should  be  killed,  as  the  best  means  of  ensuring  the 
keepiag  of  the  wine,  and  the  particular  nioilm  opfrandi  selected  is  essentially  tl>« 
following,  differing  considerably  from  the  foregoing  method.  The  bottles  are  qnite 
filled,  the  wine  touching  the  cork,  wliich  is  inserted  n-ith  such  a  degree  of  fimines« 
that  the  wine  in  expanding  may  force  tiie  cork  out  a  litlJe,  but  ^at  bo  much  M 
to  admit  air  into  the  bottle.  The  botties  are  then  placed  in  a  chamber  heated  to 
45°  to  loo",  where  they  remain  for  an  hour  or  two.  after  which  they  are  removed,  srt 
aside  to  cool,  and  the  cork  driven  in.  By  this  means  the  life  or  active  principle  of 
the  fungi  is  destroyed,  while  the  wine  acquires  an  increased  bouquet,  ia  of  a  mow 
beautifol  colour,  and,  in  fact,  is  to  a  considerable  extent  aged.  Both  new  and  old 
wines  can  be  thus  treated. 


WINE,  399 

*"**'*^wiJ?*^  ***•  Most  wines  are  self-clearing,  the  ferment  settling  to  the  bottom 
of  the  cask,  and  leaving  the  wine  clear  and  pnre.  This  applies  chiefly  to  dry  wines 
which  haye  less  sugar  than  sweet  wines.  The  sweet  wines  are  generally  more 
thickly  fluid  on  account  of  the  quantity  of  sugar  they  contain,  and  consequently 
more  frequently  need  clearing.  Fining,  as  it  is  sometimes  called,  or  clearing, 
consists  in  adding  to  the  muddy  wine  some  albuminous  or  similar  substance  that  will 
mix  with  the  suspended  matter  and  carry  it  to  the  bottom  or  bring  it  to  the  sur- 
face of  the  wine.  The  substances  most  generally  employed  are  white  of  egg,  ox- 
blood,  and  milk,  or  mixtures  of  these  substances.  Liming,  or  the  addition  of 
gypsum,  is  for  the  purpose  of  heightening  the  colour,  chiefly  of  red  wines ;  further, 
it  converts  the  soluble  potash  salts  of  the  wine  into  insoluble  lime-salts  and  sulphate 
of  potash. 

The  BMidnaor  WkRte  The  waste  of  wine-making  consists  of  the  stems,  hnsks,  and  seeds  of 
of  wine-making,  the  grapes,  as  well  as  of  the  f ermentary  sediment  and  tartar.  Both 
descriptions  of  waste  find  niuneroas  applications.  The  lees  left  from  the  pressing  of  the 
wine  contain  a  not  unimportant  quantity  of  must,  which  (i)  is  employed  in  preparing  an 
inferior  wine.  2.  In  the  making  of  an  inferior  brandy.  3.  In  the  preparation  of  ver- 
digris (see  p.  58).  4.  In  vinegar  making,  and  for  promoting  the  formation  of 
vinegar  from  saccharine  or  alcoholic  fluids.  5.  In  wine-making  countries  the  lees  are 
much  employed  as  fodder  for  horses,  mules,  and  sheep.  While  (6)  the  residue  of  the 
after-pressing  or  final  pressing  is  used  as  manure.  7.  The  grape  seed  yields  an  oil 
in  quantities  of  10  to  11  per  cent ;  or  (8)  tannic  acid  in  large  quantities.  The  oil  can  be 
extracted  by  pressure  or  by  treatment  with  benzole,  or  with  sulphide  of  carbon.  The 
tannin  obtained  can  be  employed  for  the  preservation  of  hides,  &o.  9.  Potash  is  prepared 
from  the  calcined  lees.  10.  The  stalks  and  seeds  when  oaljuned  are  employed  in 
the  preparation  of  a  black  colouring  material  (vine  black).  11.  The  ferment  and  stalks 
are  in  some  wine-producing  countries^  besides  being  employed  in  the  preparation  of  tartar 
and  potash,  also  used  in  the  distillation  of  a  peculiarly  rich  brandy,  in  which  an  oil 
is  found  possessing  highly  the  "flavour  of  cognac,  and  known  in  commerce  as  wine  oil, 
cognac  oU,  huile  de  marc,  12.  Crude  tartar  is  found  with  tartrate  of  lime,  colouring 
matter,  and  yeast,  forming  a  more  or  less  thick  crust  on  the  walls  of  the  wine  cask  or  in 
the  crust  deposited  in  the  wine,  but  not  firmly  attached  to  the  vesuel,  and  is  the  chief 
source  of  the  pharmaceutical  bitartrate  of  potash  (C4H5KO6),  and  tartaric  acid. 

iflsTTctdBg  Wines.      Efliorvescing  wines  have  been  known  for  many  centuries.    Some  of 

Rembrandt's  paintings  exhibit  among  the  accessories,  a  champagne  glass  with 

effervescing  wine.    And  from  Virgil — 

"  Ille  implger  hausit, 
Spumantem  pateram — " 
it  would  appear  that  tliis  description  of  wine  was  known  to  the  Romans.    In  1870, 
there  were  in  Germany  fifty  producers  of  efiervescing  wines,  with  a  production 
of  2 i  to  3 i  millions  of  bottles.  li  millions  of  which  were  exported.    In  France  the 
production  amounts  yearly  to  16  to  18  millions  of  bottles. 

All  wines  are  capable  of  being  produced  as  efiervescing  wines  if  bottled  before  the 
fermentation  is  over.  By  bottling  at  this  period  the  carbonic  acid  is  retained  in  the 
wine,  and  when  the  bottle  is  opened  the  disengagement  of  tliis  gas  causes  the  appear- 
ance of  efiervescence.  In  this  country  the  efiervescing  wine  most  generally  known 
is  champagne ;  but  Hocks,  MoseUes,  and  even  red  wines  are  very  admirable  when 
thus  treated.  If  the  wines  contain  much  sugar,  the  fermentation  is  arrested  in  the 
bottle  before  all  the  sugar  is  consumed,  producing  a  sweet  effervescing  wine.  On 
the  other  hand,  if  the  sugar  is  all  exhausted  in  producing  the  carbonic  acid, 
the  result  is  a  dry  efiervescing  wine.  These  wines  are  very  agreeable  to 
the  palate,  and  may  be  supposed  to  assist  the  digestion  of  the  food  with  which  they 
ve  taken ;  but  when  new,  they  are  dangerous  as  being  likely  to  communicate  their 
state  of  change  to  the  contents  of  the  stomach,  interfering  seriously  with  digestion, 


400  CHEMICAL    TECHNOLOGY. 

and  producing  what  is  well  known  as  "  acidity."  Dry  effervescing  wines  arc  lest 
likely  to  disagree  than  sweet  wines  of  this  class  containing  much  sngar  and 
fermentable  matter.  The  connoisseur  places  great  reliance  in  his  judgment  of  a 
champagne  upon  tlie  loudness,  or  rather  sharpness,  of  the  report  when  the  eork 
is  drawn,  and  upon  the  "  bead"  or  bubble  formed  on  the  side  of  the  glass  by  the  car- 
bonic acid  gas.  These  effects  are  not  proportionate,  for  while  a  loud  report  resalta 
from  an  extended  fermentation,  a  good  bead  may  be  obtained  with  a  very  weak  fer- 
mentation. The  gas  in  a  bottle  of  champagne  exerts  a  pressure  of  some  five 
atmospheres,  and  it  will  at  once  be  evident  that  if  the  bottle  be  made  a  littls 
smaller,  reducing  the  space  between  the  cork  and  the  wine  only  one-twentieth, 
a  considerable  increase  in  loudness  of  the  report  will  ensue. 

The  process  of  manufacturing  effervescing  wines  is  in  general  the  following : — ^The 
best  grapes  are  used  for  this  purpose ;  for  champagne,  the  black  grape,  called  by  the 
French  noirien:  is  employed.      The  juice  is  expressed  from  the  grape  as  soon 
after  gathering  as  possible,  in  order  to  prevent  the  colouring  matter  of  the  skin 
affecting  the  wine ;  wliile  the  fruit  is  pressed  as  quickly  and  as  lightly  as  possiUe. 
The  juice  from  the  second  and  third  pressings  is  reserved  for  inferior,  or  red- tinted 
effervescing  wines.    The  expressed  juice  is  immediately  poured  into  tuns  or  vats, 
where  it  is  left  to  stand  for  twenty -four  to  thirty-six  hours.    In  tliis  time  any  earthy 
matter  or  vegetable  impurities  will  have  settled,  and  the  juice  is  ready  to  be  trans- 
ferred to  the  fermenting  vats,  where  it  remains  for  about  fifteen  days.    It  is  then  put 
into  casks,  which  are  securely  bunged ;  sometimes  brandy  is  added  in  the  proportion 
of  one  bottle  to  one  hundred  bottles  of  juice  or  must.   Towards  the  end  of  December, 
the  wine  is  fined  with  isinglass,  and  a  second  time  in  the  ensuing  February.     About 
the  beginning  of  April  the  clear  wine  is  fit  for  bottling.    It  now  contains,  if  a  good 
wine,  1 6  to  1 8  grms.  of  sugar,  ii  to  I2  per  cent  of  the  volume  of  alcohol  per  botde, 
and  an  equivalent  to  3  to  5  grms.  of  sulphuric  acid  in  free  acids. 

Great  care  is  necessary  in  the  manufacture  of  champagne  bottles ;  they  must  be 
free  from  flaws,  and  made  of  pure  materials.  Generally  each  bottle  is  from  850  to 
900  grms.  in  weight,  and  equal  in  thickness  throughout.  Formerly  the  flawed  botdes 
amounted  to  15  to  25  per  cent,  but  recent  improvements  in  manufacture  have  reduced 
the  percentage  to  10.  Before  the  wine  is  introduced,  the  bottle  is  rinsed  with  a 
liqueur  of  white  sugar-candy  150  kilos.,  wine  125  litres,  cognac  10  litres,  the  liqueor 
being  allowed  to  remain  in  the  bottle :  according  to  F.  Mohr  the  cane  sugar  of  tha 
liqueur  becomes  converted  into  grape  sugar  in  the  champagne.  It  is  doubtful 
whether  glycerine  might  not  be  advantageously  substituted  for  a  portion  of  the  sugar 
of  the  liqueur.  The  liqueur  employed  varies  with  the  flavour  of  the  wine :  port, 
Madeira,  essence  of  muscatels,  cherry  water,  &c.,  are  used,  but  rarely  unmixed  with 
some  other  favourite  solution  of  the  manufacturer,  as,  for  instance,  \i'ater  60  litres, 
saturated  solution  of  alum  20  litres,  tartaric  acid  solution  40  litres,  tannin  solutioii 
80  Utres.  About  2  litres  of  this  mixture  would  in  practice  be  added  to  a  butt  of 
wine.  The  bottles  are  filled  by  women,  the  proportion  of  liqueur  introduced  being 
about  15  to  16  per  cent  of  the  wine.  A  space  of  about  2  to  3  inches  is  left  between  the 
wine  and  the  cork,  which,  after  being  thoroughly  moistened,  is  next  inserted  by  a 
machine.  The  bottle  is  then  passed  to  a  man,  termed  in  the  French  establishments 
the  maiUocher,  who  drives  the  cork  home  with  a  mallet.  Another  process,  now  gene- 
rally effected  by  tlie  aid  of  a  machine,  is  the  "  wiring,"  or  securing  the  cork  with 
wire  or  string.  The  bottles  are  now  conveyed  to  the  cellar,  where  they  are  laid  in 
horizontal  racks  against  the  wall.    In  about  eight  or  ten  days  a  deposit,  termed 


CHEMICAL  TECHNOLOGY.  402 

**  griffe,**  is  formed,  and  shows  that  the  time  has  arrived  for  the  wine  to  be  transferred 

to  the  cellar,  where  it  is  to  remain  until  sold  to  the  merchant.   The  deposit  is  allowed 

to  form  daring  the  summer,  and  in  the  ensuing  winter  means  are  taken  for  its 

removal     The  bottles  are  well  shaken,  and  placed  with  their  mouths  downwards,  to 

cause  the  deposit  to  settle  on  the  cork.    The  cork  being  removed,  the  sediment  falls 

out,  when  more  liqueur  is  added,  and  the  bottle  re-corked  and  again  wired.    The 

bottle  is  now  laid  upon  its  side  at  an  angle  of  about  20°,  and  in  about  eight  to  ten 

days  the  inclination  is  gradually  increased  imtil  the  vertical  position  is  attained, 

when,  by  a  dexterous  movement  of  the  cork,  the  gas  is  permitted  to  force  out  the 

remaining  sediment.    This  process  is  repeated  as  many  times  as  may  be  necessary, 

until  the  wine  is  perfectly  clear.    Wine  thus  prepared,  generally  known  as  sparkling 

wine,  vin  mousaeux,  is  ready  for  the  consumer  at  the  end  of  18  to  30  months,  the  time 

varying  with  the  temperature  of  the  season.     One  of  the  greatest  causes  of  loss  is 

the  bursting  of  the  bottles,  sometimes  as  much  as  30  per  cent  of  the  wine  being 

wasted.    This  in  some  measure  accounts  for  the  deamess  of  these  wines. 

By  the  analysis  of  several  sparkling  wines  (1867  and  1870)  the  following  results 

were  obtained ; — 

I.  2.  3.  4«  5*  ^« 

Permille.  Permille.  Permille.  Fermille.  Fermille.  Fermille. 


Free  acid 

...    5300 

5'9«> 

7*6oo 

7800 

6*200 

5600 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Alcohol     

...    8'400 

9500 

8700 

8400 

9800 

8400 

Sugar        

...      8'200 

4300 

7*900 

9*100 

7500 

5400 

Extractive  matter 

...  ii'6oo 

7500 

10*300 

12000 

ii*6oo 

15*200 

Specific  gravity 

...     1036 

I  029 

1039 

I '046 

1039 

1*041 

I.  Prom  Chalons.  3  and  4.  Prom  Wirtzburg.  2.  From  the  same  place,  but  intended 
for  export  to  India ;  3  being  the  manufacture  of  J.  Oppman,  and  4  of  Silligmuller,  both 
well-known  German  firms.  5.  Prom  Sutaine  and  Co.,  of  Bheims.  6.  From  a  well-known 
Ehenish  firm,  glycerine  being  substituted  for  a  portion  of  the  sugar. 

"*  wEJTmJ^  ""  ^®  worth  or  character  of  a  wine  is  determined  by  its  aroma 
and  the  amount  of  alcohol  and  free  acid  contained— decreasing  with  an  increase  of  the 
latter,  and  increasing  with  increase  of  the  former.  The  proportion  between  the 
chief  constituents  of  the  grape-juice,  sugar,  acid,  and  water,  is  nearly  equal  in  aQ 
good  wines,  and  this  proportion  is  never  accidental,  but  always  belongs  to  a  good 
wine.  The  grapes  not  fitted  for  making  good  wines  are  treated  in  two  ways :  either 
the  expressed  juice  is  allowed  to  ferment  as  it  is,  in  which  case  an  inferior  wine  is 
obtained ;  or,  by  the  study  of  chemical  analyses  of  good  wines,  the  incomplete  con- 
stituents are  supplied,  and  others  injurious  to  the  wine  removed,  to  make  tlie  must  of 
that  quality  which  will  yield  a  good  wine.  The  following  are  the  best  methods  of 
improving  the  must : — 

1.  The  addition  of  sugar  to  wine  poor  in  this  constituent,  and  the  neutralisation  of 
an  excess  of  acid  by  means  of  pulverised  marble  (Chaptal's  method).  /n^m 

2.  The  addition  of  sugar  and  water  to  must  poor  in  sugar  and  rich  in  amd  (Gall  s 
method). 

3.  Bepeatedly  fermenting  the  husks  with  sugar-water  (Petiot's  method). 

4-  Removing  the  water  by  means  of  freezing,  or  by  treatment  with  gypsum. 

5.  Removing  the  acid  by  means  of  a  chemical  reaction. 

6.  Addition  of  alcohol  to  poor  wines. 

7-  Treating  the  prepared  wine  with  glycerine  (Scheele's  method). 

The  addition  of  sugar  to  must  poor  in  this  constituent  is  the  oldest  method  of  improve- 
nient,  and  appears  to  have  been  known  to  the  Greeks  and  Romans.    At  that  time  cane 

2  D 


402  CHEMICAL  TECHNOLOGY. 

sugar  waB  nnknown,  honey  being  osed  for  sweetening  purposes,  and  which,  being  added'to 
the  wine,  gave  it  a  peculiar  flavour,  and  rendering  it  thick.  In  years  when  honey  was 
scarce,  we  are  informed  that  the  wine  was  inferior.  Chaptal,  in  1800,  wrote  a  work  on  the 
cultivation  of  the  grape,  in  which  he  gives  a  recipe  for  adding  sugar  to  an  inferior  must 
to  render  the  wine  equal  to  that  of  better  years,  the  acid  being  neutralised  with  pieces  of 
marble.  In  Burgundies,  Ghaptal's  method  is  not  much  required  to  be  used,  as  these  winas 
rarely  contain  more  than  6  parts  per  1000  of  free  add.  The  amount  of  pulverised 
marble  (carbonate  of  lime)  required  to  neutralise  60  parts  of  free  acid  is,  as  a  rule, 
50  parts ;  and  the  amount  of  sugar  to  be  added,  when  the  acid  is  in  excess,  is  100  parti 
for  each  50  parts  of  alcohol  required  after  fermentation,  it  being  found  that  15  per  cent 
of  sugar  in  the  must  produces  7*5  per  cent  of  alcohol  in  the  prepared  wine.  Thu, 
should  it  be  desired  to  heighten  the  alcoholic  contents  from  7*5  to  10  per  cent,  to  ereiy 
1000  kilos,  of  must  are  added  50  kilos,  of  sugar. 

The  cause  generally  of  the  poorness  of  the  must  in  sugar  is  a  wet  or  cloudy  season, 
during  which  there  has  been  but  little  warmth  from  the  sun  to  ripen  the  grapes.  Most 
German  wines  show,  besides  a  lack  of  sugar,  a  superabundance  of  acid,  malic  and  tartsrie 
acids ;  and  while  the  addition  of  a  sugar  solution  increases  the  alcoholic  contents,  it  does 
not  remove  these  acids,  which  impart  a  flavour  to  the  wine  and  lessen  its  worth.  The 
addition  of  a  saccharine  solution  does  not,  as  might  be  expected,  enfeeble  the  bouquet  of 
the  wine,  if  pure  starch  sugar,  containing  no  dextrine,  be  employed.  The  use  of  impure 
starch  sugar  causes  a  quantity  of  unfermented  matter  to  remain  in  the  wine,  imparting 
to  it  a  tendency  to  decay.  Gall's  method  is  found  to  be  economical,  as  a  flavouring  mateml 
can  be  added  to  very  inferior  must.    According  to  Gall  a  normal  must  should  consist  of— 

Sugar      24*0  per  cent. 

Free  add        . .     . .       0*6 
Water     75*4 


1 


ft 


lOO'O  „ 

1000  kilos,  of  such  a  must  contain,  therefore,  240  kilos,  of  sugar,  6  kilos,  of  free  sdd, 
and  75*4  litres  of  water.  If,  by  analysis,  the  must  to  be  improved  yields  only  167  per 
cent  sugar  and  0*8  per  cent  acid,  there  are  to  be  added — 

153  kilos,  of  sugar,  and 
180    „      or  litres  of  water, 

by  which  addition  1333  kilos,  of  normid  must  are  obtained,  corresponding  to  an  increase 
in  quantity  of  33  per  cent ;  while  in  some  years,  when  the  acid  contents  are  as  much  u 
12  to  14  per  cent,  the  increase  in  quantity  rises  to  100  to  115  per  cent,  but  seldom  moi*. 

Petiot  based  his  method  on  the  fact  that,  according  to  the  usual*  process  of  preparing 
the  must,  the  colouring  and  bouquet  constituents  remaining  in  the  marc  are  snffident  to 
give  the  flavour  and  odour  of  wine  to  a  lixivium  of  sugar-water.  This  method  may, 
tiierefore,  very  justly  be  considered  as  yielding  a  wine  without  the  aid  of  grape-juice.  To 
the  marc  left  after  the  expressure  of  the  grape- juice  cold  water  is  added,  equal  in  quantity 
to  the  must  removed  :  in  this  water  the  marc  is  allowed  to  macerate  for  2  to  3  days.  Tbe  • 
water  takes  up  the  various  soluble  constituents  of  the  marc ;  after  the  time  specified  the 
liquor  is  removed,  and  the  amount  of  sugar  and  acid  it  contains  ascertained.  There  is 
usually  only  2  to  3  per  cent  of  sugar,  consequently  an  addition  of  17  to  18  per  cent  most 
be  made ;  and  if  there  should  be  too  Utile  acid,  tartaric  add  must  be  added  to  approximate 
the  acid  contents  of  a  normal  must.  The  artificial  must,  as  it  may  be  considered,  is  then 
put  into  the  fermenting  vat,  while  the  marc  is  again  treated  in  a  similar  manner,  a  longer 
immersion  being  this  time  required.  The  resulting  wines  are  darker  in  colour  than  wises 
prepared  from  the  natural  must,  in  consequence  of  a  larger  proportion  of  tannin.  The 
flavouring  of  these  wines  is  a  matter  of  experience,  and  does  not  fall  under  any  chemicsl 
consideration. 

Freezing  is  employed  in  the  improvement  of  wine,  for  the  purpose  of  reducing  the 
aqueous  contents.  According  to  the  experiments  of  Vergnette-Lamotte  and  Bousaingaah, 
the  effect  of  cold  upon  wine  is  of  a  very  complicated  nature.  By  cooling  the  wine  at  a 
temperature  of  0-6°  there  first  occurs  the  predpitation  of  those  substances  that  are  inso- 
luble at  this  temperature.  These  consist  of  cream  of  tartar,  oolouring  matter,  and  nitro- 
genous substances,  and  a  fluid  possessing  the  property  of  becoming  solid  at  6°.  'When 
these  substances  are  removed  the  wine  becomes  more  ardent,  richer  in  alcohol,  and  its 
peculiar  merit  is  that  it  is  not  liable  to  after-fermentation,  and  can  be  kept  in  vats  and 
half-empty  casks.  The  removal  of  the  acid  from  wine  is  effected  best  by  means  of  car- 
bonate of  lime  (pulverised  marble,  chalk),  sugar  of  lime,  or  neutral  tartrate  of~potash. 
An  addition  of  carbonate  of  lime  to  the  must,  or  to  the  wine,  is  not  detrimental,  in  so  fir 
that  the  wine  retains  none,  or  a  very  small  quantity,  of  the  lime-salt.  Carbonate  of  lime 
will  not  be  of  service  in  the  case  of  so-called  acid  fermentation,  as  acetate  of  lime  will 


BEER.  403 

then  be  formed,  and  the  wine  is  no  longer  worthy  the  name.  Liebig  recommends  the  use 
of  neutral  tartrate  of  potash  for  this  purpose,  as  bitartrate  of  potash  is  formed,  which 
settles  as  an  insoluble  salt  to  the  sides  of  the  vessel  or  bottle.  The  use  of  this  neutral- 
ising agent  has  the  merit,  moreover,  of  not  injuring  -the  flavour  and  odour  of  the  wine. 
Sugar  of  lime  can  be  employed  in  the  case  of  wines  not  containing  acetic  acid.  To  pre- 
pare the  sugar  of  lime,  slaked  lime  is  diluted  with  ten  times  the  quantity  of  water,  to  form 
a  thin  cream.  This  cream  is  thinned  with  sufficient  water  to  obtain  a  milk  of  lime,  in 
which  sugar-candy  is  dissolved.  The  solution  is  left  to  stand,  and  the  clear  supernatant 
liquor — a  solution  of  sugar  of  lime — decanted  to  mix  with  the  wine  as  required.  When 
the  wine  is  treated  with  the  sugar  of  lime  solution,  the  lime  forms  with  the  acid  of  the 
wine  an  insoluble  salt,  which  is  precipitated,  while  the  sugar  remains  in  the  wine. 

Another  addition  to  wine,  hardly  bearing  upon  its  improvement,  but  effected  as  a  means 
for  its  preservation  during  removal  or  exportation,  is  that  known  in  France  as  the  vinage, 
a  certain  quantity  of  brandy  being  mixed  with  the  prepared  wine.  When  the  wine  is  to  be 
exported  from  France,  the  law  permits  the  addition  of  5  litres  of  brandy  to  each  hecto- 
litre of  wine,  provided  the  alcoholic  contents  after  the  addition  do  not  exceed  21  per  cent. 
But  experiments  have  proved  that  the  wine  delivered  to  private  consumers  does  not  on  the 
average  contain  more  than  10  to  11  per  cent  of  alcohol,  while  the  wine  delivered  to  retail 
firms  averages  16  to  17,  and  to  wholesale  firms  22  to  24  per  cent.  To  prevent  this  fraudu- 
lent proceeding,  the  operation  of  vinage  is  permitted  only  in  the  Departments  of  the 
Pyrdn^es  Orientales,  Aude,  H^'ault,  Garde  Bouches  du  Bhone,  and  Var,  immediately  under 
the  inspection  of  the  Commissioners  appointed  to  this  duty.  In  1865,  Scheele  introduced 
his  method  of  improving  wine  by  the  addition  of  glycerine,  the  addition  l>eing  made  after  the 
first  fermentation  has  subsided.  The  limits  of  the  addition  lie  between  i  to  3  litres  of 
glycerine  to  i  hectolitre  of  wine.    But  the  expense  will  not  permit  of  extended  operations. 

Beeb  Brewing. 
Beer.  Beer  is  a  well  known  liquor  obtained  from  germinated  grain — chiefly  barley 
and  wheat,  sometimes  from  rice,  maize,  potatoes,  and  starch  sugar-^and  hops,  by 
means  of  a  yeast  fermentation,  but  without  distillation  of  any  kind.  It  contains  the 
constituents  of  the  grain  employed,  which  constituents  by  decomposition  form 
dextrose,  dextrine,  and  albuminous  substances,  alcohol,  carbonic  acid,  small  quanti- 
ties of  succinic  acid  and  glycerine,  organic  matter,  with  phosphates  of  the  alkalies 
and  alkaline  earths,  besides  the  constituents  of  the  hops. 

In  Bavaria,  the  Schenk,  or  pot  beer,  is  brewed  in  the  winter,  and  the  Lager,  or  ttore 
beer,  in  the  summer.  The  winter  beer  is  brewed  during  October  to  April,  when  the 
highest  range  of  the  thermometer  is  12°  to  13°.  A  part  of  the  beer  by  a  short  storing  is 
set  aside  for  winter  consumption,  while  the  remainder  is  used  during  the  summer  months. 

I  volume  of  malt  gives  on  an  average  2*5  to  2*6  volumes  of  winter  beer. 
I  „  „  „  2*0  to  2*1        „  summer  beer. 

In  some  of  the  North  (German  States,  potato-sugar  and  syrup  are  much  employed  in 
brewing,  sometimeB  supplying  a  third  part  of  the  malt.  But  generally  i  cwt.  of  malt  gives — 

300  quarts  light  beer. 
200     „      double  beer. 
180     „      Bavarian,  or  bock  beer. 

itetaiiaii  of  bmt  Bimriaf.      The  materials  of  beer  brewing  are : — i.  Grain,  or  amylaceous 

substances.    2.  Hops.    3.  A  ferment.    4.  Water. 

The  Orain. — The  grain  selected  for  this  purpose  is  generally  barley,  as  containing 

the  proportion  of  sugar  and  starch  best  adapted  to  form  alcohol.    Many  substitutes 

have  been  suggested,  but  with  inferior  success.    In  Bavaria,  the  large  double  barley 

(Hordeum  distichan),  is  preferred.    According  to  Lermer,  100  parts  of  dried  barley 

contain: — 

Dtarcn,      ...     ...     ...     ...     ...    ...  08*43 

Protein  substances 1625 

Dextrine 6*63 

f  (*w  ...  ...  ...  ...  ...  ...  ...  J    \^0 

Cellulose  ...     ...     ... 7*10 

Ash  and  other  constituentB   351 

2  D  2    . 


404  CHEMICAL  TECHNOLOGY, 


The  ash  of  barley  contains  in  lOO  parts : — 

Potash 

17 

Phosphoric  acid 

30 

Silicic  acid    

33 

Magnesia      ...     

7 

Lime     ...     

3 

with  other  constituents.     Potatoes,  rice,  maize,  glycerine,  and  potato-  or  starch 
sugar,  are  employed  in  some  modem  breweries. 
Hopa.      The  hop  {Hamulus  lupuliis),  is  a  diaecious  plant  of  the  natural  order  of 
Urticacese,  the  female  flowers  of  which,  or  catkins,  are  used  for  flavouring  beer. 
The  catkins,  or  strobils,  are  composed  of  a  number  of  bracts  or  scales,  which  are 
green,  afterwards  changing  to  a  pale  yellow.    At  the  base  of  each  flower  is  seated 
^e  pistil  containing  the  seed,  while  surroimding  the  pistil  are  a  number  of  little 
grains,  embedded  in  a  yellow  powder,  the  farina,  containing  the  active  property  of 
the  hop,  essentially  lupuline,  the  grains  being  termed  lupulinic  grain.    This  yellow 
pulverulent  substance  contains  an   essential  oil,  tannic  acid,   and  mineral  con- 
stituents.   The  essential  oil,  the  flavouring  principle  of  the  hops,  is  found  in  air- 
dried  hops,  to  the  amoimt  of  08  per  cent ;  it  is  yellow-coloured,  with  an  acrid  taste, 
without  narcotic  efiect,  of  a  sp.  gr.  =  0908,  turning  litmus  paper  red.    It  requires 
more  than  600  times  its  weight  of  water  to  eflect  a  solution.    It  is  free  &t)m  snlphor, 
and  belongs  to  the  group  of  essential  oils  characterised  by  the  formula,  C5H8,  and 
can  become  oxidised  under  contact  with  the  air  into  valerianic  acid  (C5H10OS),  this 
oxidation  being  the  cause  of  the  peculiar  cheesy  odour  of  old  hops ;  it  is  a  mixtnra 
of  a  hydrocarbon,  G5H8,  isomeric  with  the  oils  of  turpentine  and  rosemary,  with 
an  oil  containing  oxygen,  CzoHisO,  having  the  property  of  oxidation  alluded  to. 
Tannic  acid  is  fotmd  in  the  several  kinds  of  hops,  in  quantities  varying  from  2  to  5 
per  cent,  and  is  an  important  constituent,  as  it  precipitates  the  albuminous  matter  of 
the  barley  and  serves  to  clear  the  liquor.     It  gives  with  the  per-salts  of  iron  a  green 
precipitate ;  treated  with  acids  and  synaptase,  does  not  separate  into  gallic  acid  and 
sugar ;  and  by  dry  distillation  does  not  give  any  pyrogallic  acid.    The  hop  rew  is 
the  important  constituent  of  the  hops,  and  contains  the  bitter  principle  or  lupoline. 
It  is  difi&cultiy  soluble  in  water,  especially  in  pure  water  and  when  the  lupuline  or 
essential  oil  is  absent.      But  water  containing  tannic    acid,    gums,  and   sugar 
dissolves  a  considerable  quantity  of  the  resin,  especially  when  the  essential  oil  is 
present.    It  is  intensely  bitter  in  taste,  and  becomes  foliated  when  exposed  to  the 
atmosphere.    Hop  resin  and  the  essential  oil  are  not  identical ;  the  former  is  solnble 
in  ether,  the  latter  is  not.    In  the  course  of  long  exposure  it  becomes  insoluble.   The 
gum  and  extractive  colouring  matter  are  of  littie  use.    The  mineral  constituents  of 
hops  dried  at  icx)**  are : — ^in  ash,  9  to  10  per  cent ;   15  per  cent  of  phosphoiic  add; 
17  per  cent  potash,  &c. 

Qnauty  of  th«  Hops.  The  quality  of  the  beer  is  almost  proportionate  to  the  quaUt^  of 
the  hops.  A  rich  soil  is  required  for  the  growth  of  the  hop-plant,  well  exposed  to 
the  influence  of  the  sun's  rays,  and  protected  from  easterly  winds,  which  are  highly 
detrimental.  The  hops  must  on  no  account  be  gathered  until  the  seed  is  perfectly 
ripe,  as  it  is  only  then  tiiat  the  bitter  quality  is  fuUy  developed.  The  ripeness  of 
tiie  hops  ran  be  ascertained  by  rubbing  them  between  the  fingers ;  if  an  oily  matter 
remains,  with  a  strong  odour,  they  are  fit  for  gathering.  When  gathered,  the  next 
most  important  operation  is  the  drying,  which  is  effected  in  Idlns  or  stoves,  at  a 


BSER.  405 

• 

temperature  of  40^  with  a  good  yentilation.  When  sufficiently  dried,  the  small  stem 
attached  to  the  flower  snaps  readily.  The  temperature  must  he  carefully  regulated ; 
sot  permitted  to  range  so  high  as  to  run  the  risk  of  huming  the  hops,  nor  allowed  to 
fall  80  low  that  the  hops  may  afterwards  become  mouldy  from  under-drying.  When 
dried  the  hops  are  carefully  packed,  the  finer  kinds  being  put  into  canvas  pockets, 
and  the  inferior  into  hop-bags  of  a  coarser  texture.  The  bags  are  then  subjected  to 
slight  pressure  in  a  hydraulic  or  screw  press,  to  render  them  more  impervious  to  air. 
To  preserve  the  hops  they  are  sometimes  sulphured,  that  is,  subjected  to  the  action 
of  vapours  of  burning  sulphur,  i  to  2  lbs.  of  sulphur  being  employed  to  i  cwt.  of 
hops.  Old  hops  are  sometimes  treated  in  this  manner,  to  impart  the  colour  and 
appearance  of  freshly  dried  hops,  but  the  fraud  can  be  detected  by  the  odour.  The 
best  method  of  testing  for  sulphur  in  hops  is  as  follows : — ^A  sample  of  the  hops  is 
placed  in  a  sulphuretted  hydrogen  apparatus,  with  some  zinc  and  hydrochloric  acid ; 
the  disengaged  gas  is  passed  tlirongh  a  solution  of  acetate  of  lead.  If  the  hops  con- 
tain sulphurous  acid,  sulphuretted  hydrogen  will  be  disengaged — 

(S0a+2Ha= SHa+^HaO) , 

and  black  sulphide  of  lead  thrown  down  from  the  lead  solution.  Better  still  is  to 
receive  the  disengaged  gas  in  a  s(^ution  of  nitroprusside  of  sodium,  to  which  a  few 
drops  of  potash-ley  have  been  added ;  the  slightest  trace  of  sulphuretted  hydrogen 
imparts  a  b^osttiful  purple-red  colour  to  the  solution. 

8abttitat«8  for  Hope  Other  substances  have  been  used  as  substitutes  for  hops,  as  the  bark 
of  some  species  of  the  pine,  quassia,  walont  leaf,  wormwood,  bitter  olover,  extract  of 
aloes,  <&c. ;  recently  picric  acid  has  been  employed.  Although  aU  these  substances  impart 
a  bitter  taste  to  beer,  they  are  inferior  to  hops.  They  contain  the  same  constituents, 
namely,  tannic  acid,  a  resin,  a  bitter  extractive,  and  an  essential  oil. 

Water.  Water  is  employed  for  steeping  the  barley  for  the  purpose  of  inducing  germi- 
nation. Brewers  are  careful  as  to  the  usual  distinctiou  of  hard  and  soft  waters.  Soft  water 
contains  fewer  mineral  constituents.  Bain,  like  distilled  water,  is  a  very  soft  water,  con- 
taining traces  only  of  organic  matter,  nitrates  and  carbonate  of  ammonia.  Spring  and 
well  water  are  in  most  cases  hard  waters,  while  river  water  is  often  soft.  Soft  water,  or  nearly 
so,  is  best  adapted  for  brewing.  Biver  water  is  preferred  for  malting.  According  to 
Mulder,  in  water  containing  lime  an  insoluble  phosphate  is  deposited,  while  inithe  course 
of  time  lactic  acid  is  formed.  The  water  employed  is  usually  purified  by  filtration  through 
sand,  gravel,  and  charcoal. 

The  Ferment.  The  yeast  of  former  operations  is  generally  employed  in  fermenting  the 
beer-worts.  The  preparation  of  the  yeast  and  the  ratiofiale  of  the  process  of  fermentation, 
given  in  a  previous  section  of  this  work,  should  be  consulted. 

^BLraJSISg?'  T^6  brewing  of  beer  may  be  considered  to  consist  of  the  following 
operations : — 

1.  The  malting. 

2.  The  mashing. 

3.  The  fermentation  of  the  beer-worts. 

4.  The  fining,  ripening,  and  preservation  of  the  beer. 

ThflHaiuiig.  I.  Malting  is  the  process  during  which  tlie  grain— barley— is  germi- 
nated, by  means  of  steeping  in  water  imtil  it  swells  and  becomes  soft.  The  non- 
germinated  grain  possesses  only  in  a  very  small  degree  the  property  of  changing  its 
starch  into  sugar  (dextrose) :  tliis  property  is  Very  fully  developed  during  the  germi- 
nation, so  much  BO  that  it  would  be  an  easy  matter  to  distinguish  between  tlie 
germinated  and  non-germinated  seed  by  the  degree  of  this  property  alone.  As  has 
been  already  stated,  barley  is  the  grain  preferred,  on  account  of  its  forming  sugar  in 
larger  quantities  than  any  other  kind  of  grain.  The  germination  of  the  seed  takes 
place  in  three  well-marked  periods.     In  the  first,  the  eeed  is  enveloped  in  an  outer 


4p6  CHEMICAL   TECHNOLOGY, 

organ,  which  becomes  exhausted  and  withered.  In  the  second,  the  growth  of  the 
germ  is  shown  by  the  swelling  at  the  end  by  which  it  was  attached  to  the  stalk  ;  and 
in  the  third  period,  the  little  plumule  or  acrospire,  which  would  form  the  stem  of  tho 
new  plant,  is  put  forth.  The  germinating  seed  is  similar  to  an  egg,  with  its  white, 
yolk,  and  embryo ;  the  shell  corresponds  with  the  outer  or  hard  coating  of  the  seed ; 
the  white  and  yolk  of  the  egg  appear  as  the  albumen,  or  meal  of  the  grain ;  while 
the  embryo  of  tlie  egg  has  its  analogue  in  the  germ  of  the  grain.  A  remarkable 
change  takes  place  during  germination ;  the  glutinous  constituent  has  passed  from 
the  body  of  the  grain  to  the  radicula,  or  rootlet,  which  has  grown  to  nearly  the  length 
of  the  grain,  while  about  one-half  of  the  starch  has  been  conyerted  into  sugar. 
This  conversion  is  the  aim  of  the  malting,  as  by  its  means  the  sugar  can  be  leadilj 
dissolved.  The  grain  is  supposed  to  have  been  sufficiently  treated  when  the  plumviih 
or  acrospire,  has  attained  a  length  equal  to  two-thirds  of  the  entire  length  of  the 
grain.  The  operation  of  germination  is  the  same  with  all  kinds  of  grain  employed 
in  brewing.  The  conditions  of  success  are — the  saturation  of  the  grain  with  mois- 
ture, and  a  temperature  of  not  higher  than  40**  nor  lower  than  4^  with  access  of  air 
and  exclusion  of  light. 

a.  The  softening  or  soaking  of  the  grain  is  accomplished  in  large  cisterns  df  wood, 
sandstone,  or  cement  half  filled  with  water.  The  grain  is  poured  into  the  water, 
and  after  the  lapse  of  ^an  hour  or  so.  sinks  to  the  bottom  of  the  tank,  only  the  infe- 
rior and  diseased  seed  remaining  on  the  surfiEu^e,  to  be  removed  with  wooden  shovels, 
and  thrown  aside  for  use  as  fodder  for  horses,  cattle,  &c.  The  steep  water  receives 
the  soluble  constituents  of  the  husk  of  the  seed,  and  becomes  of  a  brown  colour  and 
peculiar  flavour,  with  a  decided  inclination  to  lactic,  butyric,  and  succinic  acid  fer- 
mentation. The  duration  of  the  softening  varies  according  *Jxi  the  age  of  the  grain, 
the  temperature  of  the  water,  &c.  A  young  fresh  grain  requires  48  to  72  homn' 
soaking,  while  an  older  grain,  containing  more  gluten,  is  not  thoroughly  softened 
under  6  to  7  days.  Grains  of  equal  age  and  constitution  must  be  soaked  together,  to 
obtain  an  equally  softened  product.  After  sufficient  soaking  the  grain  is  allowed  to 
drain  for  8  to  10  hours,  then  taken  out  and  thrown  into  heaps  on  the  floor  of  the  milt- 
house.  The  sufficiency  of  the  soaking  is  ascertained — i.  By  pressing  the  giain 
between  the  finger  and  thumb-nail,  when,  if  sufficiently  moistened,  the  germ  or 
embryo  will  be  projected,  a.  The  husk  is  easily  destroyed  by  pressure  between  the 
fingers.  3.  "When  crushed  with  a  piece  of  wood  the  grain  yields  a  floury  mass. 
The  grain  when  softened  has  a  peculiar  aroma,  resembling  that  of  apples.  Ths 
quantity  of  water  usually  absorbed  by  the  barley  amounts  to  40  to  50  per  cent  of  its 
weight,  while  the  grain  correspondingly  increases  in  volume  18  to  24  per  cent. 
During  this  absorption  the  gi-ain  loses  1*04  to  a  per  cent  of  its  own  weight  in  solid 
matter.  Lermer  states,  that  in  fresh  steep  water  he  has  found  succinic  acid  in  the 
proportion  of  30  grms.  to  i  bushel  of  grain  soaked. 

&.  The  Germination  of  the  Softened  Grain. — As  soon  as  the  grain  is  thoroughly 
saturated  with  moisture,  the  conversion  of  the  starch  into  sugar  commences.  When 
germination  has  proceeded  fiar  enough  it  must  be  stopped,  as  about  this  time  the 
formation  of  sugar  has  reached  a  maximum.  The  softened  barley  is,  as  before 
stated,  transferred  to  the  floor  of  the  malting-room,  where  it  is  "  couohed,*'  or  placed 
in  a  layer  4  to  5  inches  in  thickness.  Here  the  germination  proceeds  till  the  plumoltf 
have  attained  the  desired  length.  The  temperature  rises  some  6  to  io%  on  account  of 
the  heat  developed  during  germination,  and  consequently  much  of  the  moistiue  is 


BEER.  407 

dissipated.  The  chief  art  of  the  maltster  consists  in  stopping  the  germination  at 
that  point  when  the  plumules  and  roots  commence  to  draw  upon  the  constituents  of 
the  grain.  The  duration  of  the  germination  varies,  during  the  warmer  months  of 
the  year,  from  7  to  10  days,  while  towards  autumn  the  process  will  not  be  completed 
under  10  to  16  days,  but  the  average  duration  is  8  days.  The  grain  during  the  ger- 
mination loses  about  2  per  cent  of  its  weight,  probably  by  the  oxidation  of  the 
carbon  to  carbonic  acid  by  the  oxygen  of  the  air. 

c.  His  Drying  of  the  Germinated  Grain. — The  grain  is  now  removed  to  the  drying 
floor  [wdkhoden),  where  it  is  exposed  to  the  air  in  layers  3  to  5  centims.  in  depth,  and 
turned  about  with  rakes  6  to  7  times  daily.  When  the  malt  becomes  dry  it  is 
cleared  from  the  rootlets,  some  of  which  drop  off  by  themselves,  while  others  have 
to  be  removed  by  winnowing.  Malt  must  be  dried  for  the  making  of  most  kinds  of 
beer,  and  has  to  undergo  a  roasting  process  before  quite  fitted  for  use.  This  drying 
or  roasting  is  effected  in  a  malt  kiln  or  cylinder  heated  by  flues  to  the  boiling-point 
of  water.  During  the  roasting  the  malt  acquires  a  darker  colour,  due  to  the  con- 
version of  the  remainder  of  the  starch  into  sugar.  The  equality  of  the  temperature 
is  of  the  utmost  importance,  so  that  one  part  of  the  malt  may  not  be  more  strongly 
heated  than  another.  Before  the  malt  is  submitted  to  this  operation,  however,  it  is 
first  heated  to  30  or  40°.  By  this  means  some  of  the  starch  is  converted  into  gluten, 
and  forms  a  coating  to  the  grain  impervious  to  water,  the  malt  being  in  this  stage 
known  as  *'  bright"  malt  from  its  smooth,  glossy  appearance. 

The  malt  kilns  consist  essentially  of  the  drying  plates  upon  which  the  malt  is 
laid,  and  the  heating  flues.  The  plates  used  to  be  of  stone  or  sheet-iron,  but 
modem  brewers  employ  wire-wove  frames,  placed  one  above  the  other,  so  that  the 
hot  air  from  the  flues  beneath  may  ascend  through  the  interstices.  The  flues  are 
generally  of  sheet-iron  for  the  better  conduction  of  heat  to  the  surrounding 
atmosphere.  Coke  is  used  as  fuel  on  account  of  the  absence  of  smoke ;  as  with  coal 
or  wood  in  the  event  of  a  leakage  in  the  flues  considerable  damage  would  be  done 
to  the  malt. 

The  malt  is  not  all  dried  at  the  same  degree  (50°  to  100^  C),  but  is  distinguished 
as  pale,  amber,  brown,  or  black  malt,  according  to  the  degree  of  heat  to  which  it  has 
been  exposed.  Pale  malt  results  from  heating  to  33°  to  38"*;  amber,  from  a  temperature 
of  49**  to  52**;  and  brown  from  the  rather  high  temperature  of  65*5°  to  76"5**.  Black 
malt,  commonly  called  patent  malt,  is  prepared  by  roasting  in  cylinders,  like  coffee 
cylinders,  at  a  temperature  of  163^  to  220°.  These  darker  malts  are  used  in  England 
for  colouring  porters  and  stouts. 

100  parts  of  barley  give  92  parts  of  air-dried  malt.  The  loss  of  8  parts  may  be 
thus  accounted  for : — 

In  the  steep-water    15 

During  malting 3'0 

During  germination 3*0 

Other  losses      0*5 

Total  loss ••    8*0 

The  moisture  in  air-dried  malt  amounts  to  12  to  152  per  cent,  which  is  expelled 
during  the  kiln  drying.  According  to  0.  John  (1869)  i<^  parts  of  dried  barley 
give— 


408  CHEMICAL  TECHNOLOGY. 

L  n. 

Malt      83*09  85*88 

Plumules      3*56  3*09 

Radicules  (rootlets)     4*99  4*65 

Fermentary  products 8*36  6*38 

100*00  lOO'OO 

The  change  undergone  during  the  drying  or  roasting  of  the  malt  is  shown  in  the 
following  table,  the  result  of  Oudeman's  analyses : — 

Air.dried  Malt.    Eihi^dried  Malt.    Strongly  dried  Malt 


Products  of  roasting 

0*0 

7-8 

14*0 

Dextrine 

80 

6*6 

IO*2 

Starch   

58*1 

586 

47*6 

Sugar     

0*5 

07 

o*9 

Cellulose       

14-4 

io*8 

1 15 

Albuminous  matter 

13*6 

10*4 

io'5 

jkaw...     •••     •••     ..• 

2*2 

1 

2*4 

2*6 

32 

2*7 

27 

The  amount  of  sugar  is  undoubtedly  increased  during  the  process;  and  the 
dextrine  appears  to  increase  with  decrease  of  starch,  and  vice  ven&»  The  conTersion 
of  starch  into  dextrine  and  sugar  is  effected,  as  far  as  is  known,  by  the  agency  oC 
diastase.  Dubrunfaut  has  only  lately  (1868)  shown  that  malt  presents  another 
substance  similar  in  its  effect  to  diastase,  and  which  he  termed  rnaltin.  This  principle 
is  found  to  be  much  more  active  than  diastase,  so  that  with  the  same  qumitity 
of  maltih  which  a  known  quantity  of  malt  contains,  ten  times  as  much  beer  can  be 
obtained  as  when  diastase  only  is  employed.  Dubrunfaut  has  also  found  a  second 
but  less  active  substance.  Its  behaviour  with  respect  to  the  decomposition  of  starch 
is  similar  to  that  of  diastase;  malt  contains  li  per  cent,  while  only  i  per  cent  of 
maltin  is  foimd.  The  treatment  with  alcohol  necessary  to  obtain  diastase  destroys 
the  maltin.  Dubrunfaut  believes  diastase  to  be  only  a  less  active  modificatioa  of 
these  new  substances. 

^'**^ort.*''"'®  2.  Under  this  head  is  included  the  preparation  from  malt  of  the 
wort — a  saccharine  fluid  containing  dextrine — and  the  flavouring  with  hops.  The 
general  method  of  preparation  is  in  three  operations: — 

a.  The  bruising  of  the  malt. 

b.  The  mashing. 

0.  The  boiling  and  flavouring  of  the  wort  with  hops. 

""^^TiSitf  ******  ^'  Beer- wort,  or  the  wort,  as  it  is  generally  termed,  is  obtained 
by  means  of  the  extraction  of  the  bruised  malt  with  water.  To  the  end  that  all  the 
active  principles  may  be  extracted  from  the  malt,  it  must  be  bruised  or  ground  to  a 
fine  meal.  The  obtaining  of  a  clear  liquor  after  the  extraction  is  effected  hj 
means  of  filtration.  The  grinding  is  ordinarily  performed  in  a  malt  mill,  a  madune 
with  rolkrs  being  preferred  as  affording  a  more  equable  product 

KMhiiig.  b.  The  mashing  is  a  most  important  operation,  on  success  in  which 
depends  many  of  the  good  qualities  of  the  beer.  It  is  during  this  operation  that 
not  only  the  sugar  and  dextrine  already  existing  in  the  malt  are  set  firee,  hot 
also  the  unconverted  starch,  by  the  aid  of  diastase,  the  water,  and  a  &voiiz«Ue 


BEER. 


409 


temperature,  suffer  conyersion  into  sugar  and  dextrine.  Lermer  found  in  the  best 
cases  of  mashing  that  only  half  the  starch  was  converted  into  a  corresponding 
quantity  of  sugar.  The  operation  is  very  variously  performed,  but  generally  may  be 
considered  as  effected  by  either  of  two  methods : — 

a.  The  Infusion  Method,  aooording  to  which  the  mash  is  prepared  at  a  certain 
degree  of  heat,  bat  never  attains  the  boiling-point.  The  crushed  malt  is  thrown 
into  hot  water  (Jlnt  east)  in  the  mash  tun,  and  when  the  mash  has  reached  a 
certain  saccharine  condition,  a  further  addition  of  water  is  made  (second  and 
third  cast).  The  infusion  method  is  much  employed  in  North  Germany,  France, 
Englimd,  Austria,  and  Bavaria. 

6.  The  Decoction  Method, — ^After  the  infusion  has  been  made  the  mash  is  brought  to 
the  boiling-point,  and 

a.  A  portion  of  the  water  evaporated  to  form  a  thick  mass  {thick  mash 
boiling).  At  a  subsequent  stage,  only  a  portion  of  the  mash  having 
been  thus  treated,  the  remainder  of  the  mash  is  added,  and 

/3.  The  whole  of  the  mash  is  heated  to  the  boiling-point  {clear  mash  boiling). 
During  the  clear  mash  boiling  the  hops  are  added. 

The  mashing  vessels  are  either  round  tubs  or  wooden  cisterns  with  a  double 
bottom,  the  upper  being  perforated,  and  about  an  inch  above  the  true  bottom.  Between 
the  bottoms  is  a  tap  through  which  the  wort  is  drawn  off.  In  large  breweries  these 
bottoms  are  of  metal  instead  of  wood.  The  hot  water  is  supplied  from  the  bottom 
and  not  from  the  top  of  the  vessel  Under  the  mashing  vessel  is  situated  a  large 
reservoir,  either  of  stone,  cement,  wood,  or  masonry,  and  destined  to  receive  the 
fluid  run  off  from  the  mash.  The  continuous  stirring  of  the  contents  of  the  mash- 
tun  or  tub  is  effected  either  by  hand  or  machinery  driven  by  water  or  steam  power. 

Deooetion  Method.  The  general  description  of  the  mashing  process  having  been  given, 
we  now  pass  on  to  the  particular  method  of  preparing  the  wort  by  decoction.  The 
infusion  takes  place  in  the  mash-tun,  in  which  the  required  quantity  of  water  is 
placed,  and  the  malt  to  be  mashed  shaken  in.  The  quantity  of  water  employed  in 
making  the  infusion  is  generally  in  the  proportion  of  202  volumes  of  water  to  100 
volumes  of  malt,  both  at  the  ordinary  temperature.  After  the  bruised  malt  has 
been  well  stirred  in  the  water,  the  whole  is  allowed  to  stand  for  6  to  8  hours.  During 
this  time  the  necessary  quantity  of  water  is  heated  to  the  boiling-point  in  the 
copper.  The  quantity  of  water  used  to  prepare  an  estimated  quantity  of  beer  is 
termed  the  "cast,"  and  the  quantity  of  malt  the  "yield."  In  Bavaria  the  quantity 
of  beer  prepared  from  a  defined  quantity  of  malt  is  as  follows : — 

,.^  ^^i„«,««  r.f  «,«u  -«--.ij  i202"3  volumes  of  Schenk  beer. 
100  volumes  of  malt  yieW  ^  ^^^.^       ^^        ^^  j^^^  ^^^^ 

In  order  to  produce  tliis  quantity  of  beer  an  equivalent  quantity  of  water  must  of 

course  be  employed,  so  that  in  a  Bavarian  brewery  to  100  volumes  of  malt  there  are 

taken  of  water — 

Schenk  beer.  Lager  beer. 

For  infusion 202*3  vols.  202*3  vols. 

For  mashing 170*0    „  130*0    „ 

3723  vols.  332*3  vols. 

These  proportions  vary  according  to  the  quality  of  the  grain,  the  state  of  the 
weather,  the  length  of  time  of  keeping, ^c. 

The  various  modifications  of  the  decoction  method  are — i.  The  Bavarian  or  Munich 
method.  2.  The  Augsberg- Nuremberg,  or  Swabian  method,  sometimes  termed  '*  sediment 
brewing  '*  {sats  brauen). 

Thick  Math  bouiuk.      According  to  the  Munich  method  (thick  mash  boiling)  the  cast  of  water  is 
divided  into  three  portions,  two  of  which  are  poured  into  the  mash-tun  to  form  a  paste  with 


4i6  CHEMICAL  TECHNOLOGY. 

thd  bmised  malt.  After  this  mash  has  stood  for  two  to  four  hoars,  the  remaining  third  of  the 
water,  which  daring  this  time  has  been  heated  to  the  boiling-point  in  the  copper,  ia  added, 
the  whole  of  the  mash  attaining  thereby  a  temperatare  of  30*  to  40*.  Then  follows  the 
first  thick  mash  boiling ;  for  tins  parpose  the  brewer  draws  the  mailed  grain  to  one  side 
of  the  tan,  and  removes  a  portion  to  the  copper,  where  for  sohenk  beer  it  is  boiled  for  thirty 
minntes,  and  for  sammer  beer  for  seventy -five  minates.  The  qaantity  of  mash  boiled 
at  each  operation  is  generally  about  half  the  oast.  The  boiling  mass  is  retamed  to  the 
mash  tan.  Then  follows  the  second  thick  mash  boiling,  which  for  schenk  beer  lasts 
seventy-five  minates,  and  for  sammer  beer  an  hoar.  By  means  of  the  first  bmled  mash 
the  contents  of  the  mash  tan  are  raised  to  a  temperatare  of  48°  to  50*",  and  by  the  second 
addition  to  60°  to  62°.  After  the  finishing  of  the  second  mashing  the  cUar  mashing  begins, 
t^at  is,  the  thinly  fiaid  part  of  the  mash  is  placed  in  the  copper  and  boiled  for  about 
fifteen  minutes,  and  is  then  retamed  to  the  mash  tun.  The  temperatare  of  the  mash  ii 
now  72°  to  75°,  and  is  most  suited  for  the  formation  of  sugar.  The  mash  remains  in  the 
covered  tun  i}  to  2  hours.  Dxuring  this  time,  and  as  soon  as  the  clear  maah  has  been 
removed  from  the  copper,  the  latter  is  re-filled  with  a  sufficient  quantity  of  water  for  the 
purposes  of  brewing  small  beer.  When  the  sugar  has  been  properly  formed  and 
dissolved  in  the  wort  the  latter  is  removed  from  the  mash  tun  to  the  fermenting  vessels. 
The  remaining  mash  is  then  treated  with  hot  water  to  yield  small  beer,  i  bushel  of  malt 
yielding  35  to  50  quarts  of  this  beer.  The  residue  of  the  small  beer  is  again  treated  with 
water,  the  resulting  infusion  being  employed  in  vinegar  making.  The  residue  from  this 
process  is  used  as  fodder  for  cattle. 

The  thick  mash  boiling  is  by  no  means  a  rational  method,  as  the  separation  of  lbs 
ma^  and  the  several  removals  are  unnecessary  labour,  and  do  not  contribute  so  much  to 
the  complete  extraction  of  the  malt  as  is  generally  supposed;  the  high  temperature  renders 
a  portion  of  the  diastase  ineffective,  while  much  of  the  starch  roQiains  unconverted  into 
dextrine  and  dextrose. 

All  who  have  tried  to  reduce  the  brewing  process  to  simple  methods  based  upon  sound 
chemical  and  physical  principles  declaim  against  the  process  of  thick  ma^  boiling, 
stating— and  with  good  sound  reason  proved  by  experiments — that  the  advantages  of  thLi 
method  are  absurdly  overrated ;  and  that  in  order  to  lessen  the  bad  effects  of  tUa  method 
as  much  as  possible  it  should  be  replaced  by  a  method  of  hot  mashing,  viz.,  at  a 
temperature  of  from  60°  to  65°. 

Angsboig  Method.  Distinct  from  the  foregoing  mash  methods  is  the  so  called  "  sediment 
brewing"  used  in  many  Swabian  and  Franconian  breweries.  It  essentially  consists  in 
treating  the  bruised  malt  with  cold,  and  then  with  hot  water  to  obtain  a  saccharine  wort 
The  bruised  malt  is  mixed  with  cold  water  in  the  mash  tun  in  the  proportion  of  7 
Bavarian  bushels  to  30  to  35  eimers  (each »  68*41  litres)  of  water.  After  standing  for  four 
hours,  two-thirds  of  the  fluid  is  drawn  off.  During  this  time  a  quantity  of  water 
(48  eimers  to  7  bushels  of  bruised  malt)  is  brought  to  the  boiling-point  in  the  copper ;  a 
portion  of  tins  water  is  now  added  to  the  contents  of  the  mash  tun,  which  thus  attains  a 
temperature  of  50**  to  52",  while  the  liquor  or  weak  wort  drawn  off  from  the  mash 
tun  is  poured  along  with  the  rest  of  the  water  in  the  copper.  The  liquor  that  has  been 
drawn  off  contains  albumen,  diastase,  dextrine,  and  dextrose.  The  mash  is  allowed  to 
stand  for  a  quarter  of  an  hour  in  the  tun,  when  the  fluid  is  entirely  drawn  off,  transferred 
to  the  copper,  and  heated  to  the  boiling-point.  This  is  termed  the  **  first  mash.'*  "While 
this  is  going  on  enough  fluid  will  have  drained  from  the  malt  in  the  mash  tun  to  fill  the 
space  between  the  double  bottoms  of  the  tun ;  this  fluid  is  at  once  removed  to  the  cooling 
vessels.  The  fiuid  heated  in  the  copper  is  now  returned  to  the  mash  tun,  the  entire 
contents  of  which  attain  a  temperature  of  72"  to  75"^.  This  **  second  mash  "  is,  after  an 
hour's  interval  followed  by  a  "  third  maan."  The  wort  is  then  ran  into  the  oooling 
vessels. 

infuioBMeUuMi.      The  infusion  method  is  distingaiBHed  from  the  decoction  method  by 

a  slight  difference  in  the  procedure,  the  bruised  malt  being  treated  with  water  at  a 

temperatare  of  70®  to  75°,  bat  without  any  portion  of  the  mash  being  boiled.    The 

method  is  that  usually  employed  in  this  country.  North  America,  France,  Belgium, 

and  North  Germany. 

The  quantity  of  water  intended  to  be  used  for  the  mashing  process  is,  according 

to  the  initial  temperature  of  the  water  the  brewer  has  at  hand,  heated  either  whollj 

or  only  a  portion  in  the  copper,  the  temperature  of  this  fluid  being  raised  in  winter 

to  75^  in  summer  to  from  50®  to  60°.   The  necessary  quantity  ia  first  poured  into  the 

mash  tun,  the  bruised  malt  being  next  added,  and  the  mixture  made  up  so  as  to 


BEER.  41  z 

form  a  moderately  thin  paste.  .  Water  is  heated  to  the  boiling-point  in  the  eopper  in 
order  to  proceed  farther  with  the  mashing  process.  As  soon  as  a  sufficient  qnantity 
of  water  boils  it  is — ^usually  by  means  of  properly  constructed  pipes — allowed  to 
rnn  into  the  mash  ton,  wherein  it  is  considerably  cooled  owing  to  the  colder  water 
(liquor)  present  in  that  vessel;  the  increase  of  temperature  of  the  contents  of 
the  tun  to  75**  (the  most  suitable  for  saccharification)  is  gradually  made  in  order  to 
prevent  the  formation  of  starch  paste,  whereby  the  formation  of  diastase  would  be 
interfered  with.  Since  the  conversion  of  amylum  (starch)  into  dextrine  and  dextrose 
proceeds  gradually  only,  it  is  clear  that  the  contents  of  the  mash  tun  should  be  kept 
at  the  temperature  suitable  for  that  process ;  while,  however,  on  the  other  hand,  care 
has  to  be  taken  to  prevent  the  mash  becoming  sour  by  the  formation  of  lactic 
(probably  also  propionic)  acid. 

The  progress  of  the  formation  of  dextrine  and  dextrose  is  best  ascertained  by  the 
help  of  an  aqueous  solution  of  iodine,  or  preferably  of  iodine  dissolved  in  i6dide  of 
potassium,  in  the  proportion  of  o'l  grm.  of  iodine  and  1*0  of  iodide  of  potassium  to 
100  c.c.  of  water ;  this  solution  will  at  first  give  with  a  sample  of  the  mash  a  dark 
blue  colouration,  next  a  wine  red,  and  finally,  when  only  dextrine  and  dextrose  are 
present,  no  colouration  at  all.  The  addition  of  two  to  three  drops  of  the  clear 
wort  to  a  small  quantity  of  this  iodine  solution  is  sufficient  for  testing.  When 
the  mash  has  been  kept  for  about  one  hour's  time  at  the  temperature  most  suitable 
for  the  saccharification,  the  wort  is  run  either  into  a  large  reservoir,  or  into 
a  vessel  kept  expressly  for  this  purpose,  or  lastly,  at  once  into  the  copper ;  and  a 
fresh  quantity  of  water  is  then  poured  into  the  tun,  and  the  contents  of  the  tun 
are  allowed  to  remain  for  half  to  one  hour  at  a  temperature  of  75^  It  is  as  a 
matter  of  course  quite  evident  that  the  infusion  method  may  be  varied  as  regards 
the  quantity  of  water  and  repeated  number  of  infusions ;  but  in  order  to  brew 
a  beer  of  a  certain  and  fixed  brand  it  is  requisite  that  the  degree  of  concentration 
of  the  wort  be  always  the  same.  For  the  purpose  of  ascertaining  the  degree  of 
concentration,  Balling's  saccharometer  is  generally  employed,  which  instrument  when 
put  into  sugar  solutions  indicates  the  percentage  of  sugar  they  contain.  Balling 
has  shown  that  solutions  of  dry  extract  of  malt  have  the  same  specific  weight 
as  cane  sugar  solutions  of  equal  percentage.  For  use  in  a  brewery  the  saccharometer 
need  only  be  graduated  for  solutions  varying  between  ^  to  30  per  cent. 

xitnekivw  of  the  Wort  The  quantity  of  extract  which  a  wort  should  contain  depends, 
ef  course,  upon  the  quality  of  the  beer  which  the  brewer  desires  to  make,  and  differs 
according  to  the  nature  of  the  beer,  whether  it  shall  be  thick,  heavy  (rich  in 
extract)  or  strong  (of  great  alcoholic  strength).  The  quantity  of  malt  extract  varies 
in  different  beers  from  4  to  15  per  cent,  that  of  the  alcohol  from  2  to  8  per  cent. 
I  per  cent  of  sugar  in  the  wort  3delds  after  fermentation  0*5  per  cent  of  alcohoL  To 
produce  a  beer  containing  5  per  cent  of  alcohol  and  7  per  cent  of  nudt  extract,  the 
wort  should,  before  fermentation,  mark  the  degree  on  the  saccharometer  corre- 
sponding to  17  per  cent.  A  beer  of  3*5  per  cent  of  alcohol  and  5*5  per  cent  of  malt 
extract  will  have  resulted  from  a  wort  containing  12*5  per  cent  of  sugar. 

Bofli&KtiMWort.  c.  The  prepared  but  not  yet  boiled  wort  contains  dextrose,  dextrine, 
some  unconverted  starch,  protein  substances,  extractive  matter,  and  organic  salts. 
The  colour  of  the  wort  is  a  brown  or  yellow-brown,  according  to  the  variation  of 
colour  of  the  malt  from  which  it  has  been  obtained.    The  odour  is  agreeable  and  the 


4it  CHEMICAL  TECHNOLOGY. 

taste  sweet.    The  wort  exhibits  an  acid  reaction  to  tesit-paper,  owing  to  the  presenct 

in  that  fluid  of  small  quantities  of  free  phosphoric,  lactic,  and  probably  other  adds ; 

but  in  case  the  wort  has  by  accident  become  sour,  or  if  wort  is  made  purposely 

from   already    exhausted   grain  which    has    become  sour,    this  reaction  is    far 

stronger,  and  may  be  ascertained  by  the  odour,  owing  to  the  formation  of  volatile 

acids,  among  which  butyric,  and  in  the  latter  case,  lactic  and  propionic  acids  are  present 

in  large  quantity.     The  boiling  of  the  wort  aims  at  its  concentration,  and  also 

at  the  extraction  of  the  bitter  principle  of  the  hops ;  further  also  for  the  purpose 

of  coagulating  and  precipitating  a  portion  of  the  albuminous  substances,  by  the  aid 

of  the  tannic  acid  contained  in  the  hops.     This  latter  reaction  renders  the  wort 

clear.    In  many  breweries  gypsum  is  added  to  the  boiling  wort  to  reduce  the  whde 

of  the  nitrogenous  substances.    The  boiling  is  generally  effected  in  copper  cauldrons 

(technically,  also  simply,  "the  copper"),  set  in  masonry  over  a  fire-grate.    The  fire 

is  very  carefully  disposed  to  prevent  the  burning  of  the  wort,  as  the  pans  tie 

exposed  to  the  direct  action  of  the  flame.    The  manner  of  hopping  (as  it  is  termed), 

that  is  to  say,  the  mode  of  adding  the  hops  to  the  wort,  varies  in  different  breweries, 

and  depends  as  regards  quantity  also  upon  the  quality  (strength)  of  the  hops,  ^ 

larger  or  smaller  amount  of  extract  contained  or  desired  to  be  retained  in  the  beer, 

and  last,  but  not  least,  the  mode  of  preservation  and  length  of  time  it  is  intended  to 

keep  the  beer. 

▲ddinf  tho  Hop*.      To  winter  beer,  which  in  Grermany,  as  a  rule,  is  consumed  in  four  to 

six  weeks  after  brewing,  the  old  hops  (viz.  one  year  old),  are  added  in  the  propoition 

of  2  to  3  pounds  to  a  Bavarian  bushel  of  malt  (2*22  hectolitres) .    For  summer  beer,  to 

be  consumed  in  May  and  June,  4  to  5  pounds  of  new  hops  are  added  to  the  bushel  of 

dried  malt;  while  for  the  beer  for  September  and-October  consumption,  6 to  7  pounds 

of  new  hops  are  employed  with  each  bushel  of  malt.    Among  the  constituents  of 

hops  which  are  active  in  the  process  of  brewing,  we  mention  in  the  first  place  the 

bitter  ingredient  it  contains  (not  correctly  known,  notwithstanding  recent  research) 

and  which  as  well  imparts  to  beer  its  bitter  taste  as  its  narcotic  property ;  further,  the 

tannic  acid  which  combines  during  the  boiling  of  the  wort  with  a  portion  of  such 

of  its  protein  compounds  as  are  not  rendered  insoluble  by  the  boiling  alone,  and 

form  together  a  precipitate,  rendering  the  wort — previously  turbid — quite  dear, 

and  also  regulating  the  first  and  second  (so  called  after)  fermentation.    The  essential 

oil  and  resin  met  with  in  hops  act  to  a  certain  extent  as  retarding  the  fermentatioii. 

and  thus  as  preventatives  of  converting  the  wort  into  a  sour  liquid ;  as  regards  the 

inorganic  constituents  of  hops,  they  do  not  appear — at  least  cannot  be  directly 

proved — to  be  of  much  consequence.     As  regards  the  degree  of  concentration  to 

be  given  to  the  wort  by  the  process  of  boiling,  it  should  be  observed  that  the  degree 

of  concentration  as  ascertainable  by  the  saccharometer  should  remain  from  0*5  to  i 

saccharometrical  percentage  under  the  degree  of  concentration  which  the|woit 

should  indicate  at  the  beginning  of  the  fermentation,  because  while  cooling,  tiie 

wort  gains  in  concentration  just  the  percentage  alluded  to.    The  separation  of  the 

coagulated  albumen  does  not  take  place  until  the  temperature  of  the  wort  has 

reached  90° ;    and  the  quantity  separated  is  greater  from  wort  prepared  by  the 

infusion  method  than  from  that  prepared  by  the  decoction  method.    As  soon  as  it 

appears  that  in  a  sample  of  the  boiling  wort  taken  from  the  pan  and  poured  into  a 

large  test-glass  the  suspended  fiocculent  matter  settles  rapidly  to  the  bottom  oC 

the  glass,  the  boiling  can  be  discontinued,  the  wort  being  then  ready ;  but  in  the 


BEER.  413 

case  of  the  infnsion  method,  the  boiling  is  continued  for  the  purpose  of  further 
concentrating  the  liquor,  and  the  boiling  for  this  purpose  may  even  last  for 
£rom  5  to  8  hours.  If  the  boiling  only  aims  at  the  coagulation  of  the  albuminous 
compounds,  one  hour's  boiling  in  winter,  and  three  quarters  of  an  hour  in  summer,  is 
quite  sufficient.  As  regards  the  hops,  it  is  best  to  add  them  in  a  somewhat  cut  up 
state,  and  not  before,  by  a  good  boiling  of  the  wort,  the  greater  part  of  the  albuminous 
compounds  have  been,  as  far  as  possible,  precipitated.  In  order  to  extract  the  hops, 
the  wort  is  either  passed  through  a  basket  filled  with  hops  or  through  any  suitably 
constructed  perforated  vessel  retaining  the  hops,  this  vessel  being  placed  in  com- 
munication with  the  coolers ;  or  the  hops  are  boiled  along  with  the  wort ;  or  again, 
several  portions  of  the  wort  are  boiled  successively  along  with  the  same  quantity  of 
wort ;  and  lastly,  even  with  the  weakest  wort  or  after-run. 

Cooling  tiie  Wort.  The  cooling  of  the  wort  to  the  degree  necessary  for  the  commence- 
ment of  the  fermentation  is  effected  in  large  wooden,  stone,  or  iron  cisterns.  As 
at  a  temperature  of  25°  to  30°  G.  the  wort  has  a  great  tendency  to  set  up  lactic  acid 
fermentation,  the  cooling  has  to  be  very  rapid  in  order  that  the  temperature  of  the 
liquid  may  be  soon  much  below  25°  to  30°,  and  thus  any  danger  of  souring 
prevented. 

The  cooling  of  the  wort  is  an  operation  which  is  performed  in  well  constructed 
and  in  all  directions  well  ventilated  buildings,  protected  from  rain,  in  which 
buildings  the  coolers  are  placed.  Owing  to  improvements  in  the  modes  of  cooling, 
it  is  now  possible  even  to  brew  beer  in  localities  (as  for  instance  Montpellier 
and  Marseilles,  Barcelona,  and  Naples)  where  formerly,  on  account  of  the  prevailing 
high  temperature  during  the  greater  portion  of  the  year,  brewing  could  not  take 
place  at  all;  while  also  for  the  same  reason  in  various  countries  (America, 
United  States  especially),  excellent  lager  beer  ia  brewed.  The  cooling  vessels 
are  generally  only  6  to  8  inches  deep,  of  wood,  iron,  or  copper,  and  are  placed  in 
an  airy  situation  near  or  immediately  under  the  roof  of  the  brewery.  Metallic 
vessels  are  of  course  more  effectual  in  cooling  the  wort  in  a  short  time  than  wooden 
ones ;  they  are  also  more  cleanly,  and  less  liable  to  get  out  of  order.  In  some 
breweries,  where  a  constant  stream  of  cold  water  is  available,  the  coolers  are  placed 
therein ;  but  this  is  of  course  a  matter  entirely  depending  on  the  locality  of  the 
brewery.  Without  doubt  the  surest  means  of  cooling  the  wort  rapidly  is  by 
employing  ice,  either  in  blocks  in  the  wort  or  in  pans  placed  in  the  cooling  tuns. 
But  for  economic  reasons  this  plan  is  not  generally  available.  The  temperature 
to  which  the  wort  is  to  be  cooled  is  that  best  suited  to  fermentation,  the  next  process 
to  which  the  wort  is  subjected.  The  following  are  the  temperatures  at  which  fer- 
mentation most  readily  sets  in,  depending  upon  the  temperature  of  the  locality  and 
upon  the  kind  of  fei-mentation : — 

Temperature  of  the  wort. 


Temperature  of  the  locality 
where  the  fermentation 
takes  place. 

In  sedimentary 
fermentation. 

In  superficial 
fermentation. 

6^  to    7° 

12° 

15" 

7' to    8° 

11° 

14° 

8°  to    9° 

10° 

13° 

9''  to  10" 

9° 

12° 

10°  to  12° 

7' to  8' 

12°  to  11* 

The  concentration  of  the  boiled  and  hopped  wort  is  expressed  in  degrees  per  cent 
of  the  saccharometer. 


414  CHEMICAL    TECHNOLOGY. 

According  to  J.  Gechwandler's  researches  (1868),  the  undermentioned  BaYanm 
l)eer  worts  had  the  following  composition : — 

Decoction.         Book.  Method^     Infaaioii. 

Sugar f    4*850  7100  4370            5*260 

Dextrine      6*240  8'6oo  7*610            6680 

Nitrogenous  substances    O790  i"350  —                — 

Other  constituents    0*410  0*630  0*950            0*700 

Specific  weight i"050  1*073  1052            1051 

Extract  (direct  estimation)       ...  11*870  17*050  11*980  11*940 

„        (according to  Balling) ...  12*290  17680  12930  12*640 

While  the  wort  remains  in  the  cooler  a  yellow-gray  or  brown  sediment  is 
deposited,  consisting  of  a  compound  of  coagulated  albumen  with  the  tannic  add  of 
the  hops,  and  some  starch  similarly  combined.  This  sediment  daring  the  fiist 
•cooling  is  formed  in  quantities  varying  between  3  to  4  per  cent  of  the  quantity  of  the 
cooled  wort ;  the  sediment  when  washed  and  dried  amounts  to  0*5  per  cent  of  the 
quantity  of  malt  employed. 
Th«  PMiD«ntation.  III.  Tks  Fermentation  of  the  Beer  Wort.^ — The  wort  when  cool  is  nm 
into  the  fermenting'tanks,  where  fermentation  sets  in  either  spontaneonslj,  or  is 
induced  by  the  addition  of  yeast.  The  first  kind — spontaneous  fermentation — sets  in 
as  soon  as  the  wort,  having  been  cooled  down  to  the  temperature  most  suitable  for 
fermentation,  is  left  to  itself,  and  this  fermentation  is  induced  by  the  spomles  of  yeast 
(ferment  cells)  always  present  in  all  fermenting  localities,  which  meeting  with  tbe 
wort,  find  in  that  liquid  the  proper  conditions  suited  for  their  growth.  This  kind  of 
spontaneous  fermentation  is  applied  usefully  in  the  brewing  of  the  Belgian  been 
known  as  Faro  and  Lambick,  which  are  rich  in  lactic  acid.  Usually,  however, 
yeaflt  is  added  to  the  wort,  and  there  is  avoided  the  dangerous  first  stage  of 
spontaneous  fermentation,  for  by  the  addition  of  the  yeast  a  regular  and  rapid 
fermentation  is  set  up,  but  yet  so  regulated  that  the  yeast  only  gradually  converts 
the  dextrose  into  alcohol  and  carbonic  acid. 

The  higher  the  temperature  of  the  wort  and  of  the  locality  the  smaller  the  quantity 
t)f  yeast  required.  A  yeast  formed  by  a  violent  fermentation  and  at  a  high  temperatme, 
has  more  active  qualities  than  yeast  formed  at  a  lower  temperature  and  by  a  longer 
fermentation.  The  first  spreads  itself  rapidly  over  the  6ur£&ce  of  the  fluid,  and 
is  termed  superficial  yeast  (oherhefe) ;  while  the  second  sinks  to  the  bottom  of  the 
vessel,  and  there  continues  its  action ;  this  is  termed — sedimentary ^  or  bottom  yeast 
(unterhefe).  The  fermentations  resulting  from  these  two  yeasts  are  respectively 
termed  superficial  fermentation  (o6^r<7aArt</i^),  and  sedimentary  fermentation  (awtar- 
gdhrung).  The  latter  fermentation  is  induced  in  worts  that  are  intended  to  yield 
beers  of  great  durability,  such  as  the  Bavarian  beers.  The  superficial  fermentation 
is  induced  in  such  beers  as  are  intended  to  be  soon  drunk.  Where  fermentadom 
is  induced  in  a  wort  at  a  low  temperature  and  with  deposit  only  (bottom-yeast)  tke 
so-called  surface  fermentation — that  is  to  say,  a  vinous  fermentation  whereby  yeast 

*  The  results  of  the  researches  made  by  Yon  Lermer  and  Liebig  (1870),  are  of  great 
importance  for  a  rational  basis  of  the  brewer's  business.  According  to  tnese  tarajUt,  an 
addition  of  sugar  to  a  solution  of  dextrine,  to  which  previously  beer-yeast  has  been  added, 
causes  a  large  quantity  of  the  dextrine  to  be  converted  into  alcohol  and  carbomio  add,  jnsl 
as  if  the  dextrine  were  sugar. 


BEER.  415 

is  carried  to  the  surface  of  the  fermenting  fluid — ^is  employed  chiefly  for  such 
kinds  of  worts  as  are  intended  to  produce  a  beer  which  is  not  required  to  be 
kept  for  any  length  of  time,  but  rapidly  consumed  after  having  been  brewed.  The 
wort  is  in  this  instance  generally  rich  in  sugar  (glucose) ;  and^  while  only,  a  portion 
of  this  sugar  is  converted  into  alcohol  (sweet  beer  being  formed),  tlie  formation 
of  a  small  quantity  of  alcohol  (the  wort  being  only  lightly  hopped),  contributes 
largely  to  the  preservation  of  this  kind  of  beer.  Surface  fermentation  is  also 
induced  in  such  kinds  of  worts  as  are  either  very  concentrated  or  contain  sub- 
stances which  to  some  extent  retard,  or  might  even  altogether  impede,  fermentation ; 
as,  for  instance,  the  empyreumatic  substances  present  in  a  very  highly  roasted  malt 
or  a  large  quantity  of  hops,  these  conditions  obtaining  in  the  brewing  of  porter, 
stout,  and,  as  regards  hops,  the  bitter  ale.  Worts  of  -this  description  come  com- 
paratively very  difficultly  into  fermentation.  Fermentation,  no  matter  whether 
surface  or  sedimentary  (the  yeast  is  in  this  case  slowly  deposited  as  a  sediment  on 
the  bottom  of  the  vessel),  exhibits  the  three  following  phases,  viz. : — 

1.  The  chief  fermentation,  beginning  soon  after  the  addition  of  the  yeast, 
characterised  by  the  decomposition  of  glucose,  by  the  formation  of  new  yeast,  and 
by  an  increase  of  temperature. 

2.  The  after  fermentation,  during  which  decomposition  of  glucose  continues 
slowly,  while  the  formation  of  new  yeast  cells  does  not  ensue  so  energetically  as 
in  the  first  phase,  the  suspended  particles  of  yeast  settling  down,  and  the  beer 
becoming  clear. 

3.  The  quiet  or  imperceptible  fermentation  taking  place  when  the  after  fermentation 
is  finished  is  characterised  by  a  farther  decomposition  of  glucose,  while  the  formation 
of  yeast  is  not  perceptible  to  any  extent. 

Sfldiaoiury  rwmcntotioii.  Sedimentary  fermentation  is  employed  in  the  brewing  of  the 
Bavarian  schenk  and  lager  beers,  taking  place  in  large  fermentation  vats  con»- 
taining  1000  to  2000  litres  of  wort.  Becentiy,  upon  the  suggestion  of  G.  Sedlmayer, 
these  vessels  have  been  constructed  of  glass.  The  addition  of  yeast  may  be  effected 
in  two  different  ways :  yeast  may  be  either  added  to  the  wort,  or  a  small  portion  of 
the  wort  is  first  separately  brought  into  a  state  of  fermentation,  and  next  added  to  the 
bulk  of  the  liquid.  In  the  first  case,  dry  yeasting^  as  it  is  termed,  the  yeast  is  placed 
in  a  small  tub  and  wort  poured  over  it,  and  these  substances  having  been  weU  mixed, 
the  whole  of  the  contents  of  the  vessel  are  thrown  into  the  fermentation  vats,  and 
there  worked  about  by  the  aid  of  a  stirring  pole.  According  to  the  second  method, 
wet  yeasting  or  yeast  carrying,  to  1000  maas*  of  wort,  6  to  8  maas  of  yeast  are 
added  and  well  mixed  with  about  3  eimers  of  wort,  the  mixture  being  allowed  to 
stand  for  four  to  five  hours.  After  fermentation  has  set  in,  the  fermenting  liquid  is 
mixed  with  the  wort  in  the  fermentation  tank.  The  yeast  intended  to  be  used  for 
this  purpose  should  be  obtained  from  a  former  and  normal  fermentation ;  it  should 
not  be  too  old,  and  should  possess  a  pure  odour  (not  be  foul),  thick  consistency,  and 

be  frothy. 

After  the  wort  has  been  mixed  with  the  ^east  the  following  phenomena  are  exhibited : — 
After  ten  to  twelve  hours  the  decomposition  of  the  dextrose  becomes  apparent  by  the 
evolution  of  babbles  of  carbonic  acid  gas,  which  forms  a  wreath  of  white  froth  at  the 
edge  of  the  vessel.  In  another  twelve  hours  larger  quantities  of  a  more  consistent  froth 
are  formed,  causing  the  surface  of  the  liquid  to  exhibit  a  veiy  peculiar  appearance,  which 


The  Bavarian  maas  is  equivalent  to  1*25  English  quarts. 


4i6  CHEMICAL   TECHNOLOGY. 

might  be  oompared  to  that  of  irregular  masses  of  broken  up  rooks ;  at  the  same  time  ft 
more  vivid  evolation  of  carbonic  acid  takes  place  and  becomes  perceptible  by  the  smelL 
The  German  term  for  this  phase  of  the  fermentation,  Das  Birr  Steht  im  Krausen.^  can 
hardly  be  expressed  in  English,  but  the  meaning  is  the  fermentation  is  in  fnll  force;  these 
phenomena  to  continue  with  a  regularly  proceeding  fermentation  in  full  activity  for  frcm 
two  to  four  days,  and  then  gradually  subside,  there  remaining  on  the  surface  of  the  liquid 
a  somewhat  brown-coloured  film  of  froth,  much  contracted,  and  chiefly  consisting  of  the 
resinous  and  oily  constituents  of  hops. 

The  yeast  formed  is  only  to  a  very  small  extent  present  on  the  surface  of  the  liquid* 
as  in  the  case  of  sedimentary  fermentation  the  carbonic  acid  evolved  cannot  carry  the 
isolated  yeast  cells  to  the  surface.  The  temperature  of  the  fermenting  liquid  increases 
at  the  beginning  of  the  fermentation,  so  that  the  liquid  becomes  several  degrees 
warmer  than  the  air  of  the  locality  where  the  fermenting  vats  are  placed.  By  tiie 
fermentation  the  wort  loses  the  greater  portion  of  its  dextrose,  about  half  of  which  is 
evolved  in  the  shape  of  carbonic  acid,  while  the  remainder  is  converted  into  alcohol ; 
further,  a  portion  of  the  albuminous  substances  dissolved  in  the  wort  is  rendered 
insoluble  and  deposited  in  the  shape  of  yeast.  On  being  tested  with  the  saceharometer 
the  liquid — ^for  reasons  just  explained — exhibits  after  fermentation  a  less  degree  of 
strength  than  before.  The  difference  in  percentage  shown  b^  the  saooharometer  before 
and  f3ter  fermentation  is  in  direct  proportion  to  the  quantity  of  dextrose  decomposed, 
and  provides  a  means  of  ascertaining  the  course  of  the  progress  of  the  fermentatiim. 
If  this  difiference  be  made  the  numerator  of  a  fraction,  the  denominator  of  which  is  the 
percentage  indicated  by  the  saooharometer  before  fermentation,  the  value  of  the  fraetion 
will  increase  proportionately  with  the  completeness  or  efficacy  of  the  fermentation ;  if, 
for  instance,  a  wort  before  fermentation  marks  a  saccharometrical  percentage  of  11*5, 
and  afterwards  gives  5  per  cent ;  the  difference  6*5  divided  by  11*5  gives  the  coeffident 
0*565,  that  Ib,  of  100  parts  of  malt  extract  56*5  per  cent  are  decomposed  during  fermentatioD. 

^"toT£?o2Si?°°  After  the  chief  fermentation  is  completed,  which  for  summer  or  lager 
beer  requires  nine  to  ten  days,  and  for  winter  or  schenk  beer  seven  to  eight  days,  the  young 
or  green  beer  is  put  into  barrels,  after  having  become  quite  clear  by  the  separation  of  the 
yeast.  Before  the  beer  is  vatted  the  scum  present  on  its  surface  is  removed.  The 
yeast,  settling  to  the  bottom  of  the  vat  in  which  the  fermentation  took  place  consists 
of  three  layers,  the  middle  being  the  best  yeast ;  the  lowest,  decomposed  yeast  and 
foreign  matter,  is  mixed  with  the  yeast  of  the  upper  layer,  and  if  not  otherwise 
saleable  is  sometimes  employed  in  the  distilleries  of  malt  spirits.  The  middle  layer 
aerves  for  further  fermenting  operations.  In  breweries  where  pure  water  (the  reader 
should  bear  in  mind  that  Bavaria  is  alluded  to)  is  not  to  be  had,  this  yeast  is 
occasionally  obtained  fresh  from  other  breweries.  It  is  usual  to  fill  casks  or  vats 
with  winter  beer  at  once  quite  full ;  but  as  regards  summer  beer  several  brewings 
are  mixed  in  smaller  vats  in  order  to  obtain  an  uniformly  coloured  mixture.  Tua 
barrels  are  usually  coated  with  pitch  on  the  inside,  the  aim  being  to  prevent  the  beer 
soaking  into  the  wood,  and  thus  giving  rise  when  the  cask  is  emptied  to  the  foimatioo 
of  acetic  acid.  For  the  after-fermentation  the  beer  is  placed  in  stone  cellars,  which 
should  be  as  cold  as  possible,  so  as  to  cause  the  affcor-fermentation  to  proceed  as 
slowly  as  possible,  and  thus  admit  of  the  beer  being  kept  until  the  brewing  season 
opens. 

In  all  parts  of  Germany,  but  mostly  so  in  Bavaria,  great  attention  is  paid  to  the  oan- 
struction  of  the  cellars:  often  these  cellars  are  excavated  in  rocks,  and  sometimes 
ice-pits  are  placed  in  the  cellars  to  keep  them  very  cool.  The  after-fermentatioD  of 
the  beer  sets  in  when  it  is  vatted,  the  moment  of  the  beginning  of  this  process  partly 
depending  upon  the  condition  of  t):e  beer  when  vatted  and  partly  upon  the  tempera- 
ture of  cellar.  The  after-fermentation,  which  becomes  apparent  by  the  appear- 
ance of  a  bright  white-coloured  foam  at  tlie  bung-hole,  may  set  in  immediately 
after  the  vatting  of  the  beer«  or  may  only  become  apparent  some  eight  days  afier. 
Should  tlie  beer  happen  not  to  exliibit  any  sign  of  incipient  after- fermentation. 


SEER*  417 

gre«ii,  young,  or  new  beer  is  added  for  the  purpose  of  inducing  this  process.  When 
the  after-fermentation  is  finished,  the  bungs  of  the  casks  or  tuns  are  not  tightly  fastened, 
and  the  beer  is  left  in  this  condition  (in  the  cellars  of  course)  during  the  summer 
months.  About  a  fortnight  before  the  beer  in  the  casks  is  intended  to  be  tapped,  the 
bongs  are  tightly  closed  in  order  to  cause  as  much  carbonic  acid  to  accumulate  in 
the  fluid  as  will  occasion  the  beer  to  foam  on  being  tapped ;  but  if  beer  happens 
to  be  vatted  in  very  green  condition,  the  bung-hole  should  not  remain  closed  for  so 
long  a  period,  because  then  so  violent  a  fermentation  may  set  in  that,  on  tapping  the 
cask,  its  contents  become  too  much  agitated,  and  thereby  a  very  turbid  (fuU  of 
yeast)  beer  is  served  to  the  customers.  Sometimes  the  addition  of  liqueur  (a 
solution  of  white  sugar)  is  resorted  to  for  the  purpose  of  setting  up  a  strong  fermen* 
tation  in  very  old  beer.  According  to  J.  Gschwandler  (1868)  beer  obtained  by  the 
processes  alluded  to  has  the  following  composition : — ^. 

Sedimentary 
Decoction.        Bock.  Method.        Infusion. 

Alcohol       • • 2'8io  3*380  2*940  3*130 

Sugar 1*580  2*320  1*460  1*330 

Dextrine     4*610  6*910  4*77o  4*800 

Nitrogenous  substances   03 80  0740  —  — 

Other  constituents     0*380  0*400  0890  0*550 

Sp.  gr.  of  solution  of  extract  ...  1*022  1*042  1*028  1026 

Extract  (direct  estimation)      ...  6*570  9*980  6230  6*130 

„       (according  to  Balling)  .  6*950  10*380  7*120  6680 

BmikM  vennentouon.  Surface  fermentation  is  that  induced  in  the  worts  intended  for  the 
breiivdng  of  the  bottled  beers  of  North  Germany,  Bohemia,  Alsace,  England,  and 
Belgium.  Beer  obtained  by  this  process  of  fermentation  is  not  so  lasting  as  that 
prepared  by  the  sedimentary  fermentation  process.  This  difference  is  due  to  the  fact 
that  the  surface  fermentation  goes  on  at  a  higher  temperature,  proceeds  more 
rapidly,  while  the  elimination  of  the  nitrogenous  compounds  is  also  less  com- 
plete. The  reason  why  this  process  is  preferred  to  the  sedimentary  fennentation 
process  is  that  brewing  by  the  application  of  the  last  process  is  so  greatly 
dependent  upon  a  low  temperature  tliat  this  mode  of  brewing  cannot  be  con- 
tinued throughout  the  whole  year,  while  as  regards  the  other  process  it  may  be 
continuously  carried  on,  and  the  stock  of  beer  kept  ready  for  use  can  thus  be  consi- 
derably decreased.  Surface  fermentation,  however,  is  the  only  plan  for  preparing 
briskly  foaming  and  strong  beers.  Porter,  stout,  and  ale  could  be  brewed  as  well  by 
the  sedimentary  method — although  in  tlie  English  climate  this  process  would  be 
more  difficult  to  conduct  successfully — but  the  main  reason  why  the  surface  fermen- 
tation is  employed  for  English  malt  liquors  is  that  this  method — by  a  great  saving 
of  time — is  cheaper.  The  phenomena  of  the  surface  fermentation  are  similar  to 
those  of  the  sedimentary,  with  the  exception  that  the  progress  is  by  far  more  violent, 
the  froth  surging  more  to  the  surface  of  the  wort.  The  yeast  is  employed  in  the  same 
manner.  An  ingenious  contrivance  is  adopted  in  the  London  breweries  for  the 
purpose  of  carrying  off  the  yeast  from  the  beer  after  it  has  undergone  the  process  of 
fermentation.  The  wort  is  placed  in  large  hogsheads,  or  rounds^  the  tops  of  wliich 
are  fitted  with  wooden  troughs.  Into  these  troughs  the  yeast  runs  as  it  rises,  and  ia 
carried  away.    The  beer  now  becomes  clear,  and  is  pumped  into  the  stone  vats. 

2  E 


\ 


4i8  CHEMICAL  TECHNOLOGY. 

Btmgn  Browing.  The  extensive  application  of  steam  to  the  mannfaetare  of  beet-root  sngar 
and  alcoholio  spirits  has  given  rise  to  many  Buggestions  for  the  sabstitution  of  heating  by 
steam  for  direct  firing  in  brewing.  The  heating  is  effected  by  a  system  of  tabes  aiimlar 
to  that  described  in  the  preparation  of  beet-root  sugar  (see  p.  377).  In  brewing,  how- 
ever, though  much  would  be  gained  by  uniformly  heating  the  worts,  and  by  reducing  the 
chances  of  burning,  there  would  not  ensue  any  great  economising  of  fuel;  but  much 
labour  might  be  saved.  Steam  could  not  be  employed  directly  without  a  series  oi  tubes, 
as  the  condensation  would  cause  a  great  dilution  of  the  mash. 

ooBstuaentsof  B«tt.  The  Constituents  of  a  normal  beer  prepared  from  malt  and  hops 
(not  from  snbstitates)  are : — Alcohol,  carbonic  acid,  undecomposed  dextrose,  dextrine, 
constituents  of  the  hops  (oil  and  bitter  substance,  no  tannic  acid),  protein  substances, 
a  small  quantity  of  fat,  some  glycerine,  and  the  inorganic  matter  of  the  barley  and 
hops.  The  acid  reaction  which  a  normal  beer  exliibits  after  the  carbonic  acid  has 
been  expelled  from  it  by  boiling,  is  due  to  succinic  and  lactic  adds,  with  traces  of 
acetic  acid,  and  perhaps  propionic  acid.  The  sum  of  all  the  constituents  of  a  beer 
after  the  abstraction  of  the  water  is  termed  the  total  contents ;  the  sum  of  the  non- 
volatile constituents,  the  extractive  contents.  Beer  rich  in  malt  extract  is  termed 
rich,  fat,  or  fall-bodied  beer;  and  that  which  is  poor  in  extract,  but  contains  much 
alcohol,  the  wort  having  been  rich  in  sugar  which  has  all  been  converted,  Ib  termed 
a  dry  beer. 

The  proportion  of  alcohol  in  beer  can  be  estimated  by  distillation  and  the  testing 
of  the  distillate  with  an  alcoholometer,  or  by  means  of  an  ebollioscope,  or  with  the 
help  of  a  vaporimeter  (see  Wine-testing,  p.  394).  The  following  table  shows  the 
average  weight  per  cent  of  the  alcoholic  contents  of  several  beers : — 

Percent. 
Wirtzburg  lager  beer  (1870)      40 — 43 


„         schenk  beer 
Stuttgardt  lager  beer  (1865) 
Gulmbach  lager  beer  (1865) 

Coburg  lager  beer       

Munich  lager  beer      

„      schenk  beer 

Bock  (Munich,  1870) 


3'3— 42 

41 

45 

44 

4*3— 51 
3-8— 40 

4'3— 4-8 


Porter  (Barclay,  Perkins,  and  Co.,  London,  1862)        ...  55 — 7*0 

Strasburg  beer  (1870) 4'2i 

Vienna  beer  (1870)      4*1 

Bice  beer  of  the  "  Rlienish  Brewery"  in  Mentz   36 

The  quantity  of  carbonic  acid  in  beer  varies  between  01  to  o'z  per  cent 
According  to  C.  Prandtl  (1868)  dextrose  is  found  in  beer  in  quantities  varying  frooi 
o'2  to  I  9  per  cent.  The  quantity  of  dextrine,  according  to  Gschwandler's  analyses, 
varies  from  46  to  4*8  per  cent.  The  proportion  of  sugar  to  dextrine  is  never 
constant.  The  occurrence  of  protein  substances  in  beer  has  not  been  sufficiently 
investigated  to  warrant  an  exact  conclusion.  It  may  be  said  that  on  an  average 
malt  extract  contains  7  per  cent  protein  substances,  from  which  Mulder  deduces  that 
I  litre  of  beer  should  contain  56  ^er^  cent  albuminous  substances.  A.  Vogel  (1859^ 
found  that  i  Bavarian  maas  (=  1069  litres)  of  beer  on  an  average  contained 
I  to  1*2  grms.  nitropjen ;  and  Feichtinger  (1864)  obtained  from  i  Bavarian  maas  of 
several  Munich  beers  between  0467  and  1248  grms.  nitrogen.  Succinic  acid. 
acetic  acid,  and  lactic  acid  occur  in  Belgian  and  Saxony  beers  in  large  quantities. 
Tannic  acid  occurs  in  Bavarian  beers   only  in  small  quantity.     The  inorganic 


BEER.  4x9 

ooDstitnents  of  beer  have  received  great  attention.  Martins  obtained  from  1000  parts 
of  Bavarian  lager  beer  2*8  to  3' 16  parts  ash,  containing  one -third  potash,  one-third 
phosphoric  acid,  and  one-third  magnesia,  lime,  and  silica.  J.  Gschwandler  and 
C.  Prandtl  (1868)  found  an  average  extractive  contents  in  100  parts  of — 

Parts. 

Schenk  beer  (Munich) * 5*5~~~^'o 

Lager  beer  (Munich)    6*1 

Schenk  beer  (Wirtzburg)     4*6 

Lager  beer  (Wirtzburg)       4'4 

Bock  (Munich)       8*6—9*8 

Salvator  (Munich)        9'(>— 9*4 

*Hhenish  rice  beer 7*3 

Porter  (Barclay,  Perkins,  and  Co.,  London)     5*6 — 69 

Scotch  (Edinburgh)      10*0— ii'o 

Burton  ale      i4'o — 19*29 

100  parts  of  extractive  matter  contain,  according  to  A.  Vogel  (1865)  3*2  to  3'5  parts 
of  ash ;  100  parts  of  ash  contain  28  to  30  parts  phosphoric  acid,  i  litre  of  beer 
contains  057  to  093  grm.  of  phosphoric  acid. 

Lermer  (1866)  subjected  several  Munich  beers  to  analysis  with  the  following 

results : — 

I.  2.  3.  4.  5.  6.  7. 

8p.  gr 102467  10141  101288  10200  102678  1*03327  1-0170 

per  ct.  per  ot.  per  ct.  per  ot.  per  ct.  per  ot.  per  ct. 

Extractive  matter 773  493  437        455  8*50        963  592 

Alcohol    508        3*88  3*51        4*41  5*23        4*49  3*00 

Inorganic  constituents  ...    c 28  023  0*15        o*i8  —  —  — 

Nitrogen : — 

9         Li  100  parts  extract ...  1115  871  12*19        8-85  —  699         — 

„    100^   „     beer      ...    087  043  0*53  039  —  0*67         — 

I.  Bock  beer.  a.  Summer  beer.  3.  White  beer.  4.  White  Bock  beer  (superficially 
fermented,  obtained  by  surface  fermentation  from  malted  wheat).  5.  Another  sample  of 
Bock  beer.    6.  Salvator  beer.    7.  Winter  beer. 

The  analysis  of  the  ash  of  five  of  these  beers  gave : — 

I.  2.  3.  4.  5- 

Potash    29*31  33*25  24-88  3468  29*32 

Soda      i'97  045  2023  4*19  o'" 

Chloride  of  sodium      ...  4-61  6*00  656  506  600 

Lime      234  2*98  258  3*14  621 

Magnesia       11-87  8'43  ^'34  777  775 

Oxide  of  iron        loi  o'li  047  0*52  084 

Phosphoric  acid   34*18  3205  26-57  2985  29*28 

Sulphuric  acid     1-29  271  6*05  5*16  4*84 

Silicic  acid 12*43  I4'^2  7*70  2*86  8*oi 

Sand      0-83  067  2*30  5*20  6*27 

Carbon 049  o*8i  0*40  0*65  028 

100-33       ioi'47        9S"3        9908        9^9^ 

/  2£2 


420  CHEMICAL  TECHNOLOGY. 

The  high  importance  of  beer,  both  as  regards  its  valne  as  nntriment  as  well  as  legards 
the  enormons  trade  done  in  this  article,  has  given  rise  to  attempts  to  find  proper  and 
saitable  means  for  testing  that  liquid  in  respect  of  its  quality  and  parity. 

Beer-Testing.  The  experiments  proposed  for  ascertaining  the  strength  as  well  as 
freedom  from  adulteration  of  beer,  is  termed  beer- testing ;  it  is  desirable  that 
these  operations  should  be  easily  executed  and  yield  sufl&ciently  reliable  results. 
The  strength  of  a  beer  is  judged  according  to  the  quantity  of  alcohol,  extract, 
and  carbonic  acid  it  contains ;  it  is  evident,  however,  that  an  intimate  knowledge 
of  the  real  constituents  of  the  extract,  viz.,  the  therein  contained  quantities  of 
dextrine,  hop  constituents,  the  by-products  of  alcoholic  fermentation,  such  as, 
for  instance,  succinic  acid  and  glycerine,  not  to  mention  such  substances  as,  for 
instance,  glucose  and  glycerine  purposely  added  to  the  wort,  as  substitutes  for  malt, 
largely  influence  the  quality  of  any  kind  of  beer,  and  tlierefore  ought  to  be  deter- 
mined when  any  rigorously  exact  analysis  of  that  liquid  is  wanted. 

Beer-testing  is  effected  partly  by  ascertaining  certain  physical  qualities  of  the  beer, 
partly  by  chemical  means.  To  the  former  belong  its  flavour,  odour,  colour,*  consistency, 
transparency,  specific  gravity,  refractive  power  to  light,  &c.  By  chemical  analysis 
we  ascertain  and  determine  the  immediate  constituents,  viz.,  carbonic  acid,  alcohol, 
extractives,  and  water.  The  carbonic  acid  contained  in  the  beer  is  first  eliminated 
eitlier  by  repeatedly  i)ouring  a  quantity  of  beer  from  one  tumbler  or  beaker-glass 
into  another,  care  being  taken  to  let  the  beer  fall  from  some  height,  or  the  carbonic  acid 
is  removed  by  shaking  the  liquid  up  in  a  bottle  and  pouring  it  out  of  the  same  and 
into  it  again.  The  gas  having  been  driven  ofi*,  the  specific  gravity  of  the  beer  is 
taken  by  means  of  the  hydrometer  or  saccharometer;  the  beer  is  next  boiled  down  to 
half  its  original  bulk ;  next  there  is  added  to  it  as  much  water  (best  distilled)  as  is 
required  to  restore  the  liquid  to  its  original  bulk,  and  of  this  liquid  the  specific 
gravity  is  again  determined ;  this  will  be  found  greater  than  that  previooaly 
obtained.  The  difference  between  the  two  determinations  gives  the  amount  of  alcohol 
contained  in  the  beer. 

®*^^''^?TSt!"**^'*^  Since  by  fermentation  loo  parts  of  malt  extract  yield  50  parts 
alcohol,  twice  the  quantity  of  alcohol  found  will  indicate  the  quantity  of  malt  extract 
necessary  for  its  formation.  This  quantity  of  malt  extract  added  to  that  still 
existing  in  the  beer  indicates  the  whole  of  the  malt  extract  existing  in  the  wort 
before  fermentation. 

The  specific  gravity  of  the  beer- wort  becomes  lower  by  fermentation,  partly  because 
the  specifically  lighter  alcohol  is  formed,  partly  by  tlie  loss  of  some  of  the 
extractive  matter,  and  partly  also  by  the  loss  of  the  substances  taken  up  in  the  yeast 
Tliis  decrease  of  the  specific  gravity,  or  attenuation,  as  it  is  termed,  can  be  estimated 
either  directly  by  weighing,  or  by  means  of  the  saccharometer.  The  degree  marked 
by  the  saccharometer  in  a  beer  freed  from  carbonic  acid  we  will  call  m;  the  malt- 
extract  of  the  wort,  p.  Subtracting  m  from  p,  the  difference  (p—m)  gives  the 
apparent  atUntMthn,  which  is  the  greater  the  more  thorough  the  fermentation. 
The  quantity  of  alcohol  in  a  beer  varies  in  direct  proportion  with  the  apparent 
attenuation.  The  empirical  alcohol  factor,  a,  by  which  the  apparent  attenuation 
must  be  multiplied  to  obtain  the  alcoholic  contents  of  the  beer  =  A  in  weight  per 

•  Very  recently,  C.  Leyser  has  invented  a  colorimeter  with  which,  by  means  of  • 
nrirmal  solution  of  iodine  (127  grms.  iodine  to  a  litre)  after  having  brought  the  beers  to 
fin  equal  colonration  with  water,  he  estimates  the  relative  degree  of  the  original  eolonr. 
Ti:e  invention  is  fully  described  in  the  "  Jahresberiohte  der  Chem.  Technologie  "  for  1869, 
V-  467- 


BEER.  421 

eent  [(p-m)a=A]  becomes  the  greater,  the  higher  the  original  degree  of  concen- 
tration of  the  wort.  P'or  worts  between  6  to  30  per  cent  of  extractive  matter,  this 
factor  varies  from  04079  to  o'4588.  The  alcohol  factor  can  be  found  by  the  follow- 
ing equation,  when  the  apparent  attenuation  (p  —  m)  and  the  alcoholic  contents  of 

the  prepared  wort  (A)  are  known;  then  a  =  (  ).      With  the   help  of  the 

alcohol  fftctor,  a,  the  alcoholic  contents  in  weight  per  cent  can  be  calculated.  A 
quantity  of  beer  being  boiled  to  volatilise  the  alcohol,  and  the  residue  having  been 
diluted  with  water  to  the  original  bulk  or  weight,  if  a  weighed  quantity  were 
operated  with,  the  specific  gravity  gives  the  quantity  of  extractive  matter  contained 
in  the  beer,  which  Balling  terms  n.  The  difi'erence  between  the  extractive  matter 
contained  in  the  wort  {j))  and  that  of  the  beer  (n),  or  (jp—n),  gives  the  actual 
atUttuatwn^  which,  multiplied  by  the  alcoJiol  factor  for  the  actual  attenuation  [h)^ 
likevdse  gives  the  quantity  of  alcohol  contained  in  the  beer  expressed  in  percentage 

by  weight.    The  alcohol  factor  for  the  actual  attenuation  is  6  =  ( ).   Sub- 

\p — n/ 

tracting  firom  the  apparent  attenuation  (p—m)  the  actual  (p-n)^  the  difference  (d) 

in  the  attenuations  is  obtained : — 

d=(p— m)  — (p— n) ;  or  <f=m— «. 

d  is  known,  when  the  extractive  matter  contained  in  the  beer  [n)  and  the  saccharo- 

metrical  percentage  (m)  of  the  beer  free  from  carbonic  acid  are  known;  c/is  the  greater 

the  more  alcohol  the  beer  contains.     The  alcohol  factor  multiplied  by  the  diiierence 

in  attenuation  gives  the  percentage  (A)  of  alcohol,  from  wliich  the  alcohol  factor  for 

the  difference  in  attenuation  can  be  obtained  by  the  following  equation : — 

A 


0= 


(p  —  m) 
It  averages  2*24.    Finally,  with  the  help  of  c  the  difference  in  attenuation  of  th^ 
alcoholic  contents  of  a  beer  can  be  calculated  approximatively,  even  when  the  quantity 
of  extractive  matter  of  malt  contained  in  the  wort  is  not  known.    The  apparent 
divided  by  the  actual  attenuation  gives  a  quotient  (d),  which  is  the  ratio  of  the 

attenuations,  d  =  ^-H!^'  and  can  be  calculated  with  the  help  of  the  alcohol  factor 

p  —  n 

for  the  apparent  attenuation  (a),  and  of  the  original  extractive  contents  of  the  wort 

(p).    First — (a)  is  obtained  by  the  division  of  the  alcohol  factor   for  the  actual 

attenuation  by  the  corresponding  attenuation  quotient   or   ratio.     Assuming  tlie 

alcohol  factor  for  the  difference  in  attenuation  to  be  =  2*24,  and  next  doubling  the 

approximative  alcoholic  contents  thus  obtained,  we  arrive  at  the  quantity  of  the 

extractive  matter  of  the  wort  from  which  the  alcohol  was  formed.    Adding  to  this 

the  extract  yet  met  with  in  the  beer,  the  sum  thus  found  expresses  the  approximate 

percentage  of  the  extractive  contents  of  the  wort.     When  (p)  has  thus  been  approxi- 

mately  obtained,  Balling's  tables  give  the  corresponding  attenuation  quotient  9, 

reckoning  all  decimals  above  0*5  as  units,  and  neglecting  those  under  0*5.    If  only 

the  original  concentration  of  the  wort  (p)  is  to  be  calculated,  the  percentage  of  the 

alcohol  of  the  beer  may  be  obtained  from  the  equation  to  the  actual  attenuation 

A  =  {p  —  n)b.     If  the   degree   after   fermentation  is  975  or  (16*29  -*  6-54),  the 

saccharometrical  percentage  (see  p.  363) 

975 
= =o'542. 

i6'29 


431 


CBE3IICAL  TECHNOLOOT. 


common  sftlt  1=  2778  : 1] 


FBciu'iBHtTiiM.  RaUinutrical  littr  Tett. — Fuche'a  test,  l>ased  upon  the  presnmptioii 
that  the  beec  has  b«en  brewed  from  malt  and  hops  only,  starta  from  the  fact 
that  100  parts  of  water,  iDdependeDtlj  of  temperature,  dissolve  36  parts  of  pnio 
) ,  and  that  a  fiuid  dissolves  the  less  salt  the  greater  the 
qaantitj  of  alcohol  and  extracttTe  matter  it  coataius.  It 
is  thcrGfore  possible  to  estimate  b;  this  meaufl  th* 
qoantity  of  water  in  a  beer  b;  determining  the  qoantitT 
of  common  salt  which  remains  oudisaolved ;  this  is  dona 
by  means  of  the  hallimeter.  Fig.  232,  an  instnunont  oon- 
sisttDg  of  two  glass  tabes,  one  very  wide  and  cup-shaped, 
the  other  narrower  and  attached  to  the  bottom  of  the 
former.  The  smaller  tube  is  so  gradnaled  that  the 
larger  divisions  correspond  to  a  quantity  of  5  grMns  of 
common  salt,  while  the  smaller  divisions  correspond  to 
I  grain  of  salt.  In  all  hollimetrical  experiments  it  is 
very  essential  that  the  pulverised  common  salt  be 
always  as  much  as  possible  of  the  same  degree  of 
fineness,  while  care  has  also  to  be  taken  that  this  sub- 
stance be  rednced  to  its  smallest  bnlk  when  put  into 
the  tube  by  gentle  taps,  so  as  to  expel  air.  and 
thus  cause  the  salt  to  occupy  exactly  the  space  intended 
for  it.  It  is  therefore  required  to  pass  the  pulverised 
salt  through  a  nire-gnuze  sieve,  after  which  the  pre- 
pared salt  is  kept  for  use  in  a  glass -stoppered  bottle. 
The  testing  requires  two  experiments.  By  the  first  is  estimated  the  amonnt 
of  water  together  with  the  entire  quantity  of  carbonic  acid,  alcohol,  and  extractive 
matter  contained  in  the  sample;  while  the  second  experiment  gives  the  quantity 
of  extractive  matter,  which  when  the  carbonic  acid  is  deducted  from.tha  total 
contents,  yields  the  amonnt  of  alcohol  contained  in  the  beer.  The  alcohol  is 
not  anhydrous,  bat  is  mixed  with  a  certain  quanti^  of  water.  1000  grains  (62*jgniis.) 
of  the  beer  to  be  tested  are  poured  inte  a  flask  with  330  grains  (zo'46  grms.)  of  the 
common  salt.  The  flask,  lightly  closed  with  a  stopper  or  cork,  is  freqnautly 
agitated,  and  having  been  placed  on  a  water-bath  is  heated  to  38°,  After  six  to  ten 
minutes  the  flssk  is  removed  from  the  water-bath,  the  carbonic  acid  being 
expelled  by  gently  blowing  into  the  flask,  which  is  next  weighed ;  the  loss  of  weight 
indicates  the  quantity  of  carbonic  acid,  which  in  good  beer  averages  i'5  grains. 
The  month  of  the  flask  having  been  closed  with  the  thnmb  is  turned  upside 
down  in  order  thereby  to  collect  any  non-dissolved  salt  in  the  neck  of  the  flask, 
and  the  salt  along  with  the  fluid  transferred  to  the  hallimeter,  the  non-dis- 
solved salt  settling  down  in  the  graduated  tube,  this  movement  being  promoted 
by  gently  shaking  the  instrument.  As  soon  as  the  volume  of  the  undissolved  s*lt 
ceases  to  increase,  the  number  of  grains  is  read  ofl'  and  deducted  from  330,  tba 
difference  being  the  number  of  grains  dissolved  from  which  the  quantity  of  mter 
present  is  calculated. 

Example;  1000  grains  (=-61-5  grms.)  of  beer  dissolve  330  —  18  =  31a  grains  eoBumsi 

salt ;  therefore  these  1000  grains  of  beer  conlatu  8666  graine  of  vatet ;  for 

36:ioo=3IJ:x, 

.-.     I -.866-6 

"ooo  — 866'6  =  i33-,f  grains  indicate  the  total  quantity  oJ  carbonic  acid,  eilisctivc  m*IK'> 


BEER. 


423 


and  alcohol  present  in  the  heer.  If  the  contents  of  the  flask  by  heating  have  lost 
z'5  grains  in  weight,  the  extractiye  matter  and  alcohol  together  amount  to  13 1-9  grains. 
The  second  experiment  is  now  made  to  estimate  the  amonnt  of  extractiye  matter.  For 
this  purpose  zooo  grains  (62*5  grms.)  of  beer  are  weighed  off  and  poured  into  a  flask,  and 
boiled  down  to  half  the  quantity,  that  is,  500  grains.  Both  the  carbonic  acid  and  the 
alcohol  are  driven  off.  180  grains  of  common  salt  are  now  added,  and  the  experiment 
proceeded  with  as  before.  Supposing  180  —  20  b  160  grains  of  common  salt  to  be  dissolved, 
there  will  have  remained  444*4  grains  of  water ;  for 

18  :  50  =  160  :  X 
.  • .   X  =  444*4, 

which  shows  the  quantity  of  the  extractive  matter  to  be  55*6  grains.  If  the  preliminary 
estimation  of  the  carbonic  acid  has  been  correct,  the  quantity  of  alcohol  contained  in  the 
beer  will  bo  76-3  grains,  for  ^33*4  —  55*6  —  1*5  =  76*3.  This  corresponds,  according  to  a 
table  published  with  each  instrument,  to  42*27  grains  of  absolute  alcohol.  The  beer 
would,  therefore,  contain  in  1000  parts  : — 

Carbonic  acid 1*50 

Free  water       866-60 

Combined  water      34'03 

Extractives      55 '60 

Alcohol     42*27 


1000*00 


7471 

I -06 
3-06 

728 

3-87 
11*22 

4-i8 
12-10 

1*70 
6*26 

13*21 

6*23 
22*89 
48-51 

100*00 

6*72 
24*71 
52-29 

lOO'OO 

100*00 

The  hallimetrical  assay  of  beer  is  entirely  worthless  when  beer  is  made  with  the  addition 
of  glucose  or  glycerine. 

BT-produeta  of  the  Among  the  by-products  of  brewing  the  residue  of  the  mash  tuns  is 
Brewing  proocsf.  perhaps  the  most  important.  100  parts  of  kiln-dried  malt  leave  on 
an  average  133  parts  of  residue,  which  being  dried  at  the  temperature  to  which  the  malt 
was  subjected  give  33  parts.  It  is  used  as  fodder  for  cattle  under  the  name  of  brewers^ 
grains.  This  material  yet  contains,  in  addition  to  the  husks  and  cellulose  of  the  grain, 
imdecomposed  fatty  matter  and  protein  substances,  upon  which  its  value  depends. 
Exhausted  mashed  grain  from  a  Munich  brewery  used  to  prepare  summer  beer  (by  the 
thick  mash  method)  had  the  following  composition : — 

Wet  Grains.        Air-dried.        Dried  at  100°. 

Water        

Ash 

Cellulose 

Fat     

Nitrogenous  nutritive  matter 
Non-nitrogenous  nutritive  matter 


The  rootlets  and  plumules  of  the  germinated  malt  present  in  the  proportion  of  about 
3  per  cent  of  the  weight  of  the  dried  malt,  form  a  very  concentrated  and  rich  fodder. 
According  to  the  analyses  of  Scheven,  Way,  and  Lermer  (Hungarian  barley),  the 
following  is  the  composition  of  that  substance : — 

Scheven.  Way.  Lermer. 

Water       7*2  3*7  10-72 

Ash 6*8  5-1  6'9i 

Cellulose 17*0  18-5  — 

Protein  substances        45-3  48*9  32*40 

Non-nitrogenous  nutritive  matter       23-6  23*8  4977 

The  sediment  of  the  cooling  tuns  (see  p.  414),  part  of  which  is  used  as  fodder  and  part 
in  the  preparation  of  brandy,  amounts  to  about  3  per  cent  of  the  wort.  The  after- 
washes  are  also  used  in  malt  spirit  making,  as  well  as  in  the  preparation  of  vinegar.  The 
thick  mash  processes  yield  an  after  wash  containing  from  4  to  8  per  cent  extract, 
wliile  by  the  infusion  methods  this  amounts  only  to  2  to  3  per  cent.  Much  of  the  yeast 
formed  during  brewing  is  employed  in  bread  making,  as  well  as  in  the  manufacture  of 
vinegar  and  brandy. 

if 


424  CHEMICAL  TECHNOLOGY. 

The  PrepaililTion  ob  Distcllation  of  Spirits. 

AioohoL      Since  alcohol  happens  to  be  in  almost  all  countries  an  article  which  in  s 
nearly  pure  state  (that  is  to  say  more  or  less  diluted  with  water)  is  a  fluid  used  as  an 
article  of  consumption,  and  therefore  very  properly  submitted  to  a  moare  ox  less 
heavy  duty  or  impost,  the  mode  of  manufiarcturing  alcohol  on  the  large  scale,  and 
the  raw  materials  from  which  it  is  obtained,  vary  in  different  countries,  and  conse- 
quently these  conditions  very  greatly  influence  the  industry  of  alcohol  production. 
When  a  fluid  containing  alcohol  is  distilled,  alcohol  and  water  are  collected  in  the 
receiver,  while  the  non-volatile  constituents  remain  in  the  retort  in  a  concentrated 
condition.    The  act  of  distillation  of  an  alcoholic  fluid  is  termed  the  brenn^n*  while 
the  product  of  the  operation  is  designated  as  brandy,  a  fluid  which  contains  on  an 
average  from  40  to  50  per  cent  of  alcohol.    A  distillate  which  contains  more  alcohol 
than  the  quantity  just  alluded  to  is   designated  as  spirits  of  wine,  or  simplj 
spirit.      Originally,    that   is   to   say    when    spirits   (now   some   two  and  a  half 
centuries  ago),  were  first  commenced  to  be  made  industrially  on  the  large  scale, 
it  was  only  made  for  the  purpose  of  being  drunk,  and  the  liquor  prepared  in 
the  comparatively  dilute   state   in  which  it  is  ofiered  for  sale  for  consumption. 
More  recently  (within  the  last  forty  to  fifty  years),  the  use  of  alcohol  in  varioui 
branches  of  industry  (varnish-making,  ether  preparation,  perfumery,  preparation  of 
cordials,  liqueurs,  &c.)  is  so  great,  that  as  a  rule  distillers  at  once  prepare  strong 
alcohol,  which,  if  required  for  consumption  as  a  beverage,  is  suitably  diluted  and 
sweetened  if  desired.     Since  the  distillation  of  alcohol  has  been  carried  on  on  the 
large  scale  the   apparatus  have  been  very  greatly  improved ;   and  those  now  in 
use  in  the  best  arranged  distilleries  are  constructed  upon  scientific  principles,  while 
care  is  also  taken  that  the  surveillance  on  the  part  of  the  excise  officers  is  rendered 
an  easy  task,  and  fraud  almost  impossible.    The  whole  art  of  the  production  of 
alcohol — ^its  ready  preparation  from  grain  (partly  malted),  from  beet-roots*  potatoes, 
refuse  of  saccharine  liquors  from  sugar  works,  the  proper  utilisation  of  the  residnes  of 
the  distillation,  either  ds  food  for  cattle  or  otherwise — ia  now  brought  to  a  degree 
of  perfection  almost  unequalled  in  any  other  branch  of  industry. 
^S>Sit  ftS^S;"^      The  formula  of  alcohol  (as  a  chemicaUy  pure  substance)  is 

C  H  ) 
CaHeO,  or     ^  ^  [  ^-    It  is  a  colourless,  thin,  very  mobile  fluid  of  0792  sp.  gr., 

boiling  at  78*3°,  while  water  boils  under  the  same  atmospheric  pressure  at  100^ ;  thus 
there  is  afbrded  a  means  of  ascertaining  by  the  boiling-point  of  an  alcoholic  fluid,  the 
quantity  of  alcohol  contained.  Between  0°  and  jS's^  (its  boiling-poiat),  alcohol 
expands  o  0936  of  its  volume,  while  the  coefficient  of  expansion  of  water  between 
the  same  degrees  is  0*0278.  The  expansion  of  alcohol  is  thus  3i  times  greater  than 
that  of  water ;  and  this  fact  is  made  available  in  alcoholometry.  The  tension  of  the 
vapour  of  alcohol  at  783^  is  equal  to  an  atmosphere,  while  water  must  be  raised  to  ft 
temperature  of  100°  to  obtain  the  same  pressure.  Thus,  the  varifition  in  height  of  & 
column  of  mercury  subjected  to  the  pressure  of  these  vapours  may  be  made  a  mea- 
sure of  the  quantity  of  alcohol  contained  in  a  fluid.  On  this  -principle  the  vapori- 
meter  (see  p.  395)  is  constructed.  Alcohol  is  readily  inflammable,  and  bums  with  a 
pale  blue  flame  without  giving  ofl"  soot.     Its  heat  of  combustion  corresponds  to  71S3 

*  There  is  no  equivalent  term  for  this  word  in  English  neither  also  in  the  French  lan- 
guage; the  real  meaning  is  "the  firing,"  in  Dutch  (branden) ;  the  term  Bretmerti 
(German),  and  brandery  (Dutch),  meaning  "  a  distillery." 


SPIRITS.  425 

units  of  heat.  It  eagerly  absorbs  water,  and  upon  this  property  is  based  its  use  for 
the  preservation  of  articles  of  food,  cherries,  and  other  fruit,  and  also  anatomical 
preparations.  It  mixes  with  water  in  all  proportions,  whereby  a  decrease  of  bulk 
of  the  mixture  and  increase  of  specific  gravity  is  observed — 

53 '9  volumes  of  alcohol,  with 

49*8         „         water,  form  a  mixture  not  of 

1037,  but  of  100  volumes. 

Alcohol  is  a  solvent  for  resins  (upon  which  property  is  based  its  application  to  the 
manu&cture  of  varnishes,  cements,  and  pharmaceutical  preparations),  and  also  a 
solvent  of  many  essential  oils.  These  solutions  are  employed  either  as  perfumes,  such 
as  eau  de  Cologne,  or  as  liqueurs,  cordials,  and  aqua  vits,  or  as  spirits  for  burning 
in  lamps,  as,  for  instance,  the  mixture  of  oil  of  turpentine  and  alcohol,  so-called  fluid 
gas;  alcohol  also  dissolves  carbonic  acid  gas,  a  property  made  available  in  the 
malring  of  efifervescing  wines. 

By  the  influence  of  certain  oxidising  agents  alcohol  is  converted  first  into  aldehyde 
luid  next  into  acetic  acid,  as  illustrated  in  the  so-called  quick  vinegar  making 
process.  Alcohol  does  not  dissolve  common  salt,  and  upon  this  property  Fuchs's  test 
(see  p.  422)  is  based. 

By  the  action  of  most  of  the  stronger  adds  aided  by  heat  alcohol  is  converted 
into  what  are  termed  ethers  ;  as  regards  the  action  of  sulphuric  acid  upon  alcohol,  it 
depends  upon  the  relative  quantities  and  degree  of  concentration  of  these  liquids, 
whether  sulphovinic  acid,  ether,  or  bicarburetted  hydrogen  gas,  be  formed. 
Hydrochloric  acid  forms  with  alcohol  chloride  of  ethyl  or  hydrochloric  ether. 
Butyric  and  oxalic  acids  form  ethers  directly  when  heated  along  with  alcohol ;  but 
most  of  the  other  organic  adds  require  the  addition  and  the  aid  of  sulphuric  or 
hydrochloric  acid  for  this  purpose.  Alcohol  is  the  intoxicating  prindple  of  all 
spirituous  liquors. 

^^JilSSfiSw.*'"*  Alcohol  is  always  the  product  of  vinous  fermentation.  The 
manufacture  of  spirits  therefore  indudes  three  principal  operations : — 

J,  The  preparation  of  a  saccharine  fluid. 

2.  The  fermentation  of  this  fluid. 

3.  Separation  of  the  alcohol  by  distillation. 

All  saccharine  fluids,  therefore,  or  those  substances  which  yield  alcohol  by  fermen- 
tation, can  be  employed  in  the  manufacture  of  spirit ;  and  all  materials  so  employed 
contain  already  dther  completdy  formed  alcohol,  or  cane  sugar  and  dextrose,  or 
finally  substances  which  by  the  influence  of  diastase  or  dilute  adds  are  converted 
into  dextrose.  Such  substances  are  starch,  inuline,  lichenine,  pectin  compounds,  and 
cellulose.  The  raw  materials  of  spirit  manufacture  may  be  generally  classed  in. the 
three  following  groups : — 

ut  Group, — Fluids  in  which  the  alcohol  is  already  present,  requiring  only  distil- 
lation to  eflect  its  separation.    Such  fluids  are  wine,  beer,  and  dder. 

2nd  Group, — Substances  either  solid  or  liquid  which  contain  sugar,  which  may  be 
either  cane  sugar,  or  dextrose  and  levulose,  or  sugar  of  milk.  In  this  group  are 
induded  the  beeVroot,  carrot,  sugar-cane,  maize  stalk,  the  Chinese  sugar-cane 
(iorgkum),  some  kinds  of  fruit — ^viz.,  apples,  cherries,  figs,  some  berries  (grapes, 
mountain  ash  berries,  &c.),  the  melon  and  gourd,  some  frxuts  of  the  cactus  tribe,  the 


426  CHEMICAL  TECHNOLOGY. 

molasses  of  cane  and  of  beet-root  sugar  manufacture,  the  marc  of  grapes  and  reliue 
grain  of  beer  making,  honey,  and  milk. 

^rd  Group. — ^All  substances  which  originally  contain  neither  alcohol  nor  sugar,  but 
the  constituents  of  which  may  be  converted  into  sugar  and  dextrose.  Such  are 
starch,  inuline,  lichenine,  pectin  compounds,  and  cellulose,  chiefly  found  in — 

a.  Roots  and  bulbs :  Potatoes,  dahlia  roots,  &c. 

b.  Cereals :  Hye,  wheat,  barley,  oats,  maize,  and  rice. 

e.  Leguminous  and  other  seeds :  Buck-wheat,  millet,  black  or  negro  millet,  peas, 
lentils,  beans,  vetch,  chestnut,  horse-chestnut,  oak  leaves,  &c. 

d.  Substances  containing  cellulose:   Sawdust,  paper,  straw,  hay,  leaves,  osier, 
moss. 

In  the  future  a — 

^h  Group  may  perhaps  be  added,  which  will  embrace  all  substances  as  probably 
may  enter  into  the  synthetic  preparation  of  alcohol,  and  thus  form  what  might  be 
called  a  mineral  spirit  Berthelot  in  1855  proved  that  alcohol  can  be  formed  from 
defiant  gas  and  water  (C2H4-|-H20=CaH60).  Olefiant  gas,  when  agitated  for  a 
length  of  time  with  concentrated  sulphuric  acid,  gives  rise  to  the  formation  of 
sulphovinic  add;  and  from  this  liquid  after  having  been  diluted  with  water 
a  dilute  alcohol  can  be  distilled.  This  experiment  has  as  yet  only  a  scientific 
interest;  the  process  has  been  tried  on  the  large  scale  in  France,  but  failed  to  be  com- 
mercially available. 

a.  Preparation  of  a  Vinous  Mash. 

vincnuMMiifromCereftiB.       Grain  brandy  (com  brandy)  may  be  prepared  from  either 

wheat,  rye,  or  barley.     Generally  more  than  one  kind  of  grain  is  used,  because 

experience  has  proved  that  a  larger  quantity  of  alcohol  is  obtained  when  two  kinds 

of  grain — ^for  instance,  wheat  and  barley,  rye  and  barley — are  mixed.    A  mixture  of 

rye  with  wheat  or  barley  malt,  or  wheat  with  barley  malt,  is  very  generally  used,  at 

least  abroad.    To  i  part  of  malt  from  2  to  3  parts  of  non-malted  grain  are  usually 

taken.    Either,  as  is  done  in  England,  wort  is  made,  the  grain  being  first  malted, 

next  mashed,  and  the  wort  drawn  off,  or  the  mixture  of  malt  and  unmalted  grain  is 

allowed  to  ferment  together.    The  latter  method  is  more  usual  in  Germany,  and  will 

be  that  described  in  this  work.    In  Russia  and  Sweden  brandy  is  prepared  without 

malting ;  by  properly  mashing  rye  meal  a  reaction  ensues  between  its  constituents, 

the  effect  of  which  is  the  same  as  if  it  had  been  acted  upon  by  diastase  of  malt. 

The  preparation  oi  a  mash  from  grain  may  be  considered  as  oonsiflting  of  the  foUoving 
four  operations : — 

1.  The  Bruising. — The  materials,  malted  as  well  as  umnalted  grain,  are  first  braised. 
As  it  is  not  essential  in  the  manufacture  of  spirits  that  a  clear  wort  should  be  prepared, 
the  grain  may  be  broken  up  very  small,  whereby  the  formation  of  sugar  is  rendered  man 
complete.    Qreea  malt  is  now  generally  considered  preferable  by  many  distillers. 

2.  The  Mixing  tcith  Water.—  Making  of  Mash. — This  operation  is  almost  identical  with 
that  of  the  mashing  of  the  brewer ;  the  only  distinction  being  that  the  distiller  aims  at  the 
entire  conversion  of  the  starch  into  glucose,  while  the  brewer  does  not^equire  this  as 
he  also  wants  some  dextrine.  The  complete  sacoharification,  and  next  the  oompleto  con- 
version of  the  glucose  into  alcohol  during  fermentation,  are  possible  only  with  a  certain 
degree  of  dilution  of  the  mash.  The  quantity  of  water  to  be  mixed  with  the  grain 
cannot  be  reduced  too  much,  because  that  would  involve  a  loss  of  spirits. 

3.  The  Cooling  of  the  Mash.  —  When  the  saccharification  is  complete,  the  mash  Bhoold 
be  rapidly  brought  to  the  temperature  suitable  for  fermentation  by  being  placed  in 
cooling  vessels,  just  as  is  done  with  the  wort  in  brewing,  by  being  placed  in  an  apparatus 
termed  a  refrigerator,  or  by  the  application  jof  ice  or  cold  water.  The  temperature 
to  which  the  mash  has  to  be  cooled  varies  according  to  the  locality  and  the  duration  of 


SPIRITS.  427 

tho  fenncntation,  bat  it  averages  23**  G.     When  suffioiently  oooled  the  Hqnid  is  placed 
in  the  f ermentiiig  yats. 

4.  The  FermentaHon  of  the  Mash. — Tho  fermentation  vat  is  generally  made  of  wood  and 
sometimes  of  stone.  The  first  possesses  the  property  of  retaining  the  heat  for  a  longer 
time,  and  for  the  same  reason  large  vessels  are  preferred.  The  capacity  seldom  exceeds 
4000  litres.  Either  beer  yeast  in  its  fluid  condition  or  dry  yeast  is  used  to  'set  up 
fermentation.  The  latter  is  mixed  with  warm  water  before  being  added  to  the  contents  of 
the  fermentation  tanks.  Of  the  fluid  beer-yeast,  there  is  usually  taken  to  1000  litres  of 
mash  8  to  10  litres ;  while  for  3000  litres  of  mash  15  to  20  litres  of  yeast  are  a  sufficient 
quantity.  Of  the  dry  yeast,  i  a  kilo,  is  employed  to  1000  litres  of  mash,  or  i  kilo, 
of  yeast  to  3000  litres  of  mash.  In  large  distillories  artificial  yeast  is  somt^times 
employed,  as  beer  yeast  of  the  requisite  qusdity  cannot  always  be  procured  at  a  remune- 
rative price.  The  mode  of  adding  the  yeast  is  the  same  as  that  employed  in  breweries. 
After  standing  3  to  5  hours  the  temperature  of  the  mash  will  have  increased  to  30*^  to 
32*.  Carbonic  acid  is  then  given  off,  and  the  heavier  substances  settle  to  the  bottom 
of  the  tank.  This  continues  for  about  four  days,  when  the  dear  fluid  may  be  con- 
sidered ready  for  further  operations. 

MuhfiomPotetoea.      Potatoes  consist  of  about  28  per  cent  of  dry  substances,  21  per 

cent  of  which  is  starch,  with  2*3  per  cent  of  albuminous  matter,  and  72  per  cent  of 

water.    The  active  principle  under  the  influence  of  which  the  starch  is  converted 

into  dextrose  is  diastase,  but  this  substance  is  not  found  even  in  the  germinated 

potato.    It  therefore  becomes  necessary,  in  order  to  convert  the  starch  of  the  potatoes 

into  dextrose,  to  add  malt,  or  to  treat  the  potatoes  first  with  dilute  sulphuric  acid. 

Accordingly,  the  preparation  of  a  mash  from  potatoes  may  be  performed  by  either  of 

these  two  operations.    The  former  is  that  most  generally  employed.   The  preparation 

ordinarily  includes  the   following  operations: — i.  The  washing  and  boiling  of  the 

potatoes. — ^Before  the  potatoes  can  be  boiled  or  steamed,  they  must  be  cleansed 

from  the  adhering  earth.   After  the  washing  the  potatoes  are  boiled  without  previous 

paring.    Finally,  they  are  steamed.    2.  The  chopping  of  thehoUed potatoes. — As  soon 

as  the  potatoes  are  boiled  they  are  placed  in  a  chopping  machine,  and  cut  into 

small  pieces,  care  being  taken  to  keep  them  hot  by  the  aid  of  steam,  so  that  the  cut 

up  mass  admits  of  being  readily  mixed  with  hot  water  into  a  uniform  mass,  which 

is  the  best  condition  for  the  potato  starch  to  be  most  readily  converted  into 

dextrose.    In  some  cases  the  boiled  potatoes  are  passed  between  two  hollow  cast-iron 

cylinders,  the  Axles  of  which  are  so  arranged  and  fitted  in  a  frame-work  as  to  admit 

of  the  cylinders  being  moved  in  an  opposite  direction,  and  thus  capable  of  converting 

the  boiled  potatoes  into  a  uniform  mash.    3.  The  mashing. — ^After  the  addition  of  the 

grain  or  diastase-containing  material,  the  mashing  proceeds  as  in  the  case  of  malt. 

The  grain  or  malt  added  is  sometimes  rye  malt,  sometimes  barley  malt,  and  generally 

a  mixture  of  the  two.    Green  malt  has  greater  power  of  conversion  than  air-dried 

malt,  ultimately  producing  a  larger  quantity  of  alcohol.    The  proportion  of  bruised 

malt  to  be  employed  varies  in  many  instances ;  while  in  some  cases  only  2  to  3  per 

cent  of  barley  as  malt  is  added  to  100  parts  of  potatoes ;  in  others  as  much  as  10  per 

cent  is  used.    A  medium  quantity  between  these  two  extremes,  or  about  5  cent,  is 

perhaps  that  most  in  use.     100  parts  of  potatoes  containing  about  20  per  cent  of 

starch  3rield  on  an  average  17*3  parts  of  dry  extractive  matter  in  the  mash  wort, 

5  parts  of  barley  malt  yielding  3  parts  of  dry  malt  extract ;  the  yield  of  spirits  has 

therefore  to  be  calculated  from  these  two  substances.     When  a  thick  mash  of 

potatoes  is  made  a  dififerent  proportion  of  the  dry  substances  to  the  water  to  be 

added  is  obtained  from  that  which  obtains  when  malt  or  raw  (unmalted)  grain  is  made 

into  a  mash;  these  proportions  are  in  the  case  of  potatoes  as  i :  45,  i :  4,  even  1:3. 

It  is  clear  that  the  large  quantity  of  water  contained  in  potatoes  (viz.,  72  to  75  per 

cent)  has  to  be  taken  into  account. 


4a8  CHEMICAL  TECHNOLOGY. 

The  operation  of  cooling  is  performed  as  already  described.  While  the  mash  is 
placed  in  the  cooling  vessels  it  undergoes  changes  which  are  partly  fayouraUe 
and  partly  unfavourable  to  the  yield  of  alcohoL  The  increase  of  sugar  is  ef 
course  favourable ;  this  increase  can  only  be  accounted  for  by  the  action  of  the 
protein  compounds  contained  in  the  malt,  whereby  the  dextrine  is  converted  into 
dextrose.  AH  albuminous  substances  possess  the  property  of  converting  starch  into 
dextrose ;  and  this  the  more  so  if  the  albuminous  substances  are  themselves  already 
in  a  state  of  decomposition.  Blood,  brain,  albumen  of  malted  barley,  saliva,  meat 
in  a  state  of  incipient  decay,  are  all  capable  of  converting  starch  into  dextrose,  \\rhen 
Mulder  suggests  that  the  word  diastase  should  be  banished  from  science,  and  for 
it  substituted  that  of  starch  converter,  he  is  right  in  a  scientific  sense,  because 
diastase  does  not  exist  as  a  chemical  body  by  itself ;  but  the  word  diastase  may  be 
convenientiy  used  in  technology  for  the  purpose  of  indicating  an  albuminous  body, 
which  being  itself  in  a  state  of  decomposition,  is  capable  of  converting  starch  into 
dextrose.  Another  change  of  the  mash  consists  in  the  formation  of  lactic  add, 
always  readily  formed  from  sugar  under  the  influence  of  a  peculiar  ferment.  The 
quantity  of  this  acid  is  increased  by  slowly  cooling  to  the  suitable  temperature  for 
fermentation ;  it  is  therefore  best  to  cool  the  mash  as  rapidly  as  possible.  Recently, 
an  aqueous  solution  of  sulphurous  acid  is  employed,  some  of  this  being  added  to  the 
mash  mixture,  the  effect  being  the  prevention  of  the  formation  of  lactic  acid,  and 
thus  increased  yield  of  alcohol. 

Mash  ^thsniphtuio  The  Preparation  of  a  Mash  hy  means  of  Sulphuric  Aeid.—'We 
have  already  seen  that  some  dilute  acids  are  as  capable  of  converting  starch  into 
dextrose  as  the  so-called  diastase  of  malt:  dilute  sulphuric  acid  is  usually 
applied  for  this  purpose.  Leplay  first  recommended  this  mode  of  preparing 
mash.  The  raw  potatoes  are  first  converted  into  a  pulp,  which  is  thrown  into  a 
large  vessel  containing  water.  The  starch  cells  separate,  some  settling  to  the  bott<»n 
of  the  vessel,  others  becoming  mixed  with  the  cellular  tissue  of  the  pulped  potatoes. 
The  brown-coloured  supernatant  fluid  (wherein  is  also  contained  the  albumen  of  the 
potatoes,  which  would,  if  left,  interfere  with  the  action  of  the  sulphuric  acid  upon 
the  starch)  is  first  syphoned  off.  This  liquid  is  given  as  drink  to  cattle,  or  is  used 
for  the  puiposeof  moistening  dry  fodder.  TiVhile  this  operation  is  in  progress  there 
is  heated  to  the  boiling-point  in  another  vessel  the  required  quantity  of  dilute 
sulphuric  acid,  the  heating  apparatus  consisting  generally  of  steam  pipes.  To  eveiy 
hectolitre  of  potatoes  from  1*5  to  2  kilos,  of  strong  sulphuric  acid  diluted  with 
3  to  4  litres  of  water  is  usually  taken.  The  previously  more  or  less  washed  green 
potato  starch  is  gradually  and  by  small  quantities  at  a  time  added  to  this  boiling 
fluid.  The  boiling  is  continued  until  the  whole  of  the  starch  as  well  as  all  the 
dextrine  are  converted  into  glucose,  the  course  of  the  progress  of  the  conversion 
being  ascertained  by  means  of  iodine  water,  while  the  insolubility  of  dextrine  in 
alcohol  affords  a  means  of  ascertaining  whether  the  conversion  of  this  substance  is 
complete.  A  sample  of  the  fluid  when  agitated  with  alcohol  should  exhibit  no  nulky 
appearance.  After  about  five  hours*  boiling  the  formation  of  sugar  will  be  complete. 
The  fluid  is  then  first  run  into  a  vessel  with  double  bottoms,  one  of  which  is 
perforated  with  smaU  holes  so  as  to  admit  of  acting  as  a  strainer  to  retain  cellnlBr 
tissue,  &c.,  after  which  the  fluid  is  run  into  another  vessel,  and  while  therein  is 
neutralised  by  the  addition  of  chalk.     The  gypsum  having  settled  down,  the  floid 


SPIRITS,  439 

is  again  transferred  to  another  vessel.     The  waah  water  of  the  sediment  having 
been  added,  the  liquids  are  ready  to  undergo  fermentation. 

4.  The  Fermentation  of  the  Potato  Mash. — The  addition  of  yeast  to  the  cooled 
mash  in  the  fermenting  vat  takes  place  in  the  same  manner  as  with  malt.  To  100 
kilos,  of  mash  are  added  i  to  2  litres  of  heer  yeast,  or  I  to  i  kilo,  of  dry  yeast.  The 
potato  mash  contains  besides  the  husks  of  malt  and  grain  some  finely  divided  cellular 
tissue ;  these  substances  during  fermentation  are  carried  to  the  surface  of  the  mash 
and  form  a  scum,  the  appearance  and  behaviour  of  which  gives  an  opportunity  of 
judging  the  progress  of  the  fermentation.  The  fermentation  is  said  to  be  regular  or 
irregular ;  the  former  begins  some  four  to  six  hours  after  the  yeast  has  been  added, 
and  proceeds  in  a  regular  manner,  the  end  depending  upon  the  quantity  of  yeast 
added  and  upon  the  temperature.  The  progress  is  quiet,  not  violent,  the  scum  which 
appears  on  the  surface  sinking  or  being  drawn  down  at  one  side  of  the  vat  and  thrown 
up  at  the  opposite  side,  while  bubbles  of  air  or  gas  appear  and  burst  on  the  surface, 
much  as  bakers'  dough  heaves  under  the  influence  of  the  ferment.  Irregular  fermen- 
tation is  so  far  opposed  to  the  former  that  the  surface  of  the  madi  is  only  partly 
covered  with  froth,  wldch  remains  in  one  position,  and  does  not  move  of  itself.  The 
result  of  such  a  fermentation  is  generally  defective,  the  reason  being  the  incomplete 
sacchaiification  of  the  mash,  the  addition  of  too  small  a  quantity  of  yeast,  or  finally 
working  at  too  low  a  temperature.  After  about  60  to  70  hours  with  a  regular  fer- 
mentation, the  mash  is  ready  for  distillation.  Recently  large  quantities  of  spirits 
have  been  prepared  from  maize  and  also  from  rice. 

MMh  fram  Boots.  By  the  uso  of  thosc  Vegetables  which  contain  alcohol-forming  bodies, 
either  in  the  shape  of  cane  sugar  or  as  dextrose,  the  mashing  process  is  avoided,  and 
the  prepared  fluid  is  immediately  ready  for  fermentation  as  soon  as  the  saccharine 
fluid  has  been  completely  squeezed  out  of  the  cells  wherein  it  is  contained  in  the 
vegetable.  The  great  advantage  of  the  preparation  of  spirits  with  the  avoiding  of 
the  mashing  process  is  too  important  to  be  overlooked,  and  it  is  therefore  clear  that 
every  effort  should  be  made  to  substitute  for  the  starch-containing  vegetable  products 
those  which  contain  sugar,  the  more  so  as  it  has  been  recently  proved  in  England 
perfectly  possible  to  arrange  this  industry  in  every  way  to  the  satisfaction  of  the 
excise  authorities. 

One  of  the  most  important  of  such  roots  is  the  sugar-beet  so  largely  employed 
in  the  manufacture  of  beet-root  sugar.  Although  it  would  appear  to  be  a 
simple  matter  to  extract  the  juice  from  the  previously  pulped  juice,  this  is  yet — 
notwithstanding  even  the  large  quantity  of  juice,  viz.  96  per  cent  of  the 
weight — a  difficult  matter,  because  the  remaining  4  per  cent  of  substance  have 
all  the  properties  of  a  sponge  and  tenaciously  retain  the  juice ;  it  is  this  spongy 
nature  of  the  solid  constituents  of  the  root  which  prevents  the  conversion  of 
the  whole  root  into  a  sufficiently  concentrated  mash.  If  it  were  possible  to  set  up 
fermentation  in  the  thick  pulp  obtained  from  the  roots  100  kilos,  of  the  pulp  would 
yield  6  litres  of  alcohol,  a  quantity  sufficiently  large  to  be  remunerative  even  with 
a  very  low  market  price  of  spirits.  Indeed  it  is  maintained  by  the  advocates 
of  beet-root  distilleries,  that  the  distillation  of  spirit  is  a  more  profitable  business 
than  the  manufacture  of  beet-root  sngar.  In  Belgium  and  Germany,  distilleries 
are  frequently  to  be  found  attached  to  the  beet-root  sugar  manufactories ;  and 
the  combination  of  the  industries  possesses  the  advantage  that,  in  a  season  when  the 


430  CHEMICAL  TECHNOLOGY. 

proportion  of  sugar  in  the  roots  is  too  poor  to  yield  much  profit  to  the  mannfactmer 
as  sugar,  he  may  ferment  the  sugar-containing  juice  and  ohtain  a  fair  yield  of 
spirit.  Beets  to  be  available  to  the  distiller  may  contain  only  5  to  6  per  cent 
of  sugar ;  but  for  the  purposes  of  the  manufacturer  of  sugar  they  must  contain  at 
least  8  to  9  per  cent.  The  products  of  the  first  distillation  of  the  fermented  beet- 
roots contain,  in  addition  to  water,  oils  known  as  fusel  oils,  of  very  unpleasant  taste 
and  smell  and  of  poisonous  quality.  These  oils,  however,  disappear  during  rectifica- 
tion.   The  methods  of  obtaining  the  juice  are  the  following : — 

a.  By  pulping  and 

a.  Pressure,  or 

b.  By  treatment  in  a  centrifugal  machine. 

p.  By  maceration,  or  by  the  dialytioal  method. 

a.   The  sliced  roots  being  treated  with  cold  or  with  hot  water  (Siemens^s  and 

Dubrunfaut's  methods). 
6.  The  sliced  roots  being  treated  with  hot  wash  from  former  distillations. 

y.  According  to  Leplay's  method,  somewhat  modified  by  Plachart,  the  sUoed  roots  are 
submitted  to  fermentation  without  previous  extraction  of  the  juice,  and  also  witbont 
addition  of  yeast,  the  alcohol  being  afterwards  distilled  from  the  sliced  roots  with  the  aid 
of  steam. 

sitirits  from  the  BjPTodaeu       1^  the  East  Indies  the  scum  from  the  boiled  sugar,  the  molasses, 
of  Sugar  Hanafactiir«.       ^.^  are  brought  to  fermentation  and  the  fermented  fluid  distilled. 
The  product  is  in  the  EngUsh  colonies  kuown  as  Runiy  in  Madagascar  and  the  Isle  of 
France  as  Guildine.    The  peculiar  aroma  of  rum  is  contained  in  the  portion  which  first 
distils  over.    By  the  fermentation  and  distillation  of  the  scum  from  the  boiliiig  of  the 
sugar-cane  juice,  a  coarse,  sour,  dark  brown  or  black-coloured  acrid-tasting  brandy  is 
obtained ;  it  is  known  as  Negro  rum.    In  England  and  Germany  rum  is  frequently  made 
from  the  diluted  molasses  of  the  sugar  refineries  fermented  with  yeast,  the  fermented 
fluid  being  distilled  after  about  3  to  4  days'  fermentation.    The  aroma  peculiar  to  rum 
is  obtained  by  the  addition  of  some  pelargonio  ether  or  essence  of  pine-apple.    Beet-root 
molasses  are  also  largely  used  for  the  purpose  of  obtaining  spirits.    Bv  its^  the  beet-root 
sugar  molasses  are  difficult  to  ferment,  but  if  the  alkalinity  of  this  material  ia  firrt 
neutralised  by  the  addition  of  some  sulphuric  acid,  and  the  material  next  boiled  with  a 
further  addition  of  acid  for  the  purpose  of  converting  the  cane  sugar  it  yet  may  happen 
to  contain  into  inverted  sugar,  the  fermentation  may  be  readily  set  up  and  regular^  pro- 
ceed.    100  Idles,  of  molasses  yield  on  an  average  40  litres  of  spirit.    The  very  objeotion- 
able  odour  of  this  spirit  is  due  to  fusel  oil,  which  contains  small  quantities  of  propyhe, 
butylio,  and  amylio  alcohol,  pelargonic  acid,  and  caprylic  acid,  while  later  researehes, 
have  added  to  this  list  oenanthic,  oaproic,  and  valerianic  acids.    The  residue  left  in  ^ 
retort  is  used  for  the  preparation  of  potassa  (see  page  118),     The  addition  of  snlphmic 
acid  has  not  only  the  eftect  of  converting  the  cane  sugar  into  an  easily  fermentable  sogar, 
but  also  prevents  the  setting  up  of  lactic  acid  fermentation. 

spititB  from  Wine  and  Maz«.  The  distillation  of  spirits  from  wine  is  chiefly  carried  on  in 
France,  Spain,  and  Portugal.  The  yearly  production  of  spirits  from  wine  or 
French  brandy  (aloool  de  vin)  in  France  alone,  amounts  to  450,000  hectolitres  of 
85  per  cent,  and  400,000  hectolitres  of  60  per  cent.  The  quality  of  the  spirit 
is  indirectly  affected  by  the  degree  of  ripeness  of  the  grapes,  and  directly  by  the  care 
bestowed  upon  the  fermentation  and  distiUation,  the  more  or  less  intimate  mixture  of 
the  volatile  principles  of  the  wine  with  the  alcohol,  and  by  the  age  of  the  wine.  Old 
wine  yields  a  spirit  of  better  quality  than  new  wine.  The  freshly  distilled  brandy 
is  colourless,  and  remains  so  even  when  bottled ;  but  since  tlie  spirit  is  kept  in  oaken 
casks  it  extracts  therefrom  some  colouring  and  extractive  matter.  The  best  kinds  of 
brandy  are  distilled  in  the  D6partement  de  Charentc,  and  the  brand  known  in  com- 
merce as  Cognac  (name  of  a  town)  is  tlie  most  valued.  From  the  marc  and  wine- 
lees  spirit  is  also  distilled.  By  the  distillation  of  spirits  from  wine  a  residue  is  lefl 
in  the  retort  (the  vinasse)  which  contains  a  large  quantity  of  glycerine  which  maj 
thus  be  obtained  as  a  by-product. 


SPIRITS.  431 


b.  Distillation  of  the  Vinous  Mash. 

DbtJOmtioB  of  th«  Hub.  The  fermented  mash  (as  obtained  from  potatoes)  is  a  mixture 
of  non-volatile  and  volatile  snbstances.  To  the  first  belongs  the  fibre,  malt 
husks,  inorganic  salts,  protein  substances,  undecomposed  and  decomposed  yeast, 
Buccinic  acid,  lactic  acid,  glycerine,  &c. ;  to  the  volatile,  the  alcohol,  fusel  oil,  water, 
and  small  quantities  of  acetic  acid.  The  volatile  constituents  of  the  mash,  the  pro- 
ducts of  the  fermentation,  are  separated  from  the  non-volatile  by  distillation,  during 
which  the  volatile  constituents  are  converted  into  vapour  afterwards  cooled  and  con- 
densed in  another  vessel.  When  a  vinous  mash  is  heated  to  the  boiling-point, 
vapours  are  generated  which  consist  essentially  of  alcohol  and  water ;  by  condensing 
these  vapours  there  is  obtained  a  mixture  of  alcohol  and  water. 

Water  boils  at  -f  loo*  C,  barometer  760  mm. 
Alcohol    „     „  -f  78-3'='  C,      „  „      „ 

Thus  it  might  be  thought  that  while  the  boiling-point  of  water  is  2170°  C.  higher 
than  that  of  alcohol,  it  would  follow  that  when  a  vinous  mash  is  heated  to  So°  C, 
only  the  alcohol  would  be  converted  into  vapour,  the  water  remaining  behind.     But 
this  is  not  the  case,  for  under  all  circumstances  the  boiling-point  of  a  mixture  of 
alcohol  and  water  is  higher  than  that  of  pure  alcohol  alone,  and  the  vapour  formed 
consists  of  both  alcohol  and  water.    The  reason  is  partly  due  to  the  affinity  of  alcohol 
for  water,  partly  also  to  the  fact  that  water  evaporates  at  a  lower  temperature  than 
its  boiling-point ;  the  former  (affinity)  retains  alcohol  and  prevents  it  to  escape  at 
proper  boiling-point  (78*3^)  in  the  shape  of  vapour.    If  the  mixture  of  alcohol  and 
water  be  heated  to  its  boiling-point  (suppose  90°  C.)  much  more  alcohol  will  be  con- 
verted into  vapour,  because  its  boiling-point  is  lower,  while  of  water  only  just  so  much 
is  evaporated  as  would  be  the  case  were  it  when  pure  to  be  heated  to  this  temperature, 
while  simultaneously  a  current  of  air  is  passed  through  it,  because  the  vapours  of 
alcohol  evolved  from  the  mixture  act  exactly  in  the  same  manner  as  would  a  current 
of  air  carried  through  the  mixture  of  alcohol  and  water,  the  former  substance  taking 
up  just  as  much  water  as  will  be  volatilised  at  the  boiling-point  of  the  mixed  liquids. 
As  the  quantity  of  vapour  evolved  from  a  liquid  bears  a  direct  relation  to  the 
temperature  of   that  hquid,  the  quantity  of  aqueous  vapours  in  the  mixture  of 
vapours  will  increase  according  to  the  increase  of  temperature,  until  at  last,  as  soon 
as  the  boiling-point  rises  to  that  of  water  (=  100°)  no  more  alcohol  will  be  present  in 
the  vapours  which  are  given  off.    At  the  commencement  of  the  distillation  the  vapour 
given  off  contains  much  alcohol  and  very  little  water  ;  presently  more  water  comes 
over,  and  finally  only  water.    It  is  therefore  quite  evident  that  we  cannot  by  distil- 
lation separate  alcohol  at  once  from  the  rest  of  the  volatile  constituents  of  a  vinous 
mash  liquor.    By  interrupting  the  distillation  at  the  proper  time,  there  is  obtained 
in  the  distillate  all  the  alcohol  contained  in  the  mash  along  with  a  certain  quantity 
of  water,  while  the  residue  of  the  distillation  will  not  contain  any  trace  even  of 
alcohol.    The  liquor  obtained  by  the  first  distillation  is  generally  very  weak  alcohol, 
and  requires  further  rectification,  as  it  is  termed,   to  increase  the  proportion  of 
alcohol.     This  rectification  (another  process  of  distillation)  may  be  continued  till  the 
alcohol  contains  only  a  small  quantity  of  water,  w^hich  can  only  be  eliminated  by  the 
aid  of  such  substances  as  have  a  greater  affinity  for  water  than  the  alcohol,  which 
retains  that  liquid  very  tenaciously.    Anliydroiisi,  or  ab^solute  alcohol,  can  only  be 


43a  CHEMICAL   TECHNOLOGY. 

« 

obtained  by  treating  highly  rectified  alcohol  with  some  substances  which  have  a 

great  affinity  for  water,  such  as  caustic  lime,  fused  chloride  of  calcium,  &c. ;  Imt 

really  absolute  alcohol  is  never  used  on  the  large  scale  in  industry.    The  first 

portions  of  liquid  obtained  by  the  distillation  of  vinous  mash  are  rich  in  alcohol,  and 

termed  fore-run  or  first-run,  while  the  last  portions  of  the  fluid  yet  containing  alcohol 

are  termed  after-run.    A  doubly-rectified  alcohol  contains  50  per  cent  pure  spirit ; 

but  by  means  of  rectification  alone  a  stronger  alcohol  than  of  95  per  cent  cannot  be 

obtained.    The  residue  of  the  distillation  is  called  fluid- wash. 

The  Disuiung  Appantos.      A  distilliug  apparatus  as  usually  employed  consists  in  its 

simplest  form  of  four  parts,  namely,  the  still  or  retort,  the  head  or  cap  of  the  sdll, 

the  cooling  apparatus,  and  the  receiver. 

The  still  or  retort  is  generally  constructed  of  sheet  copper — ^more  rarely  of  iron  boiler-plates. 
The  shape  of  the  vessel  varies,  but  is  generally  a  somewhat  flattened  cylinder,  provided 
with  a  round  opening  of  12  to  14  inches  in  diiuneter,  fitted  with  a  collar  about  x  inch  in 
height  forming  the  neck,  on  which  the  cap  or  head  is  placed.    The  bottom  of  the  still 
is  either  somewhat  bulged  inwards  at  the  centre  or  is  quite  flat.    The  residue  of  the 
distillation  is  removed  through  a  waste-pipe  fitted  with  a  stop-oock  attached  to  the 
bottom  of  the  vessel.    From  tiie  cap  or  head  a  pipe  conveys  the  volatilised  alcohol  to  the 
receiver,  while  jutting  obliquely  from  the  top  of  the  still  is  a  pipe  for  the  introduction  of 
the  mash.    The  head  carries  the  vapours  from  the  still  into  &e  cooling  or  condensing 
apparatus ;  althongh  a  simple  tube  might  answer  this  porpose,  it  is  preferred  to  make 
the  head  of  the  stills  large  and  wide,  not  only  for  the  purpose  of  separating  any  paiticiea 
of  mash  which  might  happen  to  be  carried  off  with  the  vapours  of  the  boiling  liquid^  bni 
also  to  obtain  a  distillate  richer  in  alcohol,  because  an  increased  surface  is  favourable  to 
the  cooling  of  the  vapours,  whereby  thus  the  aqueous  vapour  is  first  condensed ;  more- 
over large  heads  are  advantageous  in  case,  by  a  rapid  evolution  of  vapours,  the  maeh 
might  boil  up  (priming) ;  roomy  space  in  the  head  prevents  then  the  liquid  pawring  ova 
into  the  worm.    Since  the  volume  of  the  vapours  decreases  during  the  condensation,  a 
somewhat  oonioally-shaped  head  would  be  the  best  form  for  this  portion  of  the  appazatnsL 
The  cooling  apparatus  is  not  simply  destined  to  convert  the  vapours  carried  into  it  from 
the  head  into  liquid,  but  it  is  also  required  that  this  liquid  be  so  far  cooled  down  as  to 
prevent — at  least  as  much  as  possible — the  evaporation  of  the  distillate ;  the  condensing 
apparatus  should  not  be  too  roomy;  that  is  to  say,  there  should  not  be  too  much 
space  for  the  vapours,  because  this  would  cause  air  to  enter  the  cooling  apparatus, 
and  this  air,  while  mixing  with  the  vapours  of  alcohol,  carries  off  along  with  it  some  of 
this  fluid,  thereby  causing  a  loss  of  the  fluid.  -It  is  also  requisite  that  the  cooling 
apparatus  be  strongly  made,  yet  at  the  same  time  so  constructed  as  to  admit  of  being 
readily  taken  dowu  for  cleansing  purposes  and  easily  fitted  up  again ;  usually  the  cooUng 
apparatus — ^technically  termed  worm — consists  of  a  series  of  spirally  bent  tubes  made  at 
either  block-tin  or  copper,  seldom  of  lead ;  this  apparatus  is  placed  in  a  large  wooden 
or  metal  vat  containing  cold  water,  or  as  in  the  more  recently  constructed  distilling 
apparatus,  cold  vinous  mash,  which  is  thus  made  warm  previous  to  being  transferred  into 
the  still,  whereby  of  course  a  saving  of  fuel  is  effected. 

^"TSSiSii?"^  However  much  the  shape  and  details  of  construction  of  the  apparatus, 
with  the  aid  of  which  strong  alcohol  can  at  once  be  obtained  by  one  distillation,  may 
vary,  these  apparatus  all  agree  in  this  respect,  that  the  mixture  of  vapours  of  alcohol 
on  their  way  from  the  still  to  the  condenser  become  continuously  richer  in  alcohol  so 
that  on  reaching  the  cooling  apparatus  strong  alcohol  is  the  result  of  the  operation. 
This  result  can  be  attained  in  two  different  ways,  viz. : — 

1.  By  causing  the  mixture  of  vapours  to  pass  repeatedly  through  alcoholic  liquids 
formed  by  the  condensation  of  the  vapours  first  given  off;  when  afterwards 
the  temperature  increases  in  consequence  of  the  continued  rush  of  vapours  into 
the  liquid,  a  new  process  of  distillation  begins,  the  vapours  generated  by  it  being  far 
richer  in  alcohol  than  when  the  first  distillation  took  place  (principle  of  rectiJuMtionu  ' 

2.  By  so  cooling  the  mixed  vapour  that  the  water  only  is  condensed,  the  alcohol 
passing  on  as  vapour  (principle  of  dephlegmation). 


'Wlien,  in  fonner  dsys  (sixty  to  sisty-fiTe  years  ago),  it  was  desiied  to  preiius 
strong  slcohol.  a  repeated  process  of  distill&tian  was  adopted  ;  this  of  coarse  was  ft 
costly  sfEkir  both  as  regards  eonsnmptioD  of  materials,  fael,  9k.,  and  loss  of  time. 
At  the  present  day  distillation  apparatus  are  genei»Uy  so  arranged  that  by  a  kind 
of  disaodatian  of  the  mixtaie  ct  vapoora,  alcohol  of  any  desired  strength  cut  be  at 
once  prepared. 

Most  of  the  recent  distillation  appaistns  may  be  considered  to  consist  of  the 
following  porta: — 

I.  The  still  or  vessel  in  which  the  fermented  maah  is  placed. 

z.  Two'condensii^  apparatus,  one  of  which  serves  as  rectifier,  while  the  othxat 
completes  the  condensation  of  the  products. 

3.  A  dephlegroatoi  in  which  the  mixed  vaponr  separates,  a  portion  of  the  water 
becoming  condensed  and  a  vapour  richer  in  the  alcohol  being  carried  on ;  this  latter 
is  carried  into  the  cooling  apparatus,  while  the  former  Sows  back  into  the  still. 

Among  the  many  distilling  apparatus  employed  in  Oermany  for  distilling  fermented 
potato  mash,  we  propose  to  describe  those  of  Dom,  Piatorius,  Gall,  Schwarz,  and 


!>«•■  ArMHtH.  Dom's  apparatus,  Fig.  233,  consists  of  the  still,  a,  the  helm,  a,  ^ucb 
acts  as  dephlegmator,  the  condensing  apparatus,  d,  and  between  the  still  and  con- 
densing apparatus,  a  copper  vessel  divided  by  a  partition  into  two  compartments. 


o  and  r,  Uie  upper  of  which,  c,  is  termed  the  fore-warmer,  the  under,  r,  the  recti- 
ficator.  Connected  with  the  helm  is  a  small  condenser,  n,  for  the  purpose  of  taking 
an  occasional  sample  of  the  distillate  which  poases  over.  The  fore-wanner  is  filled 
with  mash  to  a  level  with  the  tube,  o,  and  usnallj  contains  as  much  mash  as  ia 
Deoessary  to  fill  the  still.  With  the  help  of  the  revolving  arms,  x  x,  the  mash  ia 
from  time  to  time  kept  stirred,  and  thus  equally  bcati^d  throughout  to  about  85°  by  the 
▼apour  passing  through  the  pipe,  i  t,  from  the  still.  When  the  distillation  is  finished 
the  wash  (waste  residue)  is  run  off  by  opening  the  Up  a,  the  stitl  being  re-fiUed  with 
mash  from  the  fore-warmer.  As  soon  as  the  distillation  commences  the  vapour  is 
condensed  in  the  worm,  i  i,  the  condensed  fluid  flowing  into  r.  When  the  steam  is 
no  longer  condensed  in  t,  which  occurs  as  soon  as  the  mash  has  reached  a  certain 
temperature,  the  vapours  pass  over  into  the  low  wine,  which  thus  becomes  rapidly 


«4 


CHEMICAL  TECHNOLOGY. 


heated  lo  tlie  boiling-point.  By  thia  means  a  second  distill.ition  ia  effected.  i«Dt  i 
rectificulion,  the  vapnur  or  sleuiii  from  which  passing  by  tlie  tube,  g.  ia  carried  to  (he 
wonn,  I  z.  placed  in  Uio  coniienser,  d,  and  having  been  converted  into  a  fluid  flo«» 
off  at  p.  The  distillation  is  continued  until  tlie  tluid  which  comes  over  (the  distil- 
latel   contains  only  35  to  40  per  cent  of  alcohol;    a  sample  is  then  taken  at  ll» 


small  cooling  appnratiix.  k,  to  l«st  the  quality  of  the  mash,  and  in  order  to 
ascertain  whether  it  contains  any  more  alcohol.  When  the  diatillala  collected  it  ■ 
is  found  to  be  only  water  the  operation  is  finished.  The  wash  is  ran  off  btnn  tb« 
still,  and  it  is  then  re-iilled  with  fresh  mash  from  the  f<«e-warmer  throng  1,  awl 


SPIRIT.  435 

Uie  distillation  again  proceeded  with.  The  low  wine  contained  in  the  vessel  f  flows 
tlirough  the  tuhe  j  or  q  back  into  the  stilL  As  may  be  seen  in  the  cut,  Dom's  appa- 
ratus has  not  a  separate  deplilegmator  and  only  one  still  or  retort.  This  apparatus 
is  now  rarely  used  for  distilling  mash,  but  frequently  for  rectifying  spirits. 

pistoiiiu's  Appantu.      Pistorius  first  introduced  in    Germany  a  distilling  apparatus 

fitted  with  two  stills  ingeniously  connected  with  rectificators  and  dephlegmators. 

When  a  distilling  apparatus  is  required  which  not  only  extracts  all  the  alcohol  from 

the  mash,   but  also  produces  the  alcohol  in  a  very  pure  and  concentrated  state, 

performing  this  work  with  the  least  possible  expen  Liure  of  fuel    and    labour, 

Pistorins's  apparatus  answers  the  purpose  admirably,    a  and  b,  Fig.  234,  represent 

the  two  stills,    a  is  the  main  still,  which  is  either  phiced  on  a  furnace  and  heated 

directly  by  fire  or  by  means  of  stoam.     Heating  by  steam-pipes  instead  of  direct 

firing  possesses  many  advantages.     The  second  still,  b,  is  placed  at  a  somewhat 

higher  level  than  the  first,  and    when   not    heated  by  steam-pipes  is  situated 

on  the  flue  of  the  furnace  fire  of  the  first  still.    The  main  still,  a,  is  fitted  with  a 

large  helm,  d,  fastened  on  the  still  with  bolts  and  nuts,    p  isa.  tube  projecting  from 

the  helm  and  provided  with  a  safety  valve  which  opens  inwards,  in  order  to  give 

access  to  air  as  soon  as  towards  the  end  of  the  distillation  a  vacuum  might  ensue  in 

the  interior  of  the  apparatus  in  consequence  of  the  condensation  of  the  vapours. 

There  is  also  connected  with  this  tube,  p,  a  small  condenser,  <;,  as  in  Dom's 

apparatus,  from  which  samples  showing  the  progress  of  the  distillation  may  be  taken. 

In  both  stills  stirring  apparatus,  m  and  n,  are  fitted  to  prevent  the  mash  burning. 

By  the  tube  x  the  vapour  of  the  "  low  wine "  is  admitted  to  the  second  stiU,  the 

maskrStilL     From  tlie  helm,  f,  of  the  mash-still  a  curved  pipe,  s,  conveys  the  vapour 

to  the  mash  fore-warmer,  which,  as  in  Dom's  apparatus,  is  divided  into  two  parts,  the 

upper,  E,  containing  the  mash,  the  lower,  g  (the  "  low  wine  "  cistern) ;  the  Vapour 

ascending  along  the  narrow  passage,  v,  to  the  rectification  apparatus,  h.    Frequently 

the  vapour  is  conveyed  to  a  third  still  before  entering  g  ;  this  still  is  not  shown  in  the 

drawing.     The  rectification  apparatus,  H,  consists  of  two  or  three  conically-shaped 

vessels,  made  of  sheet-copper  and  connected  together,  and  is  provided  with  a  cistern 

filled  with  water,  w ;  it  is  connected  with  the  condenser,  r,  by  the  tube  c.     The 

tub^  X  conveys  cold  water  to  the  rectification  apparatus,  and  the  short  tube,  y,  does 

so  to  the  fore-warmer.    The  pump,  p,  is  employed  to  pump  the  mash  from  the 

cistern,  l,  to  the  fore-warmer ;  thence  it  is  carried  to  the  second  still,  and  thence 

again  to  the  first  still.    When  both  stills  and  the  fore-warmer  are  filled  with  mash, 

the  fire  is  lighted  under  the  first  still.    The  steam  or  vapour  from  the  mash  in  a 

passes  to  the  mash  in  b,  which  is  thereby  heated  to  the  boiling-point.    The  still  b 

serves,  therefore,  the  purpose  of  a  rectificator.    When  the  distillation  has  begun,  the 

vessel,  w,  on  the  rectificator  is  filled  with  cold  water,  which  is  re-supplied  when  it 

has  become  warmed  by  the  passing  vapours.  As  soon  as  the  steam  reaches  the  upper 

rectificator,  the  real  distillation  commences.     The  condensed  fluid  drops  into  a 

cistern  in  which  a  hydrometer  is  placed. 

<HiriAi>pumtiu.  In  most  apparatus  for  distilling  from  a  vinous  mash  the  distillate 
becomes  gradually  weaker  and  is  not  throughout  of  the  same  strength.  Gall  and 
Marienbad  have  endeavoured  to  avoid  this  defect  in  their  apparatus.  Figs.  235  and 
236,  so  as  to  obtain  a  more  uniform  product  during  each  distillation.  Two  stills  are 
placed  in  a  suitable  manner  in  a  steam-boiler  and  the  stills  are  connected  with  the 
separator  (low  wine  cistern),      bb   are  the  stills;    c  is  a  boiler  with  flues,  it. 

2  F  2 


436 


CHEMICAL  TEOBNOLOGT. 


tlie  Btills,  in  order  to  prevent  them  eooling.  ore  fixed  into  the  boilet ;  s  is  s  fbiri 
Btill  placed  on,  not  in,  the  boiler ;  e  is  the  low  wine  cistern ;  r  and  a  two  dcplileg- 
inaiors  or  BeparBtorB  ;  a  is  a  condenser  with  a  worm,  h.  The  nuuh  ia  pnt  first  into 
the  Btill  0  by  means  of  the  tube  a  a,  this  still  serving  as  a  fore-warmer  mad  reeti- 
ficator.  From  tliis  Btill  botli  the  stills  h  b  are  filled.  From  the  boilet  a  corrent  d 
Steam  is  conveyed  Qu'ongli  the  bent  tnbe,  b,  into  the  three-way -cock,  c,  whence  tW 
steam  is  either  passed  into  one  or  both  the  stilla  b  b  or  is  conveyed  npwards  by  tha 
tube  tl  to  tlie  vessel  destined  t«  steam  the  potatoes.  The  vapour  from  one  or  both  ot 
the  stills  I)  n  proceeds  to  the  still  d.  and  thence  into  ttie  low  wine  cistern,  e,  aud 
passing  throngb  the  depblegmatovs,  r  and  a.  finally  ester  into 


Fto.  »3S. 


pecnliarity  of  Gall's  apparatus  conusts  in  that  by  the  peculiar  arnugcment  el 
tubes  and  stop-cocks,  each  of  the  two  stills  may  at  wiU  be  brought  into  actioD,  it 
being  possible  to  turn  the  steam  at  pleasure  into  the  right-hand  stiU,  and  next 
into  the  Icft-liand  still,  or  vice  vena.  Each  still  may  be  also  disconnectad.  A* 
wash  therefrom  discharged  and  ra-filled  without  in  the  least  interruptJng  th« 
workint;  of  the  other  portions  of  the  apparatus ;  the  distillation  can  therefora 
proceed  uniiitemipteJIy,  one  part  of  the  apparatus  being  filled  while  the  other  ii 

atbmtiiLnutxai.  Scbwttrz's  apparatus  is  in  very  general  use  in  the  Booth-west  of 
Germany.    It  consists.  Fig.  237,  of  the  steam  boiler,  d;  two  maah  stills,  land  b;  It* 


SPIRIT. 


«7 


fere-wanner,  o 


;  the  "  low  wins"  ciBton.orreoeiTar.B;  tli0r«ctifi(!atora,Huidr;  sod 
o.  H  is  a  reaerrair  for  cold,  n  one  for  hot  water.  The  Bteaiii  generated 
in  the  boiler,  d,  passes  through  the  pipe,  g,  into  the  under  compartment,  a,  of  tbe 
donUe  sdU,  through  the  maeh  cont^ned  there ;  becoming  mixed  with  Taponre  of 
alcohol,  it  arrives  in  the  hdm,  «,  and  further  makes  ite  way  b;  means  of  the  tube  it 
into  the  upper  part  of  the  double  still :  thence  after  a  double  rectification  it  ie 
convejed  bj  means  of  the  tube  t  to  the  fore  warmer,  c ;  the  npper  port  of  this 
vessel  provided  with  the  tubes  aaa  acts  as  a  dephlegmator  or  separator,  the  con- 
densed fluid  flowing  into  B.  The  steam  which  arriTes  from  the  upper  part  of  tbs 
■till  passes  through  g.  and  thmice  b;  waj  of  the  tubes  aa  into  the  helm,  and 
iha  tube  «,  which  latter  is  suiionnded  with  the  vessel  R  kept  oold  by  means  of  cold 


water ;  the  dephlegmotioQ  continues  here.  From  a  the  steam  passes  tlirough  v  to  f, 
an  appsratus  corresponding  to  the  fore-wanner,  c,  but  of  emaller  dimensions ; 
because  here  the  quantitj  of  vapour  has  become  greatlj  reduced  while  it  has  become 
richer  in  alcohoL  The  dephlegmator  tubes  are  here  surrounded  bj  cold  water,  not 
hj  cold  mash,  the  former  liquid  being  constantly  renewed  so  as  to  keep  cold.  Tlie 
steam  or  rapour  collected  in  the  helm,  b,  is  sofficientlj  laden  with  alcohol  to 
admit  of  being  at  once  conveyed  to  the  condenser,  o,  the  condensed  distillate  flowiug 
oat  at  J.    The  vinous  mash  is  first  poured  into  the  fore-warmer,  c,  wberein.it  is 


43a  CHEMICAL  TECBNOLOOY. 

OeeteiiaaMy  stin-ed  by  the  arms,  dd,  and  croak,  d,  so  ka  to  keep  it  nnifonnl^  mui 
•Dd  heated.  When  the  maeh  haa  become  warm  it  is  conveyed  into  the  upper  ewa- 
partmeDt  of  the  double  still  by  tlie  pipe,  e,  ajid  into  the  lower  compajtment  through 
the  open  valve;  this  compartment  bIbo  serveB  aa  ciatem  for  the  phlegnw  from  ill 
other  parts  of  the  appuatus;  the  fluid  flonsbackwarda  from  the  comportments  kindl 


of  the  rectificatora,  h  and  f,  by  way  of  the  tubes  w'  and  n,  into  the  low  wine  dstera.  'i 
thence  into  the  upper  compartment  of  the  double  atill,  where  it  mixea  with  the  maik- 
Aa  Boon  as  the  mash  haa  given  np  oU  its  alcohol,  which  coo  be  asoertoiued  bylMthi? 
the  inflammobilitj  of  the  vapour  issuing  from  the  t«Et  atop  cock,  o,  the  reaidw  v 


SPIRIT. 


430 


removed  by  opening  the  tap, p.  By  means  of  tlie  tubes  gqq  Qie  rectificatora  and 
eondensing  apporatua  are  supplied  with  cold  water.  The  warm  water  from  the  con- 
denser is  conveired  bj  tlie  tube  r  into  the  boiler.  By  means  of  r,  the  steam  con  b« 
admitted  to  the  potato  vessels,  and  bv  n  into  the  reservoir  n.  when  it  is  desired  to 
heat  the  water  it  coutains  to  the  baiUng- point.  Schwarz's  apparatus  possesses  the 
advantage  of  being  easilj  taken  to  pieces  and  cleansed.  Jiut,  on  the  contrary, 
amoDK  its  di^^vantages  ai-e  the  following :— the  construction  of  the  mash -warmers  is 
not  quite  suited  for  the  purpose,  while  also  the  condensed  liquid  in  k  is  not  brought 
nufficieutlv  into  contact  with  tlie  hot  steam  lo  affect  a  tliorough  distiltatioD  or  rectiti- 
eation.     The  steain  passes  so  quickly  tlirough  the  hquid  tliat  it  is  only  very 


Fio.  13S. 


imperfectly  deprived  of  its  water  (dephlegmated]  when  it  reaches  the  dephlegmatiou 
•pparatus,  where  it  vrill  consequently  be  but  imperfectly  lectihed,  while  the  vertical 
ateom-pipes  offer  too  few  paints  of  contact,  and  allow  much  steam  to  pass  olT  with- 
out being  Mly  condensed;  while  even  the  portly  condensed  vesicular  steam  ie 
carried  off  along  with  the  condensation  escaping  steam.  The  condenser  itself  is 
imperfect,  being  constructed  of  a  number  of  vertical  pipes,  through  wkich  the  con- 
densed liquid  rapidly  falls  without  becoming  quite  cold,  and  in  order  to  obtain  a 
sufficient  condensation  an  immense  quantity  of  cold  water  has  to  be  used. 


440  CHEMICAL  TECHNOLOGY. 

EUaamfuAwuaibBM.  Amoii'T  the  apparatoB  capable  of  producing  a  large  qoantitjr  of 
fipirits  at  a  small  cost  is  that  of  Semens.  This  apparatus  is  much  need  in  tbe  dis- 
tillation of  brandy.  It  consists,  Fig.  238,  of  two  mash-stills  set  in  a  bailer,  and 
capable  of  being  alternately  used  (by  means  of  the  three  cocks,  a,  b,  and  «),  in  dw 
same  manner  as  in  Gall's  apparatus,  while  the  fore-warmer  and  d^hlegmator  is 
constructed  according  to  Siemens's  plan,  l  is  the  boiler ;  p  one  of  the  mash-retortB; 
K  is  the  low  wine  receiver;  b  the  fore- warmer ;  a,  a  reserroir  in  which  the  oondcnsed 
water  intended  as  feed  water  of  the  boiler  is  collected ;  c  is  the  dephlegmator ;  b  a 
reservoir  for  the  vapours  condensed  in  c.  From  the  dephlegmator  the  vapour 
passes  to  a  condenser  not  shown  in  the  engraving.  This  apparatus  is  ccnstnieted  of 
such  dimensions  that  it  can  perform  the  work  about  to  be  mentioned.  The 
l^oiler  has  to  steam  about  5000  Mlos.  of  potatoes  in  four  lots,  duiing  from  40  to 
45  minutes  each,  and  should  thus  be  capable  to  yield  in  three  hours  the  fifih 
part  of  the  weight  of  the  potatoes  =  1000  kilos.,  or  in  one  hour  333  kilos,  of 
steam,  which  renders  necessary  a  steam-generating  surface  of  about  11  square  metres. 
But  since  the  distillation  requires  steam  also,  this  generating  surface  has  to  be 
increased  by  about  20  per  cent,  and  should  consequently  be  13*5  to  14  square  metres. 
The  size  of  the  mash  stills  should  be  sufficiently  large  to  contain  with  ease  500  litres 
when  properly  filled ;  because,  as  already  stated,  the  fluid  from  ▲  is  not  returned  to 
the  still  but  to  the  steam-boiler,  the  stills  being  set  into  the  last-named  vessel  not 
becoming  externally  cooled,  whereby  the  quantity  of  water  carried  along  with  the 
vapours  of  spirit  is  compensated  for. 

The  mash  warmer  consists  of  a  cylindrical  portion,  i  t,  the  lower  part  of  which 
has  an  indentation,  c.  In  the  cylinder  is  placed  a  narrower  portion,  0  o,  of  the  xeai 
mash-containing  vessel  fitted  with  the  heating  tube,  /  n.  The  upper  part  of  the 
fore- warmer  is  fitted  to  the  lower  part  by  means  of  the  flange,  h  h.  r  is  a  starring 
apparatus,  which  is  frequently  set  in  operation  during  the  process  of  distillatifln 
The  vapours  from  the  second  still  are  carried  into  the  depression,  c,  under  the  foie- 
warmer,  which  in  order  that  the  vapours  may  come  into  contact  with  the  phl^ma  is 
covered  with  a  sieve.  The  vapours  surround  the  under  part  of  the  mash  raserroir 
and  enter  into  the  tube,/,  through  which  they  pass  to  the  lower  cylinder  of  the 
dephlegmator.  The  condensed  water  of  the  dephlegmator  is  conducted  into  the 
reservoir,  a.  The  upper  and  under  part  of  the  fore- warmer  are  made  of  east-iron, 
but  the  interior  bottom  and  heating  sur&ces  are  made  of  copper.  This  kind  of 
fore- warmer  has  the  advantage  of  uniformly  distributing  the  heat,  while  it  can  be 
easily  cleansed.  The  dephlegmator,  c,  is  so  contrived  that  the  rectified  vapour  can 
be  conveyed  to  the  condenser  by  two  separate  pipes  placed  in  an  opposite  direetiaD 
to  each  other,  and  are  joined  again  in  close  proximity  to  the  condenser.  T^ 
remainder  of  the  details  will  be  seen  on  studying  the  drawing. 

conttownjjMjumng  Amoug  the  distilling  apparatus  intended  for  the  distiHatioii  of 
wine  (not  of  mash),  and  so  constructed  as  to  be  fit  for  continuous  woridng,  m 
must  not  neglect  to  mention  the  apparatus  of  Cellier-Blumenthal,  as  improved 
by  Derosne,  and  represented  in  Fig.  239.  This  apparatus  consists  of  two  stiDs, 
A  and  a';  the  first  rectificator,  b;  the  second  rectificator,  0;  the  wine  warmer  and 
dephlegmator,  d;  the  condenser,  f;  the  regulator,  e;  a  contrivance  for  regu- 
lating the  flow  of  the  fluid  wine  from  the  cistem,  o.  The  still  a',  which  as 
well  as  the  still  a  is  filled  with  wine,  acts  as  a  steam  boiler.     The  low  wine 


Tkponn  erolTsd  ocrme,  when  ihej  hxve  amved  in  the  re«tifieaton,  in  oontact 
iriih  Ml  muBtermpted  atream  of  wine,  wherebj'  dephlegmadon  is  effected;  the 
▼aptmr  thu  eoiiched  in  •leohol  beoomaa  still  atronger  in  the  Teasel  d,  and  thence 


amveg  at  (he  eoolmg  appuatna,  f  In  otder  that  a  real  rectification  ehoold  tabs 
place  in  the  Tecti£cato»,  the  stream  of  wine  ahoold  be  heated  to  a  certain 
tempArattira,  whioh  is  imparted  to  it  ij  the   heating  of  the  oondenMr  water. 


442  CHEMICAL  TECHNOLOGY. 

The  steam  from  the  still  a'  is  carried  hj  means  of  the  pipe  z  io  the  bottom  of 
the  still  ▲.  Both  stills  are  heated  by  the  fire  of  the  same  fomace.  By  mAan» 
of  the  tabe  b'  the  liquid  contained  in  the  still  a  can  be  run  into  the  still  a*.  The 
first  rectificator,  b,  contains  a  number  of  semi-circular  discs  of  unequal  size,  placed 
one  above  the  other,  and  which  are  so  fiistened  to  a  vertical  centre  rod  that  they  can 
be  easily  removed  and  cleansed.  The  larger  discs,  perforated  in  the  manner  of 
sieves,  are  placed  with  their  concave  surfaces  upwards.  In  consequence  of  this 
arrangement  the  vapours  ascending  from  the  stills  meet  with  large  surfaces  moistened 
%vith  wine,  which,  moreover,  trickles  downwards  in  the  manner  of  a  cascade  from 
tiiie  discs,  and  comes,  therefore,  into  very  intimate  contact  with  the  vapours.  Th» 
second  rectificator,  c,  is  fitted  with  six  compartments ;  in  the  centre  of  each  of  the 
partition  walls  (iron  or  copper  plates)  a  hole  is  cut,  and  over  this  hole  by  means  of  a 
vertical  bar,  is  fastened  an  inverted  cup,  which  nearly  reaches  to  the  bottom  of 
the  compartment  wherein  it  is  placed.  As  a  portion  of  the  vapours  are  condensed 
in  these  compartments  the  vapours  are  necessarily  forced  through  a  layer  of  low- 
wine,  and  have  to  overcome  a  pressure  of  a  colunm  of  liquid  2  centimetres  high. 
The  fore-warmer  and  dephlegmator,  d,  is  a  horizontal  cylinder  made  of  copper 
fitted  with  a  worm,  the  convolutions  of  which  are  placed  vertically.  The  tube  v 
communicates  with  this  worm,  the  other  end  of  which  passes  to  o.  A  phlegma 
collects  in  the  convolutions  of  this  tube,  which  is  richer  in  alcohol  in  the  foremost 
windings  and  weaker  in  those  more  remote :  this  fluid  collecting  in  the  lower  part 
of  the  spirals  may  be  drawn  off  by  means  of  small  tubes,  thence  to  be  transferred  at 
the  operator's  pleasure,  either  all  or  in  part,  by  the  aid  of  another  tube  and  stop- 
cocks to  the  tube  o,  or  into  the  rectificator.  By  means  of  the  tube  l  the  previously- 
warmed  wine  of  the  dephlegmator  can  be  run  into  the  rectificator.  Tlie  condenser,  f, 
is  a  cylindrical  vessel  closed  on  all  sides,  and  containing  a  worm  communicating 
with  the  tube  o.  The  other  end  of  the  condensing  tube  carries  the  distillate  away. 
On  the  top  of  this  portion  of  the  apparatus  the  tube  k  Lb  placed,  by  means  of 
which  wine  is  run  into  the  dephlegmator.  The  cold  wine  flc»ws  into  the  oooling 
vessel  by  the  tube  i.  When  it  is  desired  to  work  with  this  apparatus,  the  fixist 
thing  to  be  done  is  the  filling  of  the  vessels  a  and  a'  with  wine.  The  stop-cock,  x, 
is  then  opened,  whereby  the  tube  j,  the  condenser,  f,  and  tiie  dephlegmator  are  filled 
with  wine.  The  wine  in  the  still  a'  is  next  heated  to  the  boiling-point ;  the  steua 
enters  the  tube  z  and  is  condensed  in  a  until  the  wine  here  is  heated  to  the  boiling- 
point  by  the  combined  effect  of  the  steam  and  the  hot  gases  circulating  in  the  fine. 
The  low  wine  vapour  then  passes  to  the  rectificator,  b,  and  thence  into  the  worm  of 
the  dephlegmator,  d,  where  the  greater  portion  of  it  is  condensed,  the  phlegma  flowing 
backwards  into  the  rectificator.  As  soon  as  the  fore-warmer  is  so  flu:  heated  that  the 
hand  cannot  be  kept  in  the  hot  wine,  the  stop -cock  of  the  vessel  £  is  opened,  and 
the  distillation  commences.  The  wine  which  is  conveyed  by  the  tube  j  into  tho 
oooling  vessel,  F,  soon  begins  to  become  hot,  and  is  then  conveyed  to  the  fore- 
warmer,  where  its  temperature  becomes  nearly  as  high  as  the  boiling-point;  by 
means  of  the  tube  l  this  flmd  is  conveyed  into  the  rectificator,  b,  and  thence  into 
the  still  A. 

As  soon  as  the  wine  in  the  still  a'  contains  no  more  alcohol,  the  stop-cock,  fitted  to 
the  lower  part  of  the  vessel  is  opened,  and  the  vinasse  run  off  at  k,  the  still  being 
re-supplied  by  opening  the  stop-cock,  b'.  The  vapour  proceeds  in  the  same 
way,  but  in  a  reversed  direction ;  when  the  vapour  has  been  condensed  in  f  it  it 


SPIBIT. 


443 


first  collected,  as  alcohol,  in  the  email  vessel,  n,  provided  with  aa  a.reomet«r,  and 
thence  conveyed  to  the  cistern,  b.  The  strength  of  the  alcohol  obtained  by  meouB 
of  this  apparatus  increases  with  an  increase  of  the  number  of  the  windings  of  the 
eondeuser  placed  in  the  dephlegmator  and  connected  with  the  rectiiicator.  Practical 
esperience  decides,  according  to  the  alcoholic  strength  of  the  wines  to  be  distilled, 
and  the  quantity  of  pure  alcohol  desired  in  the  diBtillat«.  the  opening  or  shutting 
of  the  varione  stop-cocks  of  this  apparatus.  DeroBiie'e  apparatus  may  be  readily 
made  continuous ;  for  this  purpose  it  is  only  necessary  to  fill  the  reservoir,  conden- 
sing apparatus,  and  rectificator  with  cold  water,  while  the  lower  portion  of  the  tube  l 

Lmatoi'dTPumtu.  Laugler's  apparatus,  shown  in  section  in  Fig.  340,  is  also  of  great 
interest.  Notwithstanding  the  fact  that  Derosne's  apparatus  is  exceedingly  com- 
tnendablefor  great  economy  of  fiiel,  rapidity  of  distillation,  and  excellence  of  product. 


the  apparatus  is  rather  of  a  complicated  construction,  because  it  is  arranged  to 
distil  all  kinds  of  wine,  be  they  weak  or  strong,  while  at  the  same  time  alcohol  of 
any  desired  strength  may  be  ohtejned,  Apparatos  of  the  construction  of  Langier's, 
arranged  for  the  distillation  of  one  kind  of  fluid,  wine  or  mash,  and  for  the  pro- 
duction of  a  distillat«  which  is  always  of  the  same  strength  of  alcohol,  may  be 
far  more  simply  constmcl^d.  The  fluid  to  be  distilled  flows  from  the  tube,  1, 
into  the  funnel,;),  thence  into  the  vessel  a,  entering  its  lower  part  and  serving  to 


444  CSEMICAL  TBCBSOLOQT. 

condense  the  alcoholio  vapoor.  From  this  vessel  the  wormed  fluid  pUM* 
by  mefmB  of  tite  tabe  r  into  the  lower  part  of  the  second  vessel,  h,  where 
dephlegmation  takes  place  by  metuks  of  a  coudeneing  tabe.  Theace  the  flnid 
flowa  bj  waj  of  the  tube  o  into  the  second  still,  c,  which  is  heated  hj  the  hot 
gases  evolved  from  the  fire  kept  haming  under  the  first  still,  d  ;  in  the  still  c  the 
fluid  nndergoes  e  rectification,  and  the  vinasse  flows  bj  the  tabe  «  into  the 
still  s.  M  is  tlie  pipe  conveying  the  hot  vapour  from  d  into  c ;  the  tnbe  b  eonveji 
the  alcoholic  vapours  into  the  dephlegmator.  fij  means  of  the  tube  d  the  phlegms 
ia  conveyed  into  the  still  c  ;  /  serves  as  a  means  of  emptying  the  still  d  ;  g  and  k 
are  glass-gauging  tubes  for  indicating  the  height  of  the  flnid  in  the  interior  of  the 
Still ;  the  tube  l  conveys  the  non-condensed  vaponrs  from  the  dephlegmator  into  the 
condensing  apparatus ;  while  i  conveys  the  valours  formed  in  the  vessel  b  into  the 
condensing  apparatus.  The  alcohol  condensed  in  the  cooling  apparatus  flows,  as  is 
exhibited  in  the  cut,  into  a  vessel,  o,  provided  with  an  areometer  to  indicate  the 
strength  of  the  fluid.  The  cooling  apparatus  of  the  vessel  b  consists  of  seven 
compartments  or  divisions  formed  by  wide  spirals,  each  of  which  is  at  its  lower 
level  fitted  with  a  narrow  tube,  all  of  which  are  connected  to  the  tube  d,  by  way 


of  which  the  condensed  fluids  are 
made  to  flow  baok  into  the  stilL  By 
properly  regulating  .the  boiling  of 
the  liquid  in  the  first  still  and  by 
adjusting  the  flow  of  wine,  (he 
condeusation  of  the-  TaponiB  in  the 
dephlegmator  con  be  arranged  at 
will.  BO  that  either  brandy  of  50 
per  cent  or  alcohol  of  above  80  per 
cent  be  obtained. 

Sometimes  an  apparstns  of  eren 
more  simple  constmetioa  is  em- 
ployed, in  which  the  fluid  to  be 
distilled  is  heated  by  a  spiral  ti^ 
through  which  high- pressure  steam 
is  made  to  eirciilat«.  Such  an 
apparatus  is  exhibited  in  Fig.  341. 
1.  is  a  cast-iron  or  copper  cylinder, 
in  which  the  fluid  to  be  distilled 
is  heated  by  a  spiral  tnbe  made 
of  copper ;  the  inlet  of  this  tnbe  is  at 
h,  and  the  outlet  at  a ;  by  means  of  ( 
the  vinasse,  devoid  of  alcohol,  is  nn 
oflT.  B  is  the  dephlegmator.  throng 
which  the  fluid  to  he  distilled  con- 
tinually  flows  in  a  downward  direction,  while  the  vapour  of  the  low  wine  evolved  is  a 
ascends  uninterruptedly.  In  order  to  increase  the  surface  and  points  of  contact  the 
arrangement  in  the  deplegmator  is  very  difierent.  The  vapour  ascends  to  the  reservoir, 
E,  and  by  way  of  the  tube  f  enters  the  rectificator,  c,  which  is  arranged  as  osnal ;  the 
condensed  portion  returning  throngh  h  to  the  dephlegmator,  while  the  uncondensed 
vapour  passes  on  to  Ihe  condenser  of  the  vessel  d  there  to  become  oondensed 


SPIRIT,  445 

and  carried  off  throngh  m.  The  fluid  to  be  distilled  is  kept  in  a  tank  (not  represented 
in  the  cut)  placed  higher  than  the  apparatus,  being  conveyed  to  the  latter  by  way  of 
the  tube  l  i  fitted  with  the  stop -cock  k,  so  that  the  liquid  arrives  first  in  d,  is  next 
conveyed  to  c,  thence  through  o  into  the  dephlegmator,  and  lastly  into  the  cylinder. 

"'"'^'DrfSSiSr*  ^^  It  has  been  already  mentioned  (see  p.  431)  that  in  addition  to 
ethylic  alcohol  there  are  formed  during  vinous  fermentation — ^under  conditions  not  at 
all  clearly  understood  nor  scientifically  elucidated — ^larger  or  smaller  quantities  of 
alcohols  homologous  with  ethylic  alcohol ;  such,  as,  for  instance,  propylic,  butylic, 
amylic  alcohols,  which,  when  mixed  with  larger  or  smaller  quantities  of  complex* 
ethers,  bear  the  name  of  fusel  oil,  a  fluid  which  imparts  to  the  ethylic  alcohol  (in 
the  shape  of  brandy,  gin,  whiskey,  &c.)  a  very  unpleasant  flavour,  also  rendering 
these  spirits  when  crude  very  injurious  to  the  human  system.  Fusel  oil  differs 
according  to  the  nature  of  the  mash,  potatoes,  grain,  and  beet-roots  being  used 
in  its  preparation.  Fusel  oil  is  formed  in  large  quantity  only  when  fermentation 
takes  place  at  a  high  temperature  in  a  concentrated  saccharine  fluid,  while  no 
tartaric  acid  is  simultaneously  present.  A  fluid  which  ferments  at  a  low  temperature 
and  is  very  dilute  does  not  yield  fusel  oil,  at  least  no  amylic  alcohol,  which  also  is 
never  formed  in  such  wines  as  have  been  fermented  when  tartaric  acid  has  been 
present  in  the  fermenting  fluid. 

As  it  is  a  property  of  all  fusel  oils  that  they  are  less  volatile  than  water  and 
alcohol,  they  are  only  condensed  when  brandy,  gin,  whiskey,  &c.,  are  distilled  towards 
the  end  of  the  distillation ;  while  as  regards  the  distillation  of  the  alcohol  these  oils 
are  chiefly  met  with  in  the  products  of  the  condensation  of  the  dephlegmators.  A 
portion,  however,  of  the  fusel  oils  comes  over  along  with  the  alcohol,  and  being 
very  intimately  mixed  therewith  is  not  readily  removed  from  these  fluids.  Potato 
fusel  oil  is  essentially  amyUo  alcohol  iC5HiaO),  a  colourless,  very  mobile  fluid 
of  0*818  sp.  gr.,  of  penetrating  odour,  provoking  coughing,  and  of  a  burning  taste ; 
it  boils  at  133''.  By  means  of  oxidising  agents,  such  as  manganate  and  per- 
manganate of  potash,  a  mixture  of  sulphuric  acid  and  bichromate  of  potash,  or 
nianganese  as  well  as  platinum  black,  amylic  alcohol  is  converted  into  valerianic 
acid  (GjHxoOa).  By  the  action  of  acids  this  amylic  alcohol  is  tM)nvertei  into  peculiar 
kinds  of  ethers  in  the  same  manner  as  this  effect  is  produced  by  acids  upon  ordinary 
(ethylic)  alcohol.  Some  of  the  ethers  thus  formed  exhibit  a  highly  agreeable 
odour,  and  are  therefore  used  in  perfumery,  and  for  the  flavouring  of  sweetmeats, 
bon-bons,  &c. 

As  for  many  of  the  applications  of  potato-spirit  the  fusel  oil  is  a  disadvantage, 
the  spirit  has  therefore  to  be  submitted  to  an  operation  of  rectification  whereby  the 
fusel  oil  is  got  rid  of.  The  suggestions  which  have  been  made  for  this  purpose  refer 
either  to  the  destruction  of  the  fusel  oil  by  oxidation  or  the  action  of  chlorine,  or  the 
luasking  of  the  oil  and  its  conversion  into  less  disagreeable  compounds;  partly 
Also  to  a  real  removal  of  the  fusel  oil  from  the  spirit.  When  the  fusel  oil  con- 
timing  spirit  is  rectified  over  chloride  of  lime  (bleaching-powder),  permanganate  of 
potassa,  &c.,  valerianate  of  fusel-ether  is  formed;  but  since  the  action  of  these 
reagents  is  not  limited  to  tlie  amylic  alpohol  but  extends  to  the  ethylic,  it  is 
^eiy  difficult  to  adjust  the  quantity  of  these  reagents  so  that  only  the  amylio 
^cohol  be  acted  upon.  If  the  spirits  from  which  the  fusel  oil  is  to  be  re- 
moved are  treated  with  a  mixture  of  sulphuric  add  and  vinegar,  th'ere  is  formed. 


CHEMICAL   TECHSOLOOT. 


besides  some  acetic  etlier,  acetate  of  amyl,  ^,'^^  \  0.  of  a  pleasant  frui^  BaToar. 
Hydrocliloric  and  iiitric  acids,  also  used  to  remove  fusel  oil,  act  in  a  aomevhit 
Bimilar  manner.  The  must  nppinved  method  of  removing  the  fusel  oil  is  by  m 
of  well-burnt  cliarcoal  Ivej^eUble  cliarcoal.  charred  peat,  bone-black),  which,  whni 
brought  iuto  contact  nith  the  crude  spirit,  absorbs  the  fusel  oil  meclianicallj- 
the  aid  of  charcoal,  spirits  and  brandy  (not  when  obtained  from  wine),  are  pnrifi«d  I 
either  in  the  state  of  vapour,  or  by  digestion  witli  tlie  charcoal,  and  filtiBtion  at  ik 
'ordinary  temperature  of  the  air;  rectification  at  boiling  temperature  over  charcoal 
is  altogether  unsuitable,  owing  to  the  fact  tliat  the  fusel  oil  absorbed  by  the 
charcoal  is  again  readily  dissolved  at  that  temperature.  The  charcoal  to  be 
employed  ia  granulated  and  passed  through  a  sieve  in  order  to  remove  adhe- 
ring dust.  The  granulated  charcoal  is  placed  in  a  copper  cylinder,  fitted  at  lop 
and  bottom  with  a  perforated  plate  or  disc;  this  cylinder  is  connected  with  the 
distilling  apparatus  between  tlie  dephlegmator  and  rectificator  in  such  a.  manner  thit 
the  vapours  pasa  through  the  charcoal.  To  loo  litres  of  brandy  to  be  pnrjfied  3  to  s 
litres  of  granulated  charcoal  are  generally  required ;  this  can  be  ^ain  employed  aftv 
Jiaving  been  re-bomt  at  a  bright  red  heat.  Fallonaii  ■ 
apparatus  consists  of  a  helm-ahaped  vessel,  a.  Fig.  141. 
in  which  tlie  perforated  diaphragms,  bbb,  are  placed ; 
upon  each  diaphragm  a  layer  of  charcoal,  snrmonnteil 
"tj/Vsan  ^th  a  cover,  c,  is  placed.  The  apparstns  is  clowd 
'W"^  with  a  hollow  cover  containing  a  layer  erf  charcoaL 
iMb^'  dd.  Tlie  vessel  a  is  surrounded  by  a  cooling  app*- 
ratuB,  which  in  the  cut  is  represented  by  the  cold  water 
tubes,///,  and  the  hot  water  (which becomes  hot  by  tlia 
passage  of  alcoholic  vapours  through  x)  tabes,  etic. 
these  serve  tlie  purpose  of  regulating  the  temperstn* 
of  the  layers  of  charcoal. 

iMdoiAWBiioi.  The  quantity  of  alcohol  obtainable  fro* 
any  given  substance  does  not  only  depend  on  the  reli- 
tive  quantity  of  the  alcohol-fonning  constitnoit* 
(starch,  dextrose,  or  cane  sugar)  of  the  raw  material  applied  for  the  poipoff 
of  distillation,  but  depends  very  largely  also  on  the  more  or  less  snitAble.mode 
of  condncting  all  the  operalioDS  of  the  spirit  distillation  (mashing,  fennentationi,  >■ 
properly  constructed  apparatus.  Leaving  out  of  the  question  the  small  quanlitiM 
of  glycerine  and  succinic  acid  formed  by  vinous  fermentation,  chemistry  teacba 
that:- 

100  parts  of  starch  yield   567S  of  alcohol 

100       „       cane  sugar       „      5380         „ 
100       „       dextrose  „      3101         „ 

Experience  teaches  that  the  yield  of  alcohol  is  in  practice  leas  than  it  should  be. 
premising  that  every  i  mol,  of  starch  or  sugar  yields  2  mob.  of  alcohol ;  100  part*  <i 
cane  sugar  do  not  yield  in  practice  the  quantity  of  alcohol  above  indicated — vii.  5J'8 
parta,bnt  only  511. 


SPIRIT,  447 

loo  kilos,  of  barley  give  44*64  litres  of  corn  brandy  at  50**  Tralles.  * 

100        „        barley-malt     „     54*96 

100        „        wheat  „     49*22       „  „         „  „  „ 

100       „         rye  „     45*80       „  „  ,.  „ 

100       „        potatoes  „     18*32       „        potato  spirit     „  „ 

6  litres  (quart  or  maas)  o^ brandy,  from  the  metrical  hundredweight  (hectolitre,  Ac.), 
is  reckoned  to  yield  6  X  50  =  300  per  cent  alcohol ;  7  litres,  consequently,  350 ; 
8  litres,  400.  8  litres  at  48  per  cent  Tralles  =  384  per  cent  alcohol.  The  number  of 
litres  of  brandy  or  spirit  multiplied  by  the  alcohol  in  percentage  according  to 
Tralles  therefore  yield : — 

metrical  cwt  of  barley  44*64  X  50  =  2232  per  cent  alcohol. 

„  „       barley-malt  5496  X  50  =  2748         „  „ 

„  „       wheat  49*22x50  =  2461         „  „ 

rye  4580X50  =  2290        „ 

„       potatoes  18*32x50=   916         „  „ 

Usually  I  Bavarian  maas  is  taken  as  equal  to  1069  litres,  i  Prussian  quart  =  1*145 
litres. 

In  quoting  the  prices  in  the  following  foreign  markets,  it  is  usual  to  take  aa 
a  unit — 

In  Breslau  4,800  (  60  quarts  at  80°). 

In  Berlin  10,800  (200        „        54^). 

In  Magdeburg    14400  (180        „        80''). 

Recently  it  has  become  general  to  adopt  as  a  unit  8000  (100  quarts  at  80°). 

AicobokmMtiy.      For  the  purpose  of  ascertaining  the  quantity  of  alcohol  contained  in  a 
fluid  which  consists  only  of  alcohol  and  water,  the  areometer,  or  alcoholometer,  is 

ArwBMttf.  generally  employed.  The  vaporimeter  and  the  ebullioscope  (see  p.  395) 
-are  seldom  used.  The  application  of  the  ai'eometer  is  based  upon  tlie  principle  that  a 
body  immersed  in  a  fluid  (for  instance,  water)  always  displaces  a  quantity  of  water 
equal  to  its  own  volume,  and  loses  in  weight  proportionately  to  the  quantity  of  water 
displaced.  It  therefore  follows,  that  by  the  depth  to  which  the  areometer  sinks,  as 
noted  by  the  degrees  on  the  spindle,  we  can  determine  the  quantity  of  absolute 
alcohol  contained  in  the  fluid  under  examination.  The  areometer  of  Tralles  and  that 
of  Richter  are  most  generally  used  in  Germany.  Stoppani's  is  similar  to  that  of 
Richter.  Both  are  centesimal  alcoholometers  and  show  by  the  number  of  the  degree 
to  which  they  sink  the  percentage  of  pure  alcohol.  Tlie  difference  between  these 
two  instruments  consists  in  that  the  areometer  of  Tralles  indicates  percentage  by 
volume,  and  Richter's  percentage  by  weight.  Tralles*s  alcoholometer  is  much  used 
in  the  ZoUverein  (German  Custom's  Association,  viz.  of  the  various  States  constitu- 
ting, with  the  exception  of  Luxemburg,  the  German  Empire)  for  the  purpose  of 
ascertaining  the  alcohol  contained  in  spirituous  liquors  (at  14*44° ^)  >  ^  Austria  the 
same  instrument  is  used,  with  a  difference,  however,  in  the  temperature  at  which 

the  observation  is  made,  the  degree  of  the  thermometer  being  usually  taken  at 

12'' R.  (=1500.) 
The  following  table  exhibits  a  comparison  of  both  scales,  and  with  the  tma 

Weight  per  cent,  along  with  the  corresponding  specific  gravity  at  a  temperature  of 

15' C.:— 


443  CHEMICAL  TECHNOLOGY. 


Sp.gr. 

Trne  weight 
per  cent. 

per  oent  according 

▼olmne  aee 

to  Biohter. 

to  Trail 

0*990 

4*99 

5 

623 

0-981 

ii-ii 

10 

1373 

0972 

l8-I2 

15     • 

22'20 

0964 

2483 

20 

30-16 

0956 

2982 

25 

36-50 

0947 

3529 

.    30 

42*12 

0*937 

40*66 

35 

48*00 

0926 

46*00 

40 

53-66 

0-915 

5x02 

45 

5882 

0906 

54-85 

50 

62-65 

0899 

6034 

55 

6796 

0-883 

64-79 

60 

72*12 

0872 

69-79 

65 

7666 

0-862 

74*66 

70 

80-36 

0850 

78*81 

75 

84-43 

0-838 

83*72 

80 

88-34 

0*827 

8836 

85 

91-85 

0-815 

9254 

90 

9505 

0805 

9677 

95 

97'55 

0795 

99*60 

100 

9975 

The  most  usual  alcoholometer  is  that  which  indicates  the  percentage  of  yolaine,  or  faov 
many  volmnes  of  absolute  alcohol  there  are  contained  in  100  volumes  of  the  tdet^cik 
fluid.  Brandy  of  50°  Tralles  is  therefore  understood  to  be  a  spirit,  100  litres  of  which 
contain  50  litres  of  alcohol ;  and  from  which  by  distillation  these  50  litres  of  alcohol  obo 
be  extracted.  Considering  that  when  alcohol  and  water  are  mixed  a  considerable  oontn^- 
tion  and  decrease  of  bulk  is  the  result,  it  is  clear  that  50  litres  of  alcohol  (absolute  is  hen 
meant)  and  50  litres  of  water  will  only  yield  a  mixture  measuring  96-377  litres ;  tad 
accordingly  100  litres  of  such  a  fluid  contam  instead  of  50  litres  of  alcohol,  51-88  litrw  « 
that  liquid. 

Beution  of  Brandy  ^Q  relation  of  the  distillation  industry  to  agriculturet  and  M« 
Dtatming  to  ▲grieaunx^  especially  as  a  means  of  providimg  fodder  for  cattle,  is  very  interesti^ 
and  important.  The  distillation  of  spirits  leaves  a  residue  which  may  be  usefully  employw 
as  fodder  for  cattle ;  the  distillatory  process  extracts  from  the  starch-containing  matensv 
which  are  employed  only  the  alcohol  which  is  formed  in  the  mash  by  fermentation,  but  it 
leaves  behind  in  a  concentrated  state  all  the  nutritive  substances  (especially  albumfli 
compounds),  which  not  being  acted  upon  by  the  fermentation,  are  left  in  the  residues  ib 
almost  the  same  state  as  they  were  originally  present  in  the  potatoes  and  grain  made  usi 
of  by  the  distiller.  It  is  evident  that  when  the  expenses  of  the  production  of  the  ^}^ 
are  paid  to  the  distiller,  the  residues  of  the  operation  become  a  viduable  material  obisio^ 
cost  free,  the  production  of  which  is  an  important  item  in  this  industry. 

Viewed  in  the  light  of  agricultural  industry  the  preparation  of  spirits  from  potatoes 
becomes  in  reality  a  chemical  decomposition  of  the  substances  of  which  potatoes  are  ocun- 
posed,  and  a  product  of  a  relatively  far  greater  value,  and  more  readily  transpoitalw 
and  preservable — ^viz.,  spirits  and  wash,  and  fodder  material. 

The  BoddiM  or  wuh.  The  wash  is  a  fluid  in  which  starch,  dextrine,  pectin  substanees,  J^ 
tein  compoimds,  fat,  small  quantities  of  sugar,  husks  of  grain,  succinic  acid,  ^yeenstt 
salts,  and  some  of  the  constituents  of  yeast  are  met  with,  partly  in  solution,  partly  ^ 
pended,  while  some  of  these  materials  are  more  or  less  decomposed  and  altered.  ^ 
quantity  of  dry  substance  only  amounts  to  from  4  to  10  per  cent ;  this  is^  due  to  to* 
varying  nature  of  the  raw  material,  to  the  quantity  of  water  used  in  mashing,  and  f^ 
the  unequal  quantity  of  water  absorbed  by  the  fermented  mash  during  the  process  of  ^ 
tillation. 


SPIRIT,  449 

Hitthaasen  analyBed  soveral  yarieties  of  wash  with  the  following  results,  the  proportion 
of  dry  snbstance  to  the  water  being  in  (I.)  as  i :  7*3 ;  in  (II.)  as  i :  6 ;  in  (HI.)  as  i :  4*08 ; 
.    in  (IV.)  as  X  :  4 ;  in  (V.)  as  i :  3  : — 

itr'  I.  n.  m.  IV.  V. 

•-          Non-nitrogenons  substances  278  3*23  3*08  4-14  5*31 

Protein  compounds     ..     ..  o'82  1-04  ^        i'26  1-39  178 

Cellulose       0-46  043  '       0*94  078  I'oo 

Ash        0*52  0*59  072  079  I'oi 

;           Water 95'40  947^^  .       94'oo  92*90  9090 

When  in  a  distillery  potatoes  and  malt  are  always  used  in  equal  quantities  and  of  the 
;    same  quality,  and  the  mash  made  at  the  same  degree  of  concentration,  the  wash  will 

always  be  of  nearly  as  possible  the  same  composition.     It  may  be  assumed  thst,  on  an 

average,  three-fourths  of  the  solid  matter  met  with  in  the  wash  is  nutritive;  the 
'    proportion  of  nitrogenous  to  non-nitrogenous  matter  is  on  the  average  as  x  :  3,   while 

in  the  potato  it  is  only  as  x :  8.  When  the  potatoes  are  converted  into  wash  they  lose 
:     the  greater  part  of  their  non-nitrogenous  matter,  and  thus  become  a  fodder  rich  in 

protein   compounds.     In  practice,  X50  to  250  kilos,  of  potato  mash  are   considered 

equivalent  to  50  kilos,  of  hay. 

DryYaasL  By  tlio  fermentation  of  the  beer- wort  containing  hops,  yeast  is  pro- 
duced in  large  quantities,  and  tliis  is' used  in  most  cases  when  it  is  desired  to  induct 
a  vinous  fermentation ;  but  for  some  purposes,  such  as  bread-making  for  instance, 
this  yeast  is  not  applicable  o^ving  to  its  containing  much  of  the  bitter  principle  of 
the  hop,  and  tlierefore  possessing  a  very  disagreeable  flavour.  This  bitter  principle 
may  be  removed  by  thorouglily  washing  with  cold  water,  or.  as  recommended  by 
Trommer,  by  iirst  dissolving  the  yeast  in  a  solution  of  caustic  alkali,  and  then  pre- 
cipitating it  therefrom  by  means  of  dilute  sulphuric  acid :  such  proceedings,  how- 
ever,  always  impair  the  efficacy  of  the  yeast  as  a  ferment,  and  the  additional  amount 
of  time  and  labour  required  necessarily  enliances  tlie  price  of  the  yeast.  The  pro- 
duction of  yeast  in  breweries  is,  moreover,  only  a  subordinate  affair,  the  main 
point  being  the  preparation  of  beer  of  good  quality.  The  production  of  yeast, 
although  it  can  only  be  obtained  by  vinoua  fermentation,  is  best  combined  with  the 
distillation  of  spirit,  whereby,  if  desii'ed,  the  preparation  of  dry  yeast  may  be  made 
a  principal,  and  the  production  of  spirit  to  a  certain  extent  a  subordinate, 
affair. 

We  have  in  a  former  portion  of  this  work,  while  treating  on  fermentation  in  general, 
explained  tlie  mode  of  formation  and  the  nature  of  tlie  yeast,  and  that  this  yeast  has 
been  proved  by  experience  to  be  best  fed  and  most  rapidly  propagated  by  the  gluten 
and  other  protein  compounds  of  tlie  cereals  in  solution.  Yeast  may  be  made  in  various 
ways.  At  Schiedam  (Holland)  it  is  made  of  excellent  quality  by  a  mode  which  is  to 
a  certain  extent  a  trade  secret — and  differs  materially  from  the  following  process : — 
A  mash  is  made  in  the  ordinary  manner  of  i  part  of  bruised  barley  malt  with 
3  parts  of  bruised  rye,  tlie  mash  being  cooled  with  the  fluid  portion  of  the  wash. 
To  100  kilos,  of  Uie  bruised  grain  is  added  0*5  kilo,  of  carbonate  of  soda  and  035 
kilo,  of  sulphuric  acid  diluted  with  water ;  these  ingredients  having  been  added  to 
the  mash  it  is  brought  to  fermentation  by  the  aid  of  yeast.  The  newly-formed 
yeast  is  removed  from  the  strongly-fermenting  fluid  by  tlie  aid  of  perforated  ladles ; 
it  is  tlien  strained  through  a  linen  cloth  or  fine  sieve,  and  poured  into  cold  water, 
wherein  it  is  allowed  to  form  a  sediment.  The  sedunent  tlms  produced  is  col- 
lected after  the  supernatant  water  has  been  run  off,  is  placed  in  a  stout  canvas 
ottg  under  a  press,  and  formed  into  a  stiff  clayey  dough,  to  which  usually  4  to  10 

2  o 


450  CHEMICAL  TECHNOLOGY. 

(sometiines  as  much  as  24)  per  cent  of  dry  potato  starch  is  added.  Sometimes  fha 
water  is  removed  from  the  yeast  by  placing  that  substance  upon  slabs  made  of 
gypsum  or  other  absorbent  materials,  care  being  taken  to  keep  the  yeast  in  a 
cool  place ;  by  the  use  of  the  hydro-extractor — expressly  arranged  as  regards  its 
construction  for  this  purpose — ^jeast  may  be  very  rapidly  rendered  dry.  As  regards 
the  use  of  the  carbonate  of  soda,  it  appears  to  assist  in  the  separation  of  the  glu- 
tinous constituents  of  the  cereals;  the  action  of  the  sulphuric  acid  is  partly 
similar,  and  it  also  prevents  the*  formation  of  lactic  acid,  which,  if  formed,  canaet 
a  loss  of  both  starch  and  spirit ;  the  sulphuric  acid  also  accelerates  the  separatioii  of 
the  yeast.  According  to  communications  by  some  of  the  most  eminent  distillers  at 
Schiedam  to  Dr.  G.  J.  Mulder,  neither  soda  nor  sulphuric  acid  are  used  at 
Schiedam  in  the  preparation  of  what  the  trade  terms  dry  or  German  yeast,  some  of 
which  is  imported  into  this  country  from  Hamburg.  Assuming  the  researches  of 
Pasteur  and  others  on  fermentation  to  be  correct,  these  observations  are  of  great  Talae 
in  reference  to  the  manufacture  of  yeast.  It  is  found  that  the  yeast  spomlse  heoome 
properly  developed  when  they  are  placed  in  a  fluid  which,  instead  of  oontaining 
protein  compounds,  consists  of  aqueous  saline  solutions  mixed  with  a  sngar 
solution,  such  as,  for  instance — ^tartrate  of  ammonia,  phosphate  of  potash,  gypsmD, 
phosphate  of  magnesia.  It  would  hence  appear  that  under  such  conditions  yeast 
cells  take  up  the  material  for  the  propagation  of  new  cells,  partly  from  inoiganie 
substances,  partly  from  organic,  viz.,  the  decomposing  sngar  which  yields 
carbonic  acid:  in  this  respect  the  yeast  cells  agree,  then,  with  higher  organised 
plants.  As  regards  the  quantity  of  yeast  obtainable  from  a  given  weight  of 
materials,  it  may  be  stated  that  from  100  kilos,  of  rye,  including  the  bmised  malt, 
about  15  to  16  kilos,  of  dry  yeast  can  be  obtained.  As  the  quantity  of  real  yeast 
or  of  the  nitrogenous  matter  for  sale  present  in  the  ready  prepared  dry  yeast  amomits 
at  the  most  to  20  per  cent,  the  nutritive  value  of  the  wash  obtained  after  the  dis- 
tilling o£f  of  the  spirits  from  the  fermented  liquid  is  but  little  impaired. 


so^aiiBd  Axtifldai  TcMt.  We  have  yet  to  refer  to  what  is  termed  artificial  yeast,  in 
a  substance  only  intended  for  transferring  the  fermentation  of  the  wort  or  maah  in 
activity  to-day  to  a  fresh  batch  to-morrow,  so  that  it  bears  the  same  relation  to  the 
spirit  preparation  as  leaven  does  to  bread-baking.  Tbere  are  a  great  number  of 
recipes  for  the  preparation  of  artificial  yeast  and  of  artificial  fermentation-indaeing 
substances;  as  far  as  these  are  known  they  may  be  brought  to  the  following  eale- 
gories: — i.  A  small  quantity  of  fully  and  strongly  fennenting  mash  is  mixed  with 
fresh  mash.  2.  A  small  quantity  of  the  fl^nid  portion  of  the  fennenting  mash 
is  cautiously  drawn  off  by  tbe  aid  of  a  syphon,  and  this  portion  having  been  set 
into  fermentation,  is  added  to  the  freshly  made  mash  of  the  next  day.  3.  As  sood 
as  in  the  last-made  mash  the  fermentation  is  strongest  and  most  active,  a  small 
quantity  of  the  ferment  (yeast)  separated  from  the  fluid,  and  floating  on  its  surface,  is 
minced  wi^  freshly  made  mash,  the  temperature  of  which  has  been  purposely  made 
sufficiently  high  to  start  the  fermentation.  The  mash  thus  prepared  may  be  used  after 
a  few  hours  to  induce  fermentation  in  a  freshly  made  mash.  A  really  artificial  yeast, 
that  is,  yeast  only  prepared  for  the  purpose  of  obtaining  that  substance  by  itself  and 
independent  of  either  brewing  or  distilling,  is  made  in  various  ways,  but  always  by  a  real 
process  of  fermentation.  As  an  excellent  instance  of  this  mode  of  preparation,  we  quote 
the  mode  of  preparing  Vienna  yeast : — 

vieniuTMat.  This  yesst  is  prepared  in  the  following  manner: — Previously-malto^ 
barley,  mais,  and  rye  are  ground  up  and  mixed,  next  put  into  water  at  a  temperatore  of 
65°  to  75°;  after  a  few  hours,  the  saccharine  liquid  is  decanted  from  the  dregs,  and 
the  clear  liquid  brought  into  a  state  of  fermentation  by  the  aid  of  some  veast.  Tbe 
fermentation  becomes  very  strong,  and,  by  the  force  of  the  carbonic  acid  which  is  evolved, 
the  yeast  globules  (the  size  of  which  averages  from  10  to  x  2  m.m.)  are  eanied  to  the 


BREAD,  451 

BoHaee  of  the  liqiiid,  and,  forming  a  thick  scum,  are  removed  by  a  skimmer,  then  placed 
on  cloth  filters,  drained,  washed  with  a  little  distilled  water,  and  next  pressed  into 
any  desired  shape  by  means  of  hydranlio  pressure,  and  coTered  with  a  strong  and  wdl 
woVen  canvas.  This  kind  of  yeast  keeps  for  eight  to  fourteen  days  according  to  the  season, 
and  is,  both  for  bakers  and  brewers,  very  superior  to  that  ordinarily  used ;  the  extra  good 
qualities  of  Vienna  beer  and  bread  are  partly  due  to  the  use  of  this  yeast  in  preparing 
these  articles. 

i>aty  on  Siiixtta.  In  the  Original  work  a  couple  of  pages  are  devoted  to  an  uninteresting 
discussion  on  this  subject,  which,  as  might  be  expected,  has  been  treated  not  from  a 
general  point  of  view  but  from  one  bearing  upon  conditions  which  are  altogether 
different  from  those  existing  in  this  country.  There  can  be  no  doubt  that  a  duty 
on  spirits  is  a  very  excellent  thing ;  indeed,  in  this  country  this  tax  brings  in  such  an 
enormous  sum  as  to  lead  to  the  inference  that  spirits  are  consumed  in  larger  quantities 
than  is  consistent  with  healthy  conditions  of  body  and  social  comfort. 

Bread  Baking. 

ModMofBiMdVAidBc.  The  preparation  of  bread  aims  at  the  production  in  the  flour 
obtained  by  grinding  np  the  cereals  of  such  a  chemical  and  physical  condition  as 
will  tend  to  render  it  most  readily  masticated  by  the  teeth,  and  after  having 
been  duly  mixed  with  saliva  in.  the  mouth,  digested  by  the  juices  of  the  stomach. 
When  flour  is  mixed  with  water  so  as  to  form  a  dough,  and  this  mixture  dried  at  the 
ordinary  temperature  of  the  atmosphere,  a  kind  of  cake  is  obtained  which  contains  the 
starch  unaltered  and  in  an  insoluble  state,  so  that  this  kind  of  cake  is  very  difficult 
to  digest,  while,  moreover,  its  taste  is  so  unpleasant  as  to  create  no  appetite. 
Again,  if  the  cake  is  dried  at  the  boiling-point  of  water,  it  becomes  like  a  dried 
starch  paste,  which  is  also  very  difficult  to  digest.  When  this  temperature  only  acts 
upon  the  surface  of  such  dough,  and  does  not  penetrate  into  the  interior,  the  resulting 
cake  will  be  a  mixture  somewhat  similar  to  ship's  biscuit,  which  may  always  be 
considered  as  a  strongly-dried  dough,  and  although  it  may  be  preserved  for  almost 
any  length  of  time,  it  is  far  less  digestible  than  bread.  The  object  of  the  baking 
process  is  to  impart  to  the  dough  so  high  a  degree  of  heat  as  to  render  the  starch 
soluble,  while  it  is  further  desired  to  form  a  light  spongy  ma^,  instead  of  a 
brittie  or  watery  paste ;  the  heat  should  be  strong  enough  to  torrify  and  roast  the 
outer  surface  of  the  bread  mass  to  such  an  extent  as  to  form  a  deeply  coloured 
crust,  whereby  not  only  the  taste  of  the  bread  is  greatly  improved,  but  it  can 
also  be  kept  in  good  condition  for  some  time.  The  usual  means  of  rendering 
dough  spongy  is  by  vinous  fermentation  set  up  by  the  addition  of  a  ferment,  this 
being  either  leaven  or  yeast;  a  small  portion  of  the  starch  of  the  flour  is  thus 
converted  into  glucose,  which  is  then  decomposed,  yielding  alcohol  and  carbonic  acid 
gas;  the  latter,  while  trying  to  escape,  is  prevented  from  doing  so  by  the  toughness 
of  the  dough,  which  is  thereby  rendered  spongy. 

The  alcohol  is  of  no  consequence  whatever.  White  bread  is  prepared  with 
wbeaten  flour  and  yeast;  rye  meal  or  a  mixture  of  rye  meal  and  wheaten  flour  with 
leaven,  yields  "  black"  or  rye  bread.  Heeren  found  that  flour  in  the  state  in 
which  it  is  usually  applied  for  bread  baking  contains  an  average  of  13  per  cent 

moisture. 

Th*  Drtaita  of  BiMd  BaUaf.  The  raw  material;  employed  in  the  preparation  of  bread  are 
flour,  water,  and  a  ferment;  salt,  spices,  &c.,  are  also  used.    The  composition  of  the 

most  important  kinds  of  flour  and  meals  is  as  follows : — 

a  o  a 


452  CHEMICAL  TECHNOLOGY, 

a.  h,  c.  d. 

Water i5'54  14*60  1400  117a 

Albumen       i'34  1*56  vzo  1*24 

Vegetable  glue     176  292  3*60  3-25 

Casein 037  0*90  i'34  0*15 

Fibrin    519  736  824  14-84 

Gluten 3*50  —  —  — 

Sugar    2*33  346  3*04  219 

Gum      625  410  633  2*8i 

Fat        107  i'8o  223  567 

Starch •  63-64  6428  5315  58-13 

Sand     —  —  685  — 

a.  Wheat  flour,    h.  Bye  meal.    c.  Barley  meal.    d.  Oatmeal. 

In  addition  to  these  kinds  of  meal,  those  derived  from  zea-mais  (Indian  com) 
beans,  peas,  &c.,  are  occasionally  employed  for  making  bread. 

The  principal  phases  of  the  preparation  are : — 

""m?!!! &iJid£S?*^  I.  The  mixing  of  tlie  flour  with  water  is  the  first  manipulation 
of  the  ba^Qg  process.  The  object  of  this  operation  is  first  to  render  dextrin  and 
si^ar  (owing  to  the  action  of  the  gluten  upon  the  starch,  tlie  quantity  of  sugar 
becomes  increased  while  the  mixing  process  is  going  on)  and  some  albuminooB 
substances  soluble,  and  next  to  mix  the  solution  thus  formed  thoroughly  with 
the  starch  and  gluten  of  the  flour,  and  to  soak  and  somewhat  dissociate  these 
substances ;  dry  yeast  or  leaven  are  at  the  same  time  added  to  the  bread  mass,  the 
former  ferment  being  used  when  it  is  intended  to  make  white;  the  latter  when 
black  bread  is  desired  to  be  made. 

By  sour  dough  or  leaven  is  understood  that  portion  of  the  already  fermenting 
dough  which  is  set  apart  and  kept  for  the  next  baking  operation ;  it  consists  of  a 
mixture  of  flour  and  water,  in  which  a  portion  of  tlie  starch  is  converted — 
partly  into  sugcur,  which  is  again  changed  by  vinous  fermentation,  and  acetic 
add — ^but  chiefly  into  lactic  acid,  by  a  process  of  fermentation  set  up  hy  the 
peculiar  conversion  into  active  ferments  of  the  protein  compounds  of  the  flour 
itself.  Leaven  therefore  acts  as  a  fermentation-producing  substance  in  a  fresh 
batch  of  dough,  its  action  being  similar  to  that  of  yeast,  or  of  already  fermenting 
wort  when  added  to  a  freshly  made  wort.  After  a  length  of  time  the  leaven 
becomes  putrid  and  unfit  for  use  as  a  ferment.  As  regards  the  quantity  of  leaven 
to  be  used  with  the  dough  nothing  definite  can  be  said,  since  it  depends  as 
much  on  the  degree  of  sourness  of  the  leaven  as  on  the  quality  of  the  bread  in- 
tended to  be  made;  usuaUy  4  parts  of  leaven  are  added  to  100  parts  of  flour,  or  to 
80  parts  of  bread  3  parts  of  leaven.  In  the  case  of  white  bread,  100  parts  of  flour 
require  2  parts  of  dry  yeast.  The  mixing  of  tlie  flour  is  effected  with  lukewarm 
water,  at  a  temperature  of  from  21°  to  37*. 

Knoiding.  The  thin  dough  obtained  from  flour,  water,  and  ferment,  is  dredged  over 
with  dry  flour,  and  placed  in  a  warm  situation  for  a  time,  generally  during  the 
night.  Fermentation  is  thus  set  up  by  the  action  of  the  ferment  upon  the  dextrose 
of  the  dough,  the  .carbonic  acid  developed  rendering  the  dough  spongy.     The 


BREAD.  453 

sponge  thus  prepared,  is  next  mixed  with  more  floar  to  bring  it  to  the  consistency 
required  for  t}ie  baking,  this  operation  being  known  as  the  kneading  of  the 
sponge.  The  method  usually  employed  in  these  operations  is  that  one-third  of 
the  total  quantity  of  flour  required  for  a  batch  is  mixed  first  with  water  and 
ferment,  and  when  this  mass  has  come  into  fall  fermentation,  the  two  other  thirds 
of  flour  are  kneaded  up  along  with  the  sponge,  sufficient  water  being  added  to 
form  a  normal  dough.  After  .the  kneading  operation  the  dough  is  again  dredged 
over  wiOi  some  dry  flour,  and  left  in  a  warm  situation  for  the  purpose  of  becoming 
thoroughly  spongy :  for  this  continued  fermentation  only  about  half  the  time  is 
required  as  for  the  first-mentioned  fermentation.  In  most  bakeries,  however,  this 
second  fermentation  is  not  proceeded  with,  but  the  dough  is,  inmiediately  after 
having  been  kneaded,  cut  up  and  shaped  into  loaves. 

By  means  of  the  kneading  the  dough  becomes  squeezed  together,  and  has,  there- 
fore, again  to  be  left  in  a  warm  situation  for  further  fermentation,  during  which 
it  heaves  up  and  increases  to  double  its  size.  The  dough  is  generally  put  either  into 
a  basket  or  tied  in  a  stout  cloth,  which  is  previously  dusted  over  with  bran  to 
prevent  the  pasty  mass  adhering  to  the  cloth.  The  bulk  of  the  dough  increases 
twofold.  When  rye  bread  is*  made,  the  dough  is  frequently  moistened  on  its 
external  surface  witJi  lukewarm  water,  applied  by  the  aid  of  a  brush,  in 
order  to  prevent  cracks  in  the  outer  coating  of  the  dough  by  the  evaporation 
of  the  water;  just  before  putting  the  loaves  into  the  oven  this  brushing  over 
with  water  is  repeated.  The  water  softens  tlie  outer  surface  of  tlie  dough, 
and  dissolves  some  of  the  dextrine  it  contains,  which  substance,  after  the  evapo- 
ration of  the  water  from  the  surface,  remains  as  a  glaze  upon  the  crust  of  this 
kind  of  bread.  When  the  loaves  have  risen  sufficiently  and  exhale  a  vinous 
peculiar  odour,  it  is  time  to  commence  the  baking  process.  Since  the  bread  loses 
considerably  in  weight  during  the  baking,  the  baker  must  proportion  so  much  dough 
to  each  loaf  before  baking  as  will  yield  the  legal  weight  of  the  baked  bread.  The 
weight  of  dough  to  be  proportioned  to  a  loaf  of  a  certain  fixed  weight  varies 
according  to  the  size  of  the  loaf,  but  increases  comparatively  with  decrease  in  the 
size  of  the  loaf.  The  dough  generally  loses  in  baking  about  25  per  cent  of  its 
weight.  The  smaller  the  loaf,  the  more  crust  in  proportion  to  crumb ;  and  since  the 
crust  contains  less  moisture,  and,  consequently,  weighs  less  than  the  crumb, 
the  loss  of  weight  is  greater  in  a  small  than  in  a  large  loaf. 

KBMdiiic  mmudm.  The  kneading  of  the  dough  by  hand  is  not  only  very  heavy 
work,  but  is  unhealthy  and  objectionable  on  account  of  being  imdean;  the 
imiform  quality  of  the  dough  is,  moreover,  by  no  means  to  be  depended  upon. 
Although  it  is  impossible  to  perform  by  machinery  any  labour  which  absolutely 
requires  the  touch  of  the  human  hand,  bread-kneading  macliines  have  been 
introduced  wherever  the  making  of  only  one  and  the  same  kind  of  bread  is 
required.  Among  the  numerous  kinds  of  machines  invented  for  this  purpose  we 
select  for  description  that  of  Clayton  (see  fig.  243.)  The  constituents  of  the  dough 
are  placed  in  the  cylinder,  a,  mbunted  in  the  framework,  b  6,  and  provided  with 
hollow  axles,  c  and  d,  turning  in  their  bearings  at  e.  The  interior  of  the  cylinder  is 
fitted  with  the  framework,/,  which  may  be  made  to  revolve  by  aid  of  the  axles  g  and  h. 
The  two  halves  of  this  framework  are  connected  together  by  the  diagonal  knives,  it, 
which,  when  the  machiueiy  revolves,  work  up  the  dough;  the  trough  or  outer 
cylinder  revolves  in  the  opposite  direction  to  the  revolution  of  the  framework.    The 


454  CHEMICAL  TECHNOLOOr. 

crank,  o,  is  connected  with  the  axle  of  the  trongh  or  outer  cylinder ;  the  eraak,  f, 
viiib  that  of  tlie  loner  framework.  As  the  two  cranks  are  tnnted  in  oppomiU 
directions  they  impart  opposite  movements  to  trough  and  frameirork.     The  itrvolviiig 


of  the  machinery  may  be  performed  by  o 
axle,  A,  of  the  crank,  o,  which  is  fitted  to  the  L 
axle-tree,  and  revolves  along  with  it,  carries  i 
the  wheel  A,  which  being  connected  with  I  c. 


the  aid  of  one  crank,  since  tha 
□er  frame  by  means  of  the  hallow 
conicaUy-shaped  wheel,  m,  fitted  to 
)  the  trough  also  to  revolve ;   when. 


therefore,  the  wheel  m  turns  towards  the  right,  the  wheel  I  will  revolve  towards 
the  left. 

TiM  owm.  The  conversion  of  the  prepared  dou^  into  bread  by  baking  is  effected 
in  an  oven,  ordinarily  a  circuhu'  or  oval  hearth  or  Aimace,  spanned  by  a  vaolt, 
constructed  with  an  opening  at  one  end  termed  the  mouth,  serving  alike  for  tha 
introduction  both  of  bread  and  of  the  fueL  The  oven  ie  boilt  of  bricks  cemented 
together  with  fiie-clay,  the  sole  of  the  hearth  being  laid  with  tiles  or  lined  with 
fire-clay.  The  vault  is  usually  elliptical,  in  order  to  reflect  the  heat  as  much  aa 
possible.  The  mouth  is  closed  with  a  door  made  of  boiler-plate  or  of  cast-iron ; 
and  as  the  month  also  serves  as  an  exit  for  the  smoke,  a  flne  is  constructed  at  soma 
short  distance  above  it,  and  made  to  communicate  with  the  chimney.  Two  amall 
openings  in  close  proximity  to  the  month  of  the  oven  serve  to  bum  therein  smaQ 
pieces  of  wood  to  afford  hght,  while  the  bread  is  being  placed  in  the  oven.  The  air 
neeewaiy  for  the  combustion  of  the  fuel  enters  the  oven  from  the  lower  part  of  tha 
month,  while  from  the  upper  the  gases  of  combnatiim  and  tha  smoke  eacape. 
It  is  preferable,  however,  to  construct  these  ovens  with  a  separate  Sua  and 
dmnn^  communicating  with  another  part  of  the  vault,  and  to  fit  the  flue  with  a 
damper  to  regulate  the  drau^t  of  the  fire.  Fig.  244  exhibits  the  vertical  see- 
tion,  and  Fig.  345  the  plan  of  the  sole  of  a  baking  oven.  The  sole,  a.  which 
ia  made  so  as  to  slope  upwards  towards  the  back  of  the  oven,  has  a  hreadtli 
of  31  metres,  and  a  depth  of  4  metres;  it  is  spanned  by  a  vault  05  metre 
high.  The  mouth  is  o-8  metre  wide,  e  «  «  are  the  flues  throng  which  the  gasea 
of  combustion  pass  into  the  chimney,  a,  the  draught  being  regulated  by  means  of 
the  damper,  u.  The  b'eneh,  x,  affords  standing-room  for  the  baker.  Under  the  oveB 
is  a  chamber  serving  as  a  store-room  for  the  coal.  The  space  ■  serves  aa  a  hot 
room  wherein  the  bread  is  placed  previous  to  being  put  into  the  oven  in  order  Aal 
tha  dough  may  rise.  Thoroughly  dried  wood  is  used  as  fuel :  it  is  placed  mcaa- 
wise  upon  the  hearth.    Coals  are  used  in  England  aa  fuel  for  this  puipoaa.    The 


BSEA.D. 


45S 


aven  hma  retched  the  required  tempemtore,  when  a  piece  of  wood  rubbed  on  the 
hearth  gives  off  sparks.  The  glowing  charcoal  ig  remoTed  throngh  the  month  of 
the  oven,  and  extingoiahed  in  the  lower  chamber.  Before  the  bread  is  put  into  the 
oven  the  sole  ie  carefully  cleaned  wilh  a  wet  swabber  fastened  to  a  pole,  and  ash  and 


cinders  having  been  removed  the  bread  is  put  into  the  oven  with  the  aid  of  an 
oven-shovel,  fixed  to  a  very  long  handle.  The  proper  temperature  of  the  oven  for 
baking  is  between  200°  and  225'  C.  Before  tlie  loaves  are  put  into  the  oven  Ihjy 
are  brushed  over  with  water  wherein  a  small  quantity  of  flour  baa  been  mixed,  in  order 
to  prevent  the  crust  of  the  bread  formed  by  the  first  action  of  the  beat  flying  off 
and  cracking  by  \be  rapid  expansion 

of  the  vapours  formed  by  the  heat  ^"*-  '*^- 

to  which  the  bread  ie  exposed.  The 
steam,  which  after  some  time  fills 
the  oven,  materially  assists  the 
baking  process,  and  veiy  greatiy 
aids  the  chemical  changes  which 
are  especially  apparent  in  the  crust, 
which  owes  its  glazed  appear- 
ance thereto.  The  time  necessary 
for  the  baking  varies  according  to 
the  size  of  the  loaves,  the  form, 
and  the  Idnd  of  bread.  The  nearer 
the  bread  approaches  to  a  globular 
form,  and  its  surface  therefore 
relatively  smallest  in  relation  to  ila  contents  so  much  the  longer  time  ii 
necessary  for  the  baking.  Black  bread  takes  a  longer  time  to  bake  than  white 
bread.  These  ovens  are,  however,  not  of  the  best  construction:  it  is  evident 
that  they  cannot  be  uniformly  heated  throughout,  while  they  cool  unequally  also,  and 
of  conne  most  so  at  the  front  part  by  the  rushing  in  of  cold  air.  After  every  batch 
of  bread  baked  it  therefore  becomes  necessary  to  fire  the  oven  again  for  a  short  time 


456  CHEMICAL    TECHNOLOGY. 

before  a  fresh  batch  of  bread  is  put  into  it ;  of  course  less  fuel  is  required  to  Im^ 
up  the  requisite  temperature  again  than  will  be  required  when  firing  is  commenced. 
When  the  baking  of  bread  is  carried  on  continuously  and  on  a  manufiftctarizig 
scale,  ovens  are  employed  in  which  the  baking-  and  the  fire-rooms  are  sepajraie  and 

distinct. 

subrtitutes  for  the  Permente.      Substitutes  foT  the  Ferments  in  the  '*  Bainng  "  of  Bread. — ^We 

have  seen  from  the  preceding  details  that  the  preparation  of  bread  is  essentially 

based  upon  the  fact  that  by  the  act  of  fermentation  the  gluten  of  the  flour  forms  a 

kind  of  cellular  tissue  by  which  tiie  escape  of  the  carbonic  acid  is  prevented,  and  thus 

the  bread  rendered  porous  and  spongy,  whereby  its  digestibility  is  increased.      This 

quality  of  the  bread  is  obtained  at  the  cost  of  a  portion  of  the  starch  of  the  flour, 

which  is  first  converted  into  starch-sugar,  and  tlien  by  means  of  fermentation  into 

alcohol  and  carbonic  acid  gas ;  to  the  expansion  of  the  latter  the  bread  owes  its 

spongy  texture.      Many  attempts  have  been  made  for  the  purpose  of  ejecting 

the  **  raising "  of  the  bread,   as  it  is  termed,  without  the  use  of  a  ferment,  \rr 

introducing   into    the    dough  some    gas-   or  vapour-producing    substance,    whick 

would  have  the  same  mechatiical  efifect  at  least  as  the  carbonic  acid  derived  from 

the  fermentation.    Although  the  problem  of  preparing  bread  of  good  quality  withont 

the  aid  of  fermentation  cannot  be  said  to  be  quite  settled,  many  proposals  have 

been  made  in  this  direction,  and  some  of  these  deserve  notice ;  we  therefore  quote 

the  most  important.    'SVhen  sesquicarbonate  of  ammonia  (the  so-called  sal  comu 

cervi  of  pharmacy)  is  added  in  small  quantity  to  the  dough,  it  will  cause  the  raising 

of  the  same,  partiy  because  some  acid  is  always  present  in  the  dough,  whereby 

the  salt  is  decomposed  and  carbonic  acid  set  free,  partly  because  by  the  heat  of 

the  oven  the  salt  is  volatilised,  and  by  assuming  the  state  of  vapour  causes  the 

expansion  and  consequent  sponginess   of  the  dough.     Liebig   recommends  tite 

addition  of  bicarbonate  of  soda  and  hydrochloric  acid  to  the  dough,  the  carbonic 

acid  being  evolved  according  to  the  formula  (NaHC03H-HCl=NaCl+HaO+COai 

with  the  formation  of  common  salt  wliich  remains  in  the  dough.    The  proportioos 

are  as  follows : — To  loo  kilos,  of  meal  for  making  black  bread  i  Idlo.  of  bicarbonaie 

of  soda  is  taken,  and  4*25  kilos,  of  hydrochloric  acid  of  1063  sp.  gr.  (=  9*5"*  B.  =  13 

per  cent  CIH),  yielding  175  to  2  kilos,  of  common  salt ;  the  quantity  of  water  to  be 

added  amounts  to  from  79  to  80  litres.    From  this  mixture  is  obtained  150  kilos.  o£ 

bread.    The  proportion  of  the  bicarbonate  of  soda  to  the  hydrochloric  acid  is  so 

arranged  that  5  grms.  of  the  former  are  fully  saturated  by  33  c.c.  of  the  latter,  leaving  in 

the  bread  a  faintly  aScid  reaction.    The  substance  known  and  sold  as  Horsford's  yeast 

powder,  also  recommended  by  Liebig,  is  preferable  and  more  readily  applied.    This 

powder  consists  of  two  separate  preparations,  viz.,  the  acid  powder  (add  phosj^bate 

of  lime  with  acid  phosphate  of  magnesia),  the  other  the  alkali  powder  (a  mixture  of 

500  grms.  of  bicarbonate  of  soda  and  443  grms.  of  cliloride  of  potassium).     To 

100  kilos,  of  flour,  2*6  kilos,  of  the  acid  powder,  and  1*6  Idlos.  of  the  alkali  powder 

are  added.    During  the  kneading  the  following  changes  occur:  the  bicarbonate  of 

soda  and  chloride  of  potassium  are  first  converted  into  chloride  of  sodium  and 

bicarbonate  of  potash,  the  latter  salt  being  in  its  turn  decomposed  by  the  mad 

phosphate,  whereby  carbonic  acid  is  set  free.    By  the  use  of  this  baking  powder  it 

is  possible  to  make  flour  into  bread  within  two  hour's  time,  while,  moreover,  100 

pounds  of  flour  yield  10  to  12  per  cent  more  bread  than  with  the  best  method  of 

baking  in  the  usual  way.    The  plan  of  incorporating  pore  carbonic  acid  gas  with 


I 


BREAD.  457 

the  dough  has  been  frequently  taken  up  and  abandoned  again ;  many  trials  have 
been  made  in  this  direction,  and  the  process  has  its  opponents  as  well  as  its 
defenders.  Of  later  years  the  late  Dr.  Dauglish  and  Mr.  Bousfield  have  taken  this 
subject  up,  and  after  having  obtained  a  patent  have  started  the  Aerated  Brecul 
Company.  This  process  as  carried  out  in  practice  is  best  described  by  an  extract 
firom  Dr.  Dauglish's  pamphlet,  using  his  own  words : — 

'*  I  first  prepare  the  water  which  is  to  be  used  in  forming  the  dough  by  placing  it 
in  a  strong  vessel  capable  of  bearing  a  high  pressure,  and  forcing  carbonic  acid  into 
it  to  the  extent  of  ten  or  twelve  atmospheres,  taking  advantage  of  the  well-known 
capacity  of  water  for  absorbing  carbonic  acid,  whatever  its  density,  in  quantities 
equal  to  its  own  bulk.    The  water  so  prepared  will  of  course  retain  the  carbonic  acid 
in  solution  so  long  as  it  is  retained  in  a  close  vessel  under  the  same  pressure.   I  there- 
fore place  the  flour  and  salt  of  which  the  dough  is  to  be  formed  also  in  a  close 
vessel  capable  of  bearing  a  high  pressure.    Within  this  vessel,  which  is  of  a 
spheroidal  form,  a  simply  constructed  kneading  apparatus  is  fixed,  working  from 
without  through  a  closely  packed  stuffing  box.    Into  this  vessel  I  force  an  equal 
pressure  to  that  which  is  maintained  on  the  aerated  water  vessel;    and  then,  by 
means  of  a  pipe  connecting  the  two  vessels,  I  draw  the  water  into  the  flour  and  set 
the  kneading  apparatus  to  work  at  the  same  time.    By  this  arrangement  the  water 
acts  simply  as  limpid  water  among  the  flour,  the  flour  and  water  are  mixed  and 
kneaded  together  into  paste,  and  to  such  an  extent  as  shall  give  it  the  necessary 
tenacity.    After  this  is  accomplished  the  pressure  is  released,  the  gas  escapes  from 
the  water,  and  in  doing  so  raises  the  dough  in  the  most  beautiful  and  expeditious 
manner.    It  will  be  quite  unnecessary  for  me  to  point  out  how  perfect  must  be  the 
mechanical  structure  that  results  from  this  method  of  raising  dough.    In  the  first 
place,  the  mixing  and  kneading  of  the  flour  and  water  together,  before  any  vesicular 
property  is  imparted  to  the  mass,  render  the  most  complete  incorporation  of  the  flour 
and  water  a  matter  of  very  easy  accomplishment ;  and  this  being  secured,  it  is  evident 
that  the  gas  which  forms  the   vesicle,  or  sponge,  when  it  is  released,  must  be 
dispersed  through  the  mass  in  a  manner  which  no  other  method — ^fermentation  not 
excepted — could  accomplish.    But  besides  the  advantages  of  kneading  the  dough 
before  the  vesicle  is  formed,  in  the  manner  above-mentioned,  there  is  another  and 
perhaps  a  more  important  one  from  what  it  is  likely  to  efiect  by  giving  scope  to  the 
introduction  of  new  materials  into  bread  making ;  and  that  is,  I  find  that  powerfiil 
machine  kneading  continued  for  several  minutes  has  the  efiect  of  imparting  to  the 
dough  tenacity  or  toughness.    In  Messrs.  Garr  and  Co.'s  machine,  at  Carlisle,  we 
have  kneaded  some  wheaten  dough  for  half-an-hour,  and  the  result  has  been  that 
the  dough  has  been  so  tough  that  it  resembled  bird-lime,  and  it  was  with  difficulty 
pulled  to  pieces  with  the  hand.    Other  materials,  such  as  rye,  barley,  &c.,  are 
afiected  in  the  same  manner ;  so  that  by  thus  kneading  I  am  able  to  impart  to 
dough,  made  &om  materials  which  otherwise  would  not  have  made  light  bread,  from 
their  wanting  that  quality  in  their  gluten  which  is  capable  of  holding  or  retaining* 
the  same  degree  of  hghtness  which  no  other  method  is  capable  of  efiecting.    And  I 
am  sanguine  of  being  able  to  make  firom  rye,  barley,  oatmeal,  and  other  wholesome 
and  nutritious  substances,  bread  as  light  and  sweet  as  the  finest  wheaten  bread. 
One  reason  why  my  process  makes  a  bread  so  diflerent  from  aU  other  processes 
where  fermentation  is  not  followed  is,  that  I  am  enabled  to  knead  the  bread  to  any 
extent  without  spoiling  its  vesicular  properly,  whilst  all  other  unfermented  breads 


^8  CHEMICAL  TECHNOLOGY. 

are  merely  mixed,  not  kneaded.  The  property  thus  imparted  to  my  bread  If 
kneading  renders  it  less  dependent  on  being  placed  immediately  in  the  oirea. 
It  certainly  cannot  gain  by  being  allowed  to  stand  after  the  dough  is  formed ;  but  it 
bears  well  the  necessary  standing  and  waiting  required  for  preparing  the  loaTes  lor 
baking. 

*'  There  is  one  point  which  requires  care  in  my  process,  and  that  is  the  bakiiig :  as 
the  dough  is  excessively  cold,  first,  because  cold  water  is  used  in  the  process,  and 
next  because  of  its  sudden  expansion  on  rising.  It  is  thus  placed  in  the  oven  some 
40°  F.  in  temperature  lower  than  the  ordinary  fermented  bread.  This,  together  willi 
its  slow  springing  until  it  reaches  the  boiling-point,  renders  it  essential  that  the  iap 
crust  shall  not  be  formed  until  the  very  last  moment.  Thus,  I  have  been  obliged  ta 
have  ovens  constructed  which  are  heated  through  the  bottom,  and  are  furnished 
with  means  of  regulating  the  heat  of  the  top,  so  that  the  bread  is  cooked  thiongk 
the  bottom;  and,  just  at  the  last,  the  top  heat  is  put  on  and  the  top  crust  formed. 

**  With  regard  to  the  gain  effected  by  saving  the  loss  of  fermentation,  I  may  state 
what  must  be  evident,  that  the  weight  of  the  dough  is  always  exactly  the  sum  of  the 
weight  of  flour,  water,  and  salt  put  into  the  mixing  vessel,  and  Ihat  in  all  oor 
experiments  at  Carlisle  we  invariably  made  118  loaves  from  the  same  weigbt  of 
flour  which  by  fermentation  made  only  105  and  106.  Our  advantage  in  gain  over 
fermentation  can  only  be  equal  to  the  loss  of  fermentation.  As  there  has  been 
considerable  difference  of  opinion  among  men  of  science  Mdth  respect  to  the  amount  of 
this  loss — some  stating  it  to  be  as  high  as  17)  per  cent  and  others  so  low  as  i  per 
cent — I  will  here  say  a  few  words  on  the  subject.  Those  who  have  stated  the  loss  to 
be  as  high  as  17^  per  cent  have,  in  support  of  their  position,  pointed  to  the 
yield  from  the  same  flour  of  bread  when  made  by  non-fermentation  compared 
that  made  by  fermentation.  Whilst  those  who  have  opposed  this  assertion,  and 
stated  the  loss  to  be  but  i  per  center  little  more,  have  declared  the  gain  in  wei^t  to 
be  simply  a  gain  of  extra  water,  and  have  based  their  calculations  of  loss  on  tiie 
destruction  of  material  caused  by  the  generation  of  the  necessary  quantity  of  carbonie 
acid  to  render  the  bread  light.  Starting,  then,  with  the  assumption  that  li^^t  breed 
contains  in  bulk  half  solid  matter  and  half  aeriform,  they  have  calculated  that  this 
quantity  of  aeriform  matter  is  obtained  by  a  destruction  of  but  i  per  cent  of  solid 
materiaL  In  this  calculation  the  loss  of  carbonic  acid,  by  its  escape  throng  the 
mass  of  dough  during  the  process  of  fermentation  and  manufEusture,  does  not  i^peer 
to  have  been  taken  into  account,  that  our  calculations  may  be  correct 

"  One  of  the  strongest  proofs  that  the  escape  of  gas  through  ordinary  soft  bread 
dough  is  very  large  arises  from  the  fact,  that  when  biscuit  dough,  in  which  there  is  a 
mixture  of  fatty  matter,  is  prepared  by  my  process,  about  half  the  quantity  of  gas  onfy 
is  needed  to  obtain  an  equal  amount  of  lightness  with  dough  that  is  made  of  floor 
and  water  only,  the  fatty  matter  acting  to  prevent  the  escape  of  gas  from  the  dou^. 
Other  matters  will  operate  in  a  similar  manner — boiled  flour,  for  instance,  added  in 
small  quantities.  But  the  assumption  that  light  bread  is  only  half  aeriform  matter 
is  altogether  erroneous.  Never  before  has  there  been  so  complete  a  method  of 
testing  what  proportion  the  aeriform  bears  to  the  solid  in  light  bread  as  that  which 
my  process  affords.  The  mixing  vessel  at  Messrs.  Oarr  and  Go's.  Works,  Carlisle, 
has  an  internal  capacity  of  10  bushels.  When  3i  bushels  of  flour  are  put  into  this 
vessel,  and  formed  into  spongy  bread  dough,  by  my  process  it  is  quite  fiilL  And 
yfhea  flour  is  mixed  with  water  into  paste,  the  paste  measures  rather  less  than  half 


1 


-.J 


BREAD.  459 

ttie  Bulk  of  the  original  diy  flour.  This  will,  therefore,  represent  about  x^  bnshels  of 
solid  matter  expanded  into  zo  bnehels  of  spongy  dough,  showing  in  the  dongh 
nearly  5  parts  aeriform  to  x  solid :  and  in  all  instances,  if  the  baking  of  this  dongh 
lias  not  been  accomplished  so  as  to  secore  the  loayes  to  spring  to  at  least  doable  their 
size  in  the  oven,  they  haye  always  come  ont  heavy  bread  when  compared  with  the 
ordinary  fermented  loaves.  This  gives  the  relative  proportion  of  aeriform  to  solid  in 
light  bread  at  least  as  10  to  i,  and  at  once  raises  the  loss  by  fermentation  from  i  to  zo 
per  cent,  withont  takrog  into  account  the  loss  of  gas  by  its  passage  through  the  znass 
of  dough. 

"  I  may  be  allowed  here  to  state,  what  will  be  evident  to  all,  that  the  absence 
of  everything  but  flour,  water,  and  salt,  must  render  it  absolutely  pure ;  that  its 
sweetness  cannot  be  equalled  except  by  bread  to  which  sweet  materials  are  super- 
sdded ;  that,  unlike  all  other  imfermented  bread,  it  makes  excellent  toast ;  and,  on 
sccount  of  its  high  absorbent  power,  it  makes  the  most  delicious  sop,  puddings,  &c.» 
snd  also  excellent  poultices.    Sop,  pudding,  and  poultice  made  from  this  bread,  how- 
ever, differ  somewhat  from  those  made  from  fermented  bread,  in  being  somewhat 
richer  or  more  glutinous.    This  arises  from  the  fact  of  the  gluten  not  having  been 
changed  or  rendered  soluble  in  the  manner  caused  by  fermentation ;  but  that  this  is  a 
good  quality  rather  than  a  bad  one  is  evident  from  the  fact,  that  the  richer  and  purer 
fermented  bread  is,  the  more  glutinous  are  the  sops,  &c.,  znade  fr^om  it ;  and  the 
poorer  and  more  adulterated  with  alum  it  is,  the  freer  the  sops,  &c.,  are  of 
this  quality." 

It  should  be  observed  that  the  alcohol  formed  during  the  fermentation  of  the 
bread  and  volatilised  by  the  heat  of  the  oven,  acts  along  with  the  carbonic  acid 
in  renderixig  the  dough  spongy ;  upon  this  action  of  the  alcohol  is  based  the  applica- 
tion of  rum  or  brandy,  which  in  small  quantities  are  added  to  pastiy  and  puddings 
made  with  flour,  suet,  eggs,  sugar,  butter,  ftc. 

TiddofBiMML  As  regards  the  quantity  of  bread  obtained  from  a  given  quantity 
of  flour,  it  varies  according  to  the  quality  of  the  latter;  zoo  kUos.  of  flour  usually 
yield  from  Z25  to  Z35  kilos,  of  bread. 

oonpodtioa  of  bkml  The  flour  from  various  kinds  of  grain  contain  in  its  ordinazy 
sir  dry  condition  from  Z2  to  z6  per  cent  of  water;  by  its  conversion  into  bread  the 
flour  takes  up  much  more  water,  zoo  pounds  of  fine  wheaten  flour  combine  with  50 
pounds  of  water,  and  give  Z50  pounds  of  bread.  The  composition  of  the  flour  and 
of  the  bread  is,  therefore,  as  follows : — 

Wheaten  Flour.      Wheaten  Bread. 

Dry  flour        84  84 

Water  originally  contained  in  the  flour  z6  z6 

Water  added  for  znaking  the  dough  ...  —  50 

zoo  Z50 

Accordizig  to  Heeren,  zoo  pounds  of  wheaten  flour  yield  at  least  z  25  to  z 26  pounds 
of  bread ;  zoo  pounds  of  zye  meal,  Z3Z  pounds  of  bread.  Fresh  wheaten  bread  con* 
tains  9  per  cent  of  soluble  starch  and  dextrin,  40  per  cent  of  unchanged  starch,  6*5 
per  cent  of  protein  compounds,  and  from  40  to  45  per  cent  of  water.  As  is  generally 
known  newly  baked  bread  possesses  a  peculiar  softness,  and  is  at  the  same  tune 
tongh ;  does  not  yield  crumbs  readily :  after  one  or  more  days'  keepizig,  the  bread 
loses  this  softness,  becomes  dry,  crumbles  readily,  and  is  then  called  stale  or  old 


4fio  CHEMICAL  TECHNOLOGY. 

bread;  it  is  usually  supposed  that  this  change  is  da6  to  a  loss  of  water;  but 
according  to  the  researches  of  Bonssinganlt,  stale  bread  contains  just  as  much  water 
as  fresh  bread;  the  alteration  is  solely  due  to  a  different  molecular  condition  of  the 
bread. 

nnmuitie.  Md^Adjiuntioa  When  the  flour  intended  for  the  preparation  of  bread  in  mon 
or  less  decayed,  the  gluten  it  contains  is  thereby  altered ;  ^e  carbonic  acid  evolved 
during  the  fermentation  of  the  bread  does  not  render  the  dough  spongy,  but  it 
becomes,  owing  to  the  altered  state  of  the  gluten,  a  more  or  less  slimy  mass,  which 
yields  a  tough  and  far  less  white-coloured  bread ;  in  order  to  counteract  this  defect, 
and  to  impart  a  good  appearance  to  the  bread  made  from  flour  which  has  been  damaged 
byldamp,  or  by  having  been  too  closely  confined  in  casks  and  thereby  heated, 
the  bakers  in  Belgium  and  Northern  France  (and  may  we  not  say  of  RngUwi^  too), 
add  to  the  dough  a  smaU  quantity  of  sulphate  of  copper,  ts&vv  to  wova  ;  the  base  of 
this  salt  combines  with  the  gluten,  forming  therewith  an  insoluble  compound,  tha 
rendering  the  dough  tough  and  white,  and  capable  of  taking  a  large  quantity  of 
water.  In  order  to  detect  the  sulphate  of  copper  in  the  bread,  a  portion  of  the  bread 
to  be  operated  upon  is  first  dried,  then  ignited,  and  tlie  copper  separated  from 
the  ash  by  gently  washing  away  the  lighter  particles,  leaving  the  metallic  copper 
in  the  shape  of  small  shining  spangles.  In  England  alum  is  very  generally  added 
to  bread.  In  Germany  the  addition  of  sulphate  of  copper  and  alimi  (0*5  per 
cent)  to  bread  is  prohibited  by  law,  but  in  some  parts  of  that  country  leaven  is 
kept  in  copper  vessels,  whereby  verdigris  is  formed,  the  appearance  of  which  is  by  lio 
means  disliked  by  the  bakers. 

The  Manufacture  of  Vimegab. 
vib^w.  Md  iu  oriffin.      The  fluid  known  in  common  life  as  vinegar  is  essentially  a  mix- 
ture of  acetic  acid  and  water.    Acetic  acid,  C2H4O2,  or  O2H3TT  r  O,  consists,  in  its 
highest  degree  of  concentration,  in  100  parts,  of — 

Carbonic  acid     •••...  24  40*0 

Hydrogen    4  67 

Oxygen        32  533 

60  XOO'O 

and  is  formed  by  the  oxidation  of  alcohol  as  well  as  by  the  dry  distillation  of  cella- 

lose. 

As  regards  the  first  mode  of  formation,  the  process  of  the  conversion  of  alcohol 
into  acetic  acid  may  be  represented  by  the  folloi^ving  formula : — 

I  mol.  alcohol  CaHeO  =46  )     .^^  (  i  mol.  acetic  add  CaH40«  =  6o 
«    »r    oxygen         20=32)'^       li    „    water  HtO  =  i8 


78  78 

Accordingly  100  parts  of  alcohol  should  give  129*5  P<^^  ^^  acetic  acid  of  the  hi^iest 
degree  of  concentration.  The  process  of  conversion  is,  however,  by  no  means 
80  simple  as  just  mentioned,  because  the  alcohol  is  not  at  once  converted  into  acelie 
add,  but  first  converted  into  a  body  which  contains  less  oxygen  than  the  acetic  acid, 
viz.,  aldehyde,  CaH40.  The  conversion  of  the  alcohol  into  acetic  add  may  be 
dated  in  the  following  manner : — 


VINEOAR.  461 


Alcohol  CaHeO     =  46 

^  -  ^     ^  „  (Ha  becomes,  by  tiie  aid  of  0  taken  up 

Subtract  Ha=   a  |      from  the  air.  oxidised  to  HaO. 


iemainder    )   CaH,0  =  44 
Aldehyde    )  * 

Add  0  =  16      from  the  air. 


Result — 


=c^d  }  C«H*««=^ 


100  kilos,  of  alcohol  therefore  need  300  kilos.  ( =  2322  hectolitres)  of  air,  con* 
taining  69  kilos,  of  oxygen,  for  tlie  conversion  of  Uie  alcohol  into  acetic  acid.  It  is, 
however,  evident,  that  in  practice  this  quantity  of  air  is  insufficient,  and  only  that 
portion  of  the  oxygen  which  is  in  the  state  of  ozone  is  capable  of  performing 
the  duty  of  aeetification.  Alcoholic  liquids,  in  order  to  Ix^come  converted  into 
vinegar,  require  the  presence  of  a  peculiar  fungus  (cryptogamic  plant),  known  as 
Mycoderma  aoeti,  which  appears  to  act  as  the  carrier  of  the  oxygen  of  the  air, 
wliich  is  also  by  it  rendered  active  and  given  up  to  the  alcohol. 

The  origin  of  vinegar  or  acetic  acid  as  a  product  of  the  dry  distillation  of  cellu- 
lose cannot  be  elucidated  by  a  simple  formula,  because  there  are  formed  in 
addition  to  acetic  acid  a  large  number  of  other  compounds,  among  which  are  gaseous 
and  fluid  hydrocarbons,  wood  spirit,  aceton,  creosote,  oxyphenic  acid,  tar,  &c., 
the  relative  quantity  of  which  depends  not  only  upon  the  temperature  at 
which  the  distillation  took  place,  but  also  upon  the  shape  of  the  retorts  used, 
the  quantity  of  hygroBCOpic  water  contained  in  the  wood,  &c. 

a.  Preparation  of  Vinegar  from  Alcoholic  Fluids, . 

TiiMKtffiomAioohoL  When  alcohol  is  left  exposed  to  air  or  to  pure  oxygen  it  is  not 
converted  into  acetic  acid.  Nevertheless  the  conversion  is  due  to  the  alcohol 
becoming  oxidised ;  therefore  it  is  evident.the  alcohol  must  be  placed  under  such  con- 
ditions as  are  most  favourable  to  the  formation  of  vinegar.  In  this,  as  in  many  other 
chemico-technical  processes,  practical  experience  is  the  best  teacher.  The  most 
important  points  are,  of  course,  the  preparation  of  vinegar  in  the  shortest  time  with 
the  least  expenditure  of  alcohol.  The  conditions  most  favourable  to  the  formation  of 
vinegar  on  the  large  scale  are  the  following  :-^ 

1.  The  alcoholic  fluid — ^prepared  from  grape  wine  or  fruit  wine,  fermented  malt 
infusion,  beer,  and  brandy — should  be  sufficiently  diluted ;  it  should  contain  not  more 
than  10  per  cent  of  alcohol.  Experience  has  proved  that  fluids  prepared  by 
the  direct  application  of  alcoholic  fermentation,  viz.  wine,  beer,  &c.,  are  more 
readily  converted  into  vinegar  than  mixtures  of  brandy  or  alcohol  and  water.  But 
too  great  a  dilution  should  be  avoided  ;  for  although  a  liquid  containing  3  per  cent  or 
less  alcohol  can  be  converted  into  vinegar,  the  aeetification  proceeds  yerj  slowly  in 
so  dilute  liquids. 

2.  A  suitable  temperature — ^not  above  36**  C,  not  below  10**  to  12^  C.  At  a  tempe- 
rature of  7**  G.  and  less  the  formation  of  vinegar  no  longer  takes  place,  a  fact 
usually  overlooked  when  the  advantages,  of  keeping  beer  and  other  fermented 
liquids  in  ice  pits  or  very  cool  cellar^  are  enumerated.  Above  40^  to  60**  the  acetifi* 
cation  proceeds  very  rapidly,  but  there  is  a  loss  of  alcohol  and  vinegar  by  evapo- 
ration. 

3.  A  plentiful  supply  of  air  or  oxygen  to  the  alcoholic  fluid  and  an  intimate  con- 
tact between  the  two.    Small  quantities  of  alcoholic  fluid  with  an  extended  surface 


46a  CHEmCAL  TECHNOLOGY, 

are  more  readilj  converted  into  vinegar  than  large  bulks  of  fluid,  because  the  ktam 
present  a  larger  number  of  points  of  contact. 

4.  The  presence  of  substances  which  conduce  to  the  formation  of  vinegar;  thej 
are  as  regards  their  action  similar  to  the  ferments,  and  are  therefore  called  acetic  add 
or  sour  producing  ferments  ;  but  the  acetification  is  not  a  physiological  process,  as  ii 
vinous  fermentation,  but  simplj  one  of  oxidation.  The  best  ferment  is  vinegur.  and 
all  substances  impregnated  with  it,  such  as  for  instance  the  so-called  vinegar  plifit, 
the  Mycoderma  aceti ;  it  was  formerly  thought  that  the  vinegar  mycoderms  stood  to 
alcohol  and  vinegar  in  the  same  relation  as  yeast  stands  to  sugar  and  alcohol,  but  tfais 
opinion  is  correct  only  so  fiEu:  as  the  addition  of  Mycoderma  aceti  to  an  alooholie 
fluid,  as  proved  by  Pasteur's  experiments  (1862),  is  alike  in  the  action  of  small  quan- 
tities of  vinegar  and  other  acetification -inducing  substances  upon  wooden  vats  aid 
chips  of  wood  thoroughly  impregnated  with  vinegar ;  many  of  these  substances  eos- 
tain  particles  which  are  undergoing  a  process  of  oxidation  (molecule  en  momeemaiii, 
and  by  coming  into  contact  with  alcohol  they  draw  that  fluid  into  a  course  of  oxidotioB 
also.  Pure  acetic  add  is  therefore  incapable  of  inducing  acetification,  bat  vinegar,  <s 
the  contrary,  is  capable  of  doing  so  because  it  always  contains  smaller  or  larger  qoai* 
titles  of  the  protein  compounds  alluded  to;  but  unless  these  are  in  a  peenliir 
state  of  activity  they  are  useless ;  this  is  shown  by  platinum  black  and  BpoDff 
platinum,  both  of  which  are  capable  of  converting  alcohol  immediately  into  seelK 
acid.  We  may  therefore  conclude  that,  by  the  presence  of  Mycoderma  aeeti  as  «d 
as  of  spongy  platinum,  the  oxygen  of  the  air  is  rendered  active— ozonised-— and  that 
only  ozonised  oxygen  is  capable  of  converting  alcohol  into  vinegar.  Acetic  add  is, 
therefore,  an  oxidation  product,  not  one  of  the  Mycoderma.  A  more  accurate  inTei- 
tigation  of  the  behaviour  of  peroxide  of  hydrogen  and  other  ozone-containing  « 
producing  materials  with  mixtures  of  alcohol  and  water,  will  no  doubt  lead  to  a 
better  knowledge  of  the  theory  of  acetification,  and  may  lead  also  to  a  more  xatioBal 
and  improved  mode  of  vinegar  making. 

FhMMBMiiaof  VinigarFonuitioii.  AcetificatLou  exhibits  phenomena  which  are  impcvtani 
for  observation  because  they  indicate  the  progress  of  the  conversion  of  the  tkw 
into  acetic  acid ;  these  phenomena  are  partly  of  a  chemical,  partly  of  a  pkyakii 
kind.  In  proportion  as  the  formation  of  vinegar  advances,  the  alcoholic  fluid  1m> 
its  peculiar  flavour  and  odour,  and  acquires  the  refreshing  sour  taste  of  vinegar.  7o 
the  physical  phenomena  belong : — i.  An  increase  in  the  specific  gravis  of  the  faid; 
and  (s)  an  increase  of  the  temperature.  The  increase  of  temperature  is  dnetotht 
conversion  of  the  oxygen  from  a  gas  to  a  fluid.  The  more  active  tiie  abeozpta  of 
oxygen  the  higher  the  temperature. 

Tbj  oMtf  Me^  of  Accordiug  to  the  substance  fix  m  which  vinegar  is  prepared  ft» 
following  kinds  are  distinguished: — i.  Wine  vinegar,  prepared  from  wise,  n^ 
containing  in  addition  to  acetic  acid  many  of  the  other  constituents  of  wine,  nMB^f 
tartaric  add,  succinic  add,  and  certain  kinds  of  ethers,  the  latter  imparting  to  wiai 
vinegar  its  pecidiarly  agreeable  flavour  and  odour.  2.  Brandy  vinegtr,  ^f^ 
vinegar,  or  artifidal  wine  vinegar,  generally  only  a  mixture  of  acetic  acid  and  watff 
with  a  small  quantity  of  acetic  ether.  3.  Fruit  vinegar,  prepared  from  cider  aad 
perry  and  containing  acetic  and  malic  adds.  4.  Beer,  malt,  or  grain  tib^' 
prepared  firom  non-hopped  beer  wort,  and  containing,  besides  acetic  add,  1^ 
extractive  matters,  such  as,  for  instance,  dextrin,  nitrogenoms  oonstitaenta  tf^ 
phosphates.    5.  Vinegar  from  the  sugar  beet-root    The  roots  an  oonvertsd  v^ 


I 


riNEOAB.  463 

a  palp  and  then  pressed ;  the  joice  is  next  diluted  with  water  and  afterwards  boiled. 
When  sufficiently  cooled,  yeast  is  added  and  alcoholic  fermentation  set  up;  this 
having  been  finished  the  alcohol  contained  in  the  liquid  is  converted  into  vinegar. 
The  vessel  in  which  the  acetification  takes  place  is  connected  with  a  blowing  fan ;  by 
the  aid  of  a  plentiful  supply  of  air  and  the  keeping  lip  of  a  uniform  temperature  the 
Alcoholic  liquid  to  which  some  vinegar  has  been  added  is  rapidly  converted  into 
acetic  acid.  6.  Vinegar  prepared  from  the  so-called  wood  vinegar  or  acetic  acid 
obtained  by  the  dry  distillation  of  wood. 

As  regards  the  so-called  old  method  of  vinegar  making  it  is  without  doubt  an 
imitation  of  the  spontaneous  souring  of  beer,  wine,  and  fermented  liquors  generally 
and  on  conditions  which  are  conducive  to  the  improvement  of  the  product^ 
6uch  conditions  are — ^a  suitable  temperature,  intimate  contact  of  the  souring 
liquor  with  air>  and  a  so-called  acetification-inducing  ferment.  This  method  is 
very  generally  employed  for  making  wine  vinegar,  French  vinegar  as  it  is  termed  in 
£ngland,  but  may  of  coarse  be  used  for  malt  or  fruit  vinegar  making  as  well. 
Generally  a  "souring'*  vessel  or  "  mother"  vessel  made  of  oak  wood  is  employed; 
this  vat  is  first,  when  newly  made,  thoroughly  scalded  with  boiling  hot  water,  and 
when  thereby  the  extractive  matter  of  the  wood  is  exhausted  the  vessel  is  filled  with 
boiling  hot  vinegar ;  when  the  wood  is  soaked  with  vinegar  there  is  poured  into  the 
•vessel  I  hectolitre  of  wine,  and  after  eight  days  again  10  litres  of  wine  are  added, 
and  this  operation  continued  weekly  until  the  vessel  is  filled  for  two-thirds  of  its 
cubic  capacity.  About  fourteen  days  after  the  last  addition  of  the  wine  the  whole  of 
the  contents  will  have  become  converted  into  vinegar.  Half  this  quantity  is  with- 
drawn from  the  souring  vessel  and  carried  to  the  store :  to  the  remainder  more  wine 
is  added,  and  the  preparation  of  vinegar  proceeded  with  uninterruptedly  by  the  opera- 
tion described.  A  souring  vessel  may  continue  to  serve  its  purpose  for  six  years, 
and  often  longer,  but  generally  at  the  end  of  this  time  there  is  collected  in  the  vessel 
so  large  a  quantity  of  yeast  sediment,  argol,  stone,  and  other  matter  as  to 
render  the  thorough  cleansing  of  the  vessel  necessaiy ;  after  this  operation  it  is 
again  fit  for  further  use.  Although  it  might  appear  that  in  this  process  of 
acetification  there  is  no  great  contact  of  air,  and  the  fluid  is  apparently  quite  at  rest, 
there  is  a  constant  change  of  the  particles  of  the  surface  of  the  fluid,  owing  to  the 
&ct  that  every  drop  of  vinegar  formed  sinks  to  the  bottom  of  the  vessel,  or  at  least 
below  the  surfiace,  owing  to  its  increased  specific  gravity;  while  as  regards  the  air, 
that  portion  of  it  from  which  the  oxygen  has  been  absorbed  by  becoming  specifically 
lighter  (eg  sp.  gr.)  has  a  tendency  to  rise  upwards,  and  to  be  replaced  by  heavier 
air  (1*0  sp.  gr.) ;  thus  a  constant  circulation  of  air  is  provided. 

4)iikk  TiiMgw  icaUdc.  The  so-caUed  quick  vinegar  process,  founded  on  an  older 
method  of  vinegar  preparation  suggested  by  Boerhaave  in  1720,  was  first  introduced 
by  Schiitzenbach  in  1823.  The  chief  principle  of  this  method  consists  in  bringing 
the  fluid,  generally  brandy,  to  be  converted  into  vinegar  into  ultimate  contact  with 
the  atmosphere  at  the  requisite  temperature,  or,  in  other  words,  the  oxidation  of  the 
alcohol  to  acetic  add  is  efiected  in  the  shortest  time  and  with  the  least  possible  loss. 
The  intimate  contact  of  the  fluid  with  the  air  is  efiected  by: — i.  Increasing  the 
quantity  of  air  admitted  by  means  of  a  continual  current  of  air  being  made  to  meet 
tiie  drops  of  the  fluid  intended  to  be  converted  into  vinegar  in  opposite  direction  to 
that  in  which  these  drops  fidl  downwards.  2.  3y  causing  the  liquid  to  be  operated 
upon  to  trickle  down  drop  by  drop.    A  peculiarly  constructed  vessel  is  required  for 


464  CHEMICAL  TECHKOLOOr. 

this  operation ;  ftcoording  to  tlie  etrengtli  of  vinegar  deHired  to  be  made  two  to 
of  these  vessels  are  eniployefl.  tlieae  conBtitiiting  a  group  or  buttery  as  it 
A  sectional  view  of  sncli  a.  vessel  is  exhibileil  iii  Fig.  346  ;  it  ia  mode  of  stout  oakcB 
btaves,  the  vat  being  from   2  to  4 
^o*  '46-  metres  in  heiglit,  and  from  i  to  1-3  in 

nidth :  at  a  heiglit  of  from  20  to  30 
centimetres  front  tlie  bottom  of  thm 
vessel  are  bored  at  equal  <tistance 
from  each  otlier  six  holes  ^ — air 
holes — of  about  3  centimetres  in 
diameter,  m  cut  that  tlte  inaa 
month  of  the  bole  is  situated  &  little 
deeper  than  the  ontcr,  that  is  to 
Mj,  the  holes  are  bored  towards 
the  bottom  in  a  slightly  sIopinK 
direction.  About  one-third  of  ■ 
metro  above  the  real  lower  bottom 
a  false  bottom  is  placed,  simtl&r  in 
construction  to  a  sieve,  and  mt  m 
height  of  a  centimetre  above  the 
air-holes;  upon  the  false  bottom  i» 
a  layer  of  beech -wood  shavings 
extending  upwards  to  about  from  15 
to  20  centimetres  below  the  upper  edge  of  the  vat.  The  false  bottom  is  sometimes 
constructed  of  lathe  of  wood,  forming  a  Und  of  gridiron-like  network.  Before  Iheir 
application  the  wood  sliaviugs  are  thoroughly  washed  with  hot  water  and  nest 
dried.  The  tub  is  tlien  nearly  filled  with  tiie  dry  wood  ahaviuga,  which  at«  next 
"  soured."  For  this  purpose  warm  vinegar  is  ponied  over  tliem,  and  allowed  to 
remain  in  contact  with  the  woo<l  for  twenty-four  hours  so  as  to  cause  the  acetic 
acid  to  soak  into  the  wood.  At  from  18  to  24  centimetrus  below  the  itpper  edge 
.of  the  vat  is  fixed  a  perforated  wooden  disc,  the  holes  of  which  are  as  large 
as  a  goose-quill,  and  are  bored  from  3  to  5  centimetres  apart  from  each  other. 
In  order  that  the  lii^uid  intended  to  be  converted  into  acetic  acid  may  trickle  alowly, 
and  in  fine  spray,  as  it  were,  over  the  wood  shavings,  or  thin  chips  of  wood, 
throngh  the  holes,  strings  of  twine  or  loosely  spun  cotton  yam  are  passed  so 
as  to  penetrate  downwards  for  a  length  of  3  centimetres,  while  at  the  top  a  knot 
is  tied  which  prevents  the  strings  slipping  tlirough  tlie  holes;  by  the  action  of 
the  liquid,  dilate  spirits  of  wine  usually,  which  is  poured  into  tlie  vessel,  the 
twine  becomes  more  or  less  swollen,  and  thereby  obstmcta  the  passage  of  the 
fluid  so  as  to  divide  it  into  constantly  trickling  drops.  The  sieve  bottom  is  fitted 
with  from  fire  to  eight  larger  lioles,  each  about  3  to  6  centimi'tres  wide,  which  by 
means  of  glass  tubes,  each  of  from  10  to  15  centimetres  in  length,  inserted  and 
firmly  fastened  tlierein  act  as  druuglit  tubes,  so  placed  that  110  liquid  can  pass 
through  them.  The  vat  is  covered  at  tlie  top  witji  a  tightly -tilting  wiMxlen  lid, 
in  the  centre  of  which  a  circular  hole  is  cut,  which  serves  as  well  for  the 
purpose  of  pouring  tlie  liquid  into  the  vessel  as  for  the  outlet  of  the  air  which 
enters  the  vessel  from  below.    In  consequence  of  the  absorptiou  of  the  oxygen  so 


niTEGAR.  46s 

mach  heat  is  generated  in  the  interior  of  the  vessel  that  the  air  BtreainB  Btronglf 
upirarda,  cansiDg  freah  air  1«  enter  bj  the  lower  air-holes. 

After  the  Tittegor  tub  has  been  soured  the  ftoid '  to  be  converted  into  vinegar — 
geneniUy  brandy,  more  rarely  malt  liquors  or  wine — is  poured  in ;  the  fluid  flowing 
off  from  the  first  vessel  is  poured  into  the  second,  and  if  the  origiDsl  liquid  did 
not  contain  more  than  from  3  to  4  por  cent  of  alcohol  the  fluid  which  runs  off  from 
the  second  vessel  will  be  completely  converted  into  good  vinegar.  The  vinegar 
collects  between  the  true  and  false  bottoms.  As  will  be  seen  from  the  woodcut  the 
vinegar  cannot  flow  out  nntil  its  level  is  equal  to  UiSit  of  the  mouth  of  the  glass 
tube.  In  consequence  of  this  arrangement  a  layer  of  about  16  to  20  centimetres 
in  depth  of  warm  vinegar  assists  in  die  ocetifjcation  by  the  evolution  of  acid 
Tsponre  wbicli  ascend  into  the  fluid  above.  Tlie  tube  mnst  dip  into  the  lower  part 
of  the  fluid  in  the  interior  of  the  tub,  as  it  is  there  that  the  specifically  heavier 
vinegar  collects.  The  arrangement  will  be  readily  understood  from  Fig.  247; 
e  p  iaOie  perforated  bottom,  just  below  which  is  situated  the  wooden  tap,  h.  fsstened 
to  the  bent  glass  tube,  m  m,  the  free  open  end  of  which  touches  the  bottom  of 
the  tub. 

Recently  (1868)  Singer's  vinegar  generator  has  been  introduced.  It  consists  of  a 
number  of  ressels,  one  placed  above  the  olher,  and  so  connected  together  by  wooden 


ttibes  that  the  liquid  intended  to  he  converted  into  vinegar  trickles  drop  by  drop 
&om  the  one  Teasel  into  the  other  ;  in  each  tube  is  cut  a  longitudinal  slit,  through 
which  air  freely  circulates ;  the  apparatus  is  placed  in  a  suitably  constructed  shed, 
wherein  a  convenient  temperature  is  kept  up  and  from  which  draught  is  excluded. 
By  the  use  of  this  apparatus  the  loss  of  alcohol  experienced  in  tlie  nse  of  the 
vats  above  mentioned  is  prevented.  Singer's  apparatus  is  fully  described  in  the 
"  Jahresbericht  der  Chem.  Teclmologie,"  1868,  p.  580. 

The  composition  of  the  fluid  to  he  ocetifled  varies  very  much ;  one  of  the  mixtures 
very  generally  used  is  made  up  of  20  htres  of  brandy  of  50  per  cent  Tralles,  40 
litres  of  vinegar,  and  120  litres  of  n'ater,  to  which  is  first  added  a  hquid,  made  by 
Booking  a  mixture  of  bran  and  rye  meal  in  water  in  order  to  promote  the  formation 
of  the  vinegar  fungus  (Mycoderma  aeeti).  The  room  in  which  the  vats  are  placed 
should  be  heated  to  20°  to  24° ;  the  temperature  in  the  vats  rises  to  36'  Bid  more, 
consequently  the  alcohol,  aldehyde,  and  acetic  acid  ore  volatilised,  and  this  loss 
may  amount  to  about  one-tenlh ;  taking  this  loss  into  account  we  may  assume 


466  CHEMICAL  TECHNOLOGY, 

that  I  hectolitre  of  brandy  at  50  per  cent  Tralles  (=  42  per  cent  according  to  \r eight) 
yields  by  weight — 

13  o  hectolitres  of  vinegar  of  3  per  cent  acetic  acid  contents. 


99 

4 

)f                                        M 

79 

5 

"                                        »» 

6*6 

6 

»l                                        1» 

5-6 

7 

»l                                        »» 

49 

8 

»f                                        «> 

4*4 

9 

»>                                        »> 

39 

10 

f>                                        f> 

When  required  for  transport  it  is,  of  course,  most  advantageous  to  prepare 
strong  vinegar,  wliich  at  the  place  where  it  is  to  be  consumed  can  be  diluted  with 
the  reqtiisite  quantity  of  water. 

Vinegar  from  the  Bngar-Beet.  Vinegar  from  the  sugar-beet  is  prepared  from  the  expreeeed 
juice,  having  a  sp.  gr.  of  1*035  ^^  i*045>  diluted  with  water  to  1*025  ^P*  £>''•*  fermented 
with  yeast,  the  fluid  being  next  mixed  with  an  equal  volume  of  prepared  vinegar.  This 
mixture  being  well  exposed  to  the  influence  of  the  oxygen  of  the  atmosphere,  acetifieation 
soon  sets  in. 

^^"*ifySd5iSl  a26°' "'^  Pasteur,  who  refers  acetification,  as  Dr.  Wagner  thinks 
erroneously,  to  a  physiological  process,  has  in  1862  described  a  new  method  of  pre- 
paring vinegar  with  the  help  of  the  vinegar  fungus,  the  Mycodenna  aeeti.  This 
fungus  is  first  propagated  in  a  fluid,  consisting  of  water  and  2  per  cent  of  alcohol 
with  I  per  cent  of  vinegar  and  a  small  quantity  of  phosphate  of  potash  lime  and 
magnesia.  The  small  plant  soon  spreads  itself  over  the  entire  surface  of  the  fluid* 
without  leaving  the  smallest  space  uncovered.  At  the  same  time  the  alcohol  is  aceti- 
fied. As  soon  as  half  of  the  alcohol  is  converted  into  vinegar,  small  quantities  of 
wine  or  alcohol  mixed  wuth  beer  are  added  daily.  When  the  acetification  becomes 
weaker,  the  complete  conversion  of  the  free  alcohol  still  present  in  the  fluid  is  allowed 
to  take  place.  The  vinegar  is  then  drawn  off  and  the  plant  again  employed  in 
the  same  apparatus.  Vinegar  prepared  by  this  method  possesses  much  of  the  aroma 
characteristic  of  wine  vinegar.  An  essential  condition  to  the  rapid  formation  of 
vinegar  by  this  method  is  a  strong  development  of  the  plant.  A  vessel  with  i  aqoare 
metre  of  surface,  and  capable  of  containing  50  to  100  litres  of  fluid,  yields  daily 
5  to  6  litres  of  vinegar.  Tlie  vessels  are  circular  or  rectangular  wooden  tanks, 
with  but  a  slight  depth,  and  covered  with  lids.  At  the  ends  are  bored  two 
small  openings  for  the  entrance  of  the  air.  Two  tubes  of  gutta-percha,  pierced 
laterally  with  small  holes,  are  cai*ried  down  to  the  bottom  of  the  tank  and  used 
to  pour  alcohol  into  the  tank  without  opening  the  lid.  The  tank  which 
Pasteur  employed  had  a  surface  of  i  square  metre  and  a  depth  of  20  centims. 
He  found  phosphates  and  ammonia  necessary  for  the  growth  of  the  plant  When 
wine  or  malt  liquor,  &c.,  is  employed,  these  substances  are  present  therein  in  suffi- 
cient quantity ;  but  when  only  alcohol  is  used,  sulphate  of  ammonia,  phosphate  of 
potash  and  magnesia  are  added  in  such  quantity  that  the  fluid  contains  ieii«th 
of  this  saline  mixture,  to  which  also  some  vinegcu:  is  added.  It  has  been  long 
known  that  the  addition  of  bread,  flour,  malt,  and  raisins  to  alcoholic  fluids  about  to 
be  acetified  greatly  promotes  the  formation  of  vinegar,  as  these  substances  contain 
the  requisite  orgauic  and  inorganic  food  suited  for  the  propagation  of  the  vinegar 
fungus. 


VINEGAR.  4^7 

"ot^iuS?™  Bi5k!'  Dobweiner  was  the  first  who  pointed  out  that,  with  the  i^  of 
platiaiun  black,  alcoholic  vaponrs  could  be  acetified  in  a  Terf  short  time  ;  and  to  this 
process  the  following  apparatus  is  especiallj  adapted.  Fig.  248  shows  a  small  glass 
house,  in  the  interior  of  which  are  seen  a  number  of  coinpartments.  The  shelves 
forming  these  compartments  sapport  a  number  of  porcelain  capsules.  The  alcohol  to 
be  acetified  is  poured  into  these  capsules,  in  each  of  which  is  placed  a  tripod,  alsa  of 
porcelain,  supporting  a  watch-glass  containing  platdnom  black  or  spongy  platinum. 
In  the  roof  and  at  the  bottom  of  the  apparatus  are  Tentilators,  so  constructed  as  to 


Fm.  34S. 


admit  of  regulating  access  of  air. 
B;  means  of  a  small  steam  pipe 
the  inferior  of  the  house  is  heated 
to  33°.  By  this  means  the  alcohol 
is  gentlj  evaporated,  and  coming 
into  contact  with  the  platimun  black 
or  sponge,  is  acetified.  So  long  as 
the  ventilation  is  maintained,  the 
platinum  black  retains  its  property 
of  oxidising  the  alcohol.  With  an 
apparatus  of  40  cubic  metres  capa- 
city and  with  17  kilos,  of  platuium 
black,  130  htres  of  alcohol  can  daily 
be  converted  into  pure  vinegar. 
If  it  be  desired  to  prepare  the 
vin^ar  without  any  loss  of  alcohol, 
it  becomes  necessary  to  pass  the 
outgoing  air  through  a  condenser  in 
order  to  collect  the  vapoufs  of  alcohol  and  aceUc  acid  which  otherwise  would  be 
carried  off. 

KMnfViiHcu.  The  value  of  a  vinegar  is  dependent  upon  its  flavour  and  upon 
its  strength,  or  upon  the  quantity  of  acetic  acid  it  contains.  According  to  its  con- 
taining more  or  less  acetic  acid  the  vinegar  tastes  more  or  less  sour.  The  colour 
varies  with  the  fluid  from  which  the  vinegar  has  been  prepared ;  wine  vinegar  is 
of  a  yellow  or  red-yellow  colour,  fruit  vinegar  exhibits  a  golden  colour,  brandy 
vinegar  is  colourless ;  but  as  a  rule  the  latter  is  colonied  with  caramel  in  imitation 
of  wine  vinegar.  Freshly  made  vinegar  contains  besides  small  quantities  of  uncon- 
verted alcohol,  some  aldehyde,  which  always  occurs  largely  in  vinegar  not  properly 
prepared.  Kecently  it  has  become  customary  to  add  a  small  quantity  of  glycerine 
to  the  prepared  vinegar. 

The  quantity  of  acetic  add  contained  in  a  vinegar  depends  upon  the  alcohoUc  con- 
tents of  the  fluid  to  be  acetified,  and  also  upon  the  more  or  less  perfect  conversion  of 
the  alcohol  into  acetic  acid.  Malt  vinegar  contains  from  z  to  5  per  cent,  brandy 
vinegar  from  3  to  6  per  cent,  wine  vinegar  from  6  to  8  per  cent,  of  acetic  acid.  The 
specific  gravi^  of  various  kinds  of  vinegars  differs  from  I'oio  to  1030 1  the  mors 
alcohol  a  vinegar  contains  the  lighter  is  it,  the  more  extractive  matter  the 
heavier.  The  densities  of  mixtures  of  acetic  acid  (CjH^Oil  and  water  are,  at 
15°  C,  according  to  Oudemans,  the  following:— 


468 


CHEMICAL  TECHNOLOGY. 


Per- 
centage. Dens. 


o 

I 

2 

3 

5 
6 

7 
8 

9 

10 

II 

12 

13 

14 

15 
i6 

^7 
i8 

19 

20 
21 
22 

23 

24 

25 


09992 
I  0007 

I'0O22 

1*0037 

10052 

10067 

I  0083 

I  0098 

IOII3 

1*0127 

IOI42 

1*0157 

IOI7I 

IO185 

I '0200 

I'02I4 

I  0228 

1'0242 

1*0256 

I  0270 

1*0284 

I  0298 

IO3II 

10324 

10337 
10350 


Diff. 


+ 


6 

5 
5 
4 
5 
5 
4 
4 
5 
4 
4 
4 
4 
4 
4 
4 
3 
3 
3 
3 


Per- 
centage. 

26 
27 
28 
29 

30 
31 
32 
33 
34 
35 
36 

37 
38 

39 
40 

41 
42 

43 

44 

45 
46 

47 
48 

49 
50 
51 


Dens. 

10363 

10375 

10388 

1*0400 

1*0412 

1*0424 

1*0436 

1*0447 

10459 

1*0470 

1*0481 

1*0492 

1*0502 

1*0513 

1*0523 

10533 

10543 

10552 

1*0562 

10571 

1*0580 

1*0589 

1*0598 

1*0607 

1*0615 

1*0623 


Per- 
Biff.  oentage.  Dens. 


12 
13 

12 
12 
12 
12 
II 
12 
II 
II 
II 
10 
II 
10 
10 
10 

9 
10 

9 
9 
9 
9 

9 

8 

8 
8 


52 
53 
54 
55 
56 

57 
58 

59 
60 

61 

62 

63 
64 

65 
66 

67 

68 

69 

70 

71 
72 

73 

74 

75 
76 

77 


0631 

•0638 

•0646 

•0653 

•0660 

0666 

•0673 

•0679 

0685 

•0691 

•0697 

0702 

•0707 

•0712 

0717 

*072I 

•0725 
•0729 

•0733 
•0737 

0740 

•0742 

•0744 
0746 

•0747 

•0748 


Per- 
Diff.  centage. 

78 


7 

8 

7 

7 
6 

7 
6 

6 

6 

6 

5 
5 
5 
5 
4 
4 
4 
4 
4 

3 

2 

2 

2 
I 
I 
O 


79 
80 

81 

82 

83 

84 

85 
86 

87 
88 

89 
90 

91 
92 

93 

94 

95 
96 

97 
98 

99 
100 


Dens. 

1*0748 

1*0748 

1-0748 

10747 

1*0746 

X0744 

i*074Z 

10739 

10*736 

I  073 1 

1*0726 

1*0720 

1*0713 

10705 

1*0696 

i*o686 

1*0674 

i'o66o 

1*0644 

1*0625 

1*0604 

1*0580 

10553 


o 
o 

I 
z 

2 

5 
3 

5 

5 
6 

7 
8 

9 

JO 

14 
16 

21 

24 
27 


Ac«tom«tr7.  .  Commercial  vinegar  varies  greatly  as  regards  the  quantity  of  acetic 
it  contains.  '  The  specific  gravity  of  a  commercial  vinegar  is  no  certain  indication  of 
the  quantity  of  acetic  acid,  owing  to  the  fact  that  tiie  vinegar  nearly  always  con- 
tains foreign  matters.  The  testing  of  the  strength  can  therefore  only  be  accurately 
effected  by  means  of  saturating  it  with  an  alkali.  According  to  the  ordinary  method 
first  introduced  for  this  purpose  by  Otto,  ammonia  is  added  to  the  vinegar  to  be 
tested  until  the  previously  added  tincture  of  litmus  becomes  again  blue;  althoo^ 
this  method  is  not  absolutely  correct — owing  to  the  fact  that  the  neutral  alkaline 
acetates  exhibit  an  alkaline  reaction — tliis  does  not  much  impair  the  correctness 
of  this  process.  Otto's  acetometer  is  a  glass  tube  sealed  at  one  end,  36  centims. 
long  by  1*5  wide,  whereon  is  engraved  a  double  scale  of  divisions,  one  of  these 
towards  the  bottom  of  the  tube  serving  for  measuring  the  vinegar  coloured  by 
litmus,  while  the  otlier  upper  scale  is  intended  for  measuring  the  test  liquor.  When 
it  is  intended  to  apply  the  test  with  this  measuring  tube,  a  certain  quantily  (indicated 
by  Uie  divided  scale)  of  litmus  tincture  is  first  poured  into  the  tube,  next  vinegar  is 
added  in  sufficient  quantity  to  fill  the  tube  up  to  the  second  division ;  afterwards  so 
much  of  the  test-liquor  is  added  as  to  restore  again  the  blue  colour  of  the  litmus. 

The  quantity  of  test-liquor  employed  indicates  the  percentage  of  acetic  acid  con- 
tained in  the  vinegar.  The  test-fluid  should  contain  1*369  per  cent  of  ammonia. 
According  to  Mohr's  method  there  are  taken  of  the  vinegar  to  be  tested 

(2CaH40,-H,0  =  i^  =  5i); 
and  usually  having  a  sp.  gr.  varying  between  1*010  and  I'oii,  5*04  c.c.^ 

(    for  ^11=504) 

\  I'OII  / 


VttiEGJR.  469 

or  aimplj  5  e.c,  to  which  ia  added  tincture  of  litmus,  the  whole  being  titrated  with  a 
normHl  alkali  blue  (a  titrated  caustic  potassa  solation  rendered  blue  with  litmus).  It 
is  better  to  take  10  c.c  of  the  vinegar  aud  halve  the  number  of  c.c.  of  potassa 
employed. 

EiamplsB : —  i.  10*0  0.0.  of  a  Wurtzbnig  table  vinegiu*  required 

ii-S  CO.  of  potaah  aolntion,  and  the  vinegar  therefore  contained 
5-9  per  «ent  of  so-aalled  anbjdiouB  acid,  or  6-7  per  cent  of  ooetis 
add  (CjH^Oi). 
a.  10*0  e.o.  01  a  vuiegor  prepared  from  wood  vinegar  required 
iz'j  0.0.  of  potiksh  solation,  ouricBpondiug  to 
5*35  per  cent  of  anhydrona  acid,  or  7-3  per  cent  (CiH^Oi). 

fi.  Preparation  of  Viitegitr  frnnt  Wood  Vinegar. 
■wiHiyhKta.  From  the  dry  distillation  of  wood  a  portion  of  the  carbonised  matter 
remains  in  the  retorts  as  charcoal,  while  the  remainder  of  the  constituents  of  the 
wood  are  eliminated  partly  in  the  state  of  gases  and  Tapours,  sucli  as  carbonic  oxide, 
carbonic  acid,  hydrogen,  light  and  heai-y  carburetted  hydrogens — partlyin  the  shape 
<^  a  condensed  matter,  consisting  of  a  thick,  brown,  oily  fluid  floating  upon  a  stnttum 
of  a  watery  Hqaor.  The  latter,  wood  Tinegar,  consiBla  esBentially  of  impure  aceUc 
acid,  some  propionic  and  butyric  acids,  small  quantities  of  oxj-phenic  acid,  creosote. 


and  an  aleoholio  wood  spirit,  a  mixture  of  melhylic  alcoliol,  aceton,  and  acetate  of 
methyl,  the  brown,  thickish  fluid  substance  known  as  wood  tar.  oonsisting  of  a 
number  of  both  fluid  and  solid  bodies,  paraffin,  naphthalin,  ci^osote,  benzol,  toluol,  &:. 
A  well-conducted  distillation  will  yield  as  much  as  from  7  te  8  per  cent  of  the  weight 
of  the  wood  acetic  add.  According  to  the  researches  of  H.  Vohl,  peat  can  be  employed 
in  the  preparation  of  wood  vinegar  and  of  wood  spirit.  10  cwts.  of  peat  yield  3  kiloa. 
of  acetic  acid  and  145  kilos,  of  wood  spirit  lite  Table  on  the  next  page  shows  the 
principal  products  of  the  destructive  distillation  of  wood. 

Raw  wood  vinegar  contains  in  solution  a  not  inconsiderable  quanti^  of  resin,  and 
also  small  quantities  of  phenol  and  guaiacol ;  all  these  bodies  impart  a  more  or 
less  brown  colour  and  empyreomatic  odour  and  flavour,  but  they  also  render  it  a 


47© 


CHEMICAL  TECHNOLOGY. 


r 


[a.  Wood 
Wood  ■!  h.  Hygroscopic ' 
Water 


'Acetylen,  O2H2 
Elayl,  CaH^ 
lnimnatingJ3^!J*yl;p3H6 

Gas  |?*"^*T^V^^ 

1  Benzol,  CeHe 


Xylol,  CsHio 

Naph 

Carbonic 

Carbonic 

Hydrid 

Hydrogen,  Ha 


i3.  Tar 


Toluol,  C7H8 

Benzol,  C^B^ 

Toluol,  C7H8 

Styrolen,  CsHs 

Naphthalin,  CxoHs 

Betene,  CxsHig 

Paraffin,  C20H42,  or  C22H46 

Carbolic  acid,  CeHeO 

Cresylic  add,  C7HgO 

.Phlorylio  acid,  CsHzoO 

Guaicol  /Ozyphenio  add,  CeHeOa 

(C  HftO    ^  CombinationB 
CsHioOa 
.CeHxaOa 


•  Phenol 


Besin 


Creosote 


oxyphenio  add 
and  homologoufl 
adds  with  methyl* 


Wood  Vine- 
gar 


i.  Charcoal 


Acetic  add,  C2H402 
Propionic  acid,  CoEaOa 
Butyric  acid,  C4H8O2 
Valerianic  add,  C0H10O2 
\  Caproio  acid,  Cxc^xaOa 
Aceton,  C.HeO 
Acetate  of  methyl,  C3H60a 
Wood  spirit,  CH4O 
.Phenol,  Guaicol,  and  Besin 

/Carbon        . .     . .  85  per  cent. 
J  Hygroscopic  water  12        „ 
(Ash       3        „ 


valuable  antiseptic.  Where  the  principal  aim  is  to  obtain  wood  vinegar, 
iron  retort,  somewhat  similar  to  a  gas  retort,  is  employed  for  the  iiinHlliti^CTi 
of  the  wood ;  but  in  France,  a  vertical  retort  of  boiler  plate,  exhibited  at  a. 
Fig.  Z4.9,  is  employed,  fitted  at  tiie  upper  part  with  a  tube,  o,  to  which  is  faoteDed 
the  projecting  part,  b.  When  the  iron  cylinder  is  filled  with  wood,  a  lid  is  tightly 
screwed  on  to  it,  it  being  next  lifted  up  and  placed  into  the  cylindrical  fomace,  b, 
by  means  of  the  crane,  d,  after  which  the  furnace  is  dosed  at  the  top  with 
the  firebrick  lid,  fe.  The  products  eliminated  from  the  wood  contained  in  tike 
retort  pass  into  the  tube  &,  Fig.  250,  and  thence  into  the  condensing  apparatos,  e, 
placed  in  a  £ramework,  dy  which  condensing  apparatus  is  kept  continually  siqvplied 
with  cold  water  by  the  tube/,  while  the  warm  water  flows  off  at  h.  Vinegar,  tar, 
and  wood  spirit  are  condensed  and  flow  into  the  vessel  ^,  in  which  the  tar  separates, 
the  lighter  fluids  flowiug  into  h  through  the  tube  m.  The  Cion-condensed  gases 
pass  through  the  tube  i  into  the  fireplace,  where  they  assist  in  heating  the  retort, 
so  that  but  very  littie  fuel  is  required.  In  large  factories,  instead  of  the  wooden 
recdvers,  large  stone  or  brickwork  cisterns  are  employed,  generally  several  of  sadii 
tanks  being  used,  the  largest  quantity  of  tar  being  condensed  in  the  first  dstem, 
while  the  wood  vinegar,  mechanically  freed  from  the  tar  and  floating  on  its  snifaoe» 

*  According  to  S.  Marasse  (1868),  Bhenish  beech- wood  tar  creosote  is  a  mixture  of  equal 
parts  of — 

Cre^lic  acid,  C^HsO,  boiling  at  203"*, 
and  Guaiacol         C7H8O2        ««        200*. 

The  latter  is  methylic  ether  with  oxyphenio  add,  JS^^  \  Oa. 


finds  its  way  into  a  second  cistern.     PeitenlfofeT's  patent  wood-gas  generators 
produce  a  not  inconsiderable  qnantity  of  wood  vinegar. 
PiuUriii«<Tiwiviiia[u.      Raw  wood  vinegar  is  a  clear  dark  brotvn  floid,  having  a  tany 


1  small  quantities 
FiQ.  asa 


taste  and  smokj  odour.  It  is  employed 
of  meat,  also  for  the  prSservation 
of  wood,  ropes,  4c. ;  but  by  far 
the  largest  quantity  is  employed  in 
the  preparation  of  the  varioua 
acetates  used  in  dyeing  and  calico 
printing,  chiefly  as  crude  acetate  of 
iron  and  crude  acetate  of  alumina. 
It  is  also  used  in  the  preparation  of 
concentrated  acetic  acid  for  indus- 
trial pnrposes.  that  is,  for  the  pre- 
paration of  aniline  from  nitro^beo- 
zol,  and  of  sngar  (acetatet  of  lead. 
IiasCly.  it  is  largely  used  in  the 
preparation  of  table  vinegar,  an 
cperation  economical  only  where, 
ss  in  England,  there  is  a  high 
duty  on  alcoholic  fluids. 

Among  the  means  of  puri^ng 
crude  wood  vinegar,  the  most 
simple — leaving  out  of  the  question  the  filtration  of  the  crude  liquor  over 
coarsely  granulated  wood  charcoal  as  recommended  by  E.  Assmus — is  distillation, 
an  operation  usually  carried  on  in  a  still  made  of  copper  fitted  with  a  coppor 
condensing  apparatus.  At  first  a  yellow  fluid  comes  over — raw  wood  spirit  from 
which  the  wood  spirit  of  commerce  is  prepared — and  next  the  distillate  becomes 
richer  in  acetic  acid. 

The  principal  methods  at  present  employed  for  the  purification  of  wood  vinegar 
nay  be  considered  as  foiling  under  eitlier  of  tivo  classes : — 

a.  The  first  includes  the  purifying  of  wood  vinegar  without  saturation  with  a 
base;  while 

0.  The  second  includes  those  methods  in  which  the  wood  vinegar  is  purified  by 
conversion  into  an  acetate,  the  acetic  acid  being  next  separated  by  distillatioa 
with  an  acid  possessing  greater  affinity  for  the  base. 

To  the  first  class  belongs  Stoltze's  method,  consisting  in  first  obtaining  hy  dis- 
tillation lo  per  cent  of  a  liquid  which  is  employed  for  the  preparation  of  wood 
spirit ;  8o  per  cent  of  the  liquid  is  next  distilled  off  and  the  empyrenmatio 
substances  contained  are  destroyed  by  the  action  of  either  ozone  or  chlorine. 
The  purification  of  the  crude  wood  vinegar  by  the  second  method  is  more 
generally  in  use  among  manufacturers,  the  inventor  of  the  system  being  MoUerat. 
The  crude  wood  vinegar  is  first  saturated  with  lime  and  the  solution  next 
precipitated  with  Glauber's  salt  to  obtain  acetate  of  soda;  this  salt  is  purified  hy 
dTsLallisation,  and  when  in  a  dry  state  is  so  far  heated  that  the  empyreumatie 
matter  it  is  mixed  with  becomes  carbonised  and  is  thus  rendered  insoluble:  the 
acetate  of  soda  is  then  extracted  witli  water,  and  the  acetic  acid  separated  from  it 
by  distilling  the  previously  crystaUisod  .ind  dried  salt  with  sulphuric  acid.    Instead 


472 


CHEMICAL  TECHNOLOGY. 


of  acetate  of  soda  the  acetate  of  lime  is  freqnentlj  employed  in  the  preparstion  of 
acetic  acid  from  crude  wood  vinegar,  the  latter  being  saturated  wiili  lime,  and  die 
salt  foiined  evaporated  to  dryness.  The  dry  salt  is  roasted  and  treated  similarly  to 
the  acetate  of  soda  to  calcine  any  empyreumatic  products.  The  acid  employed  in 
the  distillation  is,  according  to  the  method  invented  by  C.  Volckel,  hydioefalozie 
acid.  The  distillation  can  be  effected  in  a  retort  with  a  helm  of  copper  and  a 
condenser  of  lead,  tin,  or  silver.  Upon  loo  parts  of  acetate  of  lime  90  to  95  parts  <d 
hydrochloric  acid  at  i'i6  sp.  gr.  are  used.  When  hydrochloric  acid  i&  used  in  tliis 
preparation  instead  of  sulphuric  acid,  any  contamination  of  the  crude  acetate  of  Ixdm 
with  empyreumatic  or  tarry  matter  does  not  affect  the  purity  of  the  acetie 
which  is  obtained,  provided  the  crude  acetate  be  first  so  well  dried  as  to  be 
from  all  other  volatile  substances;  when  sulphuric  acid  is  used  for  this  pnrpoae 
the  result  is  that  an  acetic  acid  is  obtained,  which  contains  not  only  a  large  quantity 
of  sulphurous  acid,  but  also  other  offensive  volatile  compounds  due  to  the  deoompo- 
sition  (by  the  sulphuric  acid)  of  empyreumatic  resins  and  tany  matter  present  ia 
the  crude  acetate  of  lime. 

Wood  Spirit.  When  the  acid  liquid  obtained  by  the  dry  distillation  of  wood  is 
distilled  on  the  large  scale,  there  comes  over  at  first  a  certain  quanti^  of  a 
yellow  fluid,  lighter  than  water,   and  exhibiting  an  ethereo-empyreumatic  odour. 

This  fluid  (wood  spirit)  consists  chiefly  of  methylic  alcohol,  CH4O,  or     X7^[0, 

aceton,  acetate  of  methyl,  and  other  substances  to  which  no  reference  need  be 
made.  Wood  spirit  was  first  discovered  by  Taylor  in  1812,  and  was  for  a  long 
time  only  employed  for  burning  in  spirit-lamps ;  it  was  not  until  1822  that  Taylor  foond 
this  body  was  a  new  substance.  Wood  spirit  is  in  a  pure  state  a  colourless  flnid  of 
0*814  sp-  g^M  boiling  at  66"  0.  It  is  in  all  respects  very  similar  to  alcohol,  and  can 
be  employed  as  a  source  of  heat  in  spirit-lamps;  it  evaporates,  however,  more 
rapidly  and  gives  a  less  intense  heat,  for  whereas  i  part  by  weight  of  alcohol  yields 
by  its  complete  combustion  to  carbonic  acid  and  water  7189  units  of  heat,  an  equal 
quantity  of  wood  spirit  only  yields  5307  units  of  heat.  It  is  employed  in  the 
preparation  of  furniture  polish  and  in  varnish  making;  for  these  purposes,  how- 
ever,  it  requires  to  be  well  purified,  and  its  rapid  evaporation  is  a  drawback  to  its 
extensive  use;  confirmed  spirit  drinkers  have  now  and  then  used  it  instead  of 
whiskey  and  the  like,  and,  it  appears,  without  bad  effects.  Its  most  recent  use  is  in 
the  preparation  of  iodide  and  bromide  of  methyl,  which  substances  are  employed 
in  the  manufacture  of  violet  and  blue  coal-tar  colours. 


The  Preservation  op  Wood. 

^SStagSSi**'  ^®  durability  of  wood,  viz.,  its  power  of  resisting  the  destructive 
influences  of  wind  and  weather,  varies  greatly,  and  depends  as  much  upon  the 
particular  kind  of  wood  and  the  influences  to  which  it  is  exposed  as  upon  the  origin 
of  the  wood  (timber),  its  age  at  the  time  of  felling,  and  other  conditions.  Beech- 
wood  and  oak  placed  permanently  under  water  may  last  for  centuries.  Alder  wood 
lasts  only  a  short  time  when  in  a  dry  situation,  but  when  kept  under  water  it  is  a 
very  lasting  and  substantial  wood.  Taking  into  consideration  the  different  kinds 
and  varying  properties  of  wood  and  the  different  uses  to  which  it  is  applied,  we  have 
to  consider  as  regards  its  durability  the  following  particulars : — 


WOOD.  473 

1.  Whether  it  is  more  liable  to  decay  by  exposure  to  open  air  or  when  placed  in 
damp  situations ; 

2.  Whether  it  is  when  left  dry  more  or  less  attacked  by  the  ravages  of  insects  which, 
while  in  a  state  of  larvsB,  live  and  thrive  in  and  on  wood. 

Pore  woody  fibre  by  itself  is  only  very  slightly  affected  by  the  destructive 
influences  of  wind  and  weather.  When  we  observe  that  wood  decays,  that  decay 
arises  from  the  presence  of  substances  in  the  wood  which  are  foreign  to  the  woody 
fibre,  but  are  present  in  the  juices  of  the  wood  while  growing,  and  consist  chiefly 
of  albuminous  matter,  which,  when  beginning  to  decay,  also  causes  the  destruction 
of  the  other  constituents  of  the  wood;  but  these  changes  occur  in  various  kinds 
of  wood  only  after  a  shorter  or  longer  lapse  of  time ;  indeed,  wood  may  in  some 
instances  last  for  several  centuries  and  remain  thoroughly  sound;  thus  the  roof  of 
Westminster  Hall  was  built  about  1090.  Since  resinous  woods  resist  the  action  of 
damp  and  moisture  for  a  long  time,  they  generally  last  a  considerable  time ;  next 
in  respect  of  durability  follow  such  kinds  of  wood  as  are  veiy  hard  and  com- 
pact, and  contain  at  the  same  time  some  substance  which — ^like  tannic  acid — ^to 
some  extent  counteracts  decay.  The  behaviour  of  the  several  woods  under  water 
differs  greatly.  Some  woods  are  after  a  time  converted  into  a  pulpy  mass.  Other 
kinds  of  wood,  agaui,  undergo  no  change  at  all  while  under  water,  as,  for  instance, 
oak,  alder,  and  fir. 

Insects  chiefly  attack  dry  wood  only.  Splint  wood  is  more  liable  to  such  attack  than 
hard  wood ;  while  splint  of  oak  wood  is  rather  readily  attacked  by  insects,  the  hard 
wood  (inner  or  fully  developed  wood)  is  seldom  so  affected.  Elm,  aspen,  and  all 
resinous  woods  are  very  seldom  attacked  by  insects.  Young  wood,  which  is  full  of 
sap  and  left  with  the  bark  on,  soon  becomes  quite  worm-eaten,  especially  so  the  alder, 
birch,  willow,  and  beech.  The  longer  or  shorter  duration  of  wood  depends  more  or 
less  upon  the  following  conditions : — 

a.  The  conditions  of  growth.  Wood  from  cold  climates  is  generally  more  durable 
than  that  grown  in  warm  climes.  A  poor  soil  produces  as  a  rule  a  more  durable 
and  compact  wood  than  does  a  soil  rich  in  humus,  and  therefore  containing  also 
much  moisture. 

b.  The  conditions  in  which  the  wood  is  placed  greatly  influence  its  duration.  The 
warmer  and  moister  the  climate  the  more  rapidly  decomposition  sets  in ;  while  a  dry, 
eold  climate  materially  aids  the  preservation  of  wood. 

e.  The  time  of  felling  is  of  importance :  wood  cut  down  in  winter  is  considered 
more  durable  than  that  felled  in  summer.  In  many  countries  the  forest  laws  enjoin 
the  felling  of  trees  only  between  November  15  and  February  15. 

Wood  employed  for  building  purposes  in  the  country,  and  not  exposed  to  either 
heat  or  moisture,  is  only  likely  to  suffer  from  the  ravages  of  insects ;  but  if  it  is  placed 
so  that  no  draught  of  fresh  air  can  reach  it  to  prevent  accumulation  of  products  of 
decomposition,  decay  soon  sets  in,  and  the  decaying  albuminous  substances  acting  upon 
the  fibre  cause  it  to  lose  its  tenacity  and  become  a  friable  mass.  Under  the 
influence  of  moisture  frmgi  are  developed  upon  the  surface  of  the  wood.  These  fungi 
are  severally  known  as  the  "house  fungi"  (Thetephora  domestica  and  Boletus 
destructor),  the  clinging  fungus  (CenUius  vastator).  They  spread  over  the  wood  in  a 
manner  very  similar  to  the  growth  of  common  fungi  on  soil.  Their  growth  is  greatly 
aided  by  moisture  and  by  exclusion  of  light  and  fresh  air.  A  chemical  means  of 
preventing  such  growths  is  found  in  the  application  to  the  wood  of  acetate  of  oxide  of 


474  CHEMICAL  TECSNOLOGY. 

iron,  the  acetate  being  prepared  from  wood  vinegar.  Wood  is  oft«n  more 
injuriously  affected  when  exposed  to  sea  water,  when  it  is  attacked  by  a  pecnlnr 
kind  of  insect  known  as  the  bore- worm,  Teredo  nuvalis.  This  insect  is  armed  with 
a  homed  beak  capable  of  piercing  the  hardest  wood  to  a  depth  of  36  centimetres. 
These  insects  originally  belonged  to  and  abound  in  great  number  in  the  seas 
under  the  ti'opical  clime:  but  the  Teredo  navcdU  is  met  with  on  the  coasts  d 
Holland  and  England. 

^"^^c^."^      The  means  usually  adopted  to  prevent  the  destruction  of  wood  by 
decay  are  the  following : — 

1.  The  elimination,  as  much  as  possible,  of  the  water  from  the  wood  previously 
to  its  being  employed ; 

2.  The  elimiuation  of  the  constituents  of  the  sap ; 

3.  By  keeping  up  a  good  circulation  of  air  near  the  wood  so  as  to  prevent  its 
suffocation,  as  it  is  termed ; 

4.  By  chemical  alteration  of  the  constituents  of  the  sap ; 

5.  By  the  gradual  mineralisation  of  the  wood  and  thus  the  elimination  of  the  organie 
matter. 

nryingwood.      I.  Thoroughly  dried  wood  remains  for  a  long  time  unaltered  while  in 
a  diy  situation,  more   especially  so  when   dried  by  so  strong   a  heat  that   it 
becomes  browned.    When  timber  has  to  be  put  into  a  damp  situation,  it  should, 
after  having  been  well  dried,  be  first  coated  with  a  suitable  substance  to  prevent 
the  moisture  penetrating  into  the  wood.      This  purpose  is  attained  by   coatuig 
the  wood  with  linseed  oil,  so-called  Stockholm  tar,  coal  tar,  creosote,  and  other 
hydrocarbons.     Hutin  and  Boutigny  adopt  tlie  following  method  to  prevent  the 
absorption  of  moisture  by  wood  that  is  put  into  the  ground.     The  portion  of 
the  post  or  wood  to  be  buried  is  first  immersed  in  a  vessel  containing  benzolr 
petroleum,  photogen,  &c.,    and   when  taken    out    is    ignited  and   thus  charred. 
When  extinguished  the  wood  is  put  to  a  depth  of  from  3  to  6  centimetres  into  a 
mixture  of  pitch,  tar,  and  asphalte,  and  next  the  entire  piece  of  wood  is  thorongfalT 
painted  over  with  tar. 

miminauon  of^the^constitMnt.  2.  The  coustituents  of  the  sap  are  the  chief  cause  of  the 
decomposition  of  wood,  and  they  should  consequently  be  removed :  many  plaas  are 
adopted.  In  order  that  the  wood  may  contain  the  smallest  quantity  of  sap,  it  should 
be  felled  during  the  winter  months.  The  constituents  of  the  sap  can  be  eliminated 
from  the  felled  tree  by  three  methods : — 

a.  By  treatment  with  cold  water,  with  which  the  wood  must  be  thoroughly  saturated 
to  dissolye  the  constituents  of  the  sap,  which  are  removed  when  the  wood  is  exposed  to  a 
stream  of  water.  It  is  evident  that  with  large  timber  a  long  time  is  necessary  to  ensoie 
perfect  saftiration. 

5.  By  employing  boiling  water  the  sap  is  removed  much  more  quickly  and  efficiently- 
The  pieces  of  wood  are  placed  in  an  iron  vessel  with  water  and  boiled.  Large  pieces  of 
timber  camiot  be  treated  in  this  manner,  bnt  are  immersed  in  a  cistern  in  which  the  flnid 
is  heated  by  means  of  steam.  According  to  the  thickness  of  the  wood,  the  boiling 
occupies  some  6  to  12  hours. 

c.  By  treatment  with  steam  (steaming  of  wood) — the  most  effectual  method  of  removing 
the  constituents  of  the  sap,  the  hygroscopicity  of  the  wood  thus  treated  being  rendered 
much  less,  while  the  wood  is  far  more  fitted  to  resist  the  effects  of  weaUier.  The 
apparatus  employed  in  carrying  out  the  method  consists  of  a  boiler  for  the  generation  of  11 

steam,  and  a  cistern  or  steam  chamber,  for  the  reception  of  the  wood,  this  chamber  being 
constructed  of  masonry  and  cement,  of  boiler  plate,  or  being  simply  a  large  and  very 
wide  iron  pipe.  In  most  cases  a  jet  of  steam  is  conveyed  from  the  boiler  to  the  steani' 
chamber,  where  it  penetrates  the  wood,  and  dissolves  out  the  constituents  of  the  sap, 
which  on  being  condensed  is  allowed  to  run  off.    In  the  case  of  oak,  this  fluid  is  of  ft 


WOOD.  475 

Iblack-brown  colonr ;  with  mahogany,  a  brown-red ;  with  linden  wood,  a  red-yellow ;  and* 
"^vith  cherry  tree  wood,  a  red,  &o.  The  operation  is  finished  when  the  outflowing  water  is 
sao  more  coloured.  The  steamed  wood  is  dried  in  the  air  or  in  a  drying  room  ;  it  loses 
3  to  ID  per  cent  in  weight  by  the  process,  and  becomes  of  a  much  darker  colour. 
TThe  steam  is  sometimes  worked  at  a  temperature  of  above  loo**,  but  generally  the  con- 
'kents  of  the  steam  chamber  are  maintained  at  60°  to  joP,  Towards  the  end  of  the 
operation  some  oil  of  coal-tar  is  introduced  into  the  boiler,  and  is  consequently  carried 
over  with  the  steam,  impregnating  the  wood. 

The  remoYal  of  the  sap  can  also  be  effected  to  some  extent  by  means  of  mechanical 
preesure  between  a  pair  of  iron  rollers,  which  are  gradually  brought  more  closely 
-together.  Another  method  is  by  means  of  air  pressure.  Barlow  employs  for  this 
parpose  a  metid  caise  in  which  the  wood  is  enclosed,  and  to  one  end  of  which  an  air 
pomp  is  attached.  Air  being  forced  into  the  tube  or  case,  the  sap  flows  away  at  the  end 
opposite  to  which  the  pump  is  attached.  But  both  these  methods  are  costly  and  not  in 
ail  oases  applicable. 

'  AirDnina.  3.  The  Construction  of  air  drains  or  passages  around  woodwork  to  be 
preserved  is,  where  tho  method  is  applicable,  a  great  aid  ^o  the  preservation  of  the  wood. 
Ihe  consideration  of  the  best  means  of  effecting  ventilation  in  this  respect,  is  not  a 
matter  with  which  we  can  deal  in  this  work.  It  is  sufficient  to  say,  that  in  many 
instances,  the  air  channels  are  connected  on  the  one  hand  with  the  open  air,  and  on  the 
other  with  the  chimney. 

^^comSttt^^fSe  sS?  ^'  ^°®  ^^  *^®  °^°®*  usual  and  most  effective  means  of  pre- 
-venting  the  decomposition  of  wood  is  by  effecting  a  chemical  change  in  tlie 
constituents  of  the  sap,  so  that  fermentation  can  no  longer  be  set  up.  To  this  class 
belongs  the  well-known  plan  of  protecting  woodwork  that  is  to  be  exposed  to 
the  action  of  the  moisture  of  the  earth  by  charring  the  wood,  either  by  fire  or 
by  treatment  with  concentrated  sulphuric  acid,  so  that  the  wood  is  coated  to  a  certain 
depth  with  a  layer  of  charcoal,  the  charcoal  acting  as  an  antiseptic  The  charring 
or  carbonisation  of  the  wood  can  be  effected  either  with  the  help  of  a  gas  flame  or 
the  flame  from  a  coal  fire.  The  apparatus  of  De  Lapparent,  invented  for  this  purpose, 
became  very  generally  employed  in  1866  at  the  dockyards  of  Cherbourg,  Pola,  and 
Dantzic.  According  to  another  method  the  wood  is  impregnated  throughout  its 
whole  mass  with  some  substance  that  either  enters  into  combination  with  the  con- 
stituents of  the  sap,  or  so  alters  their  properties  as  to  prevent  the  setting  up  of 
decomposition.  To  ,this  class  belong  the  four  following  methods,  these  being  the 
only  ones  that  have  met  with  any  more  extensive  use. 

I.  Kyan's  preserving  fluid  is  a  solution  of  bichloride  of  mercury  of  variable 
degree  of  concentration.  In  England  a  solution  of  i  kilo,  of  corrosive  sublimate  in 
80  to  100  litres  of  water  is  generally  employed  for  railway  sleepers.  The  timber  is 
laid  in  a  watertight  wooden  trough,  containing  the  solution,  where,  according  to  its 
size,  it  remains  a  longer  or  shorter  time.  In  Baden  the  wood  remains  in  the 
liyanising  solution,  when  it  is  to  be  impregnated  to  a  depth  of— 

82  m.m.  for  4  days. 
85  to  150       „        7    „ 
150  to  180       „      10    „ 
180  to  240       „      14    „ 
240  to  300       „      18 


)» 


the  solution  consisting  of  i  kilo,  of  sublimate  to  200  litres  of  water.  The  prepared 
wood  is  washed  with  water,  rubbed  diy,  and  then  placed  in  sheds  free  from  exposure 
to  rain  and  strong  sunlight.  The  principal  action  of  the  bichloride  of  mercury  is  to 
convert  the  albumen  of  the  sap  into  an  insoluble  combination,  capable  of  with- 
standing decomposition,  while  the  bichloride  becomes  gradually  reduced  to  proto- 
chloride  of  mercury  (calomel).    A  great  objection  to  this  method  is  the  danger  to 


476  CHEMICAL  TECHNOLOGY. 

which  the  carpenter  or  joiner  who  may  afterwards  shape  the  wood  is  exposed,  the 
free  chemicals  acting  upon  his  system  through  his  hands,  nostrils,  and  mouth.  In 
England  wood  to  he  varnished  is  seldom  kyanised. 

Erdmann  remarks  upon  this  plan  of  preserving  wood  that  the  interior  of  the  log  im 
still  left  in  its  original  condition.  To  answer  the  ohjection  the  kyauising  lias  been 
made  more  effective  hy  placing  the  wood  into  a  water-tight  trough,  with  the  aolntioA 
of  suhlimate,  and  by  a  great  pressure  of  air  thoroughly  impregnating  the  wood. 
Kyanising  by  this  method  becomes,  however,  as  expensive  as  any  other  impregnatiaQ 
method.  Recently  there  has  been  substituted  for  the  pure  bichloride  of  mercnxy  a 
double  salt  of  the  formula  HgOla-fKCl,  obtained  by  decomposing  a  aolatum  of 
camallite  with  oxide  of  mercury. 

2.  Burnett's  patent  (1840)  fluid  consists  of  i  kilo,  of  chloride  of  zinc  dissolved  in. 
90  litres  of  water.  Wood  treated  with  Burnett's  fluid  has  been  buried  in  earth  for 
five  years  without  undergoing  any  change,  while  unprepared  wood  buried  for  the 
same  lengUi  of  time  has  been  totally  destroyed.  Chloride  of  zinc  has  been  mncb 
used  in  Germany  as  an  impregnating  material.  Besides  this  salt  sulphate  of  copper 
and  acetate  of  oxide  of  zinc — ^pyrolignite  of  zinc  (Scheden's  method],  have  been 
employed.  The  action  of  the  copper  and  zinc  salts  may  be  explained  by  considering 
that  the  metallic  oxides  of  the  basic  salt  formed  during  seasoning,  separates  and 
combines  with  the  colouring  matter,  tannic  acid,  resin,  &c.  of  the  wood,  to  form  an 
insoluble  compound. 

3.  Bethell's  (1838)  patented  method  consists  in  treatment  under  strong  pressure 
with  a  mixture  of  tar,  oil  of  tar,  and  carbolic  acid,  this  mixture  being  known  com- 
mercially by  the  name  of  gedlotin.  In  and  near  London  wood  thus  treated  has 
remained  eleven  years  in  the  earth  without  undergoing  change;  other  pieces  of 
timber  so  treated  were  subjected  to  the  action  of  the  sea  for  four  years  and  still  were 
in  good  condition.  Vohl  employs  for  preservation  peat  and  bro^vn  coal  creosote ; 
Leuchs  uses  paraffin.  Such  agents,  however,  render  wood  treated  with  them  highly 
inflammable. 

4.  Payne's  method.  This  includes  two  patents,  the  first  having  been  taken  oot  in 
X841.  Both  are  based  on  the  impregnation  of  the  wood — ^first  with  one  salt,  and 
next  with  another  salt,  which  is  capable  of  forming  a  precipitate  insoluble  in  water 
and  sap  of  the  wood  with  the  first.  The  first  solution  is  usually  one  of  sulphate  of 
iron  or  of  alum,  then  follows  a  solution  of  chloride  of  calcium  or  of  soda.  The  wood 
to  be  impregnated  is  placed  in  a  vessel  from  which  the  air  is  exhausted,  the 
first  solution  being  then  admitted,  and  subsequently  pressure  is  applied.  The  first 
solution  being  removed,  the  second  is  admitted,  and  pressure  again  applied.  It  is 
necessary  to  dry  the  wood  partially  between  the  two  impregnations.  Payne's 
method,  much  used  in  England,  possesses,  moreover,  the  advantage  of  rendering  the 
wood  somewhat  uninflammable.  The  same  effect  results  with  the  methods  of  Buchner 
and  Von  Eichthal,  who  impregnate  the  wood  with  a  solution  of  sulphate  of  iron, 
and  then  with  a  water-glass  solution,  whereby  the  pores  of  the  wood  are  filled  with 
ferro-siHcate.  Bansome  attains  the  same  end  by  an  impregnation  with  a  water-glass 
solution  and  subsequent  treatment  witli  an  acid.  It  is  found  that  the  treatment  of  wood 
according  to  tlie  above  methods  is  generally  attended  with  good  results.  A  method 
of  impregnation  with  materials  forming  an  insoluble  soap,  oleate  of  alumina,  oleate  of 
copper,  &c.,  patented  in  1862,  has  given  some  moderate  results  on  the  small  scale. 

MtTwiraiMm  Wood.      5.  When  the  terms  mineralised,  petrified,  metallised,  orincrosted 
are  applied  to  wood,  they  include  the  meaning  that  the  wood  has  undergone  impreg- 


I 


WOOD. 


477 


nation  with  an  inorganic  substance,  which  has  so  filled  the  pores  of  the  wood  that  it 
xnay  be  said  to  partake  of  the  characteristics  of  a  mineral  substance.  Suppose  tliat 
the  wood  has  become  impregnated  with  sulphate  of  iron,  when  exposed  to  the  rain 
the  sulphate  will  be  gradually  dissolved  out,  in  time  leaving  only  a  basic  sulphate. 
Sy  the  researches  of  Striitzki  (1834),  of  Apelt  in  Jena,  and  of  Kuhlmann  (1859),  the 
influence  of  oxide  of  iron  upon  wood  fibre  has  been  rendered  very  clear.  Wood 
impregnated  with  basic  sulphate  of  iron  ceases  to  be  wood  after  some  time. 

^'towSi^uSl^*''  6.  This  method  consists  in  the  impregnation  of  the  wood  with 
the  necessaiy  substance,  in  a  manner  similar  to  the  natural  filling  of  the  pores  with 
sap ;  that  is  to  say,  the  solution  is  introduced  into  the  tree  from  its  roots,  and  is  thus 
made  to  take  the  place  of  the  sap  in  all  parts  of  the  timber.  When  the  tree  is  felled 
the  root  end  is  placed  in  a  solution  of  the  salt  (sulphate  of  copper,  acetate  of  iron), 
and  allowed  to  remain  for  some  days ;  at  the  end  of  the  required  time  the  wood  will 
have  become  completely  impregnated  with  the  salt.  Occasionally  this  method  is 
employed  in  colouring  woods,  colouring  matter  being  used  instead  of,  or  as  well 
as,  the  salt  The  linden,  beech,  willow,  elm,  alder,  and  pear  tree  can  be  treated  in 
this  manner.  The  fir,  oak,  ash,  poplar,  and  cherry  tree  do  not,  however,  absorb  the 
impregnating  fluid  sufficiently. 


Tobacco. 

TotaMeo.      Tobacco,  as  employed  for  snuff  and  for  smoking  and  chewing,  is  tlie 

product  of  various  kinds  of  annual  plants  belonging  to  the  genus  Nicotiana,  of  the 

family  of  Solanea,  generally  cultivated  in  warmer  parts  of  the  globe,  but  capable  of 

growing  in  countries  situated  under  52°  N.  lat.    The  best  tobaccos  are  grown  in 

America,  and  are  chiefly  exported  from  the  southern  states  of  North  America,  viz., 

Maryland,  Virginia,  &c.,  from  Orinoko,  Havanna,  and  Cuba,  &c.     The  European 

tobaccos  are  those  of  Holland,  Hungary,  Turkey,  and  France.     In  Europe  three 

separate  botanic  varieties  are  cultivated.    They  are : — 

z.  Common  or  Virginian  tobacco  {Nieotiana  tahacum)t  with  a  large  lancet-shaped 
ribbed  leaf. 

2.  Maryland  tobacco  {Nieotiana  macrophylla)^  with  broad  and  not  so  strongly  pointed 

leaves  as  those  of  the  common  tobacco  plant. 

3.  The  farm  or  violet  skin  tobacco  (Nicotiana  rustiea),  with  an  oval  leaf  and  long  stalk. 

The  quality  of  the  tobacco  is  dependent  upon  the  climate,  upon  the  soil,  and  upon 
the  seed  it  is  obtained  from.  Next  to  the  vine,  the  tobacco  plant  is  that  requiring  the 
most  care  in  its  cultivation.  The  influence  of  careful  culture  is  so  great,  that  plants 
grown  in  some  parts  of  Germany  yield  tobacco  unequalled  by  some  of  the  richest 
tropical  produce. 

According  to  the  most  recent  researches,  tobacco  contains  the  following  sab- 
stances: — 

(Potash 
Lime  Orffanic  f 

Ma^esia  ^^      j  Nicotine 

Oxides  of  iron  and  manganese  ^ 

Ammonia 


Mineral  acids 


^  Nitric  acid 
Hydrochloric  acid 
Sulphuric  acid 
Phosphoric  acid 


/^Malic  acid  (Tobacco  add  ?) 
I  Citric  acid 
Organic  ]  Acetic  acid 
acids      I  Oxalic  acid 
I  Pectic  acid 
xUlmic  acid 


478  CHEmCAL  TECHNOLOGY. 

INicotianin 
(xreen  and  yeUow  resin 
>  ax  or  lat 
isiitrogenous  substances 
Cellulose 

^""*^obi2S°Sif"  *'  ""•  The.  cHef  characteristic  constituents  of  the  tobacco  leaf  an 
the  tliree  following : — namely,  nicotianin,  nicotine,  and  malic  acid.  Kieotiaiun,  or 
tobacco  camphor,  is  a  fatty  substance,  possessing  sti'ongly  the  odour  of  tobacco,  ami 
a  bitter,  aromatic  flavour.  Experience  has  shown  that  the  varieties  of  tobacco  con- 
taining the  most  nicotianin  are  those  most  preferred.  It  is  generally  considered  Umi 
nicotianin  is  identical  with  cumarin  (OgHsOs),  found  in  the  tonka  bean  {ZHpUrix 
odorata),  in  the  Asperula  odorata,  in  the  Melilotus  officinalis,  and  Antkroxaatkwn 
odoratum,  as  well  as  in  the  leaves  of  the  Angraecum  fragrans^  and  the  Linsiris  odottt- 
ti$8ima.  Nicotine  (C10H14N2)  is  an  organic  base,  and  exists  in  a  pure  condition  as  a 
colourless  oil,  possessing  the  odour  of  tobacco  and  a  caustic  flavour ;  it  is  solnble  ii 
water,  alcohol,  ether,  and  some  oils.  It  is  even  in  very  small  doses  a  deadly  poisoii: 
and  in  the  very  smallest  quantities  it  will  cause  convulsions  and  paralysis,  llie  pfo- 
portion  of  nicotine  met  with  in  the  various  kinds  of  tobacco  leaves  varies  greatlv. 
From  the  experiments  of  Schloesing,  made  with  many  kinds  of  French  and  Americaa 
tobaccos,  the  following  quantity  per  cent  of  nicotine  is  found  in  the  dry  leaves  cf 

tobacco  from : — 

Nicotine. 

Departement  Lot  •••        ...        •••        •..        ...  7*96 

Lot-et-Garonne  ...        ...        ...        ...  7*34 

^orcl         ...        ...        ...        ...        ..a  6*58 

Ule-et-VilMne 6*29 

Pas  de  Calais      ...        ...        ...        ...        ...        ...  4'94 

lAisace       ...         ...         •••         ...         ...         ...         ...  3*21 

Virginia  ...        ...        ...        ...        ...        ...        ...  0*07 

Kentucky...         ...         ...        ...         ...        ...         ...  6*09 

Maryland  ...        ...        ...        ...        ...        .«.  2*29 

Havanna  ...        ...        ...        ...         less  than  2*00 

Dried  snuff-tobacco  contains  about  2  per  cent  of  nicotine,  and  contains  on  an 
average  in  its  undried  (usual)  condition  33  per  cent  of  water,  the  nicotine  then 
amounting  to  136  per  cent.  The  nicotine  is  contained  in  the  tobacco  in  the  form  of 
a  salt.  The  characteristic  acid  is  nicotic  or  tobacco  acid,  C3H4O4,  which  recent 
numerous  researches  have  proved  to  be  identical  with  malic  acid.  The  tobacco  leaf 
also  contains  albumen,  woody  fibre,  gums,  and  resin.  Tlie  leaves  are  also  very  rich 
in  mineral  constituents,  these  amounting  to  19  to  27  per  cent  of  the  weight  of  the 
dried  leaf.  Merz  obtained  about  23*33  P^^  ^^^^  ^^^  viiih  several  varieties  of. 
tobacco  leaf.  100  parts  of  this  ash  contained  potash,  2696 ;  soda,  276 ;  lime,  39*53 ; 
magnesia,  9*61 ;  chloride  of  sodium,  965 ;  sulphuric  acid,  278  ;  silica,  4-51  ;  and 
phosphate  of  iron,  4' 20  parts.  There  is  found,  also,  nitrate  of  potash,  the  quantity  of 
which  does  not,  however,  influence  the  combustibility  of  the  tobacco. 

Manufacture  of  Tobacco.  Good  smoldug  tobacco  should  give  off  an  agreeable  odour, 
should  not  deflagrate  while  burning,  and  not  bite  the  tongue.  Taste  differs  consideiv 
ably  in  the  respect  of  strength  in  this  country  from  abroad ;  nowhere  but  in  the 


1 


»> 

»» 


TOBACCO.  479 

United  Kingdom  are  such  strong  smoking  tobaccos  met  with.  The  freshly  dried 
tobacco  leaves  are  not  suited  for  smoking,  because  they  co^tain  a  very  considerable 
amount  of  albuminous  matter,  and  on  burning  give  off  an  odour  of  burnt  horn,  while 
they  contain  too  large  a  quantity  of  nicotine.  The  preparation  or  manufacture  of 
tobacco  aims  at  the  more  or  less  complete  destruction  of  the  albuminous  matters,  the 
partial  eUmination  of  the  nicotine,  and  the  development  of  a  peculiar  aroma,  while 
the  leaves  are  formed  by  mechanical  means  into  a  suitable  shape  for  smoking  and 
snuffing.  The  leaves  are  moistened  with  water  and  placed  together  in  heaps  so  as  to 
cause  a  kind  of  fermentation,  the  temperature  increasing  to  about  35°,  the  effect  of 
which  is  that  tlie  albuminous  matter  of  the  tobacco  is  destroyed,  while  aromatic 
substances  are  developed.  This  process  is  assisted  by  the  addition  of  what  the  trade 
terms  "  sauce,'*  but  nothing  is  known  of  the  reactions  and  changes  which  take  place. 
When  the  tobacco  leaves  are  gathered  from  the  plants  they  are  laid  one  upon  the  other  to 
the  number  of  ten  or  twelve  and  placed  in  heaps  in  a  dry  shed,  care  being  taken  to  cover 
the  heaps  with  canvas.  As  soon  as  the  sweating  sets  in,  the  leaves  are  suspended 
one  by  one  on  ropes  stretched  through  the  shed,  and  dried  by  exposure  to  a  current 
of  air ;  when  dry  the  leaves  are  packed  together  to  the  number  of  thirty,  so  as  to 
form  a  bundle,  several  hundreds  of  which  are  put  together  into  casks.  The  weight 
of  the  casks  filled  with  tobacco  averages  from  19  to  26  cwts.  In  some,  but  by  no 
means  in  all  instances,  the  cultivators  of  tobacco  prepare  the  leaves  to  some  extent  by 
first  moistening  them  with  brine  and  causing  them  to  undergo  a  partial  fermentation. 
The  leaves  are  then  dried  and  packed  in  casks.  By  this  means  tlie  tobacco  may  be 
preserved  for  a  great  many  years,  improving  with  age. 

smouiig  TobMco.  The  tobacco  leaves  are  first  sorted ;  that  is,  those  of  the  same  colour 
and  thickness  are  put  together.  They  are  next  stripped,  the  thicker  parts  (stem  or 
nerve)  being  cut  out,  because  as  these  consist  chiefly  of  woody  fibre  they  would  on 
burning  impart  an  unpleasant  odour  to  the  tobacco.  The  leaves  are  next  sauced  or 
moistened  with  a  liquor  containing  chiefly  salts  (common  salt,  saltpetre,  sal-ammo- 
niac, nitrate  of  anmionia),  saccharine  matter,  spirits,  and  some  organic  acids,  such  as 
tartaric  and  oxalic  acid ;  the  salts  assist  in  Ihe  preservation  as  well  as  in  the 
retardation  of  the  combustion  of  the  tobacco.  The  other  substances  impart,  under 
tlie  influence  of  fermentation,  a  peculiar  aroma  to  the  tobacco,  which  aroma  is  some- 
times compared  to  the  bouquet  of  wine.  The  sauced  leaves  are  next  submitted  to 
fermentation,  dried  at  a  gentle  hekt,  and  finaUy  cut  into  shreds  by  means  of 
machinery.  Tobacco  leaves  are  also  twisted  or  spun  together ;  for  instance,  in  the 
kind  known  as  twisst.  Cigars  are  tobacco  enveloped  in  a  smooth  leaf.  The  fact 
that  cigars  are  improved  by  keeping  is  due  to  a  kind  of  slow  fermentation,  during 
which  the  aroma  is  more  fully  developed,  while  noxious  substances  are  eliminated. 

Tobacco  smoke  contains,  in  addition  to  carbonic  acid,  water,  and  some  ammonia, 
the  products  of  the  dry  distillation  of  tobacco,  to  which  the  peculiar  flavour  is  due — 
among  these  substances  are  nicotine  and  nicotianin.  Zeise  found  in  tobacco  smoke  a 
peculiar  empyrematical  oil,  butyric  acid,  ammonia,  carbonic  acid,  paraffin,  empyreu- 
xnatic  resin,  traces  of  acetic  acid,  oxide  of  carbon,  and  carburetted  hydrogen. 

Curiously  enough,  burning  tobacco  does  not  form  carbohc  acid  nor  creosote;  hence 
tobacco  smoke  affects  the  eyes  less  than  does  the  smoke  of  smouldering  wood.  Zeise 
experimented  on  Porto  Rico  tobacco :  but  his  researches  fail  to  convey  any  informa- 
tion as  to  the  constitution  of  the  essential  aroma  of  tobacco  smoke ;  in  this  respect  it 
is  with  tobacco  as  with  the  bouquet  of  fine  brands  of  wine,  chemical  reagents  cannot 


^2  CHEMICAL  TECEN0L0G7. 

de  Cologne  is  obtained  by  disBolving  in  6  litres  of  alcohol  32  gnns.  ;of 
oil  of  orange-peel  and  equal  quantities  of  oil  of  bergamot,  r  lemoD,  etaemee  da 
limatte,  essence  de  petit  grains j  16  gnns.  essence  de  cedro,  and  equal  quantitiM  of 
essence  de  cedraty  essence  de  Portugal ;  further,  8  grms.  of  neroli  oil  and  4  gnna  of 

rosemary. 

The  perfomed  extracts  are  generally  obtained  by  the  exhaustion,  by  meaas  «£ 
alcohol,  ef  the  scented  fats  and  oils  prepared  from  flowers  as  before  described. 
Doebereiner  first  suggested  the  use  of  artificial  perfumes;  among  these  are  on 
ciMinieid  Perfumes,  alcoholic  Bolutiou  of  acetate  of  amyl  as  pear  oil,  valerate  of  amyl  as 
apple  oil,  buterate  of  amyl  as  pine-apple  oil,  pelargonate  of  ethyl  as  oil  of  qnineeB, 
Buberate  of  ethyl  as  essence  of  mulberries,  while  nitrobenzol  mixed  'with  mtrotolaol 
(commercial  nitrobenzol)  is  termed  artificial  oil  of  almonds,  and,  when  very  coarse,  is 
sold  as  essence  de  Mirbane,  chiefly  used  for  the  preparation  of  aniline.  The  perfomed 
fats  (pomatums)  of  better  quality  are  generally  prepared  from  an  infusioii  of  Ibe 
flowers  with  oil  or  &t  at  a  temperature  of  65°,  or  by  a  process  of  digestion  in  the 
cold  by  placing  the  flowers  in  layers  between  pure  lard  or  cotton-wool  soaked  in 
very  pure  olive  oil ;  enfleurage  is  the  name  given  to  this  operation.  The  ordinair 
pomatnms  are  made  simply  of  lard  or  marrow-fat  coloured  with  turmeric,  annatto,  or 
alkanet  root,  and  perfumed  with  a  few  drops  of  some  essential  oil. 

Fnpwmuonofooidiiai.  The  aim  of  the  preparation  of  liqueurs  (cordials)  is  to  render 
brandy  a  more  agreeable  beverage  by  the  addition  of  sugar,  glycerine,  and  aromatio 
substances.  A  distinction  is  made  between  finer  liqueurs  (rosoglio)  and  ordinsiy 
cordials  {aqua  vita)  according  to  the  quality  of  the  materials  employed  for  the  purpose. 
When  a  sufficiently  large  quantity  of  sugar  is  used  to  render  the  liqueurs  thickly  ffadd 
they  are  designated  crimes,  while  those  made  with  the  juices  of  fruit  obtained  by 
pressure,  sugar,  and  alcohol,  are  called  i*atafia.  These  liqueurs  are  not  prepared  to 
any  great  extent  in  this  country ;  but  in  France,  Italy,  Austria,  and  especially  Holland, 
the  preparation  is  on  a  large  scale. 

The  basis  of  all  liqueurs  is  a  very  highly  rectified  and  pure  alcohol  Tlie 
vegetable  materials  used  in  the  liqueurs  may  be  classified  under  three  heads  : — In 
the  first  place,  such  vegetable  substances  as  contain  essential  oils  and  are 
for  that  reason  only,  carraway,  aniseed,  juniper-berries,  mint,  lemon-peel, 
l^lossom,  and  bitter  almonds.  These  substances,  previously  bruised  or  cut  up, 
digested  with  alcohol,  the  mixture  being  next  distilled,  or,  as  is  more  generally  the 
case,  alcoholic  solutions  of  the  essential  oils  are  employed  and  the  pr^azatioa 
performed  in  the  cold.  To  the  second  class  belong  such  vegetable  substances  as  sre 
used  for  the  sake  of  their  essential  oil  and  for  their  aromatic  bitter  sabsUneca. 
chiefly  roots,  such  as  sweet  calamus,  gentian,  ginger,  orange-peel,  unripe  bitter 
Curaf  oa  apples  (a  peculiar  kind  of  orange),  wormwood,  cloves,  cinnamon,  vanilla  (the 
pod  of  an  orchidaceous  plant  originally  brought  from  Mexico).  These  substaiioei 
having  been  bruised  are  digested  with  alcohol  either  at  the  ordinary  temperature  of 
the  air  or  at  50"*  to  60^,  the  result  being  the  formation  of  what  is  termed  a  tincture. 
To  the  thii'd  class  belong  fruits,  such  as  cherries,  pine-apples,  strawberries,  laap- 
berries,  the  juice  of  which  is  obtained  by  pressure,  passed  through  a  sieve,  and 
mixed  with  alcohol  and  sugar  or  syrup,  viz.,  a  solution  of  4  lbs.  of  refined  loaf-sugsr 
in  4  litres  of  water.  The  liqueurs  generally  contain  from  46  to  50  per  cent  of  alcohoL 
It  is  customary  to  colour  the  liqueurs  red  with  santal-wood,  cochineal,  aniline  red, 
or  with  the  Coccus  polonicus,  as  is  the  case  with  the  celebrated  Alkermes  de  flrense. 


RESINS.  483 

tt  liqueur  made  at  Florence ;   yellow  with  saffiron,  tnrmeric,  or  marigold  flowers 
(Calendula) ;  green  by  mixing  yellow  and  blue ;  blue  witli  tincture  of  indigo ;  violet 
with  aniline  yiolet;  while  in  many  cases  caramel  is  used  to  impart  a  brown  colour. 
The  80-called  crimes  contain  for  every  litre  of  liquid  about  1  lb.  of  sugar  or  a  corre- 
sponding quantity  of  glycerine.    As  an  instance  of  the  composition  of  a  liqueur, 
Maraschino  consists  of  4  litres  of  raspberry  water,  i|  litres  orange-blossom  water, 
li  litres  kirschwasser  (a  Swiss  preparation — ^from  cherries  fermented  and  distilled — a 
strong  spiritnous  liquid  which  contains  hydrocyanic  acid) ,  18  lbs.  of  sugar,  and  9  litres  of 
alcohol  at  89  to  90  per  cent    Liqueurs  are  very  similar  to  crimes  j  but  contains  less 
sugar.    English  bitter  contains  5  parts  of  fiavedo  corticum  aurantiorum  (outer  rind 
of  dried  orange  peel),  6  parts  of  cinchona  bark,  6  parts  of  gentian,  8  parts  of  Carduus 
benedict,  8  parts  of  centaury,  8  parts  of  wormwood,  4  of  orris  root  digested  with 
54  litres  of  alcohol  at  50  per  cent,  while  after  filtration  12  lbs.  of  sugar  are  added. 
Cherry  ratafia : — 20  litres  of  cherry  juice,  20  litres  of  alcohol  at  85  per  cent,  30  lbs. 
sugar,  and  usually  4  to  8  litres  of  bitter  almond  water.    Peppermint : — 2k  litres  of 
essential  oil  of  peppermint  dissolved  in  i  litre  of  alcohol  at  80  per  cent ;  this  solution 
is  poured  into  54  litres  of  alcohol  at  72  per  cent  sweetened  with  60  lbs.  of  sugar 
previously  dissolved  in  26  litres  of  water,  and  coloured  with  either  tincture  of  indigo 
or  turmeric. 

ft 

bmiu.  By  the  action  of  the  oxygen  of  the  air  most  of  the  essential  oils  are 
gradually  thickened,  and  at  length  converted  into  a  substance  termed  resin.  Kesins 
are  frequently  met  with  in  the  vegetable  kingdom;  in  some  instances,  as  with 
coniferous  trees,  resin  flows  spontaneously  from  the  wood  in  combination  with  sii 
essential  oil,  so-called  Venice  turpentine,  which  hardens  by  exposure  to  air.  Some 
resins  are  extracted  from  vegetable  matter  by  means  of  alcohol,  this  solution  being 
either  precipitated  with  water  or  evaporated  to  dryness.  Kesins  are  either  soft,  and 
are  then  termed  balsams,  chiefly  solutions  of  resin  in  essential  oils,  or  hard.  To  the 
former  belong  Venice  turpentine,  Canada  balsam,  balsam  of  Peru,  Copaiva  balsam, 
Ac. ;  to  the  latter,  amber  (a  fossil  resin),  anime,  copal,  gum  dammar,  mastic,  shellac, 
asphalte.  The  gum  resins  are  obtained  from  incisions  made  in  certaiu  kinds 
of  plants,  the  milky  juice  of  which  hardens  by  exposxtre  to  air;  these  substances 
are  partly  soluble  in  water,  and  yield  with  it  in  many  instances  an  emulsion  ;  for 
instance,  assafoetida,  gum  gutti,  &c.  Many  gum  resins  possess  a  very  strong  odour 
and  contain  essential  oils.  Although  it  is  customary  to  treat  of  caoutchouc  and 
gntta-percha  under  the  head  of  resins,  these  substances  are  not  related  to  resins  at 
all,  but  belong  to  a  separate  class  of  bodies,  among  which,  according  to  Dr.  G.  J. 
Mulder's  researches,  the  so-called  drying  oils  must  be  enumerated. 

^tt^t^y^  Sealing-wax  of  modem  time  (for  mediaeval  sealing-wsx  was  really 
a  mixture  of  wax  with  Venice  turpentine  and  colouring  matter)  is  prepared  from 
shellac,  to  which  some  turpentine  is  added  in  order  to  promote  fusibility  and 
prevent  brittleness.  Bed  sealing-wax  and  bright  coloured  wax  are  made  of  a 
Teiy  pale,  sometimes  even  purposely  bleached,  shellac,  while  black  and  dark 
coloured  sealing-wax  are  made  of  more  deeply  coloured  shellac.  In  addition  to 
shellac  and  turpentine,  sealing-wax  contains  earthy  matter,  added  not  only  for  the 
purpose  of  increasing  the  weight,  but  also  for  preventing  the  too  rapid  fusion 
of  the  mass;  chalk,  magnesia,  plaster  of  Paris,  zinc-white,  sulphate  of  bar3rta, 
kaolin,  finely -divided  silica,  are  employed  for  this  purpose.  Red  sealing-wax  in 
prepared  by  melting  together  in  an  iron  pan  placed  on  a  charcoal  fire  4  parts  of 

2  12 


1 


a. 

3- 

4- 

5- 

620 

550 

700 

600 

680 

600 

540 

600 

200 

— 

— 

-  ■ 

100 

380 

300 

300 

220 

340 

300 

300 

— 

— 

20 

25 

4S4  CHEMICAL  TECHNOLOGY. 

shellac,  I  part  of  Venice  turpentine,  and  3  parts  of  cinnabar  (vermillion), 
being  taken  to  stir  the  mixture  constantly.    Ordinaiy  red  sealing-wax  is  often 

composed  of: — 

z. 

oneuac  •••     •••     •••    •••     •••    •••  55 

Turpentine 740 

Chalk  or  magnesia      300 

Gypsum  or  zinc- white        4  200 

Baryta  white       — 

Vennillion    130 

Oil  of  turpentine  •••    •r^    — 

The  cooled  but  still  soft  mass  is  either  rolled  on  a  slab  of  marble  and  shi^ed  into 
sticks,  or  the  fluid  mass  is  run  into  brass  moulds.    Perfumed  sealing-wax  contains 
either  benzoin  resin,  storax,  or  balsam  of  Peru.    The  various  colours  are  imparted  by 
cobalt  ultramarine  (cobalt  blue),  chromate  of  lead,  bone-black,  &c.    Marbled  sealing- 
wax  is  made  by  mixing  variously  coloured  sealing-wax  together.    Inferior  kinds  of 
sealing-wax — ^parcel-wax — are  coloured  with  red  oxide  of  iron,  while  instead  of 
shellac  ordinary  resin  is  used  with  gypsum  or  chalk.    New  Zealand  resin,  the 
produce  of  the  Xantharrhoea  luuiilU,  is  now  frequently  used  instead  of  shellac. 
Aiptaii*.    This  material  sometimes  known  as  bitumen,  is  a  black,  glossy,  brittle 
resin,  probably  formed  by  the  gradual  oxidation  of  petroleum  oil;  it  occurs  veiy 
largely  on  the  island  of  Trinidad,  on  the  northern  coast  of  S.  America,  at  the  month 
of  the  Orinoco,  on  the  water  of  the  Dead  Sea  (anciently  Laeui  Aspkaltitet),  and 
in  some  other  localties,  viz.  France,  Seyssel,  Departement  de  TAin,  a  limestone  con- 
taining 18  per  cent  of  asphalt.     By  boiling  this  limestone,  previously  broken  up 
into  small  lumps,  with  water,  there  is  obtained  an  asphalte,  7  parts  of  which  are 
mixed  with  90  parts  of  native  asphalte  limestone.     The  materials  are  ground  up 
together  and  are  employed  for  paving  purposes,  being  compressed  with  heavy  and 
highly  heated  irons.    Asphalte  also  occurs  at  Val  de  Travers,  Switzerland ;  linuner, 
Hanover;   Lobsann,  Lower  Alsace;    and  in  the  Northern  Tyrol.     Asphalte,  or 
bitumen,  is  somewhat  soluble  in  alcohol,  readily  so  in  Persian  naphtha,  oil  of  turpen- 
tine, benzol,  and  benzoline.    It  is  used  in  varnish  making  (iron  varnish),  in  engra- 
ving copper  and  steel,  as  an  etching  ground,  and  as  an  oil  paint    Asphalte  mixed 
wiUi  sand,  lime,  or  limestone,  is  largely  used  for  paving  purposes,  being  durable  and 
somewhat  elastic ;  it  is  employed  for  this  purpose  either  in  a  pasty  or  semi-fused 
state,  or  in  powder.    Instead  of  native  asphalte,  Busse's  terresin,  a  mixture  of  coal- 
tar,  lime,  and  sulphur  is  sometimes  used,  as  well  as  coal-tar  asphalte,  obtained  from 
gas  works.    The  residue  of  the  distillation  of  coal-tar  is  often  employed  instead  of 
asphalte,  and  pebbles  mingled  with  coal-tar  are  now  used  to  form  excellent  footpaths 
in  some  parts  of  the  metropolis. 

oiMMMhMus.  Elastic  gum  or  india-rubber,  is  derived  from  the  the  milky  joioe  of  a 
series  of  plants,  occurring  also  in  opium ;  but  the  commercial  article  is  obtained 
from  the  milky  juice  of  various  trees  belonging  to  the  natural  orders  of  the  Urtieem, 
EuphorUacea,  Apocynde.  Among  the  trees  which  yield  caoutchouc  in  large  quantitf 
are  the  Siphonia  cahueu,  in  South  America,  and  the  East  Indian,  Ureecla  dastiea. 
Fieus  eUutica,  F.  religiosa,  F.  indiea,  also  yield  caoutchouc.  It  is  obtained  by 
.making  incisiofts  in  the  tree  and  collecting  the  exuding  juice  in  vessels  of  dried  day. 


INDIA-RUBBER.  485 

The  juice  is  solidified  by  the  application  of  fire  or  by  exposure  to  the  sun's  rays ;  the 
variety  known  as  lard  gum  is  usually  dried  by  exposure  to  the  sun.  Perfectly  pure 
caoutchouc  is  a  white,  and  in  thin  sheets  semi-transparent,  substance ;  its  texture  is 
hot  fibrous ;  it  is  perfectly  elastic,  becoming  turbid  and  fibrous  when  strongly 
stretched.  Excessive  cold  renders  it  hard  but  not  brittle.  The  specific  gravity  of 
caoutchouc  is  0*925.  Although  hot  water  and  steam  render  caoutchouc  soft,  it  is  not 
further  acted  upon  by  them.  It  is  insoluble  in  alcohol,  not  acted  upon  by  dilute 
acids  or  strong  alkalies,  while  for  a  very  long  time  it  resists  the  action  of  chlorine. 
Strong  sulphuric  and  nitric  acids  decompose  india-rubber,  and  when  red  fuming 
nitric  acid  is  employed  a  violent  combustion  ensues.  If  when  strongly  stretched 
india-rubber  is  placed  in  cold  water  for  a  few  minutes  it  temporarily  loses  its 
elasticity,  which  it  regains  by  being  immersed  for  a  few  minutes  in  water  at  45°.  By 
exposure  to  a  gentie  heat  caoutchouc  becomes  supple,  and  finally  melts  at  200  ,  with 
pcurtial  decomposition,  forming  a  viscous  mass  which  does  not  again  become  solid  on 
cooling.  When  caoutchouc  is  ignited  in  contact  with  air  it  bums  with  a  sooty  flame. 
Of  all  substances  with  which  we  are  acquainted  none  would  be  better  suited  to  gad 
manufacture  than  caoutchouc,  which,  accor^ling  to  experiments  made  many  years  ago 
at  Utrecht,  yields  at  red  heat  rather  more  than  30,000  cubic  feet  of  gas  to  the  ton,  the 
gas  being  quite  free  from  sulphur  and  ammonia  compounds,  and  its  illuminating 
power  very  superior  to  that  of  the  best  oil  gas.  Unfortunately  caoutchouc  is  much 
too  high  priced  for  this  application.  Caoutchouc  may  be  kneaded  with  sulphur 
and  otiier  substances  by  the  aid  of  heat,  becoming  converted  into  what  is  known  as 
vulcanised  india-rubber,  vulcanite,  ebonite,  &c.  When  caoutchouc  is  submitted  to 
dry  distillation,  at  much  below  red  heat,  it  yields  only  oily  fluids,  consisting  of 
carbon  and  hydrogen  (caoutchen,  heveen,  &c.),  which  are  par  excellence  solvents  for 
caoutchouc.  Caoutchouc  itself  contains  only  carbon  and  hydrogen,  its  formula  being 
C4H7  (in  100 parts :  875  carbon  and  12*5  hydrogen) ;  probably,  however,  caoutchouo 
is  a  more  complex  mixture  of  various  hydrocarbons. 
soiTeats  of  CMntehone.  '  ludia-rubber  is  soluble  in  alcohol-free  ether,  in  the  oils 
(empyreumatic)  of  caoutchouc,  in  Persian  naphtha,  oil  of  turpentine,  sulphide  of 
carbon,  and  in  chloroform.  Industrially  the  etiiereal  solution  of  caoutchouo  is 
useless,  because  it  contains  hardly  more  than  a  trace  of  that  substance.  As  regards 
oil  of  turpentine,  it  dissolves  caoutchouc  only  when  the  oil  is  very  pure  and  with  the 
application  of  heat ;  the  ordinary  oil  of  turpentine  of  commerce  causes  india-rubber 
to  swell  rather  than  to  become  dissolved.  In  order  to  prevent  the  viscosity  of  the 
india-rubber  when  evaporated  from  this  solution,  i  part  of  caoutchouc  is  worked  up 
with  1 1  parts  of  turpentine  into  a  thin  paste,  to  which  is  added  k  part  of  a  hot  and 
concentrated  solution  of  sulphuret  of  potassium  (K2S5)  in  water ;  the  yellow  liquid 
formed  leaves  the  caoutchouc  perfectiy  elastic  and  without  any  viscosity.  The  solu- 
tions of  caoutchouc  in  coal-tar  naphtha  and  benzoline  are  most  suited  to  unite  pieces 
of  caoutchouc,  but  the  odour  of  the  solvents  is  perceptible  for  a  long  time.  As 
chloroform  is  too  expensive  for  common  use,  sulphide  of  carbon  is  the  most  usual 
and  also  the  best  solvent  for  caoutchouc.  This  solution,  owing  to  the  volatility  of  the 
menstruum,  soon  dries,  leaving  the  caoutchouc  in  its  natural  state.  When  alcohol  is 
mixed  with  sulphide  of  carbon  the  latter  does  not  any  longer  dissolve  tiie  caoutchouc, 
but  simply  softens  it  and  renders  it  capable  of  being  more  readily  vulcanised. 
Alcohol  precipitates  solutions  of  caoutchouc  and  gutta-percha. 


486  CHEMICAL  TECHNOLOGY. 

^''SSS^BSbe?."**"      India-rubber  is  used  to  dean  paper,  rub  out  black-lead  peneil 


marks,  for  making  waterproof  fiBibrics  (macintosh),  rubber  sponge,  tubing,  elastic 
lutes,  &c. 

YuinniB«d  CMatehoQc  When  csoutchouc  is  iuunersed  for  some  time  in  molteii  snlphiir 
it  absorbs  the  latter,  and  becomes  converted  into  a  yellow,  very  elastic  mass.  Hm 
properties  of  vulcanised  india-rubber  are :  elasticity  even  at  low  temperatures,  while 
ordinary  india-rubber  hardens  at  3°.  Vulcanised  india-rubber  is  insoluble  in  the  fl<d- 
vents  of  caoutchouc.  It  resists  compression  to  a  very  great  extent ;  hence  its  use 
instead  of  steel  springs  on  the  tramway  cars.  According  to  the  old  method 
caoutchouc  was  vulcanised  by  being  placed  for  some  ten  to  fifteen  minutee  in 
thin  plates  in  molten  sulphur  heated  to  120**,  the  weight  of  the  caoutchouc  increaaiBg 
10  to  15  per  cent.  The  material  was  subsequently  mechanically  treated  by  pressure, 
and  tlien  heated  to  150°.  In  order  to  prevent  efflorescence  of  the  sulphur* 
caoutchouc  is  sometimes  heated  to  120'',  and  then  kneaded,  by  the  aid  of  powexfol 
machinery,  with  either  kermes  (Sb2S3),  or  a  mixture  of  sulphur  and  sulphuret  of 
arsenic.  At  the  present  day  Parkes's  metliod  is  generally  adopted ;  the  caoutchouc  is 
simply  immersed  in  a  mixture  of  40  parts  of  sulphide  of  carbon  and  i  part  of 
chloride  of  sulphur ;  it  is  next  placed  in  a  room  heated  to  21%  and  when  all  the  sul- 
phide of  carbon  has  been  volatilised,  the  process  is  in  so  fiar  complete  that  it  is  only 
requisite  to  boil  the  material  in  a  solution  of  500  grms.  of  caustic  potassa  to  10  litras 
of  water,  the  vulcanised  caoutchouc  being  next  washed  to  remove  excess  of  alkalL 
Becently  (1870)  Humphrey  has  introduced  the  use  of  petroleum  ether  (benzoline) 
instead  of  sulphide  of  carbon,  as  the  former  fluid  dissolves  chloride  of  sulphur 
readily.  H.  Gaultier  de  Claubry  (i860)  vulcanises  caoutchouc  by  the  aid  of 
bleaching-powder  and  flowers  of  sulphur.  This  mixture  produces  chloride  of 
sulphur,  and  the  caoutchouc  treated  by  it  contains  some  chloride  of  calcium. 
Neither  this  process  nor  that  of  G6rard — the  use  of  a  solution  of  pentasulphide  of 
potassium  of  25^  to  30**  B.,  aided  by  a  temperature  of  150**,  and  a  pressure  of 
5  atmospheres  or  75  lbs.  to  the  square  inch — are  practically  available  on  the 
large  scale.  Articles  of  vulcanised  india-rubber  are  made  of  ordinary  caoutchouc 
and  then  vulcanised.  The  uses  of  vulcanised  india-rubber  are  so  many  and  so 
generally  known  that  it  is  hardly  necessaiy  to  enumerate  them. 

In  the  year  1852  Goodyear  discovered  a  process  by  which  caoutchouc  is  rendered 
hard  and  woodlike,  being  then  termed  vulcanite  or  ebonite.  This  substance  exhibits 
a  black  or  brown  colour,  and  is  largely  used  for  making  combs,  imitalaon  jet 
ornaments,  stethescopes,  and  a  variety  of  articles.  The  preparation  of  ebonite  differs 
from  that  of  vulcanite  only  in  the  introduction  of  a  larger  amount  of  sulphur 
(30  to  60  per  cent),  at  a  higher  temperature,  with  the  addition  of  other  substances, 
shellac,  gutta-percha,  asphalte,  chalk,  sulphate  of  baryta,  pipe-day,  sulphurets  of 
zinc,  antimony,  or  copper,  &c.  Ebonite  is  capable  of  taking  a  high  polish;  does 
not,  as  is  the  case  with  horn,  become  rough  when  cleaned  with  hot  water,  and  is  to 
some  extent  elastic.  Vulcanised  caoutchouc  mixed  with  sand,  emery,  and  quarts, 
is  used  for  sharpening  agricultural  implements,  scythes,  sickles,  &c. 

.  PiDdQctiaii  and  conramption      The  total  quantity  of  caoutchouc  produced  in  1870  amounted  to 
of  caoutehoue.  120,000  cwts.,  of  which  the  island  of  Java  yielded  60,000  ewta. 

The  consumption  is  fully  equal  to  the  supply,  the  largest  quantity  being  used  in  North 
America,  35,000  cwts. 

onttft-pwduL      Plastic  gum,  gntta  or  getah-peroha,  gettannia  gum,  tuban  gam,  is  a 
substance  in  many  respects  similar  to  caoutchouc;  it  is  the  inspissated  juioe  of  the 


QUTTA-PEBCHA.  487 

Isonandra  ffutUty  a  tree  growing  in  MalaeM,  Borneo,  Singapore,  Java,  Madura,  and 
adjacent  oonntries. 

Gutta-percha  was  at  first  obtained  by  felling  the  trees  and  collecting  the  exuding 
juice,  either  in  suitable  vessels  or  in  shallow  pits  dug  in  the  soil,  or  in  baskets  made 
from  banyan  leaves,  the  juice  being  left  to  coagulate  under  the  action  of  the  sun* 
More  recently  deep  incisions  are  made  in  the  trees  and  the  exuding  juice  collected. 
The  lumps  of  solid  gutta-percha  thus  obtained  are  united  by  softening  in  hot  water 
and  by  pressure.  The  raw  gutta-percha  of  commerce  is  a  dry,  red,  or  marbled  mass, 
not  unlike  leather  cuttings  which  have  been  pressed  together ;  the  raw  material  con- 
tains as  impurities  some  sand,  small  pieces  of  wood  and  bark,  and  sometimes  other 
inspissated  vegetable  juices  of  less  value  than  gutta-percha.  The  name  gutta- 
percha really  means  Sumatra  gum,  this  island  being  known  in  Malay  language  as 
Pnlo-percha.  When  perfectly  pure  gutta-percha  is  quite  white,  its  ordinary  brown 
colour  being  due  to  an  acid  insoluble  in  water,  which  is  present,  partly  free,  partly  as 
insoluble  salts  (of  magnesia,  ammonia,  potash,  and  protoxide  of  manganese), 
of  apocrenic  acid ;  but  in  addition  there  is  a  small  quantity  of  organic  colouring 
matter.  Gutta-percha  is  a  mixture  of  several  oxygen-containing  resins,  which 
appear  to  be  tlie  products  of  the  oxidation  of  a  hydrocarbon,  the  formula  of  which  is 
CaoHfio.  Payen  found  in  gutta-perclia  the  following  substances : — 75  to  80  per  cent 
•of  pure  gutta-percha;  14  to  16  per  cent  of  a  white  crystalline  resin  termed  alban : 
and  from  4  to  6  per  cent  of  an  amorphous  yellow  resin  named  fluavil.  Previously  to 
being  used  gutta-percha  is  cleansed  from  dirt  by  a  mechanical  process  of  kneading 
in  warm  water,  being  then  usually  rolled  into  thick  plates  or  sheets.  The  purified 
material  exliibits  a  chocolate-brown  colour,  is  not  transparent  unless  first  reduced  to 
sheets  as  thin  as  paper,  when  the  gutta-percha  is  in  ti*ansparency  equal  to  horn.  At 
the  ordinary  temperature  of  the  air  gutta-perclia  is  very  tough,  stifif,  not  very  elastic 
nor  ductile.  Every  square  inch  of  a  strap  of  gutta-percha,  if  of  good  quality  and  as 
homogeneous  as  possible,  can  sustain  a  strain  of  1872  kilos,  without  breaking.  Its 
sp.  gr.  =r  0*979.  At  50*^  it  becomes  soft,  and  at  70°  to  80°  it  is  so  soft  as  to  be  very 
readily  moulded,  while  two  pieces  pressed  together  at  this  temperature  become 
perfectly  joined.  By  the  aid  of  heat  gutta-percha  can  be  rolled  into  sheets,  drawn 
into  wire,  and  kneaded  into  a  homogeneous  mass  with  caoutchouc. 

Boivcntoof  oatu-Perehm.  Gutta-percha  is  iusoluble  in  water,  alcohol,  dilute  acids,  and 
alkalies ;  it  is  soluble  in  warm  oil  of  turpentine,  sulphide  of  carbon,  chloroform,  coal- 
tar  oil,  caoutchouc  oil,  and  in  the  somewhat  similar  oil  obtained  by  the  dry  distilla- 
tioh  of  gutta-percha.  Ether  and  some  of  the  essential  oils  render  gutta-percha  pasty. 
Afl  already  stated  this  substance  becomes  soft  in  hot  water,  absorbing  a  small  quantity, 
'  which  is  only  very  slowly  driven  off:  Dry  gutta-percha  is  a  very  good  insulating 
material  for  electricity. 

n«M  of  antta-Poehs.  The  natural  properties  of  this  substance  indicate  its  use  as  a  sub- 
stitute for  leather,  papier  mach^,  cardboard,  wood,  millboard,  paper,  metal,  Ac.,  in  all 
cases  not  exposed  to  the  action  of  heat,  and  where  a  substance  is  desired  resisting  water, 
alcohol,  dilute  acids,  and  alkalies.  The  raw  material,  previously  to  being  moulded  into 
shape,  is  purified  and  kneaded  by  means  of  powerful  machinery  and  with  the  assistance 
of  hot  water  (some  soda  or  bleaching-powder  solution  being  added),  the  aim  being 
the  removal  of  such  impurities  as  are  only  mechanically  mixed  with  the  gutta-peroha  as 
well  as  the  removal  of  some  of  the  colouring  matter,  while  a  more  homogeneous  mass  is 
produced.  The  purified  substance  is  next  submitted  to  the  action  of  kneading  machinery 
similar  to  that  in  use  for  working  up  caoutchouc,  while  it  is  rolled  out  into  plates  of  some 
3  centimetres  in  thickness.  Gutta-percha  is  moulded  into  tubes  by  the  aid  of  machinery 
similar  to  that  employed  for  making  lead  and  block-tin  tubing.  Many  objects  are  made 
from  gutta-percha  by  pressing  it  while  soft  into  wooden  or  metal  moulds.    By  the  use  of 


483  CHEMICAL  TECHNOLOGY. 

>  solution  of  gatt&-peroha  in  benzol,  it  may  be  glned  to  leather  and  similar  sabetaoccL 
It  is  almost  impossible  to  enumerate  the  yarions  uses  of  gntta-percha.  It  ia  emplojvi 
.for  straps  for  machinery  instead  of  leather,  tubes  for  oonveying  water,  pumps,  pails,  sar- 
-gical  instruments,  ornamental  objects  of  yarious  kinds,  for  covering  telegraph  ynres,  4e. 
Unlike  pure  caoutchouc  gutta-percha  becomes  gradually  deteriorated  by  exposure  to  the 
atmosphere,  so  that  it  can  be  even  readily  ground  to  powder. 
MUtnxe  of  ontte-Peraha  Frequently  a  mixture  of  z  part  of  gutta-percha  and  2  parts 
andoaoutdumo.  of  caoutchouc  is  employed.  Articles  made  of  this  eompound 
possess  the  properties  of  both  substances,  and  may  be  vulcanised  equally  as  wt^  is 
gutta-percha  alone.  A  mixture  of  equal  parts  of  caoutchouc,  gutta-percha,  and  saliihaz^ 
heated  for  several  hours  to  120°,  obtains  properties  similar  to  those  of  heme  andhoro. 
Sometimes  gypsum,  resin,  and  lead  compounds  are  added  to  this  mixture,  wliioh  is  thea 
used  for  making  knife  hafte,  buttons,  &q, 

vandaiMs.  By  voTmsh  we  understand  a  liquid  of  an  oily  or  resinons  Batare 
employed  for  coating  various  objects,  the  thin  film  becoming  dry  and  hard,  thtm 
protecting  the  object  on  which  it  is  laid  from  the  action  of  air  and  water,  .and 
at  the  same  time  imparting  a  glossy  and  shining  sur£fice.    We  disting^nigh  oil  and 

onvaniihM.  Spirit  varnishes.  Oil  varnishes  are  usually  prepared  from  linseed  oil, 
but  sometimes,  especially  for  artist's  purposes,  poppy  seed  and  walnut  oil  (so-called 
drying  oils)  are  used.  Linseed  oil  (raw)  becomes  slowly  converted  by  the  action  of 
the  air  into  a  tough,  elastic,  semi-transparent  mass ;  but  this  property  is  possesBed  in 
a  far  higher  degree  by  the  so-called  boiled  oil,  that  is  to  say — an  oil  which  has  beea 
brought  by  the  action  of  heat  and  of  oxidising  materials  into  a  state  of  greater 
activity,  in  fact — ^into  a  state  of  incipient  slow  oxidation,  the  result  of  which  is  the 
formation  of  the  substance  termed  by  Dr.  G.  J.  Mulder  *  linoxine,  which  in  many  of 
its  properties  corresponds  to  caoutchouc.  The  drying  of  oil  varnishes  is  not  theme- 
fore  due  to  evaporation  (leaving,  as  is  the  case  with  alcohol  yamishes,  a  coherent  fifaa 
of  resin),  but  to  the  oxidising  action  of  the  oxygen  of  the  air,  whereby  a  coherent 
film  of  linoxine  is  formed.  Linseed  oil  (raw)  is  converted  into  what  is  termed 
varnish  by  heating  the  oil  with  certain  substances  which  more  or  less  readily  give  off 
oxygen,  while  these  substances  also  act  upon  the  elaine,  palmitine,  and  myiiatine  of 
the  linseed  oil.  The  greater  part  of  the  linseed  and  other  drying  oils  is  1ini%Uing^ 
3(032H3703),C6H503,  which  by  slow  oxidation  becomes  linoxine  =  G^sH^Ou,  bj 
the  action  of  allodies  converted  into  linoxic  acid,  HO,032HasOg.  The  substances 
with  which  raw  linseed  oil  is  boiled  are  litharge,  oxide  of  zinc,  and  peroxide  of 
ganese.  It  is  certainly  preferable  to  carry  this  operation  into  effect  upon  the 
bath,  or  at  least  with  vessels  provided  with  steam  jackets.  The  oxides  are  employed 
in  coarse  powders,  which  are  suspended  in  a  linen  bag  in  the  oil.  In  practice  i  part 
of  oxide  of  zinc  or  litharge  is  taken  to  16  parts  of  raw  oil ;  and  of  the  manganese 
I  part  to  10  of  oil ;  the  oxides  become  partially  dissolved  in  the  oil,  while  thejr  aid 
in  converting  the  palmitine,  &c.  (not  linoleine),  into  plaster  (lead  or  zinc  soap). 
Boiled  linseed  oil  usually  contains  from  2*5  to  3  per  cent  of  litharge  diasolved. 
Neither  the  addition  of  sulphate  of  zinc  nor  such  absurdly  added  substances  as 
onions,  bread  crust,  or  beet-root  have  any  result  whatever.  Linseed  oil  intended  to 
be  mixed  with  zinc-white  should  not  be  boiled  with  litharge,  but  with  peroxide 
of  manganese.  The  lower  the  temperature  at  which  linseed  oil  is  boiled  the  brighter 
its  colour.  Mulder  found  that  when  raw  linseed  oil,  especially  if  old,  was  kept  lor 
12  to  18  hours  at  a  temperature  of  Ioo^  it  acquired  the  property  of  boiled  dL 
Sometimes  after  boiling  linseed  oil  is  bleached  by  exposing  it  in  shallow  trays 

'*  This  author  published  some  years  ago  in  the  Dutch  language  a  highly  interesting  and 
valuable  work— practicaU^  as  weU  as  scientifioally— on  the  drying-oils. 


VARNISHES.  4^ 

lo  eetitims.  deep,  best  made  of  sheet  lead,  covered  with  sheets  of  glass,  to  the  action 

of  strong  summer  sunlight.     Liebig's  recipe  for  making  a  bright  vamish  is  the 

following :-— To  lo  kilos,  of  raw  linseed  oil  are  added  300  grms.  of  finely  pulverised 

litharge,  after  which  there  is  added  a  solution  of  600  grms.  of  acetate  of  lead ;  the 

mixture  is  vigorously  stirred,  and  after  the  subsidence  of  the  materials  the  clear 

vamish  is  ready  for  use.    Borate  of  manganese  is,  according  to  Barruel  and  Jean, 

an  excellent  so-called  siccative  (dryer;  when  added  to  raw  linseed  oil,  z  part  to  1000 

of  oil.    Mulder's  experiments  confirm  this  statement  in  eveiy  respect. 

ooid  aiM.  This  Is  used  in  gilding  for  fixing  gold  leaf  on  wood,  paper,  Ao.,  and  consists 
jof  a  solution  of  linseed  oil  and  lead  plaster  in  oil  of  turpentine,  prepared  by  first 
saponifying  linseed  oil  with  caustic  soda  or  potassa,  and  precipitating  the  aqueous 
aolution  of  the  soap  with  a  solution  of  acetate  of  lead,  the  iMd  soap  thus  fonned  being 
next  dissolved  in  oil  of  turpentine. 

PriBtiBc  Ink.      This  is,  when  genuine  and  prepared  from  good  linseed  or  walnut  oil, 

anliydiide  of  linoleic  acid,  GsaH^Oj,  mixed  with  vezy  finely  divided  lamp-black,  and 

obtained  by  heating  raw  linseed  oil  for  several  hours,  at  a  high  temperature 

(315*^    to   360**),    whereby  the   fatty  constituents — glycerine,   palmitine,  Ac. — are 

•Tolatilised.     Usually  the  oil  is  heated  in  vessels  directly  exposed  to  the  action 

of  fire,  and  as  the  colour  of  the  ink  is  black,  a  deep  colour  of  the  residue  of  the 

heating  of  the  oil  is  not  of  much  consequence.    In  order  to  render  printing  ink  more 

rapidly  drying,  some  borate  of  manganese  may  be  heated  with  it  at  315**  for  some 

hours.  The  quantity  of  fine  lamp-black  (best  re-ignited  in  dose  vessels,  or  exhausted 

with  boiling  alcohol)  usually  added  to  printing  ink,  amounts  to  about  16  per  cent 

Soap  is  added  in  order  to  prevent  smearing  and  assist  in  obtaining  sharpness 

of  impression.    Coloured  printing  inks  are  obtained  by  adding  to  boiled  oil  red  or 

blue  or  other  pigments ;  for  red  vermillion  i^  used.    The  ink  used  in  lithography 

and  copper-plate  printing  is  made  thicker,  a  better  black  being  added. 

ouvamidMi.      The  so-called  fiit  or  oil  varnishes  are  solutions  of  resins  in  boiled  lin- 
aeed  oil  mixed  with  oil  of  turpentine,  benzol,  or  benzoline.    Amber,  copal,  anime» 
gum  dammar,  and  asphalte,  are  among  the  more  ordinary  resins  employed  for  this  pur- 
pose, the  varnishes  being  made  by  melting,  with  the  aid  of  gentle  heat,  the  amber^ 
copal,  Ac.,  to  which,  while  liquid,  boiling  linseed  oil  is  added.    The  cauldron  in 
which  this  operation  takes  place  should  only  be  two-thirds  filled ;  and  the  mixture  of 
oil  and  resin  kept  boiling  for  ten  minutes.    The  cauldron  having  been  removed  from 
.the  fire  its  contents  are  allowed  to  cool  down  to  140^,  when  the  oil  of  turpentine  is 
added.    The  quantities  by  weight  are  10  parts  copal  or  amber,  20  to  30  boiled 
linseed  oil,  25  to  30  oil  of  turpentine.     Black  asphalte  vamish  is  obtained  in  a 
similar  manner  by  treating  3  parts  of  asphalte,  4  of  boiled  linseed  oil,  and  15  to  18 
parts  of  oil  of  turpentine.    Dark  coloured  amber  vamish  is  not  prepared  from 
amber  but  from  the  residue  {amber  oolophoRium)  of  the  distillation  of  the  empy- 
reumatio  oil  of  amber  and  succinic  add  left  in  the  still  from  the  preparation  of 
succinic  acid.     These  varnishes  are  the  most  durable,  but  they  dry  slowly  and 
are  more  or  less  coloured. 

spidtvuniaii.  The  so-cslled  spirit  varnishes  are  solutions  of  certain  resins, 
viz.  sandarac,  mastic,  gumlao  (shellac),  anime  in  alcohol,  aceton,  wood  spirit, 
benzoline,  or  sulphide  of  carbon.  Oood  spirit  vamish  ought  to  dry  rapidly,  give  a 
glossy  surface,  adhere  strongly,  and  be  neither  brittle  nor  viscous.  As  shellac  is 
frequently  employed,  the  name  of  lac  vamish  is  sometimes  given  to  these  varnishes. 
The  spirit,  usually  methylated  spirit,  ought  to  be  Btrong,.aboat  93  per  cent    The 


490  CHEMICAL  TECHNOLOGY. 

Bolntion  of  tiie  resins  is  |>romoted  by  the  addition  of  one-third  of  their  ireigkt 
of  coarsely  powdered  glass  for  the  purpose  of  preventing  tlie  reainoiis  matter  caking 
together,  and  being  thus  to  some  extent  withdrawn  from  the  solvent  actiou  of 
the  alcohol.  In  order  to  render  the  coating  remaining  from  the  evaporatioa  of 
the  spirit  less  brittle,  Venice  turpentine  is  usually  added.  Sandarac  Tamisk 
is  obtained  by  dissolving  lo  parts  of  sandarac  and  i  of  Venice  turpentine  in  30  of 
spirit.  Shellac  varnish,  more  durable  than  the  former,  is  obtained  by  disBolving 
I  part  of  shellac  in  3  to  5  of  spirits.  French  polish  is  a  solution  of  uliftUac  in 
a  large  quantity  of  spirits,  and  when  this  polish  is  to  be  applied  to  white  wood,  tbe 
vamisli  is  bleached  by  filtration  over  animal  charcoal.  Copal  varnish,  fiar  Buperior 
to  the  foregoing,  is  made  by  first  melting  the  resin  at  as  gentle  a  heat  as  possiUe 
so  as  to  prevent  the  colouration  of  the  substance,  which  is  next  pulverised,  mixed 
with  sand,  treated  with  strong  alcohol  on  a  water  bath,  and  filtered.  A  solntion 
of  turpentine  or  elemi  resin  is  added  to  render  the  varnish  softer.  Ccdourless  copal 
varnish  is  obtained  by  pouring  over  6  kilos,  of  previously  pulverised  and  xoohea 
copal,  contained  in  a  vessel  which  may  be  closed,  6  kilos,  of  alcohol  at  98 
4  kilos,  of  oil  of  turpentine,  and  i  kUo.  of  ether ;  the  vessel  containing  this 
having  been  closed  is  gentiy  heated.    The  solution  is  clarified  by  decantelion. 

coiouwi  spixti  vatniahes.  Thcso  are  used  chiefly  for  the  purpose  of  coating  instmmeiiti, 
and  other  objects  of  brass  and  coloured  metallic  alloys,  so  as  to  prevent  the  aetiflB 
of  the  atmoi^here.  Such  varnishes  are  used  for  imparting  a  gold-colour  to 
base  metals ;  for  this  purpose  alcoholic  tinctures  of  gummi-gutta  and  dragon's  Uood, 
or  fnchsin,  picric  acid,  Martins  yellow,  and  coraUin,  are  separately  prepared  and 
added,  in  quantities  found  by  trial,  to  a  varnish  consisting  of  2  parts  of  seed  lac,  4  of 
sandarac,  4  of  elemi,  and  40  of  alcohol. 

Tttrpenttne  on  vanbhog.  Thcsc  are  prepared  in  the  same  manner  as  the  preeediag. 
They  dry  more  slowly,  but  are  less  brittie  and  more  durable.  Common  turpentine 
oil  varnish  is  obtained  by  dissolving  ordinary  resin  in  oil  of  turpentine ;  but  this 
varnish  is  liable  to  crack.  Copal  is  either  dissolved  in  oil  of  turpentine,  without  or 
after  having  been  melted ;  in  the  latter  case  the  varnish  being  coloured.  When  non- 
melted  copal  is  used  it  is  broken  into  small  lumps,  and  is  suspended  in  a  stout  canvas 
l)ag  over  the  surfiewe  of  the  oil  of  turpentine  contained  in  a  glass  flask  and  placed  on 
a  saiid  bath,  the  vapours  arising  from  the  oil  of  turpentine  gradually  dissolving  fliA 
copal.  Dammar  gum  resin  varnish  made  with  oil  of  turpentine  is  prepaied  hf 
drying  the  resin  at  a  gentie  heat  and  dissolving  it  in  three  to  four  times  its  weight  a^ 
oil  of  tupentine.  This  varnish,  though  colourless,  is  not  very  durable.  Green 
turpentine  oil  varnish  is  prepared  by  dissolving  sandarac  or  mastic  in  concentrated 
caustic  potash  solution,  diluting  with  water,  and  precipitating  with  acetate  of  coppeff 
the  dried  precipitate  being  dissolved  in  oil  of  turpentine. 

PoUaUng  the  Drt«d  varnUh.  In  order  to  Increase  the  gloss  of  varnished  surfaces,  especially 
on  metallic  objects  and  coaches,  carriages  and  woodwork  in  theatres,  ooneert-roomi, 
halls,  <&c.,  the  dry  surface  is  first  mbbed  over  with  soft  felt,  on  which  some  very  fine  pumiee- 
powder  is  laid,  and  is  next  polished  with  very  soft  woollen  tissue  on  which  some  oil  lod 
rotten-stone  is  placed,  the  oil  being  rubbed  off  with  starch-powder.  Instead  of  vanuflbei, 
solutions  of  collodion  (fulminating  cotton  in  alcohol  and  ether)  and  solutions  of  water- 
glass  are  sometimes  used ;  while  Puscher  recommends  a  solution  of  shellac  in  ammonis* 
largely  used  by  hatters. 

.  p«tt4nikofer'iiPit>oeMfor      l^^  order  to  remove  the  cracks  often  observed  in  old  piotures,  Vcn 

Restoring  Pictures.      Pettenkofer  has  suggested  exposure  to  the  vapour  of  idoohol  si  the 

ordinary  temperature  of  the  air,  the  picture  being  placed  in  an  air-tight  box,  at  the  bottom 

of  which  is  a  tray  containing  alcohol.    This  method  Has  been  tried,  but  not  only  has  it 


CEMENT.  491 

failed  in  many  eases,  but  some  piotves  have  been  aetuaUy  spoiled.  According  to 
I>r.  G.  J.  Mulder's  researches,  the  only  effective  preservative  of  pictures  is  complete 
exclusion  of  air.  He  suggests  that  pictures  should  be  well  varnished  on  the  painted  side 
as  well  as  on  the  back,  and  next  hermetically  covered  with  well-fitting  sheets  of  polished 
l^laBB  on  the  front,  and  some  substance  on  the  back  impermeable  to  air.  The  reid  cause 
of  the  nltimate  destruction  of  pictures  as  well  as  of  paint  is  the  gradual  but  continuous, 
yet  slow,  oxidation  of  the  linoxine,  resulting  in  the  crumbling  to  powder  of  the  pulverulent 
matters — pigments,  used  as  colours.  It  may  not  hare  be  out  of  place  to  state  that  one  of 
the  beet  solvents  of  linoxine  (dried  paint)  is  a  mixture  of  alcohol  and  chloroform,  which 
may  be  advantageously  used  to  remove  stains  of  paint,  and  also  of  waggon  and  carriage 
greaae  from  silk  and  woollen  tissues. 

CsMENTs,  Lutes,  and  Putty. 

OHMBii.  In  a  general  sense  we  understand  by  cement,  substances  or  mixtures 
which,  when  placed  in  a  pasty  state  between  the  surfaces  of  bodies  in  close  cantact, 
cause  them  to  adhere  solidly  after  the  drying  or  solidification  of  the  pasty  material. 
According  to  this  definition,  glue  and  paste  are  cements,  but  solder  is  not.  As  a 
universally  applicable  cement  cannot  be  met  witli,  it  is  clear  that  as  regards  any 
specific  cement  it  should  completely  answer  the  purpose  for  which  it  is  employed. 
The  substances  used  for  cement  are  very  various,  aad  are  of  course  adapted  to  the 
particular  objects  they  are  intended  to  imite.  There  are  numberless  receipts  for  the 
preparation  of  cements,  which  may  be  best  classified  by  stating  the  name  of  the  most 
essential  constituent.  Thus  we  have: — i.  Lime  cements.  2.  Oil  cements.  3.  Kesin 
and  sulphur  cement.  4.  Lron  cements.  5.  Starch,  or  paste.  6.  Cements  oMess 
consequence,  as,  for  instance,  water-glass  cement,  chloride  of  zinc  cement,  &c. 

uau  ooMiita.  Slakcd-limc  forms  with  casein,  white  of  eggs,  gum-arabic,  and  glue, 
mixtures  which  after  some  time  become  vexy  solid,  and  are  used  to  unite  wood, 
stone,  metal,  glass,  porcelain,  &c. 

Casein  cement  may  be  made  in  various  ways,  but  is  most  usually  prepared  by 

mixing  freshly^precipitated  casein,  obtained  by  acidifying  milk,  previously  freed  from 

whey  and  separately  reduced  to  powder,  with  freshly  slaked  lime.    As  this  mass 

hardens  very  rapidly,  it  should  be  used  immediately,  and  not  prepared  in  larger 

quantity  than  may  be  required.    Casein  dissolved  in  bicarbonate  of  potash  or  soda 

solution,  and  gently  evaporated  to  a  thick  consistency,  also  yields  a  good  cement. 

A  solution  of  casein  in  a  concentrated  aqueous  solution  of  borax  made  with  cold 

water  yields  a  clear  thick  solution,  which,  as  regards  adhesive  property,  fax  surpasses 

a  solution  of  gum-arabic.    A  solution  of  casein  in  silicate  of  soda  or  potash  is  an 

excellent  cement  for  glass  and  porcelain.    When  stone,  metal,  wood,  &c.,  are  to  be 

united,  or  when  the  cement  is  to  be  used  for  filling  up  small  cavities,  there  is  usually 

added  to  the  mixture  of  casein  and  lime  a  powder  made  of  i  kilo,  of  fresh  casein, 

z  Idlo.  of  quick-lime,  and  3  kilos,  of  hydraulic  mortar  or  lime.    According  to  Hannou 

partly  decayed  and  liquefied  gluten  yields  with  lime  a  cement  similar  to  that 

obtained  from  casein. 

oacnMBto.      The  main  and  essential  constituent  of  these  cements  is  a  drying  oil  in 

the  shape  of  an  oil  varnish  (boiled  linseed  oil).    Most  of  these  cements  resist  the 

action  of  water. 

Boiled  linseed  oil  and  fat  copal  varnish  may  be  used  as  cements  to  unite  glass  and 
porcelain,  but  are  seldom  so  employed  on  account  of  requiring  some  weeks  to  become 
dry.  Mixed  with  white-lead,  litharge,  or  minium  (red  lead),  the  cement  dries  more 
qsickly,  but  does  not  become  quite  hard  until  after  some  weeks.    When  a  larger 


491  CHEMICAL  TECBNOLOGY. 

qoantily  of  Uiis  cement,  or  rather  putter,  is  required,  it  is  frequently  made  of  baflel 
linseed  oil  with  a  mixture  of  lo  per  cent  of  litharge  and  90  per  cent  of  either  wasbed 
chalk  or  slaked  lime.  Zinc-white  is  sometimes  used  instead  of  litharge.  This  pottf 
is  frequently  wanned  hefore  use  in  order  to  render  it  softer ;  it  is  used  for  nnitisg 
stone,  brick,  &c.  A  mixture  of  2  parts  of  litharge,  i  of  slaked  lime,  and  i  of  dry  sand, 
made  into  a  uniform  paste  with  hot  and  boiled  linseed  oil,  has  been  used  by  Stephenson 
as  a  putty  to  be  placed  into  the  sockets  of  steam-pipes.  By  precipitating  a 
solution  of  soda-soap  with  altmi  solution  an  alumina  soap  insoluble  in  Wats'  is 
obtained,  which,  having  been  dissolved  in  warm  linseed  oil  varnish,  yields,  aocordiBg 
to  Varrentrap,  an  excellent  cement  for  uniting  stone.  Glaziers*  putty  is  a  mixture  of 
chalk  and  boiled  linseed  oil,  well  beaten  up  together.  When  this  putty  is  made  widi 
raw  linseed  oil  it  hardens  veiy  slowly ;  prepared  with  boiled  linseed  oil  it  may  be 
kept  soft  for  a  considerable  time  by  either  being  placed  under  water,  or  kept  ia 
bladders  like  lard,  or  tied  up  in  canvas  bags  previously  soaked  with  oil.  Aocoiding 
to  Hirzel,  a  mixture  of  litharge  and  glyceriae  forms  an  excellent  cement  and  readily 
hardening  lute,  which,  according  to  Pollack,  may  even  be  used  to  unite  iron  and  iroo. 
as  well  as  iron  and  stone. 

BMiaOMMnu.  Cemeuts  made  with  resin  as  the  main  constituent  are  often  used, 
because,  on  becoming  cold,  they  harden  at  once  and  possess  the  property  of  bezng 
waterproof;  on  the  other  hand,  these  resin  cements  will  not  endure  a  high  tempeia- 
txure  without  becoming  soft,  and  by  exposure  to  air  and  sunlight  they  become  so 
brittle  as  to  be  easily  pulverised. 

As  a  cement  for  glass  and  porcelain,  sandarac  and  mastic  are  sometimes  used, 
because  these  resins  are  readily  fusible  and  are  colourless.  They  are  applied  to  the 
surfaces  to  be  united  in  the  form  of  a  powder  put  on  with  a  small  hair-brush,  after 
which  the  object  is  heated  so  as  to  melt  the  resins,  the  pieces  to  be  joined  being 
pressed  together.  As  fiur  back  as  the  year  1828,  Lampadius  suggested  as  an  excel- 
lent cement  a  solution  of  i  part  of  amber  in  1*5  parts  of  sulpliide  of  carbon. 
Wlien  this  solution  is  painted  over  the  surfaces  to  be  united  and  immediately 
pressed  together,  the  joint  is  at  once  effected  owing  to  the  rapid  evaporation  of  the 
sulphide  of  carbon.  A  solution  of  mastic  in  sulphide  of  carbon  may  be  aimilariy 
used.  Shellac  alone  does  not  form  a  good  cement,  being  too  brittle  when  cold,  and 
contracting  too  much  after  having  been  melted :  the  addition  of  some  Venice  tQipeo- 
tine  and  earthy  powders  (see  Sealing-wax)  compensates  these  defects.  'While  wood 
cannot  be  joined  together  with  shellac,  it  is  firmly  and  readily  glued  by  coating  the 
pieces  to  be  joined  with  thick  shellac-varnish,  and  then  placing  between  the  two 
pieces  a  slip  of  muslin.  Resins  are  frequently  used  for  lining  water-dstems,  and  for 
rendering  terraces,  &c.,  waterproof.  Fitch,  colophonium,  asphalte,  mixed  with  lime, 
sulphur,  or  turpentine,  are  used  for  this  purpose,  the  object  of  the  various  additions 
being  to  obtain  a  greater  or  less  degree  of  hardness.  Jeffeiy's  marine  giue  ia 
prepared  by  dissolving  caoutchouc  in  twelve  times  its  weight  of  coal-tar  naphtha  and' 
adding  twice  the  weight  of  either  asphalte  or  shellac.  The  mixture  is  gently  heated 
to  render  it  uniform.  There  is  a  solid  and  a  fluid  marine  glue  in  the  trade ;  the 
former  is  used  for  glueing  wood  and  for  caulking,  the  latter,  obtained  simply  by  the 
use  of  a  larger  quantity  of  solvent,  is  used  as  a  varnish ;  both  kinds  are  insoluble  in 
Water,  are  not  acted  upon  by  change  of  temperature,  and  do  not  become  brittle.  By 
the  name  of  zeiodelite  is  understood  a  mixture  consisting  of  19  parts  of  snlphur  and 
42  of  powdered  glass  or  earthenware;    this  mixture  having  been  heated  to  the 


PASTE.  493 

meltmg-point  of  sulphnr,  maybe  used,  instead  of  hydraulic  cement,  for  tmiting  stones 
and  bricks.  R.  Bottger  prepares  this  cement  by  mixing  with  molten  sulphur  an 
eqaal  weight  of  infusoria  earth  to  which  some  graphite  is  added.  Under  the  name 
of  diatite  Merrick  prepares  a  mixture  of  shellac  and  finely  divided  silica. 

zraa  GeflMBt.  Among  the  very  many  recipes  given  for  tlie  preparation  of  this  cement, 
used  for  luting  the  sockets  and  spigots  or  flanges  of  cast-iron  pipes,  and  for  caulking 
the  seams  of  the  plates  of  steam-boilers,  we  quote  the  following  as  one  of  the  best: — 
A  mixture  of  2  parts  of  sal-ammoniac,  i  of  sulphur,  and  60  of  finely-pulverised  cast- 
iron  boxings  or  filings.  When  required  for  use,  this  mixture  is  made  into  a  paste 
with  water,  to  which  some  vinegar  or  dilute  sulphuric  acid  is  added.  The  parts  to 
be  joined  by  this  cement  should  be  free  from  fat,  oil,  or  rust.  The  cement  is  forced 
in  with  the  caulking-chisel  and  soon  becomes  very  hard.  A  lute  for  small  leaks  in 
iron  and  fire-clay  gas-retorts  can  be  made  with  4  parts  of  iron-filings,  2  of  clay,  and 
I  of  pulverised  porcelain  saggers.  This  mixture  is  made  into  a  paste  with  a  solution 
of  oonmion  salt. 

PMto.  The  material  used  by  bookbinders,  and,  in  fact,  wherever  paper  is  to  ba 
glued  to  paper,  is  obtained  by  boiling  flour  with  water  or  by  treating  starch  with  hot 
water. 

Starch  paste  is  best  made  by  rubbing  the  dry  starch  up  with  cold  water,  so  as  to 
form  a  uniform  magma,  to  which,  while  being  constantly  stirred,  boiling  water  is 
very  rapidly  added ;  this  paste  should  not  be  boiled  if  required  for  cementing  paper 
together.  Bye-meal  boiled  with  water  yields  an  excellent  paste,  which  may  be 
improved  by  the  addition  of  some  glue  solution  and  preserved  by  alum.  Partly 
decayed  and  liquefied  gluten  forms  an  excellent  paste.  Starch-paste  to  which,  while 
hot,  half  its  weight  of  turpentine  is  added  is  greatly  improved  and  rendered  water- 
proof by  the  addition. 


DIVISION  V. 

I   kND  THErR   INDUSTRIAL  A 


'Woollen  iNDPsmr. 
ori|iiuirnif«i««(  wdoL  Wool  is  distingaielied  from  hair  cliieflj  hy  the  three  (d- 
lowing  properties ; — wool  is  finer ;  is  not  Btraight,  but  cnrled ;  while  it  genertlly 
contains  less  pigment,  and  hence  is  white  in  colour.  The  qtulit;^  of  wool  increuM 
with  the  ifwreBae  of  these  Uiree  cliaracteristicB.  Wool,  like  hair,  exhibits  an  organiwd 
Btmctnre,  oonsi sting  hi Btolojtically  of  an  epithelium,  of  nrindsnd  of  apithormsiTOV. 
The  epithelium  of  wool  consists  of  small  thin  plates  which  overlap  each  other  lilM 
Fi8.  asi.  Fio.  asa. 


the  tiles  on  a  toof ;  in  this  manner  the  cnticnlar  plates  give  to  the  smflMe  a  squunow 
aj^earaoce,  whicli  may  be  coarsely  represented  as  the  nppeanuice  exhibited  hj 
a  fir-cone.  Fig.  231  exhibils  a  piece  of  wool  of  sn  ordinaiy  sheep;  while  Fig.  153, 
magmfied  to  the  same  number  of  diameters,  exhibits  a  piece  of  the  very  finest 
Saiony  wool,    thus  showing  the  great  diflerence  of  fineness  of  these  two  K>rts 


^  WOOL.  495 

of  wool.  The  grooves  on  the  snrfiace  of  the  wool  are  the  cfttise  of  its  rawness  to  the 
toncli,  and  from  the  existence  of  these  grooves  wool  admits  of  being  felted.  When 
the  fibre  which  exhibits  tliis  texture  is  pressed  togetlier  witli  a  kind  of  kneading 
motion,  while  the  fibre  is  at  the  same  time  softened  by  the  action  of  steam,  the  result 
is  that  the  fibres  are  joined  to  each  other  in  the  direction  of  the  scales  on  their 
surface  and^  becoming  entangled,  form  a  firm,  dense  texture,  which  is  termed  felt 

We  obtain  wool  chiefij  from  sheep ;  the  quality  of  the  wool  very  mnch  depends 
upon  the  peculiar  breed,  the  climate,  fodder,  and  care  taken  of  tlie  animals.  We 
distinguish  two  chief  breeds  of  sheep — ^viz. : — i.  The  mountain  slieep,  having  short, 
fine,  and  more  or  less  curly  wool.  2.  The  sheep  of  the  lowlands,  having  coarse, 
sleek,  long,  hair-like  wool.  To  the  first  breed  of  sheep  belongs  tlie  sheep  met  with  in 
the  interior  and  more  elevated  parts  of  Germany,  also  the  Spanish  merino  sheep,  of 
which  there  are  several  varieties,  the*  most  remarkable  being  the  infantado  and 
electoral  races.  By  the  latter  is  understood  tlie  variety  which  in  1765  was  imported 
into  Saxony,  being  made  a  present  to  the  Elector,  and  was  the  cause  of  the  exist- 
ence in  that  country  of  a  breed  of  sheep  yielding  excellent  wool.  Till  comparatively 
recently  the  exportation  of  the  living  merino  sheep  from  Spain  was  proliibited  under 
pain  of  capital  punishment.  The  variety  of  sheep  designated  Escurial  is  not 
a  peculiar  race  or  breed,  but  an  electoral  sheep  with  finer  and  faller  fleece.  Sheep, 
like  goals,  are  undoubtedly  animals  preferring  a  mountain  plateau,  and  are  very  sen- 
sitive to  a  damp  or  moist  soiL  There  are  many  varieties  of  the  lowland  sheep, 
among  them  the  heath  sheep  (lowlands  of  Germany) ;  the  so-called  Cretan  goat 
{Ovisari^  $irep$uMroi)  of  Southern  Europe  and  Western  Asia ;  the  various  breeds  of 
•Rw^liah  sheep,  Southdown,  Leicester,  Cotswold,  Lincoln,  &c.,  and  the  Scottish 
varieties,  Shetkad  and  Hebrides. 

The  varieties  of  wool  obtained  from  other  animalB  than  sheep  are : — 

a.  Cashmere  wool ;  the  fine  downy  hair  of  the  Cashmere  goats  inhabiting  the  eastern 
dopes  of  the  Himalaya,  14,000  to  18,000  feet  above  sea  level.  The  colour  is  white-grey 
or  brown.  In  the  state  in  which  it  is  sent  to  Europe  it  is  largely  mixed  with  coarse  hair, 
so  that  100  kilos,  of  the  raw  material  yield  after  sorting  and  cleansing  only  20  kilos,  of 
fine  hair. 

b.  The  ^cuna  wool ;  the  very  slightly  curly  hair  of  the  Llama  or  Tiouna  goat 
(Amehenia  VievMa)t  a  native  of  the  high  mountains  of  Pern,  Chili,  and  Mexico.  This  kind 
of  wool,  or  rather  woolly  hair,  was  formerly  more  so  than  now  employed  for  weaving  fine 
tissnes.  Sometimes  there  is  substituted  for  this  wool  a  mixture  of  ordinary  wool  and  the 
finest*  hair  of  haares  and  rabbits.  What  is  now  termed  Yiguna  or  Vicuna  wool  in 
the  trade  is  a  tissue  made  of  a  mixture  of  wool  and  cotton. 

e.  Alpaca  wool,  or  paoos  hair;  the  long,  sleek,  white,  black,  or  brown  hair  of  the 
Alpagna  or  Alpaco  (Pako),  a  kind  of  goat  which  dwells  in  Peru.  This  kind  of  wooUy  hair 
has  great  similarity  with  the  Yicmia  wool,  but  is  not  quite  so  fine.* 

d.  Mohair,  or  so-called  earners  wool ;  the  long,  slightly  curly,  silky  hair  of  the  Angora 
goat  {Copra  angoretuu),  a  native  of  Asia  Minor.  This  substance  is  spun  and  woven  into 
non-fulled  tissues  (camlet  or  plush),  and  is  also  mixed  up  with  the  hali-silk  tissnes 
of  which  it  forms  the  woof  or  weft. 

GfacmJeaicampoflittonof  Wool  Purified  sud  cleaused  wool  consists  chiefly  of  an  albumi- 
noid sulphur-containing  substance  termed  keratin  (homy  matter), but,  as  met  with  on 
the  animals,  wool  contains  mnch  dirt,  dust,  and  suint.  The  labours  of  Faist,  Beich, 
Ulbricht,  Hartmann,  Marcher,  and  E.  Schulze  have  greatly  increased  our  know- 
ledge of  this  substance. 

*  The  microscopical  texture  and  properties  of  this  kind  of  hair  have  been  investigated 
and  are  described  in  Wiesner's  work,  "Einleitung  in  die  Technische  Mikroskopie.** 
Vienna,  1867,  p.  172  et  teq» 


496  CHEMICAl,  TECHNOLOGY. 

Tlie  foIlowiDg  reBults  are  those  obtained  by  Falst  when  analysing  various  kinds  <€ 
merino  wool : — 

I.  2. 


d,  b,  C*  a*  ۥ  ^ 

Mineral  matter 63  i6'8  .   094  1-3  10  rz 

Saint  and  fatty  matter          44*3  447  2100  40-0  27*0  16-6 

Pure  wool 38*0  ^'5  7^'^  S^'o  648  777 

Moisture    ii*4  7'o  606  27  72  3-5 


lOO'O         lOO'O  lOO'OO        lOO'O        lOO'O         lOO'O 

Percentage  of  pure  air- 
dry  wool 49*4         355  7806       587       720        8sra 

z.  Baw  wooly  air-dried.-^^.  Hohenheim  wool,  with  a  small  quantity  of  readily  aolnbla 
Buint.  6.  Hohenheim  wool  (the  name  of  a  large  agriooltural  establishmeut  and  agiODO- 
mical  school  near  Stuttgardt,  Wurtemburg),  containing  a  large  quantity  of  glutinous  soini. 
a.  Washed  wool,  air-dry.* — c.  Hohenheim  wooL  d.  Same  variety,  withdiMonlUy  soinbla 
auint.    e.  Hungarian  wool,  very  soft.    /.  Wurtemburg  wool,  less  soft. 

While  making  researches  on  wool,  Eisner  of  Gronow  estimated  the  loss  wliiA 
wool  experiences  when  treated  with  sulphide  of  carbon  for  the  elimination  of 
the  suint.    The  results  were : — 

Washed  merino  wool     15  to  70  per  cent. 

Unwashed  wool  (laine  en  suint,  raw  wool) ...    50  to  80 
Long  carded  wool 18 

Suint  is  a  mixture  of  secreted  and  accidental  substances,  dust,  &c.  When  raw 
wool  is  macerated  for  some  time  in  warm  water,  there  results  a  turbid  liquid  which 
contains  suspended  as  well  as  dissolved  matters.  The  dry  substance  of  the  aqneovs 
extract  of  suint  consists,  according  to  Marcher  and  Schulze  (1869),  of: — 

z.  a.                 3.                 4* 

Organic  matter ...            58*92  61*86           59*12           60*47 

Mineral  matter  ...            41*08  38*14           40*88           39*53 

I  and  a  relates  to  wool  of  mountain  sheep.  3  and  4  to  full-bred  Bambouillet  she^. 

The  soluble  portion  contains  the  potash  salt  of  a  fatty  acid  (suintate  de  potaste). 
The  fatty  acids  contained  in  suint  are,  according  to  Keich  and  Ulbricht,  mixtures  of 
oleic  and  stearic  acids,  probably  also  palmitinic  acid  and  a  small  quantity  o£ 
valerianic  acid,  with  potash  in  such  quantity,  that  more  recently  this  material  has 
been  employed  to  obtain  therefrom  carbonate  of  potash  and  chloride  of  potassium. 
100  kilos,  of  raw  wool  may  yield  from  7  to  9  kUos.  of  potash  (See  p.  132). 
Potash  from  suint  consists,  according  to  Marcher  and  Schulze,  of: — 

Carbonate  of  potash    86*78 

ClJoride  of  potassium        ... 6*18 

Sulphate  of  potash      2*83 

Silica,  alumina,  lime,  magnesia,  oxide  of  iron, 

phosphoric  acid,  &c • •  4*21 

100*00 

*  Washed  on  the  sheep  while  alive,  an  operation  performed  by  the  farmers,  and  to  be 
distinguished  from  the  washing  wool  undergoes  during  manufacture. 


WOOL.  497 

P.  Havrez  (1870)  states  that  it  is  more  advantageous  to  extract  chloride  of  potas* 
Blum  and  prepare  ferrocyanide  of  x>otaHsium  from  suint  tlian  to  employ  it  in 
preparing  carbonate  of  potash.  Suint  is  a  valuable  material  in  gas  manufacture 
and  the  potash  salts  may  afterwards  be  extracted  from  the  coke. 

Fropertiwof  WooL  The  value  and  applicability  of  wool  for  the  purposes  of  being  spun 
and  woven  depend  upon  a  number  of  properties,  of  which  the  following  are  the  most 
important. 

Colour  and  oioH.  Wool  is  generally  white,  but  that  of  some  of  the  common  kinds 
of  sheep  and  also  of  the  alpaca  and  mohair  are  either  brown,  grey,  or  black. 
The  gloss  of  some  varieties  of  wool  is  a  highly  prized  property.  The  gloss  is  not 
exactly  related  to  tlie  fineness  of  the  wool,  but  more  to  the  softness  and  suppleness  of 
the  fibre,  which  on  being  touched  by  the  hand  imparts  a  feeling  similar  to  that 
of  cotton- wool  or  silk.  The  curl  or  waviness  of  the  wool  is  due  to  the  fact  tliat  the 
hair  or  fibre  is  bent  and  more  or  less  curved.  When  there  are  many  and  small 
curves  the  wool  is  termed  small  curled,  while  if  the  curves  are  large  it  is  termed 
coarsely  curled.  There  is  also  a  difference  between  wool  which  exhibits  high 
curves  (strongly  waved  and  curled)  and  wool  exliibiting  low  curves  (weakly  waved 
and  curled).  The  fineness  of  wool  depends  upon  the  smallness  of  diameter  of  the 
fibre ;  generally  the  finer  the  fibre  the  better  the  wool  is  suited  for  the  uses 
commonly  made  of  it.  There  are,  however,  some  varieties  of  wool  met  with  which, 
though  very  fine,  are  rather  tough  and  straight,  and  tlierefore  less  suited  for  manu- 
facturing purposes.  It  should  be  observed  that  the  diameter  of  the  woollen 
fibre  does  not  constantly  vary  with  tlie  fineness;  while  neither  the  wool-meter 
(eriometer)  nor  the  micrometer  can  sufficiently  determine  the  fmeness  of  the  wool  for 
technical  purposes,  that  property  being  best  estimated  by  practical  experience  by  the 
sense  of  touch.  What  is  termed  quality  or  uniformity  in  wool  is  that  the  fibre  has 
through  its  entire  length  the  same  diameter.  By  softness,  suppleness  of  the  wool, 
it  is  understood  that  the  fibre  readily  admits  of  being  bent  in  all  directions ;  this 
property  is  usually  accompanied  by  extensibility  and  elasticity'.  A  fibre  of  wool  may 
therefore  be  somewhat  more  strongly  stretched  before  breaking,  after  it  has  been  first 
straightened  so  as  to  remove  the  curls.  The  elasticity  of  the  fibre  is  sho>vn,  when  a 
hair  is  broken,  by  the  two  ends  becoming  more  or  less  rapidly  contracted  and  curled 
up.  By  strength  we  mean  that  property  of  wool  whereby  it  bears  without  breaking 
a  certain  weight,  which,  according  to  the  quality  and  fineness  of  the  fibre,  varies  from 
2*6  to  44  grms.  By  height  is  understood  the  length  of  the  curled  hair  in  its 
natural  position ;  while  by  length  we  designate  the  measure  (in  centimetres)  of 
a  single  fibre  when  so  stretched  that  its  curls  are  no  longer  perceptible.  The  length 
of  the  fibre  is  of  great  importance  in  the  selection  of  wool,  and  constitutes  one  of  the 
main  distinctions  between  carded  ^vool  and  short  wool.  The  teasled  wool  is 
used  more  especially  for  the  weaving  of  cloth — milled  or  fulled  cloth.  Generally 
this  kind  of  wool  is  strongly  curled,  and  the  length  of  the  stretched  hair  is  less  than 
15  centims.  The  combed  wool  (long  wool)  is  used  for  smooth  woollen  tissues  which 
require  a  middling  lengtli,  9  to  12  centims.,  some  strength,  and  not  too  much  curl. 

pnpanuon  of  wooL  Bcforc  wool  is  a  marketable  article  it  has  to  be  washed,  sliaved 
or  sheared  off,  and  sorted. 

I.  Just  before  shearing  the  wool  is  washed — or  as  the  term  more  usually  runs,  the 
sheep  are  washed — ^for  the  purpose  of  cleansing  tlie  fleece  and  of  eliminating  a  por- 
tion of  the  suint.    By  tliis  washing  wool  loses  from  20  to  70  per  cent  in  weight. 

2  K 


498  CHEMICAL  TECHNOLOOY. 

II.  The  Shearing  of  the  Sheep, — ^Usoallj  in  our  climate  sheep  are  sbom  oaIj 
a-year,  about  the  middle  of  May  or  beginning  of  June,  but  with  long-wooILed  abe^ 
this  operation  is  performed  in  September  (summer  wool),  and  about  the  end  of  Mardi 
(winter  wool).  Lamb's  wool  is  distinguished  by  its  great  fineness.  Besides  iha 
wool  shorn  from  the  live  sheep  we  distinguish  skinner^s  wool,  from  the  skins  of  dke^p 
slaughtered  for  food,  and  pelt  wool  from  sheep  which  have  died  from  disease ;  wbik 
the  former  kind  is  shoiier  than  ordinary  wool,  the  latter  is  deficient  in  strength  sad 
elasticity,  and  is  therefore  of  less  value. 

III.  Sorting  the  Wool, — Tlie  different  parts  of  the  skin  of  the  sheep  yield  wool  d 
different  quality ;  among  the  parts  which  yield  better  kinds  of  wool  are  the  shonldoB. 
the  flanks,  and  the  thighs.  The  wool  of  the  following  parts  is  of  inferior  qualikT. 
viz.,  neck,  withers,  back,  throat,  breast,  feet.  The  peculiar  mode  of  sorting  wod 
and  the  denominations  given  to  the  several  varieties  differ  in  different  cofontiici; 
generally  the  terms  firsUty  seconds y  thirds ,  &c.,  are  employed.  While  tlie  fineness  d 
the  wool  is  the  main  character  which  distinguishes  the  various  kinds,  the  sorter  afe> 
looks  to  the  length,  curl,  strength,  &c.  As  met  with  in  commerce,  wool  contains  a 
larger  or  smaller  quantity  of  hygroscopic  water,  varying  from  14  to  16  per  eent;  aai 
even  when  wool  is  exposed  to  dry  air  for  a  long  time,  the  water  amounts  to  7  orio 
per  cent. 

wooispianiag.  The  operations  of  spinning  do  not  in  strictnefls  pertain  to  ehewini 
technology,  because  the  material  operated  upon  is  not  chemically  treated,  ud  oo^f 
meohanicaUy  undergoes  a  change  of  form.  The  machinery  employed  is  very  eomplicatei, 
but  has  been  brought  to  great  perfection. 

Before  being  made  into  cloth,  the  wool,  as  is  the  ease  with  cotton,  silk,  flax,  and  hcnfi, 
has  to  be  made  into  yam.  Before  this  operation  can  be  proceeded  with,  the  sorted  vool 
is : — I.  Carded  for  the  purpose  of  weaving.  2.  Or  the  wool  is  combed  for  the  ">^^'ng  of 
smooth  woollen  goods.  Carded  wool  is  ultimately  made  up  into  doth,  while  oombed  wool 
is  made  up  into  such  materiiJs  as  thibet,  moussddne  de  lame,  merino,  <te.  The  foOofraig 
eight  operations  are  those  to  which  carded  wool  is  submitted : — 

z.  Washirtg, — The  aim  of  this  operation  is  to  eliminate  the  suint  from  the  wool,  and  Is 
this  puipose  the  fibre  is  submitted  to  the  action  of  very  weakly  alkaline  liquids.  TlMse 
even  in  the  carbonated  state  should  be  weak,  because,  when  concentrated,  the  wool 
either  is  dissolved  or  its  strength  and  elastici^  impaired.  The  alkaline  liquids  efai^ 
used  for  this  purpose  are  lant  (staie  urine)  mixed  with  water,  tepid  soap-suda,  or  a  veiy 
weak  solution  of  soda.  The  washed  wool  is  rinsed  in  plenty  of  cold  water,  wrung  oot,  aai 
then  dried  in  the  shade.  By  exposure  to  direct  sunlight  wool  becomes  yellow.  100  psaiB 
of  fleece  lose  by  washing  from  17  to  40  parts,  leaving  60  to  83  parts  of  pure  wooL 

2.  Dyeing, — ^When  tLos  operation  takes  place  immediately  after  washing,  it  is  only  ts 
impart  to  it  very  fixed  dyes,  such  as  indigo,  or  madder ;  because,  as  regards  most  oths 
dyes,  they  would  be  injured  by  the  operation  of  miUing,  in  which  soap,  lant,  and  oUmt 
materials  are  employed.  Wool  by  being  dyed  often  increases  considerably  in  weight, 
sometimes  as  mudi  as  12  per  cent. 

3.  WiUowingj  or  Devilling, — This  operation  aims  at  the  obtaining  of  thefloeka  of 
a  more  uniform  mass,  while  at  the  same  time  mechanical  impuritieB,  straw,  Ae., 
removed.    The  machinery  by  which  this  is  effected  is  similar  to  that  used  for  the 
purpose  for  cotton. 

4.  Oiling  or  Greasing. — As  wool  has  a  great  tendency  to  become  felted,  and  has  to  be 
submitted  to  the  operation  of  carding,  it  might  in  this  process  become  broken ;  and  in 
order  to  prevent  this  and  give  the  fibre,  which  has  become  harsh,  suppleness,  it  is  cTfiatteil 
or  mixed  with  oiL  For  the  finer  kinds  of  wool,  olive  oil  or  araohis  oil  is  used,  while  fer 
coarser  kinds  rape-seed  and  fish  oil  are  employed.  Olein,  as  it  is  termed,  really  oleie  add, 
a  by-product  of  the  manufacture  of  stearine  candles,  is  often  used  for  this  purpose,  pro- 
videditbe  not  contaminated  with  either  sulphuric  or  stearic  acids.  100  kilos,  of  wool  for 
warp  require  10  to  12  kilos,  of  oil,  while  100  kilos,  of  wool  for  woof  require  12  to  15  kiloa. 
of  oil. 

5.  The  carding  of  wool  aims  at  the  same  result  as  the  carding  of  cotton.  Hie 
machinery  employed  is  in  each  instance  similar  in  construction.  Wool  is  carded  at  least 
twice.    The  first  carding  is  termed  fleece-carding,  the  result  being  that  the  wool  ia  loimed 


WOOL.  499 

into  a  I00B6  fleece,  which  is  rolled  tip  on  a  cylinder ;  the  second  carding  converts  the  fleece 
into  loose  curls  about  i  metre  or  a  yard  in  length,  which  are  tnmed  over  on  to  the  roving 
mAcbine.  Recently  the  oarding-nuU  has  been  so  oonstmcted  that  it  also  performs  the 
operation  known  as  roving. 

6.  Having, — ^By  means  of  machineiy  the  wool  is  converted  into  what  is  technically 
termed  »lub  or  half -y amy  which  by  the  following  operation,  viz., 

^.  By  spinning  is  made  into  yarn.  The  maofiinery,  while  working  at  a  high  speed, 
tvnsts  the  fibres  into  a  continnoos  thread  or  yam. 

8.  The  finished  yam  is  wound  on  reels,  the  length  of  the  skeins  or  hanks  and  the 
number  of  skeins  to  a  bunch  varying  in  different  localities.  The  fineness  of  the  yam  ia 
abroad  designated  by  the  number  of  hanks  which  go  to  the  half  kilo. ;  but  in  Belgium  and 
France  the  number  of  metres  of  yam  length  which  go  to  the  kilo,  expresses  the  fineness. 

ArUOAiai  wooL  WooUou  rags  are  carefully  sorted,  and  by  means  of  machinery  converted 
into  what  is  termed  mungo  and  shoddy ;  the  former  is  a  short-haired  wool  obtained  from 
milled  goods ;  the  latter  (a  longer  hair)  is  prepared  from  woollen  hosiery.  The  rags  having 
been  well  sorted,  and  aU  seams,  buttons,  and  ornaments  cut  off,  silk  and  other  linings 
separated,  are  cleansed,  again  sorted,  and  tiien  oUed.  The  rags  yield  on  an  averase 
30  per  cent  of  the  weight  of  buttons,  linings,  ^.,  and  the  70  per  cent  remaining  yields 
Bome  five-sevenths  of  mungo,  prepared  by  means  of  a  mill.  Mungo  is  not  carded;  but 
shoddy,  made  by  a  sindlar  process,  is  carded  after  having  been  again  oiled. 

we«Tiiiit  tiM  aoth.      Cloth  is  a  smooth  woollen  fabric,  the  woof-yam  passing  alternately 

over  and  under  chain-yarns.     The  peculiar  felty  appearance  is  given  to  cloth  by  the 

operation  of  milling  or  fulling.    The  operation  of  weaving  cloth  does  not  differ  in  any  way 

from  the  weaving  of  linen  or  cotton  fabrics ;  usually  the  chaiu  and  weft  yarn  are  equally  fine. 

WMhimr  MMi  MffliaK      The  cloth  as  it  leaves  the  weaver*s  hands  is  not  in  the  least  similar  to 

iha  Booffh  Ooth.     the  finished  fabric,  but  is  very  like  a  coarsely  woren  towel,  the  chain 

and  weft  being  quite  loose  and  eveiy  thread  distinctly  visible ;  w^le  the  felty  appearance  of 

the  cloth  is  entirely  absent,  this  being  obtained  by  the  operation  of  milling,  whicn  is  preceded 

by  the  burling  process,  whereby  knots,  pieces  of  straw,  and  other  similar  impurities  are 

removed  by  the  aid  of  small  steel  forceps.     The  rough  cloth  is  next  washed  for  the 

purpose  of  removing  oil,  dirt,  and  weavers*  glue ;  this  washing  is  assisted  by  Boft  soap, 

potash  or  soda  ley,  and  is  performed  by  a  washing  machine.    The  operation  of  lulling  or 

milling  aims  not  only  at  a  cleansing  of  the  rough  cloth  (it  is  not  always  washed  previously 

to  being  milled),  but  more  particularly  at  the  felting  together  of  the  fabric,  so  that  the 

chain  and  weft  can  hardly  be  distinguished.    It  is  performed  by  the  joint  action  of 

moisture,  high  temperature,  and  a  peculiar  mechanical  treatment,  by  which  the  threads 

are  kneaded  into  each  other.    As  the  milling  also  aims  at  the  complete  removal  of  grease 

the  water  into  which  the  fabric  is  steeped  is  jrendered  alkaline  by  means  of  lant,  while 

soft-soap  and  fuller's  earth  (see  p.  295)  are  used  to  assist  the  action.    Soft  soap  is  only 

used  for  common  cloth,  while  for  the  finer  kinds  palm  oil  and  olive  oil  Boaps  are  employed. 

The  milling  or  fulling  consists  in  beating  the  rough  cloth  with  wooden  xnallets  moved  by 

machinery ;  recently  the  use  of  cylinders  is  very  general  for  this  purpose. 

T«uiiBc  Mid  shMdBf      hi  order  to  give  to  the  milled  cloth  a  more  pleasing  appearance,  it  Ui 

tha  Gioth.  fint  teasled  and  next  shom.    x.  The  operation  of  teasling  aims  at  the 

loosening  of  the  surface  hairs  of  the  felted  cloth,  and  at  brushing  these  in  one  direction ; 

the  operation  is  performed  by  the  use  of  teasles  or  weaver's  thistle  (Dtpfocia  fuUonum) 

which  acts  by  the  thorns  on  the  seed  capsules.    2.  The  shearing  of  the  cloth  is  an 

operation  by  which  the  surface  hair  is  cut  off  to  a  uniform  length.    The  shearing  is  either 

performed  by  hand — a  very  tedious  operation,  the  cloth  being  stretched  uniformly  on  a 

cushioned  table,  the  operator  using  peculiarly  made  shears— or  by  cylinders,  somewhat 

similar  to  lawn  grass-cutters  in  principle  of  working.    There  is  a  distinction  between 

transversal,  longitudinal,  and  diagonal  cylinders,    a.  The  transversal  cylinder  is  placed 

lengthwise  to  the  cloth,  the  cylinder  moving  from  one  edge  of  the  doth  to  the  other. 

/3.  In  the  longitudinal  machine  the  moving  cylinder  is  placed  across  the  width  of  the 

eioth,  which  is  moved  under  the  shearing-kmves.    7.  In  the  diagonal  machine  several 

cutting  cylinders  are  placed  diagonally  above  the  cloth.    The  wool  shom  off  is  used  in 

upholstering,  and  very  Itf gely  for  the  purpose  of  giving  a  velvety  appearance  to  some 

kinds  of  paper-hangings. 

DiMdiisttMCfetii.      Before  the  cloth  is  ready  for  sale,  it  has  to  be  submitted  to  the  three 
following  operations : — Lustring,  brushing,  and  pressing. 

X.  The  lustring  is  now  performed  by  stretching  the  cloth  very  tightly  on  a  copper 
cylinder,  the  surface  of  which  is  perforated  with  a  number  of  small  holes.  The  cylinder 
is  placed  in  a  steam  chest,  and  steam  having  been  turned  on,  the  cloth  obtains  a 
permanent  gloss  and  is  prevented  from  becoming  rough  on  being  worn.  2*  The  brushing 
of  the  doth  takes  place  before  and  after  the  shearing,  and  is  effected  by  machinery,  the 


500  CHEMICAL  TECHNOLOGY. 

brushes  being  fixed  to  cylinders,  and  the  cloth  mored  over  and  under  them,  while  at  ^ 
same  time  either  a  jet  of  water  or  sometimeB  steam  is  made  to  play  on  the  doth. 
3.  Finally,  the  cloth  is  pressed,  having  been  first  folded  ;  between  each  fold  is  placed  ea 
the  right  side  of  the  cloth  a  piece  of  glazed  millboard  and  a  piece  of  coarser  millboard  os 
the  wrong  side ;  a  plank  is  put  between  the  pieoeB  of  cloths,  some  six  to  twelve  of  wUdi 
are  placed  in  the  press  at  a  time. 

other  aoth  Fabrioi.  In  addition  to  milled  cloth  several  other  kinds  of  woolleii  goods 
are  manufactured,  wliich  are  cloth-like  in  some  particular.  Of  these  Uie  foUowiog 
are  the  chief : — Flannel,  either  smooth  or  twilled,  only  slightly  milled,  once  teasled 
on  tlie  right  side,  and  eitlier  not  sliom  at  all  or  only  once ;  the  chain  often  conaiistsdf 
carded  wool,  but  is  sometimes  cotton  or  silk ;  the  woof  is  carded  yam.  Siran-skiB 
is  fine  twilled  flannel.  Cashmere  is  finely  twilled  cloth  only  once  teasled,  but  shorn  as 
often  as  cloth.  The  hair  is  short  and  covers  the  textile  yam  slightly,  so  that  the 
twill  is  distinctly  seen.    Cashmere  is  often  made  with  a  cotton  chain. 

Frieze  is  coarser,  stouter,  and  longer-haired  than  cloth,  is  strongly  fulled,  bat  \em 
teasled  and  also  less  shorn.  After  having  been  shorn,  frieze  is  simply  dressed  by 
being  brushed  and  hot-pressed ;  it  is  then  brushed  over  with  a  solution  of  tragacsndi 
in  water,  next  calendered,  and  lastly  slightly  oiled  with  olive  oil  and  again  pressed. 
A  non-twilled  and  finer  kind  of  frieze  is  known  as  ''  ladies'  mantle  frieze  ;'*  while  a 
heavier  and  short  shorn  frieze  is  called  castories.  Kalmuk  and  thick  frieze  ^Irisk 
frieze)  consists  of  a  heavier  yam  and  is  more  strongly  milled.  Buckskin  is  a 
twilled  non-teasled  trouser  material,  the  right  side  of  which  is  shorn  and  quite 
smooth.  Kersey  is  a  coarse  kind  of  imdressed  (neither  teasled  nor  shorn)  woollen 
fabric  used  for  making  cloaks  and  overcoats  for  military  men,  sailors,  railway 
ofiicials,  &c.  The  coarser  kinds  of  railway  rugs  and  horse-cloths  are  of  a  similtf 
material.  Paper-makers*  felt  is  a  coarse,  twilled,  loosely  woven,  lightly  miDed 
material,  neither  teasled  nor  shorn,  used  for  tlie  pm'pose  of  being  placed  between  the 
wet  sheets  of  paper.  Felted  cloth,  a  fabric  first  made  some  twenty  years  ago  wiihool 
spinning  and  weaving  at  all,  has  not  been  found  suitable,  and  is  tlierefore  now  hanlly 
ever  seen.  Wool  intended  for  felting  purposes  is  first  cleansed,  freed  firom  snint, 
next  carded  and  converted  into  a  imiformly  thick  layer  similar  to  cotton- wool,  and  is 
then  felted. 

Wonted  Wool.  It  has  been  already  stated  tliat  long  haired  or  combed  wool  is  the 
material  used  for  the  purpose  of  preparing  worsted-yam — a  smooth  thread,  tbd 
longitudinal  fibres  of  which  are  placed  parallel  to  each  other — ^this  yam  serving  the 
purpose  of  weaving  such  fabrics  as  thibet,  merino,  Orleans,  &c.  There  is  a  distinc- 
tion between  genuine  combed  wool  or  worsted,  and  half-worsted  or  sayette-yam, 
which  is  the  link,  as  it  were,  between  combed  and  carded  wool,  and  is  used  for  the 
purposes  of  knitting  stockings,  in  carpet-making,  Berlin-wool  work,  &c.  Althoo^ 
half-worsted  is  always  spun  from  long-haired  wool,  the  fibre  is  not  in  this  instance 
combed,  but  caided  by  a  peculiarly  constructed  mill.  Combed  yarn  or  worsted 
consists  either  entirely  of  wool,  or  is  a  thread  of  wool  mixed  with  mohair  and 
alpaca,  or  of  wool  and  cotton,  or  of  wool  and  silk,  such  yams  being  termed  fancy 
yams. 

The  manufacture  of  smooth  woollen  fabrics  is,  as  far  as  weaving  and  the  mechanical 
operations  are  concerned,  similar  to  tlie  weaving  and  mode  of  manufacturing  oither 
textile  fabrics.  .  Some  of  the  smooth -surfaced  woollen  fabrics  are  finished  when 
woven ;  others  require  a  dressing  which  depends  upon  tlie  taste  of  the  consumers 
and  upon  the  peculiar  requirements  of  the  trade.     The  following  ennmeratioa 


SILK.  '  30I 

of  the  smooth-surfaced  woollen  fabrics,  of  whicli  there  is  an  almost  endless  variety, 
may  give  some  idea  of  the  various  kinds  of  goods  belonging  to  this  category. 

A.  Smooth  Fabrics, — Barracan  used  to  be  formerly  -woven  from  camera  hair,  but  is  now 
woven  from  combed  wool ;  it  is  termed  moir^d  when  it  is  watered.  Orleans  consists  of  a 
twisted  cotton  thread  chain  and  a  single  woollen  weft ;  the  fabric  having  been  woven  is 
singed,  washed,  dried,  shorn,  and  hot-pressed.  Camlet  also  was  formerly  made  from 
camePs  hair,  and  consists  of  combed  woollen  chain  and  weft.  Dress  crape  is  a  fabric 
made  of  a  strongly  twisted  worsted  yam-chain  and  more  loosely  woven  weft ;  -when  the 
cloth  is  woven  it  is  dyed  black  or  grey,  next  wound  round  a  cylinder,  and  boiled  in  water 
In  order  to  shrink  it.  Bolting  cloth  is  made  of  a  strongly  twisted  yam,  and  employed  for 
the  purpose  of  making  flour-sieves.  Mousseline  de  laine,  chaly,  is  a  woollen  muslm  with 
silk  chain,  and  this  class  includes  a  host  of  fabrics  generally  known  as  Bradford  fabrics  as 
well  as  mixed  materials,  alpaca,  mohair,  silk  mohair,  &o, 

B.  Tvfilled  Goods, — Merinos  with  three-  or  fonr-threaded  twill  and  two  **  right  **  sides 
are,  after  weaving,  singed,  hot-pressed,  and  dressed  or  glazed.  When  unglazed  it  is  called 
thibet.  Serges  are  twilled  fabrics  with  three,  four,  or  five  strands.  So-called  Atlas 
fabrics  are  kalmang  and  lasting,  the  latter  employed  for  ladies*  shoes,  gentlemen's  cravats, 
furniture,  and  upholstery  work.  The  fabric  from  which  the  press-bags  of  the  oil-mills 
are  made  is  also  a  twilled  woollen  material  woven  from  very  strong  and  tough  wool. 

C.  Variegated  or  Patterned  Fabrics y  such  as  are  used  for  trousers,  and  also  woollen 
damask.  Shawls  belong  to  this  class;  in  some  of  these  the  whole  fabric  is  woollen 
(Cashmere  shawls) ;  in  others  a  silk  or  cotton  thread  is  mixed.  The  plaids  and  tartans 
are  especially  British  fabrics. 

D.  Velvets, — ^Woollen  velvet,  woollen  plush,  and  velpel,  are  merely  distinguished  from 
each  other  by  the  length  of  the  hair,  which  is  greater  in  plush  than  in  velvet,  and  greatest 
in  velveteen.  Woollen  velvets  are  employed  in  various  ways ;  for  instance,  in  covering 
chairs,  sofas,  for  curtains,  d^c.  These  materials  are  more  or  less  loosely  woven,  and  are 
variously  shorn  and  dressed,  being  known  in  the  trade  by  such  appellations  as  astracan, 
beaver,  castorin,  Utrecht  velvet,  Ae. 


Silk. 

sok.  Silk  is  at  once  distinguished  from  cotton,  flax,  hemp,  and  wool  by  being 
naturally  produced  as  a  very  long  and  continuous  thread,  whereby  the  operation  of 
spinning  is  dispensed  with ;  but  in  its  stead  the  operation  known  as  silk-throwing  is 
required,  by  which  several  of  the  natural  fibres  of  the  sUk  are  twisted  into  one  in 
order  to  obtain  a  stouter  yam. 

Silk  is  the  produce  of  the  silkworm  (Bomhyx  mori)^  an  insect  which  undergoes 
four  metamorphoses.  The  worm  is  produced,  in  Uie  spring,  ^om  the  egg,  or  ovule. 
It  casts  its  skin  from  three  to  four  times,  and  finally  spins  a  thread,  produced,  or 
rather  secreted,  by  two  glands  placed  near  the  head,  from  small  apertures,  in  which 
is  a  glutinous  fluid  which  immediately  coagulates  under  contact  witii  air.  Thus 
what  is  termed  a  cocoon  is  formed,  which  serves  as  a  shelter  for  the  pupa 
against  injury  and  cold.  The  thread  is  double,  but  is  united  in  one  by  a  peculiar 
kind  of  glue  termed  serecin,  which  is  laid  as  a  kind  of  varnish  over  the  whole 
surface  of  the  thread,  of  which  it  forms  about  35  per  cent  of  the  weight.  After  a 
period  of  fifteen  to  twenty-one  days  the  pupa  is  metamorphosed  into  a  butterfly, 
which,  in  order  to  leave  its  prison,  softens  a  portion  of  the  cocoon  with  a  juice  which 
it  secretes,  and  then  perforates  the  softened  part.  For  the  purpose,  however,  of 
producing  silk,  the  pupa  is  not  aUowed  to  develop  so  far,  but  is  killed  (excepting  in 
a  number  of  cocoons  intended  for  the  full  development  of  the  butterflies  so  that  they 
may  produce  eggs),  and  the  thread  of  the  cocoon  is  carefully  wound  on  a  reel 

VMiJt£^m!^oniM.  ^^0  Bomhyx  mori  is  the  mun  supplier  of  silk.  Its  food  is  tha 
leaves  of  the  white  mulberry  tree,  Morus  alba.  There  are,  however,  other  silk- 
producing  insects,  among  which  the  following  are  to  be  noticed : — 


5oa  CHEMICAL  TECHNOLOGY. 

a.  Bofnbyx  eynthia^  largely  eultivated  by  the  natiyes  of  the  north-east  portion  oi  tht 
interior  of  Bengal  and  also  by  the  Japanese ;  the  former  call  this  worm  ^Irrirufy-ama,  tkft 
latter  Yama-mai.  This  worm  feeds  on  rice  leaves,  Ricinus  communis.  The  silk  obtaJBal 
from  this  insect,  although  less  brilliant  than  that  which  the  ordinary  silkworm  yidds,  is 
Tery  usefnl,  as  being  durable  and  strong.  This  Wbrm  will  feed  on  other  lea-res,  sueh  it 
that  of  the  weavers'  thistle,  Dipsacus  fulUmum,  wild  ohicory,  Chicorium  Intibus,  and  the 
leaves  of  the  AyUmthm  glandtUosa,  The  results  of  acclimatising  this  insect  in  FniiM 
and  Germany  have  been  satisfactory. 

6.  Bombyx  Pemyi  is  a  native  of  Mongolia  and  China ;  it  feeds  on  oak-leaves.  Some 
years  ago  these  worms  were  introduced  into  France,  and  have  been  fed  and  reand 
successfully  upon  European  oak-leaves. 

c.  Bombya  mylittai  or  Tussa  worm,  is  a  native  of  the  colder  parts  of  Hindostan  sad  <i 
the  slopes  of  the  ^mialaya.  Its  silk  is  an  important  article  of  commerce  in  Bengal 
This  insect  feeds  on  oak  and  other  leaves,  casts  its  skin  five  times,  and  yields  laife 
cocoons.  The  fibre  of  this  kind  of  silk  is  from  six  to  seven  times  stouter  than  the  silk  of 
the  ordinary  worm,  but  unfortunately  the  Tussa  worm  only  lives  in  its  free  natural  sttis, 
and  when  captive  does  not  produce  silk.  The  following  silk-produdng  varieties  belong  to 
North  America: — d,  Bombyx poluphemut ;  on  oak  and  poplar  trees,  e,  B,  cecropia;  oo 
elm,  whitethorn,  and  wild  mulberry  trees.  /.  B,  pUUensU ;  on  a  kind  of  mimoHSi 
Mitnosa  plateruU,    g,  B,  leuca  deserves  further  attention. 

We  quote  the  following  account  of  the  culture  and  rearing  of  silkworms  : — i.  Tbs 
mulberry  tree.  The  leaves  of  the  variety  known  as  the  white  mulberry  tree,  finom 
the  fact  that  its  fruit  is  yellow  or  light  red  in  colour,  is  tlie  most  suitable  food  for  thii 
insect,  but  its  cultivation  belongs  to  horticultural  pursuits,  and  we  cannot  eniesr  upon 
the  subject  here.  2.  The  production  of  the  eggs  or  ova  of  the  silkworm  is  efiected  in 
the  following  manner : — The  largest  and  finest  cocoons,  and  such  as  have  a  fins 
thread,  are  selected  and  preserved ;  usually  the  cocoon  of  the  female  insect  is  more 
oval  than  that  of  the  male,  which  is  more  pointed  at  tlie  ends  and  is  somewbst 
depressed  in  the  centre.  Although  these  characteristicB  do  not  apply  in  all  eases, 
sericiculturists  become  sufficiently  adepts  in  this  matter  to  be  able  to  select  a 
sufficient  number  of  cocoons  of  each  sex.  loo  to  120  pairs  of  well-formed  cocoons 
yield  about  30  grms.  of  eggs,  about  50,000  in  number,  from  which,  however,  only 
about  70  to  75  per  cent  of  worms  are  obtained.  The  cocoons  selected  for  breeding 
purposes  are  allowed  to  remain  on  a  table  covered  with  a  white  cotton  dolfa- 
After  some  twelve  days  the  butterflies  make  their  appearance,  and  having  paired,  the 
females  after  a  lapse  of  some  forty  hours  lay  300  to  400  eggs.  3.  The  eggs  are 
properly  protected  from  cold  in  winter  and  remain  in  the  buildings,  called  magmt- 
neiies,  being  placed  in  a  uniform  layer  on  a  cotton  cloth  stretched  on  a  wooden 
frame.  The  eggs  are  covered  with  sheets  of  white  paper  perforated  with  smaU  holee. 
Upon  the  sheets  of  paper  mulbenry  leaves,  at  first  cut  up  so  as  to  form  a  kind  of 
chaff,  are  placed.  In  France  a  contrivance  known  as  a  couveuse,  that  is  to  say,  an 
oven  in  which  a  suitable  temperature  is  kept  up,  ip  |iow.  generally  used  for  the 
purpose  of  breeding  the  worms,  which  are  best  hatched  from  the  eggs  at  a  tempera- 
ture of  30^  provided  moisture  is  also  present.  The  young  brood  on  leaving  the  eggi 
creep  through  the  holes  in  the  paper,  and  seeking  daylight  (there  is  always  free 
access  of  light  in  magnaneries)  begin  at  once  to  feed  on  the  mulberry  leaves.  4.  The 
rearing  of  the  worms  requires  care  and  attention.  They  are  best  placed  on  paper 
laid  on  wooden  frames.  The  worms  grow  rapidly  and  are  very  yoracions.  They 
cast  their  skins  four  times,  and  after  thirty  to  thirty -two  days  begin  to  spin  the 
cocoons.  5.  When  the  period  of  spinning  approaches,  the  worms  are  placed  in 
small,  somewhat  conical  wicker-work  baskets,  in  which  they  are  comfortably  located. 
The  first  thread  spun,  or  rather  an  entangled  flocky  mass,  is  afterwards  separately 
collected  and  kept  as  floss  silk.    The  insect  discharges,  before  beginning  to  spin 


SILK, 


503 


farther,  first  a  solid  sabstance,  white  or  green  in  colour,  and  consisting,  according  to 
P61igot,  chiefly  of  uric  acid,  next  a  clear,  watery,  very  alkaline  liquid,  which  contains 
i'5  per  cent  of  carbonate  of  potash,  this  curious  discharge  amounting  to  15  to  20  per 
cent  of  the  weight  of  the  worm.  The  formation  of  the  cocoon  is  finished  in  about  five 
days,  but  the  cocoons  are  not  collected  for  the  purpose  of  reeling  the  silk  until  after 
seven  or  eight  days,  so  as  to  make  sure  that  all  the  worms  have  spun. 

As  far  as  the  chemical  composition  of  silk  is  concerned,  we  have  to  distinguish 
between  the  fibre  and  its  envelope.  The  fibre  consists  for  about  half  its  weight  of 
fibroin,  a  substance  which,  according  to  Stadeler*s  researches,  is  nearly  related  to 
homy  matter  and  mucus,  and  is  identical  with  these  as  regards  chemical  composi- 
tion. The  formula  of  silk  fibroin  is  CxjHajNjOe.  The  gum-like  envelope  of  the 
silk  fibre,  which  has  been  termed  by  Cramer  and  Stadeler  silk  glue  or  sericin,  is 
partly  soluble  in  water  and  readily  so  in  soap-suds  and  other  alkaline  fluids.  The 
formula  of  sericin  is  CzjHssNjOs.  P.  Bolley*s  researches  have  proved  that  in  the 
silk-producing  and  secreting  glands  of  the  worm  only  glutinous,  semi-liquid 
fibroin  occurs,  which,  in  coming  into  contact  with  air,  is  acted  upon  by  the  oxygen 
and  then  converted  into  sericin.  Raw  silk  leaves  on  ignition  a  small  quantity  ^of 
ash ;  Guinon  found  in  Piedmontese  raw  silk,  dried  at  100**,  0*64  per  cent  of  ash,  con- 
sisting of  0*526  lime  and  o'ii8  alumina  and  oxide  of  iron.    Dr.  G.  J.  Mulder  found 

in  100  parts  of  nCw  silk : — 

Tellow  silk  from        White  silk  from  the 
Naples.  Levant  (Almasin  silk). 

Fibroin      53'40  540 

Glue-yielding  matter      2070  191 

Wax,  resin,  and  fatty  matter. ••  1*50  1*4 

Colouring  matter     005  — 

Albumin    24'40  25*5 

6.  KiiUng  of  the  Ptipa  in  the  Coeoon, — The  pupa  remains  in  the  cocoon  for  from 
fifteen  to  twenty  days,  and  is  then  metamorphosed  into  a  butterfly,  which  will 
perforate  the  cocoon  and  thus  obtain  an  exit.  It  is  dear,  however,  that  the  cocoons 
not  intended  for  breeding  purposes  should  not  be  kept  so  long,  because  by  the 
perforation  of  the  cocoon  the  silk  is  spoiled,  or  at  least  greatly  deteriorated ;  therefore 
the  papn  in  the  cocoons  are  killed  either  by  the  application  of  oven-heat  or  of  steam, 
luntpabooa  octiM  suk.  Six  different  operations  .are  required  to  render  raw  silk  fit  for 
use  as  an  article  of  commerce  and  suited  for  weaving,  Ac.  These  operations  are : — 
I.  The  sorting  of  the  cocoons,  an  operation  which  requires  great  care  and  greater 
experience,  its  aim  being — (a)  the  separation  of  yellow  from  white  cocoons ;  03)  the 
elimination  of  all  damaged  cocoons  as  only  fit  for  yielding  floret  silk ;  the  damage  may 
arise  in  various  ways,  as,  for  instance,  by  mouldiness,  injury  by  other  insects,  and, 
lastly,  fouling  of  the  pupa,  as  well  as  perforation  by  the  butterfly ;  (y)  selection  of 
the  cocoons  according  to  varying  fineness  of  thread  and  uniformity  of  the  ailk. 

2.  Winding  the  silk  on  a  reel  is  the  first  operation  with  the  cocoon.  By  this  the 
threads  of  silk  which  the  insect  has  wound  up  into  a  kind  of  ball  is  wound  off  and 
brought  into  the  shape  of  a  skein  or  strand. 

As  the  single  fibre  of  silk  is  far  too  thin  to  be  manipulated,  the  operator  usually 
unites  from  3  to  10  or  even  20,  making  them  unite  by  the  operation  of  reeling ;  this 
is  not  by  any  means  so  readily  performed  as  might  be  imagined,  because  it  is 
difiicult  to  find  tlie  end  of  the  thread,  whilst  the  surface  of  the  cocoon  is  varnished 


504  CHEMICAL  TECHNdLOGY. 

with  a  gum-like  mass  which  ghies  the  fibres  togetlicr.  Partly  hy  the  aid  of 
hot  water  and  partly  by  dexterity  these  difficulties  are  overcome,  and  by  good 
management  a  tliread  of  250  to  900  metres  length  may  be  obtained  from  each 
cocoon,  each  3rielding  from  01 6  to  020,  at  the  utmost  025  gi*ms.,  of  raw  silk,  i  kilo, 
of  raw  silk  requires  from  10  to  12  kilos,  of  cocoons.  The  silk  thus  obtained  is  termed 
raw  silk,  which  should  be  quite  uniform  as  regards  tluckness  and  strength  of  fibi>». 
That  portion — ^the  interior  and  a  portion  of  the  outer  layer  of  the  cocoon — ^which  does 
not  admit  of  being  reeled  off  is  employed  for  making  floret  silk,  by  operations  amilar 
to  tliose  in  use  fpr  wool  and  cotton — viz.,  cleansing,  disentangling,  combing. 
carding,  and  spinning,  to  produce  a  silk  yam. 

I.  TJie  'Throwing  of  Silk. — As  the  thread  obtained  by  reeling  is  too  fine  for 
use  eitlier  for  weaving,  knitting,  sewing,  &c.,  it  is  usual  to  unite  several  threads  of 
silk  by  means  very  similar  to  tliose  used  in  rope-making,  an  operation  termed 
throwing,  known  as  twisting  when  the  tliread  of  raw  silk  is  simply  rotated  oa 
its  axis  so  as  to  make  it  stronger.  The  following  are  the  chief  varieties  of  thrown 
silk : — I.  Organzine,  used  as  chain  for  woven  silk  fabrics,  is  prepared  from  the  bed 
raw  silk.  The  threads  of  3  to  8  cocoons  are  united ;  being  first  strongly  twisted  and 
next  thrown,  after  which  two  of  such  threads  are  twisted  together.  2.  Trame  used 
for  woof  or  weft  and  for  silk  cord  is  made  from  inferior  cocoons.  Single-threaded 
trame  consists  of  one  single  twisted  raw  silk  thread  made  up  of  the  united  threads  of 
3  to  12  cocoons.  The  double-threaded  trame  consists  of  two  untwisted  threads  thrown 
to  the  left  but  less  strongly  than  in  organzine.  There  is  also  three-threaded  trame,  Ac. 
Trame  is  softer  and  smoother  than  organzine,  and  tlierefore  fills  better  than  round 
threads  in  weaving.  3.  Marabou  silk  is  stiffly  thrown  and  similar  to  whipcord  ;  it  is 
made  from  three  threads  of  the  whitest  raw  silk  and  tlirown  in  the  trame  fashion ;  u 
dyed  without  being  previously  scoured  (boiling  tlie  gum  out  in  tliis  instance),  and  is 
again  thrown  after  dyeing.  4.  Foil  silk  is  a  simple  raw  silk  thread,  twisted, 
and  used  chiefly  as  a  basis  for  gold  and  silver  wire,  such  as  is  worn  on  militaiy 
uniforms.  5.  Sewing  silk  is  obtained  from  some  3  to  22  cocoon  threads  being 
twisted  together.  There  are  several  other  varieties  of  silk  thread  used  for  crochet, 
knitting,  Ac. 

4.  Conditiottuig  or  Testing  of  Silk. — The  fineness  of  raw  as  well  as  of  thrown 
silk  is  expressed  by  stating  how  many  yards'  or  metres'  length  of  the  fibre  aie 
contained  in  a  certain  weight  The  unit  abroad  is  400  ells  or  475  metres.  'NMien  the 
expression  is  used,  that  such  silk  is  at  10  grains,  it  is  understood  that  475  metm* 
length  of  that  particular  silk  weigh  10  grains ;  a  silk  at  20  grains  has  the  same 
length  but  double  the  weiglit,  and  consequently  that  silk  is  only  half  as  fine  as  the 
former. 

Raw,  as  well  as  thrown  silk,  contains  a  large  quantity  of  hygroscopic  water, 
the  quantity  of  which  cannot  be  judged  by  the  external  appearance  of  the  materiaL 
The  silk  usually  met  with  in  commerce  contains  10  to  18  per  cent  of  hygroscopic 
water;  and  silk  may  occasionally  contain  even  30  per  cent  without  appearing  to 
be  moist.  As  silk  is  a  very  expensive  material  and  often  sold  by  weight,  it  is  clear 
that  this  property  of  taking  up  water  is  too  important  to  be  left  unnoticed  ;  and  for 
that  reason  silk  is  conditioned  as  it  is  called,  tliat  is,  tlie  quantity  of  water  it 
contains  is  duly  ascertained. 

5.  Scouring  or  Boiling  tlie  Gum  out  of  Silk. — ^Excepting  a  few  instances,  such  as 
lor  example,  in  the  weaving  of  fine  silken  sieve  cloths,  and  for  crape  and  gauxs 


'      SILK.  505 

&brics,  raw  silk  has  to  be  deprived  of  its  envelope— the  gummy  matter  already 
mentioned,  in  order  to  give  softness,  suppleness,  gloss,  and  especially  also  to  render 
the  silk  fit  for  being  dyed. 

The  operation  of  scouring  is  comprised  in  the  following  manipulations  :-^ 

z.  Hemoving  the  gum  {degomtner), 

2.  Boiling. 

3.  Colouring. 

The  taking  out  of  the  gum  is  performed  in  the  following  manner : — Olive  oil  soap 
is  first  dissolved  in  hot  water  and  into  this  solution  at  85°  the  skeins  of  silk  are 
placed  hung  on  sticks.  The  skeins  are  moved  about  in  this  bath  until  all  the^gum 
has  been  uniformly  taken  out.  The  silk  is  next  wrung  out,  rinsed  in  fresh  water 
and  then  dried.  Silk  may  by  this  process  lose  12  to  25  per  cent  in  weight, 
according  to  the  quality  of  the  raw  silk  and  tlie  quantity  of  soap  employed.  The, 
scoured  silk  is  ready  for  dyeing  with  dark  colours,  but  if  required  to  be  dyed  with 
bright  colours  it  has  to  be  first  boiled.  To  this  end  it  is  put  into  coarse  canvas 
bags,  each  containing  from  12  to  16  kilos,  of  silk,  and  in  these  sacks  the  silk  is 
placed  in  a  soap  bath  and  boiled  for  li  hours ;  the  silk  is  next  rinsed  in  water,  wrung- 
out,  and  dried.  The  operation  of  rosing  or  colouring  aims  at  imparting  to  the  silk  a 
slight  tint  in  order  to  enhance  its  beauty.  The  trade  distinguishes  various  hues  of 
white  silk,  such  as  Chinese  white,  azure  white,  pearl  white,  &c.  The  first  of  these 
Jiues,  a  somewhat  ruddy  tint,  is  obtained  by  rinsing  the  silk  in  soap-water,  to  which 
some  Orleans  has  been  added.  The  bluish  hues  are  produced  by  indigo  solutions. 
The  bleaching  of  scoured  silk  is  efiected  by  tlie  aid  of  sulphurous  acid,  the  fibre 
either  being  placed  in  a  room  where  this  gas  is  evolved  from  burning  sulphur,  or  by 
treating  the  silk  with  an  aqueous  solution  of  the  acid.  As  silk  loses  a  great  deal  in 
weight  as  well  as  in  body  by  the  scouring,  which  is,  however,  required,  because  raw 
silk  does  not  admit  of  being  dyed,  it  has  become  the  practice  to  produce  a  material 
called  90upU,  obtained  by  treating  the  raw  silk  with  boiling  water  in  which  only 
a  small  quantity  of  soap,  i  kilo,  to  25  kilos,  of  silk,  is  dissolved.  Instead  of  tills 
soap  solution,  an  acidified  (with  dilute  sulphuric  acid)  solution  of  sulphate  of 
magnesia  or  of  soda  is  sometimes  used.  The  silk  loses  by  this  process  only  4  to  10  per 
cent  in  weight.  In  order  to  bleach  raw  silk  without  depriving  it  of  its  natural 
rigidity,  the  skeins  are  digested  at  a  temperature  of  20°  to  30''  with  a  mixture  of 
alcohol  and  hydrochloric  acid ;  this  liquor  becomes  green  in  colour,  and  the  deeper 
the  hue  the  whiter  tlie  silk.  The  silk  is  rinsed  in  water,  and  having  been  dried  will 
be  found  to  have  lost  only  about  2*91  per  cent  in  weight.  The  alcohol  used  in  this 
process  may  be  readily  recovered  by  neutralising  the  acid  with  chalk  and  by 
subsequent  distillation. 

wmtLbc  of  sak.  This  branch  of  the  silk  industry  is  very  similar  to  the  weaving  of 
cotton,  linen,  woollen,  and  mixed  fabrics;  very  frequently,  however,  silk  yam 
is  mixed  and  woven  ^ith  other  fibres.  Often  either  tlie  chain  or  woof  is  made 
simply  of  twisted,  not  of  thrown,  silk,  the  advantage  being  the  production  of  thicker, 
but  less  coarse  fabrics.  Dark  silk  tissues  are  ready  for  the  market  as  soon  aa 
woven ;  they  are  only  folded  and  pressed.  Lighter  silk  fabrics  (atlas  and  tafietas) 
are  washed  over  with  a  sponge  dipped  in  a  solution  of  gum  tragacanth,  and  are  next 
hot-pressed  or  calendered  by  the  aid  of  iron  cylinders  eitlier  heated  by  steam  or  by 
placing  a  led-hot  iron  in  them.     Heavy  silk  fabrics  are  often,  as  it  is  termed^ 

2  L 


5o6  CHEMICAL  TECHNOLOGY. 

moired^  tliat  is,  while  partly  moistened  are  passed  between  hot  rollers.  By  the  aid  of 
copper  cylinders  bearing  various  designs,  diiferent  patterns  are  en  relief  <»in>mf^ 
upon  heavy  silken  and  silk  velvet  fiabrics,  being  gaufred,  as  it  is  termed. 

Silk  fabrics  are : — i.  Smooth.  2.  Twilled.  3.  Patterned.  4.  CHuze.  5.  YelTei 
a.  To  the  first  category  belong : — i.  Taffetas,  a  light,  thin,  smooth  tissae,  made 
of  scoured  silk,  the  chain  being  organzine  single  threaded,  the  woof  trame,  and 
bi-  or  tri- threaded.  2.  Gros  (Oros  de  Tours,  Qros  de  Naples),  a  heavy  tafietas-lilx 
fabric,  woven  with  heavy  thread,  and  hence  having  a  ribbed  appearance  when  thick 
and  thin  threads  are  mixed. 

6.  Twilled  fiabrics  are : — i.  The  various  kinds  of  serges  (Groisi,  l^vantimy  dnp 
de  soie,  bombasin).  This  fabric  has  a  right  and  a  T^Tong  side,  the  former  being  tbe 
chain  side.  2.  Adas,  or  satin,  in  all  its  endless  varieties,  single,  double,  half,  aad 
serge  atlas. 

c.  Patterned  fabrics.  To  this  class  belong  all  fabrics  which  either  by  the 
art  of  weaving  or  by  other  means  are  distinguished  by  some  design  (droguet,  cfaagiia, 
reps,  silk  damask,  &c.) 

d.  To  the  velvet  fabrics  belong : — i.  Genuine  velvet;  cut  or  uncut.     2.  Plush. 

e.  To  the  silk  gauzes  belong  an  immense  variety  of  very  light  materials^  as  fta 
instance: — i.  Marie.  2.  Silkstramin.  3.  Crape.  4.  Various  qualities  of  silk  webs. 
5.  Barege.  • 

It  is  quite  beyond  the  scope  of  this  work  to  enter  into  further  details  on  the 
subject  of  the  mixed  fabrics,  of  wliich  indeed  there  is  a  very  large  and  jetjij 
increasing  variety.  Among  them  we  mention  here  only  poplin  as  made  in  Ireland,  a 
beautiful  mixed  fabric  of  linen,  wool,  and  silk,  and  often  woven  in  what  is  knowm 
as  tartan  pattern.  Mixed  woollen  silk  and  cotton  fabrics  are  very  largely  produced 
in  tlds  country  as  weU  as  abroad. 
hmuu  of  niltinfcniahins  Bilk      Owing  to  the  manufacture  of  mixed  fabrics,  it  has  beeeoae 

fron  Wool  And  fron 

vagvubie  Fibrsa.  a  ncccssity  to  be  enabled  to  detect  and  distinguish  silk  ham 
woollen  as  well  as  from  cotton  and  linen  fibres.  Microscopical  investigadoQ 
aided  by  chemical  tests  are  resorted  to  for  this  purpose. 

The  animal  fibres  (silk,  wool,  and  alpaca),  are  at  once  distinguished  from 
the  vegetable  (flax,  hemp,  cotton),  by  tlie  fsu^t  tliat  the  former  are  soluble  in  causde 
potash,  and  the  latter  not.  The  animal  fibres  on  being  singed  give  off  a  smell 
of  burnt  feathers,  and  when  ignited  in  tlie  flame  of  a  candle  are  almost  immcdiatdy 
extinguished,  a  carbonaceous  residue  being  left.  Cotton  and  linen  fibres  oontinae  to 
bum,  do  not  give  off  the  smell  of  burnt  feathers,  and  do  not  leave  a  carbonaoeons 
mass  when  extinguished.  Wool  and  silk  are  coloured  yellow  by  nitric  add 
(i'2  to  1*3  sp.  gr.),  cotton  and  linen  not  so.  Niti*ate  of  protoxide  of  mercury  colours 
animal  fibres  intensely  red,  and  upon  the  addition  of  a  soluble  alkaline  sulphnret 
this  colouration  becomes  black.  Linen,  or  flax,  and  cotton  are  not  at  all  acted  upon 
by  this  reagent.  An  aqueous  solution  of  picric  acid  dyes  wool  and  silk  intensdy 
^  yellow,  but  not  so  vegetable  fibres.  The  colourless  liquid  obtained  (according  to 
liebermann)  by  boiling  a  solution  of  fuchsine  with  caustic  potash  does  not  impart 
to  a  mixed  fabric  of  wool  and  cotton  any  colour  at  all ;  but  when  the  fiedNric  is 
thoroughly  washed  in  water,  the  woollen  fibre  becomes  intensely  red- coloured,  while 
the  cotton  fibre  remains  colourless.  A  solution  of  ammoniacal  oxide  of  copper  in 
excess  of  ammonia  dissolves,  first  silk,  next  cotton,  but  not  wool.  When  wool  and 
floret  silk  are  mixed  the  latter  may  be  dissolved  by  successive  treatment  with 


SILK. 


507 


nitric  acid  and  ammonia,  while  wool  is  left  A  solution  of  oxide  of  lead  in  caustdo 
potash  or  soda  may  serve  to  distinguish  wool  from  silk,  owing  to  the  &ct  that,  in 
cosseqQence  of  the  fonner  containing  sulphur  snd  the  latter  not,  the  mixtnre.  when 
-^ool  ia  present,  becomes  black.  KitrD-pmsside  of  sodium  is  undonbtedlj  the  most 
delicate  test  for  distingnishing  between  silk  and  wool  in  solution  in  eaustio 
alkali,  because,  owing  to  the  salphur  of  the  wool,  this  reagent  produces  in  the  solution 
a  -violet  colouration. 

li;  the  aid  of  the  microscope,  cotton,  wool,  and  silk  are  readily  distinguished  ' 
from  each  other.  As  for  cotton  (see  p.  343),  it  has  been  fully  described,  and  its 
microscopical  appearance  illnstrated  hj  woodcuts,  as  also  have  silk  and  woollen 
fibres.  Of  the  latter  we  maj  now  state  that,  whereas  cotton  fibre  conriets  of  onl7 
one  cell,  wool  (as  also  hair  and  alpaca),  ia  made  up  of  numerous  juxtaposed  cells; 


Pio,  353. 

t 


the  silk  fibre  being  similar  to  the  secreted  matter  of  spiders  and  other  kinds  of 
caterpillars.  The  silk  fibre  (Fig.  253)  is  smooth,  cylindrical,  devoid  of  structure,  not 
hoUow  inside,  and  equally  broad.  The  surface  is  glossy  and  only  seldom  are 
any  irregularities  seen  on  it.  If  it  is  desired  to  detect  in  a  woven  fabric  the 
genuineness  of  the  silk,  it  is  beet  to  cut  s  sample  to  pieces,  place  it  under  water 
onder  the  object-glass  of  a  microscope  magnifying  110  to  aoo  times,  covering  it  with 
a  thin  piece  of  ^ass.  The  round,  glazed,  equally  proportioned  silk  fibre.  Fig.  354, 
is  easily  distinguished  from  the  imequal  and  scaled  wool  fibre  (w  in  Fig.  255I,  and 
from  the  flat  band-like  and  spiral  cotton  fibre  (n.  Fig.  355).  Under  the  microscope 
also  the  admixture  of  inferior  with  superior  fibres  of  silk  can  be  easily  detected.  A 
amoll  microscope  known  as  a  '■  linen-prover  "  is  sold  for  these  examinations. 


5o3  CHEMICAL  TECHNOLOGY. 

Tanning. 

TumiBK.  Tlie  operation  by  which  the  skins  of  yarions  animals,  more  es|>eeiaI3T 
-those  of  the  larger  mammalia,  are  converted  into  leather  is  called  tanning.  By 
leather  we  understand  a  substance,  tough,  flexible,  not  harsh;  further,  distingm^ei 
by  resisting  putrefaction  and  bj  not  yielding  any  glue  when  boiled  in  wstet 
as  is  the  case  with  tanned  hide,  sole  leather,  and  the  so-called  red- tanned  leaHicr, « 
only  after  a  very  continued  boiling,  as  with  tawed  skins  of  calves,  sheep,  or  goak. 
Whatever  the  differences  which  obtain  in  the  practical  processes  for  carrying  oot  fte 
conversion,  the  physical  principle  involved  is  the  same  in  all.  Knapp's  genenl 
definition  of  leather  is  that  it  is  skin,  in  which  by  some  means  or  other  the  agg^Qd< 
nation  of  the  fibres  after  drying  has  been  prevented. 

To  a  comparatively  very  recent  period  tanning  was  conducted  on  an  empxrieal 
basis ;  it  is  only  by  a  more  accurate  knowledge  of  the  histological  structnie  of  ^ 
skin  and  of  the  Winin-containing  materials  that  the  real  nature  of  the  process  has 
become  known,  this  knowledge  being  due  chiefly  to  the  researches  of  F.  ICnapp  snd 
BoUet. 

That  which  is  converted  into  leather  is,  however,  not  the  skin  or  hide,  but  really 
what  is  known  anatomically  as  the  corium,  that  is  to  say,  the  inner  portion  of 
the  skins,  from  which  by  mechanical  (cutting  and  scraping!  as  well  asbj  chemicd 
means  (action  of  lime)  the  other  integuments  have  been  removed.  In  its  most  genenl 
sense  tanning  should : — i.  Effect  tiie  prevention  of  putrefaction.  2.  Render  the 
dry  skin  a  supple,  fibrous,  tough,  non-transparent  substance,  and  not  homy  as  woald 
be  the  case  were  the  skin  simply  dried.  A  well-tanned  skin  or  hide  possessing  ihem 
properties  is  termed  "  well  finished."  The  specific  process  of  tanning  is  of  course 
preceded  by  some  preliminary  operations,  the  aim  of  which  is  to  "  dress**  the  skins  or 
hides — ^that  is,  in  scientific  terms,  to  prepare  the  corium  more  or  less  perfectlj  free 
from  all  other  integuments.  Tanning  in  the  more  restricted  sense  of  the  word  may  be 
effected  by  a  great  many  organic  and  inorganic  substances ;  bat  in  practiee  on  tbe 
large  scale  there  is  employed : — 

1.  Tannin  as  contained  in  oak  bark,  producing  brown-red  tanned  leather. 

2.  Alum  an4  common  salt — Tawing. 

3.  Fatty  matters — Samiflin  or  Oil  Tawing. 

AsAiomy  of  Animal  Skin.  Leaving  the  hair  out  of  the  question,  the  skin  of  the  mam- 
malia consists  of  several  layers.  The  uppermost  of  these  in  which  the  hair  is 
growing,  the  epidermis,  is  very  thin,  semi-transparent,  and  consists  of  cells  which 
contain  nuclei.  This  epidermis  is  covered  by  a  more  or  less  homy  layer  not 
possessing  any  vital  properties,  which  gradually  wears  off,  and  is  as  gradually  replaced 
by  the  stratum  Malpighiij  or  Malphigian  net,  a  structure  consisting  of  cells  con- 
taining fluid  and  nuclei.  It  is  this  layer  in  which  the  nerves  and  finer  blood  vessds 
are  imbedded,  together  with  tlie  glands  which  provide  the  perspiration.  In  the  tsa- 
yards  this  layer  is  known  as  the  bloom  side^  or  hair  side  of  the  skin  oar  hida 
The  real  corium  or  derma,  situated  under  the  layer  just  mentioned,  does  not  consist 
of  cells,  but  is  of  a  fibrous  texture,  and  is  that  portion  of  the  skin  which  after 
tanning  constitutes  the  leather;  in  the  living  animal  it  is  separated  from  tiie 
muscles  by  a  more  or  less  strongly  developed  fat-bearing  tissue,  the  so-called 
pannioulus  adiposus,  which  is,  however,  removed  in  the  dressing,  the  side  of  tbe  slda 


TANNINO.  509 

cr  hide  to  which  it  was  attached  being  termed  the  flesh  side.  All  the  histological 
constitiients  of  skin  or  hide  possess  the  property  of  swelling  np  when  put  into  hot 
-wat^,  and  of  becoming  after  more  or  less  protracted  boiling  converted  into  glue, 
snore  slowly  when  the  skin  is  taken  from  old,  more  rapidly  when  from  young 
animals.  By  the  action  of  acetic  acid  the  fibrous  tissue  of  the  skin  is  converted  into 
a  jelly-like  transparent  mass,  in  which. the  fibres  are  not  only  not  destroyed  but  pre- 
sent with  their  peculiar  structure.  .  Alkaline  leys  dissolve  this  tissue  but  very 
slowly ;  while  lime-  and  baryta- water  have  no  other  efiect  on  it  than  simply  the  dis- 
solving therefrom  of  the  cellular  binding  tissue,  which  permeates  it,  and  which  is  an 
albumen  compound  also  acted  upon  by  .dilute  acids. 

The  various  operations  of  tanning,  more  particularly  the  preliminaiy  operations 
of  steeping  and  dressing,  are  based  upon  the  behaviour  of  the  different  histological 
elements  of  the  skin  and  hide  with  alkaline  and  acid  fluids ;  but  the  real  process  of 
tanning  is  based  upon  the  behaviour  of  the  corium  with  totally  different  reagents. 
This  latter  substance  has  the  property  of  combining  with  tannic  acid,  several 
metallic  oziden,  viz.,  alumina,  the  oxides  of  iron  and  chromium,  oxidised  fatty 
matter,  the  insoluble  metallic  soaps  (compounds  of  fat  acids,  viz.,  stearic,  palmitinio 
acids,  Ac.y  with  oxide  of  lead,  &c.),  picric  acid,  pinic  acid  (present  in  rosin),  and 
other  organic  substances,  somewhat  in  the  same  way  as  animal  and  vegetable 
fibre  combine  with  dyes  and  pigments.  In  the  most  extended  sense  of  the  word  all 
these  substances  are  tanning  agents,  because  they  possess  the  property  of  being 
precipitated  on  and  in  the  fibres  of  the  corium,  so  that  when  the  latter  is  dried  the 
agglutination  of  the  fibres  is  prevented,  and  the  natural  suppleness  and  softness  of 
the  skin  preserved.  But  in  the  case  of  the  application  of  alumina  compounds,  the 
softness  is  only  imparted  to  the  tanned  skins  by  the  operations  of  currying  and 
dressing. 

I.  Bed'  or  Bark- Tanning. 

Tanning  Materials, — ^This  branch  of  industry  employs  as  raw  materials  hides  and 
vegetable  materials  containing  tannin. 

These  vegetable  materials  contain  essentially  an  astringent  principle  termed 
tannin  or  tannic  acid,  and  which,  though  it  differs  in  some  of  its  properties  as 
derived  from  different  plants,  agrees  in  being  of  an  astringent  taste,  exhibiting 
add  reaction  to  test-paper,  of  yielding  with  salts  of  peroxide  of  iron  a  deep  blue- 
black  or  green-black  colour,  of  precipitating  solutions  of  glue  and  dnchonine,  and 
lastly  of  converting  animal  skins  into  leather.  It  has  been  proved  that  the  tannin 
present  in  nut-galls — ^which,  by-the-bye,  are  too  expensive  for  use  in  tanning  opera- 
tions—is converted  by«the  action  of  acids  and  by  fermentation  into  glucose  and 
gallic  acid,  the  latter,  however,  not  being  suited  for  tanning  purposes.  Under  the 
conditions  which  obtain  during  the  tanning  of  hides,  the  tannic  acid  contained 
in  oak  bark  (tan)  cannot  be  split  up  similarly  to  nut-galls,  and  this  negative 
property  really  aids  the  tanning  operations  greatly.  All  kinds  of  tannic  acid  are, 
when  in  contact  with  alkaline  liquids,  such  as  lime-water,  caustic  potassa,  ammonia, 
and  with  the  simultaneous  presence  of  air,  decomposed  and  converted  into  brown- 
coloured  humin  substances. 

oakBaik.  This  substanco  is  for  the  tanner  the  most  important  of  all  tannin- 
containing  materials,  and  cannot  be  replaced  by  any  other.  It  is  the  inner  bark  of 
several  kinds  of  oak,  Quereus  robur,  Q,  peduneulata,  and  is  stripped  from  the  trees 
and  branches  when  these  have  attained  an  age  of  from  nine  to  fifteen  years,  the  bark 


14*43 

ft 

41  to  53 

13*23 

if 

41  to  53 

11*69 

n 

41  to  53 

13*92 

ft 

41  to  53 

13*95 

>• 

14  to  15 

510  CHEMICAL   TECHNOLOGY. 

when  cut  into  splints  hemg  tenned  tan.    According  to  E.  WoIiOT,  the  quantity  cf 
tannin  contained  in  oak-bark  is  as  follows : — 

Tannic  Add.       Age  of  the  TreeB. 
In  the  emde  bark  covered  with  the  rind      10*86  per  cent      41  to  53 

inside  layer  of  the  old  bark 

inside  of  the  bark      

crude  bark  and  inside  of  bark  ... 

inside  layer  and  inside  of  bark 

inside  of  bark     •••    • 

„        I,  «••     •••     ...     •••       i5*"3      »»  2  to    7 

According  to  Buchner's  researches  (1867)  the  quantity  of  tannic  acid  contained  ia 
tlie  best  kinds  of  oak  bark  does  not  exceed  6  to  7  per  cent.  The  fir  bark  (prodoee  of 
Pinus  syluestris)  is  one  of  the  best  tanning  materials,  and  is  frequently  used  for  sole 
leather ;  this  bark  is  stripped  off  the  trees  immediately  after  they  have  been  cut  dom 
for  timber.  WhUe  J.  Feser  found  5  to  15  per  cent  of  tannin  in  this  bark.  Dr.  Wagner 
found  only  7*3  per  cent.  In  the  United  States  the  bark  of  the  Abieg  canadefuu 
is  used ;  and  an  extract  is  in  the  trade,  which  according  to  Nessler's  researdies 
(1867)  contains  14*3  per  cent  of  tannic  acid.  Hie  extract  ia  imported  into  this 
country  under  the  erroneous  appellation  of  hemlock  extract.  The  bark  of  the  efan 
with  3  to  4  per  cent  tannin,  the  bark  of  the  horse-chestnut  witli  about  2  per 
cent  tannin,  and  beech-tree  bark  with  also  about  2  per  cent  tannin,  are  all  emjiloiyed 
for  tanning  purposes.  The  younger  branches  and  twigs  of  the  willow  trees  yield  a 
bark  (3  to  5  per  cent  tannin)  which  is  especially  suited  for  certain  kinds  of  giore 
leather;  while  another  kind  of  willow  bark  is  used  for  the  tanning  of  RussiaB 
leather.  In  Tasmania  and  New  South  Wales  the  barks  of  some  species  of  acaeia, 
viz.,  Acacia  dealbata,  A.  melanoxylon.  A*  lasiophyUa^  and  A,  decurrens  are  vaed. 
Among  the  native  European  plants  which  might  be  advantageously  cultivated 
for  tanning  purposes,  the  Polygonum  bistorta  deserves  to  be  mentioned :  this  plant 
should  contain  according  to  Fraas  from  17  to  21  per  cent  (?)  of  tannic  acid. 

snmae.  This  substsuce  is,  next  to  oak  bark,  one  of  the  most  important  *M>«Tng 
Diaterials ;  it  is  the  product — the  leaves  and  stems — of  a  shrub,  the  so-called  tanner*8 
sumac  {Rhiu  cpriaria  and  R.  typhina),  which  grows  %vild  in  Southern  Europe  and 
the  Levant,  and  is  cultivated  in  North  America  and  Algeria.  The  shoots  from  the 
roots  are  collected  and  planted  in  June,  and  after  some  three  years*  growth,  the 
shrubs  are  large  enough  to  admit  of  the  branches  and  leaves  being  gathered.  The 
young  branches  and  twigs  are  cut  off,  and  after  drying  in  the  sun,  the  leaves  are 
beaten  off  with  sticks  or  clubs,  and  next  crushed  under  mill-siones,  sifted,  and  packed 
into  sacks,  and  tlius  sent  into  the  market.  The  sumac  of  commerce  ia  a  coarse 
powder,  exhibiting  a  yellow  or  blue-green  colour,  and  containing  12  to  16*5  per 
cent  of  tannic  acid.  By  keeping,  the  tannic  acid  of  sumac  is  converted  into 
secondary  products,  owing  to  a  spontaneous  fermentation.  Sumac  also  contains  a 
yellow  dye-stuff  which  seems  to  be  identical  with  querdtrin.  With  sumac  should  not 
be  confused  another  material  of  the  same  name,  but  distinguished  as  Italian  or 
Venetian  sumac,  and  derived  from  the  Rhusootinus,  also  yielding  fustic  or  yellow 
dye-wood.  Italian  sumac  is  the  pulverised  bark  of  the  young  twigs  and  leaves  of 
this  plant,  which  under  the  name  of  ruga  grows  in  Southern  Europe  and  also  near 
Vienna ;  it  is  largely  used  in  the  countries  where  it  grows  for  tanning  purpoeetk 
being  more  particularly  employed  for  preparing  goat-  and  slieep-skins. 


TANNING.  511 

-  DiTidiTi       The  material  designated  by  this  name  is  the  seed  capsule  of  some  trees 
fband  native  in  Central  America,  and  belonging  to  the  Cfesalpinuwue ;  these  seed 
cApsules  are  about  6  centims.  long,  are  bent  as  an  S,  have  a  brown-red  colour,  and 
contain  olive-green  coloured,  egg-shaped,  polished  seeds.    In   1768  the  Spaniards 
l>roaght  this  material  to  Europe,  where  it  is  used  for  tanning  purposes  on  account  of 
tlie  tannin  contained  in  the  epidermis  of  the  capsules  (more  correctly  siliqiuB,  or  pods). 
Xbe  quantity  of  tannin  was  found  by  Miiller  to  be  49  per  cent,  by  Fleck  32*4  per 
cent,  while  Dr.  Wagner  found  from  19  to  267  percent    Dividivi  is  rather  an  expen- 
sive tanning  material,  but  is  occasionally  used  for  dyeing  purposes.    Among  the 
tannin-containing  substances  wliich  are  occasionally  imported  from  abroad  may  be 
mentioned  the  bablah,  tlie  produce  of  the  Acacia  Bablah  and  allied  species.    This 
material  contains,  according  to  Fleck,  so' 5  per  cent  tannin,  while  Dr.  Wagner  found 
14-5  per  cent.    AlgarobiUa,  tlie  seed  capsules  of  the  Prosopis  pallida,  a  native  of 
Cliilif  has  been  also  occasionally  employed  as  tanning  material  in  this  country. 
Although  myrobolans,  the  fruits  of  Terniinalia  citra,  T,  Bellirica,  and  T,  ChebtUa,  are 
imported  from  Bombay,  they  contain  too  little  tannin  to  be  of  any  service  in  tan-yards. 
Kat  odna.      Wc  Understand  by  this  name  an  excrescence  formed  on  the  leaves  of  the 
Quercu*  infectoria  by  the  puncture  of  the  female  insect  of  the  Cynips  gaUa  Wictoria^ 
or  oak  wasp,  effected  in  the  leaves  and  young  twigs  in  order  to  deposit  its  eggs ;  the 
juices  of  tlie  tree  collect  round  the  egg,  and  on  hardening  form  the  nut-gall.    This 
material  is  best  collected  before  the  young  insect  has   become   fully   developed^ 
because  then  the  gall  contains  the  largest  quantity  of  tannic  acid.    In  the  market 
three  varieties  are  met  with,  termed  black,  green,  and  white  galls.    The  black  and 
green  variety  have  been  gathered  before  the  insect  became  fully  developed  inside  the 
nut;  these  galls  therefore  do  not  exhibit  outwardly  any  hole  or  opening,  but  on 
breaking  Uie  gall  there  will  be  observed  in  the  centre  a  small  cavity  surrounded  by  a 
light  brown  friable  substance,  which  contains  the  larva  of  the  insect.    Galls  are 
generally  spherical,  but  exhibit  small  irregularities  of  surface,  and  are  of  a  black- 
green  or  grey  colour.     The  white  galls  are  gathered  after  the  insect  is  fully 
developed,  and  has  by  perforating  the  tissue  of  the  gall  escaped.    This  variety  is 
more  spongy,  its  colour  is  a  red-brown  or  brown-yellow.    Galls  of  good  quality  are 
obtained  only  from  warmer  countries,  for  although  galls  are  formed  in  our  climate 
npon  oak  leaves,  tiie  quantity  of  tannin  contained  amounts  to  only  3  to  5  per  cent. 
Fehling  found  in  Aleppo  galls  from  60  to  66  per  cent  of  tannic  acid,,  while  Fleck 
found  58*71  per  cent  of  this  acid,  and  5*9  per  cent  gallic  acid. 
VftioniftMnu.      Thcso  are  the  dried  immature  acorn  cups  of  two  species  of  oak, 
Quercus  agilops  and  Valonia  camata,  both  being  employed  in  tanning  as  well  as  the 
Talonia  nuts  produced  by  the  puncture  of  the  Cynips  quercus  calycis.    The  quantity 
of  tannic  acid  met  witli  in  these  substances  averages  about  40  to  45  per  cent.    In  the 
so-called  valonia  flour,  obtained  by  grin<^g  the  acorns  belonging  to  this  class. 
Dr.  Wagner  found  19  to  27  per  cent  of  tannin.   The  acorn  cups  are  imported  under  the 
name  of  drillot,  and  according  to  RoUie  these  contain  43  to  45  per  cent  of  tannin. 

cbiiMM  a«ita.  Under  this  name  lias  been  known  in  the  trade  since  1847,  ^^^  imported 
from  Japan,  Cliina,  and  Nepaul,  the  excrescence  upon  a  kind  of  sumac,  Jihus 
javanica  and  li.  semialata,  produced  by  the  puncture  of  the  Aphis  sinensis.  This 
gall-nut  is  rather  oblong  or  bean-shaped,  with  an  irregular  surface  covered  with  a 
yellow-grey  felt ;  the  length  varies  from  3  to  10  centims.,  and  the  thickness  from  1*5  to 
4  centims. ;  the  texture  is  homy ;  the  quantity  of  tannin  varies  from  60  to  70  per  cent. 


512  CHEMICAL  TECHNOLOGY. 

Catch.  The  substances  long  known  in  medicine  under  the  name  of  catechu  and 
kino  have  been  for  the  last  fifty  years  also  employed  as  tanning  materials.  Theyare 
vegetable  extracts,  that  known  as  cutch  (trade  term)  being  obtained  bj  exhausting 
with  boiling  water  the  pith  of  the  wood  of  the  Acacia  catechu,  a  tree  met  with  in 
different  parts  of  the  tropical  regions  of  Asia.  The  liquor  obtained  by  boiling  the 
pith- wood  in  water  is  inspissated,  and  on  cooling  forms  a  solid  mass,  which  is  brou^ 
into  commerce  in  various  shapes  and  named  alter  the  port  of  shipment.  Bombay 
cutch  is  met  with  in  the  shape  of  large  square  blocks,  through  and  round  which  the 
leaves  of  a  kind  of  palm-tree  are  placed.  The  colour  of  the  fracture  of  this  substance 
is  a  brown-black  with  a  fatty  gloss ;  externally  the  mass  is  dull  and  friable.  Bengal 
cutch  is  prepared  from  the  nuts  of  the  Areca  catechu,  and  occurs  in  oommeree  as 
large,  irregularly-shaped  cakes,  externally  brown,  internally  more  yellow-coloiued. 
Gambir  is  a  variety  of  cutch  prepared  in  Sumatra,  Singapore,  and  Malacca,  and 
especially  in  the  Island  of  Kiouw,  from  the  leaves  and  stems  of  the  Uncaria  Qambir, 
The  dry  exti*act  occurs  in  commerce  in  small  cubical  blocks,  which  are  light,  of  a 
cinnamon-colour,  and  very  friable,  the  fracture  being  earthy.  All  these  substances 
contain  about  40  to  50  per  cent  of  a  peculiar  kind  of  tannic  acid  or  catechu  tannis 
acid,  the  formula  of  which,  according  to  J.  Lowe,  is  C15H14O6,  as  well  as  a  peculiar 
acid,  catechutic  acid,  O16H14O6,  not  of  much  use  in  the  tanning  process. 

Kino.  This  drug  is  very  similar  to  catechu,  and  is  said  to  be  the  extract  prepared 
from  various  plants,  viz. : — 

African  kino  from    Pterocarpus  erineteeus. 

East  Indian  kino  froln    Pterocarpus  Martupium^ 

East  Indian  kino,  according  to  otliers,  from  Butea  frondo$a. 

West  Indian  kino  from Coccolaha  uvifera^ 

Australian  kino  from      Eucalyptus  resinifera. 

Eino  is  met  with  in  small,  angular,  brittle,  brown-red  to  black-coloured  massea^ 
the  powder  of  which  is  always  brown-red.  It  is  soluble  in  hot  water  and  alcohol. 
yielding  a  blood-red  solution  of  an  astringent  and  sweet  taste.  Kino  contains  from 
30  to  40  per  cent  of  a  tannic  acid  similar  to  that  contained  in  cutch ;  both  of  these 
materials  are  especially  useful  in  so-called  quick  tanning. 

*^th?^lSiSi  MLtoriSL*^  ^^®  value  of  all  the  tanning  materials  entirely  depends  upon 
the  quantity  of  tannic  acid  they  contain.  The  latter  is  soluble  in  water,  and  more  or 
less  completely  precipitated  from  tliat  solution  by  various  reagents,  such  as  glue  and 
animal  skin,  acetate  of  copper,  acetate  of  oxide  of  iron,  cinchonine  and  quinine, 
while  a  solution  of  permanganate  of  potash  completely  destroj's  the  tannic  acid. 
Upon  these  properties  tlie  following  properties  have  been  based  for  the  approximative 
estimation  of  the  quantity  of  tannic  acid  present  in  various  tanning  materials :— > 

I.  Precipitation  by  glue  or  skin : —        « 

a.  Weighing  of  the  skin  before  and  after  immersion  in  the  liquor  containing 

tannin,  the  increase  of  weight  givipg  the  quantity  of  tannic  acid. — (Davt). 

b.  Precipitation  with  gelatine  solution  of  known  strength. — (Fehlino). 
e.  Titration  by  means  of  an  aluminated  solution  of  glue. — (G.  Mulueb). 

d.  First  determine  the  specific  gravity  of  the  tannin  solution  by  means  of  an 
areometer,  next  remove  the  tannin  by  skin,  and  then  again  take  speciBe 
gravity  of  liquid,  the  decrease  being  proportionate  to  the  quantity  of  tannin 
in  the  original  liquor. — (C.  Hammer). 


TANIflNa.  513 

2.  Precipitation  of  tannin  by  acetate  of  copper,  and  estimation  of  tiiie  relation 
between  tannin  and  oxide  of  copper  in  the  precipitate  :— 

a.  Vokunetrically. — (H.  Fleck)  ;  or 

b.  By  the  gravimetrical  method. — (£.  Wolff). 

3.  Yolimietrical  estimation  of  tannin  by  acetate  of  iron. — (R.  Handtke). 

4.  Oxidation  of  tannic  acid  by  permanganate  of  potash. — (Lowknthal). 

5.  Precipitation  of  tannin  by  means  of  cinchonin,  the  solution  of  which  is  tinged 
red  by  means  of  fnchsin.  i  grm.  of  qneroitannic  acid  requires  07315  grm. 
dnchonine,  equal  to  4*523  grms.  of  crystallised  neutral  sulphate  of  cinchonin. — 
(B.  Waonbb). 

TiM  suiii.  The  skins  of  almost  all  quadrupeds  might  be  converted  into  leather  by 
tanning ;  but  the  tanner  chiefly  prepares  his  leather  from  the  hides  of  cattie,  occasion- 
ally from  the  hides  of  horses  and  asses  as  well  as  of  pigs.  The  quality  of  the 
hides  not  only  depends  upon  the  kind  of  animal,  but  also  upon  its  fodder  and  mode 
of  living,  The  hides  of  wild  cattie  yield  a  more  compact  and  stronger  leather  than 
the  hides  of  our  domesticated  beasts ;  among  these  the  stall-fed  have  better  hides 
than  the  meadow-fed  or  grazing  cattie.  The  thickness  of  the  hide  varies  consider- 
ably on  di£ferent  parts  of  the  body,  the  thickest  part  being  near  the  head  and  the 
middle  of  the  back,  while  at  tiie  belly  the  hide  is  thinnest.  These  differences  are 
less  conspicuous  in  sheep,  goats,  and  calves.  As  regards  sheep  it  would  appear  that 
their  skin  is  generally  thinnest  where  their  wool  is  longest. 

The  hides  of  bulls  and  oxen  yield  the  best  and  stoutest  leather  for  soles.  In  the 
raw — suntanned — state,  and  with  the  hair  still  on,  the  hides  are  termed  *'  green  "  or 
*'  fresh."  Fresh  or  green  hides  are  supplied  to  the  tanners  by  the  butchers,  or  are 
imported  eitiier  dry  or  salted.  A  hide  weighing  in  fresh  state  from  25  to  30  kilos. 
loses  by  drying  more  than  half  its  weight.  South  America  (Bahia,  Buenos  Ayres,  &c.) 
exports  a  large  quantily  of  hides,  both  dry  as  well  as  salted  and  cured  by  smoking. 
The  hides  of  cows  yield  generally  an  inferior  grained  leather ;  but  South  American 
oow  hides  may  be  worked  for  light  sole  leather.  Calves'  hides,  again,  are  thinner, 
bnt  when  well  tanned,  curried,  and  dressed,  yield  a  very  soft  and  supple  upper 
leather  for  boots  and  shoes.  Horse  hides  are  only  tanned  for  saddlery  purposes, 
while  sheep-  and  goat-skins  and  the  skins  of  lambs  are  tanned— or  more  generally 
tawed — ^for  the  purpose  of  making  wash-leather,  maraquin,  glove-leather,  book- 
binders'-leather.    Pigs'  hides  and  seals'  skins  are  tanned  for  saddlery  purposes.^ 

TiM  BcTBiBi  opentioiia.  The  scvenJ  operations  of  the  oak  bark  tanning  process  may  be 
reduced  to  three,  viz. : — ^A.  The  cleansing  and  dressing  of  the  hide  on  the  hair  and 
flesh  side ;  in  other  terms,  the  separation  of  the  corium  from  the  other  integuments. 
B.  The  true  tanning.  C.  The  currying  and  dressing  operation,  by  which  the 
tanned  hide  becomes  a  saleable  article.  These  three  operations  are  again  subdivided 
as  follows : — 

A.  The  cleansing  of  the  hide : — 

1.  Steeping  and  macerating  the  hide. 

2.  Dressing  the  flesh  side. 

3.  Dressing  the  hair  side. 

4.  The  swelling  of  the  cleansed  hide. 

B.  The  tanning  of  the  cleansed  hide,  performed  either  by  placing  it  in  tanks  or 
pits  with  oak  bark  and  water^  or  in  a  liquor  of  these  previously  prepared,  or  by  tha 
so-called  quick  method. 

211 


5Z4  CHEMICAL  TBCENOLOOT. 

G.  Tlie  dressing  and  currying  of  the  tanned  hides,  hy  which  is  imdentood  all  ft» 
operations  which  tend  to  improve  the  compactness  of  textnre,  or  giTe  a  better  grnn 
and  better  appearance  to  the  leather,  together  with  softness,  tonghnesB,  eajfpLeoem, 
and  colour. 

OMuidJifftiMmdM.  A.  This  operation  includes: — i.  The  steeping  or  nunyraling  of 
the  hide  in  water  for  the  purpose  of  roidering  the  texture  uniformly  soft  and  m 
supple  that  it  may  be  bent  without  danger  of  cracking,  while,  on  the  other  hand,  this 
steeping  also  effects  a  cleansing  of  the  hide  by  removing  from  it  blood  and  dirt  Tkm 
fresh  hides  of  recently  slaughtered  aniwift^lg  require  a  maceration  in  water  for 
two  or  three  days,  but  dried,  cured,  or  salted  hides  have  to  be  left  macentiiig  for  i 
eight  to  ten  days.  This  operation  should,  if  possible,  be  carried  on  in  a  stream  ef 
water ;  but  if  Uiere  is  no  convenience,  then  the  hides  are  placed  in  large  tanks;  in 
either  case  the  hides  are  taken  out  twice  daily  and  put  back  into  the  water  again. 
ciMiiiiiiffofth«FtaiiBid«.  When  the  hides  have  become  quite  soft,  they  are^* 
(2)  cleansed  or  dressed  on  the  flesh  side  by  being  placed  with  the  hair  side  down- 
wards on  a  **  tree,"  a  stout  semi-circular  plank,  one  end  of  which  is  placed  en  the 
ground  while  the  other  is  supported  by  a  trestle,  so  that  the  plank  is  in  a  atk^aag 
position.  The  workman  has  a  so-called  dressing-knife,  a  tool  to  which  handlea  are 
fastened,  and  which  is  bent  so  as  to  form  a  slight  curve ;  with  this  knife  he  ahaTes, 
or,  as  it  were,  planes  off,  from  the  hide  all  fSatty  tissue  and  integuments  iMiiich  ars 
situated  between  the  hide  and  the  muscles.  At  the  same  time  the  water  is  aqueeied 
out  of  the  hide  to  some  extent 

After  a  preliminary  or  first  dressing,  the  hides  are  again  placed  for  twenty-fow 
hours  in  water;  the  dressing  and  planing  is  then  quite  finished,  and  the  hides 
having  been  well  washed,  are  left  to  drain  on  the  tree  ready  for  removing  the  hair. 
In  some  instances  the  hides  are  washed  by  the  aid  of  *'  possing-sticks,'*  and  **  fnlM  ** 
by  means  of  machinery,  by  which  the  operation  is  greatly  shortened,  so  much  ao, 
that  two  to  three  days  suffice,  instead  of,  as  is  usual  by  the  aid  of  manual  labour, 
eight  to  ten  days. 
dMiidiiic  the  Hair  0id«.  3.  This  Operation  aimrat  the  removal  frtim  the  oorium  oC  the 
epideiinis  and  hair-containing  integuments.  As  the  hair  and  integuments  o<m2ieeted 
therewith  are  very  firmly  attached  to  the  corium,  the  removal  can  only  be  saS^y 
proceeded  with,  so  as  to  leave  the  corium  uninjured,  by  the  employment  oC  a 
menstruum  which  more  or  less  dissolves  and  causes  the  epidermis  to  swell  up.  For 
this  purpose  the  hides  are  usually  placed  in  lime-pits,  the  effect  of  the  lime  being  tba 
partial  dissociation  (in  an  anatomical  sense)  of  the  epidermis,  so  that  it  and  the 
hairs  may  be  readily  removed  by  mechanical  means* 

The  effect  is  usually  obtained  by — a.  Sweating;  b.  Liming;  e.  Applicatkn  of 
rusma  or  compounds  of  sulphuret  of  calcium. 

a.  A  semi-putrefoctive  fermentation  called  sweating  is  employed  in  the  eaae  of 
thick  hides,  such  as  serve  for  sole  leather,  which  are  not  placed  in  lime  owing  to  tiie 
fiftct  that  it  cannot  be  completely  removed,  and  would  render  the  leather  hritUe. 
The  operation  of  sweating  consists  in  placing  the  hides  one  upon  the  other,  the  flesh 
side  turned  inward,  some  salt  or  crude  wood  vinegar  having  been  first  rubbed  in,  in 
a  tank,  or  box,  which  can  be  closed  so  that  the  heat  generated  by  the  fermentation 
which  sets  in  may  be  confined  as  much  as  possible  to  aid  the  action.  As  soon  aa  tiie 
evolution  of  ammonia  is  perceptible,  the  hides  are  ready  for  the  removal  of  the  hair, 
which  is  shaved  off,  together  with  the  epidermis,  by  tiie  aid  of  the  dressing-kiiife. 


TANNING.  515 

Instead  of  cansing  the  sweating  to  be  done  by  fennentation,  the  hides  are  Bometimes 
hung  on  hitha  in  rooni6  either  heated  by  means  of  steam  or  by  fire.  A  temperature 
of  50**  to  50"  should  be  kept  up,  together  with  a  good  current  of  steam,  by  which  the 
epidermis  is  thoroughly  softened.  In  order  to  prevent  any  iiguzy  to  the  corium,  the 
liides  are  sometimes  submitted  to  what  may  be  termed  a  cold  sweating  process, 
consisting  essentially  in  placing  the  hides  in  water-tight  tanks,  in  which  there  is  a 
csonstant  current  of  fresh  water,  the  temperature  being  kept  at  6**  to  12*^.  The  hides 
thus  submitted  to  a  constantly  moist  atmosphere  become,  after  six  to  twelve  days, 
"without  any  perceptible  putrefaction,  fitted  for  the  removal  of  the  epidermis  and  hair. 

b.  The  liming  of  the  hides  not  only  prepares  them  for  the  removal  of  the  hair,  but 
also  saponifies  the  fatty  matter ;  and  though  the  lime  soap  thus  formed  is  insoluble  in 
water,  it  is  removed  by  subsequent  mechanical  and  chemical  operations.  The 
operation  of  liming  is  carried  on  in  pits,  into  which,  along  with  milk  of  lime,  the 
bides  are  placed  so  as  to  be  quite  covered.  Usually  several  (three  to  five)  pits  are  in 
use  at  once,  each  of  which  contains  a  different  quantity  of  lime.  That  the  milk  of 
lime  should  be  frequently  stirred  in  these  pits  is  of  course  evident.  The  hides 
remain  in  the  lime-pits  for  three  to  four  weeks. 

c.  The  very  thin  skins  of  the  smaller  ftnimitla  wUI  neither  sustain  sweating  nor 
liming  and  are  therefore  treated  with  rusma,  a  salve-like  mixture  of  orpiment, 
X  part  with  2  to  3  parts  of  slaked  lime.  By  the  rubbing  in  of  this  mixture  on  the 
bair  side  of  the  skins,  the  hairs  are  so  softened  as  to  make  their  removal  an  easy 
matter.  Bottger  states  that  hydrosulphuret  of  calcium  has  the  same  effect ;  hence 
the  lime  of  the  purifiers  of  the  gas-works  has  been  of  late  years  frequently  employed 
for  treating  hides  as  well  as  skins,  with  the  additional  advantage  of  yielding  a  better 
leather. 

stetvptag  off  iiM  Ban,  As  soon  ss  the  hides  are  sufficiently  prepared  to  admit  of  the 
removal  of  the  hair  and  epidermis,  they  are  stretched  out  on  the  tree  and  the  integu- 
ments peeled  off  by  the  aid  of  the  blunt  dressing-knife.  In  order  to  give  to  the 
dressing-knife  a  better  grip,  the  workman  strews  some  Gne  sand  on  the  hide,  and  if 
he  has  to  deal  with  very  heavy  and  thick  hides,  uses  a  large  and  rather  sharp  knife. 
"When  the  hair  and  the  epidennis  have  been  removed,  the  hides  are  again  washed  and 
macerated  in  water,  and  after  this  dressed;  that  is  to  say,  reduced  as  much  as 
possible  to  an  equal  thickness,  while  the  waste — ^tail,  leg,  and  head  pieces — are  cut 
off  and  the  hide  planed,  thereby  losing  some  10  to  12  per  cent  in  weight. 

si*«]iiagth«mdM.  The  aim  of  this  operation  is  to  remove  the  lime,  and  also  to 
render  the  corium  more  capable  of  readily  absorbing  the  tan  materials.  This  end  is 
attained  by  placing  the  hides  in  a  so-called  sour  bath,  made  of  refuse  malt  and 
bran,  which  by  add  fermentation  yields  as  active  priaciples  propionic,  lactic,  and 
butyric  adds. 

The  lime  is  removed  from  the  dressed  hides  when  placed  in  this  add  liquid,  and 
the  lime-soap  present  becoming  decomposed,  the  fatty  adds  thus  set  free  float  on  the 
surface  of  the  liquid.  The  soluble  lime  salts  are  completely  removed  from  the 
bides  by  a  subsequent  thorough  washing  with  water.  The  thickness  of  the  hides  is 
doubled  by  the  swelling  action  of  the  add  liquid,  aided  by  the  mechanical  action  of 
the  carbonic  add  evolved  from  the  carbonate  of  lime  depodted  within  the  fibres  of 
the  hides;  while  the  butyric  add  fermentation  distends  the  fibres  of  the  hides  by  the 
gases  thereby  evolved.  When  the  hides  have  not  been  treated  with  lime  but  have 
been  submitted  to  a  *'  sweating,*'  they  do  not  require  the  add  bath,  but  are 


5i6  CEEMICAL  TECHNOLOGY. 

simply  placed  in  water  for  the  purpose  of  swelling  them.     Yet  the  sour  twth  b 
preferable  owing  to  its  more  regular  action. 

Instead  of  using  the  preceding  mixture  for  the  purposes  of  removing  the  lime  and 
of  swelling  the  hides,  they  are  often  placed  in  add  tan  liquor  (red  tan  liquor),  thai  is 
to  say,  a  liquor  containing  exhausted  oak  bark  solution  which  has  serred  tx 
tanning;  this  liquor  appears  to  contain  also  large  quantities  of  lactic  and  hotyrie 
acids.  The  dressed  hides  are  first  placed  in  a  diluted  red  liquor  and  then  in  a 
stronger  liquor,  this  operation  taking  some  1 2  to  14  days.  Macbride  and  Segaia 
have  proposed  to  substitute  veiy  dilute  sulphuric  acid  (i  in  1500),  but  althou^  by 
the  use  of  this  acid  the  operation  of  swelling  is  rendered  far  more  rapid,  the  qualitf 
of  the  leather  is  impaired.  Phosphates  and  animal  excreta  which  contain  a 
large  quantity  of  uric  acid,  such  as  that  of  dogs  and  of  pigeons,  have  been,  and  in 
many  cases  are  still,  used  for  the  purpose  of  swelling  hides,  especially  akinB  of  siheep, 
calves,  and  goats. 

The  Tannine.  B.  The  main  object  of  the  operations  just  described  is  first  to  ohtain 
the  corium  as  much  as  possible  separated  from  the  other  integuments  and  textnrea 
belonging  to  the  skin,  and  next  to  render  the  corium  as  much  as  possible  permeable 
by  the  liquor  in  which  the  tannin-containing  vegetable  matter  is  dissolved.  In 
practice  it  is  taken  for  granted  that  a  dry  hide  gains  one-third  in  weight  by  being 
converted  into  leather,  consequentiy  it  absorbs  that  quantity  of  tannin. 

The  impregnation  of  the  fibres  of  the  hide  or  skin  with  tannin  is  effected  by  two 
different  methods,  viz. : — 

1.  By  placing  the  hides  between  layers  of  oak  bark  chips  in  a  tank,  so-ealied 
tanning  in  the  bark ;  or 

2.  By  immersiDg  the  hides,  first  in  a  dilute,  and  again  in  a  concentrated  sqneoiBi 
infusion  of  oak  bark. 

Tanning  in  tiM  Bark.  I.  This  mode  of  tanning  is  at  the  present  time  confined  to  heavy 
hides  intended  for  sole  leather.  The  tanks  in  which  this  operation  is  earned  on  an 
made  of  wood,  either  oak  or  fir,  are  of  course  watertight,  and  are  usually  sunk  into 
the  soil.  Brick  cisterns  lined  with  cement  are  occasionally  used,  but  are  objec- 
tionable, at  least  when  recentiy  built,  on  account  of  the  deteriorating  action  of  the 
lime  and  cement  upon  the  oak  bark.  In  some  parts  of  (Germany  tanks  constructed 
of  slabs  of  slate  or  sandstone  are  used.  Each  tank  has  sufficient  capacity  to  cantain 
50  to  60  hides.  On  the  bottom  of  the  tank  is  first  placed  a  layer  of  exhausted  (spent) 
tan,  and  upon  this  a  layer  of  some  3  centimetres  in  thickness  of  fresh  bark,  then  a 
hide  with  the  hair  side  downwards,  again  a  layer  of  fresh  oak  bark,  and  again  a  hide, 
alternately  until  the  tank  is  nearly  fiUed,  care  being  taken  to  put  some  more  bazk  ob 
the  thickest  part  of  the  hides,  and  to  fill  not  only  all  interstices  with  bark,  bat  to  pot 
on  the  top  a  layer  of  some  30  centimetres  thickness  of  spent  tan.  Water  is 
next  poured  into  the  tank  until  it  stands  a  few  centimetres  above  the  topmost  hide ; 
this  having  been  done,  a  lid — ^in  England  loose  planks — ^is  placed  on  the  tank, 
the  contents  of  which  are  left  undisturbed  for  some  time.  When  Valonia  floor 
is  employed  with  the  oak  bark  only  half  the  quantity  of  the  latter  is  necessaiy. 

The  hides  are  left  in  "  the  first  bark"  for  8  to  10  weeks,  the  period  being  a  little 
shortened  if  Valonia  flour  is  also  used.  Before  all  the  tannin  has  been  absorbed,  and 
as  a  consequence  the  formation  of  volatile  and  odorous  acids  (valerianic,  bu^ric,  Ac.) 
has  commenced,  the  hides  are  transferred  to  another  tank  and  again  placed  between 
alternate  layers  of  fresh  bark,  the  only  difference  in  the  arrangement  being  that  the 


TANNIN0.  5^7 

liides  whicH  were  first  placed  on  the  top  are  now  laid  at  the  bottom  of  the  tank. 
The  hides  are  now  left  for  three  to  four  months,  so  as  to  thoroughly  absorb  the 
tannin.  They  are  next  placed  for  some  four  to  five  months  in  another  tank  which 
contains  less  bark.  In  the  case  of  veiy  heavy  and  thick  hides  the  process  is 
repeated  four  or  even  five  and  six  times.  The  quantity  of  bark  required  for 
obtaining  thoroughly  well-tanned  leather  depends  partly  on  the  quality  of  the  bark, 
and  somewhat  on  the  condition  of  the  hides.  Usually  the  tanners  reckon  that  the 
quantity  of  bark  required  amounts  to  four  to  sixj  times  the  weight  of  the  dry  hides; 
and  taldng  the  weight  of  these  at  an  average  of  20  kilos. — 

•  • 

For  the  first  tank  there  will  be  required  40  kilos,  of  bark. 

„    .  second  „        „        „  35  „ 

„      third  „        „        „  30  „ 

105  kilos,  of  bark. 

A  dried  and  well-tanned  hide  weighs  about  22  kilos.,  or  10  to  12  per  cent  more  than 
the  dry  raw  hide.  A  thoroughly  tanned  hide  exhibits  when  cut  with  a  sharp  knife  a 
uniform  texture  free  from  fleshy  or  horny  portions,  wliile  the  grain  on  the  hair  side 
ahould  not  on  being  bent  slowly  exhibit  signs  of  cracking. 

TunJngtaiLiiaor.  2.  The  thinner  hides,  and  indeed  most  skins  (when  tanned,  aa 
distinguished  from  tawing),  are  placed  in  infusions  of  the  tannin-containing  material. 
There  are  various  methods  in  use  for  this  operation,  which  is  based  mainly  upon  a 
thorough  uniform  swelling  of  the  hides,  so  that  when  these  are  placed  in  weak 
liquors  the  tannin  may  penetrate  readily  and  uniformly.  The  hides  are,  in  fact,  very 
gradually  tanned.  When  taken  from  a  liquor  the  fluid  is  forced  by  mechanical 
means  out  of  the  hides  before  they  are  placed  in  a  stronger  liquor,  this  liquor 
being  obtained  by  exhausting  the  tanning  materials  by  the  aid  of  cold  water.  The 
thinner  kinds  of  hides  are  thoroughly  tanned  in  seven  to  eight,  the  heavier  hides  in 
eleven  to  thirteen  weeks. 

QBkkTaniiiiic.  Many  methods — some  quite  impracticable  and  most  of  them 
thoroughly  irrational — have  been  proposed  for  converting  hides  into  leather  in  a  very 
short  time.  Of  these  di£ferent  methods  we  briefly  mention  the  following: — i.  The 
hide  is  simply  placed  in  an  infusion  of  the  tannin-containing  material — Macbride's 
process,  improved  by  Seguin  (1792).  Application  of  hydrostatic  pressure  to  force  the 
liquor  through  the  hides,  kept  from  contact  with  each  otber  by  a  stout  woollen 
tissue.  2.  Circulation  of  the  tannin-containing  fluid,  several  tanks  being  connected 
together  by  means  of  pipes,  and  the  liquor  being  forced  through  the  tanks  by  means 
of  pumps  (Ogereau,  Sterlingue,  and  Tumbull's  methods.  3.  The  hides  are  sewn 
together  so  as  to  form  sacks,  which  are  filled  with  oak  bark  chips  and  water  and  then 
placed  in  an  aqueous  solution  of  cutch,  to  which,  in  order  to  increase  its  spedfie 
gravity,  coarse  molasses  is  added — ^Tumbull's  method  by  increased  endosmose. 
At  the  time  this  mode  of  proceeding  was  brought  forward,  the  difEusion  of  liquids 
by  dialysis  (discovered  by  Graham  in  1861)  was  unknown.  4.  Motion  of  the 
liides  in  the  tannin-containing  liquids,  the  hides  being  placed  in  a  cylinder 
constructed  of  wooden  laths  so  as  to  leave  open  spaces  between  them.  This 
cylinder  is  immersed  horizontally  in  the  liquid  to  a  greater  or  less  depth,  so  that  in 
every  revolution  the  hides  are  alternately  in  and  out  of  the  liquid — ^Brown,  Squire, 
and  C.  Knoderer's  methods.    5.  Application  of  mechanical  pressoxe  to  the  hides, 


5x8  CHEMICAL  TECBNOLOOY. 

which  haTing  been  from  time  to  time  removed  from  the  tanning  tanka^  are  pUeed 
upon  perforated  planks,  and  either  pressed  under  a  heavy  roller  or  are  placed  in  a 
preBa---Jone8,  Nossiter,  Cox,  and  £[erapath's  method.  6.  Application  of  hydroalatie 
pressure  for  the  purpose  of  causing  the  tan-liquor  to  penetrate  the  hides,  which  are 
sewn  together  so  as  to  form  bags,  which  having  been  filled  with  oak  bark  liqoor,  are 
placed  in  suitably  oonstracted  vessels,  so  that  l^draulic  pressure  may  be  applied 
without  fear  of  bursting  the  bags ;  or  the  hides  are  fsistened  by  means  of  screws  and 
bolts,  placed  in  a  framework  which  is  immersed  in  a  well-constructed  dstem  filled 
with  tan-liquor,  hydraulic  pressure  being  applied— Drake,  Chaplin,  and  Santdet's 
«nethods.  7.-  Snyder's  method  of  punctation,  consisting  in  perforating  the  hide  over 
its  whole  surface,  the  punctation  being  effected  by  sharp  needles,  so  as  to  constitata 
artificial  pores.  The  experiments  of  Knapp  have  proved  the  thorou^  irratiiHia]]^ 
of  this  plan,  it  having  been  found  that  the  hide  is  so  permeable  to  tannin-liquor  thai 
a  piece  of  calf-skin  when  placed  in  a  solution  of  tannin  of  the  oonsisiencj  of  Bjnf 
is  thoroughly  well  tanned  in  about  an  hour's  time.  8.  Application  of  a  vacm 
by  placing  the  hides  in  a  vessel  firom  which  the  air  may  be  withdrawn  by  the  aid  of 
air-pumps ;  tan-liquor  having  been  forced  into  the  vessel,  the  air  is  re-admitted  and 
again  withdrawn — Enowly  and  Enewsbury's  plan.  Knoderer  has  recently  liDinid 
that  by  a  judicious  combination  of  the  vacuum  method,  followed  by  motiaii  an^ 
fulling  of  the  hides  in  the  tan-liquor,  the  operation  of  tanning  is  much  shortened. 
The  reader  should  bear  in  mind  that  the  methods  here  alluded  to  are  not  now 
in  general  use. 

Dn^B^^nTfnff  When  the  hides  have  been  converted  into  leather  by  the 
processes  described,  they  are  not  by  any  means  fit  for  use  nor  ready  for  sale  as 
a  finished  material,  but  require  to.be  dressed,  or,  as  it  is  technically  termed,  coitiedt 
an  operation  not  necessarily  performed  by  the  tanner — at  least,  never  so  in  KngtaTil 
and  France.  The  several  operations  are  not  similar  for  all  kinds  of  leather, 
but  depend  to  some  extent  upon  the  use  to  which  it  is  intended  to  be  put.  For 
instance,  sole  leather  is  submitted  simply  to  a  process  the  object  of  which  is 
to  render  it  sufficient^  stiff  and  compact,  so  as  not  to  alter  its  shape  by  wear. 

Bole  Leauittr.  The  drcsslug  or  currying  of  this  kind  of  leather  consists  mainly  in  sub- 
mitting it  to  a  mechanical  operation  of  hammering,  by  which  the  mntfirial  is 
rendered  more  compact.  As  soon,  therefore,  as  the  hides  are  taken  firam  the  tanning 
tanks,  the  adhering  spent  tan  is  brushed  off  with  a  broom,  after  which  the  hide 
is  dried  in  a  cool  place,  and  when  dry  laid  flat  upon  a  polished  stone  slab,  and  then 
beaten  with  wooden  or  iron  hammers,  an  operation  iu  large  estaUishmenla  per- 
formed by  hammers  moved  by  machinery. 

upv«LMik«r.  The  dressing  of  this  kind  of  leather,  chiefly  used  by  sadlera  and 
boot  and  shoe  makers,  is  a  far  more  complicated  process,  and  depends  in  a  great 
measure  on  the  use  for  which  the  leather  is  intended.   The  first  of  these  operationa  is 

hm  Paring,  the  paring  or  whitening,  which  means  the  cutting  away,  by  the  aid  of  a 
tanner's  shaving-knife,  of  all  portions  of  the  hide  which  are  too  thick,  so  thai 
the  whole  hide  may  be  made  of  uniform  thickness.  This  operation  is  canisd 
on  upon  the  tanner's  "wooden  leg,"  the  hide  being  placed  with  the  hair-side 
downwards.  When  goat,  lamb,  sheep,  or  calf-skins  are  to  be  pared,  they  are 
placed  on  a  polished  slab  of  marble,  and  having  been  well  stretched,  the  raw  or 
projecting  parts  are  cut  off  with  the  tamier's  shaving-knife. 


TANNING.  5x9 

The  Bttmpiiig  or  BmiwtMBg.  The  aim  of  this  Operation  is  similar  to  that  of  the  former, 
and  more  particularly  is  employed  in  the  case  of  leather  intended  for  making  gloves. 
The  leather  is  first  dried  and  next  fixed  on  the  "  perching-stick,"  one  end  of  the  skin 
remaining  free,  tlie  other  being  taken  hold  of  by  the  operator  with  a  pair  of  forceps. 
The  skin  having  been  stretched,  the  perching-knife,  a  highly  polished  somewhat 
convex  steel  disc  of  18  to  30  centime,  diameter,  and  provided  in  the  centre  with  an 
opening  fitted  with  a  piece  of  leather  serving  as  a  handle,  is  brought  into  use, 
the  portions  of  the  skin  which  require  to  be  pared  off  being  usually  indicated  by 
l>eing  rubbed  over  with  chalk. 

ondniacthaLMtiMr.  As  in  consequenco  of  the  drying  of  the  leather  the  grain  has 
'become  flat,  smooth,  and  unequal,  it  is  raised  by  an  operation  performed  by  means  of 
the  pommel,  also  termed  the  graining-  or  crimping-board,  a  piece  of  hard  wood 
30  centims.  in  length  by  10  to  12  centime,  breadth,  flat  and  smooth  on  the  top,  but  on 
the  opposite  side,  in  fhe  direction  of  the  length,  somewhat  curved,  so  that  it  is 
thickest  in  the  middle,  this  part  being  provided  with  parallel  notches,  which  are 
occasionally  sharpened  by  means  of  a  file ;  a  leather  strap  is  &stened  to  the  top  as  a 
handle.  The  leather  to  be  grained,  having  been  placed  on  the  dressing-table,  la 
fiistened  to  the  edge  of  the  wooden  board  by  means  of  iron  clamps,  and  those  portions 
of  the  leather,  the  grain  of  which  has  to  be  raised,  having  been  somewhat  bent,  are 
rubbed  with  the  pommel  so  as  to  render  the  grain  uniformly  vigible, 

poiiihii«withPiiiBioc>8t«iM. .    Such  kinds  of  leather  as  require  no  grain  (for  instance,  the 

leather  u^  in  carding  machines)  after  having  been  pared,  are  moistened  and  then 

rubbed  over  on  both  sides  with  pumice-stone,  being  thus  rendered  smooth ;  while 

leather  which  requires  a  higher  gloss,  such  as  the  coloured  leathers,  are  treated  with 

■^J5PjgjJJJJ5f»/gJg«y  a  pommel  made  of  cork,  by'  which  the  leather  is  caused  to 

assume  a  vdvety  appearance.    Again,  if  a  still  higher  gloss  is  required,  the  leather 

""""^sISKtai to?^^*  is   first   smoothed,  or  rather  ironed,   with  iron  or   copper 

**  sleekers,*'  and  next  polished  with  glass  sleekers,  a  stout  cylindrical  piece  of  glass, 

o'3  metre  in  length  by  10  centime,  diameter,  the  leather  being  placed  on  a  tanner's 

Booiiiff.  wooden-leg.    Leather  intended  for  saddles,  in  order  to  impart  to  it  the 

appearance  natural  to  hog's  leather,  is  passed  through  rollers,  the  surfaces  of  which 

are  provided  with  blunt  points,  which,  being  forced  into  the  leather,  give  to  it  the 

desired  appearance. 

luitaiiiff  ofl.  In  order  to  remove  from  the  leather  any  creases  and  other  inequalities 
of  surface,  it  is  damped,  and  then  smoothed  with  a  flattening-iron,  or,  if  the  skins  are 
thin,  with  a  piece  of  horn  provided  with  blunt  teeth. 

OflMrinf.  When  the  upper  leather  is  required  to  be  very  supple  and  soft,  it  is 
greased ;  that  is  to  say,  it  is  rubbed  with  a  mixture  of  fish-oil  and  tallow,  or  better, 
vnth  the  peculiarly  modified  fish-oil  which  has  been  used  in  "  chamoising,**  having 
heen  recovered  by  the  aid  of  a  solution  of  potash  horn  the  chamois  leather  sktns. 
The  hides  to  be  greased  are  first  moistened,  and  having  been  rubbed  with  the  greasy 
matter,  are  dried  in  heated  rooms,  so  that  the  fiitty  materials,  by  actually  combining 
vnth  the  hides,  become,  as  it  were,  tanned  and  tawed  at  the  same  time.  The  greasing 
is  therefore  not  simply  an  operation  of  dressing,  but  in  reality  a  second  tanning 
(technically  tawing)  process. 

The  black  colour  usually  seen  on  the  surface  of  leather  required  for  saddlery  and 
boot-making  is  imparted  to  the  hides  by  rubbing  them  with  a  fr«sh  solution  of 
oak  bark  and  then  sponging  them  over  with  a  solution  of  copperas  to  which  some 


520  CHEMICAL  TECHNOLOGY. 

bine  vitriol  has  been  added ;  the  hides  are  then  again  dressed,  and  laatlj  mliM 
with  a  paste  made  of  fish-oil,  tallow^,  lamp-black,  yellow  wax,  soap,  and  copperas,  the 
object  of  this  operation  being  to  protect  the  leather  from  the  injniious  e£Eeets  of  the 
shoe-blacking,  which  usually  contains  sulphuric  acid.  (For  a  shoe-blacking  withoat 
acid  see  "  Chemical  News,"  vol.  xxiv.,  p.  120).  Finallj,  the  leather  is  painted  cr 
brushed  over  with  a  mixed  tallow  and  glue  solution,  and  then,  having  been  polished 
again  with  glass,  is  ready  for  sale.  In  order  to  keep  leather  supple  and  soft,  it  is  beai 
to  rub  it  with  a  mixture  of  fish-oil  and  lard. 

Tofts.  Bnada  Leatiiar.  Under  the  name  of  yufts  is  understood  a  pecoliar  kind  d 
leather,  usually  of  a  red  or  black  colour,  which  is  very  water-tight  and  strong.  Thii 
kind  of  leather  used  to  be  made  exclusively  in  Russia,  whence  it  is  obtained  in  laige 
quantity,  the  name  being  derived  from  the  Bussian  Jufti,  signifying  a  pair,  and 
apparently  due  to  the  fact  that  in  tanning  the  hides  are  sewed  together  in  pairs. 
The  hides  usually  prepared  for  Hussia  leather  are  those  of  young  cattle;  somedmes, 
however,  the  hides  of  horses  and  the  skins  of  sheep,  goats,  and  calves  are  employed. 
The  operations  for  preparing  yufti  are : — i.  The  cleansing  of  the  hides,  performed  in 
the  usual  manner  with  lime.  2.  The  swelling  of  the  hides  in  an  acid-bath  prepared 
with  malt,  exhausted  tan-liquor,  or  with  kaschka  (excreta  of  dogs  rubbed  np  with 
water).  3.  The  tanning,  not  performed  with  oak  bark,  but  with  the  barks  of  various 
kinds  of  willows,  fir  and  birch  bark  also  being  used.  The  dressed  hides  are  first 
placed  for  some  days  in  partly  exhausted  bark,  and  are  then  put  into  the  tannfttg 
tanks  along  with  bark  (as  above  described),  or  are  sometimes  placed  in  a  waim 
infusion  of  the  tannin-containing  materials.  The  tanning  continues  for  five  to  six 
weeks.  4.  The  tanned  hides  are  placed  on  the  planing-block  for  the  purpose  of 
draining,  and  are  next  impregnated  with  diggut  or  eUwIierU  oil  of  birch,  obtained  fay 
a  process  of  dry  distillation  from  birch  wood.  This  oil  contains  creosote,  phenol  (of 
a  peculiar  kind  according  to  Louginine),  and  paraffin.  It  is  rubbed  into  the  hides  on 
the  flesh  side,  and  when  thoroughly  impregnated  they  are  stretched  until  they 
become  soft  and  supple.  The  hides  are  next  rubbed  on  the  hair  side  with  a  solntUm 
of  alum,  and  then  grained  and  dried.  The  dry  hides  are  dyed  in  pairs,  sewn  together 
so  as  to  form  a  sack,  into  which  a  decoction  of  dye  material  is  poured.  Whoi 
a  red  colour  is  desired,  the  dye  is  prepared  from  sandal  wood,  there  being  added 
to  the  former  lime-water,  to  the  latter  some  potash  or  soda.  In  more  recent 
methods  the  hides  are  dyed  by  being  brushed  over  five  or  six  times  with  the  dye 
material.  The  dry  leather  is  finaUy  dressed  by  the  mechanical  operations  previously 
described.  The  use  of  yufts  for  book-binding  and  other  purposes  is  well  known. 
Owing  to  the  empyreumatic  oil  with  which  this  kind  of  leather  is  impregnated 
insects  do  not  attack  it. 

Korocoo  Leather.  By  morocco  leather  is  understood  a  kind  of  leather  which,  whoi 
genuine,  is  obtained  from  goat  or  kid  skins,  is  very  soft,  elastic,  highly  coloured,  and 
not  lacquered.  We  distinguish  between  genuine  morocco  and  the  imitation 
obtained  by  the  splitting  of  calf,  sheep,  and  other  skins,  as  chiefly  employed  in  book- 
binding. 

The  preparing  of  morocco  leather  is  undoubtedly  one  of  the  many  industrial 
discoveries  of  the  Saracens ;  even  at  the  present  day  a  great  deal  of  morocco  leather 
is  made  by  their  descendants  in  Northern  Africa  and  in  the  Levant.  The  prepara- 
tion of  good  morocco  leather  requires  veiy  great  care,  and  especially  as  regards  tbs 
preliminary  operations.    The  skins  are  deprived  of  the  hair  by  the  aid  of  lime  and 


TANNINO.  "Tax 

Bweatmg.  The  tanning  material  in  general  use  is  sumac,  the  skins  being  sewn"*  np 
so  as  to  fonn  sacks  into  which  water  is  poured  together  with  pulverised  sumac ;  by 
this  mode  of  emplo3ring  the  tanning  matter  the  operation  is  finished  in  three  days.- 
Calf  and  sheep  skin  are  very  generally  tanned  in  England  by  the  same  method. 
The  dyeing  of  morocco  leather  is  not  performed  in  the  Oriental  countries ;  the  dry 
tanned  skins  are  exported  under  the  name  of  Meschin  leather  (cuir  en  croutes)  to  be 
dyed  and  dressed  in  Europe. 

niMdivMoioeeoLMitiMr.  The  sldus  are  dyed  and  next  dressed.  The  dyeing  is  per- 
formed—  (a)  by  means  of  the  dye-vat  (for  genuine  morocco),  or  {p)  with  the 
brush  (for  imitation  morocco),  a.  The  operation  of  dyeing  with  the  vat  is  performed 
in  a  small  trough  large  enough  to  hold  one  skin,  and  filled  with  dye-liquor  at  60** 
firom  a  larger  tank.  The  workman  pours  in  no  more  of  the  dye  material  than  can  be 
conveniently  absorbed  by  the  skin,  which  is  continually  moved  to  and  fro.  The 
dyed  skins  are  laid  out  flat,  and  from  two  to  four  dozen  placed  one  upon  the  other, 
^e  dyeing  operation  is  repeated  several  (three  to  five)  times,  care  being  taken  to 
turn  tiie  heap  over  so  Uiat  the  undermost  skin  is  placed  on  the  top  of  the  heap 
previous  to  beginning  the  dyeing  operation  again.  The  dyed  skins  are  washed  in 
vater  and  next  dressed.  P.  The  imitation  morocco  is  dyed  by  the  dye-liquor  being 
uniformly  brushed  over  the  skins  ;  tliese  having  been  first  stretched  on  a  table,  the 
dye-liquor  is  brushed  over  more  than  once  so  as- to  produce  a  uniform  hue.  The 
effect  of  the  dyeing  is  greatly  enhanced  by  the  dressing  of  the  skins  and  the  fine 
grain  given  to  them.  The  dyed  skins  are  first  rubbed  on  the  hair-side  with  linseed 
oil  applied  by  means  of  a  piece  of  flannel.  The  calendering  or  glazing  by  machinery 
is  the  next  operation,  after  which  the  peculiar  appearance  of  the  surface  is  imparted 
by  means  of  strong  pressure  or  so-cblled  platting.  Yellow  skins  are  not  glazed» 
because  their  colour  would  thereby  become  a  brown.  The  aniline  colours  are  now 
largely  employed  in  dyeing  skins. 

copdwaia.  cordo?sii  LMther.  This  diflers  from  morocco  only  by  being  prepared  from 
heavy  skins,  and  by  retaining  its  natural  grain  or  not  being  platted.  It  is  usually 
met  with  dyed  red,  yellow,  or  black. 

i^Mqamd  LMther.  This  kind  of  leather,  now  largely  used  by  coach-builders  and  for 
making  shoes,  boots,  helmets  and  other  military  accoutrements,  is  an  invention  of 
the  present  time,  its  great  merit  being  its  property  of  resisting  water,  and  in  being 
supple  and  soft,  while  the  lacquer,  if  well  laid  on,  should  not  crack  nor  peel  off. 
Only  black  lacquered  leather  is  generally  met  with.  On  the  tanned,  rarely  tawed, 
bide,  which  has  not  been  greased,  is  very  uniformly  laid  a  varnish,  which  is  thick 
and  tough  while  cold  but  thinly  fluid  when  warm ;  this  having  been  done,  the  hide 
is  placed  in  a  brick-built  stove  kept  at  50%  where  the  varnish  dries  after  having 
become  so  fluid  as  to  run  uniformly  over  the  surface  of  the  leather,  which  is  placed 
quite  horizontally.  The  coloured  lacquers  are  generally  more  thinly  fluid  and  are 
dried  at  a  lower  temperature.  The  hides  chiefly  used  for  lacquering  are  cow-hides ; 
or  a  thin  hide  is  obtained  by  splitting  thick  hides  and  lacquering  them. 

The  leather  in  use  by  pianoforte-makers  for  covering  the  hammers  is  prepared  by 
a  process  usually  kept  a  trade  secret.  This  kind  of  leather  requires  to  be  soft  and 
Tery  elastic.  All  that  is  known  about  the  process  of  preparing  this  material  is  that 
it  is  obtained  by  tanning  and  tawing  (chamoising)  combined ;  the  hair  having  been 
removed,  but  not  the  epidermis,  the  hide  is  first  fulled  in  oil,  then  washed  in  ley, 
bleached  in  the  sun,  and  next  tanned  in  a  tepid  oak  bark  infusion.    Danish  leather 

2  N 


529  CHEMICAL  TBCBN0L007. 

is  prepared  by  tanning  sheep,  goat,  kid,  and  lamb  akins  with  willow  baik ; 
leather  being  chiefly  used  for  gloves.    It  is  distinguished  by  its  strength,  sappLenen^ 
and  bright  colour. 

n.  Tawing, 

^'^^teSSSlSf ° ^      This  mode  of  preparing  leather  is  based  upon  the  peenliaf 
action  of  the  salts  of  alumina  upon  skins,  not  hides  generally. 

Four  modifications  of  tawing  are  known,  viz. : — i.  Ckxmmon  tawing.  This 
operation  extends  only  to  thin  skins,  such  as  slieep  and  goat  akin,  &c.y  which  an 
treated  only  with  alum  and  common  salt  without  the  application  of  oiL  2.  Hunga- 
rian tawing  process.  Heavier  hides  not  treated  with  lime  are  tawed  and  next 
chamoised.  Klemm's  method  of  preparing  fatty  leather  is  somewhat  similax  to  this 
treatment.  3.  The  French  or  Erlanger  tawing  method,  by  which  the  akins  an 
prepared  for  glove-leather.  4.  Tawing  by  the  aid  of  insoluble  soaps,  according  tt> 
Knapp's  suggestion. 

Common  Tftwing.  I.  The  tawcr  obtains  sheep  skin,  or  occasionally  goat  akin,  eiths 
with  the  wool  off  or  "  in  the  wool,"  as  the  term  runs,  in  the  latter  case  greater  can 
being  required,  because  the  value  of  tlie  wool,  which,  by  careful  working  may  ba 
obtained  in  good  condition,  refunds  a  considerable  portion  of  the  expense  of  ths 
operation  by  its  sale.  The  various  operations  of  tawing  are  in  a  certain  measan 
similar  to  those  of  tanning. 

The  steeping  and  planing  is  carried  on  as  in  the  tanning  process.  The  workmaa 
places  ten  skins  on  the  planing- tree,  and  dresses  each  skin  with  the  dressing-knife  oa 
the  hair  as  well  as  on  the  flesh  side ;  next  the  wool  or  hair  is  shaved  off  after  the  skins 
have  been  first  treated  with  the  lime ;  but  when  **  in  the  wool  '*  the  skins  are  cleansed 
with  thin  lime-water,  which  is  laid  on  the  flesh  side  of  the  skin  by  a  bruah  made  of 
cow*s-hair,  so  that  the  wool  is  not  brought  into  contact  with  lime.  The  wool  is 
removed,  not  by  a  planing-iron,  but  by  means  of  a  piece  of  wood  somewhat  sharpened. 
The  wool  having  been  removed,  the  skins  are  brushed  over  with  a  mixture  of  equal 
parts  of  lime  and  sifted  ashes ;  next  the  head  and  leg  strips  of  the  skin  are  tamed 
inside.  Each  skin  is  then  folded  together  and  beaten,  in  order  to  prevent  the  wool 
being  touched  by  the  lime.  The  skins  are  left  in  this  condition  for  eight  to  ten  days 
until  the  wool  is  loosened.  The  skins  are  next  thoroughly  washed  on  the  flesh  side  as 
w  ell  as  on  the  wool  side  in  order  to  remove  the  lime  and  dirt ;  this  having  been 
done  the  wool  is  partly  pulled  off  by  the  hands,  partly  removed  by  a  blunt  tooL 
The  skins  thus  deprived  of  wool  are  placed  in  the  lime-pit  and  further  treated  as 
just  described.  In  order  to  remove  the  paste  adhering  to  the  skins  they  are,  oo 
being  removed,  placed  in  a  tank,  where,  owing  to  the  quantity  of  a.Tiimi^l  matter 
dissolved  in  the  water,  a  fermentation  has  arisen  accompanied  by  an  evolutioB 
of  ammonia.  By  the  action  of  this  alkali  a  large  portion  of  the  fatty  matter  con- 
tained in  the  skins  is  removed.  After  being  taken  from  the  lime-pit  the  skins  an 
placed  on  the  dresser's  block,  and  some  parts,  such  as  the  ears,  skin  of  tail,  portioii 
of  top  part  of  chest,  cut  off  and  thro^vn  aside  for  the  glue-boiler.  The  skins  axe  put 
over  night  to  soak  in  water,  and  then  again  placed  on  the  dressing-block  in  order  to 
be  planed  wiih.  a  blunt  iron  on  botli  sides  of  the  skin ;  this  operation  is  repeated 
after  the  skins  have  been  placed  in  a  tank  containing  water,  and  while  then 
thoroughly  beaten  with  a  heavy  wooden  '^possing-stick*'  in  order  to  remove  hma. 
In  the  subsequent  planing  tlie  lime  and  lime -soap  are  forced  out,  and  any  wool  that 


TANNWG.  523 

has  remamed  shaved  off.  In  order  to  dissolve  the  last  traces  of  lime  the  skins  are 
placed  in  an  acid-tank  containing  bran  and  water,  in  which  by  fermentation  lactic 
and  acetic  acid  have  been  formed.  These  acids  convert  the  lime  of  the  skins  into 
soluble  salts,  while  the  process  causes  the  swelling  of  the  skins,  which  thus  become 
better  adapted  to  absorb  the  tanning  materials.  The  skins  remain  in  the  sour-tank 
for  two  to  three  days.  The  tanning  material  consists  for  i  dicker  (=  10  skins)  of 
an  alum  ley,  containing  0*75  kilo,  of  alum,  0*30  kilo,  of  common  salt  dissolved  in 
22*5  litres  of  boiling  water,  i  litre  of  this  liquid  is  poured  into  a  trough,  and 
liaving  become  tepid,  each  skin  is  separately  thoroughly  washed  with  and  soaked  in 
it,  and  then  put  aside  without  being  wrung  out,  the  skins  being  placed  one  upon  the 
other  so  as  to  form  a  heap.  After  lying  thus  for  two  or  three  days,  the  skins  are 
ymmng  out  and  hung  up  to  dry  slowly  by  exposure  to  air. 

As  regards  the  theory  of  the  action  of  the  alum  ley  in  the  tawing  operation,  it  was 
formerly  believed  that  only  the  chloride  of  aluminium — ^formed  by  double  decompo- 
sition between  the  constituents  of  the  common  salt  and  the  sulphate  of  alumina  of 
the  alum  (the  alkaline  sulphates  being  considered  useless) — ^was  active,  and  that  a 
basic  chloride  of  aluminium  (aluminium  oxychloride)  combined  with  the  skin, 
there  being  left  in  solution  hydrochlorate  of  alumina.  It  was  also  known  that 
acetate  of  alumina,  if  used  instead  of  alum  ley,  was  quite  as  active  and  yielded  excel- 
lent results.  The  experiments  made  by  Dr.  Knapp,  sen.,  with  alum,  acetate  of 
alumina,  and  chloride  of  aluminium,  have  proved  that  no  decomposition  ensues 
when  the  aluminium  salt  is  taken  up  by  the  skin,  the  quantity  taken  up  being  for  the 
nndennentioned  salts  as  follows : — 

Of  alum       8*5  per  cent 

Of  sulphate  of  alumina      27*9 

Of  chloride  of  aluminium 27*3 

Of  acetate  of  alumina 23*3    „ 

The  alumina  salts  do  not,  however,  combine  with  skin  under  all  conditions  in  the 
same  quantity  as  just  mentioned,  as  experience  proves  that  the  skins  absorb  more 
when  placed  in  concentrated  than  when  in  dilute  solutions.  As  regards  the  part 
played  by  the  common  salt  in  the  preparation  of  the  alum  ley,  the  salt  is  not  there 
simply  to  bring  about  the  conversion  of  the  alumina  sulphate  into  chloride  of 
aluminium  (recent  experiments  made  by  Knapp  in  1866  have  proved  that  by^ 
employing  i  atom  of  potash  alum  and  3  atoms  of  common  salt  =  37  per  cent,  no 
mutual  decomposition  ensues),  but  the  salt  is  in  this  process  active  by  itself,  partly 
aiding  dialytically  the  action  of  the  alum,  partly  owing  to  its  property — ^possessed 
also  by  alcohol — of  withdrawing  from  animal  tissues  the  water  they  contain  suffi- 
ciently to  prevent  the  fibres  to  become  glued  together  by  the  drying  of  the  substance, 
thus  promoting  the  formation  of  leather.  The  dry  and  tawed  skins  will  be  found  to 
have  become  shrunken  and  stiff,  having  lost  much  of  their  suppleness  and  flexibility. 
In  order  to  remedy  these  defects  the  skins  previously  damped  with  water  are  sub- 
mitted to  a  mechanical  operation,  being  placed  on  the  convex  side  of  a  carved  iron, 
and  stretched  by  being  drawn  between  this  fixed  iron  and  a  movable  steel  plate, 
which  is  fitted  closely  upon  the  other.  After  having  been  thus  softened,  the  skins 
are  stretched  on  a  frame  for  some  time  to  become  dry.  When  dry  they  are  ready  for 
0Ble»  the  leather  thus  obtained  being  largely  used  under  the  name  of  white-skins  for 
Ihe  lining  of  boots  and  shoes. 


^ 


524  CHEMICAL  TECHNOLOGY. 

Hnngarkn  Tawinc  ProeeM.  2.  This  procesfl  is  distuigtlished  froitt  that  just  deMiibelf 
inasmuch  as  the  heavy  liides  of  oxen,  hufhloes,  cows,  horses,  &c.,  are  made  into 
leather  for  saddlery  and  other  purposes,  while  sometimes  also  the  skins  of  wild  bom 
and  of  other  ftTiimn.lft  are  thus  tawed  for  making  flail  strings.  The  raw  liides  are  fint 
soaked  in  water  to  remove  blood  and  imparities.  Next  the  hair  is  shared  off  bgr 
means  of  a  sharp  knife.  This  operation  performed,  the  hides  are  pat  into  an  afam 
ley,  which  for  a  hide  weighing  25  kilos.,  consists  of  3  kilos,  of  alum,  3  of  oommoD  wk, 
and  20  litres  of  hot  water.  This  liquor  when  tepid  is  poured  into  an  elliptical  tab 
in  which  the  hide  is  placed. 

One  of  the  workmen  then  jumps  into  the  tub  and  by  moving  the  hide  aBoat  widi 
his  feet  soaks  it  thoroughly  with  the  liquor,  in  which  it  is  then  left  for  at  least  n^ 
days,  the  operation  of  treading  with  the  feet  being  repeated.  The  hide  ia  now  ttkm 
from  the  tub  and  hung  up  to  dry,  and  when  di-y  is  stretched  and  *'  fatted"  in  bf 
the  following  method : — The  hide  is  wanned  by  being  held  over  a  charcoal  fire,  aad 
when  warm  is  rubbed  on  the  hair  as  well  as  on  the  flesh  side  with  molten  tallow,  of 
which  some  3  kilos,  are  used  for  eveiy  hide.  "When  thirty  hides  have  been  thus 
treated,  they  are  one  by  one  again  held  and  moved  to  and  fro  over  the  fire,  and  neit 
hung  up  in  the  open  air  to  dry.    The  tallow  partly  combines  with  the  hide. 

The  hides  thus  prepared  are  converted  into  a  leather  of  excellent  quality,  especially 
suited  for  the  harness  of  horses  and  saddlery  work  of  a  more  common  kind,  is 
which,  as  in  that  used  for  artillery  horses,  great  strength  is  required.  This  leather 
is  cheap  on  account  of  its  being  prepared  in  a  short  time. 

oiorei^iiMr.  3.  The  so-called  Erlanger,  or  French  tawing  process,  is  employed 
only  for  the  production  of  the  glac6,  or  kid  leather,  used  for  making  gloves  and  ball- 
room shoes.  The  hair  side  of  the  skins  intended  to  be  converted  into  this  leather 
is  left  unchanged,  while  as  regards  wash-leather  gloves  which  are  treated  (tanned) 
with  fish  oil  the  hair  side  is  cut  off.  The  skins  intended  to  be  converted  into  kid 
leather  are  treated  with  extraordinary  care,  and  thus  acquire  in  a  Very  hi^ 
degree  all  the  good  quality  of  alum-tanned  (or  rather  tawed)  leather.  As  these 
skins  are  often  intended  to  remain  white  or  are  dyed  with  delicate  coloors,  tiie 
greatest  care  is  taken  to  prevent  any  iigury,  as,  for  instance,  contact  with  oak  wood 
or  with  iron  while  wet. 

Two  kinds  of  skins  are  employed  for  conversion  into  the  better  varieties  of 
kid  leather ;  one  of  these,  the  more  expensive,  being  the  skins  of  young  ipoalB, 
fed  solely  with  milk,  the  other  being  lamb  skin.  £ach  of  these  skins  yields  on 
an  average  2  pairs  of  gloves.  The  leather  of  which  ladies*  ball-room  shoes  are 
made  is  obtained  from  the  hides  of  young  calves  (so-called  calf-kid).  The  pnli- 
minary  operations  of  preparing  this  leather  are  exactly  similar  to  those  already 
described  for  the  ordinary  white  leather ;  but  the  tawing  operations  are  qnita 
different,  the  skins  being  put  into  a  peculiar  mixture,  by  which  th^  are  not  onl^ 
tawed,  but  simultaneously  impregnated  with  a  sufficient  quantity  of  oil  to  render 
them  soft  and  give  suppleness.  The  mixtare  eonsists  of  a  paste  composed  of  i^iesiea 
flour,  yolks  of  eggs,  alum,  common  salt,  aftd  water.  The  flour  by  the  ^uten  it  con- 
tains aids  the  absorption  of  the  alumina  compound,  and  thns  assists  the  resl  tawing. 
The  starch  does  not  enter  into  the  composition  of  the  skins,  while  the  yolk  of 
eggs  acts  by  the  oil  it  naturally  contains  in  the  state  of  emulsion,  this  oil  giving  to 
the  kid  leather  that  suppleness  and  softness  which  is  so  mnch  esteemed  in  gloves.  It 
appears  that  emulsions  made  with  almond  oil  (the  so-called  sweet  oil  of  almonds— a 


TANNING.  525 

fixed  oil),  olive  oil,  fish  oil,  and  eren  paraffin,  may  be  advantageously  substitated  for 
yolk  of  eggs.  The  skins  are  thoroughly  soaked  and  kneaded  in  this  mixture,  to 
"wliich,  in  France,  there  is  sometimes  added  2  to  3  per  cent  of  carbolic  acid  for  the 
purpose  of  preventing  the  too  strong  heating  of  the  skins  when  impregnated  with 
the  mixture  and  packed  in  heaps.  The  skins  are  next  stretched  by  hand  and  dried 
rapidly  as  possibly  by  exposure  to  air.  Having  been  damped,  a  dozen  of  the  skins 
placed  between  linen  cloths  and  trodden  upon  to  render  them  soft.  After  this 
they  are,  one  by  one,  planed,  dried,  and  again  planed.  Either  by  rubbing  with  a 
heavy  polished  glass  disc  or  by  the  appreteur,  simultaneously  with  the  application  of 
some  white  of  egg,  or  a  solution  of  gum,  or  of  fine  soap,  a  gloss  is  given  to  the  skins, 
the  hair  side  of  which  is  the  right  side  or  dyed  side.  The  dyes  are  applied  either  by 
immersion  or  by  brushing  over  the  leather ;  the  latter,  or  English  method  of  dyeing 
■kins,  is  more  ordinarily  practised. 

According  to  Knapp's  researches  very  good  white  kid  leather  is  obtained  by  tawing 
the  epidennis  (bloss)  from  lamb  or  goat  skins  in  a  saturated  solution  of  stearic  add 
in  alcohoL  The  leather  thus  obtained  is  very  soft,  has  a  whiter  colour  than  ordinaiy 
glac6  leather,  and  a  beautiful  gloss. 

Kaaf»*tLMih«.      4.  The  preparation  of  leather  with  the  aid  of  insoluble  soaps, 
introduced  by  Enapp,  would  appear  to  have  become  of  some  importance.     The  pro- 
perty possessed  by  oxide  of  iron  of  acting  as  a  tanning  material  has  been  known  for 
ft  long  time,  and  in  1855  Mr.  Belford  took  out  a  patent  in  this  country  for  a  mineral 
tan  method,  in  which  oxide  of  iron  was  used;   but  good  leather  did  not  result. 
The  hides  do  not  become  really  tanned  by  being  immersed  in  solutions  of  such 
metallic  salts,  as  those  of  the  protoxide  and  peroxide  of  iron,  oxides  of  zino 
and  chromium ;  for  though  the  acidity  of  these  solutions  is  reduced  to  a  mininnin^ 
without  producing  a  permanent  precipitate,  and  thereby  the  deleterious  action  of  the 
acid  upon  the  fibres  of  the  hides  decreased,  and  though  a  certain  combination  of  the 
oxide  and  fibres  takes  place,  no  real  leather  is  formed  because  the  substance 
when  finished  is  not  fitted  for  contact  with  water,  for  then  the  so-called  tanning 
is  washed  out.    Knapp's  process  also  is  not  really  a  tanning  but  a  tawing  operation, 
hy  which  the  skins  are  alternately  immersed  in  a  solution  containing  3  to  5  per  cent 
of  soft  soap,  and  then  in  a  saline  solution  of  oxide  of  iron,  or  of  chromium, 
containing  5  per  cent  of  the  salt,  from  which  an  insoluble  metallic  soap  is  precipi- 
tated and  impregnated  with  the  fibres.    After  this  operation  has  been  several  times 
repeated  the  hides  or  skins  are  washed  in  water  and  dried.    Although  the  exterior 
eobur  of  good  sound  leather  may  be  imitated,  the  real  qualities  of  leather  are 
wanting.    Knapp's  process  is  not  in  use  or  is  so  entirely  modified  by  substituting 
alum  for  metallic  oxides  that  the  skins  are  tawed  by  a  combination  of  the  preceding 
tawing  processes  and  the  oil-tawing  process  now  to  be  described* 


_  »  _ 

m.  Samian  or  Oil- Tawing  Process, 

TfeiHsfPraeMi.  By  this  name  is  understood  a  peculiar  process  by  which  the 
skins  and  hides  of  various  animals,  such  as  harts,  deer,  sheep,  calves,  oxen  (for  the 
white  leather  for  military  use  as  belts,  ftc.),  are  converted  into  so-called  oil-  or  wash- 
leather.  The  tanning  material  is  oil,  iat,  tallow,  or  fish  oil,  to  which  recently  there 
has  been  added  4  to  7  per  cent  of  carbolic  acid.     The  leather  thus  obtained  is 


526  CHEMICAL  TECHNOLOCr. 

thiefly  used  for  making  militaty  breeches,  socks,  vests,  gloves,  braces,  belts,  sm^ioil 
applications,  and  not  in  small  quantity  for  washing  glass  and  poreelaiii, 
to  its  softness.  On  this  accoont  wash-leather  is  also  largely  used  by  gold  and 
smiths  for  poUshing  trinkets  with  rouge  (veiy  carefully  prepared  oxide  of  iron).  Hm 
upper  or  exterior  layer  of  the  corium,  which  owing  to  its  greater  compactness  does 
not  possess  the  ductility  and  suppleness  oi  the  lower  or  interior  layer,  is  in  flit 
skins  intended  to  be  converted  into  wash-leather  entirely  cut  away,  so  that  no  hair 
and  flesh  side  are  taken  into  consideration.  The  cutting  away  of  this  layer  greatj^ 
promotes  the  absorption  of  the  oil,  which  by  the  joint  action  of  air  and  heat  yields  a 
product  which  is  a  dry  compound  of  fibre  and  oil,  in  whidi  the  latter  pfayBcalfy  htf 
disappeared,  inasmuch  as  the  leather  is  not  impervious  to  water.  Wash-Ieadicr 
differs  in  this  respect  from  oil  or  fsX  leather ;  still,  on  immersion  in  water,  the  akiii  does 
not  glue  together  and  shrink.  Thin  skins,  such  as  those  of  goats  and  li^T«K#^  ars 
not  deprived  of  their  hair  side,  because  it  would  render  them  too  thin  for  use. 

The  skins  intended  to  be  made  into  wash-leather  are,  as  regards  the  first  stage  of 
the  operation,  treated  exactly  as  described  for  the  skins  treated  with  alum,  the  anly 
difference  being  that  the  hair  is  removed  together  with  the  hair  side  portion  of  tfat 
skins,  which  are  next  placed  in  a  bran  bath  in  order  to  remove  the  lime.     After  Urn 
the  skins  are  stretched  and  conveyed  to  the  fulling  machine  in  order  to  beeont 
saturated  with  oil,  for  which  purpose  the  skins  are  first  laid  on  a  table  or  bench  and 
are  rubbed  with  oil,  the  hair  side  being  placed  uppermost    This  having  been  dons 
they  are  made  into  clouts  and  placed  under  the  stampers  of  a  machine  so  as  tt^ 
thoroughly  impregnate  them  with  oiL    From  time  to  time  the  skins  are  taken  from 
the  trough  and  exposed  to  the  air,  then  again  rubbed  with  oil  and  put  under  tfas 
stampers  until  enough  oil  has  been  absorbed.    By  the  repeated  exposure  to  air 
the  skins  become  dry,  and  oil  (fish  oil  is  chiefly  used)  absorbed ;  the  exposure  to  air 
is  continued  until  the  surface  of  the  skins  appears  quite  dry.     When  the  skins  have 
an  odour  somewhat  similar  to  that  of  horse-radish,  and  have  lost  their  fleshy  odoort 
they  have  absorbed  a  suf&cient  quantity  of  oil,  while  a  portion  of  the  oil  has  been 
somewhat  changed  and  has  entered  into  combination  with  the  fibre,  another  porticn 
only  mechanically  adhering  to  the  pores  of  the  skins.    The  next  operation  therefbn 
aims  at  rendering  the  process  of  the  combination  of  the  oil  with  the  skins  mote 
rapid  by  bringing  about  a  fermentation  attended  with  an  elevation  of  temperature; 
this  is  effected  by  placing  the  skins  in  a  warm  room,  heaping  them  together,  sad 
covering  them  with  canvas  to  keep  in  the  heat  which  is  generated,  care  being  taken 
to  air  the  heap  from  time  to  time  in  order  to  prevent  overheating  and  oonsequeot 
deterioration  of  the  skins.    This  operation  of  airing  the  skins  is  repeated  until  fay 
the  spontaneous  heating  they  have   acquired  a  yellow  colour  and  the  woxkmen 
know  by  experience  that  the  oxidation  of  the  oil  is  finished.    A  portion  of  the  oQ 
(estimated  at  about  50  per  cent  of  the  quantity  originally  employed)  is  left  in  the  skins 
in  uncombined  state,  and  is  removed  by  washing  with  a  tepid  solution  of  potash. 
From  this  liquor  there  separates  on  being  left  at  rest  a  portion  of  fat  termed  di^roM^ 
and  which,  as  already  mentioned,  is  employed  for  the  dressing  of  tanned  hideSL 
The  skins  having  been  thus  deprived  of  the  excess  of  oil  are  wrung  out,  dried,  and  next 
dressed,  in  order  to  restore  to  them  their  softness  and  suppleness  partly  lost  in  the 
drying.    Cordovan  or  Turkey  leather,  is  oil-tawed  without  the  hair  aide  having  been 
first  removed,  while  the  flesh  side  is  blackened  in  the  usual  way.    This  kind  of 
leather  is  chiefly  used  for  hulies*  boots  and  shoes.    According  to  I^pp,  skias  fron 


.       TANNING.  527 

whioh  the  hair  has  been  first  removed  may  be  tawed  by  treating  them  alternately 
"with  a  solation  of  soap  and  dilute  acids,  so  that  the  fatty  acids  are  precipitated  into 
the  fibre.  After  the  tawing  the  skins  thus  treated  should  be  thoroughly  washed 
in  water  to  remove  all  acid.  As  regards  the  constitution  of  the  leather,  commonly 
known  as  wash-leather,  tawed  with  oil,  nothing  is  definitely  known,  but  it  would 
appear  that  this  process  of  tawing  has  some  analogy  to  the  process  of  imparting  oil 
to  calico  intended  for  Turkey -red  dyeing. 

9mnhmuA,  The  substanco  known  as  parchment  is  not  really  leather,  because  its 
fibres  are  neither  tanned  nor  tawed,  as  proved  by  the  fact  that  boiling  water  readily 
converts  parchment  into  a  superior  kind  of  glue  similar  to  isinglass,  of  course  too 
expensive  for  joiners'  use.  Parchment  is  essentially  the  well-cleansed  and  carefully 
dried  skins  of  hares,  rabbits,  and  especially  of  calves  and  sheep. 

Ordinary  parchment  is  prepared  from  sheep-skins,  but  the  variety  known  as 
vellum,  Vehn  ar  Parchement  vi^rge,  is  far  finer,  and  is  made  from  the  skins  of  young 
calves,  goats,  and  stillborn  lambs.     According  to  the  use  intended  to  be  made 
of  parchment,  so  is  its  preparation  modified.    The  skins  are  first  soaked  in  water 
and  then  placed  in  the  lime-pits.    Sheep  skins  are  cleansed  by  working  with  cream 
of  lime  in  order  to  preserve  the  wool.    When  the  hair  has  been  removed  the  skins 
are  washed,  being  placed  on  the  dresser's  block,  and  usually  also  planed  with 
a  sharp  knife  to  remove  the  superfluous  fleshy  parts.    This  having  been  done,  each 
skin  is  separately  stretched  in  a  frame,  in  a  manner  very  similar  to  that  in  use  for  so-* 
called  Berlin-wool  work,  the  skins  being  held  in  position  by  means  of  strings,  and 
dried  by  exposure  in  the  open  air.     Parchment  intended  for  drum  skins  {from 
calves'  skins),  for  kettledrums   (from  asses'  skins),  does  not  require  any  furthev 
operation.     If  intended  for  bookbinding  the  parchment  is  treated  as  described, 
but  after  diying  it  is  planed  with  a  tool  the  cutting  edge  of  which  is  somewhat 
bent  in  order  to  impart  a  rough  surface,  whereby  the  parchment  is  rendered  capable 
of  being  written  on  and  dyed.     If  the  parchment  be  intended — as  it  used  fre- 
quently to  be  formerly  before  the  invention  of  metallic  paper — for  memoranda, 
written  with  lead-pencils,  to  be  wiped  out  if  desired  with  a  wet  sponge,  it  is 
after  planing  painted  over  with  a  thin  white-lead  paint,  for  which  a  mixture  of  glue* 
water  with  baryta-  or  zinc-white  is  often  substituted.    The  vellum  of  this  country  is 
generally  obtained  from  sheep  skins,  which  are  split  into  two  sheets  by  means  of 
cutting-tools.    Parchment  after  having  been  dried  on  the  frames  is  dusted  over  with 
chalk  and  rubbed  with  pumice-stone.    The  sieves  used  in  powder  mills  for  granula- 
ting the  powder  are  made  of  parchment  obtained  from  hogs'  skins. 

atecrMB.  Genuine  Oriental  shagreen  (saghir,  sagri,  sagre),  is  a  variety  of  tawed 
parchment,  one  side  of  which  is  covered  with  small  hard  grains.  This  material 
is  manufactured  in  Persia,  at  Astrakan^  in  Turkey,  and  m  Koumania,  from  certain 
portions  of  the  skins  and  hides  of  wild  asses,  horses,  and  other  animals.  The  hides 
are  soaked  in  water  until  the  epidermis  can  be  removed  easily  together  with  ths 
hairs  by  the  aid  of  a  dressing-knife ;  next  the  hides  are  again  placed  in  water  so  as 
to  swell  the  material  sufficiently  to  admit  of  cleansing  it,  and  cutting  away  on  both 
flesh  and  hair  side  all  superfluous  material,  so  as  to  leave  only  the  corium,  which  then 
has  the  appearance  of  a  fresh  bladder.  In  order  to  produce  on  skins  thus  prepared 
a  grained  surface,  they  are  put  into  frames,  as  described  under  Parchment,  while 
on  the  hair  side,  aUabuta,  the  hard  black  seed  of  the  Ohenopodium  eUbum  is 
stamped  in,  either  by  the  feet  or  forced  in  by  pressure.    When  the  skins  are  dry  they 


528  CHEMICAL  TECHN0L007. 

are  removed  from  the  frame,  the  seed  shaken  off,  and  the  skins  thoion^^j 
with  a  sharp  dressing-knife,  then  pnt  again  into  water,  tawed,  and  finally  djed.  TIh 
tawing  is  effected  by  the  aid  eitlier  of  alnm  or  of  oak  bark.  The  dye  of  shagreen  is 
generally  green,  and  is  due  to  salts  of  copper.  After  dyeing  the  skins  are  aoaiBed  is 
mntton  tallow. 

Fish  skin,  or  fish  chagrin,  is  obtained  from  varions  kinds  of  sharks  (Sgaoin 
eanictda^  8.  catuliu^  8.  centrina)  and  other  fishes  of  the  same  class.  The  skis  of 
these  animals  is  not  covered  with  scales,  but  with  more  or  less  projecliiig  hari 
points.  The  skins  having  been  removed  from  the  fish  are  stretched  in  frames  aad 
simply  dried,  being  then  sent  to  the  market.  Formerly  sharks'  skin  was  in  stmt 
countries  used  by  joiners  instead  of  sand-  and  glass-paper  for  preparing  wood.  Ths 
skins  deprived  of  the  projections  are  dyed  and  used  for  covering  small  boxes,  tnbes 
of  small  telescopes,  &c. 

Glue-Boilino. 

• 

otBmiobMrrationi.  The  Organisms  of  all  animals,  but  more  especially  of  the  hi^ier 
classes,  contain  tissues  which  are  insoluble  in  cold  as  well  as  in  hot  water,  but 
which  by  continued  boiling  become  dissolved,  and  yield  on  evaporation  of  the  solu- 
tion a  glutinous  gelatinising  mass,  which,  by  further  diying,  exhibits,  according  to  the 
degree  of  purity  of  the  material,  a  more  or  less  transparent  and  brittle  substanoe,  whidi 
in  pure  state  is  devoid  of  colour  as  well  as  of  smell,  becoming  swollen  in  cold  water  and 
dissolved  by  boiling  in  that  liquid.  This  substance,  i,e.,  the  product  of  the  convo^ 
sion  of  the  so-called  glue-  or  gelatine-yielding  tissues,  is  what  is  known  in  the  trade 
as  glue,  and  largely  used  by  joiners,  carpenters,  Ac.,  for  joining  wood^  also  te 
sizing  paper,  for  clarifying  various  liquids,  beer  and  wine  for  instance,  and  as  a 
cement.  Among  the  glue-yielding  tissues  the  following  are  the  most  important : — 
Cellular  tissue,  the  corium,  tendons  or  sinews,  the  niiddle  membrane  of  the  vasa 
lymphatica  and  veins,  the  osseine  or  organic  matter  of  bones,  hartshorn,  cartilage, 
the  bladders  of  many  kinds  of  fish,  &c.  Chemically  we  distinguish  between  glatio, 
that  is  to  say,  glue  derived  from  skins,  bones,  Ac.,  and  chondrin,  which  has  been 
obtained  from  cartilage.  In  a  technical  point  of  view  this  distinction  is  hardly 
required,  as  the  cartilaginous  matter  is  as  much  as  possible  selected  from  other  i^oe- 
making  materials,  because  experience  has  shown  that  glutin  has  a  much  greater 
power  of  adhesion  than  chondrin.  The  latter,  however,  is  largely  used  as  aixe  in 
this  country. 

As  already  observed,  the  glue-  or  gelatine-yielding  tissues  yield  on  being  dissolved 
a  gelatinising  mass,  the  aqueous  solution  of  which  does  not,  however,  possess  to  any 
great  extent  a  glueing  property,  which  is  only  imparted  to  the  gelatine  by  a  process 
of  drying.  In  considering,  therefore,  the  process  of  glue-boiling,  we  have  to  distjn* 
guish  the  animal  matter  capable  of  yielding  glue,  the  gelatinous  mass  obtained 
therefrom,  and  the  glue  obtained  by  drying  the  latter.  The  temperature  required  lor 
obtaining  gelatine  differs  according  to  the  different  animal  tissues  employed ;  tiit 
consistency  of  the  gelatine  obtained  from  equally  strong  solutions  varies  with  the  age 
of  the  tissues  operated  upon. 

Glue  readily  dissolves  by  boiling  in  water,  forming  on  cooling  a  gelatinous  masi^ 
even  if  the  quantity  of  glue  is  only  i  per  cent.  Repeated  boiling  and  cooliiig  a 
glue  solution  causes  it  to  lose  the  property  of  gelatinising,  and  the  same  effect  is  pro- 
duced by  acetic  and  dilute  nitric  acids.    Solutions  of  alum  precipitate  glue  solutions 


OLUE.  3i$ 

only  after  the  addition  of  potash  or  soda,  the  precipitate  consisting  of  glue  mixea 


basic  sulphate  of  alumina.  Glue  enters  with  tannic  acid  into  a  combination  of 
^Konstant  composition ;  hence  glue  or  gelatine  may  be  used  for  the  estimation  of 
-^i^nnin  In  Vegetable  matter. 

Three  different  kinds  of  glue  are  distinguished  by  the  manufacturers,  viz. : — 

a.  So-called   skin-glue,   or  leather-glue,  prepared    from   refuse  hides,   skins, 

tendons,  &c. 

b.  The  glue  obtained  from  bones. 

c.  The  glue  obtained  from  iish-bladders,  termed  isinglass. 

Very  recently  glue  from  vegetable  gluten  and  so-called  albumen  glue  have  been 
prepared. 

i^Miber  aine.  This  substsnce  is  prepared  from  a  large  variety  of  animal  refuse,  the 
chief  sources  being  the  following: — Refuse  from  tan  yards,  tawing  and  leather- 
dressing  works,  old  gloves,  rabbit  and  hare  skins  (the  hair  having  been  used  by  hat- 
makers),  skins  of  cats  and  dogs,  ox  feet,  parchment  cuttings,  surons  (skins  which  have 
served  the  purpose  of  carrying  drugs,  especially  from  America),  sinews,  guts, 
leather  cuttings  (leather  tanned  with  oak  bark  cannot  be  readily  converted  into  glue). 
The  glue-boiler  on  an  average  obtains  from  the  various  materials  about  25  per  cent 
^  of  glue,  preference  being  given  to  the  refuse  of  tawing  operations  and  kid  leather. 
\  naking,  because  these  materials  are  ready  for  boiling  without  requiring  any  previous 
treatment.    Glue-boiling  involves  the  following  operations : — 

1.  Treating  tiie  glue-yielding  materials  with  lime. 

2.  Boiling  these  materials. 

3.  Forming  the  gelatine. 

4.  Drying  the  gelatine  so  as  to  form  glue. 

nmitiiicwtthLtiiM.  I.  The  aim  of  this  operation  is  the  cleansing  of  the  refuse  and  the 
prevention  of  putrefioction.  It  is  effected  by  placing  the  cuttings  in  tanks  or  lime-pits 
and  pouring  in  a  thin  milk  of  lime.  The  materials,  while  the  milk  of  lime  is 
firequenUy  renewed,  are  thoroughly  mixed  with  the  lime-liquid  and  left  for  fifteen  to 
twenty  days  in  the  pits.  By  the  action  of  the  lime  any  blood  and  flesh  is  dissolved 
and  the  fatty  matter  saponified.  In  order  to  remove  the  excess  of  lime,  the 
materials  are  placed  either  in  nets  or  in  willow- baskets,  and  these  are  immersed  in  a 
brook  or  river,  where  a  continuous  stream  of  fresh  water  removes  the  greater  part  of 
the  lime  in  a  few  days.  The  washed  material  is  next  exposed  in  the  yard  to  the 
action  of  the  air  in  order  that  it  may  become  dry,  as  well  as  form  a  carbonate  of 
any  lime  still  present  in  the  materials.  When  the  materials  are  dry  they  are  packed 
and  sent  off  to  the  glue-boilers,  who,  previous  to  proceeding  with  the  boiling  opera- 
tion, macerate  the  materials  again  in  a  weak  milk  of  lime,  the  maceration  being 
foUowed  by  washing. 

Fleck  states  that  a  weak  alkaline  ley  (5  kilos,  of  calcined  soda  and  7*5  kilos,  of 
quick- hme  to  750  to  1000  kilos,  of  glae-yielding  material)  is  preferable  to  the  use  of 
milk  of  lime.  When  tiie  glue-boiling  and  tanning  operations  are  executed  on  the 
same  premises,  the  lime-treated  glue  materials  are  put  for  a  few  hours  into  old  oak 
bark  liquor,  the  acids  (lactic,  butyric,  and  propionic  acids)  of  which  remove  the  lime, 
while  the  animal  matter  is  at  the  same  time  superficially  tanned.  This  glue  tannate 
rises  during  the  boiling  as  scum  to  the  surface  and  assists  in  rendering  the  glue 
liquor  dear.    According  to  Dullo,  the  Cologne  glue-^  very  pale  and  strong  glue— 

ao 


530  CHEMICAL  TECHNOLOGY. 

28  obtained  from  offal,  which,  after  liming,  has  been  treated  with  a  soliitioii  of 
chloride  of  lime  (hypochlorite  of  lime),  and  thereby  bleached. 

Bofliag  the  MateziAia.  This  Operation  is  carried  on  either  in  the  ordinary  mimnff  of 
boiling  anything  with  water,  or  by  so-called  fractioned  boiling,  or  finallj  by  iht 
application  of  steam.  As  the  conversion  of  the  glne-yielding  materials  into  ^ii€ 
takes  place  slowly  and  gradually  under  the  influence  of  the  boiling  water,  it  is  dear 
that  the  method  of  boiling  cannot  be  witliont  influence  upon  the  glue  oltimst/dy 
produced.  The  first  portions  of  gelatine  which  are  formed  remain  in  contact  witk 
a  boiling-hot  mass,  and  are  thereby  further  changed  so  as  to  lose  the  capability  of 
gelatinising,  while  the  glue  at  last  obtained  exhibits  a  dark  colour  and  is  often  not  m 
strong,  although  it  is  generally  believed  that  deep-coloured  glue  is  of  a  better 
quality.  A  rational  mode  of  glue-boiling  would  involve  the  gradual  remofval  of  the 
solution  obtained,  while  of  course  fresh  water  would  have  to  be  supplied  to  replace 
the  liquor  drawn  off.  The  older  method  of  glue -boiling  consists  in  simply  placing 
the  materials  with  water  in  a  cauldron,  care  being  taken  to  prevent  burning  by  placing 
the  materials  on  a  stout  wire  gauze  or  t3dng  them  in  a  net  and  suspending  it  in  the 
boiling  liquid.  Soft  water  yields  a  better  result  than  hard.  Gradually  the  maieriali 
become  dissolved,  and  the  sciun  which  is  formed  is  taken  from  the  surface  with  a 
large  ladle.  The  refuse  of  glue  of  former  operations  is  added  to  the  boiling  liqraiid, 
and  the  operation  continued  until  the  liquid  is  of  the  required  strength,  which  is 
tested  by  pouring  into  a  broken  egg-sheU  a  small  portion  of  the  liquor,  and  by 
placing  the  partly-filled  shell  in  ice-cold  water.  If  the  solution  gelatinises  after  a 
while,  forming  a  hard  and  rather  stiff  gelatine,  the  liquor  is  run  off  by  means  of  a 
tap,  filtered  through  a  layer  of  straw  placed  in  a  basket,  and  conveyed  to  a  wooden 
lead-lined  cistern,  externally  covered  with  mats  or  straw,  or  some  bad  condactor  of 
heat.  In  some  works  the  liquor  is  decanted  into  a  deep  but  narrow  boiler,  tiie 
furnace  of  which  is  so  arranged  as  to  impart  heat  to  the  top  of  the  vessel  only.  Tins 
vessel,  as  well  as  the  cistern,  is  heated  previously  to  the  liquor  being  poured  in.  The 
liquor  is  clarified  by  stirring  it  with  a  small  quantity  of  very  finely-pulverised  alaa, 
075  to  I '5  per  mille  of  the  liquid.  After  this  the  liquid  is  left  to  stand  all 
night  The  alum  precipitates  any  lime  remaining  as  sulphate  of  lime,  and  also  soma 
organic  matter  which  renders  the  liquid  turbid.  Alum,  though  it  preventB  tfao 
putrefioction  of  the  glue  while  drying,  impairs  its  strength.  The  lime  mi^t  better 
be  precipitated  by  oxalic  acid,  and  the  organic  matter  removed  by  adding  to  tiia 
boiling  mass  some  astringent  matter,  stlch  as  oak  bark  decoction  or  hops,  so  th^ 
during  tlie  boiling  the  organic  impurities  could  be  taken  away  as  scum. 

motioned  Boiling.  By  tliis  Operation  only  a  comparatively  small  quantity  of  water  ia 
added  to  the  animal  matter  intended  to  be  converted  into  glue.  When  the  water  is 
fairly  boiling  the  cauldron  is  covered  with  a  well-fitting  lid,  and  the  steam  being  k^ 
in  as  much  as  possible,  is  allowed  to  act  upon  the  materials  so  as  to  convert  them 
into  glue.  When,  after  continued  boiling  for  about  two  hours,  the  water  has  taken 
up  sufficient  gelatine,  the  liquor  is  run  off  and  fresh  water  poured  on  the  «i«t^«fa 
This  operation  is  repeated  until  the  decoction  no  longer  gelatinises,  the  last  liquor 
being  kept  for  use  instead  of  water  for  a  following  operation.  The  liquors  thus 
obtained,  excepting  the  last,  are  either  mixed  or  each  is  treated  separately.  Tbe  giue 
yielded  by  the  first  decoction  is  stronger  than  that  yielded  by  the  subsequent  liquora 
By  this  method  of  boOing  the  saturated  liquor  does  not  remain  exposed  to  the  actioB 
of  heat  and  water  too  long,  and  oonsequenfly  a  better  article  is  produced.     In  some 


OLUB.  531 

instances  the  materials  intended  to  be  converted  into  glue  are  boiled  in  a  vessel 
similar  in  construction  to  those  in  use  in  bleaching -works  and  in  paper-mills, 
arranged  in  the  following  manner.  At  some  distance  from  the  bottom  a  perforated  false 
bottom  is  placed,  in  the  centre  of  which  is  fixed  a  wide  tube  which  reaches  to  about  two- 
thirds  of  the  height  of  the  cauldron.  The  materials  intended  to  be  converted  into  glue 
are  placed  upon  the  perforated  bottom  and  water  under  it ;  as  soon  as  the  water  boils, 
the  steam  produced,  not  being  able  to  escape  rapidly  and  readily  through  the  materials, 
exerts  a  pressure  upon  the  liquid  and  forces  it  through  the  tube,  the  consequence  being 
that  a  constant  stream  of  boiling  liquid  Mis  upon  the  glue  materials,  which  are  rapidly 
dissolved. 

A  more  rational  mode  of  conducting  this  operation  consists  in  employing  high- 
pressure  steam  admitted  into  the  mass  of  the  animal  materials  to  be  converted  into 
glue.  In  tins  manner  a  very  concentrated  solution  of  glue  is  obtained  in  a  short 
time.  In  England  steam  is  generally  employed,  but  on  the  continent  its  use  is  the 
exception.  It  has  been  said  that  it  is  advantageous  to  allow  tlie  animal  offal  intended 
for  glue  to  become  somewhat  decomposed  and  tlien  to  disinfect  it  with  chlorine 
and  sulphurous  acid  before  boiling  it  for  glue,  because  by  this  mode  of  treatment  a 
brighter  glue  is  obtained.    We  are  unable  to  say  whether  this  opinion  is  correct. 

M onidinc.  As  soou  as  the  glue  solution  has,  by  standing  in  the  tanks  into  wliich  it  had 
been  transferred  from  the  boilers,  become  quite  clear  and  somewhat  cooled,  the 
liquid  is  poured  into  moulds,  and  when  solidified  the  jelly  is  cut  into  cakes  of  the 
shape  and  size  met  with  in  the  trade. 

The  moulds,  into  which  the  glue  solution  is  poured  through  a  strainer  made  of 
metal  gauze,  are  of  wood,  and  generally  a  little  wider  at  the  top  than  at  tlie  bottom, 
eo  as  to  admit  of  an  easy  removal  of  the  solid  material.  At  the  bottom  of  the  moulds 
a  series  of  grooves  are  cut  at  such  a  distance  from  each  other  as  agrees  with  the  size 
of  the  intended  glue-cakes.  Before  the  liquid  is  poured  into  the  moulds,  these  are 
thoroughly  washed,  and  either  allowed  to  remain  damp,  or  if  dried  are  oiled,  so  as  to 
prevent  the  solidifying  gelatine  adhering  to  the  wood.  Recently  moulds  made  of 
sheet-iron  and  zinc  have  been  introduced.  The  moulds  are  filled  with  the  lukewarm 
glue  solution,  and  when  the  glue  is  sufficiently  hard  it  is  gently  loosened  from  the 
sides  with  a  sharp  tool,  and  the  mould  having  been  turned  over  on  a  wooden  or  stone 
table,  previously  damped,  is  lifted  off  the  block  of  gelatine,  which  is  next  cut  into 
cakes  or  slabs.  The  cutting  tool  is  simply  a  piano-wire,  or  more  frequently  a  series 
of  these  stretched  in  a  frame  at  sufficient  distance  from  each  other  to  make  the 
cakes  of  the  desired  thickness,  the  frame  being  placed  on  small  wheels  so  as  to  be 
easily  moved.  Glue  is  met  with  in  the  trade  as  a  gelatinous  mass,  or  is  sold  in 
casks  under  the  name  of  size.  It  is  said  that  the  process  of  drying  impairs  the  good 
qualities  of  the  glue. 

DrytnftiMGiM.  ThiB  Operation  is  performed  by  placing  the  gelatine  cakes  on  nets 
made  of  twine  stretched  in  frames  and  exposed  in  a  dry  aiiy  place  to  the  action  of 
the  sun.  The  drying  is  one  of  the  most  difficult  operations  of  the  glue-making 
process,  because  the  temperature  of  the  air  and  its  hygrometric  condition  exert  a 
great  influence  on  the  product,  especially  during  the  first  few  days.  The  glue  will 
not  bear  a  temperature  above  20°,  because  at  a  higher  temperature  it  becomes  again 
fluid,  and  as  a  matter  of  course  flows  through  the  meshes  of  the  net  and  adheres  to 
the  twine  so  strongly  as  to  require  the  nets  to  be  put  into  hot  water  for  the  removal 
of  the  mass.    Too  dry  air  causes  an  irregularity  in  the  drying  of  tlie  glue,  and  as 


53a  CHEMICAL  TECHNOLOGY. 

a  consequence  the  cakes  become  bent  and  cracked ;  while  firost  causes  dismiegtstkA^ 
80  as  to  necessitate  a  re-melting  of  the  glue ;  hence  it  follows  that  drying  in  the 
open  air  can  only  be  effected  in  tlie  spring  and  autumn.  Although  the  ^ae-botQcra 
have  tried  to  dry  glue  by  artificial  heat,  this  plaji  has  not  been  generally  introduced  oinBg 
to  the  fact  that  a  slight  excess  of  heat  causes  the  melting  of  the  gelatine,  the  mcR 
readily  when  ventilation  is  neglected.  Drying-rooms,  as  recently  constructed  are  large- 
sized  sheds  fitted  with  the  required  frame- work  for  receiving  the  gelatine  cakes,  azid 
heated  by  steam-pipes  placed  on  the  floor  near  the  latter.  The  walls  are  provided 
with  openings  which  can  be  closed  by  means  of  valves,  while  there  are  ventilaton  in 
the  roof  arranged  to  obtain  a  proper  circulation  of  air.  As  the  gelatine  plaoEd 
nearest  to  the  floor  of  the  room  becomes  most  quickly  dry,  it  is,  with  the  frames 
upon  which  it  placed,  removed  after  eighteen  to  twenty-four  hours  to  a  higher  part  of 
the  drying-room,  which  is  not  heated  at  all  if  the  outer  air  has  a  temperature  of 
15°  to  20°.  The -drying-shed,  or  room,  is  by  preference  built  so  as  to  face  the  north. 
When  the  glue  has  been  tlius  dried  as  much  as  possible,  it  is  generally  quickly  dried 
in  a  stove  in  order  to  impart  hardness.  It  is  next  polished  by  being  inunersed  im 
hot  water,  and  cleaned  witli  a  brush,  and  again  dried. 

oiae  from  BonM.  The  Organic  matter  contained  in  bones,  forming  nearly  one-tfaicd 
part  (32' 17  per  cent)  of  their  weight,  consists  of  a  material  which,  after  the  bones  have 
been  treated  with  hydrochloric  acid,  is  very  readily  converted  by  the  action  of  high- 
pressure  steam  into  glue.  The  preparation  of  glue  from  bones  by  the  action  of 
hydrochloric  acid  is  the  usual  mode  of  pro<?eeding,  and  the  operation  is  advantage- 
ously combined  with  the  making  of  sal-ammoniac  and  phosphorus. 

The  preparation  of  glue  from  bones  includes  the  following  operations : — ^I.  .BoUutg 
out  the  Orease. — The  bones  are  put  into  water  and  boiled  in  a  cauldron,  the  £si 
floating  to  the  surface.   Frequently  in  order  to  save  fuel  the  bones  are  put  into  an  iraa 
wire  basket,  which  is  removed  after  the  boiling  has  been  continued  for  some  time,  the 
bones  thrown  out  and  fresh  ones  put  in,  the  boiling  being  continued  until  a  thick 
gelatinous  liquor  is  obtained.    The  fat  or  grease  is  removed  from  the  sur&ce  of  the 
liquid  by  means  of  ladles.     The  gelatinous  mass  obtained  by  this  process  is 
used  as  a  manure  or  is  given  to  cattle  as  fodder.    In  some  works  bones  have 
exhausted  with  sulphide  of   carbon  for  the  purpose   of   extracting  the 
II.  Treating  tJie  Bones  tcith  Hydrochloric  Acid. — The  bones  having  been  drained  are 
placed  in  baskets,  and  witli  these  are  immersed  in  tanks  to  more  than  half  their  height, 
the  tanks  being  filled  widi  hydrochloric  acid  at  7°  B.  ( =  105  sp,  gr.  =  io'6  per  ceaX 
CIH) ;  10  kilos,  'of  bones  require  40  litres  af  acid.     The  bones  are  kept  in 
liquor  until  they  become  quite  soft  and  transparent.    They  are  next  drained  and 
with  the  baskets  immersed  in  a  stream  or  brook  with  a  good  supply  of  running 
water  to  wash  out  the  greater  portion  of  the  acid,  which  is  fully  neutralised  by 
placing  the  bones  fin  lime-water,  again  followed  by  washing  with  fresh  water, 
the   bones   being   then   ready  for  boiling.      Gerland  has  suggested  the  use  of 
sulphurous  instead  of  hydrochloric  acid.     UL  Conversion  of  the  Organic  Matter 
into  Olue. — The  cartilaginous  substance  having  been  either  partly  or  completely 
dried  is  put  into  a  cylindrical  vessel  containing  a  false  perforated  bottom,  and 
between  that  and  the  real  bottom  a  pipe  or  tube.    To  the  top  of  the  vessel  a  lid  is 
fitted,  provided  with  an  opening  for  a  steam-pipe  leading  from  a  small  boiler. 
Shortly  after  the  admission  of  tlie  steam  a  concentrated  glue  solution  begins  to  nm 
ofl'  from  the  pipe  at  the  bottom  of  the  cylinder ;  this  solution  is  usually  so  concea- 


QLUE. 


^33 


Crated  as  to  admit  of  being  at  once  run  into  the  moulds,  and  after  having  become 
solid  is  treated  as  before  described.  After  a  few  hours  a  weak  liquid  makes 
its  appearance,  and  as  soon  as  this  happens  the  cylindrical  vessel  is  opened,  the  glue 
jonass  removed  with  the  weak  liquid  to  a  copper  and  boiled,  care  being  taken 
to  stir  the  magma  constantly.  As  soon  as  the  glue  is  dissolved  the  liquor  is  poured 
into  moulds.  Glue  obtained  from  bones  exhibits  a  milky  appearance  due  to  the  pre- 
sence of  a  small  quantity  of  phosphate  of  lime  retained  in  the  substance.  Some- 
times  there  is  purposely  added  more  or  less  baryta-white,  zinc-white,  white-lead, 
chalk,  or  pipe-clay.  The  glue  obtained  from  bones  is  sold  under  the  name  of  patent 
glue. 

uvau  Gioa.  Whcu  gluo  is  dissolvcd  in  its  own  weight  of  water  and  a  small  quantity 
of  nitric  acid  added  to  the  solution,  it  loses  the  property  of  gelatinising,  while  the 
adhesive  property  of  the  glue  is  not  impaired.  Dumoulin  prefers  to  dissolve  i  kilo. 
of  Cologne  glue  in  i  litre  of  boiling  water,  and  to  add  to  the  solution  0*2  kilo. 
of  nitric  acid  at  36  B.  =  1-31  sp.  gr.  After  the  evolution  of  the  nitrous  acid  fume^ 
lias  subsided  the  fluid  is  cooled.  A  better  liquid  glue  is  obtained  by  dissolving  good 
gelatine  or  glue  of  superior  quality  in  strong  vinegar  and  moderately  strong  acetic 
acid,  to  which  one-fourth  of  its  bulk  of  alcohol  is  added,  and  some  pulverised  alum, 
the  solution  being  aided  by  a  water-bath.  The  action  of  the  acetic  add  is  the  same 
as  that  of  the  nitric  acid.  According  to  Knaffl,  a  very  excellent  liquid  glue  ia 
obtained  by  heating  for  some  10  to  12  hours  upon  a  water-bath,  a  mixture  of  3  parta 
of  glue  in  8  parts  of  water,  to  which  are  added  0*5  part  of  hydrochloric  acid,  and 
0'75  part  of  sidphate  of  zinc,  the  temperature  of  the  mixture  being  kept  below 
80**  to  85"*.  This  kind  of  liquid  glue  keeps  for  a  very  long  time  and  is  largely  used 
for  joining  wood,  horn,  and  mother-of-pearL  This  g^ue  is  employed  by  the  makem, 
of  artificial  pearls. 

T«kforih«<)iujii7  of  oim.  Although  the  quality  of  glue  is  best  ascertained  by  practical 
use,  some  of  the  physical  qualities  and  the  external  appearance  of  glue  may  be 
mentioned  as  indicating  a  superior  article.  Glue  of  good  quality  should  exhibit  a 
bright  brown  or  brown-yeUow  colour,  should  be  free  from  specks,  glos£fy,  perfectly 
elear,  brittle,  and  hard,  shoidd  not  become  damp  by  exposure  to  air ;  when  being 
bent  it  should  snap  or  break  sharply,  the  fracture  presenting  a  glassy,  shining 
appearance.  "When  placed  in  cold  water  glue  should  not  even  after  forty-eight 
hours  in  this  fluid  swell  up  and  increase  in  bulk  nor  dissolve.  A  splintery  fracture 
of  glue  indicates  that  it  has  not  been  well  boiled.  The  adhesive  property  of  glue  is 
often  increased  by  adding  certain  pulverulent  earthy  substances.  This  addition  is 
regularly  the  case  with  Russian  glue.  Among  the  substances  employed  are  white- 
lead,  sulphate  of  lead,  zinc-white,  baxyta-white,  and  even  chromate  of  lead.  As 
different  kinds  of  glue  may  agree  in  their  external ,  aspect  and  yet  vary  as  regards 
their  adhesive  power,  methods  of  testing  glue  have  been  proposed,  some  of  which 
are  based  upon  the  chemical,  others  upon  the  physical,  properties  of  this  substance. 

I.  Cfhemioal  Procetsei  of  Tenting  Olue. — Of  these  we  mention  the  following  :— 
Oraeger's  Method. — ^Premising  that  the  quality  of  a  glue  is  dependent  on  tiie 
quantity  of  glutin  contained,  irrespective  of  the  origin  of  the  glue  and  its  freedom 
frtxm  foreign  substances,  which  might  weaken  its  adhesive  property,  Graeger  estimates 
the  quantity  of  gluten  by  precipitating  the  glue  solution  with  tannin,  and  by  calcu- 
lating from  the  amoimt  of  tannate  of  gelatine  obtained  (the  composition  being  taken. 
in  100  parts  at  4274  parts  of  gluten  and  5726  of  tannin),  the  quantity  of  pure 


534 


CRSmOAL  TBOSNOLOOT. 


gluten  contained  in  the  glue.  Rialer-Bennat,  while  employing  the  sune  prind^ 
prepfLTes  two  normal  fluids,  one  of  which  contains  lo  gnna.  of  pnro  tannic  cad 
to  the  litre,  while  the  other  contains  in  i  litre  lO  grma.  of  pure  isinglaas  aai. 
20  gtms.  of  almn.  As  equal  bulk  of  theee  fluids  do  not  saturate  each  other,  the 
author  determiueB  hy  titration  the  relstion  between  them,  and  dilutes  the  tannic  »ai 
solution  with  the  requisite  quanti^  of  water.  In  order  t^i  test  a  glue  the  anthiv  dis- 
solves 10  gnus,  of  the  sample  to  be  tested  with  20  gnns.  of  alnm  in  a  lit^e  of  water, 
beat  being  applied  if  necessary.  Next  to  o.c.  of  the  tannie  acid  solution  are  taken. 
to  which  an  equal  bnlli  (10  e.o.)  of  the  glne  solution  ia  at  ouea  added,  because  one 
may  be  sure  that  this  is  not  too  mneh,  aa  no  sample  of  glue  met  with  in  oommerce  ia 
as  pure  aa  isinglass.  The  vesael  containing  the  mixed  liquid  being  well  °*'°'"»'  and 
the  precipitate  having  settled,  another  o.c.  of  glue  solution  is  added  to  the  tannia 
solution,  which  is  next  filtered  through  a  moiat^ned  cotton  filter.  If  oiu  drop  of  (be 
glue  solution  still  produces  a  precipitate  in  the  clear  filtrate  mother  c.c.  is  added  to 
the  tannin  solution,  and  then  again  filtered,  these  operations  being  repeated  mttO  tfaa 
filtrate  is  no  longer  rendered  turbid  by  the  glne  solution. 

These  modes  of  testing  glue  give  only  an  approximate  value  of  the  glue,  «a  its 
precise  chemical  constitntion  is  not  known,  and  is,  in  all  piobabili^,  oomplex  ;  whil* 
it  baa  not  been  proved  that  the  anbstance  combined  with  tannin  correaponds  to  the 
adhesive  power  of  glue.  Finally,  it  should  be  observed,  that  gelatine  and  glne,  thno^ 
both  precipitated  by  the  some  qnsntity  of  tannin,  are  altogether  different  BDbstanaea. 
II.  MtchanUai  Modes  of  Tating  Olae. — Sohattenmann's  Method.— ^The  glne  to  be 
tested  ia  kept  immersed  for  a  considerable  time  in  a  large  quonti^  of  water  at  15*;  tba 
snbatanoe  swells  np.absorbingfivetosizteentimesits  own  weight  of  water.  The  more 
consistent  and  elastic  glne  is  found  to  be  in  this  state  the  greater  its  adhesive  power. 
The  larger  the  qnanti^  <rf  water 
^a-  >SS-  absorbed  the  more  economical  will 

the  glne  be  in  use.  Aconrding  la 
Weidenbusch's  experiments,  this 
method  should  be  employed  onljr 
with  glue  obtained  frran  bones,  •■ 
that  obtained  &om  animal  obi  does 
not  behave  similarly,  lipowitz  has 
proposed  the  following  method: — 
5  parts  of  glue  are  dissolved  ia 
such  a  quantity  of  water  that  th« 
weight  of  the  solution  is  equal  to 
50  porta.  Thia  solution  ia  kept  for 
twelve  honrs  at  16°  in  order  to 
cause  the  sdution  to  gulatiniae 
The  gelatine  obtained  is  placed  in 
a  glass  veasel,  Fig.  356.  o  ia  a 
piece  of  tinned  iron  through  which 
the  iron  wire  b  movee  easily.  At  the 
lower  end  of  6  is  soldered  a  sooeer- 
like  piece  of  tinned  iron,  the  convex 
dde  of  which  ia  t&med  downwards.  The  weight  of  the  wire  h  and  the  coovax 
piece  soldered  to  it  ia  5  grms.,  while  the  fimitel,  0,  put  on  the  top  of  the  wire 


OLUE.  535 

also  weighs  5  grms.  The  fdnnel  is  of  sufficient  size  to  contain  50  grms.  of  small 
shot.  According  to  the  consistency  the  greater  weiglit  will  it  require  to  force  the 
gelatine  down  into  the  glass,  and  from  the  weight  required  the  adliesiyeness  may 
be  judged.  Heinze  has  tried  this  method  (1864),  and  the  results  of  his  experiments 
prove  the  correctness  of  Lipowitz's  proposition. 

Weidenhusch's  method  is  essentially  that  suggested  by  Karmarsch,  and  consists 
in  testing  the  weight  required  to  tear  asunder  two  pieces  of  wood  glued  together 
with  the  sample  of  glue :  but  it  is  evident  that  this  plan  is  not  satisfactory,  because 
it  is  impossible  to  obtain  wood  always  of  the  same  quality,  while  the  adhesiveness  of 
good  glue  is  greater  than  that  of  wood  itself.  Weidenbusch  has  evidently  observed 
that  the  method  is  not  reliable,  for  he  has  suggested  the  following  plan: — Small 
sticks  or  rods  are  made  of  gypsum,  are  gently  dried,  first  by  heat  and  next  over 
chloride  of  calcium  until  the  rods  do  not  lose  weight.  They  are  then  saturated 
with  solutions  of  samples  of  glue ;  the  fotce  required  to  break  these  rods  after  drying 
determines  the  strength  of  the  glue,  because  the  force  required  to  break  the  gypsum 
is  of  a  constant  value.  An  apparatus  has  been  contrived  by  the  aid  of  which  the 
weight  required  to  tear  asunder  the  dried  gypsum  rods  may  be  ascertained;  the 
average  weight  has  been  found  to  be  219  grms.  The  glue  to  be  tested  is  dried 
at  100°,  put  over  night  into  cold  water,  next  dissolved  in  hot  water,  the  solution 
being  so  arranged  as  to  contain  one-tenth  of  glue.  This  solution  is  coloured  with 
neutral  indigo  tincture  in  order  to  render  it  more  easily  discernible.  The  gypsum 
rods  are  left  in  the  solution  for  a  couple  of  minutes  and  then  dried  until  the  weight 
does  not  vaiy.  When  this  obtains  the  rods  are  broken  by  the  action  of  mercury, 
which  is  gradually  admitted  into  the  apparatus. 

liiagiMi.  The  substance  met  in  commerce  under  the  name  of  isinglass  is,  if 
genuine,  the  dried  interior  pulpous  vesicular  membrane  of  the  air-bladder  of  certain 
kinds  of  fish  belonging  to  the  order  of  the  cartilaginous  ganoids,  and  more 
espedally  of  the  common  sturgeon  (Aeoipenser  sturio) ;  the  huso,  or  grand  sturgeon 
(A.  sturio) ;  the  A,  Oulderutaedti,  and  A.  stellatus.  The  bladders  of  these  and  of  kin< 
dred  species  of  fish  plentifully  met  with  in  the  Caspian  Sea  and  the  estuaries  of  the 
rivers  running  into  it,  are  cut  open,  cleansed,  stretched,  and  dried  by  exposure  to  sun- 
light, and  when  sufficiently  dry  to  admit  of  being  handled  without  fear  of  tearing  the 
outer  muscular  membrane,  which  does  not  on  being  boiled  yield  any  glue,  is  torn  ojQT, 
while  the  interior  membrane  is  moulded  in  various  ways  (as  in  rings,  lyre-shaped,  or 
folded  as  leaves  of  paper),  and  bleached  by  sulphurous  acid,  then  thoroughly  dried 
hy  exposure  to  sunlight. 

According  to  the  countries  from  which  it  is  sent  into  the  trade  isinglass  is 
distinguished, — as  Russian  (the  best  kind  being  obtained  frt)m  Astrakan) ;  North 
American  (frt)m  Qadus  merlueim) ;  East  Indian  (irom.Polynemusplebeju8),Taiet'mXti  in 
leaves,  also  as  small  sacks,  and  in  the  entire  bladder ;  Hudson  Bay  isinglass  (derived 
from  sturgeons) ;  Brazilian  is  probably  obtained  from  various  kinds  of  Silurus  and 
PinuHadtu,  This  isinglass  occurs  in  hollow  tubes,  in  lumps,  and  in  discs.  German 
isinglass  is  prepared  at  Hamburg  from  the  air-bladder  of  the  common  sturgeon.  In 
Boumania  and  Servia  the  skin  and  intestines  (not  the  liver)  of  cartilaginous  fishes 
are  boiled  into  a  stiff  jelly,  which,  having  been  cut  into  thin  slices,  is  dried  and  sent 
into  the  market  as  isinglass.  As  regards  the  use  of  this  material  we  have  to 
distinguish  between  fish  glue  and  isinglass.  The  former,  if  properly  prepared,  is  not 
at  all  distinguishable  from  ordinary  glue  as  obtained  from  bones  or  other  animal 


53fi  CHEMICAL  TECHNOLOGY. 

refuse ;  but  isinglass  is  not  glue,  and  is  only  converted  into  it  by  boiling.  It 
of  fibres  or  threads,  wliich  when  placed  in  water  are  somewhat  dissolved,  but 
retain  their  organised  structure ;  this  being  especially  of  importance  for  the  use 
of  this  substance  in  clarifying  wine,  beer,  and  similar  fluids,  as  the  fibres  ooo- 
stitute  as  it  were  a  close  network,  wliich  readily  takes  up  the  turbidity  produced  by 
small  paiiicles.  The  presence  of  tannin  in  liquids,  which  are  intended  to  be  clari- 
fied by  the  use  of  isinglass  is  advantageous,  inasmuch  as  it  promotes  the  contractioB 
of  the  isinglass  fibres,  whereby  the  suspended  particles  present  in  the  fluid  to  be 
clarified  are  retained ;  so  that  in  truth  the  clarifying  by  isinglass  is  a  kind  of  filtntion, 
which  cannot  be  performed  either  by  glue  or  by  a  hot  saturated  solution  of  isinglass. 
For  isinglass  may,  in  all  otlier  instances,  such  as  the  dressing  of  woven  silk  fabzies, 
the  preparation  of  so-called  court-plaster  and  cements,  be  substituted  good  gelatxae. 
Under  the  name  of  IchtyocolU  Frati^aUe,  Rohart  some  years  ago  introduced  a  substi- 
tute for  isinglass,  a  compound  said  to  be  obtained  from  fibrin  of  blood  and  tft.nTiin 
8abiiututMforoine.andN«w      Beceutly  tliTce  substitutes  for  glue  have  been  introdueed, 

Preportttions  obtoiDed  ,  ^i.  !/»»».  in  «  ^ 

firomoiue.  Tiz. : — I.  Gluteu  gluc  (ooUe  gluten).    2.  Albumen  glue  {cviU 

vig€tale  ou  edbumittoide.     3.  Caseine  glue  {eoUe  caseine).     The  first  is  a  miztore 
of  gluten  and  fermented  flour.     It  is  a  very  sour  mixture,  endowed  with  but 
very    slight    adliesive   power.      Albumen   glue   is  partially  decayed  gluten*   the 
substance  largely    obtained    in    the   manufacture  of   starch  from  wheaten   ^aax 
thoroughly  washed  with  water,  and  then  exposed  to  a  temperature  of  15°'  to  20%  at 
which  it  begins  to  ferment  and  become  partly  fluid,  or  more  correctly  soft,  so  as  to 
admit  of  being  poured  into  moulds  which  are  placed  in  a  room  heated  to  25''  or  50^ 
for  twenty-four  to  forty-eight  hours.     The  sur£ebce  having  become  dry  enoi^ 
to  admit  of  the  cakes  being  handled,  they  are  taken  from  the  moulds  and  further 
dried  by  being  placed  either  on  canvas  or  on  wire  gauze.    After  four  to  five  days  the 
cakes  are  quite  dry  and  fit  for  being  kept  in  a  dry  place  for  any  length  of  tune.    A 
solution  of  this  substance  in  twice  its  weight  of  water  constitutes  a  normal  solution, 
which  may  be  diluted  according  to  tlie  use  desired  to  be  made  of  it.    This  kind  of 
glue  may  be  used  for  the  following  purposes : — Glueing  wood,  cementing  glaas, 
porcelain,  earthenware,  mother-of-pearl,  for  pasting  leather,  paper,  and  cardboard ;  it 
may  further  serve  as  weaver's  glue,  and  as  dressing  for  silk  and  other  woven 
fabrics;  also  for  a  mordant  instead  of  albumen  in  dyeing  and  printing  vanoos 
fabrics ;  and  lastly,  for  clarifying  liquids. 

Caseine  glue  is  prepared  by  dissolving  caseine  in  a  strong  solution  of  borax.  The 
thick  fluid  tlms  obtained  has  great  adhesive  powers  and  may  be  advantageously 
employed  by  joiners  and  bookbinders.  What  is  known  as  elastic  glue  is  a  prepara- 
tion of  glue  and  glycerine,  by  the  addition  of  which  glue  may  be  rendered 
permanently  elastic  and  soft.  It  is  prepared  in  the  following  manner: — Glue  is 
melted  in  water  by  the  aid  of  a  water-bath,  into  a  very  thick  paste,  to  which 
glycerine  is  added  in  the  same  quantity  by  weight  as  that  of  the  dry  glue.  Hie 
mixture  is  thoroughly  stirred  and  then  further  heated  in  order  to  evaporate  the 
excess  of  water.  The  mass  is  then  cast  on  a  marble  slab,  and  after  cooling,  serres 
for  the  purpose  of  making  printer's  inking  rollers,  elastic  figures,  galvano-plsstie 
moulds,  &c. 


PHOSPHORUS.  537 


Manufacture  of  Phosphoeus. 

oenani  Properiiet.  Phosphoras  was  discovered  in  1669  by  Brand,  at  Hamburg,  and 
prepared  by  him  from  nrine.  In  1769,  Gahn,  a  Swedish  chemist,  first  prepared  this 
element  from  bones;  his  mode  of  preparation  being  improved  in  177 1  by  his 
celebrated  countryman,  Scheele.  Since  the  introduction  of  phosphorus  matches,  its 
manufEkcture  has  become  one  of  the  most  important  technical  operations.  Phos- 
phorus occurs  largely  in  the  mineral  kingdom  as  phosphoric  acid,  but  for  the  manu- 
facture of  phosphorus  in  sufficient  quantity  only  in  such  minerals  as  apatite,  phos- 
pborite,  and  staffelite. 

Phosphorite  is  found  in  various  localities,  as,  for  instance,  near  Diez,  WeHburg, 
and  Amberg  and  Redwitz  in  Bavaria.  Some  of  this  phosphorite  is  very  rich  in 
phosphoric  acid,  a  sample  of  that  found  near  Diez  having  yielded  on  analysis  (by 
Petersen,  1866),  37*78  per  cent  of  phosphoric  acid,  correspondiog  to  1606  per  cent  of 
phosphorus. 

prapumtioD  of  pboBpbonu.  Bouc-ash  is  uow  the  only  material  used  by  phosphorus  makers, 
as  the  commercial  preparation  of  phosphorusiiftS  not  succeeded  by  using  either  apatite 
and  other  varieties  of  pure  phosphorite  which  contain  about  i8'6  per  cent  of  phos- 
phorus— as  well  as  sombrerite  (a  mineral  met  with  on  the  American  island  of  Som- 
hrero),  consisting  of  phosphate  and  carbonate  of  lime,  and  imported  into  England  for 
the  manufacture  of  superphosphates ;  or  the  Navassa  guano,  also  imported  from  the 
United  States,  containing,  according  to  Ulex's  researches,  one-third  of  its  weight  of 
phosphoric  acid;  or  phosphate  of  iron,  as  proposed  by  Minary  and  Soudray, 
by  distilling  that  substance  with  previously  well-ignited  coke-powder. 

Bones,  as  used  by  the  manufacturers,  contain : — 

In  dry  state,  but  not  ignited,  from  11  to  I2'0  per  cent  of  phosphorus. 
As  bone-black  „    16  to  i8'o    „     „     „        „ 

Asbone-ash  (white  burnt  bones)  „    20  to  25-5    „     „     „        „ 

The  composition  of  bone-ash  is  exhibited  by  the  following  results  of  analysis : — 

I.  2. 

Carbonate  of  lime    ip'07         9*4^ 

Phosphate  of  magnesia 2*98  2*15 

Tribasic  phosphate  of  lime    83*07        84*39 

Fluoride  of  calciiun 3*88         4*05 

The  bone-ash  is  decomposed  by  means  of  sulphuric  acid,  according  to  a  plan  first 
suggested  by  Nicolas  and  Pelletier: — 

a.  Bone-ash,  CajfPOJa      \  «,-oiri    f  Acid  phosphate  of  lime,  CaH4(P04) a 
Sulphuric  acid,  2HaS04)  ^®^^   I  Sulphate  of  lime,  2CaS04. 

The  acid  phosphate  of  lime  is  heated  with  charcoal,  and  converted  by  loss  of  water 
into  metaphosphate  of  lime : — 

*•  ^*|(P04)a-2HaO=Ca(P03)a. 


Acid  phosphate  Metaphosphate 

of  lime.  of  lime. 


2  P 


538  CHEMICAL  TECHNOLOGY. 

The  metaphosphate  of  lime  yields,  when  ignited  to  white-heat  with  diarcosl,  tv»- 
thirds  of  its  weight  of  phosphoms,  while  one-third  remains  in  the  residue: 


Charcoali  loG 


Phosphorus,  4P. 


The  ordinary  mode  of  preparing  phosphorus  inclndes  the  foUowing 
In  some  instances  the  preparation  of  phosphorus  is  cotemporaxy  with 
businesses,  yiz.,  glue-boiling,  the  preparation  of  sal-ammoniac,  yellow  praosate  of 
potash,  &Cm  but  generally  in  England  the  phosphorus  makers  do  not  evexi  buzzn  Ae 
bones  to  aahes,  but  purchase  bone-ash  and  occasionally  apatite ;  this  salt,  lioveva, 
is  very  difficult  to  treat  with  sulphuric  acid,  and  is  also  objected  to  on  aooomit  cf  its 
hardness,  for  it  has  to  be  ground  to  a  very  fine  powder.  Finglish  makers  onlj 
out  these  four : — 

1.  Burning  the  bones  and  grinding  the  bone-^  to  powder. 

2.  Decomposition  of  the  bone-ash  by  sulphuric  add,  and  evaporatioin  of  the 

phosphate  previously  mixed  with  charcoal. 

3.  The  distillation  of  the  phosphorus. 

4.  The  refining  and  preservation  of  the  phosphorus. 

^^'^HSf^""  ^-  The  bones  to  be  used  for  phosphorus  making  are  obtaiaed 
either  from  bone-boilers  or  from  the  waste  bone-black  of  sugar-refiners.  The 
of  the  ignition  of  the  bones  is  the  complete  destruction  of  the  organic  matter. 
operation  is  conducted  in  a  kiln  very  similar  to  those  in  use  for  burning  lime.  A 
layer  of  brushwood  having  been  put  at  the  bottom  of  the  kiln,  bones  form  the  next 
stratum,  and  so  on  alternately.  The  wood  having  been  lighted,  the  oambas- 
tion  of  the  bones  ensues.  In  order  to  carry  off  the  fumes,  the  smell  of  which  is  Tery 
offensive,  a  hood  made  of  boiler-plate  is  placed  on  the  kiln,  and  either  connected  with 
a  tall  chimney,  or  the  smoke  and  gases  are  conducted  into  the  fire  of  the  kiln  and 
burnt.  The  white  burnt  bones  are  withdrawn  through  an  opening  reserved  in  the 
wall  on  purpose,  the  kiln  being  kept  continuously  in  operation,  as  is  the  case  with 
some  Ume-kilns. 

100  kilos,  of  fresh  bones  yield  from  50  to  55  kilos,  of  white  burnt  bone-aih,  whaA 
is  converted  into  a  coarse  powder  by  means  of  machinery. 

^*°°"^SphSri?AddT^      2-  100  ^oa.  of  the  bone-ash,  of  which  aboat  80  per  eenl 
is  tribasic  phosphate,  require  for  decomposition : — 

10673  kilos,  sulphuric  acid  of  1*52  sp.  gr. 

85*68      ,,  „  „    „   170  ,,    „ 

7363      M  M  M    „   i*8o  „    „ 

Payen  advises  that  for  100  kilos,  of  bone-ash  100  parts  of  sulphuric  acid  at  50  per 
cent  or  1*52  sp.  gr.  be  taken,  The  operation  of  mixing  the  acid  and  bone-ash  a 
effected  in  lead-lined  wooden  tanks,  or  in  wooden  tubs  internally  coated  with  pitch  or 
coal-tar  asphalte.  The  liquor  decanted  from  the  precipitate  has  a  sp.  gr.  of  1*05  to 
1*07  =  8"*  to  10°  B.  The  sediment  is  lixiviated  with  water,  and  the  Hquor  obtamed 
(r=  5°  to  6^  B.)  evaporated  with  the  first  liquor  in  leaden  pans.  A  second  lixiviatiaii 
of  the  SQiiiment  yields  a  fluid  which  is  used  instead  of  water  for  the  purpose  of 
diluting  the  oil  of  vitriol.  The  evaporation  in  the  leaden  pans  (these  are  smaller,  hot 
otherwise  similar  in  construction  to  those  used  for  evaporating  sulphuric  acid)  is 
continued  until  the  fluid  has  attained  a  sp.  gr.  of  1*45  =  45^  B.,  when  it  is 


PHOSPHORUS.  539 

ith  chftrooal-powder,  or  rather  gnumlated  charcoaL  of  the  size  of  small  peas,  in  the 
proportion  of  20  to  25  parts  of  charcoal  to  100  of  liquor,  and  quickly  dried  after 
Ixaving  been  put  into  cast-iron  pots  placed  on  a  furnace. 

The  dry  mass  consists  of  phosphate  of  lime,  carbon,  and  water,  to  an  amount  of 
5  to  6  per  cent.  At  the  commencement  of  the  manufacture  of  phosphorus  the  idea 
ixreyailed  that  in  the  preceding  preparation  the  phosphoric  acid  was  present  in  free 
state,  while  the  lime  had  combined  with  sulphuric  add;  but  Fourcroy  and  Vau- 
«)iielin  finding  that  the  tri-basic  phosphate  of  lime  as  met  with  in  bone-ash 
<Ca3(P04)a)  was,  by  the  action  of  the  sulphuric  acid,  converted  into  acid  phos- 
phate of  lime  (CaH4(P04)a),  supposed  that  more  sulphuric  acid  was  required, 
aw  opinion  opposed  by  Javal,  who  proved  that  when  pure  phosphoric  acid  is  inti- 
mately mixed  with  carbon,  it  yields  only  a  small  quantity  of  phosphorus,  because  the 
add  is  volatilised  at  a  temperature  lower  than  that  required  for  its  decompodtion,  or 
xather  reduction  by  carbon.  Owing  to  the  presence  of  water  in  the  mixture,  there  is 
^ven  off  during  the  distillation  in  addition  to  oxide  of  carbon,  carburetted  and 
phosphuretted  hydrogen. 

Diatiii»tioaiofph4M»iM«i».  3.  The  mixturc  of  add  phosphate  of  lime  and  charcoal  is 
distilled  in  fire-clay  retorts  similar  in  shape  to  those  used  for  distilling  Nordhausen 
sulphuric  add,  while  the  furnace  in  which  these  retorts  are  placed  is  also  similar  in 
construction  and  holds  twdve  retorts  on  each  side.  The  body  of  the  retorts  is 
placed  on  the  dde  of  the  fire,  while  the  neck  passes  through  an  opening  in  the  wall 
of  the  furnace,  that  portion  of  the  wall  being  only  lightly  bricked  up,  as  the  retorts, 
after  the  distillation  is  finished  and  the  furnace  cooled,  have  to  be  removed,  in  order  to 
clear  out  the  reddne  and  introduce  fresh  mixture.  Between  eadi  pair  of  retorts  is  left 
B.  space  of  some  12  to  15  centims.,  in  order  to  afford  room  for  the  passage  of  the  flame. 
As  already  mentioned,  the  heat  causes  the  acid  phosphate  of  lime  (OaH4(P04)2),  to  be 
converted  into  metaphosphate  of  calcium  (Ca(P03)a)«  which,  with  increased  heat, 
gives  off  two-thirds  of  its  phosphorus,  there  being  left  in  the  retorts  one-third  in  the 
shape  of  tri-phosphate  of  caldum  iGa3(P04)a).  The  recdvers  used  in  Germany  are 
constructed  in  the  following  manner : — The  material  is  day,  glazed.  The  receiver 
consists  of  two  parts,  one  of  which  is  a  cylindrical  vessd  open  at  the  top,  into 
which  the  other  part  fits,  and  is  fixed  by  means  of  a  lim  which  is  prolonged  so  as  to 
form  a  neck,  between  which  and  the  first  part  is  inserted  a  tube  fitted  on  the  neck  of 
the  retort,  while  the  other  end  of  this  tube  dips  for  about  10  centims.  into  the 
receiver,  the  latter  being  filled  with  water.  Into  each  retort  6  to  9  kilos,  of  the 
mixture  intended  to  be  operated  upon  are  introduced ;  the  retorts  are  then  placed  in 
the  furnace  and  the  brickwork  is  restored.  This  having  been  done,  the  fire  is 
kindled  and  kept  up  very  gently  for  some  time  in  order  to  dry  the  fire-clay  used  in 
joining  the  bricks.  The  recdvers  are  filled  with  water  and  fitted  to  the  retorts. 
In  each  recdver  a  small  iron  spoon  is  placed  fastened  to  an  iron  wire  which  serves 
as  a  stem.  After  six  to  dght  hours'  firing  the  heat  has  been  so  much  increased  as  to 
cause  the  expuldon  of  any  moisture  left  in  the  material  placed  in  the  retorts,  while 
quantities  of  hydrocarbon  gases  and  oxide  of  carbon  are  formed  and  with 
sulphurous  add  expelled.  Subsequently  other  gases  are  given  off,  and  because  they 
contain  some  phosphuretted  hydrogen  are  spontaneoudy  inflammable.  As  soon  as 
this  phenomenon  is  observed,  the  joints  of  the  recdvers  and  apparatus  connecting  it 
with  the  retort  are  luted  with  clay,  care  being  taken  to  leave  by  the  insertion  of  an 
iron  wire  a  small  opening  for  Uie  escape  of  the  gases,  which  are  as  speedily  as 


540 


CHEMICAL  TECBNOLOQY. 


possible  removed  by  well-aiTAnged  Tentilalora  ttaai  the  bnildiiig  in  whidi  fti 
furnace  is  placed.  The  appetuance  of  amorphooa  phosphoms  at  the  bdmU  cfttiq 
i&djcatea  the  conunencement  of  the  diatillatioii.  The  spoon  is  then  placed  in  tb 
Teceiver  in  auch  a  direction  that  anj  pliosplioruB  coining  orer  may  collad  in  it 
Soring  the  progreBB  of  the  operation,  and  as  long  as  Buy  phoBphoma  diatila  am. 
the  evolution  of  combnstihle  gnees  continues,  and  consequently  a  Email  hlne-oobmi 
flame  is  obaerved  at  the  opening  in  the  lute.  The  water  in  the  teeeinn  a 
kept  cool  during  the  operation.  After  forty-six  hours,  with  a  greatly  increased  ira^ 
a  ftill  white-heat  is  reached,  and  the  quantity  of  phosphoms  coming  ova  1m 
decreased  so  much  aB  to  make  a  continuation  of  the  ignition  process  wasteful  llx 
receivers  are  therefore  diBconnected  from  tlie  retorts,  and  the  crude  phogphana. » 
mixtnre  of  silicide  of  phosphorus,  carburet  of  phoaphoroB,  amorphoos  phosphonii.  nd 
other  allotropic  modificstionH  of  this  element,  is  poured  into  a  tub  containing  nM. 
The  furnace  having  become  cool  is  broken  up  and  the  retorts  are  removed,  th*  f» 
tents  taken  out  with  an  iron  apatula,  and  the  retorts  replaced  alter  having  bM 
re-filled  with  fresh  mixture.  loo  kilos,  of  the  mixture  yield  about  14'S  kiks.  " 
crude  and  126  kilos,  of  refined  phosphorus.  As  to  Wohler'e  method  of  pt^anQ 
phosphorus  by  the  ignition  of  a  mixture  of  charcoal.  Band,  and  bone-ash,  the  proMi 
is  not  well  adapted  for  practical  use,  because  it  requires  a  very  high  temperiOnt 


Fio-  as7. 


Fio.  358. 


which  would  melt,  or  nearly  so,  and  at  any  rate  soften,  the  retorts.  Moreovai "" 
proposed  mixtnre  contains  only  one-third  the  quantity  of  phosphonc  acid  met  wilt 
in  Uie  mixture  now  in  general  use. 

■  '"SiKKSjb™"*  4-  ■^s  ahready  stated,  the  crude  phosphorwa  is  contaniBsI*' 
with  carbon,  ulicium.  red  and  black  phosphorus,  and  various  other  impuritiee,  vbici 
in  former  days  were  eliminated  by  forcing  the  phosphorus  tlirough  the  pores  of  stoB 
wash-leather  by  means  of  a  macbino  exhibited  in  Fig.  257,  c  representing  a  ^^^' 
tied  piece  of  waah-leatherconlaiuing  the  crude  phosphorus,  the  bag  being  [Jaced  on 
a  perforated  copper  support,  situated  in  a  vessel  filled  with  water  at  50°  to  60°.  ^ 
soon  as  the  phosphorus  is  molten,  there  ia  placed  on  the  wash-leather  a  wot^ 


PHOSPHORUS. 


541 


plate,  D  D,  which  by  the  aid  of  the  mechanical  arrangement  e,  and  the  lever,  o  o,  can 

be  forced  downwards  so  as  to  cause  the  fluid  phosphorus  to  pass  through  the  pores  of 

the  leather,  the  impurities  being  retained.    More  recently  French  manufacturers 

liave  introduced  another  system  of  purifying  phosphorus,  viz. :— a.  By  filtration 

throngh  coarsely-powdered  charcoal,  which  is  placed  in  a  layer  of  6  to  10  centims.  on  a 

perforated  plate  of  the  vessel  a,  Fig.  258,  two-thii*ds  filled  with  water,  kept  by  means  of 

the  water-bath,  b,  at  a  temperature  of  60°.   The  molten  phosphorus  placed  on  a  passes 

through  the  layer  of  charcoal,  and  is  thereby  purified.    It  flows  through  the  open 

tap  c  and  the  tube  e,  being  collected  in  the  vessel  f  filled  with  water,  maintained  by 

means  of  the  water-bath,  o,  at  a  temperature  sufficiently  high  to  render  the  phos^ 

phorus  fluid,  so  that  it  may,  when  aided  by  hydraulic  pressure,  pass  through  the 

perforated  bottom,  h,  and  the  wash-leather  spread  over  it.    The  filtered  phosphorus 

may  be  run  off  by  means  of  the  tap  j. 

According  to  another  process  of  purification  (6),  porous,  unglazed  porcelain  or 

earthenware  plates  are  fixed  in  an  iron  cylinder  connected  with  a  steam-boiler.    The 

steam  yielded  by  the  latter  forces  the  molten  phosphorus — previously  mixed  with 

charcoal  powder  for  the  purpose  of  preventing  the  pores  of  the  plates  becoming 

choked — ^through  the  earthenware  plates.    The  charcoal  containing  some  phosphorus 

is    used  in   the    distillation  of   the   phosphorus.     This  method    of  purification 

yields  from  100  kilos,  of  crude,  95  kilos,  of  refined,  phosphorus.    In  Germany  crude 

phosphorus  is  purified  by  distillation,  this  operation  being  carried  on  in  iron  retorts 

of  a  peculiar  make  and  sliaped  like  the  glass  retorts  used  in  chemical  laboratories. 

The  neck  of  these  retorts  dips  for  a  depth  of  15  to  20  millimetres  in  water  contained 

in  a  basin  filled  to  the  rim,  so  that  any  phosphorus  which  is  discharged  into  this 

water  causes  it  to  overflow.    The  crude  phosphorus  having  been  fiised  under  water 

is  next  mixed  with  12  to  15  per  cent  of  its  weight  of  moist  sand,  and  this  mixture  is 

placed  in  the  retorts  in  quantities  of  5  to  6  kilos.,  the  object  of  the  mixing  with  sand 

being  to  prevent  the  phosphorus  becoming  ignited  during  the  filling  of  the  retorts. 

Crude  anhydrous  phosphorus  yields  by  this  process  of  distillation  about  90  per  cent 

of  the  refined  product.    In  a  phosphorus  manufactory  at  Paris  the  crude  phosphorus 

is  purified  by  chemical  means,  viz.,  by  mixing  with  100  Idlos.  of  the  crude  substance 

3*5  kilos,  of  sulphuric  acid  and  the  same  quantity  of  bichromate  of  potash;  a  slight 

efiervescence  ensues,  but  the  result  is  that  the  phosphorus  is  rendered  very  pure,  and 

may,  after  washing  with  water,  be  at  once  cast  in  the  shape  of  sticks.    The  yield  of 

refined  phosphorus  by  this  process  is  96  per  cent. 

'^^'^pSiSJrSi*"**  I*  ^*®  ^^^B  ^®®^  ^^  custom  to  mould  phosphorus  into  tlie  shape 
of  sticks  formed  by  the  aid  of  a  glass  tube  open  at  both  ends,  one  of  these  being  placed 
in  molten  phosphorus  covered  by  a  stratum  of  warm  water.  The  liquid  phosphorus 
is  sucked  by  the  operator  into  the  tube  until  it  is  quite  filled.  The  lower  opening  of 
the  tube  being  kept  under  water  is  closed  by  the  finger  of  the  operator ;  the  tube  is 
instantly  transferred  to  a  vessel  filled  with  very  cold  water,  by  which  the  phosphorus 
IB  solidified.  It  is  removed  from  the  glass  tube  by  pushing  it  out  with  a  glass  rod^or 
iron  wire  while  being  held  under  water.  Instead  of  suction  by  the  mouth,  a 
oaoutchouc  bag  similar  to  that  used  in  volumetric  analysis  for  the  purpose  of  sucking 
liquids  into  pipettes  may  be  employed.  In  the  French  phosphorus  works  the  glass 
tubes  are  fittsd  at  the  top  with  an  iron  suction  tube  provided  with  a  stop-cock.  The 
operator,  who  has  from  one  to  two  thousand  of  these  tubes  at  his  disposal,  sucks, 
either  by  mouth  or  with  a  caoutchouc  bag,  the  molten  phosphorus  into  the  glass  tube. 


541  CHEMICAL  TECHNOLOOr. 

and  lutving  turned  off  the  atop-cook,  npidlj  trtDsfen  the  tube  to  a  ressel  filled  wilk 
cold  water.  When  all  the  tnbea  are  filled  the  phoaphoma  is  removed  by  opening  the 
atop-cock  and  pnahing  Uke  stick  out  hy  the  aid  of  a  wire.  A  clever  worlcman  ma; 
mould  in  this  way  2  owta.  of  phospbomg  dailj. 

Another  mode  of  performing  the  moulding  has  been  inbudnced  by  Senbert.  Hie 
apparatos  contrived  bj  him  for  this  porpose  is  exhibited  in  Fig.  260,  and  oonaiati  of 
a  copper  boiler  fitted  on  a  furnace  1  to  tbe  flat  bottom  of  this  boiler  ia  fastened  fajr 
hard  solder  an  open  copper  trough  oonunnnicating  with  the  water-tank,  c.  In  the 
boUer  ie  fitted  a  copper  funnel,  a,  provided  with  a  horizontal  tube,  a.  Thia  porlioa 
of  the  apparatus  is  intended  f(»  the  reception  of  the  pbospboroa,  of  which  it  will 
hold  8  to  10  kilos.  At  the  end  of  the  horizontal  tube,  b,  is  placed  a  stop-oodt,  a, 
while  the  portion  of  the  projecting  mouth  of  the  tube  boToad  the  ooek  ia  widened 
ont  and  fitted  by  means  of  bolts  and  nuts  with  a  flange-like  copper  plate,  into  which  are 
inserted  two  ^ass  tnbes,  a  a.  Into  the  copper  trough  is  let  a  wooden  partitMU,  o  t, 
which  serves  the  porpose  as  well  of  supporting  the  glass  tnbes  aa  of  preventing 
the  commnnicatdon  of  the  hot  water  in  the  boiler  and  a  portion  of  th«  troo^ 
with  the  cold  water  of  the  tank  and  the  portion  of  trough  nearest   to  it.     The 


vessel  A  having  been  filled  with  refined  phosphoms,  the  water  in  n  is  gently  « 
80  as  to  cause  the  fnsion  of  the  phosphorus.  As  the  warm  water  reaches  to  tfaa 
partition,  c  e,  it  is  clear  that  on  opening  and  closing  the  tap  B,  some  phoaphorua  will 
pass  throngh  and  flow  out  of  the  tubes  a  a,  but  that  remaining  in  these  tnbea  will 
solidiiy,  and  on  opening  the  tap  b  again  the  solid  sticks  of  pboaphorus  may  ba 
removed  from  the  glass  tubes  by  taking  hold  of  the  piece  of  projecting  phosphoms. 
the  phosphorus  being  immediately  inunersed  under  water  in  the  tank  c,  and  kept 
there  protected  from  the  action  of  the  light  While,  according  to  Senbert,  it  wobU 
be  possible  for  a  workman  to  mould  in  an  hour's  time  30  to  40  kilos,  of  phosphoraa. 
Fleck  has  found,  that  under  the  most  favourable  conditions  of  temperatnre,  it  take* 
six  hours  to  mould  50  kiloa  of  phosphoms.  If  it  is  desired  to  prepare  granulated 
phosphorus  with  this  apparatus,  a  stratum  of  6  to  8  centims.  tbiokneas  of  hot  watm-  i* 
so  carefully  poured  on  cold  water  as  not  to  mix  ;  next  the  tap  a  is  opened  enilidwit^y 
to  cause  Uie  phosphorua  to  form  drops,  which,  immediately  on  falling  iato  the  wld 


PHOSPHORUS.  543 

wftter,  becomes  ft  hard  solid  mass.  For  practical  purposes  grannlated  phosphoms  is 
preferable  to  the  moulded  sticks.  The  phosphorus  is  stored  either  in  strong  sheet- 
iron  tanks  or  in  wooden  boxes  lined  with  thinner  (tinned)  sheet-iron,  these  yessels 
being  capable  of  holding  6  cwts.  of  phosphorus  covered  with  a  stratum  of  water  fully 
3  eentims.  deep.  When  large  quantities,  say,  from  i  to  5  cwts.,  of  phosphorus  have 
to  be  sent  off,  it  is  usually  packed  in  water  in  small  wine  casks,  and  the  casks  having 
been  tightly  closed,  are  coated  externally  with  molten  pitch,  then  rolled  through 
chaff,  and  lastly  covered  with  stout  canvas  sewed  tightly  round  the  cask.  Another 
method  of  packing  phosphorus  consists  in  placing  it  in  well-made  water-tight  sheet- 
iron  or  tinned  iron  canisters,  such  as  are  largely  used  in  London  for  the  purpose 
more  particularly  of  conveying  oil  paints,  and  which  are  closed  by  soldering  on  a  lid 
veiy  securely.  In  some  cases  these  canisters  are  packed  in  wooden  boxes  to  the 
number  of  six  or  twelve  according  to  size  and  weight. 

**ftIi»rt5MS<55S™L°'  Among  the  many  suggestions  as  to  the  preparation  of  phos- 
phorus, we  may  mention  Donovan's  plan  of  obtaining  this  element  by  the  calcination 
of  a  mixture  of  finely  divided  charcoal  and  phosphate  of  lead,  prepared  by 
digesting  10  kilos,  of  broken-up  bones  with  6  kilos,  of  nitric  acid,  and  40  litres 
of  water ;  this  liquid,  after  having  been  decanted  from  the  gelatinous  material  of  the 
bones,  is  treated  with  a  solution  of  8  kUos.  of  acetate  of  lead.  The  washed  and 
dried  precipitate  of  phosphate  of  lead  is  next  ignited,  and  afterwards,  when  cold, 
mixed  with  one-sixth  of  its  weight  of  lamp-black  or  charcoal  powder.  Cari-Mon- 
trand  exposes  a  mixture  of  bone-ash  and  carbonaceous  matter  at  red  heat  to  the 

action  of  hydrochloric  acid  gas : — 

(Phosphorus,  P^ 
Chloride  of  calcium,  3CaCl 
Hydrogen,  3H, 


Calcium  tri-phosphate,  Ca3(P04)a 
Carbon,  8C 
Hydrochloric  acid,  6C1H 


yield 


Carbonic  oxide  gas,  SCO 
Neither  of  these  methods  have  been  tried  practically  on  the  large  scale. 
TiMsk'i  Pre  MM.  By  this  method  the  preparation  of  phosphorus  is  allied  to  that  of 
glue-  and  size-making.  The  process  is  based  upon  the  solubility  of  phosphate  of 
lime  in  hydrochloric  acid,  and  the  separation  of  an  acid  phosphate  of  lime  on  the 
evaporation  of  the  solution,  carried  on  in  earthenware  evaporating  basins.  Theo- 
retically, 156  parts  of  tribasic  phosphate  of  lime  (Ca3(P04)2)  require  73  parts  of 
anhydrous  hydrochloric  acid,  whereby  are  formed — of  chloride  of  calcium,  in  ;  of 
acid  phosphate,  100 ;  and  of  water,  18  parts.  By  the  ignition  of  100  parts  of  add 
phosphate  of  lime  with  20  parts  of  carbon,  are  generated— of  phosphorus,  21*3 ; 
of  tri-phosphate  of  lime,  52 ;  and  of  oxide  of  carbon,  46*7  parts. 

By  re-heating  the  tri-phosphate  of  lime  remaining  in  the  retorts  with  hydro- 
chloric acid  another  portion  of  acid  phosphate  of  lime  might  be  obtained ;  and  as  far 
as  experiments  have  been  made,  it  is  proved  that  it  is  possible  to  extract  aU  the 
phosphorus  contained  in  bones,  by  working  with  hydrochloric  acid  free  from 
sulphuric  acid,  and  carefully  evaporating  the  acid  solution  thus  obtained.  Practi- 
cally the  process  includes  the  following  operations: — i.  Cleaning,  breaking  up,  and 
exhausting  the  bones.  2.  The  evaporation  of  the  acid  liquid ;  crystallisation  of  the 
acid  phosphate,  and  mixing  of  the  latter  with  charcoal.  3.  The  distillation  and  purifi- 
cation of  the  phosphorus ;  and  finally, — 4.  The  glue  boiling.  The  bones,  previously 
crushed  and  deprived  by  boiling  of  the  fat  they  contain,  are  macerated  in  dilute  hydro- 
chloric acid  at  7°  B.^^sp.  gr.  1*048,  and  tiien  in  a  stronger  acid  at  30°  B.=:sp.  gr.  1*2461 
in  which  the  bones  are  left  until  they  have  become  quite  soft.    The  h'quid  which  has 


544  CHEMICAL  TECHNOLOGY, 

served  this  purpose  is  afterwards  employed  with  water  in  preparing  ihe  first  vid 
liquor  for  the  exhausting  of  the  bones.  Tlie  first  liquor,  a  solutioii  of  add 
phosphate  of  lime  (superphosphate)  and  chloiide  of  calcium,  obtains  a  sp.  gn  of 
I*ii8  =  i6°  6.  This  acid  liquid  is  evaporated,  but  this  operation  cannot  be  pnh 
ceeded  with  in  leaden  vessels,  and  tliere  is  some  difficulty  in  finding  very  kxgB 
evaporating  basins  made  of  porcelain  or  earthenware  which  will  answer  tl^ 
purpose.  As  soon  as  the  liquor  has  reached  a  density  of  30*'  B  =  sp.  gr.  1*246,  it  e 
sufficiently  concentrated  to  crystallise ;  on  cooling,  the  crystals,  having  been  hf 
means  of  pressure  separated  from  the  mother-liquor,  are  mixed  with  one-fourth 
of  their  weight  of  charcoal  powder.  They  are  then  heated  to  loo**  in  the  poreekia 
or  earthenware  vessels,  so  as  to  obtain  a  dry  mass  which  admits  of  being  sifted 
tlirough  a  copper- wire  gauze  sieve,  after  which  the  material  is  put  into  pecnhiil]f 
shaped  retorts  and  calcined  for  the  purpose  of  yielding  phosphorus.  The  residsfi 
left  in  the  retorts  is  afterwards  calcined  with  access  of  air  so  as  to  bam  off  ^ 
charcoal,  and  the  remaining  phosphate  of  lime  is  again  treated  with  strong  hydro- 
chloric acid,  yielding  a  concentrated  liquor  which  does  not  require  much  evaporatido. 
The  phosphorus  obtained  by  this  process  is  refined  as  already  described,  tke 
softened  bones  being  treated  for  glue  and  size. 
o«nteie,  G«riand,  Minanr,         Accordiug  to   a  communicatiou  published  by  Gentele  ii 

and  Soudry'H  Methods  of  _  «,  .> 

Preparing  Fhosphonu.  1 857,  upou  a  plan  of  phosphorus  manufacture,  he  com- 
bines that  industry  with  the  preparation  of  sal-ammoniac.  'The  bones  are  treated 
with  hydrochloric  acid.  To  the  resulting  solution  crude  carbonate  of  ammonia  ii 
added ;  this  substance  being  obtained  as  a  by-product  of  the  manufacture  of  aninial 
charcoal.  The  phosphate  of  lime  precipitated  is  employed  in  the  preparation  of 
phosphorus,  while  the  solution  of  chloride  of  ammonium  is  evaporated  and  sublimed. 
Gerland  (1864)  suggests  the  treatment  of  bones — ^first,  with  an  aqueous  solution  of 
sulphurous  acid,  the  heating  of  the  liquor  obtained  with  the  view  of  expelling  the 
acid,  wliich  being  again  absorbed  by  a  layer  of  coke  (a  coke  column  such  as  used  in 
alkali  works  to  absorb  hydi'ochloric  acid),  the  phosphates  first  held  in  solution  are 
precipitated  by  the  elimination  of  the  sulphurous  acid.  Minary  and  Soudiy  (1865) 
proposed  to  prepare  phosphorus  from  a  mixture  consisting  of  phosphate  of  iron  and 
well-ignited  coke. 

propeiiieiof  phosphoroa.  When  perfectly  pure  and  kept  under  distilled  water,  whidi 
previously  to  being  employed  for  this  purpose  has  been  by  boiling  deprived  of  the 
air  it  held  in  solution,  and  has  been  cooled  eitlier  under  a  layer  of  oil  or  in 
well-stoppered  bottles,  and  in  perfect  darkness,  phosphorus  is  a  colourless  and  trans- 
parent substance ;  but  usually  it  has  a  white-yellow  colour  and  waxy  appearance: 
Its  sp.  gr.  is  =  1*83  to  I  84.  When  the  temperature  of  the  air  is  not  too  kw 
this  element  is  as  soft  as  wax,  but  becomes  brittle  in  cold  weather.  Phosphoru 
cannot  be  pulverised ;  is  tough  ;  but  when  molten  in  a  bottle  under  warm  water  and 
shaken  until  the  fluid  is  quite  cold,  the  substance  is  thereby  reduced  to  a  finely 
divided  state ;  instead  of  water  it  is  better  to  use  either  alcohol,  urine,  or  a  weak 
aqueous  solution  of  urea.  Phosphorus  fuses  at  44°  to  45°,  and  remains,  especiaDy  if 
kept  imder  an  alkaline  solution,  fluid  for  a  considerable  time  though  cooled  far  below 
its  melting-point,  but  solidifies  suddenly  when  touched  by  a  solid  body.  At  290* 
phosphorus  boils,  and  it  evaporates  sensibly  at  the  ordinary  temperature  of  the  air. 
By  slow  oxidation  (fumes  of  phosphorus  are  given  ofl*  at  the  ordinary  temperature  of 
the  air)  there  is  formed  not  only  phosphorous  acid  but  nitrate  of  ammonia  and 


PHOSPHOSas.  545 

Phosphoms  is  in  tbe  eUto  of  vapour  slightly  soloble  in  water.  The  solid 
element  itself  is  slightly  soluble  in  alcohol  and  ether,  also  in  linseed  oil  and  oil  of 
torpentina,  the  best  solvents  being  sulphide  oi  carbon,  chloride  of  sulphur,  and 
chloride  of  phosphoms.  At  75°  phosphoras  ignites  in  coutact  with  air,  and  in  order 
to  ignite  it  bf  friction  this  temperature  has  to  be  reached.  Amorphous  or  red 
phoephoros  requires  a  very  high  temperature  (300°)  for  ignition.  Commercial 
phoHphams  nsnallf  contains  some  impurities,  such  as  snlphnr,  arsenic,  and  Hometimes 
traeea  of  calciiun,  dne  to  the  lime  of  the  bone-ash  used  in  the  preparation.  Beside 
being  used  in  chemistry,  phosphorus  is  chiefly  employed  in  the  making  of  matches ; 
also  for  what  is  termed  liquid  fire  (a  solution  of  phosphorus  in  sulphide  of  carbon),  for 
the  preparation  of  tar  colours,  and  for  hardening  some  copper  alloys. 

AiKiphDiu  at  Bad  rboaptutiB.  Dr.  Schrbtter,  of  Vienna,  discovered  in  1848  that  the 
property  possessed  by  ordinary  phosphoms  (first  noticed  in  1844  by  E.  Kopp) 
of  becoming  coloured  red  by  the  action  of  light,  was  due  to  the  formation  of  an 
allotropic  modification,  which  has  been  since  termed  red  or  amorphous  phosphoms. 
This  is  best  prepared  by  heating  ordinary  phosphorus,  with  exclusion  of  air  and 
water,  in  a  closed  vessel  and  under  pressure,  to  250°  for  a  length  of  time.  On  the 
lar]ge  scale  this  operatiun  is  conducted  in  an  apparatus  invented  by  A.  Albright,  of 
Bimungham.  In  Fig.  261,  g  represents  a  glass  or  porcelain  vessel,  filled  for 
five-sixths  of  its  capacity  with  pieces  of  phosphorus  to  be  heated  to  230°  to  250°. 
The  vessel/is  placed  in  a  sand-bath,  b,  heated  by  the  fire.  To  the  vessel  g  is  fitted 
an  air-tight  lid,  into  which  is  fiistened  tlie  bent  tube,  i,  provided  witli  a  tap,  k,  and 
dipping  into  the  vessel  n,  which  is  filled  with  water,  or  preferably  with  mercury 
covered  with  a  layer  of  water.  The  tap.  k,  is  left  open  at  the  commencement  of  the 
operation  for  seenring  the  escape  of  the  air  contained  in  g,  and  as  soon  as  no  more 
■ir  escapes  the  tap  is  dosed,  and  p^,  261. 

the  heat  increased  so  as  to  con- 
vert the  ordinary  into  amorphous 
phoaphoms.  The  time  required  for 
the  operation  depends  upon  con- 
ditions which  can  only  be  met  by 
experience.  After  the  thorough 
cooling  of  the  apparatus,  the  vessel 
g  is  opened,  and  Uie  red  phos- 
phoms removed.  It  is  then  placed 
under  water  and  crashed  to  a  pulp 
in  order  to  remove  any  nncon- 
verted  ordinary  phosphoms.  Sul- 
phide of  carbon  might  be  used  for 
this  purpose,  but  the  danger  of 
ignition  (by  accident)  of  the  solu- 
tion of  ordinary  phosphoms  thus 
obtained  is  prohibitive.  Nicklfis  proposiH  to  separate  ordinozy  from  amorphous 
phosphorus  by  shaking  up  the  mixture  of  amorphous  and  ordinary  plLOBp)ioru3  with 
ft  fioid,  the  specific  gravity  of  which  is  less  than  tliat  of  amorphous  phosphorus  (z*i), 
and  greater  than  that  of  ordinary  phosphoms  {rS^).  A  solution  of  chloride  of  cal- 
cium at  38°  to  40°  B.  can  be  used  for  this  purpose  ;  the  ordinary  phosphorus  floats  in 
this  fluid  and  con  then  be  readily  taken  up  by  sulpliidc  of  carbon,  while  the  operation 


546  CHEmCAL  TECHNOLOGY. 

can  be  carried  on  in  a  closed  vesseL  When  very  large  qnantities  of  ftmarphBOB 
phosphoms  have  to  be  pnrified  it  is  best  to  follow  Coignet's  plan,  conaiating  in 
treating  the  boiling  mixtare  of  the  two  varieties  of  phosphoms  with  cavalie  aoda 
solution,  whereby  ihe  ordinary  phosphoms  is  converted  into  phosphnretted  hjdrogoi 
gas  and  hypophosphite  of  soda  is  formed.  Hie  remaining  amorphons  phoa^hons 
being  purified  by  washing  with  water.  R.  Bottger  suggests  the  use  of  a  salntzon  of 
sulphate  of  copper,  which  with  ordinary  phosphorus  forms  phosphuret  of  copper. 

^'^'^SSiiS?^**^  This  substance  occurs  either  in  powder  of  a  red  or  aoakk 
colour  or  in  lumps  of  a  red-brown  hue ;  fracture  conchoidal,'  sometimes  with  aa 
iron-black  hue;  sp.  gr.  =  2'i.  Amorphous  phosphorus  is  not  soluble  in  sulphide 
of  carbon  or  other  solvents  of  ordinary  phosphorus.  It  is  unaltered  by  eicposnre  to 
air;  and  when  heated  to  290"  is  re-converted  into  ordinary  phosphorus.  Whm 
mixed  and  rubbed  with  dry  bichromate  of  potash  red  phosphorus  does  not  explode^ 
and  when  mixed  with  nitre  it  does  not  bum  off  by  friction,  but  only  by  appHcaiiai 
of  heat  and  then  noiselessly.  It  explodes,  however,  when  mixed  with  trhloTrntft 
of  potash.  With  peroxide  of  lead  amorphous  phosphorus  ignites  by  frictioQ  with  a 
alight  explosion,  but  when  heat  is  also  applied  a  violent  explosion  ensues. 

Owing  to  its  properties  and  behaviour  with  several  oxides,  moreover  its  non-vola- 
tility and  non-poisonous  properties,  amorphous  phosphorus  is,  as  well  as  on  soooimt 
of  its  less  ready  ignition,  an  excellent  material  for  the  making  of  matches ;  but 
amorphous  phosphorus  is  not  in  general  use  for  this  purpose.  It  is,  however,  used 
for  preparing  iodide  of  phosphorus,  which  serves  for  the  preparation  of  iodidfls 
of  amyl,  ethyl,  and  methyl,  used  in  the  manufacture  of  cyanin,  ethyl  violet,  and 
other  coal-tar  colours.  Sir  William  Armstrong's  explosive  mixture  fior  sihelli 
contains  amorphous  phosphorus  and  chlorate  of  potash.  From  66,000  cwtB..of 
there  are  annually  prepared  in  Europe  some  5500  cwts.  of  phosphorus. 


Requisites  for  Puoducino  Fibs. 
otMmuuMandHiatory.  Accordiug  to  the  Writings  of  the  ancients,  Prometheus  drew 
fire  from  stones  by  their  concussion.  The  Romans  rubbed  together  two  pieces  of 
hard  wood  for  producing  by  friction  sufficient  heat  to  ignite  diy  leaves  fitdlen  ftom 
trees ;  wlple  Darwin  and  the  Prince  of  Neuwied  state  that  the  uncivilised  zaoes  of 
man  obtained  fire  by  the  rapid  rotation  of  two  pieces  of  wood.  Turners  at  tbe  pie- 
sent  day  employ  friction  in  the  carbonisation  of  wood  for  ornamental  pmposea. 
During  Titus's  reign  the  Romans  obtained  fire  by  rubbing  decayed  wood  between 
two  stones,  along  with  a  small  thin  roll  of  sulphur.  In  the  fourteenth  century,  1I10 
tinder 'box,  with  the  fiint  and  steel,  became  known,  and  also  the  so-called  Qennsa 
tinder,  a  prepared  cryptogamic  plant.  Till  1820  these  remained  generaUj  the 
chief  means  of  obtaining  fire,  aided,  of  course,  by  the  wooden  splints  tipped  with 
sulphur* 

In  the  year  1823,  Dobereiner,  at  Jena',  discovered  that  finely  divided  spongy 
platinum  has  the  property  of  igniting  a  mixture  of  atmospheric  air  and  hydrogn 
gas,  and  he  contrived  the  so-called  Dobereiner  hydrogen  lamp,  which  has  been,  and 
is  still,  occasionally  employed  to  procure  fire  and  light.  About  the  same  period 
there  was  invented  a  kind  of  phosphorus  match  of  the  following  arrangement 
Equal  parts  of  sulphur  and  phosphorus  were  cautiously  fused  in  a  glass  tube ;  after 
the  fusion  was  completed  the  tube  was  tightly  corked.    If  it  were  desired  to  obtain 


PHOSPHORUS.  547 

fire,  a  thin  splint  of  wood  was  immersed  in  this  mixtnre,  and  some  of  it  having  been 
fixed  to  the  wood,  the  latter  on  being  brought  into  the  air  became  ignited  by 
the  combostion  of  the  mixed  substances,  which  took  fire  spontaneously  in  the  air. 
It  is  evident  that  this  rather  clumsy  contrivance  never  became  general.  Of  far 
more  importance  as  suited  for  practical  purposes  were  the  chemical  matches  or  dip 
splints,  first  manufactured  at  Vienna,  as  early  as  i8x2.  These  splints  were  tipped 
with  sulphur  covered  with  a  mixture  of  chlorate  of  potash  and  sugar,  to  which 
for  the  purpose  of  imparting  colour  was  added  some  vermillion,  while  a  little 
glue  gave  a  pasty  and  adhesive  consistency. 

By  touching  this  composition  with  concentrated  sulphurie  acid  ignition  ensued ; 
the  acid  was  kept  in  a  small  glass  or  leaden  bottle  into  which  some  asbestos  had 
been  inserted,  which  acted  as  a  sponge  for  the  acid.    The  only  friction  matches 
known  up  to  the  year  1844  ^^^  discovered  and  made  by  M.  Chancel,  assistant  to 
the  well-known  Professor  Thenard  of  Paris,  1805.    The  Prometheam,  first  made  in 
England  in  or  about  the  year  1830,  were  contrived  on  the  same  principle,  viz.,  the 
ignition  by  friction  between  two  hard  substances  of  a  mixture  of  chlorate  of  potash 
and  sugar  fixed  to  a  kind  of  paper  cigarette,  which  contained  also  a  small  glass 
globule  filled  with  sulphuric  acid ;  however,  the  high  price  of  this  kind  of  match 
prevented  its  general  use.    Under  the  name  of  Congreves  the  first  real  friction 
matches  were  made  in  1832.    On  the  sulphur-tipped  splints  was  glued  a  small 
quantity  of  a  mixture  of  i  part  of  chlorate  of  potash  and  2  parts  of  black  sulphuret  of 
antimony,  to  which  some  gum  or  glue  was  added.    By  strongly  pressing  this  compo- 
sition between  two  pieces  of  sand-paper  the  mixture  became  ignited,  but  frequentiy 
also  on  becoming  detached  from  the  wooden  splint  flew  about  in  all  directions  with- 
out igniting  the  sulphur  or  the  wood.    It  is  not  well  known  who  was  the  first  to 
substitute  phosphorus  for  sulphuret  of  antimony;  but  according  to  Nicklis  phos- 
phorus matches  were  already  in  use  in  Paris  as  early  as  1805,  while  in  1809  Derepas 
proposed  to  mix  magnesia  with  phosphorus  in  order  to  lessen  its  great  inflammability 
when  in  finely  divided  state.    Derosne  (1816)  appears  to  have  been  the  first  who 
made  phosphorus  friction  matches  at  Paris.    However,  it  was  not  before  the  middle 
of  1833  ^^^  phosphorus  matches  became  more  generally  known,  when  Preshel,  at 
Vienna  (this  city  is  fiunous  for  the  match  and  fusee  industry  in  Germany),  made  not 
only  phosphorus  matches,  but  also  fusees  and  German-tinder  slips  tipped  with  the 
phosphorus  composition.    About  the  same  period  F.  Moldenhauer,  at  Darmstadt, 
made  phosphorus  lucifer  matches.    The  South  Germans  attribute  to  Kammerer  the 
invention  of  phosphorus  lucifer  matches,  while  in  England,  according  to  the  opinion 
of  the  late  celebrated  Faraday,  John  Walker,  of  Stockton,  Durham,  was  the  inventor 
of  lucifer  matches,  or  at  least  the  first  maker.    The  older  kind  of  matches,  although 
▼eiy  combustible,  ignited  with  a  rather  sharp  report,  owing  to  the  presence  of  chlorate 
of  potash  in  the  mixture,  while,  moreover,  the  too  ready  ignition  by  concussion 
rendered  the  transport  of  these  matches  so  unsafe,  that  in  Germany,  the  transport, 
as  well  as  the  manufieusture,  became  prohibited.    In  the  year  1835  Trevany  substi- 
tuted a  mixture  of  red-lead  and.  manganese  for  a  portion  of  the  chlorate  of  potash, 
thereby  greatiy  improving  the  composition.    In  1837  I^reshel  altogether  discarded 
this  salt,  substituting  peroxide  of  lead,  or,  as  Bottger  advised,  either  a  mixture  of 
red-lead  and  nitrate  of  potash,  or  of  peroxide  of  lead  and  nitrate  of  lead.    From  this 
period  the  manufacture  of  matches  became  an  extensive  industry,  greaUy  aided  by 
the  manufacture  of  phosphorus  on  the  large  scale. 


n 


548  CHEMICAL  TECHNOLOGY. 


In  the  course  of  time  other  improTements  were  made,  as,  lor  »^m^*»m*,  ^ 
substitution  for  sulphur  of  wooden  splints,  thoroughly  dried  and  soaked  in  wo. 
paraffin,  or  stearic  acid,  the  coating  of  the  composition  with  a  yamish  to  proteei  it 
from  the  action  of  moisture,  while,  at  the  same  time,  the  external  appeaianoe  cf 
the  matches  was  rendered  more  omamentaL  At  the  present  day  maichea  an  1 
product  of  an  indnstiy  which  cannot  possibly  be  much  more  improved  in  a  tcfhmwl 
point  of  yiew,  being  also  a  product  which,  as  regards  its  pzioe,  is  within,  tiie  leadi 
of  all. 

However  useful  phosphorus  lucifer  matches  may  be,  it  is  a  great  dxawlMu^  to  fhm 
utility  that  the  combustible  composition  is  a  poisonous  mixture,  while,  moreover,  tfas 
workpeople  engaged  in  that  department  of  the  lucifer-match  making  in  which  the 
phosphorus  is  handled  are  often  affected  by  a  peculiar  kind  of  caries  of  the  jaw- 
bones, the  real  cause  of  which  is  the  more  difficult  to  ascertain  as  the  woikpeofli 
engaged  in  the  manufacture  of  phosphorus  and  exposed  to  its  vapoors  to  socii  tt 
extent  as  to  render  their  breath  luminous  in  the  dark  are  not  aimilaily  alfefted. 
The  discovery  of  the  red  or  amorphous  phosphorus,  which  is  neither  poiBanoiis  aff 
very  inflammable,  affords  a  happy  substitute  for  the  ordinary  phosphoroSy  but  Iht 
former  is  by  no  means  generally  used  in  the  preparation  of  matches. 
MannfMgi^of^Luaifer      The  Operations  required  are  :— 

1.  The  preparing  of  the  splints  of  wood. 

2.  The  mixing  of  the  combustible  composition. 

3.  The  dipping,  drymg,  and  packing  of  the  matches. 

I.  The  Preparation  of  the  Wooden  Splints. — Generally  white  woods  are  used  for 
this  purpose,  such  as  white  fir,  pine  wood,  aspen,  more  rarely  fir  wood  (Fohrenhob). 
sometimes  beech  wood,  lime-tree  wood,  birch,  willow,  poplar  wood,  and  cedar.  Hie 
shape  of  the  splints  is  usually  square  in  section,  but  abroad  the  splints  are  sone- 
times  cylindrical.  The  square  spHnts  are  readily  made  by  hand,  simply  hj  aplittiiig 
up  a  block  of  wood  having  the  length  required  for  the  splint.  A  cutting  tool,  a  bigs 
knife,  similar  to  that  which  is  sometimes  used  by  chaff-cutters,  is  very  fireqnentl^ 
used  for  the  purpose  of  cutting  the  wooden  splints,  while  a  contrivance  irfmilT  Id 
that  in  use  for  propelHng  the  hay  or  straw  forward  is  also  employed,  being  so 
arranged  as  to  propel  the  wood  after  every  cutting  stroke  the  length  required  fior  a 
splint.  More  generally  the  operation  of  splitting  the  block  of  wood  parallel  to  ifti 
fibres  and  next  cutting  off  the  splints  to  the  required  length  is  effected  by  machineiy 
consisting  of  fixed  knives,  against  which  the  wood  is  moved  with  sufficient  foroe  to 
split  it  up  into  splints,  which  are  next  cut  to  the  required  length.  Instead  of 
splitting  the  wood  by  these  means,  the  splints  are  now  in  Germany  always  made  by 
a  kind  of  plane,  invented  by  S.  Homer,  of  Vienna,  by  which  the  wood  is  eoi 
up  into  circular  spHnts.  The  cutter  of  this  plane  differs  from  that  of  the  oxdinaiy 
carpenter's  plane,  by  possessing,  instead  of  the  cutting  edge,  a  slight  bend,  in  whidi 
three  to  five  holes  have  been  bored  in  such  a  manner  that  one  of  the  edges  of  these 
holes  is  sharpened;  in  practice  three  holes  are  preferred.  When  this  plane  is 
forced  against  a  lath  of  wood,  placed  edgeway,  the  cutting  tool  penetrates  into  the 
wood,  splitting  it  up  into  as  many  small  sticks  or  splints  as  the  cutter  contains  holee. 
When  a  number  of  thin  splints  have  been  cut  from  the  lath,  it  is  again  planed  tns 
with  an  ordinary  plane  and  then  the  operation  repeated.  The  dividing  of  the  thin  sticks 
into  splints  of  the  required  length  is  effected  by  a  tool  consisting  of  a  nanrow  troqgh 
about  6  centims.  wide  and  provided  with  a  slit  in  which  works  a  knife  fastened  to  a 


FH08PH0EV8.  549 

leTer.  A  clever  workman  can  prepare  400,000  to  450,000  splints  daily.  In  the 
south-west  of  Gennany  a  plane  for  catting  wooden  splints,  the  invention  of  Anthon, 
at  I>annstadt,  and  similar  in  action  and  construction  to  that  above  mentioned,  is  in 
general  use ;  bnt  throughout  an  extensive  portion  of  the  empire  the  manufiEtcture  of 
the  splints  has  become  a  separate  trade  often  carried  on  in  woods  and  forests,  the 
splints  being  sold  to  the  luoifBr-match  makers  in  bundles  ready  for  dipping. 

Tnstflad  of  malring  the  splints  by  hand  they  are  occasionally  made  by  a  machine, 

sooh  as  that  by  Pellitier,  at  Paris  (1820),  having  on  a  bench  a  plane  36  centime,  long 

by  9  wide,  made  to  move  backwards  and  forwards,  while  a  piece  of  wood  is  placed 

so  that  it  is  caught  by  the  fore-cutter,  which  consists  of  a  steel  knife  provided  with 

twenty-four  teeth  sharpened  like  little  knives,  the  second  cutter  removing  the  small 

laths  from  the  plank  of  wood.    Cochot's  machine  (1830)  consists  of  a  large  iron 

wheel  I  metre  in  diameter,  on  the  periphery  of  which  are  fixed  thirty  wooden  blocks 

lengthway  of  the  sise  of  the  splints.    When  the  wheel  is  turned  round  the  blocks  of 

wood  are  caught  by  the  knives  fastened  to  a  small  cylinder,  and  the  wood  is  split  up 

mto  splints,  which  are  removed  from  the  block  by  another  knife.    Jeunot's  machine, 

patented  in  1840  in  France,  is  of  a  similar  construction.    Neukrantz,  at  Berlin 

(1845),  contrived  a  tool  based  upon  the  principle  of  the  hand-plane,  the  wood  intended 

to  be  cut  being  moved  against  a  fixed  steel  cutter,  which  produced  sixteen  to  twenty 

splints  at  a  movement.  Krutzsch,  at  Wiinschendorf,  Saxony,  has  improved  upon  thiis 

plan  (1848)  by  perforating  a  steel  plate  with  about  400  holes  placed  as  near  together 

as  possible ;  the  edges  of  these  holes  having  been  shazpened,  a  block  of  wood  is  forced 

in  the  direction  of  its  fibres  against  the  plate  and  thus  divided  into  splints.    A  piece 

of  wood  3  centims.  in  thickness  and  width  by  i  metre  in  length  yields  400  lengths, 

each  of  which  can  be  cut  up  into  fifteen  splints;  6000  of  the  latter  are  made  in 

two  minutes.     Of  the  several  tools  and  machines  contrived  for  the  purpose  of 

cutting  splints — and  the  number  of  these  contrivances  is  very  large — ^we  quote  the 

following  of  German  origin.    The  machine  invented  by  0.  Leitherer,  at  Bamberg 

(1851),  consists  of  what  might  be  termed  a  kind  of  guillotine,  viz.,  a  box  at  the  bottom 

of  which  is  placed  the  wood  to  be  formed  into  splints,  the  fibre  of  the  wood  being 

TerticaL    In  front  of  this  box  is  placed  a  frame- work,  in  which  a  heavy  block, 

provided  with  four  cutters,  each  terminated  by  eight  to  ten  narrow  tubes  (somewhat 

similar  to  cork-borers),  can  be  made  to  move  rapidly,  so  as  to  give  forty-five  strokes 

a  minute,  the  wooden  block  intended  to  be  cut  into  splints  being  made  to  move  under 

the  cutting  tool  after  each  stroke.    Wrana's  machine  is  in  principle  the  same  as 

that  of  Neukrautz,  but  has  been  greatly  improved,  the  plane  not  being  fixed,  but 

supported  by  a  piece  of  wood.     Long's  machine,  again,  consists  of  a  series  of 

^^linders,  between  which  the  block  of  wood  is  placed,  while  knives  are  so  arranged 

as  to  cut  the  block  into  splints  while  the  wood  moves  on  by  the  motion  imparted  to 

the  cylinders. 

a.  The  Preparation  of  ths  Comimsiible  Compontion  is  carried  on  in  the  following 
maimer : — ^The  glue,  or  gum,  or  any  other  similar  substance,  is  first  dissolved  in  a 
small  quantity  of  water  to  the  consistency  of  a  thin  syrup,  with  which,  having  been 
heated  to  50°,  the  phosphorus  is  incorporated  by  gradually  adding  it  and  keeping  tlie 
mixture  stirred  so  as  to  form  an  emulsion,  to  which  are  next  added  the  other  ingre- 
dients after  having  been  pulverised.  In  order  to  obtain  a  good  composition,  it  is 
essential  that  there  should  be  neither  too  much  nor  too  httle  phosphorus,  for  an 
excess  of  phosphorus  will  not  only  tend  to  increase  unnecessarily  the  price  of  the 


550 


CHEMICAL  TECHNOLOGY. 


oomposition,  but  it  has  also  the  effect  of  rendering  it  unfit  for  igniting  the  Bolphiir 
and  stearin  wherewith  the  matches  are  tipped,  becanse  the  phosphoric  add  gene- 
rated  by  the  combustion  of  the  phosphorus  is  deposited  as  an  enamel-like  masi, 
which  prevents  farther  combustion.  It  appears  that  the  best  proportion  is  firam  ooe- 
tenth  to  one-twelfth  of  phosphorus. 

A  much  smaller  quantity  of  phosphorus  is  required  if  this  element  is  first  dissolTed 
in  sulphide  of  carbon  and  the  solution  added  to  the  other  constituents  of  the  ocimp»- 
sition ;  the  sulphide  of  carbon  while  rapidly  volatilising  leaves  the  phosphorus  in  a 
very  finely-divided  state.  As  phosphorus  is  very  readily  soluble  in  sulphide  <tf 
carbon,  and  as  the  latter  is  moderately  cheap,  the  method  has  the  advantage  that  the 
mixing  of  the  materials  can  take  place  without  the  application  of  heat.  It  is,  how- 
ever, evident  that  the  greatest  care  is  required  in  manipulating  such  a  liquid  as 
sulphide  of  carbon,  and  far  more  when  phosphorus  is  dissolved  therein.  G.  Poacher 
suggested  (i860)  the  use  of  sulphuret  of  phosphorus,  PaS,  instead  of  pure  phosphoriB 
in  the  composition  for  matches.  He  prepared  a  composition  containing  3*5  per  cent 
of  this  sulphuret,  and  obtained  excellent  matches. 

Among  the  metallic  oxides  which  are  employed  in  the  mixture,  preference  is  given 
either  to  a  mixture  of  peroxide  of  lead  and  nitrate  of  potash,  or  to  a  mixture  of  the 
former  with  nitrate  of  lead  obtained  by  treating  red-lead  with  a  small  quantity  of 
nitric  add  and  leaving  this  mixture  for  a  period  of  several  weeks  to  dry.  Glue,  gum, 
and  dextrine  are  used  as  excipients ;  the  first,  however,  is  objectionable  because  it 
carbonises  and  prevents  the  combustion.  Perhaps  a  dilute  collodion  solution  or  a 
mixture  of  sandarac  or  similar  resin,  with  benzole,  might  be  used  as  an  exdpieni 
instead  of  the  gum. 

The  mixtures  actually  used  in  the  trade  are  kept  secret,  but  the  following  redpes 
may  give  some  idea  of  the  composition : — 

I. 

Phosphorus       

Gum  Senegal 

Lamp-black      


Jtieu-ieaci    •••    ••.    ■••    •••    «•• 
Nitric  acid  at  4o''B.  (=  sp.  gr.  1*384) 


XL 


Phosphorus     ... 

value  •••      ...      ••• 

Peroxide  of  lead 
Nitrate  of  potash 


.    1*5  parte 

\ 

30    ». 

0*5    ,. 

A  mixture  of  nitrate  ef 

50    .. 
20    „  ' 

lead  and  of  peroxide  of 
lead,  technically  known 
,    as  oxidised  red-lead. 

8*0  parts 
21*0    „     . 

244    ., 

Dissolved  in  the  required 
quantity  of  sulphide  1/ 
carbon. 

240    „ 

m. 


Phosphorus       3*0  parts 

Gum  Senegal     3*0 

Peroxide  of  lead       20 

Fine  sand  and  smalt 2*0 

No  doubt  there  is  room  for  great  improvements  in  these  compodtiona. 
3.  Dipping  and  Drying  the  SpUnU.—ln  order  to  fix  the  sulphur  and  ^yffn^ntiVI'f 
xompodtion  to  one  end  of  the  splints,  it  is  dear  that  these  should  not  UmA  eadi 


n 


tf 


»> 


PHOSPHORUS. 


551 


other,  bat  be  M  uranged  as  to  leave  an  intermediate  apace.  A  oontriTance  is 
employed,  conuBtiiig  of  small  planks,  o'j  metre  long  hj  10  centime,  wide,  the  nu&ca 
being  provided  with  narrow  grooves  placed  close  together,  and  juat  large  eaough 
each  to  hold  a  single  splint.  Fig.  263.  The  splints  are  one  by  one  placed  in  tiie 
grooves,  an  operation  oenallj  performed  bj  girls.  One  plank  having  been  filled 
another  is  placed  on  the  top  of  it  The  surface  of  the  plank  on  one  side  is  provided 
with  a  piece  of  coarse  flannel,  while  the  other  side  is  grooved  for  holding  splints. 
Each  of  the  planks  has  at  the  end  a  ronnd  hole,  throagh  which  pass  iron 
rods.  Figs.  263  and  264,  in  the  top  of  which  a  screw  thread  is  cut,  so  that  as  soon  aa 
some  twenty  to  twentj-five  planks  have  been  filled  with  splints  and  placed  one  upon 
another,  they  are  &stened  so  as  to  fbrm  a  bamework,  A  clever  hand  can  fill  during 
ten  honrs  fifteen  to  twenty-five  of  these  frames,  each  oonttuning  2500  splints. 
Beoently  it  has  been  attempted  to  perfonn  this  work  by  machinery,  and  the  machine 
constmcted  by  0.  Walsh,  at  Paris  (1861),  enables  a  lad  to  frame  500,000  to  6oo/x)o 
apUnts  in  ten  honrs. 

The  sulphur  intended  for  dipping  the  splints  is  kept  in  a  molten  state  over  a  mode- 
rate fire  in  a  ahallow  reetangolar  trongh,  in  the  middle  of  which  a  stone  is  placed  as 


precisely  level  as  possible.  The  qnauti^  of  solphnr  is  so  regulated  that  It  eoren 
tlie  stone  to  a  depth  of  i  eentim.  In  the  operation  of  dipping,  the  ends  of  the 
splints  are  made  jnst  to  touch  Qie  stone  and  immediately  removed,  care  being  taken 
tocanse,  by  shaking  the  frame,  any  superflnons  snlphnr  to  flow  into  the  trough  again. 

Instead  of  snlphnr  the  better  kind  of  matches  are  impregnated  with  steaiine, 
stearic  acid,  or  paraffin.  The  splints  having  been  first  thoroughly  dried,  are  placed 
in  a  bath  of  molten  paraffin,  and  left  there  for  a  time  so  ss  to  allow  the  wood  to 
absorb  by  e^illarity. 

The  tipping  with  the  phoephorns  composition  is  performed  simUaily  to  the 
snlphnring  of  the  splints,  the  composition  being  placed  in  a  unifonn  layer  on  a  piece 
at  thick  grouikd  glass  or  on  a  well-polished  lithographic  stone  (Solenhofen  limo' 
stone). 

The  drying  of  the  matches  takes  place  in  a  room  heated  by  steam,  the  frames 
being  hung  on  ropea  ot  put  on  shelves.    The  position  of  the  frames  is  such  that  the 


55a  CHEMICAL  TECHNOLOGY. 

matches  ore  in  a  vertical  positioD,  and  the  composition  hangs  on  them  as  a  drop.  Hie 
composition  of  the  saloon  matches  is,  after  diying,  coated  with  oolonred  reBinoM 
solutions,  and  often  with  a  collodion  film. 

AntiPhonthor uat4fli««.  This  Variety  of  match  was  invented  in  1848,  by  Botiger, 
at  Frankfort,  and  was  prepared  industrially  by  Fiirth,  at  Schiittttihofeai ;  Limd- 
strom,  at  Jonkoping  (Sweden) ;  Coignet,  at  Paris  (under  the  name  of  AUwmetta 
hygUniquM  et  de  tureU  au  phaspkore  amorphe) ;  De  Villiers  and  Dalemagne,  Puis 
(under  the  name  of  AUumettei  androgynes) ;  also  by  Forster  and  Waia.  Theaa 
matches  are  of  two  kinds: — a.  Those  which  are  free  from  phosphoins,  the 
amorphous  phosphorus  being  incorporated  with  the  sand-paper,  p.  Those 
tree  from  phosphorus  both  in  the  match  and  on  the  sand-paper. 

To  the  matches  of  the  first  categoiy  belong: — i.  Matches,  the  com] 
of  which  is  free  from  phosphorus,  consisting  simply  of  a  pasty  mass,  the  main 
stituents  of  which  are  sulphuret  of  antimony  and  chlorate  of  potash.  2.  Ilia 
amorphous  phosphorus  mixed  with  some  very  fine  sand  or  other  substance  promotijig 
friction  is,  with  glue,  put  on  to  the  box  in  which  the  matches  are  contained ;  or,  as  is 
the  case  with  the  androgynes,  at  the  other  end  of  the  splint  The  friction  sniftce  tm 
the  boxes  consists  of  a  mixture  of  9  parts  of  amorphous  phosphorus,  7  parts  of  pul- 
verised pyrites,  3  parts  of  glass,  and  i  part  of  glue.  The  matches  ignite  readily  by 
friction  on  the  sur£ace  containing  this  composition,  but  do  not  ignite  when  rubbed  on 
any  other  rough  sur£ace.  These  so-called  safety  matches  are  largely  manufarinred 
at  Jonkoping,  under  the  Swedish  name  of  Sakerhets-Tsndstickor  (security  fiic 
matches).  Jettel  (1870)  uses  for  the  friction  surface  a  compound  consisting  of  equal 
parts  of  amorphous  phosphorus,  pyrites,  and  black  sulphuret  of  antimonj ;  iv 
coating  on  the  two  sides  of  1000  small  boxes,  each  containing  fiffy  matches^  abont 
80  grms.  of  this  mixture  are  required.  It  need  hardly  be  mentioned  that  ia 
England  safety  matches  are  largely  made  and  of  excellent  quality,  in  iact»  better  tfasa 
anywhere  else. 

B.  Forster  and  F.  Wara,  at  Vienna,  have  introduced  a  "  non-poisonous**  mateh. 
The  amorphous  phosphorus  is  mixed  up  with  the  combustible  oompositioii  ia 
the  usual  way,  so  that  these  matches  ignite  readily  by  being  rubbed  on  any  roa^ 
sur£BUse,  but  the  ignition  is  accompanied  by  noise,  owing  to  the  chlorate  ol  poisak 
contained  in  the  mass. 

As  regards  the  matches  belonging  to  the  second  category — ^viz.,  such  as  neiflier 
contain  phosphorus  nor  require  a  phosphorus-containing  surfiace,  we  may  give 
the  analysis  by  Wiederhold,  of  the  composition  of  those  made  by  Kummer  aai 
Giinther,  at  Konigswalde,  near  Annaberg,  in  Saxony : — 


Chlorate  of  potash     

... 

... 

.•  . 

8  parts 

Black  sulphuret  of  antimony  ... 

... 

... 

... 

8     „ 

Oxidised  red-lead      

•  a. 

... 

... 

8     ,. 

Gum  senega!      ... 

... 

... 

... 

I     .. 

Oxidised  red-lead  is  a  variable  mixture  of  peroxide  of  lead,  nitrate  of  lead,  ani 
undecomposed  red-lead.  Weiderhold,  at  Cassel,  suggested  (1861)  the  following 
ignition  mixture : — 

Chlorate  of  potash 7*8  parts. 

Hyposulphite  of  lead    2*6      „ 

Gum  arabic    ...    •«.    ... j'o      ,, 


ANIMAL  CHARCOAL.  55J 

This  is  the  best  anti-phosphorus  mixture.    Jettel,  sit  Gleiwitz,  gives  the  following 
mixtures  free  from  phosphorus : — 


•  •  •    •  •  • 


•••     •••     •••    ••• 


•• •    «•# 


a. 

&. 

c. 

d. 

40 

70 

3-00 

80 

10 

10 

— 

— 

04 

ao 

— 

05 

... 

~. 

... 

80 

Chlorate  of  potash 

Sulphur 

Bichromate  of  potash  ... 

Sulphuret  of  antimony 

Sulphur  auratum,  SbSj  (Stibium  \ 

Bulfuratum  aurantiacum).  [■        —  —  0*25  — 

(Antimouium  sulfuratum,  B.P.)    j 

Nitrate  of  lead    —  a*o  —  ^ 

'While  R  Peltzer  has  called  attention  to  the  applicability  of  copper-sodium  hypo* 
sulphite  for  the  preparation  of  a  phosphorus-free  ignition  mass,  Fleck*  has  also 
remarked  the  use  which  might  be  made  of  sodium  in  this  respect. 

Wax  or  tmu  MatehM.  Instead  of  the  phosphorus  composition  being  fixed  to  a  wooden 
splint  it  is  in  the  wax  matches  lallumettes  hoiufies)  attached  to  a  thin  taper  made  of  a 
iew  cotton  threads  (4  to  6),  immersed  in  a  molten  mixture  of  2  parts  of  stearine  and 
I  part  of  wax  or  paraffin.  The  tapers,  while  this  mixture  is  hot,  are  drawn  through 
a  hole  perforated  in  an  iron  plate,  the  opening  of  which  corresponds  to  the  desired 
thickness  of  the  taper.  The  taper  is  next  cut  by  means  of  machinery  into  suitable 
lengths ;  afterwards  the  phosphorus  composition  is  affixed  and  the  vestas  put  into 

1)0X68. 

Zulzer's  machine  for  cutting  the  tapers  and  for  making  them  into  matches  has  the 
following  arrangement.  The  wicks  having  been  rolled  on  a  drum  are  forced  between 
two  cylinders,  which  impart  the  fettty  composition,  and  next  the  tapers  are  carried  by 
the  machinery  across  grooves  in  planks  to  holes  in  a  movable  vertical  iron  plate, 
^which  is  connected  with  a  cutting  apparatus  intended  to  divide  the  tapers  into 
suitable  lengths.  As  the  cutters  are  placed  at  the  entrance  of  the  holes,  the  tapers 
after  having  been  separated  from  the  main  wicks  are  left  dangling  in  these  holes,  and 
by  a  mechanical  contrivance,  the  plate  containing  the  holes  is  lifted  sufficiently 
to  bring  another  row  of  holes  level  witli  the  wick-producing  apparatus.  When  a 
plate  has  been  thus  filled  with  tapers  it  is  removed,  another  put  in  its  place,  and  the 
ends  of  the  tapers  immediately  immersed  in  the  phosphorus  composition,  and  next 
placed  in  a  drying  room.  Marseilles  is  tlie  great  centre  of  the  wax  match  industry^ 
Tvhile  Austria  stands  next. 

Animal  Charcoal. 

Animal  chmieoaL  Animal  charcoal  is  the  residue  obtained  by  the  dry  distillation  of 
bones.  Owing  to  its  introduction  (1812)  by  Derosne,  and  afterwards  re-introduction 
with  improved  filtering  apparatus  by  Dumont  (1828),  into  the  sugar  refining 
industry,  animal  charcoal,  or  bone-blacI[,  has  become  one  of  the  most  important 
substances  of  chemical  technology.  When  bones  are  submitted  to  ignition  in  closed 
vessels  with  exclusion  of  air,  the  organic  matter  yields  a  tar  known  as  crude  Dippel'a 
oil,  and  carbonate  of  ammonia,  while  a  coal-black  residue  remains  exhibiting 
perfectly  the  organised  structure  of  the  bones. 

PmparatioBofBoiM-biack.  The  bones  are  either  boiled  with  water  or,  better, 
exhausted  with  sulphide  of  carbon  to  remove  the  fat,  which  being  obtained  in 

•  Jahresberioht  der  Chem.  Teohnologie  (Dr.  Wagner),  1868,  p.  220. 

2  B 


554 


CHEMICAL '  TECHNOLOGY. 


a  quantity  of  5  to  6  per  cent  of  the  weight  of  the  bones,  is  a  valuable  by-product  of 
this  branch  of  industry.    Tlie  carbonisation  of  tlie  bones  is  so  conducted  that  tiue 
volatile  products  are  eitlier  burnt  or  condensed.    In  the  latter  case  the  broken-iip 
bones  are  put  into  iron  retorts  similar  to  those  used  for  coal-gas  manufi&cture, 
and  tlie  volatile  products  are  collected  in  suitable  condensing  apparatus,  whik 
the  gas  after  having  been  purified  is  sometimes  led  into  a  gasholder  and  used 
for  illuminating  purposes,  or  when  not  purified  is  burnt  under  the  retorts.    Ac- 
cording, however,  to  the  experience  obtained  in  Germany,  bone-black  thus  made 
has  a  lower  decolourising  power  than  when  the  bones  are  ignited  in  iron  pots, 
the  volatile  products  being  burnt  at  the  same  time.    In  Germany,  therefore,  the  older 
plan  of  carbonisation  in  pots  is  usually  resorted  to.  In  England  and  Scotland,  and  alao 
in  Holland,  Belgium,  and  France,  retorts  are  generally  used  for  this  purpose.    Hie 
carbonisation  in  pots  is  carried  on  in  t)ie  following  manner: — Cast-iron  pots  are 
filled  with  broken-up  bones  and  placed  one  on  the  top  of  the  other,  the  edges  of  the 
tnouths  of  the  pots  being  luted  with  clay.    The  pots  are  placed  on  the  hearth  of  a 
kind  of  reverberatory  furnace.    After  awhile  the  vapours  which  are  forced  throng 
the  lute  become  ignited,  thereby  enveloping  tlie  pots  in  a  sheet  of  flame,  so  that  the 
carbonisation  goes  on  without  requiring  the  firing  of  tlie  furnace  to  be  kept  npw 
When  tlie  flame  subsides  tlie  carbonisation  is  complete.    The  yield  of  animal  char- 
coal amounts  by  this  method  of  procedure  to  55  to  60  per  cent,  the  carbonaoeooi 
matter  being,  however,  mixed  with  about  ten  tunes  its  weight  of  mineral  matter,  as 
may  be  inferred  from  the  following  results  of  analysis  of  a  dried  sample  of  bone- 
black,  which  in  100  parts  was  found  to  consist  of — Carbonaceous  matter,  10 ;  pho^faate 
of  lime,  84 ;  carbonate  of  lime,  6  parts.     By  exposure  to  air  bone-black  absorbs 
7  to  10  per  cent  of  moisture.    The  carbonised  bones  are  broken  up  and  granulated 
by  machinery,  the  formation  of  dust  having  to  be  avoided  as  much  as  possibk 
because  it  has  very  little  value. 

pvoperttM of  Bone-biiiek.  As  far  back  as  the  year  181 1,  Figuier  discovered  that  bone- 
black  possesses  tlie  property  of  withdrawing  organic  and  inorganic  substances — ^viz., 
lime  and  potash  from  solutions.  It  appears  that  this  property  is  due  to  soifue 
attraction  (capillary  action),  altliough  bone-black  is  also  capahle  of  decomposing 
chemical  compounds.  Owing  to  the  fact  that  bone-black  can  absorb  inorganic 
tnatter,  it  is  largely  used  for  the  purpose  of  withdrawing  lime  and  saline  matter  firam 
Saccharine  fluids  in  beet-root  sugar  works.  According  to  Antlion,  the  property  of 
bone-black  to  withdraw  lime  from  solutions  is  partly  due  to  the  fact  that  carbonic 
acid  is  condensed  in  the  pores  of  this  substance. 

By  treating  bone-black  wiih  hydrochloric  acid,  and  thus  dissolving  the  minetal 
matter  it  contains,  the  residue,  after  haWng  been  well  washed  with  water,  dried,  and 
re-ignited  in  a  closed  crucible,  has  lost  in  a  very  great  measure  its  property  of  with- 
drawing from  solutions  and  retaining  witliin  its  pores  inorganic  matter.  AMicii  add 
liquids  are  to  be  decolourised  by  bone-black,  it  should  always  be  employed  after  hitving 
been  treated  with  hydrochloric  acid.  Shoe-blacking  manufacturers  employ  in  their 
trade  a  large  quantity  of  bone-black. 

TMUng  Bonc-bia«k.  The  greater  the  decolourisiug  power  of  charcoal  the  better  ita 
quality,  though  it  appears  tliat  the  decolourising  power  is  not  proportionate  to  the 
power  of  withdrawing  lime  and  saline  matters  fr'om  solutions.  In  order  to  ascertain 
the  decolourising  power  of  any  sample  of  bone-black,  its  quality  in  this  reqwct 
is  compared  with  tliat  of  another  of  known  strength.    Payen  proposes  to  take  eqoal 


ANIMAL  CHARCOAL.  555 

balks  of  water  coloured  with  caramel,  to  treat  these  with  eqnal  weights  of  animal 
charcoal,  and  to  filter  these  mixtures ;  the  charcoal  which  yields  the  clearest  liquid 
being  tlie  best.  Bussy  obtained  the  following  results  by  the  estimation  of  the 
relative  decolourising  power  of  equal  quantities  by  weight  of  different  kinds  of 
charcoal : — 

Ordinary  bone-black        I'o 

Bone-black  treated  with  hydrochloric  acid ...  i-6 

Ditto,  ditto,  but  afterwards  ignited  with  carbonate  of  potash 20-0 

Blood  ignited  with  carbonate  of  potash       20'o 

Blood  ignited  with  carbonate  of  lime    20'0 

Glue  ignited  with  carbonate  of  potash         15-5 

Brimmeyr's  experiments  on  the  decolourising  properties  of  bone-black  led  to  the 
following  results : — i.  The  capability  of  absorption  of  this  substance  does  not  depend 
upon  the  mechanical  structure  of  the  bone-black,  but  upon  the  quantity  of  pure 
carbon  it  contains.  2.  The  quantities  of  matter  absorbed  by  bone-black  of  various 
kinds  are — ^when  reduced  to  pure  carbon — really  equivalent,  and  are  probably 
independent  of  the  varying  chemical  nature  of  the  soluble  absorbed  substance. 
3.  Bone-black  saturated  with  any  substance  retains  its  absorptive  power  for  other 
materials  of  a  difierent  chemical  nature.  4.  Bone-black  acts  the  quicker  and  better 
the  less  its  capillary  structure  has  been  interfered  with  either  by  mechanical  or 
chemical  means  (action  of  hydi'ocliloric  acidj.  Schultz*s  results  of  experiments 
agree  with  those  just  quoted.  The  specifically  lightest  bone-black  which  contains 
the  largest  amount  of  carbon  is  the  most  strongly  decolourising  material.  As 
regards  the  sugar  (especially  beet-root)  manufacture,  tlie  p<Twer  of  bone-black  to 
withdraw  lime  firom-  a  solution  comes  also  into  consideration ;  this  lime-absorbing 
capability  is  estimated  by  directly  testing  the  quantity  of  lime  whidi  a  given  sample 
of  charcoal  can  take  up. 

BcTiTiflMtton^nR^^iNiniiiK)  ^fjg,  having  served  the  purpose  of  decolourising  and 
absorbing  lime  for  some  time  in  the  process  of  sugar  refining,  the  bone-black 
becomes,  as  it  is  termed,  fotd  and  requires  to  be  revived,  for  which  purpose  it  ih 
either  first  thoroughly  washed  with  hot  water  or  sometimes  left  to  enter  into  a  state 
of  fermentation,  or  treated  with  steam,  and  finally  always  re-ignited.  The  more 
usual  plan  is  to  wash  the  bone-black,  while  still  in  the  filters,  with  hot  water,  so  as 
to  remove  all  soluble  matter,  the  material  being  next  re-ignited.  In  this  manner 
bone-black  ma}*  be  restored  for  use  twenty  to  twenty-five  times.  Tliis  mode  of 
reviving  labours  under  the  disadvantage  that  during  the  ignition  the  organic  matter 
(absorbed  impurities)  is  not  quite  destroyed,  and  by  choking  the  pores  of  the  bone- 
black  impairs  its  decolourisftg  power.  It  is  therefore  preferable  to  cause  the  bone- 
black  to  ferment,  to  treat  it  next  with  dilute  hydrochloric  acid,  wash  it  well, 
and  lastly  ignite  it  The  quantity  of  hydrochloric  acid  employed  for  this  purpose  in 
sugar-producing  works  is  very  large. 

8niMtitiitMforBon«-biaek.  Amoug  the  substancos  which  have  been  tried  as  substitutes 
for  tlie  use  of  bone-black,  carbonised  bituminous  shale  takes  the  first  place.  This 
material  (the  coke  of  the  Boghead  coal  is  an  excellent  example)  absorbs  colouring 
matter,  but  does  not  touch  the  lime.  Moreover  it  often  happens  that  the  coke 
is  rendered  unfit  for  tliis  use  by  the  presence  of  a  considerable  amount  of  mono- 
sulphurot  of  iron.    The  coke  of  sea- weed  is  perhaps  a  more  suitable  material. 


356  CHEMICAL  TECHNOLOGY. 

Milk. 
KUk.  This  fluid  is  secreted  by  glands  with  which  all  female  maTninalit  nt 
|>royided.  It  contains  all  the  organic  and  inorganic  sabstancea  required  by  te 
young  animal  as  food,  being  intended  to  feed  the  young  until  they  arc  suffickn^ 
developed  to  partake  of  other  nutriment.  The  main  constituents  of  milk  trc:— 
Sugar  (lactose),  caseine,  butter,  inorganic  salts,  such  as  chlorides  of  potaasiiiiB  tad 
sodium,  phosphate  of  lime,  and  finally  water.  The  average  percentage  compootia 
of  cow*8  milk  is  the  following : — 

Butter    3'^^^ 

Lactose  and  soluble  salts    ...  5' 129 

Caseine  and  insoluble  salts  ...  4'  107 

Water    • 87*476 


12*524  per  cent. 


lOO'OOO 

Milk  is  a  mixture  of  several  insoluble,  very  minutely  divided,  emulskmed  nb- 
gtances,  suspended  in  a  watery  liquid.  The  specific  gravity  of  milk  varies  btm 
i'030  to  1*045*  Under  the  microscope  it  becomes  evident  that  the  white  cdoiir  <tf 
milk  is  due  to  the  so-called  milk  globules — small  globular  bodies  of  a  yellow  ookor. 
with  a  more  deeply  coloured  circumference,  and  exhibiting  a  pearly  gloss.  It  w« 
formerly  believed  that  these  globules  consisted  of  an  exterior  envelope  filled  iviA 
butter,  but  the  recent  researches  of  Drs.  Von  Baumhauer  and  F.  Kns^p  btte 
proved  this  opinion  to  be  erroneous.  When  milk  is  left  standing  these  globules  n» 
to  the  surface  and  form  cream,  below  which  remains  a  blue  transparent  f^ 
containing  the  sugar  of  milk,  salts,  and  caseine,  the  latter  in  the  form  of  caseine-sodi 
When  milk  is  kept  for  some  time  a  portion  of  the  lactose  (sugar  of  xnilk)  is  deooa- 
posed  and  converted  into  lactic  acid  by  the  aid  of  the  caseine,  which  acts  ss  & 
ferment.  In  its  turn  the  lactic  acid  decomposes  the  caseine*  soda,  wherdiy  tbe 
caseine  is  set  free  and  separated  as  an  insoluble  substance ;  this  action  takes  place  ii 
the  coagulation  of  milk.  The  whole  of  the  lactose  or  sugar  of  milk  beooBA 
converted  into  lactic  acid  by  long  keeping. 

Lactic  acid  (C^l^O^)  is  also  formed  by  the  fermentation  of  starch,  oane  sa^^* 
and  glucose,  under  the  influence  of  caseine  and  a  ferment.  This  acid  is  ib^ 
with  iu  sauerkraut  (a  favourite  dish  of  the  Germans,  being  a  well-preserred 
mixture  of  white  and  savoy  cabbages  cut  into  shreds,  and  packed  in  csab 
along  with  salt,  coarse  pepper,  and  some  water),  and  in  other  pickles,  in  b^* 
and  iu  nearly  all  animal  liquids*  Lactic  acid  is  also  present  in  some  of  the 
fluids  of  the  tan-yard  tanks;  in  the  sour  water  of  starch  worics  where  stareK 
is  prepared  by  the  old  methods ;  in  the  bran  bath  «0f  dye  works ;  and  is  eoe* 
stantly  met  with  in  the  residual  liquids  of  com  spirit  distillation.  When  li^ 
add  is  heated  with  sulphuric  acid  and  peroxide  of  manganese,  aldehyde  is  icfOttd, 
which  is  used  in  the  preparation  of  aniline  green  and  of  hydrate  of  chloraL 

The  coagulation  of  fresh  milk  is  efiected  by  the  use  of  rennet,  which  is  pi*- 
pared  from  the  stomach  of  a  calf,  well  washed  and  stretched  out  in  a  wooden  frtfA 
then  dried  either  in  the  sun  or  near  a  fire.  The  substance  thus  prepared  was  for- 
merly soaked  in  vinegar,  but  experience  has  proved  thin  to  be  unnecessary.  ^V^ 
^required  a  small  piece  is  cut  off  and  steeped  in  warm  water,  and  the  liquid  added  to  (M 
milk  previously  heated  to  30**  to  35^    The  milk  is  hereby  coagulated,  even  inktfg* 


MILK.  557 

quantity,  in  about  z  hours ;  z  part  of  rennet  is  sufficient  for  the  purpose  of  coagula- 
ting z8oo  parts  of  milk.  The  mode  of  action  of  rennet  is  not  well  understood,  but  it 
does  not  consist,  as  was  formerly  beUeved,  in  the  instantaneous  conversion  of  a  por- 
tion of  the  lactose  present  in  milk  into  lactic  acid,  since  experiments  have  shown 
that  rennet  coagulates  milk  which  exhibits  an  alkaline  reaction. 

WIM7.  By  the  term  whey  is  understood  the  fluid  in  which  the  coagulated  caseins 
of  milk  floats  and  which  may  be  obtained  either  by  decantation  or  filtration.  The 
whey  of  sour  milk  contains  very  little  lactose  and  a  large  quantity  of  lactic  acid 
(sour  whey) ;  while  sweet  whey,  obtained  by  coagulating  milk  with  rennet  contains 
aU  the  lactose.  Sweet  whey  containing  3  to  4  per  mille  of  a  proteine  compound 
(termed  lacto-proteine  by  Millon  and  Commaille)  is  evaporated  to  some  extent 
in  Switzerland,  with  the  view -of  obtaining  the  sugar  of  milk  in  crystalline  state.  The 

iixtoM  wmiToi  MOk.  substance  thus  obtained  is  purified  by  re-crystallisation.  Lactose, 
CuHasOxx  +  HaO,  does  not  possess  a  very  sweet  taste  and  feels  sandy  in  the  mouth. 
It  is  soluble  in  6  parts  of  cold  and  2  parts  of  hot  water.  It  is  not  capable  of  alcoholic 
but  only  of  lactic  acid  fermentation.  By  the  action  of  dilute  acids  sugar  of  milk  is- 
«onverted  into  galactose,  a  kind  of  sugar  similar  to  grape  sugar,  and  is  then  capable 
of  alcoholic  fermentation.  Industrially  sugar  of  milk  is  sometimes  employed  for  the 
purpose  of  reducing  a  silver  solution  to  the  metallic  state,  as  in  the  case  of  looking- 
.l^ass  making.  100  parts  of  the  commercial  sugar  of  milk  from  Switzerland  (a),  and 
isovi  Giesmannsdorf  in  Silesia  (&j,  were  found  to  consist  (1868)  of: — 

a.  h. 

DftlMB     •••    •••    •••    ■••    ■•• 

Insoluble  matter 

Foreign  organic  substances... 
Sugar  of  milk 


•••    ••• 


003 

o*i6 

0*03 

005 

ri4 

1*29 

98-80 

98-50 

lOO'OO  lOO'OO 


"TUifirSirf  "^  By  boiling  milk  the  air  it  has  taken  up  is  eHminated  and 
thereby  the  conversion  of  the  caseine  into  a  ferment,  and  the  consequent  decomposi- 
tion of  the  sugar  of  mUk,  prevented.  Milk  may  very  readily  be  kept  fresh  by 
the  addition  of  small  quantities  of  carbonates  of  alkalies  or  borax.  The  coagulation 
of  milk  (not  its  becoming  sour)  may  be  prevented  by  the  addition  of  some  nitrate  of 
potash,  chloride  of  sodium,  or  other  alkaline  salts. 

TMiii«iiiik.  In  localities  where  milk  is  consumed  in  very  large  quantities — ^for 
instance,  in  large  cities  and  towns — ^it  is  sometimes  adulterated  by  the  addition  of 
rice-water,  bran-water,  gum-solution,  and  emulsion  of  sheep's  brain.  The  most 
eonmion  adulteration  of  milk  is  its  dilution  with  more  or  less  water.  Several 
methods  and  instruments  have  been  invented  for  the  purpose  of  testing  the  quantity 
of  caseine  and  butter  present  in  milk,  and  it  should  be  here  observed  that,  according 
to  Dr.  F.  Goppelroder's  excellent  researches  (1866),  it  has  been  found  that  the 
relative  proportion  of  the  quantity  of  these  substances  varies  in  milk  from  one  day 
to  another,  and  even  in  the  milk  drawn  at  mornings  and  afternoons.  According  to 
Jones's  plan  milk  is  poured  into  a  vertical  graduated  glass  tube ;  the  quality  of  the 
milk  varies  with  the  number  of  graduated  divisions  occupied  by  the  cream  separated 
from  the  milk.  It  is  evident  that  in  this  way  only  the  quantity  of  cream  contained 
in  the  sample  of  milk  under  examination  is  found,  and  nothing  learnt  about  the 
degree  of  dilution  of  the  milk  with  water,  which  somewhat  influences  the  rapidity 


558  CHEMICAL  TECHNOLOGY. 

of  the  separation  6f  the  cream.  Chevalier  and  Henry  employ  for  &e  testing  of 
milk  an  areometer,  the  degrees  of  wliich  are  ascertained  by  experiment  from  redh 
genaine  milk.  Other  methods  are  based  upon  the  nse  of  tincture  of  nnt-galls  or 
fiolation  of  sulphate  of  zinc  for  the  purpose  of  precipitating  easeine  and  butter  in  t 
sample  of  genuine  milk,  and  next  to  compare  the  quantity  of  these  reagents  neeci- 
sary  to  precipitate  in  an  equal  quantity  by  bulk  of  any  other  sample  of  milL 
Donn6*s  galactoscope  may  be  used  for  the  purpose  of  testing  the  purity  of  milk, 
more  especially  in  reference  to  its  adulteration  with  water,  tiie  instnuneot  being 
based  upon  the  greater  or  less  transparency  of  a  column  of  milk  of  a  certain  length 
which  admits  through  it  the  rays  from  tiie  flame  of  a  lighted  candle ;  the  mors 
transparent — that  is,  the  longer  the  column  of  milk — the  more  it  is  adulterated  widi 
water.  Briinner  tests  milk  in  tlie  following  manner  :-^To  20  grms.  of  the  milk  to  bo 
tested  are  added  10  grms.  of  charcoal  powder.  This  mixture  is  eyaporated  to 
dryness  at  a  temperature  of  70**  to  80^.  The  butter  is  then  extracted  by  me«ii8  of 
ether,  and  this  solution  evaporated  and  weighed.  I'nre  milk  yields  3*1  to  3*56  per 
cent  of  butter,  cream  from  10*6  to  11*06  per  cent.  C.  Heichelt  has  lately  tried  to 
apply  the  hallimetrical  method  (see  p.  422)  for  the  purpose  of  determining  the 
quantity  of  water  contained  in  milk. 

um«  of  Milk.  Milk  is  used  as  food  and  for  the  preparation  of  butter  and  cheese,  lor 
clarifying  wine  in  order  to  render  it  less  deep  coloured,  and,  if  turbid,  quite  clear. 
More  recentiy  milk  has  been  largely  sold  in  the  so-called  condensed  state,  by  which  is 
understood  millc  evaporated  in  vacuo  after  the  addition  of  sugar  to  the  consistency 
of  thick  honey.  This  mode  of  preserving  milk  was  first  employed  by  the  An^o- 
Swiss  Condensed  Milk  Company  at  Cham,  Canton  Zug.  Switzerland,  and  is  now 
carried  on  in  various  parts  of  the  Continent  and  in  the  United  States,  and  also  in 
England,  in  Surrey  and  Berkshire.  The  average  composition  of  the  condensed 
milk  is :— • 

VV  Hilicf  ..a        •.•       •«•        •.•        ...        ...        •••       .*•       22  44 

Solid  matter      ...    ••• 77*56 

ZOO'OO 

One-half  of  the  solid  matter  consists  of  the  sugar  which  has  been  added,  the  rest 
being  butter,  9  to  12  per  cent;  easeine  and  lacto-proteine,  12  to  13  per  cent ;  sugar 
of  milk,  ID  to  17  per  cent;  salts,  22  per  cent.  Condensed  milk  is  soluble  in  cold 
water,  and  yields  with  45  to  5  parts  of  water  a  liquid  similar  to  genuine,  but  of 
course  sweetened,  milk. 

Batter.  This  substsnce  is  prepared  as  follows: — ^Milk  of  good  quality  is  placed 
in  a  rather  cool  cellar  or  other  locality  for  the  purpose  of  causing  the  cream  to 
separate.  The  cream  is  poured  into  a  dean  stoneware  or  glass  vessel  kept  ibr  the 
purpose,  and  left  until  by  constant  stirring  it  has  become  thick  and  sour ;  it  is  then 
put  into  a  chum,  by  the  action  of  which  the  solid  fat  globules  are  separated  from  the 
thick  fluid  in  which  the  easeine  with  a  small  quantity  of  butter  remains  suspended. 
Butter  being  specifically  lighter  than  water  should,  it  might  be  thought,  sepaiats 
very  readily  from  a  liquid  wliich  contains  in  solution  various  substances  which  ars 
heavier;  but  the' fact  is,  that  easeine  renders  the  separation  of  butter  from  cream 
difficult  even  when  the  cream  is  sweet  and  not  Uiick ;  when,  on  the  other  hand,  milk 
coagulates  before  the  cream  is  separated,  the  butter  is  lost.  Two  methods  have  been 
•devised  for  the  purpose  of  obtaining  all  the  butter  contained  in  milk.    Gu^sander,  a 


MILK.  559 

Swedish  agricnltnrist,  has  proposed  that  the  separation  of  cream  should  be  rendered 
more  rapid,  and  always  completed  before  the  milk  becomes  sour,  while  Trommer 
prevents  tlie  souring  of  tlie  milk  by  the  addition  of  some  soda. 

The  chums  vary  very  much  in  constioiction  ;  tlie  most  simple,  which  is  that  most 
extensively  used,  consists  of  a  tall  somewhat  conical  wooden  vessel  covered  with  a 
wooden  lid,  through  a  round  opening  in  which  a  cylindrical  wooden  stem  passes. 
To  this  stem  is  fixed  a  wooden  perforated  disc,  which  is  moved  upwards  and  downwards 
by  a  similar  motion  imparted  to  tlie  stem.  The  butter  having  been  separated  from  the 
liquid  is  thorouglily  washed  and  kneaded  with  fresh  water,  and  next  more  or  less 
salted,  at  least  in  most  cases,  although  thorouglily  well-washed  butter  may  be  kept 
for  a  very  long  time  without  becoming  rancid.  The  liquid  from  which  the  butter  is 
separated  is  known  as  chum-milk  or  buttermilk ;  it  contains  o'24  per  cent  butter, 
3*82  per  cent  casein,  90*80  per  cent  water,  5*14  per  cent  sugar  of  milk  and  salts.  In 
the  water  lactic  acid  is  present.  18  parts  of  milk  yield  on  an  average  i  part  of 
batter,  which  in  fresh  condition  consists  of: — 


I. 

n. 

IIT. 

IV. 

Butter  fat        

944 

93 'o 

875 

785 

Caseine,  sugar  of  milk 
Extractive  matter 

03 

03 

I'D 

0-3 

TV  aiiei       •••     •••     •••     ••• 

53 

67 

"•5 

21'2 

Owing  to  tlie  presence  of  water  and  caseine,  butter  after  some  time  becomes  rancid. 
It  is  salted  in  order  to  prevent  this  rancidity  as  much  as  possible,  the  salt  being 
thoroughly  mixed  with  the  butter  fiy  kneading.  To  i  kilo,  of  butter  30  grms.  of  salt 
are  required.  According  to  Dr.  Wagner,  butter  in  England  is  salted  with  a  mixture 
of  4  parts  of  common  salt,  z  part  of  saltpetre,  and  i  part  of  sugar.  In  Scotland, 
France,  Southern  and  Western  Germany,  butter  is  not  salted  at  all,  and  therefore 
only  made  and  sold  in  comparatively  small  quantities  at  a  time.  Salt  butter  is 
termed  in  Scotland  pounded  butter. 

By  melting  butter  until  the  first  turbid  liquid  has  become  clear  and  oily,  water 
and  caseine  are  eliminated,  and  settling  to  the  bottom  of  the  vessel,  the  supernatant 
fat  may  be  put  into  another  vessel,  and  will,  after  cooling,  keep  sweet  without  salt 
for  any  length  of  time.  Butter  is  often  artificially  coloured  either  by  tlie  aid  of  annatto, 
turmeric,  or  infusion  of  calendula  flowers. 

oh«xnie«i  Nainra  of  Butter.  Butter  cousists  of  a  mixturo  of  ucutral  fats — glycerides — 
which  on  being  saponified  yield  several  fatty  acids,  among  which  the  non- volatile 
are : — Palmitinic  acid,  CieHsaOa,  and  butyroleic  acid  (CiaHjoOa).  The  volatile  are : — 
Butyric  acid*  {C^HsO^),  capronic  acid  (CfiHijOa),  caprylic  acid  (CsHjsOa),  caprinic 
acid  iCioH^oOa).  The  last  four  constitute  in  tlie  shape  of  glycerides  the  butyrin  or 
peculiar  fat  of  butter,  and  impart  to  tliat  substance  its  peculiar  odour  and  flavour. 

ohMM.  Cheese  is  prepared  from  caseine.  It  is  made  either  from  skimmed  or 
nnskimmed  milk.  In  the  former  case  a  lean,  dry  cheese  is  obtained;  in  the 
latter  a  fat  cheese,  such  as  Cheshire,  Cheddar,  American,  and  the  bulk  of 
Holland  cheeses.  Lean  cheese  is  made  in  Germany  by  pouring  the  skimmed 
and  already  sour  milk  upon  a  cloth,  through  the  pores  of  which  the  whey  passes, 

*  This  add  is  formed  not  only  by  the  saponification  of  butter,  but  is  also  met  with  in 
secreted  perspiration,  the  juices  of  the  stomach,  and  results  from  the  fermentation  and 
decay  of  sugar  (in  weak  solutions),  starch,  fibrine,  caseine,  &c. 


56o  CHEMICAL  TECHNOLOGY. 

while  the  caseine  remains  on  its  surface  as  a  pasty  naassi  which  is  pnt  hj  hand  nio 
the  cheese-moolds,  these  being  next  exposed  to  air. 

Fat  cheese  is  made  of  sweet  milk  just  drawn  from  the  cows,  the  ndlk  beng 
coagulated  by  rennet  after  having  been  heated  to  30°  to  40°.  The  gelatinous  mas 
thus  obtained  is  broken  up  and  pressed  by  hand,  and  the  whey  gradually  remoTsd 
by  the  aid  of  wooden  ladles.  The  caseine  having  been  freed  from  whey  is  next  vcH 
kneaded  with  some  common  salt  and  then  put  into  wooden  moulds  with  two  or  thne 
small  holes  at  tlie  bottom  for  the  purpose  of  allowing  the  whey  to  flow  off  when  the 
cheese  is  pressed.  The  newly  made  cheese  is  usually  every  alternate  day  dipped  ia 
warmed  whey,  next  wiped  dry,  put  into  the  mould  again,  and  pressed.  When  the 
crust  has  sufficiently  formed  and  the  cheese  become  so  hard  as  to  admit  of  being 
handled,  some  salt  is  rubbed  into  its  surface  and  it  is  then  placed  in  a  cool  well-aired 
room  upon  a  slielf  to  dry,  and  become  as  it  is  termed  ripe.  The  vesicular  app^iruiM 
of  some  kinds  of  cheese  (the  Gruy&re  cheese  exhibits  this  in  a  high  degree)  is  indi* 
rectly  due  to  the  incomplete  removal  of  the  whey,  the  sugar  contained  becoming 
during  the  ripening  converted  into  alcohol  and  carbonic  acid,  which  by  its 
expansion  while  escaping  produces  the  vesicular  texture.  Dutch  cheese  does  not 
exhibit  this  appearance  on  account  of  being  strongly  pressed  and  containing  much  aah, 
by  which  the  fermentation  of  the  sugar  of  milk  in  the  cheese  is  prevented.  The 
quality  of  the  cheese  depends  to  some  extent  upon  the  temperature  of  the  room  in 
which  it  ripens.  At  Allgau  i  cwt.  of  Swiss  cheese  of  the  first  quality  is  produced 
from  600  litres  of  milk,  while  for  the  second  quality  720  to  750  litres  of  milk  are 
taken  for  the  same  weight.  The  theory  of  cheese  formation  is  not  well  known,  bat 
it  appears  that  fermentation  plays  an  important  part  in  it.  W.  Hallier  has  proved 
that  freshly  made  cheese  is  filled  with  ferment  nuclei  (Kemhefe). 

Cheese  cannot  be  formed  without  this  ferment,  and  by  the  addition  of  soitaUe 
ferments  the  duration  of  the  cheese-ripening  process  and  the  quality  of  the  cheeae 
may  be  to  some  extent  regulated  at  will.  By  exposure  to  air  cheese  undergoet 
changes  which  may  be  best  observed  in  skimmed -milk  cheese.  When  new  or  young 
its  colour  is  white.  By  being  kept  so  that  it  does  not  dry,  it  turns  yellow  and  oQea 
becomes  transparent,  waxy,  and  then  exhibits  the  peculiar  odour  of  cheese.  Whea 
cheese  gets  very  old  it  becomes  a  soft  pasty  mass,  this  change  commencing  at  the 
outside  and  progressing  towards  the  interior.  The  waxiness  of  cheese  is  due  either 
to  an  evolution  of  ammonia  or  of  add.  Mild  cheese  usually  exhibits  an  acid  reaeliaa, 
while  strong  cheese  is  ammoniacal.  Chemically  speaking,  skimmed -milk  cheese  ia 
a  compound  of  caseine  with  ammonia  or  ammonia  bases,  amylamine  for  instance. 
The  so-called  dry  cheeses,  green  Swiss  cheese,  consists  of  an  infrision  of  herbs, 
Melilotus,  &c.,  with  volatile  fatty  acids,  valerianic,  capric,  caproic  acids,  and  indif- 
ferent substances,  leucin,  &o.  The  composition  of  sweet  milk  cheese  (a)  and  of  sour 
skim-milk  cheese  {b)  is  exliibited  by  the  following  table : — 

a.  d. 

Water    36*0  44*0 

Caseine 290  450 

Fatty  matter 305  60 

aSU         .*•     •••     ..«     ...     •••  4  3  5 

lOO'O  lOO'O 


MILKm  c5i 

TThe  results  of  the  researches  of  Payen  on  cheese  are  quoted  below  in  loo  parts  for 
tlie  following  kinds : — i.  Brie.  3.  Gamembert.  3.  Roqaefort.  4.  Bouble  cream 
oli.ee8e.  5.  Old  Neufchatel  cheese.  6.  New  Neufchatel  cheese.  7.  Cheshire. 
8.    Gruy^re.    9.  Ordinary  Dutch.     lo.  Parmesan  cheese. 


1. 


!•              a.             3.  4.  5. 

Water    45'20       51*90       34*50  9-50  34*50 

Nitrogenous  matter     ...     18-50        18*90        26-50  18*40  13*00 

Nitrogen        293          3-00          4'2i  2*92  3-31 

Fatty  matters       25*70        21*00        30*10  59*90  41*90 

Salts      ., 5«6o         4*70         5'oo  6*50  3*60 

Non-nitroffenous  organic  \ 

n«tter Ld loss           I    ' oo         450         3-90  5 70  700 

n. 

« 


6.              7.  8.              9.  zo. 

Water    36*60  35'90  4000  36*10  27*60 

Nitrogenous  matter     ...  8*00  2600  31*50  29*40  44*10 

Nitrogen        1*27          413  5*00          4*80  7*00 

Fatty  matters       40*70  2630  24*00  27*50  i6-oo 

Salts      050         4*20  3*oo         0*90  5*70 

Non-nitrogenous  organic|  .^            ^^                        ^.^^  ^.^ 
matter  and  loss            J 

The  varieties  mentioned  under  I.  exhibit  an  alkaline  reaction,  and  contain  with 
ammonia  ciyptogamic  plants,  or,  as  it  is  termed,  are  mouldy.  The  varieties  under 
II.,  so-called  boiled,  strongly  pressed  and  salted,  cheese,  exhibit  an  acid  reaction,  as 
also  does  freshly  prepared  caseine.  A  portion  of  the  fat  contained  in  the  cheese  is 
even  from  the  first  decomposed  into  glycerine  and  fatty  acids. 

Emmenthaler  (a)  and  Backstein  [b)  cheese  are  composed,  according  to  Lindt*a 
researches  (z868),  as  follows: — 


a. 

5. 

... 

... 

... 

Water 

37'4 

36*7 

45*2 

35-8 

Fatty  matters 

»•• 

... 

... 

30*6 

30*5 

28*2 

37*4 

Caseine 

••» 

... 

... 

28*5 

29*0 

23*2 

24*4 

Salts    

... 

... 

... 

3-5 

3-8 

3*4 

2*4 

loo-o  1000  1000  xoo*o 


The  results  of  E.  Homig's  recent  analyses  (1869)  of  different  kinds  of  cheese  are : — 


I.  a. 


6.  7.  8. 


Water      3866  5660  51*21  5764  3672  34'o8  5928  49*34 

Fatty  matters ...    20*14  17-05  9*16  20*31  33*69  2804  10*44  20*63 

Caseine    34*90  18*76  3360  18*51  25*67  23*28  2409  2426 

Salts 6*17  678  601  3-51  371  5*58  6-17  5*45 

Loss 0*13  0*81  0"O2  004  o*2i  0*02  002  032 

.■  I  .^_^.—  ■■  ■■  ■  ■■  ■  ■       ■ 

100*00  lOO'OO  100*00  100*00  100*00  100*00  lOO'OO  lOO'OO 

2  S 


562  CHEMICAL  TECHNOLOGY. 

I.  Dutch  cheese.  2  and  3.  Ramadonz  cheese,  made  in  Bavaria.  4.  Neoldttftd 
cheese.  5.  Gorgonzola  cheese.  6.  Bringen  or  Liptan  cheese,  from  tiie  Zypt 
Comitat,  Hungary.  7.  Schwarzenberg  cheese.  8.  Limburg  cheese,  made  in  &a 
environs  of  Dolhain-Limburg,  in  Belgium. 

Freshly  made  caseine  mixed  with  lime  is  used  as  a  kind  of  cement.  Caseiiie  is 
aJso  used  in  calico-printing  as  a  mordant ;  and  a  solution  of  caseine  in  bozax  is  vottk 
instead  of  glue.  In  the  seeds  of  the  leguminous  plants,  peas,  beans,  lentila^  Acl,  s 
met  with  a  nitrogenous  substance  which  is  soluble  in  water  and  precipitahle  there- 
from by  weak  acids;  this  material  is  veiy  similar  to  caseine,  and  aeooirdii]^  to 
M.  J.  Itiers's  accounts,  peas  and  beans  are  in  China  boiled  with  water  and  BtzaiDed, 
and  to  the  liquid  thus  obtained  some  solution  of  gypsum  is  added,  wheceliy  tibe 
vegetable  caseine  (legumine)  is  coagulated,  and  the  coagulum  thus  obtained  is 
treated  as  that  of  milk,  obtained  by  the  addition  of  rennet  to  the  latter.  The  maai 
80  obtained  gradually  becomes  like  cheese  in  all  respects. 

Meat. 

OttMnittiM      That  which  we  term  butchers*  meat  is  the  museolar  snhetaiioe  el 
slaughtered  animals,  together  with  more  or  less  fsX  and  bone,  so  thmt  flie 
exhibited  for  sale  contains  on  an  average  in  xoo  parts: — 

Muscular  tissue     ...     • 16 

Fat  and  cellular  tissue 3 

■PoimH       •••     ...      ...     ...     ...     •••     •••     •••  zo 

vuicoB      •••     •••     •••     ..■     *••     •••     •••     ••■  7r 

ICO 

Muscular  tissue  is  histologically  composed  of  a  variety  of  complex  tiasaes 
fluids,  the  basis  of  which  is  animal  fibre  or  fibrin,  an  organised  proteine  00m] 
The  muscular  fibre  held  together  by  cellular  tissue  forms  the  muscles,  &t 
deposited  in  the  cellular  tissue  and  in  cells  peculiarly  constructed  for  that  prnpoae. 
Blood-vessels,  lymph-vessels,  nerves,  and  other  organised  tissues  are  digperscd 
through  the  muscles  and  serve  a  variety  of  physiological  purposes.  The  miiseahr 
tissue  is  impregnated  with  a  proteine  fluid  in  which  aro  met  with  a  variety  of  otlur 
substances,  as  kreatinin,  hypoxanthin,  kreatin,  inosite  or  muscular  sugar,  lactic  add, 
inosinic  add,  extractive  matter,  and  inorganic  salts — among  these  ehkcide  ef 
potassium  and  phosphate  of  magnesia. 

coaatttiM&u  4rf  Meat      The  average  result  of  a  great  number  of  researches  recency 
on  the  large  scale  concerning  the  quantity  of  water  contained  in  the  meat  of 
and  half-  or  non-fattened  animals,  are  the  following: — 

Lamb.  Sheep.  Bullock.  FSg. 

In  the  non-fattened  meat     62           58  —  56 

„    „  half-£Eittened  meat     —           50  54  — - 

„    ,y  fully-fattened  meat   49           40  46  39 

,,     ,,  lai  mea*      ...     ••.     ...     ...     *"^            33  *""  ^"^ 

It  hence  appears  that  with  an  increase  of  fat  the  quantity  of  water  present  in  meat 
decreases,  a  portion  being  replaced  by  £at.  Well  fed  and  fattened  meat  oontazna  for 
equal  weights  about  40  per  cent  more  dry  animal  matter  than  non-fiatiened  meal* 
while  in  highly  fattened  meat  it  may  amount  to  60  per  cent 


MEAT. 


563 


The  difference  in  nutritive  Tolne  of  the  meat  of  well-fattened  bullocks  as  compared 

ivith  that  of  non-fieittened  is  exhibited  in  the  following  percentage  results  obtained  by 

Hreonlin: — 

Fattened.  Non-fattened. 


Water 
Ash 
Fat... 
Masde  ••• 


•••    ...    ...    ... 


...    ...    •*•    ... 


.••    ••• 


•.•     .■• 


•*.    ••• 


...    ••• 


•••     ... 


...    ••. 


38-97 

5968 

1*51 

1.44 

«3'87 

807 

3665 

3081 

lOO'OO 


1000  grms.  contain  :<— 

MoBonlar 
Meat. 

Meat  from  fieittened  bullocks 356 

Meat  from  non-fattened  bullocks...    308 


Fat. 
239 

81 


Difference 


+48        +158 


100*00 

Ash.       Water. 
15  390 

H  597 

+1        —207 


Consequently  the  meat  of  fattened  bullocks  contains  in  1000  parts  207  more  of 
solid  nutritive  matter  than  the  meat  of  the  same  in  unfattened  condition. 

Tb«  ooouaff  of  M«^  Meat  is  either  roasted  or  boiled.  By  boiling,  meat  is  very  essentially 
altered  in  composition  according  to  the  time  it  is  boiled  and  the  quantity  of  water 
used  to  boil  it  in.  The  fluid  in  which  meat  has  been  boiled  contains  soluble  alkaline 
phosphates,  salts  of  lactic  and  inosinic  acids,  phosphate  of  magnesia,  and  a  trace  of 
phosphate  of  lime.  In  order  to  be  of  the  highest  nutritive  value,  meat  should  retain 
all  its  soluble  constituents ;  hence  boiled  meat  Ipses  much  in  nutritive  power.  The 
albumen  contained  in  meat  is  lost  by  boiling  according  to  the  usual  plan.  Meat 
intended  to  be  boiled  should  be  immersed  in  boiling  water  to  which  some  salt  has 
heen  added,  the  meat  being  put  in  while  the  water  boils  violentiy,  whereby  so  great 
a  heat  is  at  once  imparted  to  the  outer  portions  of  the  meat  as  to  coagulate  the 
alhumen,  which  then  acts  as  an  impermeable  layer,  retaining  the  juices  in  the  meat, 
liiebig's  directions  for  making  good  broth  are  the  following: — ^Lean  meat  is  minced, 
mixed  with  distilled  water,  to  which  a  few  drops  of  hydrochloric  acid  and  commo|i 
salt  are  added.  After  having  been  digested  in  the  cold  for  about  an  hour,  the  liquid 
is  strained  through  a  sieve,  and  upon  the  residue  some  distilled  water  is  again 
poured  so  as  to  extract  all  soluble  matter.  In  this  way  an  excellent  and  highly 
natritive  cold  solution  of  extract  of  meal  is  obtained ;  this  may  be  drunk  without 
being  heated,  and  contains  albumen  in  solution,  which  is  coagulated  by  heating. 
100  parts  of  beef  yield  an  extract  containing  3*95  parts  of  albumen  and  3*05  parts  of 
other  constituents  of  meat  not  coagulable  by  heat.  Chevreul  obtained  from  500  grms. 
of  beef  containing  77  per  cent  water,  27*25  grms.  of  extract,  in  whioh.were  325  grms. 
fat ;  deducting  these  there  remain  4*8  per  cent  extract.  The  bulk  of  this  fluid  extract 
was  1*25  Htre,  the  weight  X013  grms.,  and  it  contained: — 


...     .•■    •*•     .•■ 


Water 

n*r*«,^;^  ^.f^.^*  /  Soluble  in  alcohol    ... 
Orgamc  matter  \j^i^^^^  ^  ^^^ol 

Alkaline  salts  ... 
Earthy  phosphates... 


..•     ... 


••a  •«. 


•••  ...  ...  ... 


991*30 

9'44 

3*12 

867 
0*46 


1013*09 


564  CHEMICAL  TECHNOLOGY. 

Broth  made  from  beef  contains  only  3  parts  of  meat  substance  inclnaTe  of  gbt 

and  fat. 
Under  the  best  conditions,  i  kilo,  of  beef  yields : — 

soluble  in  cold  water       ...    6o{afi,^SS     Z     Z       Ts 

Insoluble  in  cold  water    ••-rofg^^SSr^'^'r*"..     Z     x4^ 

J.  ail   •••  •••  •••  •••  •••  zo 

w  aiier  ••■  •■•  •••  •••  •••  /  3^ 

The  Boiling  of  Moat.  We  have  already  stated  that  the  meat  intended  to  be  InbM 
should  be  immersed  in  boiling  water  and  the  fluid  kept  boiling  for  a  few  minutes,  so 
much  cold  water  being  next  added  as  will  reduce  the  temperature  of  the  lipoid  to 
70**  or  74^  At  that  heat  the  liquid  should  be  kept  for  some  hours  to  produce  a  Teiy 
savoury,  sweet,  succulent  piece  of  boiled  meat.  If,  however,  it  is  desired  to  make  a 
strong  broth,  lean  meat  is  first  minced,  next  well  exhausted  with  cold  water,  and  tbem 
slowly  heated — ^best  on  a  water-bath — and  just  allowed  to  come  to  the  boil  over  a  slow 
fire.  The  liquid  is  strained  from  the  solid  meat,  and  the  latter  put  into  a  clean  dolh  and 
well  pressed.  The  residue  is  fit  only  for  the  making  of  manure.  The  broth  may  be 
coloured  with  caramel  if  desired.  Broth  so  made  contains  all  the  solnble  oornsti- 
tuents  of  meat,  and  exhibits  an  acid  reaction  owing  to  the  free  lactic  and  inoome 
acids.  Broth  does  not  owe  its  good  properties  to  the  gelatine  it  contains,  this 
substance  being  present  in  very  small  quantities,  while  the  so-called  bomUm^ 
tablettes  obtained  from  bones  are  altogether  unfit  for  food.  These  tablettes  sboiild 
not  be  confused  with  solid  meat-extract  cakes  of  Russian  make,  which 
according  to  Beichardt  (1869) : — 

Water  driven  off  at  100°    15' 13  per  cent. 

^\iBU  ...  ...  ...  ...  .a.  •••  ...  ...  ..•  4  73        »  ff 

f  ftb  ...       ...        ...       ...       ...       ••.       ...       •..       ...  O  2Z      y,         ff 

XNicrogen       ...     ...     ...     ...     ...     ...     ...     ...     10  S7    *>      t? 

Substance  soluble  in  alcohol  at  80 per  cent    ...    38*09    „    „ 

When  broth  is  boiled  for  a  long  time  it  becomes  deep  coloured  and 

the  very  agreeable  flavour  of  roast  meat.    Evaporated  upon  a  water-bath  it  yields  a 

pasty  deep  brown-coloured  mass,  18' 27  grms.  of  which  yield,  with  i  lb.  of  hot  water 

and  the  addition  of  some  salt,  a  very  strong  and  excellent  soup.    32  lbs.  of  bones 

with  the  adhering  scraps  of  lean  meat  yield  i  lb.  of  this  extract.    Extract  of  meat  as 

generally  met  with  is  now  made  in  South  America  by  several  firms,  viz.,  at  Fraj- 

Bentos,  Uruguay,  Gualeguaychu  (Entre  Bios),  i  Idlo.  of  this  extract  contains  all  the 

soluble  portion  of  34  kilos,  of  meat  without  bones,  or  45  kilos,  of  average  botchen* 

meat.    Australian  extract  of  beef  (the  American  extract  is  of  mutton  and  beef  mixed, 

manu£EUstured  by  B.  Tooth)  is  largely  imported  into  Europe.    The  chief  test  for  the 

purity  of  the  extract  of  meat  is  its  solubility  in  alcohol  at  80  per  cent,  next  lbs 

quantity  of  moisture  it  contains,  and  the  absence  of  albumen  and  fat.    60  per  caA  of 

the  extract  at  least  should  be  soluble  in  alcohol.     The  quantity  of  water  amounts  to 

about  16  per  cent,  the  nitrogen  to  zo  per  cent,  and  the  ash  to  18  to  22  per  ceni, 

consisting  essentially  of  phosphate  of  lime  and  magnesia,  chlorides  of  the  aDcaliee, 

among  wliich  potassium  chloride  predominates. 

prGserraUon  of  Meat.      Amoug  the  many  methods  employed  for  the  preservation  of  meat, 
that  by  complete  exclusion  of  air  ranks  foremost.    Appert*8  plan  of  packing  meat  in 


MEAT.  565 

tin  canisters,  firom  which  the  air  is  completely  exhausted,  is  generally  the  follow- 
ing:— The  meat,  or  very  concentrated  soups,  game,  &c.,  is  put  into  tin  canisters, 
vhich  are  thoroughly  filled.  A  Ud  is  then  soldered  on,  in  which  a  small  hole  is  made 
lor  the  purpose  of  entirely  filling  any  interstices  with  gravy.  This  having  heen 
done,  the  small  hole  is  soldered  over,  after  which  the  canisters  are  placed  in  a 
cauldron  filled  with  brine  and  boiled  therein  for  a  half  to  four  hours,  accordiog  to 
the  size  of  the  canisters.  When  any  of  them  is  not  well  soldered,  there  wiQ 
issue  from  the  leakage  smaller  or  larger  vesicles  of  air  and  vapour,  and  where 
fluch  is  the  case  hot  solder  is  applied  to  the  spot.  By  this  boiling  the  albuminous 
flubstances  are  coagulated  and  converted  into  a  less-readily  putrescible  modification. 
The  oxygen  of  the  air  contained  in  the  canisters  is  partly  converted  into  carbonic 
add,  partly  deozonised,  and  thus  rendered  ineffective  for  the  production  of  putres- 
cence. After  having  been  submitted  to  the  action  of  boiling  heat  for  some  time,  the 
canisters  are  placed  in  a  room  heated  to  yf,  and  left  there  in  order  to  test  whether 
putre£EU!tion  can  set  in,  manifested  by  the  bulging  outward  of  the  top  cover,  which, 
if  the  operation  has  been  thoroughly  successful,  is  usually  somewhat  concave  in  con- 
sequence of  a  vacuum  having  been  formed  inside  the  tin.  After  having  been  thus 
tested  for  several  days,  the  canisters  may  be  considered  sound,  and  will  keep  for  an 
indefinite  period.  Dr.  Redwood's  method  of  preserving  meat  imder  a  layer  of 
paraffin,  and  Shaler's  plan  of  preserving  meat  in  dry  carbonic  acid  gas  at  o^  are  in 
principle  the  same  as  Appert's  method. 

^mSJiSSd  rf  iRSii'  Meat  may  be  preserved  by  drying  it  or  salting  it,  both  methods 
being  based  upon  the  withdrawing  of  the  water.  Although  drying  is  the  best 
method  of  preserving  meat,  it  is  an  operation  attended  with  very  great  diffi- 
culty. The  natives  of  North  and  South  America  cure  meat  by  cutting  it  into 
thin  strips,  removing  the  fat,  and  rubbing  Indian-corn  meal  on  the  surfEuse.  Thus 
prepared,  the  meat  is  exposed  to  the  heat  of  the  sun  and  dries  rapidly,  forming  a 
flexible  non-putrescent  mass,  which  in  North  America  is  termed  Pemmikan^  in 
South  America  Tassqjo,  and  in  South  AMcar  BUtongue.  100  parts  of  beef,  which  is, 
after  drying,  rolled  up  so  as  to  form  a  compact  mass,  yield  26  parts  of  tassajo.  The 
drying  of  meat  is  in  Europe  never  effected  on  a  large  scale,  partly  on  accoimt  of  the 
low  temperature,  partly  on  account  of  the  necessity  of  cutting  the  meat  into  piecesi 
rendering  it  in  many  instances  unfit  for  culinaiy  purposes. 

Many  preparations  of  flour  and  meat  extract  have  been  introduced  at  different 
times  imder  the  name  of  meat-biscuit,  first  made  in  1850  by  Gail  Bordon,  at 
Galveston,  in  Texas,  U.S.,  and  greatly  improved  upon  by  G.  Thiel,  at  Darmstadt. 
The  latter  minces  fresh  lean  meat,  next  exhausts  it  with  water,  and  uses  the  liquid 
obtained  for  mixing  with  the  flour  instead  of  water.  The  large  biscuit  manufacturing 
firms  in  England,  especially  Huntley  and  Palmer  at  Reading,  prepare  patent  meat- 
biscuits  or  wafers,  made  with  Liebig*s  extract  of  meat  and  HassaU*s  flour  of  meat. 
On  the  Gontinent,  E.  Jacobsen,  at  Berlin,  prepares  a  similar  biscuit,  more  especially 
with  the  view  of  preparing  soup.  To  the  mixtures  of  animal  and  vegetable  matter 
prepared  so  as  to  be  suitable  for  keeping  for  a  length  of  time  belong  the  pea- 
sausages,  first  made  by  Gnineberg  in  Berlin,  and  largely  used  during  the  late  war 
as  an  excellent  food  for  the  German  armies. 

satttogMMit.  This  method  of  preserving  meat,  based  upon  the  principle  of  with- 
drawing water,  has  been  used  from  time  immemorial.  The  salt,  while  penetrating 
into  the  meat  and  thereby  hardening  it,  displaces  the  water  and  aids  the  preservation 


566  CHEMICAL  TECENOLOOY. 

of  the  sabstoEioe.  The  freshly-slaiightered  meat  is  first  nibbed  with  ooaxse  siH,  soi 
then  left  in  a  cask  with  salt  lor  some  days.  It  is  next  pressed  and  pat  into  anodier 
cask,  the  wood  of  which  has  been  previously  soaked  with  brine.  Some  salt  is  tiiea 
added,  and  lastly  the  brine,  which  had  been  obtained  by  pressing  the  meat,  is 
poured  over  it,  and  the  lid  of  the  cask  put  on.  Frequently  some  nitrate  of  potash 
and  sugar  are  added,  as  well  on  account  of  the  antiseptic  property  of  these  snbstBDOs 
as  for  imparting  a  bright  red  colour  to  the  meat. 

Salt,  however,  not  only  withdraws  water  from  the  meat,  but  also,  as  has  been  proved 
by  Dr.  Liebig's  researches,  some  of  the  very  best  and  essential  portion  of  the  juices  of 
the  meat,  including  albumen,  lactic  and  phosphoric  acids,  magnesia^  potash,  krealia, 
and  kreatinin.  Hence  it  is  clear,  that  unless  these  substances  are  in  some  way  or  other 
added  to  the  salted  meat,  its  use  as  food  for  a  lengthened  period  cannot  £ul  to  beeome 
iigurious  to  the  system,  and  it  is  surmised  that  scurvy  is  due  to  this  condition  of  salt 
meat  Liebig  has  suggested  that  meat,  instead  of  being  treated  with  dry  salt,  shovU 
be  salted  with  a  strong  brine  made  up  of  common  salt,  Chili  saltpetre,  chloride  of 
potassium,  and  extract  of  meat.  The  salt  to  be  used  for  making  this  brine  should  be 
previously  purified  by  the  application  of  a  solution  of  phosphate  of  soda,  whoeby 
lime  and  magnesia  are  precipitated.  Cirio*s  method  of  meat  preservation,  which  was 
exhibited  in  1867  at  the  Paris  Exhibition,  consists  in  placing  the  meat  in  vacuo  and 
then  forcing  brine  into  it.  By  this  process  the  nutritive  value  of  meat  is  much 
impaired  owing  to  the  loss  of  the  juices. 

soMkiiic  or  ouiiic  Km*.  The  rationale  of  this  process  and  the  preservative  actionL  of  the 
smoke  have  not  been  scientifically  elucidated.  In  the  first  place  the  heat  of  the  smoke 
dries  the  meat,  while,  further,  smoke  contains  a  creosote,  which,  according  to  the 
more  recent  researches  of  Hlasiwetz,  Gorup-Besanez,  Marasse.  and  others,  essentiany 
consists  of  a  mixture  of  C7H80a,  CsHioOa,  and  CgHzsO^.  This  creosote  poaseaees 
the  property  of  coagulating  the  albuminous  substances  of  meat,  and  once  coagulated 
and  thereby  rendered  insoluble  these  substances  are  not  capable  of  decay,  or  only 
BO  after  a  veiy  great  lapse  of  time.*  Smol^e,  moreover,  contains  some  pyroligneoua  add 
and  other  creosote-like  substances  (oxyphenic  aud  carbolic  acidsj,  which  undoubtedly 
play  some  part  in  the  preservative  action. 

Vinegar  is  an  excell^t  preservative  of  meat,  especially  in  hot  summer  weather. 
Abroad  meat  is  frequently  put  into  a  dean  linen  cloth  which  is  thoroughly  soaked 
with  vinegar,  some  salt  also  being  sprinkled  on  the  doth.  Meat  kept  for  a  few  days 
in  this  manner  is  veiy  tender  and  readily  digested.  It  is  very  probable  that  vinegar 
might  be  advantageously  employed  on  the  large  scale  for  the  preservation  of  meat 
together  with  complete  exclusion  of  air.  In  order  to  prevent  the  vinegar  extracting 
the  juices  of  the  meat,  the  latter  should  be  exposed  to  the  action  of  the  vq^urs  of 
strong  vinegar. 

Lamy  more  recently,  and  Braconnot,  Robert,  and  De  Dombasle,  nearly  half  a  ooi- 
tury  ago,  proposed  to  preserve  meat  by  the  aid  of  sulphurous  add  gas,  pieces  of  meat 
weighing  some  2  to  3  kilos,  being  exposed  to  the  action  of  this  gas  for  ten  minutes, 
while  larger  pieces  of  10  kilos,  and  more,  are  exposed  to  the  action  of  the  gas  for  20  to 

25  minutes.  After  having  been  exposed  to  fresh  air  for  some  minutes  for  the  purpose 
of  getting  rid  of  the  excess  of  the  gas,  the  meat  is  coated  with  a  brush  with  a  solu- 
tion of  albumen  in  a  decoction  of  marsh-mallow  root,  to  which  some  molasses  have 
been  added.  Veiy  recently  meat  has  been  preserved  by  first  diying  it  in  a  cnrzent  of 
hot  air  and  next  coating  it  with  a  film  of  caoutchouc  or  gutta-percha,  by  immersing 


MEAT,  567 

the  meat  in  a  eolation  of  these  Bobstanoes  in  ohlorofonn  or  snlplude  of  carbon.  It  is 
▼ery  generally  known  that  a  temperatore  below  freezing-point  is  a  most  perfect  pro- 
tection against  decay  of  animal  matter ;  hence  ice  is  largely  used  for  the  preservation 
of  fish  in  summer  time.  Meat  as  well  as  game  and  poultry  are  best  preserved  in  hot 
breather  in  ice  pits.  In  no  country  of  the  world  is  so  much  use  made  of  this  mode 
of  preserving  meat  and  vegetables  as  in  Russia,  where  the  very  severe  winter  is 
tamed  to  good  account  by  the  preserving  of  all  kinds  of  animal  food ;  in  fact,  oxen, 
sheep,  hogs,  deer,  and  all  kinds  of  game  and  poultry  are  brought  to  market  in  a  frozen 
condition,  and  may  be  kept  so  for  any  length  of  time  without  impairing  the  goodness 
or  taste  after  cooking.  At  St.  Petersburg  large  stores  of  frozen  animal  food  and 
game  brought  from  distances  of  hundred  of  miles  are  kept  throughout  the  winter.  At 
the  Domburg,  near  Hadamar  (Province  of  Nassau,  Prussia),  a  natural  permanent 
ice  store  exists  wherein  perishable  food  is  kept  stored  in  large  quantity.  The 
artificial  production  of  ice  by  means  of  Carry's  machine  is  employed  in  New  South 
Wales  for  the  freezing  of  meat,  which  is  next  packed  in  ice  ready  for  transport 


(568) 


DIVISION  VI. 
dteino  and  calico  printing. 

On  Dtsino  and  Printing  in  General. 

Dydng  and  PiinUng  in  oenenL  The  object  of  the  art  of  dyeing  is  to  impart  to  textile 
fibres,  chiefly  in  the  shape  of  woven  tissue,  but  in  many  instances  as  jam,  aone 
colour  or  other.  Dyeing  is  distinguished  from  painting  by  the  fact  that  the 
pigments  are  fixed  to  the  animal  and  vegetable  textile  fibres  according  to  certaia 
physico-chemical  principles,  and  are  not,  as  in  painting,  simply  fixed  by  adhesioo  to 
the  surface,  although  painters  and  artists  occasionally  use  the  same  pigmenta 
Printing  consists  in  the  duplication  of  coloured  patterns,  and  is  a  very  important  pait 
of  dyeing. 

Dy«a.  The  materials  employed  for  the  production  of  colours,  the  dyes  and  {dgmenli^ 
are  partly  of  mineral,  animal,  and  vegetable  origin,  partly  artificially  obtained — that 
is,  the  products  of  modem  chemistry.  Among  the  very  large  number  of  inotgams 
pigments  few  only  are  as  such  fit  for  use,  and  if  employed  at  all  it  is  by  an  indirect  or 
circuitous  process,  JJiat  is,  they  are  produced  upon  the  woven  fabric  itself.  F(V 
instance,  chromate  of  lead  is  obtained  by  first  impregnating  the  woven  tissue  witii 
acetate  of  lead,  after  which  the  fabric  is  treated  with  a  solution  of  bichrcmiale  or 
neutral  chromate  of  potash,  the  result  being  the  formation  of  a  solid  adhenng 
chromate  of  lead.  Among  many  other  inorganic  pign^ents  may  be  enumerated — 
Berlin  blue ;  hydrated  oxide  of  i^on,  for  drab,  nankeen,  or  rust  colour ;  bistre  coloiir, 
hydrated  oxide  of  manganese :  chrome-green,  oxide  of  chromium.  Among  the  djnee 
of  animal  origin  are — The  ancient  Tyiian  purple,  derived  from  a  mollusc,  a  natiTe  of 
the  Mediterranean,  now  not  used ;  kermes  (Coccus  ilicis) ;  cochineal  (Coccum  eacU)  ;  lac 
dye  (Coceu8  lacoa).  A  much  larger  number  of  dyes  are  obtained  from  the  vegeiaUe 
kingdom.  It  appears  from  recent  researches,  that  a  large  number  of  the  so-called 
vegetable  pigments  are  present  in  the  plants  themselves  in  a  colourless  condition, 
becoming  coloured  by  the  action  of  the  atmosphere.  It  is  impossible  to  mention  anj 
general  properties  of  the  vegetable  pigments,  because  excepting  the  £act  that  they  are 
all  coloured,  they  are  not  possessed  of  any  property  common  to  all.  Nearly  all  dyes 
fade  by  the  combined  action  of  sunlight  and  moist  air.  Chlorine  destroys  mo^ 
colours ;  while  many  dyes  are  bleached,  not  destroyed,  by  sulphurous  acid.  We  owe 
to  the  researches  of  modem  chemistry  a  class  of  pigments  which  surpass  in  beauty 
almost  all  the  native  dye  materials.  These  chemically  prepared  dye  materials  are 
chiefly  derived  from  coal-tar,  more  particularly  from  benzol,  toluol,  carbolic  acid« 
anthracen,  and  naphthalin.     The  pigments  derived  from  these   substanoea  are 


DYEING.  569 

eommonly  termed  aniline  or  coal-tar  colours,  faclisin,  magenta,  aniline  blue  and  violet, 
Alanchester  yellow,  aniline  orange,  picric  add,  aniline  brown,  coralline,  alizarine 
(eurtificially  prepared  from  anthracen),  magdala  red,  aniline  black,  and  aniline  green, 
^mong  the  chemically  prepared  colouring  matters  should  be  mentioned  those 
obtained  by  the  decomposition  of  the  alkaloids  (cinchonine,  quinine,  &c.),  chinoline 
l>lue,  quinine  green  (thalleiochine),  and  also  murexide,  a  product  of  the  iiecomposi- 
tion  of  uric  acid. 

i^ake  Pficnittnta.  The  so-callcd  lakcs  are  compounds  of  starch,  alumina,  oxide  of  tin,  oxide 
of  lead  with  sometimes  carbonate  of  lime,  baryta,  or  oxide  of  antimony,  with  the  colouring 
matter  of  madder,  cochineal,  woad,  logwood,  tar-colours  (viz.  coralline,  fuchsin,  aniline 
-violet),  but  as  yet  these  substances  are  not  prepared  in  definite  proportions.  By  paints 
^w^e  understand  substances  wliich  as  a  rule  are  insoluble  in  water  and  are  mixed  with 
either  weak  glue  solution,  being  then  termed  water-colours,  or  with  linseed  oil,  called 
oil-paints.  To  these  pigments  belong  white-lead,  red-lead,  ultramarine,  Berlin  blue, 
Trermillion,  chrome-yellow,  bone-black,  &c.  The  ordinary  water-colours  are  insoluble 
in  water,  being  finely  suspended  therein  by  the  aid  of  gum,  white  of  egg,  gum 
tragacauth,  &c.  The  pastel  pigments  used  for  drawing  are  made  up  of  various 
pigments,  mixed  with  pipe-day,  soap,  and  some  tragacanth  mucilage,  and  moulded 
into  cylindrical  sticks. 

ooionring  MatexiaiB.  Dyeing  mcaus  strictly  the  tinging  or  colouring  of  absorbent 
BTibstances  by  impregnating  them  with  solutions  of  colouring  matters.  It  is  thus 
opposed  to  painting,  which  consists  in  laying  a  colour  upon  the  surface  to  be 
coloured.  In  the  art  of  dyeing  some  colouring  matters  are  applied  by  immersing 
the  tissue  to  be  coloured  in  the  decoction  or  solution  of  the  pigment.  Some  sub- 
stances are  applied  to  the  surface  of  the  woven  fabric  by  the  intervention  of  what 
is  technically  termed  a  mordant,  which  is  in  the  case  now  under  consideration 
only  a  means  of  obtaining  adhesion,  as  when,  for  instance,  ultramarine  is  fixed  by 
the  aid  of  white  of  egg.  Sap-colours  are  substances  more  or  less  soluble  in  water, 
covering  very  slightly,  and  more  or  less  translucent,  as  sap-green,  gamboge,  carmine 
solution,  many  of  the  tar-colours,  &o. 

The  Coal'Tar  Colours. 

co«i-Ttf.  This  substance  is  very  largdy  obtained  as  a  by-product  of  the  dry  dis- 
tillation of  coal  for  the  purpose  of  gas  manufacture,  and  is  a  most  complex  mixture 
of  a  very  large  number  of  substances,  among  which  are  fluid  and  solid  hydro- 
carbons (benzol,  toluol,  cumol,  cymol,  anthracen,  naphthalin);  adds  (carbolic  or 
phenylic,  cresylic,  phloiylio,  rosolic) ;  bases  (aniline,  chinoline,  odorine,  picoUne, 
toloidine,  coridine,  &c.),  and  asphalte-forming  materials.  Leaving  the  small  quantity 
of  basic  substances  out  of  the  question,  100  parts  of  tar  consists  of  the  following 
substances : — 


Benzol 
Naphtha    ... 
Naphthalin 
Anthracen ... 
Carbolic  add 
Fitch  •••     ••• 


•••  •••  •••  ••• 

••■  ...  •••  ... 

.*•  •••  •••  •.• 

.*•  •••  •••  •.• 

...  •••  ••*  ••• 

•••  ••*  •.«  ••• 


••     ••• 


1*5 
35*o 

220 
I'O 

9'o 

ZOO'O 

2T 


S70 


CHEMICAL   TECHNOLOGY. 


By  fractional  distillation  of  tar  we  obtain,  on  the  one  band,  liglit  oils,  from  ^tiA 
benzol  and  its  homologues  are  separated ;  on  the  other  hand,  heavy  tar  oil,  idiiefa  i* 
used  for  making  carbolic  acid  ;  while,  lastly,  anthracen  is  separated  &om  the  pttdL 

ApproximaUvely,  the  following  table  shows  the  quantity  of  the  vaxioos  matoMla 
obtained  by  the  dry  distillation  of  coal : — 

loo  kiloB.  of  coal  yield  3'oo  kilos,  of  tar. 
iDO  kilos,  of  tar  yield    073  to  i  Idla.  of  trathraeen. 
3*00  kilos,  of  crude  benzoL 
1*50  kilos,  of  pure  benzol. 
3-00  kilos,  of  nitro-benzoL 
z'z;  kilos,  of  crude  aniline. 
3*37  kilos,  of  omde  aniline  red. 
I'tz  kilos,  of  pore  fochaiuT 

For  Qie  preparation  of  i  kilo,  of  pure  fuchsin  60  cwts.  of  coal  are  required. 
BnuoL  Chemically  speaking,  benzol  or  benzine  is  a  fluid  hydrocarbon,  6eHs,  dis- 
covered in  1825  by  Faraday  among  the  products  of  the  dry  distillation  of  oil.  in 
the  liqoid  resulting  from  the  strongly  compressed  oil  gas.  In  1833  Mitachcrlich 
obtained  this  body  by  distiUing  ben7oate  of  lime.  Leigb,  at  Manchester,  1S4X,  fint 
discovered  benzol  in  coal-tar ;  and  to  Mansfield's  researches  is  due  tb«  m^bo^ 
of  separating  benzol  from  tar  by  a  process  available  on  the  large  sole. 

The  benzol  as  met  with  in.  commerce  is  a  mixture  of  benzol  boiling  ftt  80*4*  iritb 
toluol,  C,Hg,  boiling  at  108° ;  xylol,  CgHgo.  boiling  at  130^ ;  cumol,  C^lljL  boiling  al  - 
iji" ;  and  cymol,  C,dH^.  boiling  at  175° ;  benzol  and  tolfkol,  however,  predominate. 
Abroad  benzol  is  sold  to  the  aniline  makers  at  a  certain  specified  perc«nta^ 
of  benzol,  CgHs;  for  iastance,  benzol  at  30  to  40  per  cent  contains  by  bulk  <■ 
weight,  sa  may  be  agreed  upon,  the  above  percentage  of  the  compoond  CeHt.  dM 
rest  being  60  to  70  per  cent  <f 
Fio-  365.  toluol  and  xylol,  forming  *  fhai. 

which  is  suitable  for  maJdng  aniline 
red,  while  for  aniline  Una  or  Uack  a 
fluid  at  90  per  cent  benzol,  CgHt.  it 
required.  The  boiling-point  of  tbe 
benzols  usually  employed  for  making 
the  so-called  tar-colooia  varies  from 
80°  to  I  zo",  while  the  specific  grKvi^ 
varies  fium  085  to  oSg. 

Benzol  is  prepared  from  li^t  lar 
oil  which  boils  below  150°.  tlw 
apparatus  invented  by  Manafield  for 
this  purpose  is  shown  in  Fig.  265. 
A  is  the  still  placed  on  a  f(uiiac«, 
b;  c  is  filled  with  cold  wator.  Aa 
soon  as  the  oil  in  the  still  begins  bo 
boil,  the  vapours  are  condensed  in  b  and  flow  back  into  a  ;  this  contjnnes  imtil 
the  water  in  o  has  been  heated  to  a  certain  temperature,  when  the  vapours  an 
condensed  in  the  cooler,  d,  the  liquid  flowing  at  n  into  the  carboy,  s.  As  soon  as  tha 
water  in  c  begins  to  boil,  all  the  substances  contained  in  the  tar-oil  and  vdstila 


bTEtsa. 


57' 


■it  too"  are  condensad  and  collected  in  b.  A  very  pnre  benzol  ia  prepared  with  this 
Rppaxatns.  B;  opening  the  tap  m,  the  hydrocarbons  which  boil  above  ioo°  can 
be  rectified.  The  stopcock,  i,  is  used  for  emptying  the  stiU.  In  the  benzol  works  the 
apparatus  exhibited  ia  Fig.  x66  is  used,    a  is  th«  still,  u  the  condenser,  c  a  water 

Fio.  a66. 


tank.  At  the  commencement  of  the  operation  the  water  in  c  is  heated  by  means  of 
the  steam-pipe  d.  which  communicHtes  wit])  the  steam  boiler.  The  tnbe  o  is  attached 
to  the  still;  i  is  a  contrivance  for  filling,  b  for  emptying  it.    The  condensed  water  is 


1 


57«  CHE^nCAL   TECHNOLOGY. 

carried  off  by  means  of  h.    By  freezing  benzol  and  pressing  the  solid  sxMmmm 
obtained  it  may  be  rendered  quite  pure.^ 

In  the  year  i860,  Dr.  E.  Kopp,  at  Turin,  showed  that  the  preparation  of  \jmd 
might  be  advantageously  effected  by  the  use  of  an  apparatus  similar  in  constmctiaa 
to  that  employed  in  spirit  distilleries.  Coupier  has  constructed  an  apparatus  upon  tkii 
principle,  which  is  shown  in  Fig.  267.  a  is  the  still ;  at  b  the  crade  benzol  b 
poured  in ;  c  is  a  steam -pipe  for  heating  the  still  and  its  contents.  The  Tapoeit 
evolved  from  the  boiUng  liquid  are  carried  into  the  column  n.  which  acts  as  a  dephk^ 
mator,  by  which  a  first  fractionation  is  effected.  The  volatile  vapours  which  are  aat 
condensed  in  m  are  carried  to  the  apparatus  n,  which  is  filled  with  a  solution  d 
chloride  of  calcium.  Tliis  apparatus  is  kept  at  a  uniform  temperature  determined  bf 
the  thermometer,  t^  and  maintained  by  tlie  steam-pipe  m. 

The  steam  conveyed  by  the  heating  pipe  escapes  by  p.    When  it  is  desired  to  pre- 
pare pure  benzol  the  chloride  of  calcium  solution  is  heated  to  So"*.   The  vapours  whidi 
are  conveyed  to  a  are  a  mixture  of  benzol,  toluol,  &c.    As  the  temperature  of  the 
receiver  a  does  not  exceed  80°,  the  vapours    of  toluol   aud  other  homologafas 
compounds,  as  xylol,  are  condensed  ;  while  the  vapours  still  uncondensed  are  cani^d 
to  the  receivers  h,  i,  and  k,  losing  or  depositing  there  the  last  traces  of  the  less 
volatile  hydrocarbons,  becoming  finally  condensed  in  l,  surrounded  with  oold  watn; 
and  trickling  down  into  the  carboy,  m.     The  fluid  condensed  in  o,  h,  i,  and  k«  flows 
back  into  the  column  n.    As  the  receiver  o  contains  the  heaviest  oils  these  are 
carried,  for  the  purpose  of  dephlegmation,  to  the  lower  portion  of  the  column,  while 
the  products  condensed  in  k  are  conveyed  by  pipes  into  the  upper  porti(m  of 
the  colunm.    When  it  is  desired  to  prepare  toluol  instead  of  benzol  the  chloride  of 
calcium  apparatus  is  heated  to  loS*'  to  109''. 

H.  Oaro,  A.  and  K.  Glemm,  and  F.  Eugelhom  have  suggested,  instead  of  making 
benzol  from  coal-tar,  it  should  be  extracted  from  coal-gas  by  causing  this  to  be  passed 
slowly  through  tar-oils  which  have  a  higher  boiling-point  than  benzol,  toluol,  &c.,  and  to 
extract  by  distillation  the  benzol,  &c.,  from  these  heavy  oils  after  they  have  became 
saturated.  The  heavy  oils  can  serve  tlie  same  purpose  again,  while  as  regards  the 
depreciation  of  the  illuminating  power  of  the  gas  caused  by  the  withdrawal  oi  tbe 
hydrocarbons,  benzol,  &c.,  present  in  the  gas  as  vapours,  the  authors  suggest  the 
saturation  of  tlie  gas  with  petroleum  oil  (benzoline).  Tliis  mode  of  making  benzol  is 
not  yet  practised  on  the  large  scale. 
Mitn-bensoL       The  bcuzol  is  Converted  into  nitro-ben^ol  by  the  aid  of  nitric  acid ;  the 

commercial  article   is    a  mixture  of  nitro-benzol,  Ce  |  ^k      nitro-toluol,  C^  |  ^h 

f  IT 
and  nitro-xylol,  ^sJ^q  .     £.  Mitscherlich  discovered  nitro-benzol  in  1834,  and 

O.  Gollas  first  prepared  this  substance  on  the  large  scale  at  Paris  under  the  name  of 
Essence  de  Mirhane.  The  apparatus  employed  formerly  for  the  making  of  this  prepara- 
tion was  contrived  by  Mansfield,  and  consists  of  a  convoluted  glass  tube,  which 
towards  its  top  or  upper  end  is  bifurcated  so  as  to  form  two  separate  tubes  fitted 
with  funnels.  '  Into  one  of  these  a  continuous  stream  of  benzol,  and  into  the  oth^* 
strong  nitric  acid,  is  caused  to  flow ;  and  while  these  liquids  are  carried  downwards 
by  gravitation  through  the  windings  of  the  tube  the  combination  takes  place,  and 
the  warm  liquid  is  so  far  cooled  that  it  can  be  collected  at  the  lower  end  of  the  tu^ 
The  crude  nitro-benzol  thus  obtained  is  rendered  pure  by  firftt  washing  it  with  water 
and  next  with  a  dilute  solution  of  carbonate  of  soda. 


DYEING.  573 

Pttra-nitro-benzoie  add,  a  substance  isometric  wiUi  nitro -benzoic  acid,  is  fonnd  in 
the  washings  of  the  nitro-benzol. 

It  is  preferable,  however,  to  prepare  nitro-benzol  from  a  mixture  of  2  parts  of 

nitric  acid  at  40**  Beaum6  (sp.  gr.  1*384)  and  i  part  of  concentrated  sulphuric  acid, 

the  operatiou  being  carried  on  in  closed  vessels  very  similar  to  those  in  use  for 

making  aniline.     The  upper  part  of  the  apparatus  is  fitted  with  a  tube  for  conveying 

the  nitrous  acid  fumes  to  a  chimney,  while  an  S-shaped  tube  connects  the  apparatus 

-with  the  tank  containing  tlie  acid  mixture.    The  quantity  of  benzol  intended  to  be 

nitrated  is  introduced  into  the  apparatus  at  one  time ;  the  mixed  acids  are  gradually 

poured  into  the  benzol,  and  the  reaction  aided  by  a  stirring  apparatus.    Any  benzol 

volatilised  by  the  heat  generated  by  the  reaction  is  condensed  by  an  apparatus  fitted 

to  the  reaction  vessel  and  is  thus  saved.    The  end  of  the  reaction  is  indicated  by 

the  liquid  becoming  colourless  and  being  separated  into  two  distinct  strata  by  the 

addition  of  water.    The  acid  is  first  diluted  to  50''  B.  (sp.  gr.  1*532)  and  the  fluids 

are  separated  by  decantation.    The  nitro-benzol  is  purified  by  washing  with  water, 

the  dilute  acid  mixture  being  used  either  in  the  making  of  sulphuric  acid  or  in 

other  chemical  processes,  such  as  the  preparation  of  superphosphates.     On  £.  Kopp's 

suggestion  nitro-benzol  is  now  made  by  tlie  aid  of  a  mixture  of  nitrate  of  soda  and 

sulphuric  acid.     100  kilos,  of  benzol  yield  135  to  140  of  nitro-benzol. 

We  distinguish  three  different  kinds  of  nitro-benzol,  viz. : — i.  Light  nitro-benzol, 
boUiag  between  205''  and  210°.  This  is  used  in  perfumery  and  soap -making  in  very 
large  quantities  under  the  name  of  artificial  oil  of  bitter  almonds,  or  Estence  de 
Mirbans,  sp.gr.  =  1*20  (=  24^  B.)  2.  Heavy  nitro-benzol,  boiliug  between  210"*  and 
220**,  possessing  a  peculiar  fatty  smell.  It  is  not  used  in  perfumery,  but  chiefly  for 
the  preparation  of  aniline  red;  sp.  gr.  =  I'lg  (=  28°  B.)  3.  Very  heavy  nitro- 
benzol,  boiling  between  222°  and  235°,  sp.gr.  =  1*167  (=  5^''  ^•)  ^^  disagreeable 
odour,  this  kind  is  chiefly  used  for  the  preparation  of  aniline  intended  for  making 
aniline  blue.  ^ 

AaiiiM.      The   crude    aniline  used  for  the  preparation  of  the  so-called   tar    or 
aniline  colours  is  essentially  a  mixture  of  aniline,  C6H7N,  tolnidine,  C7H9N,  and  the 
pseudo-toluidine  discovered  by  Kosenstiehl,  a  body  isomeric  with  tolnidine.    This 
kind  of  aniline  is  known  in  tlie  trade  as  aniline  oil.    Pure  aniline  and  pure  toluidine 
only  yield  pigments  under  special  conditions.    Aniline  was  discovered  at  Dahme,  in 
Saxony,  by  Dr.  Unverdorben,  in  1826,  among  the  products  of  the  dry  distillation  of 
indigo,  and  in  1833  Runge,  at  Oranienburg,  near  Berlin,  discovered  its  presence  in 
coal-tar.    Runge  also  discovered  that  aniline  yielded,  when  brought  into  contact 
with  a  solution  of  hypochlorite  of  lime  (bleaching-powder),  a  beautiful  violet  colour ; 
hence  the  name  kyanol  {blue  colouring  oil).    Dr.  von  Fritzsche,  St.  Petersburg,  1841, 
thoroughly  investigated  the  substance  obtained  by  Dr.  Unverdorben  from  indigo, 
ascertained  its  composition,  and  called  it  aniline,  from  anil,  the  Portuguese  term  for 
indigo.    In  the  year  1842  Zinin  found  that  when  nitro-benzol  was  treated  with 
sulphuretted  hydrogen,  there  was  formed  a  base  which  he  termed  benzidam.    The 
farther  researches  of  0.  L.  Erdmann  and  Dr.  A.  W.  Hofmann,  brought  the  fact  to  light 
that  Dr.  Unverdorben's  crystalline,  kyanol,  benzidam,  and  aniline  were  tlie  same 
substance,  to  which  the  name  aniline  was  then  finally  given.    We  owe  to  the  exten- 
sive researches  of  Dr.  A.  W.  Hofmann  our  present  knowledge  of  aniUne  and  its 
compounds. 
Coal-tar  contains  0*3  to  0*5  per  cent  of  aniline,  but  its  extraction  from  tar  is 


574 


CHBinCAL  TECEKOLOar. 


attended  with  so  manj  difBcultiee  that  it  is  preferred  to  prepare  «wiiinft  from  nitfo- 
benzol  b;  a  reaction  discovered  by  /in in  ;  that  is  to  say,  to  bring  nitro-be]u<d  into 
contact  with  reducing  taenia,  i  molecule  of  nitro -benzol,  C^H^NiO  ^  123,  jviii 
I  molecule  of  aniline,  CgH^N  =  93.  In  practice  itis  assumed  that  100  parta  of  uOd- 
benzol  yield  100  parts  of  aniUue. 

Although  sulphuretted  hydrogen  completely  reduces  nitro-beniol  to  ■ 
trade  working  on  tlie  large  scale  prefers  to  follow  fi£champ'smet])od,  the  li 
nitro-benzol  with  irou-filings  and  acetic  acid.  The  apparatus  in  use  for  canyiag 
oat  tliis  operation  was  devised  by  Nicholson,  and  is  exhibited  in  Pig.  268.  It 
consists  essentially  of  a  cast-iron  cylinder,  a,  of  lo  hectolitres  (230  gallons)  enUt 
capacity.  A  stout  iron  tube  is  fitted  to  this  vessel  reaching  nearly  to  the  bottom  of 
tlie  cyhnder.     The  upper  part  of  this  tube  is  connected  with  the  machinery  a,  while 


the  surface  of  the  tnbe  is  fitted  with  steel  projectjons.  The  tube  serves  to  kdmit 
steam  as  well  as  acting  as  a  stirring  apparatus.  Sometimes,  instead  of  this  tabe,  a 
solid  iron  axle  is  employed,  and  in  tlus  case  there  is  a  separate  steam-pipe,  d. 
Through  the  opening  at  k  the  materials  for  making  aniline  are  put  into  the 
apparatus,  while  the  volatile  products  are  carried  oC  through  e.  h  serres  far 
emptying  and  cleaning  the  apparatus.  The  Sshaped  tnbe  connected  with  tha 
vessel  s  acts  as  a  safxty-valve,  ^Vhen  it  is  intended  to  work  tritfa  this  ^parstiia, 
there  is  first  poured  into  it  through  k  10  kilos,  of  acetic  acid  atS'S.  (=sp.gr.  lofio). 
previously  dOnted  with  six  times  tlie  weiglit  of  water ;  next  there  are  added  30  kilos, 
of  iron-filings  or  cast-iron  borings,  and  125  kilos,  of  nitro-benzol,  and  immediately 
after  the  stirrinf;  apparatus  is  set  in  motion.  The  reaction  ensues  directly,  and  ia 
attended  by  a  consideiable  evolution  of  heat  and  of  vapours.    Gradually  more  irwi 


DYEING.  575 

is  added  until  the  quantity  amounts  to   i8o  kilos.     The  escaping  vapours  are 

condensed  in  f,  and  the  liquid  collected  in  r  is  from  time  to  time  poured  hack  into 

the  cylinder,  a.    The  reduction  is  finished  after  a  few  hours.      The  resulting  thick 

magma  exhibits  a  reddish-brown  colour,  and  consists  essentially  of  hydrated  oxide  of 

Iron,  aniline,  acetate  of  aniline,  acetate  of  iron,  and  excess  of  iron.    Leaving  the 

acetic  add  out  of  the  question,  the  process  may  be  elucidated  by  the  following 

formula:^ 

C6H5NOa+HaO+Fea=C6HyN+Fea03. 

Nitro-benzol.  Aniline.  Peroxide 

of  iron. 

This  magma  is  either  first  mixed  with  lime  or  is  put  into  cast-iron  cylinders  shaped 
like  gas-retorts,  and  submitted  to  distillation,  the  source  of  heat  being  either  an  open 
fire  or  steam.  The  product  of  this  operation,  consisting  of  aceton,  aoetaniline, 
aniline,  nitro-benzol,  &c.,  is  rectified  by  a  second  distillation,  care  being  taken  to 
collect  only  the  product  which  comes  over  between  115^  and  190^;  but  a 
product  which  comes  over  at  between  210**  and  220**  is  very  suitable  for 
the  preparation  of  aniline  blue.  The  amline  oil  thus  obtained  is  a  somewhat 
brown-coloured  liquid,  heavier  than  water,  and  pure  enough  for  the  preparation  of 
the  aniline  colours.  According  to  Brimmeyer,  acetic  acid  is  not  necessaiy,  and  a 
yrerj  good  result  may  be  obtained  by  mixing  nitro-benzol  with  60  parts  of  pulverised 
iron  with  acidified  water  (2  to  2*5  per  cent  of  hydrochloric  acid  upon  the  weight  of 
nitro-benzol),  and  leaving  this  mixture  to  stand  in  a  retort  for  some  three  days 
before  distilling  off  the  amline  oil.  In  the  aniline-oil  works  of  Coblentz  Fr^res,  at 
Paris,  nitro-benzol  is  reduced  by  the  aid  of  iron-filings,  a  portion  of  which  have  been 
coated  with  copper  by  being  immersed  in  a  solution  of  the  sulphate. 

The  composition  of  the  aniline  oil — essentially  a  mixture  of  aniline,  toluidine,  and 
pseudo-toluidine^-depends  upon  the  nature  of  the  benzol  and  nitro-benzol  used  for 
its  preparation.  The  aniline  oil  boiling  between  180°  and  195°  (sp.  gr.  =  1014  to 
z'02i  =  2^  to  3°B.)  is  prepared  from  nitro-benzols  which  boil  between  210''  and  220^ 
and  the  aniline  it  yields  is  chiefly  used  for  aniline  red ;  while  for  aniline  blue  a  very 
heavy  nitro-benzol  is  employed,  and  for  aniline  violet  a  nitro-benzol  which  boils  at 
210^  to  225°.  The  following  table  exhibits  the  boiling-points  of  the  substances  which 
have  been  mentioned : — 

Benzol     80**  Kitro-toluol    225^ 

Toluol      108^  Aniline    182° 

Nitro-benzol    213°  Toluidine        198^ 

As  regards  the  annual  production  of  aniline  oil  it  is  now  (1871)  3,500,000  lbs.,  of 
which  2,000,000  lbs.  are  consumed  in  Germany,  and  the  remainder  in  Switzerland, 
England,  and  France. 

I.  Aniline  Colours, 

AafliiMCoioim.  The  aniline  oil  serves  for  the  industrial  production  of  the  so-called 
amline  or  toluidine  colours: — i.  Aniline  red.  2.  Aniline  violet.  3.  Aniline  blue. 
4.  Aniline  green.  5.  Aniline  yellow  and  aniline  orange.  6.  Aniline  brown.  7.  Ani- 
line black. 

abuimb^.  I.  This  pigment  or  dye,  also  known  as  fuchsin,  azaleine,  mauve, 
solferino,  magenta,  roseine,  tyraline,  &c.,  is  the  combination  of  a  base,  (which 
Dr.  A.  W.  Hofioiann  has  named  rosaniline,  with  an  acid,  usually  acetio  or  hydro- 


576  CHEMICAL  TECHNOLOGY. 

chloric.  In  Germany  and  Switzerland  fuchsin  is  the  hjdrochlomte  of  nKanilbe, 
02oHz9N3,01H ;  while  in  England  the  acetate  is  used,  the  formula  being 

The  base  rosaniline  is  a  colourless  substance,  but  its  readily  crystallising  salts  an 
coloured.  The  composition  of  this  base  is  expressed  by  the  formula,  CaoHigNj^H^O; 
and  it  is  formed  by  the  combination  of  2  atoms  of  toluidine  with  i  atom  of  anihne 
and  the  elimination  of  4  atoms  of  H,  which  become  oxidised — 

aCyH^N +C6H7N +3O = aHaO+CaoHx9N3.HaO. 
Accordingly  the  constitutional  formula  of  rosaniline  is : — 

2C7H6  Na^CaoHigNa. 
H3. 

According  to  Hosenstiehl's  researches  (1869)  all  the  different  kinds  of  fuchsin  of 
commerce  contain  pseudo-rosaniline,  a  base  isomeric  with  rosaniline. 

Aniline  red  can  be  obtained  from  aniline  oil  by  the  application  of  various  reageiiti, 
as,  for  instance : — Chloride  of  tin,  Verguin*s  method ;  perchloride  of  carbon,  Hof- 
mann  and  Natanson's  methods ;  pernitrate  of  mercury,  Gerber-Keller;*  perchlonde 
of  mercury,  Schnitzer ;  nitric  acid,  Lauth  and  DepouiUy ;  antimonic  acid.  Smith; 
arsenic  acid,  Medlock,  Oirard  and  de  Laire ;  aniline  oil,  nitro-toluol,  hydrochlonc 
acid  and  metallic  iron.  Coupler.  100  parts  of  amline  oil  yield  25  to  33  parts  of 
crystalline  fuchsin. 

Notwithstanding  the  great  danger  arising  from  the  use  of  arsenic  add,  and  the 
difficulty  of  disposing  of  the  very  poisonous  residues  of  this  mode  of  preparing  fuch- 
sin, the  majority  of  the  manufacturers  of  tliis  dye  prefer  to  use  the  arsenic  add 
method.  According  to  Girard  and  de  Laire's  method  i  cwt.  of  aniline  oil  and  2  cwts. 
of  hydrate  of  arsenic  acid  at  60**  B.  (=171  sp.  gr.)  are  heated  together  for  4  to  5 
hours  at  a  temperature  which  should  not  exceed  190^  to  200°.  The  red  fused  maas 
(fnohsin  mixture  or  smelting)  formed  by  this  operation  is  broken  into  small  Imapf 
and  then  boiled  with  water,  and  as  soon  as  the  mass  is  dissolved  it  is  filtered  through 
felt  or  linen  bags,  and  the  filtrate  poured  into  tanks  for  the  purpose  of  obtaining 
crystals.  After  the  lapse  of  2  to  3  days  the  mother-liquor,  a  very  poisonous  liquid, 
which  covers  the  crystals,  is  run  off  into  perfectly  water-tight  tanks  made  of  stone  and 
coated  \vith  asphalte,  and  in  order  to  precipitate  the  arsenic  and  arsenioua 
there  is  added  a  mixture  of  washed  clialk  and  lime,  the  ensuing  precipitate 
employed  for  making  arsenical  preparations,  t  The  crystalline  mass  is  purified  by 
re-crystallisation.  In  the  French  fuchsin  works  the  fused  mass  is  dissolved  in 
water  and  hydrochloric  acid,  and  next  neutralised  with  soda.  The  fuchsin  is  thus 
obtained  as  a  crystalline  cake,  which  is  dissolved  by  being  boiled  with  water,  and  this 
solution  allowed  to  crystallise.  The  fuchsin  thus  obtained  always  contains  arsenic, 
and  when  it  is  desired  to  use  a  salt  of  rosaniline  for  colouring  liqueurs  and  sweet- 
meats it  is  necessary  to  use  a  preparation  made  with  either  chloride  of  carbon  or 
bichloride  of  mercury.  The  salts  of  rosaniline  exhibit  by  reflected  light  a  green 
golden  hue ;  by  transmitted  light  the  colour  is  red.  The  hydrochlorate  of  rosaniline 
is  usually  called  fuchsin,  the  acetate,  roseine,  and  the  nitrate,  azaleine.  The  solutians 

*  The  fuchsin  prepared  by  the  aid  of  this  reagent  is  known  as  rubin,  and  is  employed 
for  dyeing  silk  and  for  colouring  liqueurB  and  siraetmeats. 

t  According  to  Dr.  BoUey,  the  arsenical  fluids  obtained  can  be  rendered  again  fit  for 
by  distillation  with  hydrochloric  acid.    On  being  diluted  with  water  the  arsenioos 
contained  in  the  distillate  is  thrown  down. 


DYEING.  577 

of  these  salts  in  water  or  in  alcohol  exhibit  a  well-known  and  very  magnificent, 
ottrmine  red.  The  tinctorial  power  is  exceedingly  high,  since  i  kilo,  of  fachsin 
is  sufficient  to  dye  2oo  kilos,  of  wool.  The  tannate  of  rosaniline  is  Tery  difficultly 
soluble  in  water.  Fuchsin  is  the  basis  of  nearly  all  other  aniline  colours;  for 
instance,  fuchsin  yields  violet  or  blue  with  aniline  oil ;  fuchsin  and  iodide  of  ethyl, 
blue  or  violet.  The  action  of  the  arsenic  acid  in  the  formation  of  rosaniline  may  be 
represented  as  follows : — 

2C6H9N}  =  CjoE^3+3A^=  CaoHxgNa+jAsaOs+sH^O. 

Aniline       Arsenic      Bosaniline.  ArBeniouB  Water, 
oil.  '  acid.  add. 

Aaiuaa  Violet  2.  This  pigment,  also  known  as  aniline  purple,  anileine,  indisine,  phena- 
nicine,  harmaline,  violine,  rosolan,  mauveine,  was  discovered  in  1856  by  Dr.  W.  H. 
Perkin,  and  is  prepared  by  the  action  of  bichromate  of  potash  and  sulphuric  acid. 
Xhis  substance  has  also  been  prepared  by  other  reactions,  for  instance,  by  the  treat- 
ment of  a  salt  of  aniline  with  a  solution  of  bleaching-powder  (BoUey,  Beale,  Kirk- 
bom)  ;  with  peroxide  of  manganese  (Kay),  and  peroxide  of  lead  (Price),  both  in  the 
presence  of  sulphuric  acid ;  by  the  action  of  permanganate  of  potash  upon  a  salt  of 
aniline  oil  (Williams) ;  by  treating  aniline  oil  with  chlorine  (Smith) ;  with  ferri- 
cyanide  of  potassium  (Smith) ;  with  chloride  of  copper  (Garo  and  Dale).  Indus- 
trially, only  Dr.  Perkin's  method  with  the  bichromate  and  sulphuric  acid  is  used. 
The  base  of  the  violet  thus  obtained  is  mauveine,  €27^124^. 

The  so-called  Violet  ImpSrial  obtained  by  Girard  and  de  Laire  by  the  action 
of  chromate  of  potash  upon  a  mixture  of  aniline  oil  and  hydrochlorate  of  rosaniline 
at  I  So*',  differs  from  the  preceding  product,  while  another  violet  is  obtained  according 
to  Nicholson  by  heating  fuchsin  to  200"^  to  21 5^  When  a  salt  of  rosamline  is  heated 
with  excess  of  aniline  there  are  formed,  before  blue  colours  ensue,  violet  pigments,  of 
which,  according  to  Ho&oann — 

The  red- violet  is  monophenyl-rosaniline. 

The  blue- violet  is  diphenyl-rosaniline. 

This  latter  yields  on  being  further  heated  triphenyl-rosaniline  or  aniline  blue. 
Accordingly, — 

Rosaniline  red  is    CjioHaiNsO. 

Monophenyl-rosaniline  (red-violet)  is        G2oHao(C6H5)N30. 

Diphenyl-rosaniline  (blue-violet)  is    C2oH.ig{C6H.^)2^sO, 

Triphenyl-rosaniline  (blue) G«>Hx8(06H5)3N30. 

The  violet  is  now  named  the  old  or  Nonpareil  violet;  and  we  have  the  new 
or  iodine  violet,  Hofinann's  violet  or  dahlia  colour,  distinguished  by  the  presence  of 
the  alcohol  radicals,  ethyl,  methyl,  and  amyl,  instead  of  phenyl  These  new  violets 
are  obtained  by  heating  to  100^  or  iio^  fuchsin  with  alcohol  as  a  solvent,  and 
the  iodides,  or  more  recently,  the  bromides,  of  the  alcohol  radicals,  the  mixture 
being  kept  in  closed  cylindrical  vessels.  According  to  the  length  of  time  this 
reaction  is  allowed  to  take  place  there  are  formed : — 

Monethyl-rosaniline, 
Diethyl-rosaniHne,  or 
Triethyl-rosamline. 

The  most  ethylised  base  exhibits  a  blue-violet  colour,  while  the  less  ethylised 

2  u 


n 


578  CHEMICAL  TBCHNOLOGY, 


exhibits  a  red  hue.  The  methylated  and  ethylated  violets  are  hr  more  hriTTiantttaa 
the  phenylated.  The  Violet  de  Paris,  introduced  by  Poinier  and  Chappot,  ii  tiba 
prodnct  of  the  action  of  chloride  of  tin  and  similar  oompounds  upon  the  medqfl  or 
ethyl  aniline, 
▲niiina  Bine.  3.  This  coloor,  also  known  as  aznline  and  aznrine,  was  first  obtaiaei  in 
186 1  by  de  Laire  and  Girard  by  heating  together  for  some  hours  a  mixture  of  6Mii- 
sin  and  aniline  oil,  and  treating  the  product  of  this  reaction  with  hydroehlorie  aoL 
The  blue  pigment  produced  is  known  in  commerce  as  bleu  de  Parte  or  bleu  de  Lfon ; 
in  dry  state  it  is  a  copper- coloured  shining  material,  not  exhibiting  green  or  yeSor 
by  reflection,  the  characteristic  of  fachsin  and  aniline  violet.  In  order  to  purify  tfe 
aniline  blue  it  is  dissolved  in  strong  sulphuric  acid,  and  this  mixture  heated  to  150* 
for  li  hours.  By  the  addition  of  water  to  this  solution  the  blue  is  pre<npitaied  in  t 
modified  and  soluble  form  and  is  then  called  bleu  soluble.  We  quote  here  the 
following  methods  for  preparing  this  blue: — Rosaniline  and  aldehyde  (Laoth); 
rosaniline  and  crude  wood-spirit  (E.  Kopp)  ;  rosaniline  and  alkaline  solution  of 
shellac  (Gros-Renaud  and  Schafier),  this  is  termed  bleu  de  Mulhouse  ;  also  by  oxida- 
tion of  methylaniline  (J.  Wolff) ;  rosaniline  and  bromated  oil  of  turpentine  (BeddiU ; 
rosaniline  and  isopropyl  iodide  (Wanklyn) ;  rosaniline  and  ethylen  iodide  and 
bromide  (M.  Vogel) ;  rosaniline  and  iodide  and  bromide  of  aceton  (Smith  and  Sie- 
berg).  The  conversion  of  hydrochlorate  of  rosaniline  (fdchsin)  by  heating  with 
aniline  oil  into  aniline  blue  is  elucidated  by  the  following  formula : — 

CaoHxgNj.ClH+aCeH^N  =  CaoHx6(C6H5)3Ns,Ha+3NH3. 

Bosomline  salt.    Aniline.  Aniline  blue.  Ammonii^ 

C6H4) 
The  aniline  blue  thus  prepared  is  rosaniline,  zCy'Rt  N3,  in  whi^  3  atoms  of 

hydrogen  have  been  substituted  by  3  atoms  of  phenyl,  GsHj ;  or,  in  other 
this  aniline  blue  is  triphenyl-rosoniline,  the  hydrochlorate  of  which  is — CjsHj^sKjCI 
When  a  salt  of  rosaniline  is  heated  with  toluidine,  the  toluidine  blue  (tritolyi- 
rosaniline),  G4XH37N3  =  C2oHx6(G7H7)3N3.  When  aniline  blue  is  heated,  the  produda 
of  the  dry  distillation  contain  diphenylamine,  CisHxxK,  a  white  crystalline  campound. 
which  when  moistened  with  nitric  acid  yields  a  magnificent  blue  colour.  Diphenyl- 
amine and  its  homologue  phenyl-tolylamin,  CxsHxsN,  which  yields  by  dry  diatiDa- 
tion  bleuine,  C3gH33N3,  are  employed  for  the  preparation  of  blue  pigments.  Dr.  A* 
W.  Hofinann  found  that  when  rosaniline  is  heated  for  a  considerable  length  of  time 
with  iodide  of  ethyl  or  iodide  of  amyl,  the  result  is  that  the  most  etl^iaied  or 
amylated  product  (triethyl-rosaniline,  or  triamyl-rosaniline),  yields  aniline  Use 
(iodine  blue).  Naphthyl  also  may  be  introduced  into  fuchsiD  to  fonn,  aoccHding  to 
Wolf;  a  brilliant  blue  colour  termed  naphthyl  blue.  Under  the  names  of  BUu  d0 
lumih'e  or  Bleu  de  nuit,  is  known  a  blue  dye  which  appears  blue  in  daylight  as  weQ 
as  in  artificial  light.    A  blue  with  a  violet  hue  is  known  as  Bleu  de  Parme. 

AaiiiiMaffMn.  4.  We  are  acquainted  with  two  varieties  of  this  colour,  viz.  alddyda 
green  and  iodine  green.  The  former,  also  called  emeraldine,  was  discovered  in  1863 
by  Gherpin,  chemist  in  M.  Us^be's  Works  at  Saint  Guen,  and  is  obtained  by 
treating  a  sulphuric  acid  solution  of  sulphate  of  rosaniline  with  aldehyde.  Bj 
cautiously  heating  this  mixture,  a  deep  green  pigment  is  obtained  which  oontaioa 
sulphur;  the  formula  of  this  compound  Ib,  according  to  Dr.  A.  W.  Hofinann, 
CasH^NjSsG.     When  required  for  use  hyposulphite  of  soda  is  added  and  ths 


DYEING.  579 

compound  boiled  tberewith  in  water ;  this  Bolation  is  used  for  dyeing  silk,  and  instead 
of  the  soda-salt  snlphoret  of  ammonium  or  sulphuretted  hydrogen  may  be  used. 
The  green-ooloured  material  can  be  precipitated  by  a  mixture  of  common  salt  and 
sodic  carbonate,  while  a  mixture  of  2  parts  of  sulphuric  acid  and  50  to  70  parts  of 
alcohol  is  a  solvent  for  this  substance.  This  aniline  green  is  especially  beautiful 
"when  seen  by  candle-light  The  other  kind  of  aniline  green  is  the  so-called  iodine 
green,  discoTered  (1863)  ^7  ^'  ^  ^'  Hofinann,  as  a  by-product  of  the  manufacture 
of  the  methylated  and  ethylated  rosaniline  yiolets. 

Iodine  green  is  obtained  by  the  following  process : — z  part  of  acetate  of  rosaniline, 
22  of  iodide  of  methyl,  and  2  of  methylic  alcohol,  are  heated  together  for  seyeral 
lionrs  xmder  a  high  pressure,  or  on  the  small  scale  in  a  sealed  tube.  When  the 
operation  is  finished  the  result  is  a  mixture  of  violet  and  green  pigments  dissolved  in 
xnethylic  alcohoL  The  volatile  substances  having  been  driven  off  by  distillation  the 
mixture,  of  pigments  is  put  into  boiling  water,  wherein  the  green  is  completely 
dissolved,  while  the  violet  remains  insoluble ;  the  former  is  precipitated  by  a  cold 
saturated  solution  of  picric  acid  in  water,  the  ensuing  precipitate— picrate  of  iodine 
green — ^is  collected  on  a  filter,  rapidly  washed  with  the  smallest  possible  quantity  of 
-water,  and  after  having  been  partly  dried,  brought  into  commerce  as  a  paste 
{en  p&te).     The  crystalliue  iodine  green,  free  from  picric  acid,  has  the-  formula 

IS&^Ji.  5-  By  the  preparation  of  the  red-coloured  pigments  from  aniline  oil, 
there  is  formed,  as  well  as  fuchsin,  a  resinous  substance,  from  which  Nicholson 
obtained  a  brilliant  yellow-coloured  pigment,  the  aniline  yellow,  aniline  orange, 
aurin,  or  hydroohlorate  of  chrysaniline,  which  dyes  wool  and  silk  brilliantly  y^ow. 
'Chrysaniline  is  a  base  of  the  formula  CaoHx7N3.  The  most  interesting  salt  of  this 
base  is  the  nitrate,  which  is  insoluble  in  water.  The  residue  of  the  preparation 
of  fuchsin  is  treated  with  steam,  and  as  soon  as  a  portion  of  the  base  has  been  dis- 
solved, it  is  precipitated  by  the  aid  of  nitric  acid.  Schiff  obtained  aniline  yellow  by 
the  action  of  antimonic  acid  or  hydrated  oxide  of  tin  upon  aniline;  M.  Vogel 
obtained  a  yellow  pigment  by  the  action  of  nitrous  acid  upon  an  alcoholic  solution  of 
rosaniline.  This  aniline  yellow  has  the  formula,  O^oHigN^Oe;  it  is  soluble  in 
alcohol,  not  so  in  water. 

•ndfflSTaSU.  6-  Aniline  black,  CeHyNOe,  a  deep  aniline  green  formed  by  the 
action  of  oxidising  agents  upon  aniline  oil,  was  observed  as  early  as  1843  by  Dr.  J. 
von  Fritzsche,  and  was  formerly  prepared  from  the  residues  of  the  prepara- 
tion of  aniline  violet  with  bichromate  of  potash ;  but  now  we  obtain  aniline  black  by 
the  action  of  chlorate  of  potash  and  chloride  of  copper  upon  hydroohlorate  of 
aniline,  a^  recommended  by  Lightfoot  As  has  been  proved  by  Ck>rdillot,  these  two 
chemical  reagents  may  be  replaced  by  ferricyanide  of  ammonium ;  or,  according  to 
liauth,  by  freshly  precipitated  sulphuret  of  copper.  According  to  Bolley,  the  last 
Bubstanoe  acts  by  becoming  oxidised  to  sulphate  of  copper,  and  simultaneously 
carrying  oxygen  on  to  aniline.  The  black  made  accordiog  to  this  method  being 
insoluble  has  to  be  formed  on  the  woven  textile  fabrics  themselves,  and  is  hence  also 
called  black  indigo  or  indigo  black.  More  recently,  again,  the  so-called  Lucas  black 
(Peterson's  black)  has  been  obtained,  its  most  valuable  property  being  that  it  is 
a  ready  made  black,  which  for  its  full  development  only  requires  a  weak  oxidation. 
It  is  a  black  fluid  mass  consisting  of  hydrochlorate  of  aniline  and  acetate  of  copper, 
which  mixed  with  some  starch  paste  is  printed  on  the  &bric8.    The  black  becomes 


1 


SBo  CHEMICAL  TSCHNOLOOT. 


oxidised  by  exposure  to  air;  the  oxidatioii  is  rendered  nuxre  rftpid  hy  agoig 
the  &bric8  in  a  room  heated  to  40^  Aniline  blade  is  used  both  in  dyeii^  aid 
printing  textile  fabrics. 

7.  Amline  brown  (Habana  brown)  is  prepared  according  to  de  Laare  bjr  heating  a 
mixtore  of  aniline  violet  or  aniline  blue  with  hydrochlorate  of  aniline  to  240%  mitfi 
the  mixture  becomes  brown-colonred.  The  brown  thus  obtained  is  solnUe  ia  wiier, 
alcohol,  and  acids,  and  can  be  at  once  employed  in  dyeing.  Another  kind  of  anifiM 
brown  (Bismark  brown)  is  obtained  by  fusing  fochsin  with  hydrochlorate 


n.  Carholio  Acid  Colours, 

OttiMiie  Add  Dyw.  The  portion  of  heavy  coal-tar  oil  which  distils  over  at  150*  to  200^ 
consists  chiefly  of  carbolic  acid  (phylic  acid  phenol).  As  brought  into  commeree  bj 
G.  Calvert  and  Co.,  C.  Lowe  and  Co.,  and  a  great  many  other  eminent  firms  both  in 
this  country  and  abroad,  carbolic  acid  is  a  crystalline  mass  which  beoomea  slightly 
reddened  by  exposure  to  air,  fuses  at  34*^,  and  boils  at  i86^  It  is  prepared  aoc(Bdii^ 
to  Laurent's  method  by  treating  the  heavy  oils  of  tar  with  alkalies.  There  are  three 
homologous  phenols  in  this  preparation : — 

Carbolic  acid,  CeHsO, 
Cresylic  acid,  C7H8O. 
Phlorylic  add,  CsHxoO. 

Carbolic  acid  is  soluble  in  33  parts  of  water.  Calvert's  carbolic  acid,  as  ased  in  the 
colour-works,  is  prepared  by  cooling  a  mixture  of  the  Laurent  acid  in  water.  At  -h  4' 
a  hydrate  of  carbolic  acid,  CeHeO+HsO,  is  separated,  and  by  elimination  of  water  it 
becomes  j9tfr0  carbolic  acid,  which  fuses  at  41**.  While  carbolic  acid  is  very  laigdv 
bsed  in  several  degrees  of  purity  for  a  variety  of  purposes  as  an  antiseptic,  diais' 
fectant,  &o.,  more  than  50  per  cent  of  all  the  carbolic  add  ma.nufactnred  ia  used  iv 
the  purpose  of  preparing  the  following  pigments  and  dye  materials : — 

1.  Picric  acid.  4.  Coralline. 

2.  Phenyl  brown.  5.  Azuline. 

3.  Gr6nat  soluble. 

Ftaie  Add.  Picric  acid,  trinitro-phenylic  add,  CaHjfNO^^sO,  obtained  by  the  adioB 
of  nitric  acid  upon  carbolic  acid,  or  better,  by  treating  crystallised  phenyl  sulphate 
of  sodium  with  nitric  acid,  is  a  yellow  substance  ciystalliaing  in  foliated  straetme* 
difficultly  soluble  in  cold,  readily  in  hot  water,  and  also  soluble  in  aloohoL  It  is 
used  for  dyeing  wool  and  silk  yellow,  and  with  aniline  green  (iodine  green),  indigo, 
and  Berlin  blue,  it  is  used  for  dyeing  silk  and  wool  green.* 

In  France  annually  some  80  to  100  tons  of  picric  acid  are  prepared,  but  the  bulk  is 
used  for  the  manufacture  of  the  picrate  gunpowder  (see  p.  157).  The  ammonia  salt 
of  the  trinitro-cresylic  add  is  met  witii  in  the  trade  as  Victoria  yellow  as  a  dye 
material  When  treated  with  cyanide  of  potassium,  picric  add  yields  isoparpmEio 
add,  while  thetrinitro-cresylic  acidyidds  with  the  same  cyanide  cresyl-piirpaiie  add 
(V.  Sommaruga) ;  the  potassium  and  ammonium  salts  of  the  respective  adds  yield  the 
grenate  brown. 

*  It  has  of  late  become  UBnai  to  employ,  instead  of  pure  (non-explofdve)  picrie  aeid,  the 
Boda  salt  of  thai  acid,  under  the  name  of  picric  acid  and  aniline-yellow.  This  haa  ffwm. 
rise  to  very  serious  acddents,  owing  to  the  highly  ezplosiye  nature  of  the  salt. 


DYEING.  58X 

2.  Phenyl  bzown  was  first  prepared  by  Both  in  1865  ^7  causing  nitro- 
snlphniio  add  to  act  upon  carbolic  acid ;  the  resulting  substance,  ph6nicienne  or 
phenyl  brown,  is  an  amorphous  powder,  a  mixture  of  two  pigments,  viz.,  a  yellow, 
according  to  Bolley,  dinitrophenol,  C6H4(N02)20,  and  a  black-brown  substance 
'W'hich  is  sLmilar  to  the  humus  compounds.  Phenyl  brown  is  used  for  dyeing  wool 
and  silk. 

oniMtoBrowa.  3.  Grduat  soluble,  which  has  been  yery  recently  introduced  by 
J.  Oasthelaz  in  Paris  as  a  substitute  for  orseille,  is  nothing  more  than  the  weU- 
&nown  isopurpurate  of  potash,  which  was  first  discovered  by  Hlasiwetz,  and  is 
£onned  by  the  action  of  C3ranide  of  potassium  upon  a  solution  of  picric  acid  according 
to  the  following  reaction,  as  described  by  Zulkowsky : — 

C6H3(NOa)30+3KON+2HaO=C8H4KN306+NH3+KC03. 

Picric  add.    Cyanide  of  Isopurpurate      Am-  Carbonate 

potassimn.  of  potash,      monia.  of  potash. 

As  Grenate  brown  when  dry  is  explosive  with  the  least  friction,  it  is  kept  in  the 
state  of  a  paste,  to  which  some  glycerine  is  added  for  the  purpose  of  keeping  it  moist. 
oomDiiM.  4.  Coralline,  or  pseonine,  a  scarlet  dye  material,  is  formed,  according  to 
Kolbe  and  R.  Schmidt,  by  heating  a  mixture  of  carbolic,  oxalic,  and  sulphuric  adds 
until  the  colour  has  been  suffidently  developed.  When  the  reaction  is  finished  the 
mass  is  washed  with  boiling  water  for  the  purpose  of  eliminating  the  excess  of  add. 
The  residue  is  next  dried,  pulverised,  and  submitted  at  150''  to  the  action  of  ammonia. 

The  relation  existing  between  the  rosolic  acid,  discovered  in  tar  by  Kunge,  and 
coralline  is  at  present  not  folly  established,  but  according  to  Oaro's  researches  these 
substances  are  identical.  Bosolic  add  may  be  formed  from  carbolic  and  cresylio 
acids  (as  rosamline  is  from  aniline  and  toluidine)    accordiug   to   the  following 

farmulte  :— 

C6H60+2C7H80=CaoHx603+3Ha. 

•^  t  — '     '*— 1 — '     * — I — — ' 

Carbolic     Cresylio       Bosolic 

add.         aoid.  add. 

AnUiM.  5.  Azuline  (phenyl  blue).  When  coralline  is  heated  with  aniline  oil  (com- 
xnerdal  aniline)  there  is  obtained,  according  to  J.  Persoz  and  Guinon-Mamas,  a  blue 
pigment,  which  is  termed  azuline,  or  azurine. 

^***^SiiSS2i.'"*"  ^*  ^^^  ^®^  attempted  to  prepare  pigments  directly  from  nitro- 
benzoL  Laurent  and  Casthelaz  state  that  a  red  pigment  is  obtained  by  keeping  a 
mixture  of  12  parts  of  nitro-benzol,  24  parts  of  iron-filings,  and  6  parts  of  hydrochloric 
add  for  twenty-four  hours  at  the  ordinary  temperature  of  the  air.  There  is  formed 
a  solid  resinous-like  mass,  which  is  first  exhausted  with  water  and  the  solution 
predpitated  with  common  salt.  The  pigment  thus  obtained  is  said  to  be  a  substitute 
for  fuchsin,  and  as  such  capable  of  being  used  as  a  dye  and  for  calico-printing. 

m.  Naphthaline  Pigments, 

Na^bttuJiiM.  This  material,  CxoHs,  was  discovered  in  the  year  1820  by  Garden  in 
coal-tax,  and  was  afterwards  the  subject  of  researches  by  Faraday,  A.  W.  Hofinann, 
M.  Ballo,  and  others.  According  to  Berthelot  it  may  be  synthetically  prepared  by 
substituting  for  2  atoms  of  hydrogen  of  the  benzol  2  atoms  of  acetylen  (O3H2) : — 

C6H6-2H+2CaHg-fC6H4(CaHg)a=C,oH8. 

Benzol.  Acetylen.  Naphthalint. 


58«  CHSMIOAL  TECHNOLOOY. 

Naphthftline  is  a  cr3r8talline  snbstance,  eshibiting  rliomboida  when  in  Teiy  iinn 
scales.  Its  odour  is  peculiar  and  somewhat  smiilar  to  that  of  storax ;  it  has  a  binxiig 
taste.  When  cooled,  after  having  been  fased,  it  appears  as  a  white  crystalline  mass 
having  a  sp.  gr.  =  1*151.  It  fuses  between  79"*  and  8o^  and  boils  between  216*  and 
2i8^  When  treated  with  nitric  acid,  naphthaline  yields  phthalic  acid,  which  aooovd- 
ing  to  circumstances  and  by  elimination  of  carbonic  add  may  be  either  oanverted 
into  benzol  or  into  benzoic  add  :* — 

a.  C8H604-2C0,=C6H6. 

^-  -t    '"  " — I — ' 

Phthalic  add.  BenzoL 

p.  C8H604-COa=C7H60a. 

T 

Phthalic  add. 

There  exists  between  the  derivatives  of  benzol  and  naphthaline  a  great  analogf , 
which  not  only  extends  to  the  compodtion  and  reaction,  but  even  to  chemicai  ud 
phydcal  properties.  The  analogy  of  composition  is  exhibited  by  the  following 
tabulated  form : — 

Benzol  (hydride  of  phenyl),  CeHfi.  Naphthaline  (hydride  of  naphthyl),  C10H8. 

Nitro-benzol,  C6H5(NOa).  Nitro-naphthaJine,  doHyCNOa). 

Aniline,  CeHyN.  Naphthylamine,  C10H9N. 

Eosaniline,  GaoHigNg.  Base  of  the  naphthaline  red,  CsoHuN^. 

Naphthylamine,  GiJB.q'S^,  the  base  which  corresponds  to  aniline,  is  prepared  finon 
naphthaline  in  exactly  the  same  manner  as  aniline  is  prepared  from  benzol,  by  oom- 
verting  naphthaline  by  the  aid  of  nitro-sulphuric  acid  into  nitro-napththaline,  idiicli 
is  next  converted  into  napthylamine  by  B6champ's  process  (see  p.  574).  As  proved 
by  M.  Ballo  (1870)  the  naphthylamine  may  be  readily  eliminated  from  the  reduced 
mass,  treated  with  iron  and  acetic  acid,  by  distilling  it  with  the  aid  of  steajn. 
Naphthylamine  crystallises  in  white  adcular  crystals,  fuses  at  50°,  and  boils  at 
about  300°.    Its  taste  is  sharp  and'bitter.    It  is  almost  insoluble  in  water. 

Naphthylamine  serves  for  the  preparation  of  the  following  dyes: — 

1.  Martins  yellow,  3.  Naphthaline  violet, 

2.  Magdala  red,  4.  Naphthaline  blue. 

HarttuTdiow.  X.  This  pigment,  better  known  in  England  as  Manchester  yellow,  or 
naphthaline  yellow,  Jaune  cTor,  is  the  calcium  or  sodium  compound  of  binitro-naph- 
thalinic  add  (GioH6(N02)aO),  obtained  by  adding  to  a  solution  of  hydrochloiate  of 
naphthylamine  nitrite  of  soda  until  all  the  napththylamine  has  been  converted  into 
diazonaphthoL    The  fluid  which  contains  diazonaphthol  is  next  mixed  with  ziitzie 

*  The  large  quantity  of  benzdo  add  now  consumed  in  the  preparation  of  some  of  the 
tar  colouTB,  and  employed  for  other  chemico-teohnical  purposes,  is  no  longer  obtained 
from  the  benzoin  resin  (gum  benzoin,  as  it  is  often  termed) ;  but  this  add  is  prepared 
either  from  hippurio  acid  present  in  the  urine  of  horses,  or  it  is  a  derivativa  from 
naphthaline.  The  naphthaline-benzoic  add  may  be  prepared  by  two  difierent  methods^ 
viz. : — I.  By  converting  naphthaline  into  phthiJic  acid,  and  converting  this  add,  by 
heating  it  with  lime,  into  benzoate  of  lime,  from  which,  by  the  addition  of  hj^droehlona 
add,  the  benzoic  acid  is  set  free  and  precipitated.  2.  By  converting  phthahc  add  into 
phthalimide.CeH^NOa,  and  converting  this  substance  by  diBtilling  it  with  lime  into  benzo- 
nitrile,  C7H5N,  the  latter  by  boiling  with  caustic  soda  solution  being  oonverted  into 
benzoate  of  soda,  from  which  solution  the  benzoic  add  is  set  free  and  predpitated  by  the 
addition  of  hydrochloric  add.  In  the  year  1868  Merz  obtained  from  cyannaphthyl  a  new 
acid,  to  which  the  name  of  naphtoe  add  is  given  (formula  GnHsOa),  a  substitate  tat 
benzoic  add. 


DYEING.  583 

Boid  and  then  heated  to  the  boiling  point,  the  binitro-naphthylic  acid  is  thrown  down 
in  yellow  acicular  crystals.  The  conversion  of  naphthylamine  into  binitro^naphthylic 
add  (binitro-naphthol)  may  be  elucidated  by  the  following  formul® : — 

a.  CipHgN+HN0a=2Hg0+CioH6Na. 
Naphthylamine.  DiazonaphthoL 

p.  CioH6Na+2HN03=2N+HaO+CxoH6(NOa)aO. 
DiazonaphthoL  Binitro-naphthylic  aoid. 

As  proved  by  M.  Ballo,  the  latter  acid  may  be  directly  formed  by  the  action  of 
nitric  acid  upon  naphthylamine.  Manchester  yellow  imparts  directly  to  wool  and 
silk,  without  the  intervention  of  any  mordant,  yellow  hues,  which  may  be  made 
to  differ  in  depth  of  colour  from  lemon-yellow  to  deep  golden-yellow,  i  kilo,  of  the 
dry  calcium  or  sodium  compound  dyes  200  kilos,  of  wool  brilliantly  yellow.  While 
picric  acid  dye  is  volatilised  by  steam,  the  Manchester  yellow  perfectly  admits  of  the 
operation  of  steaming.  In  this  country  this  dye  material  is  frequently  employed 
for  the  purpose  of  modifying  the  hue  of  magenta. 

MH^aiM  JEML  2.  This  pigment,  naphthaline  red,  C30H3XN3,  was  discovered  in  1867 
by  Von  Schiendl  at  Vienna,  and  has  been  the  subject  of  researches  by  Durand, 
Gh.  Kestiier,  Dr.  A.  W.  Hofinann,  and  others.  It  is  generated  from  naphthylamine 
by  the  elimination  of  3  molecules  of  hydrogen  from  3  molecules  of  the  base : — 

3CxoH9N-3Ha=C3oHaiN3. 

• , '  ' ; 

Naphthylamiue.         Magdala  red. 

On  the  large  scale  fhe  preparation  of  Magdala  red  is  effected  in  two'  stages.  In 
the  first  the  naphthylamine  is  converted  into  azodinaphthyl-diamine  by  the  action  of 
nitrous  acid: — 

a.  2CioH9N-fHNO«=2HaO+C«>Hi5N3. 

Naphthylamine.      Azodinaphthyl-diamine. 

In  the  second  stage  the  azodinaphthyl-diamine  is  treated  with  naphthylamine,  the 
result  being  the  formation  of  Magdala  red. 

/3.  CaoHi5N3+CioH9N  =  C«>HmN3+NH3, 

Azodi-      Naphthyl-     Magdala 
naphthyl-diamine.  amine.  red. 

The  Magdala  red  of  commerce,  a  black-brown,  somewhat  crystalline  powder,  is  the 
chloride  of  a  base  of  the  composition  described.  As  regards  tinctorial  powder  Mag- 
dala red  is  not  less  valuable  than  fuchsin,  while  it  surpasses  the  latter  in  being  a 
Tcry  £Buat  colour.  When  treated  with  iodide  of  methyl  and  iodide  of  ethyl,  naphtha- 
line red  yields  violet  and  blue-coloured  derivatives. 

'J|g^J^^£^  3  ^^^  4*  Violet  and  blue  naphthaline  pigments  may  be  prepared 
in  various  ways ;  for  instance,  by  phenyUsing  naphthylising,  methylising,  or 
ethylising  Magdala  red;  also  by  treating  naphthylamine  with  mercuric  nitrate 
(Wilder),  by  substituting  for  hydrogen  in  aniline  and  toluidine  the  radical  naphthyl, 
OxoH^.  J.  Wolff,  as  early  as  1867,  obtained  a  very  brilUant  naphthyl  blue  in 
this  manner ;  again,  from  rosamline  and  mono-bromnaphthaline,  and  from  rosaniline 
and  naphthylamine  (M.  Ballo).  Very  recently  Blumer-Zweifel  as  well  as  Kiel- 
meyer  have  produced  naphthylamine  violet  on  cotton  and  linen  fiAbrics,  by  treating 


584  CHEMICAL  TE0HN0L0G7. 

naphthylamine  while  present  on  the  woven  tissues  with  chloride  of  copper,  dilonte 
of  potash,  and,  in  fact,  all  such  reagents  as  may  be  employed  for  the  prodnctkni  of 
aniline  black*  (see  p.  579). 

rV.  Anthracen  Pigments, 
Antiineen  Pigments.  Anthracen  (para-naphthaline,  photen),  C14HX0,  is  present  in  cotl- 
tar  to  an  amount  of  075  to  1*0  per  cent,  and  was  discoyered  by  J.  Dumas  in  1831. 
while  in  1869  it  was  first  employed  by  Graebe  and  Liebermann  for  the  purpoie 
of  obtaining  anthracen  red  or  artificial  alizarin.  Anthracen  occurs  in  that  portion 
of  the  products  of  the  distillation  of  coal-tar  which  being  rather  thick  are  knowi 
in  this  country  by  the  designation  of  green  grease,  and,  as  such,  used  as  1 
coarse  lubricating  material.  The  green  grease  consists  of  heav}-  oils,  some 
naphthaline,  and  about  20  per  cent  of  anthracen.  By  means  of  the  hydzxh 
extractor,  and  by  submitting  the  raw  material  to  strong  pressure,  crude  (oon- 
taining  60  per  cent  pure)  anthracen  is  obtained.  This  raw  material  is  purified  by 
being  treated  with  benzoline  (petroleum  spirit),  aided  by  heat,  and  again  aided 
by  the  centrifugal  machine,  fusion,  and  sublimation,  these  operations  resulting  at  last 
in  the  production  of  pure  anthracen.  This  substance  then  appears  as  small  foliated 
crystals,  white,  void  of  odour,  fusing  at  215°,  and  subliming  at  a  higher  tempentura 
without  de^mposition.  This  body  is  sparingly  soluble  in  alcohol  and  benzol,  more 
readily  in  sulphide  of  carbon.  With  picric  acid  it  yields  a  compound  exhibiting  ruby- 
red  crystals;  while  under  the  influence  of  oxidising  agents  it  is  converted  into 
anthrachinon  (oxanthracen,  oxyphoten),  C14H8O2,  which  in  its  turn  is  converted  into 
alizarine,  C14H8O4,  by  a  circuitous  process. 

According  to  the  original  method  of  preparing  alizarine,  the  anthrachiwBi, 
O14H8O2,  obtained  firom  anthracen  by  the  action  of  oxidising  agents,  sach  aa  nitric 
add,  was  first  converted  into  bibromide  of  anthrachinon,  Gz4H6Br202,  by  treating 
anthrachinon  with  bromine,  and  this  bromated  compound  was  further  treated  either 
with  caustic  potash  or  caustic  soda  at  a  temperature  of  180''  to  200%  the  bibromide  of 
anthrachinon  becoming  converted  into  alizarine  potassium  (or  alizarine  sodium, 
if  caustic  soda  has  been  used),  from  which  the  alizarine  is  set  free  by  the  addition  of 
hydrochloric  acid : — 

a.  Ci4H6Bra02+KOH  =  Ci4H6K204+2BrK+2H20. 

Bibromide  of  Alizarine 

Anthrachinon.  Potassium. 

p.  C14H6K2O4+2CIH  =  C14H8O4+2CIK 

Alizarine  Alizarine. 

Potassium. 

Alizarine  is  now  prepared  from  anthrachinon  by  treatment  at  a  temperatmne  of 
260°  with  concentrated  sulphuric  acid  of  1*84  sp.  gr.,  the  anthrachinon  being 
converted  into  a  sulpho-acid ;  this  acid  is  next  neutralised  with  carbonate  of  lime,  the 
fluid  decanted  from  the  deposited  gypsxmi,  and  carbonate  of  potash  added  to  it  for  the 

*  It  is  evident  that  by  combining  suitable  aniline,  naphthyl,  and  cetyl  compounds,  the 
greatest  variety  of  blue  and  violet  pigments  may  be  prepared.  The  following  Una 
pigments  were  obtained  in  the  summer  of  1867,  these  repearohes  being  undertaken  in  eoo- 
sequence  qf  the  results  obtained  by  J.  Worn  in  the  same  direction,  x.  Fuchsin  and 
bromide  of  naphthyl.  2.  Fuohsin  and  oetyl  bromide.  3.  Naphthylamine,  fnchran,  and 
aniline  oiL  4.  Cetylamine,  fuohsin,  and  aniline  oil.  5.  Naphthylamine,  fuch8in«  and 
oetylamine.    6.  Cetylamine,  fuohsin,  and  naphthylanune. 


DYEING.  585 

purpose  of  precipitating  all  the  lime.  The  clear  liquid  is  then  evaporated  to 
dryness,  the  resulting  saline  mass  is  converted  into  alizarine-potassium  hy  heating  it 
with  caustic  potash.  From  the  alizarine-potassium  thus  obtained  the  alizarine  is  set 
free  by  the  aid  of  hydrochloric  acid.  According  to  another  method,  the  preparation 
of  anthrachinon  is  avoided,  and  anthracen  employed  directly,  by  first  converting  it-* 
by  the  aid  of  sulphuric  acid  and  the  application  of  heat — into  anthracen  sulpho- 
acid,  CS8HZ8SH4O3.  After  having  been  diluted  with  water,  the  solution  of  this  acid 
is  treated  with  oxidising  agents  (peroxides  of  manganese,  lead,  chromic  acid,  nitrio 
acid),  and  the  acid  fluid  is  next  neutralised  with  carbonate  of  lime.  When  peroxide 
of  manganese  has  been  used  the  manganese  is  also  precipitated  as  oxide.  The 
oxidised  sulpho-acid  having  been  previously  converted  into  a  potassium  salt,  the 
latter  is  heated  with  caustic  potash,  alizarine-potassium  being  obtained. 

There  is  no  doubt  that  anthracen  may  be  converted  into  alizarine  by  other  means  ; 
and  it  is  very  likely  that  from  other  hydrocarbons  (benzol,  toluol,  naphthalin)  present 
in  coal-tar,  anthracen  and  antliracen  red  may  be  obtained. 

The  industrial  manufacture  of  artificial  alizarine,  carried  on  in  the  first  place  by 
the  inventors  of  this  process — Graebe  and  Liebermann ;  and  taken  up  by  J.  Gessert, 
at  Elberfeld ;  Bronner  and  Gutzkow,  at  Frankfort-on-Maine ;  Briining,  at  Hochst 
(near  Wiesbaden) ;  Greiff,  at  Cologne ;  and  by  Perkin,  in  London — is  one  of  the 
brightest  pages  in  the  history  of  chemical  technology.  Although  for  the  present 
anthracen  red  cannot  compete  with  madder,  it  will,  in  all  probability,  become  in 
a  very  great  measure  a  substitute  for  that  dye-stu£f  and  garandne. 

V.  Pigments  from  Cfinchonine, 

ofcadionia^  pigmmitt.  The  preparation  of  pigments  from  cinchonine — an  almost  waste 
by-product  of  the  manufacture  of  quinine  on  the  large  scale — may  be  conveniently 
considered  as  an  appendix  to  the  coal-tar  colours.  Cinchonine  is  submitted  to 
distillation  with  hydrate  of  soda  in  excess,  the  resulting  product  being  about 
65  per  cent  crude  chinoline  (chinoline  oil),  a  mixture  of  the  three  following  homo- 
logous bases : — 

Chinoline    C^H^N. 

Lepidine      • CzqHqN. 

Kryptidine  or  dispoline     CzxHuN. 

Lepidine  is  the  chief  constituent  of  this  mixture. 

When  chinoline  oil  is  heated  with  iodide  of  amyl  the  result  is  the  formation 
of  amyl-lepidin-iodide,  which  on  being  treated  with  caustic  soda  solution,  yields  a 
very  brilliant  blue  pigment — cyanine,  lepidine  blue,  or  chinoline  blue,  C3oH39NaI.  This 
substance  is  a  crystalline  compound,  exhibiting  a  metallic  green  gloss  and  golden 
yellow  hue  ;  it  is  difficultly  soluble  in  water,  readily  in  alcohol  The  formation  of 
cyanine  may  be  elucidated  by  the  following  formula : — 

a.  CxoHgN+CjH,,!  =  CxsH^oNI. 

Lepidine.    Iodide  of  Amyl-lepidin- 
AmyL  iodide. 

P,  2Cx5HaoNI+NaOH  =  CjoHagNal+Cal+HaO. 


Am^l-lepidin-  Cyanine. 

iodide. 


2  X 


586  CHEMICAL  TECHNOLOGY. 

Red  Pigments  occurring  in  PUmU  and  Animals. 

^*^  ^JdJerV***^      Madder  is  the  root  of  the  Bubia  tinctorum,  a  perennial  plnl 
cultivated  in  Sonthern,  Central,  and  Western  Europe ;  while  in  the  Lerant  die 
M,  peregrina,  and  in  the  East  Indies    and    Japan  the   R.   mungista   (miingMi>, 
are  partly  cultivated,  partly  met  with  in  the  wild  state.     According  to  the  resesrdMi 
made  in  England,  the  dye  imported  under  the  name  of  mungeet  from  Inditii 
not  the  root,  hut  the  reedy  stem  of  a  species  of  Ruhia,  and  as  a  dye  it  is  inferior.  IIk 
native  country  of  the  madder  plant  is  the  Caucasus.    All  these  plants  are  peremiiil 
The  root  varies  in  length  from  lo  to  25  centims. ;  it  is  not  much  gnarlelnd^ 
gen'erally  a  little  thicker  than  the  quill  of  a  pen.    Externally  the  root  is  covered  with 
a  hrown  hark ;  internally  it  exhihits  a  yellow-red  colour.    Madder  is  met  with  io  the 
trade  in  the  root   (technically  racine  if  European),  and  in  i>owder  exhibithig  1 
red-yellow  colour,  and  possessing  a  peculiar  odour.    Avignon  madder,  however,  his 
hardly  any  smell  at  all ;  but  the  odour  is  particularly  marked  in  Zee]and.or  so-caOf' 
Holland,  madder.    The  powdered  madder  is  always  kept  in  strong  oaken  casks,  10 
as  to  exclude  air  and  light.     The  best  kind  of  madder  is  that  grown  in  tbe 
Levant  (Smyrna  and  Cyprus),  and  met  with  in  the  trade  under  the  name  of  littaifK 
alizariy  in  roots  which  are  usually  rather  thicker  than  the  roots  of  the  £iirope» 
varieties,  owing  partly  to  the  fact  tliat  the  Levant  madder  is  generally  of  four  to  fin 
years*  growth,  while  in  Europe  the  roots  are  of  two  to  three  years*  growth  only- 
Dutch  madder,  chiefly  grown  in  tlie  province  of  Zeeland,  is  met  with  deoortictW 
(rohS),  the  outer  bark  and  sometimes  tlie  splint  bark  having  been  removed.  The  wdl 
dried  roots  are  broken  up.  by  means  of  wooden  stampers  moved  by  madunerf*  <• 
reduce  the  bark  and  splint  bark  to  powder,  while  tlie  very  hard  internal  portion « 
the  root  is  left  untouched,  this  being  separated  from  the  powder  by  means  of  sieves. 
The  powder  is  put  into  casks  and  termed  heroofde.    During  the  last  ten  or  tvel^* 
years,  the  old  madder  sheds  (meestoven)  in  Zeeland  have  been  superseded  by  Uige 
manufactories,  in  which  the  madder  root  is  treated  as  it  is  in  the  Vanclnse  (FraBCi^ 
and  ground  up  entirely,  so  that  the  former  distinct  qualities  of  madder  are  no  longv 
met  with.    When  the  whole  root  is  pulverised  the  madder  is  termed  onberoo/dt,  ntf 
rohi.     Besides  the  Dutch  madder,  tliat   from   Alsace    and   from    the  Vandosc- 
Avignon,  occur  very  largely  in  the  trade.     What  is  known  as  mull  madder  if  ^ 
refuse  and  dust  from  the  floors  of  tlie  works,  and  is  tlie  worst  quality.    In  addition  to 
colouring  matter,  madder  contains  a  large  quantity  of  sugar,  of  which  W.  Stein  (18^) 
found  as  much  as  8  per  oent.     Wlule  it  was  formerly  considered  that  wMdAff 
contained  no  less  than  five  different  colouring  substances,  it  appears  from  reeot 
researches  that  this  root  in  fresh  state  only  contains  two  pigments,  viz.  row- 
lythrinic  acid  (formerly  termed  xanthin),  and  purpurine.  According  to  Dr.  Rochleto* 
the  former  of  tliese  is  converted  under  the  influence  of  a  peculiar  nitrogen^ 
substance  present  in  the  madder  root  into  alizarine — the  essential  colouring  xnatUr  a 
madder — and  into  sugar : — 

CaoHaaOfi  =  Ci4H804-!-C6Hia06+HaO, 

Bui  erythrinio    Alizarine.        Sugar, 
acid. 

According  to  the  researches  of  Graebe  and  Liebermann,  alizarine  is  a  deriviti^ 

from  anthracen,  C14HX0,  the  formula  of  the  former  being  CX4H8O4.    As  already  0^' 

tioned  (see  p.  585),  Graebe  and  Liebermann  have  succeeded  in  converting  anthi*^ 


DYEING.  587 

into  alizarine  (1869).  Alizarine  is  yellow,  bnt  becomes  red  under  the  influence  of 
alkalies  and  alkaline  earths.  Madder  contains  a  red  pigment,  pnrpnxine,  or 
ra'biacine,  C14H8O3,  which  by  itself,  as  well  as  in  combination  with  alizarine,  yields 
a  g^ood  dye. 

MAddcrLska.  Wc  Understand  by  this  term  a  combination  of  alizarine  and  pnrpnrine 
(the  colouring  matter  of  madder)  with  basic  alumina  salts.  Madder  lake  is  prepared 
\>y  first  washing  madder  with  water,  distilled  or  at  least  free  from  lime  salts, 
and  next  exhausting  the  dye-stuff  with  a  solution  of  alum,  the  liquor  thus  obtained 
"being  precipitated  with  carbonate  of  soda  or  borax.  The  bulky  precipitate  having 
been  collected  on  a  filter  is  thoroughly  washed  and  dried. 

FiowMB  of  Madder.  The  preparation  made  from  madder  on  the  large  scale  and  kncuini 
in  the  trade  as  flowers  of  madder  (^fleur  de  garance),  is  obtained  from  the  pulverised 
madder  by  steeping  it  in  water,  inducing  fermentation  of  the  sugar  contained  in  it, 
and  next  thoroughly  washing  the  residue,  first  with  warm,  next  with  cold  water.  The 
residue  after  subjection  to  hydraulic  pressure  to  remove  the  water,  is  dried  at  a  gentle 
beat,  and  having  been  pulverised  again  is  used  in  the  same  manner  as  madder  for 
dyeing  purposes.  The  operation  of  dyeing  with  the  flowers  of  madder  requires  a 
less  elevated  temperature  of  the  contents  of  the  dye-beck.  It  would  appear  that  by 
the  preparation  of  the  flowers  of  madder  the  pectine  substances  of  the  root  are 
eliminated  which  otherwise  become  insoluble  during  the  operation  of  dyeing. 

Ante.  When  flowers  of  madder  are  treated  with  boiUng  methylic  alcohol  (wood- 
spirit),  the  solution  obtained  filtered,  and  water  added  to  the  filtrate,  a  copious  yellow 
precipitate  is  obtained,  which  having  been  washed  with  water  and  dried  constitutes 
the  material  known  as  azale  (from  azala^  Arabian  for  madder),  which  has  been 
suggested  for  use  as  a  dye  material  in  France.  Probably  this  substance  is  crude 
alizarine ;  as  obtained  from  madder  or  garancine  it  is  met  with  in  the  trade  sometimes 
under  the  name  of  Pincoffine,  having  been  first  discovered  and  prepared  by  Mr. 
Pincofis,  at  Manchester. 

<i*ninrin*.  This  preparation  of  madder  contains  the  colouring  principles  of  the  root 
in  a  more  concentrated,  pure,  and  more  readily  exhaustible  state.  In  order  to 
prepare  garancine,  madder  (generally  this  term  is  given  to  the  pulverised  root)  is 
first  moistened  uniformly  with  water,  and  next  there  is  added  i  part  of  sulphuiio 
acid  diluted  with  i  part  of  water.  This  mixture  is  heated  by  means  of  steam 
to  about  100^  for  one  hour,  and  the  magma  then  thoroughly  washed  with  water 
for  the  purpose  of  eliminating  all  the  acid.  This  having  been  done  the  garancine 
is  submitted  to  hydraulic  pressure  for  the  purpose  of  getting  rid  of  the  greater  part 
of  the  water,  after  which  the  material  is  dried  and  lastly  ground  to  a  very  fine 
powder.  By  the  action  of  the  sulphuric  acid,  some  of  the  substances  contained 
in  madder  and  more  or  less  interfering  with  its  application  as  a  dye,  are  eliminated 
by  the  washing  of  the  garancine,  while  the  colouring  matter  remains  mixed  with  the 
partly  carbonised  organic  substances.  As  regards  its  tinctorial  value  i  part  of 
garancine  may  be  taken  as  equal  to  3  to  4  parts  of  madder.  As  madder  when 
employed  in  dyeing  does  not  become  quite  exhausted,  the  fluids  of  the  dye-beck  a^e 
QMHMeu.  strained  from  tlie  solid  residue,  and  this  is  treated  with  half  of  its  weight 
of  sulphuric  acid.  The  mass  is  next  treated  as  has  been  described  under  Grarancine, 
and  constitutes  after  drying  what  is  known  as  garanceux,  being  used  generally  for  the 
production  of  what  are  termed  9ad  colours  (black,  deep  brown,  lilac).  As  a  matter  of 
course  garanceux  is  of  less  tinctorial  value  than  garancine. 


588  CHEMICAL  TECHNOLOOY. 

{yooonB.  The  sobBtance  met  with  in  commerce  nnder  the  name  of  oolorine  s  As 
dry  alcoholic  extract  of  garancine,  and  consists  essentially  of  alizarine,  parparaK, 
fatty  matter,  and  other  substances  soluble  in  alcohol  present  in  garancine.  £.  Esff 
commenced  some  years  since  to  exhaust  madder  with  an  aqueous  solntin  of 
sulphurous  acid,  thereby  obtaining  the  pigments  of  madder  in  a  (for  teehnieal  per- 
poses)  pure  condition.  These  preparations,  which  are  already  extensiTefy  used,  m 
distinguished  as: — ^Green  alizarine  {Alizarins  verte),  which  from  Alsace  maddv 
is  ohtained  to  an  amount  of  about  3  per  cent,  containing  with  the  alizarine  a  gns 
resinous  material ;  yellow  alizarine  {Alizarins  jauns),  the  former  substance  wi&ool 
the  resinous  material,  this  having  been  eliminated  by  suitable  solvents,  as  pnipozatt 
ami  flowers  of  madder.  The  tinctorial  value  of  purpurine  amounts  to  10  times,  aoi 
that  of  the  green  and  yellow  alizarine  to  32  to  36  times,  that  of  madder,  MaH^jy  «[ 
good  quality  yields  on  the  large  scale : — 

Purpurine     ••    •••      1*15  per  cent. 

Green  alizarine    2*50 

Yellow  alizarine   ...      0*32 

Flowers  of  madder      3900 


BmnoarGunwood.      By  this  name  are  designated  several  varieties  of  wood  belongiiif 

to  the  Casalpinia,  and  used  for  dyeing  purposes.     The  best  kind  is  the  so-eaiki 

Pemambuco  or  Femambuco  wood,  obtained  from  the  Gasalpinia  brasilienns  <•  erisia; 

externally  it  is  yellow-brown,  internally  its  colour  is  a  bright  red,  while  the  wood 

is  heavy  and  rather  hard.    Its  name  is  derived  from  that  of  the  state  of  the  Brazihia 

Empire,  in  which  the  tree  grows  abundantly.    It  is  met  with  in  oonuneroe  in  6ta^ 

and  large  logs.     The  sapan  wood  obtained  from  Japan,  and  derived  from  tlb* 

{€.  sapan)  is  an  inferior  kind,  while  the  varieties  known  as  Lima  or  Nicaragua  wood. 

or  Bois  ds  8ts.  Marthe  (O.  echinata),  and  the  brasilet  wood  {C.  vesioaria),  are  aUcf 

less  value.     All  these  kinds  of  wood  contain  a  colouring  matter  termed  brariliMh 

(according  to  Bolley  the  formula  is  C44H4oOx44-3HaO),  a  colourless  snbstanee, 

crystallising  in  small  acicular  crystals,  the  aqueous  solution  of  which  turns  gndmiBj 

cannine-red  by  exposure  to  air,  a  change  brought  on  almost  instantaneously  either 

by  boiling  the  solution  or  by  the  action  of  alkalies.    Brazil  wood  is  used  hk  dyeiag 

for  the  production  of  a  beautiful  red  colour,  which  is  not  fast.  This  wood  is  also  used 

for  the  preparation  of  round  lac,  for  which  puipose,  however,  the  red  and  violet  Ur- 

colours  are  now  more  often  employed.    Bed  ink  is  commonly  made  with  brazfl 

according  to  the  following  recipe : — ^Brazil  wood,  250  grms. ;  alum,  30  gnns. ; 

of  tartar,  30  grms. ;  water,  2  litres.    Boil  down  to  i  litre,  strain  the  liquid,  and.  next 

add  of  gum  arabic  and  sugar  candy  each  30  grms.    A  better  red  ink  is  obtained  hf 

dissolving  2  decigrammes  (4  grains)  of  carmine  in  18*27  g^^i^^-  (5  drms.)  of  hqidd 

ammonia,  and  adding  a  solution  of  i  grm.  (18  grains)  of  gum  arabic  in  2  fluid  oimea 

of  water.    Red  inks  are  now  frequently  prepared  from  solutions  of  fuchsin  to  which 

some  gum  and  almn  are  added,  or  by  dissolving  commercial  aurine,  a  modificatkn 

of  rosolic  add,  in  a  solution  of  carbonate  of  soda. 

Sandalwood.  There  is  a  red  and  a  yellow  variety  of  this  wood  in  commerce.  Ths 
red  wood  is  derived  from  Pterocarpm  santalinus,  a  tree  growing  in  Ceylon  and  otiier 
parts  of  India.  The  wood  is  imported  in  logs  exhibiting  a  straight  fibrous  texture, 
and  externally  a  deep  red,  internally  a  bright  red.  The  colouring  matter  contained 
in  this  wood  is  of  a  resinous  nature  and  is  named  santaiiae.    According  to  ^ 


DYEING.  589 

researohee  of  H.  Weidel  (1869),  sandal  wood  contains  a  colourless  body,  santal, 
C8S603»  which  appears  to  be  converted  by  oxidation  into  santaline.  Sandal  wood  is 
used  for  the  preparation  of  coloured  lakes,  coloured  fumiture  polish,  for  dyeing  wool 
'bro'wn,  dyeing  leather  red,  as  a  pigment  in  tooth  powders,  Ac.  The  same  pigment  is 
found  in  barwood,  derived  from  Bapkia  nitidaf  an  African  tree ;  this  wood  is  said  to 
eontain  no  less  than  23  per  cent  of  santaline,  while  sandal  wood  only  contains 
x6  per  cent  of  this  substance. 

Bmffloww.      The  drug  to  which  this  name  is  given  consists  of  the  dried  petals  of  the 

fLowears  of  the  Oarthamus  tinetoriusy  a  thistle-like  plant  belonging  to  the  feunily  of  the 

Synantherea^  a  native  of  India,  and  cultivated  in  Egjrpt,  the  southern  parts  of 

'  Xlnrope,  and  also  to  some  extent  in  parts  of  Germany.    Safflower  contains  &  red 

matter,  carthamine,  insoluble  in  water,  and  also  a  yellow  substance  soluble  in 

that  liquid.    The  quality  of  this  drug  is  better  according  to  its  greater  purity  from 

mechanical  admixtures,  such  as  seeds,  leaves  of  the  plant  Carthamine,  CX4H16O7,  or 

Hauge  vigitdl,  is  prepared  in  the  following  manner : — ^The  safflower  is  exhausted 

"With  a  veiy  weak  solution  of  carbonate  of  soda,  and  in  this  fluid  strips  of  cotton- 

'wool  are  dipped,  after  which  the  strips  are  immersed  in  vinegar  or  veiy  dilute 

sulphuric  acid  for  the  purpose  of  neutralising  the  alkali.    The  red-dyed  cotton  strips 

are  next  washed  in  a  weak  solution  of  carbonate  of  soda,  and  the  solution  thus 

obtained  is  precipitated  with  an  acid ;  the  carthamine  thrown  down  is  first  carefully 

'washed,  and  next  placed  on  porcelain  plates  for  the  purpose  of  becoming  dry. 

Carthamine  when  seen  in  thin  films  exhibits  a  gold-green  hue,  while  when  seen 

against  the  light  the  colour  is  red.    When  carthamine  has  been  repeatedly  dissolved 

and  precipitated  it  is  termed  safflower-carmine.     Mixed  with  French  chalk  (a 

silicate  of  magnesia),  carthamine  is  used  as  a  face  powder.    Safflower  is  used  for 

dyeing  silk,  but  the  red  colour  imparted  is,  although  brilliant,  very  fugitive. 

<irwiMnnh,oro<whinMi.      This  substaucc  is  the  female  insect  of  the  Oocotu  oaeti,  found  on 
eeveral  species  of  cacti,  more  especially  on  the  Nopal  plant  and  the  Cactus  opuntia. 
This  insect  and  the  plants  it  feeds  on  are  purposely  cultivated  in  Mexico,  Central 
America,  Java,  Algeria,  the  Cape,  Ac.     The  male  insect,  of  no  value  as  a  dye 
material,  is  winged,  the  female  wingless.    The  female  insects  are  collected  twice 
a  year  after  they  have  been  fecundated  and  have  laid  eggs  for  the  reproduction 
of  young,  and  are  killed  either  by  the  aid  of  the  vapours  of  boiling  water  or  more 
usually  by  the  heat  of  a  baker's  oven.    Two  varieties  of  cochineal  are  known  in 
commerce,  viz.,  the  fine  cochineal  or  tnestica,  chiefly  gathered  in  the  district  of 
Mestek,  a  province  of  Honduras,  on  the  Nopal  plants  there  cultivated ;  and  the  wild 
cochineal,  gathered  from  cactus  plants  which  grow  in  the  wild  state.    This  latter 
variety  is  of  inferior  quality.    Cochineal  appears  as  small  deep  brown-red  grains,  at 
the  lower  and  somewhat  flattened  side  of  which  the  structure  of  the  insects  is  some- 
what discernible.     Sometimes  the  dried   insect  is  covered  with  a  white  dust, 
but  frequently  the   material  is  met   with   exhibiting  a  glossy  appearance  and 
black  colour.    The  white  dust,  very  frequently  fraudulently  imparted  by  placing  the 
grain  with  French  chalk  or  white-lead  in  a  bag,  is  according  to  the  results  of 
mioTMCOpical  investigation,  the  excrement  of  the  insect,  exhibiting  when  seen  under 
the  microscope  the  shape  of  curved  cylinders  of  very  uniform  diameter  and  a  white 
oobtir.    Cochineal  contains  a  peculiar  kind  of  acid — carminic  acid — ^which,  by  the 
action  of  very  dilute  sulphuric  acid  and  other  reagents,  is  split  up  into  cannine-red 
(cannine) — also  present  in  the  insect,  together  wiUi.the  acid — and  into  dextrose : — 


59S  CHEMICAL  TECffNOLOOY. 

and  commence  stirring  the  flnid  vigorondy  for  the  pnrpose  of  exposing  it  as  mdi 
as  possible  to  the  action  of  the  air.  Daring  this  operation,  continned  for  some  two 
or  three  honrs,  the  colonr  of  the  liquid  gradually  changes  to  pale  green,  and  iha 
indigo  may  then  be  seen  suspended  in  the  liquid  in  very  small  flocks.  The  hqmA  is 
then  left  to  stand,  and  the  suspended  matter  gradually  subsiding,  the  water  is 
gradually  run  off  by  the  aid  of  taps  or  plugs  fitted  into  the  tank  at  diffetoit 
heights.  At  last  the  somewhat  thick,  yet  fluid,  precipitate  of  indigo  is  run  into  a 
cauldron,  where  it  is  boiled  for  about  twenty  minutes  in  order  to  prevent  it  fennentiag 
a  second  time,  for  by  this  second  fermentation  it  would  be  rendered  oseleaB.  Ihe 
magma  is  left  in  the  cauldron  over  night  and  the  boiling  resnmed  next  dMj 
and  then  continued  for  three  to  four  hours,  after  which  the  indigo  is  ran  an  to  laigiB 
filters,  consisting  first  of  a  layer  of  bamboo,  next  mats,  and  on  these  stont  eanTas,  all 
placed  in  a  large  masonry  tank.  Upon  the  canvas  is  left  a  thick,  very  deep  bfaia, 
nearly  black  paste,  which  is  thence  taken  and  put  into  small  wooden  boxes* 
perforated  with  holes  and  lined  with  canvas ;  a  piece  of  canvas  is  put  on  the  tc^  sf 
the  paste,  and  next  a  piece  of  plank  is  fitted  closely  into  the  box.  So  arranged,  a 
number  of  these  are  placed  under  a  screw-press  for  the  purpose  of  eliminating,  by  a 
gradually  increased  pressure,  the  greater  portion  of  the  water,  and  thns  to  solidify  Him 
pasty  material.  On  being  removed  from  these  boxes  the  cakes  of  indigo  are  trans- 
ferred to  the  drying-room,  and  there,  daylight  and  direct  sunlight  being  careliiny 
excluded,  gentiy  dried  by  the  aid,  in  some  cases,  of  artificial  heat.  In  order  to 
prevent  the  cracking  of  the  cakes,  the  dxying  has  to  be  effected  very  gently,  and  lasts 
usually  for  some  four  to  six  days.  The  dried  cakes  of  indigo  are  next  packed  in  stost 
wooden  boxes  and  then  sent  into  the  market.  The  exhausted  plants  are  used  far  a 
manure,  for  although  the  boughs  on  being  planted  in  the  soil  would  again  grow,  they 
would  not  yield  either  in  quality  or  quantity  enough  indigo  to  pay  the  expenses  sf 
culture.  1000  parts  of  fluid  from  the  fermenting  tanks  yield  0*5  to  075  parts  of  indigOL 

pxopertiMofiBdigo.  The  indigo  met  with  in  commerce  exhibits  a  deep  blue  oolonr, 
dull  earthy  fracture,  and  when  rubbed  with  a  hard  substance  (the  better  kinds  of  indigs 
even  when  rubbed  with  the  nail  of  the  thumb),  give  a  glossy  purplish-red  streak.  Li 
addition  to  a  larger  or  smaller  quantity  of  mineral  substances,  indigo  contains  a 
glue-like  substance,  or  indigo  glue ;  a  brown  substimce,  indigo  brown;  a  red  pigment, 
indigo  red;  and  the  indigo  blue,  or  iudigotine,  Ox^HioNtOs,  the  peculiar  dye 
material  for  which  the  drug  is  valued.  The  quantity  of  indigo  blue  contained  in  the 
several  kinds  of  indigo  of  commerce  varies  from  20  to  75  and  80  per  cent,  and 
averages  from  40  to  50  per  cent.  Indigo  may  be  purified  according  to  Dnmas's 
process  by  digestion  in  aniline,  whereby  the  indigo  red  and  indigo  brown  pigments 
dissolved  and  eliminated.  According  to  Dr.  V.  Warther  (see  **  Chemical  Ni 
vol.  xxiii.,  p.  252),  Venetian  turpentine,  boiling  paraffin,  spermaceti,  stearic  acid,  and 
chloroform,  are,  at  high  temperatures,  solvents  for  indigo  blue.  (See  also  "  Chemical 
News,"  vol.  XXV.,  p.  58,  "  On  the  Solubility  of  Indigo  (Indigotine)  in  ]%enic  Acid.*") 

tmUiik  indiKo.  The  quality  of  indigo  is  ascertained  by  its  deep  blue  colonr  and  hf^ 
ness  (see  '*  Chemical  News,"  vol.  xxiv.,  p.  313).  G.  Leuchs  found  that  in  for^-mns 
samples  of  this  material  the  best  contained  60*5  per  cent,  the  worst  24  per  cent  of 
indigotine,  the  specific  gravity  of  the  former  being  low  and  of  the  latter  high.  Indigo 
should  float  on  water,  and  when  of  good  quality  it  should  not,  on  being  broken  to 
pieces,  deposit  at  the  bottom  of  the  vessel  filled  with  water  in  which  it  is  contained 
a  sandy  or  earthy  sediment.    On  being  ignited,  indigo  should  leave  only  a  compara- 


DYEING.  5» 

tively   small  quantity  of  ash.    When  suddenly  heated,  indigo  should  give  off  a 

purplish-coloured  vapour,  suhlimed  indigotine,  and  the  drug  sliould  he  perfectly 

golnble  in  fuming  sulphuric  acid,  yielding  a  deep  hlue  fluid.    That  kind  of  indigo 

which  on  being  rubbed  with  a  hard  body  exhibits  a  reddish  coppeiy  hue  is  termed 

coppery-tinged  indigo,  indigo  cuivre.    In  order  to  test  indigo  more  accurately,  a 

weighed  portion  is  dried  at  ioo°  for  the  purpose  of  ascertaining  the  quantity  of 

hygroscopic  water  contained,   which   should  not  exceed  from  3   to   7  per  cent. 

Next  tlie  dried  indigo  is  ignited  for  the  purpose  of  ascertaining  the  quantity  of  ash  it 

yields.     For  good  qualities  of  the  drug  this  amounts  to  7  to  95  per  cent.    Numerous 

methods  have  been  proposed  by  practical  dyers  as  well  as  by  scientific  men  for  the 

purpose    of   ascertaining  the  value  of  indigo ;  that   is   to  say,    the  quantity  of 

indigotine  it  con^ins.     Some  of  these  processes  are  either  too  tedious,  and  cause 

great  loss  of  time,  or  are  not  sufficiently  exact.    A  commercial  sample  of  indigo  may 

be  treated  first  with  water,  next  with  weak  acids,  then  with  alkaline  solutions  and 

alcohol,  and  the  ash  and  hygroscopic  water  having  been  estimated,  the  residue  of 

the  different  operations  will  be  the  indigotine,  the  process  being  based  upon  the 

insolubility  of  the  latter  in  the  different  solvents  used  for  the  removal  of  the  impuri* 

Ues  met  with  in  the  sample  under  examination.     Mittenzwei  proposes  to  reduce  the 

indigo  by  means  of  an  alkali  and  protosulphate  of  iron,  to  pour  over  the  surfiice  of 

the  liquid  a  layer  of  petroleum  oil  for  the  purpose  of  excluding  air,  to  take  by  the 

aid  of  a  curved  pipette  a  known  bulk  of  the  indigo-containing  fluid,  and  to  introduce 

this  fluid  at  once  into  a  test -jar  placed  over  mercury,  and  containing  a  known  and 

accurately  measured  bulk  of  pure  oxygen.    As  i  grm.  of  white  indigotine  (soluble) 

requires  for  its  conversion  into  blue  (insoluble)  indigotine  45  c.c.  of  oxygen,  the 

quantity  of  gas  absorbed  gives  the  quantity  of  indigotine.    This  method  yields  very 

correct  results,  but  requires  an  experienced  manipulator. 

^*^by  BildncSoo.^*^  Take  5  grms.  of  pure  quick-lime  prepared  from  white  marble  or 
from  well- washed  oyster- shells,  put  the  quick-lime  into  a  porcelain  mortar,  and  mix 
the  lime  with  sufficient  water  to  form  a  thin  milk  of  lime ;  next  take  5  grms.  of  the 
sample  of  indigo  very  finely  powdered,  and  add  it  to  the  milk  of  lime,  mixing 
thoroughly,  and  then  pouring  the  fluid  into  a  flask  capable  of  containing  1200  c.c. 
Rinse  the  mortar  with  water  so  as  to  make  up  a  bulk  of  i  litre,  next  add  to  the 
contents  of  the  flask  10  grms.  of  crystallised  sulphate  of  iron,  and  immediately  after 
cork  the  flask  and  let  it  stand  for  several  hours  in  a  moderately  warm  place  or  on  a 
sand-bath,  taking  care  to  shake  the  vessel  frequently.  After  the  liquid  has  becomo 
cool  and  the  sediment  deposited,  a  small  s3rphon  of  known  cubic  capacity  is  filled 
with  distilled  water,  and  by  the  aid  of  this  instrument  200  c.c.  of  the  fluid  contained 
in  the  flask  are  transferred  to  a  beaker-glass.  Some  pure  hydrochloric  acid  having 
been  added  to  the  fluid,  it  is  left  to  be  acted  upon  by  the  air  until  the  reduced  and 
soluble  indigotine  has  become  insoluble  and  blue-coloured.  The  precipitate  is 
coUected  on  a  tared  filter,  weU  washed,  dried,  and  next  weighed.  This  weight  cor- 
responds to  the  quantity  of  pure  indigo  blue  present  in  i  grm.  of  the  sample. 

I'maj'i  tmi.  This  tcst  is  based  upon  the  application  of  bichromate  of  potash  and 
hydrochloric  acid.  10  parts  of  finely-pulverised  indigo  are  digested  with  twelve  times 
iu  weight  of  faming  sulphuric  acid  at  a  temperature  not  exceeding  25**  for  a  period 
of  twelve  hours.  When  the  indigo  has  been  entirely  dissolved  the  fluid  is  poured 
i^to  I  pint  (=  o'568  litre)  of  water,  next  24gr8.  of  concentrated  hydrocliloric  acid  ana 
Added,  and  the  fluid  is  then  gently  heated,  after  which  it  is  titrated  with  a  solution 

2  Y 


594  CHEMICAL  TECSNOLOQY. 

of  bichromate  <tf  potash  in  water,  this  solution  being  adjied  as  long  as  a  drop  o£  the 
fluid  taken  with  a  glass  rod  and  placed  on  a  piece  of  white  filteiing-paper  ««h*l«%  s 
trace  of  green  or  blue  colouring  matter.  The  operation  is  finished  when  the  hqi 
tested  exhibits  a  bright  brown  or  ochrey-yellow  speck  upon  the  filtering-] 
8|  parts  of  bichromate  are  required  for  decolourising  lo  parts  of  pure  indigo  blie. 
Chloride  of  iron  may  be  used  for  converting  indigo  blue  into  isatine.  P^nobahly  tha 
observation  made  by  Stockvis  at  Amsterdam  (1868),  that  indigo  blue  is  soluble  ia 
chloroform,  might  be  rendered  available  for  the  testing  of  indigo. 

ladicoBim.  TluS  substauco,  also  known  as  indigotine,  may  be  obtained  firamthe 
indigo  of  commerce,  either  by  carefully  conducted  sublimation,  or,  as  alreadj  staled, 
by  treating  indigo  with  lime,  protosulphate  of  iron,  and  water.  The  fmnula  of 
indigo  blue  is  CieHxoNa.  When  indigo  blue  is,  in  the  presence  of  alkfdinesabetanees, 
brought  into  contact  with  bodies  which  readily  absorb  oxygen — ^for  instance,  witk 
protosulphate  of  iron,  sulphites,  Ac. — ^there  is  formed,  with  simultaneous  deoompositin 
of  water,  white  indigo  or  reduced  indigo,  daHiaNaOa.  The  use  of  indigo  as  a  dye 
material  is  in  great  measure  based  upon  this  reduction.  By  the  action  of  ozidlaiog 
substances,  such  as  permanganic  add,  chlorine,  chromic  add,  a  mixture  of 
so-called  red  prussiate  of  potash  (ferricyanide  of  potassium)  with  potash*  soda,  oizide 
of  copper,  Ac.,  indigo  blue  is  converted  into  isatine,  Cx6HxoNa04.  Indigo  bine 
dissolves  in  concentrated  sulphuric  acid,  but  becomes  thereby  radically  changed  aad 
cannot  be  brought  back  to  its  primitive  state,  forming  as  it  does  with  the  add  a 
chemical  compound— sulphindigotio  add,  or,  as  it  is  termed  by  dyers,  sulphate  of 
indigo.  When  this  acid  solution  is  treated  with  carbonate  of  potash,  there  is  fonaed 
indigo  carmine  or  blue  carmine,  soluble  indigo,  a  deep  blue  predpitate  sdnhle  in 
140  parts  of  cold  water.  This  indigo-carmine  is  used  as  a  water-colour  pogmesl; 
while  mixed  with  some  starch  and  a  little  gum-water  it  is  formed  into  balls  or  oter 
suitable  shapes  and  used  as  washing-blue,  ultramarine  being  also  employed  for  te 
same  purpose. 

Lo(i*ood.orcuAp«Mii7.  This  dye  material  is  the  wood,  freed  from  bark  and  spIiBi,  of 
the  logwood  tree,  Hamatoxylon  campeehianumy  a  native  of  Central  America,  aad 
cultivated  in  several  of  the  West  Indian  Islands.  The  colouring  matter  oontaiiwd.  ia 
this  wood,  is  called  hsematoxyline,  CX6HX4O6,  a  pale  yeUow,  transparent^  ackalalBd 
crystalline  body.  By  itfself  it  is  not  a  pigment,  but  is  a  colourable  material,  vdnch 
becomes  coloured  when  brought  into  contact  with  strong  alkalies,  more 
with  ammonia  and  the  oxygen  of  the  air.  The  solution  of  hnmatoxyline  in 
quite  colourless,  but  becomes  at  once  purple-red  by  the  smallest  addition  of 
The  colouring  matter  thus  formed  is  termed  haamateine.  Logwood  is  used  foortiie 
pose  of  dyeing  blue  and  black.  Extract  of  logwood  is  very  frequently  prqiaied. 
As  with  other  similar  extracts,  it  should  be  made  in  vacuum  pans  withdrawn 
oxidising  action  of  the  air,  because  the  hsBmatoxyline  contained  in  logwood 
thereby  altered.  The  makers  of  the  extracts  of  dye-woods  invariably  nae 
apparatus. 

Lttmns.  This  Colouring  matter,  also  sometimes  termed  toumesol,  is  only  very  ran^ 
used  as  a  dye  for  textile  fiibrics,  the  colour  imparted  being  veiy  fugitive ;  bat  lil 
is  employed  to  impart  a  bluish  tinge  to  whitewash-lime,  further  for  cobuiing 
papers,  for  giving  a  red  hue  to  the  red  champagnes,  kc*  litmus  is  obtained  from  the 
seaweeds  that  yidd  archil,  cudbear,  and  persio,  potash  bdng  employed  with  the 
ammoniacal  liquor.    The  difference  in  the  preparation  consists  in  the  fennentaftioa 


DYSINQ.  595 

and  oxidation  being  carried  farther,  the  result  being  that  the  red  pigment  (ordn)  is 
thereby-  converted  into  a  bine-coloured  material  azoHtmine  :— 


Orcin,  O7H8O2  )  (Azolitmine,  G7H7NO4 

Ammonia,  ^HA  yield  ]  and 

Oxygen,  4O       i  I  Water,  aHaO. 


The  fermented  mass  is  mixed  with  gypsum  and  chalk,  moulded  into  lozenges,  dried, 
and  sent  into  commerce. 

That  known  as  litmus  on  rags,  tournesol  en  drapeaux,  is  prepared  in  the  southern 
parts  of  France  (almost  exclusively  at  Grand  Gallargues,  D6partement  dn  Gard) 
from  the  juice  of  the  Groton  Hnctorium  in  which  coarse  linen  rags  are  repeatedly 
steeped,  and  these  having  been  submitted  to  the  action  of  the  ammonia  evolved  from 
stable  manure  or  from  lant,  become  purple-red  coloured.  Weak  acids  turn  this 
colour  to  yellow-red,  which  is  not  again  turned  to  purple-blue  by  alkalies,  the  effect 
of  these  being  to  render  the  colour  somewhat  green.  The  tournesol  en  drapeaux  is 
largely  used  in  Holland  for  imparting  a  colour  to  the  crust  of  certain  kinds  of  cheese 
made  in  that  country,  the  effect  being  that  the  cheese  thus  externally  dyed  is  by  for 
less  liable  to  decay  and  to  be  attacked  by  cheese-mites.  The  pigment  is  also  used 
for  colouring  a  peculiar  kind  of  paper,  extensively  employed  for  the  covering  of 
sugar-loaves.    It  b  also  used  for  imparting  a  tinge  to  liqueurs,  sweetmeats,  Ac. 

Yellow  Dye$. 

Taiow-wood.  nutte.  Ycllow-wood  is  the  hard  wood  of  the  dyer's  mulberry  tree, 
botanically  termed  Morm  Hnctoria  or  Madura  aurantiaoa.  It  is  imported  chiefly 
from  Cuba,  San  Domingo,  and  HaytL  This  wood  has  a  yellow  and  in  some  parts 
yellow-red  colour,  due  to  a  colourless  crystalline  body,'morine,  G12H8O5,  present  in 
combination  with  lime,  and  also  to  a  peculiar  kind  of  tannic  acid,  morine-tannic  acid^  also 
tanned  madurine  (formula,  Cx^HjoOe),  both  often  met  with  deposited  in  the  wood  in 
large  quantities.  Morine  becomes  yeUow  by  exposure  to  air  and  the  simultaneous 
influence  of  alkalies.  When  treated  with  caustic  potash  madurine  is  split  up  into 
phloroglucine  and  protocatechutic  add.  Yellow- wood  is  employed  for  dyeing  yellow 
and  also  blade,  in  consequence  of  the  large  quantity  of  tannic  add  it  contains.  The 
commercial  extract  of  this  wood  is  termed  cuba  extract 

Toa]iintttia.n«iMhFaitat  This  is  a  green-yellow  wood,  exhibiting  brown-coloured 
stripes,  and  derived  from  a  European  shrub,  the  Rhue  eotinui  of  the  botanists,  a  plant 
bdonging  to  the  southern  parts  of  Europe.  .  The  prefix  '*  young"  is  given  to  it  on 
account  of  the  smallness  of  its  branches  as  compared  with  that  of  the  yellow-wood, 
which  is  distinguished  as  old  fustic.  The  fustet  contains  a  peculiar  colouring 
matter  termed  fustine,  and  in  addition  large  quantities  of  tannic  add.  It  would 
appear  that  fnatin  yidds  quercetine  by  being  split  up  in  chemical  sense. 

AaMttcorAmotto  iM  a  ydlow-red  pigment,  chiefly  used  for  dyeing  silk.  It  is  met 
with  in  commerce  as  a  thick  paste  of  the  consistence  of  putty,  and  is  prepared*in 
America,  the  West  and  East  Indies,  from  the  pulp  of  the  fruit  of  the  Bixa  OreUana. 
Acoording  to  Chevreul,  annatto  contains  two  different  pigments ;  one  of  these  exhibits 
a  yellow  colour  and  is  soluble  in  alcohol  and  water,  while  the  other,  a  red-coloured 
matter,  is  readily  soluble  in  alcohol  but  not  in  water.  Piccaid  states  that  the  formula 
of  the  latter  is  O^H^O^.  Annatto  is  soluble  in  weak  caustio  and  carbonated  alkaline 
edntioDS. 


S96  CHEMICAL  TECHNOLOGY. 

^ dtoJiyBSti'  ^^'^  ^^^  ^  *^®  fr"^*  ®^  various  lands  of  shrubs  which  are  kwwa 
by  the  general  name  of  the  dyer's  buckthorn,  the  Ehamus  itifeetorius^  IL  tmff- 
dalinus,  R.  saxatilis  of  the  botanists,  grown  in  the  Levant,  Southern  France*  nd 
Hungary.  The  size  of  these  berries  varies  very  much,  two  sizes  being  chieflv  mei 
with  and  distinguished  in  commerce,  viz.,  the  large  bright  olive-coloured  full-sized. 
and  the  smaller  shrivelled  deep  brown  berry.  The  former  are  gathered  before  th«T 
are  quite  ripe,  wliile  the  others  have  been  left  after  full  maturity  for  a  considenUe 
time  on  the  twigs.  These  berries  contain  a  fine  golden-yellow  pigment  nasmA 
chrysorhamnine  and  olive-yellow  xanthorhamnine.  According  to  Bolley  the  Ibrmer 
is  identical  with  quercetine.  Berries  are  used  in  calico-printing,  for  the  coloutiiig  d 
paper-pulp,  and  for  the  preparation  of  lake  colours. 

Tumeric  Is  the  dried  root  of  the  Curcuma  lonya  and  (7.  rotunda,  a  plant  growing  m 
India  and  Java,  belonging  to  the  natural  order  of  tlie  Scitaminea.  The  root  is  mi 
with  in  egg-shaped  tubers  or  flattened  lumps,  exhibiting  a  dirty  yellow  colour.  The 
pigment  contained  is  termed  curcumine,  CsHioO^.  As  a  dye  turmeric  is  chiefly  used 
in  silk-printing  and  dyeing,  also  for  woollen  fabrics  for  dark  and  foil  ahadeii  of 
colour.  Upon  cotton  it  dyes  without  mordant,  but  the  colour  is  veiy  fugitive 
Turmeric  test-paper  is  used  for  the  detection  of  alkalies  and  boracio  acid,  bj  wbioli 
it  is  turned  red-brown. 

Weld.  This  dye  material  consists  of  the  dried  herb  and  stems  of  a  plant  botanJcally 
known  as  Reseda  luteola,  a  native  of  the  southern  parts  of  Europe  and  firequentiy 
cultivated  for  the  use  of  dyers.  French  weld  is  considered  the  best.  The  pigmeat 
it  contains  is  known  as  luteoline. 

Qnoxtdtron  BarL     This  dye  material,  as  its  name  indicates,  is  the  inner  bark  of  the 

black  oak,  Quereus  tinctoria.    It  is  a  native  tree  of  North  America,  and  the  drag  is 

imported  in  the  state  of  powder.    The  colour  of  this  substance  is  bright  yellow,  axtd 

it  contains  tannic  acid  in  addition  to  a  yellow  pigment,  quercitrine,   C33H30O-7. 

When  quercitrine  is  treated  with  dilute  acids  it  is  split  up,  yielding  qnereedne. 

O27HX8O12,  a  lemon-yellow  powder  met  with  in  commerce  under  the  name  of  fiavine. 

According  to  Hlasiwetz's  opinion,  quercetine  contains  the  complex  of  morine.    Owing 

to  the  beauty  of  the  colour  it  yields,  quercitron  bark  is,  with  picric  acid,  the  chief 

yellow  dye  of  the  present  day.    Among  the  more  or  less  important  yellow  dyes,  w« 

mention : — Saw-wort,   JSerratula  tiiictoria  ;    dyer's  brown,  or  "jgreenwood.   Genista 

tinctoria ;  the  wongshy,  Chinese  annatto,  or  yellow  pods,  the  seed  capsules  %af  the 

fruit  of  Gardenia  Jhrida,  a  plant  belonging  to  the  j&unily  of  the  Rubiacem  ;  panhee, 

or  Indian  yellow,  Jauns  Indieny  a  dye.  material  imported  from  India,  the  origin  of 

which  is  not  known  (it  is  the  magnesia  salt  of  purreio  or  euxanthic  acid,  and  is 

stated  to  be  obtained  from  the  urine  of  camels) ;  Morinda  yellow,  from  the  Motimda 

citrifoUa.    Since  the  tar-colour  industry  has  sprung  up,  picric  acid  (see  p.  5801  is 

frequently  used  as  a  yellow  dye,  and  mixed  with  either  indigo  or  aniline  blue,  as  a 

green  dye  for  silk  and  woollen  fabrics.    In  order  fully  to  exh&nst  the  picric  add 

d^e-beck,  some  sulphuric  acid  should  be  added  to  it.    More  recently  the  so-caJled 

Manchester  yellow  (see  p.  582)  is  frequently  employed  instead  of  picric  acid.    The 

latter  is  not  used  upon  cotton. 

^°Sck  Dyi.*^  Brown  dyes,  aniline  brown  excepted,  are  mixtures  of  red,  yelbw, 
and  blue,  or  of  yellow  or  red  with  black.  Frequently  a  brown  is  dyed  by  the  use  of 
oxidising  agents  with  tannin-containing  pigments,  such  as  willow,  oak,  or  wahmt 
barks  with  cutch,  the  extract  of  the  wood  of  the  Areca  and  Acacia  catechu,  kc.    The 


DYEING.  597 

latter  is  technically  termed  chemiok  brown.  Manganese,  or  bister  broi^ni,  is  obtained 
firom  the  hydrated  oxide  of  manganese.  Black  is  obtained  from  tannate  or  gallate  of 
]^rotoperoxide  of  iron  or  from  logwood  decoction  and  chromate  of  potash*  or  from 
aniline  black  (see  p.  579).  Green  is  produced  by  mixing  yellow  and  blue,  or  by  the 
use  of  the  Chinese  green  Lo-kao,  obtained  from  Bhamnus  chlorophorus  and  R.  utilis  ; 
<3ST  by  the  use  of  sap-green  from  the  berries  of  the  Rliamnus  catharticui ;  finally, 
smline  green  (aldehyde  green  and  iodine  green,  see  p.  578)  is  used,  and  yields  a  most 
beautiful  dye. 

Bleaching. 
Bkudiiiic.  The  operation  of  bleaching  aims  at  more  or  less  perfectly  whitening 
or  decolourising  the  yams  spun  from  flax,  hemp,  jute,  cotton,  or  of  the  textile 
fabrics  woven  from  the  same.  Vegetable  fibre  resists  the  action  of  most  chemical 
agents  in  use  in  the  bleaching,  while  the  foreign  or  incrustating  or  colouring  matters, 
occurring  chiefly  on  the  surface  of  the  fibre,  are  rendered  soluble  or  completely 
destroyed.  The  bleaching  of  the  fabrics  and  fibres  which,  such  as  linen  or  cotton 
tissues,  consist  mainly  of  cellulose,  is  based  on  this  principle.  The  method  of 
bleaching  wool  and  silk  differs  from  that  of  the  vegetable  fibres,  inasmuch  as 
the  chemicals  used  for  the  latter  would  exert  upon  the  former  a  solvent  action,  not 
only  as  regards  the  impurities,  but  the  substance  itself. 

In  the  operation  of  bleaching,  partly  chemical  and  partly  mechanical  means 
are  employed.  On  the  large  scale,  setting  aside  all  theoretical  considerations  which 
do  not  fiBLll  within  the  scope  of  this  work,  the  operation  of  bleaching  cotton  fabrics 
consists  of  the  following  operations : — 

X.  Singeing,  followed  by  *'  rot  steep"  or  **  wetting-out  steep." 

2.  Liming — ^boiling  with  milk  of  lime  and  water  for  12  to  16  hours. 

3.  Washing  out  the  lime  and  passing  in  hydrochloric  acid  "sours**  or  weakvitrioL 

4.  BowkLng  in  soda-ash  and  prepared  resin,  10  to  16  hours. 

5.  Washing  out  the  bowk. 

^  OrdinaiT  black  ink  which,  if  really  made  with  galls,  consists  essentially  of  gallate  of 
protoperoxide  of  iron  kept  in  Buspension  in  water  by  the  aid  of  gam  arabic,  is  indeed  a 
dye  liquor.    A  very  good  black  ii^  may  be  made  as  follows : — i  kilo,  of  coarsely  pulverised 
nnt  galls  and  150  grms.  of  logwood  chips  are  exhausted  with  5  litres  of  hot  ^^^^^ 
600  grms.  of  gum  arable  are  dissolved  in  2i  litres  of  water ;  and  500  grms.  of  sulphate  of 
iron  in  some  litres  of  water ;  each  of  these  solutions  being  made  separately.    This  done  the 
gall-logwood  infusion  is  mixed  with  those  of  the  gum  and  copperas ;  a  few  drops  of 
essential  oil  of  cloves  or  of  gaultheria  (winter  green  oil)  having  been  added,  there  is  added 
as  much  water  as  will  bring  the  bulk  of  the  liquid  up  to  11  litres.    While  this  kind  of  ink 
attacks  and  corrodes  steel  pens,  It  has  the  additional  disadvantage  that  after  a  time  the 
writing  becomes  yellow.    In  1848  Bunge  oaUed  attention  to  an  ink  originally  invented  by 
Leykaaf  at  Nurenberg,  and  improved  upon  by  C.  Erdmann  at  Leipzig  and  sold  by  him. 
Tins  ink  is  made  up  of  1000  parts  of  a  logwood  decoction  (i  part  of  wood  to  8  parts  of 
water)  and  i  part  of  yellow  chromate  of  potash,  some  bichlor£le  of  mercury  being  added 
for  the  purpose  of  preventing  the  formation  of  mould.    This  ink  is  cheap  and  very  per- 
manent ;  the  colouring  principle  is  a  combination  of  hnmateine  and  oxide  of  chromium. 
Leonhard's  so-called  sdizarine  ink  is  made  by  exhausting  with  water,  so  that  x2o  parts  of 
fluid  are  obtained  from  42  parts  of  gidls  and  3  of  milder.    To  this  mixture  is  added 
1*2  parts  of  sulphindigotio  acid,  5*2  parts  of  green  copperas,  and  2  parts  of  pyrolignite  of 
iron  solution.    Bouen's  blue  ink,  frequently  used  in  France,  consists  of  a  decoction  of 
750  grms.  of  logwood,  35  grms.  of  alum,  31  grms.  of  gum  arable  in  5  to  6  litres  of  water. 
For  an  excellent  extemporaneous  ink,  see  "  Chemical  News,"  voL  xxv.,  p.  45.    Copying 
inks  are  only  more  concentrated  ordinary  inks,  to  which  more  gum  and  sugar  are  added. 
Marking  ink  for  linen  is  a  solution  of  silver  (see  p.  105),  or  aniline  black  produced  on  the 
woven  fabric  (see  p.  579). 


598  CHEMICAL  TECHNOLOQY. 

6.  FaBsing  throngli  a  solution  of  chloride  of  lime  (hypocbloiite  of  Itme^. 

7.  Passing  through  weaJk  hydrochloric  aeid* 

8.  Washing,  squeezing,  and  drying. 

The  singeing  is  not  a  part  of  the  bleacliing  process  properly  oonsidersd;  ii» 
purpose  is  to  remove  the  loosely  adhering  filaments,  and  improve  tiie  appeanowe  ef 
the  cloth  if  required  for  printing. 

The  "  rot  steep "  (so-called  because  the  flour  or  size  with  which  the  goods  wen 
impregnated  was  formerly  allowed  to  enter   into   fermentation  and  pntrefiMtioBj 
is  intended  to  thoroughly  saturate  the  cloth.     The  liming  takes  place  in  kien 
or  kettles  capable  of  holding  from  500  to  r5oo  pieces  of  doth.    The  lime 
carefully  slaked  and  brought  to  a  smooth  milk  of  lime,  being  sifted  00 
small  lumps  of  quick-lime  shall  get  into  the  kier.    The  lime  ia  equally  distiibvfei 
upon  the  cloth  as  it  enters  the  kier.     The  cloth  is  pressed  into  the  liquor  wuk 
the  boiling  commenced  and  continued  for  a  period  of  is  to  16  hours.    At  the  eaid 
that  time  the  liquor  is  run  off  and  clear  water  run  in  to  cool  the  pieces  of  dath^ 
which  are  then  taken  out  and  washed.      The  utility  of  the  liming  consists  m  fis 
action  upon  the  greasy  matters,  forming  with  them  a  kind  of  insoluble  soap^  which  b 
easily  removed  by  the  subsequent  processes.    The  souring  after  liming  remores  aB 
excess  of  lime  and  breaks  up  the  insoluble  hme-soap,  leaving  the  greasy  mailerB  upon 
the  cloth,  but  in  such  an  altered  state  as  to  be  easily  dissolved  in  the  bawkjng  whidi 
follows.    Hydrochloric  acid  is  sometimes  used  in  this  souring,  but  more  oommoBly 
dilute  sulphuric  acid  is  employed.    The  bowking  or  boiling  wiUi  alkali  and  soap  has 
for  its  object  the  removal  of  the  greasy  matters ;  it  dissolves  them,  and  all  the  diii 
held  by  them  now  comes  out  of  the  cloth,  leaving  the  cotton  nearly  pore.    The  alkali 
used  in  this  process  is  soda-ash.    The  soap  is  made  from  resin  and  called  pr^iared 
resin.    The  last  process  is  that  of  passing  the  goods  through  a  dear  eolation  of 
bleaching-powder  for  the  purpose  of  destroying  the  slight  tinge  of  coloiir  of  a  boff 
or  cream  shade  still  adhering  to  the  cotton.     The  solution  of  bleaching-powder 
is  very  weak,  so  that  probably  a  piece  of  calico  of  the  ordinary  size  does  not  take  np 
more  than  the  soluble  matter  from  4  of  an  ounce  of  bleaching-powder.    The  goods 
are  allowed  to  remain  some  time  in  soaking  with  the  chloride  of  Hme  arJntywy, 
and  are  next  passed  through  sours  for  the  final  operation.    The  dilute  hydrodilnie 
acid  has  the  effect  of  setting  the  chlorine  free  from  the  bleaching-powder  and  tints 
completing  the  destruction  of  the  colour.    At  the  same  time  it  removes  the  lime 
likewise  any  traces  of  iron  (iron  moulds)  that  may  exist  in  the  doth.    Linen  is 
80  easily  bleached  as  cotton,  and  it  appears  to  suffer  considerably  by  boiling  with 
lime  and  by  contact  with  bleaching-powder.    It  is,  therefore,  generally  bleadied  by 
continual  boilings  with  alkali  and  a  few  sourings  with  bleaching-powder;  or  as 
is  injurious,  the  hypochloriles  of  potash  or  soda  are  substituted.    Woollen  goods 
yams  are  bleached  by  treating  them  with  very  mild  alkaline  liquors^  whidi 
the  fatty  matters,  lant  and  soap  with  soda  crystals  being  the  substances  juntify 
employed.    Sulphurous  add  gas — or,  as  it  is  termed  in  the  trade,  vapour  of  baniiBg 
brimstone— is  used  to  finish  wool,  giving  it  whiteness  and  lustre.    The  following  is 
an  outline  of  the  process  as  described  by  Persoz  for  bleaching  woollen  goods;  it 
is  for  40  pieces  each  50  yards  long: — i.  Passed  three  times  through  a  aohxtton  sf 
25  lbs.  of  carbonate  of  soda  and  7  lbs.  of  soap  at  a  temperature  of  100"*  F. ;  add  J  Ih. 
of  soap  after  every  four  pieces.    2.  Wash  twice  in  warm  water.    3.  Passed  Qam 
times  Uirough  a  solution  of  25  lbs.  of  carbonate  of  soda  at  120''  F.,  and  add  I  lb.  «f 


VYEtSG.  599 

8(Mif  again  after  eveiy  four  pieces.  4.  Sulphured  in  a  room  for  twelve  lionrs,  nsing 
•5  lbs.  of  sulphur  for  tlie  forty  pieces.  5.  Passed  three  times  through  a  solution  of  soda, 
as  in  No.  3.  6.  Sulphured  again,  as  iu  No.  4.  7.  Soda  liquor  again,  as  in  No.  3. 
8.  Washed  twice  through  warm  water.  9.  Sulphured  a  tliird  time  as  in  No.  4. 
10.  Washed  twice  in  warm  and  then  in  cold  water.  11.  Blued  with  extract  of 
indigo  (indigo-carmine)  according  to  taste. 

BiMdiioff  of  80k.  The  operation  of  bleaching  silk  is  always  preceded  by  removing 
fdecortieating,  degumming)  the  gummy  substance  attached  to  and  externfdly 
•covering  the  fibre.  This  is  effected  by  boiling  the  raw  silk  in  soap  and  water. 
For  the  purpose  of  bleaching  silk  nothing  but  water,  soap,  and  sulphur  (for  making 
sulphurous  acid)  are  used.  Occasionally  some  soda  crystals  are  employed  to 
save  soap  but  as  alkalies  injure,  and  if  incautiously  used  destroy,  the  fibre,  they 
must  be  employed  with  extreme  care.  Bran  is  sometimes  used  with  soap  in  order  to 
neutralise  any  excess  of  alkali  (bran  contains,  or  rather  develops,  when  it  becomes 
^iret,  lactic  acid).  The  process  is  terminated  by  passing  in  an  extremely  diluted 
sour  (solution  of  sulphuric  acid  in  water)  so  weak  as  scarcely  to  be  acid  to  the  taste. 
Sulphuring  is  only  required  for  silks  intended  to  be  left  either  white  or  to  be  dyed  or 
pxinted  with  bright  and  light  colours.  This  operation  requires  great  care  and  should 
be  seldom  resorted  to. 

This  is  an  outline  of  the  process  of  bleaching  as  carried  on  in  practice  on  the 
large  scale  in  this  as  well  as  in  other  countries.  The  theoretical  consideration  of 
the  mode  of  action  of  the  substances  employed  belongs  to  theoretical  chemistry,  and 
is  treated  imder  the  heads  of  Chlorine,  Sulphurous  Acid,  Oxidising  Substances,  Ac. ; 
and  as  far  as  the  textile  fibres  are  concerned,  under  Cellulose  for  flax,  hemp,  jute, 
cotton,  and  the  Animal  Fibres  for  wool  and  silk.  The  meadow  bleaching  of  cotton 
and  linen  fabrics  is  still  resorted  to  in  some  extent  but  only  in  connection  with  the 
processes  already  referred  to.  None  of  the  novelties  proposed  for  bleaching 
purposes — among  these,  for  instance,  the  use  of  permanganate  of  potash  (Te8si6  dn 
Motay's  process)  as  a  bleaching  agent — have  been  found  by  practical  bleachers  of 
great  experience  to  be  either  better,  more  manageable,  or  cheaper  than  the  methods 
sanctioned  by  lengthy  experience  and  daily  use. 

Dyeing  of  Spun  Yabn  and  Woven  Textile  Fabbics. 

Dyeiiif.  Just  ss  suimal  charcoal  and  arable  soil  are  possessed  of  the  property 
to  assimilate  in  their  pores  colouring  matter  and  some  inorganic  substances  without 
the  latter  being  altered,  so  also  do  animal  and  vegetable  fibres  possess  the  property 
of  absorbing  from  solutions,  and  fixing  in  a  more  or  less  insoluble  condition,  dyes 
and  some  of  the  constituents  of  mordants.  This  combination,  or  more  correctly 
union,  is  often  so  loose  that  it  is  readily  broken  up  by  repeated  treatment  with 
solvents  (viz.  simply  washing  with  water  or  soapsuds),  especially  if  aided  by  heat. 
Thus,  for  instance,  a  textile  fibre  dyed  (rather  tinged,  for  dyeing  implies  fixity)  with 
sulphindigotic  acid,  or  a  solution  of  Berlin  blue  in  oxalic  acid,  may  be  decolourised 
again  by  repeated  washing  in  water.  A  fibre  can  only  be  called  dyed  in  the  strict 
sense  when  the  dissolved  dye  material  has  been  united  in  insoluble  condition  with 
the  fibre,  for  which  purpose  often  the  intervention  of  a  third  substance,  viz.,  a 
mordant,  is  required,  the  union  thus  formed  resisting  the  action  of  solvents,  that  is 
to  say — ^repeated  washing  with  warm  water  and  soap.  The  colour  thus  produced  is 
termed  fast,  and  resists  the  action  of  light,  air,  soap-water,  weak  alkaline  solutions. 


6oo  CHEMICAL  TECHNOLOGY. 

and  weak  acids.  A  dye  which  does  not  resist  these  agents  is  termed  fogitiTCL 
Dyeing  is  partly  based  on  chemical  principles,  but  as  regards  the  taking  ap  or  fixrag 
of  tlie  dye  by  the  Hbre,  it  would  appear  to  be  only  a  physical  attraction,  capillaii^* 
as  there  does  not  exist  between  a  certain  quantity  of  fibre  and  of  dye  an  atomisDc 
relation.  Moreover,  neither  fibre  nor  dye  have  lost,  after  fixation  has  taken  place, 
tlieir  characteristic  properties. 

The  insoluble  condition  of  the  union  between  fibre  and  dye  may  be  obtained 
in  various  ways,  viz. — i.  By  removal  of  the  solvent,  bs,  for  instance,  oxide  of  copper 
dissolved  in  ammonia  may  be  fixed  on  the  fibre  by  simply  evaporating  the  latter 
fluid ;  chromate  of  zinc  dissolved  in  ammonia  may  be  fixed  in  the  same  manner.  The 
precipitation  of  carthamine  from  its  alkaline  solution  by  the  aid  of  an  acid,  and  tbs 
precipitation  of  some  of  the  tar  colours  from  their  alcoholic  solutions  belong  to  tbe 
same  category.  The  insoluble  condition  can  be  produced  by — 2.  Oxidation,  the  pre> 
viously  soluble  dye  being  rendered  insoluble  by  taking  up  oxygen  (ageing  process). 

The  ferrous  and  manganous  sulphates  becoming  converted  by  oxidation  into 
insoluble  hydrated  oxides;  and  further,  those  dyes  of  vegetable  origin  wbidi» 
in  addition  to  tannic  acid,  also  contain  a  peculiar  dye  material,  such  as  qnercitron, 
sumac,  yellow- wood,  fustet,  &c.,  belong  to  this  category.  When  any  textile  iabnc  ia 
impregnated  with  an  aqueous  or  alkaline  infusion  of  these  substances,  and  then  aged 
or  stoved  (technical  terms  for  exposure  to  action  of  air  in  what  are  termed  ageing- 
rooms),  the  dye  material  becomes  brown,  and  is  tlien  no  longer  soluble  in  water.  This 
is  more  rapidly  effected  by  treating  the  textile  fabrics,  previously  impregnated  wiA 
the  solutions  of  the  drugs,  with  oxidising  substances — tor  instance,  chromic  acid  or 
bichromate  of  potash.  Another  instance  of  this  kind  is  the  process  of  dyeing  black 
with  logwood  and  chromate  of  potash,  whereby  the  hasmatoxyline  of  the  wood 
is  oxidised,  and  the  chromic  acid  reduced  to  chromic  oxide.  To  some  extent 
the  dyeing  blue  with  indigo  in  the  vat  (blue  vat),  to  be  more  fully  described  pre- 
sently, belongs  to  the  same  category ;  but  in  this  case  tlie  production  of  the  oolonr  ii 
due  to  the  gradual  absorption  of  oxygen,  while  simultaneously  hydrogen  is  evolTed 
from  the  white  indigo,  the  hydogen  combining  with,  oxygen  and  forming  water.  The 
foimation  of  aniline  black  upon  tissues  by  the  aid  of  ozone-forming  substances 
(chlorate  of  potash,  ferricyanide  of  ammonium,  chromate  of  copper,  freshly  precipi- 
tated sulphide  of  copper)  belongs  to  this  class.  In  many  cases  the  insoluble  condi- 
tion (3)  is  obtained  by  double  decomposition ;  as,  for  instance,  blue  is  produced  by 
hydroferrooyanic  acid  and  oxide  of  iron ;  green  by  arsenite  and  sulphate  of  copper ; 
yellow  by  chromate  of  potash  and  a  soluble  lead  salt  This  mode  of  fixation  of  pig- 
ments is  only  employed  with  mineral  colours.  The  most  important  and  moct 
ordinary  method  of  fixing  dyes  is  (4)  by  the  aid  of  mordants.  We  understand  by  a 
mordant,  a  solution  of  some  substance  which,  not  being  itself  a  dye.  has  an  affinity  as 
well  for  the  fibre  as  £or  the  dye  material,  and  is  thereby  capable  of  effecting  the 
fixation  of  the  latter  to  the  fibre. 

The  more  important  mordants  are  : — Alum ;  sulphate,  acetate  and  hypoeolphite  o£ 
alumina;  aluminate  of  soda;  and  acetate  of  iron;  according  to  Keimann  [1870],. 
amorphous  silica  may  be  used  for  fixing  several  dye  materials ;  tin  mordants :  &tty 
^bstances,  Gallipoli  oil,  in  Turkey-red  dyeing;  tannic  acid,  for  madder  colomrs; 
cochineal  colours  ;  aniline  dyes  on  cotton  and  linen  fabrics ;  albumen,  dried  white  of 
egg,  gluten,  caseine,  and  fatty  oils  (linseed  oil  also  sometimes).  The  fabrics  to 
be  dyed  are  impregnated  with  the  mordants,  which  are  next  fixed,  an  operatiim 


DYEING.  6oi 

difTerisg  according  to  the  nature  of  the  mordant  as  well  as  the  specific  dye  it  is 
required  for ;  but  in  general  terms,  ageing,  dang-bath,  bran-bath,  and  soaping,  are 
employed,  after  which  the  woven  fabric  is  placed  in  the  dye  solution  contained  in  the 
dye-beck.    Most  of  the  dyes  of  organic  origin  can  be  fixed  only  by  the  aid  of  mordants* 
Hancroft  considers  dyes  as  substantive  and  adjective.     By  the  former  is  under- 
stood those  which  without  the  aid  of  a  mordant  become  fixed  upon  the  textile  fibres 
in   an  insoluble  condition:   to   these  belong  all  mineral  pigments;    and  among 
the  vegetable  colouring  substances — indigo,  turmeric,  annatto,  safflower,  also  most  of 
the    tar-colours,  although,  as  already  mentioned,  tannic  acid  is  used  for  fixing 
fuchsin  and  similar   tar-colours.     By  adjective  colours   or  dyes   is  understood 
each  as  require  an  intermediate  substance  (a  mordant  in  fact)  to  become  fixed  upon 
the  fibre  in  an  insoluble  condition.    These  intermediate  substances  are  termed  mor- 
Monunts.    dauts ;  they  not  only  serve  for  fixing  the  dye  to  the  textile  fibres,  but  also 
produce  in  the  mordanted  goods  such  an  alteration  that  the  parts  of  the  tissue  where 
the   composition  is  applied  appear  white  when  the  goods  are  taken  from  the  dye- 
heck.    The  substances  which  produce  this  effect  are  technically  termed  dischargers, 
or  discharge  compositions ;  among  them  are  phosphoric,  tartaric,  oxalic,  arsenious 
acids,  &c. ;  but  in  practice  the  goods  are  first  uniformly  dyed,  and  the  discharge  then 
applied  so  as  to  act  only  where  it  is  desired  to  exhibit  a  pattern.    Wliat  are  termed 
resists  are  not  mordants,  but  only  compositions  applied  to  the  woven  fabric  at 
certain  parts  where  it  is  desired  that  no  deposition  of  colour  or  mordant  shall  take 
place.    Mordants  may  modify  the  original  colour  that  a  dye  yields ;  as,  for  instance, 
with  alumina  compoiinds  madder  yields  red,  pink,  and  scarlet ;  with  salts  of  iron, 
according  to  the  degree  of  concentration,  lilac,  purple,  black ;  and  brown  with  cer- 
tain salts  of  copper.    For  the  purpose  of  clearing  and  brightening  [avivage],  the 
dyed  or  printed  goods  are  passed  through  solutions  of  either  dilute  acids,  weak 
or   strong  alkalies,  soap-suds,  bran-bath,  solutions  of  bleaching-powder,  or  also 
of  some  other  dye  material. 

DyeiiiK  Wooikn  Fkbziea.  Wool  is  sometimcs  dyed  in  the  fiock  or  fleece,  that  is  to  say, 
when  not  spun  ;  sometimes  in  yam  or  worsted  and  as  a  finished  woven  fabric  (cloth, 
broadcloth,  &c.).  As  there  is  always  some  refuse  wool  in  the  operations  of  weaving, 
falling,  and  dressing  the  woollen  tissues,  it  is  advantageous  to  dye  wool  in  the  condi 
tion  of  spun  yam.  When  the  dye  intended  to  be  applied  to  wool  is  fast,  the  textile 
fibre  is  first  mordanted.  For  this  purpose  the  woollen  fibre  is  treated  with  a  solution 
of  alum  and  cream  of  tartar  (bitartrate  of  potash) ;  or  with  the  latter  salt  and  tin-salt 
(chloride  of  tin) ;  or,  again,  cream  of  tartar  and  green  vitriol ;  for  certain  colours, 
chloride  of  tin  and  pink  salt  (see  p.  75 )  are  used. 

Dyeing  Wool  Bbu.  The  imparting  of  a  blue  colour  to  wool  is  one  of  the  most 
important  operations  of  dyeing  woollen  goods.  It  is  frequently  effected  with  indigo, 
which  produces  the  most  beautiful  and  fast  colours ;  but  indigo  is  used  only  for  the 
better  and  heavier  kinds  of  woollen  fabrics ;  lighter  tissues — ^merinos  for  instance — 
are  often  dyed  with  Pi*ussian  blue  (not  a  fast  colour),  while  common  woollen  goods, 
flannels,  &c.,  if  dyed  blue  at  all,  are  dyed  with  logwood  and  blue  vitriol  (sulphate  of 
copper).  In  order  to  ascertain  whether  a  woollen  tissue  has  been  dyed  with  indigo, 
IVussian  blue,  or  copper  salts,  the  following  tests  may  be  employed.  Woollen 
tissue  dyed  with  indigo  does  not  change  its  colour  by  being  boiled  with  caustic 
potash,  or  by  being  moistened  with  concentrated  sulphuric  acid.  When  Prussian  blue 
is  the  dye  used,  the  tissue  becomes  red-coloured  by  being  boiled  with  caustic  potash^ 

2  7. 


6o2  CHEMICAL  TECHNOLOGY. 

and  becomes  discoloured  by  being  moistened  with  strong  snJphtirie  acid.  WooBeB 
goods  dyed  with  logwood  and  copper  salts  are  reddened  by  being  moistened  with 
dilnte  sulphuric  acid,  and  on  being  incinerated,  the  tissue  leayes  an  ash  <v^Tit*"™g 
copper. 

Indigo  Bino.  WooUeu  goods  are  most  frequently  dyed  blue  with  indigo  by  means  «f  a 
solution  of  white  indigo  (reduced  indigo)  in  an  alkaline  fluid,  the  goods  being  htud 
by  exposure  to  air — that  is  to  say,  by  the  oxidation  of  the  indigo  taken  ap  by  the  fibre, 
the  dye  becoming  simultaneously  fixed.  The  principle  of  this  mode  of  dyemg  vilh 
inpUgo  (technically  known  as  blue  Tat),  may  be  elucidated  by  the  following  iknmidi:— 

sintYatB.  The  greatest  consumption  of  indigo  is  in  forming  the  blue  vat&,  in  whtdk 
woollen  or  cotton  goods,  more  rarely  linen,  are  dyed  by  simply  inmiersing  them  m 
the  solution  of  white  indigo.  The  same  vats  are  not  equally  adapted  for  wool 
and  calico,  there  being,  as  will  be  seen  in  the  following  details,  a  wide  difference  ia 
their  composition.  According  to  the  general  accounts,  the  lime  and  copperas  vat 
(see  below)  is  not  well  adapted  for  woollen  goods;  stiQ  in  the  most  reoenlif 
published  French  treatise  on  woollen  dyeing,  there  is  no  mention  made  of  any 
other  kind  of  vat ;  the  following  proportions  and  directions  being  given  for  settiDg 
a  vat  for  dark  blue: — 1200  gallons  of  water;  34  lbs.  of  quick-lime;  22  Iba 
of  green  copperas ;  12  lbs.  of  ground  indigo ;  4  quarts  of  caustic  potash  soIntiaB  at 
34<*  =  sp.  gr.  1*288.  The  indigo  is  ground  very  fine  by  trituration  in  propofy 
constructed  nulls,  this  being  a  point  of  the  utmost  importance.  In  the  abore  recipe 
the  potash  is  mixed  with^  5  gallons  of  water  in  an  iron  pan,  and  the  indigo  added. 
The  mixture  is  gradually  heated  to  ebullition  and  kept  boiling  for  two  hoim 
with  iminterrupted  stirring :  this  softens  and  prepares  the  indigo  for  dissolving.  Hie 
lime  is  well  slaked  so  as  to  be  very  fine,  and  is  next  passed  through  a  sieve  in  the 
state  of  milk  of  lime.  It  is  then  mixed  with  the  indigo  and  potash ;  the  copperaa 
(protosulphate  of  iron),  previously  dissolved,  is  added  to  the  vat  and  well  stirred ; 
then  the  mixture  of  lime,  potash,  and  indigo  is  poured  in,  and  the  whole  well 
for  half  an  hour.  If  the  proportions  are  well  kept,  the  vat  will  be  fit  for  wo: 
in  twelve  hours ;  if,  however,  it  looks  blue  under  the  scum,  it  is  a  sign  that  tin 
indigo  is  not  wholly  dissolved,  and  more  lime  and  copperas  should  be  added,  and  tlie 
vat  left  undisturbed  for  another  twelve  hours.  The  vat  is  worked  at  a  temperatnre 
of  70^  to  80°  F.  This  is  the  ordinary  composition  of  a  vat  for  dyeing  cotton,  but  ii 
not,  at  least  in  England,  in  use  for  dyeing  woollen  goods. 

The  usual  blue  vats  for  wool  contain  neither  copperas  nor  lime,  or  but  a  small 
quantily  of  the  latter;  as,  for  instance — ^Water,  500  gallons;  indigo,  20  Iha.; 
potash  (carbonate,  pearl-ash),  30  lbs.;  bran,  9  lbs.;  madder,  9  lbs.  The  water 
is  heated  to  just  below  its  boiling-point ;  the  potash,  bran,  and  madder  are  first  pat 
into  the  vat,  a  well-made  wooden  tub  of  convenient  size,  and  then  the  indigo 
previously  very  finely  ground.  Cold  water  is  added  so  as  to  reduce  the  temperature 
to  90°  F.,  and  that  temperature  is  maintained  constantly  by  means  of  a  steam-pipe. 
The  ingredients  are  well  stirred  every  twelve  hours.  The  vat  is  generally  ready  te 
use  in  forty-eight  hours  after  setting.  This  vat  does  not  work  longer  than  about 
a  month,  and  is  somewhat  expensive  on  account  of  the  potash.  Another — the 
so-called  German — vat  is  much  more  manageable,  and  may  be  worked  for  two 
}*ears  without  emptying,  being  freshened  up  as  required.  It  is  composed  of  the  fol- 
lowing ingredients : — 2000  gallons  of  water  are  heated  to  130°  F. ;  and  there  are  added 


DYEING.  603 

do  lbs.  of  ciystals  of  soda  (common  carbonate) ;  2\  pecks  of  bran;  and  12  lbs. 

of  indigo ;  the  mixture  being  well  stirred.    In  twelve  hours  fermentation  sets  in  ; 

bubbles  of  gas  rise;    the  liquid  has  a  sweet  smell,  and  has  assumed  a  green 

colour.     2  lbs.  of  slaked  lime  are  now  added  and  well  stirred,  the  vat  is  again  heated 

and  covered  up  for  twelve  hours,  when  a  similar  quantity  of  bran,  indigo,  and  soda, 

iprith  some  lime,  are  added.    In  about  forty-eight  hours  the  vat  may  be  worked ;  but 

as  the  reducing  powers  of  the  bran  are  somewhat  feeble,  an  addition  of  6  pounds  of 

molasses  is  made.     If  the  fermentation  becomes  too  active,  it  is  repressed  by 

the  addition  of  lime ;  if  too  sluggish,  it  is  stimulated  by  the  addition  of  bran  and 

molasses.    Like  all  the  other  blue  vats  for  wool  it  is  worked  hot.    Another  kind  of 

vat  may  be  called  the  woad  vat,  because  a  considerable  quantity  of  woad  is  added  to 

it»  and  also  madder,  which  in  this  case  acts  simply  by  reason  of  the  saccharine 

matter  it  contains.    The  proportions  are : — ^Pulverised  indigo,  i  lb. ;  madder,  4  lbs. ; 

slaked  lime,  7  lbs.,  boiled  together  with  water  and  poured  upon  the  woad  in  the  vat. 

After  a  few  hours  fermentation  sets  in,  and  fresh  indigo  is  added  according  to  the 

depth  of  colour  required  to  be  dyed.    The  pastel  vat  is  set  with  a  variety  of  woad 

'which  grows  in  France,  and  which  is  richer  in  colouring  matter  than  the  common 

woad.    It  is  possible  that  the  colouring  matter  of  the  pastel  adds  to  the  effect ;  but  it 

is  more  likely  that  while  it  furnishes  fermentescible  matters  useful  in  promoting  the 

solution  of  indigo,  it  is  added  as  a  remnant  of  ancient  usage.    Before  indigo  became 

again  known  in  Europe  (the  dye  was  known  to  the  Greeks  and  Bomans),  in  the  17th 

century,  woad  was  the  general  blue  dye  material.    The  method  of  dyeing  the  woollen 

fibre  and  fabrics  is  very  simple.    The  wool,  thoroughly  wetted  out.  is  suspended  on 

frames,  and  dipped  in  the  vat  for  an  hour  and  a  half  or  two  hours,  being  agitated  all 

the  time  to  insure  regularity  of  colouring.     The  pieces  are  then  removed,  washed 

in  water,  and  treated  with  weak  hydrochloric  or  sulphuric  acids  to  remove  the  alkali 

retained.    As  regards  blue  vat  for  cotton  dyeing,  in  some  exceptional  cases  when 

thick  and  heavy  goods  have  to  be  dyed,  the  so-called  German  vat  is  used ;  but 

generally  all  calicos  are  dyed  blue  by  means  of  the  cold  lime  and  copperas  vat.    The 

materials  used  are  lime,  protosulphate  of  iron,  ground  indigo,  and  water.    The 

chemical  action  consists,  in  the  first  instance,  in  the  formation  of  sulphate  of  lime 

and  protoxide  of  iron ;  the  latter  substance  having  a  considerable  affinity  for  oxygen, 

removes  an  atom  of  it  from  the  blue  indigo,  converting  it  into  white,  which  dissolves 

in  the  excess  of  lime,  and  is  ready  for  dyeing.    The  proportions  are  as  follows: — 

900  gallons  of  water ;  60  lbs.  of  green  copperas ;  36  lbs.  of  ground  indigo ;  80  to  90 

lbs.  of  slaked  lime,  stirred  every  half  hour  for  three  or  four  hours,  then  left  twelve 

hours  to  settle,  well  raked  up  again,  and  as  soon  as  settled  ready  for  dyeing. 

BuonyBhie.  As  already  stated,  indigo  dissolves  in  concentrated  sulphuric  add, 
forming  (because  it  is  not  a  solution  in  the  ordinary  sense  of  the  word)  sulphindigotio 
acid,  which  is  employed  in  dyeing  wool  in  the  following  manner : — First,  i  part  of 
indigo  is  treated  with  4  to  5  parts  of  fuming  sulphuric  acid ;  next,  this  solutLon 
is  poured  into  a  vessel  containing  water;  and  into  this  mixture  flock  wool  is 
immersed  for  twenty-four  hours.  After  this  time  the  wool  is  removed  from  the 
vessel  and  drained,  and  transferred  to  a  cauldron  filled  with  water,  to  which  has  been 
added  either  carbonate  of  ammonia,  or  of  soda,  or  of  potash,  and  boiled  for 
some  time.  The  solution  thus  obtained,  technically  known  as  extract  of  indigo 
or  as  indigo  carmine,  is  used  for  dyeing  wool  which  has  been  previously  mordsnted 
with  almn.    There  is  formed  on  the  wool  sulphindigotate  of  alumina. 


1 


6(H  CHEMICAL  TECBNOLOGT. 


*5^55j^  *?*  ^^  order  to  recover  the  indigo  from  scraps  and  rags  of  wooEen  ad 
other  fabrics  dyed  indigo  bine,  the  materials  are  treated  with  dilate  snlphmie  aoi 
which  is  heated  to  loo^.  The  wool  is  dissolved,  while  the  indigo  is  left  as  m 
insoluble  sediment.  Military  uniforms  yield  from  2  to  3  per  cent  of  indigo.  TVe 
acid  solution  is  next  neutralised  with  chalk,  and  a  sulphate  of  lime  is  obtaarai 
which,  owing  to  the  nitrogenous  matter  intermingled,  may  be  usefdUj  employed  as  t 
manure. 

^"^^^^cf""^  Wool  is  dyed  with  the  so-called  Prussian  blue  (ferrocjanide  cf 
iron)  by  two  methods,  one  of  which  consists  in  saturating  tlie  wool  with  a  solotiofi  <£ 
a  salt  of  peroxide  of  iron  (generally  the  persulphate,  or  preferably  the  pemitntr). 
after  which  the  wool  is  passed  through  a  solution  of  ferrocyanide  of  potaassa 
in  water,  acidulated  with  sulphuric  acid.  The  other  process  producing  so-called  Blm 
de  France  is  based  upon  the  decomposing  action  which  the  atmosphere  exerts  on  tte 
ferro-  and  ferri-cyanhydric  acids.  The  goods  are  inmiersed  in  a  solution  of  either  the 
ferro-  (yellow)  or  ferri-  (ruby  red)  cyanide  of  potassium  (commonly  yellow  or  red 
prussiate)  in  water,  to  which  are  added  sulphuric  acid  and  alum.  Afterwards  tfat 
goods  are  aged,  or  exposed  to  the  air  in  rooms  in  which  steam  is  simnltaneoasij' 
admitted  to  elevate  the  temperature  and  assist  the  action  of  the  oxygen  of  the  iii. 
The  result  is  that  the  ferro-  or  ferri-  cyanhydric  acid  is  decomposed,  hydroeruie 
acid  being  evolved,  while  there  is  deposited  on  the  fibres  of  the  woven  fabric  ftrnv  | 
cyanide  of  fron,  Prussian  or  Berlin  blue.  Meitzendorff  has  recently  invented  1 
method  of  dyeing  this  blue  by  which  a  colour  is  produced  veiy  similar  to  tbft 
obtained  by  the  so-called  Saxony  blue.  He  prepares  a  solution  containing  fena- 
cyanide  of  potassium,  chloride  of  tin  (SnCl^),  tartaric  and  oxalio  acids  ;  this  aolntuB 
is  heated  and  the  wool  kept  therein  for  some  time.  The  oxalic  acid  dissolves 
the  Prussian  blue,  which  of  course  can  only  act  as  a  dye  when  dissolved,  aor 
of  it  left  undissolved  being  lost.  The  tartaric  acid  increases  the  brilliancy  of  dtf 
colour. 

'^^^Joo^s^**^  For  this  purpose  logwood  is  boiled  in  the  dye-beck  wifli 
water,  and  to  t^e  decoction  are  added  alum,  cream  of  tartar,  and  sulphate  of  coppa- 
The  wool  is  boiled  in  this  fluid,  and  is  next  cleared  by  being  boiled  in  a  fluid  eoa- 
taining  logwood,  tiusalt  (protochloride  of  tin),  alum,  and  cream  of  tartar*  The  goods 
dyed  in  this  manner  do  not,  as  is  the  case  with  the  indigo  goods,  become  white  bf 
Wear.  Instead  of  logwood,  archil  and  cudbear  are  frequently  used  for  so-called  half- 
fast  colour. 

Dyoing  Tallow.  On  the  Continent,  weld,  which  has  become  quite  obsolete  for  djBB% 
yellow  on  wool  in  the  United  Kingdom,  having  been  entirely  snperseded  by 
quercitron  bark,  is  still  used  for  producing  a  yellow  dye,  on  account  of  the  fact  thtt 
weld,  when  brought  into  contact  with  an  alkali,  becomes  less  red-coloured  thaaii 
the  case  with  the  other  yellow  dyes. 

In  dyeing  with  weld  its  colouring  matter  is  extracted  by  water,  and  the  deeoctkft 
added  to  the  goods  intended  to  be  dyed.  With  alum  it  dyes  a  very  fine  clear  yeUoVi 
tolerably  permanent  in  soap,  but  not  resisting  air  and  light.  Weld  has  not  more  tfais 
one-fourth  the  tinctorial  power  of  quercitron  bark,  and  on  this  account,  as  well  as  ca 
that  of  its  great  bulk  relative  to  its  weight,  it  is  not  used  in  this  country.  Fastis 
yellow- wood,  is  very  extensively  employed  in  dyeing,  and  is  the  most  suitable  yeOov 
matter  for  working  with  other  colours  in  compound  shades.  With  alnmiiioas 
mordants  it  gives  yellow  of  an  orange  shade ;  with  iron  mordants  it  givtt  diatei 


DYEING.  605 

grejB,  and  olive.  As  a  yellow  colooring  matter  it  is  considered  to  be  of  far  less 
poTver  than  quercitron  bark  weight  for  weight,  while  it  is  also  inferior  in  purity  of 
colour ;  but  as  fustic  withstands  the  action  of  adds  and  acid  salts  better  than  bark, 
it  is  used  in  greens,  blacks,  and  mixed  colours  where  yellow  is  required.  Young  or 
French  fustic  (also  known  as  Venice  $umac)  is  used  for  imparting  yellow  to  merinos. 
A  golden  yellow  is  produced  upon  wool  with  either  picric  acid  or  Manchester 
yellow. 

i>7«iiiicwooiB«L      Madder  is  the  chief  colouring  matter  employed  for  imparting  to 
wool  a  red  or  scarlet  colour.    The  process  of  dyeing  wool  with  madder  consists  in 
mordanting  the  wooUen  tissue,  fibre,  or  yam,  and  in  immersing  it  in  the  dye-beck 
containing  madder  with  water.    The  wool  is  mordanted  by  being  immersed  in  a 
warm  solution  of  alum  and  cream  of  tartar.    The  dyeing  is  effected  by  placing  the 
mordanted  goods  in  the  dye-beck  or  madder-bath,  the  quantity  of  madder  being 
equal  to  half  the  weight  of  the  woollen  goods.    In  practice  the  goods  are,  of  course, 
slowly  moved  into,  through,  and  out  of  the  dye-beck,  proper  mechanism  being 
provided  for  this  purpose.     After  having  been  dyed,  the  goods  are  thoroughly 
washed,  so  as  to  remove  excess  of  dye  as  well  as  any  mechanically  adhering 
particles  of  madder.    Dyeing  red  with  cochineal  is  effected  upon  wool  in  the  same 
manner  as  with  madder.  Scarlet  is  red  with  a  yellowish  hue,  while  a  peculiar  hue  of 
red  is  termed  crimson,  often  produced  by  cochineal.    Woollen  fiibrics  are  mordanted 
in  a  mixture  of  water,  cochineal,  cream  of  tartar,  and  tinsalt,  and  next  dyed 
by  boiling  with  more  cochineal  and  tinsalt.    Wool  is  very  readily  dyed  with  all  the 
tar-colours  (red,  blue,  green,  grey,  yellow,  brown,  violet),  the  affinity  of  wool  for 
these  colours  being  so  great,  that  the  solution  of  any  of  these  pigments  may  be  com- 
pletely deprived  of  its  colouring  matter  by  contact  with  wooL 

on«i]>7w.      Green  dyes  are  usually  obtained  by  combining  blue  and  yellow.    Wool 
is  first  dyed  blue,  and  having  then  been  mordanted  with  cream  of  tartar  and  alum,  is 
dyed  with  fustic,  or,  on  the  Continent,  with  weld.    The  green  cloth  used  for  covering 
Inlliard-tables  and  other  furniture  is  dyed  in  the  following  manner : — A  weak  decoc- 
tion of  fustic  is  prepared,  and  into  this  some  Saxony  blue  is  poured,  while  there  is 
next  added  alum  and  cream  of  tartar.    The  woollen  fabric  is  immersed  in  the  bath 
and  boiled  for  two  hours.    It  is  next  thoroughly  washed  and  brightened  by  being 
again  immersed  in  a  dye-beck  filled  with  a  fresh  fustic  decoction,  to  which  a  smaller 
quantity  of  Saxony  blue  has  been  added.    All  kinds  of  woollen  tissues,  worsted,  half- 
wool,  alpacas,  delaines,  &c.,  may  be  dyed  green  by  means  of  lo-kao  (Chinese  green), 
and  iodine  green. 
KiMdBiMdM.      Mixed  shades  are  produced  on  the  fabrics  by  means  of  cochineal, 
madder,  French  fustic,  fustic,  in  a  manner  similar  to  that  used  for  dyeing  green. 
BiMk  Djn.     Excepting  only  aniline  black,  all  black  dyes  may  be  considered  as  combi- 
nations of  iron  with  tannic  or  gallic  acid ;  but  the  best  and  fastest  blacks  on  broadcloth 
are  such  as  have  as  a  first  dye  either  madder  or  indigo.    The  wooUen  goods  are  mor- 
danted with  sulphate  of  iron  (green  copperas)  and  dyed  by  immersion  in  a  decoction  of 
logwood,  galls,  sumac,  &c.    The  so-called  S6dan  black  (this  town  is  celebrated  for  its 
cloth  manufacture)  is  produced  by  dyeing  the  doth  blue  with  woad,  when  after 
careful  washing  the  cloth  is  placed  in  a  dye-beck  contaiaing  water,  sumac,  and  log- 
wood, and  is  boiled  for  some  three  hours,  after  which  sulphate  of  iron  in  a  solution 
of  known  strength  is  added.    This  operation  is  repeated  until  the  cloth  has  assumed 
■  an  intensely  Uack  colour.    Half-fast  black  colours  are  produced  on  doth  by  dyeing 


6o6  CHEMICAL  TECHNOLOGY. 

them  blue  with  Prussian  blue,  after  which  the  operation  just  desoibed  is  gam 
through.  Common  black  is  produced  by  dyeing  with  logwood,  sumac,  some  faaie, 
and  a  mixture  of  green  and  blue  vitriol.  Chromium  black,  invented  by  Leykanf  il 
Nuremberg,  is  obtained  in  the  following  manner : — ^The  cloth  is  mordanted  with  a 
solution  of  bichromate  of  potash  and  cream  of  tartar,  after  which  it  is  dyed  in  s 
decoction  of  logwood.  The  so-called  pyrolignite  of  inm  (crade  aoetate  of  ina 
prepared  from  scraps  of  old  iron  and  crude  acetic  add)  is  now  veiy  generally  used  •• 
a  mordant  instead  of  the  green  copperas.  This  acetate,  also  known  as  black  or  iraa 
liquor,  is  prepared  on  the  large  scale  and  sold  as  a  liquid  at  a  sp.  gr.  of  1*09  to  1*14. 

White  doth.  This  doth,  in  use  especially  for  military  uniforms,  is  obtained  by  iint 
thoroughly  washing,  fulling,  and  carefully  sulphuring  the  cloth,  which  is  neii 
passed  through  a  bath  containing  chalk  and  a  small  quantity  of  size,  after  whieh 
it  is  dried,  beaten,  and  well  brushed. 

BOk  Dyaitts.  Silk  is  usually  dyed  in  skeinB  unspun,  but  having  been  first  deooiti- 
oated,  that  is  to  say,  deprived  of  the  layer  of  gummy  matter  which  forms  ihe  onter 
covering  of  cocoon  silk.  It  is  then  scoured,  bleached,  and  sulphured ;  the  latter  oolj 
when  the  silk  is  to  be  dyed  with  very  bright  colours  and  delicate  light  hnes.  Silk  is 
dyed  in  cold  dye  solutions.    It  is  dyed  black  by  any  of  the  following  proceasea: — 

1.  Logwood  and  iron  mordant ; 

2.  Logwood  and  bichromate  of  potash ; 

3.  Galls  and  other  substances  containing  tannic  acid  with  iron  salts  as  mordant; 

4.  With  aniline  black,  according  to  the.redpes  of  Persoz,  jun.,  and  others,  by  tlit 

use  of  chromate  of  copper  and  oxalate  of  aniline. 

The  first  and  second  are  simply  known  as  ordinary  blacks,  while  the  third  a 
known  as  fast  black.    The  ordinary  black  is  obtained  by  simply  mordanting  the  oik 
with  nitrate  of  iron,  and  then  dyeing  it  in  a  decoction  of  logwood.    This  cheap  d/e 
is  more  particularly  applied  to  light  silken  fiabrics.    The  colour  is  reddened  even  I7 
weak  acids,  such  as  lemon  and  orange  and  other  fruit  juices.    The  feist  black  is  fu 
more  expensive,  but  it  is  not  affected  by  weak  adds,  while  it  affords  the  additiooal 
advantage  of  largdy  increasing  the  wdght  of  the  dlk  (in  raw  state  as  well  as  in  Bpsn- 
yam  silk  is  sdd  and  bought  by  weight),  as  this  textile  fibre  absorbs  from  6oU>8ik 
and  even  100  times  its  own  weight,  and  silk  used  for  shoe-laces  even  225  per  cent  d 
the  dye  material.    When  desired  the  silk-dyer  has  to  return  for  100  lbs.  of  raw  sift 
from  160  to  180  or  200  lbs.  weighted  black-dyed  silk.    In  Germany  an  indigenosB 
gall,  locally  known  as  Knoppem,  French  avllandei^  containing  some  30  to  50  pere«iit 
of  tannic  acid,  is  used  in  the  extract  to  dye  silk  black.      In  England  nut-gaOs 
imported  from  the  Levant  are  employed  for  this  purpose.    Although  the  increaae  0 
weight  of  the  silk  by  black  dydng  is  advantageous  to  the  dealers,  the  depositioii « 
80  much  foreign  matter  in  the  fibre  of  the  silk  not  only  injures  its  wearing  qualities, 
but  also  gives  rise  to  the  disagreeableness  of  the  dyeing  coming  off  while  the  ms^ 
rial  is  being  worn.    Microscopic  research  has  proved  that  the  dye  adheres  vety 
loosely  to  the  silk.    The  process  of  dyeing  silk  black  with  galls  is  very  simple.  T^ 
fibre  is  first  steeped  in  a  solution,  or  rather  infusio-decoction,  of  galls,  teehnieellf 
known  as  "  galling,"  after  which  the  silk  is  placed  in  a  sdution  of  nitrate  of  iroB- 
This  black  is  sometimes  dyed  on  silk  previously  dyed  with  Prussian  blue,  but  ftr 
more  frequently  a  bluish  shade  is  given  to  black  by  first  dyeing  the  silk  with  14^ 
wood,  copperas,  and  some  sulphate  of  copper. 

A9  regards  the  wdghting  of  the  silk,  it  is  essentially  due  to  the  £act  thai  flQk  ** 


DYEING.  607 

an  animal  prodnct,  has  the  property  of  combining  with  tannic  acid  and  thereby 
becoming  heavier.  The  burger,  therefore,  the  qnantity  of  tannic  acid  contained  in 
the  dye-bath,  or  the  oftener  the  galling  of  the  silk  is  repeated,  the  heavier  the  fibre 
VTill  become  within  certain  limits.  It  is  not  quite  indifferent  whether  a  per-salt  or  a 
proto-salt  of  iron  be  employed,  the  former  being  preferable.  The  previously  galled 
silk  becomes,  when  passed  through  a  solution  of  a  per-salt  of  iron,  at  once  coloured 
black ;  but  when  it  is  passed  through  a  solution  of  a  proto-salt  of  the  same  metal,  the 
silk  becomes  at  first  coloured  only  black- violet,  and  gradually  deep  black  by  exposure 
to  air.  Although  in  every  case  the  result  is  the  same,  the  use  of  a  per-salt  is  advan- 
tageous, and  becomes  necessary  with  a  small  quantity  of  tannic  acid,  while  for  a 
heavy  weighting  of  the  silk,  the  proto-salt  of  iron  only  can  be  employed.  It  is  stated 
that  the  dyeing  pf  silk  with  aniline  black  by  means  of  chromate  of  copper  and  oxalate 
of  aniline  yields  excellent  results.  Silk  is  dyed  blue  either  with  indigo,  Berlin  blue, 
logwood,  or  aniline  blue.  The  indigo  vat  has  not  been  much  used  for  imparting  a  blue 
colour  to  silk  since  the  discovery  of  fixing  Prussian  blue  upon  silk ;  and  if  indigo 
18  used  at  all  it  is  as  indigo  carmine,  or  the  so-called  distilled  blue,  purified  sulphin- 
digotic  acid.  In  order  to  dye  silk  with  Prussian  blue,  it  is  first  immersed  in  a 
solution  of  nitrate  of  iron.  This  salt  is  generally  in  use  in  England,  while  in  France 
a  persulphate  of  iron  made  by  dissolving  green  copperas  in  nitric  acid  is  employed, 
and  known  under  the  name  of  Baymond's  solution,  the  blue  produced  being  termed 
Raymond's  blue;  Napoleon  blue  is  produced  by  the  addition  of  a  tinsalt  to  the  iron 
bath,  foUowed  by  treatment  with  a  solution  of  ferrocyanide  of  potassium  acidulated 
with  sulphuric  acid.  The  latter  blue,  more  brilliant  than  the  former,  is  usually 
prepared  in  England,  a  tinsalt  being  invariably  added  to  the  iron  mordant  The 
mordanted  silk  is  next  passed  through  a  boiling  soap-solution,  then  washed,  and  next 
steeped  in  a  solutioii  of  ferrocyanide  of  potassium  acidulated  with  hydrochloric  acid. 
The  brilliancy  of  the  djed  silk  is  greatly  enhanced  by  passing  it  through  water  con- 
taining ammonia.  Dyeing  silk  with  aniline  or  naphthaline  blue  is  a  very  simple 
process,  it  being  only  necessary  to  put  the  silk  into  a. solution  of  the  dyes, 
the  solvent  being  alcohol  or  wood-spirit,  or  in  the  case  of  soluble  aniline  blue, 
water.  The  silk  is  left  in  the  solution  until  it  has  assumed  the  desired  hue.  Until 
the  discovery  of  fnchsin,  silk  was  always  dyed  red  and  pink  by  means  of  cochineal, 
safflower  (carthamine),  and  archil ;  but  now  silk  is  generally  dyed  with  fuchsin, 
eoralUne,  and  Magdala  red  (naphthaline  red).  The  process  is  as  simple  as  that 
just  described  for  aniline  blue.  Aniline  red  is  the  brightest,  purest,  and  deepest  of 
aU  red  dyes  for  silk,  but  it  is  not  so  fast  as  Magdala  red.  Archil  is  still  largely  used, 
but  aniline  violet  or  mauve  is  in  close  competition  with  it.  Yellow  is  produced  upon 
silk  by  first  mordanting  with  alum  and  dyeing  in  a  decoction  of  weld,  to  which,  if  it 
be  desired  to  impart  an  orange  hue,  some  annatto  is  added,  or,  preferably,  Man- 
chester yellow.  By  cautious  treatment  with  nitric  add  silk  may  be  dyed  yellow, 
some  xanthroproteic  acid  being  formed,  while  without  any  mordant  picric  acid  pro- 
duces a  bright  lemon-yellow  on  silk,  the  colour  becoming  deeper  by  treatment  with 
alkalies.  Ordinary  green  is  produced  upon  silk  by  dyeing  it  yellow  by  means 
of  either  weld,  quercitron,  fustic,  or  picric  acid,  and  then  dyeing  it  blue  with  indigo- 
carmine,  aniline  blue,  or  sulphindigotic  acid.  Fast  green  is  obtained  by  dyeing  the 
silk  blue  with  BUu  Raymond^  and  next  treating  it  with  fustic.  During  the  last  few 
years  aniline  green  (emeraldine)  has  been  generally  used  for  dyeing  silk  green.  Lilac 
IS  produced  upon  silk  by  means  of  aniline  violet,  archil,  or  logwood  and  tinsalt. 


6o8  CHEMICAL  TECHNOLOGY, 

Calico  Dyeinff.  Cottoii  is  dyed  either  in  yam  or  woTen  fabric,  but  more  genenlly  as 
yam.  Cotton  is  far  more  difficult  to  dye  than  wool,  and  requires,  espeeiaUr  fer 
obtiiiiiiug  fast  colours,  stronger  mordants.  Blue  is  produced  upon  oottoo  (olieo  it 
is  termed  in  fabric)  by  means  of  the  copperas-yat  (see  Indigo) ;  further  by  BerHn  or 
Pmssian  blue,  logwood,  and  green  copperas ;  and  finally  by  being  passed  through  a 
solution  of  oxide  of  copper  in  ammonia ;  the  fibre,  yam,  or  tissue  exhibiting  after 
drying  a  beautiful  bright  blue  colour.  Yellow  is  produced  with  Avignon  berries* 
weld,  fustic,  quercitron,  annatto,  acetate  of  iron  (nankeen),  and  chrome^yeHoir. 
Green  is  obtained  by  the  copperas- vat  followed  by  dyeing  with  fustic.  Brown  is 
produced  with  a  salt  of  iron  and  with  quercitron  or  madder,  or  simply  by  means  of 
hydrated  oxide  of  manganese.  Black  is  either  fast,  aniline  black,  or  is  produced  by 
dyeing  blue  by  the  aid  of  the  copperas- vat,  next  mordanting  with  acetate  of  iron,  asd 
then  dyeing  in  a  bath  consisting  of  galls  and  logwood.  The  aniline  colours  can  be 
fixed  upon  cotton  only  by  the  aid  of  a  specific  mordant — a  solution  of  tannin  in 
alcohol ;  or  tlie  fibre  of  cotton  is  first  animalised,  as  it  is  termed ;  that  is  to  aaj, 
impregnated  with  either  albumen  or  casein,  the  fibre  being  to  a  certain  extent  made 
similar  to  that  of  wool  or  silk  and  rendered  absorbent  of  aniline  dyes.  Cotton  may 
be  mordanted  with  Gallipoli  oil,  or  with  soft-soap  for  certain  dyes. 

As  regards  dyeing  cotton  and  calicos  red,  madder  is  the  cliief  dye  material*  while 
probably  at  no  distant  period  artificial  alizarine  from  anthracen  will  become  an  importaat 
material.  We  distinguish  between  ordinary  red  and  Turkey,  sometimes  tensed 
Andrinople  red ;  the  former  is  produced  upon  cotton  goods  mordanted  with  acetate 
of  alumina  (commonly  called  red  hquor  or  red  mordant) ;  the  latter  is  obtained  by 
complicated  manipulation,  the  rationale  of  which  is  not  quite  elucidated  by  science. 

Tnrk«7  Red.  This  beautiful  and  very  fast  red,  improved  by  washing,  is  produced  by 
the  following  distinct  operations : — ^The  well-bleached  cotton  goods  are  first  padded 
in  a  mixture  of  GaUipoli  oil  and  pearl-ash  containing  about  200  lbs.  of  oil,  40  Ifas.  of 
pearl-ash,  and  100  gallons  of  water,  a  quantity  sufficient  for  about  4000  yards  of 
calico.  The  pieces  are  next  exposed  to  air  in  summer  and  to  the  heat  of  a  stove  ia 
cold  weather  for  twenty-four  hours ;  then  padded  again  in  a  mixture  of  oil,  potash, 
and  water,  and  again  dried  and  exposed,  and  so  on  for  as  many  as  eight  different 
treatments  for  dark  colours.  The  excess  of  oil,  or  rather  that  which  has  not  suffered 
change  by  oxidation,  and  the  alkali  are  now  removed  by  steeping  in  an  alkaline  fluid, 
and  the  pieces  well  washed.  The  next  process  is  the  galling  and  aluming ;  60  lbs. 
of  ground  nut-galls  are  exliausted  with  hot  water,  and  to  this  liquor  are  next  added 
I20  lbs.  of  alum  and  10  lbs.  of  acetate  of  lead,  after  which  the  liquor  is  made  up  to 
I20  gallons.  The  pieces  are  padded  in  tiiis  liquor,  dried,  and  aged  three  days,  ^en 
fixed  by  passing  in  warm  water  containing  ground  chalk,  being  next  washed  and 
dyed  in  madder  mixed  witli  a  little  sumac  and  with  blood.  For  dark  shades  of 
colour  the  fabrics  undergo  another  galling  and  aluming  after  dyeing,  and  are  thes 
aged,  fixed,  and  dyed  a  second  time.  After  this  last  operation  the  goods  exhibit  a 
very  heavy  brown-red  colour,  and  they  are  brightened  by  two  or  three  soapings  or  a 
passage  in  dilute  nitric  acid.  In  other  processes  sheeps'  and  cows'  dung  are  mixed 
with  the  oil  and  other  modifications  introduced.  Garancine  is  largely  used  in  Turkey- 
red  dyeing.  By  its  use  the  operations  of  clearing  and  brightening  {avivage)  have 
been  much  shortened.  All  that  has  been  suggested  as  regards  the  ratiottale  of  the 
Turkey-red  dyeing  process,  and  more  especially  as  regards  the  action  of  the  Gallipoli 
oil  (huile  toumante,  an  inferior  kind  of  olive  oil  which,  when  mixed  with  a  weak 


PRINTING  OF  WOVEN  FABRICS.  609 

solution  of  pearl-ash,  should,  if  of  proper  quality,  form  a  perfect  emnlsion,  which,  after 
twenty-four  hours*  standing,  should  not  exhibit  any  globules  of  oil  floating  on  tlie 
eiir€ace),i8not  sufficiently  substantiated  to  afford  a  secure  basis  for  further  reasoning. 
i>7«iiic  LiiMn.  Linen  is  dyed  by  processes  similar  to  those  in  use  for  cotton,  but  owing 
to  the  peculiar  structure  of  the  flax  fibre,  its  affinity  for  dyes  is  much  lower  than  that 
of  cotton. 

The  Pbtntimg  of  Woven  Fabhiqs. 

'■^*5&rtcr**^"  This  very  important  branch  of  the  dyer's  art  aims  at  producing 
coloured  patterns  upon  calico,  linen,  and  woollen  and  silk  tissues.  Calico  printing  is 
the  most  important  portion  of  this  industry,  which  is  based  upon  the  same  principles 
as  dyeing,  but  is  in  the  practical  execution  far  more  difficult,  partly  because  the 
colours  have  to  be  applied  to  certain  portions  only  of  the  fabric,  while  others  either 
remain  colourless  or  are  discharged,  partly  also  because  it  frequently  happens  that 
many  colours  have  to  be  applied  close  to  each  other.  The  colours  employed  in  calico 
printing  are  of  two  different  kinds ;  first,  such  as  are  directly  applied  to  the  cloth  by 
the  aid  of  blocks  or  plates  upon  which  the  patterns  and  designs  to  be  produced  upon 
the  calico  are  engraved — ^to  the  colours  thus  applicable  belong,  also,  the  ochres, 
Serlin  blue,  madder-lake,  indigo,  cochineal,  and  most  of  the  tar  colours ;  secondly, 
the  other  kind  of  colours  are  such  as  are  produced  by  immersing  the  calico  printed 
with  various  mordants  in  dye-baths — ^madder,  cochineal,  logwood,  weld,  sumac,  cutch, 
Ac.,  belong  to  this  category. 

There  exist  various  methods  of  printing,  of  which  the  following  are  the  chief : — 

1.  From  the  thickened  and  mordanted  colours. 

2.  The  thickened  mordant  only  is  applied  by  means  of  engraved  copper  cylin- 

ders to  the  cloth,  which,  after  the  mordant  has  been  thoroughly  fixed,  is  put 
into  the  dye-beck. 

3.  The  entire  piece  of  cloth  is  either  mordanted  or  a  colour  is  printed,  while  to 

such  portions  of  tiie  cloth  as  are  to  remain  white  or  are  intended  to  be 
afterwards  of  another  colour  or  colours,  or  pattern,  a  resist  is  applied, 
sometimes  printed  from  blocks,  or  more  frequently  from  cylinders,  the  effect 
being  that  on  the  portions  of  the  cloth  thus  protected  the  dye  does  not 
become  fixed. 

4.  Coloured  patterns  may  be,  and  in  practice  are,  largely  produced  by  first 

dyeing  the  mordanted  cloth   (calico  nearly  always  requires  a  mordant) 

uniformly  with  one  colour,  and  removing  this  colour  in  certain  portions 

of  the  cloth  by  what  are  technically  termed  discharges,  that  is  to  say, 

chemicals  which  destroy  the  dye. 

In  order  to  fix  certain  kinds  of  colours  they  have  to  be  submitted  to  the  action  of 

steam  (steam  colours);  while  such  inorganic  substances  as  ultramarine,  emerald 

green,  &c.,  or  among  the  semi-organic,  the  lakes  of  madder  for  instance — which  are 

applied  mechanically  by  the  aid  of  albumen,  caseine,  gluten,  and  also  require  for 

fixing  the  aid  of  steam — are  technically  termed  surface-printed  colours. 

MoriaiiAi.  The  mordanta  employed  in  calico  printing  are  chiefly  such  salts  as  are 
comparatively  loose  combinations  of  acid  and  base,  so  that  the  latter  can  readily  unite 
with  the  fibre.  Among  the  mordants  chiefly  used  the  acetates  of  alumina  (see  p.  263) 
and  iron  occupy  a  first  place,  while  alum  or  a  solution  of  aluminate  of  soda  is  more 
rarely  used.    Acetate  of  lead  is  the  mordant  for  producing  chromate  of  lead ;  various 

3  A 


6x0  CBEmCAL  TECHNOLOGY. 

combinations  of  tin  (see  p.  75)  are  also  employed  as  mordants.    The  applicatinn  sf  a 
mixture  of  caseine  and  lime  has  been  recently  proposed  as  a  mordant;  fiir  tUs 
purpose  caseine,  technically  known  in  England  as  lactarine,  and  prepared  hvan  mSk, 
(of  which  it  is  the  curd),  is  dissolved  in  dilute  caustic  ammonia,  and  the  solntioQ  Ibi 
obtained  is  mixed  with  freshly  prepared  milk  of  lime.    The  caaeine-lime  mixtizt  a 
used  for  steeping  the  cloUi  intended  to  be  dyed ;  the  caseine-lime  beoomes  inanlMfe 
by  the  application  of  heat,  after  which  the  fabric  is  so  thorou^j  mordanted  IhitiS 
resists  washing  with  alkaline  fluids.    In  order  to  prevent  the  stifihess  of  the  di& 
when  the  caseine-lime  is  used  as  a  mordant,  it  has  been  suggested  to  mix  the  in^ 
previous  to  its  application  to  the  woven  fEibrio,  with  some  GaUipoli  oil ;  the  edieas 
to  which  this  mordant  is  applied  behave  as  regards  the  dyes  like  wool,  and  nai% 
take  the  seme  colours.    Cheese,  which  does  not  contain  too  much  fiit,  or  skim-iaik 
cheese,  when  digested  with  ammonia,  produces  a  solution  which  can  be  uaed  insteal 
of  caseine.    Tannic  acid,  albumen,  dried  white  of  eggs  re-dissolved  in  water,  md 
vegetable  gluten  are  used  as  mordants  in  calico  printing. 

TbkkMingt.  In  order  to  give  the  colours  or  mordants  used  in  printing,  eitiicrbf 
block  or  cylinder,  a  sufficient  consistency,  they  are  mixed  with  what  are  technically 
known  as  thickenings.  As  such  are  used: — Senegal  g^nm,  tragacanth,  I^ocone. 
British  gum,  dextrine,  salep,  flour,  gluten,  pipe-day  with  gum,  glue  and  size,  snlpibale 
of  lead,  sugar,  molasses,  glycerine,  starch,  sometimes  diloride  and  nitrate  of  zzne. 
The  purity  of  the  colours  and  mordants  depends  in  a  great  measure  upon  the  qjuJstf 
of  the  thickenings.  British  gum,  prepared  from  starch,  is  most  frequently  used.  JU 
regards  the  selection  of  the  tliickening,  it  should  be  borne  in  mind  that  mrj  add 
mordants  cannot  be  mixed  with  starch,  because  it  loses  its  consistency  with  aadi; 
while  again,  some  metcdlic  preparations— for  instance,  basic  or  sub-acetate  of  lead, 
solutions  of  tin,  nitrate  of  iron,  and  of  copper^— cause  gum  to  coagulate,  and  hence  gna 
should  not  be  used  as  a  thickening  with  these  substances. 

B«dati,<»B«senrei.  Afl  already  stated,  there  is  used  in  calico  printing  a  oompositiaa 
which,  on  being  implied  to  the  clotli,  prevents  the  deposition  or  fixing  of  coJour  to 
the  portions  of  the  doth  where  the  resist  composition  is  placed,  the  result  beiag 
that  tliese  portions  are  left  white.  Most  frequently  the  resist  is  employed  with  the 
view  of  preventing  the  fixation  of  indigo  to  ceitain  portions  of  the  cloth,  so  that  it 
remains  wliite  where  the  resist  has  been  applied.  The  resists  are  composed  of  pastj 
exdpients,  such  as  pipe-clay,  fat,  oil,  sulphate  of  lead,  to  which  are  added  and  with 
which  are  incorporated  substances  which  readily  yield  oxygen,  for  instance,  sulphate, 
nitrate,  and  acetate  of  copper,  or  a  mixture  of  red  prussiate  of  potash  (ferricyanide  of 
potassium),  and  caustic  soda  solution.  In  some  instances  resists  are  composed  so 
that  they  act  as  a  mordant  (alumina  or  iron  mordants)  for  other  dyes,  the  portions  of 
the  cloth  protected  by  the  resist  from  contact  with  indigo,  and  left  white,  being  dyed 
by  immersion  in  a  dye-beck  containing  another  dye-stuff,  which  may  be  maddo-  or 
quercitron  bark.  This  kind  of  printing  is  sometimes  termed  lapig^  in  consequence  of 
the  remote  similarity  which  some  of  these  patterns  bear  to  lapis  lazuli.  The  so- 
called  white  resist  for  cylinder  printing  consists,  as  an  example,  of  acetate  or 
sulphate  of  copper,  acetate  of  lead  thickened  with  gum,  or  dextrine  solution.  This 
composition  having  been  printed  by  means  of  the  cylinders,  the  pieoes  are  the  next 
day  put  into  the  indigo- vat  and  kept  there  until  the  desired  depth  of  colour  has  been 
obtained,  after  which  tliey  are  passed  through  a  bath  containing  dilate  Bulphniie 
add  until  the  places  where  the  resist  has  been  applied  have  beccme  white.    The 


PRINTING  OF  WOVEN  FABRICS.  6ix 

rationale  of  this  process  is  the  following : — ^As  soon  as  the  reduced  indigo  (white 
indigo)  in  the  vat  comes  in  contact  with  the  oxide  of  copper,  it  is  converted  at  the 
expense  of  the  oxygen  of  the  oxide  into  bine  indigo>  which  is  precipitated  in  insoluble 
state  on  the  resist.  By  the  treatment  with  dilate  sulphuric  acid  the  hydrated  sub* 
oxide  (red  oxide)  of  copper  is  dissolved,  and  with  it  the  indigo  blue  washed  oat. 

Instead  of  the  salts  of  copper  white  resists  are  used,  and  composed  of  bichloride  of 
mercury  and  sulphate  of  zinc ;  the  former  acts  in  a  manner  similar  to  the  salts  of 
copper,  while  the  latter  enters  into  an  insoluble  combination  with  the  reduced  (white) 
indigo,  which  is  precipitated  where  the  resist  has  been  applied. 

iHwiiMgM.      Discharges  are  for  the  purpose  of  producing  by  chemical  means  white 

patterns  on  certain  parts  of  the  dyed  cloth.    Tliis  end  may  be  attained  by  dissolving 

a  previously  applied  mordant  or — as  is  tlie  most  usual  method — ^by  destroying  or 

discharging  the  dye  which  has  been  distributed  over  the  whole  surface  of  the  doth. 

As  regards  the  first  method,  certain  acids — ^phosphoric,  arsenic,  lactic,  oxalic,  hydro- 

fluosilicic  acids — are  made  to  combine  with  the  base  contained  in  the  mordant; 

-while   for  the  purpose   of  discharging  the  previously  applied  colour,  there  are 

used  such  substances  as  bleaching-powder,  chromic  acid,  a  mixture  of  red  prus- 

siate  of  potash  and  caustic  soda-ley,  permanganate  of  potash,  a  paste  composed 

of  bromine  mixed  with  water  and  pipe-clay,  nitric  acid,  &c.      All  these  agents  have 

an  oxidising  efiect,  whereas  protochloride  of  tin  and  protosulphate  of  iron,  also  used 

for  this  purpose,  acting  by  absorbing  oxygen,  are  reducing  substances.    Among  the 

AddMMiMttKM.    acids,  tartaric  acid  is  generally  used  for  the  purpose  of  discharging 

alumina  and  oxide  of  iron  employed  as  mordants ;  sometimes  tliis  acid  is  mixed  with 

bisulphate  of  soda.*    A  piece  of  cloth  dyed  red  or  blue,  to  which  is  in  certain  parts 

applied  a  mixture  of  tartaric  acid,  pipe-clay,  and  gum  (the  latter  as  thickening 

to  give  consistency),  becomes  immediately  bleached  when  the  doth  so  prepared  is 

immersed  in  a  solution  of  bleaching-powder. 

^^^^mSLuSS!*^  ^  ^^^  fluoride  of  potassium  has  been  used  as  a  discharge  for 
Berlin  blue.  The  discharging  of  indigo  blue  by  oxidising  agents  is  due  to  the  for- 
mation of  isatine  from  the  indigo  blae,  the  former  being  soluble,  the  latter  insoluble 
in  water,  so  that  the  soluble  substance  can  be  removed  by  washing : — 

Ci6HioNaOa+20  =  CxeHxoNaO^. 

Indigo  blue.  Isatine. 

Indigo  is  discharged  by  chromic  acid,  employed  in  practice  as  bichromate  of 
potash,  the  add  being  reduced  while  giving  off  oxygen  to  chromic  oxide.  More 
recently  Mercer  has  proposed  to  bleach  goods  dyed  with  indigo  by  the  application  of 
a  mixture  of  potash  and  ferricyanide  of  potassium ;  for  this  purpose  the  indigo-dyed 
doth  is  soaked  in  a  solution  of  red  prussiate  of  potash,  and  then  caustic 
potash  thickened  with  British  gum  is  printed  on.  The  potash  converts  the 
ferricyanide  into  ferrocyanide,  and  by  the  oxygen  thus  set  free  the  indigo  blue  is 
coverted  into  isatine : — 
Ferricyanide  of  potassium,  4K3FeCy6 


^^\A  (  Ferrocyanide  of  potassium,  4K4FeCy6. 
^^^  I  Isatine.  Cx6HxoNa04aHaO. 


Caustic  potash.  4KOH 
Indigo  blue,  CxeHioNaOs 

^•'^JjAwiitiM  Protochloride  of  tin,  known  as  crystals  of  tin  and  as  tinsalt,  is  the 
most  important  of  the  reducing  agents  applied  to  goods  dyed  with  oxide  of  iron. 
When  the  protochloride  is  placed  in  contact  with  oxide  of  iron,  the  result  is  the  for- 
mation  of  readily  soluble   protochloride,   which  is  removed  by  washing,  while 


6x3  CHEMICAL  TECHNOLOQT. 

simnlfaneoTisly  there  is  deposited  on  the  fibres  of  the  cloth  stanmc  acid  (more  cor- 
rectly proto-peroxide  of  tin),  which  may  serve  as  a  mordaat  for  red  and  yellow  dysa 
OftUoo  Printiof.      Calioos  may  be  printed  by : — 

1.  Dyeing  in  the  dye-beck. 

2.  By  block  or  cylinder  printing  (topical  colonr-printiiig). 

3.  By  resist  or  discharge  printing. 

In  the  process  of  dyeing  in  the  dye-beck  (madder  style)  the  thioTwrned  xaor- 
dant,  to  which  usually  some  faint  colonring  matter  is  added  for  the  purpoee  d 
recognition  (the  reader  should  bear  in  mind  that  the  mordants  are  ooik>iiileaa 
or  at  least  nearly  so),  the  pattern  produced  on  the  white  calico  is  impriatei 
by  the  aid  either  of  blocks  or  cylinders,  upon  which  the  desired  patten  is 
engraved. 

The  process  of  block  printing  takes  place  upon  a  table  over  which  a  pieee  of  flnA 
woollen  cloth  is  stretched.  The  cahco  to  be  printed  is  laid  on  this  doth,  and  by  te 
aid  of  blocks  the  mordant  is  transferred  to  the  calico.  The  blocks,  made  of 
wood,  box- wood,  or  fir- wood,  have  the  pattern  engraved  en  relief,  or  wrought  by 
of  brass  wires  fastened  in  the  wood  in  such  a  manner  as  to  form  a  certain  figure.  The 
former  blocks  are  called  engraved,  the  latter  dotted  or  stippled  blocks,  wiiile  in  bodk 
cases  the  two  methods  are  used  simultaneously.  In  order  to  distribute  the  mordmt 
uniformly  a  frame  or  chase  is  employed,  on  which,  by  means  of  nails,  a  stout  piece  d 
canvas  is  stretched,  the  frame  being  made  to  float  on  the  top  of  a  thick  acdmAm 
of  gum  or  linseed  mucilage,  placed  in  a  suitably  constructed  vessel.  On  a  frazne  t 
piece  of  oil-cloth  is  fastened  to  prevent  percolation  of  the  fluid ;  next  the  mordfliit  is 
brushed  over  the  cloth  of  the  frame  quite  uniformly.  The  printer  puts  his  block  on 
the  cloth  thoroughly  moistened  with  mordant,  so  that  the  projecting  engraved 
portions  of  the  block  become  uniformly  moistened,  and  the  block  having  been  trus- 
ferred  to  the  calico  is  pressed  thereon,  the  pressure  aided  either  by  a  smart  bkrr 
given  by  the  printer's  fist  or  by  a  wooden  mallet*  care  being  taken  to  print  every 
portion  of  the  engraving  equally  on  to  the  woven  fabric.  When  several  mofdauli 
are  placed  on  to  the  frame  by  the  aid  of  separate  brushes  and  thence  printed  oo  tD 
the  cloth,  the  result  is  the  production  of  the  so-called  iris  or  fondu  prints.  In  order 
to  accelerate  the  operation  of  printing,  machinery  is  now  usual — ^for  instance,  the 
Perrotine,  invented  by  Perrot,  at  Rouen,  in  1833.  This  machine  works  witk 
three  to  four  wooden  formes  (Perrotine  formes  upon  which  the  patterns  are  £B»tened  \sj 
nails),  these  patterns  being  cast  in  a  manner  similar  to  stereotype  plates,  oonsasting 
of  a  readily  fusible  metallic  alloy.  The  arrangement  of  this  machine  is  of  comse 
such,  that  the  formes  are  as  wide  as  the  cloth  intended  to  be  printed.  Instead  of  this 
machine  cylinder  printing  has  become  general.  The  cylinders  are  made  of  copper, 
and  on  these  the  pattern  is  engraved.  The  cylinders  are  revolved  in  a  firameworkliy 
means  of  macliinery.  By  the  aid  of  a  wooden  cylinder  covered  with  doth  whidi 
dips  into  the  vessel  containing  the  mordant,  the  copper  cylinder  is  fed  with  monlaiit 
while  a  kind  of  blunt  knife,  known  technically  as  the  doctor,  scrapes  off  from  the  noa* 
engraved  portion  of  the  copper  cylinders  any  superfluous  cdour,  which  is  thus  oqd- 
fined  to  the  engraved  portion  forming  the  design. 

Before  the  mordanted  cloth  can  be  dyed  it  has  to  be  kept  for  some  time  is 
order  that  the  alumina  and  iron  mordants  may  combine  intimatdy  with  the  fibre  of 
the  doth.  Moreover,  the  cloth,  before  being  immersed  in  the  dye-beck,  has  lo 
undergo  the  operation  technically  known  as  deansing ;  that  is  to  say,  after  the 


PRINTING  OF  WOVEN  FABRICS.  6x3 

dant  has  become  dry,  the  ^ckening  and  faint  colouring  matter  have  to  be  removed, 
together  with  any  mordant  uncombined  with  the  fibre.     For  goods  intended  to 
be  madder  dyed  the  cow-dung  bath  is  required.   Usually  some  chalk  is  added  for  the 
purpose  of  saturating  the  acetic  acid  or  the  mordant.    Although  all  calico  printers 
agree  that  the  cow-dung  bath  is  necessary,  tlie  rationale  of  the  action  of  this  bath  has 
not  as  yet  been  explained.    According  to  Mercer  and  Blyth.  for  cow-dung  may  be 
subetituted  certain  phosphates  and  arseniates,  and  these  chemists  propose  the  use  of 
phosphate  of  soda  and  phosphate  of  lime.     More  recently  silicate  of  soda  has 
been  used  instead  of  cow-dung.    In  England  cow-dung  is  no  longer,  or  at  least  only 
very  rarely,  used.  After  the  goods  have  been  treated  with  cow-dung  or  its  substitutes, 
they  are  washed  and  then  dyed.    In  the  case  of  dyes  the  colouring  matter  of  which 
JB  readily  soluble  in  water,  infusions  or  decoctions  are  used ;  cochineal,  quercitron 
bark,  weld,  safflower,  &c.,  are  thus  used.    But  other  dyes,  the  colouring  principle 
of  which  is  less  readily  soluble,  such  as  madder  and  garancine,  are  put  with 
hot  water  into  the  dye-beck  in  which  the  mordanted  goods  are  immersed.     It 
JB  clear  that  when  several  different  mordants  have  been  printed  on  to  the  doth, 
several  different  colours  can  be  obtained  by  the  same  dye  material.    With  madder, 
for  instance,  all  shades  of  pink  and  red,  black,  brown,  violet,  and  lilac  can  be  pro- 
duced when  alumina  and  iron  mordants  and  mixtures  of  these  have  been  us^d 
as  mordants.    As  the  dye  only  takes  where  the  mordant  has  been  applied,  it  can 
be  readily  removed  from  the  other  portions  of  the  cloth ;  this  removal  of  superfluous 
dye  is  effected  by  washing,  treating  with  bran  and  soap,  and  grass  bleachmg  opera- 
tions, technically  termed  clearing.    In  some  cases  madder-dyed  goods  are  cleared 
^th  the  aid  of  solutions  of  bleaching-powder  or  Javelle  ley  (see  p.  223).    Some  dyes 
require  in  order  to  become  bright  and  brilliant  the  operation  known  as  avivage  or 
clearing,  but  of  a  special  nature ;  this  is  more  particularly  applicable  to  Turkey-red 
dyed  goods,  which  after  removal  from  the  dye-beck  are  submitted  to  a  boiling  under 
pressure  with  soap-suds  and  chloride  of  tin. 

Topia^erBufBMOoioan.  The  proccss  of  applying  thickened  colours  and  mordants 
simultaneously  is  known  as  topical  or  surface  printing,  the  colours,  pigments,  being 
termed  topical  or  surface  colours.  Of  these  two  varieties  are  known,  one  of  which 
is  printed  in  the  state  of  solution,  becoming  gradually  fixed  and  insoluble  on  the  fibre 
itself;  the  other  is  applied  in  the  insoluble  state  with  thickening  and  plastic 
substances,  by  the  aid  of  which  the  colours  adhere  to  the  fibre,  so  that  by  simple 
washing  they  are  not  removed — ultramarine  is  applied  in  this  manner.  Many  of  these 
styles  of  printing  require  for  fixing  as  well  as  for  clearing  the  application  of  steam, 
from  which  they  derive  their  name  of  steam  colours,  now  very  extensively  used. 
The  printed  goods  are  dried  for  two  or  three  days,  and  next  stretched  on  frames,  and 
thus  arranged  exposed  to  the  action  of  steam  at  100'',  in  properly  constructed  rooms. 
The  length  of  time  this  operation  is  continued  depends  in  practice  upon  several  con- 
ditions, and  varies  in  different  establishments,  but  is  generally  twenty  to  farty-five 
minutes  at  a  time.  The  precise  action  of  the  steam  is  not  well  known.  China  blue, 
deriving  its  name  from  a  resemblance  to  the  colour  of  old  china  ware,  is  produced  by 
a  veiy  complex  process,  of  which  the  following  is  a  brief  outline.  The  indigo  in  its 
natural  state  is  very  finely  ground  and  mixed  with  deoxidising  bodies,  such  as 
sulphate  of  iron,  acetate  of  iron,  orpiment,  or  protochloride  of  tin,  and  thus  applied  to 
the  cloth ;  the  goods  thus  printed  are  aged  and  afterwards  dipped  into  clear  lime- 
water;  this  serves  to  "wet  out'*  and  to  form  an  insoluble,  or  at  least  dificultly 


6i4  CHEMICAL  TECHNOLOGY. 

soluble,  compound  of  the  gum  paste  or  starch  of  the  thickening  with  the  lime.  Tha 
piece  is  next  placed  in  the  copperas  vat  for  ten  minutes,  the  lime-water  vfakh 
adheres  to  the  cloth  precipitating  a  little  oxide  of  iron  over  its  whole  smface.  bat  it 
does  not  appear  that  the  slightest  dissolution  or  deoxidation  takes  place.  Hie  piece 
is  now  taken  to  the  lime  vat  again,  in  which  it  is  gently  moved  about ;  by  this  ope*- 
tion  the  indigo  is  deoxidised  and  dissolved,  but  does  not  spread  beyond  the  desi^ 
for  the  reason  that  it  is  surrounded  with  fibres  saturated  with  water  and  coo^lated 
gum,  while  by  the  excess  of  lime  present,  the  solubility  of  the  deoxidised  indigo  is 
greatly  lessened.  The  piece  is  again  dipped  into  the  copperas  vat  and  again  into  the 
lime  vat  several  times,  the  last  dip  being  in  lime  for  a  long  time.  The  goods«  thickly 
coated  with  a  cream  of  lime,  are  put  into  clean  water,  and  afterwards  into  a  dilate 
acid,  then  washed  and  cleared  in  weak  soap  and  warm  weak  acid.  China  blue  is  a 
^ast  colour,  but  very  dark  shades  cannot  be  obtained  by  this  process.  whi<3li  is  rather 
costly  on  account  of  the  time  and  labour  it  requires.  Steam  blue  is  obtained  by 
printing  with  a  solution  of  ferrocyanide  of  potassium  thickened  with  atarcli, 
acidulated  with  tartaric  acid  and  a  small  quantity  of  sulphuric  acid,  after  which  the 
calico  is  dried,  aged,  and  lastly  steamed.  Yellow  is  produced  by  first  traatiqg 
the  goods  with  acetate  of  lead,  and  next  passing  them  through  a  solution  of  biduomate 
of  potash.    Green  is  produced  with  a  mixture  of  chromate  of  lead  and  Berlin  blue. 

DfiMhtfi c  styi*.  As  employed  in  practice  on  the  large  scale,  the  term  dischaige  is 
given  to  a  composition  which  has  the  power  of  bleaching  or  discharging  the  dys 
already  communicated  to  a  fabric.  The  discharging  of  mordants  by  the  aid  «f 
agents — chiefly  acids — which  dissolve  or  otherwise  render  ineffective  the  constitiieDti 
of  the  mordants,  seldom  occurs  in  practice,  and  only  then  a  few  special  styles.  As 
a  rule,  discharge  is  effected  with  uniformly  dyed  goods,  more  especially  indigo  and 
Turkey-red  dyed  fabrics,  upon  which  it  is  desired  to  produce  white  pattcfrns ;  labile 
sometimes  upon  a  portion  of  the  white  ground  thus  obtained  other  colours  are  produced. 
The  agents  used  to  produce  the  discharge  vary  with  the  dye  which  has  been  applied  as 
well  as  with  the  colour  afterwards  desired  to  be  produced  on  the  white  ground, 
while,  moreover,  the  discharge  ought  not  to  injure  the  fibre  of  the  cloth.  Oxalic, 
tartaric,  citric,  more  or  less  dilute  sulphuric  and  hydrochloric  adds,  bisulphate 
of  potash,  nitrate  of  lead,  solutions  of  bleaching-powder,  weak  chlorine  water,  and 
bichloride  of  tin  are  used,  being  properly  thickened  with  suitable  materials,  while 
some  ore  so  contrived  as  to  serve  as  mordants  for  colours  to  be  subsequently  applied; 
for  instance,  for  blue,  a  mixture  of  tartaric  acid,  Berlin  blue,  tineudt,  farina,  and 
water,  is  used ;  for  yellow,  nitrate  of  lead  with  tartaric  acid,  starch,  and  water ;  fact 
green,  a  mixture  of  yellow  and  blue;  for  black,  a  logwood  decoction  to  whidi 
nitrate  of  iron  has  been  added.  The  pieces  thus  prepared  (these  discharges  having 
been  printed  on)  having  been  put  into  and  passed  through  a  solution  of  chloride 
of  lime,  the  dye  previously  applied  is  destroyed  where  the  discharge  is  printed,  and 
in  its  stead  the  new  colour  is  produced  according  to  th&pfkttem.  Chromic  acid,  or  an 
acidulated  solution  of  bicromate  of  potash,  is  sometimes  used  as  a  discharge, 
the  oxide  of  chromium  produced  yielding  a  brown  colour. 

ABfline  Prtiitisg.  As  regards  the  application  of  these  colours  to  calico  printing  they 
may  be  tenned  steam  colours.  The  printing  and  fixing  is  effected  by  the  following 
methods : — i.  The  thickened  mordant  is  printed  on,  and  next  fixed  either  by  diying 
or  by  ageing  and  steaming  after  drying,  the  fabric  being  dyed  in  a  solution  of  the 
anihne  colour  (red,  violet,  blue),  the  colour  becoming  fixed  to  the  mordanted  poitioBi 


PRINTING  OF  WOVEN  FABRICS.  615 

only  of  the  calioo.  2.  The  thickened  mordant  is  mixed  with  the  aniline  dye,  and 
thus  printed,  and  the  fixing  effected  by  steaming.  The  mordants  for  these  colours 
are : — Dried  albumen,  blood  albumen,  viz.,  tliat  bleached  by  the  action  of  ozone 
obtained  by  means  of  oil  of  turpentine;  vegetable  gluten  in  various  forms,  for 
instance,  that  dissolved  according  to  W.  Crum's  plan  in  weak  caustic  soda  ley,  or 
iiccording  to  Scheurer-llott  in  a  weak  acid,  or  gluten  dissolved  in  saccharate  of  lime 
according  to  Li^s-Bodard,  or  finally  gluten  dissolved  by  incipient  putrefaction,  as 
suggested  by  Hanon.  Instead  of  gluten  caseine  may  be  used  dissolved  either  in 
caustic  ley  or  in  acetic  acid ;  glue  and  tannate  of  glue  are  also  used  (Kulilmann  and 
Ijightfoot).  Other  mordants  for  these  colours  are  tannin,  fiat  oils,  and  preparations 
tliereof,  as  oleo- sulphuric  acid,  palmatino-  and  glycerin-sulphuric  acid.  Further, 
certain  resins,  among  which  shellac  dissolved  in  borax  is  one. 

Gluten  is  largely  obtained  as  a  by-product  of  the  preparation  of  starch  from 
'wheaten  or  other  flour.    When  required  for  use  as  a  mordant,  the  gluten  is  allowed 
to  remain  in  moist  state,  and  by  incipient  putrefaction  becomes  sour,  and  hence  fluid. 
The  mass  is  purified  by  first  treating  it  with  carbonate  of  ^oda ;  5  kilos,  of  the  sour 
gluten  require  for  saturation  about  560  grms.  of  a  carbonate  of  soda  solution  at 
i'i5  sp.  gr.,  whereby  the  gluten  is  again  rendered  insoluble,  and  after  having  been 
-washed  is  re-dissolved  in  caustic  soda  ley,  5  kilos,  of  the  gluten  requiring  435  grms. 
of  a  caustic  soda  solution  at  1*080  sp.  gr.    This  solution  is  next  diluted  with  3*5  litres 
of  water.    The  fluid  is  printed  on  the  calico,  which  is  next  dried,  aged,  and  steamed, 
after  which  it  is  rinsed  in  water  and  dyed  in  a  solution  of  the  aniline  colour.    The 
gluten  is  sometimes  mixed  with  the  aniline  colour  and  printed  on  with  it,  after  which 
the  calico  is  steamed  a  first  time,  then  washed,  and  steamed  a  second  time.    Gluten 
may  be  used  without  the  preparation  with  carbonate  of  soda  by  leaving  it  to  putrefy 
until  it  has  become  tery  fluid ;  it  is  then  mixed  with  about  one-third  of  its  weight  of 
caustic  soda  solution  of  the  above  i'o8o  sp.  gr.    When  caseine  (lactarine,  it  is  tech- 
nically termed  in  England)  is  used  for  mordanting  calico  previous  to  the  application 
of  aniline  dyes,  it  is  dissolved  in  caustic  soda,  and  after  the  calico  has  been  printed 
with  this  mixture  the  aniline  colour  is  printed  on. 

The  method  of  printing  with  aniline  colours  as  devised  by  (3)  Gratrix  and  Javal, 
di£fers  considerably  from  the  preceding,  and  consists  (a)  in  preparing  an  insoluble 
compound  of  the  aniline  colour  with  tannic  acid,  which,  having  been  thickened  with 
Senegal  gum,  is  printed  on  to  the  cloth  which  has  been  previously  mordanted  with 
tinsalt  or  any  other  suitable  mordant;  or  (/3)  there  is  printed  on  the  previously 
animalised  cotton,  tliat  is  to  say,  cotton  mordanted  with  albumen,  lactarine,  or 
gluten,  or  cotton  mordanted  with  tinsalt,  a  thickened  decoction  of  galls,  by  which  in 
the  first  place  a  tannate  of  albumen,  &c.,  in  the  second  one  of  tin,  botli  insoluble  in 
water,  are  formed.  The  calico  having  been  dried  is  tlien  passed  through  an 
acidulated  aniline  solution.  The  aniline-tannin  compound  mentioned  under  (a)  is 
prepared  by  adding  to  an  aniline  solution  as  much  decoction  of  galls  (better  still 
solution  of  tannin)  as  is  required  for  the  complete  precipitation  of  the  dye  material. 
This  precipitate  is  collected  on  a  filter,  washed,  and  dissolved  in  alcohol  or  acetic 
acid,  and  having  been  thickened  with  gum.  Uie  solution  is  used  for  printing.  When 
printed  the  goods  are  steamed  and  washed  either  with  or  without  soap,  according  to 
the  shade  which  it  is  desired  to  give  to  the  colour.  A  red  colour  requires  a  soap- 
Wash.  According  to  tlie  second  method  the  calico  is  treated  with  a  solution  of  stan- 
nate  of  soda,  after  which  a  thickened  solution  of  tannin,  or  a  tannin-containing 


6i6  CHEMICAL  TECHNOLOGY, 

material  is  printed  on  to  the  cloth,  wliich  is  steamed  and  the  mordant  foither  fiiei 
The  dyeing  operation  \f\  carried  on  in  a  dye-beck  used  as  for  madder,  the  beds  bemg 
filled  with  water,  acidulated  with  acetic  acid,  and  heated  to  50"*.  The  cloth  is  pot 
into  this  liquid,  and  gradually  the  dye  dissolved  in  acetic  acid  ia  added,  \nien  tb 
requisite  quantity  of  the  dye  has  been  added,  the  contents  of  the  dye-beck  ar«  betted 
to  the  boiling-point.  Aniline  black  is  produced  (see  p.  579)  npon  the  cloth  byiDeaBi 
of  chlorate  of  potash,  chloride  of  copper,  ferricyanide  of  ammoninm.  or  fresh^  pre- 
cipitated sulphuret  of  copper.  Naphthykmin  violet  (see  p.  583)  is  now  prodaoedbj 
a  similar  process. 

HotpraMinff,  piniihing.  The  printed,  washed,  and  rough-dried  cotton  goods  an  not 
and  DreadnK.  finished,  that  is  to  say,  starched,  dried,  often  calendered,  hot-pi€a«d, 
folded,  and  again  pressed.  In  England  these  operations  form  a  distinct  branch  of  tbf 
dyeing  art  usually  not  periormed  by  the  printers.  For  chintz  white  wax  is  added  to  thf 
hot  starch  in  order  to  impart  a  better  gloss.  In  order  to  give  mushna  a  somewhat  Tclwtj 
appearance  spermaceti  is  added  to  the  starch  while  being  boiled  with  water. 
^  Printing  Liaen  Ooodi.  Linen  goods  are,  as  a  rule,  neither  dyed  nor  printed,  and  onlr  •  fev 
indigo-dyed  articles  on  which  white  patterns  are  produced  are  in  the  trade.     As  regsrds  tks 

Printing  Woollen  Goods,  printing  of  woollen  goods,  flauoels  more  particularly,  block-pziatiBg 
is  most  frequent.  The  goods  are  mordanted  with  chloride  of  tin.  The  fixing  of  voassd 
the  colours  imparted  to  woollen  goods  is  effected  by  steaming.  We  distinguish,  moreorv, 
in  the  printing  of  woollen  goods — i.  Golgas  printing ;  and  (2)  Berill  printing.  As  RS*'^ 
the  former  method,  now  almost  obsolete,  the  golgas,  a  very  thm  and  Ijight  flannel  fsbrie,  ii 
first  mordanted  with  alum  and  cream  of  tartar,  and  next  placed  between  woodoicr 
leaden  plates  partly  perforated  with  a  pattern,  and  strongly  pressed  in  a  pceoHsH; 
constructed  hydraulic  press,  where  it  is  possible  to  force  dye  solutions  through  Uie  goodi. 
which  are  only  wetted  by  these  solutions  and  consequently  dyed  where  the  dye  liquor  eu 
pass  through,  the  strong  pressure  preventing  the  liquid  running  over  the  fiumd  d 
any  other  direotion.  By  the  berill  printing  process  the  surface  colours,  thickened  vith 
starch,  are  printed  on  to  the  flannel  with  hot  brass  formee ;  the  starch  not  being  remofcd, 
the  result  is  the  formation  of  relieved  and  coloured  patterns.   The  processes  and  metbods 

prtnung  Silk  oooda.  of  printing  sllk  goods  are  generally  the  same  as  for  calicos ;  either  nr- 
faoe  printing  is  resorted  to  with  fixing  by  steam,  or  various  mordants  are  printed  00  to 
the  nlk,  which  is  next  dyed  in  the  dye-beck.  A  peculiar  kind  of  printing  on  silk  is  bued 
upon  the  property  of  nitric  acid  producing  upon  silk  a  permanent  yellow  odour,  as  veil  m 
of  destroying  most  other  dyes,  and  yet  acting  on  resins  and  fatty  substances  only  slovlf. 

M udaiin  Printtng.  This  mode  of  printing  on  silk  is  termed  mandarin  printing,  tad  th* 
tissue,  chiefly  silk  handkerchiefs,  to  which  it  is  applied,  mandarins.  In  order  to  etch  «iu 
nitric  acid  on  the  indigo-dyed  silk,  there  is  printed  on  to  it  a  resist,  composed  of  resm  am 
fat,  after  which  the  tissue  is  kept  for  2  to  3  minutes  in  a  mixture  of  z  part  of  water  sm 
2  parts  of  nitric  acid  heated  to  50°.  The  goods  are  then  thoroughly  rinsed  in  fresh  vs^ 
and  boiled  in  a  soap  solution,  to  which  carbonate  of  potash  is  added.  The  portions  of  »# 
silk  where  no  resist  has  been  placed  are  thus  made  beautifully  yellow. 

Banrttnat.  Qu  genuine  madder-red  dyed  silk  white  patterns  are  etched  by  a  f^^^ 
similar  to  that  just  described  for  golgas  printing.  The  goods  are  placed  between  lew 
plates  in  which  the  pattern  is  cut  out,  and  then  submitted  to  strong  hydraulic  P'^^^^* 
next  a  solution  of  bleaching-powder  acidulated  with  some  sulphuric  acid  is  forced  thnnxgft 
the  goods,  by  which  the  madder  dye  is  destroyed.  The  pattern  thus  etched  may  be  aft^ 
washing,  the  pressure  remaining  and  water  being  forced  through,  dyed  yellow  by  vaA 
forcing  a  solution  of  acetate  of  lead  and  next  one  of  chromate  of  potash  throng  tbs 
woven  fabrics^  kept  of  course  in  the  press. 


(6x7) 


DIVISION  vn. 

THS  MATEBIAL8  AND  ABPABATUS   FOB  PBODUOINa  ABTIFICIAL  LIGHT. 


*****«J}^3Jjf***<»  Veiy  few  among  the  large  nmnber  of  bodies  which  at  a  high  tem- 
perature,  either  by  combustion  or  at  a  red  heat,  evolve  a  permanent  light  are  suited 
for  use  as  materials  for  artificial  illumination.  The  number  of  bodies  which  comply 
with  the  conditions  demanded  in  artificial  illumination  is  very  small.  These  condi- 
tions are  the  following:— > 

I.  That  by  the  combustion  of  the  body  a  sufficient  degree  of  heat  be  evolved  to 
wrmif^faLlTi  the  combustion.  2.  That  when  the  burning  body  happens  to  be  solid,  it  be 
previous  to  the  combustion  converted  into  gas  or  vapour,  as  otherwise  no  flame  is 
generated,  which  is  absolutely  required  fgr  the  purpose  of  illumination.  3.  That  the 
burning  body  evolve  in  the  flame  solid  bodies  or  very  dense  vapours  as  an  essential 
condition  of  the  illuminating  property  of  the  flame.  4.  That  either  the  body  itself  or 
the  raw  material  from  which  it  is  obtainable  be  present  in  large  quantity  and  be 
readily  obtainable.  5.  That  the  products  of  combustion  be  gaseous  and  harmless  to 
the  health. 

It  is  a  generally  known  fact  that  any  great  accumulation  of  heat  imparts  to  bodies 
the  property  of  emitting  light.  This  is  more  conspicuous  in  solid  and  fluid  bodies, 
because  their  molecules  are  placed  more  closely  together  than  happens  to  be  the  case 
with  gases  and  vapours.  At  a  temperature  of  500°  to  600°  a  solid  body  becomes 
red-hot,  while  at  about  1000°  white  heat  occurs.  A  gaseous  body  heated  to  these 
degrees  of  temperature  emits  only  a  very  feeble  light.  In  order  to  render  a  gaseous 
body  (and  as  already  mentioned  only  gaseous  bodies  are  suited  for  illuminating 
purposes)  luminous  during  its  combustion,  it  should  contain  the  vapours  of  some  of 
the  higher  hydrocarbons  (for  instance,  benzol,  acetylen,  naphthaline,  &c.),  and  that 
these  by  becoming  white-hot  should  yield  light,  or  that  there  be  present  in  the  flame, 
by  itself  non-luminous,  a  solid  body  which  is  thus  rendered  white-hot ;  for  instance,  a 
spiral  platinum  wire  in  a  hydrogen  flame,  a  piece  of  caustic  lime  in  the  oxy -hydrogen 
flame,  a  cylindrical  piece  of  zircona  or  magnesia  in  a  hydrogen  or  coal-gas  flame 
fed  by  oxygen,  oxide  of  magnesium  in  the  flame  of  burning  magnesium  (magnesium 
l^ght),  solid  phosphoric  acid  in  the  flame  of  burning  phosphorus,  &c.  Leaving  out  of 
the  question  for  the  present  such  lights  as  are  not  generally  available,  as  those  just 
ftlluded  to,  and  also  the  electric  light,  it  is  clear  that  for  all  practical  purposes  we 
can  avail  ourselves  of  only  such  materials  for  illuminating  purposes  as  yield  a  flame 

3B 


6x8  CHEMICAL  TECHH0L0G7. 

which  emits  light  in  consequence  of  the  Taponn  of  heavy  hydrocarbons  ynsei 
therein.  These  hydrocarbons  are  indeed  contained  in  all  the  substances  wldcli  ii« 
either  used  for  illuminating  purposes  or  from  which  illuminating  materials  tie 
prepared,  as,  for  instance,  taUow,  palm  oil,  and  the  flatty  acids,  viz.,  stearic  kA 
palmitic,  wax,  spermaceti,  pai*affin.  rape-seed  oil,  the  various  paraffin  and  petnlaa 
oils,  campliine  (highly  rectified  oil  of  turpentine),  coals*  bituminous  schists,  bo^ioi 
coal,  wood,  fats,  and  resins.  • 

name.  Every  solid  and  fluid  body  which  becomes  either  volatilised,  or  deeoB- 
posed  into  gaJseous  matter  at  a*  temperature  below  that  required  for  its  eoimbmiti& 
can  bum  only  in  the  shape  of  gas.    The  ensuing  light  is  what  we  call  flame. 

The  well-known  shape  of  flame  is  due  to  the  pressure  of  the  ambient  air,  beeaase 
the  latter,  becoming  heated  and  being  rendered  specifically  lighter,  ascends.  ^1m 
the  illuminating  material  consists  of  molten  paraffin^  stearic  add,  or  oil  (oolza,  npe- 
seed,  or  petroleum),  it  is  sucked  upwards  in  the  interstices  of  the  wicks  Mtiog^s 
capillaiy  tubes,  and  in  the  immediate  neighbourhood  of  the  flame  these  substaaeea  are 
converted  into  gases  and  vapours,  the  nature  of  which  closely  agrees  to  that  of  poiiM 
illuminating  gas. 

Sir  Humphry  Davy  was    the  first  to   elucidate  the  nature  of  flame  tnd  Ibi 

cause  of  its  luminosity  as  well  as  of  the  unequal  luminosity  of  diflSerent  hads  d 

flames.    In  our  day  the  researches  of  Hilgard,  H.  Landolt,  Pitschke,  Bloefanani. 

Eersten,  and  more  particularly  of  H.  Deville,  Volger,  Lunge,  Dr.  Frankland,  aal 

others,  have  greatly  contributed  to  our  knowledge  of  flame.    When  closely  dbaim^ 

we  can  distinguish  in  flame  three  distinct  portions,  viz. : — (i)  an  outer  lnminoii8l>|'> 

or  so-called  veil;  (2)  a  central  nucleus,  which  is  red-hot;  and  (3)  am  inner  and  kw 

portion,  in  which  the  gaseous  substances  about  to  become  ignited  are  heated.   I^ 

opinion  formerly  held  about  the  cause  of  the  emission  of  light  by  flame  was  that  kf 

the  combined  action  of  a  very  high  temperature  and  the  oxygen  of  the  atmospben. 

w]iich  first  combines  with  the  hydrogen,  carbonaceous  matter  is  separated,  vkkk 

being  heated  to  a  bright  white  heat  emits  light.    By  the  researches  made  hjWff^ 

on  the  flame  of  burning  candles,  and  of  Landolt  and  H.  Deville,  who  experimo^ 

with  a  gas-flame,  we  have  been  taught  that  a  veiy  quick  and  rapid  diffusion  d  tf 

and  the  products  of  combustion  takes  place,  and  that  in  the  interior  of  the  fiaaa^ 

decrease  of  the  quantity  of  the  combustible  gases  and  an  increase  of  the  ^odndi « 

combustion  occurs.    But  all  these  researches  do  not  enable  us  to  explain  misy^ 

the  most  ordinary  phenomena  observed  in  luminous  flames.    We  do  not,  for  exai^ 

know  what  relation  tliere  exists  between  the  chemical  composition  of  an  iQunuDi^ 

substance  and  its  illuminating  power ;    consequently,  gas  analyses  mads  for  ^ 

purpose  of  testing  gas  are  in  that  respect  of  very  little  value.    Acoordxng  to  dx 

researches  of  O.  Eersten,  confirming  those  of  O.  L.  Erdmann,  the  atmosphesic  exjg* 

combines,  at  least  in  gas  flames,  first  with  the  suspended  particles  of  free  carbon  tf" 

next  with  tiie  hydrogen.    Tlie  combustion,  Eersten  states,  does  not  take  place  ia^ 

centre  of  the  flame,  but  only  at  the  veil  and  that  portion  of  the  luminous  Dttf*^ 

which  is  nearest  to  the  veil,  because  we  cannot  admit  tliat  any  trace  of  oxygen  ea 

pass  through  a  layer  of  red-hot  hydrogen  and  carbon.    The  products  oteomho^ 

observed  in  the  centre«of  the  flame  are  not  formed  tliere,  but  have  been  carried  dMi* 

by  diffusion.    The  total  heat  of  the  flame  is  consequently  derived  from  the  hnit  * 

the  zone  of  combustion.    The  temperature  of  the  centre  of  the  flame  and  of  tkf 

mantle  increases  of  course  towards  the  top,  and  henee  the  most  luminous  poitiflB^ 


ARTIFICIAL  LIGBT.  619 

the  flame  is  that  where  the  carbon  is  separated  by  the  intense  heat,  below  the  thin 
layer  of  tlie  dark  central  cone.  Higher,  where  the  heat  which  decomposes  the 
hydnnsarbons  into  their  constituents  reaches  upwards  to  the  middle,  the  entire 
centre  is  luminous,  and  hence  a  solid  flame  is  exhibited.  As>  then,  the  free  carbon 
comes  nearer  to  the  layer  rich  m  oxygen,  it  is  converted  into  cai'bonic  acid,  and  is 
the  more  luminous  tlie  more  energetic  this  combustion.  In  the  veil  oxide  of  carbon 
and  hydrogen  bum  simultaneously.  The  reason  why  this  veil  does  not  exhibit  at 
its  lower  part  a  luminous  mantle  is  because  the  mass  of  the  gases  in  the  interior  is 
too  cold  for  admitting  a  separation  of  hydrocarbons. 

The  non-luminosity  of  a  flame,  even  that  of  pure  defiant  gas,  due  to  the  too 
contracted  space  occupied  by  the  temperature  of  the  veil,  may  be  observed  when  a 
gas  flame  is  turned  down  as  low  as  possible ;  in  this  case  a  complete  combustion 
takes  place  before  any  decomposition  can  ensue,  just  as  happens  in  the  lower  blue 
portion  of  a  luminous  flame.  The  luminosity,  therefore,  depends  upon  the  composi- 
tion of  the  gas  before  it  is  burnt,  and  not  upon  a  subsequent  combustion  of  the 
carbon.  It  has  been  assumed  that  the  luminosity  of  gas  flames  is  due  to  the 
momentarily  eliminated  particles  of  solid  carbon  becoming  white-hot;  but 
according  to  Dr.  Frankland's  researches,  made  in  1867,  it  is  not  the  particles  of  solid 
carbon,  but  rather  the  dense  vapours  of  the  higher  hydrocarbons,  those  having 
a  high  boiling-point,  which,  while  ignited  at  an  elevated  temperature,  cause  the 
luminosity  of  the  gas  flame.  There  are  present  in  illuminating  gas  compounds  of 
great  density,  which  in  the  state  of  vapour,  simOar  to  what  may  be  observed  of  the 
vapour  of  arsenic,  may  render  flame  luminous ;  among  these  are  the  vapours  of 
benzol,  naphthaline,  and  probably  of  many  other  of  the  constituents  of  coal-tar.  These 
vapours  remain  in  the  flame  in  undecomposed  state  up  to  the  moment  that  they  reach 
the  outer  layer  or  envelope  of  the  flame,  where  they  become  consumed  when  coming 
in  contact  with  tlie  oxygen  of  the  air.  It  has  been  customary  to  adduce  as  a  proof 
that  the  luminosity  of  the  flame  is  due  to  eliminated  particles  of  carbon,  the  fact  that 
when  a  piece  of  porcelain  is  held  in  the  flame  carbon  is  deposited  thereon ;  but  it  has 
not  been  proved  that  this  substance  is  pure  carbon;  on  the  contrary,  when  the 
deposit  is  submitted  to  analysis,  it  is  always  found  to  contain  hydrogen,  and  any 
chemist  who  desires  to  obtain  pure  carbon  from  lamp-black  knows  well  enough  that 
this  substance  has  to  be  strongly  ignited  in  dose  vessels  before  all  the  hydrogen  it 
contains  has  been  eliminated.  In  order  to  accelerate  this  process  of  purification, 
chlorine  gas  is  passed  over  the  lamp-black  placed  in  a  combustion-tube,  or  better,  a 
porcelain  tube,  and  raised  to  nearly  a  white  heat.  Lamp-black  is  probably  nothing 
more  than  a  conglomerate  of  the  densest  light-emitting  hydrocarbons,  the  vapours  of 
which  become  condensed  upon  the  surface  of  the  cold  porcelain.  How  could  a  flame 
be  so  transparent  as  it  really  is  were  it  filled  with  solid  particles  of  carbon?  How 
could  it  be  the  same  for  photometrical  assays  if  the  flame  be  placed  with  its  broad  or 
nanow  edge  towards  the  photometer  if  the  light  of  the  flame  were  due  to  solid 
particles  of  carbon  ?  It  is  possible  that  in  a  slight  degree  an  elimination  of  oarbon 
actually  takes  place  as  a  consequence  of  the  decomposition  of  hydrocarbons,  but  the 
main  source  and  cause  of  the  luminosity  of  a  gas-flame  is  the  combustion  of  the  heavy 
hydrocarbons.  It  is  clear  that  the  temperature  of  the  flame^has  some  influence  on 
its  luminosity.  According  to  H.  Deville's  experiments  (1869)  the  degree  of 
the  luminosity  of  a  flame  is  intimately  connected  with  the  density  of  the  vapours 
present  therein,  while  the  dissociation  does  not  appear  to  be  without  some  influence 


620  CHEMICAL  TECHNOLOGY. 

upon  the  condition  of  the  flame.  Under  ordinary  conditions  an  illmnittatiiig  matftial 
to  be  burnt  in  air  free  from  draughts,  and  so  that  no  smoky  flame  be  pfzodseei, 
should  contain  upon  6  parts  by  weight  of  carbon  i  part  by  weight  of  faydroga, 
as  nearly  obtains  in  olefiant  gas,  paraffin,  wax,  and  stearic  acid.  Oil  of  tnxpenliiie, 
which  contains  upon  i  part  by  weight  of  hydrogen  7*5  parts  by  weight  of  carboD, 
burns  with  a  sooty  flame.  This  is  the  case  in  a  higher  degree  with  hftnzol,  which 
upon  I  part  of  hydrogen  contains  12  of  carbon,  or  with  naphthaline,  in  which  fte 
proportion  is  i :  15.  In  order  to  bum  the  excess  of  carbon  (aa  already  stated, 
according  to  Dr.  Frankland's  researches,  this  is  not  pure  carbon,  bnt  a  ttfinglnnift- 
ration  of  dense  hydrocarbons)  which  becomes  eliminated,  an  increased  snpply  of 
air  is  required,  such  as  is  created  by  a  lamp-glass.  Such  flames  as  do  not  <*liinina*» 
carbon,  as,  for  instance,  those  of  marsh-gas  and  alcohol,  yield  only  a  &int  h^ 
when  burning.  The  luminosity  of  gas  is  at  once  destroyed  when  atmospheric  air 
is  mixed  with  the  gas,  as  may  be  observed  in  the  Bnnsen  burner ;  the  same  effMt 
obtains  when  the  gas  is  mixed  with  other  indifferent  gases  or  vapours. 

Artificial  light  is  prooured : — 

I.  From  sabstancf^B  solid  at  ordinary  temperatures,  and  prepared  in  the  shaiie  of 
candles  made  of  such  materials  as  tallow,  palm  oil,  stearic,  palmitic  and  elaidio  acids, 
wax,  spermaceti,  and  parafQji. 

n.  By  employing  fluid  substances,  chiefly  in  lamps,  and  which  may  be  hroaulit  to 
the  following  categories : — 

a.  Non-volatile  oils,  such  as  rape-seed,  olive  oil,  flsh  oiL 

b.  Volatile  oils  which  are  either — 

a.  Essential  oils,  as,  for  Instance,  eamphine  (refined  oil  of  turpentine) ;  <»r 
)3.  Mineral  oils,  obtained  from  tar,  from  peat,  lignite,  bituminous  slate,  ooghead  eoal, 
and  consisting  of  mixtures  of  fluid  hydrocarbons,  met  with  in  commerce  under  a 
variety  of  names,  such  as    solar  oil,  photogen,  ligroine,  keroeen,  p*'**!**!* 
oil,  &o, ;  or 
y.  Native  earth-oil  or  petroleum,  which,  after  havingbeen  refined,  is  sold  inEn^asd, 
commonly  under  the  name  of  petroleum  oil,  to  «iigtTn£rnfaVi  it  especial^  fnn 
Young's  patent  paraffin  oil. 
m.  By  means  of   gaseous    substances   obtained    by  the  diy  distillation  of  eoak, 
bituminous  slate,  peat,  wood,  petroleum  residues,  resins,  and  fatty  substances,  all  d 
which  when  submitted  to  a  high  temperature  above  a  cherry-red  heat,  become  deeon- 
posed,  yielding  a  solid  residue  rich  in  carbon  (ooke) ,  tar,  and  gases ;  or  again,  by  other  atodm 
of  treatment,  as  with  the  so-called  water-gas,  obtained  by  passing  steam  over  zed-Lst 
charcoal. 
In  the  gaseous  illuminating  substances  the  luminous  body  is  either : — 
a.  Yielded  by  the  flame  itself,  as  is  the  case  in  the  ordinaiy  gas  flame;  or. 
If,  Introduced  externally,  as  in  the  so-called  platinum  light,  by  the  aid  of  platioua 
wire ;  in  the  lime-light  by  means  of  lime ;  in  the  magnesimn-  and  aireoniuai* 
light  from  cylindrical  pieces  of  these  substances ;  or  by  the  so-called  earbmatioa 
of  the  gas  irith  the  vapours  of  fltiid  hydrocarbons, 

I.  Artificial  Light  obtained  by  Means  of  Candles. 

LUht  from  ouidi«s.  Leaving  out  of  the  question  the  use  in  some  very  poor  diatxieti  cf 
splints  of  resinous  wood  for  the  purpose  of  procuring  artificial  light,  candles  are  tke 
only  shape  in  which  solid  materials  are  employed  for  illuminating  puiposes.  A 
candle  consists  of  the  solid  illuminating  material,  palmitic  and  stearic  acids,  parrfhi, 
tallow,  or  wax,  cast  in  the  well-known  cylindrical  shape,  and  provided  in  tht 
direction  of  its  longitudinal  axis  with  a  cotton-wick,  the  thickness  and  plaitmg  cf 
which  should  be  arranged  in  proper  relation  to  the  diameter  of  the  candle.  W« 
describe  in  the  following  pages  the  manufacture  of: — 

1.  Stearine  candles.  3.  Tallow  candles. 

2.  Parafiin  candles.  4.  Wax  candles. 


ARTIFICIAL  LIGHT.  6ai 

ii«nfii^»»^tMiiiM  I,  Palm-oil  and  tallow  are  now  in  Europe  the  raw  materials 
for  the  mannfaotnre  of  these  candles,  while  lard  is  nsed  for  this  purpose  in  the 
United  States  (Cincinnati).  The  researches  of  W.  Heintz,  which  complete  those 
made  hy  Chevreul,  have  taught  us  that  these  fats  consist  of  palmitic,  stearic,  and 
oleic  acids,  and  glycerine.  The  acid  which  Chevreul  has  designated  as  margario 
acid  has  been  proved  to  be  a  mixture  of  palmitic  and  stearic  acids.  The  so-called 
**  stearine  candles  '*  are  frequently  made  of  a  mixture  of  stearine  (viz.,  a  mixture  of 
palmitic  and  stearic  acids)  and  soft  paraffin.  Candles  of  this  description  are  known 
abroad  as  Apollo  and  Melanyl  candles.  The  manufacture  of  stearine  candles 
consists  in  two  chief  operations,  viz. : — 

A.  The  preparation  of  the  fatty  acids ; 

B.  The  conversion  of  these  acids  into  candles. 

A.  The  preparation  of  the  fatty  acids  can  be  effected  by  saponification  with  lime, 
by  means  of  sulphuric  acid  and  subsequent  distillation,  by  means  of  water  and  high- 
pressure  steam,  and  by  means  of  steam  and  subsequent  distillation. 

''TS^JSiyLSef**"*  ^-  Saponification  of  the  FaU  by  Means  of  Lime. — ^The  raw 
fats  employed  in  tliis  operation  are  beef  or  mutton  tallow,  and  palm  oil.  Tlie 
mutton  taUow  contains  a  larger  quantity  of  solid  fi&tty  adds,  and  is  more  readily 
saponified,  but  beef  tallow  is  cheaper.  The  Kussian  tallow,  of  which  large  quantities 
are  met  with  in  commerce,  is  usually  a  mixture  of  beef  and  mutton  tallow.  As  palm 
oil  is  imported  into  Europe  in  large  quantities  and  is  comparatively  low  in  price,  it 
has  become  in  many  stearine  candle  manufactories  the  &.t  chiefly  used. 

Stearine  yields  957  parts  of  stearic  add  (melting  at  70**}  CigHjeOa. 
Palmitine  „  948  „  palmitic  add  „  62**  CieH^zOt. 
Oldne         „     903       „       oleic  add  „      —  la**  Ci8H340a. 

Stearine,  palmitine,  and  oleine,  are  glyeerides.  The  stearine  is  tri-stearine, 
C/57H1Z0O6 ;  palmitine  is  tri-palmitine,  C51H98O6 ;  and  oleine  is  tri-oleine,  C37H104O6. 
By  the  saponification  with  milk  of  lime,  the  caldum  salts  of  the  three  fatty 
adds,  stearic,  palmitic,  and  oleic,  are  formed,  and  glycerine  is  separated.  The 
operation  of  saponification  is  conducted  in  the  following  manner: — Of  taUow  or 
of  palm  oil  about  500  kilos,  with  800  litres  of  water  are  put  into  wooden  lead-lined 
▼ats  or  tuns,  of  20  hectolitres  cubic  capacity,  and  next  by  the  aid  of  steam  conveyed 
into  the  vessel  by  a  leaden  pipe  coiled  spirally.  IVhen  all  the  taUow  has  been 
melted  there  are  gradually  added  to  it  some  600  litres  of  milk  of  lime,  containing 
70  kilos,  of  lime  =  14  per  cent  of  the  weight  of  the  tallow,  care  being  taken  to  stir 
the  mixture  continuously.  After  heating  for  some  six  to  eight  hours  the  formation 
of  the  lime-soap  is  complete.  The  somewhat  yellow  glycerine  solution  is  run  off 
from  the  solid  granular  lime-soap  and  used  for  prepariq^f'  glycerine.  According  to 
theory,  starting  from  the  supposition  that  upon  3  molecules  of  fatty  adds  found  com- 
bined in  the  neutral  fat  there  is  i  molecule  of  glycerine,  100  parts  of  fat  would 
require  only  8*7  parts  of  caustic  lime,  but  in  practice  14  per  cent  of  lime  is  generally 
used  because  it  has  been  found  that  the  saponification  is  rendered  easier,  but  a  larger 
quantity  of  sulphuric  add  is  also  required.  • 

The  lime-soap  thus  obtained  is  decomposed  by  means  of  sulphuric  add,  dther  con- 
centrated, or  as  so-called  brown  or  chamber  add.  This  operation  is  carried  on  dther 
in  the  vessel  in  which  the  saponification  took  place,  or  in  a  similarly  constructed  vessel 


622  CHRMICAL  TECHS0L0G7. 

or  in  stoneware  basins,  also  fitted  with  a  steam- pipe.  The  qnantitj  of  snlphurie 
required  for  the  decomposition  of  a  mixture  composed  of  500  kilos,  of  tallow  and 
70  kilos,  of  lime  amoants  to  137  kilos.  The  acid  is  first  dilated  with  water  to  12*  B. 
=  sp.  gr.  I  086  (in  this  condition  the  acid  contains  30  per  cent,  HSSO4),  and  is  jmbsX 
poured  on  to  tlie  lime-soap,  with  which  it  is  thoroughly  stirred,  while  steam  heat 
is  applied  simultaneously.  When  the  fatty  acids  have  been  set  free  the  snppiy  d 
steam  is  shut  off,  and  the  fluid  mixture  left  for  some  time,  the  melted  €&tty  aodt 
rising  to  the  surface,  while  the  gypsum  settles  at  the  bottom  of  the  liquid.  The 
melted  fatty  acids  are  transferred  to  a  lead-lined  tank,  and  in  order  to  remore  the 
last  traces  of  lime  and  sulphate  of  lime,  first  washed  with  dilate  sulphuric  add,  aad 
next  with  water,  the  steam  heat  being  kept  up  to  maintain  the  acids  in  a  fluid  6tat& 
The  quantity  of  purified  fatty  acids  thus  obtained  is  the  following : — 

500  kilos,  of  tallow  459'5  kilos,  of  fatty  acids. 
500        »  ff       4630       .. 

500        «  »•       478*0 

500        ..  ..       487*5       .» 

2000  kilos,  of  tallow  1888-0  kilos,  of  fatty  adds, 

equal  to  94*8  per  cent.    The  yield  depends  on  the  kind  of  tallow  used,  an  its  potity, 
and  tlie  mode  of  operating  for  its  saponification. 
100  parts  of  tlxe  fatty  acids  give : — 

a.  43*3  parts  of  solid  fatty  adds 
^'  45*8       „  „         „       „ 

c.  4^*2       }»  »»         »»       »♦ 


d.  484 


i>  f»         f*       fi 


On  an  average  45*9  parts  of  a  mixtnre  of  fltearie 

and  palmitic  acid. 


When  the  fatty  acids  have  been  as  much  as  posdble  freed  from  lime,  gypsum,  and 
sulphuric  add,  by  means  of  repeated  washing  with  water,  tliey  are  kept  in  mohen 
condition  for  some  time  in  order  that  the  water  may  be  thoroogfaly  eliminatfd 
Next,  the  fatty  acids  are  cooled  and  become  solidified,  after  which  th^  are 
submitted  to  strong  hydraulic  pressure  in  order  to  remove  the  oldc  add,  this 
tion  being  repeated  and  then  performed  with  the  aid  of  heat.  The  adds  are  then 
into  large  square  blocks,  or  cooled  in  moulds  similar  in  shape  to  those  used  for  lai^ge 
cakes  of  chocolate,  and  capable  of  containing  2  kilos,  of  the  &tty  adds.  In  some 
works  moulds  made  of  enamelled  iron  are  used  for  this  purpose.  The  fsitty  adds  are 
left  in  these  moulds  for  the  purpose  of  crystallising  slowly ;  in  winter  twelve  hours, 
in  summer  twenty-four  hours,  are  required  for  attaining  this  end.  The  more  slowly 
the  crystallisation  proceeds  the  better,  because  the  more  readily  the  fluid  portioa  can 
be  separated  by  pressure  from  the  solid  mass.  The  solidified  mass  ia  nezi 
submitted  to  hydraulic  pressure,  in  order  to  eliminate  the  fluid  fatty  adds  retained 
between  the  crystals  of  the  solid  mass.  The  first  operation  of  pressing  is  peifanned 
at  the  ordinary  temperature.  The  solid  cake  of  the  flatty  acids  is  for  this  puipose 
put  into  a  press-bag,  which  may  be  made  of  any  strongly  woven  &bric,  horadiair 
doth  being  often  employed.  The  press-bag  having  been  filled  is  placed  betweoi 
plates  of  iron  or  zinc,  and  then  transferred  to  the  table  of  a  hydraulic  press,  capable 
of  exerting  a  pressure  of  200,000  kOos.  The  oleic  add  which  runs  off  is  odleeted  ia 
channels  and  thence  conveyed  by  a  pipe  to  a  cistern.  This  material  is  used  in  soap- 
making,  also  for  lubricating  wool,  and  more  recently  as  oldc  add  ether  mixed 
with  alumina  for  the  purpose  of  softening  leather.    When  the  hydraulic  praas  doss 


ARTIFICIAL  LIGHT.  623 

not  remove  any  more  fluid  from  the  solidified  crystalline  acids,  hot-pressure  is 
resorted  to.  For  this  purpose  hydraulic  presses  of  a  peculiar  constiiiction  and 
placed  in  a  horizontal  position  are  employed ;  the  arrangement  of  these  presses,  tlie 
plates  of  which  are  heated  by  means  of  steam  is,  however,  too  complicated  to  be  use- 
fully  described.  The  pressed  fatty  acids  are  next  purified.  This  is  efiected  by 
treating  them  in  a  molten  state  with  veiy  dilute  sulphuric  acid  (3°  B.  =  1*020  sp.  gr.), 
and  washing  them  with  water,  an  operation  repeated  two  to  three  times,  the  fatty  acids 
being  of  coiirse  kept  molten  all  the  time.  The  wash-water  to  be  employed  for  this 
purpose  ought  to  be  free  from  lime,  and  if  such  water  is  not  obtainable,  the  lime 
should  be  removed  by  means  of  oxalic  add.  The  purified  fatty  acids  are  next  main- 
tained in  a  molten  state  for  some  time,  in  order  to  eliminate  the  water  mechanically 
adhering  to  them.  Sometimes  the  fatty  acids  are  clarified  by  the  aid  of  white  of 
eggs  beaten  to  a  froth,  and  added  to  the  water  of  the  last  operation,  in  the  proportion 
of  2  eggs  to  100  kilos,  of  fatty  acids ;  or  the  stearic  acid  is  re-molten  in  water 
containing  oxalic  acid.  The  fatty  acids  thus  obtained  are  either  cast  into  thick 
slabs  and  thus  sent  to  the  candle  factory,  or  the  molten  acids  are  directly  converted 
into  candles. 

It  ia  evident  that  annually  a  large  quantity  of  worthless  gypsum  must  result  as  a  by- 
product of  the  decomposition  of  the  lime-soap  by  the  use  of  sulphurio  acid.  It  may 
therefore  be  worth  while  to  suggest  that  canstio  baiyta  ^ould  be  substituted  for  lime, 
because  by  the  deoomposition  of  the  baryta-soap  with  sulphuric  acid,  ^ere  would  be 
formed  baiyta  white  (sulphate  of  baiyta),  the  value  of  which  will  cover  the  expense  of  the 
sulphuric  add ;  but,  on  t3ie  other  hand ,  caustic  baryta  is  a  great  deal  more  expensive  than 
eaustie  lime.  It  is  ^e  that  the  sulphate  of  baryta  separates  more  readily  and  completely 
from  the  liquor,  and  a  purer  glycerine  can  be  obtained  from  it.  Cambaoere's  suggestion 
(1855)  to  saponify  with  alumina  was  made  with  the  view  of  obtaining  a  more  valuable  by- 
product. Alumina  does  not  saponify  fats,  but  aluminate  of  soda  (employed  for  the  purposes 
of  saponification  for  some  years  la  the  United  States  under  the  name  of  natrona  refined 
sapoxufier)  does  so,  the  resrUt  being  the  formation  of  an  alumina-soap,  while  the  soda  ii  set 
free  and  may  be  used  again  for  the  purpose  of  re-dissolving  fresh  portions  of  alumina.  As 
in  the  operations  made  with  the  native  minerals  cryolite  and  bauxite,  aluminate  of  soda  is 
obtained  as  an  intermediate  product,  which  may  be  further  treated  for  sulphate  of 
alumina  and  soda ;  the  proposal  to  use  an  alumina-soap  instead  of  a  lime-soap  deserves 
every  condderation,  the  more  so  as  the  fluid  obtained  by  the  deoompodtion  of  the 
alumina-soap  with  sulphuric  acid  may  be  directly  employed  for  the  preparation  either  of 
sulphate  of  alumina  or  of  alum.  The  alumina-soap  may  be  decomposed  at  the  ordinary 
temperature  by  acetic  'acid,  and  acetate  of  alununa  obtained  (see  p.  263).  The  lime 
saponification  process  has  been  in  a  great  measure  thrown  into  the  background  since  the 
invention  of  the  far  more  profitable  saponification  process  with  sulphurio  add  and  super- 
heated steam. 

"•'^lSTlS.'''"*  ^'  Saponification  Proceu  with  a  Smaller  Quantity  of  LivM  and 
the  Application  of  Superlieated  Steam. — De  MiUy  has  essentially  changed  the  pro- 
eess  of  the  saponification  of  the  neutral  fats ;  he  found  tliat  the  quantity  of  lime 
used  in  the  saponification,  which  in  his  works  at  Paris  had  been  already  diminished 
from  14  to  8  or  9  per  cent  of  the  quantity  of  the  fats,  could  be  decreased  even  to 
4  or  to  2  per  cent,  provided  the  mixture  of  lime-water  and  fatty  matter  was  heated  to 
a  higher  temperature  than  that  usually  employed.  De  Milly  put  into  a  steam  boiler 
2300  kilos,  of  tallow  and  20  hectolitres  of  milk  of  lime,  which  contained  either 
50  kilos,  of  lime  =  2  per  cent,  or  69  kilos.  =  3  per  cent,  after  which  this  mixture  was 
heated  to  172°  by  means  of  steam,  having  a  temperature  of  182''  =  10  atmospheres,  or 
150  lbs.  pressure  per  square  inch.  The  result  was,  that  after  seven  hours  the  saponi- 
fication was  complete,  the  contents  of  the  boiler  consisting  partly  of  an  aqueous 
solution  of  glycerine,  partly  of  a  mixture  of  free  fatty  acids,  and  a  small  quantity  of 
a  lime-soap.    The  boiler  having  been  emptied  was  again  filled,  and  the  operation 


624  CHEMICAL  TE0KK0L0Q7. 

repeated,  so  that  in  twenty-four  hours  6900  kilos,  of  tallow  could  be  qpented  upoi. 
It  is  evident  that  this  method  of  saponification  is  veiy  profitable,  in  conaequenee  of 
requiring  much  less  sulphuric  acid  for  decomposing  the  lime-soap. 

Several  opinions  have  been  enunciated  explanatory  of  this  process ;  but  if  we  tar 
in  mind  (z)  that  kind  of  action  which  Berzelius  designated  as  catalytic,  when  a 
comparatively  very  small  quantity  of  any  substance  may  call  forth  a  decompoaitiaB 
under  favourable  conditions  of  a  very  large  quantify  of  another  substance;  and 
(2)  recollect  that  Wright  and  Foucli6  have  more  recently  (De  Miliy*s  ezperimeEaa 
were  made  about  twenty-five  years  ago)  found  that  water  at  a  high  temperature 
causes  the  dissociation  of  fats  and  oils  into  glycerine  and  fatty  acids,  it  is  clear  that 
while  the  small  quantity  of  lime  may  have  facilitated  the  saponification,  the  resali 
obtained  by  De  Milly  is  mainly  due  to  the  very  high  temperature  of  the  water 
employed  in  the  operation.  This  is  clearer  from  the  fact  that  a  process  of  saponifi- 
cation is  successfully  in  use  based  solely  upon  the  application  of  water  at  a  hi^ 
temperature. 

■•'^'iSShlSJlcku*"  ***  B^-  Saponification  by  Means  of  Sulphuric  Acid  and  SiAm- 
quent  Distillation  by  Means  of  Steam, — It  was  known  to  Achard,  in  the  year  1777, 
that  the  neutral  fats  are  decomposed  by  concentrated  sulphuric  acid  in  a  manna 
similar  to  the  decomposition  effected  by  caustic  alkalies.  This  fact  was 
brought  forward  in  1821  by  Caventon,  and  1824  ^7  Ghevreul,  but  was  not 
cally  investigated  until  1836  by  Fr6my,  and  not  industrially  applied  until  the  year 
1 84 1,  when  Dubrunfaut  introduced  the  distillation  of  the  fatty  acids  on  the  laige 
scale.  The  crude  fatty  matter  usuaUy  submitted  to  this  process  of  saponification  is 
of  the  kind  that  cannot  be  saponified  by  the  litne  process  by  reason  of  its  impurities; 
thus,  for  instance,  palm  and  cocoa-nut  oU,  bone  and  marrow  fat,  fat  of  slaoghter- 
houses,  kitchen-stuff,  the  products  of  the  decomposition,  by  means  of  sulphuric  add, 
of  the  soap-water  obtained  from  wool-spinning  and  cloth-making  works^  residues  of 
the  refining  of  fish  and  other  oils,  residues  of  tallow-melting,  &c. 

This  process  of  saponification  by  means  of  snlphnric  acid  as  carried  on  in  the  large 
establishment  for  stearine  candle-making  of  Leroy  and  Dnrand,  at  Qentilly,  near  Fans. 
consists  of  three  operations,  viz. : — 

a.  Saponification  with  solphurio  acid. 

/3.  Decomposition  of  the  products  of  saponification. 

y.  Distillation  of  the  fatty  acids. 

«.  In  order  to  eliminate  the  greatest  impurities  first,  the  crude  fatty  matien  are 
molten  and  kept  in  the  liquid  state  for  some  time,  so  that  the  coarser  impurities  may  sub- 
side. The  fatty  matters  are  then  transferred  to  a  kind  of  boiler  made  of  iron  boiler-plides 
lined  inside  with  lead»  and  fitted  with  a  stirring  apparatus  and  a  steam-jacket,  connected 
by  means  of  pipes  with  a  steam-boiler,  so  that  the  apparatus  may  be  heated.  Into  this 
vessel  sulphuric  acid  at  66°  B.  »  i>8  sp.  gr.,  is  poured,  the  quantity  of  this  fluid  being 
regulated  according  to  the  natnre  of  the  fatty  matters  operated  upon.  Eitohen-stoff,  fit 
from  slaughtar-hooses,  and  the  like  require  la  i)er  cent  of  their  weight  of  acid  ;  pidm  oil 
requires  from  6  to  9  per  cent  according  to  quality.  The  fatty  substimces  having  been  pat 
into  the  vessel,  the  stirring  apparatus  is  set  in  motion,  and  the  steam  turned  on  for  the 
purpose  of  supplying  heat  to  the  vessel.  The  temperature  to  which  the  vessel  is  heated 
varies,  in  Price's  Works,  Battersea,  being  177*,  while  at  Gentilly,  the  heat  is  seldom  higher 
than  from.  1 10°  to  1 15**.  Daring  the  operation  the  mass  foams,  becomes  brown, and  evolvaa 
sulphurous  acid,  partly  due  to  the  action  of  a  portion  of  the  concentrated  sulphuric  acid 
upon  the  glycerine,  partly  to  its  action  upon  the  impmities  present  among  the  fatty 
matters.  The  neutral  fat  is  converted  into  a  mixture  of  sulpho-fatty  adds  and  snlpho- 
glycerio  acid.  The  saponification  is  complete  after  some  fifteen  to  twenty  hours*  appli- 
cation of  heat.  According  to  De  Milly's  new  process  (1867)  the  tallow  is  heated  to  iao% 
along  with  6  per  cent  of  sulphuric  acid,  and  the  action  of  the  latter  is  limited  to  two  to  thraa 


ARTIFICIAL  LIGHT,  625 

minutes ;  it  is  thereby  possible  to  obtain  80  per  cent  of  the  solid  fatty  aoids  in  a  condition 
at  once  fit  for  making  candles  withont  re-distillation,  only  20  per  cent  having  to  be 
distilled. 

/3.  Decomposition  of  the  products  of  the  sulphuric  acid  saponification.  The  mass  is 
left  to  cool  for  three  to  four  hours  and  is  next  transferred  to  large  wooden  tanks 
lined  with  lead,  and  previously  filled  one-third  with  water.  At  the  bottom  of  these  tanks 
steam  pipes  are  fitted,  by  means  of  which  the  fluid  contents  of  the  vessel  are  soon  heated 
to  100".  The  sulphuric  acid  and  the  fatty  acids  are  dissociated,  and  these  bodies,  partly 
combined  with  a  larger  quantity  of  hydrogen  and  oxygen  than  was  present  in  the  fatty 
acids  from  which  they  were  formed,  partly  also  in  an  unaltered  condition,  are  found 
floating  on  the  surface.  After  having  been  repeatedly  triturated  with  boiling  water,  the 
fatty  acids  are  tapped  or  poured  over  into  a  vessel  filled  with  water  heated  to  40°  to  50'', 
for  the  purpose  of  allowing  the  impurities  to  become  deposited.  The  clarified  fatty  acids 
are  next  heated  in  a  yessel  placed  on  an  open  fire  in  order  to  evaporate  all  the  water,  after 
-which  they  are  submitted  to  distillation. 

y.  The  distillation  requires  several  precautions.  Distillation  with  an  open  fire  would 
convert  the  fatty  acids  mto  oil,  gas-tar,  and  a  carbonaceous  residue,  if  the  heat  were 
safi&ciently  high.  But  when  the  temperature  is  properly  regulated,  the  fatty  acids 
are  protected  brom.  the  direct  action  of  the  fire.  Air  should  be  completely  excluded  from 
the  distilling  apparatus.  With  these  precautions  the  fatty  acids  distil  over  without 
nndergoing  any  essential  alteration.  These  conditions  are  complied  with  by  the  use  of 
superheated  steam  at  a  temperature  of  250°  to  350°.  The  fatty  acids  are  put  into  a  roomy 
retort  supported  by  brickwork,  and  fitted  with  a  steam  tube  as  well  as  a  condensing  tube 
connected  with  a  receiver,  in  which  the  fatty  acids  are  collected. 

When  the  several  fatty  acids  are  fractionally  collected  from  the  beginning  to  the  end  of 
the  distillation  their  melting-points  are : — 

Prom  Palm  Oa.  ^^'S  l^ne  fI'"" 


ist  product      54'5"  44'o* 

2nd  „  52-0*  41*0' 

3rd  „  48*0"  4i'o 

4th  „  460*  425 

5th  „  44-0*  44-0 

6th  „  41-0'*  45 'o 

7^  M  39*5°  410 


The  water  condensed  with  the  fatty  acids  runs  oB  from  the  receiver  through  a  tap.  At 
the  beginning  of  the  operation  the  water  constitutes  half  of  the  produce ;  towards  the  end 
only  about  one-third.  With  a  retort  capable  of  containing  1000  to  1 100  kilos,  of  material 
the  distillation  takes  some  twelve  hours.  The  end  of  the  operation  is  indicated  by  the 
coming  over  of  coloured  products.  There  remains  in  the  retort  a  black  tarry  matter,  the 
quantity  of  which  amounts  in  the  case  of  palm  oil  distillation  to  2  to  5  per  cent,  and  for 
kitchen-stuff  to  5  to  7  per  cent.  This  residue  is  not  removed  after  each  distillation  but 
left  in  the  retort  until  it  has  accumulated  to  such  an  extent  as  to  render  its  removal 
necessary.  The  first  products  of  the  distillation  of  palm  oil  saponified  by  means  of  fatty 
acids  are  so  solid,  that  by  pressure  they  do  not  yield  any  fluid  acid,  and  are  at  once  fit  for 
the  manufacture  of  candles.  The  products  which  come  over  afterwards  are  further 
purified  by  hydraulic  pressure,  re-melting,  and  washing  with  water.  The  substance 
obtained  by  pressure,  more  or  less  pure  oleic  acid,  is  used  for  soap-making  only  in  this 
country,  although  abroad  it  is  burnt  in  some  kinds  of  lamps.  The  oleic  acid  obtained  by  this 
process  is  essentially  different  from  that  obtained  by  the  lime  saponification  process.  The 
quantities  of  fatty  acids  obtained  by  this  process  of  saponification  are  the  following : — 

From  Snint 47  to  55  per  cent. 

„     Olive  oil  residues      47  to  50       ,, 

„     Palm  oil      75  to  80       „ 

„     Fat  from  slaughter-houses      . .     . .  60  to  66       „ 


Palm  oil      75  to  80 

Fat  from  slaughter-houses      . .     . .       60  to  66 
Oleic  acid 25  to  30  ■    „ 


Chloride  of  zinc,  which  in  many  respects  (see  p.  81)  is  similar  in  its  action  to  sulphuric 
acid,  has  been  proposed  as  a  substitute  for  the  latter.  For  countries  into  which  sulphnric 
acid  has  to  be  imported  chloride  of  zinc  might  be  of  greater  advantage,  being  capable 
of  recovery  and  less  dangerous  and  difficult  in  transport.  When,  according  to  the 
researches  of  L.  Kraft  and  Tessi^  du  Motay,  a  neutral  fat  is  heated  with  anhydrous 
chloride  of  zinc,  a  complete  incorporation  of  these  substances-  takes  place  between  150° 

3  c 


636  CHEMICAL  TECHNOLOGY. 

and  200* ;  and  by  eontinnlng  the  heating  for  some  time,  and  waehing  the  materiak  vA 
warm  water,  or  better  with  water  addalated  with  hydiochlorio  acid,  there  is  obuiaai. 
a  fatty  matter,  whidi  on  being  submitted  to  distillation,  yields  the  corresponding  fttfy 
acid,  while  only  a  small  quantity  of  acroleine  is  formed.  The  chloride  of  ziiie,  beofTBg 
Bolnble  in  ^e  water  ns^  for  washing,  may  be  recovered  by  cTaporating  the  fluid.  Tba 
yield  of  fatty  aeids  by  this  process  is  the  same  as  that  obtained  by  the  aae  of  sntpfaenB 
acid,  while  the  fatty  acids  also  agree  as  to  their  physical  properties.  The  qaaDlil^ 
of  chloride  of  zinc  required  amounts  to  8  to  Z2  per  cent  of  the  fat. 

"•"SySiSlh  pwJSiS.*'*'  ^-  Some  sixteen  years  ago  another  agent,  capable  of  bnni^ig 
about,  in  a  manner  similar  to  alkalies  and  acids,  the  dissociation  of  fiittj  malten  inlo 
glycerine  and  fatty  acids,  was  introduced,  this  agent  being  simply  superheated 
at  high  pressure : — 

3SX0J 1  Os+3^  =^][03 + ajl^^o. 

Tripalmitine.         Water.    Glycerine.         Palmitic  acid. 

The  idea  of  submitting  fatty  matters  to  a  similar  method  of  treatment  is  not  a 
one,  for  in  the  researches  of  Appert  (1823)  and  Manider  (1826)  some  hints  are  gi'vca 
on  the  decomposition  of  fats  by  means  of  superheated  water ;  but  the  aim  of 
technologists  was  different,  for  in  their  experiments  they  employed  steam  to 
the  tallow  from  the  cellular  tissue  it  is  contained  in,  and  for  that  purpose  a 
ture  of  I  is'' to  lai"*  was  quite  sufficient,  while  at  a  temperature  of  180°  and  a 
of  10  to  15  atmospheres  (=  150  lbs.  to  225  lbs.  pressure  to  the  square  inch) 
can  exert  a  far  more  energetic  action  upon  the  neutral  £fttB,  dissociating  them  an! 
thus  setting  free  tlieir  constituents.  The  knowledge  of  this  interesting  £act  Is  doe  ti 
the  researches  of  Tilghmann  and  Berthelet,  who  almost  simultaneously  made  lidi 
discovery  in  the  year  1854,  while  shortly  after  Melsens,  at  Brussels,  obtained  tfat 
same  result.  As  regards  the  industrial  application  of  this  discovery,  Tilghmsan  aai 
Melsens  made  further  researches ;  their  modes  of  operating  are  veiy  similar. 

Tilghmann  adds  to  the  neutral  fat  about  to  be  decomposed  one-third  to  oneislf 
of  its  bulk  of  water,  and  pours  this  mixture  into  a  sufficiently  strong  vessel  in  which 
the  fluids  can  be  submitted  to  the  action  of  heat,  viz.,  a  degree  nearly  as  hi^  ss  tke 
melting-point  of  lead,  320**.  This  vessel  is  so  arranged  that  during  the  operatios  d 
can  be  closed  so  as  to  prevent  on  the  one  hand  tlie  evaporation  of  water,  and  on  the 
other  admit  of  a  sufficiently  strong  pressure.  The  process  is  canied  on  oontinQosd^ 
by  causing  the  fluids  to  circulate  through  a  tube  heated  to  the  required  temperstaiv. 
Melsens  uses  a  Papin's  digester,  in  which  the  fat  to  be  decomposed  is  heated  to  180^  to 
200%  with  10  to  20  per  cent  water,  to  which  i  to  10  per  cent  of  sulphuric  acid 
added.  Wright's  and  Fouch6's  apparatus  consists  of  two  hermetically  closed 
vessels  placed  one  above  the  other  and  connected  together  by  means  of  two  tnbes, 
of  which  reaches  nearly  to  the  bottom  of  the  lower  vessel,  and  ends  in  the  upper  om 
just  above  the  bottom. 

The  second  tube  is  fixed  into  the  lid  of  the  lower  vessel  and  passes  thT«ipgh  ihe 
upper  vessel  reaching  nearly  to  its  cover.  The  upper  vessel  is  the  steam-generator, 
while  the  decomposition  goes  on  in  the  lower  vessel.  When  it  is  intended  to  waik 
with  this  apparatus,  the  steam-generator  is  filled  with  water  nearly  to  the  point  il 
which  the  first  tube  ends  in  it.  The  second  vessel  is  then  filled  with  molten  &t  10 
that  this  material  reaches  the  top  of  the  second  tube.  There  remains  thus  a  fivft 
space  between  the  fat  and  the  lid  of  the  second  vessel,  which  space  is  termed  by  tk 
patentees  chambre  d* expansion,  expansion  room.    Heat  being  applied  to  the  generator. 


ARTIFICIAL  LIGHT.  tty 

time  steam  fonned  is  carried  by  the  second  tube  into  the  expansion  room,  and 
l>eooniing  condensed  forces  it  way  downwards  through  the  specifically  lighter  fat 
nxkd  flows  through  the  first  tube  again  into  the  generator.  In  this  manner  the 
neutral  &t  is  intimately  mixed  at  a  high  temperature  and  under  high  pressure  with 
irater,  and  completely  dissociated  in  a  short  time  into  fatty  tusid  and  glycerine. 

afaanfaAtanofTkuyAeida      Y.  Allied  to  the  proccBS  just  desoiibed  is  the  operation  carried 
^%S^ui9DE^iSSf    <>°   ^y  *^«  well-known   Price's   Candle   Company.   limited,  at 
oiatiiuiion.  Battersea.    Gay-Lussao  and  Dnbnmfant  haTe  already  tried   to 

Apply  to  industrial  purposes  the  fact  that  neutral  fats  are  dissociated  by  distillation, 
yielding  fatty  adds ;  but  notwithstanding  that  these  tavatUt  employed  steam,  the  results 
obtained  did  not  answer  the  expectation,  because  a  portion  of  the  fatty  matter  was 
decomposed,  yielding  acroleine  and  leaving  a  carbonaceous  residue.  Wilson  and  Gwynne 
"were  more  successful  with  their  experiments,  and  by  using  a  distilling  apparatus  similar 
to  that  described  on  p.  625,  they  obtained  l^  means  of  superheated  steam  the  complete 
dissociation  of  the  neutoJ  fats  into  fatty  acids  and  glycerine ;  while  by  closely  watching 
ttod  regulating  the  temperature,  they  not  only  could  completely  saponify  the  neutral  fats, 
Ibnt  also  distil  the  fatty  acids  and  glycerine  OTcr  without  undergoing  any  decomposition. 

The  retorts  haye  a  cuMc  capacity  of  60  hectolitres,  and  are  heated  by  direct  fire  to  a 
temperature  of  290*  to  3I5^  A  malleable  iron  steam-pipe  conveys  steam  at  a  tempe- 
xaiure  of  315*  into  the  molten  fatty  matter.  The  admission  of  steam  is  continued  for 
turenty-four  to  thirty-six  hours  according  to  the  kind  of  fat.  The  saponification  proceeds 
regularly  and  the  products  distil  oyer  and  are  collected  at  the  lower  aperture  of  the 
cooling  apparatus.  The  fatty  acids  are  at  once  fit  for  candle  making  purposes,  while  the 
f^lycerine  is  purified  by  a  subsequent  distillation  with  steam.  As  already  mentioned,  the 
prox>er  temperature  has  to  be  scrupulously  maintained,  for  if  the  temperature  falls  below 
310**,  the  saponification  proceeds yery  slowly;  but  if  the  temperature  rises  much  above 
that  degree,  a  portion  ci  the  fatty  substance  is  decomposed  and  acroleine  is  formed  in 
large  quantity. 

OMid]«]iakii«.  B.  The  wick  is  a  very  important  portion  of  stearine  candles,  and, 
indeed,  of  all  kinds  of  candles,  because  in  the  interstices  of  the  wick  the  molten  feitty 
matter  of  the  candle  is  drawn  upwards  to  the  flame.  The  wick  ought  therefore  to 
consist  of  porous  substances,  and  in  the  case  of  candles— for  lamps  it  is  not  so  requi- 
site— it  should  be  combustible. 

It  is  essential  that  the  wick  be  of  uniform  thickness  through  its  entire  length  and 
free  from  knots  or  loose  threads.  The  yam  ordinarily  used  for  making  wicks  is  the 
lightly-twisted  cotton  thread  known  in  the  trade  as  No.  16  to  20  for  tallow  candles, 
and  No.  30  to  40  for  stearine  candles.  It  is  evident  that  the  more  uniform  the  wicks 
the  better  fitted  they  are  for  capillary  action,  and  hence,  provided  the  illuminating 
material  be  pure  enough,  a  uniform  combustion.  Formerly  the  wicks  were  always 
twisted,  and  for  tallow  and  wax  candles  this  is  still  frequently  the  case,  the  single 
threads  being  placed  next  to  each  other  and  then  turned  so  as  to  form  a  very  elon- 
gated spiraL  In  order  to  obviate  the  snuffing  of  the  burning  candles.  Cam- 
baches  introduced  the  plaited  wicks,  which,  while  burning,  become  so  twisted  that 
the  end  of  the  portion  of  the  wick  which  protrudes  from  the  tallow  or  stearine  is  kept 
just  outside  the  flame,  so  that  it  may  be  consumed  to  ash  by  the  ambient  air. 
Before  the  wick  can  be  used  in  candles  it  has  to  be  prepared,  because  unprepared 
wick  leaves  by  its  incomplete  combustion  a  considerable  quantity  of  a  carbonaceous 
residue  which  greatly  impairs  the  capillary  action.  When  stearine  candles  were 
first  made  it  became  necessary  to  impregnate  wicks  with  substances  which  should 
promote  the  combustion,  and  De  Milly  found  (1830)  that  boracio  and  phosphoric 
adds  would  answer  this  purpose,  because  these  acids,  while  combining  with  the 
constituents  of  the  ash  of  the  wick,  caused  the  ash  to  form  at  the  top  of  the  burning 
wick  a  glass  bead,  which  by  its  weight  turned  the  wick  out  of  the  flame,  thereby 
increasing  the  combustibility.    In  the  French  candle  fiustories  the  wicks  to  be 


' 


628  CHEMICAL  TECHNOLOGY, 

prepared  are  put  for  three  consecntiye  hours  into  a  solation  of  i  kilo,  of 

in  50  litres  of  water.     The  previously  plaited  wicks  are  next  either  wrung  out  or  pA 

into  a  centrifugal  machine  to  get  rid  of  the  first  excess  of  moisture,  after  which  ftw 

are  dried  hy  heing  placed  in  a  jacketted  tinned-iron  box,  which  is  heated  by  maoid 

steam.     Some  alcohol  should  be  added  to  the  aqueous  solution  for  the  purpose  rf 

wetting  tlie  wicks  more  perfectly.    Payen  recommends  a  pickling  liquor  for  ffida. 

composed  of  a  solution  of  5  to  8  grms.  of  boracic  acid  in  i  litre  of  water,  to  whkk 

3  to  5  per  mille  of  sulphuric  acid  is  added.   In  some  Austrian  stearine  candle fcctona 

phospVate  of  ammonia  is  used  to  impregnate  the  wicks;  while  I>r.  BoUey  calli 

attention  to  the  use  of  a  solution  of  sal-ammoniac  at  2°  to  3**  B.  as  a  cheap  picklai| 

for  wicks. 

Moniding  the  cudiea.      The  blocks  or  cakos  of  stearic  acid  obtained  as  described  aR  ^ 

sufficiently  pure  for  moulding.    The  edges  of  the  blocks  are  often  more  or  less  «*j™ 

and  soft,  owing  to  some  oleic  acid  not  having  been  pressed  out,  while  the  surlaoe  rajM 

blocks  is  contaminated  with  oxide  of  iron  and  the  hair  of  the  press-bags.    In  ^^^ 

purify  the  blocks  or  cakes  (in  this  country  they  frequently  weigh  from  li  to  3  c*ts.i  Ito 

edges  are  pared  off  and  the  surface  is  scraped,  the  refuse  so  obtained  being  again  sw- 

mitted  to  hot-pressing.    The  blocks  thus  treated  are  next  put  into  tubs  lined  ^"^^ 

and  dilute  sulphuric  acid  of  3*  B.  =  1*020  sp.  gr.  having  been  poured  over  them,  thenaw 

is  heated  by  means  of  steam,  the  aim  of  this  operation  being  to  remove  oxide  of  ''J"  ^* 

destroy  the  fibres  of  the  press-bag,  and  not,  as  is  sometimes  stated,  to  decompoae  the  oA 

traces  of  stearate  of  lime,  which  of  course  cannot  be  present.    "When  the  action  of  tw 

sulphuric  acid  has  been  continued  for  a  sufficient  time,  it  is  run  off  and  the  Ust  ^'^^^ 

the  acid  removed  by  washing  the  stearic  acid,  of  course  again  molten,  with  boihug  wa«f. 

The  molten  stearic  acid  is  then  clarified  by  means  of  a  certain  quantity  of  ^^**~** 

which  is  thoroughly  stirred  through  the  molten  mass  heated  to  the  boiling-point  of  ***?  J**J 

mixed  with  it.    The  impurities  which  become  mixed  and  incorporated  with  the  **"^^ 

egg  settle  at  the  bottom  of  the  vessel.    The  great  tendency  of  Uie  stearic  acid  to  07^' 

lise  in  large  foliated  ciystals  caused  at  the  commencement  of  the  stearine-candle  n>J^ 

business  a  difficulty,  candles  of  unequal  transparency  as  well  as  of  great  brittieness  wssi 

obtained.    The  defect  was  remedied  by  the  addition  of  a  small  quantity  of  arsenious  tai, 

but  as  this  proved  detrimental  to  health  (arseniuretted  hydrogen  as  weU  as  some  *"^JJ*J 

acid  being  evolved  during  the  burning  of  such  candles),  the  use  of  this  acid  was  at^^ 

prohibited  by  law,  and  in  England  condemned  by  public  opinion.    Instead  of  the  uae« 

arsenious  acid,  some  2  to  6  per  cent  of  white  wax  has  been  added  to  the  steanc  •» 

while  molten,  continually  stirring  until  nearly  solidified  previous  to  pouring  the  s4ean« 

acid  into  the  candle-moulds  previously  heated  to  the  melting-point  of  tiie  stean* 

By  the  cooling  and  stirring  a  kind  of  fluid-fat  paste  was  obtained  which  does  not  ei5»- 

tsJlise.    Now  some  20  per  cent  of  paraffiLn  is  added  to  the  stearic  acid,  and  its  tendency  0 

crystallise  altogether  suspended.  ^    ^  ^^ 

The  candle-moulds  are  made  of  an  alloy  of  tin  and  lead,  usually  conaisting  of  ^  P^ 

of  tin  to  10  of  lead.    The  moulds  are  narrow,  somewhat  conical  tubes,  ^**?^2rAj 

internally  in  order  to  impart  a  smooth  surface  to  the  candles.    The  wick  is  fixed  m^ 

longitudinal  axis  of  the  moulds,  being  fastened  at  one  end  (the  top  of  the  finished  J**^ 

in  a  small  hole  at  the  bottom  of  the  mould,  and  at  the  other  end  fastened  to  a  funnel, thro^ 

which  the  fatty  acid  is  poured  into  the  mould.    The  shape  of  the  moulds  used  m  «• 

French  stearine  candle  works  is  exhibited  in  Fig.  269.    o  is  a  mould  consisting^ 'J" 

parts,  viz.,  the  mould  proper  and  the  funnel.    6  exhibits  these  two  parts  fitted  togetbC 

and  c  a  longitudinal  section  with  the  wick  inserted,  while  d  is  the  wire  hook  with  wM* 

the  wick  is  passed  through  the  mould.    For  the  moulds  now  generally  used  one  P^'J^^ 

basin  or  box  is  employed  to  contain  thirty  moulds.    TMs  basin  or  moulding-wiJJ 

exhibited  in  Fig.  270.    a  n  is  a  large  sheet-iron  or  tinned  box  in  which  the  moulds  iw 

placed.    This  box  is  fitted  into  another  of  similar  shape,  b  b,  which  by  meana  of  steaBi» 

kept  at  a  temperature  of  100°'    As  soon  as  the  moulds  are  heated  to  45**,  the  ^  ^  ^ 

removed  from  d  d,  and  the  molten  stearic  acid  is  poured  into  the  moulds.    ^^^*^JJJ 

moulds  and  the  candles  contained  have  become  quite  cold,  the  latter  are  removed:   f*^ 

moulding  machines  are  generally  employed,  so  that  this  operation  is  performed  hmm** 

ruptedly,  the  construction  of  these  machines  being  such  that  the  reeled  "vick  i*  w*]™ 

through  the  moulds  while  the  candles  remain  joined  together  by  a  short  piece  ®'*2 

until  after  the  moulding  is  complete,  the  candles  when  cold  being  taken  from  *^* '"^"^ 

and  the  wicks  cut  through  to  separate  them.    Cahouet*8  and  Morgane's  maehiDtf  ^ 

chiefly  used. 


ARTIFICIAL  LIOHT. 


B«tore  tlie  rtearine  ouidles  ore  pored  mi  poluhed  they  are  Id  gome  irorks  bleached  \>j 
being  exposed  to  the  action  of  the  sun'a  rajg  and  to  dew  in  open  air.  The  oacdles 
•re  carried  to  the  bleaohing-ground  by  meehanicaJ.  self-acting  meanB,  consisting  of  a  cloth 
inthont  end,  and  which  ia  connected  with  a  slightly  sloping  table,  upon  which  the  cimdleH 
axe  placed,  and  oanght  by  the  cloth,  which  is  fitted  with  a  seriea  of  rounded  wooden  laths 
fastened  acrosa  the  cloth,  whereby  the  candles  nre  held  in  position.  For  the  purpose  of 
exposing  the  candles  to  IJie  action  of  the  air  thny  are  placed  on  a  frame-worli  siimlaT  to 
that  ol  a  table,  iusteod  of  the  top  of  which  are  stretched  two  textures  of  lead-wire,  each  o( 
these  textnres  in  a  horizontal  plane  distotit  from  each  other  abont  half  the  height  of  a 
candle.  The  mesbea  of  the  upper  wire  net  are  Eovide  that  a  candle  can  be  passed  throngh 
it,  while  the  meshes  of  the  lower  wire  net  are  narrower.  The  candles  are  one  by  one  put 
into  the  meshes,  the  pointed  portions  of  the  candles  being  placed  upwards,  while  the  hasa 
rests  on  the  lower  wire  net.  Jn  this  position  the  candles  are  left  for  some  time  according 
to  the  season  ol  the  year.  Wbeo  blsAobed  the  oandles  are  pared  and  polished  by 
machinery. 

i*ddi>c«i4Ih.  a.  Beflned,  pnrifled  tallow  is  n»ed  for  making  the  dip  ai  well  as  ths 
moulded  tallow  candles.    The  dips  are  made  by  the  repeated  immersion  ol  the  wicks  in 

molten  tallow.    On  the  small  scale  this  operation  is  performed  in  the  following  manner : 

The  tallow  trough  baTing  been  filled  with  molCen  tallow,  the  wicks  looped  on  a  wooden  or 


*     f 


1 


thin  iron  rod  are  immersed  in  the  tallow.  Aocording  to  the  weight  it  is  deaired  to  give  to 
the  candles,  from  sixteen  to  eighteen  wicks  are  looped  on  to  the  dipping-rod,  oare  being 
taken  to  place  them  as  much  as  possible  eqnidistant  from  each  other ;  this  done  the  wicks 
are  dipped  Tertically  into  the  molten  tallow.  At  the  first  dip,  when  the  wicka  are  to  be 
soaked,  the  molten  tallow  should  be  hot,  because  hot  tallow  penetrates  more  readily  into 
the  insterstices  ol  the  cotton.  After  the  first  dip  the  dip-n^  ore  placed  on  the  edge  of 
the  tallow  trough,  and  next  alternately  hong  over  the  dripping  frame  after  the  somewhat 
twisted  wieka  hBTe  been  put  straight  again.  Tba  dripping  frame  is  simply  a  wooden 
frame-work,  on  the  edges  of  which  the  cupping-rods  rest,  while  the  wicks  are  suspended 
o*er  the  tallow  trough  or  another  suitable  Teasel.  When  all  the  wicks  looped  on  to  the 
dipping-roda  have  received  their  flrat  dip.  and  the  tallow  in  the  trough  has  been  so  far 
oooled  as  to  begin  to  exhibit  at  the  sides  of  the  vessel  signs  of  solidification,  the  second 


630 


CHEMICAL  TECBNOLOOT. 


affftiii.  In  order  I0  keep  the  tallow  in  the  trovgh  at  a  rndfoim  degree  of  flnUitj  d  is 
now  and  then  etixred  with  a  wooden  rod.  At  the  last  dip  the  candles  are  pnt  into  the 
trough  at  a  somewhat  greater  depth  in  order  to  form  the  upper  oonioal  portion.  Xbe 
lower  end  of  the  candles  ezhihits  a  non-symmetrical  cone,  which  is  either  eot  away  or 
removed  by  placing  the  candles  for  a  moment  on  a  copper  plate  heated  by  steam  sad 
provided  with  a  channel  for  running  off  the  molten  tallow. 

Moulded  tallow  candles  are  made  in  a  similar  manner  to  stearine  candles.  Hie  isBev 
used  for  the  moulded  candles  is  nsnidly  of  better  quality  than  that  used  for  dip  eandke, 
at  least  on  the  continent  of  Europe ;  not  so  in  England  and  America,  where  very  hi^ly 
refined  tallow  is  used  for  dips  by  the  better  class  of  makers,  the  thus  refined  tallow  besif 
harder  owing  to  the  mode  of  purifying.  What  are  termed  composite  candles  (unkn^va 
on  the  €k>ntinent)  are  made  by  precisely  the  same  method  as  the  moulded  stearina 
oandles,  the  wicks  also  being  plaited.  Moulded  taUow  candles  hare  been  entirely  sa^a- 
seded  by  composites,  excepting  that  in  some  of  the  oentral  parts  of  Europe,  lonJly 
moulded  tallow  oandles  are  here  and  there  made.  One  of  the  largest  London  firms  slalea 
that  the  manufacture  of  candles  (almost  all  moulded,  viz.,  compoaitea,  ateaziaa, 
paraffin,  ozokerite,  spermaceti),  for  exportation  from  this  countiy  to  all  parta  of 
the  world,  is  increasing  to  sncn  an  extent  that  the  candle  making  business  in  Bneaa, 
Turkey,  Greece,  Italy,  Spain,  Portugal,  Sweden,  and  Norway,  is  beoonun^  rapid^ 
extinct,  not  being  capable  to  compete  on  the  small  scale  with  the  large  makers  in  tkii 
oount^  and  in  France,  where,  however,  the  late  lamentable  evenU  have  veiy  aoiiou^ 
interfered  with  this  branch  of  industry. 

PuaflaowiAML  Paraffin  is  obtained  from  natiye  petroleum  (Rangoon  oil)  or  fipcn 
tonong  the  products  of  the  dry  distillation  of  peat,  brown  coal,  lignite,  UtamiMnB 
slates,  boghead  mineral  or  ozokerite  (a  pecnliar  mineral,  wax-like,  and  yielding 
paraffin— it  occurs  in  Galicia  and  Bohemia  in  large  qnantitiee)  It  is,  after  having 
been  purified,  the  substance  from  which  the  beautifal  paraffin  candles  are  made  by 
precisely  the  same  methods  and  apparatus  as  are  used  and  have  been  deaeribed  lor 
stearine  candles.  The  paraffin  employed  for  making  candles  is  a  mixtizie  ef 
paraffins  having  different  melting-points. 

Paraffin  obtained  from  boghead  coal  fuses  at         455''  to  52^ 
„  „  „    brown  coal  „        560** 

M    peat  .„        467° 

„  „  „    Rangoon  oil  or  tar    „       6i*o** 

„  „  .,    ozokerite  „        65-5' 

As  the  German  paraffin  candle  makers  use  almost  exclusively  a  paraffin  fitn 
brown  coal  (lignite),  and  peat,  and  of  a  comparatively  low  melting-point  (45^  to  53I, 
stearic  add  is  added  for  the  purpose  of  raising  the  temperature  at  which  the 
paraffin  melts.  The  qoantity  of  stearic  acid  (technically  stearine)  added,  depends  as 
much  upon  the  point  of  fusion  of  the  paraffin  as  upon  the  season  of  the  year, 
summer  candles  being  made  with  a  larger  quantity  of  stearine  than  winter  eandlea 
The  quantity  of  stearine  thus  added  to  paraffin  amounts  to  3  to  15  per  cent,  while  as 
already  menticmed,  paraffin  to  an  amount  of  15  to  20  per  cent  is  added  to  sleariBa 
candles.  A  small  quantity  of  stearine  is  always  added  to  paraffin  candles  liar  the 
purpose  of  preventing  these  candles  becoming  bent  while  standing  in  a  candlestick. 

The  first  paraffin  candles  ever  made  were  manufactured  by  Messrs.  Field,  of  Labi- 
beth,  from  paraffin  extracted  from  Irish  peat,  now  very  many  yean  ago,  hng 
before  paraffin  was  seen  or  known  elsewhere  than  as  small  specimena  in  chwnical 
laboratories.  Paraffin  candles  are  always  moulded,  and  the  moulds  are  heated 
to  above  the  melting-point  of  the  paraffin  (6o^  or  better  even  70^,  in  order  to  pre- 
vent the  paraffin  crystallising.  The  molten  paraffin  is  heated  to  about  60''  when  it  is 
oast  into  the  moulds;  these  when  well  filled  are  left  standing  for  a  moment  and  Asa 
cooled  by  immersion  in  cold  water,  whereby  the  candles  suddenly  solidify,  and  are 


ARTIFICIAL  LIGHT.  ^  631 

thus  prevented  becoming  erfstalline  and  opaque,  instead  of  transparent  as  desired. 
Plaited  wicks  are  used  in  the  paraffin  candles,  and  tliese  wicks  are  treated  with 
boracic  acid.  For  black  paraffin  candles  the  paraffin  is  heated  to  nearly  its  boiling- 
point  with  anacardinm  shells,  the  resin  of  which  is  dissolved  by  the  paraffin, 
the  latter  becoming  very  dark  brown,  and  exhibiting  after  cooling  a  black  colour, 
mnular  to  that  of  coals.  These  black  candles  bum  without  smoke  or  smell,  provided 
the  wick  be  thin ;  this  is  a  requisite  in  all  paraffin  candles. 

GtandiMfxomFftttyAddi.  Wo  must  not  ueglcot  to  Call  attention  here  to  a  fatty  acid, 
sebaoylic  acid,  G10H8O4,  which  might  perhaps  be  used  to  impart  to  paraffin  and  other 
kinds  of  candles  a  higher  meltiDg-point.  This  acid  may  be  obtaLned  by  the  dry  distilla- 
tion of  oleic  acid,  or  better  by  treating  castor  oil  with  a  highly  concentrated  caustic  soda 
solution.  In  the  latter  instance,  the  sebaeylio  acid  is  derived  from  the  rioinoleio  acid 
(castor  oil  is  in  Latin  termed  OUum  BUsini) : — 

I  Sebacylate  of  soda,  GioHx6Naa04  a  246 
Kidnoleic  acid,  C18H34O3         =  *98|  -iald 
Caustic  soda  solution,  aNaOH  =    80  J  J^**"" 


( =s  184  fatty  add.) 

Caprylio  alcohol,  CsHxsO  ="130 

>  Hydrogen,  Ha  »      2 


378  378 

According  to  these  formulie,  zoo  parts  of  castor  oU  will  yield  rather  more  than  8x  parts 
of  fatty  acid.  This  fatty  acid  is  no  doubt  also  contained  in  the  products  of  the  distillation 
of  the  fatty  substances  formed  by  sulphuric  acid,  the  Bebaoylio  acid  being  then  derived  from 
oleic  acid.  The  ^h  melting-point  (127°)  of  sebaoylie  acid  and  its  ready  combustibility 
render  this  body  a  very  fit  material  for  being  mixed  with  readily  fusible  candle  materials, 
and  especially  with  paraffin  of  low  fusion-point  (45'').  Moreover,  this  acid  will  impart  to 
the  candles  hardness  and  gloss.  As  this  acid  further  also  prevents  the  crystallisation  of 
stearic  add,  it  might  be  usefully  added  to  such  fatty  substances  as  have  a  great  tendency 
to  crystallise ;  an  addition  of  z  to  5  per  cent  of  sebacylic  acid  to  the  candle  materials, 
renders  them  as  hard  as  wax.  The  nmultaneous  formation  of  caprylic  alcohol,  which 
can  be  used  for  varnish  and  lacquer  making,  enhances  the  industrial  value  of  sebacylic 
aoid ;  still  oastw  oil  is  too  expenrave  for  this  purpose,  but  the  purification  of  sebaeylio 
acid,  obtained  no  matter  from  what  source,  is  not  easy,  requiring  manipulations  which  on 
the  large  scale  would  become  expendve. 

waxoudka.  4.  Wax,  or  more  particularly  bees'-wax,  is  a  fatty  substance  secreted 
by  the  bees,  and  employed  by  them  for  the  purpose  of  building  the  ceUs  in  which 
they  preserve  the  honey.  According  to  the  researches  of  J.  Hunter  and  F.  Hubner, 
it  is  now  generally  admitted  that  the  wax-containing  particles  gathered  by  the  bees 
from  flowers  are  used  excludvely  as  food  for  the  young  brood,  while  the  wax  is  a 
product  of  the  animal  organism  of  the  bees,  and  a  conversion  product  of  sugar.  In 
order  to  obtain  the  wax  the  bees  are  either  killed  or  forced  from  their  dwelling  by 
smoke,  after  which  the  honey-containing  cells  or  honeycombs  are  taken  from  the 
hive,  and  the  honey  eliminated  by  pressure,  or  by  being  allowed  to  flow  out  sponta- 
neously. By  washing  in  hot  water  the  wax  is  purified,  and  on  cooling,  the  cakes  of 
yellow  wax  are  obtained,  the  outer  dirty  crust  having  been  removed  by  scraping.  The 
crude  wax  thus  obtained  exhibits  a  more  or  less  yellow  colour,  is  soft  and  readily 
kneaded  at  the  ordinary  temperature  of  the  air,  but  becomes  brittie  at  a  lower  tem- 
perature ;  its  fracture  is  granular ;  spedfic  gravity  varies  between  0*962  and  0*967 ; 
fddon-point  between  60°  and  62^  While  the  granular  texture  of  the  yellow  wax  is 
due  to  the  impurities  it  contains,  it  is  for  tiiat  reason  as  well  as  for  its  undghtiy 
colour,  not  suited  for  candle-making,  and  has  therefore  to  undergo  bleaching.  This 
is  performed  in  the  following  manner ; — First,  the  yellow  wax  is  put  into  a  tinned 
copper  cauldron  filled  with  boiling  water,  to  which  is  added  0*25  per  cent  of  alum,  or 
cream  of  tartar,  or  sulphuric  acid,  and  this  mixture  thoroughly  stirred.  After  a  few 
minutes  the  liquid  is  run  off  into  a  tub  or  cask,  the  impurities  are  left  to  settle,  while 


632  ,  CHEMICAL  TECHNOLOGY, 

the  wax  is  prevented  from  solidifying  by  covering  the  tub  with  a  lid,  and  wrapfzag 
it  np  in  a  woollen  blanket.  Next  the  wax  is  converted  into  thin  ribbon  by  means  t£ 
machinery,  in  order  to  increase  the  surface  and  facilitate  the  bleaching  action  of  the 
air  and  light.  The  ribbons  are  placed  on  pieces  of  canvas  stretched  in  frames,  anl 
these  are  placed  on  meadows  or  grass-plots  exposed  to  the  action  of  the  snn  and  air, 
and  left  until  the  colour  has  disappeared.  In  order  to  bleach  the  interior,  iStm 
ribbons  are  again  molten  and  again  converted  into  ribbons,  and  this  op^ntiim 
repeated  until  the  wax  is  thoroughly  bleached.  The  bleaching  takes,  according  to 
circumstances,  the  state  of  the  weather  and  the  kind  of  the  wax  operated  upon,  from 
twenty  to  thirty-five  days,  for  completion.  The  loss  of  weight  of  wax  incurred 
amounts  to  2  to  lo  per  cent.-  The  bleached  wax  is  molten  again,  passed  thnmgii 
strainers,  and  then  moulded  into  large  square  cakes  or  thin  circular  tablets.  As 
regards  the  bleaching  of  wax  by  artificial  means  (chemical  bleachingi  many 
suggestions  have  been  made,  but  in  practice  these  leave  much  to  be  desired.  The 
application  of  chlorine  and  bleaching-powder  has  the  disadvantage  that  solid  and 
very  brittle  chlorinated  products  are  formed,  and  by  remaining  mixed  with  the  wax 
impair  its  combustive  quality,  and  cause  candles  made  of  such  wax  to  give  off  hydro- 
chloric acid.  The  process  of  bleaching  wax,  patented  in  1859  by  Arthur  Smith,  by 
the  use  of  bichromate  of  potash  and  moderately  dilute  sulphuric  add,  answ^«  very 
well  in  practice ;  the  bleaching  is  performed  in  a  few  hours,  and  wax  by  this  plan  is 
bleached  and  purified  as  perfectly  as  by  exposure  to  air  and  light ;  but  the  toughufss 
of  the  wax  is  somewhat  impaired,  so  that  it  is  not  suitable  for  such  purposes  as 
modelling,  flower-making,  &c.  In  reference  to  the  chemical  properties'  of  wax,  Joha 
first  found  wax  to  be  a  mixture  of  two  substances  differing  from  each  other  by  their 
solubility  in  alcohol ;  one  of  these  substances,  soluble  in  boiling  alcohol,  is  cerotie 
acid,  C27H54O2  (formerly  known  as  cerin) ;  the  other  sparingly  soluble  in  alcohol  is 
known  as  myricin,  and  consists,  according  to  Brodie,  of  palmitate  of  myiicile, 
C46Hg202  =  026H3x(C3oH6x)O3.  In  addition  to  these  bodies  wax  contains  4  to  5  p^r 
cent  of  a  substance  fusing  at  28°  and  named  cerolein,  to  wliich  is  due  the  solidity 
of  wax.  Tlie  relative  proportions  of  cerotic  acid  and  myricin  present  in  bees*-wax 
vary  considerably,  and  this  variation  is  the  cause  of  the  alteration  of  the  fusion- 
point  observed  in  different  kinds  of  wax. 

other  kinds  of  Wax.  I .  Among  the  more  or  less  wax-like  substances  are  the  following: — 
Chinese  wax,  imported  in  large  quantity  from  China,  is  derived  from  a  peculiar  kiad 
of  coccus  insect,  known  entomologically  as  the  Coccus  cerifemsy  which  dwells  on 
certain  trees,  more  especially  the  Rhus  succedanea^  upon  which  it  deposits  a  wax-like 
substance,  in  its  physical  appearance  very  similar  to  spermaceti.  Tliis  quasi- wax 
is  snow-white,  crystalline,  brittle,  fibrous,  and  fuses  at  82*.  When  submitted  to  diy 
distillation  it  yields  cerotic  acid  and  ceroten,  a  paraffin-like  body.  According 
to  Brodie,  Chinese  wax  consists  of  cerotate  of  ceryl,  Cs^HiosOass  Cji^Hs^'CayHj^^O,. 
2.  Andaquies  wax,  the  product  of  an  insect  met  with  in  the  regions  watered  by  the 
Orinoko  and  Amazon  rivers,  fuses  at  77",  has  a  sp.  gr.  of  0917,  and  appears  to  be 
similar  in  composition  to  bees*-wax.  3.  Japanese  or  American  wax,  met  with  in  the 
trade  in  round  concavo-convex  cakes,  covered  with  a  whitish  dust.  This  soft  brittle 
material  fuses  at  42°,  is  soluble  in  boiling  alcohol,  and  is  said  to  consist  of  palmitine. 
4.  Camauba  wax,  imported  from  Rio  de  Janeiro,  is  said  to  be  the  outer  coating  of 
the  leaves  of  a  kind  of  palm  tree  named  the  Kopernicia  cerifera ;  it  fuses  at  83'5^ 
and  is  used  on  account  of  its  high  fusion-point  to  improve  candle-making  materials 


ARTIFICIAL  LIGHT,  633 

of  low  fusion-point.  5.  Pftlm  wax,  obtained  firom  the  bark  of  the  Ceroxylon 
€indicola,  a  palm-tree  met  with  on  the  liigher  peaks  of  tlie  Cordilleras.  The  wax  is 
scraped  from  the  bark,  and  the  scrapings  are  boiled  with  water,  and  the  wax  thus 
moltpn  is  collected  from  the  surface  of  the  liquid,  in  which  the  impurities  remain. 
Xhis  kind  of  wax  fuses  at  83** — 86  \  and  is  very  likely  identical  with  the  Camauba 
w^ax.  6.  The  Myrica  wax,  from  the  Myrica  cenfera,  is  obtained  by  boiling  the 
fruit  of  the  plant  with  water.  It  is  imported  from  some  of  the  Southern  States  of 
the  Union.  The  variety  of  tliis  wax  known  as  Ocuba  wax  is  obtained  from  the 
same  plant  and  in  the  same  manner,  in  the  district  of  Para,  Brazil,  along  the  banks 
of  the  Amazon  river.  This  wax  has  an  olive-green  colour,  and  fuses  at  36""  to  48**. 
rt  is  used  in  America  for  making  candles.  We  may  add  here  that  of  all  countries  in 
£urope,  if  not  in  the  world,  Corsica  produces  the  largest  quantity  of  wax.  In 
ancient  as  well  as  medieval  times,  the  inhabitants  paid  their  taxes  in  wax,  and 
supplied  200.000  lbs.  annually.  Since  wax  is  to  honey  in  quantity  as  z  to  15, 
the  Corsicans  must  have  gathered  3,000,000  lbs.  of  honey. 

The  Maunc  of  Wax  oudiM.  Wax  candleB  are  most  frequently  made  by  pouring  the  molten 
wax  on  to  the  wioks.  For  this  purpose  the  moks  are  hung  upon  frames  and  covered  with 
metal  tags  at  the  ends  to  keep  the  wax  from  oovering  the  cotton  in  those  places ;  these 
frames  are  carried  to  a  heater,  where  the  wax  is  melted.  The  frames  can  turn  round,  and 
as  they  turn  a  man  takes  a  vessel  of  wax  and  pours  it  first  down  one,  and  then  the  next, 
and  so  on.  When  he  has  gone  once  round,  if  the  wax  is  sufficiently  cooled  he  gives 
the  first  wick  a  second  coat,  then  the  third,  &c.,  until  they  are  all  of  the  required  thick- 
ness. The  candles  are  now  rolled  on  a  marble  slab  or  wooden  board  for  the  purpose  of 
imparting  the  proper  shape.  The  conical  top  is  moulded  by  properly  shaped  tubes,  and 
the  bottoms  are  out  oft  and  trimmed.  The  moulding  of  wax  candles  is  now  rarely  if  ever 
performed,  but  if  executed,  it  is  done  in  precisely  the  same  manner  as  described  for 
stearine  and  paraffin  candles.  Wax,  however,  is  not  a  very  suitable  material  for  moulding, 
in  consequence  of  its  shrinking  on  cooling,  as  well  as  its  pertinacious  adherence  to 
the  moulds.  ^  The  wick  for  moulded  wax  candles  must  be  previously  soaked  with  wax  in 
order  to  prevent  the  candles  becoming  as  it  is  termed  honey -combed.  The  wax  is  molten 
on  a  water-bath,  and  glass  moulds  are  used  in  preference  to  metal  ones,  as  well  for 
the  smooth  surface  glass  imparts  as  for  the  more  ready  removal  of  the  candles  when  cold. 
In  order  to  prevent  the  breaking  of  the  glass  moulds,  they  are  covered  with  gutta-percha. 
The  large  sized  fJtar  candles,  which  often  weigh  from  15  to  20  kilos.,  are  not  made 
by  either  of  the  two  methods  described,  but  by  hand.  The  wick,  partly  made  of  linen, 
partly  of  cotton  yam,  is  first  soaked  with  wax,  or  covered  with  that  material  cut  into  long 
strips,  rendered  soft  and  kneadable  by  the  aid  of  warm  water,  and  next  made  up  to  the 
required  thioknes#by  rolling  on  more  wax ;  or  a  quantity  of  wax  is  rolled  by  hand  into 
the  required  shape,  and  the  wiok  inserted  by  cutting  a  longitudinal  channel  in  the  mass  of 
wax  into  which  the  wick  is  placed.  The  channel  is  filled  up  with  wax  and  the  candle 
finished  by  rolling.  Very  recently  (1870)  Messrs.  Riess  have  constructed  a  press  for 
making  wax  candles.  The  arrangement  of  this  machine  seems  to  be  somewhat  similar  to 
the  press  used  for  making  continuous  lengths  of  lead  and  block- tin  pipes.  This  wax 
candle  press  is  heated  by  steam  so  as  to  render  the  wax  soft.  The  wick  is  inserted  into 
the  wax  in  such  a  manner  that  it  is  concentrically  surrounded  with  wax  when  ejected 
from  the  spout  of  the  eylinder  of  the  press,  thus  forming  a  continuous  candle,  which  is 
cut  up  into  lengths. 

The  wax  tapers  of  various  thickness  are  made  by  a  method  of  which  the  following  is 
an  outline : — In  the  first  place,  these  tapers  are  not  made  of  pure  wax,  but  of  wax  and 
tallow  mixed,  in  order  to  impart  flexibility ;  while  for  coloured  wax  resin  and  turpentine 
are  added  to  the  tallow.  The  wiok  of  the  tapers  should  be  very  unifomi,  and  the  strands 
of  yarn  intended  for  this  purpose  are  reeled  on  a  cylinder  or  drum  placed  at  one  end  of  the 
workshop,  while  at  the  other  end  is  placed  a  similar  drum.  Between  these  drums  is  placed  a 
shallow  copper  pan,  which  can  be  kept  warm  by  means  either  of  steam  or  a  charcoal  fire. 
This  vessel  is  filled  with  the  molten  wax,  and  provided  with  a  hook  at  the  bottom,  below 
or  through  the  opening  of  which  the  wick  is  drawn.  At  the  edge  of  the  pan  a  draw-iron 
is  fixed,  provided  with  circular,  somewhat  conical,  apertures  of  different  size,  arranged 
in  the  same  way  as  those  described  (see  p.  25)  for  wire-drawing.  The  wick  is  drawn 
through  the  wax,  put  under  the  hook,  and  through  the  aperture  of  the  drawing-iron,  and 

3  » 


634  CHEMICAL  TECHNOLOGY. 

next  reeled  on  the  other  cylinder  or  dnun,  which  is  very  slowly  tamed  xxMind  in  ate  ti 
giy«  the  wax  time  to  soUdify.  When  all  the  wick  has  been  thns  coated  with  yii« 
the  taper  is,  when  required  to  be  rendered  thicker,  drawn  a  second,  and  eren  a  third  lai 
fourth,  time  through  the  wax,  and  a  larger-sized  aperture  of  the  drawing-irofi.  j^ie  cd^ 
less  taper  thus  formed  is  cut  up  into  the  requisite  lengths. 

Bees* -wax  is  used  for  many  minor  purposes,  as  is  well  known.  Amongst  them,  sfi  of 
interest,  may  be  noted  its  selection  by  the  British  Qovemment  for  a  lubricating  mateiial 
for  small-arm  cartridges  and  also  for  breech-loading  cannon.  This  is  due  partly  to  iu 
power  of  resisting  oxidation,  and  its  consequent  freedom  from  corrosive  action  upon 
metal  surfaces  (le^,  <bc.),  and  partly  to  its  peculiar  action  as  a  lubricating  material,  fej 
producing  an  extremely  smooth  surface  upon  the  bore  of  the  arm  as  it  is  swept  throng 
upon  the  discharge.  It  also  prevents  particles  of  paper  or  powder  residne  from  attachbig 
themselves  to  the  met^,  and  thus  is  the  best  anti-fouling  agent  known. 

sp«"»^^2[™*««"       Spermaceti  is  the  solid  portion  of  the  mI  of  the  sperm  wbak, 

Physeter  maerocephalus^  a  cetacean  belonging  to  the  mammalia,  and  living  in  some  of 

tlie  seas  of  the  southern  hemisphere  of  our  globe.    The  spermaceti  is  obtained  from 

the  oil  by  filtration,  and  is  subsequently  hardened  and  whitened  by  pressure,  and 

refining  with  a  weak  alkaline  ley.    In  some  cases  a  very  large  and  full-grown  qpem 

whale  may  yield  100  cwts.  of  sperm  oil,  containing  from  30  to  60  cwts.  of  spennao^ 

This  material  as  met  with  in  commerce  is  a  white,  mother-of-pearl  like,  glossy, 

foliated,  crystalline,  semi-transparent  substance,  fatty,  and  lubricating  to  the  tondu 

of  sp.  gr.  =  o'943,  fusing  at  43^,  and  distilling  unaltered  at  360^    It  is  soluble  in 

about  30  parts  of  boiling  alcohol,  becomes  yellow  by  exposure  to  air,  and  may  be 

pulverised.    According  to  Mr.  Smith  and  Dr.  Stenhouse,  spermaceti  consists  of  pal- 

mitate  of  cetyl,.C34H640a  =  CieHsiCCie^sa)^* '»  ^^^  according  to  Heintz  (i85i)^spcr- 

maceti  is  a  combination  of  cetyl  with  stearic,  palmitic,  myristic,  oocinic,  and 

cetinic  acids.     Spermaceti  candles  are  made  extensively,  if  not  exdnaively,  is 

England,  where  they  were  first  manufactured  about  1770.     These  candles  have 

always  been  greatly  prized  for  their  transparent  whiteness,  high  illnminating  pover. 

and  regular  burning;   and  notwithstanding  their  costHness,  are  largely  ua^  and 

exported  to  British  India.     In  order  to  check  the  great  tendency  of  spennaoeti 

to  crystallise,  5  to  10  per  cent  of  white  wax  or  a  little  paraffin  is  added  to  Uie  fnsed 

mass  intended  to  be  moulded  into  candles,  by  a  process  exactly  similar  to  that 

already  described  for  stearine  candles. 

C  H  \  \^^\ 

o]7«erin«.        Glycerine,  O3H8O3  (as  triatomic  alcohol,       3g3l03,*r  C3H3   {OHL 

is  present  in  the  shape  of  glycerides  in  combination  with  solid  and  fluid  £atty  add 
to  an  amount  of  8  to  9  per  cent,  and  may  be  separated  by  treatment  with  bases 
(potash,  soda,  lime,  baryta,  oxide  of  lead),  or  with  acids  (sulphuric  acid),  and  tfshm 
ehlorides  (chloride  of  zinc),  also  by  means  of  superheated  steam,  or  yery  hot  water 
without  the  formation  of  steam,  in  closed  vessels.  Glycerine  is  also  formed  as  a  oca- 
stant  product  by  the  alcoholic  fermentation  of  dextrose,  levulose,  and  lactose.  Aceord- 
ing  to  Pftsteur*s  researches,  the  quantity  of  glycerine  thus  formed  amonnts  to 
3  per  cent  of  the  weight  of  the  sugar.  Glycerine  was  first  disoovered  by 
whilst  engaged  in  preparing  lead  plaster.  Industrially,  glycerine  has  been  used  &r 
only  twenty-five  years,  in  consequence  of  the  large  quantity  of  glycerine  obtained  M 
a  by-product  in  the  manufacture  of  soap  as  well  as  of  stearine  candles.  The  Tininnn 
of  the  potato,  and  molasses  from  beet-root  sugar  distillation,  and  likewise  the 
residue  of  tiie  distillation  of  wine,  vinasse  proper,  as  carried  on  in  the  South  di 
France,  contain  large  quantities  of  glycerine. 
As  regards  the  preparation  of  glycerine  on  the  large  scale,  it  is  mainly  a 


AUTIFICIAL  LIGHT.  635 

of  purification  of  the  glycerine  obtained  in  the  industrial  preparation  of  the  stearic 
acid  from  neutral  fats  above  described.  When  the  lime  saponification  process  is 
used,  the  glycerine  remains  dissolved  in  the  water  after  the  separation  of  the  in- 
soluble lime-soap.  The  lime  also  dissolved  having  been  eliminated  by  either  sulphuric 
or  preferably  ozalic  acid,  the  evaporation  of  the  liquid  to  the  consistency  of  a  syrup 
will  3rield  a  glycerine  pure  enough  for  many  technical  purposes.  When  the  decom- 
position, or  rather  dissociation,  of  the  neutral  fats  is  efiected  b^  means  of  superheated 
steam,  the  glycerine  and  fatty  acids  (see  p.  634)  are  both  obtained  in*  pure  state,  pro- 
vided the  heat  be  kept  at  or  below  310^,  because  otherwise  a  portion  of  the  glycerine 
is  decomposed  with  evolution  of  .vapours  of  acroleine.  The  fact  that,  when  f&ts  are 
saponified  with  sulphuric  acid,  the  snlpho-glyceric  acid  in  aqueoos  solution  yields 
readily  by  evaporation  glycerine  and  sulphuric  acid,  may  be  applied  for  the  prepara- 
tion of  glycerine.  The  soap  boiler's  mother-liquor,  now  the  most  important  source 
of  crude  glycerine,  may  be  made  available  for  its  production,  according  to  Keynold's 
patent,  in  the  following  manner : — The  mother-liquor  is  first  concentrated  by  evapo- 
ration ;  the  saline  matter  which  is  thereby  gradually  separated  being  removed  from 
time  to  time.  When  the  fluid  is  sufficiently  concentrated — ascertained  by  the  boiling- 
point  having  risen  to  116° — ^it  is  transferred  to  a  still,  and  the  glycerine  distilled  oflf 
by  means  of  superheated  steam  carried  into  the  still.  Tlie  distillate  is  next  concen 
trated  and  brought  to  the  consistency  of  a  syrup  in  a  vacuum  pan. 
According  to  the  researches  of  A.  Metz  (1870) : — 

A  sp.  gr.  (at  i7'5°j  of  i'26i  corresponds  to  100  per  cent  of  anhydrous  glycerine. 

»»  »f  1*240  ,,  „  94  ♦«  »»  M 

»»  »1  *    232  ,,  „  90  ,,  ,,  ,, 

*  i»  »»  *  200  •,  „  OO  „  „  ,, 

♦«  ♦»  *   ^79  »»  ?»  /^  •»  »♦  »» 

»»  »»  I  ^53  »»  »»  "^  »»  »«  »» 

»»  »»  *  '*5  »»  »«  5^  »♦  ♦»  »• 

»t  »»  I  ^*7  »»  •*  45  •♦  ♦•  f» 

»t  »»  *  ^^99  »»  »»  4^  ♦»  »»  »» 

»t  »»  ^*^3  »»  »»  3^  »»  »'  »» 

»»  f.  1*048  „  ,,  30  „  „  „ 

»»  »»  1*024        »»        »»  ^®  »»  »»  »» 

Glycerine  has  become  largely  employed  owing  to  its  oily  consistency,  also  to  the 
fiEu^t  that  at  ordinary  temperatures  it  is  fluid,  and  does  not  freeze  when  quite  concen- 
trated even  at  —  40**  ;*  further  to  its  stability,  its  pleasant  sweet  taste  when  quite 
pure,  its  harmlessness,  its  great  solvent  power  for  many  substances,  and,  lastly,  to 
its  low  price. 

Among  the  many  applications  of  glycerine  are  the  following : — For  keeping  clay  moist 
for  modelling  purposes;  for  preventing  mustard  from  drying  up;  for  keeping  Bnuff 
damp ;  preserving  fruit ;  sweetening  liqueurs ;  and  for  the  same  purpose  for  wine,  beer, 
and  malt  extracts.  Glycerine  is  also  useful  as  a  lubricating  material  for  some  kinds  of 
ULachinery,  more  espeoiidly  watch  and  chronometer  works,  because  it  is  not  altered  bv 
eontact  with  air,  does  not  become  thick  at  a  low  temperature,  and  does  not  attack  such 
metals  as  copper,  brass,  Ac.    Olyoerine  is  used  in  the  making  of  copying  inks,  and  of  a 


*  The  freezing  of  glycerine,  observed  in  1867,  bv  Wr.  W.  Crookes,  in  London ;  by  Sarg,  at 
Vienna ;  and  Dr.  Wdhler,  at  Gottingen,  proves,  however,  that  under  certain  conditions, 
and  while  being  transported  from  one  place  to  another,  glycerine  may  become  solid  even 
at  a  temperature  not  so  low  as  the  freezing-point  of  mercury. 


636  CHEMICAL  TECBNOLOGY. 

great  many  cosmeticB.  In  order  to  render  printing  ink  Bolnble  in  water — its  insQlnUlitr 
is,  however,  its  greatest  advantage — it  has  been  proposed  to  use  glycerine  for  its  pie|»r»- 
tion  instead  of  linseed  oil.  Glycerine  is  an  excellent  solvent  for  many  substances,  indadiEg 
the  tar-colonrs  ^aniline  blue,  cyanine,  aniline  violet)  and  alizarine.  Tn  order  to  render 
paper  soft  and  pliable  glycerine  is  added  to  the  pulp.  To  the  quantity  of  pulp  required  fa 
making  100  kilos,  of  dry  paper,  5  kilos,  of  glycerine,  sp.  gr.  1-18,  are  sufficient.  It  is  net 
out  of  placa  here  to  mention  the  following  useful  weavers*  glue  or  dressing,  eckznposed  of^ 
Dextrine,  5  parts  ;  glycerine,  12  parts ;  sulphate  of  alumina,  i  part ;  and  water,  30  puts. 
By  the  use  of  thi^  mixture  the  weaving  of  muslins  need  not  be — as  was  formerly  the  case— 
carried  on  in  damp  darkened  cellars,  but  may  be  performed  in  well-aired  and  well-tightei 
rooms.  It  is  said  that  leather  driving  belts,  made  as  usual  of  weakly  tanned  leather, 
when  kept  in  glycerine  for  twenty-four  hours,  are  not  so  liable  to  fray.  A  glyeerine  eola- 
tion is  now  largely  used  instead  of  water  for  the  purpose  of  filling  gas-meters,  as  sock  1 
Bolutic  n  does  not  freeze  in  winter  nor  evaporate  in  suihmer.  Santi  uses  ^yoerine  far  tke 
compasses  on  board  screw-steamers,  in  order  to  protect  the  inner  compass  box  against  &e 
vibrations  caused  by  the  motion  of  the  propeller.  It  is  impossible  to  ent^*  hers  into 
minute  details  on  the  use  of  glycerine  ;  suffice  it  to  observe  further  that  it  is  employed  for 
preserving  anatomical  preparations,  for  rendering  wooden  casks  impervious  to  petk^eGm 
and  other  oils ;  for  the  preparation  of  artificial  oil  of  mustard  or  stdpho-cyan-ally],  nade 
by  treating  glycerine  with  iodide  of  phosphorus,  whereby  iodide  of  aJlyl  is  formed,  vhkih 
on  being  dissolved  in  alcohol,  and  next  distilled  with  sulphocyanide  of  potassium,  yields 
sulpho-cyan-allyl.  When  glycerine  is  treated  with  very  concentrated  nitric  acid  or  'vitk  a 
mixture  of  strong  sulphuric  and  nitric  acids,  it  is  converted  into  nitro-glycerine  (trinitiiDe 
or  glyceryl  nitrate)  (see  p.  158),  largely  {used  for  various  purposes,  the  preparatiun  of 
duidine  and  dynamite,  &o.  A  mixture  of  finely  powdered  litharge  and  very  concentrated 
glycerine  made  into  a  paste  forms  a  rapidly  hardening  cement,  especially  useful  as  a  cover 
for  the  corks  or  bungs  of  vessels  containing  such  fluids  as  benzol,  essential  oils,  benzoliae, 
petroleum,  d^c,  the  cement  being  impermeable  to  these  liquids. 

II.  Illumination  hy  Means  of  Lamps. 

^'^'slbSi^i^'*''  The  fluid  substances  in  use  as  illuminating  materials  are 
either : — a.  Fixed,  or  fatty  oils,  h.  Volatile  oils,  which  again  are  either  essentel 
oils,  as,  for  instance,  camphine  ;  or  products  obtained  from  tar,  as  photogen  ani 
solar  oil ;  or,  finally,  native,  as  petroleiun.  Among  the  fixed  or  fatty  oils,  rape-5<«d 
oil,  colza  oil,  olive  oil,  fish  oil,  and  the  dry  papaver-seed  or  poppy-seed  oil.  «« 
chiefly  used. 

^*°'"^S£**^*°*  In  order  to  refine  these  oils  so  as  to  render  them  more  snitaUd 
for  combustion  in  lamps,  they  are  treated  with  about  2  per  cent  of  their  weight  of 
strong  sulphuric  acid,  or  with  a  concentrated  solution  of  chloride  of  idnc.  TIms* 
substances  do  not  act  upon  the  oil,  but  destroy  or  coagulate  any  imparities,  as  mad- 
laginous  and  colouring  matters,  present.  The  acid  or  chloride  of  zinc  is  removed  hf 
washing  with  water,  after  which  the  oil  is  filtered,  and  in  order  to  remove  aaj 
mechanically  adhering  water,  it  is  kept  for  a  considerable  time  at  a  temperature  d 
about  100°,  being  heated  by  means  of  steam  circulating  in  pipes  fitted  in  the  tanks. 
Now  oil  is  frequently  extracted  from  the  seeds  by  means  of  sulphide  of  carbon  <9ee 
p.  199).  The  oils  which  serve  for  the  purposes  of  illumination  are  termed  lamp-dk. 
The  introduction  of  paraffin  and  petroleum  oils  has  caused  a  very  considexaUy 
decreased  consumption  of  the  fixed  i'atly  oils. 

Lampi.  Lamps  were  known  and  used  even  in  remote  antiquity,  and  were  invented, 
it  is  believed,  by  the  Egyptians.  While  it  cannot  be  denied  that  as  regards  oatwari 
form  the  lamps  of  the  ancients  were  graceful,  their  technical  construction  was  nide, 
and  remained  so — ^not  taking  into  account  some  minor  improvements  made  in  the 
seventeenth  and  eighteenth  centuries,  among  which  improvements  are  the  intxodue- 
tion  of  the  glass  cylinders  by  the  Parisian  apothecary  Quinquet,  and  the  inve&liaa 
of  the  hollow  and  circular  burner  by  Argand,  1786 — ^antil  chemistry  discovered  a 


ARTIFICIAL  LIGHT.  637 

Bound  theory  of  combustion  and  illumination,  and  until  phjsicial  science  ascertained  the 
principles  of  the  supply  of  oil  and  means  of  estimating  the  illuminating  power  of  the 
flame  of  lamps,  and  further  until  the  refining  of  oil  supplied  a  purer  and  more  fluid 
illuminating  material.  A  still  greater  step  to  improvement  in  light  obtained  from 
lamps  was  tlie  discovery  of  the  petroleum  and  paraffin  oils  and  the  construction  of 
lamps  suitable  for  their  combustion.  These  oils  have  now  become  of  general  use 
wherever  gas  is  not  obtainable.  In  passing,  it  may  be  observed  that  in  no  country  is 
gaa  so  extensively  made  on  the  small  scale  as  in  Scotland,  where  farm-houses, 
country  seats,  and  other  dwellings,  not  conveniently  situated  near  to  public  gas-works, 
are  very  generally  provided  with  small  gas-works,  in  which  tlie  excellent  Cannel 
coal  of  tlie  country  is  employed,  yielding  a  very  pure  and  highly  illuminating  gas  at 
a  reasonable  cost,  and  with  the  advantage  that  gas  is  allowed  by  the  insurance  com- 
panics  as  light  in  stables  and  otlier  places  where  readily  inflammable  materials  are 
kept,  while  lamp  and  candle  lights  are  absolutely  prohibited  in  such  places,  for 
fear  of  causing  Are.  Some  of  tlie  many  inventions  and  improvements  of  oil  lamps 
made  during  tlie  last  forty-five  to  thirty  years  are  quite  forgotten ;  the  moderator 
colza  lamp  has  been  nearly  superseded  by  improved  paraffin  and  petroleum  oil  lamps, 
and  as  we  do  not  treat  in  this  work  on  the  history  of  technology,  but  on  technology 
as  now  developed,  we  cannot  enter  into  any  further  historical  details,  but  proceed 
witli  our  subject. 

Viewing  lamps  generally,  we  observe  the  same  parts  as  in  a  candle,  viz.,  the 
illuminating  material  and  the  wick.  As  regards  the  illuminating  material,  it  is  in 
lamps  as  well  as  in  candles  fluid,  tlie  diflerence  consisting  in  that  with  candles  the 
&tty  material  is  molten  near  the  end  of  the  wick,  a  cup  of  molten  fat  being  formed, 
while  with  lamps  the  illuminating  material  is  fluid  at  the  ordinary  temperature,  and 
therefore  kept  in  a  vessel  or  reservoir  from  which  the  wick  is  uninterruptedly  and  as 
uniformly  as  possible  supplied.  The  difierences  observed  in  tlie  construction  of  the 
various  kinds  of  lamps  depend  partly  upon  the  illnminating  material  employed 
(colza  oil,  petroleum  oil,  sperm  oil,  &c.) ;  partly  upon  the  shape  of  the  wick  and  upon 
the  mode  of  supplying  air  to  tlie  flame,  either  with  or  without  a  glass  chimney ; 
farther,  upon  the  shape  of  the  oil  reservoir  and  its  position  in  reference  to  the  w^ick ; 
and  finally  and  chiefly,  upon  the  method  and  means  by  which  the  illuminating 
material  is  carried  to  that  portion  of  the  wick  where  the  combustion  is  intended  to 
take  place ;  that  is  to  say,  whetlier  the  illuminating  material  is  only  absorbed  by  the 
capillary  action  of  the  cotton  wick,  or  whether  this  action  is  aided  by  hydrostatic  or 
mechanical  means. 

Colza  oil  and  mineral  oil — ^be  the  latter  obtained  from  the  tar  yielded  by  tlie  dry 
distillation  of  certain  kinds  of  coal  or  peat,  or  be  it  derived  from  native  petroleum — 
difler  from  each  other  as  regards  their  properties  as  illuminating  materials  in  tlio 
following  particulars : — i.  Colza  oil  is  not  volatile  at  the  ordinary  temperature,  and 
not  even  when  heated  to  above  100°.  It  is  hence  devoid  of  smell,  and  is  not  by  itself 
ignitable  unless  it  be  first  heated  to  a  such  a  high  temperature  (about  200°)  as  to 
give  ofl"  products  of  dry  distillation — ^in  fact,  become  decomposed  and  converted  into 
oil-gas.  The  mineral  oil,  even  that  kind  which  is  termed  odourless,  possesses  some 
odour,  and  loses  in  weight  or  is  gradually  volatilised  by  exposure  to  air.  At  a 
higher  temperature  it  is  volatilised  and  can  be  distilled  over  unaltered,  while  at  a 
still  more  elevated  temperature  it  is  nearly  all  converted  into  illnminating  gas. 
2.  Colza  oil  consists  of  carbon,  hydrogen,  and  oxygen,  according  to  the  formula 


638  CHEMICAL  TECHNOLOGY. 

OxsHiaO^.    In  the  dry  distillation  which  this  oil  undergoes  in  the  wick  jast  below 
the  flame  it  is  converted  into  elayl  gas  and  carbonic  acid : — 

colza  on.  .C„H.sO.=340.  yield(9  -l-«lee  of  ^^^^,0,   Z^ 

consequently  25*8  per  cent  of  the  colza  oil  becoming  carbonic  acid  does  not  con- 
tribute anything  to  tlie  illuminating  power  of  the  flame,  but  deprives  the  half  of  the 
volume  of  the  elayl  gas  of  its  illuminating  power.  Befined  colza  oil  burns  in 
well-constructed  lamps  very  completely,  yielding  only  the  odouiiess  products  of 
combustion,  viz.,  carbonic  acid  and  water.  3.  Petroleum  oils  are  mixtures  of 
different  hydrocarbons,  very  probably  of  the  higher  members  of  that  homologous 
series  of  which  marsh  gas  is  the  primary.  Petroleum  oil  begins  to  boil  at  250°,  and 
is  at  a  higher  temperature  decomposed,  yielding  gaseous  products,  marsh  gas  and 
elayl  gas,  and  soot,  or  unbumed  carbonaceous  matter.  The  quantity  of  carbon 
contained  in  petroleum  oil  is  far  larger  than  that  contained  in  colza  oil ;  hence  the 
former  when  burning  in  contact  with  air  and  without  a  glass  chimney  exhibits  a  sooty 
flame,  but  this  changes  at  once  into  a  vety  bright  flame  when  by  the  addition  of  a 
glass  chimney  the  increased  draught  of  air  causes  tlie  complete  combustion  of  the 
excess  of  carhon.  Wliile  colza  oil  only  reaches  tlie  flame  in  the  state  of  gas,  the 
petroleum  oils  come  into  the  flame  as  vapour,  and  the  construction  of  tlie  petroleum 
oil  lamps  ought  to  be  so  contrived  that  the  combustion  be  as  complete  as  possible  in 
order  to  prevent  any  disagreeably  odorous  vapours  or  gaseous  matters  escaping  un- 
consumed.  As  regards  accidents  from  fire,  petroleum  or  paraffin  oil  lamps  are,  with 
proper  precautions  and  good  quality  of  oil,  not  attended  witli  greater  danger  than 
that  of  the  use  of  colza  oil.  4.  As  is  well  known,  colza  oil  is  a  fatty  lubricating  oil, 
while  paraffin  or  petroleum  is  not  so :  in  consequence  of  tills  diflerence  the  former 
may  be  used  in  lamps  in  which  the  oil  is  carried  to  the  wick  by  mechanical  means — 
either  by  clockwork  or  spiral  springs  acting  upon  one  or  more  more  pistons,  as  in  the 
Garcel  and  moderator  lamps.  Because  the  fatty  nature  of  colza  oil  aa  well  as  its 
lubricating  property  keeps  the  packing  of  the  pistons  oil-tight  as  well  as  lubricated, 
it  is  clear  that  the  paraffin  oils  cannot  be  used  in  such  lamps. 

Independently  of  the  illuminating  material,  the  construction  of  a  normal  lamp 
should  be  such,  that  (i)  it  yields  a  maximum  of  light  uniformly  for  a  definite  time 
(three  to  eight  hours).  This  condition,  a  consequence  of  the  complete  and  equal 
combustion  of  the  illuminating  material,  can  only  result  from  (a)  the  use  of  a 
purified  illuminating  material ;  (/3)  the  use  of  a  wick  of  uniform  thickness  and 
structure ;  (y)  the  uniform  supply  of  illuminating  material  to  the  flame  ;  (B)  by  suffi- 
ciently strong  heat  at  the  point  where  tlie  combustion  takes  place,  so  that  the 
conversion  of  the  illuminating  material  into  gases  may  be  complete ;  (c)  by  the 
regulation  of  the  supply  and  access  of  air.  Too  small  a  supply  of  air  often  gives 
rise  to  a  sooty  flame,  while  too  large  a  supply  causes  a  lowering  of  the  temperature 
of  the  flame,  and  hence  also  separation  of  soot  and  formation  of  odorous  products 
of  incomplete  combustion ;  and  even  if  these  results  do  not  occur  and  a  complete 
combustion  obtains,  too  large  a  supply  of  air  impairs  considerably  the  illuminating 
power  of  the  flame ;  [Z)  the  means  of  regulating  the  size  of  the  flame  must  be 
perfect.  2.  The  lamps  ought  to  be  so  constructed  that  the  light  evolved  be  not 
wasted.    The  well-known  reflectors  and  lamp  caps  aid  the  illnmination  greatly. 


ARTIFICIAL  LIGHT,  639 

The  reservoir  for  the  oil  should  be  in  the  first  place  so  situated  that  its  shadow  fiills 
on  some  unimportant  part  of  the  field  to  be  illuminated ;  and  secondly,  so  arranged 
that  the  point  of  gravitation  of  the  lamp  be  maintained. 

vaiioosKiads  of  Lamps.  Taking  the  manner  of  conveying  the  illuminating  material  by 
means  of  the  wick  to  the  flame  as  a  basis  for  the  division  of  lamps  into  various  kinds, 
we  distinguish  the  following : — 

I.  Suction  lamps,  in  which  the  oil  is  simply  sacked  up  by  the  capillary  action  of  the 
cotton  wick  from  the  reservoir.  According  to  the  sitnation  of  the  oil  reservoir  with 
reference  to  the  wick,  suction  lamps  can  be  subdivided  into : — a.  Those  in  which  the 
oil  reservoir  is  placed  at  about  equal  height  with  the  flame  of  the  burning  wick. 
/3.  Lamps  in  which  the  oil  reservoir  is  placed  higher  than  the  burner.  These  lamps  have 
a  detachable  oil  reservoir,  which,  having  been  filled,  is  inverted  into  a  fixed  vessel, 
an  arrangement  common  in  readiug-lampu  for  boruing  colza  oil.  2.  Pressure  lamps,  in 
which  in  addition  to  the  capillarity  of  the  wick,  mechanical  or  physical  means  are 
employed  for  the  purpose  of  forcing  the  illuminating  material  to  the  wick.  In  this  variety 
the  oil  reservoir  is  placed  at  the  foot  of  the  lamp.  According  to  the  method  of  forcing 
the  oil  to  the  wick,  pressure  lamps  are : — a.  Aerostatic,  in  which  the  principle  is  that  of 
Hero*s  fountain ;  into  the  closed  oil  reservoir  air  is  forced,  and  this  while  trying  to  make 
equilibrium  with  the  outer  air,  presses  upon  the  oil  and  forces  it  upwards  through  a 
tube  to  the  burner.  /3.  Hydrostatic  lamps,  based  upon  the  principle  of  the  communicating 
tubes,  in  which  the  heights  of  fluids  of  different  specific  gravity  making  equilibrium 
together  stands  in  the  inverse  relation  to  their  specific  gravity.  The  fluid  which  has  to 
make  equilibrium  with  the  oil  and  force  it  up  towards  the  cotton  wick  should  be  specific- 
ally heavier  than  the  oil.  j.  Statical  lamps,  in  which  the  oil  is  forced  from  the  reservoir 
at  the  foot  of  the  lamp  to  tne  burner  by  the  pressure  either  of  the  weight  of  a  solid  body 
(for  instance,  a  leaden  weight),  or  by  the  direct  weight-pressure  of  a  piston  moving  down- 
wards in  the  oil  reservoir,  d.  Mechanical  lamps,  in  which  the  oil  contained  in  the 
reservoir  is  forced  upwards  to  the  burner  either  (a)  by  means  of  pumps  set  in  motion  by 
wheelwork  similar  to  that  of  a  large  watch  (Carcel  lamps  with  clockwork),  or  (b)  by  the 
pressure  of  a  spiral  spring  acting  upon  a  solid  piston  (moderateur  lamps).  In  the  mechanical 
lamps  the  oil  is  carried  to  the  wicks  in  larger  quantity  than  is  required  for  the  momentary 
consumption ;  this  excess  of  oil  returns  continually  to  the  oil  reservoir.  The  lamps  here 
alluded  to  are  only  suited  to  burn  colza  oil,  and  we  ought  to  observe  that  those  mentioned 
under  a,  /3,  and  y,  are  obsolete,  for  the  very  good  reason  that  they  have  been  superseded 
by  better  and  more  simple  contrivances ;  this  applies  also  to  the  clockwork  lamps  which 
were,  even  when  well  made,  very  liable  to  get  out  of  order  and  required  very  pure  oil  to 
work  well.  3.  The  lamps  for  burning  the  paraffin  and  petroleum  oils  are  all  simple 
suction  lamps,  the  reservoir  being  placed  under  the  wick  and  in  its  axial  prolongation. 
The  lower  specific  gravity  and  the  greater  fluidity  of  the  oils  greatly  aid  the  capillary 
action  of  the  wick,  and  renders  all  pressure  apparatus  superfluous.  The  so-called 
benzoline  sponge-lamps  also  belong  to  the  category  of  suction  lamps,  the  very  volatile  and 
highly  combustible  benzoline  (obtained  from  the  crude  petroleum)  being  absorbed  by  the 
sponge,  more  commonly  cotton  waste  or  tow,  and  thence  slowly  carried  by  capillary  action 
into  the  wick. 

soetion  Liuniw.  I.  To  this  kind  belong  all  the  lamps  in  which  the  oU  is  simply  cairied  to 
the  flame  by  the  capillary  action  of  the  cotton  wick,  the  oil  reservoir  being  placed  somewhat 
below  the  burning  end  of  the  wick.  According  to  the  situation  of  the  oil  reservoir  in 
reference  to  the  wick,  suction  lamps  can  be  divided  into  (a),  those  in  which  the  oil 
reservoir  is  placed  nearly  at  the  same  height  as  the  burning  wick.  Here  we  have  to 
observe  the  two  following  conditions,  viz. : — (a)  the  burning  wick  ia  placed  in  the  oil 
reservoir  itself,  as  may  be  observed  in  the  kitchen  lamp  and  antique  lamp ;  or  (b),  the  oil 
reservoir  and  burner  are  separated  from  each  other,  the  reservoir  being  placed  by  the  side 
of  the  burner,  or,  as  is  the  case  in  the  ring  lamps,  at  the  circumference  of  the  burner, 
which  is  in  the  centre.  /3.  Those  lamps,  the  oil  reservoir  of  which  is  placed  higher  than 
the  burner,  as,  for  instance,  in  the  so-called  reading  lamp. 

Among  the  suction  lamps  are  the  following : — ^In  the  antique  lamp,  Fig.  271,  the  wick,  a 
skein  of  cotton,  is  placed  in  an  open  or  closed  oil  vessel,  the  burning  end  of  the  wick 
simply  protruding  from  the  spout.  This  land  of  lamp  is  technically  very  imperfect, 
because,  in  the  first  place,  the  wick  has  to  suck  up  the  oil,  when  the  level  of  that  fluid 
gradually  sinks  by  the  burning  of  the  lamp,  to  a  height  far  too  great  for  its  capillary 
power ;  hence  the  flame  will  by  lack  of  sufficient  oil  become  gradually  more  and  more 
lurid,  and  at  last  extinguished  altogether  before  aXL  the  oil  is  consumed.  In  consequence 
of  the  thickness  of  the  wick  the  combustion  is  incomplete,  owing  to  want  of  sulioieni 


CHEMICAL   TECHNOLOGT. 


1 


MCMs  of  ail,  the  lamp  thus  burning  witb  a  Boot;  flume ;  while  the  body  of  the  Itaf 
throws  a  great  ahndoir.  Thta  last  defect  is  legs  marked  in  a  kiud  of  kitchen  lamp,  eihi- 
bited  in  lateral  projection  in  Fig.  172,  and  riewed  in  plan  in  Fig.  273,  as  by  meaOE  (d  tbe 
HpoQt  the  distance  between  the  oil  reservoir  and  ths  flame  is  increaaed,  or,  in  other  wonii, 
the  angle,  cab,  rendered  more  acnte.  The  Bo-cnlled  Worm's  lamp,  Figa,  174  and  275,  ia 
former  days  much  ased  in  the  Rhine  proyinars,  shonl  1  be  noted  on  acconnt  of  the  tbi^al 
the  wick,  I,  which  is  composed  of  a  Qat  woven  cotton  band,  instead  of  a  skein  of  ootton  jain, 
andthns  the  access  of  aii  to  all  parts  of  the  wick  is  hu  regulated  that  complete  o 


or  the  oil  takea  place.  The  wick  is  pnt  into  the  wick-holder,  r,  which  is  soldered  to  the  ring. 
d,  loosely  fixed  on  the  rim  of  the  glass  globe,  which  aerves  as  an  oil  reeerToir.  By  mciaBs 
of  the  raekwork  and  piuion,  e  and  t",  the  wick  can  bo  tnrned  upwards  and  duwnwanU.  ail 
the  flame  thas  regnl.ited.  The  part  a  is  placed  in  a  candleatick  or  in  any  other  snitabk 
stand.  A  glass  and  globe  may  bo  placed  over  and  around  the  flame.  Although  this 
lamp  is  an  improvenient  on  the  old-fashioned  kitchen  lamp,  it  has  many  defeeta. 


In  order  to  obviate  the  constant  decrease  in  the  intenaity  of  Iht 
light  as  the  level  of  the  oil  sinks  by  its  consumption,  as  happens  ia 
the  lamps  already  described,  it  is  simply  neeessar;  to  keep  the  oil  in  the  bnmer  as  maA 
OS  posBible  at  the  same  height.  This  can  he  effected  in  snction  lamps  by  placing  the  oil 
reservoir  higher  than  the  tmmer,  but  in  doing  this  it  becomes  necessary  bo  to  arrange  the 
construction  of  the  lamp  that  the  oil  be  gradually  carried  to  the  wick  in  snob  quantity  M 
is  required  tor  its  proper  bnmiog.  This  is  practically  carried  into  eCfect  as  eihihited  ia 
Fig.  176,  which  shows  in  vertical  section  a  kind  of  lamp  in  England  known  aa  a 
reading  lamp.  The  oil  reservoir  of  this  lamp  is  a  movable  vessel,  a,  of  tinned 
iron,  and  otosed  by  means  of  a  valva,  which  when  the  vessel  is  placed  vcrtioaliy, 
as  exhibited  in  the  cut,  leaves  the  neck  or  mouth  of  the  oil  flask  open  in  a  dovnvaid 


ARTIFICIAL  LIGHT. 


fl4* 


M  b  b  ;  bat  aa  ii 


■s  the  oil  h 


direction,  BO  aa  to  admit  of  the  oil  nmning  into  the  spso 

riaen  to  tba  lavel,  ee',  the  anicl  Mte  &b  a  hydrttolio  vaiTB,  anil  no  more  oil  can  How  ont  ot 

a  until  I17  the  baming  of  the  lamp  the  level  has  been  lowered.     The  ttibe  d  carries  the  oil 

to  the  wick-holder ;  while  at  c  a  BDiall  hole  m  made  for  the  pnrpoae  oE  giving  free  acoess 

of  ail  to  the  Bpace  between  the  sides  of  the  veeael  a  and  the  ojlindiioal  box  in  which  it 

is  placed.     When  more  oil  might  flow  to  the  wick  of  this  kind  of  lamp  than  can  be  burnt 

in  a  given  time  the  flame  ia  eitingniahed,  but,  as  usually  constructed,  these  lamps,  unleHS 

the;  be  tilted,  or  exposed  to  a  ver;  wann  atmosphere  (in  which  oaBe  owing  to  ths  eipan^ 

Bioa  of  the  air  in  the  Teeael  a  the  oil 

is  forced  out  of  it|  answer  the  purpose 

ver;  well,   giving  when  burnt  with 

suitable  wicka  and  well-refined  oalza 

oil  a  good  light,  bnt  less  intenae  than 

thftt  obtainable  from  the  better  Idnds 

of  parafBn  oil  lamps. 

pnaanLmpiL  2.  These  are  diatin- 
gniahed  Erom  aaotion  lamps  by  the 
node  in  which  the  oil  reservoir  is 
situated  in  reference  to  the  burner, 
the  former  being  not  placed  on  a 
level  with  or  higher  than  the  latter 
bat  below  it,  the  place  assigned  to 
the  reserroir  being  the  foot  of  the 
Ikmp ;  and  aa  the  capiUary  action  ol 

the  'nick  ia  not  anfficient  to  enable 
it  to  auck  the  oil  apwarda  to  so  great 

»  height,  an  arrangement  ia  required 
to  lift  the  oil  towards  the  wick,  while 

any  exceaa  of  oil  above  that  which  the 

flame  at  the  wick  ia  capable  of  con- 
suming trickles  downtrards,   and  is 

either  conducted  into  the  oil  reservoir 

or  collected  in  a  separate  vesael-   The 

presBure  lamps  are  certainly,  aa  far  aa 

oolza  oil  lamps  are   concerned,  the 

best  in  every  respect ;   bat  the  dif. 

ferent  varieties  of  these  lamps  to  be 

here  noticed  have  been  superseded  by 

the  moderateur. 
Aooording   to  the  contrivance   by 

means  ot  whioh  the  oil  in  preseore 

lamps  is  forced  np  to  the  wick,  we 

distiDgtxish : — ■ 
a.  Afrottatieal  Lampi-  —  In  these 

lamps  the  principle  ol  Hero'a  foun- 
tain ia  employed.    Air  is  forced  into 

the  dosed  oil  reserroir,  and  this  air 

while  trying  to  gain  its  equilibrium 

with    the  outer   air,  foroes   the  oil 

throagh  a  very  narrow  tube  upwards 

to  the  burner.     These  Umps  have, 

owing   to  great  complicity   of   cob-  iii\\>.\,i\ ,. ; i  ,  ,A,..,-isssss!8i 

■traction,  difficulty  of  management, 

and  of  Sliing  with  oil,  never  been  of  any  real  practical  oae- 
^.  In  the  hydrostatic  lamps,  also  now  obsolete,  though  ID  use  in  Frsnoe  in  the  earlier 

part  of  thia  century,  the  oil  is  forced  to  the  burner  by  the  pressure  of  a  coltuon  of  liquid 

upon  the  oil.    The  physical  principle  involved  is,  that  of  the  two  vessela  or  tubes  com- 

mnnicating  with  each   other,  and  filled  with  liquids  of  different  speciflo  gravity,  the 

height  of  these  fluids  Is  Inversely  as  the  specific  grsvitles  of  the  fiuida.     The  floid  which 

has  to  make  equilibriam  with  the  oil  ought  of  course  to  be  specifically  heavier  than 

the  oil,  and  onght  neither  to  act  injurionsly  upon  the  metal  of  which  the  lamp  is  made 

nor  npon  the  oil ;  while  the  liquid  should  not  freeze  very  readily.     Mercorj,  solation  of 

common   salt,  molasses,  aolutions  of  chloride   of  oaloium,  and  similar  UqnidB,  havs 

been  propoted  as  flaids  to  act  in  the  manner  allnded  to. 

3« 


-'ilBhiH 


64a  CHEMICAL  TECHNOLOGY. 

y.  Statical  Lamps, — In  these  lamps  the  oil  contained  in  the  reservoir  at  the  foot  of  lln 
lamp  is  either  forced  up  to  the  homer  by  the  pressure  of  a  solid  bodj  efzerted  upon  the 
oil,  or  by  the  pressure  of  a  piston,  acting  directly  and  by  its  own  weight,  forcing  the  dl 
upwards  through  a  narrow  tube.  In  the  first  instance  the  oil  is  put  iuto  a  bag  madeof  aay 
impermeable  and  sufficiently  pliable  material — leather,  caoutchouc,  or  waxed  aSk^  for 
instance — and  this  bag  is  placed  in  a  reservoir,  and  next  a  weight  is  made  to  press  npoo  the 
bag,  to  which  is  fitted  a  small  tube  communicating  with  the  burner.  The  second  amnfe- 
ment  with  the  piston  was  the  forerunner  of  the  mechanical  lamps;  but  as  statinl 
lamps  are  no  longer  made  further  details  are  unnecessary. 

Mechanical  Lamp«i.       S.  Thcsc  lamps  are  fitted  with  a  mechanical  contrivance  hj  the  aid  ei 

which  the  oil  is  forced  from  the  reservoir  in  the  foot  of  the  lamp  to  the  burner,  the  qiun- 

tity  of  oil  thus  supplied  to  the  latter  exceeding  the  requirements  at  any  given  moment  of 

the  burning  flame.    While  in  all  the  lamps  mentioned  the  contents  of  the  bfotiier  is  a 

constant  column  of  oil,  which  decreases  steadily  from  the  top  downwards,  or  is  renewed 

from  time  to  time,  the  oil  in  the  mechanical  lamps  is  a  constantly  flowing  stream,  whiek 

yields  the  wick  the  requisite  quantity  for  combustion,  while  the  excess  flows  downwndi 

into  the  reservoir. 

Two  kinds  of  mechanical  lamps  are  especially  noteworthy,  viz. : — 

doekwork  Lamp.       I.  The  clockwork  lamp,  pump  lamp,  Carcel  lamp,  invented  in  1800,  kj 

the  lamp  maker  Carcel,  at  Paris,  and  afterwards  improved  upon,    llie  pump  or  pnmpe — §i 

in  the  better  kinds  there  are  two,  unless  the  single  pump  is  double  acting — which  farees 

the  oil  from  the  reservoir  in  the  foot  of  the  lamp  is  moved  by  clockwork,  provided  witli  a 

strong  spring  which  is  wound  up.    The  pump  is  a  combination  of  suction-  and  foree- 

pump ;  in  some  lamps  of  this  kind,  instead  of  a  pump  an  Archimedean  screw  is  employed 

for  ^e  same  purpose.   In  the  socket  of  the  clockwork  the  oil  reservoir  and  pump  are  placed. 

The  tube  through  which  the  oil  is  forced  upwards  to  the  burner  is  carried  throng 

the  shaft  of  the  lamp.     The  oil  reservoir  and  the  clockwork  are  separated  from  eadi 

other  by  a  horizontal  metallic  plate. 

An  apparatus  of  simple  construction  often  employed  in  the  Carcel  lamp  is  sbown 
in  section  in  Fig.  277.  The  body  of  the  lamp  forms  the  cylinder,  in  which  the  horizontal 
piston  m  is  moved  to  and  fro,  while  the  space  n  above  it  is  connected  with  the  oil  pipe 

leading  to  the  burner.      The  space  below  the  body  or 
Fxo.  277.  cylinder  of  the  pump  is  connected  with  the  oil  reeervcir, 

and  divided  into  two  compartments  by  means  of  a  par- 
tition, and  further  provided  with  two  valves,  made  eithooi 
oiled  silk   or    of   gold-beaters'   sldn.      "When  the  pistoa 
moves  in  the  direction  from  <i  to  c,  oil  enters  from  ths 
reservoir  through  b,  while  the  oil  then  present  in  ths 
space  between  c  a  and  m,  is  forced  through  e  into  the  spaot 
n,  and  thence  into  the  oil  pipe.    The  space  n  serves  also 
the  purpose  of  an  air  vessel,  for  the  compressed  air  acts  as 
a  regulator  to  the  constant  flow  of  the  oiL     When  the 
piston  moves  in  the  direction  from  c  to  b,  oil  enters  thronfli 
a,  and  through  d  into  n.    The  clockwork  which  moves  the 
piston  rod  of  m  is  placed  below  the  oil  reservoir.     Hie 
arrangement  of  the    pump  is  such  that  the  bizmer  of 
the  lamp  is  supplied  with  a  larger  quantity  of  oU  thsa 
is  required  for  the  immediate  consumption  of  the  flame,  the  result  b^ng  that  ^m 
wick  and  the  burner  are  kept  cool,  and  the  carbonisation  of  the  wick  at  the  flame  is  pre- 
vented, and  thereby  the  capillary  action  of  the  cotton  left  unimpaired.    The  excess  of  aH 
flows  again  into  the  reservoir.     The  clockwork  of  these  lamps  requires  winding  vp 
about  once  in  twelve  to  fifteen  hours ;  and  for  burning  seven  to  eight  hours,  the  aetioD  is 
so  very  uniform  that  a  light  of  equal  intensity  is  maintained  for  that  time.    Sons 
of  these  lamps  are  fitted  with  an  external  knob,  which  can  be  used  for  the  pnipoee  el 
stopping  the  clockwork  by  arresting  the  motion  of  the  regulating  wings. 
Moderateor.  or  Moderator      2.  This  lamp  was  invented  in  1837  ^y  Franchot,  and  as  it  is  mote 
Lamp.  simple,  less  liable  to  get  out  of  order,  and  is  cheaper  than  the  dodc- 

work  lamp,  it  has  in  a  great  measure  superseded  the  use  of  the  latter.  The  essential  part 
of  this  lamp  is  a  large,  well-packed  piston,  which  resting  on  the  oil  contained  in  the 
reservoir,  is  forced  downwards  by  means  of  a  spiral  spring,  the  oil  finding  no  outlet  bat 
through  a  small  opening,  into  which  is  inserted  a  narrow  tube  leading  to  the  bomer.  A 
moderateur  lamp  is  exhibited  in  Fig.  278,  the  upper  part  of  the  cut  being  a  front, 
the  lower  a  sectional  view.  The  oil  reservoir  is  placed  in  the  hollow  body  of  ths 
Isjnp,  made  of  metal;  this  reservoir  serves  also  as  pump  body  or  cylinder  for  tks 
piston  ▲,  made  of  a  metallic  disc,  fitted  with  a  leather  rim  as  packing,  and  also  aetiag  as  a 


ARTinCIAL  LIOHT. 


643 


T»lve.  To  the  piiton  ii  fitted  tlie  rod  b,  vhich  through  nearly  its  entire  length  ia 
provided  with  t«etb,  biting  in  those  of  the  Bmall  wheel,  d,  forming  a  rack  and  wheel-work 
ooDtTiTuioe,  which  sdmits  of  drawing  the  piston  upwards  b;  taming  the  handle  of  d. 
When  thne  woond  op  the  eipaneion  of  the  spiral  spring  which  in  held  at  s  forces 
the  piston  downwards.  When  the  reservoir  is  not  GUed  with  oil,  the  piston  rests  on 
the  bottom  of  the  veseeti  and  when  oil  is  poured  into  the  oap  of  the  lamp,  it  Qows 
downwards  into  the  reserroir  and  on  to  the  upper  surface  of  the  piston :  if  this  is 
next    moTed    apwards  or  woond  np,  there  ia  a  Taennm   formed  below   it,  and  the 


Fio.  278. 


Fio.  I 


atanoBpfaerifl  air  pressing  upon  the  oil  forces  it  downwards  by  reason  of  the  flsiiliflity  of 
the  leather  packing  acting  as  a  Talre.  nntil  all  the  oil  is  below  the  piaton  and  the  latter 
foil;  wonnd  ap,  when  the  oil  forces  the  leather  packing  so  ti^^^tly  against  the  sides  of  the 
reaerroir  that  there  is  no  way  of  escape  bnt  by  the  Inbe  c,  which  communicates  with  the 
bnmer.  Ths  spring  is  very  accurately  adjusted,  and  its  eipansion  recrnlatal  to  Ihn  bulk  o( 
oil  which  is  oonsomed,  so  that  the  wick  is  properly  supplied.  After  the  lapse  of  some 
Ilotm  the  tamp  has  to  be  wonnd  up  again.  In  order  to  prevent  the  nil  passing  through 
the  tnbeo  ia  too  lajga  a  quantity  at  onoe  and  being  forced  oat  of  the  burner  as  a  jet,  there 


<44 


CHEMICAL  TECHNOLOGT. 


ii  brongbt  into  play's  oontriTUKe  which  ia  teehmcftUv  termed  the  moderstenr,  t/ODfttiat 
of  (Figs.  279  and  tSo)  h  perniMllj  beut  vrire,  o.  whioh  is  pluied  in  the  tube  c,  and  is  ul- 
dered  to  the  inner  tnbe  ot  the  lower  part  ol  the  bomer.  The  lower  and  movable  portiia 
ol  the  tube  c  ia,  when  the  pieton  is  mllj  wound  np,  so  placed  that  o  fits  and  dips  iato  c. 
while,  when  the  piston  moves  downwards,  c  ia  also  lowered,  and  not  partlj  plowed  bj  e. 
By  this  ammgement  the  Sow  of  the  oil  is  rendered  nniform  and  independent  of  the 
greater  force  of  eipaneion  exerted  bj  the  spiral  spring  when  the  lamp  has  been  fsllT 
wound  np.  To  eome  of  tbeae  lamps  an  arrangement  has  been  fitted,  consisting  of  a  dial 
and  hand,  exhibiting  externally  the  position  of  the  piston,  so  that  it  may  be  aei 
waen  the  lamp  again  reqairee  to  be  wonnd  up,  and  in  some  eases  an  alamm  haa  bon 
Aided  for  the  purpose  of  giving  audible  warning  when  the  operation  ia  required.  Vith 
good  colza  or  sperm  oil  an  eicellent  light  ia  obtainable,  while  the  machineij  is  not  mj 
liable  to  get  out  of  order. 
PtiiLieiuiiouuidPuiaii  3-  'nie  Quida  commonly  termed  paraffin  or  petnlenm  oUe,  tai 
ouLMn^i.  n^gff  known  as  kerosen,  photogeii,  pyrogen,  *c.,  are  always  bnmtin 

■action  lamps,  the  oil  reservoir  being  placed  either  below  or  by  the  side  of  the  wick. 
Uechanical  lamps,  anchas  the  moderatenrlamp,  for  instance,  camiot  be  used  f or  petroleam 
oila,  becaQBB  these  oils  do  not  lubricate  the  iealha 
F,o_  2g,^  of  the  piston.     As  the  mineral  oils  are  not  Tiacc«. 

the  oapillaiy  tubes  of  the  wick  can  more  readilT 
snck  ap  the  oil  from  the  reserToir,  so  that  by  tlw 
lowering  ol  the  level  of  the  fluid  a  loss  of  intensily 
in  the  light  is  hardly  perceptible.  Owing  to  tbe 
large  quantity  of  carbon  oootained  in  these  oik, 
a  Binokoleas  flame  is  produced  onljiy  a  pow«rfd 
current  of  air,  which  is  obtained  partly  by  the  gla« 
chimney  and  partly  by  the  adjuetment  of  the  wici, 
which  ahonld  project  very  slightly  above  the  ria 
of  the  bnmer;  while  in  the  paraffin  oil  lampi 
provided  with  Hat  wicks  the  object  ie  promoted  i^ 
the  brass  cap  put  over  the  flame  and  pro-rided  wi^ 
an  opening,  below  which  the  admiitore  of  aii  and 
vapours  of  the  oil  takes  place,  and  also  ■  atrotif 
current  of  air  called  forth  to  aid  the  combnitic*. 
In  reality  the  petroleum  and  paraffin  oil  lampa  in 
vaponr  lamps :  that  is  to  say,  the  vapours  of  tha> 
liquids  yield  the  luminous  flame,  not  the  gaie* 
resnlting  from  the  decomposition  of  the  oil.  u 
obtains  in  the  case  of  colza  oil  and  candlea.  li 
order  to  guard  ai^Hiust  the  possibility  of  is 
eii'Ioaion,  the  parsfliu  oil  lamps  are  all  so  eoB- 
trived  that  the  fluid  oontained  in  the  it»m«r 
does  not  become  heated,  and  for  tbia  purpooe  tbt 
cnrrent  of  air  which  euatains  the  oombnstioii  a 
i^a- -JH      IM-    &"  medo  to  cool  the  burner. 

^i      aP  Rl      f  Among  the  many  paraffin  oil  lamps  one  of  iht 

^       Wa         mff.'l  beat   ia  that   of  Ditmar,  at  Vienna.       This    Ui^ 

Fig.  28!,  consists  of  a  metal  oil  reservoir,  h,  wbick 
Hurrounda  the  wick  tube  and  ia  connected  with 
that  tnbe  by  means  of  a  horizontal  tabe,  thiaa^ 
which  the  oil  is  conveyed  to  the  wick,  a  is  a* 
aperture  for  filling  b  with  oil.  and  closed  by  a 
metnliic  screw-plng.  The  wick  ia  a  drcnlar  argafid 
burner  with  double  currents  ot  air  and  with  ^m* 
chimney,  c.  The  metallic  bearer  or  galleiy.  /,  el 
n  moderatenr  oil  lamps,  to  alide  upwards  and  downwudi 
the  bnight  ot  the  bent  narrowed  portion  of  the  glaM 
Bu  08  to  prodiice  the  bent  flame.  Tbin  narrowed  part  of  the  gloss  ahonld  atuid  aboW 
three-eighths  of  Fin  inch  above  the  wick,  as  indicated  by  the  dotted  lines  d  and  /, 
to  that  the  greater  part  ot  the  flame,  which  ahonld  be  abont  6  to  8  ccntima.  higk. 
is  above  the  narrowed  portion  of  the  glaaa.  If  the  glass  it  too  high  the  flanie  eitbs 
smokea  or  ia  ruddy,  and  when  too  low  the  Dame  ia  small  and  hardly  emits  any  hght. 
The  oil  reservoir  of  this  lamp  does  not  become  heated,  since  it  is  kept  cool  by  the  stnmg 
current  of  air  drawn  in  by  the  coni1>nstion.  In  one  of  the  recently  pnbliahed  nDinben  of 
the  "  Journal  of  the  Society  ot  Arts,"  the  petrolenm  lamps  of  Silbar  are  vetj  bighlv 


ARTIFICIAL  LIGHT.  645 

eommended.  ThoBe  lamps  yield  a  light  equal  to  that  of  twelve  to  forty  wax-candles, 
while  the  constmction  is  such  that  they  can  be  used  with  either  mineral  or  fatty 
oils  alternately,  and  without  the  necessity  of  trimming  the  wicks.  We  have  already 
allnded  to  the  so-called  benzoline  or  sponge  lamps  (see  p.  639). 

ni.  Oas, 

^*"H£iriS?ifot«?. *"^  ^^^  many  hundreds  of  years  it  has  been  known  that  fossil  coals 
yield  a  combustible  gas,  and  even  in  very  ancient  times  the  observation  has  been 
made  that  large  quantities  of  combustible  gases  were  sometimes  evolved  from  coal 
and  other  mineral  seams,  also  from  salt-mines,  &c.  The  soil  contains  in  many 
localities  such  a  quantity  of  gas  that  by  boring  a  hole  the  escaping  gas  may  be 
employed  for  the  purposes  of  illumination.  In  the  neighbourhood  of  Fredonia, 
State  of  New  York,  a  native  permanent  source  of  gas  exists,  which  having  been 
accidentally  discovered  by  the  pulling  down  of  a  mill  situated  on  the  banks  of  the 
river  Canadaway,  has  been,  by  boring  into  the  bituminous  limestone,  enlarged,  and  a 
gasholder  constructed.  The  native  gas  now  serves  for  the  purpose  of  illuminating 
the  locality.  The  quantity  of  gas  collected  in  twelve  hours  amounts  to  about 
800  cubic  feet,  and  consists,  according  to  Fouqu6's  researches,  of  a  mixture  of  marsh- 
gas  (CH4)  and  hydride  of  ethyl  (C^He).  In  the  Szlatina  salt-mine,  situated  in  the 
Marmaro  Comitate  (Hungary),  illuminating  gas  is  constantly  evolved  at  a  depth  of 
90  metres  below  bank  from  a  marly  clay  which  is  interspersed  between  the  layers  of 
rock-salt.  This  phenomenon  was  known  in  1770,  and  the  gas  is  now  collected  in  a 
gas-holder  and  used  for  lighting  up  the  mine.  A  small  quantity  of  gas  is  also 
evolved  in  the  Stassfurt  rock-salt  mines.  The  Rev.  Mr.  Imbert,  who  as  a 
missionary  has  travelled  through  China,  states  that  in  the  Province  of  Szu  Tchhouan, 
where  many  bore-holes  for  rock-salt  have  been  made  to  a  depth  of  about  1500  to 
1600  feet,  gas  is  permanently  emitted  and  conveyed  in  bamboo  tubes  to  places  where 
it  is  used  for  lighting  as  well  as  heating  purposes,  more  especially  the  heating  of 
salt-pans  in  which  the  brine  is  evaporated.  In  Central  Asia  and  near  the  Caspian 
Sea  there  are  at  several  localities  so-called  eternal  fires,  which  are  due  to  the 
constant  evolution  of  gas  from  the  soil.  Similar  phenomena  are  observed  at  Arbela 
in  Central  Asia,  at  Chitta-Gong  in  Bengal,  and  elsewhere,  while  now  and  then  large 
volumes  of  gas  emitted  in  the  coal-pits  and  conveyed  to  bank  by  means  of  iron  pipes 
are  suffered  to  bum  for  several  days. 

As  regards  the  artificial  production  of  gas  from  coals,  Clayton  and  Hales,  1727  to 
1739,  made  the  first  observations  on  this  subject;  while  the  Bishop  of  Uandaff, 
1767,  exhibited  how  the  gas  evolved  from  coal  might  be  conveyed  in  tubes.  Dr. 
Pickel,  Professor  of  Chemistxy  at  Wiirzborg,  lighted  his  laboratory,  1786,  with  the 
gas  obtained  by  the  dry  distillation  of  bones.  At  about  the  same  period  Earl  Dun- 
donald  made  experiments  on  gas-lighting  at  Culross  Abbey;  but  it  should  be 
observed  as  regards  these  experiments  tliat  they  were  made  more  with  the  view  to 
obtain  tar,  and  the  gas  evolved  by  the  distillation  of  the  coals  was  considered  a 
cariosity.  The  real  inventor  of  practical  gas-lighting  is  William  Murdoch,  who  in 
1792  lit  his  workshops  at  Redruth.  Cornwall,  with  gas  obtained  from  coals.  His 
operations  remained  unknown  abroad  for  some  ten  years,  and  hence  the  French 
consider  Lebon  as  the  inventor  of  gas-lighting,  since  he  lit  (1801)  his  house  and 
garden  with  gas  obtained  from  wood.  The  first  more  extensive  gas-work  was 
•estabUshed  in  1802  by  Murdoch,  at  the  Soho  Foundry,  near  Birmingham,  the 
property  of  the  celebrated  Boulton  and  Watt;   and  in  1804  a  spinning-mill  at 


64»  CHEMICAL   TECHNOLOGY. 

Manchester  was  lighted  with  gas.  From  that  period  gas-lighting  became  more  loi 
more  generally  adopted  in  factories  and  workshops,  hut  not  before  the  3'ear  18x2  did 
this  mode  of  lighting  become  introduced  into  dwelling-houses  and  streets,  a  few  of 
which  in  London  were  lit  with  gas  in  this  3'ear :  wliile  in  Paris  gas  was  fii^ 
introducad'  in  1820.  From  that  year  gas-lighting  may  be  said  to  have  become  of 
general  importance  in  Europe,  and  now  there  is  hardly  any  important  place  on  the 
Continent  where  it  is  not  in  use,  while  as  regards  tlie  United  Kingdom  in  no  portioQ 
is  gas-making  and  lighting  so  general  over  town  and  country  as  in  Seotlind. 
Among  the  more  recent  improvements  in  tliis  direction  are  Pettenkofer^s  wood  and 
peat  gas  manu&cture,  and  Hirzel's  gas  from  petroleum  residnes.  The  principle  of 
gas -lighting  is,  as  has  been  already  stated,  the  same  as  that  of  candles  and  oil  lamps, 
but  the  raw  materials  in  use  for  gas-making  are  not  by  themselves  suited  finr 
illumination,  and  it  is  therein  that  the  great  improvement  is  to  be  found. 

^oL^icMiig!^  These  are  coals,  wood,  resin,  fatty  substances,  oil,  petroleum,  and 
water,  and  according  to  the  material  employed  the  gas  obtained  is  designated  as  coaL 
wood,  resin,  oil,  petroleum,  and  water  gas. 

coaioas.*  I.  Coals  consist  of  carbon,  hydrogen,  oxygen,  and  small  quantities  of 
nitrogen,  mineral  matter,  or  ash,  and  contain,  further,  a  larger  or  smaller  quanti^ 
of  iron  pyrites.  Technically  we  distinguish  in  England  gas  coals,  steam  coals,  aad 
household  coals.  As  regards  the  first — the  so-called  cannel  coals  usually  excepted— 
tliey  belong  to  the  class  termed  caking  coal,  for  the  reason  that  this  kind  of  coal 
when  submitted  to  heat  softens  and  becomes  agglutinated.  According  to  H.  Fleck, 
the  best  kinds  of  gas-coals  contain  upon  100  parts  of  carbon  2  parts  of  fixed 
igebundenen)  and  4  parts  of  disposable  [disponiblen)  hydrogen.  Among  the  best  gas- 
coals  are  the  so-called  cannel  coals,  the  term  cannel  being  a  corruption  of  candle,  is 
in  former  times  pieces  of  these  coals  were  in  some  pai-ts  of  Scotland  and  Lancashire 
used  by  the  poorer  people  to  bum  instead  of  candles.  Cannel  coal  is  chiefly  found 
in  Scotland  and  Lancashire,  although  tliere  exist  seams  of  cannel  coal  in  some  of  the 
pits  of  Durham  and  Northumberland.  The  Boghead  coal,  or  Torbane  Hill  mineiaL 
is  not  properly  speaking  a  cannel  coal,  and  will — excepting  as  specimens  in 
museums — soon  have  disappeared  altogether ;  for  gas  manufacture  it  has  already 
become  quite  obsolete.  Li  France  and  Belgium — in  addition  to  large  quantities  of 
imported  English  gas-coals  and  Scotch  cannel — the  coals  of  Mons  and  Commentzy 
are  used,  while  in  Germany  the  Saxony,  Silesian,  Westphalian.  and  Bhenish  coal- 
pits yield  excellent  gas-coals.  Gas-coal  should  be  as  much  as  possible  free  from 
sulphur,  and  should  further  contain  only  a  small  quantity  of  ash  ;  but  in  practice 
these  points  are  less  attended  to,  because  the  defects  of  one  kind  of  coal  are  by  good 
gas-makers  counterbalanced  by  the  better  properties  of  other  kinds. 

I  cwt.  (=50  kilos.)  of  Geiman  coals  yields  on  an  average  14  cubic  metres,  or 
500  English  cubic  feet  of  gas,  and  35  kilos,  or  150  parts  by  bulk  of  coke.  Is 
England  it  is  usual  to  compute  the  quantity  of  gas  yielded  per  ton  of  eoals  ;  on 

*  I  cubic  metre  =  35*3 1  English  cubic  feet. 

40*22  Bavarian    „      „ 
32-34  Rhenish      „      „ 
3 1  65  Vienna        „      „ 
1000  cubic  feet  Engli^^^  28*31  eubio  metres. 

1 138  Bavarian  cubic  feet. 
915  Rhenish       „      „ 
896  Vienna        ,»      „  • 


ARTIFICIAL  LIGHT. 


647 


average  the  Newcastle  ooals  yield  about  9000  to  9500  cubic  feet  of  gas  per  ton  of 
€oalB;  cannel  coals  vary  in  yield  from  10,000  to  i2»ooo;  as  regards  the  Boghead  variety 
it  gave  about  15,000  cubic  feet  of  gas,  but  much  depends  upon  the  mode  of  distilla- 
tion and  the  length  of  time  this  operation  is  continued.  It  should  be  borne  in  mind 
that  the  best  illuminating  gas  is  given  off  during  the  first  hours  of  the  distillatory 
process ;  the  latter  products,  though  adding  greatly  to  the  bulk  of  the  mixture,  contain 
much  of  the  comparatively  useless  gases  and  diluents.  The  mode  of  decomposition 
of  the  gas-coals  may  be  elucidated  by  the  following  diagram,  100  parts  of  coal  con- 
sisting of : — 

Carbon       ...  7^*^* 

^y*;°8f fl  fCoke     70-75 

ftHUi  «••         •••         •••         •••         ••«        ^  KJ ^ 


•  •• 

^1 


30— «5 


lOO'O  lOO'O 

vndMti  of  Kb«  Diauiuiioii.      These  may  be  classified  into  four  chief  products : — 

f  Carbon 9^^"^^$ 

5 


I  v^ar oou  •••     •••     •••     •••     «•• 

i.  Coke.  ]  Sulphuret  of  iron  (FeySg)  ... ) 

\  ^XDU  •••         ••*         •••  •••         ...J 


100 


II.  Ammoniacal 
liquor. 


Mainconstituents.|S*^^^?f***,^^*°^"**^P*'  f^f\^^^+^^* 
.uuuu  vvixouK  c  ».  ^  guipiji^Q  ^f  ammonium,  (NH4)»S 

'  Chloride  of  ammonium,  NH4CI 
Cyanide  of  ammonium,   NH4CN 
Sulphocyanide  of  am- 
monium, 


in.  Tar. 


Hydro- 
carbons. * 


Fluid.  - 


SoUd.   . 


Acids. 


'Benzol, 

Toluol, 

Xylol, 

Cumol, 

Cymol, 

Propyl, 
tButyl, 

Naphthaline, 

Acetylnaphthaline, 

Fluoren, 

Anthracen, 

Methylanthracen, 

Reten, 

Chrysen, 

Pyren, 

Carbolic, 

Cresylic  (cresol), 

Phlorylic  (phlorol), 

Rosolic, 

Oxyphenic, 

Creosote,  consisting  of 
three  homologous 
substances, 


NH4CNS 

CgHg 
C7H8 
CsHjo 

CgHxa 

CxoHx4 

C3H7 

C.0H8 

CiaHjo 

I?) 

CisHxa 

CieHxa 

CisHia 

CxfiHxo 

CeHeO 

CyHgO 

•CsHxoO 

CaoHxeOj 
C6H503 

(CyHsOa 

CsHxo 
.C9HI2 


-v        Can 
J2  )   o* 

^2}  till 


OoillUBAttO<ltf 

oxnUatda 
add  and  Midi 

homolofnni 
Oienwltli. 


*  Has  become  important  as  a  source  of  alizaxine,  in  consequence  of  the  dlseovAry  ci 
Ora^be  aad  liebermann,  1869. 


648 


CHEMICAL  TECHNOLOGY. 


111.  Tar. 


/PTridine,  C8H5N 

Aniline,     CeH^N 

Bases.  jPicoline,   CeHsN 

I  Lntidine,  CyHnN 

ICoUidine,  CsHnN 


Leucoline,  C9H7N  Coridine.  C^„N 

Iridoline.    CxoHgN  Rnbidine,  CxxHj^N 

CrypUdine,  C„HxxN  Viridine,  Ci^Hr^N 
Acridine,      Ci  "  "' 


'laHgN 


(Anthracen 
Empyreumatic  jreains 
Carbon. 


IV.  THiiTninatJng 
gas. 


Illaminating 
or  light-yield- 
ing constitu- 
ents. 


Gases. 


Vapours. 


/Acetylen, 

jElayl, 

iTritjrl, 

iDitetryl, 

^Benzol, 

Styrolen, 

Naphthaline, 


C4HS 

CsHs 
CxoHa 


Acetyl  naphthaline,    CxaHxo 


C3H7 


p.  Diluents*  or  Ught- 
bearers. 


y.  Impurities. 


Fluoren, 

Propyl, 
)Butyl, 
J  Hydrogen, 
I  Methylhydrogen, 
^Carbonic  oxiae, 

Carbonic  add. 

Ammonia, 

Cyanogen, 

Sulphocyanogen, 

Sulphuretted  hydrogen. 

Sulphide  of  carbon. 

Sulphuretted  hydrocarbons 

Nitrogen, 


CH4 

CO 

CO, 

KH. 

CN 

CN8 


SsC 

N 


lUnafiMtanofCoaiaaa.  Whether  coals,  resin,  wood,  peat,  or  other  materials 
employed,  the  manufacture  of  gas  involves  the  three  following  chief  operstioos. 
viz. : — a.  The  obtaining  of  crude  gas  by  the  process  of  distillation,  h.  The  aepaim- 
tion  of  tarry  and  other  condensable  matters,  e.  The  purifying  of  the  cnide  gas  so 
as  to  render  it  fit  for  use. 

a.  The  distillatory  process  or  making  of  crude  gas  is  effected  by  the  applicatioa  of 
a  high  temperature — above  red-heat — and  exclusion  of  air,  and  is  carried  on  in 
vessels  which  are  technically  termed  gas  retorts  or  simply  retorts. 

Betortc  The  retorts  were  in  the  earlier  days  of  gas-lighting  always  made  of  east- 
iron  and  of  cylindrical  shape,  but  for  the  last  twenty  years  fire-day  retorts  haw 
become  very  generally  used,  though  they  have  not  altogether  superseded  the  nae  of 
cast-iron  retorts,  which  were  found  inconvenient  for  only  two  reasons,  viz^  lor 
wearing  out  too  rapidly,  and  for  not  admitting  of  being  raised  to  the  veiy  la^ 
orange-heat,  which  has  been  adopted  for  the  distillation  of  some  kinds  of  eanad 
coals.  As  regards  the  size  of  the  retorts,  this  varies  according  to  the  requiremeBts 
of  the  works,  but  generally  the  retorts  are  sufiicientiy  large  to  hold  100  kilos,  of  eoal, 
leaving  from  0*5  to  0*6  of  the  interior  space  unfilled  for  the  purpose  of  afibrdiag 
room  for  the  expansion  of  the  coals.  The  diameter  of  such  a  retort  is  abofot 
54  centimetres  in  the  larger  axis,  and  43  to  45  centimetres  in  the  smaller  axis,  by  a 
length  of  2*5  to  3  metres.  One  end  of  the  retort  is  usually  dosed,  although  in  acme 
Isxge  gas-works,  as  at  Edinburgh,  Glasgow,  Paisley,  fire-clay  retorts  of  very  greil 
length  and  open  at  both  ends  are  in  use,  being  fired  by  two  furnaces  situated  at  ead 
end.    In  some  of  the  London  gas-works,  retorts  are  in  use  not  made  of  fire-day,  m 


ARTIFICIAL   LIGHT.  649 

one  or  mote  pieces,  bat  bnilt  up  with  fire-bricks  or  slabs  of  fire-claf ,  of  a  peculiar 
Bhape.  uid  made  for  the  purpose  in  Wales ;  these  slabs  ore  put  together  with  a 
cement  of  pure  quartz  sand  and  about  i  per  cent  of  lime,  or  a  clay  which  becomes 
pastj  and  adhesive  in  very  great  heat.  Retorts  of  this  kind  are  cheaper  and  aland 
fire  years'  wear.  Retorts  made  of  heavy  boiler-plate  rivetted  together,  as  well  as 
forged  iron  retorts,  welded  together  like  the  iron  mercniy  bottles,  are  also  in  ose,  bat 
of  coorse  are,  in  the  foraaces,  projected  from  tlie  direct  action  of  the  fire  by  properly 
bnilt  arches  and  coverings  of  fire-bricks. 

""S"^!!™?  "*  The  retorts  are  always  fitted  with  a  separate  mouth-piece,  to  which 
daring  the  process  of  distillatioii  the  lid  is  fastened  ;  this  mouth-piece  is  always 
made  of  cast-iron,  even  in  the  fire-clay  retorts,  to  which  it  is  fitted  by  a  flange  on  the 
retort,  the  flange  of  fire-clay  being  provided  with  six  to  eight  holes  for  putting  in  the 
screw  bolts  for  the  purpose  of  making  a  good  Joint.  In  order  to  get  a  gas-tight  Joint 
a  mixture  of  iron  filings  and  gypaum  is  used,  which  is  mode  into  a  paste  witli  an 
aqueous  solution  of  sal-ammoniac.    The  month-piece  is  fitted  with  a  short  tube  for 

Fio.  18*>  Fto.  3S3.  Fia.  184.  Fia.  185. 


^m 


the  pnrpoae  of  giving  Tent  to  the  gases  and  vapours  evolved  during  the  distillation. 
As  the  mouth-piece  is  placed  outside  the  fumsrce.  it  ie  generally  of  longer  duration 
than  the  retorts,  and  these  are  moulded  to  stiit  the  month-piece. 

fig.  383  exhibits  the  firont  view  of  a  mouth-piece  of  a  Q-shaped  retort.  Fig.  283 
exhibits  a  section,  b  is  the  opening  at  the  retort  end ;  n  is  the  lid  for  closing 
the  retort  during  the  distillation.  At  11,  Fig.  282,  are  seen  the  cB«t-iron  eyes 
intended  to  snpport  the  malleable  iron  bars  for  the  support  of  the  lid.  00.  Fig.  283, 
is  the  flange  wherewith  the  mouth-piece  is  fitted  to  Hie  retort  n  is  the  short  piece 
of  tube.  Fig.  284  is  a  front  view  of  the  cast-iron  lid  of  the  retort ;  and  Fig.  385,  a 
view  of  the  side  of  the  lid  tuned  towards  the  retort  As  will  be  observed,  the  lid  fits 
accnrately  into  ih»  opening  of  the  retort.  The  meUiod  of  closing  or  rather  tightly 
festening  the  lids  of  gas  retorts  is  exhibited  in  Fig.  286,  being  a  side  view  of 
the  month-piece,  mm  are  the  malleable  iron  bars  on  which  the  lid  is  supported  by 
means  of  the  projections,  nn.  Pig.  384.  Through  the  bars  mm  are  cut  openings, 
through  which  the  cross-barp  is  put,  and  in  its  centre  a  hole  with  screw  thread,  into 
vrhich  is  made  to  fit  a  screw-bar  and  handle,  a.  By  turning  the  screw,  the  lid  is 
forced  tightly  against  the  rim  of  the  month-piece ;  but  in  order  to  secure  a  gas-tight 
joint,  a  lute  is  used  consistiiig  of  some  clay  or  spent  purifier  lime  and  clay  mixed. 

Another  mode  of  fastening  the  lid  is  exhibited  in  Fig.  2S7,  being  also  a  side  view. 
The  bars  fnfli  are  in  this  instance  bent  at  one  end  where  the  cross-bar  a  is 
to  be  placed.    To  that  cross-bar  is  fitted  at  tight  angles  another  bar.  h,  provided 


650  CHEMICAL  TECHNOLOGY. 

at  nne  end  with  k  heavy  iron  ball,  and  at  the  other  wilh  a  knee-bend,  90  that  bj 
pnlling  the  ball  downwards  the  lid,  n,  is  tightly  fastened. 

BMai  FDruBH.  The  retorts  are  placed  in  a  furnace  in  the  manner  exhibited  in 
Fig.  288,  that  ie  to  aay  they  are  placed  horizontally  and  aupported  by  brickwork — 
technically  benches.  The  month-piece  projects  from  the  fnmace.  each  of  which  may 
contain  two  to  three,  five  to  seven,  or  even  twelve  to  sixteen  retorts,  as  in  large  gas- 
works, in  which  case  the  lower  rows  are  of  fire-clay,  the  higher  of  iron. 


Fin.  186.  Fio.  287. 


The  retorts  are  in  aome  works  charged  by  means  of  a  larga 
scoop,  which  being  filled  witli  the  quantity  of  coals  the  retort  is  intended  to  be 
charged  with,  is  carried  by  four  men  and  then  lifted  into  the  retort,  and  being  over- 
turned fills  the  retort,  after  which  the  scoop  is  withdrawn  and  the  lid  of  the  retort 
fastened  on.  But  in  many  gas-worlis  the  coals  are  thrown  into  the  retorts  with  shovels. 
As  soon  as  the  retorts,  which  preriouslj  to  being  filled  are  always  heated  to  red- 
heat  or  higher,  are  charged,  and  the  lida  closed,  the  evolution  of  gas  is  very  strong, 
and  continues  so  for  some  time,  until  after  some  fonr  to  five  hoars  the  distillation  is 
finished,  or  at  least  the  gaa  then  given  off  is  not  worth  collecting.  In  Scotland  the 
distillation  is  not  continned  so  long,  three  or  three  and  a  half  hours  being  deemed. 
with  good  firing,  quite  sufficient,  cannel  coals  giving  off  their  gas  more  freely  than 
caking  coals.  The  Uds  are  now  loosened  and  the  gas  at  tlie  mouth  of  the  retorts 
kindled  in  order  to  prevent  explosion  by  its  becoming,  as  wonld  be  the  case  if 
the  lids  were  at  once  removed,  mixed  with  air.  The  red-hot  coke  left  in  the  retort  is 
raked  out  and  at  once  need  for  firing  the  foniaces.  or  pnt  into  iron  wheelbarrows 
and  wheeled  out  of  the  retort-house  into  the  yard,  there  to  be  quenched  with  water 
and  kept  for  sale.  Cannel  coala  do  not  as  a  rule  yield  a  good  coke,  but  only  broken-np 
black  shaly  breeze,  which,  however,  along  with  some  dead  oil,  is  used  in  the  Sooteh 
gas-works  for  heating  the  reiorle.  On  an  average  one-third  of  the  coke  obtained  is 
required  for  firing  the  retorts. 

riwniiruiuaiitiii.  We  understand  by  the  hydraulic  main  a  vessel  with  which  are 
connected  the  ascending  tuhns  leading  from  the  retorts.  As  a  rule  the  hydiaulie 
main  is  placed  on  the  top  of  the  furnace  in  which  the  retorts  aie  ignited.  The 
diameter  of  the  ascending  tubes  varies  of  course  witli  the  size  of  the  retorts,  but  is  on 
an  average  I2  to  18  centimetres.  Tlie  liydrauUo  main,  of  which  b,  Fig.  28S.  is 
a  section  at  riglit  angles  to  Uie  longitudinal  axis,  is  a  wide  pipe  of  cast-iron  or 
of  boiler-plates  rivetted  togcUier.  and  liaving  an  average  diameter  of  30  to  60 
centime.  It  ia  eitlier  cylindrical  or  Q-shaped,  and  extends  over  the  entire  length  of 
the  row  of  furnaces.    The  hydraulic  main  is  intended  to  act  as  a  receiver  for  all  the 


ARTIFICIAL  LIOHT. 


652 


CHEMICAL  TECHNOLOGY. 


volatile  products  of  the  distillation,  while  at  the  same  time  it  afibrda  to  every  ra^ 
retort  a  hydraulic  valve,  shutting  it  off  from  the  other  retorts,  and  prenotbg 
effectually  any  gas  finding  its  way  back  to  the  retorts  when  opened  at  the  moGlk. 
The  mode  of  connection  between  the  retorts  and  the  hydraulic  main  is  shoim  m 
Fig.  289.  A  is  the  ascending  tube ;  b  the  saddle-pipe ;  c  the  dip-tabe  earned  down- 
wards into  the  hydraulic  main ;  d  is  the  main ;  and  m  the  liquid— viz.  tar.  or  it  «b 
first  starting  of  a  gas- work,  water.  Fig.  290  exhibits  a  somewhat  different  mode  of 
connecting  the  retorts  and  hydraulic  main.  There  is  fitted  to  this  main  a  s^phoi 
tube  for  running  off  the  excess  of  tar  t»  the  tar  dstem,  and  on  the  top  (tf  the  osiB 
is,  as  exhibited  in  Fig.  288,  a  wide  iron  tube  for  canying  off  the  gas  to  dtf 
condensing  apparatus. 


Fia.  289. 


Fio.  290. 


^'^^iSiSSSS!"*"*^  *•  The  volatile  products  of  the  distillation  which  are  not  am- 
densed  in  the  hydraulic  main  are  carried  off  with  the  permanent  gases.  The  resdff 
should  observe  that  a  comparatively  very  high  temperature  prevails  in  the  asoendiiilg 
tubes  and  hydraulic  main.  These  volatile  products  are  gas,  steam  vapoois  of  tir, 
the  steam  containing  in  solution  and  suspension  various  ammoniacal  compoaodi- 
Before  the  gas  can  be  purified  it  has  to  be  cooled  and  deprived  of  a  number  of  sab- 
stances  which  are  in  fact  impurities,  inasmuch  as  they  would  impede  the  flow  of  p^ 
through  the  pipes  if  they  were  not  got  rid  of.  The  condensing  process  may  be  euof^ 
on  in  various  ways,  but  on  the  large  scale  the  most  efficient  is  the  Teiy  sivp^ 
expedient  of  causing  the  gas  to  pass  through  a  series  of  cast-iron  pipes,  as  eihiUitl 
in  Fig.  291,  in  vertical  section ;  also  in  d.  Fig.  288.  These  tubes,  placed  in  the  open 
air — ^in  warm  climates  or  in  hot  summer  weather  arrangements  being  made  to  cool 
the  pipes  externally  by  a  stream  of  water — ^are  connected  with  each  other  it 
the  top,  and  rest  in  a  large  cast-iron  tank,  j>,  which  by  means  of  partitions  if 
divided  into  compartments  not  communicating  with  each  other,  being  hjdxaiilioi]^ 


ABTIPICIJL   LIGHT. 


653 


locked.  E&eh  oompartment  is  fitted  with  ui  inlet,  tn,  utd  an  outlet,  ».  In  tbia  tank 
the  gas-water  or  unmoniacal  liquor  and  tar  ore  collected,  whUe  the  height  these 
fiuids  should  oocap7  in  tiie  tank  is  regulated  bj  s  tnbe,  d.ta  ea  seen  in  Fig.  283,  at  H, 
by  a  ayphon  tube.  The  condensed  liquids  flow  to  the  brickwork  tank,  o,  and  thence 
to  the  tar  ciatem.  The  inlet  tnbes  dip  to  some  depth  into  the  fluid  so  as  to  force  the 
gaa  to  pass  through  it.  The  size,  nnmber,  and  height  of  tliese  condensing  tulea 
depends  on  the  quantitj  of  gaa  which  has  to  be  cooled  in  a  giyen  time  ;  OD  an 
average  50  to  90  Bqnare  feet  of  surface  of  tubes  is  allowed  for  1000  cubic  feet  of  gas 
to  be  cooled  per  bonr. 

Tbasaniitar.  In  mau^  of  the  larger  gaa-works  the  gas,  after  it  has  issned  from  the 
tube  condenser,  ie  passed  tbrongh  an  qtparatns  tanned  tlie  scmbber,  for  the  purpose 
of  more  completel7  depriving  it  of  tarrj  matter  before  sending  it  on  to  the  pniifiers. 


Sa 


Tfe3nt3f1HT 


ilL 


^ 


mni  also  for  getting  rid  of  the  ammonia  and  enlphnr  compounds.  The  rationale  of 
the  mode  of  action  of  the  scrubber  is  similar  to  that  often  employed  on  a  minnt4 
scale  in  practical  chemistrj.  when  a  gas  or  vapour  is  passed  through  a  glass  tnbe 
filled  with  pomice-Btone,  so  that  in  a  limited  apace  a  great  surfiue  is  provided. 
The  scrubber  consiata  of  cylindrical  oast  or  malleable  iron  chambers  of  sufficient 
Hze,  and  filled  with  Inmps  of  coke  or  fire-brick,  which  are  constantly  moistened  with 
Tatar.  Fig.  29a  exhibits  a  sectional  view  of  a  scmbber,  also  seen  in  Fig.  388  at  00. 
The  cylinder  has  a  diameter  of  i|  to  i|  metres,  b;  a  hei^t  of  3  to  4  metres ; 
the  vessel  is  filled  with  coke,  which  is  kept  moist  bj  means  of  water  introdnoed  hy 
the  rotating  perforated  tnbe,  h.  The  inlet  of  the  gas  is  at  i ;  it  proeseda  upwards 
throogh  the  column  of  coke  and  on  reaching  the  top  pasaes  oS  downwards  tbrongh 
n>  to  the  second  scmbber.  At  the  lowest  bend  of  the  exit  or  outlet  tubes  a 
syphon  pipe  is  fitted  for  the  purpose  of  draining  off  water  and  twry  matters  which 


654  CHEMICAL   TECHSOLOGY. 

collect  in  the  reservoir,  m.  The  use  of  tlie  scrubber — tlie  gas  hardly  requires  107 
addiUonal  presBore  to  be  carried  tkrongh  it — effects  s  saving  of  the  pafifring 
materials,  lime,  &o.,  bj  causing  the  gas  to  be  thoroughly  washed  aod  cooled: 
in  other  terms — mechanically  poritied. 

■iimiHr.  This  apparatus,  also  termed  the  aspimtor.  is  placed  between  tbe 
hydraulic  main,  being  connected  with  the  gas  leadio-j  pipe,  or  bHween  ifae 
condenaera  and  the  purjhcrs.     It  is  intended 

to  suck  or  pump  the  paa  from  the  retorts  so  as  F'"-  >9>- 

to  diminish  their  internal  pressure.  This 
pressure  amounts  in  some  cases  to  nearly 
15  lbs.  to  the  square  inch,  luid  it  was  found 
that  under  that  pressure  a  great  deal  of  gas 
was  lost  tlirough  the  pores  of  the  fire-day 
retorts,  especially  when  new,  being  then  not 
coated  witli  a  film  pf  graphite  wliich  after- 
wards acta  OS  an  impermeable  layer.  The  aspi- 
rators also  serve  to  remove  the  gaseous 
mixture  as  rapidly  as  possible  from  the  red- 
hot  tetortfi  and  coke,  and  tlius  prevent  the 
partial  decomposition  of  valuable  illuminating 
constituents  of  tlie  gas,  by  which  decompo- 
sition, moreover,  the  retorts,  iron  as  well  as  ^ 
fire-clay,  become  lined  with  a  graphite-like  I  /  ^lir^-^^^^iEi^ 
coke,  wliich  impairs  the  conducting  power  for 
heat,  as  well  as  decreases  tlie  internal  cubic  capacity  of  tlie  retorts.  The  intro- 
duction of  exhausters  dates  from  1839,  when  Grafton  made  and  tried  the  tiisL  Hii 
airangement  was — a  box  filled  with  water  for  about  three -fourths  of  its  capaciiv. 
whUe  in  the  box.  on  an  axis  projecting  outside,  tlirough  gas-  and  water-tight  staffing 
boxes,  four  circularly-bent  scoops  were  fixed,  so  that  on  a  rotating  motion  being 
imparted  to  the  axis,  and  thereby  Ui  the  scoops,  a  partial  vacuum  was  formed,  and  the 
gas  inspired  into  the  apparatus,  and  thence  carried  ofi  by  side  tubes.  This  appaiatu 
hits  never  been  of  any  practical  use  in  gas-works.  Next,  the  so-cnlled  bell 
exhauster  was  used;  the  principle  of  this  apparatus — dmilar  in  construction  to 
tliat  in  use  in  paper  mUlit — being  in  reality  nothing  else  than  a  hydranlic  air- 
pump,  consisting  of  two  or  three  large  bell-shaped  iron  vessels,  connected  together 
and  placed  in  tanks  filled  with  water,  and  moved  slowly  upwards  and  downwards  by 
mechanical  power.  Under  each  of  these  bell-shuped  vessels  an  inlet  and  outlet 
pipe  is  fitted  provided  with  valves.  There  have  been  a  great  many  varionilj 
constructed  exhausters  proposed ;  some  of  these,  Anderson's  for  instance,  art 
similar  to  the  cylinder  blowing  machines  in  use  with  blast  furnaces;  othen 
again  ore  similar  in  construction  to  the  double-acting  air-pumps  of  low-preasnr* 
marine  steam-engines;  some  to  centrifugal  pumps.  With  the  fire-clay  retorts, 
now  very  generally  adopted  in  gas-works,  the  use  of  exhausters  is  almoa  a 
necessity,  and  the  apparatus  is  always  fitted  up  with  new  gas-works.  Of  conise  IB 
accessory  of  the  exhauster  is  a  small  steam-engine  and  boiler. 

Pujfjini  ou.  c.  The  crude  gas  having  been  passed  tlirough  the  appantos  just 
described,  and, mechanically  purified,  is  sent  on.  as  it  is  technically  termed,  to  tb« 
purifiers,  in  order  to  eliminate  by  chemical  meaus  snch  substances  as  snlphorelud 


ARTIFICIAL  LIGHT,  655 

hydrogen,  carbonic  acid,  and  varions  ammoniacal  componnds,  carbonate  of  ammonia, 
salphuret  of  ammonium,  cyanide  of  ammonium,  &c. :  and  also  some  of  the  compound 
ammonias,  as,  for  instance,  aniline,  iridoline.  &c.  At  the  outset  of  the  gas-li<^hting 
industry,  quick-lime  was  the  ouly  material  employed  for  purifying  pui-poses,  this  sub- 
stance being  at  first  employed  in  tlie  form  of  a  tliick  milk  of  lime,  the  purifier  being 
60  constructed  that  the  crude  gas  was  brought  into  intimate  contact  witli  tlie  fluid, 
which,  in  order  to  prevent  the  lime  from  forming  a  sediment,  was  kept  in  constant 
motion  by  a  stirring  apparatus ;  while  the  purifier,  made  of  cast-iron,  was  provided 
witli  inlet  and  outlet  pipes  for  the  gas,  a  pressure  gauge,  and  the  necessary  syphon 
pipes  and  valves  for  letting  out  tlie  waste  milk  of  lime  and  re-filling  the  vessel. 
Variously  arranged  wet  lime  purifiers  have  been  devised,  and  among  them  some 
which  act  also  as  exhausters;  but  notwithstanding  the  very  satisfactory  results 
obtained  by  the  use  of  wet  lime  purifiers,  tlie  gas  being  very  effectually  freed  from 
carbonic  acid,  sulphuretted  hydrogen,  and  ammonia,  there  is  the  defect — ^first,  of 
the  back  pressure  on  the  retorts  and  otlier  apparatus;  and  secondly,  a  difficulty 
in  the  mode  of  so  disposing  of  the  very  foetid  waste  lime  liquor  as  not  to  create  a 
nuisance;  hence  it  iB  that  the  wet  lime  purifiers  have  been  almost  entirely  super- 
seded by  the  so-called  dry  lime  purifiers.  These  are  large  square  iron  boxes  fitted 
inside  with  movable  trays  resting  on  ledges  and  provided  with  sieve-like  perforations, 
and  either  made  of  iron  gratings  or  iron  plates,  or  even  wooden  boards,  on  which  the 
previously  slaked  and  somewhat  moist  lime  is  carefully  placed  in  layers  of  uniform 
thickness  to  a  height  of  20  centimetres,  there  being  in  every  purifier  box  from  five  to 
eight  frames.  The  purifier  is  usually  divided  into  two  compartments  by  a  partition, 
so  that  the  gas  which  enters  from  the  bottom  of  one  compartment  has  to  ascend 
through  the  layers  of  lime  of  tlie  inlet  compartment,  and  to  descend  through  those  of 
the  outlet  compartment.  The  gas  passes  through  the  layers  of  dry  lime  readily 
enough  and  almost  without  producing  any  back  pressure,  and  there  is  no  necessity 
to  render  the  lime  more  porous  by  the  addition  to  it  of  either  moss,  sawdust,  chopped 
straw,  &c.  As  to  the  quantity  of  lime  required  for  the  purpose  of  purifying  a  cer- 
tain volume  of  gas,  it  is  stated  that  for  1000  cubic  feet  of  crude  gas  from 
Newcastle  coals,  2'6  kilos,  of  unslaked  quick-lime  are  required.  With  careful 
selection  of  the  gas-coals  to  be  carbonised,  and  a  well-conducted  distillation  and 
mechanical  purification  of  the  crude  gas,  the  lime  purifying  process,  especially 
if  wet  and  dry  purifiers  both  are  used,  as  is  the  case  in  some  of  the  largest  gas- 
works in  Scotland,  yields  excellent  results,  and  there  is  no  need  for  any  other 
purifying  materials ;  while  the  spent  lime,  as  is  the  case  in  Scotland,  is  found  useful  as 
a  manure,  as  well  as  for  building  purposes  with  some  fresh  lime  and  sand.  It  is,  how- 
ever, true  that  in  many  places  the  gas  thus  made  is  too  impure  for  use  in  dwelling 
houses,  and  a  more  complete  elimination  of  the  ammonia  and  some  of  the  sulphur 
compounds  is  found  to  be  absolutely  necessary.  Since  1840  an  immense  number  of 
gas-purifying  materials  and  contrivances  have  been  brought  forward  and  tried  but 
again  abandoned.  It  is  entirely  beyond  the  scope  of  this  work  to  enter  into  more 
than  a  very  slight  sketch  of  the  various  gas  purifying  processes ;  but  we  give  the 
following  particulars  on  this  subject. 

It  cannot  create  any  surprise  when  we  find  that  adds  and  metallic  salts  should  have 
been  called  in  to  aid  the  absorbing  of  the  ammonia  and  sulphuretted  hydrogen  from  coal- 
gas.  ProtoBulphate  of  iron  has  been  here  and  there  resorted  to,  of  course  in  aqueous 
solution.  Mallet  (1840)  commenoed  the  use  of  the  residue  of  the  chlorine  manufacture, 
crude  chloride  of  manganese,  for  the  same  purpose.    Far  more  important  is  the  method 


656  CHEMICAL  TECHNOLOGT, 

first  suggested  in  1847  ^.T  ^'  Laming,  and  now  generally  known  as  the  Jmnmg  ]nri- 
fying  process.  As  originally  patented,  the  mixture  was  composed  of  protocliloride  of  iioa 
with  qoiok-lime  or  chalk,  and  in  order  to  keep  the  mass  poronB  sawdost  was  adM. 
Instead  of  protochloride  of  iron,  sulphate  of  iron  is  now  more  generally  nsed,  and  mixed 
with  previously  sifted  and  slaked  lime,  and  one-fifth  to  oue-fourth  of  its  balk  of  sawdust 
The  mass  is  then  placed  in  heds  or  layers  exposed  to  open  air,  moistened  with  water,  and 
is,  after  twenty-four  hours,  fit  for  use  in  the  same  apparatus  as  is  employed  in  the  dry  lime 
purifying  process.  According  to  the  results  of  the  scientific  researches  of  A.  Wagaer 
(1867),  G^Us  (1862),  of  Brescius,  Deioke,  and  others,  the  peroxide  of  iron  of  the  T^ftwiTng 
mixture  becomes  converted  by  the  sulphuretted  hydrogen  into  sesqaisnl^oret  of  in» 
(Fe2S3),  and  by  exposure  to  air — revivifying  process,  for  which  purpose  old  purifiers  ■» 
used,  air  being  forced  through — the  sulphur  is  separated  again,  and  oxide  of  irca 
mechanically  mixed  with  sulphur  is  left.  This  mixture  may  be  used  several  times,  ani 
as  mentioned  in  the  earher  pages  of  this  work,  the  sulphur  may  be  adrantageoady 
extracted  from  this  mixture.  Gauthier-Bouchard,  at  Paris,  has  proved  that  the  m^ga 
Laming  mixture  may  be  used  on  the  large  scale  for  manufacturing  Berlin  bine  and  yellow 
prussiate  of  potash ;  while  Menier,  at  Marseilles,  prepares  annually  12  to  15  tons  of  snlpko- 
oyanide  of  ammonium  from  the  spent  gas-purifying  materials.  Yeiy  recently  (1869)  tkd 
proposition  has  been  made  to  withdraw  the  benzol  contained  in  iUuminating  gas  hj 
passing  the  gas  through  heavy  oils  of  tar,  from  which  the  benzol,  to  be  used  for  aoiliDe 
making,  is  to  be  separated  by  fractioned  distillation,  and  the  gas  again  rendered  Inminoaft 
by  passing  it  through  benzoline,  light  petroleum  spirit.  It  is  evident  that  considering  the 
great  bulk  of  gas  to  be  operated  upon,  this  proposal  or  suggestion  will  be  diffionlt  to  cany 
oat  in  practice,  and  also  costly  in  consequence  of  the  apparatxis  required. 

OM-hou«n.  These  apparatus,  sometimes  but  less  correctly  termed  gasoineters, 
serve  as  well  for  the  purpose  of  storage  of  the  great  bulk  of  the  gas  as  for  causing  a 
sufficient  pressure,  so  as  to  regulate  its  flow  through  the  street  mains  and  boraeiB. 
The  gas-holder  consists  of  three  parts,  viz. : — i.  The  tank,  a  cylindrical  water-tight. 
more  or  less  deep  vessel,  with  vertioal  sides,  filled  with  water  as  a  hydraolic  Iste. 
2.  The  bell,  or  rather  inverted  cylinder,  which  can  move  freely  between  the  siand- 
pillars  by  the  aid  of  grooved  rollers  or  pulleys,  which  work  on  iron  bars  fitted 
against  the  stand-pillars.  3.  The  large  inlet-pipe  which  communicates  with  the 
purifiers,  and  the  outlet-pipe  which  communicates  with  the  street  mains,  each  being 
supplied  with  valves  and  syphon-boxes  for  the  purpose  of  collecting  any  water 
which  might  condense  or  otherwise  find  its  way  into  these  pipes. 

The  tank  was  in  former  days  made  of  wood,  then,  when  the  size  of  the  gas-holders 
was  increased,  of  cast-iron  plates  fitted  with  flanges  provided  with  holes  for 
screw-bolts,  the  joints  being  filled  with  cement  so  as  to  make  a  water-tight  vesseL 
Now  the  tanks  are  constructed  by  digging  to  a  greater  or  less  depth  into  the  soiL  the 
bottom  and  sides  being  laid  in  brickwork  with  a  water-tight  cement  backed  by  a 
puddling  of  clay.  In  some  few  cases  the  tank  is  constructed  as  exhibited  in  f^g.  293, 
where  a  cone  remains  covered  by  brickwork,  but  as  water  is  generally  plentiiuL,  and 
is  less  costly  than  the  .expense  attending  this  arrangement,  it  is  not  usuaL  The 
bell  or  holder  is  always  made  of  sheet- iron  plates  ri vetted  together,  care  being  taken 
either  to  put  red-lead  putty,  or  brown  paper  soaked  with  red-lead  paint  or  thick 
boiled  tar  between  the  overlappings  of  the  plates  so  as  to  obtain  good  joints.  The 
plates  are  inside  and  outside  painted  with  iron -paint  or  coated  with  boiled  coal-tar. 
Formerly,  with  gas-holders  of  a  capacity  varying  from  30,000  to  80.000  cubic  feeC 
the  bell  was  suspended  by  means  of  iron  chains  led  over  puUeys  fastened  to  the 
stand-columns  and  provided  with  heavy  weights  for  the  purpose  of  counterbalancing 
the  too  great  weight  of  the  iron  holder  and  to  regulate  the  pressure  exerted  upon  the 
gas ;  but  with  the  very  large  holders  now  in  use,  and  the  practice  of  building  them 
of  thinner  iron  plates,  the  holders  are  simply  made  to  move  freely  between  the 
stand-columns  as  exhibited  in  Fig.  293.    In  order  to  gain  space  with  the  same  depth 


ARTIFICIAL  LIGHT.  657 

cf  tank,  the  so-called  teleacopicgRS-holdeTBareconstrticted.  being,  in  fact,  one  or  more 
cylinders  fitUng  into  each  other  and  capable  of  sliding  upwards  wvX  downwards,  the 
topmost  cylinder  only  being  fitted  with  a  roof,  while  a  gas-tight  joint  is  obtained  by 


«  hydraulic  Inte  The  inlet  and  outltt  mams  are  of  cast  iron  and  open  just  «  few 
inches  above  the  level  of  the  natpr  in  the  tank  (Figs  288  and  293)  A  peeiiliar 
ennstrnctioQ  of  gas  holder  iniented  bv  Pauwt-ls  at  Pans  and  in  use  in  sume  of  the 
gas-works  of  tliat  cit;  is  exhibited  111 1  ig  294     The  uilet  and  outlet  pipes,  it  and  b. 


Fk;.  294. 


are  in  this  gas-holder  connected  with  the  roof,  and  consist  of  several  pieces  witli 
joints  fittod  with  gua-tight  stuffing-boxes,  tlie  arrangement  being  readily  unilerHtood 
from  the  engraving.  Tlie  advautiige  is  that  all  chance  of  flooding  of  the  inlet  and 
ootlet  pipes  is  prevented,  but  the  arrangement  is  expensive  and  not  compatible  with 
telescopic  gas-holders ;  inuruover,  t)ie  level  uf  the  walcr  in  the  tanks  of  gu-hohlera 


658  CHEMICAL  TSCBN0LCO7. 

is  rarely,  if  ever,  subject  to  any  great  increase  in  height,  because  a  drain-pipe  ii 
fitted  to  the  npper  rim  of  the  tank  for  carrying  off  rain-water.  Gas-engineen  vdl 
enough  know  that  it  is  difficult  in  many  cases  to  prevent  leakage  from  tanks  so 
effectually  that  there  should  be  much  risk  of  the  sudden  flooding  of  the  inlel  and 
outlet  pipes  by  a  rush  of  water.  Small  gas-holders  are  often  provided  with  a  scale, 
the  divisions  of  which  correspond  to  certain  quantities  of  cubic  measure ;  bat  Imt^ 
gas-works  are  nearly  all  fitted  with  a  station-meter,  through  which  all  the  gas  waie 
has  to  pass  previous  to  entering  the  gas-holders,  and  by  means  of  this  meter  a 
control  is  kept  over  the  quantity  of  gas  made.  The  cubic  capacity  of  every  gas-hdd^ 
is  of  course  accurately  known.  The  size  of  the  gas-holders  varies;  some  tX^reij 
small  works,  for  villages,  railway-stations,  country-seats,  Ac.,  are  only  1000  to  3000 
cubic  feet  capacity,  while  there  exist  gas-holders  of  enormous  size,  45  metres  dianetv 
by  20  in  height,  which  contain  i  million  cubic  feet.  According  to  Riedinger's  role,  the 
cubic  capacity  of  a  gas-holder  should  be  equal  to  2  to  2I  times  the  average  dmtj 
quantity  required. 

The  fiUing  of  a  gas-holder  is  proceeded  witli  in  the  following  manner  :-r-The  aalid 
main-pipe  having  been  shut  off  by  the  closing  of  the  valve  fitted  to  it,  gas  is  admitted 
through  the  inlet-main  into  the  holder ;  the  gas  accumulating  in  the  latter  exerts  a 
pressure  upon  the  water  in  the  tank,  which  consequently  is  depressed  inside  the 
holder  and  rises  higher  outside  it,  while  gradually  the  holder  is  lifted  by  the  force  cf 
the  gas,  the  inlet  valve  being  shut  off  as  soon  as  the  holder  is  filled  to  within  aboot 
20  centimetres  of  its  height.  Wlien  the  outlet  valve  is  then  opened  the  gas  flows  iota 
the  street  mains,  the  pressure  being  obtained  firom  the  weight  of  the  holder.  In 
order  to  ascertain  the  quantity  of  the  gas  made,  it  is  measured  by  a  large  gaso- 
meter, technically  termed  a  station-meter,  and  placed  between  the  purifiers  aoi 
the  inlet  to  the  gas-holders.  The  construction  of  these  station-meters  is  very  airailar 
to  that  of  the  ordiuary  wet  gas-meters. 

Very  little  is  known  as  to  the  composition  of  the  gas  at  the  difEerent  stages  of  its 
manufacture  from  the  moment  it  enters  the  hydraulic  main  to  the  moment  it  mten 
the  street  mains.  The  experiments  of  Firle,  made  at  Breslau  in  i860,  are  ven- 
valuable,  but  only  relate  to  a  special  inquiry. 

Firle  tested  coal-gas : — (a)  after  it  left  the  condenser ;  (b)  aft«r  it  left  the  scrubber: 
(c)  as  taken  from  the  washing-machine ;  {d)  as  taken  from  the  punfier  eontainiag 
Laming's  mixture ;  (e)  as  taken  from  the  lime-purifier,  consequently  thorooi^ 
purified  gas  as  sent  into  the  holder : — 

a. 

Hydrogen 37'97 

Marsh-gas 3978 

Carbonic  oxide 7*21 

Heavy  carburetted  hydrogens...  4*19 

Nitrogen    4*81 

Oxygen      0*31 

Carbonic  acid 372 

Sulphuretted  hydrogen 106 

Ammonia 0*95 

Beferring  these  figures  to  bulk,  and  taking  1000  cubic  feet  of  crude  gas  as  Ihe  nait 
quantity,  we  find  the  following  proportions : — 


b. 

c. 

d. 

e. 

3797 

37  97 

37*97 

3797 

38-81 

3848 

4029 

39*37 

715 

711 

3*93 

397 

466 

446 

4'66 

4*9 

4*99 

6-89 

786 

999 

047 

0*15 

0*48 

0*61 

387 

3*39 

333 

0'4i 

i"47 

056 

036 

— 

054 

— 

— 

— 

ARTIFICIAL  LIGHT.  659 


Gnbio  feet. 


r 

a«  &•  e.  dm  Bm 

Hydrogen     380  380  380  380  380 

Marsh-gas    390  388  384  403  394 

Carbonic  oxide        72  71  71  39  30 

Heavy  earbnvetted  hydrogens  ...      42  46  45  46  43 

Nitrogen       ...      48  50  69  79  100 

Oxygen •.     ••«     3  5  ^  5  ^ 

Carbonic  acid       •      40  39  34  33  4 

Sulphuretted  hydrogen      •      15  15  5  3  — 

Ammonia      •».    ...     «••     ••.     •••      10  5  *""  ""■  "~ 


1000        999        990       988       966 

The  above  results  exhibit  the  changes  which  the  composition  of  the  gas  undergoes 
daring  the  purifying  process  as  well  as  the  action  of  the  different  apparatus.  When 
1000  cubic  feet  of  gas  composed  as  stated  in  (a)  enter  the  purifying  apparatus,  in 
each  of  these  there  is  taken  up  of  the  absorbable  gases,  chiefly  carbonic  add, 
sulphuretted  hydrogen,  and  ammonia,  the  under-mentioned  quantities : — 

For  1000  cubic  feet  in  cubic  foot  measure : — 

Washing-'    Laming's       Lime- 
Scrubber,     machine,     purifier.        purifier. 

Carbonic  acid     ^  i  5  i  29 

Sulphuretted  hydrogen    ...  —  10  2  3 

Ammonia    ...    • '.  5  5  '~'  '~' 

Carbonic  oxide —  —  32  — 

Oxygen       —  3  —  — 

The  original  bulk  of  the  gas  decreases  consequently  steadily,  and  there  remain  of 
1000  cubic  feet  of  crude  gas  after  leaving : — 

The  scrubber •     ..•     ...  994  cubic  feet. 

The  washing-machine    971 

The  Laming's  purifier    936     „ 

The  lime-purifier    914     „ 

This  is  correct,  premising  that  the  other  constituents  of  the  gas  are  unabsorbed, 
which  really  is  so,  as  we  may  neglect  the  very  small  quantities  of  marsh-gas  and 
heavy  hydrocarbons,  which  are  kept  mechanically  arrested  in  each  purifying  appa- 
ratus. The  bulk  of  the  gas  is,  however,  slightly  increased  by  an  addition  of 
atmospheric  sir.  1000  cubic  feet  of  the  crude  gas  (a)  contain  51  cubic  feet  of  oxygen 
and  nitrogen ;  this  quantity  is  increased  :— 

In  the  scrubber  by  * 4  cubic  feet 

In  the  washing-machine  by    20     „      „ 

In  the  Lduning's  purifier  by    33 

In  the  lime-purifier  by     55 


If  f> 
tf 
If 


19  n 


By  this  addition  the  total  bulk  of  the  gas  in  each  apparatus  is  again  increased,  and 
amounts  (taking  account  of  the  variable  quantity  of  marsh-gas  and  heavy  carbn- 
retted  hydrogen, compounds)  for  1000  cubic  feet  unit  quantity: — 


1 


„    Laming's  purifier,  to  .     988      „       „ 
„         „  „    lime-purifier,  to 966      „       „ 


660  CHEMICAL   TECHNOLOGY. 

After  leaving  the  scrubber,  to       999  cnbic  feet. 

washing-machine,  to  .     990 

Laming's  purifier,  to  .    988 

„    lime-purifier,  to 966 

It  is  understood  that  temperature  and  pressure  remain  constant  during  thepm- 
fying  process. 

Distribution  of  Gas.  Generally,  in  the  United  Kingdom,  and  as  regards  coal-gu  also 
abroad,  the  gas  is  conveyed  to  the  localities,  where  it  is  to  be  burnt  by  means  of  cist- 
iron  pipes  laid  underground.  But  so-called  portable  gas  (gas  portatif]  is  sdH 
made  abroad  and  conveyed  to  the  consumers  in  large  gas-tight  bags  placed  in  cars, 
the  bags  being  emptied  at  the  houses  of  tlie  consumers  into  small  gas-holders.  Tbe 
mateiials  from  which  this  kind  of  gas  is  made  are  generally  such  (refuse  of  oil,  oil  d 
bones,  very  crude  olive  oil,  resins,  &c.)  as  yield  a  gas  of  far  higher  illnminating  powff 
bulk  for  bulk  than  coal-gas.  so  that  a  comparatively  small  bulk  of  gas  will  snffice  fs 
even  a  large  number  of  burners.  The  pressure  exerted  upon  the  gas  in  the  hoHea 
causes  it  to  move  through  the  pipes.  The  amount  of  this  pressure  is,  howcvfr, 
usually  regulated  at  the  works  by  a  peculiar  mechanical  contrivance,  so  as  to  make 
it  as  uniform  as  possible  over  the  total  length  of  the  mains  and  service-pipes.  Coal- 
gas  being  lighter  than  air  has  a  tendency  to  rise,  and  for  this  reason  it  is  conaderrf 
preferable  to  build  gas-works  at  the  lowest  level  of  the  locality  it  is  intended  to 
supply,  because  a  less  pressure  is  sufficient  for  moving  the  gas  through  the  maiss. 
The  pressure  at  the  burners  should  be  from  0*05  to  0*15  of  an  inch,  watcr-giE?« 
pressure,  while  at  the  gas-works  a  pressure  of  2 J  to  5  inches  (water-gauge)  is  fjH^ 
sufficient  to  force  gas  to  any  distance  within  a  circuit  of  several  miles. 

The  street  mains  are  made  of  cast-iron,  and  laid  under  the  pavement  at  a  smtabk 
depth,  varying  from  o'6  to  i'6  metre.  Tlie  service-pipes  in  England  and  on  theCce- 
tinent  are  of  malleable -iron  or  of  lead,  but  in  Scotland  cast-iron  pipes  (even  quartti 
and  half-inch)  are  preferred  and  in  general  use.  The  large  mains  are  pat  togetiiff 
by  placing  the  spigot  into  the  socket-end  of  each  pipe  alternately,  and  caulking  ia 
greased  or  tarred  tow  and  pouring  in  molten  lead.  In  Scotland  the  mains  are  so* 
genei-ally  pat  on  the  lathe,  and  the  spigot  and  socket  ends  turned  true,  so  as  to  gi^^ 
a  gas-tight  joint  simply  by  the  aid  of  some  red -led  paint  and  putty  and  a  coDarrf 
soft  greased  tow.  Although  carefully  laid,  tlie  gas-mains  give  rise  to  moit  « 
less  loss  by  leakage,  wliich  is  stated  to  amount  in  some  instances  to  15  or  20,  aci 
even  25  per  cent  of  the  gas  made  and  sent  into  the  aiains ;  but  if  street  mains  are 
cast  vertically  and  the  iron  be  of  good  quality,  each  pipe  properly  tested  by  hydraatt 
pressure  for  its  soundness  before  being  laid,  and,  moreover,  first  immersed  in  1** 
coal-tar  and  the  joints  well  secured,  leakage  may  be  very  much  reduced,  if  >^ 
altogether  prevented.  Tlie  mains  should  have  a  sufficiently  large  bore  for  t^ 
quantity  of  gas  to  be  convoyed  tlirough  them,  so  as  to  reduce  friction.  They  are  »"* 
laid  quite  level  even  in  level  streets,  but  slop^  gently ;  while  at  the  lowest  k^^l 
so-caUed  syphon-pots  are  placed  for  tliij  purpose  of  collecting  any  condensed  watcr- 
the  gas  is  almost  saturated  witli  water  by  being  in  contact  with  it  in  the  gas-hoWtrs. 
altliough  after  some  time  a  tliin  layer  of  empyreumatic  matter  covers  tlie  surfert*:^ 
the  water,  tliereby  preventing  the  gas  becoming  excessively  saturated.  Thta* 
syphon-pots  are  fitted  with  a  narrow  iron  tube  reaching  nearly  to  the  surface  of  ih* 
pavement,  being  closed  by  a  screw-cap,  which,  being  unscrewed,  a  hand-pump  nuj^ 
screwed  on,  and  any  condensed  water  pumped  out  of  the  syphon-pot  or  box.    For  the 


ARTIFICIAL  LIGHT. 


66i 


J 


^ 


.-UV 


•*£"5* 


purpose  of  connecting  the  burners  with  the  service-pipes  narrower  tubes  are  used, 
made  either  of  pure  block-tin  or  of  an  alloy  of  lead  and  tin  or  of  lead  and  copper ; 
the  latter  are,  however,  not  so  readily  bent,  and  have  tlie  disadvanUige  that  there 
may  be  formed  in  them  acetylen-copper,  wliich,  as  proved  by  Crova,  is  a  very  explo- 
sive compound. 

HydrauUe  Voire.  The  valvo  represented  in  Fig.  295  is  now  almost  superseded  by  valves 
of  a  totally  different  description,  termed  slide-valves,  and  worked  similarly  to 
those  in  use  for  the  water-mains  common  in  London 
streets.  The  valve  represented  in  the  engraving 
in  placed  near  the  gas-holdeib',  and  may  serve  either 
for  shutting  off  the  inlet-pipe  to  the  holder  or  for 
the  same  pnq>ose  at  the  outlet-pipe.  The  valve  con- 
sists of  an  iron  vessel,  i  k  l  m,  filled  with  water.  The 
pipe  A  commnni(;ates  with  the  gas-holder  and  b 
with  the  street  main.  The  drum -like  vessel,  cepd,  is 
suspended  over  the  pipes  and  is  counterbalanced  by  the 
weights  .r  aud  y.  When  the  latter  are  removed  the  drum 
sinlEs,  and  the  partition  n,  dipping  in  the  water,  cuts  ofif 
the  communication  between  a  and  b. 

prpMure  RoKuiacor.  This  coutrivauce,  actiug  automati- 
cally, is  arranged  for  the  piurpose  of  regulating  the 
supply  of  gas  from  the  gas-liolders  to  the  mains.  It 
consists  essentially  of  a  small  gas-holder  connected  with 
a  conical  valve  placed  in  the  outlet-pipe,  while  the  small 
gas-holder  to  which  it  is  fastened  is  very  accurately 
adjusted,  or  provided  with  counterweights,  by  means  of  which  its  position  may  be  set  at  a 
certain  supply  f  ither  per  hour  or  evening,  as  the  case  may  be.  If  from  some  cause  or 
other  the  consumi)tion  of  gas  increases  the  gas-holder  will  sink,  and  the  opening  in 
which  the  conical  valve  plays  becomes  larger,  and  consequently  more  gas  passes  through  ;  if, 
on  the  other  hand,  the  supply  decreases,  the  consequence  will  be  that  too  much  gas  enters 
the  small  holder  from  the  large  ones,  and  the  former  rising  draws  the  conical  valve  with  it 
upwards,  thus  more  or  less  completely  plugging  the  outlet -pipe. 

Tenting  niomtiiiiUnR  om.  The  cause  of  the  luminosity  of  tlie  flame  of  gas  is  the  ignited 
carbonaceous  matter.  Everything,  therefore,  which  impairs  the  separation  of  tlie 
cai'bonaceous  matter  or  chemically  affects  their  proper  ignition,  decreases  the 
luminosity  of  the  flame;  among  these  deteriorating  causes  are: — i.  Excessive 
admission  of  air  or  of  oxygen.  A  coal-gas  flame  bummg  in  oxygen  will  be  found  to 
have  lost  its  luminosity,  and  the  same  occurs,  as  is  well  known  and  exhibited  in  the 
Bunsen  gas-burner,  when  gas  is  mixed  with  air  previous  to  being  igrnited.  2.  Car- 
bonic acid.  When  red-hot  or  white-hot  carbonaceous  matter  comes  into  contact 
with  carbonic  acid,  there  is  formed  carbonic  oxide  (C0a+C=2C0).  which  bums 
with  a  blue,  non-luminousidame.  As  elayl-gas  (C2H4)  becomes  decomposed  by  red 
heat  into  methyl-hydrogen  (marsh -gas,  CH4)  and  carbon  (C),  and  as  the  latter 
reduces  an  equivalent  quantity  of  carbonic  acid  to  carbonic  oxide,  it  is  evident  that 
the  carbonic  acid  deprives  half  its  bulk  of  elayl-gas  of  its  illuminating  power.  Sup- 
pose an  illuminating  gas  to  contain  6  per  cent  of  elayl-gas,  and  also  6  per  cent  of 
carbonic  acid  gas,  the  result  will  be  the  elimination  of  the  luminosity  of  3  per  cent 
of  elayl-gas.  This  proves  the  great  importance  of  the  complete  removal  of  carbonic 
acid  from  gas  by  tlie  lime-purifier. 

Very  little  has  been  cxpeidmentally  proved  as  to  the  relation  existing  between  the 
illuminating  power  of  a  flame  and  the  quantity  of  the  separated  carbonaceous 
particles  ;  it  is  probable,  however,  that  tliis  relation  is  a  direct  one,  and  that  there- 
fore the  luminosity  of  a  flame  is  the  stronger  the  larger  tlie  quantity  of  carbonaceous 
particles  separated,  provided,  however,  that  the  temperature  of  the  flame  be  very 
high,  because  otherwise  tlie  flame  will  be  eitlier  ruddy  or  smoky.    Although  by  an 


66a  CHEMICAL   TECHNOLOOY. 

increased  access  of  air  (as  in  the  case  of  petroleum  lamps  provided   with  a  gisa 
chimney  I  the  combustion  may  be  increased  so  as  to  create  a  very  high  tempentarre 
of  the  flame  and  thereby  a  very  white  hght,  it  is  probable  that  this  expedient  (espe- 
cially if  applied  to  ordinary  coal-gas)  would  cause  a  too  sudden  combustion  of  tlic 
carbon,  rendering  it  useless  for  illuminating  purposes.     Supposing  the  illumiotliBg 
power  of  a  flame  to  be  proportional  to  the  quantity  of  carbonaceous  partides  sept- 
rated,  and  applying  this  principle  to  some  of  the  carburetted  hydrogens  occuning  in 
purified  illuminating  gas,  taking  account  more  particularly  of  the  gases  (CHfi  » 
composed  that  by  ignition  they  become  decomposed  into  methyl-hydrogen  and 
carbon,  we  have : — 
Vol.  Vol.  Vols. 

I  elayl,  C2H4,  which  yields  10  of  methyl-hydrogen  and  2  of  vapoar  of  carbon. 
I  trityl,  C5H6,       „        >t       1*5  f»      «  «  »    3  »» 

I  ditetryl,  C4H8,  „        „      1*0  „      ,.  „  „    4  „     „ 

and  may  assume  the  illuminating  power  of  these  three  gases  to  be  as  2 : 3 : 4.  Takiiig 
the  illuminating  power  of  elayl-gas  to  be  100,  the  illuminating  powers  of  the  gases  tnd 
vapours  contained  in  purified  coal-gas  may  be  represented  by  the  nnder-mentiooed 
figures,  the  vapours  having  been  calculated  at  a  sp.  gr.  =  o*" : — ^Elayl,  100 :  trityl,  150; 
ditetryl,  200;  propyl,  250;  butyl,  350;  acetylen,  450;  vapour  of  benzol,  450; 
vapour  of  naphthaline,  800. 

The  following  figures  exhibit  the  quantity  of  elayl-gas,  for  which  can  be  substitnted 
a  combustible  gas  (hydrogen  or  marsh-gas)  impregnated  with  the  vapours  of  hydro- 
carbons at  0°  and  15"  for  yielding  an  equal  amount  of  light.    Impregnation  with— 

At  o*.  At  15*. 

Vapour  of  propyl,  is  equivalent  to    11  "500  25700  vols,  elayl. 

„       „  benzol,  „        „  „       9630  23700    „        „ 

„       „  naphthaline,  „        „  „      o-ii6  oo*oi6    „        „ 

When,  therefore,  100  litres  of  hydrogen  at  o**  or  at  15**  are  saturated  with  vapons 
of  benzol,  the  illuminating  power  of  the  resulting  mixture  is  equal  to  that  wfaidi 
would  ensue  by  mixing  100  litres  of  hydrogen  with  96  or  23*5  litres  of  elayl-gas. 

In  order  to  saturate  100  English  cubic  feet  of  hydrogen-  or  marsh-gas  with  vaponn 

of  hydrocarbons,  there  are  required  of : — 

At  o*.  At  i5«. 

Vapours  of  propyl     500*00               ii28'oo  grammes 

„        „  butyl       17*00  *           58  00        „ 

„        „  benzol     214*50                  522*00        „ 

„        „  naphthaline    0*32                     0*32        „ 

For  the  purpose  of  carburetting  hydrogen-gas  with  vapours  of  benzol  to  saturaticB, 
2145  grms.  of  benzol  at  0°,  and  5220  grms.  of  the  same  at  15°,  would  be  reqoired 
for  1000  cubic  feet  of  gas. 

^SStoaUn?^"  In  order  to  ascertain  the  relative  value  of  illuminating  gas  fonr 
diflerent  modes  of  testing  are  now  in  practical  use,  viz. : — i.  Gasometrical  te^i 
2.  Specific  gravity  test.    3.  Photometricaltests.    4.  £rdmann*s  gas-testing  appaiatas. 

I.  The  gasometrical  test  requires  for  its  proper  management  an  accurate  knoir- 
ledge  of  Bunsen's  method  of  gas  analysis.*    Be  it  sufficient  for  our  purpose  here  to 

*  Anleltznng'  zu  einer  teohnischen  Leuohtgasanalyse  giebt  Adolf  Biehter ;  Dins^> 
polyt.  Journal  (1867),  Bd.  olzzzvi.,  p.  394. 


ARTIFICIAL  LIGHT.  663 

mentioii  that  a  mixture  of  atihydifous  snlphnric  acid  and  ordinary  concentrated  oil  of 
vitriol  has  the  property  of  absorbing  the  heavy  hydrocarbons  contained  in  illumina- 
ting gas,  which  absorption  is  best  effected  by  bringing  into  an  eudiometer  containing 
the  gas  to  be  tested,  a  piece  of  coke  moistened  with  the  acid,  and  fixed  on  a  piece  of 
platinum  wire.    In  order  to  ascertain  the  quantity  of  carbon  of  these  compounds, 
the  toFit,  in  which  the  decrease  of  bulk  of  the  gas  indicates  the  relative  quantity 
of  the  hydrocarbons,  is  combined  with  two  separate  eudiometrical  tests,  the  gas 
being  first  ignited  by  itself  with  an  excess  of  oxygen,  and  tlie  operation  repeated 
with  the  gas  after  it  has  been  acted  upon  by  the  sulphuric  acid.    The  quantity  of 
CO2  obtained  in  the  last  instance  is  then  deducted  from  that  obtained  by  the  first 
operation.     Chlorine  and  bromine  are  very  frequently  employed  to  absorb  the 
heavier  hydrocarbons  present  in  gas,  these  haloids  combining  with  the  hydrocarbons 
as  a  fluid  residue.    According  to  a  method  of  gas  analysis  originally  devised  by 
O.  L.  Erdmann,  and  described  by  C.  0.  Orasse,*  the  gas  first  freed  from  any  carbonic 
acid  it  may  happen  to  contain  is  burnt  from  a  burner  connected  with  a  small 
gas-holder,  by  the  aid  of  oxygen ;  the  water  and  carbonic  acid  formed  are  collected 
and  weighed.    2.  The  estimation  of  the  value  of  an  illuminating  gas  by  specific 
gravity  is  frequently  employed  in  practice,  as  experience  has  proved  that  as  a  rule  a 
higher  illuminating  power  of  gas  (provided  it  be  well  purified  and  freed  from 
carbonic  acid),  is  intimately  connected  with  its  higher  specific  gravity;  but  it  does 
not  follow  that  a  light  gas  is  useless,  while  there  ought  to  be  taken  into  account  the 
durability  of  the  gas,  by  which  is  understood  the  length  of  time  a  cubic  foot  of  the 
gas  will  burn  under  a  certain  pressure  (as  low  as  possible)  from  a  given  burner, 
and  yield  a  certain  light  to  be  tested  either  by  comparison  with  another  kind  of  coal- 
gas  or  standard  sperm  candles  by  the  photometer.    In  Scotland,  the  gas  engineers 
when  testing  caunel  and  other  coals  always  take  into  consideration  and  minutely  esti- 
mate by  means  of  very  accurate  apparatus  these  particulars,  care  being  taken  to  manu- 
facture the  gas  on  the  large  as  well  as  on  the  small  scale,  taking  say  4  cwt.  of  coals,  and 
to  compare  both.    In  most  of  the  large  Scotch  gas-works,  a  separate  experimental  gas- 
work,  with  two  or  three  retorts,  and  all  the  necessary  apparatus,  is  to  be  met  with,  as 
it  has  been  found  that  only  by  the  use  of  judiciously  selected  mixtures  of  different 
cannel  coals,  a  gas  of  high  illuminating  power,  great  purity,  and  average  durability, 
can  be  supplied  at  the  price  now  generally  adopted  per  1000  cubic  feet. 

Illuminating  gas  consists  of  a  mixture  of  various  gases  and  vapours,  having 
different  specific  gravities,  viz.,  elayl-gas,  0*976 ;  methyl-hydrogen,  0*555 ;  hydrogen, 
0*069;  carbonic  oxide,  0967;  carbonic  acid,  1*520.  The  specific  gravity  of  the 
vapours  present  in  coal-gas  varies  of  course  according  to  the  bodies  which  are  met 
with  in  the  gas  in  the  state  of  vapour ;  among  these  benzol  is  one  of  the  most 
important  for  illuminating  purposes.  The  estimation  of  the  specific  gravity  of  illu- 
minating gas  as  a  test  of  its  quality  is  only  of  value  if  taken  in  connexion  with  other 
tests  applied  to  the  same  gas.  Dr.  Schilling  has  constructed  an  apparatus  for  the 
purpose  of  taking  the  specific  gravity  of  illuminating  gas.  This  apparatus  is  based 
upon  the  fitct  that  the  specific  gravities  of  two  gases  issuing  from  narrow  apertures 
in  a  thin  plate  under  equal  pressure  are  to  each  other  as  the  squares  of  their  time  of 
efflux.  There  are  several  more  readily  managed  apparatus  for  estimating  the 
specific  gravity  of  illuminating  gas,  and  among  them  those  made  by  Mr.  Wright,  of 
Westminster.    3.  Photometrical  tests  and  apparatus,  Bunsen's,  Wight's.  Desaga'a 

*  Journal  fur  Prakt.  Chemie  (1867),  oil.,  p.  257. 


^ 


664 


CHEMICAL  TECHKOLOGY. 


(Bothe'e  tangentol  pliotometer),  and  others  are  freqiii?ntly  eiuplojei]  fur  Itao! 
the  value  of  gas  and  comparing  its  illuminating  power  H'ith  that  of  Uta^n  ■< 
candles.  As  the  kind  of  burner  emplo.ved  in  thesn  experiments  )ias  v^nr  fnv 
influence  on  the  reEults,  pliotometrical  estimations  of  the  value  of  gases  require  gnd 
care.  4.  Erdrnann's  gas  tester,  introduced  on  tlie  Continent  in  many  ^tswaVi 
since  1S60,  is  a  vciy  useful  and  retulilj  manageable  instrument,  based  iipun  tlw  ba 
^lat.  as  the  valne  of  an  illiiniinating  gas  depends  mainljr  upon  the  quantity  ot  h<%^ 
hjdrocarbons  contained,  tliat  qnantitj  may  be  measured  by  estimaiin;;  the  Hnixnl 
of  atmottpheric  air  required  to  deprive  tlie  Hame  of  the  burning  gas  of  a  given  sur 
of  alt  illuminating  power. 
au-DHMn.  At  flrBt,  in  the  early  days  of  gas-lighting,  tbe  barxnin  between  eonsniDfr  ud 
BellerisaH  to  pay  a  ceitaiu  sum  per  burner  per  hour,  or  to  I'oiitract  for  a  certain  fosn  j^ 
annnm  for  a  giveu  number  of  burners  kept  hghted  from  dank  (ill  n  cerlnin  honr  of  C* 
night,  at  rbicb  time  it  was  customary  to  have  the  tnmcockii  of  the  rbb- works  at  hud  " 
their  respectire  beats,  to  turn  off  the  supplv  of  the  bouse,  by  shattinR  ■  tup  pl>^ 
on  purpose  in  the  servico  pipes ;  but  although  here  and  tliere  in  Email  lowux  in  lul^. 
France.  Spain,  and  Germany,  this  arrangement  still  es:ists,  it  in  the  eiceptinn  aoa  dpi  ll' 
mle;  tbe  latter  being  that  tbe  ga^  is  sold  by  cubic  measure  as  registered  bv  inBtraimli 
termed  gas-meters,  the  construction  ot  which  is— especially  in  the  Uiiiled  Kinrriosi- 
brought  to  such  a  high  stanilaid,  that  Mr.  Ratter's  remark  is  perfectly  tme—lhtl  e^' 
is  measured  with  greater  accuracy  than  anything  eine  either  measured  or  wa^laei  a 


We  distinguish  between  dry  and  wet  meters  ;  tbe  conatructioo  0/  tbe  former  it  I** 
tbe  following :— In  a  (lastiglit  metallic  box  nre  plnocd  two  or  three  bellows-like  Tetetif. 
which  instead  of  leiuK  iuflaled  by  air,  arc  inflateil  by  tbe  gas  entering  from  the  »ttv* 
pipe.     When  influleil  to  some  extent  an  arrangement  ot  springs  and  leven  forcn  tbe  p> 


out  of  the  bellows  again  into  the  eiit-pipc  leading  to  tbe  bnruers.  The  enbic  npacilT'' 
the  chambers  (aa  the  bellows-like  arrangements  are  called)  having  been  accnraK^ 
adjusted,  the  movemeut  ot  tiieir  walls  is  oonunnnicated  to  wbecl-work,  which  being  <*f" 
nected  with  dials,  indicates  in  tens,  buudieds,  and  thonsauds,  tbe  conenmption  of  gu  °> 
cubic  teet. 

Dry  meters  are  preferred  on  acoonnt  as  well  ot  not  being  liHble  to  be  afteciol  V 
trofltas  of  not  causing  tbe  sudden  eilinguiHh ingot  the  gas-lights  tor  want  of  water,  ui°'? 
occur  with  wet  meterB.  Viet  meters  nre  constructed  upon  a  plan  devised  in  1S17  I? 
Clegg,  and  improved  by  Crosaley  and  othem.  Figs.  196,  297,  398,  and  199.  »* 
drawings  ot  this  kind  of  meter,  which  consists  in  the  Urst  place  of  an  outer  cvlinibi'*' 
box  of  cast-iron,  closed  on  all  sides.  In  this  box  is  placed  a  drum  ot  pure  bloclU"' 
divided  into  four  compurlincnls,  bearing  upon  a  bell-metal  a\U,  and  immervod  fornttai 
more  than  halt  its  circumtereuce  in  water.    By  the  preHsuro  of  the  gas  and  lh«  4d*ui| 


ARTIFICIAL   LtaST. 


66s 


lepreBsloti  of  the  -waUr  the  arum  reTolvM.each  ot  its  compartmontB  becoming  altematplj 
lUed  with  and  emptied  of  gas.  On  the  aiia  of  the  dram  is  an  eudlesa  screw,  which 
ay  mechanical  means  is  connected  with  the  wheel-work  of  the  dials.  The  drum  18  Tei^ 
Mjcuratelj  adjusted,  so  that  at  every  complete  reTolation  a  certain  cabio  qnantiiy  of  gaa 
poBBeB  throngh  and  is  registered.  Fig.  196  eihibils  the  apparatus  with  the  front  plate 
removed  ;  Fig.  297  shows  the  side  of  the  meter  ;  Fig.  198  is  sectional  plan  ;  and  Fig.  299 
IB  a  section  through  the  box.    a  ia  the  box  ;  a'  the  drum ;  b  its  axis ;  e  the  endless  screw, 


Fio.  19S. 


Fia.  sgg. 


bearing  in  the  »h»el,  d,  and  carrying  by  maana  of  <  the  moTement  ot  the  dram  on  to  the 
wheelwork  of  th»  dials,/,  g  ia  the  inlet-pipe  (or  the  gas,  which  flows  into  the  valve  boi, 
A.  and  passing  b}<  the  T^ve,  i  (kept  open  as  long  as  the  meter  contains  sufficient  water  for 
its  action),  flows  through  the  bent  tube,  I,  into  the  bulged  cover  of  the  dmm,  or 
tachnically  antechanibei,  m,  and  thence  into  the  several  compartments  of  the  dmm. 
Thence  the  gaa  enters  the  space,  n,  to  which  is  tittei)  the  outlet  pipe,  0.  i  is  the  valve  ; 
p  tbo  float ;  q  the  funnel  tube  for  filling  the  meter  with  water ;  r  Uie  waste  water  cistern ; 
t  the  plug  b;  the  remorol  of  which  the  waste  water  may  be  ran  off.  As  long  as  no  gas- 
bnmers  are  in  ase  the  meter  connected  with  them  is  inactive,  bnt  when  the  gas  is  burnt 
the  drum  rotates,  and  by  its  oommnnication  with  Uie  wheelwork  registeia  the  quantity  of 
gas  eonsnmed.  Instead  of  filling  wet  meters  with  water  they  may  be  filled  with  glycerine, 
which  does  not  freeze  nor  evaporate.  Wet  meters  should  be  placed  perfectly  levd. 
As  regards  their  size  they  are  maJe  to  supply  from  three  lights  up  to  many  thousandB  if 
required.  By  an  Act  of  Parliament  gas-meters  are  tested  in  order  to  ascertain  that  they 
register  properly  within  the  limits  of  the  Act.  The  inspectors  of  gas-meters  hava 
been  provided  with  very  accurate  sets  of  apparatus  made  according  to  four  sets  of  standard 
apparatus,  of  which  one  each  ia  in  the  hands  of  the  Corporations  of  London,  Edinbnrgb, 
and  Dublin;  while  the  fonrth  is  in  the  custody  of  the  ComptroUei  ot  the  Eicheqoer, 
at  Westminster.    Theae  apparatus  are  masterpieces  of  highly  finished  workmanship. 

Bonm.  These  are  made  so  as  to  prodnoe  all  shapes  of  flame,  and  are  of  different 
materials,  iron,  steel,  poroetain,  steatite,  brass,  platinom-lined,  Ac.  The  bore  from  which 
the  flame  of  the  burning  gas  issaes  should  be  arranged,  as  r^ards  its  width,  for  the 
quality  ot  the  gas  consumed — cannel  coal  gas-bniners,  for  instance,  being  provided  with 
narrower  openings  than  those  for  common  coal-gas.  We  have  single  jet  burners,  doubla 
jet  burners,  bats'-wiog,  fish-tail,  cockepor,  and  other  varieties;  also  Argand  burners  of 
various  sizes,  bored  with  six  to  thirty  or  forty-eight  holes,  or  as  in  the  Comas  burner,  a  slit 
instead  of  the  holes.  The  quantity  of  gas  consumed  by  different  kinds  ot  burners  vaiie*. 
of  course,  greatly  for  the  same  kind  of  gas  under  the  same  pressure.  Much  gas  is  wasted 
because  sufficient  care  is  not  taken  by  the  coneumers  to  have  really  good  burners. 

(hiLaoip*.  Of  these  there  is  an  almost  endless  variety,  from  the  most  simple  and  unpre- 
tentious to  the  highly  ornamented  and  expensive  chandeliers. 
"'■"MlSfcrnSr"'"  Among  these  such  as  are  of  important  commercial  advantage  to 
coal-gas  works  ore  : — i.  Coke.  a.  AromoDiacal  liquor.  3.  Tar.  4.  Spent  gas-lime. 
3.  Sulphur  obtained  from  the  Laming  mixture.  In  some  localitieg  Berlin  blue 
ia  made  from  the  cyanide  of  calcium  of  the  Laming  mixtnra  (see  p.  656). 

I.  Coke,  of  which  we  shall  speak  more  particularly  uurler  th«  beading  of  Fuel, 


*66  CHEMICAL  TECHNOLOGY.      ' 

as  gas-coke  is  more  porous  and  spoDgj  than  the  oven-ooke,  and  hence  better  adj^tai 
for  use  in  stoves.    In  Germany  the  gas-works  have  now  very  generally  adopted  ik« 
plan  of  selling  the  coke  broken  up  into  small  nut-sized  lumps,  this  operation  haa^ 
performed  by  means  of  machinery ;  the  breeze  is  mixed  with  some  tar  and  ImeebA 
under  the  retorts  at  the  works.    2.  The  ammoniaoal  liquor  is  essentially  aji  aqaeoas 
solution  of  carbonate  of  ammonia,  2(NH4)2C03-|-COs.    The  quantity  of 
contained  in  this  liquid  must  of  necessity  vary  according  to  certain 
the  quantity  of  water  contained  in  the  coals,  the  larger  or  smaller  amoani  dt 
nitrogen  they  contain,  the  degree  of  temperature  and  duration  of  the  process  of  dis- 
tillation.    The  higher  the  temperature  the  more  nitrogen  -  will  be  converted  isto 
ammonia,  while  otherwise  a  portion  of  it  is  converted  into  aniline,  lepidine,  cbinolme. 
^.,  and  also  into  cyanogen.    Estimating  gas-coals  to  contain  on  an  average  5  per 
cent  of  hygroscopic  water  and  075  per  cent  of  nitrogen,  100  kilos,  of  sndi  coal  will 
yield  under  tlie  most  favourable  conditions  910  grms.  of  ftwiTn/wiT<L'  (NH3).    B 
has  been  found  that  i  cubic  metre  of  ammoniacal  water  yields  on  an  averags 
(see  p.  230)  50  kilos,  of  dry  sulphate  of  ammonia  ([NH4J2S04),  so  that  20  heda- 
litres  yield  100  kilos,  of  this  salt,     i  ton  of  Newcastle  gas-coal  yields  45  litrta 
of  ammoniacal  liquor,  i  litre  of  which  yields  from  74  to  81  grms.  sulphate  of 
ammonia.    3.  Coal- tar,  formerly  a  source  of  inconvenience  to  many  gas-works,  aad 
at  any  rate  a  substance  of  very  little  commercial  value,  has  become  since  1858,  of 
great  importance  as  the  raw  material  for  the  coal-tar  <}olours.    As  already  stated,  tv 
consists  of  fluid  hydrocarbons — benzol,  toluol,  propyl;   solid  hydrocarbons — tasfk- 
thaline  and  antliracen;  of  acids-^carbolic,  cresylic,  phlorylic;   of 
chinoline,  lepidine,  &c. ;  and  lastly,  of  resinous,  empyreumatic,  and 
matters.     The  quantity  as  well  as  the  quality  of  the  lar  obtained  by  the  distiTlatinB 
of  coals  for  gas-making  depends  partly  upon  the  kind  of  coal  used  and  jMurtly  opoa 
the  heat  applied  to  the  retorts ;  as  at  a  very  high  temperature,  for  instance  with  the 
fire-clay  retorts,  the  quantity  of  tar  is  less  than  at  a  lower  temperature.     Owing  as 
well  to  the  carbolic  acid  contained  in  tar  as  to  the  empyreumatic  substances,  it 
has  antiseptic  properties,  and  is  hence  used  for  preventing  the  decay  of  wood 
exposed  to  wind  and  weather,  for  coating  iron,  &c.    Coal-tar  is  also  used  for  the  par- 
pose  of  mixing  with  small  coal,  saw-dust,  peat  dust,  Ac.,  for  making  artificial  fad, 
and    recently,   when    mixed    with    sifted   pebbles,   as   a   substitute    for  as^ialte 
to  form  excellent  footpaths.     In  order  to  separate  the  constituents  of  tar  frcB 
each  other,  it  is  poured  into  a  large  iron  still,  and  heated  to  So*"  to   100",  ftr 
the  purpose  of  distilling  off  the  light  hydrocarbons  along  with  any  ammoniacal  water 
the  tar  may  contain.    After  thirty-six  hours  the  distillation  is  further  proceeded 
with,  and  as  the  latent  heat  of  the  volatile  products  to  be  obtained  is  very  small,  the 
still  ought  to  be  made  as  low  as  possible,  and  the  helm  ought  to  be  well  protected 
against  any  cooling  influence.    At  tlie  bottom  of  the  still  a  tap  is  fitted  for  the  par- 
pose  of  removing,  at  the  end  of  the  distillation,  the  molten  pitch  which  remains.    Is 
some  cases,  however,  the  distillation  is  pushed  further  so  as  to  leave  only  a 
carbonaceous  residue,  the  still  being  made  red-hot  at  the  bottom ;    the  residue 
is  removed  after  the  cooling  of  the  still  by  opening  the  man-hole.    The  distiUatua 
of  750  to  800  kilos,  of  tar  tiikes  twelve  to  fifteen  hours.    At  first  the  heat  should  noC 
be  too  strong,  and  in  many  tar  distilleries  high-pressure  steam  is  passed  through  a 
iH>il  of  pipes  placed  in  the  still,  in  order  to  assist,  together  with  open  fire,  the  fint 


ARTIFICIAL  LIQHT.  667 

stage  of  the  distillation.    The  light  tar-oik  obtained  exhibit  iirst  a  sp.  gr.  of  0780, 
but  on  an  average  0*830.    The  heavy  tar-oil  comes  over  at  200". 

The  light  tar-oil  is  again  distilled,  and  the  distillate  treated  with  strong  snlphurio 
add,  next  with  caustic  soda  solution,  and  then  again  distilled.  The  treatment  with 
sulphuric  acid  aims  at  the  removal  as  well  of  basic  substances  (ammonia,  aniline),  as 
of  naphthaline,  while,  by  means  of  the  caustic  soda,  the  carbolic  acid  is  fixed.  The 
quantity  of  sulphuric  acid  to  be  used  for  this  purpose  amounts  to  5  per  cent  of  the 
weight  of  the  tar-oil :  while  the  soda  solution  of  1*382  sp.  gr.  ( =  40°  B.)  amounts  to 
2  per  cent  of  that  weight.  The  liquid  thus  obtained  is  the  benzol  of  trade; 
it  remains  colourless  on  exposure  to  air,  and  is  a  mixture  of  various  substances  with 
benzol,  toluol,  and  xylol  as  chief  constituents.  It  is  easily  converted  into  nitro- 
benzol  (see  p.  572),  the  starting-point  for  many  of  the  coal-tar  colours.  The  coal-tar 
naphtha,  now  usually  sold  after  the  benzol  has  been  completely  removed  by 
firactional  distillation,  is  used  as  a  solvent  for  caoutchouc  resins,  fixed  oils,  gutta- 
percha, and  for  burning  in  lamps  peculiarly  constructed  for  the  purpose,  and 
only  used  in  open.  air.  Coal-tar  naphtha  is  also  used  for  carbnretting  gas  of  low 
quality.  When  the  crude  oil  of  tar  is  cooled  down  to  —  io\  naphthaline  is 
deposited  from  it,  which,  as  already  mentioned  (see  p.  581),  is  used  for  the  prepa- 
ration of  some  dyes,  and  also  for  the  manufacture  of  benzoic  add.  The  heavy  oil  of 
tar  is  purified  with  concentrated  sulphuric  acid  and  caustic  soda  ley,  and  freed  froia 
fOBtid  sulphur  compounds  by  distillation  over  a  mixture  of  sulphate  of  iron  and 
lime.  By  fractional  distillation  between  150^  and  200®  creosote  is  obtained, 
being  a  mixture  of  carbolic  or  phenylic,  cresylic,  and  phlorylic  acids.  This  is 
the  raw  material  used  for  the  preparation  of  carbolic  acid  and  picric  acid  (see  p.  580), 
also  for  certain  blue  and  red  pigments,  for  creosoting  wood,  for  preserving  anatomical 
preparations,  dtc.    Lunge  obtained  from  a  ton  of  tar: — 

• 

Benzol  at  50  per  cent    2'88  gallons  =     i3'oo  litres. 


Best  naphtha  ...     . 
Burning  naphtha    . 

Creosote 

Ammoniacal  liquor 


2*69        „  =      12*00     „ 

...      3*51      «       =     1508    ». 

...    8325      „       =      374  hectolitres. 

300      „        =       13*5  litres. 

And  III  ewts.  of  pitch. 

The  heavy  oils  of  coal-tar  and  the  pitch  are  now  largely  used  for  the  preparation 
of  anihracen,  from  which  artificial  alizarine  is  made.  The  pitch  is  further  usefully 
employed  in  lacquer  and  varnish  making,  and  also  for  asphalting  pavements. 

4.  The  gas-lime  is  used  abroad  for  the  purpose  of  removing  the  hair  from 
bides  and  skins  intended  to  be  tanned,  the  sulphuret  of  calcium  contained  in  the 
lime  acting  as  a  depillatory.  In  some  localities  the  spent  lime  is  employed  for  making 
Berlin  blue  from  the  cyanide  of  calcium  contained  in  the  lime,  and  for  the  prepara- 
tion of  sulphocyanogen  compounds,  owing  to  the  sulphocyanide.  of  calcium  it 
contains.  As  already  mentioned,  spent  gas-lune  is  largely  used  in  Scotland  as  a 
manure,  which   at   the   same    time   destroys   a   great   many   injurious   insects. 

5.  Sulphur  is  prepared  from  the  TAmit^g  mixture  (see  p.  198),  and  used  for  making 
sulphuric  acid ;  it  might,  perhaps,  be  better  to  extract  the  sulphur  from  the  mixture 
by  means  of  steam  at  130''.  The  Louuing  mixture  is  occasionally  treated  with 
heavy  tar-oils  for  the  purpose  of  eliminating  the  sulphur. 


*-**«'y*    •••    •••    •••    •••    •••     4*1^ 

Ditetryl       3*14 


13^ 


668    ^  CHEMICAL  TECHNOLOGY. 

oompotition  of  co«i-g«  .      The  following  figures  exhibit  the  compositioii  of  pmified  eodi- 
gasin  100 parts  by  bulk : — 

I.        n.        in.       IV.       V.       YL    TIL 

Hydrogen    4400      41-37      39-80      51-29      50*08      460     277 

Marsh-gas  (methyl-hydrogen)  3840      38*30      43*12      36*45      35*92      395     jotd 
Carbonic  oxide   5-73        5-56        4*66        4-45        5*02        7*5       6'8 

:.,J     475        4-91        5  33        3-8 
4  34' 

Nitrogen      423  543  4-65  1*41  1*89  05  04 

Oxygen        —  —           —  0*41  0*54  —  — 

Carbonic  acid     0*37  —  3-0^  i-o8  1*22  07  oi 

Aqueous  yapoor —  —  —  —  —  2"o  aro 

I.  and  n.  Heidelberg  coal-gas.  m.  Bonn  ooal-gas,  analysed  by  H.  LandoH.  IV.  ml 
v.  Ghenmitz,  Saxony,  coal-gas  analysed  by  Wander.  YL  London  ooal-gas  (X867V 
Yn.  London  cannel  gas  (1867). 

wood-gM.  n.  As  already  mentioned  (p.  645)  the  French  engineer  Lebon  v« 
engaged  in  1799  with  the  making  of  gas  from  wood,  and  brought  out  an  apparatni 
tenned  by  him  a  thermolamp,  which,  however,  was  neither  found  to  answer  ibr 
heating  nor  for  illuminating  purposes,  as  the  illuminating  power  of  the  gat 
obtained  by  his  process  from  wood  was  very  inferior  and  could  not  eonqpete  with  tfa« 
coal-gas  which  became  known  soon  after.  The  reason  why  wood,  as  oooTerted  iiit» 
gas  by  Lebon's  apparatus,  did  not  give  satisfactory  results  is  explained  by  Dantt. 
by  proving  that  under  the  conditions  of  the  distillation  of  wood  employed  hj 
Lebon,  the  gas  evolved  consists  chiefly  of  marsh-gas  and  carbonic  oxide,  both  d 
which  can  scarcely  be  considered  luminous  gases.  In  the  year  1849,  I^*  ^-  ^'^ 
Pettenkofer,  at  Munich,  resolved  to  experiment  on  the  manuJactare  of  gas  firan 
wood,  and  he  found  that,  as  stated,  by  Dumas,  when  wood  is  submitted  to  dJBtillatwi 
in  a  manner  similar  to  coal,  the  gas  produced  is  entirely  unfit  for  illnminadoB, 
as  in  addition  to  carbonic  acid,  there  are  only  formed  carbonic  oxide  and  mazsh-gis. 
But  Dr.  Pettenkofer  also  found  that  when  the  vapours  of  tar  and  empyreomatic  oils 
given  off  by  the  carbonisation  of  wood  at  a  comparatively  low  temperature  •!« 
further  heated  by  passing  through  a  red-hot  retort,  a  very  large  quantity  of  hettj 
hydrocarbon  gas  remains  among  the  products,  so  that  then  wood  yields  a  better  gtf 
than  coal. 

While  coals  are  not  perceptibly  acted  upon  by  a  temperature  as  high  as  200%  vooi 
gives  off  combustible  vapours  at  150'';  and  in  order  to  understand  the  process  d 
wood-gas  manufiEusture,  we  must  distinguish  between  the  temperature  at  which  wott^ 
is  carbonised  or  converted  into  charcoal  and  empyrenmatio  vapours,  and  the  toi- 
perature  at  which  these  vapours  are  converted  into  permanent  gas  suited  for  illmi- 
nation.  Coals,  resin,  and  oils  yield  an  illuminating  gas  at  once,  when  submitted  to  d? 
distillation  in  gas  retorts,  because  the  temperature  of  carbonisation  and  of  formatiaii  d 
gas  are  nearly  the  same ;  consequentiy  the  vapours  formed  by  the  dry  distillitiii  d 
these  substances  are  fax  higher  in  illumination  power  thsu  obtains  in  the  case  of  wooi 
Therefore  the  apparatus  in  use  for  coal-  and  oil-gas  preparation  are  not  suited  for  maUsg 
wood-gas.  Some  of  the  substances  rich  in  carbon  and  hydrogen  met  with  in  wood-ttr 
(Stockholm  tar)  boil,  by  themselves,  at  a  higher  temperature  (200*  to  250*)  than  tkit 
at  which  they  are  formed  from  wood;  and  the  illuminating  power  of  wood-gas  is  in 
a  great  measure  due  to  their  conversion,  b}'  a  higher  temperature,  into  permaitfDt 


ARTIFICIAL  LIGHT.  66g 

gAses.    The  manufacture  of  wood-gas,  therefore,  requires  in  the  first  place  a  retort 
in  which  the  wood  is  converted  into  vapour,   and  another  retort  or  generator 
in  which  the  vapours  are  rendered  gaseous.     At  first  the  carbonising  retort,  of 
the  same  shape  as  the  ordinary  coal-gas  retorts,  was  connected  with  a  series  of  iron 
tubes,  which  were  made  red-hot,  and  through  which  the  vapours  given  ofif  by  the  car- 
bonisation of  the  wood,  at  a  temperature  of  250''  to  300^  were  passed  to  be 
converted  into  gas:  but  now  large  retorts  are  .used  for  this  purpose,  about  three 
times  88  large  as  the  carbonisation  retort,  which  holds  60  kilos,  of  wood,  and  there 
is,  therefore,  ample  space  for  the  convq|»ion  of  the  vapours  into  gas.    As  regards  the 
quality  and  quantity  of  gas  obtained  (torn,  difierent  kinds  of  wood,  there  is  no  very 
{preat   difference,  as   may  be  inferired  from  the  under-mentioned  results  of  the 
researches  made  by  W.  Reissig,  who  operated  upon  aspen  wood  (i) ;  linden  wood  (2) ; 
larch  wood  (3) ;  willow  wood  (4) :  fir-tree  wood  (5) ;  and.  white  wood  or  Memel 
timber  (6). 

50  kilos,  (i)  gave  of  purified  gas  592  cubic  feet,  and  9*9  kilos,  of  charcoal. 


50 

f» 

(ay 

620—640 

»> 

,,9—" 

f>            • 

50 

I» 

(3) 

550 

»» 

M  ia-5 

»»           f 

50 

»• 

(4) 

660 

»t 

«>    90 

»>           »i 

50 

»» 

(5) 

648 

»» 

»    95 

»»           »i 

50 

•1 

(6) 

564 

t» 

»,    9'^ 

»»           »• 

That  the  crude  wood-gas  contains  a-  large  quantity  of  carbonic  acid  may  be 
inferred  from  tlie  following  results  of  analysis  by  Pettenkofer,  the  gas  having  been 
made  of  wood  as  much  as  possible  free  from  resin : — 

Heavy  hydrocarbons     6*91 

Marsh-gas  (methyl-hydrogen)      ...  11 '06 

Hydrogen        ^5'^ 

Carbonic  acid 2572 

Carbonic  oxide       40*59 

One  volume  of  the  heavy  hydrocarbons  contained  282  volumes  of  vapour 
of  carbon.  The  carbonic  acid  is  removed  from  the  crude  gas  by  means  of  hydrate 
of  lime.  According  to  Beissig's  researches,  the  composition  of  purified  wood-gas  is 
the  following : — 

I.  2. 

Heavy  hydrocarbons        7*24         7*86 

Hydrogen 3^*84       48*67 

Light  hydrocarbon  gas  (marsh-gas)  ...        35'30        21*17 
Carbonic  oxide 25*62        22*30 

loo'oo      loo'oo      100*00      100*00 

"•  MuiSiiISSl:*^  The  wood,  chiefly  fir-wood,  is  first  dried  for  twenty-four  hours  in 
«  drying  room,  generally  brick- built,  and  heated  by  the  waste  heat  of  the  retort 
furnaces.  The  carbonising  retort  is  filled  with  50  to  60  kilos,  of  wood  and  the  lid 
.  screwed  on;  the  distillation  is  finished  in  i|  hours,  and  after  the  removal  of  the 
carbonic  add  there  is  obtained  about  16  cubic  metres  (nearly  600  cubic  feet)  of  good 
illuminatbg  gas.    In  some  places,  where  wood*gas  is  regularly  made,  it  is  prefiurred 


3- 

4. 

900 

734 

2976 

2960 

20*96 

2402 

40-28 

3904 

\ 


670  CHEMICAL  TECHNOLOGY. 

to  distil  with  the  wood  some  Scotch  boghead  coal  or  Bohemia]^  foliated  coal  {SlaUd 
Icohle). 

wood-OMBunan:  The  construction  of  the  burners  .is  of  great  importance  with  regiid 
to  wood-gas  illumination.  The  sp.  gr.  of  this  gas  amounts  on  an  average  to  07, 
while  that  of  ordinary  coal-gas  scarcely  every  reaches  0*5  ;  the  lighter  the  gas  the 
more  readily  and  rapidly  it  flows  out  and  expands  in  the  air,  and  the  heavier  the 
gas  tlie  more  slowly  and  difficultly  it  issues  and  expands.  A  light  gas  will  not  ob 
issuing  into  the  air  separate  its  particles,  while,  on  the  other  hand,  a  heavy  gas  wiH 
by  exerting  greater  friction,  mix  with  the  air;  in  order  that  this  effort  shall  not 
injure  the  luminosity  or  the  gas,  the  openings  in  wood-gas  burners  must  be  eoa- 
siderably  larger  than  in  coal-gas  burners.  When  wood-gas  is  burnt  with  rather 
strong  pressure  from  coal-gas  burners  calculated  to  consume  70  to  100  htres 
(3  to  4  cubic  feet)  per  hour,  the  flame  is  scarcely  luminous,  while  when  burnt  from 
burners  with  large  openings,  wood-gas  yields  a  light  exceeding  that  of  ooal-gn. 
According  to  the  experiments  made  in  1855  by  Drs.  Liebig  and  Steinhill,  the  iUa* 
minating  power  of  coal-gas  and  wood-gas  used  each  at  4!  cubic  feet  per  hour  wm 
found  to  be : — 

For  coal-gas  =  10*84  normal  wax-candles. 
„   wood-gas  =  irga       „         „ 

so  that  the  average  illuminating  power  of  coal-gas  stands  to  that  of  wood-gas  as  6 :  5* 
The  advantage  of  wood-gas  manufacture  over  that  of  coal-gas  (only  of  oourse  in  locali- 
ties where  wood  is  very  abundant  and  coal  either  not  to  be  had  or  at  great  coat)  i> 
evident  enough,  because,  in  addition  to  less  complicated  apparatus  than  required  ftr 
coal-gas,  the  manufacture  of  wood-gas  yields  far  more  valuable  by-products,  wood  char- 
coal being  the  chief  of  these.  Wood,  moreover,  yields  weight  for  weight  more  gM 
than  coal  in  a  shorter  time  and  of  higher  illuminating  power,  while  the  gas  ia  abso- 
lutely free  from  sulphur  and  ammoniacal  compounds,  so  that  by  the  burning  of  wood- 
gas  no  sulphurous  acid  can  be  formed.  As  the  distillation  of  wood-gas  proeeedf 
mpidly,  one  retort  kept  continuously  in  action  for  twenty-four  hours  will  yidd 
10,000  cubic  feet,  while  for  coal-gas  only  4000  cubic  feet  are  obtained  with  one  reUxt 
in  the  same  time.  On  the  other  hand,  wood-gas  requires  for  purifying  purpoe^a 
very  large  quanti^  of  quick-lime.  The  wood-tar,  about  2  per  cent  of  the  weight  d 
the  dry  wood,  and  the  wood- vinegar — 100  parts  of  wood  yield  0*5  to  0'75  parts  of  drf 
acetate  of  lime — are  usefully  applied ;  the  tar,  however,  is  in  some  localities  bant 
under  the  retorts. 

pwt-OM.  in.  When  peat  is  submitted  to  dry  distillation,  there  is  obtained,  aa  wifli 
coals,  an  aqueous  distillate,  tar,  and  carbonised  peat  or  peat-coke.  Yohl  obtained  I7 
the  dry  distillation  of  an  air- dried  peat,  taken  from  a  high  moorland  in  the  caatflfi 
Zurich,  Switzerland,  from  100  parts : — 

\7ao  ...     •••     ••.     •••     ••.     ...     ...     ...  ^7  0Z3 

jLajT    ...     •».     •••     ...     ...     ...     •••     ...  ^  375 

Aqueous  distillate 52*000 

x^eai-cojEe...     ••*     •••     •••     ...    ...     ...  25  000 

The  products  of  the  dry  distillation  of  peat  are : — 


Fluid  and  solid 
hydrocarbons. 


Peat  oil,  0*820  sp.  gr. 

Heavy  oil  ^ubricating-oil),  0885  sp. gr. 

kl^uraflui. 


ARTIFICIAL  LIGHT. 


671 


Bases. 


Ammonia. 

Ethylamine. 

Picoline. 

Lutidiue. 

Aniline. 

Caespitine. 


Acids. 


r  Carbonic. 

Salphuretted  liydrogen. 
Cyaiihydric. 
Acetic. 
Propionic. 
Butyric. 
Valerianic. 
.Carbolic. 


Gaseous  products. 


Heavy  hydrocarbons. 
Light  hydrocarbons. 
Hydrogen. 
.Carbonic  oxide. 


The  apparatus  in  use  for  making  wood-gas  answers  the  purpose  of  making  peat- 
gns.  W.  Keissig,  who  has  for  a  long  time  been  engaged  in  experimenting  on 
peat-gas  manufacture,  used  a  fat  peat  from  the  neighbourhood  of  Munich,  con- 
taining very  little  ash  and  14  to  15  per  cent  of  water.  On  an  average  i  Bavarian 
cwt  of  this  peat  yields  426  Bavarian  cubic  feet  of  gas ;  134  lbs.  of  this  peat  yield 
337  English  cubic  feet  of  gas.  The  gas  is  evolved  at  first  very  rapidly,  as 
is  also  the  case  with  wood,  but  the  evolution  of  gas  from  peat  decreases  more 
uniformly  and  steadily  than  it  does  from  wood.  Keissig's  experiments  prove  that 
peat-gas  may  be  prepared  of  very  good  quality ;  he  found  the  purified  peat-gas  to 
consist  of: — 

I.  Heavy  hydrocarbons       

Light  hydrocarbon  gas 

xxy ux ugeu  ...     «..      *••     ■•.     ...     .••     .■• 

Carbonic  oxide  •• • 

Carbonic  acid  and  sulphuretted  hydrogen 


The  analysis  of  another  gas,  made  with  a  very  excellent  peat,  gave  the  following 
result: — 

II.  Heavy  hydnxiibonB  {  ^^^^^  =  Jg  |  = 

Light  hydrocarbons ... 

Hydrogen  ... 

Carbonic  oxide ... 

Carbonic  acid  and  sulphuretted  hydrogen 

Nitrogen 


«••     ...     ...     ... 


...     ...    .*•     ...     ...    .*• 


...     .*•     ...     ••■     •*• 


•*•     •••     ...     ...     f*.     »*«     ... 


9-52 

4265 

2750 

2033 

traces 

100*00 

ent  peat,  gave 

1316 

3300 

3518 

1834 

000 

032 

lOO'OO 

wsurOM.  rV.  The  manufacture  of  water-gas  essentially  consists  in  forcing  steam 
through  iron  or  fire-clay  retorts  filled  with  red-hot  charcoal  or  coke.  The  steam  is 
decomposed,  yielding  a  mixture  of  hydrogen,  carbonic  oxide,  and  carbonic  acid  gases, 
with  a  small  quantity  of  marsh-gas.  The  purified  gas,  consisting  essentially  of 
carbonic  oxide  and  hydrogen,  is,  although  not  luminous  when  burnt  by  itself,  suitable 
for  illuminating  purposes  under  the  following  conditions : — i.  By  placing  on  the 
burners  small  platinum  cylinders  which,  by  becoming  white-hot,  yield  a  strong  light 
— Gengembre's  and  Gillard's  plan.  2.  By  impregnating  the  gas  with  vapours  of 
hydrocarbons,  a  more  common  plan,  the  original  idea  being  due  to  Jobard  (1832)  of 
Brussels. 


67i  CHEMICAL  TECHNOLOGY. 

The  determinations  of  the  compositions  of  water-gas  vary  very  nnich.  Jar-qnelim 
and  Gillard  state  that  the  crude  gas  obtained  by  them  is  a  mixture  of  hydrog«i  vak 
carbonic  acid,  which,  after  having  been  purified  by  means  of  lime,  consists  essentialk 
of  hydrogen.  But  it  is  stated  by  others,  and  not  without  good  reason,  that  tiie 
purified  gas  contains  carbonic  oxide  and  hydrogen;  and  Langlois*s  results  agree 
with  this  account.  Tlie  formation  of  i  molecule  of  carbonic  oxide  requires  i  mole- 
cule of  steam,  the  hydrogen  of  which  is  set  free,  C+HaO=CO+Ha.  When  the 
carbonic  oxide  meets  a^ain  with  steam  at  a  higher  temperature,  it,  as  has  been 
experimentally  shown  by  Dr.  Verver,  withdraws  oxygen  from  the  stecun,  fonma^ 
carbonic  acid,  while  some  hydrogen  is  again  set  free :  C0+H20=COa-|-H,.  Only 
when  the  carbonic  acid  is  not  withdrawn  rapidly  enough  from  the  retorts  is  its 
re-conversion  into  carbonic  oxide  by  contact  with  the  red-hot  charcoal  possible^ 

rSSJ2iOm.  ^  ^^®  y®*^  1846,  Gillard  established  at  Passy,  near  Paris,  a  gas- 
work  for  the  purpose  of  manufacturing  hydrogen  by  tlie  decomposition  of  wat^. 
At  first  the  steam  was  decomposed  by  passing  it  through  retorts  filled  with 
ret-hot  iron  wire,  the  idea  being  to  re-convert  the  oxidised  iron  to  the  metallic  state; 
but  as  this  process  did  not  answer,  Gillard  commenced  decomposing  tlie  st^ini  br 
passing  it  tlirough  a  retort  filled  with  red-hot  charcoal  The  cmde  gas  tbas 
obtained  is  readily  freed  from  the  large  quantity  of  carbonic  acid  it  contains,  br 
ciystallised  carbonate  of  soda,  which  is  converted  into  bicarbonate  of  soda.  The  gas 
is  burnt  from  an  Argand  burner  provided  with  numerous  small  holes,  and  the 
flame,  not  luminous  by  itself,  is  surrounded  by  a  net-work  of  moderately  ine 
platinum  wire,  which  on  becoming  white-hot  is  luminous.  In  Paris  this  gas  is 
known  as  platinum-gas  igaz-platine).  It  is  free  from  smell,  bums  without  smoke  or 
soot,  and  for  this  reason  is  prefen*ed  by  gold  and  silversmiths  and  electro-gildefs. 
The  illuminating  power  of  this  gas  exceeds  that  of  coal-gas  in  the  proportioii. 
according  to  Girardin,  of  130  :  127.  The  flame  is  quite  steady,  because  the  Hght- 
.  producing  substance  is  a  solid  body  at  a  white  heat.*  According  to  Dr.  Vervos 
researches  there  are  used  at  Narbonne,  France,  for  the  production  of  i  cubic  metre  of 
this  gas  0*32  kilo,  of  wood -charcoal,  and  for  heating  the  retorts  1*41  kilos,  of  ooals. 

Ottboxetted  wstei^aai.  While  engaged  in  his  experiments  on  the  oil  obtained  by  the 
strong  compression  of  oil-gas,  Faraday  proved  that  if  marsh-gas,  which  bins 
with  a  scarcely  luminous  flame,  is  impregnated  with  this  oil,  it  becomes  a  veir 
luminous  gas.  Lowe  proposed,  in  the  year  1832,  that  common  coal-gas  should 
be  rendered  more  luminous  by  impregnating  it  with  vapours  of  tar-oil  or  petraleua« 
He  also  showed  that  with  the  aid  of  steam  and  red-hot  coke  a  mixture  of  carbocie 
oxide  and  hydrogen  might  be  obtained  and  rendered  luminous  by  impregnation  with 
these  vapours.  Afterwards  Jobard,  at  Brussels,  took  up  the  subject  and  communi- 
cated his  researches  to  the  IVench  gas-engineer  Selligue,  who  having  at  an  earlier 
period  U833)  been  engaged  with  similar  researches,  entered  upon  the  subject  with 
great  energy,  and  employed  carburetted  water-gas  for  illuminating  purposes  on  die 
large  scale.  Selligue  used  the  oil  obtained  from  a  bituminous  shale  for  the  purpose 
of  carburetting  the  watei'-gas,  the  oil  being  obtained  in  the  same  manner  as  such  oil 
is  now  made  from  various  kinds  of  cannel  coal  and  bituminous  shales.  Selligue  s  gis- 
making  apparatus  consisted  of  a  battery  of  three  vertical  retorts  kept  continooosljr 

«  Sohinz  has  lately  published  an  essay  on  this  gas ;  see  Dr.  Wagner^s  **  Jahresberidil 
der  chem.  Technologies'  i86g,  p.  731. 


ARTinCtAh  LtaST.  67^ 

v%d-liot,  two  of  these  retorts  being  filled  with  charcoal  or  coke  of  good  quality 

and  very  free  from  sulphur.    Into  the  first  of  these  retorts,  which  are  connected 

together,  steam  is  introdnced,  forming  with  the  red-hot  charcoal  carbonic  oxide  and 

hydrogen.    This  gaseous  mixture  passing  through  the  second  retort,  also  filled  with 

charcoal,  is  there  depriTed  of  any  carbonic  acid,  which  is  converted  into  carbonio 

oxide.     This  is  the  reverse  of  the  method  of  water-gas  making  now  employed, 

where  the  carbonic  oxide  is  converted  into  carbonic  acid,  to  be  next  removed  from 

tlie  gaseous  mixture  by  means  of  lime.    The  very  hot  mixture  of  hydrogen  and 

carbonic  oxide  ia  next  passed  into  the  third  retort,  which  is  filled  for  two-thirds  of  its 

height  with  iron  chains  kept  red-hot,  while  a  continuous  stream  of  the  oil  of  the 

bituminous  shale  flows  from  a  reservoir  through  a  syphon-pipe  into  this  retort  (to 

every  10,000  litres  of  gas  5  kilos,  of  oil  are  admitted),  and  upon  becoming  decomposed, 

mixes  with  the  carbonic  oxide  and  hydrogen,  forming  a  gaseous  mixture,  which, 

notwithstanding  the  large  quantity  of  carbonic  oxide  contained,  bums  with  a  highly 

luminous  flame,  the  gas  being  at  the  same  time  of  great  durability.    A  gas-furnace 

upon  Selligue's  plan  and  containing  six  retorts  in  two  batteries,  together  of  6  cubic 

metres  capacity,  yielded  in  twenty -four  hours  24,000  to  28,000  hectolitres  (=8  (,768 

to  98.896  English  cubic  feet)  of  excellent  gas,  with  a  consumption  of  1231  kilos,  of 

oil  of  bituminous  shale,  400  kilos,  of  wood-charcoal,  and  16  hectolitres  of  coal  for 

firing  the  retorts. 

Selligue*s  process  has  given  rise  to  the  following  methods : — x.  White*8  hydroearbon 
process,  in  whieh  steam  and  gas  are  made  from  coalB  (originally  resin  was  employed,  but 
cannel  coals  have  been  substituted)  under  the  influence  of  a  jet  of  superheated  steam 
passed  through  a  red-hot  retort.      2.  Leprinee^s  process,   Ocu  mixU  Lfprince,  is  an 
improved  hydrocarbon  process,  the  products  of  the  decomposition  of  steam  and  coke 
being  carried  at  a  suitable  temperature  and  in  the  same  retort  (provided  with  a  partition 
and  thus  divided  into    two  compartments)    over    coals    in  process  of   carbonisation. 
3.  Isoard's  process,  with  superheated  steam    and  coal-tar  mixed.      4.    According    to 
Baldamns  and  Grune's  plan,  steam  and  a  fluid  hydrocarbon  are  decomposed    simul- 
taneously in  the  same  retort.    5.  £irkham*s  plan  and  that  of  others,  the  impregnation  of 
water-gas  with  fluid  hydrocsjrbons,  benzol,  photogen,  petroleum,  naphtha,  £e,    6.  Long- 
bottom's  proposal  to  carburet  air  by  impregnating  it  with  vapours  of  benzol,  or,  according 
to  Wiederholt'splan,  with  petroleum  naphtha,  the  benzoline  as  used  in  sponge-lamps. 
WMte'i  HydnMmrboa      White  in  SO  far  modified  Selligue's  plan  in  causing  water-gas  and 
i*»MMi.  steam  to  be  forced  through  a  retort  in  which  cannel  coal,  boghead,  or 

resin  are  submitted  to  distillation.  White's  process,  as  yet  rarely  employed,  came  under 
sotioe  through  the  researches  which  Dr.  Frankland  instituted  at  Clarke  and  Go.'s  gas- 
works at  Ancoats,  near  Manchester. 

Dr.  Frankland  found  the  gas  made  by  White's  process  to  contain  about  15  per  cent  of 
carbonic  oxide,  no  carbonio  acid,  and  some  45  per  cent  of  hydrogen.  This  increase  of 
hydrogen,  without  an  equivalent  increase  of  carbonic  oxide,  can  oxdy  be  explained  by  the 
action  of  the  steam  upon  the  marsh-gas  evolved  in  the  retort  filled  with  cannel  coal, 
probably  according  to  the  following  formula : — 

Marsh-gas,  CH4 1      .  « >  ( Carbonio  oxide,  CO. 

Steam,  HaO        f  ^®**  i  Hydrogen,  3H2. 

The  composition  of  the  gas,  made  with  and  without  water-gas,  was  as  follows : — 

Gas  from  Boghead  coal : — 

Without  With 

water-gas.  water-gas. 

Heavy  hydrocarbons      24*50  14*12 

Marsh-gas 58*38  22*25 

Hydrogen 10*54  45'5i 

Carbonic  oxide 6*58  i4'34 

Carbonic  acid —  3*78 

Oxygen  and  nitrogen      —  — 

XOO'OO  XOO'OO 

3* 


674  CHEMICAL  TECHNOLOGY. 

The  advantages  of  White's  hydrocarbon  process  are  not  only  the  inereace  of  hydroga 
and  decrease  of  carbonic  oxide  and  marsh-gas  as  met  with  in  ordinaiy  ooAl-gas,  bni  tn  %o 
be  found  in  the  mechanical  action  of  the  products  of  the  decomposing  steam  by  canyiBg 
off  yeiy  rapidly  the  heavy  hydrocarbons  from  the  retort,  so  that  these  are  withdiavB  m. 
time  from  the  decomposing  influence  of  high  temperature,  thereby  lessening  the  fanaa- 
tion  of  tar.  Dr.  Frankland  summarises  the  results  of  this  process  as  follows : — a.  It  oc 
be  employed  without  great  expense  in  any  gas-work.  6.  The  quantity  of  gas  ykiiBi 
increases  from  46  to  ago  per  cent.  c.  The  iUuminating  power  increases  from  14  to  loS  fe 
cent.  d.  Less  tar  is  made,  a  portion  being  oonyerted  into  gas.  e.  The  heat  and  fcma- 
tion  of  carbonic  acid  accompanying  the  combustion  is  much  less,  as  this  gas  eoaUici 
more  hydrogen  and  less  carbon. 

LepriDM'ti  wat«r-aM.  This  Is  Only  a  modification  of  White's  proeesfl,  oonsisting  ckw^ 
in  the  use  of  retorts  divided  by  means  of  horizontal  partitions  into  three  rooms  or 
chambers,  in  which  the  two  phases  of  the  process,  viz.,  the  partial  decomposition  of  walEr 
by  means  of  coke  or  charcoal,  and  the  carburation  of  the  gas  by  means  of  the  Tokbfe 
products  of  the  dry  distillation  of  gas-coals,  are  carried  on  simultaneously.  The  Gtu  mute 
Leprince  is  used  in  the  broad-cloth  factory  of  Simonis  at  Yerviers,  and  at  the  Tidlb 
Montague  zinc-works,  both  in  Belgium,  also  at  Maestricht  and  some  places  near  JLnik  1m^ 

isoard'i  ou.  In  this  process  tar  is  used  instead  of  charcoal  or  coke  for  the  poxpom  d 
decomposing  the  steam. 

Baidamns and onmeB  According  to  this  plan  the  decomposition  of  steam  and  of  the  fa;^ 
om.  carbons  is  carried  on  simultaneously  in  the  same  vessel,  so  that  tbs 

hydrogen  contained  in  the  steam  is  not  evolved  in  free  state,  but  in  eombinatkm  «iik 
carbon  as  a  Ught-giving  hydrocarbon.  The  gas-making  material,  brown  ooal,  peal, 
bituminous  shale,  <&c.,  is  fully  utUised  without  any  by-products,  for  the  tar  is  entn^ 
converted  into  gas,  forming  with  the  hydrogen  of  the  water  a  real  hydrocarbon. 

carbnretted  Oas.  The  process  proposed  by  Kirkham  and  several  others  simply  oonsists  is 
the  impregnation  of  water-gas  with  the  vapours  of  fluid  hydrocarbons,  boizol,  phote- 
gen,  petroleum,  &c.  This  impregnation  may  take  place  at  the  works  where  the  gas  is 
made,  but  better  where  the  gas  is  consumed,  just  before  issuing  from  the  bnmers.  Net- 
withstanding  that  a  great  many  apparatus  have  been  contrived  for  the  purpose  of  eaite- 
retting  water-gas  and  ordinary  coal-gas,  the  process  has  never  answered  yerj  wdl. 
because  it  is  difficult  to  find  suitable  materials  for  carburetting,  and  because  enoneoes 
calculations  have  been  made  in  respect  of  the  quantity  of  carburetting  materials  requind 
to  render  a  non-luminous  gas  luminous.  If,  for  instance,  benzol  (CsHe)  be  the  hydro- 
carbon to  be  used  for  carburetting  purposes, 

1000  cubic  feet  of  gas  require  I  **  jf^*  ^11!  ^^™^'  \  benzol. 

The  improvement  of  coal-gas  by  impregnating  it  with  the  vapours  of  some  roIatQe  hydiv- 
carbon  has  been  frequently  suggested  and  practically  tried  in  England ;  but,  alttkoofik 
various  apparatus  have  been  contrived  for  this  purpose,  such  apparatus  being  geaenl^ 
fixed  to  the  outlet-pipe  of  the  house-meters,  the  results  have  not  been  so  satisfactoiy  as  ts 
lead  to  a  general  introduction  of  these  so-called  carburetters.  Among  other  reasoou  vsf 
these  appliances  have  been  discarded,  is  the  fact  that  the  gas,  especially  in  Xiondan,  eoa- 
tains  sulphuretted  hydrocarbon  compounds  in  very  small  quantity,  which,  by  beeomk; 
dissolved  in  the  hydrocarbon  used  for  impregnating  the  gas,  accumulate  in'^the  eeibm' 
retter,  and  are,  when  fresh  carburetting  oil  is  added,  carried  on  to  the  burners  and  escape 
partly  in  the  state  of  vapour,  causing  a  very  foul  atmosphere  in  the  rooms  where  the  pi 
is  burnt. 

AiT-oaa.  Longbottom  suggested  to  free  air  from  carbonic  acid  and  moisture,  and  tte 
to  impregnate  it  with  the  vapours  of  very  volatile  fluid-hydrocarbons,  such  as  benzine  aai 
benzoline.  Air  can  be  used  as  an  illuminating  gas  in  this  way,  but  it  requires  buiwci 
with  wide  openings  and  a  low  pressure,  because  if  the  current  of  the  gas  he  too  rapid  tbe 
flame  is  cooled  too  much  and  readily  extinguished.  Apparatus  for  preparing 
been  devised  and  constructed  by  Marcus,  Mille,  Methei,  and  others.* 

ouoat.  B«dn-Ga«.      Y.  The  fatty,  or  so-called  fixed  oils,  are  among  the  best  gas 

materials,  yielding  a  very  pure  gas  and  of  high  illominating  power.    This  ioSkm 

from  their  composition : — Lefort  found  the  formula  of  rape-seed  oil  to  be  CioH|gO^: 

olive  oil  and  poppy-seed  oil,    GisH^^Os;    linseed  oil,  Ci^HasO^i    hemp-aeed  oL 

CiiHazOa-    The  fatty  oils  yield  by  dry  distillation  chiefly  elayl-gas  or  a  mixtnie  d 

*  See  *'  Jahresbericht  der  chem.  Technologic,'*  1866,  p.  701 ;  x868,  pp.  763  and  765. 


ARTIFICIAL  LIGHT.  675 

hydrogen  and  marsh-gas  with  the  vapours  of  fluid  hydrocarbons,  tlie  illuminating 
power  of  which  is  equal  to  that  of  elayl-gas.     As  oils  yield  further  only  a  small 
quantity  of  carbonic  acid  gas  and  no  sulphuretted  hydrogen,  oil-gas  does  not  require 
any  purifying,  and  hence  the  apparatus  may  be  very  simple ;  while,  owing  to  the  high 
illuminating  power,  smaller  gas-holders,  smaller  pipes,  and  burners  of  different  con- 
struction are  required.    But  notwithstanding  all  these  advantages,  oil-gas  is  a  thing 
of  the  past.    The  Binnenhof,  at  the  Hague,  with  some  of  the  adjacent  public  build- 
ings, was  lighted  with  oil- gas  until  within  some  ten  or  twelve  years,  when  the 
apparatus  requiring  renewal  was  removed,  and  coal-gas,  as  in  the  other  parts  of  the 
town,  substituted.     The  sp.  gr.  of  oil-gas  amounts  on .  an  average  to  076  and  0*90, 
but  may  be  as  high  as  I'l.    Half  a  kilo,  of  oil  yields  22  to  26  cubic  feet  of  gas,  equal 
to  90  to  96  per  cent. 

OMfromSnint.  By  this  WO  Understand  a  gas  prepared  from  the  fatty  materials 
present  in  the  soap-suds  used  in  washing  raw  wool  and  spun-yams.  The  water 
containing  the  suint  and  soap-suds  is  run  into  cisterns  and  is  there  mixed  with  milk 
of  lime  and  left  to  stand  for  twelve  liours.  A  thin  precipitate  is  formed,  which,  after 
the  supernatant  clear  water  has  been  run  off,  is  put  upon  coarse  canvas  for  the 
purpose  of  draining  off  any  impurities,  sand,  hair,  &c.,  while  the  mass  which  runs 
through  the  filter  is  put  intd  a  tank,  in  which  it  forms  after  six  to  eight  days  a  pasty 
mass,  which  having  been  dug  out  and  moulded  into  bricks,  is  dried  in  open  air. 
At  Rheims  the  first  wash-water  of  tlie  wool  is  used  for  making  both  gas  and  potash, 
because  the  water  contains  no  soap  and  only  suintate  of  potash  (see  p.  132). 
Havrez,  at  Verviers,  has  recently  'proposed  to  employ  suint,  which,  by-the-bye,  is 
very  rich  in  nitrogen,  for  the  purpose  of  making  ferrocyanide  of  potassium. 

The  dried  brick-shaped  lumps  are  submitted  to  distillation,  yielding  a  gas  which 
does  not  require  purification,  and  which  possesses  an  illuminating  power  three  times 
that  of  good  coal-gas.  The  wash- water  of  a  wool  spinning-mill  with  20,000  spindles 
yields  daily,  when  treated  as  described,  about  500  kilos,  of  dried  suinter,  as  the  sub- 
stance is  technically  termed,  z  kilo,  of  this  substance  yields  210  litres  of  gas. 
AnnuaUy  about  150,000  kilos,  of  suinter  are  obtained,  and  this  quantity  will  yield 
31,500,000  litres  =1,112,485  cubic  feet  of  gas.  Every  burner  consuming  35  litres 
of  gas  per  hour,  and  taking  the  time  of  burning  at  1200  hours,  the  quantity  of  gas 
will  suffice  for  750  burners,  and  as  a  spinning-mill  of  20,000  spindles  only  requires 
500  burners,  there  is  an  excess  of  gas  supply  available  for  250  other  burners,  or  the 
owner  may  dispose  of  5000  kilos,  of  suinter,  which  is  valued  at  Augsburg  at  about 
3s.  per  50  kilos.,  and  at  about  4s.  at  Mulhouse. 
om  from  PBtrotemn      VI.  The  so-callcd  posidouiau  schist  of  tlie  lias  formation,  met 

00.  or  Oil  txom  ' 

Bitominoiu  shaira.  with  ucaT  Rcutlingeu,  in  Wiirtemberg,  yields  by  dry  distillation 
about  3  per  cent  of  tar,  which  on  being  submitted  to  distillation,  yields  an  oil 
which  cannot  be  burned  in  lamps  owing  to  its  containing  sulphur;  but  tlie  oil  is  an 
excellent  material  for  gas  manufacture.  According  to  Haas,  i  cwt.  (50  kilos.)  of  the 
oil,  valued  at  i6s.,  yields  1300  English  cubic  feet  of  gas,  so  that  1000  cubic  feet 
inclusive  of  fuel  (i^t  klafter  of  wood ;  the  klafter  is  a  cubic  measure  by  which  wood 
is  sold,  and  is  =108  cubic  feet)  and  labour  cost  i6s.,  a  low  price  considering  the  high 
illuminating  power  of  the  gas.  The  gas,  according  to  W.  Reissig*s  researches  (1862) 
was  found  to  consist  of: — 


676  CHEMICAL  TECHNOLOGY, 

Heavy  hydrocarbons       25*30 

Marsh-gas  ...     ..*     ...     •••     ••■  64*80 

Carbonic  oxide 6*65 

Hydrogen 3*^5 

Carbonic  acid 0'20 

Oxygen  and  nitrogen       traces 

lOO'OO 

According  to  experiments  made  at  Stnttgart,  the  Olnminating  power  of 
2*5  to  3'5  times  that  of  coal-g^. 

FitioifliiiB-OM.      In  America  and  on  the  Continent  of  Europe  petroleum  is 
for  the  pnrpose  of  gas-making,  being  either  converted  into  gas  or  used  to  carboiaie 
water-gas. 

According  to  the  method  of  Thompson  and  Hind  (1862)  the  petroleum  is  canTertai 
into  gas  by  causing  it  to  pass  through  a  red-hot  retort,  which,  in  order  to  increase 
the  contact  surface,  is  filled  with  lumps  of  fire-brick  or  is  fitted  with  a  series  of  tnf  • 
like  iron  plates,  and  the  gas  so  obtained  mixed  with  that  made  by  passing  steam  oiv 
red-hot  charcoal.  The  crude  gaseous  mixture  is  washed  by  causing  it  to  babUe 
through  hydrochloric  acid  and  then  through  a  series  of  "purifying  apparatus,  so  thit 
the  gas  collected  in  the  gas-holder  is  devoid  of  smell.  The  arrangement  of  the 
retort  used  in  this  process  is  the  following :—  The  retort  is  placed  hoiizontaUy;  to  Uk 
Hd  is  fitted  a  hollow  cylinder  which  is  filled  with  coke  or  charooaL  In  the  spaee 
between  this  cylinder  and  the  sides  of  the  retort*  is  placed  a  serpentine  iron  pkHi^ 
Through  the  lid  of  the  retort  two  tubes  are  carried ;  one  of  these,  conunnnicati^g 
with  the  serpentine  iron  plate,  is  destined  for  the  introduction  of  the  petroleam  oO, 
while  the  other  is  used  for  passing  in  the  steam,  and  communicates  with  die  eylinder 
filled  with  coke  or  charcoal.  At  the  other  end  of  the  retort  a  tube  is  fitted  lor 
carrying  the  gas  to  the  purifier.  When  the  petroleum  is  converted  into  gas 
water-gas,  i  cwt.  of  Pennsylvanian  oil  yields  1590  cubic  feet  of  gas,  which, 
purified,  consists,  according  to  Bolley,  of: — 


Heavy  hydrocarbons 
Light  hydrocarbons 
Hydrogen 


...     ... 


...     ... 


...     ••• 


I. 

IL 

316 

334 

457 

40*0 

327 

26*0 

100*0  lOO'O 

H.  Hirzell  prepares  gas  from  the  residues  of  the  refining  of  petroleum,  whidi 
less  volatile,  as  well  as  from  petroleum  itself.  Hirzel's  apparatus,  already  laigelj 
used  in  Germany,  Austria,  Hussia,  and  elsewhere,  is  especially  adapted  for  t^ 
purpose  of  making  gas  for  railway -stations,  barracks,  factories,  hotels,  and  isolated 
country  seats ;  its  mode  of  action  will  be  readily  understood  with  the  aid  of  Fig.  30a 
D  is  a  wrought-iron  vessel  containing  petroleum  or  the  residues  of  the  refining. 
This  vessel  is  fitted  with  a  suction-  and  force-pump,  e,  the  piston  of  which  can  be 
filled  with  petroleum  by  winding  up  tiie  clockwork  with  which  it  is  connected.  As 
soon  as  the  retort  is  red-hot,  weights  are  put  on  the  piston,  after  which  the  pendolira 
of  the  clockwork  is  set  in  motion  and  the  rope  unreeled,  allowing  the  piston  to  eiok 
slowly  into  the  pump-body,  thus  forcing  the  petroleum  through  i  uniformly  into  the 
retort  ▲.    The  petroleum  is  converted  into  gas,  and  this  is  carried  throng  the  tabe  i 


ABTIFICIAL  LIOHT. 


into  the  receiTer  b  ftnd  thence 
thro  agh  the  condeneer  c  irhichia 
tilled  with  pieces  of  bnck  mto 
R  gns-holder  Id  B  the  pipe  dipe 
under  the  sar&UM  of  the  petro 
lenm,  bo  thkt  a  hjdraiiho  Talve 
ia  provided,  preventing  the  gas 
from  retonung  to  the  retort  In 
order  to  keep  this  colnmn  of 
petrolenm  at  the  suns  height, 
there  ig  fitted  to  e  the  U  shaped 
tube  e,  hy  meana  of  whieh  any 
Bnperflnoiu  oil  entering  e  iB  nin 
off  into  a  puL  The  tnbe  b 
fitted  to  the  gas  tube  <I  ia  br 
means  of  a  pipe  conneoted  with 
ft  water-preasnre  gauge  by  the 
aid  of  which  the  pressnre  in  ttie 
retort  dunng  the  operation  can 
be  ascertained  this  pressare 
UDOnntsnsiiaUf  to  8  to  13  centims 
of  water.  The  tid  «  of  the  con 
denser,  c  is  kept  gas  tight  b;  the 
rim  dipping  m  water  poured  into 
an  annular  space.  The  working 
of  this  apparatus  is  ybtj  simple. 
The  clock-motion  is  mainttuned 
for  an  honr,  and  in  that  time 
about  200  cubio  feet  of  gas  are 
made.  If  hj  anj  chance  the 
tabes  are  choked,  the  manometer 
will  indicate  the  accident.  When 
in  regular  use  the  apparatus 
ehonld  be  cleaned  once  in  five  or 
six  weeks,  and  after  everj  twelve 
distiUatioiia  the  retort  should  be 
opened  and  the  crust  of  coke 
picked  off  with  a  sharp  iron  bar. 
Petrolenm-gas  is  the  best  that 
can  be  made,  and  it  has  the  ad- 
vantage that  even  nnder  strong 
pressure  and  intense  cold  it  does 
sot  deposit  tarr;  matter,  noi 
does  it  lose  any  of  its  iUnmi- 
natingpower.  It  is  absolutely  free 
from  ammoniacal  and  sulphur 
compounds  and  frum  carbonic 
add.    The  sp.  gr.  of  petroleum- 


678  CHEMICAL  TECHNOLOGY. 

gas  is  0*69,  and  it  consists  chiefly  of  acetylen  (CsH^).  It  is  bnmt  from  bonicis 
which  consume  per  hour  only  one-qnarter  of  a  cubic  foot  to  a  maiciTmiTn  of  2  culce 
feet.  SCO  cubic  feet  of  this  gas  are  equivalent  to  1000  cubic  feet  of  coal-gas.  At  tke 
suggestion  of  L.  Ramdohr  (1866),  the  sodium  carbolate  (creosote  aoda),  which  is 
obtained  in  large  quantities  in  the  paraffin  and  mineral-oil  works,  is  used  farg*a- 
making  under  the  name  of  creosole-gas. 

bwIii-gm.  VII.  When  the  substance  known  as  Venice  turpentine,  a  mixture  of  oil 
of  turpentine  and  resinous  matter,  is  submitted  to  distillation  with  wat^r,  tbeit 
remains  colophonium,  or  commonly  resin,  which  essentially  consists  of  sylvie  aai 
pinic  acids,  these  being  isomeric  and  corresponding  to  the  formtda  CaoHjoOs. 
Before  the  late  American  war  colophonium  was  imported  in  very  large  qnantitj  into 
Europe,  and  was  used  in  England  as  well  as  on  the  Continent  for  the  purpose  of  gis 
manufacture. 

When  decomposed  under  the  influence  of  heat  colophonium  yields  an  oily  QxaiL 
so-called  resin  oil,  which,  when  submitted  to  red-heat,  is  converted  into  gB&  This 
oil  is  very  complex,  and  contains  bodies  which  are  volatilised  below  red-heat,  aa 
inconvenience  in  gas-making,  because  these  compounds  as  soon  as  formed  beoone 
Tolatilised  instead  of  being  converted  into  gas.  Consequently  it  is  necessary  to  pass 
the  first  products  of  the  decomposition  through  several  retorts  in  order  to  oonvext 
them  completely  into  gas,  tliereby  complicating  the  apparatus  and  increasing  the  cost 
of  fuel.  Another  difficulty  in  the  making  of  resin-gas  is  occasioned  by  the  fitct  that 
colophonium  is  a  solid  substance  which,  in  order  to  be  fitted  for  gas-making,  so  as  to 
supply  the  retorts  uniformly  and  constantly,  has  to  be  first  liquefied.  This  has  bees 
in  some  instances  effected  by  dissolving  the  resin  either  in  oil  of  turpentine  or  ia 
resin  oil,  while  in  other  instances  the  resin  has  been  first  molten,  and  then  caused  to 
flow  into  the  retorts  filled  with  coke  or  lumps  of  fire-brick  to  increase  the  snr&ee. 
The  hot  gas  from  the  retorts  is  washed  w^ith  cold  water  in  order  to  free  the  gas  froa 
any  adhering  resin  oil.  It  is  next  purified  from  the  cai'bonic  acid  it  contains  (on  ai 
average  about  8  per  cent)  by  passing  it  through  a  solution  of  caustic  soda.  100  Iba 
of  resin  yield  about  1300  English  cubic  feet  of  gas,  a  quantity  which  is  greatly 
increased  when  the  White-Frankland  hydrocarbon  process  is  employed.  This 
process,  however,  is  obsolete  in  consequence  of  the  very  fluctuating  supply  of  reaia 
since  the  last  American  war  and  the  greatly  increased  price  of  that  article. 

The  lime-light,  Tessi6  du  Motay's  oxyhydrogen  light,  the  magnesium  light,  and  the 
electric  light  have  to  be  considered  as  appendices  to  the  illuminating  and  aitifidsl 
hght  producing  materials. 

Lime-Light.  Whcu  a  mixturc  of  two  volumes  of  hydrogen  and  one  volume  of  oxygen 
is  ignited,  each  gas  being  supplied  from  a  separate  gas-holder,  we  obtain  what  is 
known  as  the  oxyhydrogen  blowpipe,  the  heat  evolved  being  sufiicient  to  fuse 
platinum.  The  flame  of  this  mixture  is  not  luminous,  but  if  it  is  made  to  impirge 
against  a  piece  of  quick-lime,  the  latter  being  rendered  inter  sely  white-hot,  emits  a 
light  of  very  great  intensity.  For  the  general  purposes  oi  artificial  illumination  the 
lime-light  is  not  suitable,  arising  partly  from  the  high  price  of  oxygen ;  but  for 
scientific  purposes  and  for  signals,  the  lime-light,  also  known  as  tlie  Drummond-,  or 
sideral-light,  is  very  manageable.  According  to  the  "  Journal  of  Gas  Lighting" 
(1869)  the  authorities  of  the  British  War  Department  have  arranged  to  use  the  lime- 
light in  hulitary  barracks  and  cavalry  stables,  having  instituted  a  series  «i 
experiments  in  the  yard  of  tlie  Queen's  Barracks.     The  illuminating  apparatus  and 


ARTIFICIAL  LIGHT.  679 

reflecting^mirror  were  placed  on  a  teraporarily-erected  wooden  frame- work,  18  feet 
bigh,  and  when  the  lime  was  ignited  the  yard  was  lighted  up  so  strongly,  that  at 
100  yards  distance  from  the  light  the  smallest  type  could  be  read.  A  smaller  light 
surrounded  by  a  glass  globe  was  tried,  and  found  to  be  so  efficient,  that  at  30  yards 
distance  from  the  light  a  pin  could  be  distinguished  lying  on  the  pavement.  The 
light-appari&tus  tried  in  one  of  the  barrack-rooms  was  still  smaller,  but  lighted  the 
room  very  brilliantly. 

'•"  of  mlJSSSi"!*''^      ^^^  ^^^  y®*"  Tessi6  du  Mota/s  method  of  illumination  has 
been  often  before  the  public.    During  the  latter  part  of  1871  and  the  earlier  months 
of  this  year,  this  method  has  made  considerable  progress  in  improvement,  and  is 
nsed  in  some  parts  of  Paris  and  Vienna,  and  has  been  tried  at  the  Crystal  Palace. 
The  gas-mixture  used  is  either  water-gas — a  mixture  of  hydrogen  and  carbonic 
oxide — or  hydrogen  only,  or  also  coal-gas,  burnt  with  a  regulated  supply  of  oxygen 
instead  of  air.    The  oxygen  is  obtained  by  the  decomposition  of  the  vapours  of 
sulphuric  acid  or  from  manganate  of  sodium,  or  by  the  decomposition  of  oxychloride 
of  copper.    The  flame  of  the  oxyhydrogen  gas  is  made  to  play  against  a  small 
cylindrical  piece  of  magnesia  or  zirconia ;  but  more  recently  (1869)  Tessi6  du  Motay 
has  somewhat  altered  his  method,  by  causing  the  oxygen  to  become  saturated  with 
a  solution  of  naphthaline  in  petroleum.    It  appears  that  the  latest  and  most  practi- 
cally available  method  is  the  feeding  of  good  coal-gas  with  oxygen,  a  very  excellent 
light  being  produced. 

Mr.  Crookes  has  found  a  supply  of  good  coal-gas  best  adapted  to  the  oxy-hydrogen 
flame,  the  oxygen  being  supplied  from  a  burner  quite  separate  from  the  hydrogen  burner, 
and  having  a  broad  slit  from  which  the  gas  issues.  The  oxygen  should  be  supplied  at  a 
steady  but  full  pressure.  The  material  upon  which  the  flame  impinges  may,  with  advan- 
tage, be  of  dolomite.  Under  these  conditions,  Mr.  Crookes  has  always  found  the  lime- 
light to  work  BatisfactorUy.  The  dolomite  does  not  crack  nor  splinter,  as  is  the  case  with 
quick-lime  or  magnesia.  There  are  also  the  advantages  in  employing  separate  burners,  of 
decreased  expense  of  apparatus,  and  of  perfect  safety. 

MM.  Deville  and  Gemez  proposed  some  time  since  to  make  a  series  of  experiments  to 
ascertain,  in  a  chamber  containing  compressed  air,  whether  the  tension  of  steam  (which  is 
said  to  be  complementary  to  the  tension  of  dissociation)  in  the  flame  of  the  oxyhydrogen 
blowpipe  is  augmented  by  exterior  pressure,  and  if  the  augmentation  extends  to  the  tem- 
perature  of  the  flame.    In  a  cylindrical  chamber  of  forty  metres  contents,  and  the  sides 
of  which  have  been  proved  to  eleven  atmospheres,  is  arranged  the  necessary  apparatus. 
The  operators  enter  the  cylinder,  and  the  air  is  compressed  by  means  of  a  steam-pump, 
when  the  experiments  are  proceeded  with  as  in  the  open  air.    The  endeavour  has  at  pre- 
sent been  confined  to  ascertaining  the  condition  of  various  substances  at  the  moment  they 
combine  in  homogeneous  flames,  and  the  resulting  temperatures.     The  homogeneous 
flame  employed  is  that  of  carbonic  oxide  and  oxygen.    With  this  flame  and  a  pressure  of 
1*7  atmospheres  platinum  melts,  flying  off  in  sparks  with  a  facility  it  never  exhibits 
in  air ;  it  melts  in  those  portions  of  the  flame  which  in  the  air  would  only  heat  it  to  red- 
ness.    We  must  then  deduce  that  the  temperature  of  these  flames  augments  with 
the  pressure  they  support,  and,  consequently,  the  quantities  of  matter  which  combine 
are  greater,   and  the  dissociation    diminished.     Dr.   Frankland  has  shown  that  the 
brilliancy  of  the  flame  of  hydrogen  gas  increases  considerably  with  the  pressure,  so  that 
with  a  pressure  of  twenty  atmospheres  it  surpasses  that  of  a  normal  candle.    Similarly 
when  a  mixture  of  oxygen  and  hydrogen  is  ignited  in  an  eudiometer  the  flame  is  intense, 
while  in  open  air  it  is  scarcely  visible.    M.  Deville  thinks  that  if  the  quantity  of  heat 
disengaged  by  a  sabstance  burning  with  brilliancy  be  measured,  the  result  would  not  be 
the  same  in  operating  with  an  opaque  calorimeter  as  with  one  which  transmits  the  Ught 
and  chemical  rays.    This  remark  when  worked  out  will  probably  produce  results  of  tech- 
nical interest. 

Macnaduin  Light.  The  vory  intcuse  light  which  is  produced  by  the  burning  of  magne- 
sium (see  p.  1 14)  has  been  of  late  frequently  employed  for  photographing  purposes. 
Magnesium  lamps — as  exhibited  in  1867  at  the  International  Exhibition,  at  Paris — 


G8o  CHEMICAL  TECHNOLOGY. 

are  arranged  for  the  use  of  magnesiiim  wire  or  magneainm  dmt,  wlule  in 
isBtance  a  spirit-flame  Is  employed  to  ensure  the  continnity  of  combiutian.  Li  Ike 
lamps  with  wire,  this  is  pulled  forward  by  the  aid  of  clockwork ;  while  in  the  knfs 
burning  the  dust,  this,  mixed  with  very  dry  and  fine  sand  (one-third  magneonm  wok 
two-thirds  sand),  in  order  to  ensure  to  the  magnesium  particles  a  sufficient  aooe«  «f 
air,  is,  on  opening  a  stop-cock,  supplied  from  a  reservoir.  The  magnesinm  li^  m 
used  on  a  large  scale  in  the  Abyssinian  war,  several  cwts.  of  magnesiam  lusnag 
been  supplied  by  Mr.  Mellor,  the  director  of  the  Magnesium  Metal  Company,  nt 
Manchester. 

outiuuB  ucht.  Under  this  name  is  known  in  England  a  kind  of  flash-fight,  obtaiBei 
by  blowing  a  mixture  of  pulverised  resin  and  magnesium  dust  through  the  flame  of 
a  spirit-lamp.    This  flash-light  is  used  for  military  signals. 

Eketxk  Light.  Although  the  electric  light  has  not  been  generally  employed  Tt 
deserves  a  lengthy  notice.  As  is  well  known,  the  discharge  of  an  electric  spark,  er 
a  continuous  voltaic  or  magneto-electric  current,  is  capable  of  producing  in  pieees  of 
graphite  an  intense  light ;  and  when  this  is  obtained  by  suitably  constructed  apparstm, 
it  may  be  rendered  available  for  practical  purposes.  More  recently  I^:0fe8Bor 
Jacobi  has,  with  the  assistance  of  M.  Argeraud,  of  Paris,  made  a  series  of  expezi- 
ments  on  street  lighting  with  the  electric  light.  Upon  the  tower  of  the  Admirahr 
buildings  at  St.  Petersburg,  an  electric  light  apparatus  was  placed,  and  with  it  three 
of  the  largest  streets  of  the  city,  viz.  Newsky  Prospect,  Erbsen  Strasse,  and  Wos- 
nesensky  Prospect,  were  illuminated  at  night  from  seven  until  ten  o'clock.  The 
light  was  intense,  and  the  very  clear  sky  appeared  as  by  sunlight,  while  the  gmdights 
became  lurid.  The  batteiy  employed  was  a  carbon  battery  of  185  cells.  In  i854« 
the  works  for  the  construction  of  the  Napoleon  docks,  at  Rouen,  were  for  aevezal 
nights  illuminated  with  the  electric  light  for  three  to  four  hours  consecatively ; 
800  men  were  at  work,  and  could  continue  their  labour  at  a  distance  of  100 
from  the  source  of  light.  A  Bunsen  battery  of  large  size  with  100  ceDs 
used.  This  light  was  very  cheap,  the  cost  per  man  being  about  three  fiuthings; 
while  the  labour  could  proceed  as  in  daylight.  Several  lighthouses,  among  them  the 
North  Foreland  on  the  Kentish  coast,  and  also  that  of  Cape  la  H&ve  near  Havre, 
have  been  fitted  with  apparatus  for  the  electric  light.  This  light  is  also  nsed  in 
many  cases  in  dissolving  views,  and  for  the  illumination  of  pleasure  gardens  at 
London,  Paris,  Berlin;  and  permanently  for  ligl^ting  the  slate  quarries  situated  near 
Angers,  France.  The  electric  light  has  been  tried  for  submarine  illumination  with 
success,  and  also  for  photographing  purposes.  Colonel  von  Weyde  invented  a 
submarine  electric  illuminating  apparatus,  used  by  the  French  men-of-war  in  the 
late  conflict  between  France  and  Germany.  In  Spain,  in  1862  and  1863,  the  eleetrio 
light  was  frequently  employed  during  the  night  in  the  construction  of  railways.  The 
magneto-electric  apparatus  invented  by  Dr.  Siemens  (1867)  is  of  great  importaiioe, 
as  proved  by  the  experiments  made  at  Burlington  House.  By  means  of  this  w»«^^wmi 
it  becomes  possible  to  obtain  electric  currents  at  a  cheap  rate,  of  enormous  power, 
and  especially  adapted  for  lighthouses. 

By  the  exercise  of  great  ingenuity,  the  difficulties  attending  the  maintenance  of  the 
oarbon  points  at  an  equal  distance  have  been  oyercome.  The  lamps  in  which  tMa  recnlk 
is  effected  are,  however,  more  or  less  complicated,  expensive,  and  liable  to  get  oat  of 
.)rder.  The  electric  lamps  of  Foacault,  Serrin,  and  Bubosoq,  described  admirabty  in 
Or.  Schellen'B  "  Bpeotmm  Analysis,"  and  engravings  of  which  are  to  be  met  with  in  moil 
treatises  on  physios,  are  delieate  pieces  of  mechanism  peculiarly  unsuited  to  the 


ARTIFICIAL  LIGHT.  68i 

laandHng  to  which  apparatus  in  use  for  technical  or  signalling  purposes  mnst  be  sub- 
mitted. The  electric  lamp  devised  by  Mr.  Browning  is  simple  in«cou8tniotion,  bat  even 
tills  requires  more  attention  than  could  be  bestowed  npon  the  source  of  light  for  general 
purposes. 

Tlie  purity  of  the  carbon  points  has  much  to  do  with  the  intensity  of  the  light 
emitted  by  batteries  of  the  same  strength;  while  their  distance  from  each  other  is  also  of 
conseqaence.    50  or  60  Bunsen's  elements  will  yield  a  light  equal  to  that  of  400  to  1000 
stearine  candles,  according  to  the  purity  of  the  carbon  points.    Taking  the  BuoHght  at 
noon  on  an  August  day  to  be  represented  by  1000,  Foucault  and  Fizeau  have  found  the 
ehemieal  power  of  the  light  obtained,  under  the  best  conditions,  from  46  Bunsen's 
cells,  expressed  by  the  number  235.    Despretz  states  that  the  light  from  100  Bunsen 
elenients  produces  much  discomfort  to  the  eyes,  while  that  from  600  elements,  eyen  at  a 
glance,   is  sufficiently  intense  to  cause  considerable  injury.    But  the  duration  of  the 
electric  light  as  obtained  from  battery  power  is  not  continuous.    Whether  from  polarisa- 
tions in  the  battery  or  from  many  other  causes,  the  light  sometimes  fails  for  several  con- 
seontiTe  minutes.    It  becomes  then  necessary  to  have  recourse  to  some  source  of  elec- 
tricity in  which  these  objections  are  eliminated.     To  a  great  extent  this  is  the  case 
^Ui  magneto-electricity.     The  light  from  Messrs.  Wilde's  large  machine  is  the  most 
powerfnl  artificial  light  which  has  ever  been  produced,  giving  about  eight  times  the  light 
of  former  magneto-electric  machines.    like  most  practical  applications  of  science,  the 
important  results  which  Mr.  Wilde  has  obtained  depend  more  upon  an  ingenious  combi- 
nation of  several  known  facts,  united  with  considerable  engineering  skill,  than  upon  any 
really  new  and  striking  discovery.    The  principle  of  the  machine  can  be  expressed  in  a 
lew  words.    It  consists  in  the  application  of  a  current  from  an  electro-magnetic  machine, 
armed  with  permanent  magnets,  for  the  purpose  of  exciting  a  powerful  electro-magnet ; 
this  electro-magnet  being  now  used  as  the  basis  of  a  still  larger  electro-magnetic  machine, 
for  the  purpose  of  having  induction  currents  generated  by  its  agency.    In  other  words,  by 
well-known,  means,  an  electric  current  can  be  obtained  by  the  rotation  of  an  armature 
close  to  the  poles  of  a  magnet.     If  this  electric  current  be  passed  round  an  electro- 
magnet, it  may  be  made  to  produce  a  far  greater  amount  of  magnetism  than  was 
poBsessed  by  the  first  magnet.    There  is  no  difficulty,  therefore,  in  comprehending  how, 
by  the  mere  interposition  of  a  rotating  armature,  and  the  expenditure  of  force,  a  small 
and  weak  magnet  may  be  made  to  actuate  a  very  powerful  magnet.    But  as  the  power  of 
the  magnet  increases,  so  does  the  power  increase  of  the  electric  current  which  may 
he  generated  by  induction  in  an  armature  rotating  between  its  poles.    We  have,  therefore, 
only  to  pass  this  No.  2  induced  current  from  No.  2  magnet  round  a  still  larger  magnet, 
No.  3  ;  and  by  rotating  an  armature  between  its  poles,  we  can  get  a  still  more  energetio 
current.  No.  3.    Theoretically  there  is  no  limit  to  this  plan — it  is  a  species  of  involution  ; 
and  when  it  is  considered  that  each  conversion  from  magnet  No.  z  to  magnet  No.  2,  <ftc.,  or 
fi'om  induced  current  No.  i  to  induced  current  No.  2,  <Src.,  multiplies  the  power  very  many 
times,  it  will  not  be  surprising  that  after  three  involutions  the  induced  current  possesses 
such  magnificent  iK>wers.* 

Some  erroneous  opinions  are  pretty  generally  entertained  as  to  the  actual  discovery 
claimed  by  Mr.  Wilde,  and  the  splendour  of  the  result,  for  achieving  which  he  deserves 
the  very  highest  credit,  is  liable  to  cause  earlier  investigators  in  the  field  to  be  overlooked ; 
this  would  be  most  unfair,  for  it  is  through  their  instrumentality  that  the  way  has 
been  paved  for  the  success  now  achieved.  In  1838,  Abbes  Moigno  and  Raillord  proved 
that  by  taking  an  electro-magnetic  machine,  the  original  magnet  of  which  would  sup- 
port only  a  few  grammes,  and  passing  the  electric  current  generated  by  it  round  a 
large  electro-magnet,  the  latter  could  be  made  to  support  a  weight  of  600  kilogrms.  The 
Abb^s  carried  the  multiplication  of  power  only  so  far  as  to  obtain  the  more  powerful 
magnet.  No.  2,  from  the  weak  magnet.  No.  i. 

With  the  three  armatures  of  Mr.  Wilde's  machine  driven  at  a  uniform  velocity  of  1500 
revolutions  per  minute,  an  amount  of  magnetic  force  is  developed  in  the  large  electro- 
magnet far  exceeding  anything  which  has  hitherto  been  produced,  accompanied  by  the 
evolution  of  an  amount  of  dynamic  electricity  from  the  quantity  armature  so  enormous 
as  to  melt  pieces  of  cylindrical  iron  rod  fifteen  inches  in  length  and  fully  one  quarter  of 
an  inch  in  diameter.  With  this  armature  in,  the  physiological  effects  of  the  enrrent  can 
be  borne  without  inconvenience.  When  the  intensity  armature  was  placed  in  the  7-inoh 
magnet  cylinder,  the  electricity  melted  7  feet  of  No.  16  iron  wire,  and  made  a  length  of 
21  feet  of  the  same  wire  red-hot.  The  illuminating  power  of  the  current  from  this  arma- 
ture was  of  the  most  splendid  description.    When  an  electric  lamp,  furnished  with  rods 

*  See  "A  New  Era  in  Illumination,"  by  W.  Crookes,  F.B.S.;  *'  Quarterly  Journal  of 
Science,"  October,  1866. 


1 


682  CHEMICAL  TECHNOLOGY. 

of  gas  oarbon  half  an  inch  square,  was  placed  on  the  top  of  a  lofty  bnflding,  ftt 
light  eYoWed  from  it  was  snffioient  to  cast  the  shadows  of  the  flames  of  the  street  lamps 
a  quarter  of  a  mile  distant  apon  the  neighboming  walls.     When  yiewed   from  llot 
distance,  the  rays  proceeding  from  the  reflector  haye  all  the  rich  efiFnlgenee  of  smmhine. 
With  the  reflector  remoyed  from  the  lamp,  the  bare  light  is  estimated  to  have  an  intcDsty 
equal  to  4000  wax  candles.    A  piece  of  ordinaiy  sensitised  paper,  such  as  is  used  lor 
photographic  printing,  when  exposed  to  the  action  of  the  li^t  for  twenty  aeeoods,  tX  a 
distance  of  2  feet  from  the  reflector,  was  darkened  to  the  same  degree  as  a  piece  of  tfas 
same  sheet  of  paper  was  when  exposed  for  a  period  of  one  minute  to  the  dueet  rays  of 
the  sun  at  noon  on  a  yery  clear  day  in  the  month  of  March.    Paper  could  be  easily  set  on 
fire  with  a  burning-glass  introduced  in  the  path  of  the  rays  from  the  reflector. 
-  It  will  be  of  interest,  apart  from  all  questions  as  to  economical  production,  to  aseeitsia 
what  Lb  the  theoretical  quantity  of  coal  required  to  be  consumed  in  the   prodnetioD 
of  this  amount  of  electric  force.    Mr.  Wilde  says  that  a  7-horse  engine  is  required  to 
driye  the  machine.    One  horse-power  is  equal  to  1,980,000  foot-pounds  per  hour;  thsi 
multiplied  by  seyen  is   13,860,000  foot-pounds  per  hour,  which  tiierefore   represests 
the  actual  power  required   to  driye  the  machine.      Now,  by  multiplying  the  BtioEli 
Fahrenheit  units  of  heat  produced  by  the  combustion  of  one  pound  of  ooal  by  Joule^s 
equiyalent,  772  foot-pounds,  the  result  will  be  the  total  heat  of  combustion  expressed  in 
foot-pounds.    In  the  best  coal  this  is  aa  high  as  12,000,000  foot-pounds.    We  aziiys* 
therefore,  at  the  conclusion  that,  to  oyercome  the  friction  of  the  different  parts  of  the 
machine;   to  whirl  a   mass  of  metal,   weighing  seyeral  hundredweights,  round  with 
a  yelocity  of  1500  reyolutions  per  minute ;  to  generate  a  current  of  electric  fcuroe  far 
passing  anything  before  produced ;  and,  after  allowing  for  the  waste  inherent  in  its 
sage  through  the  conducting  wires  and  electric  lamp,  to  cause  it  to  blaze  forth  with  an  ~ 
sity  of  light  paling  the  rays  of  the  sun ;  to  keep  up  this  intense  deyelopment  of 
for  one  hour — ^requires  an  expenditure  of  force  represented  by  the  combustion  of  less  than 
i8|  ozs.  of  coal.    This  is  the  theoretical  calculation ;  but  if  reduced  to  actual  practice,  the 
results  are  scarcely  less  astonishing.    The  efficiency  of  an  engine,  i.e,  the  ratio  of  the 
work  actually  performed  to  the  mechanical  equiyalent  of  the  heat  expended,  Tsxies  in 
extreme  cases  between  the  limits  0*02  and  o'2.    Taking  an  ayerage  efficienpy  as  o*z,  or 
tenth,  we  find  that  the  ordinary  consumption  of  coal  required  to  work  a  j  horse-po^ 
engine,  midway  between  excessiye  wastefulness  on  the  one  hand,  and  ngid  eooaia 
on  the  other,  is  10  x  i8i  ounces,  or  ii|  lbs.  of  coal  per  hour,  worth  about  one  halfjpemiy. 
This  is,  of  course,  only  one  item  in  the  cost — to  it  must  be  added  the  expense  ttf  eaiboD 
rods  for  the  lamp,  which  will  be  about  ten  inches  per  hour,  worth  perhaps  a  pemqr; 
there  must  also  be  added  interest  of  the  cost  of  purchase  of  machines,  expense  of  nain^ 
tenance   and  repairs,  which  will  perhaps  bring   up   the  total  expense    per  hour  to 
sixpence  or  eightpence.    Comparing  this  with  the  hourly  expense  of  the  eleetiie  fi^ils 
already  in  existence,  we  find,  according  to  the  Abb^  Moigno,  that  the  French  marhine 
costs  altogether  sixpence  per  hour  for  a  light  equal  to  goo  wax  candles ;  whilst  the  actual 
working  expenses  of  maintaining  the  electric  light  at  Cape  La  Heye^  during  a  pcnod  of 
twenty-seyen  months  haye  been,  exclusiye  of  salaries,  about  one  shilling  per  h€«r, 
or  inclusiye  of  salaries,  two  shillings.    According  to  a  calculation  made  by  the  Ahbi^ 
Moigno  respecting  the  economy  of  &e  light  eyolyed  by  the  French  machines,  it  appesn 
that  to  maintain  a  light  equal  to  4000  wax  candles  for  one  hour  would  cost — ^with  gas, 
£1  26.  6d. ;  with  colza  oil,  £1  7s. ;  and  with  the  electricity  produced  by  a  Bunaen*s  ^k, 
£1 15s.  6d.    The  annual  expeuditure  at  a  first-class  lighthouse  on  the  old  ^stem  is,  on  •■ 
ayerage,  £400  per  annum ;  and  on  the  assumption  that  the  light  bums  for  4000  boon  p9 
annum,  that  would  come  to  two  shillings  per  hour.    The  expenses  of  the  eld  nd 
the  electric  system  are  therefore  not  yexy  dissimilar ;  and  the  problem  of  the  adoption 
of  electricity  to  supersede  oil  must  be  decided  on  grounds  of  eonyenience  and  effieieD^ 
alone. 

One  cause  of  inconstancy  in  the  electric  lamp  which  hinders  the  adaptation  to  the  p«r- 
poses  of  lighthouse  illumination  is  the  unequal  consumption  of  the  carbon  points.  Tmb. 
experiments  recently  conducted  for  the  Trinity  House,  Bfr.  Steyenson  finda  that  the 
employment  of  a  modified  form  of  yacuum-tube  remoyes  this  objection.  The  sabjeet 
upon  which  we  cannot  enter  more  fully  here  is  yery  exhaustiyely  treated  in  Mr.  Stefenson** 
recent  work  on  the  illumination  of  lighthouses. 

The  following  Table  exhibits  the  comparative  illaminating  power  of  the  princ^ii 

artificial  lights : — 


ARTIFICIAL  LIGHT.  683 

...          ,    .             Oonsumption  Intensity  of  light.  Light  obtained  IllaminAting 

jjigbt-prodxicing                 ^^^  ^       ,^  ^^^  candle  from  logrms.  of  power  (wax 

SubBtanoe.                   ^^^^                  =100).  this  materiaL  candles « 100). 

Wax      9'oa                loa'oo  11102  100 

Stearic  add 9*94                  95'50  9603  84 

Spermaceti 887                 108*30  123'17  108 

Tallow ...      887                   90-25  10170  90 

Paraflfin (ist quality)   ...      883                     —  9469  83 

(and    „    )  ...      849                    —  139*87  123 


O 


'Moderator lamp  ...  4069  694*00  17007  159 
Kitchen  lamp      ...  733  45"^  6«"30  55 
Reading  lamp ,  with- 
out glass  chimney  9*86  11401  ti5'8o  102 

Photogen      2002  —  i49*03  ^3^ 

Solar  oil       26*82  —  22564  199 

Petroleum     1506  —  i74'40  180 

8*09  —  i86'oi  195 


•f  ••     ..• 


According  to  Dr.  Frankland*s  researches,  the  following  quantities  of  illuminating 
materials  exhibit  equal  illuminating  power : — 

Young's  parafi^  oil  from  Boghead  coal  4*53  litres. 

American  petroleum  (No.  i)  ...     570     „ 

ft  ft  {jSo»  2)  ...     ...     .*•        5*88     ft 

Paraffin  candles ... 8*42  kilos. 

Spermaceti  candles io*37    » 

wax  ff         ...     .*•     ...     ...     ■*.  11 95 

Stearine         „        • 12*50 

xaixow^  yf         ...     ...     a..     ...     •••  xo  30     t% 


Paraffin  akd  Solar  or  Pktrolxum  Oils. 

pMafinooik  Paraffin  was  discovered  in  the  year  1830  by  Karl  tob  Beichenbach 
among  the  products  of  the  dry  distillation  of  beech-wood  tar,  and  has  obtained  its 
name  from  paruniy  little,  and  qffinis,  related  to,  on  account  of  its  incapability  of 
chemically  uniting  witli  other  substances.  Paraffin  is  not  acted  upon  by  alkalies  or 
acids,  nor  is  it  decomposed  at  a  red-heat.  It  was  afterwards  found  that  paraffin  is 
also  formed  by  the  dry  distillation  of  peat,  brown  coal.  Boghead,  and  some  cannel 
coals,  but  not  by  the  dry  distillation  of  real  coal.  Paraffin  is  found  native  and  occurs 
in  large  quantities  in: — i.  Petroleum,  Bangoon  and  Persian,  which  sometimes  con- 
tains 6  to  40  per  cent.  2.  In  impure  state,  under  tlie  names  of  ozokerite,  neft-gil, 
or  mineral  wax.  3.  In  bitumen,  asphalte  as  contained  in  some  schistose  rocks,  and 
as  met  with  at  Trinidad  and  elsewhere. 

MwoiMtan  of  parmflia.  The  modc  of  obtaining  this  substance  differs  according  to  its 
being  an  educt  or  a  product.  It  is  an  educt  as  obtained  from  petroleum,  ozokerit, 
neft-gil ;  but  a  product  of  the  dry  distillation  of  brown  coal,  peat,  and  the  Boghead 
shale. 


684  CHEMICAL  TECHNOLOGY. 

"""^SSfStoSe^lS*"  '•  'niatpetroletimcontamBpw^ffiii  was  known  in  the  year  i8«. 
when  A.  Buchner  discovered  in  the  earth  oil  of  the  Tegemsee,  in  Upper  BaTBiia,  a 
solid,  fatty  substance,  which  was  afterwards  ascertained  by  V.  Kobell  to  be  panfflou 
Hence  Buchner  is  locally  considered  to  be  the  discoverer  of  pa^raffln ;  while  later 
researches  have  proved  that  the  earth  oil  of  Baku,  on  the  Caspian  Sea ;  of  ^"*^«»*. 
near  Parma ;  and  of  Gabian,  H^rault,  France ;  contain  this  substance  to  greater  or 
less  extent.  The  idea  of  using  these  oils  for  the  industrial  preparation  of  parsflbi 
dates  only  from  1856,  when  some  samples,  of  petroleom  which  were  found  to  ooataia 
a  large  quantity  of  paraffin  were  imported  into  Europe.  The  American  petrolesiDB 
contain  only  a  very  small  quantity  of  paraffin:  but  in  those  derived  from  Bmniah 
and  Bangoon,  Gregory,  De  la  Hue,  and  H.  Miiller  found  10  per  cent.  Bleekrodc 
investigated  a  sample  of  Java  petroleum  which  contained  40  per  cent  of  paiaffiiL 
The  mountain  naphtha  of  Eastern  Galicia  is  with  great  advantage  employed  for  prrf 
paring  paraffin.  According  to  Jacinsky,  45,000  cwts.  of  this  material  were  in  1866 
obtained  from  this  naphtha. 

The  Kangoon  oil  obtained  from  Burmah  as  a  native  product  flowing  firon  spfrings 
in  the  neighbourhood  of  the  river  Irawadi  is,  according  to  De  la  Bae's  patent 
(1854),  treated  in  the  following  manner  for  the  purpose  of  preparing  paraffin  aad 
hydrocarbon  oils.  The  crude  oil  is  first  put  into  a  still,  which  can  be  heated  by  fire 
externally  while  steam  is  admitted  internally.  By  this  operation  abont  25  per  cent 
of  a  fluid  is  obtained,  which  on  being  submitted  to  fractional  distillation  yields 
hydrocarbon,  the  sp.  gr.  of  which  varies  from  0*62  to  0*86,  while  the  boiling-point 
varies  from  aC'y"*  to  200°.  The  lightest  and  most  volatile  of  these  hydrocarbons  is 
used  as  an  antesthetic,  under  the  name  of  Sherwood  oU,  whOe  the  heavier  oils 
are  burnt  in  paraffin  lamps.  The  residue  of  this  first  distillation — abont  75  per  cent 
of  the  original  quantity — ^is  again  distilled,  but  with  steam  at  150^  to  200^ ;  and  the 
products  of  variable  volatility  are  separately  collected.  The  last  portions  of  the  dis- 
tillate contain  chiefly  paraffin,  which  is  in  crude  state  separated  from  the  liqnl 
by  the  application  of  artificial  cold.  The  heavy  oil  is  used  as  lubricating  oil,  and  tke 
paraffin  is  purified  as  already  described. 

'''"Sd  iTStSo*'*^'*  Paraffin  is  prepared  from  ozokerite  and  neft-giL  on  the  isbai 
Swatoi-Ostrow,  in  the  Caspian  Sea,  about  a  verst  (  =  106678  metres)  from  the 
peninsula  Apscheron,  on  the  Caucasian  shore.  The  nefb-gil  is  carried  by  ships  tram 
Truchmenia.  Paraffin  is  largely  manufactured  in  Galicia  from  the  minetal  wax 
which  occurs  near  Drohobicz  and  Boryslaw,  also  on  the  northern  slopes  of  the  Csr- 
patliian  mountains,  and  in  other  parts  of  the  Austrian  Empire.  The  chief  works  are 
found  at  Aussig,  Florisdorf,  Ostrau,  Vienna,  New  Pesth,  Temisvar,  Stc  Mineral  wax 
is  also  largely  found  in  Texas. 

Neft-gil,  according  to  F.  RossmassUer,  is  treated  in  the  following  manner:— 
15  cwts.  of  the  crude  material  is  put  into  iron  stills  provided  with  a  leaden  womt,  sad 
submitted  to  fractional  distillation,  yielding  68  per  cent  of  distillate,  consisting  of 
8  per  cent  of  oil  and  60  per  cent  of  crude  paraffin.  The  oil  thus  obtained  is  yeUov, 
opalescent,  possesses  an  ethereal  odour,  and  a  sp.  gr.  of  0*75  to  o'8i.  Bach  distilk' 
tion  yields  a  quantity  of  a  hght  oil  boiling  below  loo^  which  is  used  ior  the  purpose 
of  purifying  the  paraffin.  The  crude  paraffin  obtained  by  the  first  distillatioa  if 
tolerably  pure,  has  a  yellow  colour,  and  can  at  once  be  treated  by  the  hydiaolic  pns 
and  centrifugal  machine.  The  oil  from  these  operations  is  again  submitted  to 
fractional  distillalion  in  order  to  obtain  more  paraffin.     The  pressed  paraffin  i* 


ARTIFICIAL  LIGHT.  685 

molten  and  treated  at  170°  to  iSo**  with  Bulphnric  acid,  which  is  next  neutralised  bj 

means  of  lime,  and  the  paraffin  again  rapidly  distilled;   then  again  submitted 

to  strong  pressure,  and  the  material  obtained  treated  witli  25  per  cent  of  the  light 

oil ;  then  again  molten,  again  pressed,  and  finally  treated  with  steam  for  the  purpose  of 

eliminating  the  last  traces  of  essential  oil.    The  material  obtained  by  this  treatment 

is  a  perfectly  pure,  colourless  material,  free  from  smell,  transparent,  and  so  hard  as 

to   exhibit  in  large  blocks  an  almost  metallic  sound.     The  fusion-point  is  63"*. 

Bossmassler  states  that  the  raw  material  yielded  to  him  in  a  week's  time,  after 

a  previous  continued  distillation  of  two  months,   148^   cwts.  of  paraffin  ready 

for  second  pressure.    The  Galician  ozokerite  yields  by  distillation  only  24  per  cent  of 

paraffin,  and  45  per  cent  of  paraffin  oil,  also  termed  ozokerite  oil. 

PMnfflnfrommtimax.      0.  Paraffin]  is  made  in  England  from  bitumen,  asphalte,  mineral 

^tar,  and  the  bituminous  organic  matter  present  in  certain  shales ;  among  these,  the 

so-called  Kimmeridge  clay.  Boghead  coal,  and  a  few  cannel  coals.    The  asphalte 

occurring  in  Trinidad,  Cuba,  Nicaragua,  Peru,  California,  and  other  countries,  is 

used  for  the  purpose  of  preparing  paraffin  and  paraffin  oils.    The  Cuba  and  Trinidad 

asphaltes  yield  175  per  cent  paraffin.    The  extensive  deposits  of  bituminous  shale  in 

Hungary  are  treated  for  paraffin  and  oil  at  Oravicza.  According  to  Wunschmann,  the 

shale  yields  5  to  6  per  cent  of  paraffin,  49  per  cent  of  oil  suited  for  burning  in  lamps, 

and  6  per  cent  of  lubricating  oil. 

^'dJ^^dLSBK?**^  The  preparation  of  paraffin  by  the  dry  distiUation  of  peat, 
brown-coal,  coal-shale,  Boghead  coal,  Ac.,  involves  two  operations : — i.  The  prepa- 
ration of  tar.  2.  The  application  of  the  latter  to  the  preparation  of  paraffin  oil 
and  paraffin.  The  coal-tar  of  the  gas-works  does  not  contain  paraffin,  but  naphtha- 
line and  anthracen. 

pnptt»U(mofi]iaTar.  I.  This  Operation  is  one  of  the  most  important  and  difficult  of 
the  industry,  and  during  the  last  fifty  years  many  enterprises  undertaken  for  the 
application  of  fossil  fuel  to  the  preparation  of  illuminating  materials  have  failed 
solely  on  account  of  the  imperfect  preparation  of  the  tar.  The  making  of  the  tar  is 
carried  on  in  retorts  or  in  peculiarly  constructed  ovens,  the  distillation  being  in  many 
eases  assisted  by  the  application  of  superheated  steam.  The  principle  of  the  con- 
struction of  the  tar  oven  is  very  simple,  being  that  by  a  portion  of  fuel  burning  in  the 
lower  part  of  the  oven,  a  layer,  more  or  less  thick,  of  superincumbent  fuel,  is  sub- 
mitted to  a  slow  carbonisation,  resulting  in  the  production  of  tar,  which  flows  down- 
wards, while  the  gaseous  products  are  lost.  In  order  to  prevent  its  violent  combus- 
tion, the  fuel  is  covered  with  a  layer  of  clay.  But  as  experience  has  shown  that  this 
mode  of  distillation  is  not  well  suited  for  the  production  of  tar  intended  to  yield 
paraffin  and  the  oils,  it  is  not  general  in  practice  on  the  large  scale,  although  it  has 
the  advantage  of  being  a  continuous  and  uninterrupted  process.  According  to 
report,  an  oven  constructed  by  L.  Unger,  the  manager  of  a  paraffin  works  at  DoU- 
nitz,  near  Halle,  yields  suitable  products,  while  a  saving  is  effected  in  labour  as  well 
as  in  the  quantity  of  fuel  required  for  the  distillation. 

Horizontal  retorts  are  frequently  used  for  the  preparation  of  tar,  but  experience 
has  taught  that  if  in  the  construction  of  the  furnaces  containing  the  retorts  the 
arrangement  is  similar  to  that  of  a  gas-works  where  four  to  eight  retorts  are  worked 
in  one  furnace,  no  satisfactory  results  can  be  obtained,  one  of  the  reasons  being  that 
the  principles  of  gas-  and  of  tar-making  are  entirely  opposed.  It  appears  to  be 
necessary  to  construct  a  furnace  for  every  retort,  and  that  the  furnace  should  be 


686  CHSmCAL  TECHNOLOGY. 

of  snoh  dimensions  as  to  be  salted  to  hold  a  retort  xo  feet  long,  50  inches  wide,  wai 
15  inches  high,  forming  in  section  a  shallow  oval.  More  recently  there  hare  been 
bnilt  in  Bohemia  and  elsewhere  brickwork  retorts,  shaped  somewhat  like  a  baker's 
oven.  These  seem  to  answer  well,  but  are  difficult  to  repair  although  of  small  first 
cost.  Vohl  observed  that  a  qaantity  of  20  to  25  per  cent  of  water  present  in  the 
fossil  material  very  greatly  assists  the  formation  and  increases  the  yield  of  tar, 
owing  to  the  superheated  steam  formed  from  the  water  daring  the  distillation 
carrying  off  the  vapours  of  the  tar  rapidly  from  the  hot  retort.  This  has  given  rise 
to  the  construction  of  Lavender's  tar-producing  apparatus,  the  principle  of  which  is 
the  same  as  that  of  Violetti's  wood-charring  apparatus  used  for  the  preparatiaB  of 
the  charcoal  in  gunpowder  manufacture.  Lavender's  apparatus  consists  of  an  inxi 
cylinder  provided  with  holes  at  the  bottom  for  the  purpose  of  admitting  8aperhea;ted 
steam,  while  to  the  top  of  the  cylinder  a  tube  is  fitted  for  carrying  off  the  products  of* 
the  distillation.  It  would  appear  that  L.  Bamdohr's  method  of  preparing  tar  from 
brown-coal  by  means  of  steam  yields  a  tar  which  contains  22  to  24  per  cent  of 
paraffin  and  36  to  38  per  cent  of  oil. 

Yi^^lTii^^'Sa  ^^®  condensation  of  the  products  o(  the  dry  distillation  is  one  of 
the  most  important  operations,  and  greatly  influences  the  yield  of  tar.  Vohl  has 
lately  proved  that  even  when  the  construction  of  the  retorts  is  not  of  the  best,  an 
average  yield  of  tar  may  be  obtained  by  attention  to  the  condensation  of  the  vapovis. 
The  complete  condensation  of  the  vapours  of  the  tar  is  one  of  the  most  difficult 
problems  the  paraffin  and  mineral  oil  manufacturer  has  to  deal  with,  while  the  means 
usually  adopted  for  condensation,  such  as  large  condensing  surfaces,  injection  of  cold 
water,  and  the  like,  have  proved  ineffectual  It  has  often  been  attempted  to  oondense 
the  vapours  of  tar  in  the  same  manner  as  those  of  alcohol,  but  there  exist  essential 
differences  between  the  distillation  of  fluids  and  dry  distillation.  In  the  former  case 
the  vapours  soon  expel  all  the  air  completely  from  the  still  and  from  the  condenser* 
and  provided,  therefore,  that — in  reference  to  the  size  of  the  still  and  bulk  of  the 
boiling  liquid — ^the  latter  be  large  and  cool  enough,  every  particle  of  vapour  must 
come  into  contact  with  the  condensing  surfaces.  In  the  process  of  dry  distiUatioa 
the  case  is  entirely  different,  because  with  the  vapours,  say  of  tar,  permanent  gases 
are  always  generated.  On  coming  into  contact  with  the  condensing  surfaces,  a 
portion  of  the  vapours  are  liquefied,  leaving  a  layer  of  gas  as  a  coating,  as  it  were, 
on  the  condensing  surface.  The  gas  being  a  bad  conductor  of  heat,  prevents  to  sodi 
an  extent  the  further  action  of  the  condensing  apparatus,  that  a  large  proportion  of 
the  vapours  are  carried  on  and  may  be  altogether  lost.  A  sufficient  condenaatioQ  of 
the  vapours  of  tar  can  be  obtained  only  by  bringing  all  the  particles  of  matter  whick 
are  carried  off  from  the  retorts  into  contact  with  the  condensing  surface,  which  need 
neither  be  very  large  nor  exceedingly  cold,  because  the  latent  Jieat  of  the  vapoms 
of  tar  is  small,  and  consequently  a  moderately  low  temperature  will  be  sufficient  to 
condense  these  vapours  to  the  liquid  state.  The  mixture  of  gases  and  vapours  may 
be  compared  to  an  emulsion,  such  as  milk,  and  as  the  particles  of  butter  may  be 
separated  from  milk  by  churning,  so  the  separation  of  the  vapours  of  tar  from  the 
gases  can  be  greatly  assisted  by  tlie  use  of  exhausters  acting  in  the  manner  of 
blowing  fans.  It  is  of  the  utmost  importance  in  condensing  the  vapours  of  tar  that 
the  molecules  of  the  vapours  be  kept  in  continuous  motion,  and  thus  made  to  tooek 
the  sides  of  the  condenser.  The  condenser  should  not  be  constructed  so  that  the 
vapours  and  gases  can  flow  uninterruptedly  in  one  and  the  same  direction.    Tht 


ARTIFICIAL  LIGHT.  687 

temperature  at  which  the  distillation  is  conducted  greatly  influences  the  yield  of  tar, 
and  consequently  of  the  paraffin  and  oil.  As  regards  the  influence  of  the  shape  of 
the  retorts  and  mode  of  distillation,  H.  Vohl  made  the  undermentioned  comparative 
researches  by  distilling  French  and  Scotch  peat  in  horizontal  retorts  (No.  I.j,  in 
vertical  retorts  (No.  II.) »  and  in  ovens  somewhat  like  coke-ovens  (No.  III.) 
100  parts  of  peat  yield  of  tar, — 

I.  n.  m. 

French  peat  ...    ...    5*59  467  2*69 

Scotch  peat »    ...    9*08  639  4*16 

The  sp.  gr.  of  the  tar  from  the  different  kinds  of  apparatus  was  as  follows : — 

I.  n.  m. 

French  peat 0*920         0*970  i'oo6 

Scotch  peat ^'935  0*970  1*037 

It  appears  from  these  results  that  horizontal  retorts  yield  the  largest,  and  ovens 
the  smallest,  quantity  of  tar ;  moreover,  the  duration  of  the  operation  of  distilling  is 
shortest  in  horizontal  retorts,  which  also  yield  less  gas,  while  in  the  ovens  both  tar 
and  coke  are  burnt  away  to  a  considerable  extent  by  the  too  great  supply  of  oxygen. 
piopMtiMofTw.  The  tar  obtained  from  the  retorts  in  distilling  peat,  brown-coal, 
lignite,  bituminous  shales.  Boghead  coal,  Ac.,  at  as  low  a  temperature  as  possible, 
and  hardly  higher  than  dull  red-heat  even  towards  the  end  of  the  operation,  exhibits 
a  coffee-brown  colour,  generally  an  alkaline,  in  some  instances  an  add,  reaction,  and 
possesses  the  very  penetrating  odour  characteristic  of  tar.  By  exposure  to  air  the 
colour  of  the  tar  becomes  deeper,  and  sometimes  even  brownish-black.  This  tar 
often  semi-solidifies  at  a  temperature  of  9°  to  6**,  owing  to  the  paraffin  it  contains. 
The  sp.  gr.  varies  from  0*85  to  0*93,  and  consequenUy  the  tar  floats  on  water.  The 
so-called  steam-tar,  obtained  by  the  aid  of  superheated  steam  frt>m  brown-coal 
(according  to  Ramdohr's  plan,  1869)  always  has  an  acid  reaction,  and  is  completely 
saponified  by  alkalies ;  this  tar  becomes  solid  at  a  temperature  of  55°  to  60'',  and  can 
therefore  be  preserved  in  solid  blocks  in  summer  time.    Its  sp.  gr.  is  0*875. 

As  regards  the  quantity  of  tar  obtained  from  100  parts  of  raw  material,  the  fol- 
lowing results  are  most  general : — 

Tar.        8p.  gr.        Crude  paraffin, 
, u_-^  Per  cent. 

Foliated  bituminous 

shale,  Siebengebirge         20*00       0*880  0*750 


M  »t 


Hesse  25*00  0*880  x'ooo 

Brown-coal,  Prussian  Saxony      700  0*910  0*500 

lo'oo  0*920  0750 

6*00  0*915  0500 

5'oo  0*910  0*250 


»»  »» 


Bohemia  11 'oo  0*860 

Westerwald  5*50  0*910 

3*50  0*910 

Nassau  4*00  0*910 

„  3*oo  0*910 

Frankfort  9*00  0890 


Lignite,  Silesia  3*00       0*890  0*25 

Shale,  Vend6e  14*00       0870  .  I'ooo 


688 


CHEMICAL   TECHSOLOGY, 


Tar. 


Sp.  gr. 


Shale, 

Schist, 

Peat, 


»f 


»♦ 


»» 


»f 


»!• 


Westphalia 

Wurtemburg 

Neumark 

Hanover 

Erzgebirge 


ft 


Boghead  coal, 
Cannel  coal, 
Peltonian  coal, 
Coarse  coal, 


Russia 
Scotland 


5*00 

963 
500 
900 

570 
S'30 
586 

700 
3300 


0*920 

0975 
0910 

0*920 

0*902 

0905 


o'86o 


»» 


9t 


»» 


900  0910 


Grade  paraffin. 
Per  cent. 

0050 

0'124 

0330 
0330 
0350 
0*400 


1—1-4 
I— 13 

I'OOO 
I— I '25 


Mode  of  Operating 
with  the  Tar. 


Tlie  first  tiling  to  be  done  with  the  crude  tar  is  to  separate  the 
water,  which  is  effected  by  pumping  the  tar  into  the  dehydrating  apparatus.  These 
apparatus  consist  of  tanks  of  boiler-plate,  placed  within  a  larger  tank,  so  that  a  space 
of  10  centims.  intervenes,  into  which  water  is  poured  and  maintained  by  means  of 
steam  at  a  temperature  of  60°  to  80"  for  ten  hours.  After  this  time  the  ammoniacal 
water  and  other  impurities,  together  about  one-third  of  the  bulk  of  the  crude  tar. 
have  become  separated,  while  the  small  quantity  of  water  still  adliexing  to  the  tar  is 
of  no  consequence  in  the  further  operations.  The  tar  is  decanted  by  opening  a  stop- 
cock or  valve  placed  near  the  top  of  the  tank,  and  the  ammoniacal  water  is  removed 
by  opening  a  stop-oock  at  the  bottom. 

Specifically  light  tars  are  of  course  readily  separated  from  the  water,  while  heavy 
tars  are  more  difficult  to  deal  with.  If  to  the  ammoniacal  water  of  such  tars  salts 
are  added,  for  instance,  common  salt,  Glauber  salt,  chloride  of  calcium,  and  the  like, 
the  specific  gravity  of  the  water  is  increased,  and  the  heavy  tar  more  readily  sepa- 
rated ;  but  according  to  Dullo  these  means  are  either  too  expensive  or  do  not  quite 
answer  the  purpose.  The. complete  separation  of  the  tar  from  the  water  is  of  the 
greatest  importance,  because  in  the  subsequent  distillation  the  presence  of  water  may 
cause  the  tar  to  boil  over  and  give  rise  to  serious  accidents  by  coming  in  contact 
with  the  fire  under  the  stills. 

DistfflftUonofttieTw.  This  Operation  is  usually  carried  on  in  cast-iron  stills  large 
enough  to  hold  20  cwts.  of  tar.  In  order  to  prevent  the  flame  impinging  on  the 
bottom  of  the  still,  it  is  protected  by  a  fire-brick  arch.  The  still  is  usually  built  in 
two  separate  parts,  which  are  joined  with  a  flange  and  bolts,  so  that  if  the  lower  part 
is  burnt  out,  only  that  requires  to  be  renewed. 

The  helms  of  these  stills  are  rather  flat  and  the  spout  very  wide.  The  vapours  of 
the  various  oils  have  a  high  density  and  low  latent  heat,  so  that  these  vapours  have 
a  tendency  to  condense  readily  and  flow  back  into  the  still ;  therefore  the  helm  is 
covered  with  sand  or  ash,  being  bad  conductors  of  heat.  When  the  tar  is  thoroughly 
dehydrated,  the  distillation  proceeds  quietly  and  without  ebullition ;  but  if  any  water 
be  mixed  with  or  adheres  to  the  tar,  the  liquid  in  the  still  boils  violently  and  is  very 
apt  to  boil  over.  At  below  loo"^  the  tar  loses  the  very  volatile  sulphide  of  ammonium 
and  the  pyrrhol  bases,  while  gases  are  evolved  which  ought  to  be  allowed  to  escape 
by  a  safety-valve.    The  true  distillation  begins  at  lob'',  yielding  at  first  a  distillate 


ARTIFICIAL  LIGHT.  689 

consisting  of  yeiy  strong  anunoniacal  liquor  and  some  light  oils.  The  boiling-point 
of  the  tar  is  not  constant,  the  oil  coming  over  onintermptedlj  when  the  temperature 
has  risen  to  above  200'' ;  then  the  boiling-point  becomes  somewhat  constant,  while 
with  the  oil  some  water  cornea  over,  due  to  the  chemically-combined  water  of  the 
carbolic  add  being  set  free.  The  distillation  then  again  becomes  somewhat  inter- 
rupted, and  can  be  maintained  only  by  stronger  firing  of  the  retort.  The  oils  now 
distilling  over  become  solid  on  cooling,  owing  to  the  large  proportion  of  paraffin  they 
contain.  The  distillation  is  continued  to  dryness,  the  asphalte  left  in  the  still  being 
removed  after  about  four  or  five  operations,  and  for  this  purpose  the  still  is  some- 
what cooled  and  the  molten  asphalte  run  off  by  a  tap  at  the  bottom  of  the  still.  If 
the  distillation  is  carried  to  dryness,  some  water  finally  distils  over,  due  to  the 
decomposition  of  the  organic  matter.  A  still  of  500  litres  capacity  can  be  distilled 
off  in  twelve  to  fourteen  hours,  if  the  operation  is  pushed  so  feu:  as  to  decompose 
the  asphalte,  leaving  only  a  carbonaceous  residue ;  but  if  the  asphalte  is  to  be  col- 
lected, the  distillation  must  be  stopped  after  eight  to  ten  hours.  The  still  is  sepa- 
rated from  the  condensing  apparatus  by  a  massive  wall,  through  which  the  spout  of 
the  helm  is  passed  into  the  leaden  worm  serving  as  a  condenser,  and  kept  cool  by 
being  placed  in  a  wooden  tank  filled  with  cold  water.  But  as  soon  as  the  paraffin 
magma  begins  to  come  over  the  water  is  allowed  to  become  warm,  in  order  to 
prevent  the  paraffin  solidifying  in  the  worm.  The  gases  which  are  evolved  towards 
the  end  of  the  distillation  are  carried  off  by  a  pipe  communicating  with  the  chimney. 

^'^^S'DiSaiutiS?*™^  The  mixed  products  or  raw  oils  obtained  by  the  distillation 
are  poured  into  a  large  cast-iron  cylinder  and  mixed  with  a  solution  of  caustic  soda 
so  as  to  cause  the  latter  to  act  upon,  and  intimately  combine  with,  the  acid  sub- 
stances (homologues  of  carbolic  acid) — simply  termed  creosote  in  the  works — and 
pyroligneous  acid — which  impart  an  offensive  odour  and  dark  colour  to  the  oils. 
When  the  mixture  of  the  oils  and  caustic  soda  solution  has  been  effected,  the  fluid  is 
run  into  an  iron  tank  and  allowed  to  settle ;  the  creosote-soda  is  then  removed,  and 
the  oil  washed  with  water  to  eliminate  any  adhering  alkali.  The  crude  oil  is  next 
similarly  treated  with  sulphuric  acid  for  the  purpose  of  removing  basic  substances, 
which  impart  odour  and  colour.  The  quantity  of  acid  to  be  used  and  the  duration 
of  its  action,  aided  sometimes  by  heat,  depend  upon  the  nature  of  the  crude  oil — 
5  per  cent  of  acid  of  170  sp.  gr.  and  five  minutes  action  are  sometimes  sufficient, 
while  in  other  cases  25  per  cent  of  acid  will  be  required,  and  three  hours'  contact 
with  the  oil.  The  action  of  the  sulphuric  acid  should  be  carefully  watched,  as  it  may 
injure  the  quality  of  the  oil  by  decomposing  some  of  the  lighter  hydrocarbons,  whereby 
sulphurous  add  is  given  off.  The  mixture  of  acid  and  oil  is  allowed  to  settie; 
the  former  is  run  off,  and  the  latter  washed  first  with  water  then  with  very  dilute 
soda  ley,  and  is  finally  poured  into  the  rectifying  stills.  The  solution  of  creosote-soda 
is  neutralised  with  the  sulphuric  acid  from  the  preceding  operation,  the  result  being 
that  crude  carbolic  acid  is  obtained,  which  is  used  for  various  purposes ;  such  as 
impregnating  wooden  railway  sleepers,  as  a  disinfecting  material,  or  for  preparing 
certain  tar-colours  (see  p.  580).  More  recently  the  creosote-soda  has  been  used  for 
gas  manufacture,  leaving  a  coke  containing  soda,  the  soda  being  abstracted  by 
lixiviation  with  water. 

R^eujcjumrof  um      ^his  Operation  is  conducted  predsely  as  the  distillation  of  the  tar. 
The  oils  are  separated  according  to  their  greater  or  less  volatility  and  specific 

3^ 


690  CHEMICAL  TECHNOLOGY. 

gravity,  or  are  kept  mixed,  as  parafiELn  oil,  at  a  sp.  gr.  of  0-833,  ^^^  ^^^^  <^  Bach  to  the 
market.    When  the  oil  which  comes  over  begins  to  solidify  on  cooling  or  exhibits  a 
sp.  gr.  of  o'88  to  0*9,  it  is  separately  collected  and  placed  in  a  cool  situation  for  the 
purpose  of  crystallising  the  paraffin.     The  vessels  in  which  the  paraffin  magma 
is  placed  for  the  purpose  of  solidifying  are  rectangular  iron  tanks,  fitted  with  a  tap, 
or  are  conical,  sugar-loaf  shaped  vessels,  made  of  iron  or  wood,  and  from  i'6  to  2 
metres  high,  and  i  metre  wide  at  the  top,  being  provided  with  a  tap  for  the  purpose 
of  removing  the  oily  matter  which  has  not  solidified  after  the  lapse  of  about  two 
to  four  weeks.    This  thick  oil  is  next  cooled  to  far  below  the  freezing-point  of  water, 
in  order  to  obtain  more  paraffin  and  other  hydrocarbons  mixed  with  it.     Any 
still  non-solidified  matter  is,  when  it  has  a  low  specific  gravity,  again  refined  by  dis- 
tillation, and  will  yield  paraffin  oU ;  but  if  its  sp.  gr.  is  high— say  from  0*925  to  0*940— 
it  is  used  as  a  lubricating  oil,  known  abroad  as  Belgian  waggon  grease. 
Eeflain^the  Grade      The  crude  paraffin  is  in  England  sold  to  the  refiners,  irtio  are 
also  paraffin-candle  makers;   but  on  the  Continent  every  manu£Eictnrer  of  cmde 
paraffin  refines  his  product  and  converts  it  into  candles.    The  crude  paraffin,  so- 
called  paraffin  butter,  is  treated  in  various  ways :  some  manufacturers  crystallise  it 
by  the  aid  of  cold,  and  press  it  for  the  purpose  of  removing  any  oil ;  others  again 
first  treat  the  crude  material  with  caustic  alkali  ley,  next  with  sulphuric  acid, 
and  then  again  distU  it  or  leave  it  to  crystallise.    The  caustic  soda  ley  removes 
from  the  paraffin  all  the  acid  substances  and  other  impurities  it  may  contain.    The 
partly  purified  paraffin  is  now  treated  with  6  to  10  per  cent  of  sulphuric  acid, 
whereby  alkaline  and  resinous  matters  are  removed.    The  loss  in  bulk  of  the  crude 
material  by  these  operations  amounts  to  about  5  per  cent.    The  purified  paraffin  is 
next  allowed  to  remain  in  a  very  cool  place  for  some  three  or  four  weeks;  after 
which  the  nearly  solid  mass  is  filtered,  then  submitted  to  the  action  of  centrifugal 
macliines,  and  finally  strongly  pressed.     The  oU  which  is  separated  from  the 
paraffin  is  again  distilled,  yielding  paraffin  oU  and  paraffin  butter.  The  solid  paraffin 
is  molten,  cast  into  blocks,  and  these  submitted  to  very  powerful  hydraulic  pressure. 
The  pressed  cake  is  next  treated  at  180°  with  10  per  cent  of  sulphuric  acid  for  two 
hours,  then  washed  with  hot  water,  again  cast  into  blocks,  again  pressed,  and 
then  washed  with  a  solution  of  caustic  soda.    Instead  of  treating  the  paraffin  with 
active  agents,  it  has  been  proposed  to  use  neutral  solvents  for  the  removal  of  the 
oily  materials;    for  this  purpose,  benzol,  light  tar  oils,  benzoline,  and  sulphide 
of  carbon,  have  been  employed  in  the  following  manner: — ^The  crude  paraffin 
is  first  hot-pressed,  and  the  pressed  mass  fused  with  5  to  6  per  cent  of  the  solvent ; 
having  been  again  cast  into  blocks,  these  are  pressed,  and  the  operation  repeated  if 
necessary.    The  paraffin  having  thus  been  made  quite  white  and  pure,  is  again  fused 
and  treated  with  high-pressure  steam,  forced  into  the  molten  mass  for  the  purpose  of 
volatilising  the  last  traces  of  the  solvents.    The  sulphide  of  carbon,  first  employed 
by  Alcan  (1858)  for  refining  paraffin,  is  used  in  the  following  manner : — The  paraffin 
is  melted  at  the  lowest  possible  temperature,  then  well  mixed  with  10  to  15  per  cent 
of  sulphide  of  carbon,  after  which  the  cooled  and  solidified  mass  is  strongly  pressed, 
the  expressed  fluid  being  submitted  to  distillation  for  the  purpose  of  recovexing  the 
sulphide  of  carbon.    The  paraffin  is  next  fused  and  kept  in  liquid  state  for  some 
time  for  the  purpose  of  eliminating  the  adhering  sulphide  of  carbon. 
SSSSSs'SSSi'      Instead  of  following  the  preceding  method  with  the  crude  tar, 
Hiibner  treats  it  first  with  sulphuric  acid,  and  next  distils  the  tar,  separated  from  the 


ARTIFICIAL   LIGHT. 


691 


acid,  over  quick-lime.  The  crndd  paraf&n  obtained  is  pressed,  and  then  farther 
refined  by  treating  it  with  colourless  brown-coal  tar  oil.  The  advantages  of  this 
method — ^by  which  one  distillation  is  saved — are : — 

a.  A  larger  yield  of  paraffin. 

/9.  A  material  of  better  quality  and  greater  hardness  than  by  the  usual  method. 

With  the  paraffin  the  so-called  paraffin  oils  are  obtained;  but  this  industry 
has  been  greatly  crippled  by  the  extensive  importation  of  paraffin  oils  (really 
petroleum  oils)  from  America,  so  that  the  aim  of  the  paraffin  makers  is  to  increase 
the  yield  of  paraffin.  By  Hiibner's  method  of  distillation  over  quick-lime, 
40  to  50  per  cent  of  impurities  (chiefly  empyreumatic  resins  and  creosote)  are 
removed,  which  by  the  old  process  are  only  got  rid  of  at  greater  expense  by  the  use 
of  caustic  soda. 

Yield  of  PazaAn.  As  regards  the  yield  of  p&raffin,  paraffin  oil,  and  lubricating  oil,  from 
the  various  kinds  of  raw  materials,  we  quote  the  following  particulars.  At  the  Ber- 
nuthsfeld  works,  near  Aurich,  the  excellent  peat  yields  6  to  8  per  cent  of  tar ; 
20  per  cent  of  paraffin  oil,  of  sp.  gr.  =  0*830 ;  and  075  per  cent  of  paraffin.  H.  Vohl 
obtained  from  100  parts  of  peat-tar  from  the  peat  of  undermentioned  localities : — 


Celle  (Hanover) 

Coburg       

Damme  (Westphalia) 
Zurich  (Switzerland) 

Russia        

Westphalia       


Paraffin  Oil. 
Sp.gr.,  0-820. 

3460 

20*62 

1945 
1440 

2o*39 

II'OO 


Sp.  gr.,  o- 

860. 

Paraffin. 

36*00 

8*01 

26*57 

312 

19*54 

3*31 

8*66 

042 

20*39 

3-36 

19-48 

2-25 

Brown-co«].  In  the  works  situated  in  the  Weissenfels  brown -coal  mineral  district, 
I  ton  ( =  275  to  300  lbs.)  of  the  mineral  yields  35  to  50  lbs.  of  tar.  100  lbs.  of  this 
tar  yield  8  to  10  lbs.  of  hard  paraffin  suited  for  candle-making,  and  further  8  to  10 
lbs.  of  soft  paraffin  for  use  in  stearine-candle  making,  as  well  as  43  lbs.  of  paraffin 
oil.  Hiibner's  works  at  Rehmsdorf,  near  Zeitz,  yield  annually  from  360,000  cwts. 
of  brown-coal  about  40,000  cwts.  of  tar,  yielding  18.000  cwts.  of  crude  oil, 
4000  cwts.  of  refined  paraffin  oil,  and  6000  cwts.  of  paraffin. 

100  parts  of  retort-tar  (in  contradistinction  to  steam-tar)  from  brown-coal  yield: — 

Lubricating  oil. 
Sp.  gr.,  0*860. 

40*00 


Brown-coal  from — 


u 


»f 


f« 


f< 


Aschersleben,  Prussia 

Frankenhausen 

Miinden 

Oldisleben 

Oassel 

Der  Rhon,  Bavaria 

Tilleda.  Prussia 

Stockheim,  near  Diiren 

Bensberg,  near  Cologne 

Tscheitch,  Anstro-Hungary ... 

Eger 

Herwitz 

Schobritz 


tf 


» 


II 


»> 


>» 


Paraffin  pU. 
Sp.  gr.,  0*820. 

33*50 

33'4i  4006 

17*50  26'2I 

I7"72  2660 

i6'42  27' 14 

1062  1937 

i6-66  1805 

17-50  2663 

16-36  19*53 

9*04  28*86 

9*14  54-00 

22*00  48*32 

21*68  4633 


Paraffin. 


V 


33 
67 

50 
4*4 
4*2 

I'2 

44 

3"2 

34 

32]. 

5-2 1 

5-2| 

4*3^ 


Analysed  by 
Vohl. 


Analysed  by 
C.  Muller. 


699  CHEMICAL  TECHNOLOGY. 

Ramdohr  obtained  (1869)  from  steam-tar  from  brown-coal  on  an  average-—' 

«  to  =H  per  cent  paraffin  j  ^  J5  per  cent  fusing  at  56;  to  g- J  ^^ 
36  to  38  per  cent  of  oil. 

With  carefal  management  steam -tar  may  yield  28  to  30  per  cent  paraffin. 

The  quotations  of  the  yield  from  cannel  and  Boghead  coals  vary  veiy  mncb. 
100  parts  of  tar  from  bitnminous  shale  were  fonnd  to  yield : — 

Mineral  oil.  Lubricating  oiL  ParaiBiLi 

English  bituminous  shale 24*28  40*00  0*12 

Bituminous  shale  from  Romerickberg,  Prussia      25*68  43 'oo  '  oii 

Westphalia  „  2750  13*67  i*ii 

Oedingen  on  the  Hhine  „  18*33  38*33  S'oo 

According  to  Miiller  (1867),  100  parts  of  Galician  mineral  wax  (ozokerite)  yield 
24  per  cent  of  paraffin  and  40  per  cent  of  oil. 

Properties  of  Paimffln.  Pure  paraffin  is  a  white,  wax-like,  tasteless,  and  inodorous  sub- 
stance, with  a  slightly  fatty  appearance.  Its  sp.  gr.  is  0*877.  ^*  ^^  harder  than  tallow, 
but  softer  than  wax.  Its  properties  vary,  however,  according  to  the  raw  materials 
from  which  it  has  been  obtained.  Paraffin  from  Boghead  coal  has  been  obtained, 
after  melting,  in  a  very  crystalline  state,  and  with  a  fusion-point  at  45*5^ ;  while, 
again,  it  has  been  obtained  granular  as  bleached  wax,  with  a  fusion-point  of  52*- 
Paraffin  from  Rangoon  oil  was  found  to  fuse  at  61^,  and  that  from  peat  at  46*7''.  The 
paraffin  from  the  tar  of  Saxony  brown-coals  fuses  at  56°,  and  the  oil  paraffin  at  43^. 
The  native  paraffin  from  ozokerite  fuses  at  6$'^'''  ^®  composition  of  the  yariouB 
kinds  of  paraffin  is: — 

From  Peat.      peSSS«. 


From  Saxony 
Brown-ooal. 

From 
Ozokerite. 

From  Boghead 
mineral. 

Carbon   ...    8502 

85-26 

8500 

Hydrogen  .    14*98 

1474 

•      1536 

84*95—85-23      85*15 
1505—1516      15*29 

From  these  figures  the  conclusion  may  be  drawn,  contrary  to  the  view  generalLr 
adopted,  according  to  which  all  varieties  of  paraffin  sliould  be  mixtures  of  hydro- 
carbons constituted  as  CnHn  (whether  the  paraffin  be  obtained  from  brown-coal,  peat, 
ozokerite,  or  petroleum),  that  paraffin  is  a  mixture  of  hydrocarbons  homologous  with 
maxsh-gas,  many  of  which  contain  no  less  than  C27.  Paraffin  is  insoluble  in  water, 
but  soluble  to  some  extent  in  boiling  alcohol ;  100  parta,  however,  dissoWe  when 
boiling  only  3  parts  of  paraffin.  Paraihn  is  soluble  in  ether,  oil  of  turpentine*  oil  of 
olives,  benzol,  chloroform,  and  sulphide  of  carbon.  Paraffin  boila  above  300% 
and  may  be  distilled  wit]iout  undergoing  any  alteration.  Adds,  alkalies^  and 
chlorine  do  not  at  all  act  upon  paraffin  at  the  ordinary  temperature ;  but  when 
chlorine  is  caused  to  pass  into  molten  paraffin,  hydrochloric  acid  is  evolved  and 
chlorinated  products  formed.  Paraffin  may  be  frised  with  stearine,  palmitine, 
and  resins  in  all  proportions.  Paraffin  is  used  for  making  candles  (see  p.  630U  bat 
has  been  employed  now  and  then  as  a  lubricating  material;  also  for  preaerving 
timber;  for  rendering  wine  and  beer  casks  water-tight ;  for  the  purpose  of  preventing 
the  foaming  and  boiling  over  of  the  sugar  solutionB  in  the  vacuum  pans  at  the 
beginning  of  the  ebuUition.  It  has  been  suggested  to  use  paraffin  for  preserriag 
meat ;  for  waterproofing  fabrics  (Dr.  Stenhouse^s  process ) ;  for  use  instead  of  wax 


ARTIFICIAL  LIGHT,  693 

for  waxing  paper  (employed  in  pharmacy  under  the  name  of  charta  eerata) ;  instead 
of  stearic  acid  for  soaking  plaster-of-Paris  objects.  Finally,  paraffin  is  used  in  the 
manufacture  of  the  better  varieties  of  matches,  as  a  waterproof  varnish  for  coating 
the  phosphorus  composition ;  and  in  chemical  laboratories  to  replace  oil  in  the  oil- 
baths. 

Fuafin  oa.      As  already  mentioned,  the  dry  distillation  of  Boghead  mineral,  brown- 
coal,  peat,  and  bituminous  shales,  yields  tar,  the  quantity  of  wliich  varies  according 
to  the  nature  of  the  raw  material  and  other  conditions,  mode  of  distillation,  degree 
of  heat,  &c.    As  regards  the  natiire  of  tar  we  cannot  say  that  it  is  fully  elucidated. 
Until  the  year  1830,  tar  was  considered  to  be  simply  a  solution  of  empyreumatic 
resins,  rich  in  carbon,  in  empyreumatic  oil  or  oils,,  the  nature  of  these  substances 
being  left  undecided.    The  late  Baron  von  Reichenbach  was  the  first  who  seriously 
investigated  the  nature  of  tar,  and  the  result  was  the  discovery  of  paraffin  and 
of  eupion,  a  very  volatile  liquid,  highly  inflammable,  and  found  to  boil  at  47**  to  169°, 
consequently  a  mixture  of  various  substances.    Notwithstanding  the  high  merits  of 
Reichenbach's  researches,  the  constitution  of  tar  was  not  fully  elucidated.     In 
an  industrial  point  of  view  tar  has  many  important  applications,  especially  for  the 
preparation  of  illuminating  materials ;  for  by  a  rectifying  and  fractioned  distillation, 
tar  yields  paraffin  and  paraffin  oils,  when  the  heavy  oils  and  acids  have  been 
previously  separated.    Paraffin  oils — ^met  with  in  the  trade  under  various  names, 
such  as  solar  oil,  photogen  oil,  ligroine  oil,  &c. — are  very  similar  to  petroleum  oils, 
and  consist  like  them  of  carbon  and  hydrogen,  and  are,  when  thoroughly  rectified, 
almost  colourless  and  &ee  from  smell. 

The  mineral  oils  now  met  with  in  commerce  are  distinguished  as: — Photogen, 

prepared  in  Saxony,  and  consisting  of  a  mixture  of  oils  boiling  between  100''  and 

300"*.     It  is  a  colourless,  very  mobile  fluid,  exhibiting  a  characteristic  ethereal  smell, 

and  a  sp.  gr.  of  o'8oo  to  0810 ;  but  the  sp.  gr.  of  its  constituent  oils  varies  from  076  to 

0*86.    Formerly  there  were  met  with  in  the  trade  light  photogens  of  a  sp.  gr.  of  078, 

consisting  chiefly  of  a  so-called  essence,  of  072  sp.  gr.  and  boiling  below  60° ;  but  this 

oil  was  found  to  be  too  inflammable,  and  is  now  used  as  benzoline  (also  known  as 

naphtha,  ligroine,  Canada  oil,  &c.)  in  the  sponge-lamps,  and  for  other  purposes. 

Solar  oil,  or  German  petroleum,  is  a  colourless  or  faintly  yellow-coloured  fluid  of 

about  the  same  consistency  as  colza  oil,  and  of  a  sp.  gr.  of  0830  to  0*832.    The 

boiling-point  lies  between  255°  and  350'';  cooled  to  —10*'  it  should  not  deposit 

paraffin,  while  its  vapour  is  not  inflammable  below  100**.     Pyrogen  is  a  kind  of 

paraffin  oil  invented  by  Breitenlohner  and  prepared  from  residues  of  crude  oils  which 

contain  carbolic  add,  paraffin,  and  other  substances,  and  exhibit  a  sp.  gr.  of  0*895 

to  o'945  ;  these  materials,  which  accumulate  in  tar-works,  are  converted  into  pyrogen 

by  a  process  presently  to  be  described,  yielding  a  light  straw-yellow  oil  of  0*825  ^ 

0*845  sp.  gr.    Engine-oil,  or  lubricating  oil,  also  known  as  Vulcan  oil,  is  a  thickly 

fluid  oil  imported  in  large  quantities  from  the  United  States,  and  which  deposits, 

when  submitted  to  cold,  a  large  quantity  of  crystals  of  paraffin.    This  oil  is  obtained 

largely  in  the  paraffin  oil  and  petroleum-refining  works.    According  to  A.  Ott's 

account,  the  American  lubricating  oil  is  not  obtained  by  distillation,  but  simply  by 

defecating  a  specifically  heavy  native  petroleum  with  charcoal  so  as  to  eliminate 

the  colour.    This  lubricating  oil  is  sometimes  mixed  with  a  certain  percentage  of 

vegetable  or  animal  fats.    The  oil  is  largely  used  for  lubricating  cotton-spinning 

machinery,  but  notwithstanding  its  extensive  employment,  the  production  £Eur  exceeds 


€04  CHEMICAL  TECBN0L0G7. 

the  consumption ;  it  should  be  as  much  as  possible  re-converted  into  paraffin  oil  and 
pyrogen.  In  America  and  on  tlie  Continent  a  large  quantity  is  employed  for 
making  gas. 

prtputition  of  Mineni  00.  The  manufacture  of  these  oils  is  a  collateral  industry  with  the 
manufacture  of  paraffin.  The  products  of  the  distillation  of  tar  are  first  treated  with 
a  solution  of  caustic  soda.  Tliis  operation  aims  at  the  removal  of  carbolic  and  acetic 
(pyroligneous)  acid  compounds,  which  impart  to  the  oil  a  disagreeable  odour  and 
dark  colour.  The  quantity  of  soda  to  be  used  may  vary  from  5  to  6  or  even  20  per 
cent,  and  the  operation  requires,  in  some  instances,  the  aid  of  heat  for  about  two 
hours,  while  in  others,  again,  the  end  is  attained  in  two  minutes  and  at  the  ordinary 
temperature  of  the  atmosphere.  ,  The  mixture  of  soda  ley  and  other  substances  is  then 
run  into  a  large  tank  for  the  purpose  of  depositing  the  soda  ley  and  combined  com- 
pounds, which,  when  settled,  are  run  off,  and  tlie  oU  washed  with  water  until  it  has 
become  free  from  alkali.  The  oU  is  next  treated  with  sulphuric  acid  of  17  sp.  gr., 
the  quantity  of  which  may  vary  from  5  to  25  per  cent,  wliile  the  duration  of  the 
operation  may  vary  from  one  minute  to  three  hours.  The  treatment  with  sulphoiie 
add  greatly  influences  the  quality  of  the  oil,  because  it  might  happen  that,  by  this 
treatment,  oils  originally  free  from  sulphur  would  become  impregnated  therewith, 
in  consequence  of  the  fact  that  the  more  volatile  portions  of  these  oils  are  essentially 
mixtures  of  aldehydes  and  ketones,  bodies  which  readily  combine  with  sidphurons 
,  acid.  The  mixture  of  oil  and  sulphuric  acid  is  run  into  a  tank  for  the  purpose  of 
depositing  the  specifically  heavier  portions  of  the  liquid ;  the  supernatant  lighter 
oil  is  afterwards  tapped  off,  and  washed  with  plenty  of  water,  then  with  weak  caustic 
soda  ley,  being  finally  rectified  by  distiUation.  According  to  H.  Vohl,  paraffin  oils  are 
sometimes  bleached  with  hydrofluoric  acid,  whereby  fluorine  compounds  are  stated 
to  be  formed,  which,  on  burning  the  oil,  give  off  noxious  vapours.  The  alkaline  and 
acid  liquors  used  in  tlie  operation  are  utilised  in  the  following  maimer : — ^The  erode 
alkaline  carbolic  acid  liquor  is  saturated  with  sulphuric  acid,  and  crude  carbolie 
acid  obtained.  The  latter  is  used  for  various  purposes,  among  which  are  the 
creosoting  of  timber,  for  disinfecting,  &c. ;  or  it  is  used  for  preparing  pyrogen  by 
causing  the  vapours  to  pass  through  a  red-hot  tube,  the  condensing  product  being, 
after  treatment  with  soda  ley  and  sulphuric  acid,  as  well  fitted  for  burning  in  lamps 
as  paraffin  oil.  Perutz  submits  the  alkaline  liquid  containing  carbolate  of  soda  to 
distillation  in  an  iron  still,  pushing  the  operation  on  to  dryness,  and  obtaining  a 
mixture  of  carbolic  acid  with  light  fluid  hydrocarbons.  If  it  is  desired  to  prepare  pure 
carbolic  acid,  the  liquid  which  comes  over  between  140^  and  240**  is  separatelf 
collected  and  treated  in  the  ordinary  manner.  The  residue  left  in  the  stOl^  a  mixture 
of  alkalies  and  coke,  is  calcined,  the  ash  lixiviated,  and  the  resulting  liquor 
causticised  \nth  lime.  Tlie  sulphuric  acid  is  employed  for  preparing  sulphate  of 
iron.  The  rectification  of  the  oils  is  performed  in  the  ordinary  manner.  100  parts 
of  peat  tar  yield  of  rectified  products : — Solar  oil  of  0*865  ^P*  S****  ^^'4  *  photo^n. 
0*830  sp.  gr.,  207 ;  paraffin,  23*3 ;  crude  carbolic  acid"  (peat-tar  creosote),  ii"0 
parts.  100  parts  of  Saxony  brown-coal  tar  yield  on  an  average : — Paraffin.  10  to  15; 
photogen,  16  to  27;  solar  oil,  34  to  38;  creosote,  5  to  10;  coke,  15  parts.  The 
commercial  value  of  these  articles  fluctuates  and  depends  on  the  demand  and  supply* 
There  were  prepared  in  1870  in  Prussia  from  $k  miUions  of  cwts.  of  brown-coal  in 
sixty-seven  different  works,  100,000  cwts.  of  paraffin  and  250,000  cwts.  of  mineral  or 
paraffin  oil. 


ARTIFICIAL  LIGHT,  695 

Petroleum. 

'tti'oeSw^e*"*      Siiice  the  year  1859  native  petroleum  has  become  a  most  important 
iUnminating  material.    Petroleum  was  known  to  the  ancients  and  was  used  by  them 
for  various  purposes.    Greece  obtained  it  from  the  Island  of  Zante ;    and  the 
petroleum  from   Agrigentum  was  burnt  in  lamps  under  the  name  of  Sicilian  oil. 
The  inspissated  oil  which  was  used  under  the  name  of  mineral-pitch,  or  asphalte, 
as    a    cement  in  building   Babylon,   was  obtained  from    the   neighbourhood  of 
the  River  Euphrates.     Mineral  pitch  was  uded  by  the  ancients  for  embalming 
their  dead,  while  it  would  appear  that  some    black-coloured    earthenware    was 
prepared  with  asphalte  gently  burnt  in.     In  some  parts  of  Central  Asia  large 
quantities  of  inspissated  petroleum  occur,  and  the  Dead  Sea  is  especially  a  locality 
where  this  substance  is  met  with ;  hence  ihe  name  of  lacvs  asp Jialtites^  In  the  Island  of 
Trinidad  a  large  lake  (Pitch  Lake)  occurs,  filled  with  mineral  pitch,  which  according 
to  the  prevailing  temperature  is  more  or  less  soft.    Petroleum  is  found  in  a  great 
many  localities  in  different  parts  of  the  world — ^Amiano,  near  Parma,  where  this  oil 
has  been  used  for  burning  in  street  lamps;    Tegemsee,  Bavaria,  the  oil-spring 
having  been  known  since  1430,  but  yielding  only  42  litres  annually ;  Neufch&tel, 
Switzerland ;  Sehnde,  near  Hanover ;  Kleinschoppenstedt,  Brunswick ;  Bechelbronn, 
Alsace ;  Coalbrookdale,  England ;  in  the  Pyrenees,  and  other  portions  of  Spain  and 
France ;  also  in  Galicia.    In  far  larger  quantity  petroleum  occurs  on  the  Caspian 
seaboard  at  Apscheron,  and  especially  on  the  Island  of  Tschellekan  (39^°  N.  lat.), 
where  more  than  3400  sources  are  found,  which  yield  annually  54,000  cwts.  of 
petroleum.    At  Rangoon,  in  Burmah,  petroleum  occurs  in  such  lai'ge  quantity  that 
annually  400,000  casks,  weighing  6  cwts.  each,  are  exported  thence.    But  in  no 
country  is  petroleum  found  in  such  inexhaustible  quantity  as  in  the  United  States, 
in  a  tract  parallel  to  the  Alleghany  mountains,  and  extending  from  Lake  Ontario 
into  the  Valley  of  the  Kanawha,  in  Virginia.    The  oil  region  includes  the  western 
counties  of  the  State  of  New  York  and  Pennsylvania,  and  part  of  Ohio.    The  most 
important  petroleum-wells  are  at  Mecca  (Trumhall  Co.,  Ohio),  and  at  Titusville,  Oil 
City,  Pithole  City,  Rouseville,  McClintockville  (Venungo  Co.,  Pennsylvania,  the 
country  of  the  Seneca  Indians).    This  territory  is  termed  Oil  Creek.    The  wells  are 
bored  to  a  depth  of  22  to  23  feet :  some  wells  are  flowing  wells,  the  oil  being  yielded 
spontaneously;   other  wells  are  pumped.    In  Canada  petroleum  is  met  with  in 
different  localities ;  as,  for  instance,  at  Gaspe,  near  the  St.  Lawrence,  and  in  Lambton 
Co. ;  also  on  the  western  portion  of  the  peninsula  formed  by  the  lakes  Huron,  Erie, 
and  Ontario,  in  the  Enniskillen  district.    California  3rields  enormous  quantities  of 
petroleum,  which  occurs  also  in  many  parts  of  South  America,  and  in  the  islands  of 
Java,  Borneo,  and  Timor. 

^*^  StoSSSS**""  ^  regards  the  origin  and  formation  of  petroleum,  several  hypo- 
theses have  been  brought  forward.  According  to  some  the  formation  of  petroleum  is 
intimately  connected  with  the  occurrence  of  hydrocarbons  met  with — ^according  to 
the  observations  of  Dumas,  H.  Rose,  and  Bunsen — in  compressed  condition  in  many 
rock-salt  deposits,  from  which  they  are  set  free  either  in  the  state  of  gas  or  as 
naphtha,  when  the  salt  comes  into  contact  with  water  or  is  broken  up.  The  crack- 
ling salt  of  the  Wieliczka  mine  gives  off  marsh-gas ;  but  by  condensation  CH4  might 
yield  homologous  hydrocarbons,  C6H14  and  C7HZ6,  which  form  the  bulk  of  the  vola- 
tile pordons  of  petroleum  and  paraffin,  the  composition  of  the  latter  varying  between 


696  CHEMICAL  TECHNOLOGY. 

C^Tl^  and  C27H56.  The  association  of  petroleum,  rock-salt,  and  combustible  gases 
is  met  with  in  a  great  many  localities ;  as,  for  instance,  in  the  Bavarian  Alps,  in  Tus- 
cany, Modena,  Parma,  the  Carpatliian  mountains,  on  tiie  Caspian  Sea,  in  India,  and 
also  in  America.  According  to  another  view,  petroleum  is  the  product  of  the 
slow  decomposition  of  yegetable  and  animal  matter,  and  results  from  a  re-arrangement 
of  their  elements.  The  American  geologists  suppose  petroleum  to  be  due  to  the  diy 
subterraneous  distillation  of  accumulations  of  sea-plants  and  marine  animals,  and 
that  the  petroleum  is  forced  upwards  by  water,  always  present  in  the  bored  wells. 
Of  course  the  h3rpothe8is  involves  the  action  of  subterraneous  heat  at  great  depth, 
which,  according  to  existing  observations  on  the  increase  of  temperature  in  deep  coal 
mines,  reaches  the  boiling  temperature  of  vrater  at  8000  feet.  According  to 
Berthelot's  view  (1866),  there  should  be  formed  subterraneously,  from  carbonic  acid 
and  alkali  metals,  acetylides,  which  again  should  yield  with  aqueous  vapour  acetylen, 
GaHs,  which  in  its  turn  should  be  converted  into  petroleum  and  tar  products 

^SSuSea^^*  Almost  all  the  native  petroleums  require  to  be  refined  before  they 
can  be  used  as  illuminating  material,  the  mode  of  refining  differing  according  to  the 
nature  and  consistency  of  tlie  oil.  The  oils  met  with  at  Apscheron,  in  Russia,  and 
in  the  neighbourhood  of  Baku,  are  nearly  all  colourless,  and  can  be  directly  used  far 
burning  in  lamps  after  having  been  simply  rectified  by  distiUation.  The  Bangoon 
oU  contains  so  large  a  quantity  of  paraffin  that  it  has  at  the  ordinary  temperature 
the  consistency  of  butter,  and  is  therefore  employed  for  extracting  paraffin.  The 
native  petroleums  of  many  of  tlie  East  Indian  islands  contain  sulphur  oomponrnds, 
and  cannot  therefore  be  burnt  in  lamps  until  they  have  been  treated  with  caustic 
soda  and  sulphuric  acid,  and  rectified  by  distillation.  The  specific  gravity  of  the 
native  petroleums  met  with  in  Canada  and  the  United  States  varies  veiy  much; 
that  from  Venimgo  Co..  Pennsylvania,  has  a  sp.  gr.  of  o'8,  while  oils  in  other 
localities  have  a  sp.  gr.  of  0*85  to  0*9.  Gralicia  produces  large  quantities  of  native 
petroleum,  which  is  refined  in  some  twenty -two  works,  situated  near  Boiyslav  and 
Drohobicz  ;  while  a  large  quantity  of  parafiin  oil  is  obtained  as  a  by-product  of  the 
distillation  of  paraffin  from  ozokerite.  The  lighter  petroleums  yield  about  90  per 
cent  of  photogen  and  solar  oil,  but  the  heavier  kinds  yield  only  40  to  50  per  cent,  the 
remainder  being  tar.  The  methods  of  refining  native  petroleums  consist  in  treat* 
ment  ^vith  caustic  soda,  sulphuric  acid,  and  finally  fructioned  distillation. 

oonsuttiUon  of  Petroleum.  As  fiuT  ss  rescarches  havc  been  instituted,  all  the  native 
petroleums,  irrespective  of  consistency  and  specific  gravity,  are  mixtures  of  the 
higher  series  of  the  homologous  compounds,  of  which  marsh-gas,  CH4,  is  the  first 
term.*  Amyl  hydrogen,  hydride  of  amyl,  CjHza,  boiling  at  68%  and  hydride  of 
caproyl,  C6H14,  boiling  at  92'',  constitute  the  more  volatile  portion  of  crude  American 
petroleum;  these  bum  like  marsh-gas  with  a  faintly  luminous  flame.  The  con- 
stituents of  the  oil  used  in  lamps  are  represented  by  the  hydrocarbons  C7H16  and 
CiftHae*  The  higher  series  of  the  marsh-gas  group  exliibit  a  butter-like  consistency, 
and  are  composed  according  to  the  formula  C20H43  and  C27H56,  and  belong  to  the 
paraffins  met  with  in  petroleums. 

*  Bonalds  proved  in  1865  that  the  gases  evolved  from  crude  American  petrdenm  sit 
essentially  hydride  of  ethyl  (CaHe),  and  hydride  of  propyl  (CjHs),  which  aie  the 
second  and  third  terms  of  the  above  series.  The  researches  of  Fouqu£  (1869)  agree  with 
those  of  Bonalds,  for  he  found  that  the  gases  evolved  trora  petroleum  are  partly  a 
mixture  of  the  hydrides  of  propyl  and  butyl,  and  partly  a  mixture  oi 
a^d  hydride  of  ethyl. 


ARTIFICIAL  LIGHT.  697 

Tcebnoioffy  of  peitoiemn.  According  to  an  Act  of  CongTcss  crude  petroleum  may  not  be 
exported,  owing  to  its  high  degree  of  inflammability,  and  a  sample  of  every  cask  of 
petroleum  is  to  be  tested.  The  oil  ought  not  to  give  off  inflammable  vapours 
(liydride  of  butyl;  below  38"  C.  =  100°  F.  In  the  United  longdom,  as  elsewhere, 
legislative  measures  have  been  taken  in  order  to  insure  safety  in  the  petroleum 
trade.  Consequently  crude  petroleum  is  chiefly  refined  by  submitting  it  to  fractional 
distillation  in  order  to  separate  from  it  the  naphtha  of  0715  sp.  gr.  (the  benzoline  of 
the  shops),  which  begins  to  boil  at  60°.  Wiederhold  found  that  the  nai)htha  yields 
by  fractional  distillation : — 

486  per  cent  of  070  sp.  gr.  boiling  at      100°    (a) 

457  n  073        M  „  200''    {b) 

57  ♦»  o'fio       »  ♦.  above  200'    (c) 

(c)  is  refined  petroleum  ;  (a)  is  too  volatile  for  burning  in  lamps ;  (6)  maybe  used  in 
properly  constructed  or  sponge  lamps.  H.  Vohl  calls  petroleum  naphtha,  canadol 
or  Canada  oil,  and  applies  it  to  the  carburetting  of  illumijiating  gas ;  and  also  as  a 
solvent  for  caoutchouc,  colophonium,  mastic,  dammar,  copal,  amber,  shellac,  oils 
and  fats,  and  for  preserving  anatomical  preparations.  The  most  volatile  and  lightest 
portion  of  the  naphtha  (sp.  gr.  065,  boiling-point  between  40°  and  50°),  known 
as  STiericood  oil^  keroselen,  petroleum  etlier,  and  rhigolen,  is  used  as  an  anesthetic, 
and  applied  externally  in  neuralgia.  The  loss  fluid  petroleum  oils  are  used  as 
lubricating  oils  under  a  variety  of  names — Globe  oil,  Vulcan  oil.  Phoenix  oil,  &c. 
Crude  petroleum  is  used  as  fuel  in  the  llussian  nav}*,  in  steamers  on  Caspian  Sea, 
and  by  tlie  United  States  nav}'^  in  some  cases ;  it  has  been  tried  witli  success  in 
France  as  fuel  for  locomotive  engines.  Refined  petroleum,  the  parafiin  oil  of 
the  London  shops,  is  an  opalescent  fluid,  somewhat  yellow,  boiling  at  150",  not 
miscible  with  water,  alcohol,  and  wood-spirit ;  but  readily  miscible  with  ether,  oil  of 
turpentine,  and  sulphide  of  carbon.  Petroleum  dissolves,  especially  when  hot, 
asphalte,  elemi,  Venice  turpentine,  and  caoutchouc.  As  is  well  known,  petroleum  is 
largely  used  for  burning  in  lamps.  The  fluid  known  as  kerosine,  also  used  for 
burning  in  lamps,  has  a  sp.  gr.  of  078  to  0825.  ^^^^  ^^  seems  to  be  identical,  and 
both  are  prepared  from  American  petroleum  by  distillation.  As  a  great  confusion 
exists  in  tlie  names  of  tlie  various  distillation  products  of  petroleum,  we  quote  the 
following  particulars  communicated  by  Kleinsclmiidt,  of  St.  Louis : — 

060°     =  90*'— 97*  B.  =  Ehigolin. 
063 — 0*6 1  =  80" — 90°  B.  =  Gasolin. 
0-67— 0*63  =  70*— 80"  B.  =  Naphtlia. 
o 73 — 067  =  60°— 70^  B.  =  Benzine. 
078 — 0*82  —  40° — 60"  B.  =  Kerosen. 

At  higher  temperatures  paraffin  and  illuminating  gas  oome  over.  In  order  to  give 
some  idea  of  the  enormous  consumption  of  petroleum,  it  may  be  mentioned  that  the 
imports  in  the  German  Customs  Union,*  amounted  in  1866  to  918,954  cwts.,  and  in 
the  first  half-year  of  1870  to  1,260,630  cwts. 


Oils  distilling 

over  below 

377'  sp-  gr. 

I* 

at 

76-6-      „ 

» 

»» 

1370°      .» 

>» 

ft 

1480°      „ 

>» 

183°— 219**,, 

*  Embraces  all  the  States  of  Germany,  including  the  Grand  Duchy  of  Luxembourg, 
but  no  Austrian  territory. 


3M 


(698) 


DIVISION  vin. 

FUEL   AND   HEATIXO  APPARATUS. 


A.  Fuel. 

ro«i.  We  nnderstand  by  fnel  such  combustible  materials  as  may  be  bnnit  with  tbe 
view  of  obtaining  heat.  Wood,  peat,  brown-coal,  coal,  anthracite,  wood-charcoal, 
peat-charcoal,  coke,  petroleum,  combustible  gases,  such  as  carbonic  oxide  and 
hydrocarbons,  are  fuel.  Excepting  the  gases,  all  kinds  of  fuel  are  closely  related  to 
each  other  as  far  as  regards  their  origin,  because  fuel  consists  of  celluloBe  or  has 
been  formed  from  it.  Native  fuel,  coal,  wood,  peal,  anthracite,  consists  of  earbon, 
hydrogen,  and  oxygen,  with  larger  or  smaller  quantity  of  ash  (silica,  aluminav 
oxide  of  iron,  alkalies,  and  alkaline  earths),  and  as  regards  coals,  also  nitrogen, 
sulphur,  and  phosphorus.  Only  hydrogen  and  carbon  are  combustible  substances, 
and  these,  therefore,  determine  the  value  of  fuel  by  complete  combustion,  leaving 
only  ash,  water,  and  carbonic  add.  In  wood-ash,  carbonate  of  lime,  in  the  adi 
of  mineral  fuel,  alumina,  chiefly  prevail.    The  effect  of  fuel  depends  upon : — 

a.  Combustibility. 
h.  Inflammability. 
c.  Calorific  effect. 

oombiutibmty.  By  Combustibility,  is  understood  the  greater  or  less  readiness  with 
which  fuel  is  kindled  and  continues  to  bum  after  having  been  kindled.  ^This 
property  depends  upon  the  composition  of  the  fuel.  A  porous  fuel  kindles  more 
readily  than  a  denser  and  more  compact  fneL  With  regard  to  the  relation 
between  combustibility  and  composition,  it  has  been  foimd  that  the  more  hydrogen  a 
fuel  contains,  the  more  readily  it  bums. 

imunmuiboity.  By  the  inflammability  of  fuel  we  imderstand  its  property  of 
bursting  into  flame  when  kindled;  and  as  flame  is  due  only  to  burning  gases, 
it  is  evident  that  the  fuel  containing  most  hydrogen  is  that  which  bums  witii 
the  most  intense  flame.  In  the  case  of  coke,  charcoal,  and  similar  fuel,  there  can  be 
no  flame  other  than  that  due  to  the  formation  of  carbonic  oxide  owing  to  inoonq»Iete 
combustion. 

oaiorifk;  Effect  The  heat  evolved  by  the  complete  combustion  of  fuel  may  be 
measured  in  two  different  ways  ■ — 

1.  As  regards  the  quantity  of  heat  evolved. 

2.  As  regards  the  degree  of  temperature  or  intensity  of  the  heat. 


FUEL.  699 

'When  the  heat  evolved  is  measured  according  to  its  quantity,  we  obtain  the  com- 
bnstive  power,  the  specific  or  absolute  calorific  effect,  of  the  fuel. 

When  the  degree  of  heat  is  measured,  the  heating  power  or  pyrometrical  effect 

of   the  fuel  is  ascertained.     These   two    measurements  together   determine  the 

technical  value  of  a  combustible  material.    When  the  absolute  calorific  effect  of  a 

fuel  is  referred  to  its  cost,  we  determine  its  combustible  value  in  the  locality  where  it 

ia  to  be  consumed. 

cSSbSStSfpowt^.     As  we  do  not  possess  a  particular  measure  for  heat,  we  have» 

when  desirous  of  detennining  the  quantity  of  heat  yielded  by  a  fuel,  to  institute 

trials  for  the  purpose  of  ascertaining  the  relative  quantity  of  heat  evolved  by  various 

kinds  of  fuel,  in  order  that  by  comparison  we  may  find  how  much  more  heat  is 

evolved  by  one  kind  of  fuel  than  by  another.     If  the  results  thus  obtained  are 

referred  to  a  given  bulk  of  the  fuel  experimented  with,  we  obtain  its  specific  calorific 

effect ;  but  if  it  be  referred  to  a  given  weight,  we  obtain  the  absolute  heating  effect. 

The  following  table  exhibits  the  heat  of  combustion  of  several  substances: — 

Hydrogen yields  34,462  units  of  heat. 

Carbon  (when  completely  burned  and  yielding  oar- 

bonio  acid)      

Carbon  (when  yielding  carbonic  oxide)        

Carbonic  oxide 

Marsh-gas •.     

Elayl-gas 

Crude  petroleum       

Ether .. 

Alcohol       

Wood-spirit        

Oil  of  turpentine      

Wax 

Wood 

Wood-chareoal 

Peat 

Compressed  peat       

Coal  (anthracite)       

Fat      ..     .. 

The  absolute  heating  effect  is  determined  according  to  the  methods  of  Karmarsch 
and  of  Berthier,  or  by  elementary  analysis. 

'^■^"ISiS?^"*^  According  to  this  method,  applied  by  Dr.  Playfair  to  EngUsh 
coals,  by  Brix  to  Prussian,  by  Hartig  and  Stein  to  Saxony  coals,  the  quantity 
of  water  is  determined  which  i  lb.  of  the  fuel  will  evaporate.  According  to 
Kegnault's  formula,  652  units  of  heat  are  required  to  convert  i  kilo,  of  water  at  o** 
into  steam  at  150°.    Consequently — 

I  kilo,  of  carbon  can  evaporate  (^^  )   =12*4  kilos,  of  water. 

I  kilo,  of  hydrogen        „  (  Mdr?.  j  =  ^xg  „ 

\    652  / 

Experiments  instituted  by  Dr.  R  Wagner  and  others  gave  the  following  results: — 

Bed  beech  wood     378  kilos,  of  steam. 

Zwickau  caking  coal  (6*0  per  cent  ash)  6*45  9, 

Bohemian  coal  from  Nurschau  (iq'o  „        )  5*58  „ 

Forge  or  smith's  coals  from  Saarbriick  (21*5  „        )  606  „ 

Ruhr  coals  (55  „        )  690 

Cannel  coal  (4*0  „        )  774  „ 


ff 

8080 

tf 

^74 

»l 

2403 
13,063 

11,857 

ft 

"»773 

ft 
ft 

9027 
7183 

*ff 
ft 
tt 
>t 
tt 

5307 
10,852 

10,496 

3600 

7640 

tt 

3000 

t* 

tt 

4300 
6000 

tt 

9000 

TOO  CHEMICAL  TECHNOLOGY. 

^«**^«iJ;^Jy*^°°  According  to  the  law  of  Welter  (which,  however,  is  not  confinned 
by  experience,  since  recent  researches  have  proved  that,  especially  as  regards 
hydrogen,  great  deviations  from  the  law  exist),  the  quantities  of  heat  evolved  from 
different  kinds  of  fuel  are  relatively  proportioned  as  the  qaantity  of  oxygen  required 
for  their  combustion.  Assuming  tiiis  to  be  correct,  it  is  easy  to  ascertain  the 
absolute  calorific  effect  of  fuel  if  its  composition  is  known,  it  being  only  required  to 
calculate  the  amount  of  oxygen  which  will  effect  the  complete  combustion  of  the 
constituents  of  the  fael;  careful  account  being  taken  of  the  oxygen  it  contains. 
Practical  experience  has  proved  that  Berthier's  metliod  yields  results  which,  owing 
to  a  constant  error,  are  about  one-nintli  below  the  truth.  The  fuel  to  be  tested 
by  this  method  is  finely  pulverised,  and  i  grm.  is  mixed  with  a  quantity  of  lithar^ge 
slightly  more  than  required  for  the  complete  reduction  to  metallic  lead,  the  Tninimnm 
quantity  being  20,  and  the  maximum  40  grms.  This  mixture  is  put  into  a  fire-<!lay 
crucible,  and  covered  with  a  layer  of  20  to  40  grms.  of  litharge.  The  cracible  is 
covered  with  another  crucible  and  placed  in  a  charcoal  fire,  where  it  is  gradoally 
heated.  When  the  contents  of  tlie  crucible  are  fused  the  fire  is  increased  for  a  few 
minutes,  and  the  crucible  then  cooled  and  broken  up  in  order  to  obtain  the 
lead  button,  which  is  usually  clean.  This  experiment  has  to  be  repeated  with 
the  same  kind  of  fuel  two  to  tliree  times,  and  the  results  should  not  differ  from  each 
otlier  more  than  o*i  to  0*2  grm.  G.  Forchhammer  employs  instead  of  litharge  a  mix- 
ture of  3  parts  of  tliat  oxide  with  i  part  of  chloride  of  lead  (consequently  an  oxy- 
chloride  of  le$ui),  which  mixture  previous  to  use  is  fused  in  a  crucible,  and 
after  cooling,  pulverised.  Pure  wood-charcoal  yields,  when  ignited  with  litharge  or 
with  oxyohloride  of  lead,  34  times  its  weight,  and  hydrogen  1037  times  its  weight  of 
metallic  lead ;  the  hydrogen,  therefore,  rather  more  tlian  three  times  as  much  as  the 
charcoal  (carbon).  By  means  of  these  data  it  is  possible  to  estimate  the  absolute 
calorific  effect  of  any  kind  of  fuel.  As  i  part  of  carbon  can  by  its  combustion  raise 
the  temperature  of  8080  parts  of  water  1°,  and  as  pure  carbon  yields,  according 
to  Berthier,  34  parts  of  lead,  every  part  of  lead  reduced  by  the  fuel  under  examina- 
tion is  equivalent  to  f     ^  ^  J  =  237*6  units  of  heat.    The  application  of  Berthier*s 

method  is  suited  only  to  fuel  which  contains  but  a  small  quantity  of  hydrogen, 
owing,  as  already  observed,  to  the  incorrectness  of  the  law  of  Welter;  and  the 
method  is  not  applicable  to  fuel  which  becomes  decomposed  below  red  heat,  as  in  thia 
case  a  portion  of  the  gaseous  matter  evolved  does  not  react  upon  the  lead. 

Example :—  i  grm.  of  compressed  peat  yields  1776  grms.  of  lead,  equal  to  4x24*5  units 
of  heat  (since  237-6  x  1776  —  4124*5) ;  in  other  words,  i  kilo,  of  compie&sed  peat  yielda 

6'3  kilos,  of  steam  at  150°  (since  ^^^U  ;=  6*3). 

Elementary  Analysis.  Altliough  it  lias  been  provcd  that,  as  regards  isomeric  organic 
bodies,  tlie  quantity  of  heat  evolved  by  tlieir  combustion  is  not  precisely  proportional 
to  tlie  quantity  of  oxygen*  required  for  that  combustion ;  and  whereas  the  same 
quantity  of  oxygen  may  yield,  under  different  conditions,  different  quantities  of  heat, 
it  may  still  for  all  practical  purposes  be  assumed,  that  as  regards  fuel  of  the  same  or 
similar  composition,  the  results  of  elementary  analysis  give  the  means  of  ascer- 

•  The  composition  of  butyric  acid  and  of  acetic  ether  is  the  same,  and  is  expressed  by 
the  formula  C4HyO;i ;  yet  the  former  yields  on  combustion  5647  units  of  heat,  and 
the  latter  6292. 


FUEL,  7or 

taining  the  caloiific  value  of  such  fuel,  provided  tlie  quantity  of  ash  it  contains 
be  first  determined. 

Example : — i  grm.  of  compressed  peat  yielded  on  analysis  0*4698  grm.  of  carbon,  and 
0'0Z43  grm.  hydrogen,  equivalent  to  42887  units  of  heat ;  because —  * 

Carbon,      0*4698.       8080  =  3795*9 
Hydrogen,  0*0143.     34,462  =    492*8 

4288*7 
The  compressed  peat  contained — 

15-50  per  cent  of  hygroscopic  water,  and         )        «.^o  ^^^  ^^.  _  . 
3?*78         ..  chemicaUy  combined  water  }  ==  48*28  per  cent  water. 

Bequiring  for  evaporation  255-3  heat-units ;  hence  4288*7—255-3  =  4033*4  units  of  heat. 
The  evaporating  power  of  the  compressed  peat  is  therefore — 

4033*4 

=  6*19  kilos. 

652 

Btromayer'a  Teat.  According  to  this  method  (1861)  the  fuel  is  ignited  with  oxide  of  copper^ 
the  residue  treated  with  hydrochloric. acid  and  chloride  of  iron,  whereby  the  latter  is 
partly  reduced  to  protoohloride,  which  is  estimated  by  permanganate  of  potash.  This 
method  yields  very  correct  results,  but  is  rather  tedious. 

spMiflc  caioriflfi  Effect.  By  specific  calorillc  effect  we  understand  tlie  relative  quantities 
of  heat  evolved  by  equal  bulks  of  different  kinds  of  fuel.  The  specific  calorific  efiect 
is  obtained  by  multiplying  the  absolute  calorific  efiect  by  the  specifiq  gravity  of  the 
fuel  under  trial. 

PyrometxicaioaiorifleEfloet.  The  pyrometrical  calorific  efiect  of  a  fuel  is  that  indicated  by 
the  temperature  resulting  from  its  complete  combustion.  As  there  does  not  exist  any 
pyrometer  the  indications  of  which  are  sufficiently  reliable  to  be  converted  into 
thermometrical  degrees,  we  have  to  content  ourselves  for  the  present  with  a^ 
approximative  knowledge  of  the  pyrometrical  calorific  effect  as  deduced  from  calcula- 
tion. The  pyrometrical  effect  of  a  fuel  is  equal  to  the  heat-units  of  absolute  heating 
effect  divided  by  the  sum  of  the  relative  quantities  by  weight  of  its  products  of  com- 
bustion, each  of  these  quantities  by  weight  being  multiphed  by  the  corresponding 
specific  heat.  The  fiame-yielding  substances  of  the  combustible  matter  of  wood  and 
coals  are,  therefore,  possessed  of  a  lower  pyrometrical  effect  than  the  non-infiam- 
mable  carbonised  substances ;  while  in  reference  to  the  absolute  calorific  effect,  tlie 
reverse  obtains.  This  is  due  to  the  fact  that  the  aqueous  vapour  formed  by  the 
combustion  of  hydrogen  takes  up  nearly  four  times  as  much  heat  to  acquire  a 
certain  temperature  as  does  carbonic  acid.  The  difference  of  pyrometrical  effect  of 
fuels  is  far  greater  when  they  are  burnt  in  oxygen  than  when  they  are  burnt  in  air. 
In  order  to  approach  in  practice  as  nearly  as  possible  the  pyrometrical  effect  of 
theory,  it  is  necessary  to  bum  all  the  carbon  completely  to  carbonic  acid,  because 
the  temperature  of  its  combustion  to  carbonic  oxide  amounts  in  air  to  only  1427°, 
-with  2480  units  of  heat;  while  if  the  carbon  is  burnt  to  carbonic  acid  the  tem- 
perature rises  to  2458°,  with  8080  heat-units.  This  complete  combustion  may  be 
greatly  promoted  by  proper  treatment  of  the  fuel ;  for  instance,  by  keeping  wood- 
charcoal  and  coke  in  drying  houses  for  a  considerable  time ;  by  compressing  peat  to 
increase  its  density;  by  preparing  dense  coke;  heating  the  fuel  previous  to 
introducing  it  into  the  furnace ;  by  tlie  use  of  heated  air ;  and,  lastly,  by  effecting 
the  combustion  with  compressed  air. 
The  temperature  of  combustion  is  not  only  the  product  of  the  act  of  combustion 


t»  »t  »t 

»»  t»  tt 

»»  »>  »» 

ft  >t  >» 


702  CHEMICAL  TECHNOLOGY, 

itself,  but  is  essentially  modified  by  the  action  of  tJie  active  principles  of  tJie  air 
during  the  combustion.    For  complete  combustion  there  are  required : — 

For  1  kilo,  of  carbon,  at      15^    97  cubic  metres  of  air. 
„    I    „     „  hydrogen,  at  15%  280    „ 

From  these  data  we  deduce  the  following  quantities  of  air  as  required  for  the 
complete  combustion  of  the  subjoined  quantities  of  fuel ; — 

I  kilo,  of  wood  (with  20  per  cent  of  hygroscopic  water)  =  52  cubic  metres  of  air. 
I      „      wood-charcoal =  9*0 

^       }>       pit'Coai     •••     ...     ...     ...     ...     ...     ...     ...  ^^  9  o 

X        ,1        (/Oa6  ••.     ...     ...     ..•     ...     ...     ...     ...     ...  "—  9  o 

X       ff       orown~coaL       ...     ...     ...     ••.     ...     ...     •••  -^  y  ^ 

X       «}       pc&v   .••     ...     ■•.     ...     ..•     ...     ...     ...     ...  — •  y  ^ 

In  practice  on  the  large  scale  these  quantities  of  air  require  to  be  doubled  in  order 
to  obtain  complete  combustion. 

MechwdttO^EyuiYaient  rpho  law  of  the  conscrvation  of  energy  teaches  that  heat  can  be 
converted  into  labour,  and  inversely  labour  into  heat ;  and  that  i  unit  of  heat  corre- 
sponds to  424  metrical  kilos,  of  labour.  When  heat  does  work  it  is  dispersed  in  the 
proportion  of  424  units  of  work  for  i  unit  of  heat ;  consequently  the  number  424 
expresses  the  mechanical  equivalent  of  heat  By  a  foot-pound  is  imderstood  the 
force  required  to  lift  a  weight  of  i  pound  i  foot  high.  When  instead  of  the  pound 
the  kUo.,  and  instead  of  the  foot  the  metre  are  taken,  the  term  kilogranunetre  is 
employed.  1  kilogrammetre  =  637  Rhenish  foot-pounds ;  i  English  foot-pound  is 
equal  to  013825  kilogrammetre;  75  kilogrammetres  =  542  English  foot-piounds; 
I  horse-power  (33,000  pounds  lifted  i  foot  high  in  i  minute)  is  equal  to  760390 
kilogrammetres ;  i  unit  of  heat  per  English  pound  is  equal  to  $ths  of  a  French  cakurifie 
unit  per  kilo.  The  starting-point  of  tlie  mechanical  theory  of  heat  is  the  axiom  first 
put  forward  by  H.  Clausius,  that  "  in  all  cases  in  which  heat  does  work  a  propor- 
tional quantity  of  heat  is  dispersed  or  consumed,  and  inversely,  by  the  performaoca 
of  an  equal  amount  of  work,  the  same  quantity  of  heat  can  be  regenerated.** 

Wood. 

Wood.  Wood  consists  of  several  structurally  different  parts,  which  may  be  seen  in 
the  transverse  section  of  the  wood,  -^iz. : — The  axis,  or  pith,  a  rather  spongy, 
regularly  shaped  tissue  of  parenchyma  cells,  which  radiate  towards  the  bark.  Tbia 
is  surrounded  by  the  wood,  consisting  of  an  aggregation  of  bundles  of  vascular 
tissue.  The  wood  is  surrounded  by  the  bark,  and  between  wood  and  bark  is 
deposited  a  very  thin  layer  of  cells  filled  with  a  turbid  fluid,  from  which  the  fdrtiier 
growtli  of  the  tree  proceeds  by  the  gradual  deposition  of  newly  formed  cells  towards 
both  the  wood  and  bark  side.  The  bark  is  externally  covered  with  a  layer  of 
peculiarly  shaped  cells,  which  with  the  rind  form  the  bark,  covered  by,  in  young 
trees,  epidermis.  The  pith-cells  become  obliterated  in  old  trees,  and  leave  a  hollow 
tube.  The  wood-cells  become  thicker  by  the  deposition  of  cellulose,  and  as  tikis 
deposition  increases  in  spring  but  decreases  in  summer  and  autumn,  the  effect  is  the 
formation  of  the  so-called  annual  rings,  which  are  separated  from  each  other  by  the 
more  compact  and  harder  layers  deposited  in  autumn.  The  wood-cells  areintenially 
hollow,  and  are  separated  from  each  other  by  intercellular  meatus,  which  oontain 
usually  air,  but  sometimes  also  gum,  resin,  &c.    The  largest  quantity  of  cellulose  is 


FUEL. 


703 


deposited  in  the  wood  and  vascular  cells,  wliich  essentially  constitute  the  wood ;  tlie 
wood  is  the  harder  and  more  compact,  when  in  a  given  space  the  cellulose  is 
deposited  in  larger  quantity,  while  in  the  so-called  soft  wood  the  walls  of  the  cells 
are  thinner  and  their  number  smaller  in  a  given  space.  The  trees  of  which  the 
wood  is  used  as  fuel  in  Central  Europe  are : — 

Leaved  trees. 
Oak  (Quereits  peditnculnta  and  robtir)     ... 

"Red  heech  iFugtig  sylvatlcf I)    

White  beech  {Carpinus  hetulm)      

Elm  tree  ( Ulmus  eampestris  and  effusa)  . 

Ash  tree  (Fraxinu^  exeelsior) 

Alder  (Alnus  glutinosa  and  incana) 
Birch  (BetuUt  alba  and  puhescens) 

GoniferouB  trees. 

White  fir  {Pinus  abies)     

Ked  fir  (Scotch  fir)  (Pinuspicea)   

Common  fir  (Pintu  stflvestris) 

Larch  or  larix  tree  {Pintu  larix)   

Oak,  beech,  elm,  birch,  and  ash.  are  hard  woods.  Sycamore,  larch,  and  common 
fir  are  half -hard;  while  poplar,  lime  tree,  willows,  are  soft  woods, 
contitiieiits  of  Wood.  Wood  essentially  consists  of  woody  fibre,  small  quantities  of  ash 
and  sap,  and  a  variable  quantity  of  hygroscopic  water.  Woody  fibre,  or  cellulose, 
constitutes  about  96  per  cent  of  di'y  wood,  and  is  composed  of  C6HX0O5 ;  in  100  parts, 
of— Carbon,  44*45 ;  hydrogen,  6*17  ;  oxygen,  49*38.  The  vegetable  sap  consista 
chiefly  of  water,  but  contains  organic  as  well  as  inorganic  matters,  partly  in 
solution  and  partly  suspended.  The  inorganic  constituents  of  the  sap  (the  ash  left 
after  the  incineration  of  the  wood)  are  the  same  in  all  kinds  of  wood  (see  p.  123). 
In  practice  it  is  assumed  that  wood  leaves  about  i  per  cent  of  ash  ;  but  there  is  a 
difiTerence  for  certain  portions  of  the  tree,  the  trunk  yielding  about  1*23  per  cent  of 
ash,  the  branches  and  knotty  parts  1*34  and  1*54,  and  the  roots  2*27  parts  of  ash 
respectively. 

The  quantity  of  water  contained  in  wood  is  generally  larger  in  soft  than  in  hard 
woods.  100  parts  of  wood  recently  felled  are  found  to  contain  on  an  average  the 
following  quantities  of  water : — 


fit  for 

felling  in 

50 —  60  years. 

»» 

80 — 120 

♦» 

no — 120 

i» 

20 —  30 

?? 

20—  30 

>* 

20 —  30 

»i 

20 —  25 

ft 

50—  60 

t) 

70 —  80 

ft 

80 — 100 

a 

50—  60 

i8-6 

Common  fir 

308 

Red  beech 

347 

Alder     ... 

35*4 

Elm       ... 

37' X 

Red  fir  ... 

397 

397 
41*6 

44*5 
45*2 


'<D66CO        *••        .a.        ••.        •••       ... 

'^Ia  CU  ...  *.•  a*.  .a.  .aa 

V^MiH  >a.  ...  ...  ...  •••  ... 

Oak  (Queretu pedancvlata)  ... 
White  fir 

Air-diy  wood  may  be  considered  as  consisting  of : — 

40  parts  of  carbon  (inclusive  of  i  part  ash). 

40     „     „  chemically  combined  water. 

40     „    „  hygroscopic  water. 
Wood  dried  at  130'' — at  which  temperature  all  the  hygroscopic  water  18  driven 
off— is  composed  of: — 

50  parts  of  carbon  (inclusive  of  i  part  ash). 

50     „    „  chemically  combined  water. 


704  CHEMICAL  TECHNOLOGY, 

Aii'-dry  beech  wood,  as  used  for  fuel,  contains  in  loo  parts : — 

Cftrbon       *.     39*^^ 

Hydrogen 490 

Oxygen      36*00 

Water  and  ash 20*00 


lOOOO 

Hoatinu  v,jue  of  Wood.  The  licating  value  of  soft  wood  is  greater  tlian  tliat  of  hard 
wood.  The  wood  from  coniferous  trees  is,  on  account  of  the  resin  it  contains,  the 
most  readily  inflammable.  Birch  wood  is  very  similar  to  coniferous  wood.  Resinous 
woods  yield  the  longest  flame.  According  to  "Winkler's  researches  on  the  heating 
power  of  the  various  kinds  of  wood,  it  appears  ihat  for  1  klafter  of  red  fir  wood 
might  be  substituted  : — 1*07  klafter  of  lime-tree  wood.  094  klafter  of  common  fir, 
0*92  klafter  of  poplar,  0-91  klafter  of  willow  wood,  0*89  klafter  of  tanne,  0*70  klafter 
of  beech,  0'665  klafter  of  birch,  0*65  klafter  of  sycamore,  0*635  klafter  of  elm, 
o'59  klafter  of  oak.*  Scheerer  assumes  that  tlie  absolute  calorific  effect  of  the 
diflerent  varieties  of  uniformly  dried  wood  is  the  same,  and  that  tlie  speciiic  caloric 
eflect  of  wood  containing  the  same  amount  of  hygroscopic  moisture  is  proportionate 
to  the  specific  gravity.  The  pyrometiic  heating  eflect  of  kiln  half-dried  wood,  with 
10  per  cent  of  moisture,  is,  according  to  Scheerer,  =  1850°;  while  that  of  fully  kiln- 
dried  wood  is  =  1950".  According  to  Peclet,  tlie  combustion  of  clean  dry  wood 
evolves  a  temperature  of  1683°,  provided  tlie  oxygen  of  tlie  air  supplied  for  com- 
bustion be  all  consumed,  for  if  that  is  not  the  case,  or  only  half  the  oxygen  be 
consumed,  the  temperature  is  onl}'  960%  as  happens  in  stoves  of  the  ordinaiy 
construction. 

According  to  Brix's  investigations,  the  evaporative  power  of  diflerent  kinds  of 
wood  is  as  subjoined: — 

Fir  wood,  containing  water,  per  cent 
Elm  wood, 


ft  f) 

»»  f» 

?»  »» 

'»  »» 

»»  It 


Undricd. 

Dried. 

Per  cent. 

Percent. 

161 

413 

5" 

H7 

384. 

467 

I2'3 

372 

439 

187 

3*54 

4'6o 

22*2 

339 

463 

12*5 

362 

428 

Birch, 
Oak, 

Red  beech, 
White  beech, 

That  is  to  say.  i  Idlo.  of  fir  wood,  containing  16*1  per  cent  of  water,  evaporates 
4*13  kilos,  of  water. 

Wood  ctuuoooL  Nearly  all  organic  compounds  become  decomposed  by  heat,  and  leave 
carbon  if  access  of  air  is  prevented.  If  tlie  escape  of  gases  and  volatile  vapours 
evolved  when  wood  is  submitted  to  dry  distillation  is  permitted,  a  residue  is  left 
known  as  wood-charcoal.  Among  tlie  volatile  products  of  this  operation  are  gaseous 
substances,  such  as  carbonic  acid,  carbonic  oxide,  and  marsh-gas,  while  the  con- 
densable portion  of  the  volatile  products  consists  of  tar  and  an  aqueous  fluid.  This 
latter  consists  of  crude  pyroligneous  <acetic)  acid  (see  p.  469)  and  of  wood-spiiit 
The  tar  contains  a  large  number  of  fluid  and  solid  substances,  among  which  are 
paraffin,  creosote  (oxyphenate  of  meUiyl),  oxyphenic  and  carbolic  acids  (that 'is  to 
say,  true  carbolic  acid,  cresylic  acid,  and  phloiylic  acid),  and  several  hydrocarbons; 

*  A  klafter  is  a  cubical  measure  =  108  cubic  feet. 


all  these  Bubataneea  are  combnatible.    The  fbllowing  diagram  exJubite  the  chief 
piodactB  of  the  dry  diatillation  of  wood : — 

rAee^len. 
,  lUamiiiftting  1  E!la;l. 
gea.  1  Benzol. 


NaphthaUn  (?) 

i  Benzol. 
Naphth&Un  (?) 
Paramo. 
Ret«n. 
Carbolic  acid. 


Carbonic  oxide. 
Carbonic  acid. 
Marsh- gas. 
Hydrogen. 
Oifphenic  acid. 
CresjIJe  add. 
Phlorylic  acid. 
EmpTrenmatio  resina. 
Creosote. 


/.  Wood  charcoal. 
Wood  ia  earbouised  ohieflf  for  the  purpose  of  concentrating  tho 
fael  or  combustible  matter  it  contains,  to  obtain  a   more    readily  transportable 
material,  and  for  the  pnipose   of 
conrerting  the  wood  into  a  fiiel  for 
use  in  metollnrgical  and  technical 
proceases  in  which  wood,  aa  such, 
cannot  be  employed. 

Wood  may  be  carbonised  with 
the  sole  Tiew  of  making  tar  (Stock- 
holm tar),  or  with  that  of  making 
wood-gas  or  charcoaL  In  the  latter 
ease  the  wood  is  very  frequently 
carbonised  In  the  forests  where  it  is 
felled,  in  heaps,  pits,  or  ovens. 
cuAairiHUiui  la  A  regoluly  oon- 
Ba^L  ■tmcted  heap  of  blocks 
ol  timber  eoTered  with  a  layer  of  earth 
ud  oharcool-dait  is  formed,  the  wood 
being  placed  vettieally  or  horizon- 
tally Ks  regards  the  direction  ol 
the  aiiB  of  the  heap.  In  the  lint 
«au  the  heap  is  termed  a  "itand- 
ing,"  in  the  other  a  "laid"  heap. 
The  uii  is  a  pole  or  seTeral  poles  of 
wood. 
OnumMionsi  "^9  building  of  the 
tbt  liHf.  heap  ia  oommenoed  by 
DDtting  np  tiie  aiia  pole  or  poles. 
Vartioal  beapa  are,  aceording  to 
their  oonstmction,  diatingnisbed  in 
Oennany,  as  ; — a.  Walsh  heap,  Kg. 
Joi.  b.  Slaionian  heap,  Fig.  3U3. 
t.  Schwarten  heap,  Fig.  303. 

The  Walsh,  or  Italian  heap  (Pig. 
301)  ia  oonab^eted  with  a  hollow 
central  support  of  ploolis  or  stont 
laths,  kept  apart  from  each  other  by 
the  tnlks,  n.  The  heap  contains 
two  or  tlu'ee  layers  of  wood  and  ie 
eonlcal  in  shape.  The  layer  of  earth 
'""  "  '1  termed  Uie  chemise. 


IB  wood  ia  placed  for  kindling  the  pile. 


In  the  lower  part  of  the  hollow  pole  or  shaft 


7o6  CHEMICAL  TECHNOLOGY. 

The  Slavonian  heap  (Fig.  302)  is  distingniBhed  from  the  former  by  the  tad  that  tiie 
axis  is  a  solid  pole  and  oy  the  channel,  b,  by  means  of  which  the  wood  is  fired.  A  thirl 
kind  of  vertical  heap,  termed  the  Schwarten,  is  in  use  in  Norway,  the  name  being  denied 
from  the  word  **  Sohwarten,"  signifying  irregular.  Three  of  the  larger  logs  fonn  the 
central  pole,  aa^  round  which  light  combnstible  material  is  placed  for  the  pnrpose  of 
kindling  the  heap ;  while  the  blocks  of  wood  are  next  bnilt  up.  The  horizontal  heaps 
have  the  outward  appearance  of  the  former,  but  the  blocks  of  wood  are  placed  horizontally 
and  radially.  The  pole  or  axis  is  a  solid  shaft,  and  air  holes  or  channels  are  made  in  tli^ 
wood.  In  order  to  prevent  the  layer  of  earth  which  covers  the  heap  falling  in  and  choking 
the  progress  of  the  smouldering  fire,  a  layer  of  leaves  and  twigs  is  first  placed  on  the 
wood,  and  on  that  the  earth,  mixed  with  charcoal-dust.  At  first  the  heap  of  wood  is  not 
quite  covered  with  earth,  an  uncovered  space  of  some  6  to  12  inches  being  left  at  the  foot 
of  the  heap  for  the  purpose  of  admitting  air.  The  layer  of  earth  usually  has  a  thickness 
of  3  to  5  inches,  hut  at  the  top  it  is  thicker.  In  order  to  protect  the  heap  from  the  effects 
of  strong  wind,  it  is  usual  to  put  up  what  are  termed  wind-blinds,  simply  planks  of  wood 
placed  dose  together  and  supported  by  stout  poles. 

There  are  two  methods  in  use  for  kindling  or  firing  the  heaps  of  wood : — z.  Kmdiing  at 
the  bottom,  access  to  the  centre  of  the  heap  being  obtained  by  a  channel,  into  wbaeh 
ignited  straw  is  introduced.  2.  Ignition  from  the  top,  or  roof,  by  throwing  into  &e 
central  shaft  ignited  charcoal  and  wood-shavings. 

ohaTCoai Bnrninff .  We  havc  to  distinguish  three  stages  or  phases  in  this  operation:— 
I.  The  sweating.  2.  The  full  combustion.  3.  The  dow  smouldering.  In  order  that  the 
fire  may  spread  through  the  heap,  it  requires  at  first  a  more  plentiful  supply  of  air,  and 
for  that  purpose  the  heap  is  left  entirely  uncovered,  or  at  least  left  open  at  the  bottom. 
The  first  effect  of  the  fining  is  that  a  large  quantity  of  watery  vapour  and  products  of  diy 
distillation  are  formed  within  the  heap,  which  becomes  consequently  wet,  or  begins  to 
sweat.  During  this  time  there  is  the  risk  of  explosion  of  the  mixture  of  air  with  hydro- 
carbon gases  and  vapours,  by  which  explosion  the  overthrow  of  the  heap,  or  if  not  so 
•violent,  a  shaking  of  the  eovering  layer  of  earth,  may  take^laoe.  It  may  happen,  also, 
that  at  this  period  the  combustion  becomes  internally  so  active  as  to  completely  oonsnme 
more  or  less  of  the  wood.  Any  holes  which  may  be  observed  externally  are  at  once  filled 
up  with  earth,  grass,  wet  wood,  clay,  or  any  suitable  material.  When  the  vapours  issuing 
from  the  bottom  of  the  heap  become  brighter  in  colour,  complete  ignition  of  the  wood  has 
eommeneed,  and  it  then  becomes  necessary  to  prevent  the  access  of  air  by  eovering  the 
entire  heap  with  earth  mixed  with  charcoal-powder ;  this  operation  is  termed  the  eneom- 
passing  {umfoBgen)  of  the  heap,  which  is  left  in  that  condition  for  three,  four,  or  six  dvjtt 
the  high  temperature  being  sufi&oient  to  complete  the  carbonisation  of  the  wood  without 
further  access  of  air.  In  order  to  insure  the  complete  carbonisation  of  the  outer  portiooos 
of  the  heap,  the  combustion  must  be  carefully  conducted  from  the  top  and  oemtre  out- 
wards by  partially  removing  the  covering  layer  towards  the  bottom,  and  by  making  small 
channels  at  various  parts  of  the  covering,  an  operation  known  as  the  slow  smonldaing  or 
burning  off.  When  the  smoke  which  issues  from  the  channels  becomes  bright  and  bine- 
coloured,  the  charcoal  is  well  burnt,  and  therefore  the  channels  and  iq)eiture8  are  all 
dosed  with  earth,  in  order  to  extinguish  the  fire.  In  this  condition  the  heap  is  left  for 
twenty-four  hours.  Then  the  layer  of  earth  is  raked  off,  and  6xj  earth  thrown  on  the 
heap  for  the  purpose  of  filling  the  insterstices  between  the  still  red-hot  charooal,  which 
becomes  gradually  extinguished.  As  soon  as  the  heap  is  quite  cold  externally,  it  is  ooee  or 
twicegently  watered  by  means  of  a  watering-pot,  then  broken  up,  and  the  charooal  takm  ont. 

cubonitttion  in  B«dB.  This  modc  of  charcoal-buming  is  in  use  in  Southern  Q&maaj, 
Bussia,  and  Sweden,  and  is  a  continuous  operation  in  so  far  as  the  wood  is  gradual^ 
carbonised,  fresh  green  wood  being  added  while  the  charcoal  is  withdrawn.  The  wood  is 
sawn  into  logs  and  not  hewn  to  smaller  blocks.  The  oarbonisation-bed  is  a  reetangular 
wooden  box,  Figs.  304  and  305,  the  latter  being  a  vertical  section.  The  bed  is,  in 
fact,  a  kind  of  kiln,  of  which  a  a  are  the  poles  and  outer  logs,  h  the  eovering  layer  of 
earth,  h  the  hearth.  While  the  slow  combustion  proceeds  from  6  towards  the 
opposite  end,  the  charcoal  formed  is  gradually  withdrawn.  The  burner,  or  workman,  has 
to  see  that  the  combustion  proceeds  regularly  and  keeps  parallel  to  the  sides  of  the  bed. 

oubonimti^n  In  otcxxs      T^^  proccss  is  an  imitation  in  brickwork  of  the  earbonising  proeeeB 
orKiiiw.  in  heaps,  because  the  carbonisation  of  the  wood  is  effected  by  the 

combustion  of  a  portion  of  wood  of  the  heap.  The  oven,  or  kiln,  admits  of  a  more  perfect 
collection  of  the  products  of  the  dry  distillation — ^tar,  pyroligneoua  add,  <fto., — ^but  the 
eharcoal  is  not  quite  so  good  as  that  obtained  by  the  preceding  methods.  The  ahiqie  and 
mode  of  construction  of  these  kilns  may  vary,  as  will  be  presently  seen. 

Fig.  306  exhibits  one  of  the  most  simply  constructed  kilns.  The  wood  is  placed  either 
TorticaUy  or  horizontally,  being  thrown  into  the  kiln  through  the  opening,  a,  or  eaniBd  in 


tbrmtob  the  ioontMf,  b,  whioh  tiao  Benea  as  the  ahuinel  through  whieh  tba  firing  of  the 
wood  IB  performed.  Daring  the  ignition  all  the  apertarei  of  the  kiln  ore  oloaed  irith 
brickwork,  with  the  eioeptian  ot  anm&U  opening  at  6  and  at  a.  Tbesin»U  apntoies  teen 
•t  the  top  of  the  kiln  are  intended  tof  the  escape  of  the  antoke. 


In  the  kiln  exhibited  at  Fig.  307,  the  donrwavn,  a  ani  6,  are  intended  for  the  intro- 
dnetion  of  the  wood,  and  b  also  for  witlidrawing*the  charcoal,  ccc  are  dranght-hole* 
proTided  with  plnge.    The  iron  pipe,  if,  ia  intended  tor  carrying  off  the  volatile  proiuoti  of 


the  dry  diatiUatioD.  Dnring  the  operation  a  and  b  are  oloeed  with  briekwork  or  with 
tightly- fitting  iron  door»  lined  with  fire-claj  slabs.  The  tar  ii  collected  in  a  teserroir. 
Below  b  a  small  aperture  indicates  the  month  or  outer  opening  of  the  firing  channel. 


TbsldlD  repreeented  in  Fig.  308,  in  vertioal  section,  ia  oonstmated  tor  the  sdmiiuon  of 
aiz  throQgh  the  aab-pit,  f,  and  tire-bars,  r ;  the  wood  is  introduced  throngh  a  and  bi  qia 
the  pipe  for  carrying  off  the  volatile  prodacte. 


708  CHEMICAL   TECHNOLOGY. 

cubmiHUitBttirosd     TbeoftrbonisatioiiofwixidiBalioefleotedinaloBAdTMadi: — i.Bitort*. 

laoruifc  J,  In  tobss  or  cylinders,  heated  tit,  bUat-funiaoe  gMsa,  or  nqxi- 

healed  rteun  being  sometimeB  nmd  foi  the  purpose  of  MrboiUHiiig  the  wood.    As  rasaidi 

the  o&rboiuKBtioii  of  wood  in  retorts,  thii  ii  effsBtAd  by  pladng  the  wood  in  OMt-iiml 


awB;  the  voUtile  products  ( 


obtaining  tar  or  wood-gM.  In  the  c 
tabolai  kilns,  the  firing  of  the  wood  ii  effMited 
by  the  aid  of  a  aeries  of  iron  tubes,  placed  in 
the  Iriln  and  eonneoted  ontaide  with  *  aoarM 
of  heat  tt  well  m  with  a  ebimney- stalk.  'Hie 
hot  air  and  Qame  of  a  faroaoa  are  paned 
throQgh  these  tnbea,  or  may  be  directly  led 
into  Uie  kiln,  provided  the  hot  air  and  B*ms 
are  depriTed  of  their  oxygen.  Upon  thcca 
priudples  is  oonstrnoted  tiie  Idhi  iuvetited  by 
Sohwarz,  and  known  as  the  Swedish  kiln,  of 
which  Fig.  309  exhibits  a  vertioal  section,  h  i* 
the  carbonisatian  space  endoaod  by  the  laidt- 
work,  a.  Tbronsh  the  apmtnrea,  ce,  the  hot 
ftii  is  admitted  miioh  elfeelB  the  oarbonisatioD, 
Tho  liqnid  prodncts  of  the  dry  distillation  an 
collected  on  the  sloping  floor  of  the  kiln  add 
conreyed  by  means  of  the  sjphon-tnbee,  >', 
into  uie  tw-TeMels,  //.    The  Ti^ioiirt  <A  th* 


volatile  flojds  (pyroligneo 


tVEL. 


709 


Um  dravgbt  of  th«  mpjmnitaH.    Tbe  opeuingi,  id,  tMrre  tor  tb«  intradnctfoti  of  ths  wood. 
There  are  no  fii«-ban  in  the  heurth  of  Uub  Uln. 

The  earboniwtioii  of  wood  with  the  new  of  prodnciiig  tnr  U  bett  efleeted  by  tlie  method 
in  genenl  nw  in  Biuai>,  of  whioh  Heasel  has  givea  (1861)  the  foUowing  deaohption. 
Iba  wood,  generally  ot  oqniferoiu  trees,  is  oat  op  with  an  axe,  being  diatingniihed  a* 


Biwvican  and  Liuiina  the  former  wood  from  the  trunk  of  the  trees,  tb«  latter  the 
knotty  Tooti.  The  wood  is  heaped  np  on  a  plot  of  ground  Fig.  311,  whioh  is  somewhat 
elevated  above  the  level  of  the  soil  and  is  famiel  shaped  tlia  whole  being  oonstrncted  of 
olay  and  lined  with  roofing  tiies  on  which  the  tar  collects  and  flows  off  into  a  vessel 
placed  in  the  vanlt  as  exhibited  in  the  out  The  wood  is  heaped  in  di  to  ei^t  layers, 
mod  is  first  ooveied  with  ha;  or  dung  next  with  a  layer  of  a  few  inches  in  Uuekness  of 
aand  or  earth.     The  wood  m  the  heap  is  ignited  at  the  bottom,  where  forty  to  fifty 


Fia  311 


uwrtnrei  are  left  m  the  onvenng  these  apertnrea  being  dosed  with  wet  sand  as  mod  as 
the  eomhnstion  of  the  wood  beoomes  active,  and  has  spread  through  (he  whole  heap. 
After  about  ui  days'  uuoaldering,  the  top  of  the  heap  falls  in  and  a  strons  flame  bnnta 
out.  After  tan  to  twelve  days  the  tor  begins  to  collect  and  it  removed  daily.  The 
Bmonldering  of  the  wood  coutinaes  for  three  to  foor  weeks ;  the  quantity  of  charcoal 
obtained  is  very  small.  Aooording  to  TbenioB,  wood-tar  is  obtained  by  a  similar  prooaea 
In  Lower  Austria  from  the  wood  of  the  black  fir,  which  does  not  yield  turpentine  ;  but  in 
Bohemia  a  very  resinouB  wood  is  used  for  tar-making.  loo  puts  of  fir  wood  yield  in 
Bnsaia  17*6  ports  of  tar  and  ly^  parts  of  ohorooal. 

Since  the  year  1853  there  hog  been  in  use  in  Sweden  an  apparatus  for  the  distillBtlon  of 
tar  from  wood,  known  as  a  thermo- boiler.  According  to  Heesal'*  daseription,  thia 
apparatus  consists  of  a  boiler-shaped  iron  vessel,  k.  Fig.  31a,  of  aboat  8  cubic  metre* 
capacity,  and  Btted  with  a  man-hole  for  Introdncing  the  wood.  This  vessel  is  heated  by  a 
fin  at  a,  and  Uw  Sum,  bb.    In  order  to  hsat  the  wood  f^idly  to  too^,  a  jet  of  steam  ii 


710 


CBBMICAL  TBCBNOLOar. 


foToed  into  the  vmmI  through  e.  The  ttx  wbioh  might  colleot  and  eondense  in  the  Te«id 
is  oarriad  off  by  the  aid  of  the  pipe  e  to  b,  while  the  Taponra  of  tar  and  other  ToIatil« 
prodaeti  are  oonTeyed  throngh  d  into  b'.  The  matter  there  oondeiiBed  flaws  Ouoiigh 
A  to  B,  while  the  moie  volatile  prodnata  are  rendered  liqnid  ia  the  oondenaer,  c.  1^ 
eombiutible  gases  are  returned  to  the  fireplace.  In  additioo  to  tftr,  there  ara,  at  the 
oataet  ol  the  operation,  also  obtained  oU  of  turpentine  and  pjroligiieaas  acid.  The 
oharooal,  whioh  is  eitingnished  by  means  of  steam,  is  removed  from  the  boiler  by  the 
opening  a.  According  to  on  inveetigation  by  Thenina  (1S63),  with  the  view  of  asoertaining 
whether  the  tar  obtained  in  making  wood-gas  is  equally  fitted  for  naval  pnrposes  and  for 
boiling  down  to  pitch  as  the  tar  obtained  by  other  methods,  it  was  fonnd  that  saoh  is  not 
the  caao.  This  agrees  with  Dr.  Owden's  reaearohes,  made  at  hie  extenaTe  aoetio  a<ud  and 
wood-spirit  worlu  at  Snnderland,  where  the  tar  obtained  ia  bomt,  or  used  with  lima  and 


0  the  cheapiieas  of  ooal  in  the  loeali^. 


mMniaai  (aitieML  We  distingiuBh  between  hard  wood  and  soft  wood  charcoAl.  and 
as  regards  the  latter,  again  between  charcoal  obtained  from  leaf-bearing  lieea  and 
from  coniferous  trees.  According  to  the  degrees  of  carboniaation,  we  Hiatingnimh 
between  well-bnmt  black-coal  and  the  ao-called  ekarbon  roitx,  a  more  or  teas  deep 
brown  torrified  oharooal,  often  used  in  gnnpowder  making. 
According  to  tlie  size,  charcoal  is — at  least  abroad — divided  into : — 

1.  Coerae  log-coal,  the  largest  and  most  compact  lumps. 

2.  Forge-coid,  compact  Inmps  about  4  inches  diameter. 

3.  Coal  from  the  centre  of  the  heap,  small  lamps  and  porous. 

4.  Small  coal,  nnt  and  pebble-sized  lumps,  mixed  with  dust. 

5.  Raw  coal,  or  not  well-burnt  lumps. 

As  regards  the  yield  of  charcoal  by  bnlk,  this  may  be  referred  either  to  tiie  rMl 
volume  of  the  mass,  after  dedacdon  of  interstices  present  in  the  heap,  or  to  tht 
apparent  volume  without  that  deduction  being  made.    We  can  compare : — 

<i.  The  apparent  voltune  of  the  wood  with  the  apparent  volume  of  the  charcoal. 
b.  The  real  volume  of  the  wood  with  the  real  volume  of  the  chareoaL 
D.  The  real  volume  of  the  wood  with  the  apparent  volnme  of  the  charcoal. 

The  'first  method  may  be  called  the  production  according  to  the  apparent 
volume  (I.) ;  the  second,  the  yield  according  to  the  real  volume  (IL) ;  the  thud,  tbs 
yield  according  to  both  volumes  lIU.) : — 


»» 

»» 

>» 

1» 

it 

»» 

»» 

f* 

FUEL.  711 

Method  (I.)  gives  the  following  results : — 

Oak  wood    71*8 — 24*3  P^^  ^^^^  charcoal. 

Ked  beech  wood •     73*0 

Hirch  wood 68*5 

Dwarf  beech  wood  (as  grown  for  hedges  abroad)  57*2 

^ It  TV \jou      •••     •••     •••     •••     •••     •■•     •••     •••  03  o 

According  to  the  real  volume  (II.)  the  average  of  several  experiments  gave  a  yield 

of  47*6  per  cent.    According  to  both  volumes  (III.),  the  following  results  were 

obtained  at  Eisleben : — 

Apparent  Both 

Weight.  volume.  volumes. 

Oak  wood     21*3  per  cent     71*8  per  cent     987  per  cent 

Red  beech  wood 227  „  „  73*0  „  „  ioo'4 

Birch  wood '209  »,  „  685  „  »,  94*2 

Dwarf  beech  wood     ..^    ...  20*6  „  „  57*2  „  „  786 

Fir  wood      25*0  „  „  636  „  „  87*2 

.^'*"'*^SISmSiT°**'  Omitting  the  small  quantities  of  hydrogen  and  oxygen  present  in 
charcoal,  its  average  composition  in  air-dry  state  is  the  following : — 

Carbon    85  per  cent 

Hygroscopic  water       12 

^AiBU  •••       •••       •••       ...        •*.        •••        •»•  3 

^nliSS^if**  The  combustibility  of  freshly  burnt  charcoal  is  very  great,  for  it 
continues  to  bum,  with  proper  access  of  air,  when  once  ignited ;  but  as  charcoal 
does  not  contain  any  volatile  combustible  matter,  it  requires  a  great  heat  to  become 
ignited,  more  especially  as  it  is  a  very  bad  conductor  of  heat. 

The  heating  effect  of  various  kinds  of  wood-charcoal  is  shown  by  the  figures  of  the 
subjoined  table,  the  heating  effect  of  carbon  being  taken  as  the  unit : — 

S  B  f 

-        I        I  till  Ml ^8 


>r  tf 

I*  t> 

>»  «> 

»  9t 


»»      »» 


CO 


Well-burnt  charcoal,  air-dry    0*97  —  2450  —  ^ 

Well-burnt  charcoal,  quite  dry  ...  0*84  —  2350  —            "S 

Birch  wood         „                   „  ...  —  0'20         —  33  71  P« 

Ash  wood            „                   „  ...  —  0*19          —  —  r* 

Bed  beech  wood  „                   „  ...  —  o'i8         —  33'57 

Red  fir  wood       „                   „  ...  —  0*17          —  3351 

Sycamore  wood  „                  „  ...  —  o"i6         —  — 

Oak  wood           „                   „  ...  —  015          —  3374 

Alder  wood         „                   „  ...  —  013          —  32*40         ^ 

Linden  wood      „                   „  ...  —  o'lo         —  32*79         S 

Fir  tree               „                   „  ...  —  —            —  3353 

Willow  wood      „                   „  ...  —  —           —  33*49 


Ui 


S 


The  evaporative  power  of  fir  wood  charcoal  containing  10*5  per  cent  of  water  and 
27  per  cent  of  ash  amounts  to  675  kilos.,  viz.,  i  kilo,  of  the  charcoal  evaporates 
675  kilos,  of  water.  This  charcoal,  in  perfectly  anhydrous  state  and  with  3*02  per 
cent  ash,  evaporates  7*59  kilos,  of  water. 

***'***"<£fSiJ*"****  -^.s  the  complete  carbonisation  of  wood  entails  a  loss  of  about 
40  per  cent  of  fuel,  it  has  been  recently  tried  to  prepare  a  kind  of  charcoal  exhibiting  a 
brown-black  colour,  and  obtained  from  wood  by  tonifying  rather  than  by  carboniBing 


7i«  CHEMICAL  TECHNOLOGY. 

it,  experience  having  shown  that  such  a  charcoal  is  obtained  when  the  tar-dsj 
wood  has  lost  by  torrifying  some  60  to  70  per  cent  of  its  weight.  This  kind  of  char- 
coal is  intermediate  to  real  black  charcoal  and  kiln-dried  wood ;  it  contains  mora 
oxygen,  is  readily  pulverised,  but  is  less  porous  than  either  kiln-dried  wood  or 
ordinary  charcoal,  than  which  it  is  far  more  inflammable,  and  is  hence  preferred  in 
gunpowder  making.  Oharbon  roux,  or  terrified  charcoal,  is  a  very  useful  and 
important  fuel  for  industrial  and  metallurgical  purposes. 

Freshly  prepared  terrified  charcoal  has  the  following  composition : — 

Carbon 74*0  per  cent 

Chemically  combined  water     ...     ..,    24'5    „ 

*^BU  ...  ..a  •••  »..  •••  •.•  •■•  I    S 

The  composition  of  this  charcoal  after  keeping  is : — 

Carbon 66*5  per  cent. 

Chemically  combined  water     22*0 

Hygroscopic  water    10*0    ,, 

^oH         •••   .••   •••   •••   •••   •••   •••    I  ^ 


» 

9>    »> 


•I 


BoMtodWood;  The  ARsooiatlon  for  Promoting  Chemical  Industry  at  Mains  prepares  an 
BoiiBoox.  intermediate  product  to  wood  and  torrified  charcoal,  to  which  the  name 
Ted  wood  (roasted  wood,  hois  roux)  is  given.  It  is  made  from  beech  wood,  and  is  the  by- 
product of  the  preparation  of  acetic  acid  and  creosote.  It  has  all  the  external  appearances 
of  wood,  but  the  colour,  which  is  deep  brown.  It  is  highly  inflammable,  and  consists  on 
an  average  of : — 

Carbon 52*66  per  cent 

Hydrogen      578    „    „ 

Ash        .. 0-43    „    „ 

Water  (moisture  or  constitutional?)  .      4*49    „    „. 
Oxygen 3664    „    „ 

According  to  B.  Fresenius's  researches,  the  evaporative  power  of  air-dzy  beech  wooi  is 
io  that  of  boia  roux  as  54*32  :  zoo. 

Peat. 

pMt.  This  is  the  product  of  the  spontaneous  decay  of  vegetable  matter,  man 
especially  of  marsh  plants,  mixed  with  various  mineral  matters,  sand,  day,  mari, 
lime,  iron  pyrites,  iron  ochre,  &c.  Peat  is  especially  formed  in  places  where  shallow, 
stagnant  pools  of  water  abound,  in  which  the  plants  grow,  while  at  the  same  time 
the  peat  is  precluded  access  of  air.  The  following  plants  are  chiefly  met  with  in  peai 
bogs  and  form  the  peat : — Eriophorum,  Erica,  Calluna,  Ledum  paluitre,  Hypmun^ 
and  also  Sphagnum,  a  plant  especially  fitted  for  the  formation  of  peat,  becaisse 
it  never  wholly  dies,  but  continues  to  vegetate  towards  the  surface  of  the  water  or 
bog,  while  the  older  parts  decay. 

The  different  qualities  of  peat  are  partly  due  to  the  plants  from  which  the  pest  is 
formed,  but  chiefly  to  the  more  or  less  complete  decay  these  plants  have  nndetgooe, 
to  the  mineral  substances  mixed  with  the  peat,  and  to  the  compression  to  which 
it  has  been  submitted  by  the  weight  of  other  mineral  materials  deposited  upon 
it.  Abroad,  and  in  countries  where  peat  abounds,  several  varieties  *are  dis- 
tinguished, such  as — I.  Moor  peat,  chiefly  derived  from  kinds  of  Sphagnum,  sad 
found  in  several  parts  of  the  United  Kingdom  as  very  young  peat — for  instance,  at 
Aldershot,  and  on  moor  lands.  2.  Heath  peat,  in  Holland  known  as  plaggentmrf,  is 
the  sur&ce  soil  of  heather-growing  places.    3.  Meadow-land  peat,  decayed  coaise 


FUEL,  713 

grass  mixed  with  a  soft  subsoil.  4.  Wood  or  forest  peat,  met  with  in  forests, 
and  formed  by  the  decayed  wood,  leaves,  &c.  5.  Marine  peat,  formed  by  the  decay 
of  sea  plants,  yarions  kinds  of  Fuous,  &c. 

Peat  is  directly  obtained  by  simply  catting  it  with  a  spade  from  the  surface  of  the 
soil,  either  with  or  without  the  necessity  of  first  removing  a  layer  of  other  soil, 
while  some  peat  can  be  obtained  only  by  dredging  for  it  under  water.  In  the 
latter  case  a  mud  is  dredged  up  which  (as  happens  in  Holland,  where  the  land  peat  is 
known  as  koog  veen,  while  the  peat  from  under  water  is  termed  laag  veen),  has  to  be 
dried  gently  in  open  air,  and  afterwards  cut  up  in  brick-shaped  lumps,  and 
further  air-dried.  Peat  is  often  artificially  compressed  for  the  purpose  of  obtaining 
a  more  compact  fuel.  The  quantity  of  water  contained  in  freshly  dug  peat  is  very 
large,  and  by  keeping  this  peat  in  dry  situations  it  may  lose  45  per  cent  of  its 
original  weight    Assuming  the  organic  matter  of  peat  to  consist  of — 

Carbon ...    •••    •••      60  per  cent. 

Hydrogen    •        2 

Yva«er  •••    •••    ■••     •••    •••      ^o 

The  best  solid  air-dry  peat  consists  of — 

Solid  peat  mass  (inclusive  of  ash)     75  per  cent. 

Hygroscopic  water ...    ...     25        „ 

or  of— 

Carbon       •     •••    45*0  per  cent. 

^^yVLxt}f^"JX    •••        «.•        •••        •••        *»m        •*•        •••  IS  ,, 

Chemically  combined  water   28*5        „ 

Hygroscopic  water 25*5        „ 

The  following  analyses  exhibit  the  composition  of  peat-ash,  which  is  characterised 
by  containing  a  far  larger  quantity  of  phosphoric  acid  than  wood-ash. 

According  to  E.  Wol6r,  two  kinds  of  peat-ash  from  the  Mark  (a  and  6),  and  another 
from  South  Bavaria  (0,  analysed  by  Dr.  Wagner)  contain : — 


ft 


a. 

(. 

c. 

liimC        •••      ,»,      ,,a      ,,,      ,,,      ,,,      ,,, 

15-25 

2000 

18-37 

20-50 

47-00 

45*45 

Oxide  of  iron       

550 

7'59 

7-46 

Diiica     •••    •••    „,    ,,,    ,,,    ,,,    ,,, 

41*00 

X3'5o 

20-17 

Phosphate  of  calcium  and  g3rpsnm  ... 

310 

2'6o 

Alkali, 

phosphoric' 

acid 

[,  sulphuric 

•  8-55 

acid,  &c.           j 

Dryiiiff  PMt.  The  use  of  peat  as  fuel  and  its  value  as  such  depend  in  a  great  ^measure 
upon  the  quantity  of  water  and  the  mineral  substanoes  it  contains.  Peat  may  be 
more  or  less  dried : — 

1.  By  exposure  in  stacks  in  open  air,  or  better  in  sheds  where  the  peat  is  protected 
from  rain,  but  where  a  free  oircolation  of  air  obtains.  Air-dried  peat  contains  25  per 
cent  water. 

2.  By  artificial  heat,  kiln  drying  at  zoo*  or  120*,  in  kilns  or  stoves  heated  by  a  distinct 
fire-plaoe,  or  by  waste  heat  from  other  operations. 

3.  By  compressing  peat.  The  compression  has  the  following  advantages: — a.  Ben- 
dering  the  peat  more  compact  and  thus  increasing  its  pyrometrio  effect.  6.  Lessening  its 
bulk,  and  consequently  lessening  the  cost  of  transport  by  water,  in  which  mode  of  trans- 
port the  cost  is  calculated  by  bulk  or  cubic  measurement,     c.  The  compression  aids 

30 


714  CHEMICAL  TECHNOLOGY. 

the  drying.  The  operation  of  compressing  freshly  dug  peat,  simple  as  it  appears,  has  been 
found  in  practice  to  be  accompanied  with  difficulties  which  hitherto  have  not  been,  and 
are  not  likely  to  be,  overcome,  for  several  reasons,  among  which  is  the  fact  that  peat,  as  a 
heterogeneous  material,  cannot  be  dealt  with  satisfactorily  by  compression.  But  a  step  in 
the  right  direction  towards  the  utilisation  of  the  enormous  masses  of  peat  soil  has  been 
made,  by  submitting  the  soil  first  to  a  kind  of  grinding  lixiviation,  which  converts  it  into  a 
homogeneous  mass,  from  which  the  greater  part  of  the  mineral  matters  can  be  eliminated. 

In  the  works  at  Staltach,  near  Munich,  the  following  process  has  been  introduced 
by  Weber  for  preparing  peat.  The  peaty  material  having  been  brought  from  the  moor  in 
lumps  is  put  into  a  kind  of  pug-mill  moved  by  steam-power,  and  which  reduces  the  peaty 
substance  to  a  uniform  paste.  This  paste  is  moulded,  compressed,  and  dried  in  a  stove. 
Schhokeysen  has  invented  a  machine  of  improved  construction ;  in  its  appUcation 
it  is  unnecessary  to  pour  any  water  on  the  peaty  material,  consequently  the  drying  pro* 
cess  is  less  tedious  and  expensive.  Dr.  Versmann's  peat-preparing  machine  conasts 
chiefly  of  a  funnel-shaped  stout  sheet-iron  vessel  provided  with  small  holes  on  its 
periphery  and  internally  fitted  vdth  an  iron  core-piece,  which  bears  cutters  fastened 
spirally  on  its  surface.  By  the  action  of  these  cutters  the  peaty  matter  is  reduced  to 
a  pulp,  and  in  that  state  issues  from  the  holes,  while  any  coarse  particles,  such  as  pieces 
of  root,  vegetables,  (&c.,  are  discharged  at  the  lower  opening  of  the  funnel-shaped 
iron  vessel.  On  the  Haspel  moor  peat  bog  situated  between  Augsburg  and  Munich, 
there  has  been  in  use  up  to  the  year  1856  a  peat -preparing  machine,  originally  invented 
by  Exter,  at  Munich,  and  consisting  essentially  of  sohd  iron  cylinders,  provided  with 
strong  teeth  6  centims.  long,  and  arranged  in  the  same  manner  as  obtains  in  bone* 
crashing  mills.  The  peaty  material  is  reduced  with  the  aid  of  water  to  a  pulp,  which 
is  next  pressed,  moulded,  and  dried.  The  unreduced  vegetable  matter  and  roots  are 
separated  from  the  peaty  mass  by  the  machine.  Challeton's  peat-preparing  machine, 
invented  in  1824,  and  worked  at  Montanger,  near  Corbeil,  Seine  et  Oise,  France,  consists 
of  a  set  of  cylinders,  1*3  metres  in  length,  and  fitted  with  cutters.  The  peaty  mass  is 
first  cut  into  shreds  and  is  next  transferred  to  another  portion  of  the  machinery,  in  the 
particulars  of  its  construction  very  similar  to  a  coffee-mill.  With  the  assistance  of  some 
water  the  peaty  material  is  converted  into  a  pulp,  which  is  next  lixiviated,  and  thus 
deprived  of  mineral  impurities.  The  thin,  pasty,  peaty  mass  is  nm  into  a  large  tank  or 
pit  dug  in  the  soil,  and  left  there  until  it  has  acquired  sufficient  consistency  to  be  moulded. 
This  mode  of  treating  peaty  matter  has  iTeen  employed  at  Rheims  and  St.  Jean  on 
the  Bieler  L'ake,  Switzerland.  By  Challeton's  process — 100  cwts.  of  peaty  material 
{veen)*  yield  14  to  15  cwts.  of  peat,  containing  about  seven-eighths  less  ash  than  in 
natural  state. 

It  is  evident  that  a  process  of  lixiviation,  however  suitable  in  regard  to  its  application  to 
peaty  matter,  is,  in  a  certain  sense,  an  irrational  mode  of  treating  a  substance  \diieh  has 
to  be  again  dried  thoroughly,  and  which,  even  after  being  submitted  to  the  several 
operations,  is  not  a  fuel  equal  to  coal.  It  is,  therefore,  a  very  great  improvement  in 
the  utilisation  of  peat-soil  that  the  peaty  matter  should  be  treated  in  a  different  manner, 
or  by  the  so-called  dry  compression  process,  as  carried  out  by  Gwynne  and  Exter. 
According  to  this  method  the  peaty  mass  is  first  deprived.of  its  natural  excess  of  water  by 
means  of  a  hydro-extractor ;  next  pulped,  and  this  pulp  dried  by  artificial  means ;  the 
material  obtained  is  ground  to  powder,  which  is  finally  moulded  with  the  aid  of  strong 
pressure  and  the  simultaneous  application  of  heat.  The  peat  thus  prepared  is  of  a  deep 
brown-black,  a  hard,  stone-like  material,  excellently  suited  for  use  as  fuel,  especially 
for  manufacturing  and  metallurgical  purposes.  Another  process  of  peat  preparation  oon- 
sists  m  first  cutting  and  drying  the  peat  in  air.  The  air-dried  peat  is  ground  to  a  ooarae 
powder  and  then  dried  in  a  stove.  The  dried  peat  is  moulded  and  pressed  by  means  of  an 
eccentric  press,  heat  (50°  to  60°)  being  simultaneously  applied.  Peats  from  the  Kolber 
moor  (a),  and  from  Haspel  moor  (&),  thus  prepared,  were  found  to  contain  in  100  parts: — 

a.  b. 

Ash 
Water 
Carbon 
Hydrogen  . . 
Nitrogen    . . 
Oxygen 


*  There  is  no  word  in  English  equivalent  to  the  Dutch  Veerit  a  term  appUeable  to  all 
soils  which  consist  either  entirely  or  chiefly  of  peaty  matter.  There  is  no  eqniTskot 
term  also  in  German,  but  there  is  in  the  Danish  and  Bussian  languages. 


4*21 

8-34 

15-50 

15-50 

46-98 

4982 

496 

4*35 

072 

2763 

26*99 

100*00 

100*00 

1* 


94*6  kilos. 

of 

air-dry  fir 

wood. 

107-6 

>» 

»> 

lY 

104*0 

ft 

»» 

»» 

1 107 

»♦ 

** 

>» 

33*2  < 

cubic  metres  of  fir  wood. 

897 

ti 

*t 

»> 

144-6 

»» 

*t 

>9 

184-3 

>» 

»» 

»> 

FUEL.  715 

-  Heatinff  Effect  of  Peat.      The  combustibility  and  inflammability  of  peat  are,  owing  to  the 
large  quantity  of  ash  and  water  it  contains,  less  than  that  of  wood. 
According  to  Karmarsch  the  absolute  heating  effect  of: — 

100  kilos,  of  yellow  peat 

100       „        brown     „ 

100       ,,       hard 

100       „       pitch 

100  cubic  metres  of  yellow  peat  = 

100  „  brown     „     = 

100  „  hard       „     = 

100  .,  pitch       „     = 

These  results  agree  with  those  obtained  by  Brix.    Karst^n  states  that  for  evapora- 
tive and  boiling  operations — 

2i  parts  by  weight  of  peat  are  =  i  part  by  weight  of  coal. 
4   parts  by  volume         „         =1  part  by  volume      „ 

According  to  Vogel,  the  evaporative  effect  of  peat  is  the  following : — 

Water.  Eyaporative  effect. 

Air-dry  fibre     10  per  cent  55  kilos. 

Machine-made  peat...  12 — 15    „  5'^>~"5'5  »» 

Compressed  peat     ...  10 — 15     „  58 — 60  „ 

New  Method  of  During  the  last  twenty  years  peat  has  been  employed  for  the  preparation  of 
utmaingpeBt.  paraffin,  peatrcreosote,  and  paraffin  oil.  As  far  back  as  the  year  1849,  Reece 
tried  to  utilise  Irish  peat  in  the  preparation  of  paraffin ;  and  the  experiments  of 
Dra.  Kane  and  O'SuUivan  proved  that  i  ton  of  Irish  peat  yielded  about  1*36  kilos,  of 
paraffin,  9  litres  of  paraffin  oil,  and  4*54  litres  of  lubricating  oil.  According  to  Wagen- 
mann,  the  peat  of  the  Isle  of  Lewis,  Scotland,  yields  from  6  to  8  per  cent  tar,  and 
this  again  yields  2  per  cent  of  photogen  or  paraffin  oil,  1*5  per  cent  of  solar  oil,  and  0*33 
per  cent  of  paraffin. 

Carbonised  Peat. 

cttrboniied  Pert.  In  many  parts  of  Germany,  and  of  all  countries  where  peat  bogs 
abound,  the  use  of  peat  as  fuel  is  out  of  all  proportion  to  the  enormous  quantity  of 
material  left  untouched ;  this  is  due  to  the  fact  that  peat  is  as  fuel  in  many  respects 
a  very  inferior  material.  Its  bulk  in  reference  to  its  heating  effect  is  very  large ;  its 
combustion  evolves  a  very  disagreeable  odour  and  pungent  smoke,  so  that  peat 
is  therefore  not  suited  for  heating  rooms.  On  this  account  peat  is  carbonised.  As 
peat  varies  greatly  in  composition,  the  carbonised  peat  or  peat-coke  also  varies,  and 
the  composition  of  the  peat-coke  may  be  represented  as  follows : — 

Superior  quality.  Inferior  quality. 

Carbon    86  34 

Hygroscopic  moisture 10  10 

*v8ii  .*■     ...     ...     «..     c     ,,,  4  5 

Nothing  is  known  as  to  the  absolute  and  specific  calorific  effect  of  peat-coke,  since 
no  experiments  have  been  instituted.  Ordinary  peat-coke  appears  to  approximate 
charcoal  in  its  specific  calorific  effect,  but  peat-coke  is  otlierwise  inferior  to  charcoal 
because  it  is  less  dense,  and  cannot  on  account  of  its  dusty  ash  produce  an  intense 
heat.  Peat-coke  is  not  suited  for  fuel  in  blast-furnaces  or  other  metallurgical  opera- 
tions, but  answers  well  for  heating  steam  boilers,  evaporating  pans,  and  similar 


7i6  CHEMICAL  TECHNOLOGY. 

apparattis.  But  peat-coke  made  from  compressed  peat  is  a  highly  Talnable  lad  §at 
metallnrgical  operations,  so  that  it  becomes  a  matter  of  importance  to  find  a  means  of 
compressing  peat  inexpensively.  In  Holland,  peat,  especially  that  known  as  tpcm 
turf,  or  hoogeveensche  turf,  is  very  largely  nsed  for  industrial  purposes,  and  oo 
account  of  not  containing  sulphur  is  used  at  the  Utrecht  mint  for  melting  silver  and 
gold. 

Brown- Coal. 

Brown-coAL  This  mineral  fuel  is  also  the  product  of  a  peculiar  decomposition  of 
wood,  but  the  decay  has  in  this  instance  been  more  complete.  It  is  not  easy  to  draw 
a  clear  line  of  demarcation  between  brown-coal  and  coal,  when  only  the  properties  of 
these  substances  are  to  be  considered.  Therefore  the  palffiontological  and  geolo^cal 
relations  have  to  be  taken  into  account  when  it  is  required  to  estimate  the  value  of  a 
fossil  fuel.  In  general  it  may  be  said  that  any  fossil  coal  of  more  recent  date  than 
the  chalk  formation  may  be  termed  brown-coal ;  while  all  fossil  coals  found  below 
the  chalk  formation  are  really  pit-coal.  As  tlie  latter  contain  more  nitrogen  than  the 
former,  this  fact  may  be  utilised  in  testing  to  distinguish  between  pit-coal  and  brown- 
coal.  Brown-coal,  on  being  heated  in  a  dry  test-tube,  yields  fumes  which  exhibit  an 
acid  reaction,  because  brown-coal  is  somewhat  similar  to  ceUiQose ;  whereas,  if  the 
same  test  be  applied  to  pit-coal,  ammoniacal  fumes  are  given  off  (containing 
ammonia,  aniline,  lepidin,  &c.),  which  exhibit  an  alkaline  reaction.  When  finely  pul- 
verised pit-coal  is  boiled  for  some  time  with  a  rather  concentrated  solution  of  caustio 
potash,  the  fluid  remains  colourless;  but  when  brown-coal  is  similarly  treated, 
the  liquid  becomes  brown- coloured  by  the  formation  of  humate  of  potash.  This  test 
does  not,  however,  apply  to  the  brown-coal  found  in  the  tertiary  formation  of 
the  northern  slope  of  the  Alps.  £.  Richter  and  Hinrichs  state,  that  when  pit-coals 
are  dried  at  1 15^  and  caused  to  lose  a  very  small  quantity  in  weight,  this  loss  dimp- 
pears  again,  in  consequence  of  an  oxidation  which  takes  place;  while  if  brown-coal 
is  so  treated,  the  subsequent  increase  in  weight  is  not  observed. 

According  to  the  various  degrees  of  decay,  several  kinds  of  bxown-«oal  are 
distinguished : — i.  Fibrous  brown-coal,  fossil  or  bituminous  wood,  lignite,  is  similar 
to  wood,  the  structure  of  stem,  branches,  and  roots  being  apparent,  s.  Commoa 
brown-coal  forms  compact  brittie  masses,  exhibiting  a  conchoidal  fracture.  3.  Earthy 
brown-coal  is  a  mixture  of  brown-coal  and  earthy  matter.  In  several  parts  of  Grer- 
many  and  the  Austro-Hungarian  Empire,  brown-coal  of  excellent  quality  is  found, 
especially  suited  for  the  purpose  of  preparing  paraffin  and  paraffin  oils. 

Brown-coal  is  frequently  found  mixed  with  the  rhombic  variely  of  iron  pyrites.  When 
that  mineral  and  earthy  matter  predominate,  there  is  formed  what  is  termed  alom- 
shale,  under  which  name,  however,  is  also  known  a  kind  of  clay  mixed  with  bitomen 
and  iron  pyrites.  The  average  quantity  of  ash  contained  in  brown-coals  amounts  to 
5  to  10  per  cent.  The  ash  contains  chiefly  alumina,  silica,  lime,  magnesia,  oxides  of 
iron  and  manganese ;  while  the  quantity  of  hygroscopic  moisture  in  fireahly  dug 
brown-coal  may  amount  to  50  per  cent.  The  substance  contains  in  air-diy  state 
20  per  cent  water,  and  the  average  composition  of  brown-coal  may  therefore 
be  quoted  as  :•— > 


v^aroon      •••     ...     ...     ...     ... 

•  •a 

... 

48 — 56  per  cent 

Hydrogen 

Chemically  combined  water  ... 
Hygroscopic  water 

... 
... 

... 
... 
... 

1—2 

31—32 
20 

FUEL.  717 

The  combustibility  of  brown-coal  is  less  than  thftt  of  wood,  while  its  inflamma- 
bility varies  between  that  of  wood  and  pit-coal.  The  heating  effect  of  brown-coal 
is  with — 

o 

^  9^  &         .  d 


•3  0 
pu 

i 

OQ 

1 

Air-diy  fibrons  brown-coal,  containing  20 

and 

0 

0-48 

055 

1800 

M                        »»                            »f 

It 

20 

»t 

10 

0-43 





„      earthy          ,, 

»» 

20 

}» 

0 

o-6i 

079 

1975 

>l                     iJ                       9* 

>« 

20 

f» 

10 

055 





„      conchoidal    „ 

»• 

20 

» 

0 

069 

0-88 

2050 

»»                      »t                         !• 

»• 

20 

» 

ID 

0*62 





Kiln-dried  fibrous  brown-coal 

>t 

20 

»» 

0 

o*6i 



2025 

»»           »»               >» 

»» 

20 

t» 

10 

055 





„        earthy          „ 

>l 

20 

»» 

0 

076 



2125 

>i            »»               »» 

»» 

20 

n 

10 

0*69 





„       conchoidal    „ 

» 

20 

f* 

0 

085 



2200 

>»                         M                                  >t 

»» 

20 

» 

10 

076 





3*9 

If 

576 

4-8 

99 

555 

31 

99 

5'o8 

99 

19  O  *  >»  3  *"^       »» 


It  appears  from  this  table  that  the  absolute  and  pyrometrio  calorific  effect  of  air- 
dry  brown-coal  is  more  than  twice  that  of  kiln-dried  wood ;  and  this  remark  applies 
to  the  specific  calorific  effect  of  brown-coal,  which  is  more  than  twice  that  of  the  best 
wood. 

The  evaporatiye  effect  of  brown-coal  is  the  following : — 

Water.  Ash.  EyaporatiTe  effect. 

Bohemian  brown-coal  287  per  cent.        10*6  per  cent        5*84  kilos. 

Bituminous  wood     ...  237        „  39      „  576    „ 

Earthy  coal       472 

Lump  coal        477 

Bnmn-eoaiMFML  Browu-coal  IB  a  lesB  Suitable  fuel  and  its  applications  are  far  more 
limited  than  those  of  pit-coal,  for  brown-coal  cannot  be  used  in  those  cases  where  a 
caking  coal  is  required.  Brown-coal  is  useful  as  fuel  for  certain  chemical  operations — dis- 
tillation, evaporation,  &o, — and  may  be  used  for  heating  rooms  in  dwelling  houses,  when 
burnt  in  well-constructed  stoves.  Earthy  brown-coal  is  not  well  fitted  for  use  as  fuel, 
unless  it  has  first  been  liriviated  with  water,  moulded  into  bricks,  compressed,  and  dried. 
It  has  been  found  in  practice  that  brown-coad  freshly  dug  is  a  better  fuel  than  brown-coal 
which  has  been  exposed  to  the  air  for  some  time,  because  by  the  combined  action  of  air 
and  moisture,  even  when  the  material  does  not  contain  pyrites,  a  slow  combustion  takes 
place,  whereby  the  combustibility  of  the  materisJ  is  greatly  impaired.  As  already 
observed,  from  brown-coal  paraffin  and  paraffin  oUs  may  be  extracted. 

Pit'Coal,  or  Coal. 

ooaL  Iron  ores  and  coal  are  the  most  useful  minerals,  and  the  most  important  of  all 
inorganic  products  of  nature.  Without  coals  the  industry  of  the  world  as  now 
existing  would  have  been  simply  impossible.  Goals  supply  heat  and  are  a  source  of 
power ;  and  cheap  coal  is  a  most  important  incentive  to  extensive  industry. 

Coals  are  the  mummified  and  carbonised  remnants  of  an  ancient  flora  belonging  to 
a  former  phase  of  existence  of  our  globe ;  and  they  exist  as  a  distinct  geological  for- 
mation, which  extends  in  some  localities  over  an  area  of  several  square  miles. 
As  regards  the  mode  of  formation  of  coal  different  opinions  are  current     The 


>■•      •    ■•• 


52-65 

5'25 

42*10 

6o*44 

596 

33'6o 

6696 

5-27 

2776 

7420 

5*89 

19*90 

7618 

5-64 

1807 

9050 

505 

4*40 

9285 

3-96 

319 

718  CHEMICAL  TECHNOLOOY. 

simplest  view  is  that  a  peculiar  kind  of  decay,  aided  by  the  internal  heat  of  the 
earth,  and  modified  by  the  pressure  of  superincumbent  rocks  and  sedimentary 
deposits,  has  taken  place  among  the  plants,  which  have  been  gradually  converted 
into  a  more  or  less  pure  carbon.  Hence  antliracite  is  a  nearly  pure  carbon ;  while 
the  different  varieties  of  coal  which  contain  bituminous  and  volatile  matter  are 
less  completely  decayed.  The  hydrogen  and  oxygen  escape  in  combination  with 
carbon  as  marsh-gas  and  carbonic  acid  and  as  petroleum.  Antliracite  must  be  viewed 
as  tlie  final  product  of  the  slow  process  of  decay  through  which  brown-coal  and  pit- 
coal  pass. 

Carbon.      Hydrogen.    Oxygen. 

Cellulose     

Peat  from  Vulcaire    

Lignite        

Earthy  brown-coal     

Coal  (secondary  formation) 

„     (coal  „       ) 

Anthracite .•     •. 

The  most  important  explored  coal  deposits  in  Europe  are : — ^In  England  :*  The 
South  Wales  coal  formation  extending  over  an  immense  area ;  the  Staffordshire  and 
Yorkshire  coal  basins,  tlie  latter  of  which  stretches  to  the  Durham  and  Northum- 
berland basins,  and  these  again  to  those  met  with  in  the  Southern  parts  of  Scotland, 
s.  In  Belgium :  The  basin  of  the  Maas,  near  Li^ge,  and  tliose  of  tlie  Sambre  and 
of  Mons.    3.  In  France :  The  basins  of  the  Loire,  of  Valenciennes,  of  Crenzot  and 
Blanzy,  of  Aubin,  of  Alais.    4.  In  Germany :  The  Silesian  coal  basin,  those  of  the 
Saar,  of  the  Kuhr,  a  tributary  river  of  the  Rhine,  the  basins  near  Zwickau  and 
Plauen,  &c.      5.   In  Austria:  the  Bohemian  coal  basin  at  Pilsen,  and  those  of 
Brandau  and  Schlan.    The  largest  of  the  European  coal  deposits  or  basins  is  very 
small  compared  with  tjiiose  situated  in  North  America.    The  largest  of  the  American 
deposits  is  that  which  stretches  from  near  Lake  Erie  to  the  Tennessee  river,  through 
the  states  of  Pennsylvania,  Virginia,  Kentucky,  Tennessee,  and  known  aa  the 
Apalachian  coal  field.     The  coal  fields  of  Illinois  and  of  Canada  are  not  much 
smaller. 

AeceMog  oonrtitnenu  ]j.qu  pyiites,  or  muudic,  as  Uio  pitmen  term  it,  is  in  the  tesseral 
or  in  the  rhombic  shape,  a  very  common  accessory  constituent  of  coal,  which 
by  being  impregnated  with  this  material  may  not  only  become  unfit  for  use  in 
certain  operations,  but  is  liable  to  crumble  to  dust,  as  is  the  case  with  many  kinds  of 
the  Welsh  coals  which  are  thoroughly  incorporated  with  pyrites,  because  the  pyiites 
on  coming  into  contact  with  air  are  oxidised  and  increase  in  bulk,  forcing  the 
coal  asunder.  This  oxidation  may  become  so  active  as  to  give  rise  to  spontaneous 
combustion  of  the  coal  even  in  tlie  seams.  Galena,  copper  pyrites,  and  black-jack 
(native  black  sulphuret  of  zinc),  also  occur  occasionally  in  coal.  Among  the  earthy 
minerals,  carbonate  of  lime,  gypsum,  heavy  spar,  clay,  ironstone,  and  blackband  (aa 
iron  ore)  ^  are  frequently  met  with. 

ciMBiflcation  of  ooi^fk  Abroad  coals  are  classified  with  respect  to  their  behaviour  under 
combustion,  as — i.  Caking  coals,  which  on  having  been  reduced  to  powder  and  then 

*  The  yield  of  coals  in  great  Britain  is  annually  increasing,  for  in  i860  it  amounted  to 
80  millions  of  tons  ;  in  1868  to  104  millions ;  in  i86g  to  108  millions ;  and  in  1870  to  113 
millions  of  tons. 


FUEL.  719 

ignited  in  a  closed  crucible  to  red  heat,  cake  together.  2.  Sintering  coals,  the 
powder  of  which  agglutinates  without  fusing.  3.  Sandy  coals,  the  powder  of  which 
neither  cakes  nor  agglutinates  when  ignited.  In  England  coals  are  usually  classified 
as — I.  Gas  coal.    2.  Household  coal.    3.  Steam  coal. 

Comparing  the  elementary  composition  of  the  coals  with  their  chemical  and 
physical  properties,  it  appears  that  caking  coals  contain  a  bitumen  consisting  of 
carbon  and  hydrogen  ready  formed,  or  what  is  more  likely  formed  at  a  high  tem- 
perature. The  larger  quantity  of  oxygen  present  in  sintering  coals  causes  less 
bitumen  to  be  formed ;  while  in  sandy  coals  a  still  smaller  quantity  of  bitumen 
is  formed.  The  most  recent  researches  on  coal  disprove  the  opinion,  that  with 
an  increase  of  the  quantity  of  oxygen  the  caking  should  decrease,  and  that, 
consequently,  the  coals  which  contain  the  largest  quantity  of  oxygen  should  be 
sandy  coals.  Coals  exhibiting  almost  the  same  elementary  composition  behave  very 
differently  when  exposed  to  heat.* 

Anthneite.  This  carbouaceous  mineral  is  to  be  considered  as  the  final  product 
of  the  process  of  decay  which  has  converted  plants  into  coal.  Anthracite  is  found 
in  the  metamorphic  rocks  deposited  in  seams  between  clayey  slate  and  greywacke, 
also  between  deposits  of  mica  slate.  Anthracite  is  amorphous  and  thereby  distinguished 
from  graphite;  it  is  deep  black  coloured,  brittle,  exhibits  a  conchoidal  uneven 
fracture,  bums  with  a  scarcely  luminous  flame,  and  without  producing  smoke. 
It  does  not  become  soft  in  the  fire,  but  frequently  decrepitates. 
Jacquelain's  analysis  of  several  anthracites  led  to  the  following  results: — 

Carbon.  Hydrogen.  Oxygen.  Nitrogen.  Ash. 

From  Swansea 90*58           360  3'8i          029  172 

Sabl6       .•   87-22           2'49  i'o8          2'3i  6*90 

Vizille     94*09            1*85  „            2*85  1-90 

Is^re  Department,  France    ...      94*00            1*49  „            0*58  4*00 

Anthracite  is  an  excellent  fuel  for  many  purposes,  and  yields,  especially  with  the 
blast,  a  very  strong  heat  It  is  therefore  largely  used  in  Wales  in  metallurgical 
operations,  for  burning  lime  and  bricks,  and  in  stoves  for  household  purposes. 
In  Pennsylvania,  anthracite  is  met  with  and  used  largely  in  the  reduction  of  iron 

ores. 

cakiDffOoaL  lu  addition  to  its  behaviour  under  combustion,  this  coal  is  charac- 
terised by  its  deep  black  colour,  ready  inflammability,  and  by  yielding  when  heated 
in  closed  vessels  a  compactly  fused  coke.  Designating,  with  Fleck,  the  quantity  per 
cent  of  carbon  in  ash-free  coaly  matter  as  C,  the  free  hydrogen  as  Wx,  the  combined 
hydrogen  as  W,  the  oxygen  and  nitrogen  as  S;  then  (C+(W+Wi)+ 8=100). 
Wx  is  found  by  calculation  on  the  supposition  that  8  per  cent  oxygen  holds  in  com- 
bination I  per  cent  of  hydrogen ;  consequently  Wx=i ;  and  this  deducted  from  the 
total  quantity  of  hydrogen,  gives  as  diflerence  the  free  hydrogen  =W.  The  caking 
property  of  a  coal  is  due  to  the  proportion  that  upon  100  parts  of  carbon  there  should 
not  be  less  than  4  of  hydrogen.  Caking-coals  are  especially  suited  for  gas  manu- 
facture, though  Fleck  designates  as  such,  in  the  widest  sense,  all  coals  containing 
upon  1000  parts  of  carbon  at  least  20  of  combined  hydrogen.  But  as  the  value  of 
such  a  gas-coal  depends  upon  the  free  hydrogen,  which  with  carbon  will  yield  volatile 

*  E.  Bichters  has  recently  described  a  method  for  the  comparative  determination  of 
^different  kinds  of  ooal.    See  Dingler's  Folyt.  Jonm.,  vol.  195,  p.  72. 


9f 
»» 


720  CHEMICAL  TECHNOLOGY. 

hydrocarbons,  for  tihe  purpose  of  rendering  the  flame  Inminons,  coal  containing  npon 
ICO  parts  of  carbon  2  parts  of  combined  (or  fixed)  and  4  of  free  or  disposable 
hydrogen  may  be  considered  as  the  best  gas  coal  and  the  strongest  caking  coaL 

Because  they  contain  a  larger  quantity  of  hydrogen  than  other  kinds  of  coals, 
caking- coals  are  more  readily  inflammable  and  evolve  the  strongest  flame.  Strongly 
caking  coals,  however,  are  not  well  suited  for  use  as  fuel  by  themselves,  owing  to  the 
fact  that  by  the  fusion,  as  it  were,  they  undergo,  they  greatly  impede  access  of 
air  at  the  open  fire-bars.  Caking-coal  is  an  excellent  fuel  on  the  forge-hearth, 
because  by  caking  together  it  forms  a  receptacle  for  the  blast  from  the  beliows,  and 
increases  the  heating  eflect.  The  peculiar  kind  of  small  coal  used  by  blacksmiths  is 
known  in  the  French  language  as  charhon  de  forge,  houiUe  marickale^  and  is  in 
England  termed  smithy-coal. 

Sandy-coal  is  the  poorest  qualify.  It  contains  much  oxygen,  suffers  great 
contraction  when  converted  into  coke,  leaving  a  sandy,  small  coke.  This  kind  of 
coal  contains  less  than  4  per  cent  of  free  hydrogen ;  it  is  used  as  fuel  for  buming 
bricks,  lime,  and  for  similar  purposes  where  a  cheap  fuel  is  required* 

Sintering-coal  exhibits  an  iron-grey  colour,  is  frequently  very  lustrous,  £»  less 
readily  ignited  than  caking-coal,  often  contains  much  pyrites,  and  is  employed  where 
a  strong  and  lasting  heat  is  required.  It  is,  therefore,  used  industrially  on  the  large 
scale  as  a  steam  coal,  as  fuel  for  metallurgical  purposes,  &c.  This  kind  of  coal 
yields  only  a  small  quantity  of  gas,  and  when  burnt  for  coke  in  coke-ovens  it  is 
scarcely  changed  in  bulk,  yielding  a  loose  somewhat  porous  coke.  100  parts  of  the 
combustible  portion  of  this  coal  contain  less  than  4  parts  of  free  and  less  than  2  parts 
of  combined  hydrogen.  Some  kinds  of  anthracite  belong  to  this  class  of  coal ;  but 
the  real  anthracite  is  to  be  viewed  as  a  native  coke  produce^  in  a  peculiar  manner, 
not  comparable  with  the  process  of  coke-making  as  carried  on  industrially. 

The  physical  properties  of  coal  may  be  judged  from  the  quantity  of  hydrogen 
contained,  and  we  find  that : — 

Caking  coals  contain  upon  100  C,  more  than  4  Wx,  less  than  2  W. 

Gas  and  caking  coals  „  „  100  C,  „  „  4  Wx,  more  than  2  W. 
Gas  and  sandy  coals  „  „  100  C,  less  than  4  Wx,  „  „  2  W. 
Sintering  coals  „        „     100  C,    „      „     4  Wx,  less  than  2  W. 

Assuming  coals  to  contain  on  an  average  5  per  cent  of  hygroscopic  and  5  per  cent 
of  chemically  combined  water,  the  average  compomtion  is : — 

v/EuDOU      •••       •••       ...       •••       .••       •••       •••       •••       ...       ...       ...       •••       0^    '   /O 

XiyCu  OS6Q  ..•       ...       ...       ...       ■•*       ■*.       ...       .«.       •••       •••       •••  ^  4 

Chemically  combined  water  and  hygroscopic  water       13 — 23 

^aOU  ...  •••  ...  •••  •••  ...  ...  ...  ...  •.•  ...  ...  «..  /( 

The  composition  of  the  ash  varies,  greatiy  depending,  not  only  as  regards  qmJity, 
but  also  the  quantity  of  the  constituents,  upon  a  variety  of  causes,  among  which  flie 
geological  age  of  the  coal,  the  formation  in  which  it  is  found,  and  others,  have  great 
influence.  The  ash  consists  chiefly  of  an  alumino-silicate,  or  of  gypsum  and 
sulphuret  of  iron,  mixed  with  larger  or  smaller  quantities  of  lime,  magnesia,  carbonie 
acid,  oxides  of  iron  and  manganese,  with  very  small  quantities  of  chlorine  and 
iodine.  Ash  which  contains  much  alumina  and  little  silica  is  iofusible.  Ash  con- 
taining much  silica,  but  not  any  or  only  a  small  quantity  of  oxide  of  iron,  siiiien, 
but  does  not  fuse ;  but  ash  which  contains  oxide  of  iron  and  alkaline 


FUELm  721 

forms  a  slag,  and  may  give  rise  to  loss  of  fuel  by  enveloping  the  particles  of  coal.  The 
qnantity  of  ash  found  by  incinerating  coal  in  a  small  crucible  varies  from  0*5  to  20 
and  30  per  cent.  By  washing  coals,  small  coal  especially,  a  portion  of  the  mineral 
matter  may  be  eliminated. 

cuoiiiic  BflecL     The  Subjoined  table  exhibits  for  average  coals  the  calorific  effect, 
specific  gravity,  and  composition : — 


Composition : — 

Carbon       

Hydrogen 

Chemically    com- 
bined water   ... 

Anthracite. 

85 
3 

2 

Caking  coal. 

78 
4 

8 

Sintering  coaL 

75 
4 

II 

Sandy  Coal. 

69 
3 

18 

Hygroscopic  water 

5 
5 

5 
5 

5 
5 

5 
5 

Calorific  effect:— 

Absolute     

Specific       

IV^ometric 

0-96 

1*44 
2350° 

0*93 
117 
2300" 

089 
116 
2250° 

072 
I '06 
2100** 

I  part  reduces  lead 
I   part  heats  water 

26—33 

23     31 

19—27 

21—31 

from  0° — 100 

605— 747 

52*87 — 20 

4406 — I '6 

50*0— 7 10 

Sp.  gr.     ...     ...     ... 

1-41 

113— 1"26 

i'ii—130 

205— 134 

It  is  assumed  in  practice  that  the  heating  effect  of  a  good  coal  is  very  nearly  that 
of  wood-charcoal,  and  twice  that  of  dry  wood.  In  smelting  operations  the  heating 
effect  of  coals  is  taken  by  bulk  to  that  of  wood  by  bulk  as  5  :  i,  and  by  weight  as 
15:8.    According  to  Karsten's  researches : — 

100  parts  by  bulk  of  coal  in  the  reverberatoiy  furnace  =  700  parts  by  bulk  of  wood. 
100    „     by  weight    „  „  „  „      =250    „    by  weight  of  wood. 

In  boiling  operations : — 
100  volumes  of  coal  =  400  volumes  of  wood  =  400  volumes  peat, 

loo.parts  by  weight  of  coal  =160  parts  by  weight  of  wood  =  250  parts  by  weight  of 
neat. 

'^^ofcoSsf **      '^^^  forms  the  most  important  industrial  investigation  which  can 
be  made  with  coals.    In  order  to  ascertain  the  evaporative  effect,  we  must  know — 
I.  The  quantity  of  hygroscopic  water  contained.    2.  The  quantity  of  ash  or  non- 
combustible  matter  it  contains.    3.  The  composition  of  the  organic  matter. 

As  Hartig's  experiments  have  proved  that  the  evaporative  effect  of  the  organic 
matter  of  coal  is  the  same  for  nearly  all  kinds  of  coal  (=  8*04  to  8*30  kilos,  of  steam), 
the  evaporative  effect  of  any  given  sample  of  coal  can  be  ascertained  by  estimating 
the  quantity  of  water  and  ash  it  contains.  According  to  W.  Stein,  the  practical 
evaporative  effect  on  the  large  scale  may  be  taken  as  equal  to  two-thirds  of  that 
which  has  been  calculated  from  the  chemical  composition  of  the  coal.  The  practical 
evaporative  effect  of  the  coals  in  use  in  Southern  Germany  is,  according  to  laboratory 
experiments  and  experiments  made  on  the  large  scale,  the  following : — 

3  ^ 


»»  ♦« 

»»  »♦ 


7M  CHEMICAL  TECHNOLOGY. 

Praetieal 
Ash.  evaporatiTe  eSeet 

Ruhr  coals,  I.   quality    5*00  7-20 

Zwickau  black  pitch-coal,     I.        , 6"o6  6*45 

II i5'4i  5"6i 

Bohemian  coal,                      I.        , 6'6o  5*80 

n.        „        6*90  4-90 

m.        „        10*30  4*  20 

Saar  coal,                                                 21*50  606 

Stockheim  coal,                     I.        „        6*30  272 

„                       II.        , 840  386 

The  average  evaporative  effect  of  the  Hartley  steam  coals  is  14  lbs.  of  water  for 

X  lb.  of  coal. 

Bo^ead  cotL.  This  mineral,  also  known  as  Torbane  Hill  coal,  found  in  the  neigh- 
bourhood of  Bathgate,  a  town  situated  between  Edinburgh  and  Glasgow,  belongs, 
with  the  blattel-coal  of  Bohemia,  to  a  peculiar  fossil  &una,  and  is  especially  suited 
for  the  manufacture  of  paraffin  and  oils,  owing  to  the  large  quantity  of  bituminous 
matter  it  contains.  Boghead  coal  is  now  solely  employed  in  the  preparation  of 
paraffin  and  oils ;  and  the  supply,  which  is  very  limited,  because  the  seam  is  almost 
exhausted,  has  been  secured  by  Mr.  Young,  of  Bathgate  Works. 
100  parts  of  Boghead  coal  contain : — 

Carbon^..     ..•    • 60*9  65*3 

Nitrogen 

...  •.*  a*.  .••  7  7 

•  «•  ...  •*.  ...  3  V    & 

...     •••     •«•     ...       4  3  5  4 

I..     •.•     •*•     ...     ••.       ^3  5 

24'i  i8'6 

Boghead  coal  was  formerly  employed  for  gas  making,  i  ton  yielding  15,000  cubie 
feet  of  a  highly  illuminating  and  very  durable  gas.  Many  varieties  of  the  Scotch 
oannel-coals  are  suitable  and  are  used  for  the  preparation  of  paraffin  and  oils,  and 
have  therefore  so  greatly  increased  in  price  that  these  coals — the  Wemyas,  Bigside, 
and  others — are  now  seldom  employed  for  gas  manufacture. 

Petroleum  oi  Fuel. 

PetK>ienm  m  Fad.  Native,  as  Well  as  artificially  prepared  petroleum,  is,  under  oerUun 
conditions,  a  veiy  valua'Ue  heating  material.  The  sp.  gr.  of  this  oil  vuies,  ai  o^ 
from  0786  to  o'923,  wliile  its  coefficient  of  expansion  for  1°  varies  from  0*00072  to 
o'ooo868.  The  experiments  as  to  the  application  of  petroleum  as  fuel  for  marine 
purposes  in  America  have  proved  that  peti'oleum  is  three  times  more  efficient  than 
coal :  and  as  tlie  complete  combustion  of  petroleum  does  not  produce  smoke,  but 
simply  evolves  cai'boiiic  acid  and  watery  vapour,  a  tall  chimney  is  not  required. 
Coals  may  be  burned  in  marine  boilers  witli  the  same  effect,  proved  by  a  series  d 
experiments  made  about  fifteen  years  ago,  on  the  large  scale,  by  the  late  Dr.  Eich- 
ardson,  of  Newcastle-upon-Tyne,  in  conjunction  with  Messrs.  J.  A.  Longridge  and  Sir 
William  Armstrong.  As  petroleum  contains  14  per  cent  of  hydrogen,  the  oondensa* 
tiou  of  tlie  gases  of  combustion  yields  a  lai-ge  quantity  of  water  which  may  serve  for 


Hydrogen   .. 
Sulphur 
Oxygen 
Water 

^xsn      ...     • . 


FUEL. 


723 


10,180  units  of  heat 

10,223 

t» 

»> 

9963 

» 

»» 

10,399 

t/ 

»1 

10,831 

»» 

«« 

9.593 

*f 

«« 

10,183 

Tl 

»f 

10,458 

«f 

f» 

10,005 

»♦ 

,« 

10.235 

»♦ 

y« 

9.950 

1* 

*» 

feeding  the  hoilers,  while  the  heat  thns  set  free  may  be  employed  for  the  purpose  of 
beating  the  feed-water.  According  to  H.  Deville,  there  is  no  difficulty  in  regulating 
the  supply  of  petroleum,  and  it  is  not  necessary  to  heat  it  previously.  According  to 
Fr.  Storer,  i  kilo,  of  crude  petroleum  evaporates  io'36  kilos,  of  water,  while  i  kilo. 
of  anthracite  coal  evaporates  only  5*1  kilos,  of  water.  The  theoretical  evaporative 
effect  of  the  purest  petroleum  is  18*06  kilos.,  as  may  be  deduced  from  the  percentage 
composition  of  petroleum,  viz. : — 

C    ...    0-86    ...      8080=6948 

H    ...    014    ...34.462=4824      .^     ^,     ^     21:772  =  1806 kilos. 

11,772  umts  of  heat ;       5^2 

The  heating  effect  of  different  kinds  of  petroleum  has  been  ascertained  by 
!£•  DevUle  (i8i56— 1869)  to  be  as  follows: — 

Heavy  oil  from  West  Virginia     

Light  oil  from       „  „  

Light  oU  from  Pennsylvania       

Heavy  oil  from  Ohio     

Oil  from  Java  (Rembang)     

Oil  from  Java  (Oheribon)     

Oil  from  Java  (Soerabaya)    

Petroleum  from  Schwab wiler  (Alsace)... 

Petroleum  from  East  Galicia       

Petroleum  from  West  Galicia      

Crude  shal€  oil  from  Autun  (France)... 

More  recently,  B.  Foote,  Wyse,  Field,  Aydon,  H.  Deville,  Dorsett,  and  Blyth,  have 
vonstmoted  petroleum  fornaces  suitable  for  steam-boilers,  which  answer  the  purpose  well. 
Peiroleum  lamps  are  used  abroad,  instead  of  spirit-lamps,  for  domestic  purposes,  viz., 
iieatimg  tea>  and  coflee-urus,  tea-kettles,  <ftc. 

Cohe. 

cok«w  By  coke  we  generally  understand  carbonised  coal;  and  in  England  there  is 
no  other  description  of  coke  than  oven-  and  gas-coke,  referring  of  course  to  the  mode 
of  production. 

Coke  is  prepared  for  the  puiposes: — z.  Of  increasing  or  rather  concentrating  the 
quantity  of  carbon  in  coal,  and  thus  to  obtain  a  fuel  which  will  jrield  a  more  intense 
heat  tlian  coal.  2.  For  the  purpose  of  converting  coal  into  a  fiiel  deprived  of  its 
volatile  constituents,  so  as  to  obviate  the  unpleasant  smell  emitted  by  the  combustion 
of  coal  when  used  to  heat  rooms  in  dwelling-houses.  3.  For  the  purpose  of 
converting  coal  into  a  fiiel  which  does  not  become  pasty  when  ignited,  coal,  in  con- 
sequence of  this  property,  being  unsuitable  for  use  in  blast,  cupola,  and  other 
furnaces.  4.  For  the  purpose  of  eliminating  from  the  coal  a  portion  of  the  sulphur 
contained  as  pyrites.  Before  being  converted  into  coke,  coal,  and  especially  small 
coal  or  coal  mixed  with  slaty  shale,  fire-clay,  and  other  heterogeneous  mineral 
matter,  is  washed,  as  it  is  technically  termed,  the  operation  consisting  in  a  process  of 
purification  by  means  of  suitably  constructed  machinery,  and  the  aid  of  a  stream  of 
water,  the  rationale  of  the  process  being  that  the  mineral  matter,  which  is  about 
three  times  heavier  than  tlie  coal,  is  deposited.  The  machinery  in  use  for  this 
purpose  is  similar  in  constniction  to  that  employed  for  washing  metallic  ores.  By 
this  method  of  purifying  coal,  the  quantity  of  asli  (mineral  matter)  it  contains  may  be 


7*4 


CHEMICAL  TECHNOLOGY. 


reduced  from  lo  or  12(^4  or  5  percent ;  but  it  shonld  be  borne  in  mind  thfttytoSper 

cent  of  the  coal  is  lost  as  dust.  Bessemer  has  Bnggeeted  the  use  of  a  solaliia 
of  chloride  of  calcium,  bo  concentrated  that  the  coal  maj  float  on  its  snr&oe,  while 
the  mineral  matter  will  sink.  The  residues  of  coal-waehing  ma;  contain  so  much 
iron  pTrites  as  to  be  lit  for  uee  in  the  preparation  of  sulphuric  acid  (see  p.  203). 

The  operation  of  coking  is  carried  on  in  heaps,  in  ovens,  or  in  retorts  :  bnt  in  the 
latter  case  the  abject  is  not  so  much  to  prepare  coke  as  to  obtain  gas.  tar,  and  other 
prodncls  from  coal.  The  construction  of  colce-ovens  according  to  Knab's  pLu, 
admits  of  obtaining  from  the  coal,  tar,  ammoniacal  water,  and  other  volatile  prodncta. 
cokiDc  In  nap..  This  method  of  converting  coal  into  coke  is  veiy  umilar  to  that  in  an 
tor  converting  wood  into  charcoal ;  but  the  central  shaft,  1  to  1-5  metres  in  haigbt,  it  in 
this  inBtauce  made  of  flie-bricks,  having  a  diameter  of  o'3  metre,  and  provided  with 
aereral  lateral  air-holes.  Fig.  31),  by  means  of  which  the  mass  of  coals  is  broo^t  in 

Pio,  313, 


n  with  the  central  shaft.  The  largest  lumps  uf  coal  are  placed  neit  to  the  shsfl, 
being  filled  np  with  small  coal,  technicall;  termed  cinders  and  cnlm.  At  the  bottom  of 
(he  heap  channels  are  conatncted  radiating  towards  the  centre.  The  bottom  of  the  shaft 
is  filled  with  dr;  wood,  which  is  kindled  from  the  top.  The  opening  at  the  top  is  not 
closed  with  the  iron  cover  fitted  to  the  shaft  as  long  aa  anj  smoke  from  the  smouldeiiiig 
coal  is  emitted.  When  no  more  smoke  isemitted.theair-abonnela  at  the  bottom  of  the  heap 
are  stopped  with  wet  sand  and  coal-dust.  In  England  the  cooling  of  tbe  glowing  heap  is 
hastened  b;  pouring  on  oold  water,  whereb?  a  greater  degree  of  desulphnratioD  of  th* 
eoke  ia  obtained. 

oountiiiOTau.  In  the  present  day  coal  is  converted  into  coke  almost  exdnsiTelj  in 
ovens  constructed  for  this  purpose  ;  because  it  has  been  found  tliat  by  the  use  of 
ovens  the  operation  is  mora  readily  conducted,  while  a  larger  qnanti^  and  a  better 
qtiolity  of  coke  are  obtained.  As  regards  the  construction  of  coke-ovens,  some  are 
BO  built  that  the  gases  and  vaponrs  evolved  during  the  operation  of  coking,  escapt 
without  being  ntHised,  Others  again  are  so  arranged  that  the  combustible  gases  are 
employed  aa  fuel  for  coking  the  coal,  or  as  fuel  for  steam-boilers  or  other  purpaeea. 
This  kind  of  oven  is  constmcted  with  or  without  admission  of  air.  To  the  latter 
class  belongs  Appolt's  coke-oven,  which  is  esBentially  similar  ia  a  vertical  gas-retort, 
fitted  with  apertures  for  the  exit  of  the  evolved  gaseous  matter.  Other  coke-ovens 
again  are  bo  conatmcted  that  the  tar  and  volatile  products  of  the  dij  distillataMi  of 
the  coal  may  be  condensed,  collected,  and  ntiliaed.  Knab's  coke-oven  is  thns  arranged. 
Among  the  coke-ovens  of  older  construction  is  one.  Fig.  314.  in  use  at  the 
Oleiwitz  ironworka  in  Silesia,  a  is  the  body  of  the  oven  or  Mln,  with  hOtnl 
openings,  000,  which  can  be  closed  by  dampers  or  iron  plugs :  similar  apertnreB  an 
made  in  the  bottom  of  the  oven.    The  lop  of  the  kiln  ia  vaulted,  wi^  the  ba^ 


FUEL.  725 

opening,  b,  which  serves,  aa  well  as  the  lateral  doorway,  a,  tax  tlie  iatrodnction  of  the 
coals.  The  large  lumps  are  placed  at  the  bottom  of  the  kiln,  wliich  ia  ealirely  filled, 
vith  the  exeeptioa  of  a  Bmall  space  towards  the  top  of  the  doorway,  left  fur  the  pur- 
pose of  throwiug  in  ignited  coals.  The  doorway,  a.  is  bricked  up,  only  a  small  chaimel 
being  left  for  the  introduction  of  the  ignited  coal,  /  is  an  iron  pipe  for  carrj-ing  off 
the  Tolatile  products  of  the  smonldering  of  the  coals  ;  d  is  an  iron  lid  fitting  tightly 
in  the  opening  b.  At  the  conunencement  of  the  operation  all  the  openings  of  the 
oven,  excepting  those  at/and  thoae  at  tlte  bottom,  are  closed ;  and  as  soon  as  there 
appears  at  the  lower  apertures  an  orange-coloured  glow,  these  openings  ore  closed, 
and  those  of  the  next  row  opened,  and  kept  open  for  about  ten  hours ;  the  third  row 
of  Openings  being  then  nnplngged  and  kept  open  for  siiLteeu  hours ;  finally,  the 
fbnith  row  ia  opened  for  about  three  honrs,  alter  which  the  oven  is  left  to  cool — all 
openings  being  plugged — for  twelve  hours.  The  door,  (.  is  then  broken  up,  and  the 
coke  drawn  from  the  oven  by  means  of  iron  rakes.  This  description  of  oven  contains 
35  to  40  cwta.  of  coal,  and  the  average  yield  of  coke  is  53  per  cent  by  weight  and 
74  per  cent  by  hnlk.  The  gaaea  and  vapours  issuing  from  /  are  carried  to  a 
condenser,     i  cwt.  of  coals  yields  10  litres  of  tar. 

The  twldng  of  small  coal,  cuhn.  coal-dust,  either  previously  washed  or  not. 
is  carried  on  in  ovens  similar  in  constmctiou  to  those  used  for  bread-baking.  Small 
coal,  especially  of  the  caking  quality,  yields  excellent  coke,  and  in  many  instances, 
this  fuel  ie  now  guaranteed  not  to  contain  more  than  €  per  cent  of  ash.  The  mode 
of  construction  of  coke  ovens  for  small-coal  coking  differs  in  various  conntries. 
Fig,  315  exhibits  a  vertical  section  of  such  an  oven  in  use  by  the  Leipzig-Dresden 
R^way  Company.  The  cokiug-ronra.  a.  is  3-3  metree  high.  The  doorway,  il, 
I  metre  high  and  wide,  can  be  closed  with  an  iron  door,  provided  at  the  top  with  four 


Fio.  315. 


air  holes.  The  chimney  stalk.  6,  is  rather  more  than  1  metre  high.  At  each  side  of 
the  doorway  an  iron  hook.  e.  is  fixed,  for  the  purpose  of  supporting  the  rakes  used 
by  the  labourers  when  drawing  the  coke.  In  this  description  of  oven  50  Dresden 
bushels*  of  amall  coal  and  coal-duat  are  converted  into  coke  in  seventy-two  hours- 
The  coke  obtained  is  very  compact ;  but  if  the  oven  be  lightly  filled,  a  more  spongy 
coke  ia  the  result.  Fig.  316  exhibits  the  construction  of  the  coke-oven  at  Ihe 
Zaukerode  colliery,  near  Dresden.  The  bottom  or  hearth  of  the  coking-kiln  is  of  a 
circular  shape  ahghtly  inclined  towards  the  doorway.     The  width  of  the  hearth 

*  I  Dresden  bushel  =  103'B  litres. 


726 


CIIEUICAL   TECHNOLOGY. 


is  3'6  metres.  T)ie  top  of  the  vault  c  is  3-0S  metres  above  tlie  lieartb.  66  are  two 
cbiranef  B,  each  i'3  metres  in  height,  for  canjiiig  off  tlie  volatile  product.  The  cut- 
iron  door  is  so  arranged  that  at  the  top  of  the  doorwaj  an  opening  ia  left  foe 
the  admisaioD  of  air  into  the  oven ;  « is  a  hook  serving  the  purpose  mentioned  in  tha 
description  of  Fig.  314.  Fig.  317 
'  '  ^'  '  exhibits  the   vertical   section,  and 

F^.  318  the  ground  plan  of  the 
coke-ovens  in  use  at  the  collieriM 
BitnaUd  in  the  Saar  district.  He 
hearth  of  the  kiln  ia  egg-shaped, 
3  metres  long  and  2  metres  wide ; 
while  the  height  of  the  kiln  it  at 
most  only  I  metre.  The  chimney, 
i'7S  metres  high,  also  Berves  far  the 
introdnction  of  the  coals.  Th* 
admission  of  air  to  this  oven  ii 
regulated  b;  a  cliannel  at  a  height 
of  03  metre  above  the  hearth  this  channel,  Fig.  318,  communicates  on  bothsideaof 
the  doorway  t  with  the  outer  air.  and  commnoicates  bj  means  of  the  channels.  000. 
with  the  intenor  of  the  oven.  The  door,  t.  fits  rather  tiglitlj-  in  the  doorway. 
A  quantity  of  i  to  1-25  cubic  metres  (firom  40  to  50  cubic  feet]  of  small  coal  is  cos- 
verted  into  cute  witli  tliis  oven  in  24  to  30  hours. 
Fio.  317. 


Among  the  eolte-ovens  constructed  to  utilise  the  escaping  gases  and  heat  tat 
the  purpose  of  making  coke,  that  of  Appolt  deserves  notice.  The  first  of  these  ovetti 
was  built  in  1835  at  St.  Avoid.  This  coke-oven  is  distinguished  from  thow 
desoribed  by  its  peculiar  shape,  which  is  that  of  a  vertical  shaft,  heated  oxtemallf, 
the  heat  being  supplied  by  the  ignition  of  the  gases  and  vapours  evolved  front  the  ooalf 
while  becoming  coked.  Fig.  319  exhibits  a  vertical  section,  and  Pig.  320  a  horiionlal 
section  of  this  oven.  In  order  that  the  heat  may  reach  the  centres  of  the  shafts,  aa, 
tlieir  shape  ia  that  of  a  parallelogram.  o'45  by  i'2  metres,  and  4metresdeep;  lift 
such  shafts  form  one  oven.  The  separate  shafts,  the  walls  of  which  consist  of 
hollow  double  walls,  b.  are  connected  with  each  other  as  well  as  with  the  lining 
walls,  which  Forms  a  series  of  intercommunicating  channels.  Every  compartment  ii 
provided  with  an  upper  and  a  lower  aperture,  through  the  former  of  which  the  ecall 
are  introduced,  while  through  the  latter — closed  during  the  coking  operation  with  aa 
iron  trap  door^the  coke  is  withdrawn.  The  apertures  e«  in  the  brickwork  serve  (or  tb» 
purpose  of  carrying  oft  the  gases  and  vapours  which  are  burnt  in  the  fh«TinBlii  by  the 


FUEL. 


I'l 


aid  of  the  air  rushing  m  Atff  The  heat  produced  bj  this  combastion  cnnrerts  the 
ccais  into  coks  and  tlie  products  of  the  combustion  are  cnmed  off  Ihiough  the 
chumelB  g  and  A  The  dampers  h  serve  to  regulate  the  draught  The  chauneU  y 
commoiucate  with   the  honzootal  chanael    i,  the  ciiaonels  h  nith  the  cliauuel  j ; 


Fio  31S 


the  channelB  i  and  j  are  carried  into  the  cliimae;  stalk,  k  The  compartments  of 
the  kilD,  Fig,  319,  are  united  at  the  top  bj  a  contraction  of  the  hnckwork.  leaving  to 
each  onlj  a  small  opening,  dosed  by  a  cast-iron  lid.  fitted  inth  an  iron  tube  for  the 
pnrpoM  of  conveying  a  portion  of  the  gases  and  volatile  matter.    On  the  top  of  the 


Fio.  319. 


Fid.  31C 


ovan  I'^la  are  placed,  on  which  an  iron  tmck  runs,  laden  with  the  charge— 25  cwts.— 
for  each  compartment.     The  coals   are   drsclmryed   into  the  oompartmenls  by 
1  tlie  bottom  of  the  U'nck.     Under  tiie  •.■anlted  brickwork,  u, 
1  be  run  for  the  pnrpose  of  bein^  laden  wilh  Uie  eofce. 


opening  a  trap-door  ii 
of  the  oven,  tmeks  c 


728 


CHEMICAL   TECHNOLOGY. 


In  order  to  set  the  oven  in  operation  dry  wood  is  thrown  into  the  compartments,  ud 
this  having  been  kindled,  coals  are  thrown  upon  it.  The  interior  of  the  oven  smb 
becomes  hot  by  the  combustion  of  the  gases  issuing  from  the  openings  e.  When  the 
heat  of  the  oven  is  sufficient  to  effect  the  decomposition  of  the  coals  and  the  combus- 
tion of  the  volatilised  products,  tlie  compartments  are  charged,  the  iron  lid  beii^ 
tightly  luted  to  the  top  with  clay.  The  charging  is  so  conducted  that  the  twelve 
compartments  of  the  oven  are  filled  in  twenty-four  hoiu*8,  after  which  tlie  coke  in  the 
first  compartment  is  ready  for  being  drawn,  and  fresh  coal  put  in,  an  operation  whicli 
is  continued  every  second  hour.  As  may  be  expected  from  the  mode  of  constractian. 
Appolt's  coke-oven  is  rather  expensive  in  the  first  building,  the  cost  abroad  bdng 
about  i£6oo,  while  an  ordinary  coke-oven  may  be  built  for  Myz  to  ^120 ;  but  Appolt's 
oven  3rields  daily  about  240  cwts.  of  coke — 66  to  67  per  cent  from  Duttweil  ooaL 
which  in  ordinary  coke-ovens  yields  only  61  per  cent.  It  should  be  mentioned,  thsft 
with  Appolt's  ovens,  the  coke  from  the  inner  and  outer  compartments  is  not  of  tha 
same  quality  and  compactness,  owing  to  the  higher  degree  of  heat  prevaiHng  in  tlie 
former. 

We  may  mention  briefly  the  following  contrivanoes  for  preparing  coke,  based  npon  the 
same  principle  as  Appolt's.  Marsilly's  oven  is  covered  with  a  brick  arch,  ftftTnmiiT>^f8^fing 
with  a  flue  through  which  the  gases  and  vapours  are  carried  under  the  hearth  of  the  oyen, 
and  by  burning  there  heat  it.  Jones's  oven  is  similarly  constructed,  but  with  the  differ- 
ence that  the  combustion  of  the  gases  and  vapours  is  made  to  take  place  in  the  coking 
kiln.  This  arrangement,  used  only  with  very  dry,  non-bituminous  coals,  certainly  aeasts 
the  coking  process,  because  the  air  is  heated  previous  to  entering  the  kiln.  Frommont's 
double  cooking  oven,  in  use  on  the  Maas,  in  Belgium,  as  well  as  in  Westphalia,  and 
at  Saarbriicken,  is  a  stage  oven,  so  constructed  that  the  gases  formed  in  the  lower  coking 
compartment  are  carried  through  channels  to  the  upper  hearth ;  thence  with  the 
gases  formed  in  the  upper  compartment,  are  conveyed  under  the  hearth  of  the  lower 
oven,  and  thence  through  lateral  channels  to  the  chimney,  so  that  the  heat  is  thorough^ 
utilised.  Gendebien's  coking-oven  is  distinguished  from  that  of  Frommont,  in  bo  far  that 
one  of  the  upper  coking  compartments  is  placed  over  two  of  the  lower ;  these  ovens  are 
chiefly  used  on  the  Sambre  (Belgium).  The  coke-ovens  according  to  Smet's  pJan  are 
inclusive  of  the  principles  of  all  ovens  built  to  utilise  the  heat  of  the  combustible  gases. 

Dubochet's  coking-oven,  constructed  in  185 1  by  PoweU,  is  a  tubular  oven  with  doping 
hearth,  consisting  of  two  shallow  curved  parts  placed  one  above  the  other,  and  separated 
by  doors.  The  upper  part  is  the  distillatory  furnace  or  oven,  the  gases  and  vapoun 
there  evolved  being  conveyed  under  the  oven,  and  burnt  with  admission  of  air,  the  heat 
evolved  by  this  combustion  serving  to  coke  the  coals.  The  coke  is  caused  to  fall  into  a 
eooling  oven,  from  which  it  is  removed  when  extinguished.  The  combustible  gases  evolved 
by  this  process  are  sometimes  employed  for  the  purpose  of  heating  a  steam-boiler 
belonging  to  the  coal-washing  machinery.  In  the  coke-oven  built  upon  Knab's  plan,  the 
gases  evolved  from  the  coaJ  are,  previous  to  being  burnt,  deprived  of  the  tar  and 
ammoniacal  water  carried  ofif  by  them.  For  this  purpose  the  gases  are  conveyed  to  two 
large  cylindrical  vessels  filled  with  coke,  and  in  which  nearly  all  the  tar  is  deposited ; 
thence  the  gases  are  conveyed  to  a  system  of  tubes  connected  with  water  reservoirs  for  the 
purpose  of  eliminating  the  ammoniacal  products.  The  purified  gases  are  then  conveyed 
to  the  furnace  to  be  there  burnt  from  a  large  circular  burner,  to  the  centre  of  which  air  is 
admitted.  The  necessary  motion  is  imparted  to  the  gases  by  bell-shaped  exhansters, 
which  draw  the  gases  from  the  furnace  through  the  purifying  apparatus  and  force  them  to 
the  burner.  According  to  the  statement  of  Gaultier  de  Glaubry,  there  are  150  tons  of 
coal  converted  daily  into  coke,  in  eighty- eight  ovens  belonging  to  the  Soci^t^  de  Carbonisa- 
tion de  la  Loire,  near  St.  Etienne.     The  yield  in  100  parts  is : — 


Coarse  coke  (large  lumps)  . .  70*00 

Small  coke 1*50 

Breeze 2*50 

Graphite       0*50 


Tar 4'oo 

Ammoniacal  water 9*00 

Gas 10*50 

Loss 1*92 


It  is  questionable  whether  the  coke  thus  obtained  is  equal  in  quality  with  that  obtained 
by  the  ordinary  coke-ovens ;  because  experience  proves  that  all  coke  prepared  in  close 


FUEL, 


729 


Tesselfl,  is  rather  poroufl  and  less  suitable  for  use  on  locomotiye  engines  and  in  blaat- 
fumaoea. 

Very  small  coal  and  dast  are  converted  into  coke  in  ovens  built  similarly  to  those  osed 
for  baking  bread.  The  large  quantities  of  refase  coal,  screenings,  d^o.,  formerly  waste,  to 
be  found  in  enormous  heaps  near  coal-pits,  and  to  effect  their  removal  being  frequently 
set  on  fire,  burning  for  month  after  month,  producing  huge  volumes  of  smoke,  are  now 
utilised  and  made  into  excellent  coke,  after  having  been  first  washed. 

The  coke  drawn  from  the  ovens  is  extinguished  with  water  or  under  ash.  The  former 
plan,  however,  is  most  frequent,  and  has  the  advantage  of  giving  to  the  coke  a  peculiar 
silvery  gloss.  There  is,  however,  more  than  one  objection  to  this  mode  of  extinguishing 
ooke,  because  in  the  first  place  the  coke  absorbs  and  retains  some  water,  which  as  it  has  to 
be  evaporated  when  the  coke  is  burnt,  absorbs  a  portion  of  the  heat  generated  by  the 
combustion.  Secondly,  the  weight  of  the  coke  is  increased,  and  may  be  increased 
fraudulently  to  a  large  extent^  as  some  portions  of  the  coke — the  more  porous  lumps — ^take 
up  I20  per  cent  of  their  weight  of  water,  while  the  dense  metallic  portion  takes  up  only 
X}  per  cent.,  and  the  coke  from  the  bottom  part  of  the  oven  13  per  cent.  On  an  average 
the  coke  takes  up  by  being  extinguished  by  water  6  per  cent  of  its  weight ;  but  cold  coke 
takes  up  when  thrown  into  water  hardly  half  as  much. 

ProptftiM  of  cok*.  Well  burnt  coke  or  oven  coke,  is  a  hard,  uniform,  compact,  solid 
mass,  difficult  to  break,  and  not  honeycombed,  nor  very  porous.  Its  colour  is  black- 
grey  or  iron  grey,  with  a  dull  metallic  gloss.  Good  coke  should  contain  very  little 
sulphur.  All  the  sulphur  contained  in  coal,  chiefly  as  iron  pyrites,  cannot  be  com- 
pletely eliminated  by  the  coking  process,  as  the  sulphuret  is  only  reduced  to  a  lower 
degree  of  snlphuration.  In  the  north  of  England  it  has  been  found,  that  if  the  coal, 
even  when  highly  sulphurous,  is  first  treated  with  a  strong  brine  and  powdered  rock- 
salt,  a  coke  very  free  from  sulphur  is  obtained.  The  sulphur  in  coke  is  objectionable, 
from  its  action  upon  the  ironwork  of  the  furnaces,  the  fire-bars,  &c. 

SdTiKvSuiMPuii.      '^^^®  average  composition  of  good  coke  is  tlie  following : — 

Carbon        85 — 92  per  cent. 

A.SX1      «••     •••     •••     •»•     •••  3^^  5 

Hygroscopic  water    5 — 10 


Owing  to  the  great  density  and  compact  structure  of  coke,  and  the  fact  that  it  does 
not  contain  any  combustible  gases,  it  is  ignited  with  difficulty,  and  requires  for  kind- 
ling a  strong  red  heat,  with  a  blast  for  continued  burning. 

According  to  a  series  of  experiments  in  Prussian  ii'onworks  with  coke  in  furnaces 
with  hot  blast : — 

100  pai-ts  by  weight  of  coke  =    80  parts  by  weight  of  charcoal. 
100      „        bulk  „      =  250  „  „  „ 

Brix  found  that  a  coke  made  from  upper  Silesian  coals,  and  containing  5*9  per 
cent  of  water  and  25  per  cent  of  ash,  yielded  for  every  kilo,  burnt  7' 15  kilos,  steam. 

Artificial  Fuel. 

Artificial  Fnei.  Under  this  name  we  understand  an  originally  pulverulent,  combus- 
tible fuel,  such  as  small  coal  or  coke,  breese,  sawdust,  refuse  wood,  Ac.,  ^xed  with 
tar  or  thin  clay  liquor,  and  by  strong  pressure  subsequently  moulded  in  the  shape  of 
bricks.  Compressed  peat  and  compressed  spent  tan  are  in  a  certain  sense  artificial 
fuel. 

TwM.  Under  this  name  is  known  an  artificial  fuel  first  prepared  from  caking  coal 
by  Marsais,  the  viewer  and  manager  of  some  collieries  near  St.  Etienne.  The  small 
coal,  screenings,  dust,  and  other  refuse,  are  first  lixiviated  for  the  purpose  of 


730  CBKMICAL  TECHNOLOGY, 

removing  mineral  impurities,  such  as  gangae.  clay,  pyrites,  &c.  Tlie  purified  cosl 
is  drained,  then  ground  to  powder  by  suitably  constructed  mill- work,  afterwards 
dried  by  the  application  of  heat,  then  mixed  with  7  to  8  per  cent  of  thick  coal-tar. 
and  finally  moulded  into  bricks  by  the  aid  of  strong  pressure,  the  brick-shaped 
lumps  weighing  each  about  20  lbs.  Peras  is  less  fragile  than  ordinary  coal,  and  being 
of  a  imiform  shape,  can  be  better  stored  than  coal,  taking  up  about  one-iifth  less  roooi, 
a  matter  of  considerable  advantage  on  board  steamers.  Similar  to  peras  are  the 
patent  coals  made  by  Wylam  and  Warlich. 

The  so-called  moulded  charcoal,  or  Parisian  coal,  introduced  about  fifteen  years 
ago  by  Popelin-Ducarr6,  is  an  artificial  fuel  composed  of  charcoal  refuse  with  coal- 
tar.  The  small  lumps  and  dust  of  charcoal  are  mixed  with  8  to  12  per  cent  of  water. 
then  ground  to  powder,  and  to  100  kilos,  of  the  powder  are  added  33  to  40  litres  of 
coal-tar.  Tliis  magma  is  thoroughly  incorporated  and  next  moulded  into  cylinders. 
These  are  dried,  and  finally  carbonised  in  a  muffle-furnace.  This  fuel  is  fsx  less 
fragile  than  ordinary  charcoal,  better  fitted  for  transport,  bums  better  than  coke,  and 
even  when  only  slightly  kindled,  continues  to  bum  in  air,  which  is  not  the  case  with 
coke. 

BriqaettoB.  When  strougly  caking  coal  is  heated  in  closed  vessels  to  260^  to  400^ 
and  then  compressed  in  moulds,  the  result  is  the  formation  of  a' hard  brick- shaped 
fuel,  very  suitable  for  domestic  use  as  well  as  for  steam  production.*  It  has  been 
found  that  the  manufacture  of  briquettes  can  be  advantageously  combined  with  the 
preparation  of  tar  for  the  purpose  of  extracting  benzol,  carbolic  acid,  naphthaline, 
asphalte,  and  anthracen. 

Gaseous  Fuel, 

OMeoosFtMi.  Tlie  utilisation  of  certain  combustible  gases  and  mixtures  of  these 
gases  as  fuel  has  been  practically  solved  only  during  the  last  few  years,  although  in 
metallurgical  operations  the  idea  of  sucli  utilisation  is  of  more  remote  date.  The 
combustible  gases  used  on  the  large  scale  as  fuel  are  those  evolved  from  blast- 
furnaces, and  from  coke-ovens  and  other  apparatus  in  which  these  combnstible  gases 
are  formed  as  the  by-product  of  industrial  operations.  The  composition  of  the  blast' 
furnace  gases  varies  of  necessity  according  to  the  kind  of  fuel  used,  the  temperatim 
of  the  furnace,  the  shape,  build,  and  lieight  of  tlie  latter,  the  pressure  on  the  blast,  Ac: 
The  combustible  gases  escaping  from  these  furnaces  consist  chiefly  of  carbonic  oxide, 
hydrocarbons,  hydrogen,  carbonic  acid,  nitrogen,  and  of  ammonia  where  coalor  eoike  is 
used  as  fuel.  The  so-called  generator  gases  are  those  combustible  gases  which  are 
evolved  from  solid  fuel,  coke,  peat,  or  wood,  by  its  carbonisation  in  a  separated 
furnace,  kiln,  or  oven,  with  or  without  the  aid  of  a  blast.  These  combustible  gases  may 
be  utilised  in  various  ways  and  obtained  from  fuel  which  is  not  otherwise  applicable 
as  such.    According  to  Ebelmen  these  gases  are  composed  as  follows : — 

Generator  gases  obtained  from : — 


Wood-oharooal. 

Wood. 

Peat. 

Coke. 

Nitrogen 

...     64*9 

532 

631 

648 

Carbonic  acid... 

o*8 

11-6 

140 

1*3 

Carbonic  oxide 

...     341 

34*5 

22*4 

338 

Hydrogen 

0'2 

07 

05 

01 

*  See  Th.  Oppler,  "  Die  Fabrikation  der  kunstlichen  Brennstoffe,  insbesondere  der 
gepressten  Kohlenziegel  oder  Briquettes,"  Berlin,  1864 ;  also  "  Jahresbericht  d^  ehem. 
Technologie,"  1864,  p.  760  ;  1866,  p.  333  ;  1868,  p.  800. 


•  WARMING.  731 

There  has  long  been  in  use  in  England  a  gas  mixture  obtahied  by  passing 
high-pressiu'e  steam  over  red-hot  coke  contained  in  retorts.  Siemens's  regenerative 
gas-fiimace,  described  on  pp.  24  and  273,  belongs  to  tliis  category.  Combustible 
gaseous  bodies  are  largely  utilised  in  metallurgical  operations,  puddliug-fomaces, 
zinc-smelting,  &c. 

**"  i^mT-i^if *  ^^  ^^s  ^^  ^^  years  been  frequently  suggested  that  a  cheap  gas 
should  be  manufactured  for  heating  purposes.  In  Berlin  a  company  has  been 
formed  under  tlie  technical  guidance  of  C.  Westphal  and  A.  Piitsch,  the  object  being 
to  prei)are  gas  from  brown-coal  at  Fiirstenwald,  a  distance  of  about  38  kilometres 
from  the  city.  Tlie  intention  is  to  construct  twelve  retort-houses,  each  to  contain 
seventy  furnaces  provided  witli  ten  retorts,  to  be  fired  as  in  Siemens's  regenerative 
gas-furnace.  The  purified  gas  is  to  be  forced  by  blowing-machines,  actuated  by 
steam-engines  of  360  nominal  or  500  indicated  horse  power,  into  a  main  pipe  of 
1*3  metres  diameter  constructed  of  boiler-plates  and  carried  above  ground  supported 
on  iron  pillars.  The  gas  will  be  collected  at  Berlin  in  twelve  gas-holders,  each  of 
750,000  cubic  feet  cai)acity.  The  pressure  of  the  gas  in  the  mains  and  service-pipes 
-within  tlie  city  wOl  be  i'5  centims.  water-gauge,  in  order  tliat  pipes  of  smaller 
diameter  may  be  used.  According  to  Ziureck,  the  composition  of  tlie  gas  obtainable 
from  the  brown-coal  is,  at  a  sp.  gi\  of  0*5451,  as  follows : — 


Hydrogen       

4236  per  cent. 

Carbonic  oxide       

4000    .,      „ 

Marsh  g}is       

11-37     V       »» 

Nitrogen 

317         »              M 

Carbonic  acid 

2*01     „      „ 

Condensable  hydrocarbons  ... 

109     „      „ 

A  gas  of  tliis  composition  will  answer  admirably  for  heating  purposes.  3000  cubic 
feet  of  it  are  in  heating  effect  equal  to  i  ton  of  brown-coal,  and  equal  to  ^  ton  of 
pit-coal,  the  ton  being  equal  in  this  case  to  275  to  300  lbs.  The  price  will  be  7 id. 
per  1000  cubic  feet,  so  that  the  heating  effect  3'ielded  by  it  as  compared  with  tlie 
price  of  a  ton  of  coals  will  be  about  4s.  6d.  The  works  are  constructed  for  an  annual 
production  of  9500  millions  of  cubic  feet  of  gas,  or  a  daily  supply  of  2}  millions  of 
cubic  feet. 

Hmting  Apparatus.^ 

wuming.  We  understand  by  waiming  the  heating  of  any  room  or  space  by  heat 
evolved  from  the  combustion  of  friel.  The  room  or  space  may  be  an  apartment  in  a 
dwelling-house,  a  church,  a  steam-boiler,  a  glass-house,  a  hothouse  in  a  botanical 
garden,  &c.  It  is  the  aim  of  technology  to  apply  the  fuel  so  as  to  yield  by  its  most 
economical  use  the  greatest  amount  of  heat.  In  order  to  obtain  by  the  combustion 
of  fuel  as  nearly  as  possible  its  absolute  and  specific  calorific  effect,  the  combustion 
should  not  only  be  complete,  but  the  gaseous  products  should  suffer  tlie  highest 
degree  of  oxidation ;  in  other  words,  neither  smoke  nor  any  combustible  gases 

*  The  following  works  alTord  very  valuable  information  on  this  subject : — C.  Sohinz, 
*•  Pie  WarmeMosskmiBt,"  Stuttgart,  1858  ;E.  P6olet,**  Traite  de  laChaleur,*'  3rd  edition, 
Paris,  1861-62,  3  vols ;  and  for  stoves  lor  domestic  use,  "  Die  Badische  Gewerbezeitnng," 
edited  by  H.  Meidinger. 


732  CHEMICAL  TECHNOLOGY. 

should  be  evolved.    The  pr&ctical  importance  of  this  principle  is  exhibited  by  the 
following : — 

I  part  of  carbon  yields,  when  burnt  to  carbonic  oxide,  2480  units  of  heat. 
I     „  „  „         ,.  M         carbonic  acid,    8080      „  ,, 

In  order  to  obtain  complete  combustion,  the  fuel  should  be  supplied  with  the 
requisite  quantity  of  air,  while  the  vitiated  air  should  be  carried  off  with  the  gaseous 
products  of  the  combustion.  This  supply  of  air  or  draught  can  be  assisted  artificially 
by  means  of  blast-  or  exhaust-apparatus ;  but  in  most  cases  the  draught  is  natoraL 
i.e.,  produced  by  the  calefaction  of  the  air,  which  becoming  specifically  lighter, 
ascends. 

All  heating  apparatus  consist  of  tliree  distinct  parts — ^the  fire-place  or  hearth,  the 
heating-room,  and  tlie  chimney.  The  hearth  is  that  portion  where  combustion  takes 
place.  The  heating-room  is  the  portion  of  the  apparatus  where  the  heat  generated 
is  utilised,  and  the  chimney  is  a  cliannel,  usually  placed  in  a  vertical  position,  and 
often  connected  by  means  of  flues  with  the  heating-room  and  hearth — ^through  which 
tlie  gases  evolved  by  the  combustion  of  the  fuel  are  carried  off,  and  a  draught 
created  maintaining  an  efficient  combustion  of  the  fuel. 

The  hearth  or  fire-place  may  vary  greatly  in  shape  and  mode  of  oonstmctioiL 
The  most  primitive,  but  also  the  most  defective  kind  of  hearth,  is  that  on  which  the 
fuel,  usually  wood  or  peat,  is  placed  on  tiles  or  bricks  under  the  chimney.  Such 
arrangements  are  still  in  use  in  many  remote  country  places,  especially  in  the 
country  districts  of  Ireland  and  Scotland,  where  faggots  of  wood  and  peat  are  tbus 
burnt.  In  this  manner  a  very  great  amount  of  heat  is  wasted  and  the  supply  of  air 
not  properly  regulated ;  there  is  an  excess  of  air  supplied,  and  hence  loss  of  fhd. 
The  air  required  for  the  complete  combustion  of  the  fuel  should  be  made  to  pass 
through  tlie  fuel,  which  for  that  purpose  is  placed  on  a  grating,  consisting  of  bars  of 
iron  or  fire-brick.  The  space  under  tlie  fire-bars  is  called  the  ash-pit,  through  which 
the  air  is  supplied  to  the  fuel.  The  hearth  is  usually  provided  with  iron-doora. 
which  are  opened  when  fresh  fuel  has  to  be  introduced.  This  plan  is  accompanied 
with  the  objection,  tliat  during  the  period  of  feeding  and  raking  up  the  fire,  a  large 
quantity  of  cold  air  enters  Uie  hearth,  and  causes  the  combustion  to  become  irregular 
and  much  smoke  to  be  produced.  The  use  of  the  so-called  stage  fire-bars,  placed  in 
the  manner  of  steps,  one  above  the  other,  is  not  attended  with  this  defect. 

When  the  fuel  contains  much  sulphur,  the  iron  fire-bars  are  soon  worn  out,  owing 
to  the  formation  of  sulphuret  of  iron ;  in  order  to  prevent  tliis,  it  is  often  usual  to 
leave  a  layer  of  clinkers  and  slag  on  the  bars  for  the  purpose  of  protecting  them  from 
the  direct  action  of  the  fuel.  In  order  to  regulate  the  draught,  dampers  or  similar 
contrivances  are  fitted  to  the  flues,  chimney,  or  funnel. 

a.  Heating  Dwelling  Houses. 

HMttins  DwdUng  HoaflM.  The  heating  of  dwelling-houses  and  public  buildings,  halK 
theatres,  churches,  &c.  (in  connection  with  tlie  ventilation),  can  be  effected  in 
various  ways,  either  by  radiant  or  conducted  heat.  According  to  the  construeticn 
of  the  heating  apparatus,  we  distinguish: — i.  Heating  by  flues.  2.  By  stoves,  or 
with  hot  air.  3.  Air  heating.  4.  By  means  of  steam  or  hot-air  pipes.  5.  Hot- water 
heating.    6.  Heating  by  means  of  gas. 

xMiMt  Haatinit.  The  direct  heating  of  rooms  by  the  combustion  of  wood  and  other 
fuel  on  an  open  hearth,  or  in  chauflng- dishes  and  small  stoves  without  chimneys,  » 


WARMING,  733 

undoubtedly  the  most  ancient  and  primitive  method  of  heating.  In  the  centre  of 
the  huts  in  Ireland  and  the  Highlands  of  Scotland,  a  rough  hearth  is  constructed, 
^hile  the  smoke  evolved  by  the  fuel  escapes  through  a  hfile  in  the  roof.  In  some 
parts  of  Fratice,  Italy,  Spain,  and  Turkey,  rooms  are  heated  by  means  of  a  chaufing- 
dish  containing  burning  charcoal,  by  the  combustion  of  whicli  the  air  of  the  room  is 
vitiated,  becoming  unfit  to  be  respired  by  the  lungs.  It  is  evident  that  for  this 
reason  and  owing  to  the  risks  of  fire  this  mode  of  heating  is  very  dangerous. 

Chimney  HeaUng.  This  mode  of  heating,  in  general  use  in  England  and  the  larger 
towns  of  Scotland,  Ireland,  and  Wales,  is  of  ancient  use,  and  is  based  upon  the 
heating  of  the  air  of  the  rooms  by  the  direct  radiation  of  the  heat  of  the  fire.  It  is 
tmdoubtedly  the  most  imperfect  and  wasteful  method,  as  tliere  flows  into  the  chimney 
a  very  large  excess  of  air  above  that  required  for  maintaining  the  combustion  of  the 
fuel,  the  consequence  being  that  strong  draughts  of  cold  air  are  felt  near  tlie  windows 
and  doors  of  the  rooms,  while  a  downward  current  of  air  is  frequently  created, 
causing  the  chimney  to  smoke.  This  mode  of  heating  only  suits  countries  enjoying 
an  average  mild  climate  and  possessed  of  plenty  of  fuel.  It  would  appear  that 
among  the  reasons  why  this  mode  of  heating  is  continued  is  the  pleasure  of  seeing 
the  fire  and  of  warming  the  feet  by  it,  notwithstanding  that  the  other  parts  of  the 
body  remain  comparatively  cool.  The  arrangements  of  the  metliod  of  warming  by 
the  radiant  heat  from  cliimneys  are  in  the  most  piimitive  form  the  following : — At 
the  lower  part  of  the  wall  from  which  the  chimney  is  built,  a  niche  or  recess  is 
constructed  in  which  the  fuel  burns ;  but  in  grates  of  better  construction,  the  recess 
is  not  very  deep,  and  less  contracted  where  it  issues  in  the  chimney,  while  frequently 
the  hearth  is  fitted  with  a  sliding  door,  and  a  valve  or  trap-door  in  the  upper  part  of 
the  flue  leading  into  the  chimney. 

In  order  to  utilise  a  portion  of  the  conducted  heat,  yet  still  to  leave  the  heating  to 
be  effected  chiefly  by  radiation,  the  flow  of  hot  air  into  the  chimney  is  to  some  extent 
intercepted,  so  as  to  form  a  combination  of  the  methods  of  stove-  and  chinmey- 
heating. 

8toT«  HMti&ff.  Tliis  method  of  heating  is  in  general  use  in  the  colder  parts  of  the 
Continent,  in  America,  Canada,  &c.  A  well  constructed  stove  should  not  consume 
too  much  fuel,  the  combustion  of  which  should  be  complete,  while  the  heat  generated 
should  be  uniformly  I'adiated,  and  only  a  very  small  quantity  allowed  to  escape  into 
the  chimney.  As  a  stove  is  placed  at  some  distance  from  tlie  chimney,  the  radiating 
as  well  as  the  conducted  heat  is  utilised.  The  loss  of  heat  is  prevented  by  a  series 
of  flues ;  but  in  order  to  keep  up  a  sufficient  draught,  the  air  escaping  into  the 
chimney  should  have  a  temperature  of  at  least  75".  The  fuel  is  generally  intro- 
duced into  the  stove  from  the  room,  although  some  kinds  of  stoves  are  so  constructed 
that  they  may  be  fed  with  fuel  from  the  outside  of  the  house  similarly  to  the  hot- 
house stoves ;  this  method  of  construction  entails  a  larger  consumption  of  fuel  and 
some  loss  of  heat. 

Stoves  are  made  of  cast-iron,  sheet-iron,  and  fire-clay.  Iron  readily  absorbs  heat, 
and  as  the  sides  of  the  stove  are  usually  not  very  thick,  the  heat  is  rapidly  and 
readily  dispersed.  As  ii'on  stoves  may  become  red-hot,  the  air  surrounding  the 
stove  is  chemically  changed  in  consequence  of  the  permeability  of  red-hot  iron  to 
carbonic  oxide  This  gas,  according  to  the  experiments  of  Deville  and  Troost,  1868, 
is  absorbed  and  evolved  by  red-hot  iron  to  0*0007  to  0*0013  ^^  volume.  Fire- 
clay stoves  yield  a  very  uniform  heat,  given  off  only   slowly   and   gradually. 


734 


CHEMICAL  TECHNOLOGY, 


Compound  stoves  are  those  in  which  tlie  hearth  is  made  of  cast-irun,  on  which  is 
placed  a  sheet-iron  column  closed  at  the  top,  and  provided  with  a  lateral  opening 
communicating  by  sheet-iron  pipe  with  the  chimney. 
We  distinguish  according  to  the  material  of  which  stoves  are  constructed : — 

a.  Those  simply  of  iron. 
h.  Those  of  fire-day. 
c.  Compound  stoves. 

Iron  stoves  are  usually  so  constructed  that  the  heat  generated  by  tlie  corabnstioQ 
of  the  fuel  is  rapidly  communicated  to  the  air  of  the  room.  The  heat  generated  in 
fire-clay  stoves  is  commuuicated  to  tlie  great  mass  of  fure-clay  of  which  the 
stoves  are  constructed,  so  that  even  long  after  tlie  fire  has  been  extinguished 
the  stove  continues  to  give  off  heat ;  these  stoves  are  especicdly  used  in  Sweden 
and  llussia. 

Iron  stores.  The  constructlon  of  these  stoves  varies  greatly.  WTien  made  of  cast- 
iron  the  shape  is  frequently  cylindrical,  a  short  pipe  being  cast  on.  to  whicli  is  fitted 
a  sheet-iron  pipe  leading  to  tJie  chimney.  In  some  cases  the  length  of  this  pipe  is 
considerable,  in  order  that  the  heat  evolved  by  the  combustion  of  the  fuel  may  be 
better  utilised. 

Sometimes  iron  stoves  are  constructed  with  an  outer  mantle  which  is  perforated 
and  usually  exhibits  an  ornamental  appearance ;  this  mantle  is  placed  at  some  few  laches 
distance  from  the  inner  stove,  in  which  the  combustion  of  the  fuel  takes  place. 

Firc-dny  8toTo».  These  RtoTes,  raado  of  a  pecuUar  kind  of  clay,  are  externally  glazed 
similarly  to  the  so-called  Dutch  tiles.  The  construction  of  these  stoves  is  very  massiTe. 
They  consist  of  a  series  of  channels  made  of  burnt  clay  and  put  together  with  a 
mixture  of  the  same  clay  unbumt  and  gypsum.  The  thickness  of  the  pipes  forming  the 
channels  is  7  inches.  The  number  of  channels  or  flues  is  four  to  six,  or  even  twelTC. 
The  Russian  stove,  Fig.  321  m  ground  plan,  is  fitted  with  six  flues.    Fig.  322  is  a  front, 

Fi^*  323  a  side  view,  and  Fig.  324  a  vertical  section. 
a  is  the  vaulted  fire-place,  the  flame  and  smoke 
evolved  by  the  combustion  of  the  fuel  being  carried 
upwards  in  flue  i,  downwards  in  flue  2,  again  up- 
wards in  fine  3,  agnin  downwards  in  flue  4,  again 
upwards  in  flue  5,  and  again  downwards  in  fine  6^ 
and  thence  into  the  chimney  by  means  of  an  iron 
pipe  fltted  to  the  stove. 

Each  of  these  stoves  has  a  separate  chimney,  a 
tube  18  to  30  centimetres  wide,  carried  straight  up  to 
above  the  roof  of  the  house.  These  narrow 
chimneys,  also  in  use  in  Edinburgh,  Glasgow,  and 
other  Scotch  towns,  are  constructed  of  fire-claj 
tubes  fltted  into  the  atone  of  the  walls.  As  a  Bussian 
stove  is  really  intended  to  be  a  store  of  heat,  it  has  to  bo  hermetically  closed  as  soon  as 
the  fire  is  extinguished ;  this  is  effected  by  the  following  contrivance,  termed  in  the  Bussian 
langua(;e,  Wiuschke.  Near  the  junction  of  the  last  flue  and  Uie  stove-pipe  a  plate  of  eaat- 
iron,  Figs.  325,  326,  and  327,  is  fltted  to  the  stove,  the  plate  being  provided  in  the  centre 
with  an  opening  of  21  to  24  centimetres  diameter.  This  opening  has  an  internal  vertical 
flange  or  collar  of  2  centimetres,  and  an  external  vertical  flange  of  3  centimetres  height. 
An  iron  cover,  a,  Fig.  327,  flts  closely  on  to  the  inner  flange,  and  a  larger  cover,  6,  fits  on 
to  the  outer  flange,  thus  securing  a  tight  joint.  These  ovens  are  heated  with  wood, 
which  is  sawn  into  small  blocks.  Ko  smoke  is  evolved,  because  the  high  temperature  pre- 
vailing in  the  flues  consumes  the  smoke  compl<itely,  and  the  wood  is  not  used  until  it  ii 
thoroughly  dry.  The  Swedish  stove  is  usually  cylindrical  in  shape,  and  very  tall,  reaching 
nearly  to  the  ceiling  of  the  rooms.  The  flues  (four  in  number)  of  these  stoves  are  of 
rather  complicated  construction.  They  communicate  laterally  with  each  other.  The 
chimney  pipe  is  placed  at  the  top  and  is  provided  with  a  damper,  closed  when  the  fire  is 
extinguished.  The  fuel,  dry  wood,  required  for  one  heating  of  the  stove,  is  put  into  the 
stove  at  one  charge,  and  when  the  combustion  has  ceased,  the  damper  and  the  stove  doat 
are  tightly  closed. 


Fio.  321. 


! 

'  - 

Ir 

u' 

f 

f" 

m 

\L.- 

^PCl 

and  330  vertioftl  flaotioofl.     The  section  exbibiteil  in  Fig.  339  is  Ibrough  the  grooad  plan, 
Fig.  331,  lu  indicated  b?  the  dotted  liuoi  a.  The  section  ehonuinFig.  330  is  according  to  tho 
Fro.  3'S- 


dotted  line  br  and  the  section  exhibited  in  Fig.  331  to  the  line  cc     Tbe  henrth  of  this 
stove  is  constructed  of  iron  anrrounded  by  a  bvimt  olaj  mimtle  or  boi.    The  prodncta  of 


J 


736 


CHEMICAL  TECHSOIOGY. 


Fl8.  331- 


_  .  .  iS  centims.  width,  ttii 

mbiiBtinu  in  very  complete,  no  aooi  or  smoke  being  formad. 
This  store  ia  divided  into  two  compartmentB  by  means  of  ■ 
yerticnl  nail ;  and  honxontal  shelves  &re  Stted  to  this  vH, 
tbUB  focming  a  senen  of  chaimela  or  flnea,  throngli  niiidi 
the  prodacte  of  combustion  are  made  to  pnas.  Tha  length 
of  these  flues  viuieFi,  acuordiog  to  the  size  of  the  stoTS.  from 
9  to  30  metree.  As  the  hearth  is  bo  placed  as  (o  be  a  sepa' 
rate  part  of  the  store,  the  room  becomeahpatedae  soon  as  the 
fite  is  lighted.  In  the  lover  put  of  the  stove  a  kind  ol  air- 
beating  is  arranged,  because  bj  two  openinKS,  ea.  Fig.  31S, 
cold  air  enters  and  becomes  strongly  heated  while  passing 
through  the  stove.  Whenthecombuetion  of  thefuel  has  ceased 
thedamperin  the  pipe  leading  to  the cbimtie;riBcloB^:  the  olayportionof  the  stove  having 
then  been  so  strongly  heated  that  one  firing  answers  for  a  whole  da;,  bbb  is  the  brick- 
work foot  of  the  stove;  cc  ore  eupporta  for  carrjitig  the  cast-iron  bed-plate,  d if ,  of  the 
iron  hearth  ;  e  are  the  side  plates  ;  //  the  top  plate  ol  the  fire-room ;  ^  is  a  tabe  fitted  to 
the  top  plate,  and  intended  for  carrying  o&  the  gasea  and  other  prodacts  of  the  eotnbiii. 
tion  of  the  fael.  On  the  top  plate  are  placed  fire-bricks  Eupporting  hh,  which  is  mode  of 
boiler-plate,  and  provided  with  a  circular  hole  bo  situated  as  to  be  free  from  the  tube  f- 
Oa  this  boiler-plate  are  roofing  tiles,  which  reach  to  the  side  walls  of  the  stove,  and  are 
ooveud  with  sand  or  dry  ash.  This  eoustruction  ia  necessai;  for  the  purpose  of  pre- 
venting the  iron  bearth  iu  its  expansion  forcing  oaonder  the  hriokwork. 

The  vertical  partition  wall,  i,  in  boilt  of  brick ;  it  supports  k,  t  t  are  alao  bnill  of 
brick,  n  n  are  so  short  that  each  of  the  openinga  is  7  inches  distant  from  the  opposits 
aide.  The  smoke  is  carried  upwnrda  throngh  the  openings  on.  p  p  iit  the  iron  fift, 
which  oommniiicates  with  the  chimney.  The  heat  and  gases  generated  by  the  combustion 
of  fuel  iu  this  stove  proceed  from  the  hearth,  e,  throngh  .7,  are  returned  hy  *,  flow  along  i, 
pass  through  the  opening  0  into  the  flue  11,  and  finally  into  the  pipe,  which  commnDieata 
with  the  open  air. 

Hensehel's  stove,  constructed  to  barn  brown-coal,  deserves  notice.  Fig.  331  exhibit*  • 
vertical  sectiou,  aud  Fig.  333  a  horizontal  section  at  the  line  t  b.    This  atove  conaiati  of 

Flo  33J 


two  iron  ojlinders,  the  onter,  a,  being  ol  oast-iron,  the  inner,  i,  of  stout  sheei-inm. 
The  outer  cylinder  is  supported  by  the  ash-pit,  c  d,  fitted  with  flre-ban  towards  the  apper 
end.     The  inner  iron  thunder  does  not  reacn  to  the  flre-bora,  and  is  oloaad  at  the  top  bj 


WARMING.  737 

a  tightly-fitting  oover,  g,  while  the  outer  cylinder  is  cloeed  by  the  lid  h.  When  it  is 
intended  to  heat  this  stove  it  is  first  filled  with  brown-coal,  thrown  in  from  the  top  after 
remoYal  of  the  lids.  The  fuel  is  kindled  at  i,  through  k.  The  combustion  can  only  take 
place  on  the  fire-bars,  the  hot  air  flowing  upwards  between  the  two  cylinders,  and  thence 
into  Z,  the  iron  pipe  leading  to  the  chimney.  The  fuel  contained  in  the  inner  cylinder 
gradually  sinks  downwards  as  the  combustion  proceeds.  The  ash  is  removed  by  imparting 
motion  to  the  crossed  iron  bars,  m.  Fig.  333,  to  which  are  fitted  pieces  of  iron  passing 
between  the  fire-bars.  The  handle,  n,  projects  outside  the  stove.  Any  smoke  which 
might  reach  the  upper  part  of  the  stove  is  carried  off  by  the  pipe  0.  This  kind  of  stove 
having  once  been  filled  with  fuel  continues  to  supply  heat  for  forty-eight  hours. 
Meidinger,  of  Carlsruhe,  has  constructed  many  very  excellent  stoves  of  this  description. 

Air  Heating.  This  method  of  heating  is  effected  by  means  of  stoves,  but  is  dis- 
tinguished from  the  ordinary  stove-heating  by  the  situation  of  the  stove,  which  is 
in  most  cases  not  placed  within  the  space  or  room  to  be  heated,  being  within  a 
chamber  from  which  the  heated  air  is  conveyed  by  channels  to  the  space  intended 
to  be  warmed.  The  aim  of  air  heating  or  central  heating  is  to  heat  a  large  space 
uniformly  with  one  stove,  or  to  heat  by  means  of  one  fireplace  all  the  rooms  and 
apartments  in  the  same  building,  when  it  is  not  found  convenient  to  construct  fire- 
places in  each  apartment.  There  are  in  use  three  modes  of  air  heating,  which 
differ  from  each  other  in  the  method  of  ventilating  the  space  to  be  heated. 

(a.)  The  cold  air  enters  the  heating  apparatus,  becomes  warm,  and  is  conveyed  through  a 
pipe  or  channel  into  the  room  or  space  to  be  heated,  while  an  equal  bulk  of  vitiated  air 
escapes  from  the  imperfectly-closed  windows  and  doors. 

(6.)  The  heated  air  is  returned  to  the  heating  apparatus,  becomes  again  warmed,  and 
re-enters  the  room.  While  the  method  (a)  has  the  advantage  of  constantly  supplying 
fresh  air  to  the  room,  thus  creating  an  uninterrupted  ventilation,  the  method  (&)  has  the 
advantage  of  saving  that,  quantity  of  heat  which  is  lost  in  the  efiluz  of  warm  air  in  the 
first  method. 

(c.)  The  outer  air  becomes  heated  at  the  fireplace,  and  is  then  conveyed  to  the  room  to 
be  warmed.  The  vitiated  air  from  the  room  is  conveyed  through  a  flue  to  the  fire,  this 
air  serving  the  purpose  of  maintaining  the  combustion.  This  method  combines  all  the 
advantages  of  (a)  and  (5),  while,  with  constant  ventilation,  a  saving  of  fuel  is  effected. 

As  regards  the  methods  of  employing  air  heating,  we  distinguish  according  to  the 

construction  of  the  apparatus : — 

(a.)  Air  heating  by  means  of  a  mantle  oven. 
(b.)  Air  heating  by  means  of  a  heating  chamber. 

The  first  method  is  very  similar  to  ordinary  stove-heating,  and  only  distinguished 
firom  it  in  the  respect  that  the  stove  is  surrounded  by  an  outer  mantle  of  bricks 
or  fire-clay  slabs,  some  6  to  8  inches  from  the  stove.  This  niantle  is  provided  with 
openings,  through  which  the  heated  air  escapes,  and  is  uniformly  distributed  through 
the  room. 

In  warming  with  a  separate  chamber  we  have  to  consider  the  form  of  the  chamber, 
a  small  vaulted  room,  built  of  brickwork,  and  containing  the  furnace.  The  heating 
chamber  should  be  comparatively  very  small,  so  that  the  heated  air  shall  be  carried 
as  rapidly  as  possible  to  the  room  intended  to  be  warmed.  The  channels  for 
carrying  off  the  heated  air  are  placed  at  the  top  of  the  heating  chamber,  while  the 
channels  for  conveying  the  cold  air  are  situated  at  the  bottom.  The  space  between 
the  furnace  and  the  walls  of  the  heating  chamber  measures  from  12  to  16  centims., 
but  the  vault  is  elevated  i  to  1*3  metres  above  the  top  of  the  furnace. 

The  furnace  or  stove  is  the  most  essential  part  of  this  air-heating  apparatos.  It 
is  made  either  of  cast-iron  or  of  boiler  plate ;  and  as  regards  size  i  square  foot  of 
heating  surface  is  capable  of  heating  800  to  1000  cubic  feet  of  air.  Another  kind 
of  air-heating  apparatus  consists  of  the  following  arrangement :— A  series  of  rows 

3  » 


738  CHEMICAL  TECHNOLOGY, 

of  cast-iroa  tabes,  which  communicate,  are  so  placed  in  a  furnace  or  oven  that  cM 
air  enters  into  the  lowest  row  of  the  series,  while  the  heated  air  escapes  from 
the  upper  row.  Since  the  hot  air  having  become  specifically  lighter  always  tends 
to  rise,  it  is  clear  that  the  apparatus  should  be  placed  in  the  cellar  or  lowest  room 
of  the  building  to  be  heated.    The  hot-air  pipes  should  be  as  vertical  as  possible. 

The  apertures  througli  which  the  hot  air  gains  admission  to  the  rooms  to  be 
heated  are  best  situate  in  the  floor,  in  this  case  generally  a  double  one ;  or  the  hot- 
air  pipes  are  placed  in  channels  covered  with  an  iron  grating,  and  sometimes 
provided  with  a  damper  so  that  the  supply  can  be  regulated. 

Heating  with  hot  air  is  usually  attended  with  a  serious  defect,  viz.,  that  the  air 
is  exceedingly  dry  or  even  burnt.  This  defect  can  be  remedied  only  by  supplying 
air  with  aqueous  vapour  by  placing  in  the  current  of  hot  air  shallow  basins  filled 
with  water,  or  by  suspending  wet  sponges  near  the  pipes.  Dr.  von  Pettenkofer  has, 
however,  proved  that  these  expedients  do  not  quite  answer  the  purpose.  Air  heating 
is  not  very  suitable  for  dwelling-houses,  but  answers  best  for  public  buildings,  whidi, 
as  churches,  theatres,  and  concert  rooms,  require  to  be  only  occasionally  heated,  the 
defect  of  the  too  great  dryness  of  the  air  being  in  these  instances  counterbalaneed 
by  the  watery  vapour  exhaled  in  the  process  of  respiration  by  the  persons  assembled, 
and  by  the  gas  lights. 

oaioiiferM.  A  systcm  of  air-hoating  by  means  of  so-called  calorif&res  has  becooae 
rather  general  in  the  United  Kingdom,  North  America,  Sweden,  Russia,  HoUaad, 
Belgium,  and  also  to  some  extent  in  Germany.  It  is  usually  employed  in  large 
buildings,  but  ia  also  applicable  to  dwelling  houses.  Among  the  best  of  this  kind  of 
heating  apparatus  are  those  supplied  by  the  London  Warming  and  Ventilating  Com- 
pany, who  «nploy  the  modification  of  a  plan  successfully  introduced  by  ^  Golds- 
worthy  Gumey  in  both  houses  of  Parliament.  Steam,  hot  water,  gas,  and  ooal  or 
coke,  in  open  or  enclosed  fire-places,  are  equally  available  for  the  process,  while 
the  cost  is  less  and  the  effect  greater  than  with  any  other  known  means.  Tlie 
apparatus  are  successfully  in  use  in  St  Paul's  Cathedral,  York  Minster,  eighteen  other 
cathedrals,  looo  churches  in  England,  and  a  large  number  of  government,  puUie. 
and  private  buildings,  and  mansions.  Abroad,  Hartmann  at  Augsburg,  Boyer  and 
Co.  at  Ludwigshafen,  Bacon  and  Perkins  at  Hamburg,  have  invented  more  or  lets 
excellent  calorif^res.  Those  by  Beinhardt  and  Sammet,  at  Mannheim,  appear  to  be 
of  very  great  efficacy ;  they  are  so  contrived  that  the  fuel  is  thoroughly  burnt,  not 
even  any  soot  or  smoke  being  left,  while  the  air  is  rendered  agreeably  moist  by  the 
gentle  dripping  of  water  on  the  hot-air  gulls.  The  temperature  of  the  air  can 
be  kept  uniform  for  days  and  weeks  consecutively.  As  this  apparatus  if  used  in  a 
dweUing-house  is  placed  in  the  cellar  and  the  whole  house  heated,  there  is  no  dut 
nor  other  inconvenience  attending  the  ordinary  fire-places.  This  apparatos  con- 
sumes only  a  small  quantity  of  Aiel,  and  requires  as  an  attendant  an  ordinaiy 
labourer.  In  the  air-heating  apparatus  invented  by  Boyer  and  Co.,  Ludwigshafen, 
now  in  use  in  many  large  buildings  in  Munich,  Wiirzburg,  and  other  Bavanaa 
towns,  the  heating  pipes  are  not  made  of  wrought-iron  but  of  charcoal  east-iraa, 
while  the  dimensions  and  shape  are  so  arranged  as  to  expose  the  pipes  as  little  as 
possible  to  iijury  from  the  fire,  and  yet  to  afford  a  large  heating  surface.  For  ewrj 
kilo,  of  coals  hourly  biimt,  2*5  square  metres  of  heating  surface  are  present  In  ordcsr 
thoroughly  to  utilise  the  heat  of  the  products  of  combustion,  these  products  are 
caused  to  pass  through  a  series  of  pipes,  some  of  which  are  coated  with  a  nDOotii 


WARMING.  759 

layer  of  mortar,  for  the  pnrpose  of  preyenting  loss  of  heat  by  radiation.  The  heat 
of  the  products  of  combustion  escaping  into  the  chimney  is  below  loo'' ;  and  these 
products  consist  only  of  watery  vapour  and  carbonic  acid.  In  order  to  render  the 
hot  air  supplied  by  this  apparatus  pleasantly  moist,  water  is  evaporated  with 
the  heated  air  at  the  rate  of  1*5  to  2  litres  per  100  cubic  metres  heating  surfEuse. 

ThM  Heating.  This  modc  of  heating,  now  confined  to  hothouses  for  plants,  and  even 
there  superseded  by  better  methods,  consists  chiefly  in  carrying  the  products  of 
combustion  of  a  stove  or  furnace  through  a  series  of  pipes  which  are  placed  within 
the  room  to  be  heated,  and  are  at  the  opposite  end  to  the  furnace  connected  with  a 
chimney.  If  this  plan  is  adopted  for  heating  dwelling-houses,  the  furnace  is  placed 
in  the  cellar ;  but  experience  hftS  shown  that  this  method  of  heating,  except  in  the 
case  of  hothouses,  is  too  crude,  and,  moreover,  dangerous,  as  by  overheating  of 
the  flues  fire  may  ensae. 

Hot.wftterH«atfntf.  Instead  of  heating  air  directly,  it  is  often  heated  intermediately  by 
water,  which,  owing  to  its  high  specific  heat,  is  eminently  adapted  to  this  pnrpose. 
This  kind  of  heating  is  known  as  hot-water  heating,  i  kilo,  of  water  at  100''  emits, 
while  cooling  to  20**,  80  units  of  heat,  capable  of  heating  32  kilos.,  or  24*61  cubic 
metres  of  air  to  10°.  The  system  of  hot- water  heating  is  based  upon  the  placing  of 
a  vessel  filled  with  hot  water  in  the  space  to  be  heated,  care  being  taken  to  keep  up 
the  temperature  of  the  water.  In  the  ordinary  hot- water  apparatus,  the  fluid  is 
never  heated  higher  than  its  boiling-pomt,  and  is  usually  kept  many  degrees  below 
that  temperature ;  hence  this  method  is  termed  low-pressure  water  heating. 

This  low-pressure  or  ordinary  hot-water  heating  is  maintained — 

a.  By  circulation  through  a  c^psed  boiler  which  is  heated. 

b.  By  circulation  and  syphon  action  between  an  open  and  a  heated  vessel. 

a.  In  this  method  there  is  fitted  to  a  boiler,  quite  x^losed,  a  series  of  pipes,  through 
which  the  hot  water  is  conveyed  from  and  the  cooled  water  returned  to  the  boiler. 
The  principle  of  the  circulation  of  the  water  may  be  elucidated  by  Fig.  334.  The 
water  is  heated  in  a,  c  is  the  ascending  tube,  df  are  the 

tubes  through  which  the  water  is  returned  to  the  boiler. 
The  tube  e  serves  for  the  purpose  of  filling  the  apparatus 
with  fresh  water,  as  well  as  for  the  escape  of  any  air  or 
steam  which  might  be  evolved.  The  hot  water  ascending 
in  o  causes  a  circulation  in  the  apparatus,  which  when  once 
conmienced  is  maintained  as  long  as  the  heating  is  con- 
tinued. From  time  to  time  it  is  necessaiy  to  unscrew  the 
cap  at  0,  for  the  purpose  of  adding  a  small  quantity  of  water. 
Usually  e  is  provided  with  a  stop-cock,  which  admits  of  the 
introduction  of  a  funnel.  For  100  cubic  feet  of  space  to  be 
heated,  20  to  30  square  feet  of  heating  surface  are  required. 
The  heat  of  the  warm-water  apparatus  is  imparted  to  the 
rooms  through  stoves,  usually  made  of  sheet-iron.  These  stoves  are  cylindrical 
in  shape,  2  to  3  metres  high,  by  03  to  07  metre  diameter,  and  fitted  with  a 
series  of  pipes  in  which  the  air  becomes  heated  by  a  larger  hot- water  tube. 

b.  The  other  method  of  hot-water  heating  by  means  of  an  open  boiler  with 
syphon  action,  or  the  so-called  thermo-syphon  of  Fowler,  as  compared  with  the  first 
method,  has  the  disadvantage  that  from  an  open  boiler  a  considerable  loss  of  heat  is 
unavoidable,  while  it  is  difiicult  also  to  prevenf  accumulation  of  air  on  the  upper 


740  CHEMICAL  TECHNOLOGY. 

part  of  the  syphon  tnbe.  The  height  to  which  the  tuhing  can  he  carried  is  in  this 
system,  too,  limited  to  the  height  eqaivalent  to  the  atmospheric  pressure,  about  30  feel 
for  a  column  of  water. 

Perkins's  so-called  high-pressure  hot  water  system,  wherein  the  temperature 
of  the  water  in  immediate  contact  with  the  fire  is  raised  to  150°,  200**,  and  even  500*, 
consists  of  a  closed  tube  filled  with  water.  One-sixth  of  the  length  of  this  tube  is 
coiled  and  placed  in  a  furnace ;  the  other  five-sixths  are  heated  by  the  circulation  of 
the  hot  water.  The  tubes  are  of  malleable  iron,  capable  of  resisting  a  pressure 
of  3000  lbs.  per  square  inch.  More  recently  the  hot  water  from  native  hot  springs, 
or  obtained  from  bored  artesian  wells,  has  been,  as  for  instance  at  Baden-Baden« 
employed  for  the  purpose  of  heating.  At  Baden-Baden  the  hot  water  (67'')  from  a 
native  spring  is  used  to  heat  a  church. 

HMting  witbBteBiB.  This  method  of  heating  is  based  upon  the  latent  heat  contained  in 
steam,  i  kilo,  of  steam  at  100^  contains  so  much  latent  heat  that  by  it  5*5  kilos,  of 
water  can  be  heated  from  o*"  to  100^. 

A  steam-heating  apparatus  consists  of  a  boiler,  steam-pipes,  and  pipes,  which  re- 
convey  the  condensed  water  to  the  boiler.  The  boiler  may  be  Constructed  in  the 
usual  manner.  The  steam  pipes  are  of  cast-iron  and  placed  vertically,  or  if  hori- 
zontaJly,  with  a  gentle  slope  towards  the  boiler.  If  several  stories  of  a-  building 
have  to  be  heated,  a  main  steam-pipe  is  carried  to  the  highest  story,  and  branch 
pipes  are  fitted  to  it.  The  pipes  are  here  and  there  fitted  with  air  valves  for  the  pur- 
pose of  permitting  the  expulsion  of  the  air  compressed  by  the  steam.  The  boilnr,  if 
low-pressure  steam  be  used,  should  also  be  provided  with  an  air  valve,  in  order  to 
prevent  the  collapse  of  the  boiler  by  the  outer  atmospheric  pressure  if  the  generation 
of  steam  ceases.  Heating  by  means  of  steam  is  advantageously  applicable  in  works 
where  steam  is  used  as  a  motive  power. 

oombiiMtioD  of  steam  and      Very  recently  it  has  been  proposed  to  combine  steam-  with  hoi- 
Hot-wfttar  HeaUng.       water-heatiiig,  and  to  heat  from  one  central  locality  a  series  of 
bmldings  and  houses,  in  the  same  manner  as  these  are  now  supplied  from  one  oentral 
reservoir  with  gas  or  water. 

Ofti-Hoatinff.  It  IS  wcU  kuowu  that  illuminating  gas  is  now  very  generally  used  for 
the  purpose  of  heating,  being  in  this  application  best  mixed  with  air,  as  is  the  case, 
for  instance,  in  the  Bunsen  burner. 

Gas  is  used  for  cooking  in  stoves  specially  constructed  for  the  purpose,  and  also  for 
heating  apartments  and  buildings.  As  a  rule  it  may  be  assumed  that  the  combus- 
tion of  5  cubic  feet  of  gas  is  sufficient  to  elevate  the  temperature  of  1000  cubic  feet 
of  air  12°,  and  one-fifth  of  this  quantity  of  gas  suffices  by  its  combustion  to  keep  the 
temperature  constant. 

HeatioR  without      There  is  no  doubt  that  an  inexhaustible  supply  bf  heat  exists  as  latent 
Ordinary  PaeL    heat,  which  can  be  set  free  by  friction,  or,  in  other  words,  by  the  conversioa 
of  mechanical  force  into  heat. 

Notwithstanding  many  medianioians  have  constnioted  apparatus  for  producing  heat  fay 
mechanical  force,  none  of  these  have  been  found  practically  available,  and  some  were  found 
to  be  extremely  wasteful.  The  heat  generated  by  the  fermentation  of  manure  lb  uaefully 
applied  to  heating  hothouses,  by  placing  under  the  manure  heap  thin  sheet-iron  pipes, 
imieh  convey  the  heat  into  the  hothouse. 

p.  Boiler  Heating  and  Consumption  of  Smoke. 

Boiler  H«atiiiff.  Stcam-boilers  are  as  a  rule  built  in  brick- work,  and  in  th^  con- 
struction, as  well  as  that  of  the  furnace  they  are  fitted  with,  economy  of  fuel  is  the 
great  object.    The  furnace  is  of  course  built  with  fire-bars  and  ash-pit.    The  grate 


WARMING.  74t 

or  fire-bars  consist  of  parallel  cast-iron  bars,  the  size  and  shape  of  which  depend 
upon  the  kind  of  fuel  to  be  used,  while  as  regards  the  space  between  the  bars  expe* 
rience  has  taught  that  the  sum  sh^d  not  amount  to  more  than  one-fourth  of  the 
total  surface  of  the  grate.  A  large  grate  has  the  advantage  of  more  freely  admitting 
air  to  the  fuel,  while  obstruction  by  clinker  and  slag  is  less  to  be  feared.  The 
operation  of  firing  with  a  large  grate  is  more  easily  conducted,  and  can  take  place  at 
longer  intefvals  of  time.  Of  course  the  grate  must  be  kept  entirely  covered  with 
fuel.  Small  grates  may  be  preferable  in  some  instances,  especially  where  a  vivid 
combustion  is  required.  Grates  for  wood  fuel  may  have  half  the  surface  required  for 
coal,  as  with  the  former  the  openings  between  the  bars  do  not  become  choked  with 
clinker  and  slag.  According  to  £.  Koohlin  a  grate  for  burning  in  one  hour  350  kilos, 
of  old  oak  wood  should  be  of  i  square  metre  surface  with  \  square  metre  for  space 
between  the  bars.  Usually,  however,  the  grates  for  wood  fuel  are  made  four  times 
smaller  than  those  for  coal. 

The  fire-place  or  furnace  should  of  course  be  constructed  of  sufficient  height, 
width,  and  depth  to  admit  of  the  proper  combustion  of  the  fuel.  The  fuel  should  be 
thrown  into  the  furnace  in  sufficiently  large  quantity  at  once  to  keep  up  the  steam 
adequately.  Too  frequent  filing  is  not  economical,  because  a  large  quantity  of  cold 
air  is  admitted,  which  cools  the  boiler  and  interferes  with  the  proper  combustion  of 
the  fuel.  The  dimensions  of  the  furnace  doors  must  bear  a  proper  proportion  to  the 
size  of  the  furnace,  and  these  doors  must  close  tightiy  so  as  to  prevent  draughts  of 
air  impinging  on  the  burning  fuel. 

^""AroSStS**^  While  we  cannot  here  enter  into  any  further  details  on  boiler- 
furnaces,  a  subject  really  belonging  to  engineering,  we  may  now  tufn  our  attention 
to  smoke-consuming  furnaces,  contrived  with  the  view  not  only  of  abating  the 
nuisance  arising  from  the  smoke  evolved  in  huge  volumes  from  large  factory  and 
other  chimneys,  but  also  for  the  saving  of  fuel,  it  having  been  ascertained  that  by 
the  ordinary  combustion  of  i  ton  of  coals  25  IbE^  of  soot  are  evolved,  having  a 
heating  power  of  four-fifths  of  the  coal.  The  loss  occasioned  by  the  carbon  thus 
carried  off  amounts  to  T^ith,  or  not  quite  i  per  cent. 

When  green  coals  are  put  in  quantity  on  a  bright  boiler  furnace,  there  is  suddenly 
evolved  an  immense  volume  of  combustible  gases  and  vapours  containing  a  large 
amount  of  carbon  (benzol,  toluol,  carbolic  acid,  anthracen,  naphthalin,  paraffin,  &c., 
the  oxygen  of  the  air  contained  in  and  supplied  to  the  furnace  being  usually  insuffi- 
cient to  cause  the  complete  combustion  of  these  substances,  so  that  only  the  hydrogen 
bums,  while  the  carbon  is  separated  as  smoke  and  soot,  the  evolution  being  promoted 
by  the  comparatively  cool  state  of  the  boiler-plates,  as  well  as  by  the  large  influi^  of 
cold  air  at  the  time  of  firing.  The  contrivances  for  preventing  and  consuming 
smoke  are  based  upon  different  principles ; .  for  instance : — a.  Air  is  sometimes 
conveyed  to  the  fire-bridge  by  means  of  a  separate  pipe  or  channel,  b.  Two 
adjoining  furnaces  are  connected  and  alternately  fired  in  such  a  manner  that  the 
smoke  of  the  furnace  last  fired  is  consumed  in  the  high  red  heat  of  the  other  furnace. 
c.  The  firesh  fuel  is  spread  over  only  the  front  of  the  fire  nearest  the  furnace-door,  so 
that  the  evolved  gases  may  be  consumed  by  the  red-hot  fire  on  the  bars.  d.  The 
feeding  is  effected  by  mechanical  means,  uninterruptedly,  in  such  a  manner  that  the 
fuel  on  the  bars  remains  in  a  high  state  of  incandescence,  e.  The  construction  of 
very  high  chimneys  has  been  resorted  to  for  the  purpose  of  supplying  a  rapid  current 
of  air;  but  this  expedient,  a  very  expensive  one,  does  not  answer  the  purpose,  aud 
leads  to  loss  of  heat. 


741  CBSmCAL  TECHNOLOOr. 

We  may  mentioa  briefly  tii«  following  smoke -prerentii^  and  coDflmning  mppa- 

I.  Mechanical  removal  of  the  smoke  by  washing  the  products  of  combastion.  In 
some  chemical  works  near  Newcastle -npon-TTile  the  smoiie  of  the  different  farnaeea 
ia  washed  by  a.  spray  of  water  previons  to  being  passed  into  the  chimney.  For  this 
purpose  the  smoke  of  the  different  furnaces  of  the  work  ia  conducted  into  sabt«r- 
raneaa  brick-W;ork  channels,  so  conatruoted  with  knee-bends  that  the  smoke  is  caused 
to  flow  upwards  and  downwards  alternately,  while  at  the  mouth  of  the  fumsce-flue  a 
continuous  spray  of  water  is  caused  to  impinge  upon  the  smoke,  whereby  all  solid 
particles  are  thrown  down  and  are  removed  &om  the  channels  as  soot.  There  is  in  this 
case  only  one  chimney,  in  which  the  draught  is  kept  np  by  means  eitlker  of  a  blast  of 
air  or  a  jet  of  injected  steam.  Jean,  at  Paris,  has  somewhat  modified  this  method  by 
cansing  the  smoke  and  waste  steam  of  a  bigh-presenre  engine  to  be  conveyed  into  a 
subterranean  channel  covered  with  a  layer  of  water  several  centimetres  in  depth, 
while  a  jet  of  cold  water  ia  made  to  play  upoa  the  sraoke  and  steam.    The  4 

Fio-  335- 


is  provided  with  a  kind  of  water-wheel,  which  does  not  quite  touch  the  anrface  o/  tht 
water,  bqt  is  fitted  with  brashes,  which,  toncliiug  the  water,  prqjeet  it  as  spray 
throngh  the  channel.    The  water  becomes  heated,  and  servesafler  filtration  as  feed 

z.  Application  of  improved  fire-bara,  to  be  diatingoisbed  as  {a)  immovable,  and 
((]  xQovable. 
sup  oimu.  Among  the  immovable  grates  are  the  step-  and  stage-giates.  The 
former  consists  of  a  series  of  step-lik^  stages  of  fire-bars,  to  which  the  poker  has 
access  from  the  ssh-pit.  By  the  heat  of  the  fire  on  the  lowet  steps  the  fuel  on  tha 
higher  step  is  converted  into  coke,  and  only  after  this  process  has  continned  for  some 
time  is  the  partly-coked  fuel  raked  down  to  a  lower  step,  while  fresh  green  ooal  is 
placed  on  the  higher.  The  air  enters  this  kind  of  grate  not  only  throngh  the  apace 
between  the  bars,  but  also  laterally  through  the  grated  space  between  the  steps. 
Caldng-coal,  or  coal  which  makes  mnch  slag,  does  not  answer  as  fiiel  in  this  grate, 
but  small  ooal,  refuse  peat,  sawdust.  &c.,  are  well  adapted.  Instead  of  iron  fire-bara 
MM.  Longridge  and  Mash  make  use  of  slabs  of  fire-clay,  provided  with  ehanneb 
and  perforations  so  as  to  constitute  a  grating. 


WARUISQ.  743 

KUK  or  son  onw.  Thii  ie  a  modificatioa  of  the  grate  joat  deaoribed,  and  was  invented 
b7  Longen  {1866).  The  green  fael  is  Dot  placed  above  the  burning  fael,  bnt  under 
it,  for  which  purpose  the  grate  is  constrncted  in  stages,  the  fire-bars  being  inclined 
to  tbe  horiznn  at  an  angle  of  about  28°.  There  is  between  each  ttagt,  or  stage,  of 
the  grate  a  space  of  about  12  centims.  The  fuel  becomes  coked,  and  the  volatile 
products  pass,  mixed  witli  air,  through  several  atages  of  incandescent  fuel,  thus 
insuring  complete  combuation. 

viinbii  ontH.  The  leading  idea  of  these  grates  is  to  effect  the  firing  hj  mecbsnical 
means.    jVroong  these  the  chain  grate  sod  rotating  grate  deserve  notice. 

QuiDdnu.  Notwithstanding  the  expensive  nature  of  this  invention,  it  has  been 
found  useful  in  practice  and  is  employed  in  man;  establishments.     It  consists 

Fio.  336. 


'^g-  335*  of  two  endless  flat  chains,  00,  which  run  on  two  octo-geared  rollers. 
Between  these  chains  the  fire-bars  are  placed  longitudinally,  so  that  the  grata 
consists  of  an  endless  eenes  of  bars.  The  distance  of  the  two  rollers  from  eacli 
other  determines  the  length  of  the  grate.  A  rotating  motion  is  imparted  at  o  in  snch 
a  manner  that  the  grate  moves  through  17  to  30  millimetres  per  minute.  The  fresh 
foel  is  thrown  in  at  b,  and  is  carried  continuoualy  towards  the  fire.  The  height  of 
the  layer  of  fuel  ie  regnlated  by  meana  of  the  slide-damper,  d.  which  can  be  moved 
by  means  of  the  lever,  p.  The  chains  and  rollers  are  supported  by  the  truck,  i, 
running  on  the  iron  rails,  h  h.  The  velocity  of  the  grate  is  so  regulated  that  the 
fael  is  entirely  consumed  when  arriving  at  tJie  end  of  the  fire-place.  There  are 
several  aerions  defects  in  tliia  apparatus.  It  is  complicated,  aoon  out  of  repair, 
requires  a  considerable  amonnt  of  force  to  muntoin  its  motion,  and  it  does  not 
altogether  prevent  amoke,  while,  finally,  it  is  found  wasteful  for  fael. 


744  CHEMICAL   TECHNOLOGY. 

BouttBgOnta.  This  oontriyanoe,  invented  by  Collier,  consists  of  a  rotating  diao 
which  supplies  the  coal  to  the  furnace  uniformly  through  a  slit  cut  below  the  funia4se 
doors.    This  apparatus  has  never  been  extensively  in  use. 

improTMi  Fuel  sappiy.  3.  Amoug  the  numcrous  suggestions  for  the  better  feeding  of  fur- 
naces are  the  following : — 

Collier's  feeder  (1823)  consists  essentially  of  two  horizontal  crushing  rollers 
provided  with  projections,  so  that  the  cgal  is  broken  up  into  uniform  lumps,  and 
then  thrown  into  the  fire  by  wheels  provided  with  scoops  revolving  200  times  a 
minute.  This  mechanism  requires  a  half  nominal  horse-power  to  maintain  its  motion. 
Stanley's  feeder,  Fig.  336,  consists  of  a  funnel,  a,  fitted  with  toothed  crusliing 
rollers.  The  crushed  coals  fall  on  the  distributor,  b,  which  rotating  with  great 
velocity  throws  the  coals  uniformly  on  to  the  fire.  Notwithstanding  the  defects  of 
this  invention,  the  chief  being  that  it  is  not  possible  for  the  stoker  to  fire  hard  if 
required,  this  apparatus  certainly  prevents  smoke,  but  is  also  liable  to  be  quickly 
out  ojf  repair. 

pnttFiTM.  Pult  fires  were  first  introduced  by  Wedgwood  for  porcelain  furnaces. 
The  characteristic  feature  is  the  mode  of  admitting  air,  which  instead  of  entering  as 
usual  from  below  is  forced  downwards.  The  grate  is  placed  in  a  sloping  position. 
The  fire-doors  remain  open,  while  the  ash-pit  is  quite  closed.  This  arrangement 
fulfils  certainly  all  the  conditions  of  complete  combustion,  but  in  practice  has  not 
answered  and  is  only  applicable  with  wood  fuel. 

vogri  ante.  The  fire-bars  in  this  grate  are  placed  at  an  angle  of  33**.  The  ooals  are 
supplied  by  means  of  a  funnel,  and  Uie  bars  can  be  shaken  up  and  down  by  mechanical 
means. 

Boquiiion'B  onte.  An  arrangement  of  rather  oomplicated  nature  intended  to  be  applied  to 
house  stoves,  and  so  constructed  that  the  green  fuel  is  brought  under  the  glovring  fueL 
The  grate  consists  of  a  horizontal  movable  cylinder,  upon  which  the  fuel  rests.  When 
fresh  fuel  is  added,  this  cylinder  is  turned  so  as  to  cause  the  fuel  to  be  placed  below  the  red- 

Appantna  of  Cntiar  hot  clnders.  In  practice  this  grate  has  not  answered,  being  too  compli- 
ed a«orge.  cated.  In  many  cases  it  has  been  attempted  to  feed  the  fires  in  an  aecendmg 
mode,  as,  for  instance,  in  Cutler's  grate,  improved  upon  by  Axnott  in  1854.  The  ooals 
are  burnt  from  an  iron  vessel  which  is  by  mechanical  means  lifted  over  the  fire,  the  supply 
of  coals  in  the  vessel  being  regulated  to  last  for  twenty-four  hours.  In  George's  apparatus 
the  fuel  is  supplied  to  the  grate  by  means  of  a  screw  propeller. 

Apponttu  with  unequa      4*  Among   the  apparatus  in  which  smoke  is  prevented  by  an 
Dfatribution.  unequal  distribution  of  fuel  on  the  grate,  that  of  Dumery,  deserves 

notice.  This  arrangement  is  dlBtinguished  from  those  of  Cutler  and  George  by  the  fraeh 
fuel  being  put  on  from  both  sides  of  the  grate  under  the  red-hot  cinders.  For  this 
purpose  the  grate  is  strongly  curved  upwards,  exhibiting  a  saddle  shape.  The  fad 
is  forced  on  to  the  grate  by  mechanical  means  in  such  a  manner  that  it  is  first  placed  on 
the  lowest  fire-bars,  and  gradually  forced  towards  the  centre.  This  principle  was  known 
to  Watt  in  1785,  and  was  applied  by  him  in  a  slanting  grate. 

Tenbrinck  also  places  the  grate  in  a  sloping  direction,  so  that  the  ooals  tumble  towards 
the  fire-bridge,  and  accumulating  there  as  incandescent  coke  cause  the  complete  eombaa- 
tion  of  the  fuel.  In  Corbin*s  grate  a  partition  of  fire-brick  is  employed.  Fairbaim  (1837) 
appears  to  have  been  the  first  to  contrive  smokeless  grates.  In  his  double  grate  the  fur- 
nace is  provided  with  two  hearths,  two  grates,  and  two  furnace  doors.  The  gratea 
are  separated  from  each  other  by  a  partition  of  fire-bricks.  The  stoking  is  so  regulated 
that  while  the  one  furnace  is  in  full  combustion,  the  other  is  supplied  with  fresh  fuel,  this 
operation  occurring  at  regular  intervals  and  alternately.  The  result  is  that  the  smoke 
and  gases  evolved  are  burnt  by  the  highly  incandescent  fuel  of  the  other  furnace.  De 
Buzonniere  contrives  to  force  the  smoke  of  one  furnace  under  the  incandescent  fad 
of  the  other.  With  a  properly  regulated  supply  of  air  and  regularity  of  stoking,  it  has 
been  proved,  by  a  series  of  experiments  made  on  the  large  scale  with  a  40  horae-powar 
marine  multi-tubular  boiler,  by  the  late  Dr.  Richardson,  of  Newcastle-on-Tyne,  and  by  Meeara. 
Longridge  and  Sir  William  Armstrong,  that  with  all  kinds  of  coal  and  with  every  variety 


WARMING.  745 

of  steam  boiler,  smokeless  and  complete  combustion  of  the  fael  may  be  obtained  without 
difficulty,  the  plan  being  attended  with  a  considerable  saving  of  fuel  and  production  of  its 
highest  calorific  effect. 

b^^^dofOo^Suw!  5*  Nearly  all  attempts  in  this  direction  have  proved  an  utter 
^  Aircitfrenu.  failure  in  practice.  Parkes^s  (1820)  split  bridge  was  constructed  with 
the  view  of  causing  the  air  to  flow  partly  as  usual  under  the  grate,  partly  to  act  at  the 
end  of  the  furnace  so  as  to  effect  a  complete  combustion.  Palazot*s  invention,  highly 
oommended  by  Bumat,  Tresoa,  and  others,  appears  to  be  somewhat  similar.  Chanter's 
arrangement  consists  essentially  of  two  grates  placed  parallel  to  each  other.  The  green 
fuel  is  put  upon  one  of  these,  and  having  been  coked  by  the  incandescence  of  the  fuel  on 
the  other  grate  is  raked  on  to  that,  thus  insuring  complete  combustion  increased  by 
lateral  jets  of  air. 

QaU's  Fbn-piMe.  Gall,  reversing  the  rule  that  the  dimensions  of  a  factory  chimney  should 
bear  a  proportionate  relation  to  the  quantity  of  fuel  to  be  burnt,  has  constructed 
chimneys,  the  highest  point  of  which  above  the  buildings  is  only  0*6  metre,  and  which, 
therefore,  simply  serve  to  carry  off  the  products  of  combustion.  As  the  difference  of 
temperature  is  the  cause  of  the  draught  of  a  furnace.  Gall  maintains  a  very  high  tem- 
perature in  the  combustion  room ;  and  in  order  to  cany  this  out  aU  the  causes  of  loss  of 
heat  ate  reduced  to  a  minimum  in  the  following  manner : — a.  While  in  the  ordinary  mode 
of  stoking  the  heat  of  the  combustion  room  is  necessarily  lowered  by  the  influx  of  cold 
air,  the  grating  in  GaU^s  arrangement  is  partitioned  in  such  a  manner  that  each  compart- 
ment is  gradually  supplied  with  fresh  fuel,  by  which  arrangement  the  formation  of  smoke 
is  prevented.  6.  The  furnace  is  constructed  so  that  the  stoker  cannot  possibly  put  on  too 
heavy  a  charge  of  green  coals,  while  he  is  compelled  to  spread  these  uniformly  over  the 
fire.  e.  The  loss  of  heat  by  radiation  from  the  brick- work,  fire-doors,  (6c.,  is  prevented 
by  causing  the  air  required  for  the  combustion  of  the  fuel  to  pass  these  hot  surfaces. 
d.  Gall  retards  the  velocity  of  the  gases  which  escape  to  the  chimney,  while  the  surface  of 
the  grate  and  the  section  of  the  chimney  are  enlarged.  Indeed,  the  entire  arrangement  is 
quite  different  from  that  in  ordinary  use,  as  the  fire-bars  are  placed  3  metres  below  the 
boiler,  while  the  grate  is  very  deep.  It  was  found,  however,  that  when  well  built  there 
was  a  sufficient  draught,  and  steam  could  be  kept  up.  Nothing  is  stated  as  regards 
the  nature  of  the  gases  issuing  from  the  chimney. 

Renun^.  As  regards  smoke  consuming  and  preventing  apparatus,  it  is  only  too 
evident  that  most  of  these  do  not  answer  the  purpose  so  completely  as  might 
be  expected.  Prcustical  experience  has,  however,  taught  that  if  the  conditions 
of  complete  combustion  are  well  attended  to  in  the  construction  of  the  furnace,  that 
with  proper  management  and  regular  mode  of  stoking,  adequate  supply  of  air, 
and  the  application  of  the  well-known  means  of  preventing  loss  of  heat  by  radiation, 
with  coal,  peat,  or  any  other  fuel,  the  combustion  may  be  so  conducted  as  to 
be  smokeless ;  and  at  the  same  time  the  fuel  thoroughly  utilised. 


s 


INDEX. 


ACETATE  of  alamina,  263 
lead,  64 

Aoetomotrji  468 

Adamantine  or  diamond-boron,  256 

Adulteration  of  white-lead,  72 

Aerostatical  lampe,  641 

Air  drains,  475 

—  gas,  674 
Alabaster  glass,  290 
Albumen  glne,  536 

Alkali  for  treating  gold,  106 
Alcohol,  424 

—  and  its  technically  important  pro- 

perties, 424 
— >  Tinegar  from,  461 
Alooholometry,  447 
Alizarine,  584 
Alkalimetry,  224 
Alloys   and  preparations  made  and 

obtained  from  metals,  4 

—  of  copper,  51 

gold,  109 

lead,  62 

nickel  and  copper,  41 

silver,  103 

-—  platinum,  96 
Aloe  hemp,  341 
Alpaca  wool,  495 

Alun  and  snlpbate  of  alnmina,  nses 
of,  263 

earths,  257 

roasting,  257 

—  flour,  258 

—  from  Banxite,  259 

>—  —  blast  furnace  slag,  260 
felspar,  260 

—  manufacture,  material  of,  256 

—  preparation,  257 

—  — >  from  alum-stone,  257 
clay,  268 

ainm-shale  and  alum  eaithp, 

257 
cryolite,  258 

—  production,  256 

—  properties  of,  260 

—  shale,  257 

—  works,  preparation  of  green  vitriol 

as  a  by-product  in,  82 
Alumina  acetate,  263 

—  sulphate  of,  261 
Aluminate  of  soda,  262 
Aluminates,  256 
Aluminum,  applications  of,  114 
— -  preparations,  113 

—  properties  of,  113 


Amalgamation,  extraction  of  silver  by, 
97 

—  process,  American,  98 
European,  97 

American  amalgamation  process,  98 

Ammonia-alum,  260 

Ammonia  and  ammoniacal  salts,  226 

—  as  a  by-product  of  beetroot  sugar 

manufacture,  236 

—  carbonate,  238 

—  from  bones,  235 

gas-water,  230 

lant,  234 

—  inorganic  sources  of,  228 

—  nitrate,  238 

—  preparation  of  liquid,  227 

—  sulphate,  238 
Ammoniacal  liquor,  666 

—  salts,  technically  important,  236 
Amorphous  phosphorus,  545 
Ananas  hemp,  341 

Aniline,  573 
^  black,  579 

—  blue,  578 

—  brown,  579 

—  colours,  575 
^  greeo,  678 
— -  orange,  579 

—  printing,  614 

—  red,  575 

—  violet,  577 

—  yellow,  579 
Annatto  or  amotto,  595 
Annealing,  20 
Annular  kilzu^  317 
Anthracen  pigments,  584 
Anthrachinon,  584 
Anthracite,  719 
Antichlor,  349 

Antimonial  preparations  in  technical 

use,  84 
Antimony,  82 
^-  black  sulphuret  of,  85 
^-  cinnabar,  85 

—  oxide,  14 

—  prop^es  of,  84 

— -  sulphuret  for  refining  gold,  106 
Apparatus  for  consuming  smoko,  74 1 
Apparatus  for  distilling,  432 

—  ^  heating,  731 
Areometer,  447 

—  to  test  milk,  558 
Arrow-root  staiob,  360 
Arsenic,  85 

^  acid,  86 


u 


IHDBX. 


Anenio,  zed,  or  realgar,  87 

—  Bnlpbtirete,  86 

—  yellow  Bnlphnret,  87 
Anenions  add,  85 
Artificial  iUamination,  617 
Asphalte,  484 

Assay,  dry,  108 

—  hydiostatical,  104 

—  of  silver,  103 
•—  wet,  104 

Augsburg  method  of  xnash-boiling,  410 
AuGU8TiK*s   method   of    silver    ex- 
traction, 99 
Aumm  musivum,  mosaic  gold,  75 
Aventnrin  glass,  291 
Azale,  687 
Azaleine,  575 
Azulise,  578,  581 
Aznrine,  578 

BALDAMUS    and   Gkune*s   gas, 
674 
Balling's  sacchazometrical  beer  test, 

420 
Bandanas,  616 
Bar  iron,  20 

properties  of,  26 

Bark  of  oak,  509 

—  or  red  tanning,  509 

Bauxite,  preparation  of  alum  from, 

259 
Beer  brewing,  403 

—  -—  materials,  403 

—  constituents  of,  418 

—  processes  of  brewing,  405 

—  testing,  420 

—  wort  fermentation,  405,  414 
Beet,  chemical  constituents  of,  368 

—  molasses,  382 

—  species  of,  367 

—  washing  and  cleansing,  371 
Beet-root  juice,  components  of,  373 
evaporating,  380 

—  —  filtration  through  animal  char- 

coal and  evaporation  of,  374 

—  separating  the  juice  from,  371 

—  soda  from,  171 

—  sugar,  367 

manufactory,  ammonia  as  a  by- 
product of,  236 

Bell-metal,  51 

Benzol,  570 

Berlin  blue,  36 

soluble,  37 

Berlin  or  Prussian  blue  on  wool,  004 

Bebthieb's  reduction  method,  700 

Bebzelius^b  indigo  test,  593 

Bessemer  steel,  27 

Bicarbonate  of  soda,  190 

Bismuth,  appb'cations  of,  77 

-—  oocuzrence  and  mode  of  obtainlog, 
76 

Bismuth,  properties  of,  77 


Bisolphate  of  sodai  214 
Bitumen,  paraffin  from,  685 
Black-jack,  mode  of  obtaining  tine 

from,  79 
Black  platinum,  95 

—  suphuret  of  antimony,  85 
Blast,  blowing  engine  and,  12 
Blast-f  uxnace,  chemical  prooess  going 

on  In  the  interior  o^  13 

—  description  of,  11 

—  gases,  15 

—  process,  10 

—  temperature  of  at  different  pointf, 

15 
Blasting  powder,  new  kinds,  154 
Bleaching,  597 

—  glass,  270 
Bleaching-powder  and  hypochlorites, 

214 

—  preparation,  214 

—  properties  of,  220 

—  theory  of  the  formation  of,  220 
Blistered  metal,  refining,  49 
Blowing  engine  and  blasts  12 
Blue  vats,  602 

—  vitriol^  54 

applications  of,  56 

Boghead  coal,  722 

Bohemian  crystal  glass,  268 

Boiler  heating,  740 

Boiler  plate,  rolling,  24 

Bois  roux,  loasted  wood,  712 

Bombay  hemp,  341 

Bone-ash  decomposition  by  sulphuric 

acid,  538 
Bone-black  preparation,  553 

—  properties,  554 

—  substitute  555 
Bones,  ammonia  from,  235 

—  glue  from,  532 
B0QUiLL0N*s  grate,  744 
Bouchebib*8  method  of  mineralising 

wood,  477 
Boradc  add,  formation,  250 
production,  250 

—  —  properties  and  uses,  251 
Borax,  252 

—  from  boradc  add,  252 

—  octahedral,  255 

—  purifying,  254 

—  uses  of,  255 

Boric  or  boradc  add  and  borax,  249 
Brandy  distilling,  relation  of  to  agri- 
culture, 448 
Bra^  or  camwood,  588 
Brass,  52 

—  tinning  of,  75 
Bread  balung,  451 

—  composition  of,  459 

-—  impurities  and  adulteration,  460 

—  making,  modes  of,  451 
^  oven,  454 

Bremen  blue,  56 


IVDIX. 


m 


Bren&on  fffeoii)  66 
Biewing  by  steam,  418 

—  beer,  403 

—  procMB,  by  pioducts  of,  423 
Biiok  mateziaU  311 

—  moulding,  312 
Bricks,  310 

—  and  Hme  kilns  for  bozning,  325 

—  field  bnming  of,  318 
-*  fixe,  319 

—  floating,  318 

—  from  dried  clay,  314 

—  the  bnming  of,  315 
Brine,  boHing  down,  168 

—  common  mlt  from,  168 

—  concentrating,  168 
Briquettes,  730 
Bromine  ixreparation,  193 
Bronze,  51 

Brown  coal,  691,  716 
Bronswick-green,  56 
Buckthorn  dyers,  596 
Burners  for  wood  gas,  670 
Burning  of  the  bricks,  315 
Butter,  558 
^-  chemical  nature  of,  659 

CADMIUM,  82 
Caking  coal,  719 
Calcining  or  roasting  the  ores,  48 
Calcium-soap,  249 
Calico  dyeing,  608 

—  printing,  612 
discharges,  611 

—  —  resists  or  reserres,  GIO 

—  —  thidEcnings,  610 
Calorifdres,  738 
Calorific  effect,  698 
Campeachy,  594 
Camwood  or  Brazil,  588 
Candle  making,  627 
Candles  from  Sitty  adds,  631 

—  light  from,  620 

—  moulding,  628,  633 

—  paraffin,  630 

—  sperm,  634 

—  stearine,  621 

—  taUow,  629 

—  wax,  631 
Cane-sugar,  364 
Caoutchouc^  484 

—  and  gutta-percha,  mixture  of,  488 

—  X^'^'^l^^^^on  and  consumption  of,  486 

—  solvents  of,  485 

—  vulcanised,  486 
Capsule,  or  sagger,  301 
'Carbolic  acid  dyes,  580 

;  Carbon,  211 
^'  .^  imparting   to   wrought-iron,    for 

steel-making,  28 
;     —  sulphide,  210 
/      Carbonate  of  ammonia,  238 
' potassa,  118, 121 


Carbonised  peat,  715 

Cardboard,  354 

Carinthian  oast-steel,  27 

Carmine-red,  589 

Carrara  and  Parian,  304 

Cartrid^  of  needle-guns,  mixture  for 

igmting,  157 
Cassava  starch,  360 
Casein  as  a  oementi  562 

glue,  636 

Cashmere,  500 

—  wool,  495 
Casselmann's  green,  57 
GAfisniB's  purple,  111 
Cast-iron,  16 

—  crude,  re-melting,  18 

—  enamelling,  20 

—  grey,  16 

—  white,  16 
Cast-fteel,  29 
Caustic  potassa,  133 

—  soda,  189 

Cement,    artificial,   manufacture    in 

Germany,  330 
Cements,  327 

—  artificial,  328 

—  lutes  and  putty,  491 
Cementation  process,  107 
Centrifugal  drier,  381 

—  machine,  391 

Ceramic  or  earthenware  manttbctare. 

293 

Cereals,  vinous  mash  from,  426 

Chair  grate,  743 

Chamber  acid,  206 

Charbon  roux,  terrified  charcoal,  711 

Charcoal,  animal,  553 

Berlin  blue  as  a  by-product  in 

manufactore  of,  37 

—  burning,  706 

—  combustibility  and  heatlnff  effect,. 

711 
-—  prcnpertiesof,  710 

—  revivification  of,  553 

—  sulphur  obtained  by  th«  reaction  of 

sulphurous  acid  on,  198 

—  terrified,  or  charbon  roux,  711 

—  wood,  704 
Chfttham  light,  680 
Cheese,  559 

Chemical  metallurgy,  4 
Chestnut  starch,  360 
Chili-saltpetre,  iodiire  from,  192 

—  preparation  of  nitrate  of  potusa 

from,  138 
Chimney  heating,  7t  33 
Chinese  galls,  511 
China  grass,  340 
Chlorate  of  potas  ja,  223 
Chloride  of  sulpl'iur,  211 

zinc,  81 

potassiu'A,  119 

Chlorine,  214 


4 


ly 


JKBXX. 


Chlarine,  apparatus  for  preparing,  216 
Chlorine,  condensing  apparatns,  217 

—  preparation   wiuiont  manganese, 

215 
— -  production  residues,  utilisation,  218 

—  residues,  other  methods  of  utilising, 

219 
Ohlorometry,  221 
Chlorometrical  degrees,  222 
Chromste  of  lead,  64,  66 

zinc,  81 

Ghromates  of  potassa,  applications  of, 

65 
Ohrome-alum,  67 
CShrome,  oxide  or  chrome  green,  67 

—  red,  66 

—  yellow,  66 
Cinchonine  pigments,  585 
Cinnabar,  91 

Claj,  kinds  of,  294 

—  pipes,  309 

—  preparation  of  alum  from,  258 
for  brick-making,  311 

—  ware  dense,  296 

kinds  of,  296 

porous,  297 

Clays  and  their  application,  293 

—  colour  of,  294 

—  plasticity  of,  294 

—  technically  important  qualities  of, 

293 
Clinkers,  Dutch,  318 
Cloth,  bough,  washing  and  milling,  499 

—  dressing,  499 

—  fabrics,  600 

—  teasling  and  shearing,  499 

—  white,  606 

—  weaving,  499 
Coal,  717 

>-  Boghead,  722 

—  brofm,  716 

—  caking,  719 

—  accessory  constituents  of,  718 
Coal-tar.  666 

—  colours.  569 
Coal-gas,  646 

—  Berlin  blue  as  a  by-product   in 

manufacture  of,  37 

—  composition  of,  668 

—  manufacture  of,  648 

—  manufacture,  by-products  of,  665 
Coals,  calorific  effect,  721 

—  classification  of,  718 

—  evaporative  effect  of,  721 
Cobalt  and  potassa,  nitzate  of  prot* 

oxide  of,  39 

—  bronze,  39 

—  colours,  37 

—  green,  39 

—  metallic,  37 

—  protoxide,  chemically  pure,  39 

—  speiss,  38 

—  ultramarine,  38 


CaBruleum,  39 

Cochenille,  or  cochineal,  589 

Cocoa-nut  fibre,  341 

Cocoon,  kiUing  of  the  pupa  in,  603 

Coke,  665,  723 

—  composition  and  value  as  fuel,  729 

—  properties  of,  729 
Coking  in  heaps,  724 

—  in  ovens,  724 
Collodion,  162 
Colorine,  588 
Coloured  fixes,  157 
Colours,  aniline,  675 

—  coal-tar,  669 

—  topical,  or  surface,  613 
Colza  oil,  637 
Common  pottery,  310 
Coolers  for  watet,  309 
Coj^r,  43 

—  alloys,  61 

—  amalgam,  54 

—  and  nickel  alloys,  41 

—  blistered  or  crude,  49 

—  from  oxidised  ores,  49 

—  hydrometollnrgical  method  of  pre- 

paring, 49 

—  ores,  treating  of  for  extraction,  44 

—  pigments,  66 

—  preparatioDS  of,  54 

—  properties  of,  60 

—  refining,  46 

_  smelting,  Enslish  mode,  47 
>—  solution  for  electro-plating,  116 

—  stannate  of  oxide  of,  58 

—  sulphate,  54 

—  tinning  of,  75 

Copper-plate  engravings,  repiodaction, 

115 
Copperas,  31 
Coralline,  581 

Cordwain,  Cordovan  leather,  521 
Cordials,  preparation  of,  482 
Cork  pommels  to  raise  the  grain  of 

leather,  619 
Cotton,  342 

—  combing  or  carding,  342 

»  detection  in  linen  fabrics,  343 

—  fabrics,  343 

—  species,  342' 

—  spinning,  342 

—  substitutes,  343 
Crucibles,  321 

—  distillation  of  zinc  in,  79 

Crude  iron,  statistics  concerning  the 

production  of,  18 
Crjolite,  decomposition  of  by  ignititt 

with  carbonate  of  lime,  259 
with  oaufltio  lime   hy  the 

wet  way,  259 

—  glass,  291 

»  preparation  of  alum  from,  258 

—  soda  from,  188 
Crystal-glass,  285 


IKDSX. 


Capola,  or  shaft  farnace, 

Catch,  512 

Ojanide  of  potassiaini  35 


18 


DAMASCENB,  30 
Decoction  method  of  preparing 
the  wort,  409 
Decomposition  famace,  new,  173 
Def  oseHng,  445  • 

De-liming|  or  saturating  the  juice  with 
carbonic  acid,  373 

—  the  jnice,  other  methods,  374 
Devillb  and  Dbbbat's  method  of 

extracting  platinum,  95 
Dextrine,  361 

Diamond  boron,  or  adamantine,  256 
Dinas  bricks,  321 
Discharge  style,  614 
Discharges,  calico  printlnfTi  611 
Distillation  of  the  mash,  431 
Distillery  apparatus,  432 

—  —  continuous,  440 
Divldivi,  511 
DOBN*s  apparatus,  433 
Drain  tiles,  318 
DuMONT's  filter,  375 
DUNiiOP'B  process,  218 
Dutch  clinkers,  318 

—  tUes,  318 
Dye-materials,  blue,  591 

—  red,  586 

Dyeing  and  printing  in  general,  568 

—  blue,  and  with   logwood    and    a 

copper  salt,  604 

—  calico,  608 

—  linen,  609 

—  spun  yarn  and  woren  textile  fab- 

rics, 599 

—  silk,  606 

—  wool  blue,  601 
red,  605 

—  woollen  fabrics,  601 

—  yelbw,  604 
Dyes,  568 

~  black,  605 

—  brown,  green,  and  black,  596 

—  carbolic  acid,  580 

—  green,  605 

—  red«  less  important,  591 

—  yellow,  595 
Dynamite,  Nobbl*S,  160 

EFFBBVESCINa  wines,  399 
Elayl  platino-ohloride,  96 
Blectric  light,  680 
Electro-metallurgy,  114 
Electro-plating  with  gold  and  silyer, 

115 
Electro-stereotyping,  117 
Electrolytic  law,  114 
Bleotro^ing,  115 
Bmerala  greeui  58 


Enamel,  bone  glass,  290 
Enamelling  of  cast-iron,  20 
Engraving  steel,  31 
Etage  or  stage  grate,  742 
Etching  by  galvanism,  117 
Etruscan  rases,  309 
European  amalgamation  process,  97 
Explosive  compounds,  technology  of, 
148 

FAGGOT  gradation,  168 
Fatty  acids,  candles  from,  631 

—  —  manufacture,  627 
Fayence  ware,  307 
flowing  colours,  309 

—  omamenthig,  308 
Felspar,  293 

—  mode  of  obtaining  potassa  from, 

122 
Fermentation,  386 

—  after,  in  the  casks,  416 

^-  alcoholic  or  vinous,  conditions  of, 
389 

—  of  the  grape  juice,  393 

potato  masb.  429 

beer  wort,  414 

mash,  427 

—  sedimentary,  416 

—  surface,  417 
Ferments,  substitutes  for,  45() 
Fibre  vegetable,  technology  of,  338 
Filter  for  beet-root  juice,  375 
Fire-bricks,  319 

Fire-clay  stoves,  734 

Fire-gilding,  110 

Fireplace  gulls,  745 

Fire,  requisites  for  producing,  546 

Firework  mixtures,  commonly  used,  156 

Fireworks,  chemistry  of,  148 

—  chlorate  of  potassa  mixture,  156 

—  friction  mixtures,  156 

—  grey-coloured  mixtures  for,  156 
Flame,  618 

Flannel,  600 
FUx,  338 

—  combing,  340 

—  beating  or  batting,  339 

—  hot-water  cleansing,  339 
^-  spinning,  340 

Flaxes  from  New  Zealand,  341 
Fleck's  jnocess  of  preparing  phospho- 
rus, 543 
Floating  bricks,  318 
Flowers  of  sulphur,  197 
Flue  heating,  739 
Franklinite,  9 
Frieze,  500 
Fritte  porcelain,  French,  304 

English,  304 

FucH8*s  beer  test,  422 
Fuchsin,  575 
Fuel  ariifldal,  729 

—  and  heating  apparatus,  698 


71 


htdbx. 


Tnel,  brown  ooal  as,  717 

—  oombostibillly  of,  698 

—  detenninationof  oombnfltiTepower, 

699 

—  elementary  analysifi,  700 
•—  inflammability  of,  698 

—  gaseoiUi  730 

—  petroleam  as,  722 

—  pyrometrical  calorific  effect,  701 
— -  specific  calorific  effect^  701 

—  supply  improved,  744 
•—  Stbomsybb'8  test,  701 

—  value  of  coke  as,  729 
Falling  soaps,  245 
Fulminating  mercury,  92 
Furnace,  capola  or  shaft,  18 

—  reverberatoiy,  18 

—  working  copper  ores  in,  44 
Fustic,  yoUow  dye,  595 
Fusel  oils,  removing,  445 

GALAOTOSOOPE  to  test  milk,  558 
Gkdl-nnt,  611 
Gall^b  apparatus,  435 

—  fireplace,  745 
(Galvanism,  application  of,  114 

—  etching  by,  117 
Galvanography,  117 
Ghdena,  59 
Qarancine  587 
Garancenx,  587 

Gas,  Baldamus  and  Grxtvb's,  674 

—  burners,  665 

—  carbuietted,  674 

—  charging  the  retorts  and  distilla- 

tion, 650 

—  cooling  or  condensing  apparatus,  652 

—  distribution  of,  660 

—  exhauster,  654 

—  general  introduction  and  historical 

notes,  645 

—  heating,  740 

—  GUiLABD'B  platinum,  672 

—  for  heating  purposes,  731 

—  .—  illuminating  testhig,  661 

—  from  peat,  670 

—  —  petroleum,  676 

—  —  petroleum  oil,  or  oil  from  bitu- 

minous shfdes,  675 
suint,  675 

—  —  wood,  668 
— >  holders,  656 

—  hydraulic  valve,  661 
-*  IS0ABD*8,  674 

—  lighting,  raw  materials  of,  646 

—  lime,  667 

—  manufacture,  sulphur  as  a  by-pro- 

duct, 198 

—  meters,  664 

—  oil,  resin,  674 

—  preisure  regulator,  661 

—  products  of  the  distillation,  647 

—  purif^ng,  654 


Gas,  retorts,  648 

—  Uie  scrubber,  653 
Gas- water,  671 

ammonia  from,  230 

Gaseous  fuel,  730 
Gases,  blast-furnace,  15 

—  heating  with,  24 
Gatty*b  process,  219 
Gat-Lub8AC'§  chlorometric   method, 

221 

Gentble's  method  of  preparing  phos- 
phorus, 544 

Gbbland's  method  of  preparing  phos- 
phorus, 544 

German  iron  refining  process,  21 

—  silver,  53 

Germination  of  the  softened  grain,  406 
Gilding,  110 

—  by  the  cold  process,  110 
wet  way,  110 

—  porcelain,  bright,  303 
6lLLABD*B  gas,  672. 

Glass,  aluminium-calcium  alkali,  269 

—  aventurin,  291 

—  bleaching.  270 
~  bottle,  282 

—  classification  of  the  various  kinds, 

268 

—  dear  melting,  275 
•—  cold  stoking,  275 

—  coloured,  and  glass  staining,  289 

—  crown,  277 

—  crjoUte^  291 

—  crystal,  285 

—  defects  in,  276 

—  definition  and  general  properties 

of,  268 

—  filigree  or  reticulated,  292 

—  ice,  291 

—  making,  raw  materials,  269 

—  material  melting,  275 

—  melting  and  clearing,  280 

—  optica],  286 

—  oven,  271 

—  painting,  289 
~  pearls,  292 

—  plate,  279 

casting  and  cooling,  281 

or  window,  276 

polishing,  281 

—  platinising,  282 

—  potassium-caloium,  268 

—  potasBium-lead,  269 

—  preparation  of  the  material  «nd 

melting,  274 

—  pressed  and  cut^  283 

—  refuse,  utilisation,  270 

—  relief,  291 

—  sheet  or  cylinder,  278 

—  silverings  281 

by  precipitation,  281 

—  sodium-calcium,  268 

—  technology  o^  268 


IlfTDEX. 


VU 


GlatB,  the  meltmg  Tenel,  270 

—  toolfl  for,  277 

—  Tarions  kinds,  276 

—  water,  283 
GliAUBBB'B  salt,  213 
Olne  boiling,  528 

—  drying,  631 

—  fram  bones,  532 
leather,  529 

—  liquid,  633 

—  snbstitntes  for,  536 

—  test  for  qualitj  of,  533 
^-  treatiiig  with  lime,  629 
Glnten  glae,  636 
Glyoerine,  634 
Gljphography,  117 

Gold  alloys,  109 

—  applications  of,  110 

—  chemically  pure,  108 

—  colour  of,  109 

—  and   sUTer,  electro-plating  with, 

115 

—  extraction  from  other  metallic  ores, 

106 
poor  materials,  106 

—  leaf  for  gilding,  110 

—  mode  of  extracting,  105 

—  mode  of  extracting  by  means  of 

mercury,  106 

—  mosaic,  75 

—  eccurrenoe  and  mode  of  extracting, 

105 

—  properties  of,  108 

—  refining,  106 
~  salts,  111 

—  size,  489 

—  smelting  for,  106 

—  solution  for  electro-plating,  116 

—  testing  the  fineness  of,  109 

—  treating  with  alkaU,  106 
Grain  germinated  drying,  407 
Gtepe-jnice  fermentatioD,  393 
Grape-sugar,  383 

—  preparation,  384 
~  uses  of,  386 
Grapes,  pressing,  391 
Grate^  Boqxjillon's,  744 

—  chain,  743 

—  ^tage  or  stage,  743 

—  rotating,  744 

—  step,  742 

—  VoOL'B,  744 
Grates,  movable,  743 
Green  vitrio],  31 

—  ^-  preparation  of,  as  a  by-product 

in  alum  works,  32 
Gkenate  brown,  681 
Gbunbbbbo's  method  of  estimating 

the  yalue  of  potash,  226 
Ghm-cotton,  160 

—  as  a  subrtitate  for  gunpowder,  162 

—  other  uses,  162 
•^  properties  df  161 


Gun-metal,  61 
Gunpowder,  148, 156 

—  caking  or  pressing,  150 

—  composition,  152 

—  drying,  161 

—  granulated,  polishing,  160 

—  grani^dation  o4  the  cake,  and  sort- 

ing the  powder,  150 

—  manufacture,  148 

mechanical  operations.  149 

—  mixing  the  ingredients,  149 

—  products  of  combustion  of,  153 

—  properties  of,  161 

—  polrerising  the  ingredients,  149 

—  sifting  the  dust  from,  151 

—  testing  strength  o^  154 

—  white,  154 

Gutta-percha  and  caoutchouc,  mixture 
of,  488 

—  solvents,  487 

—  uses  of,  487 
Gutter  tiles,  318 
Gypsum,  333 

—  casts,  336 

—  grinding,  335 

—  hardening  of,  336 

—  kilns  or  burning  ovens  for,  334 
--  nature  of,  333 

—  uses  of  385 

HABANA  brown,  680 
Hsmatinon  astralite,  291 
Hssmatite  iron  ore,  8 
Heat,  mechanical  equivalent  of,  702 
Heating  apparatus,  731 
~  by  fines,  739 

hot  air,  737 

water,  739 

—  direct,732 

—  dwelling-honses,  732 

—  with  gases,  24 
steam,  740 

—  without  ordinary  fuel,  740 
Heaton  steel,  28 

Hemp,  340 

»  substitutes,  340 

Hides,  cleansing,  514 

—  swelling,  515 

—  stripping  off  the  hair,  516 

—  HoFMANN's  process,  219 
Hollander  mill,  347 

Hops,  404 

—  adding,  412 

—  quality  of,  404 

—  substitutes  for,  406 
Hot-pressing,  finishing,  and  dressing 

616 
Houses,  heating,  732 
Hungarian  tawing  process,  624 
Hyalography,  292 
Hydraulic  main  for  gas,  660 

—  mortar,  327 

—  valve,  661 


vui 


I5DEX. 


Hydrocarbon  proceBs  (Whitb*b)  for 

water-gas,  673 
Hydrochloric  addi  211 

—  —  properties  of,  213 

uses  of,  213 

Hypochlorites  alkaline,  223 
Hyposulphite  of  soda,  201 
Hyposalphnrous  acid,  199 

ICE-GLASS,  291 
lUamination,  artificial  in  general, 
«17 

—  Tkbsib  du  Motat*8  method,  679 

—  with  lamp?,  636 
India-mbber,preparation  and  use  of  ,486 
Indigo,  591 

—  properties,  592 

—  recovery  from  rags,  604 

—  testing,  592 
Indiffo-blae,  594,  602 
Ink  for  marking,  105 

—  —  printing,  489 

Iodine  from  carbonised  sea- weed  192 
Chili-saltpetre,  192 

—  preparation,  191 

—  properties  and  uees  of,  103 
Iron,  8 

—  catty  16 

•—  cement,  493 

—  cmde  16 

—  extraction,  9 

—  —  process,  tbeory  of,  10 

—  foundry  work,  18 

—  malleable,  tinning  of,  75 

—  metallic,  frreen  Titriol  from,  32 

—  minium,  32 

—  ore  hematite,  8 

mal^etic,  8 

marsh,  9 

pea,  9 

spathose,  8 

—  refining  by  mechanical  meanp,  24 
Geman,  21 

Swedish,  22 

—  sheet,  tinned,  75 

—  stones,  734 

—  wire  manufacture,  25 
Isinglass,  535 
ISOARD'8  gas,  674 

JUTE,  341 


TTAOLIN,  293 


Eabmabsch*s     evaporation 
method,  699 
Kelp,  130 

—  preparation  of  iodine  from,  191 
Kilns,  annular,  317 

—  for  burning  lime  and  bricks,  325 

—  —  gypsum,  334 

—  —  lime,  continuous,  324 

occasional  or  periodic,  323 

Kino,  512 


Knapp*8  leather,  525 
Kneading  machines,  453 

LAO  dye,590 
Lacquered  leather,  521 
Lactose,  sugar  of  milk,  557 
Lake  pigments,  568 
Laming  mixture,  667 
Lamp  with  constant  oil  level,  640 
Lamps,  636 
•—  for  illumination,  636 

—  petroleum  oil  and  paraffin  oil,  644 

—  pressure,  641 

—  statical,    mechanical,    clockwork, 

moderator,  642 

—  suction,  639 

—  various  kinds,  639 

Laht*b  refining  apparatus  for  sulphur, 

196 
Lai^gieb'b  apparatus,  443 
Lant,  ammonia  from,  234 
Lead  acetate,  64 

—  alloys,  62 

—  basic  chloride  of  as  a  substitute 

for  white-lead,  71 

—  chloride,  white-lead  from,  71 

—  chromate,  64,  66 

—  containing   silver,  mode  of   pre- 

paring, 100 

—  metallic,  applications  of,  G2 

—  obtained  by  calcination,  60 

—  —  —  precipitation,  59 

—  occurrence  of,  69 

—  oxide,  63 

combinations  of,  64 

—  preparations  of,  63 

—  properties  of,  62 

—  sulphate,  white-lead  from,  70 

—  peroxide,  64 

Leaden  pans,  concentration  in,  207 
Leather,  cord  wain.  Cordovan,  521 
^-  dressing  or  currjing,  518 

—  finishing,  519 

—  for  gloves,  524 

—  glue,  529 

—  graining,  519 

—  $!Teasing,  519 

—  Khapp  8  process,  525 

—  lacquered,  521 

—  morocco,  520,  521 

—  polishing  with  pumice-stone,  519 

—  preparation  of  white,  522 

—  Russia,  520 

—  sole,  518 

—  the  paring,  518 

—  the  scraping  or  smoothing,  519 

—  upper,  518 

LsBLAKC*B  process,  theory  of,  183 
Lepbincb's  water-gas,  674 
Ley,  242 

—  evaporation  of,  180, 257 

Light,  materials   and  apparatus  for 
producing  aitificialj  617 


IKDEX. 


IX 


Lime  and  brickBykilnaforbiiniiDg,  825 
Ume-bnniing,  322 

—  cementa,  491 

—  light,  678 

—  preparation  of  fatty  acids  by  meaxii 

of,  621 

—  properties  of,  322,  225 

—  slakiog,  326 

—  sulphite  of,  201 

—  treating  glne  with,  529 

—  uses  of,  326 
linen-dydng,  609 

—  fabrios,  detection  of  cotton  in,  343 

—  goods  printing,  616 
Litharge,  63 

—  re^iTiflcation  of,  01 
Lithophanie,  303 
Litmus,  594 
Liquation  process,  47 
Liquid  glue,  533 
LizlTiation,  257 
Loam,  296 
Logwood,  594 

—  and  a  copper  salt  to  dye  blue,  604 
London  board,  354 

Lucifer  matches  manufacture,  548 
LiTNOB*s  apparatus,  232 
Lustres,  309 
Lye,  raw,  breaking  up  of,  136 

—  —  boiling  down,  136 

—  —  treatment  of,  136 

MACHINE  for  paper-ontting,  353 
—  paper,  352 
Machines  for  moulding  bricks,  312 
Madder,  586 

—  flowers  of,  587 

—  lake,  587 
Magdala  red,  583 
Magenta,  575 
Magnesium,  114 

—  light,  679 
Magnetic  iron  ore,  8 
Malachite,  43 

Malleable,  bar,  or  wiouKht  iron,  20 

Mallbt*s  apparatus,  230 

Malt,  the  bruisiog  of,  408 

Malting,  405 

Mandiuin  printing,  616 

Manilla  hemp,  341 

Manganese  and  its  preparations,  HI 

—  soap,  249 

—  testing  the  quality  of,  HI 
Marking  ink,  105 

Marl,  295 
Marsh  iron  ore,  9 
Martin  steel,  28 
Martins  yellow,  582 
Mash  boiling  thick,  409 

—  distillation  of,  431 

—  from  potatoeff,  427 
roots,  429 

—  with  sulphuric  acid,  428 


Mashing,  408 

Massicot,  63 

Matches  anti-phosphor,  552 

—  lucif er,  manufacture  of,  548 

—  wax  or  vesta,  553 
Mauve,  575 

Meat,  constituents  of,  562 

—  the  cooking  of,  563 
— >  generalities,  662 

—  preservation  of,  564 

—  salting,  565 

—  smoking  or  curinfr,  566 

—  the  boiling  of,  664 
Meerschaum  pipes,  artificial,  337 
Mercurial  compounds,  91 
Mercuric  chloride,  91 
Mercury,  applications  of,  91 

—  extracting  by  Spanish  method,  89 

—  extraction  of  gold  by  means  of,  106 

—  fulminating,  92 

—  method  of  decomposing  by  the  aid 

of  other  substances,  90 

—  method  of  extracting,  pursued  in 

Idria,87 
-^  occurrence  and  mode  of  obtaining, 
87 

—  or  quicksilver,  87 

—  preparations  of,  91 

—  properties  of,  91 

Metal,  ooazse,  roasting  or  calcining, 

49 
Metals,  alloys  and  preparations  from,  4 

—  sted  and  other,  30 

Metallic  iron,  green  vitriol  from,  32 
Metalloohromy,  117 
Metallurgy,  chemical,  4 

—  meaning  of  the  term,  4 
Meters  for  gas,  664 
Milk,  556 

—  means  to  prevent  becoming  sour, 

557 

—  sugar  of — lactose,  557 

—  testing,  557 
MilUfiore  work,  292 

MiNABY*s  process  of  preparing  phos- 
phorus, 544 
Mineral  green  and  blue,  57 

—  oil,  preparation  of,  694 

—  potash,  121 
Mineralising  wood,  476 
Minium,  red-lead,  63 
Mohair,  495 
MOHB'8  method,  225 
Moire-metallique,  75 
Molasses,  366 

—  beet,  382, 

—  potash  from,  122 
Mordants,  601,  609 
Morocco  leather,  520,  521 
Mortar,  326 

—  hardening,  327 

—  hydraulic  hardening  of,  331 
Mosaic  gold,  75 


iin>Ex« 


MonldB^  making,  19 
MnffleB,  difltUlatlon  of  zinc  in,'  78 
Hnriatio  add,  211 
Moflti  chemical  oonatitaents  of,  391 
Hyooderma  aoeti|  vinegar  with  the 
help  of,  466 

NAPHTHALINE  bine  andnaptha- 
line  Tiolet,  583 
•^  pigments,  581 
Neapolitan  jellow,  86 
Nef t-gil/  paraffin  from,  684 
Nettle  cloth  and  mnslin,  341 
Nickel  and  copper  alloja,  41 

—  and  its  ores,  39 

—  metallic  preparation,  41 

—  properties  of,  43 

—  Bilyer,  53 

Nitrate  of  ammonia,  238 

potaasa,  134 

—  preparation     from     Ohili« 

saltpetre,  138 

silver,  105 

soda,  soda  from,  189 

tin,  76 

Nitric  acid,  142 
bleaching,  143 

—  —  condensation,  144 
density  of,  146 

—  —  faming,  147 

in  saltpetre,  qnantitatire  esti- 
mation of,  140 

—  — -  mannfactoie,    other   methods, 

145 

—  —  nses  of,  147 
Nitro-benzol,  572 

—  pigment  directly  from,  581 
Nitro-glyoerine,  158 
Nobel*s  dynamite,  160 
Nat-galls,  511 

OAK  bark,  509 
Oil,  blue,  57 

—  cements,  491 

—  colza,  mineral,  637 

—  gas,  resin  gas,  674 

—  Tarnishes,  488 

Oils  Grade,  rectification  of,  689 

—  essential  and  resins,  480 

—  —  extraction  by  fatty  oils^  481 

—  —  preparation  of,  481 

—  paraffin,  683 

—  purifying  or  refining,  636 

—  treatment  of  the  products  of  dis- 

tillation of,  689 
Oleic  add  soap,  245 
OUye-oil  soap,  243 
Optical  glass,  286 
Ores,4 

—  calcining,  or  roasting,  48 

—  dressing  of,  5 

— >  ozidiaed,  copper  from^  49 

—  preparalion  of,  6 


Ores,  smelting,  48 

—  smdting  of,  5 
Orchil  and  Persio,  690 
Orpiment,87 
Orais,  coking  in,  724 

—  for  bominff  gypsam,  334 

—  for  porceUSn,  301 

—  or  kilns,  carbonisation  of  wood  in 

706,  708 
Oxide  of  antimony,  84 
Oxidised  silver,  106 
Oxysolphuret  of  antimony,  85 
Ozokerite  and  neft-gil,  pazaffin  froUi 

684 

T>^ONINE  or  coralline,  581 

Pans  for  evaporating  beet-root  jnioe 

876 
Paper-catting  madiine,  353 

—  different  kinds,  351 

—  drying,  351 

—  histoiy  of,  345 

—  madiine-made^  352 

—  making,  345 

—  mana£ctare  by  hand,  346 

—  materials  of  mannfactore,  346 

—  pressing,  351 

—  palp-bloin^,  350 

—  sheets  straining,  350 

—  sizing,  351 

—  sizing  the  palp,  350 
Papier-mach^  356 
Paraffin  candles.  630 

—  crude,  refining  of,  690 

—  from  bitumen,  685 

—  from  ozokerite  and  neft-gil,  684 

—  HuBNSB's  method  of  preparing, 

690 

—  numufaoture,  683 

—  oils,  683,  693 

—  oil  lamps,  644 

—  preparation  by  dry  distillation,  68 

—  from  petroleum,  684 

—  prop^ties  of,  692 

—  yield  of,  691 
Paichment,  527 

—  paper,  355 

Parian  and  Oarrara,  304 

Paste,  493 

Pasteboard  making,  353 

Pattik8on*s  method  of  refiniog  dlver^ 

101 
Pea-iron  ore,  9 
Pearls,  blown,  292 

—  solid,  292 

—  glass,  292 
Peat,  712 

—  carbonised,  715 
--  drying,  713 

—  gas,  670 

—  heating  effect  of,  715 

—  new  method  of  utilising,  715 


XI 


Peoqner  eraporaiixig  pan,  376 
Pbhkt's  indigo  tesV^dS 
Fbhot*8  test»  221 
Pens,  729 
Fereasaioii  oaps,  93 

—  powden,  166 
Perfumes  chemical,  482 
Perfnmeiy,  481 
Pennanganate  of  potassa,  112 
Petroleam  as  fuel,  722 

—  constltation,  696 

—  crude,  lefining,  696 

—  oil  and  its  occnrrenoe,  695 
gas  from,  675 

—  •—  Utmps,  644 

—  origin  and  formation  of,  695 

—  technology,  697 
Pettbnkofbb'b  process  for  restoring 

pictures,  490 
Phenicienne,  phenyl  brown,  681 
Phenyl  bine,  681 
Phosphorus,  distillation  of,  538 

—  Flbck*s  process,  543 

—  making,  burning  the  bones  to  ssh, 

538 

—  manufacture^  537 

—  other  proposed  methods  of   pre- 

paring, 543 

—  prepaiiDg  by  Gentbla,  Gbbland, 

MiNABT,  and  Sondbt'b  methods, 
544 

—  properties  of,  544 
and  preparation,  537 

—  red  or  amorphous,  645 

—  refined,  moulding,  541 

—  refining  and  puri^jring,  540 
Physic,  or  nitrate  of  tin,  76 
Picric  acid,  680 

Pictures,  Pbttbnkofbb's  process  for 

restoring,  490 
Pig  or  crude  iron,  9 
Pikaba  hemp,  341 
Pigments  from  cinchonine,  685 

—  lake,  668 

—  naphthaline,  681 

—  rod,  686 
Pipes  of  clay,  809 
Pi8TOBiT7B*8  apparatus,  435 
Pit  coal,  717 

Plaster  of  Paris  forms,  moulding  Id, 

299 
Platinum  alloys,  96 

—  black,  96 

Tinegar,  with  the  help  of,  467 

—  gas,  672 

—  hammered  or  cast,  95 

—  method  of  Deville  and  Dbbbay, 

95 

—  occurrence  of,  93 

—  ores,  93 

— >  properties  of,  95 
--  retorts,  207 

—  spongy,  95 


Platinum,  Wollabton's  method  of 

extracting,  94 
Porcelain  articles,  preparation  with> 

out  moulds,  299 

—  bright  gUding,  303 

—  castiDg,  299 

—  day,  293 

—  drying,  299 

the  mass,  297 

~  faulty  ware,  302 

—  French  fritte,  304 

—  glaze  applying,  300 

—  glazing,  299 

-—  kneading  the  dried  mass,  298 

—  grinding  and  mixing  the  material, 

297 

—  hard,  297 

—  ornamenting,  303 

—  oven,  301 

—  painting,  302 

—  OTen,  emptying  and  sorting  the 

ware,  302 

—  silvering  and  platinising,  303 

—  tender,  304 

—  moulding,  298 

~  the  potter's  wheel,  298 
Portland  cement,  329 
Potash  from  molasses,  122 

—  from  the  ashes  of  plants,  122 

—  Qbu^bbbbo^s  method  of  estimating 

the  value  of,  226 

—  purified  preparation  of,  133 
Potassa  and  cobalt,  nitrate  of  prot- 
oxide of,  39 

—  carbonate  of,  118 
-*  chlorate  of,  223 

—  chromates,  applications  of,  65 

—  mode  of  obtaining  from  felspar,  122 

—  neutral  or  yellow  chromate  of,  64 

—  nitrate  of,  134 

—  permanganate  of,  112 

—  salts  from  sea-water,  122 

sea-weeds,  129 

Btiint,  132 

.^ the  StasBfnrt  salt  minerals, 

118 

—  sources  whence  derived,  118 

—  sulphate  of,  121 

—  yellow  prussiate  of,  32 
Potassium,  chloride  of,  preparation,  119 
-—  cyanide,  85 

Potatoes,  mash  from,  427 

—  starch  from,  367 
Potato-mash  fermentation,  429 

—  starch  drying,  358 
Potter's  day,  295 
Pottery  common,  310 

Printing  and  dyeing  in  general,  568 

—  ink,  489 

-^  linen  goods,  616 

—  silk  goods,  616 

—  woollen  goods,  616 

—  of  woven  fabric*,  609 


TKDBI. 


PrnsBian  blae  on  wool,  604 
Paddling  furnace,  22 

—  prooess,  22 

Polp^  bleachingi  for  paper,  340 
Pnlt  fires,  744 

Pumice-stone  to  polish  leather,  519 
Purple,  CAfisius's,  111 
PjriteB  distillation,  green  yitriol  from 
residues  dP,  32 

—  preparation  of  sulphur  from,  197 

—  use  of  for  the  preparation  of  sul- 

phurous add,  206 
Pyrotechny,  148 

—  chemical  principles  of,  155 

QUAKTATION,  107 
Querdtion  bark,  596 
Quiduilver  or  mercury,  87 

RAGS,  cutting  and  deaning,  347 
-—  for  paper,addition8  of  mineral 
to,  346 
^  substitute  for,  346 
Baw  lead,  61 
Bealgar,  87 
Bed  arsenic,  87 
Bed  lead,  63 

—  phosphorus,  545 

—  prussiate  of  potash,  35 
Befined  steel,  29 
Befining  copper,  46 
Beeins,  483 

Beein  cements,  492 

—  gas,  678 

oil  gas,  674 

Besin-tallow  soap?,  245 

Besin,  use  of  as  sealing  wax,  483 
Besume,  745 
Betort  furnaces,  650 
Betorts  for  gas,  648 

—  glass,  concentration  in,  208 
— -  platinum,  207 
Bererberatory  furnace.  18 
Bhea  grass,  341 

Bice  starch,  360 

BiNHANN^s  or  cobalt  green,  39 

Bock  salt,  165 

mode  of  working,  167 

Boll  sulphur,  197 
Boofing  tile?,  318 
Boots,  mash  from,  429 
Boseine,  575 
B0SB*s  apparatus,  232 
Bough  sted,  27 
Busina,  87 
Bussia  leather,  520 
Bussian  stoves,  734 

SAGCHABIMETBT,  369 
Sacdiarometrical  beer  test,  Bal- 
ling's, 420 
Sago,  361 
Safflower,  589 


Sal*  ammoniac,  application  of  gases  to 

the  manufacture  of,  16 
Salines,  method  of  obtaining  common 

salt  in,  164 
Halt,  common,  dixeet  conrersion  of 

into  soda,  188 
method  of  obtaining  in  saUneSi 

164 

—  —  method  of  preparing  from  sea- 

water,  163 
oocuirenoe  of,  163 

—  —  properties  of,  169 

uses  of,  170 

Saltpetre,  134 

—  and  sulphur  mixture,  156 

—  cruder  refining^  137 

—  mode  or  obtaining,  135 

—  occurrence  of  native,  134 

—  of  the  earth,  treatment  of,  135 

—  quantitative  estimation  ot  nitric 

add  in,  140 

—  testing,  140 

—  uses  of,  141 

Salt-springs,  mode  of  working,  167 

Samian,  or  oil-tawing  process,  526 

Sandal  wood,  588 

Sanitary  ware,  321 

Sap,  diemical  alteration  of  the  con- 
stituents of,  475 

— >  dimination  ot  the  constituents  of, 
474 

Saponification,  theory  of,  242 

—  with  Ume,  623 

—  —  sulphuric  add,  624 

water  and  high  pressure,  626 

SAUEBWEiN'smethod  of  deoompositum 

cryolite  with  caustic  lime,  259 
Saxony  blue,  603 
ScHAFFNBB's  sulphuT    regeneration 

process,  186 
ScHBBLE*s  green,  57 
Schist  or  alum- shale,  257 
SCHWABZ'S  apparatus,  436 
ScHWEiNruRT  green,  58 
Sealing-wax,  Tise  of  resin  as,  483 
Se&-w^  carbonised,  iodine  from,  192 
Sea-weeds,  potassa  salts  fnmi,  129 
Sea-water,  method  of  preparing  com* 

mon  salt  from,  163 

—  potassa  salts  from,  122 
Seridcultuxe,  601 

Shaft  or  cupola  furnace,  18 

Shagreen,  537 

Shear-steel,  29 

Sheep-shearing,  498 

Shot  manufacture,  62 

Siderography,  31 

SideroUte  and  terraUte  ware^  307 

Sibmbnb's  apparatus,  440 

SUica  ultramarine  preparation,  267 

Silk,  501 

Silk  bleaching,  599 

—  dydng,  606 


IKDBX. 


iiii 


Silk  goodiy  printiof;,  616 

—  manipulatioii,  603 

—  floonnng  or  boiJiiig  the  gum  ont, 

604 

—  testing,  604 

—  to  diflSngoish  from  wool  and  rege- 

table  fibre,  606 

—  weaTing,  605 
Silkworms,  601 
Silyer,  alloys  of,  103 

—  alloy  for  plate,  103 

—  and  gold  for  electro-plating,  115 

—  and  its  occnrrenoe,  96 

—  assay,  103 

^  chemically  pore,  102 

—  extraction  by  amalgamation,  97 

AuouBTiN'B  method,  99 

the  dry  way,  100 

from  its  ores,  96 

—  —  sundry  hydio-metallnTgicsl  me- 

thods of,  99 

—  German  or  nickel,  53 

—  mode  of  preparing  the  lead  con- 

taining, 100 . 

—  nitrate  of,  105 

—  oxidised,  106 

—  properties  of,  102 

—  redaction  by  means  of  zinc,  102 
•—  refining  process,  100 

—  smelting  for,  directly,  97 

—  solution  for  electro-plating,  116 
— •  ultimate  refining  of,  102 
Silvering,  104 

—  by  the  wet  way,  105 

—  —  fire  or  igneous,  104 

—  in  the  cold,  104 
Sizing  the  paper,  351 
Skins,  513 

Skin  of  animals,  anatomy  of,  608 

Slaking  lime,  326 

Smalt,  38 

Smelt,  the  mixing  of  the,  6 

Smelting  for  sold,  106 

silver  mrectly,  97 

—  —  white  metal,  49 

—  of  nickel  ores,  40 
the  ore,  5 

—  operation,  products  of,  7 

—  process,  oouree  of,  13 
Smoke  consumption,  745 
Smoke-consuming  apparatus,  741 
Snuff,  480 

Soap-boiling,      raw     materials     of, 

239 
Soap,  chief  varieties  of,  243 

—  uisoluble,  249 

—  making.  239 

—  tests,  248 

—  transparent,  248 

—  uses  (Xf,  248 

S  )ape,  toilet,  247 

—  various,  247 
Soda-alum,  261 


Soda-ash,  171 

Soda,  aluminate  of,  262 

—  bicarbonate  of,  190 

—  caustic,  189 

—  crude,  conversion  of  sulphate  into, 

174 
lixiviation  of,  176 

—  direct  conversion  of  common  salt 

into,  188 

—  from  chemical  processes,  172 
cryolite^  188 

nitrate  of  soda,  189 

soda  plants,  and  from  beet- 
root, 171 

—  furnace,  with  rotatory  hearth,   176 

—  hyposulphite  of,  201 

—  manufacture^  170 

—  occurrence  of  native,  170 

—  preparation  from  sulphate  of  soda 

187 
— •  stannate  of,  76 

—  sulphate,  213 

—  sulphate  uses  of,  214 

—  ultramarine  preparation.  266 

—  wastes  sulphur  from,  198 

—  waste  utilisation,  184 
Sodic  nitrate,  141 

Soft  soap,  246 

Solferino,  675 

SoKDBYS  process  of  preparing  phos- 
phorus, 644 

Spathic  iron  ore,  green  vitriol  from,  32 

Spathose  iron  ore,  8 

Sperm,  or  spermaceti  candles,  634 

Spinning  cotton.  342 

Spinning  flax,  340 

Spirit  from  dry  distillation  of  wood, 
472 

•—  manufacture  raw  materials,  425 

—  varnish,  489 

Spirits  from  the  by-products  of  sugar 
manufacture^  430 

—  from  wine  and  marc,  430 

—  the  preparation  or  distlllatioa  cf. 

424 
Spongy  platinum,  95 
Stags,  6 

Btege,  or  ^tage  grate,  743 
Stamp  machine,  347 
Stasfobd  and  Mobidb*b  method  of 

preparing  iodine  from  carbonised 

sea- weed,  192 
Stannate  of  soda,  76 
Staich,  355 

—  commercial,  constituents  and  uses 

of,  360 

—  from  potatoes,  357 

—  nature  of,  356 

—  rice,  chestnut,  Cassava  arrow-root, 

360 

—  sources  of,  357 

Starch-meal,  boiling  with  dilute  snl- 
*   phuiic  acid,  384 


xiv 


^ 
4 


Starch  sngar  compoeition,  386 
BtatiflticB  conoemlDg  the  production 

of  crade  iron,  18 
Statistiofl  of  Bteel  production,  31 
Steam  brewing,  418 

—  for  heating,  740 
Stearine  candUes,  621 
Steel,  26 

—  and  other  metals,  30 

—  engraying,  31 

—  from  midleable   and   crude    cast 

iron,  29 

—  production,  statistics  of,  31 

—  properties  of,  29 

—  hardening,  29 
fitep  grate,  742 
Stereochromy,  285 
Stibium,  82 
Stoneware,  305 

—  lacquered.  307 

—  OTcns,  306 
StoYe  heating,  733 
Stoves,  compound,  735 

—  iron,  734 

—  of  fire-clay,  734 
Strass,  288 
Styrian  cast-steel,  27 
Sugar-beet,  vinegar  from,  466 
Sugar-candy,  382 
Sugar-cane,  364 

-s-  components,  364 

Sugar,  draining  the  crystals,  381 

—  historj  of,  362 

—  manufacture,  362 

—  beet-root,  367 

—  spirits  from  the  by-products  of,  430 

—  nature  of,  362 

—  of  the  grape,  392 

—  preparation  from  the  beet,  370 

—  preparation  of  moist,  raw,  or  loaf, 

380 

—  raw,  preparation  from  the  sugar- 

cane, 3G5 

—  production,  367 

—  refining,  366 

-^  remoying  from  the  form,  381 

—  solution,  evaporating  and  purify- 

ing, 385 

—  starch,  composition,  386 
<--  varieties  of,  366 
Suint,  gas  from,  675 

—  potassa,  salts  from,  132 
Sulphate  of  alumina,  261 

—  ^-  alumina  and  alum,  uses  of,  263 
w.  —  ammonia,  238 

copper,  54 

potassa,  121 

soda,  213 

zinc,  81 

—  or  decomposing  furnace,  172 
Sulphates  of  alumina,  256 
Sulphide  of  carbon,  210 
Sulphite  of  lime,  201 


Sulphur,  194 

—  as  a  by-prodnot  of  gas  mannfao- 

tme,  198 
Sulphur,    by    heating    eulphmetted 
hydrogen,  198 

—  chloridi,  211 

—  flowers  of,  197 

—  for  refining  gold,  107 

—  from  soda  wvste,  198 

—  obtained  by  the  reaction  of  solpha- 

rouB  add  on  chansoal,  198 

—  preparation  of  from  pyrites,  197 

—  production    by   the    reaction    of 

sulphuretted  hydrogen  upon  sul- 
phurous add,  198 

—  properties  and  uses  of,  199 

—  reg6nerationprooeBs,8cHAFFNBB*8, 

186 

—  smelting  and  refining,  194 
Sulphurets  of  arsenic,  86 
Sulphuric  add,  201 

conoentration,  206 

—  — -  decomposition  of  bone-ash  by, 

538 

—  —  green  vitriol  from,  32 

for  refining  gold,  107 

fuming,  202 

manufacture,  other  methods  oL 

208 
mash  with,  428 

—  —  ordinary  or  Bi^lish,  203 

present  manufacture  o^  203 

properties  of,  209 

'  saponification  by  means  of,  624 

separation  from  the  sugar  aolu- 

tion,  385 
Sulphurous  add,  199 
use  of  pyrites  for  the  preparation 

of  sulphurous  add,  206 
Sumac,  510 
Sun  hemp,  341 
Swedish  iron  refining,  22 

TALLOW  candles,  629 
Tanning,  508,  516 

—  in  liquor,  517 
the  bark,  516 

—  materials,  509 

estimation  of  value  of,  512 

—  quick  process,  517 

—  the  several  operations,  513 

Tar,  condensation  of  the  vapours  of, 
686 

—  distillation  of,  688 

—  mode  of  operating  with,  688 

—  preparation  ot  685 

—  properties  of,  687 

Tawer's  softening  iron  to  smooth  the 

leather,  519 
Tawing,  622 

—  common,  522 

Temperature  of  blast-fomace  at  dif- 
ferent points,  16 


Tempering,  20 

—  steel,  30 
Teira-Ksotta,  311 

Tetralito  and  siderolite  ware,  309 

Thickenings,  610 

Thomsen's  method  of  decompoBition 
of  cryoHte  by  ignition  with  car- 
bonate of  lime,  269 

Tiles  drain  and  gutter,  318 

—  roofing  and  Dutch,  318 
Tin,  73 

—  applications,  74 

—  nitrate  of,  76 

—  preparatioos  of,  75 

—  properties  of,  74 
Tinned  sheet  iron,  75 
Tinning,  75 

—  of  copper,  brass,   and   malleable 

iron,  75 
Tinsalt,  75 
Tobacco,  477 

—  leaf,  chemical  composition  of,  478 

—  manufacture,  478 

—  smoking,  479 

Tow,  or  tangled  fibre,  340 
Tubes,  distillation  ot  zinc  in,  79 
Turkey  red,  608 
Turmeric,  596 

TUKNBULL'B  bluc,  37 

Turpentine  oil  varnishes,  490 
Tyraline,  675. 

UCHATIUS'S  steel,  28 
Ultramarine,  264 

—  artificial,  264 

—  cobalt,  38 

—  constitution  of,  267 

—  conversion  of  green  into  blue,  266 

—  green  preparation,  265 

—  manufacture,  264 

—  native,  264 

—  properties  of,  267 

—  sulphate  of,  preparation,  265 

YACUUM  pans,  377 
Yalonianuts,  611 
Varnish,  polishing  dried,  490 

—  spirit,  489 
Varnishes,  488 

—  oU,  489 

—  spirit,  coloured,  490 

—  turpentine  oD,  490 
Vases,  Etruscan,  309 
Vegetable  fibre,  technology  of,  338 
VeUum,  527 

Verdigris,  58 

Vienna  wool,  495 

Vienna  yeast,  460 

Vine  and  its  cultivation,  390 

Vinegar  and  its  origin,  460 

—  formation,  phenomena  of,  462 

—  from  alcohol,  461 
the  sugar-beet,  466 


XT 

Vinegar  from  wood  distillation,  469 
— •  making,  older  method,  462 
quick  process,  463 

—  testing,;  467 

—  witt^the  help  of  the  Myooderma 

aoeti,  466 

—  platinum  black,  467 

—  the  manufacture  of,  460 
Vinous  fermentation,  387 

—  mash  from  oer^kls,  426 
Vintage,  390 

,  Vitriol  blue,  64 

—  —  applications  ol  56 

—  double,  56 

—  green,  31 

from   metallic    iron  and  sul- 
phuric add,  32 

:;-^f*^.*^®  residues  of  pyrites 

distillation,  32  ^ 

in  beds,  preparation  of,  32 

preparation  of;  as  a  by-product 

in  alum  works,  32 

uses  of,  32 

—  white,  81 

Violrt  and  blue  naphthaline  pigments, 

—  imperial,  577 
VoOL»s  grate,  744 

Voltaic  electricity,   copper   obtoined 
by,  50 

Volumetrical  method,  224 

Vulcanised  caoutchouc,  486 

WALKERITB,  295 
Wanning,  731 
Water,  405 

—  coolers,  309 

—  gas,  671 

oarburetted,  672 

LfiPfiiNCS's,  674 

—  hol^  for  heating,  739 
Wax  candles,  631 
making,  633 

—  or  Vesta  matches,  553 
Weaving  silk,  506 

—  the  cloth,  499 

linen  threadf,  340 

Weld,  696 

Wkldon's  chlorine  process,  219' 
Wheat  starch,  preparation  of,  358' 
Whey,  567 
White  gunpowder,  154 

—  lead,  67 

adulteration  of,  72 

application  of,  72 

English  method  of  manufac- 
turing, 68  •"ui»c 

French  method  of  preparing,  69 

from  chloride  of  lead,  71 

sulphate  of  lead,  70 

manufactuie  at  CUchy,  appa- 
ratus used  in,  69  ^^ 
properties  of,  71