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IWJV.O* 


INDIARUBBER   AND  GUTTA  PERCHA 


V 


INDIARUBBER   AND 
GUTTA    PERCHA 

A    Complete    Practical    Treat 

ON 

INDIARUBBER    AND    GUTTA    PERCHA 

IN'    THEIR 

HISTORICAL,  BOTANICAL,  ARBORICULTURAL 

MECHANICAL,   CHEMICAL,    AND 

ELECTRICAL    ASPECTS 


TRANSLATED  FROM  THE  FRENCH 

OF 

T.    SEELIGMANN,   G.    LAMY  TORRILTION 
AND  H.    FALCONNET 

JOHN    GEDDES    MCINTOS1I 

LATE   IECTURER  ON  THE  CHEMICAL  TECHNOLOGY  OK  OUM8,    RRMINH,   RT< 
THE    POLYTECHNIC,    REOKNT   STRKKT 


WITH    145    ILLUSTRATIONS   AND  125  TABLES 


SeconD  Biifllieb  EMtion,  •Rcvtec^  an? 


LONDON 

SCOTT,     GREENWOOD      &      SON 

8  BROADWAY,  LUDGATE  HILL,  B.C. 

1910 

[The  sole  rights  of  TnmxMiim  into  Enylish  r?*t  icith  &ott,  GrteMDood  &  So*] 


ft 


AUTHORS' 


//'  flu'  reader  will  be  rjood  enough  to  take  a  rapid y lance  at  the 

resume  at  the  end  of  this  treatise,1  he  will  wry  readily  acknon-l>  tl<, 

ial  literature  devoted  to  india  rubber  unit  <jutt<i  j»  rcha  is  considerable,  not 
only  in  foreiyn  countries,  but  also  in  our  <>mi,  and  that  such  is  the  case 
although  only  a  comparatively  short  time  has  elapsed  since  the  discovery  of 
these  raw  materials  and  their  industrial  applications. 

If  we  to-day,  therefore,  undertake  the  responsibility  of  pre*>  n  tiny  to  tfie 
public  a  new  treatise,  dealing  ivith  the  same  subject,  it  is  not  for  the  mere  sake 
of  the  vainglory  of  adding  another  unit  to  tlie  already  considerable  number 
of  works  and  memoirs  published,  as   many  on  "gum  elastic"  as  on  "gum 
plastic"     We  have  a  higher  ambition,  a  less  futile  object.     We  acknun  < 
that  almost  all  the  treatises  hitherto  published  hace  the  great  merit  of  Im 
dealt  excellently  with  the  subject  from  the  special  point  'of  view  or  vantage 
ground  in  which  the  authors  were  placed,  but,  taken  as  a  whole,  they  are, 
nearly  always,  awanting  in  that  cohesion  and  in  that  unity  of  /?///•/« 
the  reader  looks  for  in  a  work  of  this  nature.     They  are  deficient  in  (hnj 
co-ordination  ivhich  is  so  essential  for  those  who  seek  to  embrace,  in  a  single 
glance  of  the  eye,  the  results  obtained,  up  to  a  certain  moment,  on  an;/  // 
xubject.     The  greater  number  of  treatises  v/VnV//,  t»  our  own  /,-//" //•/<</'/<•,  / 
been  edited  with  this  end  in  view,  contain,  most  ye /tern  II  i/t  obsolete  infvi 
and  no  longer  respond  to  the  wants  of  the  present  time.     Like  mnn,  books 
get  old  quickly  nowadays,  and  a  book  is  scarce///   n-ritten  before  if 
modification,  nay  even  completion. 

Freely  availing  ourselves  of  the  elements  of  an  abundant  special  /• 
and  profiting  by  our  own  personal  experience,  we  have  been  able  to  effect  our 
purpose,  to  combine  in  one  harmonious  whole  the  /< 
of  an  infinite  number  of  publications,  to  extract  from  them  tin  //•  <imnte^, 
and  mil],-''  of  them  an  exact  precis  or  /r'.s// ///,-'  rexptnalinri  to  the  needs  of  t tie 
present  day.     In  this  way  we  have  been  enabled  to  methodically  claujfy  in  their 
turn  or   rotation   the  plants    arodueimj   the  raw  material.  <'ial 

varieties    //*<»•/    mmmonly  met   with  on   the    international    iinirbt.   n-ith 
eharaHerixlic  sit/tlS  of  their    -IntHi-iil unlit ;i,   ami    /in re   al*u    hern    >  nahleit    to 
nxxii/n  ft,  tin-iii  n  certain    liabitut    i,,i  eneh  fiarf   t>f  the   <//<>!>,.       M<>r<  «•/•,  /•,  titanic 

to  these  elements^  >/•«•/////•/•  /«>•//  >•////////•</  /»>»/»•///  »-»»///y;»  /<//////  //•////  ///••  /'"fi< 
enlture  and  acclimatisation  o/'  iniiia.rnlln'r  and  gvttapercha  /  '  ftl 

</•  vote  Ourselves  t<>  a   erit'n-al  *///////   of  lh»     metlnul^   ••inji/fftt.tt.  not  onl;/  J\'i'  t/i< 
n>llect'n>n  of  the  latc.e,  bid  also  for  the  extraction  tlfi\frv,n  of  the   n-*jn. 
1'nbbi-r*  and  gutta  pcrchast  ami  thu*  ha>  mlleil  to  recommend  the 

method  which  appeared  to  us  tlie  most  adfantaijeon*for  ""/<  species. 

1  Omitted  from  Second  English  KUtio.i. 


vi  AUTHORS'    PREFACE 

After  having  studied  the  physical  properties  of  the  rubbers  in  their 
natural  state,  as  well  as  the  mechanical  transformations  which  are  necessary 
to  impart  to  the  crude  material  the  qualities  which  industry  demands  of  it, 
this  question  has  led  us  to  examine  such  a  singularly  interesting  phenomenon 
as  the  vulcanisation  of  indiarubber,  and  we  have  endeavoured  to  define  this 
transformation  in  as  plain  and  intelligible  a  manner  as  possible.  Our  theory 
may  be  criticised,  but  contradiction  throws  light  on  the  subject,  and  we  shall 
be  pleased  if,  in  giving  rise  to  discussion,  we  have  been  enabled  to  shed  some 
light  upon  a  question  which  is  still  so  obscure. 

We  have  next  studied  the  chemical  and  physical  properties  of  india- 
rubber  after  it  has  been  essentially  transformed  by  vulcanisation,  to  again 
occupy  ourselves  with  ike  reclamation  of  the  waste,  and  finally  to  dwell  a 
moment  on  extreme  vulcanisation,  that  is  to  say,  on  the  preparation  of 
hardened  rubber,  namely,  ebonite. 

We  have  assimilated  all  the-  data  at  our  disposal  on  the  methods  of 
analysing  rubbers,  and  examined  the  methods  of  technical  testing  and  valua- 
tion proposed  by  several  technological  savants ;  then  we  have  been  induced  to 
take  up  the  substitutes  and  artificial  products  capable  of  replacing  the  crude 
material  t-o  a  certain  extent,  whether  they  act  by  correcting  certain  faults  in 
the  latter,  or  ivhether  it  be  proposed  by  means  of  them  to  lessen  the  cost. 

In  regard  to  gutta  percha  we  have  followed  the  same  method  of  study,  not 
without  taking  into  account  the  difficulties  incidental  to  such  an  undertaking* 
The  botanical  origin  of  gum  plastic,  as  well  as  its  commercial  varieties, 
presents  to  any  one  who  ivishes  to  obtain  information  in  regard  thereto  a 
regular  muddle  or  maze.  To  face  this  labyrinth  is  to  incur  the  risk  of 
getting  lost  in  it.  If,  thanks  to  more  recent  researches,  the  darkness  tends 
to  be  dissipated,  complete  light  is  nevertheless  far  from  being  an  accomplished 
fact,  and  we  shall  be  pleased  if,  on  our  part,  we  have  contributed  a  little  to 
advance  such  a  difficult  and  complex  question. 

However  that  may  be,  we  -do  not  forget  that  our  work  is,  in  a  large 
measure,  the  result  of  the  labours  of  our  predecessors.  We  have  often,  in  fact, 
been  limited  to  assimilating  the  fruits  of  their  learned  and  patient  re- 
searches. We  have  not  always  and  in  every  instance  quoted  the  sources 
from  which  we  have  drawn  our  information,  so  as  not  to  hinder  the  progress 
of  our  work.  We  beg  the  specialists,  who  have  been  good  enough  to  lend 
their  often  precious  assistance,  to  receive  here  the  legitimate  homage  of  our 
sincerest  gratitude. 

If  the  reader  obtains  from  our  treatise  information  of  use  to  him,  we 
shall  be  amply  recompensed  for  our  efforts  and  our  trouble,  for  our  motto  is 
and  always  shall  be — 

To  BE  USEFUL. 


CONTENTS 

FIRST   PART 
INDIARUBBKR 

k»AO1 

HISTORICAL  INTKODUCTION  ........        3 

CHAPTER  I 

IndiaruhlMjr,  Latex;  Definitions;  Laticiferous  Vessels ;  Botanical  Origin,  Habitats         .       11 

CHAPTER  II. 

Methods  of  Obtaining  the  Latex — Methods  of  Preparing  Raw  or  Crude  Indiarubber         .       32 

CHAPTER   III 

Rubber  Cultivation  in  Various  Countries     .  .  .  .  .  .  .56 

CHAPTER   IV 

Classification  and  Valuation  of  the  Commercial  Brands  of  Raw  Rubber     .  .  .       fJ 

CHAPTER  V 

Physical    and    Chemical    Properties    of    the    Latex     and     of     Indiarubber  -  <  Jcini.il 

Considerations  .  .  .  .  .  .  .  .  .  .110 

CHAPTER  VI 

M.rhanical     Transfonn.it ion    of    Natural    Rubbt-r    into     Washed    or    Normal     Kiil>l-«-i 

(Purification)— Softening,  Cutting.  Washing.  Drying,  Storage  .     136 

CHAPTER  VII 

Mechanical  Transformation  of  Normal  Rubber  into  Masticated  Rubber     .  .  .142 


viii  CONTENTS 

CHAPTER  VIII 

PAGE 

Vulcanisation  of  Normal  Kubber     ....  .     162 

CHAPTER   IX 

Chemical  and  Physical  Properties  of  Vulcanised  Rubber     .  .  .     193 

CHAPTER   X 

Hardened  Rubber  or  Ebonite — Enamelling  and  Colouring  Ebonite — Ebonite  Veneers       .     212 

CHAPTER  XI 

Remarks  on  Mineral  Rubber  Fillers — Various  Rubber  Mixtures— Coloration  and  Dyeing 

Dental  Rubber — Analysis  of  Natural  or  Normal  Rubber  and  Vulcanised  Rubber       .     219 

CHAPTER  XII 

Rubber  Substitutes — Imitation   Rubber — Analysis  of  Substitutes    and    of   Vulcanised 

Indiarubber  containing  Substitutes  and  of  Ebonite      .....     260 

SECOND   PART 

GUTTA  PERCHA 
HISTORICAL  INTRODUCTION  .........     289 

CHAPTEjR   I 

Definition  of  Gutta  Percha — Botanical  Origin — Habitat — Descriptive  Botany  of  Gutti- 

ferous  Plants     ......  294 

CHAPTER   II 

Climatology— Soil— Rational  Culture— The  Dutch  Plantations  in  Java     .  .  .319 

CHAPTER  III 

Methods  of  Collection— Felling  and  Ringing  versus  Tapping— Extraction  of  Gutta  Percha 

from  Leaves  by  Toluene,  etc.,  and  from  Leaves  and  Bark  by  Mechanical  Means         .     328 

CHAPTER   IV 
Classification  and  Valuation  of  the  Different  Brands  of  Commercial  Gutta  Percha  .     339 

CHAPTER  V 

Physical  and  Chemical  Properties  of  Gutta  Percha,  Balata,  etc.  351 


CONTENTS  ix 

CHAPTER  VI 

Mrrh;uiir,il  Ttv.ttninit  <,f  (iutt.i  Percha — Clu-mical  II ml.  nitigof  Gutta  Percha— Bleaching 

Dental  Gutta  Percha — Reclamation  of  Gutta  Percha  .  ....     378 

CHAPTER  VII 

M»  thuds  of  Analysing  Gutta  Percha  .......     895 

CHAPTER  VIII 
Gutta  Percha  Substitutes     .........     402 

INDEX         .  .  .....  t<u 


LIST   OF   ILLUSTRATIONS 


I'AOE 

1.  Full-grown  Para  Indiarubber  Tree        .......         4 

2.  Six-months-old  Indiarubber  Tree          .......         5 

•'!.   llcvea  Brazilicnsis.     Flowering  Twig    .  .  .  .  .  .  .14 

4.  Manihot  Gla~<nrii.     Young  Branch,  etc.  .  .  .  .  .  .15 

5.  Castilloa  Elastica          .........       16 

6.  Ficm  Elastica    .  .  .  .  .  .  .  .  .  .17 

7.  Artocarpus        ..........       18 

8.  Artoca-rpus  Iiicisti          .  .  .  .  .  .  .  .  .19 

9.  Vahea   ...........       j<i 

10.  Landolphia  Owariensis .  ........       21 

11.  'funtumia  Elastica        .........       27 

12.  Plants  Producing  Root  Rubber  ...  .  .      29 

13.  Guayule  Rubber  .  .  .  30 

14.  Hatchet  for  Tapping  Rub  .  .       35 
1."..    Tujclinha  (cup)  for  Collecting  Latex    ...  .35 

16.  Seringneiro  Tapping  Para  Rubber  Tree  .       36 

17.  t'rceola  Elastica  .........       38 

18.  Latex-Collecting  Utensil  .....  40 
18 A.  Fumciro  or  Furnace  for  Smoking  Rubber       .                          .                                      .41 
18  u.  Mould  Used  in  "  Smoking "  the  Latex           ...  41 

19.  Smoking  Para  Rubber   ...  .  .  .       42 

20.  „  „ 43 

21.  Collecting  Rubber  by  Spiral  Tapping   .  .  .03 

22.  Utensils  and  Tools  Used  on  a  Rubber  Plantation  .       64 

23.  Collecting  Rubber  from  Castilloa  Trees  .  65 

24.  The  K.  L.  [Kala  Lumpur]  Coagulator  .....  .68 

25.  Plantation  Rubber  Washing  Machine .  .  .69 

26.  Testing  Rubber  Washing  Machines       ....  70 

27.  Hydraulic  Rubber  Blocking  Press         .  71 

28.  Vacuum  Dryer  for  Indiarubber  (Passburg)       .  .72 

(Scott) 

30.  Plan  of  Plantation  Rubber  Factory      . 

31.  Rubber  Plantation  Three  Years  Old      .  •       r4 

32.  ,,  „          Four  Years  Old       . 

33.  Machinery  for  Crushing  Guayulo  Rublu-r 

34.  Para  Rubber  Trees,  Palapilly,  Cochin,  India   . 

35.  Landolphia  which  yields  Mozambique  Rubber  .... 
3G.  Transverse  Section  of  CaUotropis  Gif/antca 


xii  LIST   OF   ILLUSTRATIONS 

FIG.  1'AGE 

37.  Transverse  Section  of  Landolphia  Gummifcra  .  .     115 

38.  Sections  of  Landolphia  Senegalensis     .  .115 

39.  Machine  for  Cutting  up  Eaw  Kubber    . 

40.  "Washing  Machine 

41.  Indiarubber  Washing  Machine  driven  by  Electric  Motor  .     139 

42.  Rolls  for  Washing  Machines     .  140 

43.  Rubber  Washing  Machine         .  .141 

44.  Mixer  (Elevation)          ...  .142 

45.  „      (Plan)      .  .  143 

46.  47.  Mixer,  with  Superimposed  Rolls     .  144 

48.  Improved  Mixing  Machine 

49,  50.  Machine  for  Cutting  a  Continuous  Sheet  of  Rubber  147 

51.  Automatic  Thickness  Gauge 

52,  53.  Micrometers  for  Rubber      ...  .148 

54.  Thicknesses  of  English  Sheet  Rubber   .  .     148 

55.  Horizontal  Sheet  Cutting  Machine        .    ,  .      149 

56.  Machine  for  Cutting  Circular  Sheets     ....  .150 

57.  Rickkers'  Crushing  Mixer         ...  .     151 

58.  Large  Calibre  Mixer      ...  .151 

59.  Heavy  Two-Roll  Calender        .....  .152 

60.  Three-Roll              „                   .                          ...  .     153 

61.  Six-Roll                  ,,                   ....  .154 

62.  63.  Four-roll          „                    .....  155,  156 
64,  65.  Six-Roll  Double-Effect  Calender     .....  156,  157 

66.  Machine  for  Making  Raised  Sheet-Rubber        .  .  .  .  .158 

67.  Horizontal  Spreader       .......  .159 

68.  Vertical  Spreader          .  .  .  .  ...  .  .  .160 

69.  Karmarsch  and  Heeren's  Vulcaniser      .......     176 

70.  High-pressure  Steam  ,,  .  .  .  .  .  .  .177 

71.  Coster,  Rickkers,  &  Co.'s  .  .  .  .177 

72.  Vertical  Steam-Cased  Vulcanisation  Pan  .  .  .  .  .  .178 

73.  Horizontal  Open-Type  ,,  .  .179 

74.  Single-Screw  Vulcanising  Press  .......     180 

75.  Hand-Power  ,,  .......     180 

76.  „          Screw         „  .......     181 

77.  Double-Screw  Vulcanising  Press  .......     181 

78.  Vulcanising  Screw  Press  with  Three  Plates       .  .  .  .  .  .182 

79.  ,,  Press  with  Cylindrical  Guide        .  .  .  .  .183 

80.  Hydraulic  Vulcanising  Press  (Six  Pistons)        .  .  .  .  .  .183 

81.  „  „  (Six  Plates)          .  .  .  .  .  .184 

82.  „  „  (Birmingham,  U.S.A.)    .  .  .  .  .185 

83.  ,,  ,,  (Decauville)         .  .  .  .  .  .185 

84.  Three-Nip  Hydraulic  Press       .  .  .  .  .  .  .  .186 

85.  Hydraulic  Vulcanising  Autoclave          .......     187 

86.  Indiarubber  Band  Used  in  Stewart's  Experiments        .....     19£ 

87.  Graphical  Representation  of  „  .     198 

88.  Effect  of  Pressure  on  Rubber  Bands       .  .  ....      201 

89.  Apparatus  for  Reclaiming  Rubber  Waste          ......     207 

90.  Fine  Grinding  Machine  for  Rubber  Tyres         ......     208 

91.  Apparatus  for  Elongation  Experiments  ....  .231 


LIST  OF   ILLUSTRATIONS  xiii 

FI<:.  r.\i;K 

92.  AI>|  MI  at  us  for  Determining  Breaking  Strain    ...  j  .: 

Deformation  of  Pleated  Bobber 
94,  i'f>.    I)\  nan  uiiii'ter  Diagrams    .......          'J.">1,  254 

.'<;.   Dynamometer  for  Tensile  Te*ta          .......    255 

97.  ,,          for  OompreMion  Tetti .  ......     'jsri 

98.  ,,  l"i  IVmling        ,,.......     256 

99.  100.      „  for  Al.i..>i..n       .......          25«;. 

101.  Chopper's  Bnbber-Teflting  Machine   .  .'          . 

102.  Cutting  Machine  for  Test  Samples      .....  .259 

103.  Apparatus  for  Extracting  Resin,  etc.,  from  Kuliln-r    .....  266 

104.  Autoclave  for  Analysis  of  Rubber        .......  266 

105.  Microscopic  sections  of  Palaquiiim  Gutta        ......  294 

106.  Branch  of  D/e/itf/W* '/"'/•'       ....... 

107.  Dichopsi*  Oblonyifo!  i  n  IK           ........  303 

108.  ,,        Borncense     .........     304 

109.  ,,        Trcubii        .........     305 

110.  Paycua  Lerii  ..........     306 

111.  Cake  of  Gutta  Sandck .  .                         .            .            .            .            .            .307 

112.  Mimusops  Batata         .........     309 

113.  Bassia  Parkii  ..........     310 

111.  „             ,,         (Fruit  and  Branch)    .             .             .             .             .             .             .311 

115.  ,,  ,,         (Cross  Section  of  Young  Branch)       .  .  .  .  .312 

116.  Gutta  Percha  Plantation  in  Java         .  .  .  .  .  .  .323 

117.  Golf-Ball  Testing  Apparatus  .  ....  .353 

118-122.  Sections  of  Submarine  Telegraph  Cables  ....          357-359 

123.  Lead  Press  for  Covering  Electric  Cables         ......     360 

124.  Machine  for  Covering  Wires  with  Gutta  Percha         .....     363 

125.  Gutta  Percha  Slicing  Machine  .  .  .  .  .  .  .379 

126.  Section  of  Breaking,  Mixing,  and  Rolling  Machine-  .....     380 

127.  Slicing  Machine  or  Chopper    .  .  .  .  .  .  .  .381 

128.  English  Washing  Machine      .  .  .  .  .  .  .  .381 

129-131.  Filter-Press          ........         382,  883 

132,  133.  Sections  of  Drying  Machine        .....  ;     383 

134.  Leblanc's  Masticator   .........     384 

135-138.  Three-Cylinder  Mixers     ...  .  387,  388 

139,  140.  Rolling-Mills       .......  389,  390 

141.  Truman  Washing  Machine      .  .  .  .  .  .  .  .391 

142.  Masticating  Drying  Machine  .....  .     392 

143.  Masticator        ..........     393 

144.  Electrometer  .  .     399 


LIST   OF   TABLES 


TABLE  pAGE 

I.  Typical  Analysis  of  Para  Latex  .  .11 

II.  Distribution  of  Landolphia 

III.  Classification  of  Landolphia      ....  .26 

IV.  Methods  of  Coagulating  Latex  ...  .40 
V.  Analysis  of  Para  Rubber  Latex             ....  .43 

VI.  Natural  Habitat  of  Rubber  Plants        ....  .57 

VII.  Growth  and  Development  of  Manihot  .            .             .             .  .             .61 

VIII.  Tappings  giving  Non-Coagulable  Latex            .             .  .66 

IX.  Rational  Manure  for  Rubber  Plantation            .             .             .  .             .76 

X.  Defective      „           „                    ,,....  .77 

XL  Manure  for  Rubber  Plantation  on  Rich  Land  .             .             .  .             .77 

XII.        ,,           ,,                   ,,          on  Poor  Land  ...  .78 

XIII.  ,,       for  Green  Manuring      .             .             .             .             .  .             .79 

XIV.  Rubber  Exports  from  Ceylon    .  .  .  .  .  .  .79 

XV.  Elevation  and  Rainfall  of  Ceylon  Plantations  .  .  .  .  .80 

'  V  Composition  of  Ficus  Elastica  Rubbers  from  Borneo  .  .  .  .    -j 

XVI  A.  j  v88 

XVII.   Analyses  of  Gold  Coast  Rubber  ......       89 

XVIII.  Percentage  of  Solid  Matter  in  Latex     .  .  .  .  .  .110 

XIX.  Density  of  Rubber  Latex  .  .  .  .  .  .  .111 

XX.  Analysis  of  Para  and  Assam  Latex        ......     Ill 

XXI.  Chemical  Composition  of  Latex  of  Hevea  Braziliensis .  .  .  .114 

XXII.  Constants  of  Sugars  of  Dambose  Type  .  .  .  .  .  .117 

XXIII.  Ultimate  Analysis  of  Pure  Para  Rubber  .  .  .  .  .119 

XXIV.  „  ,,         of  Rubber    .......     119 

XXV.         ,,  „        of  Ficus  Rubber      .  .  .  .  .  .119 

XXVI.  Density  of  Commercially  Pure  Rubbers  .....     120 

XXVII.  Analysis  of  Bouchardat's  "  Synthetic  Rubber  "  .  .  .  .126 

XXVIII.  Solubility  of  Rubber  in  Various  Sol  vents          .  .  .  .  .128 

XXIX.          ,,  ,,  in  Benzol  .  .  .  .  .  .130 

XXX.  Percentage  of  Oxygen  in  Rubber  ......     130 

XXXI.  Analysis  of  Rubber  Extracted  from  Waterproofs          .  .  .  .131 

XXXII.  Loss  on  Washing  Crude  Rubber  ......     141 

XXXIII.  Variations  in  Tensile  Strength  of  Rubber         .  .  .  .  .166 

XXXIV.  Ingredients  of  Mixture  for  Curing  Rubber        .  .  .  .  .174 
XXXV.  Tension  of  Steam  at  Different  Temperatures    .             .             .             .             .176 

XXXVI.  Action  of  Carbon  Disulphide  on  Vulcanised  Rubber    ....     191 
XXXVII.  Density  of  Different  Sorts  of  Rubber    .  .193 


LIST  OF  TABLES 


TAIM.l. 

XXXVIII.    Kir.-.-t  of  Mixtures  on  Density  of  Rubber 

XXX  IX.    ItuliliiT  Hands  used  in  Sh-v 

Kloii^itiuit  of  Hands  under  Different  Weights 
X  LI. ) 

XL1L  Invariability  of  Volume  of  Depressed  Caoutrhou.- 
XI.I1I.   Acids  used  in  lle«-l{iiiniiig  Unblu-r  Waste 
Xl.iv.   I •'.\ji;in>ion  of  KUmitr  ;it  Different  TeraperfttarM 
,XLV.  Substances  Mixed  with  Iiuliarubbi-r  (Hubbn-  fillers). 
XL  VI.  Rubber  Compositions  for  Various  I'm  poses    . 
XLVII. 
XLVIII. 
XLIX.  Rubber  used  by  Dentists 

L.  Calculations  for  Finding  Density  of  Rubber  . 
LI.  Scale  of  Densities  and  Saline  Solution  Formula* 
LII. 

'  /^Influence  of  Ash  on  Density  . 
LI  \  .  1 

LV.J 

LVI.  Mixture  for  Calcining  Rubber 
LVII.  Results  of 


'  |  Pigments  used  ill  Colouring  Rubber . 


T  T  V 
' 
LX. 

LXI. 
LXII. 
LXII1. 
LXIV. 
LXV. 
LXVI. 
LXVlA. 

VVTT 

LXVIII. 
LXIX. 
LXX. 
LXXI. 
LXX  1  1. 
LXXIII. 


LXXV. 

LXX  VI. 

LX  XVII. 

LXXVIII. 

LXXIX. 

LXXX. 

LX  XXI. 

LXXXII. 

LXX  X  III. 

LXXX  IV. 


Analysis  of  Vulcanised  Rubber 

J 

Loss  Sustained  by  Rubber  when  Heated 
Analysis  and  Valuation  of  Vulcanised  Rubber 
Tests  of  Rubber  under  Pressure 
,,  ,,  ,,      Hammering    . 

\ Chemical  Experiments  on  Vulcanised  Rubber  and  Ebonite 

|  Physical  Experiments  on  Vulcanised  Rubber  and  Ebonite 

(1  and  2).  Summary  of  Heinzerling  and  Pahl's  Results 
Moisture,  Sulphur,  and  Ash  in  Rubber  Substitutes  . 
Results  of  Repeated  Analysis  of  Vulcanised  Rubber  . 
Ratio  of  Insoluble  Sulphur  to  Rubber  in  Vulcanised  Para 
Effect  of  Alcoholic  Potash  on  Rubber 
,,  ,,         Soda  on  Ebonite  . 

Analyses  of  Sophisticated  Rubbers    . 

, ,         of  Commercial  Rubber  Substitutes 
, ,         of  Substitutes  prepared  from  Oils  . 
Effect  of  Sulphur  Chloride  on  Oil  Substitutes 
,,  ,,  on  Pure  Para  Rubber 

,,  ,,  on  English  Sheet . 

,.  ,,  on  Commercial  Shelt 

Analyses  of  Vulcanised  Rubber  containing  Substitute 
Composition  of    ,,  ,,  ,,  ,, 

Analyses  of  Rubber  Mixtures  containing  Asphaltuni 
of  Ebonite 


196 
(191 

»  KM 

207 

•ji: 

220 

I  '-"--" 

Ian 

UB 


226,  227 

.     228 
.     220 

230,  231 


.  233 

.  -234 

.  237 

.  237 

240-243 

244-247 

248,  249 
.  269 
.  271 

.  -j;i 
.  272 
.  272 

.     179 


274 

l^7o 
73 

280 
280 
281 

282 


xvi  LIST  OF  TABLES 

TABLE  PAGE 

LXXXV.  Mixing  for  Red  Washers         .  .     284 

LXXXVI.  Solvents  for  Nitro-Cellulose   .  .  .  .  .  .  .286 

LXXXVII.  Analysis  of  Coagulated  Latex  of  Isonandra  Gutta      .  .  .  .     292 

LXXXVIII.  Sapotaceous  Plants  which  should  Yield  Gutta  Percha  .  .  .309 

LXXXIX.  Synoptical  Table  of  the  Principal  Guttiferous  Plants  .  .          314-317 

XC.  Analysis  of  Gutta  Perchas  of  Known  Botanical  Origin  .  .  .     318 

XCI.  Analysis  of  Commercial  Samples        .  .  .  .  .  .321 

XCII.  Gutta  Percha  Extraction  by  Toluene  .  .....     337 

XCIII.  Valuation  of  the  Different  Brands  of  Commercial  Gutta  Percha         .          342-349 
XCIV.  Analyses  of          ,,  ,,  .  .  .  .          348,  349 

XCV.         „         of  Getah  Taban  Merah  and  Getah  Soondie  .  .  .  .350 

XCVI.         ,,         of  Singapore  Gutta  Perchas  .  .  .  .  .     350 

XC  VII.  Tenacity,  etc.,  of  Gutta  Percha          .  .  .  .  .  .352 

XCVIII.  Elasticity  of  Gutta  Percha      .  .  .  .  .  .  .352 

XCIX.  Analysis  of  Oxidised  Gutta  Percha     ......     356 

C.  Elementary  Composition  of  Gutta  Percha      .....     358 

CI.  Classification  of  Submarine  Cables      ......     358 

OIL  Gutta  Percha  on  Cores  of  Early  Cables  .....     361 

CIII.  Variations  in  Resistance  of  Gutta  Percha  at  Different  Temperatures  .     364 

CIV.  Dielectric  Strength  of  Gutta  Percha,  Caoutchouc,  and  Ebonite          .  .     365 

CV.  Analysis  of  Gutta  Percha  (Paylu's  Method)    ....  357 

CVI.  Properties  of  Hardened  Gutta  Percha  .  .  .  357 

CVII.  Elementary  Composition  of  Fluavile  .....  368 

CVIII.  „  „  ofAlbane    ....  368 


cix 

CX.  Destructive  Distillation  Products  of  Gutta  Percha     .             .  .                  370 
CXI.  Ultimate  Analysis  of  Pay  ena  Lerii     ......     370 

;??'  )  Analyses  of  Abyssinian  Gutta  f  371 

cxiit.j  •  \372 

CXIV.  Composition  of  Mimusops  Gutta  Percha         ...  372 

CXV.  Solubility  of  Gutta  Percha  in  Different  Solvents        .             .  373 

'  [Comparison  of  Commercial  and  Bassia  Gutta  Percha  /373 

cxviij  •  \374 

'  j  Analyses  of  Bassia  Gutta  Percha  f374 

cxix.j  •  \375 

CXX.  Analyses  of  Balata      ......  376 

CXXI.  Balata  Exports  of  British  Guiana       ...  377 
CXXII.  Waste  from  Gutta  Percha 

.  .       ooO 

CXXIII.  Insulation  and  Induction  by  Wet  and  Dry  Gutta  Percha      .  397 

CXXIV.  Electrical  Properties  of  Gutta  Percha,  etc.     .             .  401 

CXXV.  Gutta  Percha  Substitutes,  Formulae  for          ^            .  403 


FIRST  PART 


IND1ARUBBE11 


INDIARUBBER  AND  GUTTA  PERCHA 


HISTOKICAL  INTRODUCTION 

IT  would  be  superfluous  to  describe,  in  detail,  the  successive  phases  of  the  discover}' 
of  the  industrial  properties  of  that  peculiar  body,  called  Indiarubber.  Others  have 
already  done  so,  and  with  a  masterly  hand.  But  to  avoid  all  mention  of  these 
phases  would  be  to  forfeit  the  pleasure  of  doing  homage  to  the  powers  of  observa- 
tion, and  the  inventive  genius,  of  the  men  who  founded  a  great  industry  with 
a  substance  which,  at  the  outset,  appeared  to  be,  from  a  technological  point  of 
view,  of  very  trivial  value  indeed.  So  far  back  as  1868,  Turgan,  in  his  book 
on  the  Great  French  Factories  (les  Grandes  Usines  de  la  France),  was,  even  then, 
able  to  say :  "  Indiarubber  has,  at  the  present  day,  become  not  only  an  essential 
factor  of  industry,  but  also,  and  to  an  equal  extent,  of  everyday  life,  so  much  so, 
indeed,  that  its  sudden  suppression  would  cause  vast  confusion  in  a  great  number 
of  instances.  It  in  fact  enters,  under  every  size  and  shape,  into  the  whole 
equipment  of  civilisation,  from  the  railway  buffer  to  the  sight-piece  of  the  chasse- 
pot."  It  would  be  an  easy  matter,  at  the  present  day,  to  enlarge  to  a  much 
greater  extent  on  the  importance  of  this  substance,  the  manufacture  of  which  since 
then  has  increased  by  leaps  and  bounds.  Prior,  however,  to  discussing  the  present 
vast  and  multifarious  uses  of  indiarubber,  and  the  developments  which  the  rubber 
industry  has  now  assumed,  we  must,  in  the  first  instance,  glance  at  its  early  history, 
a  knowledge  of  the  vicissitudes  of  which  is  in  all  industries  so  essential  to  the 
expert  therein. 

It  was  Gonzalo  Fernandas  d'Oviedo  y  Valdas  who  first  mentioned,  in  his 
Gkneral  History  of  the  Indies  (Madrid,  1536,  L.  V.,  c.  ii.  p.  165),  "the  Indians' 
game  of  Batey,  which  is  the  same  as  the  game  of  ball,  although  played  in  a 
different  manner,  and  the  ball  is  made  of  a  different  substance  to  that  used  by 
Christians."  According  to  Morris,  the  first  record  of  indiarubber  was  made  soon 
after  the  discovery  of  the  New  World  by  Columbus.  The  Old  World  rubbers 
were  still  unknown.  During  the  second  voyage  of  Columbus,  it  was  noticed  that 
the  inhabitants  of  Hispaniola  (Hayti)  played  with  balls  made  from  the  gum  of  a 
tree.  This  was  fully  400  years  ago.  Father  Xavier  de  Charlevoix,  of  the  Society 
of  Jesus,  1682-1761,  describes  the  Batos,  a  species  of  ball  of  a  solid  matter,  but 
extremely  "  i>orous  and  light.  It  soars  higher  than  our  balls,  falls  on  the  ground, 
and  rebounds  much  higher  than  the  level  of  the  hand  which  it  quitted ;  it  falls 
back  again,  and  rebounds  once  more,  although  not  to  such  a  height  this 
time,  and  the  height  of  the  bounces  gradually  diminishes."  Antonio  de  Herrera 
Tordesillas,  the  Spanish  historian  (born  at  Cuellar  in  1549,  died  at  Madrid 
in  1615),  completed  these  data  in  1601  in  his  General  History  of  the  Voyages  and 
Conquests  of  the  Castilians,  in  the  islands  and  mainlands  of  the  East  Indies, 
and,  in  speaking  of  the  ball  used  by  the  Spanish  Indians,  enunciates  for  the 


INDIARUBBER 


first  time,  the  descriptive  term  gum.  The  same  author,  whilst  speaking  about 
the  conquest  of  Mexico,  quotes,  as  one  of  the  peculiarities  of  Cumana,  certain 
trees  which,  when  punctured,  yield  milk  which  becomes  converted  into  //////*  with 
a  fine  smell.  Jean  de  Torquemada,  in  his  book  of*  the  Monarquia  Iu<li<i,,<i. 
(Madrid,  1615),  mentions  the  uses  of  the  elastic  balls,  and  calls  tin-  tiv<-  which 
furnishes  the  milky  juice  from  which  they  were  elaborated,  Ulaquakutl,  or 
the  Ule  tree,  a  name  still  used  .by  the  natives  to  designate  the  Castilloa 
Markhamiana  and  the  Castilloa  elastica.  The  new  conquerors,  on  their  part,  made 


Fiu.  1.— Full-grown  Para  indiambber  tree  (HcrcaJBrazilicnsis) 
in  a  Brazilian  forest. 

use  of  rubber  itself  to  coat  their  hempen  cloaks,  and  thus  protect  themselves  from 
rain;  these  were  waterproof,  but  the  intense  heat  of  the  tropical  sun  greatly 
affected  them.  At  the  court  of  Montezuma,  in  the  ancient  Aztec  city  which  is  now 
Mexico  D.F.,  and  the  capital  of  the  Mexican  Republic,  they  played  a  sort  of  tennis 
in  walled  patios  with  balls  of  indiarubber.  The  tree  which  yielded  the  material 
for  these  earliest  tennis  balls  was  called  Ule  (with  certain  variants),  and  it  is 
known  in  Mexico  and  Central  America  amongst  the  Indians  as  Ule  to-day.  [British 
scientists  call  the  tree  Castilloa  elastica',  American  scientists  call  it  Castilla  elastica. 
There  are  many  species,  of  varying  commercial  value,  the  best  having  been  named 


HISTORICAL    IXTRODCC    IK  ).\ 


/(irt^f!  mi.  I'.ra/il  abounds  in  (  '«*i, 
thrill  is  inferior  to  the  product  of  th 
The  Brazilian  <''i*fill<'<t  rubber  i>  k 
whence  \\e  iret  tin-  variant  caoutc 
nearer  to  the  original  hulian  \M.nl 
tin-  ilejith  <•!'  tlie  (iniana  furots,  in 


ees,  luit  the  indiai  uliln-r  obtained  l'r«.iu 
as,  uhich  \ield  tin-  famuli*  Para  rubber. 
on  tin-  market-  »\  the  \\orld  a.s  «•»/»//•/<  «, 
r  it  ma\  !»«•  that  t: 


ular   lad,  si\  s    Mori'i-.    that    in 
n  \illa^re>  nn  the  t  ril.ntiiries  of 


the  Ama/.on,  and  in  the  heart  of  Africa,  similar  rul.l.er  balls  arc  >till  U-in^  unod  to 
plav  \\ith.      ()ften    it    i>   onl\    in    thi^  \\av  that    traveller^,    ha\e    ln-ennir   a«,ji, 
\\ith  the  existence  "f  nil.l.ei-  \  id.lin^  trees  in  the  \  icinit\.      Now  and  then,  in  these 
early  days,  >oine   ran-  samples  of   the  r  ///.<///•  j.rodnet  reaeln-,1    KurojM-   to   ..rnainont 
ihc  curiosity  cabinets  ..f  the  epoch.      It   was  \\orth  a  guinea  an  ounce. 


tlis-uld  imliarulilM-r  tree   //-'••"  Bntttiie***) 

dcni  plantation  in  Cochin,  Southern  India. 

lint,    coming    to    a   period    \\hen    the   history    U   more    definite   and    precise,    in 

17:U  the  Paris  Academy  of  Science  organised  two  expeditions  to  sohre  the 

(|iiestion  of  the  exact  shape  of   the  earth.      <  hie  ..f   these,  under  La  Condam: 
Bouguer,  went    to  the  equatorial  regions  of  South  . \ineri. -a.      BoUgUerwaa  a 
nomerand  a  learned  mathematician,  and  La  Condamine  wafl  B  I  kXJtorol  Medi- 
an  eminent  naturalist.       It  is  not   therefore  >urprisin,ur   that    the   latter  should   liave 
profited  by  the  opportunity  of  .xtudyin.ir  the  fauna  and  tl>ra  of  Peru  and  P.ra/il.       In 
L736,a  short   time  after  his  arrival  at  Quito  (capital  of  Keuadon.  LaCondainine 


6  INDIARUBBER 

« 

dispatched  to  the  French  Academy  of  Science  some  rolls  of  a  blackish,  resinous  mass 
known  under  the  name  of  caoutchouc.  His  parcel  was  accompanied  by  a  memoir  in 
which  the  following  occurs  : — "  There  grows,  in  the  forests  of  the  province  of  Esmer- 
aldas,  a  tree  called  by  the  natives  of  the  country  Heve;  there  flows  from  it,  by  simple 
incision,  a  liquor,  white  as  milk,  which  gradually  hardens  and  blackens  in  the  air. 
The  inhabitants  make  flambeaux  of  it,  which  burn  very  well  without  wicks,  and  give 
rather  a  fine  light.  ...  In  the  province  of  Quito,  sheets  of  linen  are  coated  with  it, 
and  are  used  for  the  same  purpose  as  we  use  waxcloth.  .  .  .  The  same  tree  grows 
along  the  banks  of  the  river  Amazon,  and  the  Mainas  Indians  call  the  resin  which 
they  extract  from  it  cahuchu  (pronounce  caoutchouc).  They  make  boots  of  it, 
which  do  not  draw  water,  which,  after  having  been  blackened  by  holding  them  in 
the  smoke,  have  all  the  appearance  of  real  leather.  They  coat  earthen  moulds  in  the 
shape  of  a  bottle  with  it,  and,  when  the  resin  is  hardened,  they  break  the  mould 
and  force  out  the  pieces  through  the  neck  and  mouth  ;  they  thus  get  a  non-fragile 
bottle,  capable  of  containing  all  kinds  of  liquid."  Pursuing  his  investigations,  he 
describes  the  peculiar  use  which  one  of  the  tribes  made  of  iudiarubber.  "  The  use 
which  is  made  of  this  resin  by  the  Omaguas,  in  the  middle  of  the  American  con- 
tinent, on  the  banks  of  the  Amazon,  is  still  more  singular ;  they  make  bottles  of  it, 
in  the  form  of  a  pear,  to  the  neck  of  which  they  attach  a  fluted  piece  of  wood.  By 
pressing  the  bottles,  the  liquid  which  they  contain  is  made  to  flow  out  through  the 
fluted  piece  of  wood,  and  by  this  means  these  bottles  become  real  syringes."  That 
is  the  origin  of  the  name  given  by  the  Portuguese  to  the  tree,  which  yields  this 
rubber,  Pao  de  Ciringa  (syringe-wood),  and  of  serinyarios  (seringueiros)  to  the 
rubber  collectors.  Preoccupied  by  his  scientific  researches,  determining  an  arc  of 
the  meridian,  Lacondamine  could  not  continue  his  investigations  on  the  indiarubber 
tree,  and  matters  would  have  remained  so  if  he  had  not  found,  in  Fresneau,  the 
French  engineer  stationed  at  Cayenne  (an  isle  of  French  Guiana),  a  collaborateur  as 
persevering  as  he  was  enlightened.  Fresneau,  who  seems  to  have  foreseen  all  the 
future  importance  of  indiarubber,  carefully  inquired  into  its  real  source.  No  toil 
rebuffed  him,  not  even  the  horrors  of  a  residence  in  Cayenne,  and  finally  he  found 
among  the  Coussaris  Indians  the  much-sought-after  tree.  In  a  note  which  he 
addressed  to  Lacondamine,  he  described  the  characteristics  of  the  yum  tree,  and,  at 
the  same  time,  communicates  the  first  exact  notions  as  to  the  methods  employed 
by  the  natives  to  obtain  indiarubber.  "  They  commence,"  he  says,  "  by  washing  the 
foot  of  the  tree ;  then  they  make,  with  a  bill-hook,  longitudinal  but  rather  oblique 
incisions  which  should  penetrate  the  whole  thickness  of  the  bark,  taking  care  to 
make  them,  one  above  another,  so  that  the  flow  from  the  top  incision  falls  into 
the  incision  underneath,  and  so  on,  until  the  last  one,  at  the  bottom  of  which  a  leaf 
of  the  Balisier  (an  American  reed)  is  placed,  which  is  made  to  hold  the  liquid  l>y 
potter's  earth,  so  as  to  lead  the  juice  into  a  vessel  placed  at  the  foot  of  the  tree. 
To  utilise  the  milky  juice  of  the  different  trees  which  I  have  mentioned,  all  of  which 
are  resinous,  a  mould  is  made  of  potters'  earth,  according  to  the  shape  of  the  vessel 
which  it  is  intended  to  make,  and,  to  hold  it  more  conveniently,  a  piece  of  stick 
is  sunk  in  the  place  which  is  not  to  be  coated  with  milky  juice.  An  aperture  is 
thus  secured  through  which  the  potter's  earth  may  be  afterwards  expelled,  by 
introducing  water  to  soften  it.  Any  one  mould  being  shaped,  polished,  and 
softened  with  water,  it  is  coated  all  over  with  milky  juice  by  means  of  the  fingers, 
after  which  this  coating  is  exposed  to  a  denser  smoke,  where  the  heat  of  the  fire 
hardly  makes  itself  felt,  keeping  constantly  turning  it,  so  that  the  juice  may  be 
spread  equally  over  the  mould,  and  taking  good  care  that  the  flame  does  not  reach 
it,  which  would  cause  the  milky  juice  to  boil,  and  thus  to  form  small  holes.  As 
soon  as  a  yellow  colour  is  seen,  and  this  first  coating  is  no  longer  tacky  to  the 
fingers,  a  second  layer  is  applied,  which  is  treated  in  the  same  way,  and  so  on  with 
the  other  coats,  until  it  is  judged  to  be  sufficiently  thick,  and  then  it  is  kept  longer 
over  the  fire  so  as  to  evaporate  the  whole  of  the  moisture,  until  nothing  but 
elastic  resin  remains,  .  .  .  finally,  the  objects  will  be  the  more  substantial  the 
greater  the  number  of  coats  which  have  been  applied.  With  this  juice  and  linen 


HISTORICAL   INTRODUCTION 


sheeting,  tarpaulins,  pump  ho-,-,  (liven1  clothing,  hottl.-*.  -ack-  for 
campaigning  biseiiits,  etc.,  may  \><-  made,  \\ithoiit  tear  of  thi-  material  imp  rtinj- 
any  l»ad  .-mell  ;  l»ut  all  these  things  can  »nly  be  executed  on  the  sjiots  when-  the 
trees  grow,  as  tlirsr  juices  «OOW  /0*C  t/iri'r  jluiilit  //." 

The  communications  of   Lacondamine  and   |-'iv-n.-au  indu.vd  tin-  r'r.-nch  bol 
t  Al>let   to  start  for  Guiana   in    17ii_,   and   two  yean*  later  lie  puMi-hr.i 
/7o/-«/   o/"  (,'in'-i,i,i,    in   which    he  gave   a  botanical   description   nf    the    indiaruliliur 
tree,    \\liicli    he   named    //,/•,</    </»//<  mentis.      A   doctor  of    mcdicin,-    of    I'man- 
Prince  of  \Vali-s  Island,  .lame-  llowison,  \\as  the  tir-t   to  determine.  in   17!'^.  under 
th'-  name  of  an  da*ti<-  <iiint  /•///?,  the  speei»->  that  later  on  \sa-  c,dl.-d  / 
by   lloxbnrgh,  who,    aided    by    Mr.  Smith    of    Sylln-t,   di-coveri-d    in   the   forests  of 
Uraliniapiitra,  in  Assam,  the    /•'/<•//>•  »  A/.s7/.-.-(.  the  Assam   i-iiMn-i-  trei-.      The  (M-niliar 
circumstances  under  \\hich  eadi  of  the-e  trees  wen-  re-pecti\r|y  «li-«-o\rr.-d   t-.yi«-l«i 
indiariil»l»er  are  so  intei-e^tin^  as  to  merit  de-eriptioii.      With  regard  t«»  the   I'rrcola 
f/>i*f/i'ii,  this   tree  was  the  principal  source  of  supply  from  the   Ka-t   prior  to  tin- 
introduction  of  that  from  the  Ficus  elastica.     Its  importance  .sr«-m>   to  have  been 
iliscovered   l»y  accident,  towards  the  close   of  the  last    century,    the  cin-um-taiH  - 
1  n>  ing  recorded  in  the  Asiatic  Researches  of   1798.     It  appears  from    the  narrative. 
that  in  clearing   a    way  through   the  jungle  with    eiitlas>es  in   the  island  of  jVnang, 
the  juics  which  had  collected  on  the  blades  turned  on  drying  into  a  sul-tan.- 
pnssessing  all  the  characteristics  of  indiarubber.       The  SOUK.-  of  the   juicr  was 
found  to  be  a  vine  about  as  thick  as  a  man's  arm,  which  trailed  along  the  ground 
for  a  grea£  distance,  sending  out  rootlets  from  each  joint,  and  ultimately  eliml'in^ 
to  the  top  of  the  highest  trees.     The  plant  was  introduced  into  various  botanic 
gardens  as  a  species  of  the  genus  Hevea,  to  which  the  well-known  Para  rubber  with 
which  it  is   still   occasionally  confused   belongs.     The   earliest    writer  on  A»am 
rubber  was  Dr.  Roxburgh.     His  attention  was  first  directed  to  the  rubber  as  a 
waterproofing  material  on  a  vessel    containing  honey,  sent  to  him  in    IS  10  from 
Sylhet  by  Mr.  Matthew  Richard  Smith.     More  recent  writers  assert  that  the  nat 
of  Assam  have  utilised  the  properties  of  gum-elastic  for  ages  to  waterproof  l>a>ket- 
and  to  burn  as  candles.1     Coltigny  discovered  in  Madagascar  a  sarmentose  plant 
of  the  jasmine  species,  which  furnishes  a  milky  juice  which,   in  thickening,  yield- 
an  elastic  juice,  like  indiarubber. 

M'inihot  Glazioivii  muell.  d'arg.,  the  tree  which  produces  the  rubber  known  in 
commerce  as  Ceara,  was  exploited  in  Brazil  for  a  considerable  period  before  it  \\a- 
botanically  identified.  It  was  discovered  by  Dr.  Glaziow,  a  French  botanist,  in  tin- 
neighbourhood  of  Rio  de  Janeiro,  Brazil,  and  was  described  and  named  after  him 
by  Mueller  in  Martin's  Flora  Braziliemis,  xi.,  part  ii. 

Although  some  seventy  species  of  Manihot  are  said  to  occur  in  Brazil,  it  wa> 
generally  stated  until  quite  recently  that  Manihot  (?!n  :/**//•//  alone  yielded  rubU-r 
of  commercial  value,  but  it  now  transpires  that  a  distinct  species  is  Iteing 
cultivated  in  South  America.  The  latter  plant  appears  to  he  well  known  in  San 
Paulo,  South  Brazil,  but  it  has  not  been  botanically  identified  nor  is  it  known 
how  the  rubber  which  it  produces  compares  with  that  yielded  l>y  Mnnilot  f, 

The  utilisation  of  rubber  for  making  articles  for  domestic  pnrp'-e-  WM  not  only 
practised  by  the  natives  of  Central  and  South  America,  but  also  by  the  tribe- 
inhabiting  Assam,  long  before  it  was  known  to  Kuro()eaii  nations.  Krnst  states 
that  the  "  Cambibas,  a  section  of  the  tribe  Amaguas  on  the  rpjH-r  Amazon,  used 
rubber  juice  in  pre-Columbian  times  to  make  waterproof  vessels  for  carrying  food 
and  water,  giving  it  the  name  of  caucho,  no  doubt  the  original  of  oiir  word 
caoutchouc."  Further,  it  is  related  that  in  1755  the  King  of  Portugal.  Don  Jose\ 
having  heard  of  the  wonderful  waterproof  materials  used  by  the  India  i 
several  pairs  of  his  royal  boots  to  Para  in  order  that  they  might  l>e  <•..  \.-i.d  \\ith 
rubber."  It  would  appear  to  have  been  towards  the  end  of  the  eighteenth  century 

1  In  any  case,  Assam  rubber  was  unknown  in  Cal«  ntt.i  in  1828,  as,  wlu-n  .in  ui»«>untr\ 
gentleman  sent  some  to  his  Calcutta  agents,  they  replied,  "  the  article  beinj?  unknown  ir 
market,  we  are  sorry  we  can  give  you  no  idea  of  its  value." 


8  INDIARUBBER 

before  rubber  was  imported  into  Great  Britain,  where  the  name  of  indianibber  was 
first  given  to  it  owing  to  the  facility  with  which  it  removes  black-lead  (graphite) 
pencil  marks.  Whilst  botanists  were  accomplishing  their  task,  chemists  studied  the 
new  resin,  and  succeeded  in  dissolving  indiarubber.1 

1761. — Herissant  and  Macquer  published  the  first  technical  monograph  on  india- 
rubber  "etudes  sur  les  racines  du  caoutchouc  de  cayennes,"  and  in  1763  addressed 
memoirs  simultaneously  on  caoutchouc  to  the  Paris  Academy,  and  enumerated 
DippeVs  animal  oil,2  spirits  of  turpentine,  as  well  as  pure  ether,  as  bodies  capable 
of  softening  and  even  of  dissolving  the  elastic  resin  insoluble  in  water  and  alcohol. 
They  proposed  to  use  this  resin,  softened  in  this  way,  in  the  manufacture  of 
medicinal  probes  and  small  tubes  for  use  in  laboratories.  1770. — The  English 
chemist  Priestley  (1733-1804)  called  the  attention  of  the  scientific  world  to  the 
use  of  indiarubber.  He  recommended  the  use  of  the  "  rubber  "  for  effacing  pencil 
marks.  1772-75. — It  was  Magellan  who  spread  this  method  in  France,  and,  at 
the  stationers'  shops  in  France,  as  far  back  as  1775,  small  cubes  of  indiarubber 
could  be  obtained,  which  were  for  the  nonce  called  peaux  de  negres  (niggers'  skins), 
but  in  England  the  name  indiarubber  has  been  definitely  retained.  1780. — The 
experiments  of  Bernard,  a  French  chemist,  completed  the  work  of  Macquer  and 
Herissant,  and  forecasted  the  numerous  applications  which  could  one  day  be  made 
of  indiarubber.  Between  times,  Faujas  de  St.  Fond  occupied  himself  with  a  sort 
of  bitumen  found  in  the  mines  of  Castleton  (Derbyshire),  and  which  he  did  not 
hesitate  to  term  mineral  caoutchouc, 

1780-1820. — Fourcroy  (1735-1809),  like  He'rissant  and  Macquer,'  acted  on 
rubber  with  ether  and  caused  it  to  swell  therein.  Berthollet  (1748-1822) 
and  Giobert  also  studied  indiarubber,  whilst  Grossart  made  known  the  most 
convenient  way  for  making,  from  the  Brazilian  indiarubber,  bottles,  and  all  the 
tubes  and  other  articles  which  are  required  not  only  for  physical  or  surgical 
purposes,  but  also  for  domestic  use.  In  order  to  prepare  small  tubes,  he  cut  the 
bottles  into  thin  narrow  strips  of  the  most  suitable  shape,  and  after  they  had  been 
softened  and  become  swollen,  by  having  been  immersed  in  ether  for  half  an  hour, 
or  a  little  longer  in  essential  oil,  he  rolled  the  strip  on  a  mandrel,  and  pressed  the 
substance  strongly  by  means  of  a  bandage  twisted  into  a  spiral.  In  drying,  the 
surfaces  amalgamated,  and  the  objects  so  prepared  preserved  the  form  which  had 
been  given  to  them.  Payen  gives  a  somewhat  different  account  of  the  way  in 
which  Grossart  made  his  tubes.  The  cut  strips  were  twisted  into  a  helix  and 
moulded  on  to  slightly  conical  glass  tubes.  These  were  rendered  durable  and 
uniformly  flexible  by  applying  them  as  an  envelope  round  brass  or  steel  springs, 
termed  bretelles.  We  shall  only  cite  in  passing  the  attempts — more  or  less  fortunate 
— of  Charles  the  physicist,  in  1785,  to  coat  his  aerostat  with  rubber  dissolved  in 
turpentine  (spirit),  of  Besson  (1791-93),  of  Johnson  (1797),  of  Champion  (1811), 
of  Clark  (1815),  for  rendering  clothing  waterproof  by  solutions  of  indiarubber,  and 
finally  arrive  at  the  year  1820,  which  gave  birth  in  real  earnest  to  the  indiarubber 
industry. 

1820. — The  English  mechanic  Nadier  discovered  at  this  time  the  means  by  which 
indiarubber  could  be  cut  into  thread,  and  to  make  from  it  articles  in  common 
use  and  elastic  fabrics,  to  replace  advantageously  the  brass  wire  rolled  in  spirals. 
In  this  year  James  Hancock  established  in  England  the  first  rubber  manufactory. 

1823. — Mackintosh  discovered  and  applied  a  solution  of  indiarubber  in  coal-tar 

1  From  1736  till  1770  it  appears  to  have  been  a  mere  curiosity.  In  that  year  it  was 
introduced  to  the  British  public  for  the  purpose  to  which  it  was  long  almost  exclusively 
devoted,  and  from  which  it  has  derived  its  familiar  name.  In  the  preface  to  a  book  on 
perspective,  published  in  that  year,  the  following  interesting  passage  occurs  :  "  Since  this  work 
was  printed  off,  I  have  seen  a  substance  (no  name  is  given  to  it)  excellently  adapted  to  the 
purpose  of  wiping  from  paper  the  marks  of  a  black-lead  pencil.  It  must,  therefore,  be  of 
singular  use  to  those  who  practise  drawing.  It  is  sold  by  Mr.  Nairne,  mathematical  instrument 
maker,  opposite  the  Royal  Exchange.  He  sells  a  cubical  piece  of  about  half  an  inch  for  three 
shillings,  and  lie  says  it  will  last  for  several  years."  Translator's  note  to  2nd  English  Edition. 

8  Bone  naphtha. 


HISTORICAL    INTRODUCTION  9 

naphtha,  itinl    t!iu>   created    tin-  \\aterproof   ^.milt-lit   in. lu-try  \\hirh  t<.nk  the   name 
of  the  inventor.      lleitholer  of  Vienna  mad.-  >imultaneot. 

Hut  tin-  ose  <>f  bdiarubber  presented  numerous  ditli.-ulti.-  ;  the  MI  I, stance  wa> 
wery  easy  to  manipulate,  required  special  plant,  and  the  methods  adopted  for  effect- 
ing solution— .still  imj>erfect — rendered  it  difficult    to   impart  to  in«liarubU-r  ait 

any  \\ell  deterinineil  shape. 

1880.     Almiit  1830  Rattier  and  Ouibal  applied  the  property  of  the  non-ex- 
tensibility  of   rubber  stretched  in  the  cold  to  weave  indiarubber  thread-  /in  i-haiii)  ; 
they  made   lace-  \\hidi,  heated  to  40°  C.,  contracted    and  resumed  their  prim: 
elasticity.       Very   excellent  re    produced    in    this  way,    but   liable  to  harden 

in  c<.ld   \\eather.      The  first    1'rench  rubber  factory  was  established  at  Clermont 
l-Vrraud  in  1830. 

I  >."»»;.-  -These  i.l»tacles  \\ere  surmounted  in  the  end  of  \*'M'<,  \\ln-n  it  irtl  found, 
in  consequence  <>f  the  researches  of  Thomas  Hancock  in  KniHand  and  ( 'hafle  in 
America,  that  indiarubber  cut  into  small  strips,  or  shredded  and  submitted  to 
energetic  kneading  uiuler  the  influence  of  a  moderate  heat,  could  be  reduced  into 
thick  masses,  that  its  elasticity  could  for  the  moment  be  suppressed,  and  that,  in 
this  state,  it  was  capable  of  assuming  whatever  form  was  desired  to  be  impressed 
upon  it.  The  manufacture  of  indiarubber  articles  of  daily  use  was  henceforth  a 
solved  problem  ;  the  discoveries  of  Rattier,  Guibal,  Aubert,  and  Gerard  succeeded 
each  other  rapidly,  and  caused  the  industry  to  make  remarkable  progress.  Bernard 
used  the  heavy  oils  from  rubber  distillation  in  varnish  making,  and  Nikel  of  Vienna 
first  produced  laminated  sheets. 

Vulcanisation. — This  progress,  however  important,  would  have  remained  barren. 
and  the  very  existence  of  the  new  industry  would  have  been  in  peril,  without  on» 
of  those  opportune  inventions  of  which  last  century  furnished  so  many  notable 
examples.  Indiarubber  goods  are  subject,  without  exception,  to  a  great  defect 
proceed  ing  from  the  deterioration  of  their  elasticity  under  diflcivnt  circumstances 
and  conditions.  In  fact,  indiarubber  is  very  elastic  at  the  ordinary  temperature  ; 
it  is  so  to  such  an  extent  that  a  thread  may  by  a  pulling  force  be  stretched  to 
five  or  six  times  its  original  length,  to  resume  its  natural  length  if  the  cause  which 
produced  the  elongation  ceases  to  act.  Cold  causes  it  to  lose  this  property:  it 
becomes  hard,  and  if  it  be  attempted  to  elongate  it  in  this  condition,  it  break-.  In 
the  heat  of  summer,  or  under  the  influence  of  artificial  heat,  the  elasticity  is  restored 
But  natural  indiarubber,  besides  its  impermeability  and  elasticity,  possesses  a  \ 
energetic  adhesive  property,  especially  in  contact  with  itself.  This  pro}*-rty, 
tit  disable  for  indefinite  elongation  of  threads  and  sheets,  for  example,  is  extremely 
injurious  in  the  manufacture  of  certain  articles.  In  the  heat  of  summer  this 
adhesiveness  is  still  further  accentuated  ;  the  indiarubber  becomes  tacky  and  pitchy, 
whilst  at  the  same  time  it  gives  off  a  very  disagreeable  smell.  The  grave  nature 
of  the  defects  of  crude  indiarubber  will  be  better  understood  from  a  iV\\  examples. 
One  of  the  first  industrial  applications  of  indiarubber,  a.s  has  IK.H.MI  already 
mentioned,  was  the  waterproofing  of  garments.  Though  excellent  against  rain,  these 
garments  split  and  broke  under  the  influence  of  cold,  however  feeble  its  intensity  . 
they  became  viscous,  and  in  summer,  on  the  other  hand,  under  the  action  of  the 
sun's  rays,  they  became  tacky.  It  was  the  same  with  indiarubber  shoes,  golothe*, 
.ft u tin-*  iinfi'/i.t.  which,  whilst  they  were  not  very  graceful  in  shajH-,  \\ere  at  tir-t 
well  patronised  by  European  fashion.  But  very  soon  the  consumer  did  not  want 
any  more  of  them  at  any  price.  Mm'kiiit<i*lw9y  as  then  made,  shared  tin- 
same  fate. 

1832. — Going  back  a  little  to  pick  up  the  thread  of  the  history  of  vitlcanitatio*, 
the  German  chemist  Ludersdorf,  famous  for  his  alcohol  vaj>our  lamp,  was  the  first, 
in  1832,  to  observe  that  sulphur  removed  the  viscosity  of  indiarubber  dissolved 
in  spirits  of  turpentine.  He  afterwards  claimed  the  discovery  of  vulcanisation. 

1839.— The  Hayward  patent,  taken  out  by  Goodyear  on  24th  February 
1839,  pointed  out  the  changes  induced  in  indiarubU-r  under  the  action  «»f  >nlplmr. 
but  it  indicated  neither  the  proportions  nor  the  temperature.-  under  \\hich  the  reaction 


10  INDIARUBBER 

is  rationally  conducted.  Flowers  of  sulphur  was  used  to  dust  over  sheet-rubber 
and  thus  attenuate  the  clammy  adherence  of  the  gum. 

1844. — Goodyear,  who  seems  to  have  been  the  prime  mover  in  the  Hay  ward 
patent,  seems  to  have  been  somewhat  dilatory  in  following  the  matter  up.  But  in 
1844  he  described  how  he  had  solved  definitely,  in  1839,  the  question  of  the 
industrial  production  of  an  indiarubber  neither  brittle  at  low  temperatures  nor 
tacky  at  high  temperatures.  He  described  the  properties  which  sulphur  imparted  to 
rubber  by  combining  therewith,  and  the  process  was  henceforth  known  as  vulcanisa- 
tion. Goodyear's  discovery  consisted  in  submitting  natural  indiarubber,  first  to  the 
action  of  sulphur  and  then  to  that  of  rather  a  high  temperature.  The  term 
vulcanisation  was  given  to  this  process,  and  the  indiarubber  so  treated  was  termed 
vulcanised  indiarubber.  Vulcanised  indiarubber  preserves  its  elasticity  at  a  low  as 
well  as  at  a  high  temperature  up  to  120°  C.  (248°  F.);  moreover,  it  resists  better 
the  action  of  chemical  reagents.  Vulcanisation  gave  an  impetus  and  development 
to  the  indiarubber  industry  that  henceforth  had  no  bounds,  and,  during  a  period 
of  twenty  successive  years,  each  day  brought  its  contingent  of  discoveries  and  im- 
provements in  the  new  industry,  which  had  just  made  its  exit  from  the  embryonic 
stage  of  development.  If  Goodyear  patented  his  process  of  vulcanisation  by 
mechanical  mixture,  his  fortunate  and  very  inventive  rival,  Hancock,  took  out  a 
patent  in  1844  for  vulcanisation  in  a  sulphur  bath.  Parkes,  the  chemist  who 
in  1843  had  already  discovered  a  better  process  of  dissolving  indiarubber  by  a  new 
vehicle,  carbon  disulphide,  patented  in  his  turn  a  method  of  vulcanisation  called  the 
steeping  or  immersion  method  (au  trempe),  or  vulcanisation  in  a  bath  of  chloride 
of  sulphur.  We  owe  to  the  same  chemist  the  first  process  for  desulphurising 
vulcanised  indiarubber  waste.  Peroncel  and  several  other  manufacturers  improved 
the  sulphur  chloride  process  by  applying  it  to  the  manufacture  of  a  whole  host 
of  products  used  in  the  industrial  arts,  surgery,  and  domestic  economy.  Guibal 
made  by  the  aid  of  talc  and  indiarubber,  mixed  into  a  paste,  a  cylinder  from  which 
thick  rings  were  cut.  The  first  vulcanised  rubber  boots  were  made  at  Vienna  by 
Reithofer  in  1850. 

Austin  H.  Day  took  out  a  patent  in  1858  for  improved  vulcanisation,  and 
Gerard  proposed  the  alkaline  sulphides  for  the  vulcanisation  of  thin  objects. 
Finally,  the  series  of  grand  discoveries  terminates  in  the  invention  of  hardened 
rubber  or  ebonite,  likewise  due  to  Goodyear.  This  indefatigable  investigator  was 
able  by  a  more  energetic  treatment  of  the  indiarubber,  by  means  of  sulphur,  to 
transform  it  into  a  horny  mass  analogous  to  whalebone  and  even  to  ivory. 

Hancock's  patent. — Up  to  this  point  no  mention  has  been  made  of  the  patent 
taken  out  by  Hancock  in  1846  for  moulding  objects  in  caoutchouc,  an  invention 
which  was  the  starting-point  of  solid  moulds,  buffers  for  railway  rolling  stock,  etc., 
valves,  engine  and  machinery  belts,  then  of  hollow  moulds  (toys,  etc.).  These  are 
important  advances  without  doubt,  but  not  indispensable  to  the  forward  march  of 
an  industry  which  has  created  itself  all  in  one  piece,  so  to  speak,  and  which 
certainly  has  not  had  its  last  say. 

Later  researches,  developments,  and  improvements  are  fully  described  in  the 
sequel.  These  at  the  present  day  all  tend  towards  scientific  tapping  and  the 
production  of  pure  well-coagulated  rubber,  thoroughly  washed  and  dried,  in  one 
word,  cured  on  the  spot  by  the  planter  in  the  most  rapid,  thorough,  and  effective 
manner  possible.  But  what  gave  to  the  indiarubber  industry  the  greatest  impetus 
it  ever  received,  was  undoubtedly  the  re-invention  by  Dunlop  of  the  pneumatic  tyre 
previously  suggested  by  Thomson,  the  forerunner  of  all  the  tyres  now  used  so 
extensively  in  many  branches  of  locomotion. 


OH  A  1'Tl.i;    I 

INDIARUBBER,  LATEX;  DEFINITIONS;   I.  A  Th  1 1  I.|;<  )US 
VESSELS;  BOTANICAL  olMCIN,    HAIJITATs 

ANONYMS. —  Knglish,     A'A />•//,•,      /;„,„      Kl.isti,-,     C,in,it,-lti,m- :      Latin.      (, 

/•/A/A-///-,////  ;     r'n-m-h,     1.,     (',!<,, //, •/<,,,/<•.    (,'',111111''     A'A/.xV /.///».    Unuuii'  :    (  iernian, 
fin  in  mi;   Spanish,  Nr  /•/////./;    1'ortugii'  ,/»/./. 

Definition.  —  Indiarul.her  is  a  hydrocarbide1  of  vegetable  origin,  extiaeted  ii.,m 
the    juice    secreted   by  the    protoplasm    of    a    so-called    primordial    eellular   ti 
of   a   great   number   of   trees,  shrubs,   and    vines,  climbers  or  bind  hot 

countries.  The  principal  vessels  of  this  tissue  are  situated  in  the  inner  lav 
tin-  bark,  outside  the  liber  bundles  and  their  sclero.se  sln-ath  (when  it  exist*). 
They  send  out  numerous  branches,  some  outwards,  across  the  bark  to  the  epidermis, 
where  they  terminate  in  a  *•///  de  sac;  the  others,  less  numerous  towards  tin- 
interior,  cross  the  endodennis  and  the  medullary  rays  to  the  pith,  around 
tin-  periphery  of  which  they  diverge  longitudinally.  This  carbide  of  hydrogen  ' 
and  its  derivatives,  the  issue  of  the  activity  of  the  protoplasm,  would  not 
appear,  at  least  according  to  certain  naturalists,  to  be  afterwards  employed  in 
the  life  of  the  plant,  and  it  is  considered  by  them  as  a  product  of  elimination,  a 
reserve  product,  utilised  by  man  in  the  arts  and  industries.  Other  men  of  MMH06, 
with  whom  we  more  readily  agree,  consider  this  carbide  necessary,  at  least  partially, 
to  the  life  of  the  plant. 

The  Latex. — If   an    incision  be   made  on   rubber-bearing  plants,  there  flows 
from  it  a  milky  juice,  having  some  resemblance  to  the  milk  of  the  goat;  the  / 
collected  therefrom,  under  suitable  manipulation,  abandons  its  sus^-nded   micro- 
scopical globules  to  form  a  more  or  less  white  solid  matter,  which  is  Midi 
These  globules  have  a  diameter  of  not  more  than  two  to  three  niieromillimetrep2 
(Adriani).     Where  the  latex   is  abandoned  to  itself,  the  globules  gradually  separate 
from  the  aqueous  liquid,  and  form    a    true    en-am     on    the    surface.      In    narrow 
vessels,  they  aggregate    into  flakes,   distributed    through    the    whole  liquid.     Tin- 
properties  of  latex  may  be  summed  up  thus :  it  p  -he  den-ity  of  cream.  i> 
>lightly  amber-coloured,  mixes  with  water,  but  not  with  naphtha  or  any  other  >oh 
of  indiarubber.      Its    specific    gravity   varies    between    l'0'2  and    I'll,   whiUt   that 
of   caoutchouc    is    0'930.     In  regardi   to  its  percentage  of  pure  rubber,  it   \ari.- 
considerably;  the  typical  latex,  that  of  Para  (Brazil),  is  composed  as 

TABLE  I. — TYPICAL  ANALYSIS  OF  l'.\i:\   LATEX. 


Percent 

Pure  incliarnbher  

32 

Albumenoid  extracts  and  mineral  \vat«-r 

12 

Water  .... 

50 

1  The  terms  i-uvlude  of  hydrogen  and  hydrocarbnlr  show  the  dinvt  n-lutiu-i.sliip  of  this  class 
of  compounds  to  the  metallic  carbides  better  than  the  misleading  ti-rni 
-  A  iniiToniillimetre^tbe  thousandth  part  of  a  millimetre. 

11 


12  INDIARUBBER 

The  rubber-yielding  milky  juice  of  caoutchouciferous  plants  is  a  watery  fluid, 
containing  diverse  substances  in  solution,  in  which  there  are  suspended  minute 
globules  of  rubber.  The  milkiness  of  the  juice  is  due  to  the  difference  in  the  re- 
fractive power  of  the  solution  and  the  suspended  globules.  The  latex  falls  to  be 
differentiated  from  the  juice,  from  which  it  essentially  differs.  The  latex  is,  as  a 
matter  of  fact,  a  secretion  and  (some  say)  not  at  all  indispensable  to  the  well- 
being  of  the  plant.  Hence  comes  the  idea  that  the  plant  would  be  perfectly  healthy 
and  discharge  all  its  functions  normally  if  the  latex  were  collected  from  it  in  a 
rational  manner  and  by  a  system  of  tapping  which  did  not  injure  the  vegetable 
tissues  to  any  great  extent.  But,  in  any  case,  some  slight  incisions  must  be  made 
to  start  the  flow.  The  goal  at  which  we  should  aim  is  to  obtain  the  largest  flow 
of  the  best  quality  of  latex  in  the  shortest  period  of  time,  and  with  the  least  per- 
manent injury  possible  to  the  rubber-producing  tree  and  to  the  soil. 

Laticiferous  vessels. — The  system  of  laticiferous  vessels  of  caoutchouciferous 
plants  would  appear  to  G.  David  to  be  simple  isolated  cells  which  follow  the 
elongation,  and,  at  the  same  time,  send  laterally,  across  the  meatus  of  the  ambient 
tissue,  ramified  branches  which  are  prolonged  into  the  leaves.  These  branch 
laticiferous  cells  belong  not  to  a  fibro-vascular  bundle,  but  to  the  fundamental 
parenchyma.  G.  David's  observations  are  quite  in  accord  with  the  micrographical 
researches  of  Trecul,  C.  R.,  1865  (2°  Semestr.,  page  159  and  page  294).  It  is 
necessary  to  differentiate  between  the  morphological  structure  of  the  various 
systems  of  laticiferous  vessels  of  the  different  families  to  which  the  individual  india- 
rubber  plants  belong.  According  to  Sach's  Treatise  on  Botany  (Paris,  1874),  the  system 
of  laticiferous  vessels  of  the  Urticacece,  very  highly  developed  especially  in  the  Ficus, 
threads  its  way  through  the  bark,  in  the  immediate  neighbourhood  of  the  liber 
fibres ;  it  is  also  found  in  the  pith  of  the  Ficus,  never  in  the  wood.  But  these 
vessels  are  neither  so  abundant,  nor  so  decidedly  articulated,  as  in  the  Papaveracece, 
nor  so  regularly  anastomosed  in  a  network  of  narrow  meshes,  as  in  the  Chicoracece. 
They  travel  between  each  internode  of  the  stem,  side  by  side,  almost  isolated,  like 
long,  uninterrupted,  cylindrical  tubes,  which,  but  rarely,  send  out  lateral  branches, 
and  only  communicate,  here  and  there,  with  the  neighbouring  tubes.  In  the 
nodes,  on  the  contrary,  and  in  the  leaves,  they  assume  numerous  ramifications,  at 
times  anastomosed  in  a  network,  and  form  small,  fine  prolongations  terminated  in 
a  finger-stool.  In  the  thick  leaves  of  several  fig-trees  they  spread  far  through  the 
parenchyma,  and  even  come  in  direct  contact  with  the  epidermis. 

Laticiferous  vessels^  of  the  Eiiphorbiacece,  Apocynece,  and  Asdepiadece. — The 
laticiferous  vessels  of  the  Euphorbiacece  resemble  the  preceding,  in  so  far  as  they 
likewise  ramify,  and  are  abundantly  distributed  throughout  the  whole  of  the  funda- 
mental tissue,  but  they  differ  from  it  because  their  sides  are  thicker,  and  resemble, 
in  transverse  section,  the  liber  fibres ;  attaining  their  greatest  development  in  the 
neighbourhood  of  the  latter,  which  they  sometimes  entirely  replace.  From  this 
point  they  send  out  branches  into  the  bark  and  into  the  pith,  forming  numerous 
ramifications  especially  in  the  nodes  of  the  stem  and  the  armpits  of  the  leaves. 
The  laticiferous  vessels  of  the  Asclepiadece  and  the  Apocynece  have  a  still  greater 
resemblance  to  the  liber  fibres ;  like  the  latter  they  are  (1)  partly  pointed  at  the  two 
ends,  and  (2)  their  sides  are  sometimes  thickened  and  streaked  in  a  characteristic 
manner.  Sometimes  they  occupy  essentially  the  place  of  true  liber  fibres,  whilst 
on  other  occasions  they  are  united  and  mixed  with  them  in  the  liberian  bundles, 
moreover  they  sometimes  surround  them.  It  is,  therefore,  by  the .  simple  presence 
of  the  milky  juice  that  the  relationship  of  these  transformed  liber  fibres,  with  the 
true  laticiferous  vessels,  is  recognised ;  the  more  milky  their  contents,  the  thinner 
does  their  cell-wall  become.  Besides  the  simple  and  fibrous  elements,  ramified 
and  anastomosed  tubes  are  found,  which  are  more  especially  abundant  in  the  nodes, 
in  the  pith,  and  the  bark. 

Differentiation  of  rubber  from  milky  juice  of  2jlants  of  temperate  climates.— 
The  flora  of  temperate  countries  include  a  large  number  of  plants  with  a  milky 
juice,  but  these  juices  do  not  always  contain  indiarubber ;  and,  even  when  they  do 


LATEX—  DEFINITIONS,    ETC.  13 

contain  it,  it   is  too  often  pr.-,-nt   in  >neh  Hiiall  «jiuntitirs  that  it-  imli! 
would  nut   !•«•  profitable.      Tin-  m-tlles,  the  poppies,  tin-  lettuces.  i! 

tin-  tig  tree.,  etc.,  of  <•"/•   temporal    cUmak    cannot,  • 

india  rubber  \  ielding  plant-,  an.l  then-  ,-aii  !,»•  \\«  question  of  obtaining   nil. 

them     i>n    a    large    scale.       Ol'    tin-    M-M-ral    Imndivd    plant-   '-ndoNVed    with   .1    milk\ 

juic.  .  mi  more  than  fifty  contain  indiarubher  in  .Mich   a    pro|M,ition  a-  \\oul.  I 

pay  for  ill-  cost  -;  '  ctracting  it. 

Rubber-producing  <  >nly  the  tropical  ami   intertiopical   /one*,  from  the 

30°     X.     lilt,     to    tin-    •"><>      S.     lat.,    yield     plan'  nn    e'  .,n<  >ini«  al     \ahic. 

80    far  ;is    tin'  «|iie.stion  now   at    issue    is   com-crncd.      Then-,    a    \a-t    U-lt    .,f   Ian.  I, 
SOO   kilometres    (say    .',()()   mil«-s)  u  ide,  encircling  the  globe  all  round  tin-  K.JU 
fulfils  all  the  conditions    requisite    for    the     production    of    in.liarul.U-r    plant 
commercial  value.      There,  a  moist    warm  climate  piv\ail>  at  one  ami  the  >anie  time, 
The  temperature  generally  \ari.->  lY«»m  26°  to  42°  0.  (from,  8tiy,  ,«  •     I 
whilst    the  mean    a\erage   rainfall    is    L'-()(.>   metres   (say*|J    inch- 
ities  restrict    the   indiarabber  zone  to  25°  or  28°  north  and  south  «.t    the  K,ju  . 
This  zone  ia  divided  by  Drude  into  —  («/)  the  tropical  American,  including  the  \Ve«t 
Indies;  (6)  the  tropical  African,  including  Nfadagascar;  and  (<•)  the    In.l-.  Malay 
region,  including  Oceania.     The  world's  supply  of  indiarulil»er  is  draxsn  ••\<-lu- 
from  these  three  regions. 

Botanical  or  i<  i  i  u  <>f  /•//////»  i--[>r»<lnciint  ///<///^s.—  The  plants  which  yield  theindia 
ruhUer  latex  are  not  always  of  the  same  species,  nor  are  th«-y  (-\.  -n  ••!"  tin-  same 
botanical  order  over  the  whole  extent  of  the  indianil»bcr  zone.  They  U-long  to 
different  tx>tiinical  orders,  more  especially  (1)  to  the  A'//y<//"/-/,/,/,-,  //  or  spurgeworte; 
(*J)  to  the  Artocarpece  family  of  the  Urticacevn  or  nettles;  (.'>)  to  tli  I 
Or  dogbanes;  (4)  to  the  Asdepiadiacecu  ;  and  (5)  various  other  orders.  I  Jut  an 
appreciable  difference  exists  between  the  various  sjiecies  of  the  same  order,  not 
only  in  regard  to  the  quantity  but  in  an  equal  degree  to  the  quality  of  the 
indiarubber  which  they  yield.  The  indiarubber-yielding  plants  of  tropical  America 
are  chiefly  arborescent,  Hevea  Brazil  i<  '//s/x,  M«nlhot  Glaziowii,  Sapimn  i'!<il<tndu- 
/oxnni,  Castilloa  elastica,  etc.  A  few  shrubs  like  Parthenutn  ni'i/mt'ifimt, 
and  climbers  like  Fosteronia  floribunda,  also  flourish  there.  The  African  ruhlier 
industry,  including  that  of  Madagascar,  depends  mainly  on  climber-  (\in.-s),  or 
as  the  French  term  them,  lianes.  Such  are  the  various  specie!  of  the  genus 
Landolphia,  Clitandria,  Carpodinus,  Cryptostegia.  But  lately  trees  indigenous 
to  Africa  have  yielded  an  appreciable  amount  of  rubber,  and  have  thus  brought  a 
notable  contingent  to  swell  the  supply  from  the  climbers.  The  rubber  of  the 
Indo-Malay  region  is  secreted  by  (1)  gigantic  trees,  Fie  tin  thixti- 
and  by  (2)  climbers,  Cryptostegia,  Willughbeia,  Urceola,  Lewcoimti*.  /'>tranun'a. 
The  characteristics  of  the  species  introduced  into  and  acclimatised  in  these  different 
zones  and  rationally  cultivated  therein  will  be  described  in  their  proper  place. 

As  will  be  seen  later  on,  the  quantity  of  commercial  Indiarabber  do. 
depend  solely  on  the  plant  producing  it.  Many  other  determining  cause* 
intervene  to  increase  or  diminish  the  production  of  the  latex,  and  to  determine  the 
production  of  superior  or  inferior  quality  latex.  Hut,  00f0f*M  j-n-ifitu,  the  most 
suiK3rior  grades  of  rubber  are  produced  from  plants  belonging  fc>  the  natural  order 
Kni>horbiacece,  the  botanical  characters  of  which  are  now  given. 


1.  NATURAL  Omn:i:  Knf,h.,,'i,i>i>\'i  (spurgeworts)  ;  tril)e 
ESSENTIAL  CHARACTER.  —  Flowers,  monoecious  or  dicecious.  Calyjr,  none,  or 
lobed,  inferior,  with  various  glandular  i»r  scaly  internal  appendage**.  Male*: 
Stamens,  definite  or  indefinite,  distinct  or  monadelphouB  ;  •//^//'/•>-.  two-celled. 
Females  :  Ovary,  su}>erior,  sessile,  or  stalked,  three  cell.-d  :  -  ./•»//..«.  solitary  «»r  twin. 
suspended  from  the  inner  angle  of  the  cell  ;  styl*-*.  tin  <  e  .  >-//,///M,  conijw.und  or  single. 
Fruit,  consisting  of  three  dehiscent  cells,  separating  with  elasticity  from  their  common 
axis.  —  Trees,  shrubs,  or  herbaceous  plant-,  often  abounding  in  acrid  milk.  Lcai**, 
opposite  or  alternate,  simple,  rarely  compound,  usually  with  stipules.  /7o»/rr», 


14 


INDIARUBBER 


axillary  or  terminal,  usually  with  bracts,  sometimes  enclosed  within  an  involucre. 
The  fruit  of- this  order  is  tricoccous,  that  is,  it  consists  of  three  carpels,  which,  when 
ripe,  separate  from  each  other  with  some  elasticity,  opening  by  the  edge  next  the 
axis ;  this,  together  with  the  unisexual  flowers,  distinctly  marks  the  order.  The 
Euphorbiace  yield  as  rubber-producing  plants  (1)  the  Hevea',  (2)  the  Micrandra ; 
(3)  the  Manihots ;  (4)  the  Euphorbia  •  (5)  Sapium.  In  addition  to  several  genera 
of  rubber  plants,  this  large  order  of  290  genera  and  2500  species  yields  such 
economic  products  as  teak,  castor  oil,  ipecacuanha,  and  tapioca. 

(1)  The  Hevea  (Figs.  1,  2,  and  3)  is  a  genus  of  the  Euphorbiacece,  tribe 
Crotonece,  which  gives  its  name  to  the  series  of  Heveas.  The  flowers,  dioecious 
and  apetalous,  have  a  five-lobed  valvular  or  subinduplicate  calyx.  The  lobes  are 
sometimes  slightly  twisted  at  the  summit.  Their  androecium  consists  of  five 


FIG.  3.—  Hevea  Braziliensis.     Flowering  Twig. 

alternisepalous  stamens;  or  six  to  ten,  on  two  alternate  whorls.  They  are 
reduced  to  extrorse,  bilocular  anthers,  dehiscent  along  the  longitudinal  slope 
[loculicidal],  and  sessile  on  a  central  stalk  ornamented  and  terminated  by  a 
sterile  gymnoecium.  The  disc,  sometimes  absent  or  rudimentary,  is  generally 
developed  round  the  base  of  this  stalk.  In  the  female  flower,  the  uniovular, 
trilocular  ovary  surrounded  by  distinct  glands,  connate,  or  sometimes  inconnate,  is 
surmounted  by  a  style  in  the  form  of  a  very  short  stalk,  which  is  terminated  by 
stigmatiferous,  fleshy,  and  bilobed  lobules.  The  fruit,  which,  according  to  Aublet, 
would  appear  to  be  edible,  is  a  three-shelled  capsule,  each  of  which  is  dehiscent 
by  means  of  two  elastic  valves.  The  exocarp,  become  fleshy  before  maturity, 
s  easily  separated  from  the  endocarp.  They  are  large  trees,  with  an  abundant 
milky  juice,  alternate  leaves,  elongated  petioles,  digitate,  on  three  sessile  or  petiolated 


LATEX — DEFINITIONS,    I 


15 


leaflets,  leather  veined  .uid  glandular  at  tin-  l..i--.  Their  flowers  are  arranged  on 
compound  racemes,  composed  of  axillary  and  terminal  cyme*.  The  central  tl<.\\.r 
of  the  cyme  i>  generally  female.  The  tree  reproduce  it^-lf  uitli  the  greatest 
of  facility;  the  envelope  \\hi.-h  contains  tin-  seed  liiuMs  with  a  nobfl  like  the 
detonation  of  a  capsule  i.f  fulminate  of  ninvin  \ ,  ami  the  seed  is  projected  in  the 
neighbourhood  tn  a  distance  of  about  .")(»  •  •.  li.-pr.Mln,  '  ,,.ft  f» 

natuiv  l,y  tin-  natives.     The  tree  is  upright,  and  grows  to  a  la!-'-  ri»  u|.  to  «;0  feet 
in  height,  with  a  conical  trunk   ('»  to  8  feet  in  circumference.     The  top  luan.li,->, 
when   th>    tiv.vs  grow  closely  together,  are  .short,  the  leaves  are  roinjNun. 
trifoliate.     The  whitish-green  flowers  are  male  and  female  in  the  same  panicle,  th«- 
female   usually   large   and   terminal.       The    fruit    i-,   ;i   large  dry  capful* 


Ki<;.  4. — Manihot  Glazowii.     Young  branch  (half  its  natural  size)  ;  inflorescence 
(half  its  natural  size) ;  half-ripe  fruit  (its  natural  size). 

of  three  one-seeded  pieces.  The  wood  is  white  and  soft,  and  forms  bad  timber. 
It  is  an  error,  which  prevailed  until  lately,  to  regard  the  Hewa  Guyanenti* 
(the  Jatropha  elastica  of  Linnaeus  and  tin*  Si f, him  in  elastica  of  Schreber)  as 
being  the  real  tree  called  Serinya  or  Cahuehu  by  the  Indians  of  Brazil,  and  as 
constituting  the  indiarubber  tree  par  excellence.  This  is  indeed  the  tree  mentioned 
by  Lacondamine,  but  it  yields  a  s« -anty  latex,  which  is  very  poor  in  resinous 
globules.  The  dry  extract  which  is  obtained  from  it  is  of  a  very  inferior  quality. 
The  hevea  which  produces  the  most  esteemed  commercial  rubber,  is  the 
Brazil  I,  v/x/x  (Muller  d'Arg.),  or  Sijth<-,,,  /;,  /  tiensi*  (H.  B.  K.). 

(2)  The  Micrandra  (Benth.)  is  a  genus  of  the  Euphorbiacc*  of  the  tribe  of 
Crotoitece,  with  monoecious  flowers,  with  valvular  or  imbricated  petaK  a  petandroos 
andrwcium,  trilocular  ovary,  the  fruit  opening  tardily  or  scarcely.  They  coi 


16 


INDIARUBBER 


three  or  four  species  of  trees,  with  alternate  leaves,  which  came  originally  from 
Brazil.  Their  latex  is  said  to  contribute  its  contingent  to  the  supply  of  Ama/on 
rubber. 

(3)  The  Manihots  (Plum-Adams). — A  detached  species  of  the  Crot«nt:n.  »\ 
which  it  possesses  the  characteristics  with  male  decandrous  flowers,  if  its  perianth 
be  not  unique,  gamophyllous,  with  five  short  divisions  with  a  large  disc  in  bisexual 
flowers.  They  consist  of  about  seventy-five  American  herbs  or  shrubs,  with 
alternate  leaves,  digitate  lobed,  or  partite.  Their  root  is  often  swollen  and  rich  in 
starch.  The  Manihot  Glazowii  (Fig.  4)  or  leitera  yields  the  Ceara  Scraps  of 
commerce  or  the  Manisoba  of  the  natives ;  it  is  the  indiarubber  tree  of  granitic 
land,  high  and  dry,  just  as  the  hevea  is  the  indiarubber  tree  of  low-lying,  well- 


FIG.  5. — Castilloa  clastica.     Male  flower-bearing  branch. 


watered  ground,  of  which  a  clay,  rich  in  vegetable  mould,  constitutes  the  principal 
essential. 

2.  NATURAL  ORDER  Urticacece,  or  nettle  family. — The  natural  order  is  too 
well  known  to  need  any  botanical  description  here.  It  supplies  as  rubber-producing 
plants  (1)  the  Castilloa-  (2)  the  Ficus -,  (3)  the  Artocarpus;  (4)  the  Acropia. 

(1)  The  Castilloa  (Fig.  5)  is  a  genus  of  the  Urticacece,  tribe  Artocarpece,  whose 
monoecious  flowers,  very  analogous  to  those  of  the  pseudolmedia,  are  united  on  dis- 
tinct capitula,  almost  flat,  or  induplicated,  reniform,  and  surrounded  by  numerous 
imbricated  bracts,  constituting  an  involucre.  The  males,  consisting  of  numerous 
stamens,  have  no  perianth.  The  female  flowers  unite  in  numerous  glomerules,  on 
a  common  receptacle.  They  possess  a  calyx  with  four  divisions,  a  semi-inferior, 
uniovular  ovary,  surmounted  by  a  thin  cylindrical  style,  and  divided  at  the  summit 


LATEX  —  DEFINITIONS,    I   1C.  17 


into  two  stigmatiferons,  linear,  ;i\\l  sha|H-d,  compressed,  and  KNnetimei 
branches.      Tin-    fruit  is  a  drupe,   which  is  almost  dry  at   maturity,   adhering  on 
MM   ^ide,  to  the  calyx,  and  containing  an  exalbuminous  seed.  with  a  - 
embryo  with  thick,  almost  equal  cotyledons,  and  a  short 

tier  with  a  milky  juice,  generally  pubescent,  with  distichous  leaves,  unequal  at 
the  base,  and  accompanied  by  supra  a\illar\  ami  acute  oblong  connate  stipule*  with 
unisexual,  axillary  stipite,  fasciculated,  rarely  numerous,  often  military  inflorescences. 
(2)  The  /Yo/.s-  (  Fig.  6),  a  genus  ,,f  the  Urticactn  <  snUnler  A  rtocarpece,  character- 
ised by  uni  wcrs,  contained  in  a  globular  or  pear-shaped  receptacle  more  or 

less  .,],,  n  at  the  summit.  The  male  ami  female  flowers,  agglomerated  together, 
sometimes  exist  together  simultaneously  in  the  -ame  receptacle,  and,  in  *\H-\I  .1 
case,  the  males  occupy  the  iij»|K-r  |>arl  ;  more  generally.  ho\\e\.-r,  the  80X68  are 
place,!  in  separate  receptael.-s.  The  calyx  is  formed  of  two  to  six  leaflets.  and  i* 
often  Meshy,  four  to  six  stamens,  opposite  the  .sepaU,  ,,r  .sometimes  only  one  stamen 
(//ms//V///</f)  or  two  stamens  (yi//»//-//Mfo.s-//«-.//  »  ;  the  pistils  an-  In  ......  eonnate  at  the 


FIG.  6. — Ficus  clastica.     Branch. 

base;  the  anthers  are  introrse,  with  two  longitudinal  sutures;  ovary  sessile  or 
stipite  generally  unilocular,  very  rare  bi-  or  trilocular,  sunnounted  by  a  style, 
inserted  laterally,  enclosed  in  the  receptacle,  with  a  stigmatic  infumlibuliform  or 
bifid  surface.  Ovule  descending,  anatropous,  or  campylotropous,  with  micropyle 
superior  and  turned  outwards.  Fruits,  drupaceous,  contained  in  a  closed  receptacle  ; 
mesocarp  thin,  membranous,  often  decidedly  awanting ;  kernel  crnstaceous  or 
fragile,  with  a  single  descending  seed,  provided  with  a  Meshy  albumen.  The 
various  kinds  of  Ficus  are  large  trees  or  shrubs,  and  sometimes  climbing  plants, 
latescent,  generally  with  alternate,  rarely  opi^site,  leaves,  very  variable  in  form  in 
even  a  single  secies,  entire  or  lobed,  persistent  or  caducous,  accompanied  by  broad 
stipules  which  at  first  envelop  the  terminal  buds,  and  become  detac lied  often  \ery 
promptly.  The  inMorescences  are  axillary,  solitary,  or  fasciculated,  or,  more  rarely, 
arranged  in  terminal  spikes  or  clusters.  The  genii. s  /  is  one  of  the  most 
important  of  the  vegetable  kingdom, — more  than  Go< ' 
over  all  the  regions  of  the  globe  ;  but  it  is  principally  in  the  Malay  islands  and 


18 


INDIARUBBER 


the  islands  of  the  Pacific  Ocean  that  the  species  attains  its  maximum  development. 
The  Castilloa  being  the  indiarubber  tree  par  excellence  of  Mexico  and  Central 
America,  the  Ficus  is  more  especially  the  indiarubber  tree  of  Eastern  Asia  and 
Oceania.  It  is  only  occasionally  met  with  in  Africa  and  America.  One  of  the 
varieties  of  Ficus  is  very  familiar  to  us  in  Europe,  where,  under  the  name  of  india- 
rubber  plant,  it  constitutes  one  of  the  ornamental  plants  of  our  hothouses, 
gardens,  and  apartments.  In  order  to  thrive  in  our  climate,  this  plant  requires  a 
moderate  hothouse  temperature,  or  simply  that  of  the  orangerie,  and  it  can  very- 
well  pass  part  of  the  year  in  the  open  air ;  it  is  brought  indoors  before  the  first 
frosts.  Cultivated  in  pots,  it  preserves  its  lustre  for  a  long  time;  in  order  to 
revivify  it  when  weak,  or  to  cause  it  to  develop  better,  it  is  transplanted  to  the 
ground  itself  in  an  open-air  greenhouse.  Propagation  is  easy,  and  is  done  in 
mould  or  loam,  under  a  hotbed,  beneath  a  bell  glass,  by  means  of  slips,  cuttings, 
or  branches,  bearing  two  or  three  leaves,  or  even  one  only  and  provided  with  at 
least  one  bud.  A  light,  substantial  soil,  rich  in  mould,  kept  very  fresh  during  the 
period  of  vegetation,  is  that  suitable  for  indiarubber. 

(3)  The  Artocarpus  (Figs.  7  and  8)  (Lin.  apros  tree,  Kapiros  fruit,  bread-tree). — 
A  genus  of  Urticacece,  which  gives  its  name,  to  the  series  of  Artocarpece,  described 
by  several  authors  as  a  distinct  family,  under  the  name  of  Artocarpacece.  Its 


FIG.  7. — Artocarpus  ii 


Flowering  branch  and  fruit. 


flowers  are  monoecious.  The  male  flowers  have  a  more  or  less  deep  and  imbricated 
two  to  four-lobed  calyx,  a  single  stamen  with  a  central  smooth  pistil  and  smooth 
anther,  bilocular  and  dehiscent  by  two  sutures.  The  female  flowers  have  a  tubular 
receptacle,  very  concave,  dug  like  a  well  on  the  common  receptacle  of  the  inflor- 
escence, the  sides  of  which  bear  a  gamophyllous  perianth,  sometimes  at  the  summit, 
whilst  in  the  bottom  a  sessile  or  short  stipite  ovary  is  inserted,  free,  and  surmounted 
by  a  lateral  or  central  style,  enclosed  or  exposed,  simple  or  two  to  three-lobed  at 
its  stigmatic  extremity.  This  ovary  is,  originally,  bi-  or  trilocular,  the  only  one 
itent  division  of  which  in  the  adult  stage  contains  in  its  internal  angle  a  thick 
placenta,  on  which  is  inserted  a  descending  anatropous  ovule,  with  the  micropyle 
superior,  exterior,  and  often  covered  by  an  obturator.  At  maturity  each  ovary  becomes 
an  achene,  the  descending  seed  of  which  contains  under  its  integuments  a  curved, 
exalbummous  embryo,  generally  with  very  unequal  cotyledons.  The  aggregate  of 
these  achenes,  enclosed  in  the  mass  of  the  receptacle,  which  often  becomes 


LATEX — DEFINITIONS,    1 


19 


rtarchy,  constitutes  a  compound  spherical  or  oblong  fndl      •  .  .N|.|  -j^ei«i  of 

//•/»//.<  knou  n  iii  A-ia  and  (  >r> Mhi.i,  «.nl\  tivi-  an-  •  •..imiH-ivially  imjmrtant  in  India. 
Tli.-\  an  trees  with  ;i  milky  juir,-,  ^<>\i   \\. •.,.!.  ahi-ni.it.-  i-ntiiv  l.-av.-~. 

.-tit.  and    accompanied    l.y    t\\o    lateral    « nat<-    -ti|.nl«->    in    a    lu-naul,    siijiru  axil!  u  \ 

-li.-ath   which  envelope  the  yOUUg  l»ran«-li,  ami    l»-a\r-,  alt.-r    it  !',    a    lim-ar 

annular  riratri«-r.      Tin-    MO\MT-   an-   arraiiu'fl  in  g\n\nt -rules  in  dj-tim-t    n-n-| •• 
that  «>t    thr    mal">  in    thr    !'«»rm  «•!'   a  rvlimlriral  «»r  rla\  it'..i  in  -pikr.  t'lirnitliril,  nn  its 
•  •xtt-ri'.r   Hiirface,    \\ith    si-ssiK-    tl.. \M-I-..    ^.Mu-rally    Mitri-min^'lnl    \\ith    JK-!I 
wliil>t    tin-    t'i-mal«-N   arc   ,u  ran-t- I,    in    the    i.-r.-pta.-!,-,    in    tin-   «li-j.r«-->i«.n 


I-'H;.  s. 

ItN  vi.M-i.iisJatcM-rnt  latex  is  nsi-.l  l.y  tin-  Indian-  \n  make  l.inl-liim-.  I'.ut 
it  i-  >^|,rrially  valued  on  account  of  its  fruit  in  Oceania  (Taith.  It  is  a  live  which 
may  rise  to  a  height  of  50  to  80  feet,  with  a  trunk  as  large  as  a  man'.-  l>ody. 

(4)  The  Cecrojtia  (Lu-H.).—  (Jenus  <»f  Uriicacea^  lielonging  to  the  family  of 
''"//"  •• /.It <tle<x,  distinguished  liy  its  din-cimis  tl«»\ver^  in  very  «len-«-  -j.ikes.  IVrianth 
of  the  male  flowers,  o|>en  at  the  summit  l>y  tw<»  JMUVS:  Mamrns  two,  exser 
short  filiform  filaments  with  biloe.ular  anthers;  jK-rianth  of  the  female  flowers, 
tuluilar.  t-ntire,  or  almost  entire,  slightly  thickened  at  the  summit.  Ovary  free, 
unilocular ;  terminal  stigma,  suKsessik-  eapitulum.  MEonoepermOOfl  aclu-ne,  re- 
covered l.y  the  j.er>i-tent  j.erianth.  Ovules  inserted  on  the  summit  ««f  th-- 
dissepiment  descendant,  with  a  micropyle  directed  aln>ve  and  outwards.  Seeds 


20  INDIARUBBER 

numerous.     A  tree  with  knotty  branches,  fistulent  in  the  internodes,   alternate 
palma-bilobed  leaves.     Habitat. — Central  and  Equatorial  America. 

3.  NATURAL  ORDER  Apocynacece  (dogbanes).  —  ESSENTIAL  CHARACTER.  — 
Calyx,  divided  into  five,  persistent.  Corolla,  monopetalous,  hypogynous,  regular, 
five-lobed,  with  contorted  aestivation  deciduous.  Stamens  five,  arising  from  the 
corolla;  filaments,  distinct;  anthers,  two-celled,  opening  lengthwise;  pollen, 
granular,  globose,  three-lobed,  immediately  applied  to  the  stigma.  Ovaries,  two, 
polyspermous ;  styles,  two ;  stigma,  one.  Fruit,  a  double  follicle.  Trees  or  shrubs, 
usually  milky.  Leaves,  opposite,  sometimes  whorled,  seldom  scattered,  quite  entire, 
often  having  ciliae  or  glands  upon  the  petioles,  but  with  no  stipules.  They  are 
readily  known  by  their  opposite  leaves,  and  bifollicular  fruit,  from  all  orders  except 
Asclepiadacecu ;  and  from  that  order  by  their  separate  anthers  having  powdery  pollen. 
The  Periwinkles,  Vinca  major  and  minor,  common  trailing  shrubby  evergreens,  and 
an  Apocynum  or  two,  are  the  plants  of  this  order  which  inhabit  Europe. 

But  the  Apocynece  or  Dogbanes,  noted  in  tropical  Africa  for  valuable  rubber- 
yielding  species,  yield  the  Vahea,  the  Landolphia,  Funtumia,  Mascarenhesia, 
Clitandra,  Carpodinus,  and  amongst  other  genera  in  various  parts  of  the  tropics 
noted  for  their  rubber  are  the  Urceola,  Dijera,  Hancornias,  Camcraria,  Parameira, 
Leuconotis,  Anodendron,  Alstonia,  Chenomorpha,  Xylinabaria,  Talerncemontana, 


FIG.  9.—  Vahea.     Entire  fruit  and  longitudinal  sections. 

Willughbeia,  Hymenelopus,  Diplorhynchus,  Fosteronia,  Ecdysanthera,  Micrechites. 
etc. 

(1)  The  Vahea  (Fig.  9),  a  genus  of  Apocynaceoe-crotonece,  formed  by  some  twenty 
climbers  of  Central  Africa  and  Madagascar,  distinguished  by  terminal  cymes  with 
corolla  flowers  bearing  the  stamens  near  the  base  of  the  tube,  the  divisions  of  the 
limb  narrow  ;  fruit,  a  large  bay  with  numerous  angular  seeds,  the  albumen  of  which 
is  horny  (see  Landolphia). 

(2)  The  Camcraria  (Muller).— A  genus  of  Apocynacece,  of  the  series  of  the 
Plumemcce,  sub-section  of  the  Euplumeriece,  distinguished  by  the  absence  of  a  disc 

its  flower,  and  by  its  stamens,  the  anther  of  which  is  surmounted  by  a  long 

The  two  carpels  enclose  numerous  ovules,  arranged  in  twos,  in    their 

ovarian  portion ;  ripe  they  become  two  indehiscent,  top- winged,  hardened  samaras. 

They  are  West  Indian  glabrous  shrubs  with  opposite  leaves,  and  flowers  in  terminal 

cymes.     The  C.  lucida  et  latifolia  (Jack)  yields  indiarubber. 

(3)  The  Parameria  (Benth.).— Genus  of  Apocynacece,  allied  to  the  Ecdysan- 
therece,  distinguished  by  a  calyx  with  several  interior  glands,  a  five-lobed  corolla, 

J  lobes  covering  over,  by  their  left  end,  the  elongated  fruits,  swollen   to  the 

utmost  with  seed.     It  consists  of  two  or  three  vines  of  tropical  Asia  and  Oceania. 

Ve  nave,  provisionally,  named  a  Cambodian  species  which  yields  excellent  india- 

ber,   P.  Pierrei.—P.   Glandulifora,  often    confused    with    Willughbeia  edulis, 


LATEX— DEFINITIONS,    ETC.  1' 1 

U  a  large  climbing  evergreen  shrub  of  tin-  l..,rd,-rs  of  the  tidal  I'.inMs  of  Tenaftterim 
and  Andaman    I 

The   Leuconotit   (Jack)     (ienu  //HOCM*,  o  lutasrent 

*hrul»  of   tin-    Mala\   Aivhi|N-l;igo.  di>tingui>hed    l.y  four   primitm-   flowers,  with   .1 
bilocular  ovary,  the  disse|.imeni>  containing  two  OVnJeti      The   fruit    i>   tl.-l:  . 

••eda  are  exallniminous      /.  eon    Hhrub, 

of    IVnang.     Mala\     I'eninsula,    Sumatra,    BomeO,    with    -inooth    |,.irk.    l.-.t\. 

l»ro\\n  ai>o\e,  paler  beneath,  yellow  l>ro\\ii  minutely  dott«-«i.  \\::i,  -trong  horizontal 
nerves,   fruit   the   >i/,-  of  a  gooseberry,  furnishes  some  of  the  Straits 
rubber  known  as  gn-grip  sundik  (Ridley)  which,  with  that  from  /,.  Anrr/»*<t(  IWnco, 
.   |M.or   in   Duality,  whiUt    that    tr  -  .,f  I'.oi  n,-o  j>  ,.\<-.-||,  nt.      'II,.- 

lat.-x  from   /..    Tubawni*,  liunieo,   i  an  a«lulterant. 


FIG.  10. — Landoljthia  oicaricnsis.     Branch. 

(5)  "The  Landolphia,"  says  Dewevre,  "are  all,  according  to  \\hat  we  know  up 
to  the  | »n -SIM it  day,  woody  vines,  which  climb  trees,  by  hooking  themselves  on  by 
tendrils  t«>nned  by  the  transformation  of  their  inflorescences  or  of  certain  bram-ho. 
and  by  enrolling  their  stem  round  the  sustaining  plant.  Their  maximum  height 
may  be  25  meters  (say  80  feet)  (Captain  Chaltin),  probably  even  greater;  their 
trunk  may  attain  a  thickness  of  15  centin  i\  (\  inches)  in  diameter,  and 

even  more  (L.  comoremis  [Boj.],  var.  m/fo/-/-/</.  K.  Sclium.):  I  have  never  seen 
trunks  of  that  size,  but  I  have  examined,  at  Berlin,  portions  of  vines  having 
a  diameter  of  5  centimeters  (2  inches)."  I  cannot,  moreover,  give  a  better  idea 
of  the  appearance  and  manner  of  life  of  these  vegetables,  than  by  transcribing  a 
l-aoa^e  of  R.  P.  Merlon  relative  to  the  //.  comorensi*  (Boj.),  var.  flarid<i,  K. 
Sdmm.,  which  he  calls  the  vegetable  boa:  ''Trailing  its  trunk  on  the  ground. 
stripped  underneath,  gliding  across  all  the  thorns,  running  with  enormou*  I 


22  INDIARUBBER 

over  the  footpaths  of  the  deer,  circumventing  the  rocks,  shooting  towards  the 
large  trees,  which  it  inlaces,  throwing  its  bridges  of  verdure  and  its  dark  assemblage 
of  branches  from  one  bank  of  the  streams  of  water  to  the  other,  redescending 
to  the  ground  further  on,  where  it  entangles  itself  in  an  inextricable  network  of 
roots,  this  peculiar  and  wild  plant  occupies  immense  regions  in  the  mysterious 
forests  of  the  interior."  l 

Stem. — The  stem,  of  a  brown  or  greyish  colour,  is  generally  covered  with 
numerous  lenticells.  In  the  case  of  certain  species  (L.  comorensis  [Boj.],  K.  Schum., 
L.  senegalensis,  D.  C.)  the  stems  are  completely  glabrous,  but  in  the  majority 
brownish  downs  are  present  on  the  young  branches  (L.  Peter siana  [KL],  Th. 
Dyer,  L.  Lecomtei,  A.  Dew.,  L.  Kirkii,  Th.  Dyer,  L.  parvifolia,  K.  Schum.,  etc.), 
sometimes  even  on  old  branches  (L.  tomentosa,  A.  Dew7.,  L.  bracteata,  A.  Dew., 
etc.);  perhaps  down  is  still  present  on  even  some  of  the  adult  stems.  Leafy 
branches  start  from  the  stem  in  greater  or  less  number. 

Leaves. — The  leaves  are  opposite,  petiolated,.  usually  elliptical,  sometimes 
almost  rounded  (certain  forms  of  L.  Peter  siana  [KL],  K.  Schum.,  some  leaves  of 
L.  madagascariensis  [Boj.],  K.  Schum.),  sometimes  oval  or  oboval,  acute  at  the 
apex  (L.  Petersiana  [KL],  Th.  Dyer,  L.  parvifolia,  K.  Schum.,  L.  Kirltii,  Th. 
Dyer,  etc.),  sometimes  obtuse  (L.  comorensis  [Boj.],  L.  madagascariensis  [Boj.],  K. 
Schum.,  L  senegalensis,  D.  C.,  L.  lucida,  K.  Schum.),  or  more  or  less  rounded  (L. 
tomentosa,  A.  Dew.,  L.  Thollonii,  A.  Dew.),  rather  often  prolonged  into  a  long  or 
short  mucron,  pointed  or  rounded  [(L.  Lecomtei,  A.  Dew.,  L.  Heudelotti,  D.  C., 
L.  owariensis,  P.  D.  Beauv.,  etc.)];  the  base  is  most  frequently  cuneiform  [(L. 
Kirkii,  Th.  Dyer,  L.  Petersiana  [KL],  Th.  Dyer,  etc.)],  sometimes  more  or  less 
rounded  [(L.  comorensis  [Boj.],  K.  Schum.,  L.  bracteata,  A.  Dew.,  L.  Thollonii,  A. 
Dew.,  L.  Lecomtei,  A.  Dew.)],  rarely  cordate  [(L.  lucida,  K.  Schum.,  L.  bracteata, 
A.  Dew.)] ;  the  edges  of  the  limb  are  often  recurved  towards  the  inferior 
surface ;  the  latter  is  often  dull  and  pale,  whilst  the  upper  surface  is  lustrous  and 
deeper  in  tint.  As  a  general  rule,  these  leaves  are  coriaceous,  sometimes  glabrous 
[(L.  comorensis  [Boj.],  var.  florida,  K.  Schum.,  L.  madagascariensis  [Boj.],  K. 
Schum.,  L.  senegalensis,  T).  C.,  L.  Petersiana,  Th.  Dyer,  etc.)],  sometimes  downy; 
in  the  latter  case  the  down  is  not  commonly  found,  except  on  the  veins,  and 
almost  exclusively  on  the  under  side ;  amongst  the  most  downy  we  may  cite  L. 
tomentosa,  A.  Dew.,  L.  bracteata,  A.  Dew.,  L.  Trawnii,  Sadeb.,  and  L.  Michelinii, 
Benth. ;  on  the  upper  surface  only  the  mid-rib  is  downy,  rarely  some  rare  hairs 
are  observed  on  the  limb.  In  some  species  the  edges  of  the  leaf  are  ciliated, 
especially  in  L.  Kirkii,  Th.  Dyer.  The  presence  or  absence  of  hairs  would  not 
appear  to  be  very  constant  characteristics.  The  nervation  is  pinnate  in  all  the 
species  of  the  genus ;  a  mid-rib  is  always  present,  glabrous  or  pubescent,  generally 
making  rather  strong  projectures  on  the  inferior  surface,  crossed  in  grooves 
on  the  upper  surface;  in  L.  madagascariensis  it  is  wide  and  not  grooved  on 
the  upper  surface;  the  secondary  veins  are  inserted  almost  perpendicularly  or 
more  or  less  obliquely  on  the  mid-rib.  The  latter  are  sometimes  numerous, 
packed  parallel  one  against  the  other  (L.  madagascariensis  [Boj.],  K.  Schum.),  at 
other  times  more  distant  (L.  comorensis  [Boj.],  K.  Schum.),  often  uniting  towards 
the  margin  in  such  a  manner  as  to  form  a  hem,  which  is  particularly  marked  in  L. 
madagascariensis,  K.  Schum.,  L.  lucida,  K.  Schum.,  L.  Traunii,  Sadeb.,  L. 
Heudelotti,  D.  C.,  etc.  The  leaves  are  always  furnished  with  a  petiole,  sometimes 

1  The  first  notice  of  the  Landolphia  yielding  indiarubber  is  by  Col.  (now  Sir)  J.  A.  Grant, 
in  the  appendix  to  SpeTces  Journal  (p.  639),  repeated  in  an  elaborate  account  of  his 
collections  published  in  the  Linnean  Society's  Transactions  (xxix.  107).  In  this  he  says 
ot  L.  florida  "  A  wood  -climber,  named  M'hoonga  (Kis),  found  at  Madi,  Derembe,  in  a  shady 
spot  by  a  rocky  burn.  Its  trunk  travelled  like  a  boa-constrictor  along  the  ground  till  it  found 
3  to  climb  up,  and  was  twenty-five  inches  in  circumference  ;  ascending  to  the  topmost 
branches,  it  threw  down  pendants  of  foliage  and  clusters  of  lily-white,  scented  flowers.  The 
milk  if  rubbed  upon  the  skin  adheres  like  bird-lime  and  can  scarcely  be  rubbed  off  ...  The 
Waniao  people  make  playing-balls  from  the  juice,  and  consider  its  rubber  to  be  the  most 
adhesive  known." 


LATEX— DEFINITIONS,    ETC  23 

hut   slightly  developed     /..     /<««*;*«,  lladlk.),  r..  -ii.in   !:•  millimetre*; 

generally  it    |fl    pitted,  n. ,t    >\\o||rn    at    tin-    ba-e.  BXOepJ    in    /..  B 

optionally  a  little  enlarged  si  n-  point  ..t  in^.-rii-.n  on  the  stem,  it  is  observed  in 

L.  i,i'i< f"!/'tscarien«t)(  (  I1.-- 1 . -.  K.  Schitm.  ;  it  is  often  do\\n\.  ^labrou-*  in  /..  fomorrmit 
(l)"j.),  K.  Schum.,  L.  niadayascaricnsis  (Y»  I  -on,,-  -then*. 

'Hit-  inflorescences  are  terminal  or  later.il,  all  ron-trm -t.  .1  »n  th.-  name 
type.     They  consist,  in  a  more  or  less  reduced  Btate,  of  panicle,  .,r.  n, 
rally,  of   corymbiform   or  thyrsiform   cymes;   they   always  o  i  i«-dunde 

whirli,  sometimes  sessile  or  almost  sessile  (/..  /arvifMi,  K. 
in  certain  -pecies  (£.  Petersiano,  [Kl.],  K.    Srhum.)    a   considerable    length.    K 
centimetres   (6J    inches).      This   jxxluncle    is   continued   by  a   rachin,  on    which 
secondary  branches  arr  inserted,  to  \\hirh  sometimes  some  small  branches,  bearing 
a  certain  number  of   flowers,   are   attached.     It  may  hap|»en  that    tin-   tertiary 
branches   are  awanting,   and  that  the   secondary   an* I    primary  are  gi 
shortened,  so  as  to  simulate  a   kind    of   capitulum    (L.    Th<  I».\s  .    /.. 

•'••/A/,  K.  Schum.).  The  rachis  may  be  elongated  so  as  to  leave  a  rather 
considerable  space  between  tin-  secondary  branches.  The  panicles  of  L.  Peirrsiana 
(K!.)..  K.  Sclnun.,  arc  produced  in  this  way.  These  inflorescences  are  generally 

red  with  brown  down,  or  glabrous  in  L.  comorensi*  (Boj. ).  K.  ft  hum. 

After  tlnwering,  the  majority  of  the  species,  perhaps  even  the  whole,  elongate 
en-tain  of  their   inflorescences,  sometimes   very  greatly  ('/..    /'''/'-/  [K'-l»   K. 
Schum.,   and   L.   senegalensis,  D.  C.),  and    transform   them    iiit  =  »   ten.lriU.   whi.h 
in  the  end  become  lignified.     The  flowers  are  always  hermaphrodite.  «.,n^ 
in  a  rather  similar  fashion  in  the  different  specie*.     They  include  a  calyx,  r.m-ly 
glabrous  (L.  comorensis  [Boj.],  K.  Schum.),  more  frequently  pube-mit  or  covered 
with  bn>wn  down,  divided  as  far  as  or  almost  as  far  as  its  base    int«»  live  lobes, 
accidentally  into  four  lobes,  often  coriaceous,  carinated  (keel-shaped),  lanceolate, 
or  elliptical,  more  or  less  acute  or  obtuse  at  the  ap«-\.      In    /..  A     fa  .  'I  1  . 
the  base  of   the   divisions   is   rounded,  slightly  pedicillate.      The  length  of  the 
sepaN  hardly  exceeds  8  millimetres  in  those  species  where  they  are  largr-t  in  -i/e 
(L.  />mcteata,  A.  Dew.);  the  most  frequent  size  is  2  or  3  millimetres  ;  the 
with  large  flowers  have  generally  very  small  calices.    Thus  the  L.  madagcuca / 
(Boj.),  K.  Schum.,  and  the  L.  camorensis  (Boj.),  K.  Schum.,  the  corolla?  of  win.  h 
measure  40  millimetres  (say  1^  inches)  and  more  in  length,  have  calices  of  1*5 
to  '_'  millimetres.     There  are  no  glands  or  apj>endages  in  the  interior  <>f  the  «,d\\. 
The   funnel-shaped  corolla  always  consists   of  a  tubular  portion,  dividing  in  its 
upper  part  into  five  almost  equal  petals,  which  before  flowering  are  twistrd  to  the 
left.     Its  total  size,  that  is  to  say,  from   the  base  of   the  tube  to  the  apex  of 
the  petals,  varies  between  5  5  to  60  millimetres  (say  from  \  to  2J  irirhes).     The 
tube  is  rarely  thin  and  glabrous  (L.  comorensis  [Boj.],  K.  Schum.),  more  frequently 
hairy  and  coriaceous,  narrow  (1   to  3  millimetres),  exhibiting  either  immediately 
above  the  calyx  [(L.  Kirkii,  Th.  Dyer,  L.   Tholl<.nu,  \.    Dew..  /..  />/"///</,  K. 
Schum.)],    or    throughout   the   whole  extent   of    the    inferior  jwirt  [(/,.   madagar 
>•••«//  •/•  a  nix  [Boj.],  K.    Schum.,    L.    comorensis   [Boj.l,    K.    Schum.,    /..  •••,//*••*•»  H.<I.< 
[Boj.],  var.  Jlorida,  K.  Schum.,  L.  Petersnana  [Kl. ),  Th.  Dyer,  etc.)],  a  more  or 
less  marked  swelling.     In  L.  Lecomtei,  A.  Dew.,   thi-  -welling  i-  a  little  above 
the  middle.     In  fact,  some  species,  the   I..    //>  »•/>  /«///,    D.  C.,  for  example,  have 
an  expanded    tube   throughout    their  whole    length,  only  contracting  und< 
the  petals.     The  length  of  the  tube  varies  between  '_'  millimetres  (A.  AV/7. 
Dyer)  and  25  to  26  millimetres  (L.  comorensis  [Boj.],  K.  Schum..  and  its  va 
its  dimensions  exceed  in  certain  species  those  of  the  petals  ;  in  others  they  appear 
perceptibly  equal ;  finally  they  are  sometimes  >maller.     No  appendages  are  found 
in  the  throat  of  the  corolla  in  plants  of  this  class.      The  i«tals  are  som- 
glabrous    exteriorly   (L.    comorensis    [Boj.],    K.    Schum.);   more   often    they  are 
ciliary  on  their  edges;  many  species  with  small  flowers  have  downy  petals  on  the 
exterior ;   their  form  is   generally   lanceolate,    oboval,  or   fusiform,  more  <>i 
acute  at  the  apex,  sometimes  slightly  rounded.     Their  size,  in  certain  sj^-i.-.  /.. 


24  INDIARUBBER 

KirMi,  Th.  Dyer,  for  example,  is  from  3  to  4  millimetres  in  length  by  1'25 
millimetres  in  width.  In  others,  such  as  the  L.  comorensis  (Boj.),  K.  Schum., 
and  the  L.  comorensis  (Boj.),  var.  florida,  K.  Schum.,  they  reach  as  much  as  40 
millimetres  in  length  by  6  to  10  millimetres  in  width.  In  the  living  state  the 
flowers  of  the  Landolphia  are  white  (or  yellowish),  and  exhale  a  very  pronounced 
odour  of  jasmine;  dry,  their  tint  varies  from  brownish  yellow  to  deep  reddish 
brown.  The  stamens,  to  the  number  of  five,  are  lodged  in  the  swollen  part  of  the 
tube  of  the  corolla,  and  are  consequently  hidden  ;  they  are  reduced  to  free  anthers, 
in  the  form  of  arrows,  prolonged  into  rather  a  long  point  at  the  apex,  and 
attached  by  a  very  slender  filament  to  the  side  of  the  tube.  The  pistils  them- 
selves are  also  very  short ;  they  comprise  a  globular  ovary,  glabrous  or  pubescent, 
especially  at  the  base  of  the  style,  unilocular,  containing  two  parietal  placentas,  on 
which  are  attached  numerous  small  grains ;  the  styles  which  they  bear  at  the  apex 
are,  in  the  larger  species,  5  or  6  millimetres ;  they  are  terminated  by  a  fusiform 
stigma,  pubescent,  prolonged  by  a  sort  of  double  hanging  beak.  The  flowers 
are  intermingled  with  bracts,  generally  small  and  downy ;  the  largest  are  found 
in  L.  bracteata,  A.  Dew. ;  they  are  two  in  number,  very  downy  on  the  outside, 
situated  at  the  base  of  each  group  of  flowers.  Their  dimensions  are,  6  millimetres 
in  length  by  3  millimetres  in  width. 

Fruit. — The  fruits  are  spherical  or  piriform  bays,  with  a  coriaceous  envelope, 
which  may  in  certain  species  reach  the  size  of  a  cocoanut,  often  becoming  reduced 
to  the  size  of  an  orange,  of  an  apricot,  or  still  smaller  fruit ;  their  colour  in  the 
fresh  state  is  yellow  or  brown ;  dry,  it  is  black ;  their  surface  is  glabrous, 
sometimes  pruineuse  (I  prickly),  covered  with  lenticells ;  inside  the  fruit  are  seeds, 
more  or  less  numerous,  which,  according  to  what  little  is  known  of  them,  do  not 
appear  to  have  the  same  structure  in  all  species.  In  fact,  those  of  L.  comorensis 
(Boj.),  var.  florida,  K.  Schum.,  bear  two  distinctly  visible,  wide,  thin,  foliaceous 
cotyledons,  applied  against  one  another,  and  surrounded  by  a  horny  albumen; 
those  of  L.  Kirkii,  Th.  Dyer,  exhibit  a  continuous  albumen,  without  differentiated 
cotyledons  and  a  very  small  embryo  placed  at  the  apex  of  this  albumen.  The 
integument  of  the  seed  is,  in  all  the  known  species,  surrounded  by  an  acid,  edible, 
pulpy  layer,  which  results  from  hairs  gorged  with  juice  which  cover  its  surface. 

Geographical  Distribution. — The  genus  Landolphia  is  peculiar  to  Africa; 
twenty-one  species  are  known,  spread  between  the  16°  N.  lat.  and  the  30° 
S.  lat.,  that  is  to  say,  stopping  on  the  north,  where  the  desert  of  the  Sahara 
commences,  and  penetrating  neither  into  Nubia  nor  into  Egypt.  In  the  south, 
it  would  only  appear  to  exist  in  the  north  of  Cape  Colony ;  it  has  not  yet  been, 
so  far  as  I  know,  observed  south  of  the  Diamond  Fields.  The  most  widely  dis- 
tributed species  are  the  Landolphia  comorensis  (Boj.),  var.  florida,  K.  Schum.,  and 
the  L.  Petersiana  (Kl.),  Th.  Dyer,  which  are  found  throughout  almost  all  Africa 
to  as  great  an  extent  on  the  eastern  as  on  the  western  coast.  The  following 
species  are  met  with  on  the  western  coast : — L.  comorensis  (Boj.),  K.  Schum. ;  L. 
comorensis  (Boj.),  var.  florida,  K.  Schum.;  L.  Petersiana  (Kl.),  Th.  Dyer;  L. 
Petersiana,  var.  crassifolia,  K.  Schum. ;  L.  Lecomtei,  A.  Dew. ;  L.  lucida,  IL 
Schum. ;  L.  owariensis,  Pal.  de  Beauv. ;  L.  senegalensis,  D.  C. ;  L.  Heudelotii, 
D.  C. ;  L.  Michelinii,  Benth. ;  L.  Traunii,  Sadeb. ;  L.  tomentosa,  A.  Dew. ; 
L.  parvifolia,  K.  Schum. ;  L.  Manii,  Th.  Dyer;  L.  Thollonii,  A.  Dew. 

On  the  eastern  coast  the  following  have  been  signalised : — L.  comorensis 
(Boj.),  K.  Schum.;  L.  comorensis  (Boj.),  var.  florida,  K.  Schum.;  L.  Petersiana 
(KL),  Th.  Dyer;  L.  Petersiana,  var.  crassifolia,  K.  Schum.  ;  L.  Kirkii,  Th.  Dyer; 
L.  capensis,  Oliv. ;  L.  crassipes,  Radlk. ;  L.  madagascariensis  (Boj.),  K.  Schum. ; 
L.  angustifolia,  K.  Schum.  The  different  Landolphia,  so  far  as  is  known  at 
present,  are  quite  localised.  A  tabular  list  of  the  regions  of  Africa,  with  the 
species  which  grow  there,  will  sufficiently  show  this  to  be  the  case. 


LATEX— DEFINITIONS,    ETC. 


TMU.E  EL— DlSTBIBUTIOH    "i     NIK   \'  \  i:i<>t  >  M-I  ,  1 1      .  m\\    IN   Till 

AFRICAN  INDIARUBDKR  ZONE 


* 

*~ 

,L. 

comorenti*  (Ho\.),  var.  flaridn,  K.  Schum. 
PeUrnana(Kl),  K.  Schum. 

L. 

stnegalensi*,  D.  C. 

Senegambia  .... 

L. 

Heudelotii,  D.  C. 
Michdinii,  Benth. 

L. 

Traunii,  Sadeb. 

V& 

tomcntosa,  A.  Dew. 

Foutah-Djallon      . 

(L. 
\L. 

cowu>rat«*(Boj.),  K.  Schum. 
Hevdclotii,  D.  C. 

Gambia         .... 

(L. 
\L. 

senegalcnsis,  D.  C. 
tomentosa  (Lep.),  A.  Dew. 

Niger,  Benin,  Abbeokuta 

(L. 
\L. 

comortnsis  (Boj.),  var.  fiorida,  K.  Schum. 
vwaricnsis,  Pal.  de  Beauv. 

Calabar          .... 

(L. 
\L. 

bracteata,  A.  Dew. 
Traunii,  Sadeb. 

Region. 

Species. 

Cameroons,  Togaland     . 

(L. 
\L. 

}L. 

(L. 
r, 

coinarensis,  (Boj.)  var.  flor'ula,  K.  Schum. 
ou-ariensis,  Pal.  de  Beauv. 
Heudclotii,  D.  C. 
Mu  nil,  Th.  Dyer. 

Manii,  Th.  Dyer. 

Gaboon  and  French  Congo     . 

L. 
L. 
L. 

\i 

(i 

comoraisis  (Boj.),  K.  Schum. 
c0m0raww(Boj.),  var.  Jloritta,  K.  Schum. 
Petcrtiana  (Kl.),  Th.  Dyer. 
PtUrsiana,  var.  crasaifolia,  K.  Sihiim. 
Lecwntei,  A.  Dew. 
uit'tiri'-Hittx,  Pal.  di-  I'.IMUV. 
Thollvnii,  A  Dew. 

Congo  Free  State  . 

L. 

comorcntis  (Boj.),  K.  Si-hum. 
wnwrensis  (Boj.),  var./oruia,  K.  Schum. 
P«^r*ia7ja(Kl.),  Th.  Dyer. 
oinirientis,  Pal.  de  Beauv. 
/M«'//a,  K.  Schum. 

Angola  

L. 
\LL. 

comor«n*w(Boj.),  var.  >>•»<*«,  K.  Schum. 
Pefemona  (Kl.),  Th.  Dyer. 
otDoricnsi*,  Pal.  de  Beauv. 
jHirnfolia,  K.  Schum. 

26 


INDIARUBBER 


Eastern  Coast 


Cape      

L.  capensis,  Oliv. 

Transvaal      .... 

L.  capensis,  Oliv. 

Delagoa  Bay. 

(L.  Kirkii,  Th.  Dyer. 
\L.  Petersiana,  var.  crassifolia,  K.  Schum. 

(L.  Kirkii,  Th.  Dyer. 

Mozambique  .... 

'.L.  Petersiana  (Kl.),  Th.  Dyer. 
{.L.  cotnorensis  (Boj.),  var.  florida,  K.  Schum. 

Madagascar  .... 

/  L.  madagascariensis  (Boj.),  K.  Schum. 
{L.  crassipcs,  Radlk. 

Comores  Isles         . 

L.  comorensis  (Boj.),  K.  Schum. 

Dar-es-Salam 

)  L.  Kirkii,  Th.  Dyer. 
{L.  Petersiana  (KL),  Th.  Dyer. 

(L.  Kirkii,  Th.  Dyer. 

Zanzibar        .... 

L.  Petersiana  (Kl.),  K.  Schum. 

L.  comorensis,  var.  florida,  K.  Schum. 

(L.  angustifolia,  K.  Schum. 

Usarabara      .... 

1  L.  Kirkii,  Th.  Dyer. 
'\L.  Petersiana  (YA.},  Th.  Dyer. 
\L.  comorensis  (Boj.),  var.  florida,  K.  Schum. 

cL.  Heudelotii,  D.  C. 

Djours  .         .       •  . 

j  L.  owariensis,  Pal.  de  Beauv. 

^L.  comorensis  (Boj.),  var.  florida,  K.  Schum. 

Bahr-el-Ghazal      . 

L.  Heudelotii,  D.  C. 

Morris  classifies  Landolphia  according  to  the  size  of  leaf  and  flower  thus — 

1.  Species   with   large  flowers. — L.    florida,    L.     madagascariensis,    and    L. 
Petersiana. 

2.  Species  with  small  jlowers  and  large  leaves. — L.  senegalensis,  L.  oivariensis, 
and  L.  tomentosa. 

3.  Species  with  small  flowers  and  small  leaves. — L.  Kirkii. 

TABLE  III. — CLASSIFICATION  OF   LANDOLPHIA,  ACCORDING  TO  THEIR  VALUE 
AS  RUBBER  PRODUCERS 


Good. 


L.  Heudelotii,  A.  D.  C. 
L.  Kirkii,  B.  Dyer. 
L.  Dawei,  Stapf. 
L.  owariensis,  Beauv. 


Doubtful. 


L.  kilimandjarica,  Stapf. 

L.  Buchananii,  Stapf. 

L.  Holzii,  Busse. 

L.  drovgmanansia,  de  Wild. 

L.  Klaireii,  Pierre. 

L.  reticulata,  Halker. 

L.  Petersiana,  Dyer. 

L.  Pierrei,  Hua. 

L.  lucida,  var.  Hispeda,  Hall. 


Worthless. 


L.  florida,  Benth. 

L.  uganensis. 

L.  subturbinata,  Stapf. 


LATEX— DEFINITIONS,    ETC. 


27 


/•'"">""""  tlastica,     Thi~  if  a  plant  of  recent  importance  (tee  pp,  B 

(7)   The    Urceola^     irt-iui-     <-l     .1  '.n-i-tiiiL'     o| 

distinguished    in    the    /•/•  ••///.<. i /////» / ••  •/    -roU|.    by  tlou.-r>   \\itha   HUM  jjandular  • 
an    areolar    or  globular    \al\ate,    >ubindiiplicate.    .-r    m«.re    i.tten    -lixhtK     • 
coi-olla,  the   i-i^|,{  edges  ,,f   the   lobes   folding   backwards  on   themselves;  an  t-iitin- 
or  tive-lobed  disc.      Urceola  el«*tii-n,  a  climb»-r  \\ith   a   trunk   a>   thick   a>   a  man  > 
body,  has  a  soft,  thick  bark,    may  be  tapped  when   three  years  old,   and  soon 
shoots  up  after  liein^  cut   down.      Borneo  rubber  U   not  the  product  of  an 
but  of  s|>ecies  of    Willit<ittl><i<i  and   LrumiHtfi*.      I  (  havannesia) 

r.enth.,  a  climbing  plant  with  smuntli  branches  and  leaves,  known  locally  a>  • 

j-hpo,"    is   ,i    troublesome   weed    in    the    teak    forests  of    llurmah,    but    \i«ld, 

r 


Ki<;.  11. — Funiuiiiiu  '-Jnsti'-ii,  Stapf.  Natural  Order,  Apocyncetr.  The  ire  or  Lagos 
rubber  plant  formerly  known  as  Kicksia  Africana.  1,  Flowering  branch, 
thirds  natural  size  ;  2,  bud  ;  3,  segment  of  calyx  with  glands  at  the  base  ;  4,  corolla 
cut  open  with  style  and  stigma  removed  ;  5,  another  front  view  ;  6,  jij*til 
with  disc,  d  ;  7,  a  pair  of  follicles,  fruit  two-thirds  natural  size ;  8,  seed  of 
transverse  section  of  seed  ;  t,  testa,  a,  albumen,  c,  cavity,  Nos.  2-6,  8  and  9, 
all  enlarged.— (Kew  Bulletin.) 

caoutchouc  of  excellent  quality.  The  plant  is  cultivated  to  some  extent  for  tin- 
sake  of  its  fruit,  which  finds  a  market  as  a  substitute  for  tamarinds.  It  has 
been  under  experimental  cultivation  in  Madras,  but  it  was  found  to  be  slow  of 
growth,  and  not  regarded  as  of  much  promise  as  a  rubber  producer.  .v 
species  of  this  genus  have  been  reported  as  yeldiug  fair  quantities  of  useful  rubber. 
Urceola  esculenta,  Henth..  in  Uritish  I'mrmah  and  other  part*  of  India,  yields 
dry  rubber  with  75-80  per  cent,  of  caoutchouc,  f,  ^t'ra,  Roxb.,  in 

Malaya;    Urceola    "<•///.    »/<•// //f///.rte,  Boer.,   in    Borneo;   and    Urceola 
Hook,  f.,  in  Singapore  and  Borneo,  are  said    to   yield  milk  occasionally  rich  in 
caoutchouc.     One  species — yielding  25  grammes  of  rubber — Urceola  l/rachytepala, 
Hook,  f.,  thrives  in  Malaya,  Borneo,  and  Java,  and  may  be  cultivated  up  to  an 
altitude  of  2300  feet  (Jumelle). 


28  INDIARUBBER 

(8)  The  Hancornias. — A  genus  of  Apocynacew-crotonece,  sub-tribe  Euca, 
characterised  by  a  quinque-partite  corolla,  with  non-glandular  lobes,  arranged  in 
a  quincunx  manner,  in  the  preinflorescence.     Corolla,  hypocraterimorphous,  with  a 
narrow  tube,  hairy  within,  one  at  the  level  of  the  throat,  surmounted  by  a  limb 
with  five  linear  lanceolate  divisions.     Five  stamens,  inserted  in  the  middle  of  the 
tube  of  the  corolla,  with  lanky  filaments  bearing  linear  anthers,  acuminated,  of  the 
same  length  as  the  filaments ;  nectary  absent.    Ovary  single,  fusiform,  and  glabrous, 
divided  into  two  dissepiments  by  a  thick  fleshy  partition,  surmounted  by  a  filiform 
style,  with  an  induced  linear,  conical,  bilobed  stigma.     The  ovules  are  numerous, 
amphitropous,  inserted  on  each  side  of  the  partition  walls.     The  fruit  is  a  globular 
or  pear-shaped  bay,  pulpy,  latescent,  unilocular   by  the   abortion  of   one  of   the 
carpels,  containing  numerous  ovoid  and  compressed  seeds  embedded  in  the  pulp  of 
the  fruit,  provided  with  a  hard  albumen  and  a  central  embryo,  erect,  with  a  very 
short  radical  and  sub-oval  cotyledons.     The  ffancomias,  which  yield  Mangabeira 
rubber,  are  small  latescent  shrubs  with  opposite  entire  leaves,  short  petioles,  and 
odoriferous  flowers.      The  fruits   of  the  Hancornia  speciosa  (Gom.)  and  of  the 
Hancornia  pubescens  (Nees  and  Mart)  are  commonly  known  under  the  name  of 
Mangaba,  and  are  very  much  sought  after  by  the  natives. 

(9)  The  Alstonia  (C.)  gives  its  name  to  the  tribe  of  the  Alstonice,  of  the  family 
of  the  Apocynaceae.     Its  regular,  hermaphrodite  flowers  have  a  gamosepalous  calyx 
with   five   divisions,  quincocial  in  the  bud,  a  gamopetalous   corolla,  hypocrateri- 
morphous, with  five  lobes,  in  twisted  inflorescence,  an  andrecium  of  five  enclosed 
stamens,  and  a  gynoecium  analogous  to  those  of  the  Apocynece.     The  fruit  is  com- 
posed  of   two   narrow   elongated   follicles   containing   numerous    flattened   seeds, 
terminated   at  each  extremity  by  a  winged,  ciliated  membrane.      Fine   trees   of 
northern  Oceania  and  tropical  Asia.     Leaves  opposite,  and  flowers  united  in  spikes 
of   cymes.     The   latex  is  as  bitter  as  that   of   gentian.     Alstonias   scholar  is,  the 
chatwan,  is   a  large  evergreen  tree,  60   feet   high,  found  in  the  drier  forests  of 
India,  but  extending  to  Ceylon,  Singapore  and  Penang,  the  Malay  Archipelago, 
tropical  Australia,  Africa.     It  has  large  leathery  leaves  and  greenish-white  flowers, 
with   very  long  and  slender   follicles.     It   has  long   been  regarded  as  producing 
an  inelastic  rubber-like  substance,  but  so  far  no  use  has  been  found  for  it.     Dr. 
Ondaatje  in  1884  sent  from  Ceylon  a  large  sheet  of  a  resinous  substance  got  from 
the  latex  of  Alstonia  scholaris.     He  claimed  it  to  be  a  good   substitute  for  gutta 
percha,  being  plastic,  acid  resisting,  soluble  in  chloroform,  precipitated  by  alcohol. 
The  substance  had  been  prepared  with  care  and  pressed  into  sheets.     No  informa- 
tion was  given  as  to  quantity  available  or  cost  of  production.      The  specimen  is 
still  in  Kew  Museum. 

(10)  Chonemorpha  (G.). — Genus  of  Apocynacece,  sub-tribe  of  Euechitideos,  short, 
tubular,  quinquefid  calyx,  furnished   at  its   internal  base  with  a  glandular  ring. 
The   corolla   subinfundibuliform,  with   a   very   short   tube,    and   naked,    tubular, 
elongated  neck.     The  stamens  are  enclosed,  with  very  short  broad  filaments,  with 
anthers  adherent  to  the  stigma,  and  furnished  with  short  appendices  to  the  base  of 
their  lobes.     The  ovary,  surrounded  by  a  thick  disc,  entire,  or  scarcely  five-lobed, 
has  two  distinct  multiovular  carpels,  surmounted  by  a  filiform  style,  split  at  its 
base,  and  presenting  below  its  bifid  summit  a  fleshy  stigma,  inferiorly  dilated  into 
an   annular   membrane.     The   fruit   is   composed   of   two   triquetre   follicles,  the 
numerous  seeds  of  which,  at  their  extremity,  thinned  out  into  a  spur,  exhibit  a 
crown  of  long  hairs.     The  albumen  is  not  abundant,  and  the  cotyledons  are  thick, 
flat,  and  oblong,  with  a  short  radicle.     They  are  pubescent,  sarmentose,  climbing 
shrubs,  with  opposite,  wide,   feathered-veined   leaves   and   beautiful,  large  white 
flowers,  uniting  in  branching  cymes,  loose,  terminal,  and  sometimes  pseudo-axillary. 
Some  two  or  three  species  are  known  in  the  East  Indies  and  Malay  Archipelago, 
Chonemorpha  macrophylla,  a  stout  climbing  shrub,  found  in  moist  forests  of  India, 
Ceylon,  Malacca,  Andaman  Islands,  Sumatra,  Java.     Value  as  rubber  plant  little 
known   except   that  "it  yields  a   considerable  quantity  of   caoutchouc"  (Parish, 
quoted  by  Kurz  in  Forest  Flora,  ii.,  117). 


LATEX— DEFINITIONS,    ETC. 


•JO 


(II)  WiK'Kilihtia.— Much  rul.U-r  hitherto  ascribed  to  Willuyhlxia  will  have  to 
!>•  transferred  to  other  species  (Watt).  That  from  \V.  eduli*  contains  an  roach  M 

,•»•!•  n-nt.  "i  resin  and  only  10*8  of  caoutchouc. 

(li!)  r,,,y*i7///*/x  and  <'i ititmlrn. — Thr*«-  phmta  secrete  rubber  by  their  •tana 
ami    roots.      They    JUT    U'tt.-r    ruM»er    producing    plants    than    the    Landclphia 
thallnni  of  tin-  same  region.     Tlioy  grow  rapidly  on  sandy  ground,  and  co \ 
ground  like  couch-grass. 

<  1  ."•  i  Bedytant/u  /••/  //*/«•/•»/ //f/«i. — A  large  climbing  shrub  of  Darjeeling,  Himalaya, 
thriving  at  an  altitude  of  3000-5000  feet. 

Ail-it  IKT  plant,  mentioned  by  Mr.  Home,  is  Alstonia  jtunvmi.  of  tlii-  tlxx 
is  a  hairy  tWm.  with  >ni.ill«-r  leaves  (A.  villoM,  Seemaun).  Tin-  large-leaved  plant  i-. 
known  Inrally  as  "  Drega  «|iirui|iini."  Alstonia  plunwM  in  kimuii  in  Viti  I>evu  a« 
••Sarna."  It  alntuinls  in  tin-  fovotta,  ami,  if  aref ul ly  treated,  might  prove  a  useful 
rubber-producing  plant.  Mr.  -Irsk,-,  thr  ( 'nnniii-ionrr  for  Cole.  '  Mtes:"The 

a  IT  largr   and   glossy:    the   gum   W  obtained  from   tin-    petid0  Of   stalk.      A» 


f 


;.  12.—  Plants  producing  the  New  Root  Rubber  from  the  Congo  ami 
Carpodinii.s  lati&olatus,  natural  size,  showing  underground  stem  or  rhizoiuu 
which  the  rubber  is  obtained  ;  JB,  Top  part  of  shoot  of  the  same,  one-sixth  natural 
size  ;  C,  Single  flower  cut  open  on  one  side,  three-fourths  natural  size  ;  D  and  J?, 
Clitandra  Henresguiaiiay  one-tenth  natural  size.  —  (Tropen  pflanzer.) 

as  the  leaf  is  broken  a  thick  milky  juice  exudes,  \\hich  when  r\]M>sod  to  the 
heat  of  the  sun  for  a  little  while  congeals.  It  is  then  detached  with  a  bit  of 
bamboo  or  knife,  and  the  different  i>articles  are  pressed  together  into  balls.  That 
is  the  way  it  is  produced  when  required  as  an  article  of  comm 

ASCLEPIADEJ: 

The  Cynanchum  (L.)—(Asclepiadea>,  tribe  Cynanchw)—  characterised  by  ti\«- 
partite,  acutely  divided  calyx,  containing  five  to  ten  glands  within  iu  Imsilar  region. 
Corolla  subrotate,  deeply  quinquefid,  oblong  or  rounded  lolx?s,  contorted  folds  from 
right  to  left,  membranous  corona,  in  juxtupoMtitm  to  staminal  tubo,  ctipuliform  or 
annular  at  base,  with  five  lanceolate  or  liguliform  lobrs.  with  small  tongue  or  scale 
inside  with  denuded  *iuus,  t  \\o-teethed,  or  presenting  a  ^mall  lobe.  Stamens 
inserted  at  base  of  corolla,  with  connate  filaments  in  very  short  tuU-.  Th< 
antherous  membrane  bent  from  without  inwards,  each  dissepiment  containing  .1 
single  pollen  grain,  ovoid,  oblong,  noncompressed,  attached  some  distance  below  its 


30 


INDIARUBBER 


summit.  Stigma,  the  central  region  of  which  is  slightly  convex,  or  in  form  of  sin- 
based  cone.  Follicles  very  thin,  acuminated,  light.  Seeds  bearded.  Twining  sub- 
shrubs,  glabrous,  or  scarcely  pubescent,  opposite,  cordiform,  or  hastate  leaves,  with 
small  flowers  arranged  in  umbelliform  or  racemiform  cymes,  situated  at  the  level 
of  a  single  axil ;  pedicels  filiform. 


l 


§0 


The  Periploca  Grceca  (L.)—(Asclepiadacece)— distinguished  by  granular,  non 
massive  pollen,  glued,  however,  to  a  corpuscle,  dilated  at  its  extremity,  corolla 
rotate,  twisted,  lined  with  a  crown,  with  short,  wide  scales,  generally  prolonged  into 
five  awl-shaped  ligules.  Milky,  twining  plants,  sometimes  aphyllous. 

The  Calotropis  procera  (R.  Br.)— (Asclepidacece)— with  opposite  decussate 
leaves,  subsessile,  embracing  stem,  obovate,  superior  surface  smooth;  inferior 


LATEX  —  DEFINITIONS,    IK 


surface  covered  with  white  woolly  pul»e>rmce.     Inflorescence  in  n.in|N,Mt<- 
peduncle-  woolly;  large,  very  pretty  flo\\rrs.  of  a  roae  colour  mixed  \\ith  purple  ; 
calyx    in  live  divisions  ;  corolla  campanulate  with  angular  tuU-.  limb  \\ith  live  Mg» 

.  oblong,  obtuse,  revoluted,  U-nt,  In.  in  \sithoitt  inwards  t..  tin-  |N,ii,-      • 
with    live    scales,    adhering    to    -taminal    tube,    rather    !le>h\,    compreiwed    lat.  -rally, 
prolonged    in    the   back  at  base  OT  tOWaidl  middle    into   a   tuU%   reclined  upu.irds. 
Stamen-  \\itli   connate  filaments  in    short    tiilx-  ;    jiollrn    grains    -olit.u\   in  wwh   din 
sfjiiinrnt,   oliovsil,   oblong,    coni|.rc—  «-d.    sii>jM-ndrd    !r«.iii    -uniinit  ;    >ti^'ina   ol 
(irntagonal  ;  follicles  short,  acuminated,  with  bearded  need.1 

('ri/fttimtniin  !/r<i/i't/f!»,-<i  (\l.   I'.r.  ).       A  liandsoiiu-   climbing   plant,  tin-  "l'u!.i\. 
with   glossy    leaves  and    pah-    purple    tlo\\.-rs   in    large,    terminal   rlijstrrs.    pmliably 
a    nativr    of    Madagascar.    l>ut    now    naturalised    in    India   and    many    parts   of    the 
Tropics,  is  said  to  yield  good  rubber.     Rubber  of  fair  quality,  about  30  per  cent 
caoutchouc. 

N  \TUBAL    ORDER     Compo&itce.  —  If   this    natural   order   comprise*    a    great 

number  of  genera  and  species  distributed  over  all  regions  of  the  globe,  yet  it  com- 

but  very  few  species  capable  of  being  cultivated  for  indiarubber  ;  but  lately 

the   source   of   guayule   rubber    in    Mexico   has    been    identified    as    J'<n  •///.//,///« 

A  /••/'  iit'itum  (Asa  Gray)  (see  Fig.  13). 

NATURAL   ORDER   Lobeliacett*.  —  Si/phocampy/  1«,   a    South    American    tropical 
species,  is  said  to  yield  commercial  rubber  in  Columbia  and  Ecuador. 

According  to  Jumelle,  Sonchm  Oleraceus  (L.)  yields  valuable  rubier.     Colorado 
rubber  is  said  to  be  derived  from  a  species  of  Hymenoxys. 

1  This  genus  is  retained  here  as  a  rubber-yielding  plant,  as  it  was  so  placed  by  the  author*. 
But  its  product  is  described  as  a  jwudo  yutta  by  Hooper.  —  J.  G.  M. 


CHAPTER   II 

METHODS  OF  OBTAINING  THE  LATEX— METHODS  OF 
PREPARING  RAW  OR  CRUDE  INDIARUBBER 

BEYOND  the  sphere  of  the  general  causes  (see  Chapter  I.)  which  influence  in  so 
many  different  ways  the  richness  of  the  latescent  juice,  there  is  another  and  quite 
a  special  influence — independent  altogether  of  the  predetermining  influences  of 
natural  agents — which  depends  solely  on  the  intelligence  of  the  operator,  namely, 
the  methods  adopted  for  collecting  the  latex,  as  well  as  the  processes  employed  to 
extract  the  indiarubber  from  the  harvested  juice. 

Wright  points  out  that  the  "  commercial  possibilities  and  the  ultimate  success 
of  several  species  are  determined  by  the  particular  type  of  laticiferous  tissue  which 
each  contains;  each  type  (he  insists)  requires  to  be  dealt  with  in  a  particular 
manner :  it  is  very  dangerous  to  adopt  the  same  methods  of  tapping  for  all  species. 
The  principles  of  paring  and  pricking  the  primary  and  renewed  cortex  should  be 
^studied  more  seriously  and  intelligently  than  they  appear  to  be  at  the  present  time. 
When  one  considers  the  great  difference  in  the  nature,  mode  of  origin,  and  develop- 
ment of  the  laticifers  in  various  plants,  there  is  every  reason  for  suggesting  that 
each  species  should  be  tapped  on  a  particular  system  in  order  to  take  advantage  of 
the  peculiarities  of  each  type.  These  remarks  are  made  because  there  is  a  tendency 
among  responsible  persons  to  recommend  or  adopt  for  their  Castilloa,  Manihot, 
Funtumia,  Landolphia,  and  Ficus  plants,  the  system  of  tapping  which  has  been 
found  to  be  so  successful  with  Hevea  braziliensis.  From  a  study  of  the  laticiferous 
system  of  our  prominent  plants,  I  am  convinced  that  in  certain  instances  the  old, 
native,  and  apparently  wasteful,  methods  adopted  in  the  extraction  of  latex  are 
probably  as  good  as,  and  even  better  than,  many  wrhich  have  been  evolved.  The 
laticiferous  system  in  several  of  our  important  species  occurs  in  the  cortex  of  the 
stem,  branches,  roots,  and  in  the  leaves,  flowers,  and  fruits.  In  some  species  the 
laticifers  appear  to  be  best  developed  in  the  root,  and  the  extraction  of  latex  is 
only  considered  in  relation  to  that  part ;  in  other  species  there  appears  to  be  a 
better  development  in  the  stem,  and  in  a  few  others  the  flowers  or  young  twigs 
show  conspicuous  developments.  Generally,  these  structures  and  the  latex  appear 
in  the  embryo  and  remain  until  the  death  of  the  plant ;  in  some  cases,  however,  the 
laticifers  are  not  obvious  except  in  plants  of  some  years'  growth.  Sometimes  they 
are  absolutely  restricted  to  stem  and  roots,  the  leaves  and  flowers  never  being  in 
possession  of  such  structures ;  in  a  few  cases  they  appear  in  the  young  tissues,  and 
then  gradually  die  and  disappear.  There  are  three  types  of  laticiferous  systems,  the 
components  of  which  are  scattered  freely  throughout  the  cortex  in  the  stem ;  they 
may,  according  to  their  age  and  the  condition  of  the  plant,  be  partially  or  wholly 
filled  with  latex.  When  the  cortex  is  incised  the  latex  escapes,  the  quantity  thus 
issuing  depending  largely  upon  the  structural  relations  of  the  laticifers  and  the 
moisture  conditions.  A  given  incision  allows  the  latex  to  issue  only  from  a  local  • 
area,  dependent  in  extent  upon  the  nature  of  the  laticiferous  system  being  tapped ; 
generally  several,  and  sometimes  a  very  large  number  of,  incisions  may  be  made  on 
the  basal  part  of  the  stem." 

Perkin  observes  that  the  latex  from  the  thin  stems  of  Urceola  elastica,  such 
as  bear  the  leaves  or  have  recently  shed  them,  forms  a  sticky  substance  when 
moulded  between  the  fingers  and  thumb.  The  plant  resembles  Castilloa  in  this 

32 


METHODS   OF  OBTAINING  THK    LATEX     1   l< 


respect.      The   latex    both  from    tin-  pith  ami  from    tin-  <-..n«-\  of   tin-    \"Uii^ 
:ii>-k\.  heiici-  it   l<  tin-  triu-  caoutchouc  i-  ..nl\  l-nnrd  in  tin*  HeCOIuUr 

/////•  .i,///////,/..  I/////    (c)  toil,       'I'll'-   <-limat<-.    tin- 

as  \\ell    .1-    ill.-    SOU,  Or    rather    I  he-e    three    t..  .-    not   \\ithuiit 

,i   i-i-rtain    iiiijiortaiiri-.  from    tin-    ]M.int    of    \ir\vof   tli<-   >piantit\   ami    qiialitx   of   the 

Kor  altitude  in  <  v\  ion  where  //•/•••/  ma\  be  grown,  lee  Table  XV. 

C/fm-if'  and  "tfi/iHl,.  -  -Although  generally  tin-  culture  of  mdi.ii  ubU-r  ran  only 
be  remunerative  in  tin-  tropical  /."lie,  \\here  a  temperat  un-  reign-  which  nevi-r  full" 
IK-IONS  I'D  C  !•'.),  ami  m-ver  goes  beyond  TJ  •  107*6  I  .  >.  with  an 

rainfall  of  -j-iir,  m.  -tres  (say  80  inches),  even  in  the  zone  confined  between 
'i'  of  N.  lat.  and  tin-  ."><>  of  S.  hit.,  tliriv  exists  SO  many  variation*  in 
regard  to  heat,  moisture,  a>  well  as  altitude,  that  a  r.-rtain  sp<-ci,->  of  plant  may 
prosper  in  I'.ra/.il,  \\ithoiit  it-  being  capable  of  being  ac.-limat  i.-«-d  in  India.  ] 
asM-rtions  arc  amply  continued  in  the  chapter-  mon-  e>p.-.-i.dly  devoted  to 
Acclimatisation  and  rational  culture. 

Methods  of  ofifai  Hint/  t/n   Latex.  —  The  latex  is  obtained  by  making  im-i-io- 
the  imliariibber  tree  :  this  operation  seems  a  very  simple  one,  yet  it  requires  <•• 
precautions,  in  view  of  the  immediate  industrial  yield,  but  more  especially  in  regard 
to  the   preservation    and    reproduction    of   the    indiarul.l  er    trees.     An    uiitiim-ly 
operation  may  destroy  the  end  in  view:  the  collection  of  the  utmost  ipiantn 
the  best  quality,  but,  at  the  same  time,  the  preservation  of  the  harvests  of  the 
future. 

Tli  roe  methods  are  adopted   for  obtaining  the  latex  :  —  1.  The  felling  of  tin- 
2.  Bleeding  by  puncture  or  incision  —  "tapping."     3.   Drying  the  root  with 
subsequent  maceration  in  water. 

1.  lulling:  an  operation  to  be  condemned.  —  Felling  the  tree  is  an  expeditious 
method,  but  is  in  general  irrational  and  barbarous;  it  meets  immediate  wants,  but 
does  so  only  once.  Nature,  after  many  long  years  —  a  prolonged  period  of  ge- 

-has  placed  at  the  disposal  of  man  a  working  and  producing  tool,  and  with  a  single 
blow  of  the  axe  all  this  weary  preparation  is  annihilated,  and  it  once  more  requires 
another  long  lapse  of  time  to  repair  what  the  improvidence,  the  thoughtlessness, 
the  indolence,  coupled  with  the  greed  of  the  collector,  has  destroyed.  Felling 
is  still  carried  on  in  Africa,  in  Asia,  and  more  especially  in  the  Indian  Archipelago, 
where  until  recently  it  was  the  only  method  adopted  in  obtaining  Borneo  india- 
rubber  ;  it  is  therefore,  undeniably,  to  be  condemned,  except  in  j>erha|)8  two 
exceptional  cases. 

Exceptional  cases  in  which  fellintj  mnu  !,<  justified.  —  (a)  Where  tree,  »n<->  U«L 
dies.  —  In  the  case  where,  as  is  stated  by  the  gummeros  of  Peru,  the  imliurubber 
tree  on  which  they  operate  (Ilancornia  speciosa),  once  incised,  even  slightly,  is 
inevitably  killed  by  that  single  incision.  Insects  attack  the  bark  and  the  tree,  on 
the  >j»ot  incised,  and  the  tree  soon  dies.  But  if  the  tree  be  cut  down  close  to 
the  ground,  sprouts,  the  growth  of  which  is  very  rapid,  spring  up  from  the  stump, 
new  trees  rise  up  in  a  cluster,  and,  after  a  few  years,  for  one  tree  felled  a  whole 
group  is  reproduced.  As  the  trees  are  very  abundant,  and  as  the  activity  of  tin- 
collector  is  sufficiently  exercised  by  operating  on  trees  of  full  vigour,  and  also 
owing  to  a  quasi-tacit  agreement,  only  trees  of  more  than  a  metre  (3-:!8  feet)  in 
diameter  at  the  base  are  operated  on,  it  would  appear  evident  that  this  method  ot 
obtaining  the  latex  has  something  rational  in  it.  But  beyond  the  fact  that 
clusters  of  trees  from  the  same  stump  have  but  little  allurement,  it  is  dihMcult  to 
understand  how  the  incised  tree  perishes  in  Peru,  and  continues  to  thrive  in  < 
in  Ceylon,  and  on  the  Congo.  Can  future  explorers  and  naturalUt-  enlighten  us 
on  that  point1?  Till  then,  the  excellence  of  the  native  process  is  not  demonstrated, 
and  a  better  one  can  no  doubt  be  elaborated. 

(b)  For  thinninif  or  clearing  /mrposes.—  There  is  a  second  case  when-  felling 
may  be  justified  :  this    is,  when   it   is   desired  more  especially  to  realise 
forests  —  for  example,  those  of  Central  Africa.      An   inextricable  thicket.  \\h- 
operator  could  not  otherwise  penetrate  nor  move  about,  can  then  be  advantageously 


34  INDIARUBBER 

cleared;  moreover,  felling  admits  air  and  light,  so  necessary  for  active  growth,  and 
if  the  operation  be  performed  with  intelligence  and  in  a  methodical  manner  tlinv 
is  nothing  irrational  in  it.  The  essential  thing  is  to  make  the  native  understand 
the  point  at  which  his  work  of  destruction  should  stop.  It  is  a  delicate  matter, 
difficult  to  settle. 

2.  Bleeding  by  incision  or  puncture—"  tapping."— This  is  an  infinitely  more 
rational  method;  if  performed  methodically  and  carefully,  so  as  not  to  injure 
the  tree  nor  the  quality  of  the  rubber  to  be  extracted  from  it.  Brazil,  and 
more  especially  the  basin  of  the  Amazon  and  its  tributaries,  is  the  country  which 
has  produced  the  indiarubber  which  is  held  in  highest  repute,  so  far  as  purity  and 
quality  are  concerned.  It  is  also  in  that  country  that  tapping  would  appear  to 
have  been  first  practised  in  the  most  methodical  way.  It  is  therefore  preferable  to 
describe  the  process  practised  in  that  country,  show  its  advantages,  and  quote  it 
as  an  example  each  time  that  it  may  be  compatible  with  the  country  and  the  plants 
operated  upon. 

The  arrocho  system  of  tapping. — The  most  primitive  process  of  tapping  known 
in  Brazil  under  the  name  of  arrocho,  consisted  in  binding  the  Hevea  with  an 
obliquely  adjusted  rope,  the  tied  knot  being  in  the  upper  part.  Above  this  ligature, 
tightened  at  the  bottom,  numerous  incisions  were  made.  The  sap  flowed,  descended 
vertically,  then  meeting  the  rope,  followed  the  small  gutter  which  the  rope  formed 
with  the  tree,  and  at  last  arrived  at  the  lower  point,  below  which  was  a  receptacle. 
This  process  damaged  the  trees  to  a  very  great  extent,  the  serinyueiros  did  not 
always  take  the  trouble  to  remove  the  ropes,  and  the  Heveas,  strangled  at  their 
base,  soon  perished.  Moreover,  the  latex,  making  a  long  journey  down  the  tree, 
brought,  in  its  train,  mosses,  wooden  debris,  and  other  impurities,  afterwards 
found  in  the  rubber.  The  incision  was  made  with  a  butcher's  knife,  a  pruning  hook, 
or  a  cutlass,  and  penetrated  more  or  less  deeply  into  the  trunk ;  and,  where  the 
tree  was  not  mortally  wounded,  it  was  either  insufficiently  tapped,  and  did  not 
yield  sufficient  latex,  or  too  deeply,  and  thus  facilitated  the  addition  to  the  latescent 
juice  of  other  juices  more  or  less  prejudicial  to  the  purity  of  the  rubber,  and,  above 
all,  to  its  after-preservation.  This  process  has  been  almost  completely  abandoned. 

The  present  method  of  bleeding  or  tapping  rubber  trees  in  Brazil. — Tapping  as 
now  practised  in  the  lower  valley  of  the  Amazon,  is  better  understood  and  more 
rational ;  all  writers  on  rubber  have  more  or  less  completely  described  it.  Carrey 
and  Chapel  give  the  most  intelligible  and  the  most  methodical  description.  The 
seringueiro  starts  work  at  daybreak,  i.e.  about  five  o'clock  in  the  morning.  If  the 
estrada  (100  to  150  Heveas}  which  he  is  going  to  operate  upon  be  rather  far  away 
from  his  hut,  he  has  taken  care  to  bring  thither  the  previous  night  the  tools  required 
for  his  work.  The  first  of  these  is  the  machado,  a  small  hatchet  with  a  short  handle, 
the  blade  of  which  is  only  3  centimetres  (say  1^-  inch)  wide,  with  a  sharp  cutting 
edge  of  about  5  milimetres  (say  i  of  an  inch),  the  bucket,  and  the  tigelinhas,  small 
white  iron  goblets.  The  seringueiro,  or  cauchero,  is  generally  accompanied  by  his 
family  or  by  one  or  more  assistants ;  it  is  but  rarely  that  he  operates  single- 
handed — a  condition  contrary  to  profitable  working.  After  having  previously  well 
cleaned  the  outside  surface  of  the  tree  to  be  incised,  and  removed  the  rubbish  from 
around  the  foot  of  the  tree,  he  commences  to  tap  the  tree.  With  a  single 
straight  cut  of  the  hatchet  he  incises  the  bark  so  far  that  the  latex  flows,  but  with- 
out the  wound  mutilating  the  tree.  He  strikes  the  same  trunk  in  a  dozen  places, 
taking  care  that  his  tool  does  not  penetrate  more  than  a  few  centimetres,  according 
to  the  tree  upon  which  he  is  operating.  The  shape  of  the  machado,  due  to  the 
sound  practical  sense  of  the  North  Americans,  is,  moreover,  well  chosen  to  attain 
the  object  in  view,  and  it  is  with  justice  that  E.  Carrey  remarks  that  "  this  small 
hatchet  has  saved  more  Heveas  from  destruction  than  all  the  protective  laws  of  the 
Brazilian  Assemblies.  Since  the  time  that  the  collectors  of  the  Amazon  adopted  this 
tool,  which  only  makes  uniform,  narrow,  and  easily  executed  incisions,  the  greater 
number  of  them  have  given  up  the  use  of  those  tools  with  which,  in  every  sense  of 
the  word,  they  used  to  martyr  the  trunks  of  the  Heveas. 


METHODS   OF   OBTAINING  THE   LATEX,    ETC. 


35 


Some  i-,.||i-.-t.,r>  make  their  iiici-i.m>  in  tin-  l'..rm  «.!  .1    V,  'there  make  cut*  along 
enr\rd  lim-sat   :i  di-taii«v  i.f  al"-ut    -jo  cent  iinH  i  -  -  i,r   ^   inches  the  one  from  tin* 
otlici-.       Kinally,  a   u'lvat    rniiiil»T  an-  c..ntrnt  to  make  \.-rti.al  im-i-i..ii-.  striking  a* 
hiu'h  up  tin1  live  as  thr  arm  «-an  n-ai-li.  and  repeat  in^  tin-  Mo\s>  down  to  the  ground. 
\Vein-i-t    LTivatK  on    ;i    regular    \ertical    incision  :   tin-    ft  i    dioiild  never 

de\iate  from  it.  Kxperinice  ha-  demonstrated  that  a  tivr  in.-i...-d  in  an  irregnlar 
manner  continues  to  yield  it-  annual  .piota  for  tin-  lir-t  and  tin-  NOOOd  fBMBi  following, 
I.  lit  l.y  the  third  year  the  milk  I.e-in-  to  decrease,  and  Boon  dries  up  eompl.  • 

Repeated  careful  inci-ion.,  bowever,  do  not  atiVct   tlie  tree.      Numen.n,  //even* 
may  !•.-  -'•'•n  riddled  \\itli    -car-   to   -iich   an   extent  that  not  a  Hpot  remains  ax  large 
as     tlie     hand     \\hieh     lias     not    been 
tapped.  and   in    spite  of   these  repeated 
assaults  the  tree   retains    its  flourishing 
appearance.        A    tree    4    to    8   feet    in 
circumference  at  its  base  can  very  \\cll 
stand  ten  to  t  \\enty  incisions  e\ery  two 
or  three  days  at   the  most.     A  daily 
ineixion  would  give  an  uiuvniunerative    ¥lQ>  14._Hatchet  (nuirA.-  -/o)   uaed  in 

yield.  tapping  wild  indiarubber  trees  in  Brazil. 

The  estrada  of  150  trees  is  gener- 

ally divided  by  the  seringueiros  into  three  divisions,  each  of  which  is  OJK  iat«  d  »\\ 
every  three  day-.  I  f  the  estrada  be  smaller,  100  trees,  the  operation  is  repeated 
every  two  days.  The  whole  season  comprises  in  all  twenty  tappings  |*  -r  tree  per 
annum;  l>y  going  beyond  that,  the  tree  would  be  too  much  enfeebled  and  n.\t 
year'-  yield  compromised.  One  man,  with  his  equipment,  generally  \\ork.s  tin* 
whole  estrada  ;  but  this  number  is  not  fixed  ;  all  dei>ends  on  the  activity  of  the 
collet-tor  and  on  the  proximity  of  the  trees  to  each  other.'  An  essential  condition 
Is  not  to  have  to  walk  a  long  way  from  a  tree  which  has  been  operated  upon  to  one 
about  to  be  similarly  treated. 

/'•  riod  »r  season  of  collection.  —  The  collection  of  the  latex  may  be  made  at  any 
season  of  the  year,  but  it  generally  takes  place  in  the  period 
between  the  end  of  August  and  the  first  of  January.  Beyond 
this  season  the  yield  is  not  remunerative. 

//•>ur  at  which  trees  are  tapped.  —  Generally  operations 
commence  at  daybreak  ;  the  trees,  refreshed  by  the  nocturnal 
breezes,  bleed  more  profusely  than  at  any  other  hour  of  the 
day.  In  some  localities,  however,  the  serin</ueir<j  prefers  t«. 
make  his  incisions  at  dusk  and  to  collect  the  first  thing  in  the 
morning, 

Height  of  the  incision.  —  Tapping  is  practised  to  the  . 
of  the  sweep  of  a  man's  arm,  about  ()•:*  to   1'S  metre  (say  1 
to  6  feet)  above  the  ground.     When  the  incisions  have  been 
15.  —  TiydiHha,   made,  the  operator  fixes  tiyelinhas  below,  and  makes  them 

"    adhere  to  the  tmilk  by  meailS  of  alittk'  Illastit'  l>Ia-Vt  I"'"'"1"1 

beforehand. 

}'/./»/  taut  <l,i  ration  of  the  flow.  —  Each  regular  incision  with  the  hatchet  distils 
its  latex,  drop  by  drop,  from  one  to  three  hours,  so  as  to  yield  3  centilitres  (rather 
more  than  1  oz.)  of  milk.  This  quantity  is  not  absolute,  and  may  vary,  areoidini: 
as  the  tree  is  in  full  vigour  or  in  its  decline.  The  yield  differs,  moreover,  according 
to  the  year.  The  prolonged  duration  of  the  rains  or  excessive  drought  influences 
the  How  of  the  latescent  juice,  in  the  same  way  as  the  situation  of  the  incision, 
whether  it  be  in  the  sun  or  in  the  shade,  may  determine  a  more  or  less  abundant 
How.  This,  to  a  certain  extent,  explains  the  preference  of  certain  Indians  for  the 
nocturnal  incisions  of  which  we  have  just  spoken.  Hut  those  stormy  rains  which 
occur  almost  daily,  and  which  have  such'  a  prejudicial  effect  on  the  quality  of  the 
latex  collected,  do  not  occur  during  the  night,  and  this,  again,  is  a  further  reason 
for  the  preference  of  the  collector  for  the  hour  which  he  select*. 


36 


INDIARUBBER 


Influence  of  the  phase  of  the  moon  on  the  secretion.—  The  native  asserts  that  the 
flow  is  more  abundant  at  full  moon  than  at  any  other  time.  We  do  not  know  to 
what  extent  this  assertion  may  be  founded  on  fact;  old  folk  often  furnish  very 
curious  facts,  based  almost  always  on  meteorological  and  telluric  observation*  ; 
science  has  often  explained  and  almost  always  accepted  them. 

Yield  of  an  estrada. — An  estrada  of  150  trees  may  on  an  average  yield  by 
tappings  52  litres  (say  11^  gallons)  per  incision,  say  36  kilogrammes  (80  Ib.  of 


FIG.  16. — Seringueiro  using  an  improvised  ladder  to  tap  the  para  indiarubber 
H  (Hevea  brasiliensis). 

raw  indiarubber),  which,  at  the  average  price  of  5  francs  the  kilogramme  (say 
Is.  lOd.  per  Ib.),  gives  a  return  of  180  francs  (£7,  4s.).  It  being  given  that 
twenty  incisions  are  made  annually,  the  season  will  produce  a  gross  revenue  of 
3600  francs  (£144). 

The  tapping  methods  of  the  Upper  Amazon. — The  methods  of  tapping  in  the 
Upper  Amazon  are  almost  identical  with  the  preceding,  except  that  the  tools  are 
more  rudimentary,  and  the  care  taken  in  the  management  of  the  trees  is  not  so  well 
observed.  The  collector  does  not  encumber  himself  with  much  baggage  as  he 
penetrates  deeper  and  deeper  into  solitude.  A  calabash  serves  as  a  bucket,  a 


METHODS  OF  OBTAINING  THE   LATEX,    ETC  3? 


slirll    as    a    //»/.//////•/,   and    the    American     li;itdi.-t    gives    plaCC    tO    UlO    old    wilfo-lieitt 

iron  axe  >•»  deadly  t«i  indiarubber  trees. 

M  //»•/•  ,s'r,/^//  Ain>rn-<m  m.ihn.l*.  Aliii-.-t  \\ithoiit  exception,  the  method  of 
tapping  is  tin-  same  throughout  tin-  \\hoK-  of  s.nth  America;  the  arrangement, 
extent,  and  depth  nt  thf  inci-ion>  are  not  always  identical,  tin-  manii'-i  of  collecting 
tin-  secreted  juice  ditlers,  Init  tin-  principle  is  alua\>  the 

('•ntnil    Aiii>i-i'-'iii    iiftliifln.      In   Central    America,  \\hrn-   tin-    principal 
rubber  \ieldiiiU'    tree    is   of    i|iiitc    a    dim-rent    natm-  ucUiotl 

properly    -«,   called   is  often    replaced    by    puncture.    a    -mailer    \\oimd    m.id- 
hatchet    "f   still    more    infinitesimal    dimensions    than    that    of    the   niaehtut 

fB  Wright,  the  natives  -rni  to  believe  in  the  tapping  of  the  higher 
parts  of  the  Castilloa  tree.  In  some  part-  «.f  Mexico  e\en  Kuropeaiw  appear 
tn  ha\r  HTdiu-M'  tn  larj^e  un\\irl«ly  kiml>  with  \shich  a  heavy  Mow  may  be 

inflicted 

A/rli-mi  processes.  —  In  Africa,  the  iiicthntls  t>\'  incision  almost  always  dill'n- 
from  one  locality  to  another,  but  until  lately  they  have  always  been  carried  on 
in  a  very  imperfect  and  irrational  manner.  Unt  n«i\\  (  '<>l«mial  '.'  mine  ntn  art- 
eilueatinx  the  natives  in  rubber  arlx>riculture.  The  product,  which  from  its  very 
nature  is  often,  to  a  certain  extent,  inferior  to  South  American  rubber,  and 
especially  to  that  of  Ama/onia,  loses  still  further  in  value  by  admixture  with 
a  foreign  resin  produced  by  too  deep  an  incision.  This  re«in  very  often  brings 
about  the  decomposition  of  the  caoutchouc. 

A*i'it'n-  niettiods.  —  In  Asia,  and  principally  in  those  localities  when-  the  india 
rubber  is  extracted  from  the  different  varieties  of  /Yo/x,  the  incision*  are  made  on 
the  lower  part  of  the  trunk  and  on  the  roots  rising  out  of  the  ground  ;  its  form  is 
elliptical,  and  it  penetrates  as  far  as  the  liber;  it  is  150  to  450  centimetres 
l"ii.r  and  73  centimeters  deep.1  The  yield  in  latex  varies  with  the  season.  The 
milky  juice  is  not  very  abundant  from  February  to  March,  but  as  its  richness 
in  rubber  is  considerable,  therefore  working  is  then  most  profitable.  It  is 
almost  the  same  in  August,  a  time  at  which  the  latex  gives  a  yield  of  30  per 
cent.,  but  which  diminishes  as  far  as  10  per  cent,  during  the  other  months. 

3.  Oceanic  methods.  —  In  Oceania,  Asiatic  methods  are  partially  followed,  when 
similar  indiarubber  trees  are  tapi>ed  ;  or  the  primitive  process  of  felling,  when  the 
want  of  authority,  coupled  with  short-sightedness  or  indolence  of  the  local  powers, 
the  natives  to  their  own  initiative.  Their  inconsiderate  ravages  are  princi- 
pally inflicted  on  the  Urceola  elastica,  a  plant  which  often  attains  a  diameter  equal 
t  >  tiiat  of  the  human  body.  The  shrub  is  broken  up  into  pieces  of  O'l  •-'."»  metre 
(say  5  inches)  to  0'8  metre  (say  31  inches),  which  are  placed  above  large  receptacles, 
intended  to  collect  the  juice  which  drops  from  them.  If  the  exudation  show  signs 
of  slackenings,  or  does  not  go  on  as  the  collector  thinks  it  should,  the  flow  is 
stimulated  by  the  heat  of  a  few  kindled  twigs. 

I'r<'i-nlii  '.«-nlenta.  —  As  far  as  it  is  concerned,  the  methodical  tapping  as  it 
ought  to  be  informed  consists  in  making,  in  the  body  of  the  plant,  a  V-shaped 
incision  of  1  to  '2  centimetres  (from  f  to  $  of  an  inch  in  height  by  3  to  4 
centimetres,  say  1J  to  1J  inches,  in  depth).  These  cuts  ought  to  go  right 
through  the  bark,  but  stop  short  at  contact  with  the  wood. 

'/'///•  ini'Toscopical  structure  of  Urceola  elastica.  —  The  microscopical  examination 
of  the  fragments  of  bark  found  in  the  mass  amply  show  the  necessity  of  thi-* 
method;  in  fact  we  meet,  below  the  suber,  *«.,  which  forms  the  external  limits— 
(1)  A  thi<k.  M-lerenchymatous  layer,  as.,  consisting  of  a  do/en  r«.\\s  of  cells  in 
radial  lines;  (2)  an  abundant  parenchyma,  /'.<-..  shoeing  here  and  there  miHMIfl 
of  sclerenchymatoiis  cells,  c.s  ;  (3)  finally,  aneutiivK  soft  liU'r.  //..  very  voliimniouft, 
which  in  itself  alone  constitutes  one  half  of  the  thickne<>  of  the  bark,  very  rich  in 
laticiferoii<  tUsur,  especially  in  the  young  parts.  The  in«-i>ioiix  .,-i-jht  therefore 
to  penetrate  as  far  a-  the  cambium,  so  a-  to  atl'ect  all  the  laticiferoUS 
and  thus  ensure  the  largest  yield. 

1  Millimetres  are  evidently  meant,  say  6  to  18  inches  long  by  3  inrhe*  in  dopth.—  Tn. 


38 


INDIARUBBER 


Nummary.— Such  are,  sketched  rapidly,  the  different  processes  in  use  for 
obtaining  the  latex.  The  influence  which  they  exert  on  the  preservation  of  the 
rubber-producing  plants  need  not  be  dwelt  upon  further.  The  great  importance 
of  working  rationally  to  secure  this  end  is  obvious.  The  same  remark  applies  to 
the  quantity  of  latex  to  be  obtained,  and  to  the  yield  of  the  latter  in  rubber.  But 
the  method  of  tapping  nevertheless  exerts  a  very  important  influence  on  the  quality 
of  the  rubber  extracted  from  the  latex,  and  more  especially  on  its  keeping 
properties  in  the  crude  state.  Too  large,  too  deep,  an  incision  may  reach  the  liber, 
expose  it  too  much,  and  impoverish  the  plant,  if  it  does  not  cause  it  to  die  ; 
it  may,  moreover,  allow  certain. juices,  from  the  interior  of  the  plant,  to  mingle 
with  the  latex  at  the  exit  of  the  wound,  and  so  alter  its  natural  purity,  and  even 
affect  eventually  its  proximate  chemical  constitution,  converting  it  into  a  body 
of  different  chemical  composition.  But  this  influence  is  most  deleterious  when 
the  latex  has  been  obtained  by  felling.  The  milk  is  then  forcibly  mixed  with 


r* 


FIG.  17,—Urceola  elastica.—l.  Longitudinal  and  transverse  sections— si'..,  suber  ;  p.c., 
cortical  parenchyma  ;  c.s.,  sclerose  cells  ;  la.,  laticiferous cells  ;  r.m.,  medullary 
rays  ;  p.L,  ligneous  parenchyma  ;  r.L,  large  ligneous  vessels  filled  with  latex. 
2.  Details  of  laticiferous  vessels  in  the  traverse  and  longitudinal  section  in  the 
bark;  la.,  laticiferous  vessels  ;  li.,  liber.  3.  Details  of  the  sclerose  cells  ;  c.s., 
sclerose  cells. 


the  other  secretions  which  the  plant  may  yield,  whether  saccharine,  amylaceous, 
proteic,  tannic,  or  resinous;  and  according  to  what  these  juices  may  be  they 
will  have  a  more  or  less  injurious  influence  on  the  industrial  rubber,  and  the 
qualities  which  commerce  exacts  from  it.  It  will  readily  be  seen  that  the  French 
and  American  methods  of  obtaining  oleoresin  from  the  pine  with  their  deep 
incisions  to  reach  the  new  wood  in  which  the  resiniferous  vessels  occur  are  not 
adapted  for  indiarubber. 

Methods  of  preparing  commercial  indiarubher  from  the  juice. — Preliminary 
considerations. — This  part  of  the  authors'  work  is  important,  but  at  the  same  time 
the  most  delicate,  and  it  is  not  without  some  hesitation  that  they  enter  upon  it.  All 
authorities  acknowledge  that  rubber-extraction  processes  are  in  general  defective, 
and  considerably  injure  the  marketable  quality  of  the  product,  all  of  which  has 
the  effect  of  restricting  the  use  of  the  latter.  But  technical  literature  is  too  often 
content  to  point  out  the  evil  without  going  deeply  into  the  causes  in  a  methodical 
manner,  and  without  indicating  any  possible  remedy. 

Bobei's  method  for  improving  the  coagulation  jwocesses. — "It  would  be  advan- 
tageous to  improve  the  processes  of  coagulation  adopted  in  French  colonies,  and 
to  do  so  it  would  be  necessary  to  study  the  nature  and  properties  of  the  latex, 


METHODS   OF   OBTAINING  THE   LATEX.    IK 

;ui(l    then  tn    make  somr  e\ | .eriim-nt s  on  COBglllat i. .n,     o  a«  to  decide  UJH.II  tin-  l«tt 

method  to  follow.     Onthr  supposition  that  these  exjH-i  ulil  m,t  U-  made 

•  in  the  spot,  tin-   local  colonial   oH'n-ial>  could  ra-ily  p-t  them  don«-  in    tin-  mother 
country    (neither    willing    hands    nor    talenN    uoiild    !„•    t'»und    \\anting),    but 
\\oiild  In-  desirable  to  prosidc  sample-  and  the  following  d 

"(1)  Necessari/  «/«//•/  for  iin/-i-"i>ement  of  present  processes. — San> 
M  now  inivde. — Send  (a)  sample  of  rubber  as  now  <-oll.Tt.-d  :  </,,  j,,,  .],. 

tin-  process  adopted  by  the  natives  for  extracting  and  coagulating  tin-  milks 
juice.  C_')  Sample  of  specially  prtpOA  S.-nd  a  .-n-tain  quantity  of  l.i- 

as  it  Sows  from  the  tree,  when    incised,     s..  that   this  milk  does  not  alter  dm 
the  voyage,    add    a    -mall    quantity  of    ammonia    to    it,    and    enclose    tin-    mix- 
in  a  1'ottleor  other  hermetically  sealed  v«  .//  x////iy./  ",.,- 
>l«t<i.      Furnish   lea\e>,   tlo\\er>.  fruit,  and  seeds  of  the  tn-e  from  \\hirh  tin-  milk 
In-    I.e.-n   extracted;  indicate,  if    possible,   the  name  of  the  tree  and  specie*  to 
\\hifh   it   belongs;    and   state   season  during  which    the    samples   \\en-    collreted. 
/)»/t«-r/on8  to  be  drawn  from  above  data. — By  means  of  such  data  it   \\ould  be 

i'le    to   decide    upon    the    process    desirable   to    adopt    in    collecting    and  • 
coagulating   the    latex   under   the    most    favourable    conditions.     This   acqnii 
kno\\led^e    afterwards  diffused   by  the  government  of    the  colony,   would    under 
the  greatest  of  service  to  the  natives,  and  to  the  colony  itself,  for  it  would  imp 
to  certain  kinds  a  far  higher  value  than   what   they   no\\    posses*     <>\\in^  to  the 
enormous   number  of  rubber  trees  growing  in  equatorial  Africa,  the  rubber  trade 
of  those  countries,  and  particularly  in  French  colonies,  is  destined  to  assume  the 
greatest  developments,  but  provided  always  that  the  inoHomMtr  exported  be  of 
f//>'    I>est  quality  only.     In  that  case  alone  will    f//>    <l>ui'tn<l  increase;    and   the 
siff />///'  at*  established  on  tJie  coasts,  finding  an  assured  outlet,  would  be  disposed 
t<>  f/ive  a  hiylur  j>i-i<->  /<>r   f//c   ni/iln'r  l>r<>n<iht  by  the  MatUflMj  <ii»f  '/<  f<Ue 

f//>ir  zeal."  Bobet's  proposals,  if  carried  out,  would  l>e  a  great  step  in  advance  in 
the  improvement  of  the  raw  rubber.  But  this  would  riot  be  enough,  if,  in  face  of 
these  instructions,  a  methodical  and  critical  comparison  were  not  made  of  the 
processes  now  in  use  for  the  coagulation  of  the.  latex  and  the  preparation  of  the 
marketable  rubber.1 

Collins'  and  Hoehnel's  researches. — James  Collins  in  Great  Britain,  Dr.  F.  de 
Hoehnel  in  Germany,  and  Dittmar  in  Austria,  have  partially  taken  the  matter  in 
hand.  Taking  advantage  of  their  labours  and  exj)erience,  an  endeavour  will  be 
made  to  investigate  the  subject  as  completely  as  possible. 

Outlui'*  of  method  of  studying  coagulation. — After  outlining  the  methodical 
classification  of  the  processes  of  coagulation  generally  used,  each  of  these  in 
details,  so  as  to  draw  rational  conclusions  from  it;  as  well  as  the  result>  which  m.i\ 
be  expected  from  them  in  regard  to  the  quality  of  the  marketable  product, 
incidentally  copious  extracts  will  l>e  made  from  a  remarkable  work  by  M.  J. 
Morellet. 

Influence  of.  different  Hiet/uK.1*  of  <-<,n</ii/<i//<>n  <>u   rubber*  ''/••.///  the  tame  so > 
—Whether  the  latex  be  obtained  by  felling  or  by  tapping,  it  does  not  yield  the 
rubber  in  suspension  until  it  has  been  coagulated,  a  process  which  may  vary,  from 
one  country  to  another,  and  even  in  different  districts  of  the  same  p  and 

from  one  bank  of  a  river  to  that  on  the  other  side.  It  is  not.  therefore,  rare  for 
samples  of  rubber  from  the  same  country  and  the  same  plants  to  be  of  quite 
different  qualities  according  to  the  method  of  coagulation  adopted. 

Clax*(ti'-'iti'nt  of  <-n,t,iutnti,tlt  /»™r.wx. — But  these  di\er«-e  processes  may  be 
<  la— itied  into  four  groups,  which  may  be  further  suMivided  into  sub-group-  \\\\\\ 
some  atlinity  to  each  other.  The  following  is  a  table  of  method-  of  copulation 
now  in  use,  with  their  subdivisions,  and  the  country  in  which  each  process  is  or  has 
been  formerly  applied. 

1  The  different  Colonial  Governments  hav  u..\v  experts  on  the  spot  in  all  countries  will, 
rubber  plantations,  whose  duties,  inter  alia,  are  to  instruct  natives  how  to  collect  anil  coagu- 
late rubber. 


40 


INDIARUBBER 


TABLE  IV. CLASSIFICATION  OF  THE  DIFFERENT  METHODS  OF  COAGULATION 

OF  THE  INDIARUBBER  LATEX. 


Process. 


1.  By  heat.  a.  Artificial  heat. 


I.  Dry  heat  or  smoking. 
II.  Moist  heat. 


/3.  Natural  heat.        I.  Absorption  of  the  serum  by  the 

soil. 
II.  Absorption  of  the  serum  by  the 

human  body. 
III.  Evaporation  on  flat  surfaces. 

2.  By  creaming.  7.  Creaming  after  doubling  its  volume  with  water. 

5.  Creaming  after  standing,  addition  of  four  to  five 
times  its  volume  of  water,  drawing  off  the  liquor, 
washing,  and  pressing. 

3.  By  selection,    e.  Chemical  selection  by  mineral  reagents. 

t.  ,,  vegetable     ,, 


4.  By  natural  and  aitificial  heat  and  chemical  reaction  combined. 

5.  By  churning  or  by  centrifugal  motion. 


Locality. 


Amazonia,    New 

Caledonia. 
Mexico,    Central 

America. 
Angola. 

Congo,  Angola. 

Ceara,  Angola. 
Bahia. 
Bahia,  Congo. 


Matto  G  rosso, 
Pernambuco. 
Maranaho. 

Peru,  Guatemala, 
Nicaragua, 
Gambia,  Ma- 
dagascar, Casa- 
manza. 

Gambia,  Senegal, 
Mozambique. 


To  this  table  of  methods  there  is  added  in  No.  5  a  churning  process  proposed 
by  M.  Rousseau,  a  process  which  is  dealt  with  below. 

Process  in  ivhich  the  latex  is  coagulated  by  dry  artificial  heat  or  smoki)></ — 
Where  and  on  what  rubbers  practised. — This  process  is  adopted  in  Amazonia  to 
obtain  Para  rubber,  the  most  famous  species  of  caoutchouc,  as  regards  purity, 
nervousness,  and  elasticity.  It  is  also  adopted  in  many  other  localities,  from  Brazil 
to  Venezuela,  in  the  Guianas,  and  is  especially  used  in  extraction  of  rubber  from 
the  latex  of  the  Heveas  and  the  Micandras.  Until  the  new  order  of  things,  this 
process  is  the  best  of  all  those  hitherto  employed.  It  will  be  necessary  to  study 
it  with  care  in  its  most  minor  details,  because,  although  certain  peculiarities  may 
appear  useless  at  first  sight,  they  may  really  be  important. 

Collection  of  the  latex — Preliminary  treatment. — The  tapping  finished,  the 
collector,  or  one  of  his  assistants,  provided  with  a  bucket  or  a  large  cuya  calabash, 

surrounded  with  an  open  meshed  net  and  furnished 

^  ipggr  with   a   plaited   cord,    which   serves   as    a   handle, 

detaches  the  tigelinhas  or  goblets,  empties  them  into 
his  collecting  dish,  and  replaces  them.  He  then 
leaves  the  tree,  the  latex  of  which  he  has  just  col- 
lected, but  not  without  having  minutely  inspected 
the  incisions,  the  lips  of  which  are  often  obstructed 
by  a  pellicle  of  latex  coagulated  by  natural  heat — a 
pellicle  which  stops  the  further  flow  of  the  milky 
juice.  If  need  be,  he  pulls  off  this  pellicle,  which 
he  places  on  one  side,  on  the  rim  of  his  dish, 
refreshes  the  wound,  and  then  passes  on  to  a  second 

and  a  third  tree  to  repeat  the  same  process  until  the  bucket  is  sufficiently  full, 
the  hut  of  the  seringmiro  be  close  to  the  estrada,  the  latex  collected  is  simply 
poured  as  it  is  into  the  collecting  bucket  without  any  precaution.     But  if  the  dis- 
tance to  be  traversed  between  the  estrada  and  the  hut  be  rather  far,   the  cauchero 


FIG.  18.— Calabash  in  which 
latex  is  collected. 


METHODS   OF   OBTAINING   THE    LAT!  \.    I   TC.  11 

take-,    tin-    precaution  of  adding   about    -'i/|>er  r.-nt.-W  li.{m,|  ammonia  t..   th--   latex. 
He  thus  pi-.  \   coaL'ulation  \\hich  illicit  occur,  es|»eciallv  if   tin-  J..IIMI. 

mad--  in  ill''  li'-.it  of  the  noonday  -<in.     \Yh.n  .-i...'i_'li  has  been  collected,  the  pre- 
paration—-properly  so  called     is  proceeded  \\ith,  nam-l\. 

Smoking  the  lot,,-.     The  \\orkman,  having  pn  -vi.  .ii^ly  cleared  away  the  herb*, 

brushwood,  ami  lea\e>,  arraii'_:e-  hi>  /'/////.  //•••  ..\,-r  a  li.-artli 
duic  ..tit  of  tlit-  ground.      'I'll'1  /////«'//•'•  i-a  Laked  rarthen 
furnace    Surmounted     liy    a    >h'>rt     ei.nieal     pipe    calli-il    a 
bouillon,  of   ;i  rather  narro\\  diainrtrr,  SO  as  not  to  allow 
the  fumes  to  spread  too  far   afield.       He    tills   the    hearth 
\\ith  previously  collected  l.ranrhes  and  applies  a  li^lit.1 
l-'n'L — As   soon  as  the  smoke  disen^a^ed   is  sutli 
ciently  dense  and  thick,  a  point   which  the    Indian   a 
tain.s  by  passing  his  liand  into  it,  the   *•  /•///</""/'"   throw-* 
into   the    tire   some    previously    provided    palm    nuts    col 
lected   in  the  vicinity.      Then  >..me  more    \\ood  ;ind    nuts 
alternately.     The  latter  are  dropped  into  the  mouth  of 
the  jar  until  within   I  inches  of  the  top.     Thoc-  nuts  are 
the  fruits  of  the  Urucury  or  ^"////.<x//   palm  tree  (Attalea  FIG.  I«A. — /'«;/*<>«  or  furnace 
Mtceha  and  M'lnl'-'iria  saxifera),  which  are  also  knn\\n          for  smoking  rubber, 
in  some  localities  under  the  name  of  Garottes  de  Rocom-i. 

In  default  of  these  the  fruit  of  the   M't.rinuliana  regia  is  used.     Care  \&  taken 
to  use  a  proportional  quantity  of  wood  with  the  nuts.     It  is  only  in  the  Lower 
Ama/on — that  is,  in  the  country  where  the  preparation  of  natural  ruhticr 
most  skilfully  conducted — that  these  nuts  are  used.     Everywhere  eUe  the  twigs  of 
shrul  is  which  are  within  reach  of  the  hand  are  used  in  smoking. 

As  soon  as  the  smoke  is  given  off  abundantly  from  the  bouillon,  the  cauchero 
seizes  the  mould  or  palette,  a  wooden  instrument  having  the 
appearance  of  a  washer- woman's  beetle,2  but  the  handle  --f 
which  varies  in  length  from  about  3  to  6  feet.  He  exposes 
the  wide  flattened  end  of  this  mould  to  the  smoke  for  a 
minute,  or  moistens  it  with  water  charged  with  soft  clay,  to 
prevent  the  rubber  from  adhering  to  it,  and  then  dips  it  into 
the  bucket  tilled  with  latex,  which  lies  close  at  hand,  as  near 
to  the  / a ni'  ir<>  as  }>ossible. 

After  holding  the  mould  on  edge  for  a  sufficient  length 
of  time  to  allow  it  to  drain  sufficiently,  the  cuucht-m  quickly 
places  the  mould,  to  which  a  slight  coating  of  latex  adheres, 
in  the  smoke,  the  Hat  side  downwards,  al>out  '2  inches  above 
the  mouth  of  the  jar,  and   makes  a  motion   with  it  ;us   if  he 
1  i' .  IN;.     Mould  us.  d  were  describing  the  form  of  a  cipher,  so  that   the  current   «•! 
in    "smoking"  the  smoke  may  be  uniformly  distributed  o\er  it.     The  other  >ide 
of  the    mould   is    then    treated    in    the    >ame    \\.iy.       The    t\\,, 
faces  of  the  mould  are  thus  equally  >moked.      I'nder  the  aeti-.n 
of  the  heat  and  smoke,  the  latex  is  coagulated  almost  instantaneously,  and  a-sume- 
a  yellow  tinge ;  the  mother  liquor,  which  is  exuded  profusely,  evaporate-,  lea\inir 
on  the  mould  a  first  layer,  which,  though  feeling  firm  to  the  touch,  is  soft  and  juicy 
like  freshly  coagulated  milk.     When  the  operator  considers  the  coagulation  sntiiciriit 
and  uniform,  he  again  dips  the  mould  in  the  bucket  and  repeat*  his  continuous 

1  The  authors'  account  of  this  OJM -ratii'ii  is  rather  vague.  The  funn-iro  is  a  bottomless  jar 
18  inches  in  height.  7  iin-lii-s  di.-um-ti-r  .it  base,  and  narrowing  at  tin-  mouth  to  '2  inches.  Larger 
jars  an  used  where  a  master  employs  a  number  of  men.  The  /M//I.  iro  is  set  on  three  small 
stones  which  raise  it  above  th«-  floor,  thus  creating  a  certain  amount  of  draught,  which  causes 
tlu>  smoke  to  rise  with  some  force  and  regularity — TR. 

-The  mould  has  lircn  more,  aptly  com  pan  d  to  the  paddle  of  a  canoe,  ami,  a«  a  mat: 
fa.-t.  this  is  the  implement  most  frequently  used  on  the  Amaxun  for  a  lar--.'  quantity  of  milk, 
\  ieliling  bulky  masses  of  rubber.      In  such  crises  the  mould  is  occasionally  slung  to  the 
the  fatigue  of  working  (see  Fig.  19). — Til. 


42 


INDIARUBBER 


to-and-fro  movements  from  the  bucket  to  the  fumeiro  and  from  the  fwmeiro  to 
the  bucket,  until  the  desired  thickness  has  been  attained,  which  is  the  case  in  the 
Lower  Amazon,  when  the  cake  formed  is  the  size  of  a  military  loaf  and  weighs 
about  5  kilogrammes  (say  11  Ibs.).  He  now  frees  his  tool  by  splitting  the  block  in 
the  direction  of  its  axis,  in  the  upper  part,  with  the  point  of  a  previously  moistened 
knife,  and  recommences  the  making  of  a  fresh  block  until  the  store  of  latex  col- 
lected is  exhausted.  A  workman  can  so  prepare  2J  to  3  kilos,  (say  5f  to  6J  Ib.) 
of  rubber  in  an  hour.  The  blocks  so  split,  known  in  commerce  as  biscuits,  are 


FIG.  19. — Smoking  Para  rubber. 

still  moist.  To  dry  them,  the  workman  places  them  at  sunset  on  the  branches  of 
the  trees  close  at  hand,  and  repeats  this  operation  until  they  are  perfectly  dry, 
which  takes  several  days.  So  prepared,  the  biscuits  are  marketed  Para  fin. 
Formerly  Para  rubber  came  to  the  European  market  in  the  shape  of  animals  and 
little  figures.  The  biscuit  form  is  now  dominant. 

The  characteristic  properties  of  Para  rubber  due  to  "  smokinfi  "  ^roces.s.- — The 
most  onerous  part  of  this  method  of  coagulation  is  the  smoking,  which  is  the  essence 
of  the  process  which  gives  to  Para  rubber  that  universal,  well-deserved  reputation 
which  it  enjoys  on  our  markets  and  in  our  factories.  The  following  is  the  composi- 


METHODS   OF   OBTAINING  Till-    I  .Ml  \.    KTC. 


lion  of  tin-  iiv-.li  I. it. A  u-e.l  in  tin-  preparation  .,|  I'.ira  iii.liarnl.U-r.  Tin-  information 
is  nece^ary  l''»r  tin-  perfect  uiider-tandiiiLr  "I"  tli.-  eOOHOmy  "1"  tin-  uliOVO  pT006M  for 
obtaining  rul.IxT  from  the  latt-x  extracted  from  /A  »./x  and  Mi>'<iu<lr(U. 

TABLE  V,     AJJALYSW  01    mi    LATKX   I-SKI>  IN   I-KKIVMCINI,   l'\i:\  IM-I  MMBBKE. 


IiidianiMicr   ....... 

Putreaoible  Organic  matter  ;in« I  minn-al  matter 

\Vatn 

Aniiiionia        ....... 

,'.1  i|iiantiti,-«  up  t«»  :'.  j"  r  "-lit.  of  wliii-h 

are  adtlwl  to  th«-  liquid) 
Resinous  bodies 


: 

3-2-0 
12-0 
56'0 

fcno  . 


: :  i  M 


100-0 


fn'1-nlitiritie*  of  Para  latex  and  i»i-,,l,,triti,*  iinluc.il  t,i/  ti,- 

lary  r.'icthw  and  their  prevention.— This  latrx,  it  is  fixvly  su-know- 


FIG.  20.     Smoking  Para  rubber.     The  man  in  the  right  hand  .-OIIM  r  i>  making  Para 

Sernain>>>/. 

h-dm-d,  ha^  special  quaUtiea  wl.i.-h  no  other  latex  lias  ^,,t  :  1-ut  tlu-n.  consider  the 
raiv  exercised    in   collecting  the    latc.x,  and   at    the   precautions   in   the  method 
curin--  to  avoid    loss,  as  much  l.y  elimination  of   the   mother  liquid,  a^  by  the  ant 
Beptisation  of  the  f.-nnental.h-  or  put ivscil.le  siil-tan.  6&     The  nil.U'r  is  thus  placet 
l«-\ond  the  reach  of  se.-ondary  reactions,  and  \\\\\-  preserves  intact  aill  those  pro- 
iH-i-ties   on    \\hidi    its    reputation   depends.     Tin-   secondary  reaction    IU.M 
dreaded    is  that  due   to  all.innen.ud    fermental.l.'   or    putrescible   proteids  HI 
action    of   a    noxious  en/yme.       NTow,    at    the    very   outset,  without  any  snentit 


44  INDIARUBBER 

knowledge,  and  so  to  say  instinctively,  the  Brazilian  aborigines  found  tin:  best 
process  for  paralysing  this  enzyme. 

Effect  of  regulated  heat — Smoke  and  creosote  in  smoke. — By  methodical  and 
frequently  repeated  application  of  a  gentle  heat,  like  that  from  the  fm/icira,  the 
bulk  of  the  water  contained  in  the  serum  is  eliminated,  and  the  rubber  coagulates 
almost  instantly.  The  carbon,  produced  by  incomplete  combustion  which  con- 
stitutes the  chief  part  of  the  smoke,  is  an  energetic  antiseptic,  and  exerts  a  certain 
beneficial  influence  in  the  Brazilian  process.  But,  besides  carbon,  creosote,  a  wood- 
distillation  product  always  met  with  in  this  smoke,  is  the  antiseptic  par  excellence 
of  nitrogenous  matters,  and  it  is  to  its  action  that  the  superiority  of  the  smoking 
process  used  in  Amazonia  is  chiefly  due.  Whether  the  use  of  palm  nuts  as  fuel 
causes  a  more  energetic  production  of  antiseptic  bodies  than  the  ordinary  wood 
used  by  the  Upper  Amazonian  collectors,  is  a  moot  question  still  to  be  elucidated. 
Their  use  is  possibly  due  to  the  more  abundant  disengagement  of  smoke,  and 
thus  of  antiseptic  bodies.  Sulphur,  says  Collins,  plays  a  certain  role  in  the  prepara- 
tion of  Para  rubber.  "  I  believe  too  that  the  vapour  of  sulphur  plays  a  part  in 
the  preparation  of  some  of  the  Para  caoutchouc."  The  authors  do  not  believe  any- 
thing of  the  kind ;  leave  sulphur  its  acquired  quality  as  a  vulcaniser  of  caoutchouc  ; 
it  is  great  enough,  and  do  not  let  us  allow  it  to  intervene  inconsiderately  where  it 
has  no  footing. 

Summary. — Elimination  of  ivater. — Exclusion  of  air-bells  and  serum. — Uni- 
form distribution  of  finally  divided  antiseptics  throughout  the  mass. — By  the  oft- 
repeated  intervention  of  heat,  always  on  minimum  quantities,  the  greater  part  of 
the  water  is  eliminated  from  the  caoutchouc.  Its  presence  would  constitute  one 
reason  for  disqualification.  This  same  heat  applied  to  each  successive  coat  of 
rubber,  and  each  coat  is  infmitesimally  attenuated,  prevents  interposition  of  air- 
bells,  or  globules  of  serum,  which  might  cause  fermentation  of  the  nitrogenised 
bodies  present  in  large  quantity  in  the  latex.  Powerful  antiseptics  used  in  a 
state  of  extreme  dilution  throughout  the  mass  of  the  rubber  completely  suppress 
the  deleterious  action  of  fermentescible  nitrogenous  substances. 

Trial  of  the  smoking  process  in  New  Caledonia  and  Loyalty  Isles. — A  tentative 
imitation  of  the  smoking  process  of  Amazonia  was  used  with  great  success  by  MM. 
Grandjean  and  Weser,  concessionaires  des  Banians  de  VEtat  in  New  Caledonia 
and  the  Loyalty  Islands.  Dr.  Daville  (On  the  Colonisation  of  the  New  Hebrides, 
Paris,  1895),  says  :  "  The  extraction  process  is  most  simple,  and  requires  but  a  slight 
equipment ;  it  is  that  of  the  tigelinhas  of  Brazil.  The  operation  requires  a  conical 
elongated  gutter  in  the  form  of  a  hollow  prism  with  a  lower  edge  terminated  on 
one  side  by  a  cutting  blade,  and  on  the  other  by  a  hook.  The  blade  is  used  to 
make  the  incision  8  to  10  centimetres  (3  to  4  inches)  in  length  through  the  whole 
thickness  of  the  bark ;  the  gutter  remains  fixed  in  the  lower  part  of  the  incision, 
receives  the  juice  which  follows  the  channel,  and  thus  arrives  at  the  other  end,  to 
the  hook  of  which  is  hung  a  small  conical,  white-iron  goblet,  capable  of  con- 
taining 10  to  15  centilitres  (i.e.  100  to  150  c.c.,  or,  say,  3J  to  5  fluid  ounces). 
It  is  easy  for  the  workman  to  fix  the  goblets  at  daybreak,  and  return  three  or  four 
hours  afterwards  to  empty  them  into  a  gourd,  or,,  better  still,  into  a  white-iron  can, 
and  replace  them  on  the  tree."  The  other  operations  are  conducted  on  the  Amazon 
principle.  The  product  is  v«ry  fine  and  constitutes  a  very  valuable  rubber. 

But  in  attempting  to  apply  the  smoking  process  to  other  latices  than  Hevea, 
it  is  well  to  bear  in  mind  that  the  latex  of  Hevea  braziliensis  is  alkaline  (the 
addition  of  a  solution  of  ammonia  preserves  it  indefinitely  from  spontaneous 
coagulation).  The  coagulation  of  the  latex,  by  exposing  it  to  the  smoke  of  the  urucuri 
nuts,  is  doubtless  brought  about  partly  by  heat  and  partly  by  the  action  of  the 
acetic  acid  contained  in  it.  The  latter  and  the  creosote  further  tend  to  preserve  the 
rubber.  The  smoking  process  would  appear  to  be  only  applicable  in  the  case  of 
latex  possessing  alkaline  properties.  It  is  unsuitable  in  the  case  of  the  latex  of  the 
Castilloa  elastica,  as  this  has  an  acid  reaction  towards  litmus  paper,  hence  alkalies 
are  used. 


METHODS   OF  OBTAINING  THK    LATEX,    ETC. 


"/'  /''//•-',  f'-ii-'i  i/f' 

This  description  uf  tin-  pi-ore--  .,r  pivp.nii  ,/  ,-nd-  \\itli  -.me  detail*  of 

tin-  origin  »f  tin-  sort   culled  entreflna,  QT  Pa  .  and   finally 

,,f    that    called    >''  rii'iinbi/   or    lift  .H    \>  -i  token-Is.       From    tin-    p.-llides   ,,r   -kim  of 
rubber  taken  from    tin-    //«/»//////«/*,  or  1'nun  tin-    lips   of   tin-    inrisinn  mi  the  tne,  tin- 
collector  |in-|iiire8  a  second   sort    1»\   agglut  inat  in-j    -ueh   il.-bri-  together  on    th.    end 
of   a  handle,  so  as  to  shape    them    into  a  flattened  ball,  \\lii.-li  he  dips  fn-m  tiiu- 
time  into  fre-h   latr\,  \\hich  In-  thus  al-o  ••  -m«  -ke-  "  after  each  immei-ion.      When 
tin-  block  i>  lit'  sutlicient  si/f,  the  ca,uchero  dip-  it  -evrral  times  in  tin-  di-h 
ing  the  fresh  latex,  and  holds  the  finishing  coating  in  tin-  -moke  carh  time.      II. 
thus  gives  it   tin-  appearance  <>f  /'nrn  tin,  hut  tin-  a|.]M-arance  IB  Only  >il|*Ttirial,  and 
n»    li»ngt-r  diTrivi-s  any  one.      Tin-  lm\i-r  ha-  in.u    beOODM  diMru-ttuI,  and  >-\.nnine0 
the  t'n-sh  section.      It  is  then  seen  at  «mee   that  the  sulMamv   i>  nut    hoinogeneoilfl. 
If  tlie   j.pipertii's  of   this  substance  approach  Pom  ^»,  that  is  not  to  say  that  they 
are  identical.     There  is  a  large  quantity  of  non-eliminated  water,  a  notaUe   ; 
purl  ion  of  non-antisepticised  nitrogenous  bodies,  ruining  especially  from  the  \»>r 
tiuns  detached  from  the  lips  of  the  incision,  \\hieh  ha\e  Ixjen  coagulate.!  by  natural 
heat    al'>ne.      When   this  method  of  coagulation   is  examined,   the  inherent  defects 

•  .f  /'-//•"  <  iifi-'tiint   will    be   evident.      The    projecting   seams  of    the   inould>   on    the 
rakes   «»f    /'.//•«/    ihia  and  entrefina,  the  scraping  of  the  moulds,  the  coagulated 
residuum  of  the  latex  in  the  tigelinhas,  the  ralai  i«l  the  latex   tubs     all 
the  \\aste  products,  in  fact  —  are  made  into  blocks  which  are  jiacked  into  "n-nuned 

•  iiipty      boxes  or  old  casks;   the  whole  mass  agglutinates  into  a  block   which 

lines  the  form  of  the  receptacle  in  which  it  is  placed.     This  altogether  inferior 
kind  constitutes  the  Sernamby  or  Para  Neyroheads.     It   is   the    lea-t    \alued  of 
I'ara  rubbers,  and  justly  so.     It  is  often  very  moist,  containing  serum  and  .-M-II 
non  -coagulated    latex;    it   has   received  no  antiseptic    preparation,  and   conta 
moreover,  animal  and  vegetable  debris. 

Coagulation  by  moist  artificial  heat  or  boiling  process.  —  A  M>  ticdH  method.  — 
Description.  —  This  process,  adopted  by  the  Mexican  Indians  in  the  coagulation  of 
the  latex  of  the  Castilloas,  is  primitive  ;  whether  they  incise  the  tree  or  puncture  it, 
they  collect  the  latex  in  the  hollow  of  a  piece  of  bark  or  in  a  pot,  transfer  the  pn- 
vioiisly  strained  latex  into  a  cauldron,  and  underneath  the  cauldron  set  tire  to  some 
twigs  and  branches.  As  with  animal  milk,  there  is  formed  a  creamy  layer  which, 
on  prolonged  boiling,  coagulates,  and  the  serum  soon  separates  completely  from  the 
nil  il»er  which  it  held  in  suspension.  The  indiarubber  thus  obtained  is  spread  on  plates, 
dried  and  pressed,  to  eliminate,  as  far  as  practicable,  the  water  which  it  contain-. 

Criticism  —  Inherent  defects  —  I'/x/V/A-  iinj>nriti>  x.  —  There  is  no  need  for  a 
lengthy  examination  of  this  process  to  discover  its  weak  point*.  Moiling  dors  not 
sterilise  indefinitely  the  fermentable  and  putrescible  principles  of  the  milky  juice. 
The  compression  of  the  sheets  does  not  remove  all  the  moisture,  and  the  method 
of  obtaining  the  latex  is  not  so  carefully  gone  about  as  to  prevent  the  presence  of 
all  vegetable  and  mineral  impurities,  in  spite  of  the  straining  before  boiling.  Facts 
confirm  this  theory.  The  section  of  the  sheets  obtained  by  the  boiling  prorewea 
exposes  pockets  full  of  a  thick  greenish  liquid  embedded  in  a  blackish  rubber, 
mixed  with  sand  and  the  minute  debris  of  wood. 

Another  and  better  M.  ,-n-nn  method  —  Sea  salt  as  a  ctMyuhint.  —  Mexico  now 
produces  a  new  kind,  of  a  bright  amber-brown  colour,  from  the  same  milky  jui 
the  Castilloas,  which  when  cut  does  not  show  either  sand  or  organir  drbrk  Thi* 
remarkably  nervous  rubber,  like  Brazil  rubber,  only  loses  1'J  to  15  jK-r  rent,  in 
handling.  Data  as  to  its  preparation  are  still  awanting,  but  sea  salt  i«  possibly 
the  coagulating  and  antiseptic  isiug  reagent.  Coagulation  by  boiling  is  also  adopted 
in  lirit  ish  India,  in  the  preparation  of  the  Assam  rubber  extracted  from  the  milky 
juice  of  the  Ficus. 

Coa</»f'iti'ni  of  the  latex  by  natural  heat,  the  soil  acting  at  an  absorbent  of  f/<> 
water  and  of  the  nitrogenous  /,t/fr>.  «•//,/,    !„,'•  lined  in  the  serum  —  Chiffly 

"    IT,  x/   African  jn-ocess.—  Coagulation  by  natural  heat  is  adopted  more  especially 


46  INDIARUBBER 

in  West  Africa.  That  is  not  to  say  that  it  is  not  used  elsewhere;  but  such  pro- 
cesses, defective  in  every  way,  are  the  chief  cause  of  the  inferior  quality  of  the 
resultant  rubber,  and  the  depreciation  which  follows  as  a  natural  scipu-iK c  would 
appear  to  be  the  special  fate  of  the  Africans,  whose  indolence  is  only  equalled 
by  their  greed.  This  process  is  practised  to  a  slight  extent  by  certain  tribes  of 
the  Congo  and  Angola,  who  work  more  particularly  the  Landolphias  of  their  forests. 

Description. — According  to  Jeannest,  the  negro  of  these  coasts  is  content  to 
tap  the  tree,  caring  little  or  nothing  whether  the  wound  injures  the  plant  or  not. 
So  long  as  he  gets  what  he  wants — an  abundant  collection — other  matters  concern 
him  but  little.  The  juice  flows  naturally  on  to  a  soil  from  which  the  rubbish 
has  been  but  imperfectly  cleared.  In  the  track  which  it  thus  follows,  under  a 
scorching  sky,  the  milky  juice  at  the  outset  loses  a  portion  of  its  water.  On  the 
ground,  which  it  reaches  in  a  semi-solid  state,  it  evidently  solidifies  completely, 
giving  up  the  remainder  of  its  serum  to  the  dry  hot  soil,  which  surrounds  the 
vine  which  he  has  tapped.  All  that  he  has  now  to  do  is  to  lift  his  rubber  and 
deliver  it  to  the  dealers. 

Criticism — Defects. — Is  it  necessary  to  examine  such  a  method  critically,  and 
is  it  not  comprehensible,  without  more  ample  details,  that  a  substance  obtained 
in  such  a  summary  manner  possesses  but  few  of  the  requisite  qualities  of  market- 
able rubber  1  As  to  the  mineral  impurities,  present  so  fatally  in  the  rubber 
prepared  in  so  rudimentary  a  manner,  the  native,  instead  of  avoiding  these,  too 
often  adds  them  designedly.  If  the  earth,  acting  as  a  filter,  draws  off  the  serum 
and  the  putrescible  bodies  present  on  the  surface  of  the  mass,  aggregated  at  the 
foot  of  the  tree,  the  lower  parts  of  the  coagulum,  imprisoned  by  the  first  crust, 
preserve  all  their  serum  with  its  fermentable  elements,  whether  nitrogenous, 
saccharine,  or  resinous.  These  rubbers  must  perforce  remain  soft  and  tacky,  and 
give  off  a  nauseous  smell,  which  must  become  accentuated  afterwards.  The  waste 
in  manufacture  will  always  be  considerable. 

Coagulation  by  natural  heat ;  evaporation  on  the  human  body — Also  a  West 
African  process. — This  process,  confined  to  the  natives  of  the  West  Coast  of  Africa, 
if  picturesque,  seems  infinitely  superior  to  the  preceding. 

Description — Congo  and  Angola  process. — According  to  R.  V.  Merlon,  the 
Congo  negro,  when  he  comes  to  a  vine  which  he  desires  to  tap,  removes  what 
serves  to  him  as  clothing,  and,  having  tapped  the  tree,  collects  the  milky  juice 
in  the  palm  of  his  hand,  so  as  to  cover  the  whole  of  his  body  with  it.  This 
done,  he  returns  to  his  hut,  garbed  in  this  new  clothing,  removes  bit  by  bit  the 
portions  of  the  juice  which  the  commencement  of  cohesion  has*  rendered  consistent, 
and  makes  them  into  balls  for  the  market.  The  same  process  is  used  by  certain 
tribes  in  Angola  (Welwitsch).  After  incising  a  branch,  the  negro  places  the  palm 
of  the  hand  against  the  tree,  and  lets  the  milky  juice  flow  along  his  arm.  When 
it  is  covered  with  a  sufficiently  thick  coat,  he  draws  the  rubber  off,  as  he  would  a 
glove,  commencing  by  freeing  the  elbow,  rolling  the  rubber  on  itself  so  as  to  make 
a  pad  with  a  hole  in  the  centre,  thus  stripping  in  this  manner  first  the  forearm,  then 
the  wrist,  and  finally  the  hand. 

Criticism. — This  method,  without  being  perfect,  and  without  being  capable 
of  producing  a  rubber  exempt  from  putrescible  matter,  has  yet  the  advantage  of 
not  mixing  it  with  the  extraneous  vegetable  or  mineral  matters  so  abundant  in  the 
rubbers  previously  mentioned.  It  also  eliminates  the  greater  part  of  the  moisture 
by  coagulation  in  thin  and  often  repeated  layers,  spread  over  a  large  surface. 
This  elimination  is  stimulated  by  the  natural  heat  which  is  continuously  dis- 
engaged from  the  human  body. 

Coagulation  by  natural  heat ;  evaporation  on  flat  surfaces  other  than  the  soil — 
The  Brazilian  method  of  preparing  Ceara. — This  is  the  special  method  used  in 
Brazil  in  the  preparation  of  Ceara  rubber  (Ceara  Scraps),  obtained  from  the  latex 
of  the  Manihot  Glazowii.  This  process  is,  moreover,  frequently  used  in  West 
Africa  and  on  the  Indian  continent. 

Description. — The  following  is  the  manner  in  which  the  collectors  of  the  Brazilian 


METHODS   OF   OBTAINING  THE   LATEX,    ETC.  47 

province  .if  Ceara  \\-M-k.     The  tree,  very  like  tin-  .-a>t..r  oil  plant,  i-  wrought  a*  early 

as  till'  ihat    IB  to  say,  \\hen  tin-  diameter   of    tin-   trunk    ha>   irarhed   aUni't 

."i  inches.     The  seringueiro  clean  tin-  -round  nnmd  aUnit  tin-  foot  of  tin-  tree,  ami 

on    the    >pot     80    cleared     he    la\  -    d-i\\n    «<oine    l.aiiana     leaves,    to    i-.-i..-    the    Lit.  \. 
\\hieh   may    ll..\\  in. I.        II.-    then   >plits    th,.    Lark,   from    tli.-  f-M.t   ,,| 

tin-  tree  up  to  a  height  of  .".  f.-.-t.  in  several  place,  ami  in  ditlerent  din-ciion-..  The 
Mnnihnt  latex,  thicker  than  that  of  the  /A-/v»/x  ami  r,/>7///,  */.,-,  t|.,\\-,  H|,,\S 
only  reaches  tin-  ground  rarely,  and  then  in  minute  ijuaiitity.  The  greater  hulk 
solidities  on  the  hark  of  the  plant  and  agglutinate^  there,  as  a  long  How  of  team, 
similar  to  those  found  on  the  trees  in  our  gardens.  The  eolli-etor  leaves  them 
there  for  several  davs.  to  facilitate  drying;  he  then  detaehes  th<  either 

rolling   them    into   a   hall,  or  re  folding   them  on  them-eKes      Without  any  further 
preparation,  the  product  is  put  on  the  market  .1     '  </*. 

l>itj'-  f  nt  (jiHilifi'.t  <>/  C«tra.  The  ///•>•'  quality  i>  a  Monde  rubber,  collected  in 
the  beginning  <»f  the  season;  the  second  quality,  more  bro\\n,  is  collected  later  on. 
when  the  tirst  rains  eommenee  to  fall  ;  the  /////•»/,  eartliv  <|iialit\',  collected  at  tin- 
foot  of  the  tree,  and  consequently  often  contains  considerahh-  quantities  of  earth 
and  sand  added  accidentally,  or  intentionally,  SO  u  sometimes  to  r.-duce  the  in 
dust  rial  \ield  to  below  50  })er  cent. 

1',-itirixm  D< /.>'t*.  —A  suhstance  so  pn-pared  naturally  contains  a  quantity  of 
mineral  and  vegetable  substances  which  materially  reduce  its  value. 

Properties  of  Ceara  Rubber. — Ceara  rubber  has  a  fine,  almost  translucent  amber 
colour.     It  does  not  become  opaque  and  white,  except  under  the  action  of  en 
stretching.     This  phenomenon,  only  met  with  by  MoreUet  in  this  ela>s  of  rubber, 
is  due  to  numerous  ruptures  in  the  interior  of  the  mass,  creating  emptv  spaces, 
which  split  up  the  luminous  rays  tending  to  traverse  this  body. 

Smell. — Ceara  rubber  gives  off  a  rather  strong  smell,  and  soon  becomes  nauseous 
if  e\i>osed  to  the  combined  action  of  heat  and  moisture. 

)V'7rf. — In  the  pure  state  it  furnishes  an  industrial  yield  of  7">  to  su  p,-r  cent.. 
and  is  endowed  with  great  resistance ;  the  demand  would  be  much  greater,  if  it 
were  not  for  its  defective  preparation,  and  its  ^twm'-sophistication  by  mineral  and 
vegetable  matters,  always  present  if  in  very  variable  quantities. 

Tin'  latex  of  the  M<inilt<>t  <•,>////"/,•"/  n-ith  that  of  tlt>  J/>i>ea. — The  Mani/tut 
latex  is  at  least  equal,  if  not  superior,  to  that  of  the  Hevea.  The  quantity  of 
fermentable  nitrogenous  matter  is  lower,  the  amount  of  water  is  less,  and  yet  the 
industrial  yield  of  pure  rubber  is  only  75  to  80  per  cent.  Moreover,  the  rubber  is 
ditlieult  to  preserve,  and  requires  a  dry  cold  place;  the  putrescihle  proteic  matter 
which  it  contains  is  evidently  the  'cause.  Its  greater  consistency  renders  M>inih«t 
latex  more  dith'cult  to  handle  than  I/evea  latex,  but  the  obstacle  does  not  a 
insurmountable  ;  and  here  is  what  should  be  done  : 

,SV////rsW  ii!ij>r<>r<in,,it.  Instead  of  allowing  the  latex  to  flow  almi«:  the  plant. 
it  should  be  collected  in  ////<//////".<,  pre\  iously  furnished  with  a  little  alkaline 
water.  The  fresh  milky  juice  mixes  \\ell  with  water,  and,  better  still,  if  slightly 
alkaline,  it  could  thus  preserve  its  liquid  state  for  a  certain  time,  so  that  it 
could  l>e  coagulated  by  smoking,  so  >uc.v-sful  in  Amazonia.  The  secondary  cau-.-^ 
which  react  so  injuriously  on  Ceara  rubber  and  depreciate  its  intrinsic  value  would 
thus  be  suppressed.  This  experiment  has  been  Miecex.xfully  tried  in  Ceara. 
But  the  native  collectors  do  not  take  to  it;  it  is  too  troublesome,  and  they  prefer 
to  stick  to  their  old — more  expeditious  and  less  burdensome  i 

In  Ceara,  the  Mmiilmt  of  arid  granitic  heights  yields  a  highly  concrete,  scanty 
latex  ;  but  prospers  equally  well  on  the  plain  and  <>n  humid  ground.  The  milk  is 
more  abundant,  and  lends  itself  easily  to  the  above  treatment. 

J /"-///'  /•  siii/,/, . <f;,,n.-  -IvxjK-rimenK  might  be  made  on  the  coagulation  of  this  latex 
by  natural  heat,  aided  by  small  quantities  of  common  salt ;  this  process,  described 
a  little  further  on,  yields  quite  satisfactory  re-mi ts.  In  this  later  experiment,  the 
smaller  the  blocks  the  better  the  rubber  :  df-ic.  ation  goes  on  U-tter  the 
numerous  the  evaporation  sun 


48  INDIARUBBER 

Ceara  Sernamby. — In  Ceara,  the  Manihot  does  not  everywlierc  uniformly  yield 
rubber  latex.  Whether  the  difference  lies  in  the  climatic  or  thermal  conditions,  <n-  in 
a  degeneracy  on  the  part  of  the  plant,  certain  regions  in  which  the  Munilint  likewise 
grows  would  appear  to  be  little  capable  of  being  exploited  for  rubber.  The  tree, 
when  tapped,  only  exudes  a  few  drops  of  latex,  and  the  flow  stops  almost  instantly. 
This  barrenness  is,  however,  only  apparent.  The  incision  made  at  the  foot  of  the 
tree,  quite  near  to  the  tubercules  formed  on  the  root,  causes  a  very  abundant 
gummy  liquid  to  flow,  which  the  native  knows  very  well  how  to  put  under  contri- 
bution for  making  Ceara  Sernamby.  But  the  work  is  done  carelessly,  and 
the  product  so  obtained,  mixed  with  the  sand  and  stones  on  which  the  latex  has 
been  spread,  is  almost  unsaleable,  although  it  has  really  the  same  properties  as 
Ceara  prima.  It  would,  however,  be  easy  to  coat  the  excavation  made  in  the  soil 
before  the  incision  with  a  layer  of  moistened  clay.  The  sole  so  formed,  after 
drying,  would  rapidly  drink  up  the  mother  liquor,  and  a  rubber  would  be  thus 
obtained  quite  as  pure  and  fine  as  that  of  the  elevated  plateaux.1 

Coagulation  by  creaming  after  doubling  the  volume  of  the  latex  with  ivater, 
followed  by  more  or  less  prolonged  standing — Localities  in  which  applied. — In 
Bahia  to  the  latex  of  the  Hancornias;  in  several  localities  of  Nicaragua  and 
Central  America  to  that  of  the  Castilloas,  as  well  as  in  Assam  to  that  of  the 
Ficus. 

Description. — In  Bahia,  the  latex,  left  to  itself,  after  its  volume  has  been 
doubled  with  water,  separates  rapidly  into  two  superimposed  layers,  the  upper  part 
of  which  assumes  a  buttery  consistency ;  it  is  dried,  and,  as  soon  as  it  has  sufficient 
homogeneity,  it  is  put  on  the  market.  In  Assam,  the  rubber  so  prepared  is  gently 
heated  in  pans  to  accelerate  drying  and  render  the  product  less  humid.  In 
Central  America,  the  cakes  so  obtained  are  first  pressed  with  wooden  rolls,  which 
remove  the  excess  of  water  and  suppress  some  of  the  pores ;  sun-drying  completes 
the  process  in  fifteen  days,  when  the  rubber  is  ready  to  be  rolled  and  packed. 

Criticism — Defects. — This  rudimentary  method  yields  a  very  inferior  quality, 
which  often  loses  more  than  50  per  cent.,  especially  when  fresh.  When  cut,  not 
only  does  water — more  or  less  charged  with  foreign  bodies — escape,  but  also  a 
certain  quantity  of  uncoagulated  latex,  and  it  is  easy  to  prove  that  it  is  really  latex — 
(1)  by  the  microscope;  and  (2)  by  simply  pressing  it  between  the  index  finger  and 
thumb,  the  heat  of  the  fingers  induces  coagulation,  and  the  rubber  may  be  drawn 
out  into  elastic  filaments  by  withdrawing  the  finger  and  thumb  from  one  another. 
Hence  the  bad  repute  of  a  product  whose  effective  rubber  is  in  no  way  inferior,  in 
regard  to  elasticity  and  resistance,  to  many  other  sorts. 

Coagulation  by  standing  for  a  greater  or  less  length  of  time  after  diluting 
the  latex  with  Jive  times  its  bulk  of  water,  and  drawing  off  the  water — A  Congo 
process. — The  process,  used  for  Landolpia  latex  in  the  Congo,  consists  in  making 
incisions,  which  penetrate  just  under  the  bark  of  the  vine  without  reaching  the 
heart  of  the  plant,  because  the  latter  contains  another  milky  substance,  but  highly 
diluted  ivith  ivater  and  acid,  which  rapidly  decomposes.  The  incisions  are  longitu- 
dinal or  oblique,  and  made  the  one  below  the  other.  Underneath  the  lowest 
incision  the  native  fixes  by  means  of  potter's  earth,  or,  better  still,  semi-coagulated 
juice,  a  rather  wide,  curved  leaf,  which  leads  all  the  juice  which  flows  from  it  in  a 
thin  thread  into  a  calabash  laid  at  the  foot  of  the  tree.  The  vessel  into  which  the 
juice  flows  is  pierced  in  its  base  by  a  hole,  which  is  carefully  corked.  At  the 
moment  of  extraction  the  juice  is  fluid,  and  very  much  resembles  milk,  thickened 
by  prolonged  boiling.  To  this  juice  the  negroes  add  four  to  five  times  its  volume 
of  water. 

This  dilution,  and  also  the  influence  of  the  initial  acidification,  facilitated 
thereby,  induces  the  hydrocarbide  elements  to  solidify  on  the  surface  into  a  sort  of 
thick  cream ;  twenty-four  hours  afterwards  the  cork  which  closed  the  inferior  orifice 

1  The  Manihot  is  being  cultivated  in  Mozambique  on  the  large  scale,  and  the  trees  tapped 
and  the  latex  prepared  with  all  the  care  that  science,  backed  by  abundant  capital,  can 
command. 


METHODS  OF  OBTAINING  Till-    LATEX,    ET<  49 


of  tin-  calal-a-h  is  reino\ed,  the  a'pieou-  |Mirtinii  tlou-  ,iuay,  and  with  it  the  major 

portions  of  the   piitr.->ciM.-  dements;   the  rubber  remain*  at  the  lx<ttom  of  the 

in  a  si  -mi-  tluiil  state.     To  hasten  coagulation,  the  negroes  pour  it  into  wooden 

.  ami  expose  it   \<>  the  air  for  some  h 

Tin-  solidification  i>   then   more  advanced  \\iihmit  being  complete.     It  i-.  tin- 
moment  \shich  tlu-  negrne^  tl  ink  opportune  for  kneading  it  into  liallri. 
KM  rubber  which  fa    found    in    the    bottom    of    tin-    \e  —  -l>    [|    t  .....  -..n   ;-t.-nt  t..  I.  ml 
itself  ea-il\  ti»  kneading.      It    i-   tlien   cut    into  small   euU-M  or  tliiuiMe-  (  lu-u.v  tl,,- 
comni'Tcial  name  of  ////WVrx). 

<'ritii-i.tiii      /)'(><•?.<.      This    method,    like    the    preceding.    incor|M,  rates    with   the 
rubber  a  certain  quantity  of  serum,  and  even  of  undeei  imposed  latex,  and  • 
quently  fermentaM.-  -ul>-tances  which   s  .....  i  impart  a  characteristic  nauseous  odour 
t»    the<e    sorts.      Nothing    is   done,    uith    the   exception   of   im|H.»rfert    wa-h. 
sterilise  these  substances  and   prevent  ulterior   decomposition.      The    rul.l 
produced,  has  therefore  all  the  inherent  defects  of  the  method.      Its  yield  does  not 
HBOeed  <><>  per  cent.      The   product    is   very  spongy,  and   contain-   in   the  numeroUM 
vesicles  .if  the  paste  a  whitish  liquid,  which  eventually  generates  the  repulsive  smell 
already  mentioned.      Other  samples  of  rubber,  prepared  more  rationally    from  the 
latex    of    the-c    same  Lnmln/jJit'mt,  are    exempt    from    the--  and    our    tln-ir 

qualities  to  the  method  of  coagulation. 

Coagulation    by   chemical  mean*  —  J>i/    mineral  reagents-    A/  i»»tk 

A/rt'-'t  and  America.  —  This  process  is  as  expedition-  as  it  i-  easy,  It  i-  not 
wonderful,  therefore,  to  find  it  practised  both  in  Africa  and  in  America.  1'ernam- 
buco,  Maranhao,  and  -certain  rubbers  of  the  Ivory  Coast  and  Cameroons,  are  »o 
prepared. 

Coatjtilntinn  by  alum—  The  Strauss  method  —  Description.-  Tin-  process,  used 
in  I'ernamluico  for  coagulating  Hancornia  latex,  bears  the  name  of  its  inventor, 
Henry  Anthony  Strauss.  It  consists  in  pouring  into  the  latex  an  aqueous  solution 
of  potash  alum;  coagulation  is  effected  almost  immediately.  The  coagulum  is  then 
allowed  to  drain  for  eight  days  on  wattles  arranged  for  the  purpose.  The  mnnnon 
so  prejmred  are  divided  into  small  fragments,  sun-dried  for  a  month,  and  put  «»n 
the  market  in  that  condition. 

f'l-itirfx/n  —  Defects.  —  Strauss's  process  is  ingenious  (Morellet),  but  the  results 
of  its  application  are  bad,  and  the  authors  in  no  way  share  the  enthu-ia-m  ••! 
J.  Collins  for  this  method  of  coagulation.  "  This  method,  purchased  by  the 
Government  of  the  province  of  Pernambuco,  is  very  much  approved,"  he  says, 
"the  more  as  it  may  be  performed  far  from  the  place  of  collection,  ami  that  it  is 
always  done  in  the  cold  state."  The  rubber  so  prepared  goes  wrong  as  it  ages, 
chaniriui:  into  ;i  substance  the  market  value  of  which  is  very  }>oor  :  a  piece  of 
Manual  »'ira  of  sufficient  elasticity  at  the  outset  becomes  transformed  into  a  sort  of 
badquality  millboard,  incapable  of  resisting  strain,and  without  any  elasticity:  itsmole- 
cular  state  is  so  far  modified  as  to  render  it  granular  and  friable.  The  rubber,  of  a 
rose  colour  both  interiorly  and  exteriorly,  is  covered  with  a  crystalline  effloresce; 
alum.1  When  cut,  the  section  shows  a  large  number  of  pockets,  tilled  with  water,  not 
only  from  the  serum  imprisoned  in  the  mass  by  instantaneous  coagulation,  but  al>o 
and  more  especially  from  the  solution  of  alum  used  in  the  process.  It  would  be  easy 
to  separate  a  portion  of  the  alum  water  by  the  press  ;  but,  even  so,  the  collector  has 
not  always  a  press  at  his  disposal  ;  and  if  he  had,  elimination  would  be  very 
incomplete,  and  the  deleterious  action  of  alum  would  always  make  itselt  t»-lt. 
manual  labour  be  economised  during  collection,  the  product  is  deteriorated,  and 
the  cost  of  freight  is  in  no  way  diminished  ;  it  is  almost  doubled,  since  the  rubber 
often  yields  as  much  as  60  per  cent,  of  water. 

It  is  not  likely  that  coagulation  by  alum  will  advance  in  the  future.  Manu- 
facturers agree  as  to  the  bad  quality  of  the  products,  and  tend  more  and  more  to 
reject  them,  as  appears  from  the  following:  — 

1  The  defects  of  this  process  are  i-vid.Mitly  din-  t..  th.-  lunn.itioii  ..f  resinates,  etc.,  of  alumina. 
The  otllorescence  points  to  too  strong  solutions,  as  well  as  inijicrfect  washing.—  Tm. 

4 


50  INDIARUBBER 

"Mangabeira  rubber  is  obtained  from  the  trees  of  that  name  [species  of  Jl<tn- 
cornia],  found  in  large  numbers  in  the  interior  of  Pernambuco,  as  well  as  of  the  other 
northern  provinces.  The  reports  which  I  hear  have  been  received  from  Liverpool  of 
the  reception  of  this  article  are  far  from  favourable ;  the  price  went  up  to  2s.  7d. 
per  lb.,  but  has  fallen  again,  and  it  would  appear  that  Is.  per  Ib.  is  about  the  price 
obtainable  in  England  in  ordinary  times.  The  method  employed  in  the  prepara- 
tion of  the  rubber  is  very  primitive,  and,  I  think,  may  easily  account  for  the 
article  not  being  well  received.  If  the  milk  were  treated  in  a  more  careful  manner, 
there  seems  no  reason  why  the  rubber  should  not  be  favourably  received.  At 
present  the  plan  adopted  is  simply  to  mix  alum  with  the  milk,  which  causes  it  to 
coagulate ;  the  lumps  of  rubber  are  then  placed  in  the  sun,  after  which  they  are 
sent  to  the  market.  From  the  defective  mode  of  preparation  a  great  loss  of  weight 
afterwards  occurs,  frequently  as  much  as  40  to  50  per  cent.,  some  say  even  more. 

"  From  Bahia  and  Pernambuco,  in  Brazil,  comes  a  rubber  of  a  different  grade 
from  that  of  Para.  It  is  cured  with  alum  and  water.  The  Pernambuco  comes  in 
sheets,  and  is  of  yellowish  white  tint ;  that  from  Bahia  is  not  so  good,  and  comes 
in  round  balls.  The  principal  objection  to  it  is  that  it  is  very  damp,  entailing  a 
large  loss  to  the  importer  from  shrinkage. 

"  Of  Mangabeira  rubber  there  are  three  grades,  very  similar  to  the  Bahia  and 
Pernambuco  sorts.  A  grade  that  has  a  red  look  is  considered  superior,  and  sells 
for  five  or  ten  cents  per  pound  higher  than  the  others." 

2.  Coagulation  by  sulphuric  acid  and  common  salt — Description. — (1)  Sulphuric 
acid. — In  Maranho  and  Matto  Grosso  alum  is  replaced — as  a  coagulant — by  dilute 
sulphuric  acid.     Sulphuric  acid,  like  all  acids,  is  an  energetic  coagulating  agent. 
But,  besides  the  well-known  transport  difficulties,  it  coagulates  the  juice  too  rapidly, 
and  thus  does  not  sufficiently  eliminate  the  mother  liquor.     Moreover,  the  acids  do 
not  possess  antiseptic  properties ;  and  it  must  be  condemned  for  reasons  already 
mentioned.     (2)  Common  salt.  — A  solution  of  common  salt  also  possesses  coagulat- 
ing properties ;  its  antiseptic  power  is  well  known,  and  it  does  not  present  the  same 
transport  difficulties  as  dilute  sulphuric  acid.     The  use  of   acidulated  water  has 
thus  been  generally  replaced  by  common  salt  in  the  two  provinces  mentioned  above. 
The  use  of  common  salt  alone  would  be  rather  to  be  recommended  if  no  better 
process  were  at  the  disposal  of  the  collector,  but  it  has  the  defect  of  leaving  a  large 
quantity  of  ivater   in  the  rubber.     Certain  Ivory  Coast,  Cameroon,  and    Congo 
rubbers  are  likewise  coagulated  by  salt  water.     There  is  thus  a  great  resemblance 
between  such  rubbers  and  the  American  rubbers  just  mentioned. 

3.  Coagulations  by  an  aqueous  solution   of  soap  —  Description.  —  Between 
coagulation  by  mineral  reagents  and  by  vegetable  reagents  a  special  method  of 
coagulation,  sometimes  adopted  in  Peru,  for  the  Hancornia  latex,  intervenes,  and  in 
which  a  soap  solution  acts  as  coagulant.     To  coagulate  the  milk,  it  is  either  poured 
into  a  vessel  or  into  holes  in  the  clay  soil,  containing  about  30  kilogrammes  (say  66 
Ibs.)  of  liquid.     The  night  before,  125  grammes  (about  4J  oz.)  of  soap  are  dissolved 
in  a  bucket  of  water.     Two  buckets  of  this  solution  coagulate  about  30  kilogrammes 
(say  66   Ibs.)  of   rubber  in  the  space  of  half  an  hour.     As  soon  as  coagulation 
commences,  the  milk  is  beaten  with  the  flat  of  the  hand  to  facilitate  the  operation. 
"  The   indiarubber   is  afterwards   taken  away  in  the   form  of   a  block,  which  is 
punctured  here  and  there  with  a  knife  to  free  it  from  water.     The  punctures  are 
not  made  very  deeply,  so  as  not  to  diminish  the  weight  of  the  rubber  "  (E.  Bard). 

Criticism. — The  rubbers  so  made  are  naturally  very  porous,  and  this  rudi- 
mentary method  often  brings  in  its  train  a  considerable  quantity  of  extraneous 
matter.  As  to  the  action  of  the  soap  solution  by  itself,  it  is  difficult  to  understand. 
Possibly  it  acts  in  this  case  purely  and  simply  by  the  mass  of  water  which  it 
contains,  and  that  it  is  the  water,  as  in  the  previously  mentioned  processes,  which 
sets  the  rubber  globules  free  from  the  too  dense  latex,  and  thus  enables  them  to 
aggregate  more  easily  on  the  surface  of  the  liquid.  The  method  of  collecting  and 
preparing  rubber  in  Peru  is  to  fell  the  tree  and  cut  it  into  pieces,  limbs  and  all, 
and  let  the  milk  run  out  from  the  wood  into  holes  dug  in  the  ground.  It  is  then 


METHODS  OF  OBTAINING  THE   LATEX,    II 

eoagulated  in  these  p"oU  l»y  mixing  it  \\itliunlin.,  It  pi-ndm-i-  ,i  iu-,,t  vil. - 

smelling  compound  \\hirh  M-IU  at  about  thr  same  pri--,-  a  ,'immhy. 

Ctwmical    (•<>•  i </ii/' if  /' > n    i>ij     > ••  •  />  f> i1'!'     / •" i</>  // 1»  —  Countries    where    prao 
and  nature  •  >/  reagent*     <'/?,-/'<•  «  .•««/•/*//.//»/.     This  method  of  coagulat- 

ing thr  latex  is  practiced  in  t lie  case  of  some  Madagascar  nil »U -is,  in  (iaml.M 
(iuatemala,  and  N  iearagua.     S.  .met  init-  >  it  is  a  vegetable  acid  \\  hirh  u  1 1  •  i  \  ciien,  aom*- 

lillies  it   is  tlir  infusion  .if  a  Nestable  product  of   indeterminate  rhriniritl  ri>l||]Mi-.iti»ii, 

Init   \\hich    very   likely   owes   it-  n.agulating  p<>\\ei    t..  its  nior. 

acidity.  Thr  African  rubbers  just  mentioned  would  appear  I,M-.,III.-  I'n.iii  tin-  <*ugula- 
t'on  -if  tlir  I.  tixloljJt  ias  by  citric  acid.  "  In  thr  OOOTSe  of  our  examinat  i..n^  wo  have 
often  observed,  in  thr  nil"  In.in  Madaga-  MI  ,  -rrd>  witli  an  anat  r.,|-,i^  ovule 

\\ith  a  rlrarly  marked  chalaza,  seeds  certainly  of  tlir  j  /,/,/„//,/,•,,/.     \\,  did  not  at 
first  und'TMand  li««\v  these  seeds  could  be  mixrd  \\iili  thr  indi.iriil.U-r  JKI-- 
tliry  \vriv  mrt  with  too  frequently  to  l>r  fortuitous,  and  \\e  wen-  f"i  ncludr 

that  their  }>resence  was  due  to  the  methods  of  coagulation,  that  they  uned  thr  jui«-.-  .,t 
the  fruits  of  tin  Ani-'infnicecet  and  that  citric  acid  was  the  coagulating  agent  Tin- 
opinion  was  corroborated  by  the  testimony  of  IKM'SOIIH  who  had  travelled  in 
those  countries'1  (Morellet). 

Criticism — Defects. — Si.  Cousin  states  that  he  obtained  with  this  method,  during 
his  stay  at  Casamanca,  a  superior  quality  of  rubber  of  a  fine  amber  nhade,  im-lining 
to  a  bright  horn  colour,  almost  translucid,  very  sensitive,  and  of  remarkable 
elasticity.  Until  proof  to  the  contrary  is  forthcoming,  this  assertion  may  be 
doubted  :  if  mineral  acids  produce  too  rapid  a  coagulation,  thus  facilitating  the 
imprisonment  in  the  mass  of  rubber  of  too  large  a  quantity  of  mother  liquor  and 
fermentable  bodies,  vegetable  acids  have  the  same  defect,  and  are  the  natural  hot- 
beds of  microbe  culture  hastening  the  putrefaction.  It  is  inq>ossible  to  In-li- 
the excellence  of  a  process  where  this  new  drawback  has  to  be  added  to  thoae 
already  pointed  out  in  coagulation  by  mineral  acids.1 

Citric  Acid  replaced  by  sulphuric  acid  in  Madagascar. — In  Madagascar,  ^ 
citric  acid  was  at  first  extensively  used  for  this  purpose,  it  haa  now  been  cornplet.  1\ 
replaced  by  the  sulphuric  acid  introduced  by  the  Europeans. 

South  American  Practice. — In  Peru,  Hancornia  juice  is  sometimes  coagulated 
by  means  of  the  juice  of  a  climber  called  Sachaacamote  by  the  caucherot  of  the 
country,  likewise  the  latex  of  the  Castilloas  of  Guatemala  and  Nicaragua,  the 
coagulation  of  which  is  effected  by  an  infusion  of  the  tuberous  root  of  a  convolvulus, 
the  i/><»iiea  bona  HOJC,  numerous  varieties  of  which  grow  in  Central  America.  The 
den  imposition  of  the  milk  is  effected  by  means  of  an  undetermined  organic  acid, 
hut  the  rubber  resulting  from  the  reaction  is  intimately  mixed  with  a  foreign 
resin,  which  not  only  reduces  the  industrial  yield,  but  which,  mixed  up  in  the  paste, 
is  difficult  to  eliminate,  and  an  obstacle  in  manufacture.  Plants  producing  the 
so  manipulated,  yield  under  other  and  different  conditions  a  very  elastic,  sensitive, 
and  profitable  product.  This  leads  incidentally  to  the  exi>eriiuents  of  Dr.  Morisae 
(member  of  the  expedition  of  the  Upper  Orinoco,  led  in  1889  by  Count  Kntier)  on 
different  methods  of  treating  the  latex  of  the  Heveas. 

£.'•/.•  i-i'ntents  on  Hevea  Latex. — "Choosing  preferentially  reagent-  capal-le  Q| 
rapidly  coagulating  without  injuring  the  quality  of  the  rubber,  Dr.  Morisae  used 
different  products  which  yielded  the  following  results: — 

(1)  "One  volume  of  90  p«r  cent,  alcohol  coagulates  G  volumes  of  latex,  yielding 
.1  tine  superb  rubber  of  brilliant  whiteness,  and  yellowing  but  slightly  on  ageing, 
but  the  dearness  of  alcohol  and  its  feeble  coagulating  i*)wer  put*  it  out  of  the 
reckoning.'2  Liquid  perchloride  of  iron  coagulates  in  the  proportion  of  1  to  9  of 
latex.  The  rubber  so  obtained  is  a  coarse  powder  with  an  ugly.  «  irthy  appearance, 

1  Coagulation  by  acids— mineral  or  vegetable— in  modern  rubber  plantations  where  the 
rubber  is  forthwith  put  through  a  washing  machine,  is  scarcely  subject  to  the  above  criticism. 
Translator's  note  to  2nd  English  edition. 

-  This  coagulating  power  of  alcohol  contradicts  lire's  results,  but  it  is  hard  t 
tK-  identity  of  the  actual  latices  he  tested.     Translator's  note  to  2nd  English  edition. 


52  INDIARUBBER 

the  molecules  of  which  have  little  cohesion  between  themselves.  (2)  One  volume  of 
an  alcoholic  solution  of  corrosive  sublimate  coagulates  11  volumes  of  milk,  and 
yields  good  rubber.  (3)  One  volume  of  chloride  of  calcium  coagulates  15  of  milk, 
but  this  deliquescent  salt  is  difficult  to  preserve  in  a  region  where  the  air  is 
constantly  charged  with  humidity.  (4)  Monohydrated  hydrochloric  acid  has  a 
coagulative  power  of  1  to  5.  Commercial  nitric  acid  is  still  more  feeble.  (5)  Nou- 
crystalline  commercial  carbolic  acid  has  a  coagulating  power  of  1  to  18.  But  the 
most  wonderful  of  the  coagulants  hitherto  tested  is  commercial  sulphuric  acid.  An 
aqueous  solution  of  J^  coagulates  10  of  milk,  and  this  coagulating  power  extends  as 
far  as  TJ^,  but  more  slowly  and  by  stirring  the  mixture.  (6)  Tincture  of  iodine 
would  not  appear  to  coagulate  except  in  virtue  of  the  alcohol  which  it  contains. 
The  other  reagents  tested  gave  no  appreciable  result.  Amongst  these  were  the 
carbonates  and  bicarbonates  of  potash  and  soda,  chloride  of  sodium,  the  bromides  of 
potassium,  sodium,  and  ammonium  ;  ammonia,  ether,  chloroform,  carbon  disidphide, 
glycerine,  permanganate  of  potash,  arsenious  acid,  etc.-  (7)  Alum,  used  successfully 
with  some  indiarubber  trees,  gave  negative  results  with  the  milk  of  the  Hevea. 

"  Defects  of  sulphuric  acid  coagulation. — The  first  sheets  prepared  by  sulphuric 
acid  coagulation  were  at  once  attacked  by  insects  and  cryptogams,  the  rapid 
development  of  which,  in  the  interior  as  well  as  on  the  surface,  spoiled  the  appear- 
ance and  quality  of  the  rubber. 

"  Coagulation  by  a  mixture  of  sulphuric  acid  and  an  antiseptic. — Dr.  Morisse 
then  mixed  the  sulphuric  acid  with  an  antiseptic,  the  action  of  which  was  most 
lasting,  and  carbolic  acid  possessing  in  itself  a  rather  high  coagulating  power  gave 
him  full  satisfaction.  Traces  of  carbolic  acid  sufficient  to  ensure  sterilisation  do 
not  disappear  from  the  surface  until  after  six  months  from  the  date  of  coagulation. 
But  desiccation  is  then  so  far  complete  that  injurious  fermentation  is  no  longer  to 
be  feared.  The  final  definite  formulae  deduced  from  the  results  of  numerous 
experiments  are  as  follows  : — 

{Commercial  carbolic  acid         .....       4  Grammes.1 
Alcohol  in  sufficient  quantity  to  dissolve  the  carbolic  acid. 
Water  .  .....     80         ,, 

84 
( Commercial  sulphuric  acid       .  .  .  .  2         ,, 

Solution  B        .  J  Water  • 

I  22 

How  to  use  J/omse's  Coagulants. — "Mix  the  two  solutions  before  use.  This 
quantity  of  mixture  instantly  coagulates  a  litre  of  milk  by  the  aid  of  slight  agita- 
tion. Even  a  mixed  solution  of  -^  for  the  first  acid  and  ^  for  the  second  is 
sufficient  in  ordinary  weather,-  but  the  hour  at  which  the  work  is  done  must  be 
taken  into  account,  the  temperature,  the  hygrometric  state  of  the  air,  have  an 
incontestable  influence  on  coagulation.  In  fact,  on  certain  days  it  is  effected  slowly 
and  with  difficulty  with  the  second  solution.  It  is  therefore  advisable  only  to  put 
the  strong  solutions  A  and  B  into  the  hands  of  the  operators. 

"  Cost  of  coagulants  a  negligible  quantity. — In  order  therefore  to  coagulate 
and  asepticise  a  ton,  say  1000  litres,  2  litres  of  sulphuric  acid  and  4  litres  of  non- 
crystalline  carbolic  acid  would  be  required.  The  cost  of  chemical  coagulants  may 
therefore  be  completely  neglected.2  One  hundred  kilogrammes  of  Para  rubber 
were  obtained  by  this  process,  white,  hard,  resistant,  compact,  and  pleasant  to  the 
eye.  The  practical  proof  of  the  success  of  the  process  has  thus  been  demonstrated. 
It  results  from  the  preceding  that  the  reagents  capable  of  coagulating  the 

1  T^"8  &ives  a  total  of  106  grammes  ;  and  as  that  amount  precipitates  1000  grammes,  106 
OZl  J"}J  also  P^cipitate  1000  oz.,  that  is  as  near  as  may  be  17  oz.  to  1  gallon.— TR. 

The  figures  in  the  formula  are  given  by  weight ;  but  in  this  calculation  by  measure  this 
lead  to  error,  as  carbolic  acid  is  rather  heavier  than  water,  sp.  gravity   1-060;  whilst 
icentrated  sulphuric  acid,  sp.  gravity  1-840,  is  nearly  twice  the  weight  of  water.— TR. 


METHODS   OF   OBTAINING  THE   LATEX,    ETC.  53 

t  certain  plant>  ha\e  no  effect  on  the  latex  of  the  J/ewt.     Moreover,  it  does 

not  appear  to  us  that  attempts  to  substitute  a  ne\\   met!,    •  .-illation  for  the 

smoking  process  -hould  !.«•  encouraged.  The  collectors  \\..uli|  pi.,l,al,l\  readily 
take  t«.  any  process  of  simplifying  tin-  \<>ng  ami  toKom  "|*-,.it ion  ••!  -linking  but 
\se  need  not  study  their  convenience  but  rather  the  result  obtained.  Now  we 
have  determined  that  rubl>er  prepared  l»y  the  addition  of  r.-rt.nn  Holution*  w  of 
inferior  quality,  etc.  etc." 

The  authors  perfectly  agree  with  M.  Koiwseau  on  the  value  of  the  procem 
published  by  Morisse.  Para  rubber  owes  its  excellent  quality  especially  to  it- 
dilticult  method  of  [reparation;  full  of  minute  details,  to  depart  from  it  \\'i.uld  I*. 
to  court  inevitable  mistakes,  which  would  resolve  themselves  into  <  !.  |.,^ 

of  money.     Moreover,  they  have  no  faith  in  the  antiseptic  action  of  carU>Ii 

be  alone,  applied  on  each    layer   l.y   aid   of  a  jjentle   heat,  i.   capaMr   ..i    pro 
during  c(»inplcte  sterilisation  and  of  destroying  tin-  secondary  influences  to 
we  have  already  referred. 

I.   t',,  ,1,1  ill  tit  ion  by  natural  or  artificial  heat   and  ctiemical   coagulation 
i, in •  •/    -I'nictised  in  M<>:,iin'>i<fue. — The  reader's  special  attention  is  drawn  to  this 
method,  and  the  reasons  for  so  doing  will  be  given  after  having  described   the 
The  milk  of  the  Landolphias  and  other  vines  in  Gambia  (Casamanca, 
I  \ory  i  oa>t)  and  Mozambique  is  coagulated  as  follows  : — 

Description. — The  collector  taps  the  vines  very  slightly;  he  somewhat  brains 
the  bark.  The  shallow  incisions  are  5  to  6  centimetres  long  (say  about  i 
iiiehex),  their  width  varies  \vith  the  size  of  the  vine;  the  incisions  are  very  close 
to^etlirr,  about  4  inches  apart.  After  the  bark  is  cut  the  latex  soon  exudes,  white 
and  thick.  The  native,  by  aid  of  a  shell,  immediately  besprinkles  each  inri>ion 
with  a  little  salt  \\ater,  which  dissociates  the  serum  from  the  rubber.  The  latter 
is  instantaneously  coagulated  into  small  lump.  These  the  collector  draws  off  each 
incision  to  form  a  kind  of  nucleus,  which  he  rolls  between  his  hands.  He  draws 
the  nucleus  to  him,  and  the  latex,  continuing  to  flow  and  solidify,  is  drawn  out 
into  filaments.  There  are  thus  as  many  filaments  as  there  are  incisions.  The 
nati\e,  as  he  draws  these  filaments  to  him,  winds  them  on  to  the  initial  small 
niK  lens,  moistening  the  incisions  from  time  to  time  with  salt  water.  The  traction 
and  subsequent  compression  between  the  fingers  causes  the  central  filaments  to 
eoalesee  as  they  are  covered.  The  threads  are  apparent  only  on  the  outside;  only 
a  small  part  of  these  balls  can  be  afterwards  unwound.  Almost  white  in  the 
U'^inning,  the  envelope  of  rubber  browns  with  time,  and  turns  reddish.  The 
weight  of  the  balls  varies  between  300  and  800  grammes  (roughly,  between 
10J  and  '28  oz.),  but  the  negro  sometimes  makes  maasefl  of  more  than  *J  kilo- 
grammes (say  4J  Ibs.).  As  these  balls  are  very  bulky,  and  as  the  workman 
cannot  easily  hold  them  between  the  fingers,  he  lies  on  the  flat  of  his  back  and 
continues  to  wind  the  rubber,  supporting  the  ball  with  his  hands  and  the  pit  of 
•  mach.  The  operation  is  continued  until  the  flow  of  juice  is  <-\h 

(Chapel). 

('i-ifirifsiH  —  Mirit*  ,,t'  tlf  /traces*. — This  process,  where  natural  and  artificial 
heat  as  well  as  a  powerful  antiseptic,  common  salt,  are  constantly  coming  in 
contact  with  the  most  infinitesimal  quantities  of  rubber,  is  very  useful  where 
smoking  is  not  possible,  either  on  account  of  the  local  dispositions  of  the  country 
which  yields  the  latex,  or  on  account  of  the  more  or  less  thick  nature  of  the 
•aerated  juice.  Kadi  filament  is  in  contact  both  with  the  exterior  air  and  the 
hand  of  the  operator;  the  evaporation  of  the  serum  is  thus  greatly  facilitated 
whilst  the  common  salt  is  constantly  ant iseptieising  the  whole.  The  operation  ia 
tiresome,  yet  if  Nature  be  bountiful  in  furnishing  us  with  raw  materials  for  our 
industries,  it  involves  a  certain  effort  on  our  part  to  profit  as  far  as  possible  there- 
from. C'oul -mining  is  laborious  and  metals  are  not  obtained  without  great  effort  ; 
no  one  complains  of  the  total  work  exjK-nded  if  the  result  be  profitable. 

Purity  <>f  f//<-  jn-ixhtct — Bad  effect  of  natives'  malpractices. — This  process 
has  another  advantage :  it  facilitates  the  production  of  a  rather  pure  product, 


54  INDIARUBBER 

without  admixture  of  extraneous  mineral  or  vegetable  matter,  unless  the  collector 
feels  bound  to  add  these  substances  to  increase  the  weight  of  the  goods.  But  the 
buyer  will  do  justice  to  such  misdeeds,  and  the  natives  cannot  be  too  much 
admonished  against  their  very  marked  tendencies  towards  these  malpractices. 
Ill-repute  rapidly  strikes  their  raw  material,  and  it  is  always  difficult,  and 
sometimes  impossible,  to  induce  the  trader  to  resume  the  route  which  he  has 
abandoned  on  accounts  of  a  bad  deal. 

5.  Separation  of  the  indiarubber  by  churning — The  process  inherently  de- 
fective.— A  few  lines  are  devoted  to  the  method  proposed  by  M.  Rousseau  for 
coagulation  by  simple  churning.  The  notion  is  seducing :  to  churn  the  latex,  as 
cream  is  churned  in  butter-making,  is  an  easy  enough  operation,  but  it  has  a  grave 
defect  which  will  never  allow  of  this  conception  being  adopted  in  actual  practice. 
Butter,  once  separated  from  the  butter-milk,  abandons  by  a  slight  pressure — 
whether  mechanical  or  by  hand — almost  all  the  serum  which  it  has  imprisoned ; 
kneading  with  table-salt  antiseptici  ses  it  for  some  time,  but  rubber  does  not  yield 
to  pressure  or  kneading  in  the  same  way  without  sufficient  desiccation  and  anti- 
septisation.  The  rubber  thus  obtained,  even  with  the  best  juices,  would  have  all 
the  previously  mentioned  defects. 

Summary  of  the  best  methods  adopted  for  obtaining  raw  rubber — (1)  The 
process  must  vary  with  the  density  of  the  latex. — In  choosing  a  rational  method  for 
coagulating  the  latex,  regard  must  always  be  had  to  the  density  of  the  juice.  The 
Landolphias  and  Manihots  yield  a  thicker  milk  than  the  Heveas,  the  Castilloas, 
and  the  Ficus,  and  the  same  method  of  coagulation  cannot  be  used  indiscrimin- 
ately. 

(2)  A  pure  product  always  to  be  aimed  at. — It  is  necessary,  whatever  process 
may  be  adopted,  not  to  forget   that  the  object  of   coagulation  is  to  produce   an 
article  as  exempt  from  water  and  fermentable  substances  as  possible,  whilst  it  at 
the  same  time  frees  it  from  all  inert  foreign  bodies,  which  can  only  impart  to  the 
product  a  sophisticated  appearance,  which  perceptibly  depreciates  it,  whether  the 
addition  be  intentional  or  not. 

Processes  recommended. — From  this  point  of  view,  two  coagulation  methods 
specially  recommend  themselves  to  the  attention  of  collectors,  namely,  that  marked 
1  a  I.  Coagulation  by  artificial  heat  or  smoking ;  and  4.  Coagulation  by  natural 
or  artificial  heat,  ivith  the  intervention  of  common  salt. 

(3)  Injurious  action  of  acids  and  alum  and  dilution  with  water. — The  use  of 
acids — mineral  or  vegetable — that  of  alum,  as  well  as  the  addition  of  water  in  any 
form,  are  always  injurious  to  the  quality  of  the  product,  and  ought  to  be  carefully 
avoided  in  coagulation  processes. 

(4)  Influence  of  shape  and   size. — The  size  and  shape  given  to  the  mass   of 
rubber  is  not  without  its  influence  on  the  quality  of  the  product,  and  we  have 
often  remarked,  chiefly  in  the  methods  in  which   an  aqueous    liquid  intervenes, 
that  the  product  is  more  defective  the  greater  its  bulk.     This  is  easily  explained. 
The  more  the  surfaces  are  renewed  in  the  drying  of  the  same  quantity  of  matter, 
the  greater   is    the   evaporation,  the   rubber   gains   in    quality,  and   the   greater 
desiccation  diminishes  the  ulterior  action  of  ferments. 

(5)  Evil   effect  of  mixing  the  milk  of  different  trees. — In  order    to  obtain  a 
rubber  endowed  with  the  maximum  of  good  qualities  which  a  latex  is  capable  of 
producing,  it  is  necessary  to  carefully  avoid  mixing  the  milks  of   different  rubber 
trees :    for  one   reason   or  another,  the  one  is  always  inferior  to  the  other  with 
which  it  is  associated.     In  such  a  mixture  the  inferior  sort  always  reacts  on  its 
neighbour,    and   not    only   depreciates    its   value,    but   its    properties   are   really 
more  or  less  altered. 

(6)  The  desirability  of  ascertaining  the  chemical  composition  of  the  latex. — A 
knowledge  of  the  exact  composition  of  the  latex  of  each  species  would  aid  greatly 
in  the  selection  of  the  best  method  for  coagulation  of  each  individual  rubber. 

Absence  of  data. — Unfortunately,  sufficiently  exact  data  are  wanting.  It  is  to  be 
regretted  that  this  work  has  not  been  already  undertaken,  for  it  would  render  immense 


METHODS   OF   OBTAINING  THE   LATEX     1 

Service  t..  tin-  rul.Ker  indu>tr\.  ;m,|    it    i^    to    l,e  ho|,ed  that  in  i.-.-.-nliii-;  th,-  imj.,n 

'  tli-'  urap  lli«'  attention  ,,f  chemists  ami  natuiali-t-  \\ill  IKJ  arottied.      A 
in  his  study  "t  the  latex  ..('  tin-   Indian   /•'/.-//>•.  adopted  tin-  l..-t   ineth.,d> 
In  the  following  chapter  an  eti'ort  lias  heen  made  to  study  th--  tin?  Ilcvoa 

under  tin-  ni'ist  exact  ruiulitions  possible.      It  wmild  IK-  necessary  l"«»r  t  he  name  Work 
t..  lie  dune  with  each  variety  of  latex  produce. I    l,\    the  different    j.l.iiit-*   -»f  each 
i-oiintry ;  a  j>owerful  factor  would  then  have  been  gained  in  the  elucidation  - 
important  questions  as  the  best  methods  of  coagulation  and  the  prenervation  «.f 
cadi  nf  tin1  natural  varieties  of  rubber.1 

(7)   The   necessity  of  ascertn //////«/    flu    intini'it'  ,,/  tlt.    /' 

. — The  exact  knowledge  of  the  intimate  structure  of  laticitei'.us  \«-s^  U,  their 
arran.Lrenu'iit  and  development  as  regards  the  other  organs  of  the  bark,  \\<>uld  .iU«. 
be  of  the  greatest  assistance  in  such  a  research,  lint  little  has  been  done  in  this 
direction,  although  it  might  bring  a  fresh  light  to  bear  on  the  originating  intliien.c. 
«>n  the  quality  of  the  rubber  and  its  most  appropriate  treatment.  The  auth-- 
know  tin-  inicrographical  work  of  M.  Moivllet  UJMHI  some  riiblier  Lark-.  This 
example  would  l^e  a  good  one  to  follow,  particularly  on  the  s|*,t.  H« .\\.-\i-r  that 
may  l»e,  use  has  been  made  here  of  the  slight  amount  of  material  published  l.y  this 
•awml,  and  it  i>  to  be  hoped  that  he  will  not  leave  such  an  interesting  \\--rk 
unfinished.1 

1  This  has  now  been  done,  or  is  being  accomplished. 

•i-iit  resino-micograpliical  literature  abounds  in  data  of  the  tyj>e  h«-n-  d 
Miu-li  interesting  work  lias  been  done  of  recent  years  on  the  minute  structure  of  lati 
Is,  for  a  survey  and  bibliography  of  which  see  7'.vc/< irs>'h '5  7/arre  und  Harzt  llrhaltrr. 


CHAPTEK  III 
RUBBER  CULTIVATION  IN  VARIOUS  COUNTRIES 

CLIMATOLOGY SOIL — RATIONAL    CULTURE   AND    ACCLIMATISATION    OF   THE 

DIFFERENT    SPECIES    OF    INDIARUBBER    PLANTS 

Influence  of  methods  of  collection  of  latex,  and  separation  of  resin,  on  quality. 
— If  the  richness  of  the  latescent  juice  of  indiarubber  plants  vary  with  the  nature  of 
the  plants  producing  it,  their  age,  their  surroundings,  with  the  season  and  even  the 
hour  of  harvesting,  the  quality  of  the  latex,  and  therefore  that  of  the  indiarubber, 
obtained  from  it,  may  also  vary,  according  to  the  method  of  collecting  the  latex, 
and  the  process  of  separation  of  the  resin,  disseminated  through  it.  Influence  of 
genera  and  species. — The  diversity  of  the  plants  yielding  the  latex  need  not  be 
insisted  upon  any  further.  We  reserve  our  description  of  the  importance  of  the 
plant  until  the  merits  and  defects  of  each  commercial  variety  of  indiarubber  falls 
to  be  discussed. 

Influence  of  age. — The  influence  which  the  age  of  the  plant  exerts  in  the 
production  of  the  latex  is  important.  Extreme  youth,  like  extreme  old  age,  is  pre- 
judicial to  the  productive  force  in  the  vegetable  kingdom  as  well  as  in  the*  animal 
kingdom.  The  Hevea  of  Brazil  do  not  commence  to  be  remunerative  before  the 
age  of  fifteen  to  twenty  years,  and  that  it  does  not  become  exuberantly  productive 
under  twenty-five  years,  without  reaching  decay  in  a  hundred.  The  Manihot  of 
the  same  country  yields  profitably  as  young  as  ten  years,  and  the  Urceola  in  its 
fifth  year. 

Influence  of  the  age  of  the  plant  on  the  nature  of  the  latex  and  the  abundance  of 
its  floiv. — This  point  has  been  studied  by  several  authorities,  amongst  others  by 
Wright,  by  Proudlock,  and  by  Perkin  : — "  Some  laticiferous  plants  yield  rubber  of 
good  quality  when  quite  young,  but  this  cannot  be  said  of  the  Hevea,  Castilloa, 
or  Manihot  species  in  Ceylon.  The  cortex  of  the  seedling  of  Hevea  braziliensis 
and  the  cotyledons  of  the  seed  itself  possess  a  large  number  of  laticiferous 
channels,  but  the  latex  obtainable  therefrom  is  usually  very  sticky 
and  the  dried  product  of  low  commercial  value.  Rubber  prepared  from 
two-year-old  trees  of  Hevea  braziliensis  is  sticky  and  easily  snaps  when  lightly 
stretched ;  that  from  four-year-old  trees  or  from  stems  which  have  a  circumference 
of  about  twenty  inches,  though  it  does  not  possess  the  properties  wrhich  manu- 
facturers most  desire,  realises  a  price  which  is,  to  the  producers,  satisfactory. 
When  a  tree  is  tapped  for  the  first  time,  though  it  may  be  four  to  twenty-nine  years 
old,  the  rubber  obtained  from  the  latex  is  apt  to  turn  soft,  sticky,  or  tacky  on  keep- 
ing; this  is  usually  accounted  for  by  the  large  proportion  of  sap  contents 
which  are  unavoidably  mixed  with  the  latex  when  the  original  incisions  are  made, 
the  sugars,  gums,  etc.,  from  the  cortical  cells  providing  a  good  food  supply  for 
bacteria  responsible  for  the  development  of  tackiness  in  rubber.  Subsequent 
tappings  of  trees  of  these  dimensions  usually  give  good  rubber  when  the  tapping 
operations  are  carried  out  on  the  basal  part  (base  to  5  or  6  feet)." — Wright,  Cantoi* 
Lectures. 

Proudlock,  curator  of  the  Government  plantations  on  the  Nilghiri  Hills,  found 
that  Castilloa  trees  three  or  four  years  old,  in  the  Barliar  plantation,  2,400  feet, 
yielded  a  gummy  substance  destitute  of  the  properties  of  true  rubber.  Fifteen 

56 


RUBBER   CULTIVATION    IN   VARIOUS  COUNTRIES 

months  later  these  selfsame  breea  \  i.-ldrd  :t  U-tter  quality  «.t  rubU-r.  I  ..new  he  conclude* 

that  the  change    from  yielding   ;i    gnmm\    -nl.stain-,-   t«i  yieldin  rubber,  ccv 

in.-ides  with  or  clo-M-ly  t..ll..\\  3  tin-  period  \\hcii  the  special  tnM  U-gins  tn  pr.Hlu.v  *«  d. 


TABLE  VI.  —  NATURAL  HABITAT  OF  INDIABUBBKR  PLAJTPB. 


Country. 


Suutli  America  . 

(Yntr:d  America 
West  Africa 

East  and  Central  Africa 

India 

Oceania 


Altitl.de. 


Plain. 

Heights. 


Indiarabber  PlanU  best 
adapted  for  dim  i 

//•  i:  .,  h 

Micandraa. 

1 1  UMtt  i.i  i~. 


LandoL 

Vaheas,  Callotropis. 

Va.li. 

Landolphias. 

Willughbeia,  Cyiiaiirliti 
C.IIIH  niria,  Chavanesia. 
/•'<>/'>•,  f'r<-rola. 


No//.-  It  has  been  assumed  for  a  long  time  that  swampy  lain!,  cxjiORed  to 
the  action  of  the  tropical  sun,  is  alone  adapted  for  the  growth  and  development  of 
indiaruliluT  trees.  This  assertion,  if  true  as  regards  tin-  /A  />•//  of  the  Amazon, 
is  not  so  as  far  as  the  ll'inc'n-iihi  or  the  Mnnt/n'»  //•</  «>f  the  suidy  soil  of  Pernambuco, 
Maranhao,  and  Bahia,  nor  as  regards  tin-  Manihot  or  .!/'////>•"/  ,  ,,f  the  arid 

and  granitic  rocks  of  the  province  of  Ceara.     This  plant  resists  tin-  driest  weather, 
and,  whilst  every  other  form  of  vegetation  is  destroyed  under  the  inrliu-nr. 
scon-hin^  wind,  it  thrives  and  \ieldsgenerously  a  protital-le  latex. 

It  mu>t,  however,  be  acknowledged  that  vegetation  is  much  nuuv  intei: 
ground  exposed  to  inundations  or  divnelied  by  the  periodieal  rains,  and  that  the 
combined  action  of  heat  and  moisture  is  essentially  favourable  to  the  development 
of  indiurubber  plants.  If  the  soil  on  which  they  grow  be  marshy,  or  greatly  soaked 
by  the  rain,  or  by  the  prolonged  sojourn  of  the  water  along  the  banks  of  the 
ri\«  i>,  the  latex  will  be  watery  and,  consequently,  j  .....  ivr  in  resin.  If,  on  the 
nmtrary.  the  >ame  plant  be  situated  on  dry  ground,  exjxxsed  to  the  heat  of  a  torrid 
sun,  the  latex  will  be  less  abundant  and  more  difficult  to  collect,  but  it  gives  a 
larger  proportion  of  resin. 

Moreover,    this    intluem-e    of    an    QZCCiflfl    of    humidity   brings   in    its  train 
unsatisfactory   results  so  far  as  the   harvest  is  concerned,  when  the  rains   have 
persisted  longer  than  the  customary  time. 

l!<ttin  ,,r'  i,Kli,i,',ii>t>i  i-  to  latex.  —  However  that  may  be,  the  yield  of  the  lat« 
indiarubbt-r  may  vary  from  15  to  40  l>er  cent.  ;  below  1  .~>  per  cent,  the  trees  are  not 
wrought,  the  results  being  no  longer  profitable. 


A(  (  I.1MAT1>\TION    OF    iNlHAUriUll  I:     PLANTS.        K.VKLY     Hl-l- 

The  question  of  soil  brings  us  naturally  to  that  of  the  rational  cwfa*9  ^f 
iixlinnii,',,  rjJ'Hif*  and  to  that  of  the  wtin,»-  •''  flu-  different  tpeeie*  from  one 

hemisphere  to  another. 

///  /;/•/>/.</,  India.—  In  this  respect,  the  P.ritisk  illy  practical,  and 

always  zealous  to  free  th«-m>elves  as  tar  i-le  fn»m  paying  tribute  to  foreign 

countries  for  the  acquisition  of  raw  materials  employed  in  industry,  hav 

1  Recent  developments  must  have  perforce  modified  the  views  of  the  authors  on  the  acclima- 
tisation of  rubber.     This  section  (pp.  57-63)  is  retained  as  of  purely  historical  interest—  Trans- 

lator's note  to  second  edition. 


58  INDIARUBBER 

hesitated  to  introduce  into  their  Asiastic  colonies  the  rational  culture  of  iiirliarul»l  im- 
plants, and  to  try  to  acclimatise  those  most  adaptable  to  the  soil  and  climate  of 
Asia.  These  experiments  are  on  the  point  of  being  crowned  with  full  success.  In 
their  intention  to  make  India  the  indiarubber-producing  country  of  the  world  par 
excellence,  the  British  were,  to  a  certain  extent,  encouraged  in  their  enterprise  by 
several  reasons,  which  contributed  to  present  this  design  under  the  most  alluring 
colours. 

Inducements  leading  to  attempts  at  acclimatisation. — In  Amazonia  the  rubber 
trees  had  been  treated  in  such  an  irrational  manner,  that  many  of  the  trees  and 
the  best  were  annihilated,  and  consequently  the  seringueiro  had  been  constrained 
to  penetrate  farther  and  farther  into  the  solitude  of  the  virgin  forests.  On  the 
other  hand,  the  Brazilian  Government,  as  well  as  the  local  authorities  of  the  produc- 
tive provinces,  had  imposed  on  indiarubber  an  export  tax,  levied  at  the  place  where 
it  was  wrought ;  then  it  capped  that  with  an  ad  valwem  duty  of  21  to  22  per  cent. 
(9  per  cent,  on  account  of  local  customs  dues  and  11  to  13  per  cent,  for  provincial 
taxes).  This  taxation,  moreover,  was  not  the  only  imposition.  The  formation  of 
a  syndicate  of  Liverpool  speculators,  desirous  of  cornering  the  world's  market  of 
indiarubber,  had  still  further  contributed  to  raise  the  price  of  the  article  beyond 
what  it  would  ever  have  been  if  the  ordinary  rules  of  supply  and  demand  had  been 
followed.  These  considerations  were  bound  to  influence  a  Government  mindful 
alike  of  its  industry  and  commerce.  There  was,  however,  a  dark  side  to  the  picture. 
The  cheap  rate  at  which  indiarubber  was  produced  by  plants  growing  wild  was 
brought  forward  as  an  objection.  What  had  the  collectors  to  do  with  rational 
culture,  when  it  was  only  necessary  to  penetrate  a  little  farther  into  the  virgin 
forest,  where  abundant  vegetation  presented  itself  to  them  3  Could  a  colonist, 
however  intelligent  he  might  be,  hope  to  enter  into  serious  competition  with 
such  a  rival  1  This  objection  was  victoriously  fought.  If  the  indiarubber  tree 
is  only  to  be  found  in  the  virgin  forest,  has  not  the  harvester  to  undertake  a  long 
and  tiresome  journey  of  several  weeks'  duration  before  arriving  thereat,  and  before 
finding  the  most  convenient  place  for  fixing  his  hut  1  Is  he  not  frequently  under 
the  necessity  of  changing  his  abode  until  he  has  collected  enough  to  cover  the 
expense  of  his  journey,  his  stay,  as  well  as  his  return,  without  speaking  of  the 
profit  to  be  realised — a  profit  which  enables  him  to  live  during  the  rainy  seasons  1 
Is  he  not  far  removed  from  the  settlers  who  would  buy  his  harvest  from  him  *?  and 
the  far  from  conscientious  dealers,  are  they  not  there  for  the  express  purpose  of 
working  upon  his  extreme  distress  on  his  return,  and  to  acquire  dirt-cheap  the 
product  of  his  work  1 

The  colonial  planter's  advantages  over  the  Indian. — However  small  may  be  the 
wants  of  the  Indian,  he  will  never  produce  with  so  little  cost,  and  so  much  quietude 
and  peace,  as  the  colonist  in  his  enclosed  plantation.  The  British  had  already  had 
a  striking  example  of  this  in  the  culture  of  cinchonas.  Hence  they  passed  over 
these  specious  objections,  and  continued  on  the  road  which  they  had  mapped  out 
for  themselves.  It  was  quite  natural  that  the  first  attempts  should  have  been 
brought  to  bear  on  the  rational  culture  of  the  indiarubber  tree  indigenous  to  the 
country  itself,  the  Ficus  indica.  This  tentative  had,  moreover,  become  urgent,  in 
consequence  of  the  ever-increasing  destruction  by  the  native  collectors  of  the 
natural  trees  in  existence  at  the  time ;  and,  under  the  risk  of  seeing  this  branch  of 
national  production  perish  for  ever,  it  became  necessary  to  replace  the  ever- 
decreasing  trees. 

Rational  culture  of  rubber  first  attempted  in  Assam. — The  first  attempt  to 
form  plantations  was  made  in  Assam  in  1860.  The  experiment  furnished  sufficient 
data  to  be  able  to  count  upon  the  success  of  an  undertaking  of  this  kind. 

Yield  of  a  Ficus  in  rubber — Amount  and  intervals. — It  is  only  after  twenty-five 
years  that  the  Ficus  can  actually  furnish  a  profitable  yield.  From  that  time 
forward  the  tree  will  yield  every  three  years ;  to  expect  more  from  it  would  be  to 
condemn  it  to  rapid  impoverishment.  At  the  age  of  fifty  years,  each  Ficus  should 
furnish  a  triennial  harvest  of  20  kilogs.,  say  44  Ib.  of  indiarubber. 


RUBBER   CULTIVATION   IN   VARIOUS  COUNTRIES        59 

failur\  —Iini»'rh-t'tinn»  of  Ficu*  rultber. — This  calculation  wan  not  no 
attractive,  considering  the  time  that  had  to  elap-e  before  drawing  any  j'fotit  from  a 
plantation.      Analyses  and   experiments    undertaken   at    int.-i  \  al  -  pi.  .\,  d,  moreover, 
that  the  /•'/»•// >•  I  iy  it>   o\\n    milky  juice   could   not,  no   matter    h«.\\   jH-it.-'t   u 
methods  of  preparation,  furnish   an    imliarubbrr  e.|iial   to   that    ..!'   Para  and 

experiments  \\ere  therefore   condemned,  and  the  Assam   plantations 
temporarily  discontinued. 

/•;7/m////  /it file  attempts  to  acclimatise  the  Urceola  elastica  and  Urceola 
f#;i/,-nta. — Trials  were  then  made  with  the  Urceola  elastica  of  Borneo,  the 
development  of  which  is  so  rapid  that  as  early  as  the  third  year  it  yields  it*  firot 
crop.  Moreover,  the  plantation  once  established  re.juiies  no  other  care  whatever. 
r.ut,  without  knowing  the  reason,  it  would  appear  to  us  that  no  serious  attempt 
was  made  in  this  matter.  The  same  holds  good  in  regard  to  the  Urceola  esculent*, 
the  preliminary  establishment  expenses  of  which  are  very  much  below  the  average, 
and  which  furnish  by  the  seventh  year  a  yield  varying  between  j  and  2J  kilogx. 
(11  to  5J  lb.). 

StiU  further  futile  atf<'/ti/>f*  «t  aecttinatiitttion  Trial*  trith  t/u;  ( 
The  British,  especially  struck  with  the  really  remarkable  qualities  of  American 
rubber,  directed  their  efforts  particularly  in  that  direction.  But  it  is  .t 
remarkable  thing  that  in  their  trials  they  did  not  start  with  the  //•  ' 
/,/-,/ ://;, •,/>•/>•,  but  rather  with  the  Castilloa  elastica,  which  yields  a  much  inferior 
rubber.  In  1875,  Robert  Cross  was  entrusted  by  the  director  of  the  Royal 
Botanical  Gardens  of  Kew  with  a  mission  to  Central  America,  with  the  object  of 
procuring  slips,  cuttings,  and  seeds  of  the  different  species  of  CV*////"</,  intended  to 
be  multiplied  and  propagated  in  glass-houses,  for  ultimate  distribution  amongst  the 
different  British  colonies.  This  system,  which  is  adopted  by  the  British,  in  a 
general  manner,  for  all  the  plants  which  they  wish  to  acclimatise  in  their  colonial 
settlements,  is  not,  however,  without  a  flaw.  Because  a  plant  succeeds  in  a 
perfectly  well-regulated  greenhouse,  under  the  hand  of  educated  and  skilful 
gardeners,  with  care  bestowed  upon  it,  which  it  would  be  impossible  to  give  it  in 
the  open  field,  it  does  not  follow  that  the  plants  will  inevitably  succeed  on  the  sjM.t 
to  which  they  are  eventually  transplanted.  Hence  arise  innumerable  deceptions, 
where  there  have  been  every  ground  to  hope  for  success.  That  is  exactly  what 
happened  with  the  Castilloas:  whilst  they  prospered  in  the  Kew  hothouses,  they 
perished  in  the  Indian  plantations  in  default  of  the  soil  and  climate  of  the  mother 
country.  These  trees,  in  fact,  prosper  more  especially  in  the  dense  moisture- 
saturated  forests  of  Central  America,  on  the  banks  of  the  rivers  on  the  Attain 
of  the  watershed  or  "divide."  In  the  producing  districts  par  excellence  of  this 
indiarubber  tree,  namely,  in  the  basin  of  the  Rio  San  .luan,  it  rains  nearly  nine 
months  of  the  year,  and  that  is  par  excellence  the  climatic  conditions  essential  to 
the  perfect  growth  and  development  of  the  Castilloas.  These  trees  will  ne\«-r 
succeed  in  marshy  ground,  but  are  especially  fond  of  humid  but  arable  land.1 
Reproduction  is  easily  effected  by  marcots  (branches  covered  with  soil  \\ithout 
being  detached  from  the  main  stem,  so  that  they  may  take  root ;  in  Britain  tin- 
branch  is  called  a  layer,  and  the  process  is  known  as  layering)  detached  from  the 
young  branches,  but  these  marcots  or  layers  never  assume  a  very  \«  rtical  |".*ition. 

Futil,    ntt.inpts   to  acclimatise  the  7/r*v//   /.,•<( .Hicnsis. — In  the  following  year 

i  Robert  Cross  was  sent  to  Amazonia   to  get  slips  and  seeds  of  the  Hevea 

/'.</'.<.     In   spite  of   the    ill-will   of   the  natives,  jealous   of   preserving  the 

monopoly  of  so  highly  profitable  a  product,  he  succeeded  in  his  mission,  and  the 

Hevea  was  brought  to  augment  the  richness  of  the  acclimatisation  gardens  of  K--w. 

Came  of  failure. — This  tree  prospered  well  iu  the  hothouse,  but  suffered  in 
its  turn  the 'fate  of  the  Castilloas,  and  for  the  same  reasons,  in  the  bare,  exposed 
country  plantations.  'The  thing  was  easily  understood  :  the  Hevea  subsisted  under 

1  Manson  recommends  Casfilloa  trials  on  hillsides  with  western  aspect.  It  thrirea  on 
hills  of  Southern  India,  near  Calient  and  Malabar,  and  is  a  tree  for  the  coffee  tone  and  moist 

hilly  regions. 


60  INDIARUBBER 

appreciably  the  same  conditions  of  soil  and  climate  as  the  Castilloa.  The  tiv«- 
may  live  on  ground  of  varied  nature  and  constitution,  but  it  does  not  succeed  \\vll 
except  in  rich,  argillaceous  alluvium,  on  the  banks  of  streams  or  rivers,  where 
moisture  does  not  degenerate  into  swamps  and  marshes,  the  regular  flow  of  the 
water  through  the  soil  is  to  a  certain  extent  indispensable,  and  in  countries  where 
the  thermometer  registers  at  midday  32°  to  35°  C.  (89 '6°  to  95°  F.),  but  which 
never  falls  below  22°  C.  (71 '6°  F.).  It  is  rare  in  Amazonia  to  pass  ten  consecutive 
days  without  rain,  and  every  day  clouds  of  mist  envelop  vegetation.  Now, 
almost  parallel  climatic  conditions  are  not  to'  be  found  in  the  south  of  Burmah. 
But  there  are  other  essential  conditions  which  did  not  at  first  receive  the 
attention  which  they  deserved.  The  countries  where  it  is  proposed  to  establish  a 
plantation  of  indiarubber  trees  ought  to  be  hospitable;  iti  s  necessary  that 
man  should  be  able  to  live  there,  and  to  withstand  the  fatigue  of  regular  and  con- 
tinuous labour.  In  those  regions  which  are  specially  adapted  and  fitted  for  the 
successful  growth  and  development  of  the  Castilloas,  as  well  as  the  Heveas,  even 
the  Indian  native  himself  cannot  establish  a  fixed  domicile ;  the  more  reason, 
therefore,  why  the  civilised  colonist  should  not  even  dream  of  doing  so.  Amazonia 
and  the  banks  of  the  San  Juan  rivers,  the  most  productive  of  all  indiarubber  tree 
countries,  are  uninhabited.  The  seringueiros  alone  pass  through  them  during  the 
so-called  dry  season,  wasted  by  fever,  devoured  by  insects,  longing  for  the  day  of 
departure. 

Successful  acclimatisation  of  Manihot  Glazowii. — Better  success  attended  the 
attempts  to  acclimatise  the  Ceara  indiarubber  plant,  the  Manihot  Glazowii,  which 
thrives  naturally  on  stony  ground,  where,  generally,  brambles  and  such-like  bushes 
alone  can  live.  It  requires  heat,  but  it  can  bear  a  comparatively  large  amount  of 
drought.  Its  natural  habitat  is  in  the  most  arid  countries  of  Brazil,  where  a 
temperature  of  25°  to  30°  C.  (say  77°  to  86°  F.)  reigns.  According  to  experiments 
made  in  Ceylon,  this  indiarubber  plant  thrives  best  at  an  altitude  of  1800 
metres  (say  5904  feet)  above  the  level  of  the  sea,  and  does  not  require  any 
very  particular  soil,  and  adapts  itself  admirably  to  the  climatic  conditions  of  its 
adopted  country.  It  also  succeeds  equally  well  on  the  Indian  continent  as  in 
Ceylon,  and  the  Manihot  was  at  one  time  considered  as  the  indiarubber  tree  of  the 
future. 

Aids  to  germination — Nursery  ivork — Transplanting. — Its  seed  is  very  thick, 
protected  by  a  very  hard  shell;  in  order  to  hasten  germination,  which  lasts  for  a 
whole  year,  the  corners  may  be  removed  by  a  file ;  great  care  must  be  taken  in 
this  operation  so  as  not  to  injure  the  germ.  Each  seed  prepared  in  this  way  is 
planted  in  the  ground;  planting  is  done  in  the  open  air,  75  millimetres  (say 
3  inches)  between  each  seed;  the  seed  is  covered  with  from  12  to  13  millimetres 
(say  about  half  an  inch)  of  soil,  and  is  afterwards  watered  twice  a  day  in  dry 
weather.  It  is  essential  that  the  seed  be  not  in  the  shade,  otherwise  it  will  rot. 
The  plants  germinate  in  about  three  or  four  weeks ;  and  as  soon  as  the  young 
shoots  have  attained  a  height  of  30  centimetres  (say  1  foot),  they  are  fit  for  being 
transplanted  out  definitely,  without  any  other  precaution  than  to  keep  the  shoots 
3J  metres  (say  11 '48  feet)  apart  in  every  direction. 

Steeping  versus  filing  the  seeds — Propagation. — Instead  of  filing  the  seeds,  an 
operation  always  attended  with  great  risk,  the  planter  may  rest  satisfied  with  steep- 
ing them  in  cold  water  beforehand  for  six  days ;  in  that  case  germination  does  not 
commence  until  the  fourth  week.  Propagation  may  also  be  effected  by  the  mar- 
cotage  or  layering  of  the  young  branches ;  these  marcots  easily  take  root,  provided 
one  "  eye  "  is  at  least  in  the  ground  and  another  in  the  open  air.  At  the  present 
time  horticulturists  and  seed  merchants  supply  both  shoots  in  cases  and  prepared 
seeds  at  very  moderate  charges. 

When  Manihots  can  first  be  bled. — In  these  unprecedented  trials,  practice  alone 
could  serve  as  a  guide.  One  of  the  most  important  results  attained  was  the  know- 
ledge of  when  to  fix  exactly  the  proper  age  at  which  to  bleed  the  manihot. 
Experience  taught  that  it  was  in  the  fifth  year  that  the  first  profitable  incision 


RUBBER   CULTIVATION    IN    VARIOUS   COUNTRI1  •>        «i  1 


could  l»e  ma. If,  and  that  after  that  tin-  tree  could  U-  o|M-r.it.-d  QO  i\\u-,'  aiiiuuillv. 
and  during  three  consecutive  <la\>  each  timr.  'I'll,-  folloN\in-  u-  to  iudiii 

rubber  culture  on  Cocowate  Station,  l.unugalla,  ('.-\|..n: 

Area  uinl,  r  rn/tirntion.      Twelve  hectare-, 

Duration   of    "/•///  »F'.t/t,    /"it  drouth   stop-,   in    a  regular  manner 

,  .MI  ••hiring  tin-  months  «»f  Jinn-   and   July;   tin-  l«-a\.      fall  ami   .-e»-in   to  di«-. 
lint  a  little  afterwards  tin-  luids  and  tin-  foliage  ieap|»ear  more  U»ailtifnl  than  ever. 
t*.     After  thi'  ciiimnene.-    t«.  tlosvei    and   to  yield   teed, 

which,  as  they  ripen,  fall  mi  the  ground  and  germinate  rapidly. 

p.  The  trees,  still  very  young,  \idd  l.ut  \,T\  link,  aln.nt  500  gramme* 
(say  I/,,  H>.),  Imt  it  is  more  than  probable  that  \\ith  age  the  yield  will  IHH-OIII- 
considerable.  Kx|H'rirmv  alone  will  tell.  It,  however,  this  ti^nre  become*  a 
definite  one,  a  hrc-tun-  \\ill  ]>rodiire  annually  'M'>  kil«i^rainnn-s  ot  iinliarulilier  (lay 
:\:\\  11  >s.  per  acre),  which,  at  the  prire  of  ^)  francs  the  kilo^rannne  («tj  Is.  10d. 
the  !!•.),  would  give  a  total  of  187;")  tran.-s  (say  £75  the  nectar-  p  a<  n  ..  th, 

third  of  whieh,  <i •_'.">  francs  the  hectare  (say  £10  the  acre),  would  DOfVf  uorkinj^ 
e\pen>e-,  to  yield  a  Lrros-  profit  of  1250  francs  the  hectare  (say  .1'L'o  the  acre). 
Hut  unfortunately  the  Ceylon  results  have  been  disappointing^  the  utmost  profit 
realised  was  50  rupees  per  acre  after  >ix  year-. 

TABLE  VII. — SHOWING    I{.\TK  <>K  (;i;o\\ru    \M.   |)»-.\  M.HI-MI  M    «\ 

HI:-T    KIM: 


Height  of  the 
Trunk. 

Height  of  Trunk  t<> 
First  Branch. 

Circumference  at 
the  Base. 

Upper  Circumference 

at  J  metres  (6J  feet). 

Age  in 
Kara. 

In  metres. 

In  feet. 

In  metres. 

In  feet. 

In  in 

I:i  in<-lu->. 

In  metres. 

In  inch*. 

1 

18 

024 

9k 

«'  17 

«l 

•_' 

8-25 

17 

2-50 

8 

0-56 

22 

0-35 

13} 

3 

11-0 

35 

•2-7:. 

9 

075 

•_".", 

0-60 

•'.",' 

4 

13-0 

42 

3-30 

11 

1-06 

ttl 

062 

•Ji.  1 

5 

15'0 

50 

6-70 

22 

1-16 

45i 

Growth  is  rapid,  reproduction  by  sowing  easy  as  seed-crop  is  abundant. 

/'"/•'•nek  Colonial  enterprise — Sl-uggixh  >in<-nnt  niethods  contracted  with  energetic 
modern  ///"/N///VX. — Attempts  at  acclimatisation  and  rational  culture  hive  also  been 
made  it.  other  countries,  and  especially  in  the  Kivnch  j...--e--;..njj.  If  Jac«|ue> 
l>ii\al  could  say  in  his  day  that  "Of  the  live  nation>  which  divide  e.ju.itori.il 
America,  it  must  be  acknowledged  that  France  is  the  one  which  has  made  the 
-t  blunders  in  its  administration  of  it-  conquered  territory,  and,  after  the 
lajise  of  three  centuries  our  \\oik  in  Cuiaiia  may  be  thrown  in  our  fa*-e  as  an 
insult  and  an  injury,"  he  would  not  be  able  to  sj»eak  in  thi>  \\;iy  of  our  recent 
colonies  in  Western  Africa,  Cochin-China,  Tonkin,  and  Annam.  Colonial  adminis- 
tration in  these  cases  has  been  organised  on  a  more  practical  basis,  our  adminis 
trator>  interest  themselves  much  more  in  the  working  and  development  of  the 
natural  ridme-s  of  the  provinces  over  which  they  rule,  our  explorers,  our  colonist-*, 
oar  merchants  find  help,  encouragement,  and  facilitio  ;  e\en  otu  soldiers  «ad 
sailors  understand  better,  that  the  conqueror  of  modern  society  is  QMfeftS  unlem 
i-ivilisation  come  alongside  of  him,  charged  with  finding  new  commercial  and 
industrial  outlets  for  the  mother  country  as  well  as  for  the  new  colony. 

Ace!  i  unit  tuition  in  ill'  I-'r<  in-lt  CoiKio. — Thus  in  the  ( 'ougo,  the  natives  having 
rc-M-ted  to  cutting  down  the  indiarul.l.er  vines  instead  of  bleeding  them  nion- 
or  less  methodically,  the  rubber-producing  tree,  the  /,- 1 ,nl<Jjt/iia,  disappeared  more 

1  At  the  level  of  the  hranches. 


62  INDIARUBBER 

and  more  every  day  from  the  skirts  of  the  coast  and  the  naval  stations,  and  this 
disappearance  thus  deprived  the  immense  territory  of  the  coast  zone  of  a  consider- 
able source  of  revenue. 

TJie  Libreville  Botanical  Gardens. — E.  Pierre,  founder  of  the  Libreville  ex- 
perimental gardens,  sought  a  remedy  for  the  evil  in  acclimatisation,  and  in  the 
same  way  as  in  Ceylon  he  has  experimented  with  the  .]/•  mi/tot  (see  Fig.  4). 
The  attempts  of  Pierre  are  on  the  road  to  success ;  his  communication  to  the 
Paris  Society  of  Commercial  Geography  bears  witness  to  it :  "A  single  tree  which 
I  imported  in  1887  at  first  yielded  115  trees,  of  which  the  greater  number  now 
have  trunks  of  50  centimetres  (say  20  inches)  in  circumference,  and  a  height  of 
7  to  8  metres  (22 '96  to  26 '24  feet).  The  tree  which  M.  de  Brazza  distributes  as 
much  as  he  can  amongst  the  natives  has  a  great  future  before  it  in  this  country. 
The  tree  imported  in  1887  is  the  father  of  14,000  to  15,000  young  plants  formed 
this  year.  Several  thousands  of  these  young  seedlings  have  been  distributed  to 
the  most  distant  Pahouins  of  the  river  Congo."  The  director  of  the  Libreville 
Botanical  Gardens  counts  on  being  able  to  supply  henceforth  200,000  shoots, 
which  will  enable  new  plantations  to  be  made.  But  one  fact  must  be  pointed 
out,  which  has  been  communicated  to  us  verbally  by  M.  Mazier,  one  of  the 
young  and  bold  French  colonists  who  settled  some  years  ago  at  N'Djole,  on  the 
Ogooue :  1 — It  is  all  very  well  to  distribute  young  shoots  of  Manihot  to  the 
Pahouins  with  recommendations  and  instructions  for  their  plantation  and  culture, 
but  the  natives,  who  can  only  recognise  their  immediate  interests  and  benefits, 
have,  in  the  majority  of  cases,  placed  the  young  shoots  on  one  side,  to  continue, 
far  from  any  surveillance,  their  barbarous  process  of  destruction  and  devastation. 
By  penetrating  a  little  into  the  interior  they  find  an  easy  and  abundant  harvest : 
what  is  the  good,  therefore,  of  them  setting  themselves  to  the  weary  work  of 
plantation  and  cultivation,  and  wait  several  years  for  a  harvest  from  which 
probably  they  might  not  profit  1  The  wants  of  the  case  are  not  met,  therefore,  by 
simply  forming  nurseries  of  excellent  indiarubber  trees,  and  distributing  the  young 
trees  without  discernment  to  the  native ;  it  is  necessary,  if  the  firm  resolve  has 
been  made  to  attain  a  practical  result,  that  the  more  intelligent,  the  more  far- 
seeing  colonist  of  the  future  should  see  to  the  surveillance  of  the  plantations,  from 
which  he  will  soon  be  able  to  draw  substantial  profit.  According  to  Paroisse,  the 
Libreville  Manihot  is  not  the  same  as  that  which  yields  the  Ceara  and  the  Ceylon 
Manihot,  but  a  Manihot  which  is  a  native  of  one  of  the  isles  in  the  neighbourhood 
of  the  French  colony  des  rivieres  du  Sud.1 

Acclimatisation  in  Cochin-China. — In  Cochin-China,  where  the  soil  and  the 
climate  are  admirably  adapted  for  indiarubber  plantations,  acclimatisation 
experiments  have  not  been  neglected.  M.  Pierre,  the  director  of  the  botanical 
garden  of  Saigon,  has  successfully  acclimatised  the  Hevea  guyanensis.  It  is  not 
known  whether  the  transplanting  into  fresh  ground  has  succeeded  any  better  than 
the  Kew  trials. 

In  Reunion. — The  Isle  of  Reunion  has  also  had  its  attempts  at  the  acclimatisa- 
tion and  rational  culture  of  indiarubber.  Unfortunately  no  information  as  to  the 
success  of  these  attempts  is  available. 

Rational  culture  in  South  America. — Peru,  Colombia,  Costa  Rica,  San  Carlos, 
and  Amazonia  itself,  have  all  had  their  attempts  at  the  rational  culture  of  rubber, 

1  At  the  time  at  which  this  article  is  being  finished,  it  would  appear  that  the  question  of 
the  rational  culture  of  the  Ceara  indiarubber  had  received  a  check  at  the  Congo.  Fortunately 
this  check  was  not  of  long  duration,  for  the  following  is  what  we  read,  under  date  of  19th 
August  1894,  in  the  different  Paris  newspapers  :— "  The  Journal  Officiel  du  Congo,  which 
reached  Paris  to-day,  publishes  a  report  of  the  director  of  the  Libreville  Botanical  Garden, 
from  which  it  would  appear  that  the  trials  on  the  germination  of  the  Ceara  (?)  indiarubber, 
commenced  a  long  time  ago,  have  finally  been  crowned  with  complete  success.  After  many 
blindfold  attempts,  a  process  has  been  discovered,  by  means  of  which,  after  a  simple  and 
practical  preparation,  these  seeds  placed  in  the  ground  and  watered  spring  up  in  eight  days. 
At  the  present  time  the  garden  possesses  about  1000  of  these  small  plants,  which,  in  a  little, 
may  be  handed  over  to  the  planters."  Are  the  seeds  sown  the  same  way  as  those  in  Ceyloii  ? 
We  do  not  know  (Authors'  note  to  first  edition). 


RUBBKR   CULTIVATION   IN   VARIOUS   COUNTRIES        63 

and  the  result  ha-  al\\ay-  responded  to  the  -uni  of  the  ellon-.  expended.  Hut  let 
it  !•••  \\ell  kiiouii,  and  here  the  author-  speak  more  especially  for  the  I.. 
/I////W.N-,  that  experimenting  alone  i-  not  all  that  i-  \\aiit«-d  ;  it  is  necessary,  like  the 
IJritish.  to  persevere  and  not  to  be  discouraged  \\ith  a  tir-t  failure,  nor  by  the  first 
unprodiirti\e  expense.  If  ^uccess  be  certain,  it  is  possible  to  \\ait  a  little  longer. 
K\er\  experiment  always  \ields  a  result,  but  this  result  may  not  be  attained  until 
the  moment  uhen  the  operator  ha-  already  I«M  all  hope.  What  more  Mrikiiitf 
proof  riiuld  be  i;i\en  of  the  truth  of  this  remark  than  <  loodyeai  in  despair  and 
reduced  t«.  his  last  extremity,  \\lio  tinally  di-vovered  the  \  ul.-am-at imi  of  indiarubber, 
and  afterwards  the  manufacture  of  ebonite  or  hardened  indiarubber  ! 

\\n(    1-Yance  i-  now  doing  excellent  work  in  rubber^cultivation   in  West  Africa, 
and  there  are  hopes  ,,f    Madagascar   bein,ur  opened  uji  for  rubber  cultivation   also. 
[Tu.  1909.] 

riil>i»r  liYi'n.      The  jilanter  decides  upon  the  form  of  Cttl 


, 


*Zm 

-m 


Fie.  -Jl.— Collecting  rublx-r  by  spiral  tapping  in  British  Malaya. 

will  adopt  herring  bone,  V-«haped,  spiral,  etc. — the  first  two  being  practically  the 
only  ones  adopted  in  Malaya.  The  bark  is  cut  across  the  tree  in  the  selected  \\ay, 
l>ut  not  so  deeply  as  to  reach  the  wood  of  the  tree,  always  leaving  l>ehind  some  of 
the  rambial,  or  growing  layer  of  the  stem,  so  that  the  wound  may  rapidly  heal 
and  before  very  long  be  suitable  for  tapping  over  again. 

Directly  the  cut  is  made,  the  milk-white  latex,  which  is  a  mixture  of  caoutchouc, 
or  rubber,  and  the  sap  of  the  tree,  flows,  and  where  there  are  a  number  of  cuts  of 
a  tree  these  are  joined  together  by  shallow  channels  in  tin-  bark,  and  the  latex  run- 
down to  a  round  aluminium  or  galvanised  iron  cup  placed  at  the  base  of  the  tree. 
As  much  as  half  a  pint  of  this  white  milk-like  fluid  may  run  into  the  cup,  and  then 
the  tlow  ceases  and  some  of  the  latex  begins  to  coagulate  on  the  cuts  and  in  tin- 
channels  on  the  tree,  from  whence  it  is  pulled  off  and,  after  thoroughly  cleaning, 
becomes  "scrap"  rubber,  which  ditl'ers  only  slightly  in  colour  from  the  rubber 
prepared  from  the  latex  caught  in  the  cups.  A  series  of  experimental  tappings  were 


64 


INDIARUBBER 


ivivntly  madf  upon  Cast-ill* •«  tnrs  of  six,  seven,  and  eight  years  old,  on  an  estate  on 
the  Isthmus  of  Tehuantepec.  The  crude  method  of  tapping  as  practised  by  the 
native  Indian,  by  cutting  the  trees  with  a  "  machete,"  has,  of  course,  been  suj 


CO 


RUBBER   CULTIVATION   IN   VARIOUS  COUNTRIES        65 


by  the  employment  ..f  vpreially  designed  took  The  knife  iwed  in  the 
experiment  hen-  dealt  \\ith  was  one  invented  l.y  Mr.  V.  >.  Smith,  -in  American 
plant.-!-  in  the  State  of  Chiapas.  The  ineMons  were  made  in  V  form,  hut,  imtnnd 
of  making  a  complete  V,  the  mt  on  one  side  was  stopped  short  of  the  other,  to 
avoid  introducing  a  possible  focus  of  infection  or  rot  at  the  m«  •  -tin-  j-.int,  where 
moisture  nii^ht  In-  retained.  A  drip  enp  was  attarhed  to  the  base  of  the  tree,  by 

..f   an  upward  cut   nia.le  in    the    Lark,  the    Lottom   of  the  CUp  resting  Oil  the 
ground.     (The  ol.ject  -.f  the  upward  eut  was,  of  course,  to  c«m\ey  tin-  latex  into 
the  receptacle  \\ithoiit   \\aste.)       Ill    earlier   tapping   e\|*-riments   a  straight  ii 
\\a^  al>o    made    between    the   centre^   ..f    the    V  s,    forming    a    ivgular   herriiig-b<MM 
arrangement  ;   thi>    \vas  h"\\.-\.T,   f..iind   to   !•••   a    n>e|i-ss  mutilation   of  tin-  cortex, 


;.  23.— Collecting  rubber  from  CastiUoa  trct-s  l.y  V  tapping  in  a  Mexican 
plantation. 

the  risk  of  rot,  as  the  mere  drawing  of  a  finger  on  the  bark  from  V  to  V 
sutlieed  to  «-stal.li>h  a  route  for  the  flow  of  the  latex  d-.un  int. i  the  drip  enp.  The 
central  cut,  moreover,  added  little  or  nothing  to  the  actual  tl«»w  of  latex,  owing  to 
the  vertical  structure  of  the  lactiferous  cells  in  the  CmttilltM  tree.  When  the 
hiirher  parts  of  old  trees  are  tapin-d,  the  latex  obtained  is  often  changed  in 
conMitiition.  The  latex  from  high  parN  is  often  \ery  \\atery,  and  possesses  a  low 
percentage  of  caoutchouc;  on  treat  men:  \\ith  the  requisite  ipiantity  of  acid, 
coagulation  does  not  take  place;  even  \\hen  allowed  to  stand  for  several  days  a 
curdled  liquid  only  is  obtained,  the  particles  of  \\hich  are  not  elastic  and  do  not 
adhere  to  one  onother. 

The  number  of  times  when  non-coagulable  Para  latex  has  been  obtained  from 
various  sections  of  the  stem  of  twenty-nine  year-old  trees  is  given  below,  and  in 
considering  them  it  should  be  rememlieivd  that  the  circumference  of  the  stems  at 
the  higher  points  tapped  was  not  less  than  30  inche-. 

5 


INDIARUBBER 
TABLE  VIII. — PERCENTAGE  OF  TAPPING  GIVING  NON-COAGULABLK   LATEX, 


Number  of  times 

Per  cent,  of 

Height  of  tapping 
area. 

Number  of  times 
tapped. 

when  latex 
not 
coagulable. 

tappings  giving 
non-coagulable 
latex. 

Base  to  5  or  6  feet 

1165 

9 

077 

6  to  16  feet 

95 

1 

1-05 

10  to  20    „ 

94 

1 

1-06 

20  to  30    ,, 

94 

2 

2-12 

30 

171 

24 

14-03 

50 

84 

5 

5-95 

Coagulating  plantation  latex. — The  latex  may  be  transferred  to  the  factory  in 
suitable  vessels  carried  by  the  coolies  on  their  head,  or  it  may  be  transferred  to  the 
factory  in  capacious  milk  cans  on  trucks  running  on  a  mono-rail.  At  the  factory  it  is 
run  into  either  circular  or  rectangular  small  tins,  and  treated  with  the  requisite  amount 
of  lime  juice,  acetic  acid,  formic  acid,  etc.  When  the  rubber  is  not  washed  it 
assumes  the  form  of  the  vessel  in  which  it  was  coagulated,  namely,  round  biscuits 
or  rectangular  sheets.  When  large  quantities  are  coagulated  in  bulk,  after  being 
treated  with  the  calculated  amount  of  acid,  the  whole  is  allowed  to  stand  till  next 
morning. 

Dittmar's  classification  of  coagulants. — Amongst  chemical  coagulants  not 
mentioned  in  the  text  by  the  original  authors  in  the  first  edition,  Dittmar  in  his 
classification  of  coagulants  gives  the  following  : — phenicin  sulphate,  acetone,  acetic 
acid,  formic  acid.  He  also  gives  a  separate  heading  to  coagulation  by  urine,  and 
another  to  coagulation  by  sterilisation  followed  by  acidification,  amongst  which 
he  enumerates  the  following  antiseptics  as  being  used — formaldehyde,  guaiacol  or 
thymol  solution,  then  acidification  with  oxalic  acid,  formic  acid,  citric  acid,  extract 
of  termites  and  of  ants.  In  addition  to  churning,  he  gives  a  separate  heading 
to  centrifuging,  otherwise  his  classification  is  similar  to  the  authors'.  Zimmerman 
classifies  the  reagents  he  used  or  tested  for  coagulation  of  the  latex  of  Manihot- 
Glaziowii  as  follows  : — 

Useless — Alum,  5  per  cent. ;  ammonium  ferrocyanide,  5  per  cent.  Incomplete  or 
very  slow — formalin,  2  per  cent. ;  common  salt,  2  to  5  per  cent.  ;  pyridine,  2  to 
4  per  cent.  Paplike — Tannic  acid,  2  to  5  per  cent.,  and  bark  extract  from  Acacia 
decurrens.  Good — hydrochloric  acid,  sulphuric  acid,  formic  acid,  acetic  acid,  citric 
acid,  lysol  and  carbolic  acid. 

Weber 's  summary  of  coagulation  according  to  his  theories. — (1)  That  the  so- 
called  coagulation  of  rubber  by  acids  or  alkalies  is  erroneous  in  that  it  is  only  the 
albumen  which  is  coagulated  by  these  substances,  and  not  the  rubber  itself. 
(2)  That  the  albumen  contained  in  latex  is  very  harmful  in  many  respects,  and 
that  it  ought  to  be  as  far  as  possible  eliminated  from  the  milk  before  attempting 
to  agglutinate  the  rubber.  (3)  The  method  Weber  recommends  for  coagulation 
is  briefly  as  follows  : — First  mix  the  latex  with  water  at  least  five  times  its  volume. 
In  cases  where  the  latex  is  thick,  actual  boiling  water  may  be  used  with  advantage. 
In  this  state  it  can  be  easily  strained  to  remove  impurities.  After  this,  add 
formaldehyde  in  the  proportion  of  8  oz.  to  a  petroleum  barrel,  stir  well  and  let 
it  stand  for  twenty-four  hours,  when  the  rubber  will  collect  on  the  top  and  can  be 
lifted  out  in  one  mass.  In  order  to  remove  any  traces  of  albumen  that  may  be 
suspended,  the  rubber  should  next  be  cut  into  strips  and  subjected  to  a  thorough 
washing  upon  an  ordinary  rubber  washing  machine.  But,  according  to  Watt,  the 
use  of  formaldehyde  does  not  seem  to  have  been  the  success  that  Weber  antici- 
pated, though  his  recommendation  for  cleanliness  and  repeated  washing  has  been 
universally  accepted. 

Weber  regards  coalescence  of  the  latex  as  in  the  churning  process  as  different 


RUBBER   CULTIVATION   IN  VARIOUS  COUNTRIES        67 

from  <'<xi<inlnt  imi  thereof.      Tin-    latex    examined  1>\    llairie^  he  assert*  had  u. thing 

in  eoininon   \\ith  g I  latex.      To    Weber    there    i-    the    -am.     d.!l'«-rene.-   a>    U-tv, 

butter-making  and  cheese  making.  In  the  future,  \\hen  \\e  know  how  rublx-r 
becomes  po|\  meri-eil,  a  more  decided  opinion  can  !,.•  fornn-d  on  th«-  -ubjeet.  The 

direi-tion  \\hich  the  polymerisation  a— ume>  plays  an  important  n'.le  in  the  process, 

and  \\eber  doubted  it  K-ch  and  Chvulles  \\ell  under-iaiid  it-  bearing.  One 
cannot,  in  Weber's  opinion,  n  ;_,ud  the  po|\  meri-al  ion  of  rubber  like  that  »\  other 
organic  bodie-,  -ndi  a-  formaldehyde  into  paraldehyde,  acetylene  into  U'nzcne. 
Besides,  coagulated  rubber  has  not  the  -aine  proper!  ie-  ,  d  rubber;  that  i> 

why  the  centrifugal  method  used  in  Ceylon  tailed  to  give  good  re>nlts,  the  product* 
obtained  thereby  not  being  comparable  with  the  rubber  obtained  by  coagulation 
by  means  of  acetic  acid.  The  coalesced  product  has  no  sale  on  the  market,  beca 
it  i-  especially  in  the  //'>;,/  latex  exploited  in  Ceylon  that  tin-  differentiation  of 
the  two  products  is  very  decided.  Weber  attributed  that  to  a  less  advanced  stage 
of  1 1  .lynieri-ation  in  the  coalesced  product,  but  he  \\a-  never  able  to  impart  to  it 
the  polymerisation  of  the  coagulated  product.  Then,  again,  there  j<  another  thing 
besides  polymeri-atioii  in  rubber.  llubber  has  a  structure,  for  its  physical 
properties  are  sometimes  different  according  to  the  direction,  thus  one  can  ea>ily 
detect  sometimes  that  rubber  vulcanised  in  sheets  has  an  elongation  in  the  case  of 
overcured  rubber  in  one  direction  and  undercured  in  another.  Welder  made 
experiments  fourteen  years  ago  (i.e.  ill  1801)  in  Messrs.  Macintosh's  factory 
in  Manchester,  in  order  to  dissolve  fine  select  Para  rubber  in  ether,  and  found  to 
his  great  astonishment  that  sheets  of  this  quality  did  not  dissolve  therein  e\en 
after  several  weeks'  contact.  Weber  afterwards,  with  his  assistant,  Mr.  Better's- 
frequently  repeated  this  experiment,  and  the  result  was  always  the  .-ame.  Weber 
also  repeated  the  same  experiments  on  other  rubbers,  but  his  death  prevents  an 
account  of  them  being  given. 

According  to  Weber,  there  are  considerable  oscillations  in  the  solubility  of  rubber 
in  ether.  Carbon  disulphide  solves  the  problem  better.  It  may  be  taken  that 
the  portion  which  dissolves  in  ether  is  pure  rubber  of  the  formula  C10  Hlfi,  and 
that  the  remainder  obtained  by  other  solvents  contains  oxygen  of  which  the 
quantity  gradually  increases  with  the  fractionation,  and  the  rolls  change  the  ratio 
of  these  two  quantities  and  may  render  all  the  rubber  solvents.  That  pla\ 
giand  role  iii  actual  practical  working,  and  Weber  had  said  so  for  a  long  time.  We 
cannot,  therefore,  appreciate  the  quality  of  a  rubber  by  the  amount  of  insoluble, 
it  being  given  that  mixing  and  mastication  changes  this  very  variable  quantity 
even  so  far  as  to  cause  it  to  disappear  altogether. 

Tlf  churning  and  centrifugal  methods  of  coalescing  the  latex. — Biffen,  by 
treating  the  latex  in  a  centrifugal,1  revolving  at  a  speed  of  6000  turns  a  minute, 
found  that  the  Hevea  latex  left  a  residue  of  28  to  30  per  cent.,  and  that  of  Ca9till<*i 

'"•n  25  per  cent.  The  latex,  after  being  mixed  with  50  per  cent,  of  water,  i- 
placed  in  the  machine  and  spun  for  the  space  of  a  few  minutes.  The  machine  is 
then  allowed  to  come  to  rest  gradually,  when  the  rubber  floats  to.  the  top  of  the 
liquid  in  a  thick  white  mass,  with  the  albuimnoids,  proteids,  and  all  dirt  and  chips  at 
the  bottom.  The  rubber  is  skimmed  off  and  drained  on  a  porous  surface.  Accord- 
ing to  experiments  carried  on  by  Mr.  Hart  in  Trinidad,  it  can  be  removed  in  about 
t\\o  hours,  and  in  six  hours  afterwards  it  is  comparatively  dry.  The  advantages 
claimed  for  this  method  of  extracting  caoutchouc  are  as  follows;  (1)  It  pro- 
duces absolutely  pure  rubber;  (2)  the  whole  process  is  under  scientific  control; 
(3)  it  is  capable  of  dealing  efficiently  and  immediately  with  any  quantity. 
Many  recent  writers  deprecate  the  use  of  centrifugal  force,  and  special  machinery 
has  been  patented  in  which  the  advantage  set  forth  is  that  they  do  not  invoke  the 
aid  of  that  force. 

The  noxiout  <  ruym*  in  ,-uM>er  latex. — Preyer  churned  the  soft  milky  cream  in  a 
boiling  aqueous  solution  of  formic  acid  or  chloral  hydrate,  and  obtained  rubber  of 
a  pure  white  colour,  and  it  remained  white  in  the  air,  and  when  well  washed  with 

1  Watson,  Laid  law,  &  Co.  type. 


68 


INDIARUBBER 


water  contained  neither  resinous  nor  acetic  compounds.  The  colour  of  rubber  would 
therefore  appear  to  be  due  to  oxydases.  With  regard  to  the  important  discovery 
by  Bamber  of  the  enzyme  which  occurs  in  rubber  latex,  and  which,  if  not  destroyed 
early  in  the  preparation  of  the  raw  rubber  by  heat  or  by  washing,  tends,  with 
other  organic  products,  to  darken  the  rubber  when  it  is  exposed  to  the  air. 
Bamber  states  that  unless  this  enzyme  is  destroyed,  the  sunlight  through  a  window 
or  crevice  falling  on  parts  of  the  rubber,  or  a  draught  of  air,  tends  to  turn  out  a 
batch  of  rubber  uneven  in  colour,  according  to  the  varying  amount  of  the  enzyme 
present.  It  is  advisable  to  ensure  the  destruction  of  the  enzyme  which  occurs  in  the 


FIG.  24. — The  K.  L.  [Kala  Lumpur]  Coagulator. 

latex,  together  with  certain  organic  products  which  darken  on  exposure  to  air. 
The  enzyme  has  an  effect  very  similar  to  the  enzyme  in  tea.  Unless  it  is  de- 
stroyed early  in  rubber  manufacture,  or  thoroughly  removed  by  washing,  variations 
in  colour  are  bound  to  result  in  every  day's  out-turn,  as  it  is  impossible,  under 
present  estate  factory  conditions,  to  dry  all  the  rubber  under  identical  conditions 
of  light,  air  currents,  and  probably  temperature.  The  sunlight  through  a  window 
or  crevice  falling  on  parts  of  the  rubber  and  not  on  other  parts,  or  a  draught  of 
air,  would  tend  to  darken  the  colour,  but  the  change  would  also  be  affected  by  the 
varying  amount  of  enzyme  present.  The  strength  of  the  rubber  is  probably  not 
affected,  or  only  to  a  very  slight  extent,  by  this  variation  in  colour,  but  a  pale 


RUBBER   CULTIVATION    IN   VARIOUS  COUNTRIES        69 


ml, her    is    preferred  for   many   -uperior   artirl,-,,   especially   articles   for  medical 
Ua     The   IM-M    lerdinu  l>ottle  tubes  and    •  QI  I, lack  or  opaque, 

l.nt     transparent     ami     of     a     pale     \vllo\\.     \\hi«-|i     i-    a     -KM'  .:.!    ugainat 

uncleanlii.' 

Marly  in  11)07,  I'.amber  filtered  hit. A  thn>iiL'h  p..iv,-lain  in  a  vacuum,  and 
obtained  tin-  perfectly  roloiirlr—  watery  pari  of  th,-  latei  containing  all  tin-  soluble 
matter  naturally  pre-ent.  On  exposing  this  liquid  to  air.  In-  n.iti.vil  tliat  within 
a  ti-w  ininiiti-- a  rapid  ilarkt-nin^  t«»«,k  jilac«-,  which  pointed  to  the  presence  of  an 
artm-  o.xydi-inu'  I-II/NIIH-.  and  ihi-  li«-  cuiitiriiiril  l»y  <>tlirr  tette,  It  was  «-\id»-nt 
that,  if  this  rn/.yinr  cuiilil  In-  d.-M  r«>\  rd,  i.r  iviiin\rd  tM^.-tln-r  \\ith  most  of  tin- 
solnlilc  inatti-r,  jialrr  nilil«-r  should  iv-ult.  lv\|.i-riiiifiit-.  -ho \\.-d  tin-  trin|H'ratmv 
at  \\hidi  the  enzyme  Cpllld  be  destroyed,  and  it  only  ivmainrd  to  get  experiment-* 
ni  a  large  scale,  on  somr  estates  for  \\hieh  airaiiirfineiita  were  made  before 


Fie.  '_'.'•.-  ri:iiitati.iii   nilihi'!-  \v;i.sliiii<4  inachiiif,  ronstnicti'd  in  Kala  Lumpur, 

'.Malay  States. 


I 


r.ainl>er  left  for  England.       l(itl,l)er  so  treated  ha<  ..l.tained  tlie  toj,  pri.v  at  i 
re.-eiit  sale-,  and  the  fart    lias   attracted   considerable  attention.      The  hoat  must  In- 
applied  long  enough  to  thoroughly   pmeti-ate  a   oon-condacting  material,   f«>r  the 
men'  surface  destruction  of  the  en  /vine  i-  u-el. 

HW//////    jJilitf'lfi'-m      i-iifiln  i-    Li/    'I     <'»/»„;,  if     rniLtti-iirf,,/     inis/n',1;/     ("/'    /'•  "'' 

machine.-  This  new  ma.-liin.-.  l-'i--.  25,  -«'-.  ha-  l.een  produced  primarily  for  large 
elates,  and  is  of  a  similar  si/e  to  a  wa-hiim  machine  manufactured  in  Kurope. 
It  can  be  converted  into  a  ruLl-er  rolling  machine  when  d.-sired. 

Plantation  l>ln,-k  rubber.—  Fi,ur.  -7  show-  a  new  and  impn.\rd  form  of  machine 
for  comitressin^  \\a-hed  ruhljer  into  block-  for  -hipmeut.  It  i-  entirely  self 
contained,  requiring  no  belting  nor  shafting  for  driving,  i-  ea-ily  worked  by 
native  labour,  and  has  no  complicated  parts  likely  to  get  out  of  order.  The  twin 


70 


INDIARUBBER 


boxes  into  which  the  rubber  is  placed  are  9  inches  square  by  8  inches  dee}),  and 
finished  blocks  9  inches  square  by  about  3  inches  thick  are  obtained  after  the 
pressure  has  been  applied.  The  top  of  each  box  is  hinged  to  facilitate  charging 
and  emptying,  and  is  held  in  position  by  a  simple  locking  device  when  the 
pressure  is  on.  The  pressure  is  obtained  by  a  small  hand-pump,  capable  of  exerting 


II 


a  pressure  of  7  tons  on  each  ram.  The  presses  and  pump  are  carried  on  a  cast-iron 
box  base  which  forms  a  water  tank,  from  which  the  water  is  obtained  for  working, 
and  after  each  operation  the  water  is  again  returned  to  the  tank.  The  valves  are 
arranged  to  enable  each  press  to  be  worked  separately,  so  that  while  one  press  is 
being  charged  the  other  can  be  pressed  and  emptied,  thus  reducing  the  labour  to 
a  minimum.  Loose  plates  are  provided  to  fit  inside  the  boxes,  by  means  of  which 


RUBBER   CULTIVATION   IN   VARIOUS  COUNTRIES        71 


the  name,  Duality,  <>r  other  di-t  inguNiiiig  marks  can  be  impressed  on  each  block. 
single  presses  an-  also  made  ..n  similar  principle^  t»  the  above,  also  presses  of  any 

other  si/.r  to  suit   individual  rc<|iiirQmQDte, 

The  usual  method  of  drying  rul>l»er  is  l.\  >  •  hot  air,  [lassed  through  dry- 

ing rooms  by  means  of  fans  or  >imilar  de\  i  ,in  drawbacks  attached  to  the 

methods  at   present   used  ha\r  led    IM  a  \.-rv  iTfiirral  u«e  of  a  vacililin  ill  tin* 

place  of  hot  air,  \\itli  >atista«toi\  r«  suits,  and  among  the  most  suitable  vacuum 
apparatus,  with  condenser*  and  vacuum  pumps,  are  tho-r  ot  tin-  Kmil  fiutsbarg 
System  (  Fig,  '28). 

For  the  Scott  method  of  drying  rublxjr  the  following  advantages  are  claimed  : 

Uapid  drying  at  low  tciiij-iMMt  un-s.  Kxtivinr  CCOIIOIIIN  of'  -ttMin,  j.iactically  all 
thf  li«-at  in  the  steam  ln-in^  utilised  in  removing  the  moisture  from  the  HU!' 


;.  -7.    Hydraulic 


»IT>S,  \vith  tv.  .  1  haml-{>umi». 


Small  spjice  cuTiijiinl.  Kn-e«|om  from  atmospheric  impurities.  rniformity  of 
\vorkin-  and  uniformity  of  product.  Independence  of  elimatie  eonditions.  ltubU»r 
<MII  l.e  dried  in  from  one  to  four  hour-.  Temperatures  from  1»0  F.  uj»\vards, 
and  below  this,  if  required,  the  rate  of  drying  then  being  slower.  The  Scot- 
i-  ii-ed  for  drying  rul-Kei  in  crepe,  block,  biscuit,  worm,  or  manufactured  form,  and 
gutta  pereha  with  recovery  of  solvent.  It  can  be  supplied  in  cast-iron  or  mild  steel 
body  of  either  rectangular  or  cylindrical  form  ;  also  made  in  sections  for  easy  trans- 
port and  up-country  \\ork.  Other  features  an-  Sliehe-  constructed  in  one 
without  any  joints.  Special  method  of  attachment  with  steam  joint  outside  the 
stove.  1  >ooi-  of  sliding  or  hinged  form  to  suit  requirements  and  position.  Con- 
deiiM-r  of  double-flow  tyi»e,  giving  complete  condensation  with  economy  of  water. 
lu  <  eiver  titted  with  inspection  glasses,  enabling  the  flow  of  condensed  water  and 


72 


INDIARUBBER 


FIG.  28. — Vacuum  dryer  for  indiarubber  (Passburg). 


FIG.  29. — Vacuum  dryer  for  indiarubber  (G.  Scott  &  Sons), 
(See  right-hand  corner  of  plan,  Fig.  30.) 


RUBBER   CULTIVATION    IN   VARIOUS  COUNTRIES 


(l.y  inference)  tli''A<-<-ii«liti..n 

]iiiniii  with  inr.-liaiiirull     ni.i\i-,l  \al\,- 


.'^;,,.  •  l.-ti-nniiii-.l        \ 
|,tt|,.  at  i.-nli-.n  ,,r   rr|..iir. 


\xx\xxxxxx\xvw 


c\  ^^^\>^ 


ritlier  steam  or  belt  driven.      The  jihint    is  mu.lr  in  stamlanl  MA->.  whidi  imvt  th. 
«inliiiary  requirements.     Many  larger  -\/.^<  liave,  li«>wovcr,  l»oen  constructed,  .m«l 


74 


INDIARUBBER 


special  combinations  of  plant  with  a  number  of  stoves  working  into  the  one  con- 
denser have  also  been  made. 

Recent  development  in  rubber  arboriculture. — Since  the  above  critical  essay  on 
rubber  acclimatisation  was  written  by  the  original  authors  of  this  treatise,  the  whole 
domain  of  the  arboriculture  of  rubber  has  widened  and  enlarged,  and  the  tropical 
culture  of  indiarubber  in  equatorial  zones  has  progressed  to  an  extent  which  at 
that  time  no  one  then  dreamt  of  its  attaining  within  such  a  short  period  of  time. 
The  contentions  of  the  authors  in  this  chapter  that  the  Hevea  cannot  be  ac- 
climatised in  the  East,  etc.,  so  as  to  produce  rubber  at  a  profit,  seem  to  have  been 


FIG.  31. — Rubber  plantation  three  years  old.  Strong  application  of  potash  (15  per 
cent.)  ;  weak  application  of  nitrogen  (4 '5  per  cent.).  Circumference  of  stem  1 
inch  from  base  :  beginning  of  1905,  9  inches  ;  June  1906,  14  inches. 

demonstrated  by  actual  results  to  be  untenable.  Their  ideas  are,  however,  worthy 
of  respect,  and  there  can  be  no  doubt  but  that  the  Hevea  yields  a  more  abundant 
and  a  better  quality  of  latex  in  its  own  hemisphere,  in  its  own  native  habitat  on 
the  banks  of  the  Amazon  and  its  tributaries,  than  in  a  colonial  plantation  in  another 
hemisphere.  But  that  is  not  to  say  that  it  cannot  be  cultivated  at  a  profit  in  such 
colonial  plantations.  On  the  other  hand,  many  other  authorities  besides  the 
authors  question  the  advisability  of  replacing  native  rubber  by  Hevea,  etc. 

The  function  of  fertilisers  in  rubber  culture. — Let  us  deal  with  the  question 
of  fertilisers  in  rubber  arboriculture,  and  then  we   shall  be  free  to  consider  the 


RUBBKR   CULTIVATION   IN   VARIOUS  COUNTRIES 


opinions  <-f  ditl'fiTiil  observers  In  ;ill    their    I-.MI  in-^.       l'|.  to  n<>\\  artificial  manure- 

ha\e  not  been  very  largely  UM-.I  in  tin-  rubber  arlxu-iculture,  l.ut  this  practice  in  now 
romiiiLr    moiv    int..    favour.      This    i>    due   to    the    results    oi'    m.i: 
which  have  shoun  the  following  advantages  from  tin-  jmlicious  iwe  of  suiiaMr 
:     (  1  )  Tln-iv  is  a  healthier  'ini/  /""•/•  iirnii-tli  <>i'  t/,,  /,>•».<,  and  tliis  maken 


FIG.  32.— Rublier  plantation   lour   yean   <>U1.     T...,  strong  application  .>t   in: 

(6  per  cent);  too  wt-;ik  applii-ati.m  •  >!'  potash  (".  J..T  cent),     CircnmfeNDOi   «-f 
st. -in  1  inoh  fn.iii  base:  beginning  of  1*05,  «.»J  iiiflu-> :  .iun«-  r.»06.  in  inehm, 

it  available  to  coinnienrr   tajipiiiLi  eai'liei.  and    the   tree-   arc   nn.iv   resistant 

attacks  of  diseases  and  l.li^lit.    V_()  Tin-  tree,  ^n.wn  on  .Milti\ated  and  manured 

land  give  a  greater  incr#t*    <>/  <i>:>,i't!,  eacli   year,  and    this   incruAM^s    tin-  amount  "t 
tapping  that    can   l>e    can'ie.l    out.      (.".)    Tliciv    is   a    ./w/f/-. /• 

of  bark,  and  as  a  re>ult  a  tcurfftf  ///»/•/  "'   rvbbei    per   annum 


76  INDIARUBBER 

increased  and  more  regular  flow  of  latex.  (5)  The  growth  and  vitality  of  ttie  root 
system  is  considerably  developed.  This  result  is  of  very  great  importance  in  the 
drier  zones,  as  the  deeper  and  more  widely  spread  the  root  system  is  carried,  the 
smaller  the  chance  of  the  tree  being  affected  by  drought,  and  the  more  unvarying 
the  latex  return  during  the  drier  seasons  of  the  year.  For  the  above  reasons,  the 
application  of  artificial  manures  to  rubber  trees  in  bearing  is  an  economical  and 
necessary  practice  for  their  successful  and  permanent  cultivation.  In  most 
countries  artificial  manures  are  obtained  at  a  comparatively  small  cost,  which  is  much 
more  than  repaid  by  the  good  results  previously  mentioned  on  the  yield  and  growth 
of  trees.  In  some  countries  rubber  plantations  are  found  on  rich  virgin  soils,  but, 
nevertheless,  in  many  cases  the  application  of  artificial  manures  is  found  to  have 
a  very  well-marked  and  valuable  effect.  In  other  parts  rubber  plantations  are 
found  on  very  poor  soils,  and  in  these  cases  there  is  no  question  at  all  as  to  the 
value  of  applying  artificial  manures.  The  same  may  also  be  said  of  rubber  growing 
among  tea.  Here  the  artificials  have  a  double  effect,  for  whilst  improving  the 
growth  and  yield  of  rubber  they  also  improve  the  quality  and  increase  the  yield  of 
tea ;  on  lands  where  tea  is  growing,  a  larger  application  of  manures  can  be  given 
than  on  land  only  carrying  rubber  trees,  as  the  ground  is  more  thickly  covered 
with  plant  life.  The  question  that  now  comes  to  the  front  is,  What  manures 
should  be  applied  1  But  we  may  first  state  that  the  three  most  required  plant 
foods  deficient  in  the  soil  are  nitrogen,  phosphates,  and  2^otash,  and  it  should  be  the 
method  of  all  cultivators  of  rubber  to  apply  these  three  plant  food  constituents  in 
the  manure  that  is  applied,  and  also  to  give  them  in  the  proper  proportions  that 
the  plants  require.  Let  us  take  a  survey  of  the  three  most  essential  plant  foods, 
and  commence  with  the  one  that  requires  the  most  care  in  its  judicious  use.  The 
application  of  too  much  nitrogen  tends  to  make  the  plants  produce  very  quick 
growth,  and  this  causes  the  trees  to  become  very  weak  and  tender  and  very  liable 
to  be  broken  down  by  the  wind,  as  shown  in  Fig.  32. 

The  result  of  an  experiment  on  the  manuring  of  rubber  trees  in  Ceylon,  which 
was  carried  out  by  Mr.  R.  M.  Eckert,  Vincit,  Ruanwella,  showed  the  good  effect  of 
a  rational  manuring,  which  consisted  of — 

TABLE  IX. — SHOWING  INGREDIENTS  OF  RATIONAL  MANURE  FOR  A  RUBBER 
PLANTATION  AND  THE  CHEMICAL  COMPOSITION  OF  THE  MIXTURE. 


Chemical  Composition. 

Ingredients. 

I,  ,     ,         !   Phosphoric 
Potash.              A  id 

Nitrogen. 

20 
10 

per  cent.  Castor  cake  1 
,,        Rape  cake     J 

1-8 

10 

,,         Crushed  fish        .         .              ...                     0'4                    0'6 

10 

.,        Bloodmeal  .         .         .             ...                    O'l                    1*3 

20 

,,         Bonemeal    .         .         .              ...                     4-0 

0-8 

30 
100 

,,        Muriate  of  potasli        .             15 

4-5 

,,         contains      ...             15                     4  '5 

This  gives  a  well-balanced  manure,  which  produces  a  very  healthy  plant. 
But  quite  a  different  result  ensues  from  injudicious  manuring  in  a  case  of  a 
tree  manured  by  a  mixture  containing — 


RUHHRR  CULTIVATION   IN   VARIOUS  COUNT1 


TABLE    X. — SHOWING    THE    COMI-«M  1 1..\    OF    A    DKKKCTIVK    MANL-EH   roa   A 
RUBBER  PLANTATION,  NMNI    OHIMIOAX  OoMFoanoi  01    rm    I     KKIUKNTH 

\M.    OF    TNI.    Mix  i  i   1:1  . 


*». 

Ingredients 

Prtuh. 

Phora 
Acid, 

Nit: 

•J.">  IMT  cent. 
18 

Castor  c;iki-  \ 
Rape  cake    / 

!•< 

20 

(  'nislit-.l  tish 

0-8 

1  -J 

10 

Bloodineal  . 

o-i 

20 

Bonemeal    . 

40 

0-8 

10 

Muriate  of  potash 

... 

100      „ 

contains 

5 

4-9 

57 

This  mixture  contains  a  higher  percentage  of  nitrogen  ami  a  l-.urr  |NTcrnUge  of 
|Mitash,  with  tlu-  ivsult  tliat  the  tree  is  in  a  very  weak-wooded  condition,  the  stem 
being  much  bent  owing  to  the  growth  of  a  heavy  top  with  to,,  much  leaf  ^mwth. 
But  the  result  of  this  exi>eriment  was  further  demonstrated  in  I'.MM;,  when  th- 
characteristics  were  shown.  When  the  rubber  trees  are  nianuivd  with  mixture* 
containing  a  large  percentage  of  potash  and  a  small  percentage  <>f  nitrogen,  tin- 
trees  are  all  in  a  good,  healthy  condition,  whilst  the  result  of  the  application  <,f 
manure  containing  a  large  percentage  of  nitrogen  and  a  small  percentajri'  «>t  |M,t.i-h 
is  that  the  tree  has  been  broken  down  by  the  wind  and  thus  destroyed,  owin^  to 
the  tenderness  of  the  wood,  due  to  the  too  strong  application  of  nitrogen  ami  the  t<»o 
weak  application  of  potash  (Fig.  32).  The  above  gives  a  good  illn>trati..n  of  tin- 
effect  of  a  too  high  proportion  of  nitrogen;  but,  nevertheless,  nitrogen  cannot  In- 
allowed  out  of  a  manurial  mixture,  as  the  potash,  phosphoric  acid,  and  Hint  \\ithoiit 
nitrogen  do  not  appear  to  have  their  full  effect,  owing  to  the  deficient  leat^'i "\\tli 
of  the  tree.  Phosphoric  acid  is  also  essential  in  a  manurial  mixture,  a-  it  is  t»und 
to  be  beneficial  in  not  allowing  an  excess  of  leaf-growth,  but  ]mta.sh  appears  t«.  h<>ld 
the  most  important  relation  to  the  rate  of  growth  of  the  trunk  and  branches, 
provided  it  is  accompanied  with  sufficient  supplies  of  phosphoric  acid  and  lin 
a  reasonable  quantity  of  nitrogen  to  induce  free  growth  and  the  absorption  ..t  the 
three  inorganic  ingredients  above  mentioned.  Now  conies  the  question  of  tli 

TABLE  XL — FORMULA  FOR  MANURE  FOR  RUBBER  PLANTATION  on   I .  \M« 
RICH  IN  NITROGEN  AND  GOOD  LEAF-<JKO\\TH. 


Ingredients. 

Chemical  Comi>osition. 

Potash. 
14 

Phosphoric 
Add 

Nitrogen. 

28  per  cent.  Muriate  of  potash  (50) 
25        „        Superphosphate  (18)  . 
20        ,,        Bonemeal  (28/1) 
17        „        Oilcake       . 
10        ,,        Sulphate  ammonia 

4-50 
5-60 

0"J 
!•:: 
_H» 

100        ,,        contains      . 

14 

10-1 

3-1 

400  to  800  Ib.  per  acre  to  be  applied. 


78 


INDIARUBBER 


in  which  the  manures  should  be  employed.  Nitrogen  can  be  employed  in  the 
organic  form  as  fish  guano,  bloodmeal  or  oil  cake,  or  inorganic  as  sulphate  of 
ammonia, 

Phosphoric  acid  can  be  employed  in  various  forms,  such  as  superphosphate  Di- 
basic slag,  but  on  soils  that  are  deficient  in  organic  matter  bones  are  useful. 
Potash  may  be  employed  in  the  form  of  muriate  or  sulphate,  and  in  many  cases 
muriate  seems  to  have  the  best  results  in  the  dry  climates.  The  mixture  given  in 
Table  XI.  is  suitable  on  land  rich  in  nitrogen  and  where  there  is  a  good  leaf-growth ; 
moreover,  the  superphosphate  supplies  both  lime  and  sulphuric  acid  to  the  soil  in 
addition  to  phosphoric  acid. 

On  land  which  is  very  poor  the  following  mixture  is  to  be  recommended  : — 

TABLE  XII. — FOKMULA  FOR  MANURE  FOR  RUBBER  PLANTATION  ON  POOR  LAND. 


Chemical  Composition. 

Ingredients. 

Potash. 

Phosphoric 
Aci.l. 

Nitrogen. 

20  per  cent.  Muriate  of  potash  (50) 

10 

30         ,,        Superphosphate  (18)    . 

.VI 

10         ,,         Boiiemeal  (28/1  ) 

... 

2-8 

o-i 

24         ,,        Sulphate  of  ammonia  . 

4-9 

16        ,,        Oil  cake  (6) 

... 

,-o 

100         ,,         contains 

10 

8-2 

6-0 

400  to  700  Ib.  per  acre  to  be  applied. 

WJien  to  apply  manures. — The  next  question  is,  When  is  the  best  time  to  apply 
these  manures,  and  the  method  of  applying  them  1  Artificial  manures  should  not 
be  applied  during  heavy  rains  or  just  previous  to  the  rainy  season,  as  if  then 
applied  there  is  considerable  loss  due  to  drainage. 

Mode  of  applying  manures — Cattle  manures. — The  manures  can  be  sprinkled 
round  the  tree  at  a  distance  of  from  1  to  1 J  feet  from  the  stem  for  each  year  of  the 
plant's  growth,  and  then  thoroughly  forked  into  the  soil,  or,  in  order  to  secure  the 
manure  not  being  washed  away,  a  shallow  trench  may  be  cut  round  the  tree,  and 
the  manure  forked  therein,  and  the  surface  soil  then  replaced.  Another  point  with 
regard  to  the  manuring  of  rubber  is,  there  is  a  very  large  advantage  to  be  obtained 
by  green  manuring,  whilst  the  use  of  litter  and  cattle  manure  is  also  of  the 
greatest  advantage.  The  cattle  manure  has  a  twofold  effect,  and  that  is,  besides 
acting  as  a  direct  manure,  it  is  also  of  very  great  influence  in  ameliorating  the  soil, 
and  also  the  acids  which  are  formed  are  of  great  benefit  in  making  the  insoluble 
salts  soluble  in  the  soil  and  thus  more  readily  taken  up  by  the  plants.  The  chief 
thing  to  take  into  consideration  about  farmyard  manure  is  that  in  tropical  countries 
it  is  very  scarce,  and  with  the  supply  available  it  is  best  applied  to  other  crops  than 
rubber,  and  for  this  crop  only  to  apply  artificials,  with  frequent  green  manuring. 

Green  manuring. — The  value  of  green  manuring  is  very  great,  but  the  fullest 
advantage  is  only  obtained  by  it  being  supplemented  by  an  application  at  the  time 
of  ploughing  in  of  potash  and  phosphoric  acid.  For  this  purpose  the  potash  is 
best  applied  in  the  form  of  muriate,  and  the  phosphoric  acid  either  as  superphosphate 
or  basic  slag. 

The  following  mixture  should  be  employed  at  the  time  of  green  manuring  : — 


RUBBER   CULTIVATION    IN   VARIOUS  COUNTR 


TABLI  MIL— SH..\\  i\..  COMPOSITION   \M>  tauLYin  «.K  CMKMI.  \i.  M  \SORI 

To    I-.K     AITI.IKI.     IN     .  ..VII    N.    I  |,,N     unit     <;t;|:i  N     \]  SM    , 


:'  I  I.IT  rent.  Muriate  of 

44         „ 

22 


100 


contains 


1    WI 

"IUJMIM 

Lion. 

ish. 

Photphork 

Nitrogen. 

17 
17 

7:9 

»;••_' 

14-1 

6'-2 

0-2 

I 

Of  the  above  mixture  600  to  900  Ib.  per  acre  can  bo  applied. 

If  the  above  points  are  attended  to,  and  a  liberal  supply  of  potash,  phosphoric 
iil,  and  nitrogen  given,  with  periodical  applications  of  green  inauuriiig.  \>  iy 
-n.  .v^tul  results  and  profitable  returns  can  he  obtained  in  the  cultivation  of 
rubber.  (For  further  particulars  as  to  plant  chemistry  and  the  scientific  use  of 
manure,  see  Ayri<-nltnrnl  Chemistry,  by  Ingle  (Scott,  Greenwood,  A:  Son.).) 

IliiMiir  plantations  in  Ceylon.  —  From  an  official  British  Colonial  KejKjrt  for 
the  information  of  those  studying  the  Ceylon  rubber  exhibits  at  the  International 
Rubber  Exhibition  at  Olympia  1908,  it  appear*  that  — 

It  was  not  until  187G  that  a  commencement  was  made  of  Para  rubl>er  cultiva- 
tion in  Ceylon.  In  this  year,  2000  seedlings  were  sent  out  from  Kc\v  t.. 
IVr  fl'-niva,  one  of  the  Ceylon  Government's  experimental  stations.  These  plants 
had  been  raised  from  seed  obtained  by  Mr.  Wickham  from  South  America.  At 
the  beginning  the  plants  were  first  propagated  from  cuttings,  but  when  they  began 
to  flower,  and  seeds  became  available,  the  earlier  method  was  naturally  dropped. 
In  1883,  over  200  seedlings  were  raised  from  seed  obtained  from  the  original  plants, 
and  in  1884,  about  1000  seedlings  were  grown,  the  whole  being  distributed  to 
planters  and  officials  throughout  Ceylon.  From  the  500  original  trees  which  canie 
to  maturity,  the  seed  supply  has  risen  from  200  seeds  in  1883,  to  about  200,000 
at  the  present  time.  Much  of  this  rubber  has  been  planted  throughout  tea, 
and  a  fair  amount  of  the  remainder  is  interplanted  with  cocoa  and  other 
products.  For  instance,  in  the  Kalutara  district  up  to  the  end  of  1900  there 
\\vre  about  L'0,000  acres  under  rubber;  of  this,  however,  only  9000  acres 
were  under  rubber  alone,  the  remainder  being  interplanted  with  other  products, 
chiefly  tea. 

Export*  of  /•///,/»  /•  /rum  Ct'i/fnn.  —  The  following  figures,  showing  the  ex^rta  of 
rubber  from  Ceylon,  are  taken  from  tables  complied  by  the  Colombo  Chamber  of 
(  'oininerce  :  — 

TABLE  XIV.  —  SHOWING  EXPORTS  OF  RUBBER  FROM  CEYLON,  1903-1907. 


Lb. 

Year. 

Lb. 

1903  . 
1904  . 
1905  . 

41,798 
77,213 

168,547 

1906  . 
1907  . 

827,661 
556,080 

This  crop  is,  of  course,  only  derived  from  a  very  small  proportion  of  the  rubber 
already  planted.     Taking  the  age  at  which  a  rubber  tree  can  be  tapped  at  six 
it  will  be  seen,  on  comparison  with  the  figures  given  on  another  jwige,  that  the 


80  INDIARUBBER 

output  for  1907  was  derived  from  not  more  than  4500  acres.  The  planted  area 
in  Ceylon  at  the  present  time  is  almost  forty  times  as  large  as  this,  so  that  in  six 
years  it  would  be  safe  to  put  the  export  at  a  very  much  higher  figure  than  the 
amount  given  for  1907. 

Climatic  conditions. — In  its  native  home,  the  Para  tree  grows  from  the  sea 
level  up  to  a  fair  elevation  on  the  highlands.  The  rainfall  is  usually  between  80 
and  120  inches,  and  the  mean  temperature  between  76°  and  81°  F.  Although  the 
Para  tree  has  shown  itself  to  be  adaptable  to  a  considerable  degree,  it  is  only  a  com- 
paratively limited  area  of  Ceylon  that  seems  to  be  suitable  for  its  cultivation,  as 
elevation  and  rainfall  has  to  be  taken  into  account.  In  a  recent  Surveyor-General's 
report  it  is  stated  that  rubber  is  being  successfully  grown  under  the  following 
conditions : — 

TABLE  XV. — SHOWING  DISTRICT  ELEVATION  AND  RAINFALL  UNDER 
WHICH  RUBBER  is  BEING  SUCCESSFULLY  CULTIVATED  IN  CEYLON. 


District. 

Elevation. 

Rainfall. 

Galle      
Kalutara         ..... 
Passara  ...... 

48  feet 
200     „ 
2800     ,, 

91  inches 
150      „ 

89      „ 

Wright  states  that  in  Ceylon  an  elevation  of  2000  feet  in  the  Central  Province, 
and  3000  feet  in  the  Uva  Province,  is  considered  near  the  maximum,  and  a  rainfall 
of  70  near  the  minimum,  for  the  cultivation  of  this  species. 

The  planting  of  rubber  in  Ceylon. — The  following  are  a  few  brief  notes  on  the 
planting  operations  in  connection  with  rubber  cultivation  : — The  forest  is  cut  down, 
and  when  dry  is  burned.  Drains  are  then  cut,  the  number  and  distance  depending 
upon  the  land.  Holes  are  then  dug,  1 J  feet  deep  by  2  feet  by  2  feet  being  considered 
good,  the  axiom  being  that  the  larger  the  hole  the  better  the  plant,  the  plant  re- 
sponding to  generous  treatment.  The  distance  between  the  holes  depends  upon  the 
planter's  idea  of  wide  or  close  planting.  Para  trees  are  grown  in  Ceylon  from 
10  feet  by  70  feet  to  20  feet  by  20  feet.  The  average,  however,  is  about  180  trees  to 
the  acre.  The  seeds  are  either  planted  out  as  soon  as  they  have  germinated  in  the 
nursery,  or  they  are  allowed  to  grow  there  until  they  have  attained  a  fair  size,  and 
become  what  are  known  as  stumps.  A  still  better  method  is  to  grow  the  seeds  in  a 
rough  basket  in  the  nursery.  When  the  time  for  planting-out  comes,  the  basket  is 
put  in  the  hole  with  the  seed,  and  there  is  thus  no  interruption  of  root  growth. 
Planting-out  operations  should,  of  course,  only  be  conducted  wiien  rain  is  plentiful. 
As  a  general  rule,  all  planted  rubber  is  fenced  in  order  to  protect  it  from  the 
attacks  of  animals.  As  soon  as  the  rubber  is  planted,  the  planter's  main  duties  are 
to  see  that  any  vacancies  are  supplied,  and  to  keep  the  ground  free  from  weeds, 
which  would  interfere  with  the  growth  of  the  young  rubber.  Weeding  is  a  com- 
paratively expensive  operation,  and  many  planters  prefer  to  reduce  the  expense  by 
the  cultivation  of  some  other  product  between  the  lines  of  the  rubber  trees.  In 
most  districts  where  the  cultivation  of  cocoa  is  possible,  this  product  is  the  favourite, 
as  not  only  is  it  profitable,  but  it  seems  to  last  for  a  much  longer  time  when  the 
shade  of  the  rubber  has  grown  dense.  Ground  nuts,  chillies,  lemon  grass,  pepper, 
gingelly,  etc.,  are  also  being  tried  for  the  same  reasons.  Granted  favourable  con- 
ditions, Para  rubber  will  grow  6  to  10  feet  in  height  per  annum  for  the  first  three 
or  four  years.  In  girth,  the  increase  is  about  4  to  5  inches  per  annum  for  the  first 
few  years,  afterwards  increasing  more  rapidly.  Some  of  the  old  trees  in  Ceylon, 
about  thirty  years  of  age,  have  a  circumference  of  over  100  inches,  and  are 
about  80  feet  in  height.  These  trees  were  not  grown  Tinder  the  most  favourable 
conditions. 

Tapping  the  rubber  tree  in  Ceylon. — When  the  tree  attains  a  circumference  of 


RUBBER   CULTIVATION    IN    VARIOUS   COUNTRIES        81 

20  inches  at  a  yard  from  the  ground,  which  is  more  often  than  not  in  il  w, 

tapping   is  commenced.     '|'i.  -.pe;lk   <>t'  tin-   varioitH  tpping  there  ia  no 

space  available.       All  aiv  based   upon  the  one  Illain   l'ai-t,  that   i..-t\\.  cii  tin-  outer  Ijark 

aih I  the  wood  there  exists  an   inner  bark  provided  with  a  system  of  U: 
When  our  uf  these  tubes  is  pierced,  the  latex  milk,  or  >ap,  exudes.     Those  latici 
fe  PHIS  tube-   are   \erv  minute,  and    in   tin-    I'ar.i   tree   the   l.itex  may  approximate] . 
be  saiil  to  exude  only  from  the  tube  ineis.-d,  or  at  the  m..M  from  its  near  neighbour*. 
It  is  necessary,  then-fore,  in  order  to  get  a  good  yield  of  rubber,  to  : 

year  as  niiieh  bark  in  thin  shaving  as  the  tree  \\ill  >taiid.  economy  of  bark,  i 
in  comparison  with  the  yield,  ha\ing  t"  be  taken  into  account.  Koiighly  .-jn-ak 
it  m.iy  be  said  that  the  l»ark  of  the  tree  up  to  6  feet  from  it-  Uisr  is  divide*!  up  into 
four  pails  for  four  years'  tapping.  The  >imple>t  method  is  the  "  hall'  herring 
bone."  A  \vrtieal  ehannel  is  cut  down  the  tree  in  order  to  convey  the  latex 
to  the  cup  at  the  foot  of  it.  Two  or  more  oblique  cuts  are  made  a  quarter  round 
the  tre,- and  connecting  with  this  channel.  Every  alternate  day  a  thin  sha\  ing  ia 
taken  otl  the  bottom  of  each  of  these  cuts,  and  so  on  until  the  bark  between 
the  cuts  is  all  used  up.  Then  the  other  side  of  the  vertical  channel  is  U-gun  upon, 
and  when  that  is  finished  the  operation  is  repeated  on  the  other  side  of  the  tree. 
The  bark  grows  again  fairly  rapidly,  from  above  downwards,  and  from  inside  out 
wards.  Although  the  renewal  of  the  bark  does  not  take  long,  it  Is  some  time, 
however,  before  the  latex  tubes  are  rich  in  latex,  and  for  this  reason,  generally 
speaking,  the  renewed  bark  is  left  untouched  for  four  years,  when  it  has  been  found 
to  yield  a^  well  as  the  original  bark.  s  The  greatest  care  has  to  k-  taken  not  to 
touch  the  cambium  or  wood  of  the  tree^as  this  not  only  injures  it,  but  also  makes 
t  he  >m  face  irregular,  so  that  tapping  is  difficult,  or  in  bad  cases  impossible.  In  order 
to  avoid  this,  many  tapping  knives  have  been  invented,  some  of  which  have  met  with 
a  fair  measure  of  success. 

The  preparation  of  rubber  in  Ceylon — Coagulation. — The  latex,  as  it  exudes 
from  the  tree,  is  in  the  form  of  a  white  milky  fluid.  Upon  standing,  however,  or 
by  the  addition  of  acid,  it  coagulates ;  that  is  to  say,  the  rubber  globules  separate 
out  from  the  rest  of  the  liquid,  and,  uniting,  form  a  jelly-like  substance,  sumVieiitly 
firm  to  be  handled.  Jiim-uif  robber. — At  first,  this  coagulation  was  done  in  dairy 
pans,  and  the  resulting  "biscuit"  of  rubber  (so  called  from  its  shape')  was  washed 
by  hand,  and  put  upon  wire  shelves  to  dry,  a  process  which  took  considerable  time. 
d-i'/x  riiiiln  r. — Xow,  however,  on  most  of  the  larger  producing  estates,  the  co- 
agulated rubber  is  put  into  a  washing  machine,  consisting  of  a  pair  of  very  heavy 
corrugated  cylinders,  revolving  at  different  speeds ;  an  ample  supply  of 
poured  upon  the  rubber  as  it  goes  through  the  cylinders,  which  is  drawn  into  the 
finest  films  in  the  process,  the  operation  being  continued  until  the  rubU-r  i> 
thoroughly  washed,  and  free  from  all  grit,  bark,  or  other  impurities.  The  rubber 
coining  from  the  machine  in  the  form  of  a  thin  sheet,  with  nu ml wrless  corrugations 
on  its -surface,  is  then  hung  up  in  the  drying-room,  and,  owing  to  its  thii. 
great  surface  exposed,  dries  very  quickly,  and  comes  on  the  market  in  the  form  of 
"cre"pe."  Other  forms  of  cultivated  rubber  are  "sheet,"  "smoked  sheet,"  and 
"block." 

Cost  of  rubber  rv////m//'.,//  ///  Ceylon. — Ceylon  has  long  been  famous  for  its 
labour.  Not  only  has  it  a  native  imputation  available  for  a  proportion  of  the  work 
done  on  the  estates,  but  it  has  also  the  valuable  supply  of  lalxmr  from  Southern 
India  to  drawn  upon,  and  in  the  past  this  has  formed  the  main  source  of  supply. 
With  this  and  the  favourable  soil  and  climatic  conditions,  Oylon  is  eminently 
suited  for  the  growth  of  rubber.  From  estimates  made  by  well-known  planters  in 
1905,  it  would  appear  that,  exclusive  of  the  cost  of  land,  the  expenditure  required 
to  plant  and  bring  to  maturity  an  acre  of  rubber  amounted  to  about  £20.  .s 
then,  however,  advances  have  gone  up,  contract  rates  have  increased,  and  planters 
are  spending  more  on  clean  weeding  than  was  then  thought  necessary.  It  would 
be  safe,  howexer,  to  put  the  cost  at  £25  per  acre  on  a  well  managed  estate  of  a 
fair  si/e.  This  would  include  everything  except  the  land,  the  price  of  which  va 
6 


82  INDIARUBBER 

but  will  certainly  not  average  more  than  <£5  per  acre  ;  or,  say,  .£30  in  all,  up  to  the 
end  of  the  sixth  year. 

The  yield  of  rubber  in  Ceylon. — The  yield  of  rubber  from  individual  trees  varies 
enormously.  The  average  per  acre  for  trees  of  the  same  age,  however,  is  fairly 
constant,  and,  futhermore,  the  yield  per  acre  is  the  safest  method  of  calculating 
possible  returns.  From  the  results  published  in  companies'  reports,  official  reports, 
and  the  literature  on  the  subject,  it  is  evident  that,  provided  the  climatic  conditions 
and  soil  are  suitable,  a  yield  of  100  Ib.  per  acre  by  the  end  of  the  seventh  year  can 
be  safely  reckoned  upon,  while  the  eighth  year  will  give  150  Ib.,  and  the  ninth  year 
200  Ib.  per  acre,  and  so  on  increasing  as  the  trees  grow  older.  Practice  has  shown, 
of  course,  that  in  most  cases  a  large  yield  can  be  got  from  rubber  in  its  sixth  year, 
and  even  earlier,  so  that  the  figures  given  can  be  taken  as  conservative.  The  cost 
of  collecting,  preparing,  and  selling  this  rubber,  including  all  fixed  charges,  is  now 
known  to  be  about  Is.  8d.  per  Ib.,  with  a  great  probability  of  a  decrease.  The 
price  of  plantation  rubber  in  London  to-day  is  about  4s.  2d.  per  Ib.  This  leaves 
a  margin  of  2s.  6d.  per  Ib.  net  profit.  Upon  these  figures,  therefore,  it  would  seem 
that  the  initial  expenditure  of  .£30  would  be  covered  by  rubber  obtained  in  the 
seventh  and  eighth  years,  and  that  in  the  ninth  year  the  investment  would  yield 
over  80  per  cent.  These  calculations  are  based  on  rubber  at  the  present  price  of 
4s.  2d.  per  Ib.,  but  the  fluctuations  in  value  during  the  past  few  years  have  been 
considerable,  as  shown  by  the  supplement  giving  the  price  obtained  for  rubber  from 
1861  to  1903.  Since  1903,  the  rubber  market  has  been  subject  to  the  same  causes 
as  affected  nearly  every  other  crude  material.  The  financial  crisis  in  America  in 
the  autumn  of  1907  resulted  in  not  only  a  cessation  of  the  American  demand,  but 
also  in  a  large  quantity  of  their  purchases  being  thrown  upon  the  market,  with  the 
result  that  rubber  fell  to  2s.  9d.  per  Ib.  Since  then,  however,  it  has  steadily 
improved,  until  to-day  (1908)  it  is  worth  4s.  per  Ib. 

Guayule  rubber. — The  very  partial  success  of  Castilloa  plantations  in  Mexico 
rendered  the  appearance  of  a  new  plant  from  which  rubber  could  be  extracted  by  a 
chemical  process  highly  welcome.  Guayule  rubber  cannot  certainly  compete  with  the 
good  sorts  of  rubber,  but  it  can  very  well  be  mixed  with  them.  It  is  a  rubber  of 
medium  value.  This  rubber  has  been  known  for  a  long  time,  especially  in  the 
State  of  Durango.  It  was  Father  Negrete,  the  Jesuit,  who  made  its  value  known, 
eighteen  years  ago.  The  Guayule,  Partliagenium  argentatum  (Synantherea 
mexicana),  is  a  tree  from  8  to  40  inches  in  height,  which  flowers  in  October. 
Its  wood  is  used  as  fuel,  for  which  purpose  it  is  very  good.  It  dies  after  a  life 
of  fifteen  years.  This  plant  bears  several  names,  such  as  Guayule,  or  Hayule  (hule 
means  rubber  in  Indian) ;  in  the  State  of  Durango,  it  is  called  Yerba  de  Hule,  Yule 
in  the  northern  parts  of  San  Luis  de  Potosi,  and  Jiguihite  near  Saltello.  Moreover, 
it  is  sometimes  confused  with  a  medicinal  plant  called  Yerba  del  Negra.  There 
is  a  mistake  also  as  to  the  extent  of  its  distribution,  which  is  not  very  consider- 
able. The  districts  of  Chihuahua,  the  north  parts  of  Zacatecas  and  of  San  Luis  de 
Potosi,  the  east  of  Durango,  produce  the  most.  It  lives  more  especially  at  altitudes 
of  900  to  1 700  metres  above  sea-level  in  any  soil  rich  in  lime.  It  springs  up  in 
sparse  tufts  or  continuous  tracts.  Its  distribution  per  acre  is  therefore  difficult  to 
ascertain.  The  plants  weigh  100  grammes  (say  3J  oz.)  to  3  kilos.  (6'6  Ib.)  per  stock, 
with  an  average  of  500  grammes  (I'l  Ib.).  There  is  on  an  average  500  to  800 
kilos,  of  plants  per  hectare  (say  440  Ib.  to  704  Ib.)  per  acre.  Altogether  one  may 
count  on  70  square  kilometres  (43,400  square  miles).  Latex  does  not  exist  in  the 
bark  of  the  Guayule  as  in  the  Euphorbia  or  the  Apocynaceae.  The  rubber  is  found 
dissolved  in  the  cellular  sap  of  the  wood  and  the  bark.  It  is  not  present  in  the 
leaves,  nor  in  the  fruit ;  the  wood  yields  less  rubber  than  the  bark,  but  gives  a 
purer  product ;  the  ratio  of  the  two  quantities  is  as  7  to  2.  The  bark  also  contains 
aromatic  balsamic  bodies,  and  sometimes  a  noxious  gummy  product,  which  flows 
in  drops  over  the  surface  of  the  shrub.  This  product  diminishes  the  value  of  the 
Guayule.  The  plants  are  allowed  to  dry  in  the  air  for  some  days,  so  as  to  be  able 
to  crush  them.  They  produce  generally  44 '5  per  cent,  of  bark,  47  per  cent,  of 


RUBBER   CULTIVATION   IN   VARIOUS   COUNTRIES 


wood,  an.  I    S  |,er  rent.  ••!'  teoVML        r'if'N'eii   |H-S..>  .llv   |*tJ4i  for  a  toil  of 

(luayiile.       I'.ut  the    price  VAlim  witl    tin-    >ituati«m  •  if   tli.-   r.niiitn  or  tin-  fit. 
Cuayiile  i>  ti,iiis|.i.rtft|  in  tnUMfl  l«y  rail. 

A'r//v/i-//..//  procet969,     'I'hriv  are  -.^ri-al  «,i   tin--..-.      Bflign  .in  Patent 

L'l  \1,  cm,  lies  thr  plant   in  a   Knij,|,  .li^inl.-.:r:»t..i-.  Him  in  a  mill  with  lalU  until  all 


the  wood  is  sfjiarati'il.  ami  tin-  rnlil»«T  t'unns  l-alls  with  the  remaining  wood. 
Thesi'  halls  are  phu-ed  in  a  sti-am  ja^ki-tted  inni  ^68801  I>iiring  boiling  SOine»oda  » 
added,  but  that  is  not  absolutely  ne.-,-^ary.  The  whole  is  then  run  into  wooden 
vessels,  \\heiv  tlie  nil. her  is  \\ashed  with  cold  water.  It  is  afterwards  nifted  in  a 
sieve  with  a  false  bottom.  The  rubber  i>  airain  wa<ln-d  with  soda  and  precipitated 
by  chloride  of  calcium,  j>ossibly  injurious  owiug  to  the  action  of  the  free  chlorine  on 


84  INDIARUBBER 

the  rubber.  The  methods  by  which  the  finely  ground  wood  is  treated  by  steam 
are  more  simple.  Soda  ley,  of  10°  to  12°  B.,  is  used  with  a  pressure  of  6  to  14 
atmospheres  (1).  The  soda  is  neutralised  by  weak  acids.  Possibly,  the  American 
factories  use  carbon  disulphide  for  this  extraction.  The  rubber  obtained  by 
the  ordinary  method  is  black  on  the  surface,  and  grey  in  the  interior.  Its  drawback 
is  that  it  contains  27  per  cent,  of  gummy  or  aromatic  substances,  which  render  it 
tacky.  Guayule  is  easily  vulcanised ;  its  unpleasant  smell  comes  from  the  aromatic 
bodies  which  it  contains.  At  Jimulco,  this  rubber  has  been  so  much  improved 
that  there  are  only  10  to  15  per  cent,  of  substances  present  other  than  its  water.  This 
variety  sells  at  5s.  the  kilo.  (2s.  3d.  the  Ib.)  instead  of  3s.  per  kilo.  (Is.  4d.  the  lb.),  the 
price  of  the  former.  Rubber  which  only  loses  5  per  cent,  on  washing  is  worth 
7s.  to  8s.  the  kilo.  (3s.  2d.  to  3s.  7d.  per  lb.)  in  Great  Britain  or  Germany.  The 
plant  produces  according  to  its  humidity  8  to  12  per  cent,  of  crude  rubber,  say 
6 '8  to  10  per  cent,  of  good  caoutchouc.  A  factory  to  produce  a  ton  a  day  of  Guayule 
rubber  would  require  to  treat  10  to  14 '8 6  metric  tons  of  plants,  which  would 
require  16-7  to  23*8  hectares  (40  to  60  acres)  to  exploit  per  day,  say  6 '01 2  to  8 '588 
hectares  annually  (say  15,000  to  21,473  acres).  The  difficulties  of  such  an  under- 
taking are  evident,  especially  when  the  factory  is  far  from  the  spot  of  production. 
Asses  are  the  animals  best  adapted  for  the  transport  of  the  raw  material  The 
ton  of  Guayule  shrubs  transported  by  them  costs  4 '9 7  to  5 '80  pesos  (say  10s.  6d. 
to  12s.)  for  a  journey  of  20  kilometres  (12'4  miles).  The  want  of  water  for  the 
recovery  of  the  rubber  is  a  cause  of  much  anxiety.  The  selling  price  of  Guayule 
is  low.  It  may  be  taken  that  the  75,000  square  kilometres  producing  Guayule 
will  only  yield  26,250  to  37,500  tons  of  rubber.  It  is  therefore  desirable  to 
cultivate  these  plants,  and  cheap  land  lends  itself  to  this  admirably.  It  is  not 
known  how  long  the  seed  of  Guayule  takes  to  develop.  In  eight  to  ten  years  the 
plants  reach  their  average  height,  but  young  plants  also  yield  rubber.  One  can 
reckon  on  200  grammes  per  plant  as  weight  after  six  years,  and  4000  kilos,  (say  4 
metric  tons)  of  plants  per  hectare  (say  1  -6  tons  per  acre).  Whether  the  rubber  from 
cultivated  plants  will  be  the  same  as  that  from  the  wild  Guayule  remain  to  be 
seen.  Guayule  has  the  following  good  points  : — 1.  It  is  not  exacting  as  regards  soil 
or  humidity.  2.  It  grows  in  a  more  healthy  climate  than  the  Tropics.  3.  It 
may  be  cultivated  all  the  year  round.  4.  Its  culture  gives  reason  to  hope  for 
profits.  As  some  parts  of  South  Africa  have  an  analogous  climate,  it  is  desirable 
not  to  lose  sight  of  this  plant. 

Funtumia  elastica  (Kickxia  africana,  formerly  so  called). — A  new  rubber  plant 
came  all  at  once  into  prominence  in  the  colony  of  Lagos  in  1894,  namely,  a  hand- 
some tree,  locally  known  as  Ire,  Ireh,  or  Ereh,  belonging  to  the  same  natural 
order  as  the  Landolphias.  It  was  erroneously  determined  from  data  accumulated 
at  Kew  to  be  Kickxia  africana,  Benth.,  a  tree  said  to  be  widely  distributed  in 
West  Africa  from  Sierra  Leone  to  the  delta  of  the  Niger,  the  island  of  Fernando 
Po,  and  the  Gaboon.  It  is  believed,  says  Morris,  that  rubber  was  first  obtained  from 
it  on  the  Gold  Coast  in  1883.  In  1888  seeds  of  it  were  introduced  to  Europe  as  a 
substitute  for  Strophanthus  seed,  and  stated  to  be  worth  72s.  per  lb.  They  were 
called  "  indiarubber  "  seeds,  but  nothing  further  could  be  obtained  respecting  them. 
The  following  extracts  are  taken  from  the  "Kew  Bulletin,"  1890  (pp.  242,  247)  :— 

"In  September  1894,  Kew  received  from  Captain  Denton,  C.M.G.,  two  pieces 
of  the  trunk  of  the  Lagos  rubber  tree,  each  about  10  inches  to  1  foot  in  diameter, 
scored  with  the  marks  of  the  rubber  gatherers.  They  were  sent  as  the  *  female ' 
rubbertree,  a  name,  we  learn,  that  is  locally  applied  to  the  Kickxia  africatm,  Benth. 
It  is  thus  distinguished  from  Holarrhena  africana,  quite  a  different'  plant,  which  is 
fancifully  called  the  '  male '  rubber  tree.  The  latter  is  also  an  Apocynaceous  plant, 
but  not  known  to  yield  any  rubber. 

"  In  tapping  the  trees  the  bark  is  first  cut  in  a  vertical  direction  from  the 
bottom  to  the  top.  This  single  line  is  about  J  to  f  of  an  inch-  broad,  and  deep 
enough  to  reach  the  inner  bark.  This  forms  the  main  groove ;  on  each  side  of  this 
two  series  of  oblique  grooves  about  2  feet  apart  are  cut,  each  running  into  the 


RUBBER   CULTIVATION    IN   VARIOUS   COUNTRIES        85 

main  groove.  The  side  grooves  an-  made,  beginning  at  the  top,  and  gradually 
reaching  tin-  l>ase  of  tin-  tree.  All  tin-  milk  exuding  from  the  lateral  grooves  will 
timl  \\-  \\a\  into  tin-  main  groove,  and  so  ultimately  reach  the  bottom,  where  a 

I   ifl  placed  to  rereixe  it.      |  This  i-  t  lie  II-TI  in-  I •  -\  -lein  of  tapping.]      When 

siitlieient  milk  ha-  accumulated,  it  is  then  collected  and  made  into  rubber. 

"The  method-,  adopted  for  coagulating  the  milk  are  then  described.  Tin 
at  present  of  t\\o  kinds,  namely,  'the  cold  process'  and  'the  heat  pTOcetsJ  The 
cold  process  is  chiefly  practised  by  the  Fanti  men  introduced  from  the  Gold  Coast. 
\  cavitj  is  excavated  in  the  trunk  of  a  fallen  tree  so  as  to  form  a  cistern  of  the 
capacity  necessary  '">'  holding  the  milk  collected  during  several  days.  Into  thi> 
the  rulil MM-  gatherers  pour  the  milk,  after  straining  it,  from  day  to  day  until  it  is 
«|iiite  full.  It  Uthen  covered  \\ith  palm  lea\es  and  left  for  twelve  to  fourteen  days, 
and  >oinetimes  much  longer,  depending  on  the  season,  until  most  of  the  watery  portion- 
ha\e  either  evaporated  or  sunk  into  the  wood.  After  being  kneaded  and  pp-^.-d 
together,  the  rubber  thus  obtained  has  a  dark  brownish  colour,  with  the  inner 
portions  of  a  slightly  lighter  colour.  Such  rubber  is  known  locally  as  'silk 
rubber.'  The  local  price  is  from  lOd.  to  Is.  2<1.  per  ll».  The  heat  process  is 
the  one  generally  adopted  by  the  natives  of  Lagos.  This  is  much  simpler  in 
\sorking,  as  it  disposes  of  all  the  milk  collected  at  the  close  of  each  day.  After 
being  strained  the  milk  is  placed  in  a  vessel  and  boiled.  The  rubber  begins  to 
coagulate  almost  directly  the  heat  is  applied,  and  after  the  boiling  is  over  is 
removed  in  a  somewhat  sticky  condition  owing  to  being  burnt,  and  of  a  blackish 
colour.  The  local  price  of  this  rubber  is  from  9d.  to  Is.  per  Ib.  It  is  pointed  out 
that  the  heat  process,  though  simpler,  impairs  the  quality  of  the  rubber,  and  is 
calculated  to  injure  the  industry.  It  is  probable  that  if  the  heat  process  were  some- 
what modified  the  results  would  not  be  so  injurious.  An  experiment  was  tried  at 
the  Botanic  station  to  coagulate  the  milk  by  heat  but  not  applied  directly  to  it. 
The  result  was  much  more  satisfactory.  The  rubber  came  off  a  milky  white  colour, 
and  after  being  pressed  it  was  clean  and  firm  without  being  sticky.  The  history 
of  this  new  rubber  industry  in  Lagos  is  full  of  interest,  and  illustrates  the  wonder- 
fully rich  resources  of  the  vast  forests  of  West  Africa.  It  shows  also  very  clearly 
how  largely  these  resources  can  bo  developed  by  judicious  and  intelligent  action  on 
the  part  of  the  government. 

"  Should  the  new  rubber  l\i<-lc,i-i<i  continue  of  commercial  value,  there  is  no  doubt 
that  it  will  eventually  be  possible  to  establish  regular  plantations,  and  thus  make 
the  industry  a  permanent  one.  It  has  always  been  seen  that,  owing  to  the  climbing 
habit  of  the  speeies  of  the  La  mini /Ala,  which  have  hitherto  yielded  African  rubber, 
it  was  not  practicable  to  cultivate  them  in  regular  plantations,  as  they  required  the 
support  of  other  plants,  and  when  once  tapped,  many  years  would  have  to  elapse 
before  they  would  be  fit  to  yield  another  crop.  With  the  Kicksia  these  practical 
difficulties  disappear.  According  to  Chalot,  Kickxia  a/fi<-«/ta  has  been  found 
lately  in  Gaboon.  Specimens  have  been  measured  1  metre  in  circumference  and 
1- to  15  metres  high.  Each  tree  is  estimated  to  yield  annually  without  any  injury." 

But  the  Kew  authorities  were  apparently  in  error  in  their  botanical  determination 
of  this  rubber  tree,  for  Wright,  Cantor  Lectures,  1907,  says  : — 

•  •  /•'// // / // mia.  This  genus  has  lately  become  known  as  a  source  of  rubber  in  Africa. 
It  is  still  much  confused  \\ith  the  genus  /\V.-/-.,-/Vi,  and  it  is  as  well  to  again  point  out 
that  Africa  does  not  pi  teaeee  a  single  species  of  Kickxia  of  value  as  a  rubber-producing 
plant.  The  four  species  of  Kickxia  acknowledged  by  Stapf.  are  found  only  in  Java, 
Celebes,  Philippine  Islands,  and  Borneo.  The  genus  Fun* muni  is  partly  African, 
and  is  represented  by  three  secies — F.  elastica,  Stapf.,  F.  africana,  Stapf.,  and 
F.  latifolia,  Stapf.  The  species  of  importance  as  a  source  of  rubber  in  Africa  is 
F.  elastica,  Stapf.  Its  occurrence  has  been  recorded  in  Liberia,  Gold  Coast,  Ashanti, 
Lower  Nigeria,  Cameroons,  Mundanie,  French  Congo,  Congo  Free  State,  Uganda, 
etc.  The  rubber  from  this  species  is  very  valuable,  possessing  when  properly 
1  »i v pared  from  80  to  90  per  cent,  of  caoutchouc.  /•'//  //  /  //  //« fa  elastica  has  been  described 
as  a  tree  with  a  cylindrical  trunk  which  attains  a  height  of  100  feet ;  sometimes  the 


86 


INDIARUBBER 


tree  occurs  more  abundantly  in  local  areas,  and  out  of  an  area  of  about  54  square 
miles  as  many  as  1,760,000  trees  have,  as  previously  stated,  been  estimated  to  occur. 
Rubber  in  Cochin  (India). — Rubber  was  first  planted  on  any  scale  in  1905, 
when  Mr.  K.  E.  Nicoll  obtained  a  grant,  of  forest  land  at  Palapilly,  behind  the 
Government  teak  plantation.  This  was  a  well-situated  block,  at  the  foot  of  the 
hills,  with  the  Chemoni  River  running  through  the  centre.  Some  40  acres  were 
opened  in  1905;  and  later  on,  in  the  same  year,  Mr.  E.  G.  Windle,  on  behalf  of  a 
syndicate,  took  up  an  adjoining  block  of  forest  now  called  Pudukad.  In  1906 
there  were  some  300  acres  opened  on  each  place,  and  in  1907  the  balance  of  the 
land  was  opened,  Pudukad  being  in  all  some  650  acres,  and  Palapilly  nearly  500, 


FIG.  34. — Two  and  three-quarter  years  old  Para  trees,  Palapilly  estate,  Cochin. 

the  two  places  making  a  fine  sheet  of  over  1100  acres  of  rubber.  The  conditions 
here  are  very  favourable,  the  elevation  being  almost  sea-level,  rainfall  about  150 
inches,  and  surrounding  hills  sheltering  the  basin  from  wind.  As  a  result,  growth 
has  been  remarkably  fine,  and,  according  to  those  who  have  seen  both,  it  may 
challenge  comparison  with  fine  Straits  growth.  The  plantations  are  some  eight 
miles  by  cart  road  from  the  Pudukad  Station  on  the  Cochin  Railway,  and  about 
twenty  miles  from  the  coast.  In  1906  also  a  grant  of  Government  forest,  six  miles 
from  Trichur  Railway  Station,  and  lying  on  the  main  road  from  Trichur  to 
alghat,  was  obtained  by  E.  G.  Windle  and  R.  E.  Campbell-Gompertz,  who  opened 
'0  acres,  and  subsequently  disposed  of  the  block  to  the  Cochin  Rubber  Co.  Ltd., 


RUBBER  CULTIVATION   IN   VARIOUS  COUNTRIES        87 


Of    Colombo,    ill     who,,-     name    tin-    <  ioNeriimeiit     titlt-    \\.is    i^u,-,|.        This    COnsisU    Of 

..f  \\iiich  HIM  ,l(  iv-  were  opened  in  P.»H;,  UOO  in  1907,  and  L'MU  in 
1908,  200  bein.u'  forest      Kli-\;iti«»u  ami  rainfall  an-  lunch  the  same  as  at  Puduka.l 

anil     I'alapilK.  and    i_rro\\th    lias    been    excellent.       Then-    arc,    therefore,  at   present 
some   I'.'MM   aCTOfl   "f    I'ara    opened    iii    ('ochin.       Many    other  applications   for   land 
have  been    made,  I.  nt    \\crc    refilled    by  the    hurbur    (Cochin    <  i"\.-i  nincnt),   on   the 
ground  that  it    had    in   !•••   M-CII  \\hether   nil.  li«-r  \\.nild    I..-  successful.      There  seems 
ini  r  ......  i  to  dtiiilit   this  now.  and  it   is  to  be  Imped  that   further  land  may  IN-  available 

to  the  pulilic  fur  tea  a-  \\ell  as  rubber.  Tin-  fore-t  v|()prs  \\hich  are  now  lieing 
tapped  li\  the  tram\\a\,  mi-lit  ren^.iiably  be  surveyed  with  the  \ie\\  of  opening 
suitable  parts  ;  there  are  probably.'^)  to  100,000  acres  which  would  grow  one  or 
other  of  the  above  products  without  unduly  interfering  with  forest  resources. 

llnMn  r  I'u/finifiuu  in  l>nf'-lt  llorn'o.    -Horne,,  \\ith  13,000  square  miles  is  I 
than  llritain,  Germany,  and  Switzerland  combined.      The  interior  i>  more  healthy 
than  districts  >ome\\hat    nearer  the  coa-t.      Starting  from  the  j>ort  of  Ban<ljcrma>in 
(S0!'!''  latitude  ami  114°  38'  longitude),  going  intoNegara  and  Tabalong,  Taudjong 
is  reached  at  'J^O  kilometres  from  ]>andjerma<in,   wliere   there  is  virgin  noil  and 
rul>l>er  trees  \\hi<  h  yield    Borneo  rubber,  namely,   Ficua   couwiato,  and  the  \ 
II  '/////////  /«•/•/  and    Urceola.     There  is  not  a  single  Ifevea   nor   /•'<'<•,/.<  ,/,i.<f  ,',-,,  \\hidi 
yield  \\ild  rubber.      The  rubber  goes  to  Bandjermasin,  the  chief  port  of  the  south 
and  west  of  Borneo. 

This  rubber  was  formerly  adulterated  by  means  of  all  sorts  of  detritus,  which 
brought  it  into  discredit.  The  climate  is  hot.  But  the  heat  is  not  often  unbearable  ; 
'2\  metres  of  rain  fall  annually.  The  European  can  therefore  live  there.  Schram 
of  Dresden  lived  there  eight  years,  and  saw  no  Euro[)ean  die  there.  There  is  no 
want  of  cheap  labour  if  their  habits  be  not  crossed  at  every  step.  Everything 
goes  well  since  private  companies  have  set  to  work  in  the  country.  Trade 
communication  is  by  rivers.  Telegraphs  and  telephone  have  been  in  use  some 
years,  and  life  there  is  not  one  of  isolation.  Plantation  experiments  have  been 
made  in  the  district  of  Tabalong  and  Kaloewa  with  gutta  and  rubber  trees, 
J'ti/n</nJi///i  ohlonyifolium  et  borneense,  Hevea  A/v/;///r//.s-/s,  Ficus  elastica,  Castilloa 
t/'infii-.f.  The  /'/I-HS  elastica  appears  to  succeed  best.  Plantations  are  also  to  be 
found  in  Martapoere,  Kendagan,  and  Doesoen  ;  marshy  ground  is  less  propitious. 
The  Ficn*  neither  fears  humidity  nor  drought  ;  its  wood  burns  badly,  an  advantage 
against  fire.  In  1892,  "layers"  of  Ficus  elastica  from  the  Botanic  Garden  of 
•lava  were  planted  in  the  district  of  Tabalong  by  a  German  tobacco  company. 
There  are  now  more  than  100,000  trees.  The  propagation  of  this  tree  is  simple 
and  costs  little.  Its  product  analysed  in  Holland  and  Germany  was  regarded 
as  very  ^ood,  and  it  was  quoted  at  6'8  marks  per  kilo,  in  Hamburg  in  1903.  Its 
culture  is  therefore  assured  of  success.  Weber  and  Schser  of  Hamburg  rate  this 
rubber  as  follows:  —  No.  1,  Cakes.  —  Pale,  porous,  moist  inside,  pure,  roilicnt.  might 
be  used  for  making  ebonite;  value  about  6  marks  to  G*3  marks  per  kilo.  N,,.  •_'. 
7V//x.  —  -Very  dry,  resembles  African  twits  ;  value  S  marks  per  kilo.  No.  3,  Scraps  — 
Kesembles  Java  rubber,  fresh  and  white,  resilient  ;  value  t',-7  marks  per  kilo. 
The  Kolonial  Museum  of  Haarlem  gives  the  following  analysis:  — 

TABLE   XVI.—  SHOWING  THE  COMPOSITION  OP  Ficus  ELASTICA  RUBBER 

CULTIVATED    IN    BORNEO    (HAARLEM    KOLONIAL    MUSEUM). 


T 

H. 

Pure  Rubber          
Resins  
Impurities    
Water  

89-5 
3-7 
0-2 
6-6 

856 
6-4 
1-0 

7-0 

100-0 

100-0 

88  INDIARUBBER 

Dieterich  Helgenberg  also  analysed  Borneo  Ficus  rubber,  and  found  :— 
TABLE  XVI  A. — SHOWING  THE  COMPOSITION  OF  Ficus  ELASTIC  A  RUBBER 

CULTIVATED    IN   BORNEO    (HELGENBERG). 


Per  cent. 

1-025 

Resin    ......... 
Ash       
Non-rubber  ........ 

4-2 
6-514 
5-51 
88-56  to  88-72 

It  is  a  good  rubber,  compared  with  certain  Asiatic  rubbers,  which  have  less 
than  30  per  cent,  of  rubber.  Van  Romburgh  and  Henriques  recommend  the 
plantation  of  the  Ficus  in  Borneo.  The  oldest  trees  in  a  plantation  of  5000  trees 
in  Java  Pamanocken  in  Trassemlanden,  planted  since  1863,  yield,  according  to 
Dinet,  1000  grammes  of  rubber  per  tree  in  1899,  1640  in  1900,  and  1310  in  1901. 
Van  Romburgh  also  gives  some  data  on  this  subject.  At  Tijandi  in  Bantero,  trees 
of  twenty-four  years  old  yield  2 \  kilos,  to  3  kilos,  per  tree.  Trees  of  two  to  six  years 
yield  530  grammes  of  rubber.  According  to  Van  Romburgh,  only  plants  in  full 
vigour  should  be  planted.  They  may  be  tapped  every  year  after  eight  years.  Collet 
estimates  that  a  five-years-old  tree  gives  500  grammes  of  rubber. 

Rubber  in  the  Philippines. — The  U.S.A.  are  making  strenuous  efforts  to 
develop  the  exploitation  of  indigenous  species  (all  of  which  are  vines) ;  moreover, 
a  recent  official  report  says  a  species  of  Para  tree  is  now  growing  in  Manilla, 
and  apparently  the  climate  is  suitable.  The  Bureau  of  Agriculture  has  distributed 
many  Ceara  rubber  seeds,  and  the  growth  of  the  seedlings  is  marvellous. 

Much  more  might  be  written,  did  space  permit,  of  the  cultivation  of  rubber- 
bearing  trees  in  tropical  lands  all  round  the  globe — in  the  West  Indian  Islands, 
Dominica,  St.  Lucia,  Jamaica,  Trinidad ;  in  Africa,  on  both  the  east  and  west 
coasts  ;  and  in  Madagascar,  Travancore,  Java,  Malaya,  and  other  parts  of  Asia  and  the 
adjoining  archipelago.  The  vast  demand  for  this  product  has  led  to  innumerable 
experiments,  which  will  probably  result  in  a  continuous  "  rubber  belt "  encircling 
the  globe  at  that  part  of  its  circumference  which  favours  the  growth  of  rubber- 
producing  plants. 

Gold  Coast  rubber.— First  exports  in  1880,  1200  Ib. ;  in  1890  they  exceeded 
3J  million  Ib.  From  1891  to  1900  rubber  most  important  export  value  in 
1899,  £555,731;  decade  average,  £321,265.  But  1901-03  showed  marked 
decrease  due  to  Ashanti  disturbances  and  destruction  of  forest  trees  by  unskilful 
tapping,  and  to  French  and  German  Colonial  rubber  no  longer  being  shipped 
from  here,  and  enticements  to  labour  in  mines,  cocoa  culture,  etc.  Hence  the  value 
fell  in  1901  to  £88,602  (lower  than,  any  year  since  1899).  But  rubber — value 
£360,644— in  1904  resumed  first  place  in  exports,  and  if  figures  for  1905-07  are 
slightly  less,  and  values  for  output  of  gold  and  cocoa  exceed  respectively 
£1,000,000  and  £500,000,  the  rubber  shipped  in  any  one  of  these  years  is  greater 
than  the  average  for  the  decade  when  it  was  the  staple  product  of  the  colony. 

Numerous  trees  planted  at  government  Botanic  Stations  at  Aburi,  Kumasi, 
Tarkwa,  and  near  Cape  Coast  Castle,  form  nursery  centres,  and  seeds  and 
seedlings  of  Para  and  various  indigenous  rubber-producing  plants  are  distributed 
therefrom.  Travelling  instructors,  European  and  native,  educate  natives  to 
more  scientific  methods  of  tapping  and  preparing  rubber  for  market.  Simple 
literature  bearing  on  subject  in  English  and  the  vernacular  has  been  circulated.  A 
Commission  of  Inquiry  recently  inquired  into  details  of  industry,  so  as  to 
maintain  and  improve  sources  of  supply,  prevent  adulteration,  and  obtain  best 
prices. 


RUBBER  CULTIVATION   IN   VARIOUS  COUNTRIES        89 


Tin-  two  principal  souree-  .if  (  ;«»1J  Coast  ml.  ber  are  (1)  /•'»///>• 

AlVican  rubber   tree),   ami    (1*)  /.///////*//*///»•   nn-.t,-',,  //>•/>-,   both    in-.  to   Colony. 

(.'>)  The   tree    /•'/<•//.<    I',  */,//'/,  \\hirli    fimii>hes   ;i    nther   inferior   rubber,    abo 
in  (inlil  CoaM,  l.iit   is  not   IIM\\   exploit.-d  liy  native*  to   .m\   extent.       II.-.  .-nt  l\  .   I'.tr.i 
cultivation    lias    been    SQCCeesfui    in    Colony,    ami    may    |>rovr    important    as   future 
source  of  Gold  Coast  rubber. 

Gold   Coast    lump    rubbers    niostl\    produced    liy    /•'////'//  //*/»/    tln*ti<-,i,    but    from 
defecti\e    native   collection    and    preparation   are   usually    inferior.     \ati\- 
variably   add    lion  <  aoutchoiiciferous  latices  to  I1  \  i/'iatti-n  latex    before  coagulation  ; 
resultant   rubber  \er\    ivsinoilS.      Preparat  ion  of    larur<-  lump*  deti-riorat«-*  niblicr,  as 
it   retains    nmtlier  liijuor  and  allninien,  usually  fermenting  in  transit  ;   it   al»»   li»Mt<, 
lieromes   stiek\,and   smells  badly.       Hence  (  iold    Coasl    ruMiers   realist-   1«.\\    prii-i-s. 
When    tine    hard    Tara    is    Is.    per    11>.,    (inld    Coast    lumps  is    Is.    7d.  ;     M8 
Is.    :;,!.;    -Paste,"  5Jil.  ;    "N  Is.   s,|.      Put  F.   elastica  yields  cxrell.-nt 

ruliher  if  properly  prepared.  Natives  are  induced  to  prepare  biscuit  rubber,  and 
to  c-ease  adding  othi'r  latices.  Recently,  many  specially  prepared  samples  of 
Finit,  i  a,  I  'i  rubber  were  sent  to  Imperial  Institute  for  valuation,  to  show  advantages 
from  rationally  prepared  rubber. 


TABLE  XVII. — ANALYSES  OF  GOLD  COAST  RUBBER. 


A 

B 

C 

D 

E 

F 

<: 

H 

I 

J 

K 

L 

M 

N 

0 

Moi-ture  . 

3-6 

4-7 

:,•! 

3-7 

0-6 

0*6 

i-o 

0-4 

0-8 

0-39 

0-67 

Caoutchouc 

84'6 

86-9 

70-0 

72-7 

80-2 

79-2 

88-0 

89-0 

88-6 

91-3 

90'() 

51-6 

60-6 

95-53 

M-ft 

Kcsin 

5-8 

9-1 

9-5 

9'2 

8-0 

7-2 

8'6 

8-1 

8'9 

4-7 

0-2 

44'0 

35-6 

3-90 

3-25 

Proteids   . 

8'3 

3-4 

10-2 

10-2 

7'8 

9-6 

2'3 

1-9 

2-1 

0-9 

0-9 

3-5 

1-7 

.. 

lii-nlul,lr  mutter 

6-7 

3-2 

0-9 

0-3 

•l-\ 

2-3 

0-5 

1-3 

.. 

Ash   .... 

1-3 

0-6 

•• 

0-5 

n-4 

0-4 

•• 

•• 

•• 

-• 

0-18 

0-2 

A.  By  letting  Funtiimia  latex  coagulate  by  air  exposure,  London  value, 
3d.  per  Ib. — B.  Same  latex  coagulated  by  boiling,  London  value,  4s.  6d. ;  Para 
at  5s.  4d. — Cf,  D,  E,  F.  Same  latex  spontaneously  coagulated  after  adding  a 
little  formalin,  London  value,  4s.  9d. ;  Para  at  5s.  2d. — G,  H,  /.  Same  latex 
coagulated  by  hot  infusion  of  Bauhinia  reticulata, .  London  value  of  G  and  //, 
La  to  4s.  3d. ;  Para  at  4s.  7d.  Of  /,  2s.  8d.  to  2s.  lOd. ;  Para  at  3s.  aid. — J.  Crepi 
Ball  from  Landolphia  owariensis,  London  value,  4s.  3d.  to  4s.  6d. ;  Para  at6&  Id.— 
A".  IVmpeiii  rubber  from  L.  otvariensis,  London  value,  3s.  to  3s.  3d.;  Para  at 
3&  ")£d. — L,  M.  Ficus  Voc/eli  (Inferior).  Trials  as  to  techni.al  uses  value, 
being  conducted  for  Imperial  Institution. — ^Y,  0.  Hewn  A'/M  :///'» //>•/>•,  London 
value,  4s.  6d.  to  4s.  7d.  The  analysis  compares  favourably  with  Ceylon  and  Malay 
States  Para  biscuits,  and  show  that  the  Para  tree  will  furnish  excellent  rubber 
in  the  Gold  Coast. 


90 


INDIARUBBER 


APPENDIX   TO   CHAPTEE   III 
PARA  -RUBBER   CULTIVATION 

OFFICIAL  ESTIMATE  FOE  1000  ACRE  ESTATE;  250  ACRES  TO  BE  OPENED 

EACH  YEAR. 


EXPENDITURE, 


IST  YEAR. 
Premium        ..... 

Survey  fees 

Rent      .  '      . 

Clearing,  felling,  and  burning  250 

acres  ($15  per  acre)     . 
Lining,   holing,  and  planting  250 

acres  ($6  per  acre) 

Plants   

Koads  and  drains  ($6  per  acre) 
Bungalow       ..... 

Lines     ...... 

Medical— Hospital,  medicines,  etc. 
Labour] — Advances,      immigration 

fees,  etc.  ...'".. 
Superintendence  .... 
Tools  and  sundries 

Total     . 

2ND  YEAH. 

Rent 

Clearing,  felling,  and  burning  250 

acres  ...... 

Lining,  holing,  and   planting  250 

acres  ...... 

Plants 

Roads  and  drains  . 

Medical          .         .         .         . 

Labour  ...... 

Superintendence     .... 

Tools  and  sundries 
Weeding  250  acres 
Supplying  ..... 

Total     . 

SRD  YEAR. 

Rent 

Clearing,  felling,  and  burning  250 

acres  ...... 

Lining,  holing,  and   planting   250 

acres  .... 

Plants ', 

Lines      ...... 

Roads  and  drains  .... 

Medical.         ..... 

Labour  ..... 

Superintendence     .... 

Tools  and  sundries 
Weeding  500  acres 
Supplying 


3,000 
1,000 
1,000 

3,750 

1,500 
800 
1,500 
2,000 
1,500 
2,000 

1,500 

3,600 

.1,000 

24,150 

1,000 
3,750 

1,500 

800 

1,500 

1,000 

1,000 

4,000 

750 

2,500 

100 

17,900 


1,000 
3,750 

1,500 
800 
1,500 
1,500 
1,000 
1,000 
4,000 
1,000 
6,000 
100 


Total     .     23,150 


4TH  YEAR.  $ 

Rent 1,000 

Clearing,  felling,  and  burning  250 

acres 3,507 

Lining,   holing,  and  planting  250 

acres  ......  1,500 

Plants 800 

Roads  and  drains  ....  1,500 

Medical 1,000 

Labour 1,000 

Superintendence     ....  4,000 

Tools  and  sundries          .         .         .  1,000 
Weeding  750  acres          .         .         .12,000 

Supplying      .....  100 

Total    .  27,407 

STH  YEAR. 

Rent 1,000 

Roads  and  drains   ....  800 

Medical 1,000 

Labour 1,000 

Superintendence     ....  4,000 

Tools  and  sundries          .         .         .  1,000 

Weeding  1000  acres        .         .         .  15,000 

Total     .  23,800 


6TH  YEAR. 

Rent      .... 
Roads  and  drains  . 
Labour  .... 
Medical 

Superintendence  . 
Tools  and  sundries 
Weeding  1000  acres 


Total 


7'i'H  YEAH. 
Rent      . 

Roads  and  drains 
Medical. 
Labour . 
Superintendence 
Tools  and  sundries 
Weeding  1000  acres 


1,000 

800 

1,000 

1,000 

4,000 

1,000 

17,000 

25,800 


4,000 

800 

1,000 

1,000 

4,000 

1,000 

17,000 


Total     .     28,800 

8th    and    following  years    as   7th 
year 28,800 


With  the  exception  that  the  cost  of  weeding  gradually  decreases  till,  in  the  llth  or  12th 
year,  it  is  practically  nil. 


RUBBER   CULTIVATION   IN   VARIOUS   COUNTRIES        91 


I 'KOI  ITS. 


7TH    YI.AI:. 

250  ai-iv.x.  |-1  uited  150  trees  per 
lore,  at  1  II).  nil.U-i  pi-r  tree, 
sold  jit  ta,  |..-r  11).  .  .  .  48,214 

250  acres,  planted  150  trees  per 

acre,  at  H  Ib.  rubber  per  tree  .  72,321 

Total      .  120,535 

Less  cost  of  product  i«m,  shipping, 
etc.,  of  93,750  Ib.  at  Is.  6d. 
,,.11. 60,268 

Net  profit    .     60,267 

STH  YEAH. 
250  acres  at  1  Ib.  per  tree  and  3s. 

per  Ib 48,214 

250  acres  at  H  Ib.  per  tree  and  3s. 

perlb 72,321 

250  acres  at  2  Ib.  per  tree  and  3s. 

I..M-  Ib 96,428 

Total       .  216,963 

Less  cost  of  production,  etc., 
253,125  Ib.  at  Is.  6d.  per  Ib.  .  108,482 

Net  profit      .  108,481 


9Tii   Yi  IB, 
250  acres  at  1  Ib.  p«-r  tr« •••  .u.-i  .;  . 

p.-r  I!.. 
2f>0  iirivs  .it   1  ',  11..   pi-r  i  Mt    ni-1    .;•-. 


Ib. 


500  acres  at  2  Ib.  per  tree  and  3«. 

peril..         .  ...  192,856 

Total      . 

Cost  of  production,  etc.,  243,750  Ib. 
at  Is.  6d.  per  Ib.         .        .         .   156,696 

Netpn.iit       .   156,695 

IOTII  YEAR. 
250  acres  at  1^  Ib.  per  tree  and  3». 

perlb 7 

750  acres  at  2  Ib.  per  tree  and  3s. 

perlb 289,280 

Total       .  361,601 
Less     cost     of    production,     etc., 
262,500  Ib.  at  Is.  6d.  per  Ib.       .  180,800 

Net  profit      .  180,801 

HTH  YEAR. 
1,000  acres  at  2  Ib.  per  tree  and  3s. 

perlb 385,710 

Cost  of  production,  etc.,  of  300,000 

Ib.  at  Is.  6d.  per  Ib.   .         .        .  192,857 

Net  profit      .  192,853 


And  so  on  each  year,  annual  profit  .$192,853,  with  a  probability  of  still  increased  yield. 
ABSTRACT  OF  PROFIT  AND  Loss. 


Expendi- 
ture. 

Profit  on 
rubber. 

Net  profit 
on  estate. 

Expendi- 
ture. 

Profit  on 
rubber. 

Net  profit 
on  estate. 

* 

1st  year        24,150 
2nd          ;     17,900 
3rd          1     23,150 
4th                27,650 
5th                23,800 
6th                25,800 

9 

... 

1! 

7th  year 
8th 
9th 
10th 
llth 
12th 

$ 
28,800 
28,800 
28,800 
28,800 
28,800 
28,800 

$ 

60,267 
108,481 
156,695 
180,801 
192,853 
192,853 

$ 

31,467 
79,681 

127,895 

i;.  2,000 

164,053 
164,053 

Expenditure  with  interest  at  5  per  cent,  up  to  end  of  6th  year,  $168,670  (120,000). 
NET  PROFIT  ON  ESTATE  AFTER  DEDUCTING  5  PER  CENT.  INTEREST  ON  CAPITAL. 


Net  profit. 

*                                 i 

Net  profit. 

$ 

7th  year 
8th     „ 
9th     „           .         . 

22,967  or  13  per  cent. 
71,181  „  42        „ 
119,395  „  70 

10th  year      . 
llth     ,, 

143,500  or  84  per  t-.-nt. 
156,553  ,,92 

And  so  in  future  years  with  a  probability  of  increased  yields. 


Capital  expended 


Profit  . 


ABSTRACT  OF  PROFIT  AND  EXPENDITURE. 

S  £  s.  d. 

168,670    (19,678  3  4) 

22,967     (  2,679  9  8) 


f     Z*,VO/  . 

71,181  (  8,304    9  0) 

.      '  119,395  (13,929     8  4) 

143,500  (16,741   13  4) 

156,355  (18,211     8  4) 


CHAPTEE    IV 
CLASSIFICATION  OF  THE  COMMERCIAL  SPECIES  OF  RAW  RUBBER 

Chief  classes.  —  The  different  species  of  raw  rubber  which  come  on  the  inter- 
national market  may  be  divided,  according  to  their  geographical  origin,  into  four 
chief  classes  :  — 


3.  Asiatic  rubbers. 

4.  Oceanic  rubbers. 

Origin  of  different  designations.  —  The  trade  has  not  always  given  to  each  of 
these  different  varieties  a  uniform  designation.  One  sort  is  sometimes  known  by 
the  name  of  the  province  which  more  especially  produces  it,  although  the  same 
variety  is  likewise  met  with  in  other  countries,  and  to  an  equal  extent  ;  sometimes 
by  the  port  of  shipment,  or  of  the  central  market  town  of  the  substance.  Even  the 
shape  is  often  put  under  requisition  to  design  a  special  brand. 

Certain  brands  disappear  to  reappear  in  a  new  and  better  form  under  a  new 
name.  —  Commercial  denominations  are  very  variable,  and  some  sort  well  known  to 
merchants  of  twenty  years  ago  has  disappeared,  to  give  place  to  another,  although 
the  product  comes  from  the  same  plants  and  the  same  countries  ;  the  mode  of  pre- 
paration has  alone  changed  and  necessitated  this  alteration.  A  rubber,  of  reputed 
inferior  quality,  reappears  under  a  new  brand,  which  raises  the  price.  But  the  label 
is  not  all.  In  changing  the  name  the  rubber  has  been  modified,  and,  above  all, 
improved. 

The  study  of  each  commercial  sort  impracticable.  —  We  shall  not  examine  each 
commercial  sort  individually  ;  they  are  subject  to  such  variations  that  the  data  of 
to-day  might  not  be  correct  to-morrow.  Incessant  progress  in  preparing  the  raw 
material,  exhaustion  of  one  rubber  tree  and  its  replacement  by  another,  render  such 
work  uncertain  and  of  doubtful  value. 

Description  of  the  Synoptical  Tables.  —  The  list  of  the  different  commercial 
varieties  at  present  on  the  market  has  been  condensed  into  a  synthetical  Table,  and 
opposite  each  variety  the  geographical  origin  of  the  species,  its  botanical  origin,  the 
method  of  coagulation  adopted,  which  is  indicated  by  the  abbreviated  notation 
adopted  in  the  chapter  preceding  the  Table  of  the  different  methods  of  coagulation. 
The  usual  port  of  shipment,  wrhen  known,  is  also  given,  the  country  or  the  market 
which  more  particularly  imports  it,  the  tangible  form  under  which  the  substance 
comes  to  market,  its  outside  surface  appearance,  the  texture  of  its  section,  the 
peculiar  smell  often  given  off  by  each  kind,  the  frequent  adulterations  to  which 
they  are  subject,  the  waste  in  their  industrial  working,  the  estimation  of  its  com- 
mercial value.  Finally,  in  the  remarks  column  there  is  mentioned,  if  need  be,  any 
important  peculiarity  for  which  a  place  could  not  be  found  in  the  other  columns. 

No  pretence  is  made  of  having  thereby  accomplished  a  work  of  rigorous  pre- 
cision and  exact  valuations.  Such  results  are  only  possible  with  products  manu- 


CLASSIFICATION   OF   COMMERCIAL   RUBBKRS  93 

faetured  in  ;i  regular,  methodical,  and  almost  mathematical  manner. },  In  the  present 
instance  we  have  to  deal  with  a  substance  which  is  tin-  product  ,,f  tin-  i-o|.tted 
efforts  of  individual  workers,  <>ne  of  ulnun  is  more  indolent,  tin-  other  inon-  a<-ti\e  : 
one  more  honest,  the  other  more  cuniiin^  and  less  scni|.ul..u- ;  tin-  «.m-  follows  tin- 
old  routine,  tin-  other  mmv  ot  an  innovator,  and  more  esjiut-ially  an  observer.  The 
I't-sult  of  all  this  is  an  intinitc  \ari«-ty  in  tin-  |.roduction  of  cadi  >oit,  \shich  rnnlri^ 
tliis  classification  extremely  ditlicult.  However  imperfect  it  may  apj»ear  to  IH-,  it 
enables  one  to  encompass  with  a  single  glance  of  the  eye  the  generality  of  the 
indiarulilx-r  products,  with  tin-  csx.-iitial  characters  of  each  variety,  and  to  give  an 
:  ciioii-h  idea  «,f  the  pivsriit  jtrndiiction. 


[TABLE. 


INDIARUBBER 


SYNOPTICAL  TABLE  OF  THE  DIFFERENT  VARIETIES 

i 

I.  AMERICAN  RUBBERS— 


1 

Commercial 
Denomination. 

Geographi- 
cal Origin. 

Botanical 
Origin. 

Method  of 

Coagula- 
tion. 

Port  of 
Shipment. 

Commercial 
Market. 

Packages. 

Usual  Commercial 
Size  and  Shape. 

PARA. 

Amazonia 

Hevea 

la  I. 

Para 

Liverpool, 

Cases     of      Formerly      came      to 

(1st  fin.  Sininga 

(Brazil). 

(various 

pp.Wetseq. 

(Belem), 

London,     i  130   to    140  market  in  the  shape  of 

fina,  the  native 

Similar 

species)  : 

Manaos.          Havre.        kilos.    (286    little    figures,    bottles. 

Borracha,    up- 
river  hard  cure  ; 

rubber      is 
obtained 

H.  Brazili- 
ensis, 

to  308  lb.).     pears,  shoes. 
Now    as    cakes    and 

and   Para  Fine 

from  Peru, 

lutea, 

biscuits. 

Islands,  soft 

Bolivia,  and 

bentham- 

The     Lower    Amazon 

cure). 

Venezuela. 

rana. 

cakes   smaller,    3   to   5 

panaflora. 
Micrdndra. 

kilos.    (6|  to  11  lb.). 
The    Upper    Amazon 

cakes  larger,   10  to   15 

kilos.  (22  to  33  lb.). 

PARA 

id. 

id. 

Mixture  of 

id. 

id. 

id.                              id. 

(£  fin.  Entrefin 

1  a  I.  and 

Grossa). 

1  /3  III. 

pp.  45  et  seq. 

PARA  SERNAMBY 
(Negroheads), 
Cabeca  de  Negro. 

id. 

id. 

id. 

id. 

id. 

Cases     or 
barrels      of 
200      kilos. 

Sometimes  in  the  shape 
of  rather  big  blocks,  but 
more  often  in  irregular 

(say  4  cwt.). 

shaped  lumps  of  about 

the  size  of  the  fist,  and 

agglutinated    by    tight 

packing. 

VIRGIN  SHEETS 
(White  Para). 

Province 
of  Matto 
Grosso 
(Brazil). 

Hevea. 

3e. 

pp.  49  et  seq. 

Manaos. 
That  from 
north 
shipped 
from  Para. 

Cakes    in    the    shape 
of  parallelopipedons  of  i 
various         dimensions. 
Large-sized  cakes  with 
sharp  regular  edges  are 
generally  0'60  metre  in 

length  by  0'30  metre  in 

width  by  0'15  metre  in 

thickness  (24x12x6  in.). 

The   small    cakes   are 

about  half  this  size. 

MOLLENDO. 

Bolivia. 

id. 

Mollendo. 

CEARA  SCRAPS. 

Province 
of  Ceara 
(Brazil). 

Manihot 

Glazioirli 
(Manisoba 
or  Leitera). 

1  ft  III. 
pp.  46  and 
54  et  seq. 

Ceara. 

id. 

The  milk  coagulates  as 
tears  on  the  trees. 
Small    strips    or   net- 
works of  tears  agglome- 

rated into  balls,  some- 

times   of    considerable 

size,  and  which,   when 

packed  fresh,  eventually 

amalgamate  together  to 
form  blocks  weighing  as 

much  as  150  kilos,  (say 

3  cwt.). 

CLASSIFICATION   OF   COMMERCIAL   RUBBERS 


OF  COMMERCIAL  CRUDE  INDIABUBBKR, 
(1.)  SOUTH  AMERICA. 


Skin  or 

Coat. 

•tattoo. 

Smell. 

Adulteration. 

Industrial 
Use. 

Observations. 

Dark  hro\\  n 

The  colour  of  the 

•llghtlj 

Little    or    m 

10  to  16%. 

Sensitive  and 

' 
cakes    of    Para 

inclining    to 

secti.m  in  the  direc- 

smoky.f  rom  extraneous 

\1'2  to  18, 

elastic  par  ex-   rubb.  r  often  bear   the 

black.          lion  <•[  the  thickness 

the  method 

matter. 

Weber.] 

Ki-.ii,    h-  ! 

from  the  outside  t. 

of  preparing 

Humidit\  \ari 

.1   the  priHlu.-mg  factories 

a  depth  of  1  centi 
metre,  say  i  ot  an 

the  rubber. 

able,  according 
to  date  of  col- 

rubber,   ;•:;      ;  (•  all.-d  the  brand,  as  in 
ash,  0-5%.          the  CAM  d  tedkri 

inch,  is  changed  bj 

lect  ion.     Some- 

Collect, •<!   during    the 

insensible       grada- 

times    adulter- 

• uson—  endof  .lune 

tions  to  a   sl'iuhtU 

ated   by  an   ad- 

to middle  of  <»,(,, 

amber  tinted  while. 

mixture  ..t    tin 

During      the      rainy 

the  general  tone  of 

latex  of  M  'in" 

season  the  latex  is  too 

,the  rest  of  the  sec- 

M./o- fill  til.  Mill-- 

poor  in  rubber.     More- 

tion    perpendicular 

filii'lili-iilnl. 

over,  the  collectors  <••  •  \  •  Id 

to  the  first. 

not  work  on  account  of 

Apparent        folia1 

bad  weather. 

or  pellicles  tell  the 

Borracha  arrives  abun- 

origin of  this  rubber. 

dantly  on  the  Brazilian 

New      cakes      sub- 

markets from  the   end 

divide     under     the 

of  July  to  the  end   .,f 

thumb  into  as  many 

December. 

pellicles    as     there 

Parafin  is  the  standard 

have     been     super- 
imposed layers. 

' 

against    which    quality 
all  rubbers  are  valued. 

u 

Kxhibits         quite 

Odour  less 

Few     foreign 

15  to  20  %. 

Less  sensitive 

i  Dirty  milky-white  i* 

different  character- 

jronounced 

bodies.       More 

Resin,    2'5    % 

always  a  sign  of  mois- 

istics from  Para  Jin. 
The  method  of  co- 

ban in  the 
>  r  e  c  e  ri- 

moisture   than 
the  above. 

ash,  0-6  %. 

ture,  due  either  to  the 
latex  itself  or  the  serum 

agulation     explains 
this  difference.  The 

ng  variety. 
Smell     of 

being  imprisoned  in  the 
rubber.     Horny    trans- 

portions   «  evapor- 

n e  t  h  y  1  a- 

parency  is,  on  the 

ated  without  being 
smoked    are    of    a 

nine. 

trary,  a  sign    of   good 
quality.    This  variety  is 

dirty   white,  whilst 

only  met  with  on  the 

those      that     have 

market  in   small  quan- 

been    smoked     are 

tity. 

amb.-r  brown.*  (See 

Observations.) 

Blacker 
and 

Yellowish     white, 

marbled  with  black 

id. 
S  o  m  e- 

Often     mixed 
with     sand. 

20  to  40  %. 

Is      awanting 
n  sensitiveness. 

Negrohead    is    made 

up  of  rounded  masses  of 

roogber 

stria;.      Cuts      like 

>imes  smells 

Moisture     con- 

un.ured   rubber,    with 

than       fine 

fine  cheese. 

nouldy. 

siderable.    Mix- 

sometimes       flattened 

Para. 

ture  of  "  dead  " 

discs,     the     result     of 

rubber  without 

coagulation  in  the  clay 

nerve    or   elas- 

cups. 

ticity. 

Brifhl 

Straw  yellow  with 

15  to  30  y,. 

Less  sensitive 

Collected  from  August 

brown. 

ureenish     marbling, 
especially    on     the 

;  h  a  n  brown   to  February.    Like  Para, 
Para,  yet  good   is  di\ided  into  fine,  4 

eilires. 

and  strong. 

fine,  and  Semambv. 
Another  sort  of  Matto 

0  rosso  rubber  from  the 

southern     part    of    the 

State    is   probably   got 

from       flancornia 

./„    ,-,:      ,,( 

Nearly    equal 

•' 

o  I'.u-a. 

Me  ire      Hi- 
less        dee]) 
amber. 

1  '.right  amber,  al- 
most       traiislneid  ; 
when     drawn     out, 
becomes  white  and 
opaque. 

Sui  generis     Always  mixed 
very     pro-  1  with   vegetable 
n  on  need  ;  de  b  r  i  s,    and 
becomes!  often  with  sand, 
nauseous  in|;  as  much  as  15  % 
moist  heat,    of  moisture. 

2n  to  26%. 

ities    char- 
ged with 
earth    as 

hi-ha- 

Rather  sensitive      The  serum    from    the 
and  esteemed,      coagulation  of  the  Ceara 
A  drv  rubber,   rubber  is  to  a  greater  or 
very  elastic  and  lessextent  eliminated  by 
ree  from  sticki-   mechanical  pressure, 
ness.     Resin.       The   .l/.,,,//i..f    is    the 
•4  %  ;  ash,^-8    .  indiarublvr  tree  of  arid 

dry  ground. 

96 


INDIARUBBER 

SYNOPTICAL  TABLE  OF  THE  DIFFERENT  VARIETIES 

1.  AMERICAN  RUBBERS— 


Commercial 
Denomination. 

Geographi- 
cal Origin. 

Botanical 
Origin. 

Method  of  ,     Port  Qf 

Commercial     p_  „!.._„ 
Market.     > 

Usual  Commercial 
Size  and  Shape. 

PERNAMBL-CO 

Province 

Hancornia.          3  e.          Rio  Janeiro,  i  Liverpool. 

As    biscuits.      Some- 

(Mangabeira). 

of  Pernam- 
buco 
(Brazil), 

pp.  49  et  seq. 

Bahia  ; 
that  from 
Matto 

times   in    the    form  of 
rectangular     slabs     of 
different     sizes,    some- 

Bahia, 

Grosso 

times    1'50    metre      in 

Southern 
Matto 

by  River 
Parana 

length,  0'6  to  0'7  metre 
in  width,  and  0'08  to  O'l 

Grosso, 

through 

metre  in  thickness  (sav 

Uruguay. 

Paraguay. 

60x24  to  27x3  to  4  in.). 

MARANHA.M. 

Province  of 

Maranham 

pp.  ^Qetseq. 

(Brazil). 

BAHIA. 

Province 
of  Bahia 

Hancornia. 

1/3  1. 
pp.  47  and 

United 
States. 

.. 

Irregular    masses    or 
bulky     sheets,      which 

(Brazil). 

53. 

sometimes     weigh      as 

much  as  15  to  20  kilos. 

(33  to  44  lb.). 

CARTHAGENA 

Colombia. 

Heveas. 

1/3  III. 

Carthagena, 

United 

Bulky    masses  which 

(Essequibo). 

pp.  45  et  seq.  \   Sa  vanilla.         States, 

may   weigh    as     much 

46  et  si-q. 

France. 

as  80    kilos.   (176    lb.), 

proceeding  from  sheets 
of  variable  dimensions 

placed  in  juxtaposition, 
or    attenuated    tangles 

re-folded  on  themselves 

like  Nicaragua  Scraps. 

CIUDAD  BOLIVAR 
(Colombia- 

Venezuela. 

Heveas, 
Callotropis 

la  I. 

pp.  40  et  seq. 

Bolivar. 
Sometimes 

Hamburg, 
United 

Same  as  Para. 

Virgin). 

procera, 
Hancornia 

Sometimes       Manaos. 

States. 

speciosa, 

'3e. 

Sapium 

(Lucien     ! 

(biglandu-       Morisse). 

losum)      \pp.5letseq. 

(Lechere). 

CAYENNE. 

French 

Heveas. 

la  I. 

Cayenne. 

France. 

id. 

Guiana. 

pp.  40  et  seq. 

PERU  and  PERU 
1   SBRNAMBILLO. 

Peru. 

Hevea, 
Cineraria 

1/31. 
Si. 

Iquitos. 

Bulky  blocks,  or  like 
Para. 

la  folia, 
Hancornia 

and     punc- 

Sernambillo,  like  Ser- 
namby  Para. 

speciosa. 

tur  es    to 

evacuate 

the  serum. 

pp.   45,   49. 

and    51    et 

seq. 

CLASSIFICATION   OF  COMMERCIAL  RUBBERS 

OF  COMMERCIAL  CRUDE  INDIARUBBER. 

(1.)  Sorrn   AMI  1:1-  \     ••••,,Hm»<l. 


97 


.skin  OF 

•n.l.  . 

Sm.-ll. 

Adulteration. 

Los*  in 
Industrial 

Valuation 

Ori  ii  u  - 

\\  Ilitcro-c.    There 

Often      also 

40  to  60  %. 

l.ittl,-    eUuti- 

HUU*  of  Mina^GerMC 

n.l.       uith 
saline  i  ttlor- 

an-  iuinier..ii-  p...-k 
ct-     -liown     in    the 

coagulated  \\ith 
-alt  in  excess. 

[»l  to  40, 
Weber.  | 

city,  fluhli.x.    In 

certain         CMC* 

and  Quyai  have  largest 

production,  when.-,-  ,,n.- 

escences. 

-ection,   tilled    with 

-eniiii     containing 

onl\  used  on  ac- 
count of  it  -  flue 

half  i*  shipped  to  Rkxto 

.i.in.  n..  and    the  other 

alum,     \\hidi       h:i- 

colour.     A  wet 

half  to  liahiu.      Export 

hcen    used    as    the 

rubber. 

<tllt\,    1  t   |MT 

chemical    coa-nlat 

-iltly      affected 

Becomes  brittle,  hard. 

ing  agent. 

l.y    method     ,,f 
coagulation. 

and    friable    with    age. 
ittrtbuted 

lie-in.    f,-9    %  ; 
ash,  3-1  %. 

to  the  presence  of  alum. 
This  quality  has*  ten- 

(len<\  to  disappear,  and 

>>e  replaced  by  Mann- 

ham. 

Mm.  other      White  rose  which, 
>kin.     more    in  theair,  assumesa 

25  to  80  %. 

30  to  35  '%. 

More  sensitive 
and  elastic.  And 

The  presence  of  sugar 
has  been  determined  in 

hr  ill  i  a  n  t.  deep    \\ine-lce   tint. 

thus      so      far 

mother  liquor  collected 

no       cttlor-    Few  or  no  pockets. 

superior     to 

from  this  rubber. 

essence. 

previous  brand. 

Resin,    5'8    %; 

ash,  2-4  %. 

White  rose.  Pockets 

Wood,    vege- 

50%. • 

Quality    infe- 

. . 

coat. 

tilled    with    serum, 

table      matter, 

[18,  Weber.] 

rior.    Not  much 

and  very  often  with 
non-coagulated 
latex. 

sand,  earth. 
Very  humid. 

esteemed.     [An 
excellent  variety 
almost  as  strong 
as  Para.WeberJ 

Resin,    97  %  ; 

ash,  0-8  %. 

p  brown 

inclining 
to      black. 
Translucid. 

The  cut  rubber  is 
amber-coloured  like 
the  bright  parts  of 
Para  Seruambv  . 

Odour  of 
methy  la- 
mine  and  of 
mould. 

But  little  vege- 
table debris  or 
sand. 

20%. 
25  to  50  %. 

Good  elasticity, 
rather  sensitive, 
somewhat     es- 
teemed.  Resin, 
6-7      %  ;      ash, 

There  is  another  Car- 
thagena  rubber  of  older 
date,  but  as  it  has  all  the 
properties  of  Guayaquil 
rubber   we    will   amal- 

2'8%. 

gamate  it  with  the  latter. 

Like  Para. 

Like  Para. 

Slightly 
smoky. 

Sophisticated 
with   the   juice 
of  the  Pindare 
and    the   Mas- 

15  to  20  %, 
according 
to  the  qual- 
ity. 

Rather  similar 
to  Para,  to  the 
price  of  which 
it  is  alone  inferi- 

Collection commence* 
in   November,    ends  in 
April. 
Tapping  is  sometimes 

*<ti-iinda. 

or,  under  which 

replaced   by   felling  on 

name  it  is  often 

Orinoco     ('baneful     re- 

sold.     Yellow, 

sults). 

clean,  does  not       Mixing  of  other  juii-ea 
require    to    be  of  inferior  quality  always 

pressed.    Supe- 

injurious. 

rior    to    coast 

Trees    ruthlessly    de- 

rubber. 

stroy  ed  ;     little    rubber 

now  exported. 

;,i. 

id. 

Some  what  pure. 

15  to  20  %. 

Like    Para. 

Resin,    2'2   %; 

Development      much 

MglMlM,  M  -  "ph:..    !- 

ash,  0-4  %. 

Coudreau. 

Intense 

Yellow,         which 

Sand  consider- 

25 to  80  %. 

Very   elastic; 

Collection  commences 

black.   Sur-  turns     slaty     grey 
.ranu-    with      a»e.        \    r\ 
lar.                  porous. 

able.     Water  in 
quantity. 

[20  to  30, 
Weber.] 

quality     e  s- 
teemed,  if   not 
its  colour.    The 
Sernambillo 

in  A  u  trust. 
Felling  after  tapping. 
This  rubber,  when  b<.ilr< 
in  water,  is  decolorised. 

(waste)  is  more 

and       becomes 

esteemed    than 

white. 

that  of  Para  ;  it 

The   water,  which  is 

is   less   porous, 

tinted,  is  an  energetic 

and  it  contains 

purgative. 

less      water. 

Resin,    3'G    %; 

ash,  1-4  %. 

98 


INDIARUBBER 


SYNOPTICAL  TABLE  OF  THE  DIFFERENT  VARIETIES 

1.  AMERICAN  RUBBERS — 


Commercial 
Denomination. 


GUAYAQUIL 
(Sheet). 


GUAYAQUIL  and 

CARTHAGENA 

(Strip). 


MEXICO. 


Geographi- 
cal Origin. 


Botanical 
Origin. 


Ecuador 

and 
Colombia. 


GUATEMALA. 


id. 


I  Vera  Cruz, 

Taumapilas 

Tabasco, 

Guerro, 

Baraca, 

Repic  Chia- 


Guatemala. 


NICARAGUA 

(Sheets), 

Savanilla, 

Central 

America, 

Costa  Rica, 

Puerto  Cabello. 


NICARAGUA 
(Scraps). 


West  Indies. 


Castilloas. 


id. 


Caslilloa. 


Method  of 
Coagula- 
tion. 


3  i. 

3e. 

pp.  49  and 
51  et  seq. 


Castilloa. 


id. 


I  all.,  and 

unknown 

process. 

p.  45. 


3u  with 

ipomea 

bona  nox. 

p.  51. 


Port  of 
Shipment. 


Guayaquil. 


Commercial 
Market. 


Guayaquil 
and 

Carthagena 


North 
America, 

little  in 
Europe. 


America, 
little  in 
Europe. 


Packages. 


Nicaragua. 


Usual  Commercial 
Size  and  Shape. 


Sheets  of  considerable 
size,  sometimes  as  large 
as  1  metre  long,  0'5  to 
0'7  metre  wide,  and 
0-01  to  0-05  metre  thick 
(say  39ixl9|  to  27Ax| 
to  2  in.). 


uastiuoa.   |        6  i. 
p.  51. 

England, 
France. 

Sheets,    thickness    of 
5  mms.  to  1£  cms.  (|  to  f 

of  an  in.).  Margins  often 

thicker     than     centre. 

These  sheets  are  united 

by   meshes    into    balls, 

which  may  weigh  more 
than   100   kilos,   (say    2 

(cwt.). 

Castilloa. 

'. 

Grey  town. 

South 

Sometimes  in  the  form 

p.  48. 

America. 

of  bladders,  which  may 

be  as  thick  as  the  arm. 

Sometimes  in  the  form 

of  balls,  the  smallest  of 

which  are  as  big  as  the 

head. 

Sometimes    in    bulkv 
blocks  of  60  to  80  cubic 

centimetres. 

They  consist  always  of 
more  or  less  attenuated 

tangles      folded      back 

upon  and  rolled  round 

j  each  other,  being  sheet 

cuttings  and  spontane- 
ously dried  tears. 

Network  of  O'lO  metre 
(say  4  in.)  in  dia- 
meter, rarely  more. 
Length  varies' 3  metres 
(say  10  ft.)  (?). 

Sheets  of  1  to  4  cms. 
(say  |  to  1£  in.  thick). 

Length  and  width  0'5 
to  0-6  metre  (say  20  to 
24  in.).  Sometimes  in 
balls  or  marbles  5  to  6 
cms.  in  diameter  (sav  2 
to  2|  in.). 


Sheets. 


CLASSIFICATION   OF   COMMERCIAL   RUBBERS 

OF  COMMERCIAL  CRUDE  INDIARUBBER. 
(2.)  OENTKAL  AMERICA. 


Skin  ,>r 
C.al. 

Section. 

Sm.-ll. 

Adulteration. 

Lottin 
Industrial 
Uee. 

Valuation. 

Observations. 

f- 

I  .a  rue         \\hitisl             ..                Many    earthy 
flakes  and  lumps  in                             impurit 

20  to  86%. 
|:«ito40, 

Somewhat 
sensitive      and 

The  produce  of  r 
loa  trees  in  the  Central 

best  >ort>      nneut-                          \\.itn-    in    ooa-       Weber.]     (elastic.      Little 

American  States  b  vari- 

tiiitf the  poor  quali-                              -iilerable   quali- 
ties there  is  found                          tiiie-. 
a    greenish    black, 

sought  after  on 
account  of    it- 
impurities   and 

ously  known  as   Nicar- 
agua, West  India,  Hon- 
duras, Mate,  Bo* 

\er\       moist       suh- 

variable  quality. 

mala,     Panama,      and 

-laiic-i',    with    inan\ 

Resin,    5-7    %; 

Peruvian       "Can 

\esieles  of  \\aler. 

ash,  1-2%.     ' 

according  to  the  locality 
from  which  it  U  obtained. 

The  rubber  comes  fn 

blo<-kH,  sheets,  or  scraps  ; 

is  uniformly  black,   not 

unfrequently    tarry   or 

sticky  on  the  outside. 

and  usually  obtains  price* 
about  two-thirds  of  that 

of  the  best  Para. 

Carthagena  Strip 

.. 

id. 

id. 

M 

is   a   black     tough 

rubber. 

Brown  or 

Greenish  matter  ; 

Sand,     earth, 

12  to  15  %. 

Very  sensitive. 

The  arboriculture   ol 

blackish, 
right    am- 
>er  brown. 

very  beautiful 
horny  section. 

leaves,      some- 
times fragments 
of  wood. 

[80,  Weber.] 

Resin,  5'3  %  ; 
ash,  1-1  %. 

Caxtilloa  in  being  vigor- 
ously and   scientifically 
prosecuted  on  the  Isth- 

mus   of   Techuantepec, 

in  the  district  of  Soco- 

usco.the  State  of  Chiapas 
and  the  State   of  Vera 

Cruz. 

Black. 

When  cut,  allows 
a  viscous,  blackish, 

Very  char- 
a  c  t  e  r  istic 

Very  aqueous. 

30%. 
[25  to  35, 

Very  sensitive 
but  little  appre- 

Fair average  quality 
rubber. 

very  bitter  charac- 

special 

Weber.] 

ciated    on    ac- 

teristic substance  to 

odour. 

count     of    the 

escape.  This  liquid, 

resin   which   it 

on  drying,  produces 

contains,      and 

a    coat    of    vurni»h 

from    which    it 

which  easily  scales 

cannot  be  freed 

off. 

without    iniur- 

ing  the  rubber. 

x 

Resin,     7'2    %; 

ash,  3-0  %. 

Hlarkish. 

On  cutting,  a  black- 
ish or  crreenish  vel- 

Special         Small  quantity 
character-  !  of  water.    Very 

10  to  15  %. 

The  sort  most 
esteemed        in 

The  thinner  the  sheets 
the  more  they  are  em- 

low  suDstance.  and 

istic  odour,    rarely        sand*. 

Central    Amer- 

teemed in  trade.     The 

a  little  brown  liquid, 
with  a  bitter  taste, 

wood. 

ica.     Sensitive, 
ela-ti.-.      Rivals 

government  of  Nicaragua 
has    issued    a    decree 

but  not  foetid. 
The   section,    on 

Para.       Resin, 
2-8    %;     ash, 

giving    a    premium    of 
10  cents  for  every  rubber 

<lr\in^,        becomes 

I'l  %• 

tree  planted  where  the 

brilliant  and  black. 

number   does    not    go 

below   250   planted  by- 

one  person.    The  trees 

must  be  planted  16  feet 

apart. 

/  . 

Generally  blackish 

Little     mois-    lo  to  i:.    . 

Highly  esteemed 

M 

and  brilliant,  some- 

lure.  Some  bits                             after  1'ani  fin. 

tiine»  NrllouMi.  but                              of  wood  (su  her). 

blackening    rapidh                            s  ome  time- 

wit  h  aire. 

adulterated 

with  sand. 

100 


INDIARUBBER 


SYNOPTICAL  TABLE  OF  THE  DIFFERENT  VARIETIES 

I.  AMERICAN  RUBBERS— 


Commercial       Ge  "graph! 
Denomination,     cal  Origin. 

Botanical 
Origin. 

Method  of        p    fc    f 
Copula-       ggj*^ 

Commercial    „.„,...„              Usual  Commercial 
Market.                                      Size  and  Shape. 

GUAYULE.            Mexico. 

Par- 

Crushing   of  New  York. 

North                 .  .                Black  liquorice,  tarn 

thenium. 

entire 
shrub  and 

America,                           tacky  masses. 
Europe.     ; 

subsequent 

extraction, 

possibly  bv 

solvents. 

SENEGAL, 
SOUDAN. 

South 
Senegambia, 
Senegalais, 
Segou, 
Foutah- 

Vahea, 
Landolphia, 
Callotropis 
procera, 
Ficus 

4. 
p.  53. 

Kaves, 
Bakel, 
White  Cape. 

Marseilles 

Sometimes  in  the  form 
of  more  or  less  bulky 
bomb-shaped  masses,  or 
in  flat  sheets  of  from  1 
to  3  cms.  thick  (f  of  an 

Djallou, 

khal. 

in.  to  1}  in.). 

Samory, 

Sometimes  as  pellets 

Bammako. 

obtained  by  rolling 
upon  itself  the  rubber 

got  by  spontaneous 
coagulation  and  dra\\7i 

:\ 

out  into  filaments  like 

Gambia  and  Mozam- 

bique. 

CASAMANCA 
(Boulam). 

High 
plateau  of 

Landolphia. 

1/3  II. 
p.  46. 

Boulam. 

The  same  as  Senegal 
rubber. 

the  right 
bank  of  the 

Casamanca. 

CASAMANCA 

(Gambia). 

Left  bank 
of  the 

Vahea. 

4. 
p.  53. 

Zighinchor. 

.. 

Is  met  with  in  the 
form  of  pellets  of  from 

i 

Casamnnca. 

Sometimes 
Lemon 

300  to  800  grammes  (say 
10£  to  28  oz.),  sometimes 
even  2  kilos,  (say  4|  lo.). 

juice. 

SIERRA  LEONE 
(Southern 
Rivers). 

Sierra 
Leone  and 
Southern 
Rivers. 

Ficus, 
Vahea, 
Landolphia, 
Diander, 

i  pa. 

p.  46. 

Boke,  Boffa, 
Kouakry, 
Benty, 
Freetown. 

Liverpool, 
London, 
Marseilles. 

.. 

Like  Soudan,  Senegal 
rubber  and  Casamanca 
(Boulmi). 
Balls  and  sheets. 

j 

Fituma. 

i 

1 

CLASSIFICATION   OF  COMMERCIAL   RUBBERS 


101 


OF  COMMERCIAL  CRUDK  ENDUBUBBKE, 

(2.)  CKXTUAL  AMERICA-  continued. 


Skin  or 

Cnut. 

Section. 

feMJB, 

Adulteration. 

LoMbi 

Industrial 
Use. 

Valuation. 

ONunnHm, 

Ito  black  colour  and 

iu  tacky  ol«o  rerinoos 

nature  are  agalnct   it. 
It  can  only  find  a  ate 
in  admixture  a*  u  |-~,r 

natural    subtiUtut- 

ratttr. 

RUBBERS. 

Reddiati 

brown. 

White  -slightly 
rose. 

Bits  of  wood. 

So  m  e  t  i  in  e  s 

38%. 
[25  to  50.] 

Inferior  qual- 
ity.    Colle<-ti«.n 

Tensile  strength  high, 
demand  good. 

earth.        Much 

[30  to  50, 

process  too 

moisture. 

Weber.] 

rudimentary 

Full  of   sand 

Resin,    6'1    %; 

and  dirty  bark. 

ash,  4-0%. 

Deep  brown. 

Greyish,  inclining 
to    creamy    white, 
sometimes  to  rose. 

Bad. 

Much  earth  and 
sand. 

40%. 
[60%.] 

But     slightly 
appreciated. 

In  Mar.-h  the  busiest 
time     of     arrival     and 
barter. 

Abundant  pockets 

of  serum. 

White    at 

Concentric  circles 

Butlittledebris. 

20  to  25%  (11 

Rather  nervous 

This     rubber,     which 

ti  I-M  ,  after-  varying      from 

Rather  humid. 

30  to  40%  (2). 

quality.    Kesin. 

would    be    an    e\r«-ll<  -lit 

war-  Is    red-  brownish      red      to 

[15  to  30, 

•f         ;      ash, 

one  if  it  were  not  often 

dish  brown,   white    (white    pre- 

Weber.] 

2-6     %.     First 

mixed  with  latex  from 

dominating),  which, 

quality      valu- 

different sources,  lose* 

on  exposure  to  the 

able  ;     second, 

its  value  by  these  fre- 

air,  eventually 
assumes  the  brown- 

inferior. 

quent  admixtures.    The 

hla.-k    riililx-r   wh 

ish  red  colour  of  the 

present   in    it    i- 

outside. 

tacky,  and  produces  a 

Sometimes    black 

disastrous  effect  on  the 

concentric  veins  al- 

It-mutiny  with  \\hitc 

rose  rubber.   The  coagu- 
lation experiments  with 

and    rose  •  coloured 
veins.    The   rubber 

3  t,  although  they  gave 
very  good  results,  Bar* 

obtained  by  3  c,  sec- 
tion bright  amber. 

stopped  at  that.    Why? 
^  en"  nervous. 

Very  elastic. 

Dirty  red- 

di-h  brown. 

Slate  grey;  heated 
to  30°c,  pitclu   and 

tarkv.      Hull.' 

Impurities. 
Moisture     con- 
siderable. 

23  to  25  %. 
[Niggers, 

in  to  86, 

qpongy, 

but  little  appre- 
ciated.  Niggers 

Large  tracts  of  forest 

land   with  nibU-r  trees 

Wt-ber.J 

very       good. 

The  most  valuable  is  L. 

Resin,    6-8    *,  ; 

oirari  fiutit,     "  Lilibue." 

vih.n-4    .  Twist 

The  next  is  L.  Jtorida, 

very  fair,  20  to 

"  Nofe,"  which  .yield*  a 

30;  Resin,  6-7  V; 
ash,  0-7  %. 

dark    rubber    prepared 
with  1  i  me  j  uice.  Fi'tn  m*a 

is  estimated  in  one  dis- 

trict alone  to  be  distri- 

buted over  600  sq.  miles. 

102 


INDIARUBBER 


SYNOPTICAL  TABLE  OF  THE  DIFFERENT  VARIETIES 

II.  AFRICAN 


Commercial 
Denomination. 

Geographi- 
cal Origin. 

Botanical 
Origin. 

Method  of 
Coagula- 
tion. 

Port  of 
Shipment. 

Commercial 
Market. 

Packages. 

Usual  Commercial 
Size  and  Shape. 

LIBERIA. 

Landolphia. 

4. 
p.  53. 

Moravia. 

.Small-sized  balls. 

GRAND  BASSAM 
(Assinia). 

Ivory  Coast. 

Ficus, 
Landolphia, 
Urostigma, 
Funlumia. 

4. 
p.  53. 

Grand 
Bassam. 

Liverpool, 
London. 

Met  with  in  the  form 
of  marbles  of  1  to  3  cms. 
in  diameter  (|  to  1|  in.). 

ACCRA 
(Biscuits). 

Gold  Coast. 

Landolphia. 

3e. 
p.  49. 

London. 

-• 

Small  discs. 

NIGER 
(Niggers). 

Cameroons. 

Landolphia. 

•• 

•• 

Balls  sometimes  amal- 
gamated together,  and 
then  called  Block  Balls. 

ARUWIMI, 
MONO  ALA, 
BUMBA,  etc. 

Congo. 

-• 

•• 

•• 

•- 

Large  balls,  varying  in 
size  like  Equator  and 
Lopori. 

LOFORI.             Congo. 

•• 

•• 

•• 

Balls. 

GABOON 
(in  balls). 

f.Gaboon, 
Congo. 

Landolphia. 

Unknown. 

Ambris. 

Antwerp, 
Rotterdam, 
London. 

Very  bulky  lumps, 
which  eventually  as- 
sume the  shape  of  the 
vessel  in  which  they  are 
packed. 

GABOON 
(Strip). 

Unknown. 

Pieces  of  the  size  of 
the  thumb  to  that  of 
the  little  finger,  pressed 
and  stuck  against  each 
other,  but  which  do  not 
amalgamate  owing  to 
the  moisture  present. 

EQUATOR. 

Congo. 

•• 

Balls  glued  to  each 
other. 

UELLE. 

- 

•• 

10-20  Ib.  slabs. 

CONGO. 

Landolphia. 

2  y,  p.  48, 
and  some- 
times 1/3  II. 
p.  46. 

Banana. 

Antwerp, 
Havre. 

Balls  or  thimbles. 

LOWER  CONGO. 

Congo, 
Angola. 

Carpodinus, 
Clitandra. 

•• 

Small  cubes. 

CLASSIFICATION  OF  COMMERCIAL  RUBBERS 
OF  COMMERCIAL  CRUDE  INDIARUBBER. 


103 


Sroat°r                  8ection- 

Smell. 

Adulteration. 

LDM  IN 
Industrial 

Valuation. 

Observations. 

Brown,                   White. 

M,,M  ;     adul- 

26 to  85%. 

Rather    good 

Fair  average  quahts. 

white,  or 
black. 

terated  with  im- 
purities,    vege- 

[20 to  40.] 
[15  to  25, 

quality.    Resin, 
P5%;     ash, 

table      matter, 

Weber.] 

and  sand. 

Brown. 

Mrep  brown,  slight 

Almost  no  im- 

20%. 

Firm,     good 

Marbles  or   ball*   are 

ly  transparent,  >i<m. 
white     spots,     hril- 

purities. 

[25  to  36, 

Weber.] 

juality,    highly 

•iiinmcndahle. 

illv    an    index    of 
good     quality.        1'..  tl.-r 

liantly  poUthed  sur- 

Barin,   7-0  ft; 

sorts  highly  esteemed. 

face. 

ash,  1-0  %. 

Red  black. 
Tackv. 

White,  veined  with 
red. 

Red. 

Bad  ;  much 

Earth. 

Very   impure, 
nuch       better 
recently. 

35%. 
[30  to  45.] 

40  to  50  %. 
Great. 

Not  very  ner- 
vous,    passable 
juality,  second- 
ary. 

Quality      but 
ittle   esteemed 
at     first,     but 
seems  to  be  get- 
ting into  favour 
with  consumers. 

Resin,  5  "2  %  ; 

•• 

fermentable 

As  much  as 

ash,  0-7  %. 

matter. 

35,  Weber.] 

Putrescible 

[8  to  16, 

Resin,  3'3  %  ; 

matter. 

Weber.] 

ash,  0-7  %. 

Brown, 
slightly 
tacky. 

White,  filled  with 
pockets,  from  which 
a      whitish      liquid 

Nauseous 
(fermenting 
nitrogenous 

Very      moist, 
but  few  impuri- 
ties. 

40%. 
[30  to  40.] 
[25  to  35, 

Sluggish,  but 
little     appreci- 
ated.   Resin, 

Action  of  hypochlorite 
of    lime.       Large    balls 
strong,  small  balls  weak. 

issues.   [Large  balls  matter). 

Weber.] 

7-3     %;     ash, 

rose  blue  ?   or  red,  j 

0'9%. 

small,      white,      or  ; 

green. 

l!la.-k. 

Spongy       white, 

id. 

id. 

45%. 

But  little 

slate    grey,    mass  ; 
dry  section  dotted 

[35  to  45 
Weber.] 

appreciated. 
Resin,  11  -4%; 

with  whitish  spots. 

ash,  1-8  %. 

Is  not  dirty. 

6%. 

Resin,  3-3  %  ; 

Much  esteemed. 

ash,  0-7  %. 

l»ark.                     White. 

[7-0,  Weber. 

Resin. 

Very      fair      average  • 

ash,  0-9  *. 

quality. 

Black  or 
deep  brown. 

White,  spongy. 

.-./. 

But     little 
moisture. 

40%. 
Upper 

Thimbles  more 
esteemed    than 

The  Upper  Congo  white 
is  in  bails,  and  is  highly 

Congo  14  % 

the  balls.  Resin, 

esteemed.   The  common 

Upper     Congo, 
7-7     %;     ash, 

contains  bark  and  water, 
loss  15    .  Congo  rubbers 

0'6%. 

coagulated    h\    diluting 

with    4    to   ;,   times    its 

weight  of  water,  hence 

l>iitr«-<  ible  matter  is  en- 

. 

trained  b\  the  "cream." 

Brown     or        Brown  or  grey. 

[12  to  35.] 

Resin,  8-2  %  ; 

\erage    tensile 

Mark. 

a-h,  I'-'     . 

-er  ;  dry  good,  wet 

inferior. 

104 


INDIARUBBER 


SYNOPTICAL  TABLE  OF  THE  DIFFERENT  VARIETIES 

II.  AFRICAN 


Commercial 
Denomination. 

Geographi- 
cal Origin. 

Botanical 
Origin. 

Method  of 
Coagula- 
tion. 

Port  of 
Shipment. 

Commercia 
Market. 

Packages. 

I'snal  Commercial 
Size  and  Shape. 

KASAI  (red). 

Congo. 

Small  red  balls. 

KASAI  (black). 

•• 

Irregular  pieces. 

LOANDA 

(thimbles). 

Angola. 

j- 

1/3  II. 
2«. 
1/31. 
4. 
pp.  45,  46, 
and  53. 

St.  Paul  de 
Loanda. 

Marseilles, 
Bordeaux, 
Nantes, 
Havre. 

Thimbles  or  cubes  — 
more  or  less  perfect— 
with  from  5  nuns,  to  3 
cms.  of  edge,  i.e.  from 
?  of  an  inch  to  1|  inch. 

LOANDA 
(Niggers,  or 
Prima). 

Angola. 

Landolphia,. 

10  II. 

p.  46. 
1  ft  III. 
p.  46. 
4. 
p.  53. 

id. 

Balls  of  3  to  5  cms.  (1J 
to  2  in.)  in  diameter. 

ANGOLA 
(Niggers). 

Angola. 

id. 

1/3  II. 
p.  46. 

Balls  of  3  to  5  cms.  (1J 
to  2  in.)  in  diameter, 
and  more  or  less  de- 
formed. 

BENGUELA 
(agglomerated). 

Benguela. 

Pressed  balls,  amalga- 
mated together. 

MOZAMBIQUE 

(  marbles,  balls). 

Mozam- 
bique. 

Vahea, 
Landolphia. 

3e. 
p.  49. 

Natal. 

Balls  of  rolled  thread 
of  800  grms.  to  li 
kilos,  (say  from  28  to 
53  oz.). 

MOZAMBIQUE 
(balls). 

4. 
p.  53. 

Balls,  2  to  4  cms.  (say 
2  to  1£  in.)  diameter, 
wound  thread. 

MOZAMBIQUE 
(spindles, 
sausage). 

•• 

1/3  III.     , 
Wound 
round  a 
core  of 
wood, 
p.  46. 

Spindles,  7  to  15 
cms.  (say  2f  to  6  in.)  in 
ength  by  2  to  4  cms. 
(say  J  to'  U  in.)  in  dia- 
meter. 

ZANZIBAR. 

Zanzibar, 
Darrar, 
Central 
Africa. 

Landolphia. 

Zanzibar. 

Like  Mozambique  balls. 

CLASSIFICATION   OF  COMMERCIAL  RUBH1  K^ 


10; 


OF  COMMERCIAL  CRUDE  IMHAUUUUKI:. 

IIl'l:|:l  U      ''  •"' 


Like 

Moxamhique 

halls. 


skin  or 

Coat. 

Sen 

Smell. 

Adulteration, 

-in 

In.l  i.trial 

Vftluati..,,. 

Obwn-aUoiM. 

Clean. 

otos^;. 

ir.nn 

(    '<,h 

•    -ll.n.'ll,  high. 

\..t  much  sand 
c-r  wood,  but 
volatile  and  |ni- 
trescible  matter. 

Stoll     . 

lle-m. 

1%. 

Slat' 

I'.rillianl    dr\    sub 

stance,  i;re\,  slate- 

coloiired,  with  nu- 
merous white  IIIHIC- 
tures. 

Nauseous 
Like  Congo, 
dry. 

No  foreign 
bodies;  latch  a 
tendency  to  so- 
phistloMe. 

15  to  20%. 

T.-ndency      to 

turn       greasy. 

Tin-    in- 

teemed     of     the 

Angola      sorte. 
Id-sin.    «'6    %; 
Mb,  T4%. 

Thin  rublx-r  intiMt  be 
1  in  a  cool  place.  ' 

Reddkfa 

amber 

brown. 

lilonde,  horny, 
translucent. 

\  c  r  y  f  e  w 
f..r.-iun  bodies. 
No  moisture 
(Author-).  \  8TJ 
dirty  and  full 
of  bark  (Consul 
Pickersifill). 

8%. 

\  «  r\  ncrvoiiH. 
Highly 
esteemed. 

Tends  more  and  more 
to  disa|>|»ear  from  the 
market,  and  to  be  re- 
placed by  the  following 
species,  called  Angola 

the  more  enterprising 
planters  are  turning 
their  attention  to  the 
cultivation  of  the  nil  -I  M  r 
plant. 

Reddisli         Keddish  brown  on 
brown.       the  surface,  almost 
translucent  towards 
the    centre.      Very 
-"it.      Appears    to 
harden  after  a  few 
days  like  the  skin. 

Some  small 
vegetable 
ilehris.  Aj)pre- 
ciahly  moist. 

20%. 
[18,  Weber.] 

Not  so  nervous. 
More  tacky. 
Resin,  9-0  %  ; 
ash,  0-5  %. 

Average  qualin. 

•• 

•• 

Ifuoh 

table  <l«-bris. 

-and,  and  earth. 
Much  moisture. 

30  to  50%. 
[20  to  25, 
Weber.] 

Very    inferior 
(jiialitv.    Resin, 
4-o         ;     ash, 
0-6%. 

Much  esteemed,  if  dr\. 

Deep 
brown. 

Oreyisli,  inclining 
to  cream  white. 

\el\    lll'iist. 

Ip  t->  40%. 
(1'2  to  20, 
cr.] 

Secondary 
qualitv. 

Ue-in. 

ash,  2-6  %. 

The  arlxmculture  of 
the  <  Yara  rubber  tree  to 
iK'inir  enenreticallv  and 
scientifically  prosecuted 
in  plantations  on  suit- 
able soils  by  the  Mozatll- 

hi<|U>  ' 

Sometimes 

some- 
times hlark. 

\hitt-  section, 
shiiiinu. 

Moisture,  sand, 
earth. 

15  to 

llather 
esteemed. 
pting 
adulteration. 

Sometime* 
mme- 

times  black. 

Red    layers    and 

black         concentric 
more  numer- 
ous    towards      t  lu- 
cent re. 

Little  mois- 
ture. (Jreatly 
adulterated  by 
v  eg  e  t  a  1.  1  .• 
debris  ami  CM  n 
sand. 

18  to  SO  %. 

Rather 

.  d.  if 
it  were  not 
adult. 
Kesin.  i.'l      : 
ash,  1-S  *. 

T   M 

Like   M../am- 

bii|Ue  balK. 


106 


INDIARUBBER 


SYNOPTICAL  TABLE  OF  THE  DIFFERENT  VARIETIES 

II.  AFRICAN 


Commercial 
Denomination. 

Geographi-     Botanical 
cal  Origin.        Origin. 

Method  of 
Coagula- 

Port  of       Commercial 
Shipment.        Market. 

Partner              Usual  Commercial 
Packages.            gize  ftnd  Shape 

MADAGASCAR 
(black). 

Madagascar, 
Commores. 

4. 
p.  53. 

Nossi-Be. 

Irregularly  shaped 
masses,  most  generally 
flattened  by  the  pres- 
sure of  the  package. 
The  lumps  vary  in  size 
from  a  man's  fist  to  a 
human  head. 

MADAGASCAR 
(pinky  rose). 

Madagascar, 
Reunion. 

Tamatave. 

•• 

Round  balls. 

MADAGASCAR 
(Niggers). 

Madagascar. 

.. 

Dark  large  balls. 

III.  ASIATIC 

ASSAM. 

North-west       Ficus, 
of  Bengal         Urceola. 
(Brahma- 
putra). 

la  11. 

p.  45. 

1  j8  III. 

p.  46. 

Calcutta. 

London. 

In  3  cwt. 
baskets    of 
split       rat- 
tans, cover- 
ed   with    a 
gunnv  bag 
tied      with 
cane. 

Blocks  (weighing  to 
150  grms.,  say  5  oz.), 
which  strongly  adhere 
to  the  cloth  'in  which 
they  are  packed,  to 
which  they  stick  on  ac- 
count of  the  greasy  state 
into  which  this  kind  of 
rubber  quickly  passes. 

RANGOON.           Burmah, 
Annam. 

Singapore, 
Rangoon. 

{Irregular  lumps. 
Similar  to  Assam. 

- 

PENANG  and        Prince  of     Ficus,  Cyn- 
PATANI.               Wales          anchum. 
Island, 
Malacca, 
Sunda  Isles. 

Penang. 

Irregular  blocks  of 
about  1  sq.  decimetre 
(4  inches). 

CEYLON.             Ceylon.          Hevea,         Churn  or 
Manihot,          centri- 
;  Glaziowii,         fugal. 
:    Castilloa 
elastica. 

Colombo. 

London. 

Crepe  block  biscuit. 

COCHIN-CHINA.       Cochin-  :    Parameria 
China,       Glaudulipe. 

•• 

•• 

Clumsy,    hard,    deep 
j  brown  lumps. 

IV.  OCEANIC 

JAVA               Sumatra           Ficus 
(Lampong).          (South-         elastica. 
east). 

1/3  III. 
p.  46. 

Singapore. 

More    or    less    bulky 
cakes,  formed  by  agglo- 
merated sheets. 

JAVA  Sumatra  id. 

(Ben  Kalen).         (South). 


id. 


CLASSIFICATION   OF   COMMERCIAL   RUBBERS 


107 


OF  COMMERCIAL  CRUDE  INDIARUHI'.KK 

lit  1:1:1  i:s  — 


Skin  or 
Coat. 

Section. 

Smell. 

Adulteration. 

Low  in     ! 
Industrial        Valuation.               ObeerratloM. 

, 

Black  or 
very  <l>  gp 

hrown, 

moist, 

covered 

White,  slightly  rose. 

- 

Earth,  gravel, 

much  moisture. 

•  45%. 
pi,  Weber.) 

1.,  --  .  -ti  .  mi  .t 
than  the   |>ink\ 

10-4    %;    ash, 

l-l     . 

Tli.-  milk  of  the  In- 
firior  Korta  ia  coagulated 
i.-.  treatment  With  aalt 
water  or  acid,  or  by  arti- 
ficial heat.  The  black 

with 

rubber  shipped  from 

impuri  ies. 

Majunga  i«  rappoaed  to 
be  produced  bymeh 

HMthod*. 

Peculiar 
deep  rose 

Bright  red  or  rose. 

Few  impurities-. 
Rather  moist. 

M    . 
I'-Jii,  Weber.] 

Very  min-h  es- 

Speciality  for  moulded 

artl.l,  Mada- 

red. 
Smooth 
like  pale 
horn. 

nervous,  rather 

elasti.-. 
1-1         ;      ash. 
0-2%. 

gaacar  sort,  owing  to 
reckless,  felling  and 
digging  up  by  the  roota, 
likely  to  be  toon  ex- 

hrartad 

M 

Brown,  white  or 

25  to  45  %. 

Resin,  7'8%; 

Very  variable. 

black. 

ash,  2-3     . 

• 

RUDDERS. 

Brown. 

Dark,    sometimes 
reddish  with  white, 

•• 

Moisture,  sand,     25  to  40  %. 
earth.              115  to  40. 

Not  much  es- 
teemed.   Resin, 

Tending  to  disappear 
from  the  market. 

almost  transparent, 

Weber.] 

5-6%;  ash,  0-7%. 

spots.    The  rubber 

is     always     of     a 

mottled  appearance 
with     bright     pink 

streaks. 

•"" 

Very  dark 
brown. 

Brilliant,  marbled 
with  white,  blackish! 
red. 

Always  wood. 

20%. 
[12  to  30, 
Weber.] 

More    valued      Cultivated  niblier  from 
than    the    pre-  chonemorpha,     macro- 
ceding.     Ke.si...    phvlla.  Rhynr  Wallichi, 
4'4%;  ash.n-T    .  Kcdvsanthera,    Micran- 

tha,"    yield    results    in- 

-ting  to  planters  in 

further  India. 

Black  on 
the  outside. 

Deep  brown,  bright 
transparent  brown. 

Earth,  sand.       20  to  25  %. 
11.-.  to  30, 
Weber.] 

Rather  nervous. 
Resin,  7  •«;  : 
ash,  1-3  %. 

Fair  average   q<. 
dry,  good.    Tacky,  in- 

Straw. 

Straw. 

Faint.                   Nil. 

Cultivated       Rational   cultivation. 

Hevea    rubber,    Recent  importation. 

about  equal  to 

Para.    Superior 

for  waterproof- 

ing, but  inferior 

in           tensile 

strength. 

RUBBERS. 

Deep  brown  - 

Brown  red. 

LStoM      .         Little  valued,        Trndrn<  \     t--    .lark,  n 

coloured 

ITJ  to  .-{it,     inn    esteemed,  and  baooma  tacky  in  the 

tears. 

Weber.  1      if    drv.     Resin,  airand  with  heat.  "Jara 

5-6     '     :      ash.    nil.i.rr    is    similar    (to| 

Assam)  but  usually  not 

so  good."—  Moms. 

Bright           "Almonds  "of  red                                                       30  to 

.. 

blonde-     ;  Sumatra  gutta  per- 

coloured     cha  tears  with  bluish 

tears. 

efflorescence. 

108 


INDIARUBBER 

SYNOPTICAL  TABLE  OF  THE  DIFFERENT  VARIETIES 

IV.  OCEANIC 


Commercia  1 
Denomination. 

Geographi- 
cal Origin. 

Java. 

Botanical 
Origin. 

Method  of 
Coagula- 
tion. 

Port  of 
Shipment. 

Commercial 
Market. 

Packages. 

Usual  Commercial 
Size  and  Shape. 

JAVA. 

Ficus 
elastica. 

•• 

More  or  less  bulky 
cakes,  formed  by  agglo- 
merated sheets. 

BORNEO 
(White  Assam). 

Borneo, 

Straits 
Settlements, 
"Celebes, 
Moluccas, 
Philippines. 

LTrceola, 
Willugh- 
beia,  Dijera, 
Callotropis. 

3e. 
p.  49. 
By  salt 
water  from 
ash  of 
leaves  of 
Nipa  palm. 

Macassar, 
Singapore. 

Sheets  or  balls  more 
or  less  bulky,  deformed 
(callotropis). 
Sheets  varying    from 
2  to  3    centimetres   in 
thickness,  with  numer- 
ous  depressions  (other 
botanical  origin). 

BORNEO 
(Djambes). 

Sumatra. 

Willugh- 
beia,  Leuco- 
notis. 

•• 

Singapore. 

•• 

Balls  and  sheets 

BORNEO 
(Ben  Koclen). 

Block  Pura. 

Rather  thick  sheets. 

NEW  GUINEA. 

•• 

••       .. 

Clusters  of  small  balls. 

PONTIANAE. 

Borneo 
(West). 

Greyish-white  balls. 

NEW 

CALEDONIA. 

New 
Caledonia. 

Ficus 
prolixa 
(Banyan), 
Urostigma, 
Prolixa, 
Artocarpus, 
Integrifolia 

la  I. 

pp.  4Qetseq. 

Port  Villa. 

Marseilles. 

Cakes  like  Para,  from 
6  to  10  kilos.  (13-2  to 
22  lb.). 

CLASSIFICATION   OF  COMMERCIAL   RUBBERS 


109 


OF  COMMERCIAL  CRUDE  INDIARUBBER. 
RUBBKRS— conti/i 


Skill  ..r 

Ooat, 


SlIH-ll. 


,  ,        . 


Tears  of  a        The 
more        more  decided. 


lsto4.r>     .       l.iitlo  valm 


colour. 


Ooat 

(<-:illotro- 
l-i-o.  Hrown 
(cither  bota- 

White paste  (cal- 
lotropis).  White, 

often  rose  or  violi-t 
t  in  ted  (other  bo  tan  i- 

Callotropis      Pockets  with    i: 
rubbers      abundant     ser- 
haveasmell  urn. 
of  tanned        Pockets  with    :;. 

to  30%.       Fairly  good, 
to  40  %.        Much  less  e*- 

Obtained 
phattetoplMtti  " 

troin  a  few  inches  to  2  to  i 
:'.  ft.  long,  and  allowing 

nical  origin). 

;il  origin). 

leather,  at-   abundant     ser-      | 

35  to  50     teemed. 

the  jui.1.  to  drain  into 

tril.utedto 
the  tannin 
contained 
in  the 

um,   frequently      Weber.] 
sand,    greenish 
clays. 
Very     porous 

in  kiu.heatbeingsome- 
times  applied  to  one  of 
kfaeptMMwbtath    •-• 
flows  slowly.    TbeUlU 

vine. 

and  spongy,  the 

of  rubber  forconvenieooe 

The  other 
kinds  have 

pores    being 
filled  with  *ali 

of  carrying  are  threaded 
••n  >  -trip  of  rattan. 

a  nauseous    water. 

smell,  com- 

ing from  the 
alluimen- 

oidsof  th, 

latex  not 

asepticisi  <l 

by  the 

tannin. 

Reddish 

Greenish  red. 

Clay  water  in      45  %  and         Little  enough 

(< 

brown. 

quantity. 

more.       esteemed  on  ao- 

count    of   adul- 

teration. 

llrown. 


Black. 


White  inside. 


Whitish. 


Ilather  pure. 


I  it  own,        Section  veined  with       Slight  1\  Very  pure. 


inclining  to 
black. 


white. 


smoky. 


Good  qualitx. 


15%.          Good  when  free       Sometinu-. 

from  bark  orim-  sort  is  shipped,  whitish 
i  purities.  Resin,  and  hard,  almost  recem* 
4-2%;ash,r:<  .  bling  bard  balata. 

15  %.         Resin,  85  to  95  %  i     Highly  resinous.  Value 
ash,  1-8  ;;.        low. 

18  to  20,.        Very       good!     Lately    put    on    the 
quality       wlu-n   European  market. 
,  free    from    di- 
verse      admix- 
tures. 

Slightly  resin- 
ous. 


CHAPTEE    V 

PHYSICAL  AND   CHEMICAL  PROPERTIES   OF   THE   LATEX  AND  OF 
INDIARUBBER— GENERAL  CONSIDERATIONS 

Preliminary  Observations — Resume  of  previous  chapters. — In  Chap.  I.  the 
general  definitions  of  latex  and  of  rubber  have  been  given,  and  in  succeeding 
chapters  attention  has  been  drawn  to  the  differences  in  the  physical  properties  and 
in  chemical  constitution  of  these  two  substances,  according  to  the  producing  plants, 
their  age,  environment  of  the  locality  in  which  they  grow,  season,  and  even  hour  of 
collection,  method  of  tapping,  and,  finally,  the  process  employed  for  separating  and 
getting  at  the  rubber  held  in  suspension  in  the  latex. 

From  this  diversity  of  circumstances,  which  may  influence  one  way  or  another 
the  substance  to  be  examined,  arises  the  absolute  necessity  of  examining  the 
physical  and  chemical  properties  of  the  latex,  and  of  rubber,  in  a  rational  and 
systematic  manner.  Only  one  and  the  same  type,  therefore,  will  be  examined  from 
the  different  points  of  view  which  the  subject  involves.  Proceeding  thus,  it  is 
hoped  some  deductions  may  be  drawn  with  a  really  tangible  interest,  in  actual 
industrial  practice  ;  and  if  some  anomaly  supervene,  it  will  suffice  to  point  it  out. 
A  few  examples  will  explain  this  scheme. 

Adriani's  researches  on  the  latex  of  the  Ficus  elastica. — Dr.  Adriani,  author  of  a 
monograph  on  the  fresh  latex  of  the  Ficus  elastica^  direct  from  the  plant,  observed 
that  in  a  general  manner  the  quantity  of  solid  matter  contained  in  a  resiniferous 
sac  was  less  the  higher  up  the  tree  the  incision  was  made,  and  consequently  on  the 
younger  parts  of  the  incised  tree.  He  experimented  on  a  Ficus  elastica  of  about 
7J  feet  in  height.  The  following  are  his  results  : — 

TABLE  XVIII. — SHOWING  THE  PERCENTAGE  OF  SOLID  MATTER  IN  LATEX 

ACCORDING    TO    HEIGHT    OF    INCISION    (ADRIANl). 


Quantity  of  Latex 
Evaporated. 

Height  of  the 
Incision. 

Total  Residue. 

Percentage  of 
Solid  Matter. 

Kilogrammes. 
0-185 
0-393 
0-143 
0-825 

Metres. 
0-30 
1-74 
2-10 
2-25 

Kilogrammes. 
0-046 
0-095 
0-030 
0-145 

25-15 
24-05 
20-98 
17-70 

Deductions  to  be  drawn  from  above  Table. — Such  analytical  data  are  certainly 
very  interesting,  and  would  be  more  so  if  experiments  had  been  conducted  not  only 
on  Ficus  elastica,  but  also  under  similar  conditions  on  other  species  of  rubber  trees  in 
general.  Some  general  law  could  then  have  been  deduced  from  such  experiments 
as  to  which  was  the  most  advantageous  part  of  the  rubber  tree  to  bleed,  but  at  the 
same  time  they  show  us  the  futility  of  the  summary  indication  of  such  and  such  a 
manual  dealing  with  this  subject,  which  tells  us  that  the  latex  yields  so  much  per 
cent,  of  rubber  without  any  further  particulars. 

Example  II. —  Variations  in  size  of  the  globules  of  rubber  svrimming  in  the 

no 


PROPERTIES   OF   LATEX   AND   INDIARUBBER 


1  1  1 


latex. — Adriani,  examining   micrOMOpicalty  tlie  latex  of  the  Ficu*t  found  that  th<- 
spherical  globules,  \\hich  e.ni>t it ute  rubber,  tl'.utin^  in  the  liquid  in  givat  numbers, 
a\era^e  -•'•'»  inieroinillimetres  when  tin-   late\  is  taken  from  tin-  lo\\rr  jmrt  of  the 
tree,  \\hiUt  tlioso  of  the  upprr  part   of   tin-  tree  an-  '_'  inicroinillin 
in  giving  the  dimensions  of  the  globulites  <>f  rubber,  iln-  height  nni-t  i  d  at 

\\lii.-h  tin-  |;it.-\  was  collected  on  the  tapp«-d  tnv,  as  well  an  the  \.in.-t\  i,,  uhirh 
tin-  tree  belongs. 

I  imple  III. — The  density  of  t/ie  lat>  ••.  ll'ie  are  three  ex|N-rinn-iiU  to 
.let. •inline  the  den>ity  of  the  latex  :  one  on  a  juiee,  \\ithoiit  any  indication  rith.-r 
of  its  origin  or  of  the  height  of  incision;  the  t\\<>  nther>  b\  l'iv  <un-  on  H  latex 
rich  in  rubber,  the  other  on  a  poorer  juice. 

TABLE  XIX. — SHOWING  DENSITY  OF  RUBBER  LATIN  <MI-SI»RATT,   I 


Density. 

Miispratt,  without  indication    . 
Ure  :  Latex  rather  thick    . 
Ure  :  Latex  thinner  .... 

T01200 
1  '01750,  say  37  per  cent,  of  gum. 
1-01121,    „    20         „ 

Above  data  as  to  density  insufficient. — Such  data  cannot  facilitate  tin- .  \  ui  d.  t.  i 
initiation  of  the  density  of  a  latex  without  the  comparative  results  furnished  by  a 
tixed  and  immovable  type. 

Example  IV. —  Variations  in  analyses  of  latex  still  more  striking. — The.se 
differences,  and  the  difficulties  which  they  beget,  are  still  more  striking  if  \\«- 
compare  the  analyses  of  various  species  of  latex.  Faraday  analysed,  in.  1*26,  a 
//•'•"/  latex  sent  to  Europe.  Opposite  this  analysis  there  is  generally  placed  that 
given  by  Adriani,  on  the  laticiferous  juice  of  a  terminal  bud  of  Ficu*. 

TABLE  XX. — ANALYSES  OF  LATICES  OF  lV\i;\    \M>  ASSAM 
RUBBERS  (FARADAY,  ADRIANI). 


Analysis  of  a  Latex  imported  from 
Brazil  (Faraday). 


Caoutchouc  . 

Albuminous  matter 

Bitter  nitrogenous  colouring 

principles 

Substances  soluble  in  water 
Wax    .... 
Water  slightly  acid      . 


Per  cent. 
37-70 
1-90 

7-13 
2-90 
0-13 
56-37 


Analysis  of  a  Latex  of  Ficus  of  2 '25 
metres,  say  7£  feet  in  height  (Adriaui). 


Caoutchouc  . 

Resin  soluble  in  alcohol  but 

insoluble  in  ether 
Organic  acids  comhinrd  \\ith 

magnesia .... 
Substances  insoluble  in  water 
Calcic  and  sodic  salts  . 
Water. 


Per  cent. 
9-57 

l-f.8 


0-36 

2-1" 

traces 

82-30 

95*99 


Al l>n in iinnds  and  tannin. — Ure  did  not  find  in  the  two  samples  of  latex  he 
submitted  to  analysis  the  albuminous  matter  determined  by  Faraday,  whilst.  «'n 
the  other  hand,  he  determined  the  presence  of  tannin.1 

!I  cannot  trace  Ure  having  mentioned  tannin  as  an  ingredient  of  latex.  He  mentions 
aloetic  matter  which,  if  it  contains  tannin,  is  essentially  ilillerent  from  tannin  /»»-r  sr.  It  will 
be  as  well  to  quote  Ure  textually  as  follows  : — "  Having  been  favoured  by  Mr.  Sevier,  fonwrlv 
managing  director  of  the  Joint-Stock  Caoutchouc  Company,  and  by  Mr.  Bealc,  engineer,  with 
two  different  samples  of  caoutchouc  juice,  I  have  subjected  each  to  chemical  examination. 
That  of  Mr.  Sevier  is  greyish  brown,  that  of  Mr.  Beale  is  of  a  milky  grey  colour,  the  deviation 
iu  whiteness  in  each  case  being  due  to  the  presence  of  aloetic  matter  which  accompanies  the 
caoutchouc  in  the  secretion  by  the  tree.  The  former  juice  is  of  the  consistent  «•  ot  thin  cream, 
has  a  specific  gravity  of  1 '04 125,  and  yields  by  exposure  upon  a  porcelain  crucible  in  a  thin 
layer,  for  a  few  days,  or  by  boiling,  20  per  cent,  of  solid  caoutchouc.  The  latter,  though  it  has 


112  INDIARUBBER 

Latex  of  trunk  absent  from  leaves  and  branches. — Finally,  Nees  d'Esembeck 
and  Clamor  Marquart  identified  real  caoutchouc,  as  we  know  it,  in  the  latex  of  the 
trunk  of  the  Ficus,  but  not  in  the  branches  and  leaves  of  the  same  plant ;  tilt- 
substance  which  takes  its  place,  and  which  they  call  visriiu',  is  only  converted  inter 
on,  according  to  these  two  chemists,  into  indiarubber. 

Want  of  co-ordination  in  researches. — Such  examples  could  be  multiplied,  but 
those  given  amply  suffice  to  show  that  if  the  numerous  researches  on  this  subject 
are  full  of  interesting  details,  and  form  precious  documents  for  the  history  of 
rubber,  they  are  at  least  awanting  in  sufficient  co-ordination  to  deduce  therefrom 
precise  and  certain  laws.  It  would,  therefore,  be  useful  to  proceed  more  methodic- 
ally, and  thus  assist  those  who  seek,  in  a  work  of  this  kind,  acquired  information, 
from  which  they  may  draw-  proper  conclusions.  That  is  the  determinant  reason 
which  leads  us  to  confine  the  examination  to  the  physical  and  chemical  properties 
of  (1)  the  latex  of  the  most  highly  esteemed  rubber-producing  plant,  and  (2)  of 
the  rubber  which  it  yields,  namely,  the  rubber  to  which  the  trade  up  to  now  has 
given  a  just  preference — the  Hevea  braziliensis — and,  as  type,  a  Hevea  of  about 
twenty-five  years  old,  that  is  to  say,  one  arrived  at  the  adult  age,  and  thus  capable 
of  producing  the  most  abundant  and  the  richest  milk.  The  plant  has  been 
incised  0'50  metre  (say  19 '65  inches)  above  the  soil,  the  first  hour  in  the  day  the 
second  month  of  the  dry  period  of  the  year  1888  (good  average  harvest  in  the 
Lower  Amazon).  If  in  course  of  such  examination  wu  find  in  the  special 
literature  of  this  subject  a  fact  in  flagrant  contradiction  with  the  results  obtained, 
attention  will  be  drawn  thereto,  a  work  of  this  nature  never  having  anything 
absolute  about  it. 

Latex — Physical  properties  —  Colour.  —  The  latex  of  the  Hevea  braziliensis, 
collected  under  the  above  conditions,  has  been  examined  under  the  microscope.  It 
is  a  liquid,  white  to  the  naked  eye,  but  really  colourless,  or  rather  slightly  amber- 
coloured,  in  which  there  float  quantities  of  suspended  spherical  globules,  of  which 
the  diameter  varies,  and  the  average  of  which  is  3*51  /A.1  These  globules  constitute 
the  rubber.  Colourless  in  themselves,  they  impart  to  the  liquid,  by  their  extreme 
division — whilst  each  of  them  still  preserves  its  own  individuality, — that  white 
milky  aspect  which  it  has  not  by  itself. 

Action  of  air,  light,  and  contact  ivith  coloured  juices  on  colour  of  latex  and 
resultant  rubber. — The  coloration  of  this  liquid  may,  however,  under  definite 
circumstances,  be  altered  very  perceptibly,  and  so  influence  the  final  colour  of  the 
rubber  which  is  produced  from  it.  Without  mentioning  the  oxidising  action  of 
air  and  light,  the  effects  of  which  will  have  to  be  studied  more  especially  when 
treating  of  real  rubber,  it  is  possible  that,  with  rubber  trees,  other  than  Hevea,  the 
juice,  as  it  leaves  the  laticiferous  tissue,  in  its  passage  to  the  exterior  portion  of 
the  wound,  may  have  to  traverse  other  tissue  containing  coloured  juices.  The 
colour  of  the  latex,  as  well  as  its  resiniferous  portion,  would  be  appreciably 
altered. 

Morellefs  microscopical  examination  of  the  bark  of  the  Landolphia — Resinous 
cells. — Morellet  establishes  a  similar  fact  whilst  studying  the  Landolphia  yielding 

the  consistence  of  pretty  rich  cream,  has  a  specific  gravity  of  only  1'0175.  It  yields  no  less 
than  37  per  cent,  of  white,  solid,  and  very  elastic  caoutchouc.  ...  I  find  that  neither  of  the 
above  two  samples  of  caoutchouc  juice  affords  any  appearance  of  coagulating  when  mixed  in  any 
proportions  with  alcohol  of  0'S25  specific  gravity,  and  therefore  I  infer  that  albumin  is  not  a 
necessary  constituent  of  the  juice,  as  Mr.  Faraday  inferred  from  his  experiments  published  in 
the  21st  volume  of  the  Journal  of  the  Royal  Institution.  The  odour  of  Mr.  Sevier's  sample  is 
slightly  acescent ;  that  of  Mr.  Beale's,  which  is  by  far  the  purer,  has  no  disagreeable  smell  what- 
ever. The  taste  of  the  latter  is  at  first  bland  and  very  slight,  but  eventually  very  bitter  from 
the  aloetic  impression  upon  the  tongue.  The  taste  of  the  former  is  bitter  from  the  first,  in 
consequence  of  the  great  excess  of  aloes  which  it  contains.  When  the  brown  solution,  which 
remains  in  the  capsule  after  the  caoutchouc  has  been  separated  in  a  spongy  state  by  ebullition 
from  100  grains  of  the  richer  juice,  is  passed  through  a  filter  and  evaporated,  it  leaves  4 
grains  of  concrete  aloes.  .  .  .  The  prepared  aloetic  liquor  is  not  affected  by  the  nitrates  of 
baryta  and  silver.  It  affords  with  oxalate  of  ammonia  minute  traces  of  lime." — TK. 
1  The  /j.=  l  micromillimetre,  which  is  the  thousandth  part  of  a  millimetre. 


PROPERTIES   OF    LATEX   AND    INDIARUBBER 


113 


.Mo/.;tmbiqiie  rubber,  the  microscopical  examination  of  the  bark  of  which  lie  d» 
thus :  -Si -v» Till  layers  of  parenchyma  ue  met  with  on  the  exterior p.c.  (Fig.  35), 
alt. Tiiatinir  with  livers  of  suber,  «.  Where  desquamation  has  occurred,  only  th«- 
two  internal  lavers  are  visible.  Beneath  the  extreme  internal  layer  of  the  suber, 
luminous  sclerose  cells,  c.*.,  occur,  arranged  in  radial  lines,  forming  a  continuous 
thi.-k  la\.  i  generally  of  from  10  to  20  cellules,  then  parenchyma,  intermixed  with 
num. Tons  branches  of  sclerose  cells,  then  soft  liber,  formed  from  paivnrlmua,  cell* 


FIG.  35.— 1.  Laitdolphia,  which  yields  Mozambique  rubber  ;  transverse  and  longitudinal 
section  of  the  bark:  c.s.,  sclerose  cells;  p.c.,  cortical  parenchyma;  sit.,  suber  ; 
la.,  laticiferous  vessels;  c.res.,  resinous  cells.  2.  c.rcs.,  detail  of  the  resinous 
cells  in  the  longitudinal  section  of  the  Vahea  which  yields  Mozambique  rubber. 

full  of  a  red  win,  c.res.,  possessed  of  great  colouring  power,  liber  fibres  >mall  in 
MiimlnT,  and  laticiferous  vessels  in  very  great  abundance/  Tln^e  resinous  edN 
are  the  cause  of  the  peculiar  smell  of  Mozambique  rubber. 

Smell. — Fresh  Jfevea  latex  is  inodorous.  But  when  left  by  itself  it  rapidly 
acquires,  under  the  action  of  the  oxygen  of  the  air,  a  slight  smell  of  rnethylamine, 
which  again  makes  itself  felt  in  the  rubber  prepared  from  it  if  it  be  not  sterilised 
by  the  smoking  process,  as  occurs  with  Para  seconds,  or  when  a  small  quantity  of 


c..t 


FIG.  36. — Transverse  section  of  the  < 'allot r»tn*  > 
--./.,  cells  full  of  tannin. 

smoked  is  mixed  with  a  larger  quantity  of  spontaneously  coagulated  rubber.  This 
characteristic  smell  is  equally  manifest  in  some  varieties  of  other  juices  depending 
upon  the  intimate  constitution  of  each  latex,  and  its  more  or  less  perfect  state  of 
preservation, 

T«*t,.—  The  taste  of  fresh  Hevea  latex  is  not  very  accentuated,  rather  pleasant 
and    sweet  than    repugnant    and  bitter.     Carrey  says  he   drank   it   not  without 
8 


114  INDIARUBBER 

enjoyment,  but  the  latex  must  always  be  fresh,  as  the  taste  as  well  as  the  smell 
change  quickly  in  contact  with  the  air.  Although  this  change  is  not  so  marked  in 
the  Hevsas,  it  is  very  much  more  decided  in  the  Hancornias  of  Peru  and  the 
Landolphias  of  Western  Africa.  The  juice  of  Callotropis  gigantea  of  Borneo  owes 
its  slightly  bitter  taste  to  a  particular  astringent  substance  whose  presence  has 
been  pointed  out  by  Morellet,  in  certain  cells  of  the  bark  of  this  plant, 

Density. — It  has  already  been  seen  how  difficult  it  is  to  determine  in  an 
absolute  and  rigorous  manner  the  density  of  the  latex,  and  how  many  circum- 
stances intervene  to  modify  the  results.  As  a  general  rule,  the  richer  a  juice  is  in 
rubber  the  lower  is  its  density,  and  the  higher  the  density  the  less  will  be  tfie  amount 
of  rubber  therein  per  unit  of  volume.  However  that  may  be,  the  density  of  the 
latex  here  adopted  as  type  is  1 '01 9  at  the  temperature  of  14°  C.  (57 '2°  F.),  and 
corresponds  to  a  richness  in  real  caoutchouc  of  32  per  cent. 

Chemical  properties  —  Proximate  principles.  —  In  Table  XXI.  the  chemical 
composition  of  the  latex  of  the  Hevea  braziliensis  at  the  moment,  it  issues  from 
the  plant  is  given. 

TABLE  XXL — CHEMICAL  COMPOSITION  OF  THE  LATEX  OF  THE  HEVEA 

BRAZILIENSIS. 


Elastic  matter 

Nitrogenous  organic  matter  (putrescible) 
Mineral  salts,  sodic  and  calcic  (no  magnesic) 
Resinous  bodies     ..... 
Water  slightly  alkaline 


Per  cent. 


32-00 
2-30 
970 

traces 
55  to  56-00 


100-00 


This  analysis,  which  appreciably  approaches  that  given  by  Faraday  in  1826, 
differs,  however,  in  one  interesting  point.  Faraday's  analysis  was  of  a  sample  of 
latex  imported  from  Brazil.  It  had  thus  taken  some  time  in  arriving  at  the 
laboratory.  Owing  to  very  great  liability  to  decomposition  of  the  vehicle  of  the 
rubber  globulites,  in  spite  of  all  precautions  in  bottling  the  sample  sent,  Faraday 
found  an  acid  reaction ;  whilst  on  the  spot,  at  the  very  moment  the  liquid  flows 
from  the  incision,  it  has  a  slight  but  decidedly  alkaline  reaction.  This  ephemeral 
alkalinity  of  the  latex  of  the  Hevea  is  peculiar,  and  totally  differentiates  it  from 
the  latex  of  the  Ficus,  which,  as  soon  as  it  issues  from  the  producing  plant,  always 
appreciably  reddens  litmus  paper.  Adriani,  who  more  especially  examined  the 
latex  of  the  Ficus,  attributes  the  reaction  to  the  presence  of  a  peculiar  organic 
acid,  which  is  distinguished  from  all  other  organic  acids  by  its  sodic  and  potassic 
salts  being  difficultly  soluble  in  water,  whilst  the  salts  which  it  forms  with  lime, 
magnesia,  and  iron  are  very  soluble.  See  Table  XX. 

Nitrogenous  putrescible  organic  bodies  in  the  latex. — Our  analysis  mentions 
2 '30  per  cent,  of  nitrogenous  putrescible  matters.  This  term  is  purposely  used 
in  preference  to  that  of  albuminoids  or  proteid  matter.  The  properties  of  the 
substances  have  not  been  sufficiently  studied,  and  scientists  who  have  specially 
examined  them  are  too  much  at  variance  as  to  their  nature  to  justify  a  definite 
declaration  on  the  point.  They,  however,  merit  very  careful  examination,  for  it 
is  undoubtedly  to  their  presence  that  the  great  liability  of  the  latex  to  change,  to 
which  we  have  already  referred,  is  due,  and  it  is  almost  always  owing  to  their 
insufficient  elimination  or  neutralisation  that  commercial  rubber  owes  its  most 
salient  defects. 

The  mineral  matter  in  serum  of  Hevea  latex. — It  is  unnecessary  to  dwell 
particularly  on  the  mineral  matters  present  in  the  serum  of  the  milk  of  the  Hevea, 
consisting  of  potassic  and  calcic  organic  salts  to  the  exclusion  of  magjiesic  salts. 


PROPERTIES   OF   LATEX   AND    INDIAKtT,r,l-:u 


1  15 


There  i-    nntliin^   ;il> normal    in    their    |.i.-,  i,,,..  ;lnd    they    would    U-    uninU-n 

they  dill  nut  atl'ord  an  analytical  method  ,,|'  a^i^niiiLr,  ••\fiituall\.  \sith  lOnM  degree 

•  •f  certitude,  a    true   certificate  of    its   origin    t<>   any    gi\«-u    nibb.-i        M.i-i,,-  . 

arc   absent    tVniii    tin-   mother    liquor  of   tin-    //»•*•»,/    juice.    \\liiUt    . \driani  -   anal\-i- 

show.s  its  pre-ciicr  iii  every  instance  in   /•'/.•//.<  latex.      Apiin,   tin-  cal.-i.-  an. I  |. 

salts   nt    tin-    //•       /    an-   ••iiin|Miiiinls   nf   t  \vu   Iwisrs    \\itli    a    >|M'cial    and    liithr;  • 

determined  organic  acid  ;  t  lii-.sc  t  \\«i  hasi'H  air  met  \\  itli  in  /.<init»/ji/tin  juice,  roinl  lined 


37.—  Transverse  section  of  Lau<!»//i/</'<>  •nnnmfff.ra  :  p.c.,  cortical  i»arenchyina  ;  //., 
liln-r  containing  crystals  ;  la.t  latieiferons  vessels  ;  /.//.,  lil>erian  fibres. 


\\ith  c\alic  acid,  and   Morullet  discovered  under  the  microaoope  decided 
cxf  this  compound  (Fig.  37  /?'.,  Fig.  38  <-i\  ). 

T/ie  resinous  bodies  in  the  latex.  —  The  traces  of  resinous  bodies  in  the  analy>i> 
of  J/t  '/'ex  latex  are  for  the  moment  neglectable  quantities.  They  are  dealt  with 
under  the  chemical  composition  of  raw  commercial  rubber. 

Dqmbonite  amylaceous  and  saccharine  jwinciples.  —  Certain  amylaceous  and 
saccharine  principles  are  met  with  in  the  latex  of  the  //"/""//""<  "t  IVrnainbuco 
and  Maranliam,  in  that  of  the  African  Landolphias  and  Vaheas,  and  the  UrceoUu 
of  the  Malays.  Aim^  Girard  was  the  first  to  draw  attention  to  these  ].riiicipl<-. 


1'n:.    38.    1. — Transverse    and    longitudinal    sections    of    the    liark    of  the 

polfiwit:    /".,  laticiferous  vessels  and  latex;    //.,    liber;  cr.,    small   cells  with 

crystals. 

In  his  tirst  memoir  t<>  the  Arademy  «>f  Science-  in  I  s«;s.  h.  jayg  "The  defective 
pnu-ess  followed  in  the  preparation  of  Galn.on  nil»Ker  leave-  a  white  limpid  liquid 
enclosed  therein,  which  changing  gradually  alters  the  caoutchouc  itself,  and  causes 
it  eventually  to  lose  all  its  properties.  ()\\ini:  t..  thes,-  ,),••  ; -.  Gaboon  nibU-r 
reijuires  special  and  repeated  treatment.  In-fore  this  method  wa>  established, 
manufacturers  could  not  use  it,  s..  Cerard  and  Auln-rt  of  Grenelle,  being  unable  to 
utilise  a  lot  of  Gaboon  rubber,  sj wiled  by  age,  resigned  them>elves  to  dec..iujM,>e 
it  by  heat  and  convert  it  into  liquid  pitch.  During  the  progress  of  the  operation, 


116  INDIARUBBER 

and  amongst  the  volatile  bodies  condensed  in  the  chimney,  they  observed  a  white 
substance,  crystallised  in  fine  needles,  and  possessed  of  a  sweet  taste.  That  is  the 
substance  which  I  have  called  Dambonite." 

Pre-existence  of  dambonite  in  the  fresh  latex  itself.  —  According  to  Girard, 
dambonite,  a  neutral  volatile  body,  pre-exists  in  the  latex  itself  when  it  is  of 
recent  production.  But  when  the  serum  has  been  imprisoned  for  a  long  time  in  / 
the  pores  of  the  rubber,  it  no  longer  contains  the  same  saccharine  substance ;  it 
is  converted  into  a  gummy  body  in  which  there  is  found,  besides  a  little  unaltered 
dambonite,  another  non-volatile  saccharine  body  of  different  composition.  In  the 
samples  examined  Girard  collected  as  much  as  TT^y  of  pure  dambonite  from  the 
caoutchouc  analysed. 

Properties  of  dambonite. — It  is  a  white  crystalline  substance,  very  soluble  in 
water,  readily  soluble  in  ordinary  alcohol,  slightly  soluble  in  absolute  alcohol.  It 
melts  at  190°  C.  (374°  F.),  and  volatilises  from  200°  to  210°  C.  (392°  to  410°  F.) 
in  long  brilliant  needles.  Its  chemical  composition  is  indicated  by  the  formula 
C8H8O6. ' 

Hydrates  of  dambonite. — In  presence  of  water,  dambonite  hydrate  takes  up 
three  equivalents  of  water,  which  it  loses  at  100°  C.  (212°  F.).  The  crystals 
deposited  from  a  syrupy  solution  of  this  hydrate  are  in  the  form  of  highly  surbased 
oblong  prisms. 

Action  of  reagents  on  dambonite. — Dambonite  does  not  reduce  cupro-potassic 
tartrate,  is  not  subject  to  either  the  alcoholic  or  the  lactic  fermentation ;  in  contact 
with  hydrated  acids  it  is  attacked  even  in  the  cold ;  by  raising  the  temperature 
the  reaction  becomes  more  energetic,  and  at  100°  C.  (212°  F.),  in  presence  of 
hydriodic  acid,  or  fuming  hydrochloric  acid,  it  is  complete  in  half  an  hour.  It 
then  splits  up  in  a  remarkable  manner,  and  if  the  operation  be  performed  in  a 
close  vessel,  methyl  hydriodic  ethers  are  observed  to  form  in  the  liquid,  whilst  in 
the  acid  liquid  there  remains  in  solution  a  new  neutral  non- volatile  substance, 
with  a  saccharine  taste,  crystallising  very  well,  and  presenting  the  centesimal 
composition  of  a  dried  glucose,  Dambose. 

Chemical  constitution  of  dambonite. — The  production  of  dambose  indicates  the 
real  composition  of  dambonite,  which  cannot  therefore  be  considered,  like  the 
greater  number  of  saccharine  bodies,  as  a  polytomic  alcohol,  but  as  a  methylic 
ether  splitting  up  according  to  the  formula 

CsHA  +  HI.  =  C6H606  +  C2H3I 

Dambonite. 

C8H806  +  HC1.  =  C6H(iO6  +  C2H3C1. 

The  author  resumes  his  first  work :  "  The  milky  juice  of  the  vines  secreting 
Gaboon  rubber  contains  a  volatile  saccharine  principle  different  in  its  behaviour 
and  composition  from  the  saccharine  bodies  hitherto  studied.  This  principle, 
dambonite,  may  be  regarded  as  the  methylic  ether  of  a  second  saccharine  principle, 
dambose ;  and  this  latter,  noted  for  its  great  stability,  evidently  belongs  to  the 
family  of  glucoses,  and  may,  like  them,  play  the  role  of  a  polytomic  alcohol." 

Borneo  dambose  and  Meteza  dambose  (bornesite  matezite). — It  is  not  necessary 
to  follow  M.  Girard  in  the  continuation  of  his  researches,  by  which  he  was  enabled 
to  announce  to  the  Academy  of  Sciences  in  1871  bornesite  extracted  from  the 
Urceolas  of  the  Malays,  and  in  1873  matezite  extracted  from  a  Madagascar  rubber 
called  by  the  natives  Meteza  roritina.  These  two  products  are  likewise  peculiar 
methylic  ethers  of  damboses,  which  the  author  has  styled  Borneo  dambose  and 
Mateza  dambose.  His  final  conclusions  are — 

"In  comparing  the  three  products,"  he  says,  "I  have  been  able  to 
establish  in  a  decided  manner  the  non-identity  of  the  three  damboses  formed  1  >  y 
their  splitting  up  in  presence  of  hydracids,  and  I  have  been  able  to  determine 
amongst  their  physical  properties  relations  which,  coupled  with  their  chemical 
properties,  justify  their  being  considered  as  the  result  of  the  progressively  increas- 
ing condensation  of  the  same  molecule  C6H6O6." 


PROPERTIES   OF   LATEX   AND    INDIARUBBER 


117 


Tile    tollouing    is    the    residue    o|     my    ol  ^, -|  \  all  o|  [-,    U|K>11    this 

Tvr.i.i:    \.\II.      SIIOUIN..   ('HIMI.  \\     \M,    I'm  -i.  \i    C/ONSTAim   • 
OF  TMK    I)\MU..-K   '\'\  ii 


Sui-i 

K"i  inula. 

M.-liinx  I'-ini. 

Danibonite      . 
Bornesite 

«'JI 
'     ,H  .A,- 

205°C. 
200°C. 

0 
+  32°. 

lUtesite, 

1     IUOW. 

181°C. 

+  70°. 

haiiiliose 
KOMI.-.)  duiiil'use 

'     ",;'>„ 
(',..11,  .(),.. 

2ia°a 

•_"JO°C. 

0 
0 

M.it.vti  <l;uiil»osc 

<',Ji,,.0|H. 

W5°C. 

+  6°. 

Tin-  work  of  (Jirard,  already  \.-ry  interesting  in  it-elf  from  tli.-  |N.int  of  \ie\v  of 
the  discovery  of  a  new  natural  sugar,  is  of  still  greater  interest  to  n-  by  tin- 
that  it  enables  us  to  give  the  most  plausible  explanation  of'  tin-  din'eivncr  in  the 
behaviour  of  the  rubbers  which  come  from  tin-  milk  of  the  //er»v*/.<,  compared  \sith 
that  extracted,  as  we  have  just  said,  from  other  American,  African,  and 
Au>trala-ian  8OUTC6& 

If  the  authors  do  not  quite  agree  with  (iirard,  in  so  tar  that  they  do  not 
admit  the  pre -existence  of  dombonite  in  the  fresh  latex  yielding  tin-  dill- 
rubbi'rs  which  he  has  examined,  it  is  none  the  less  true  that  tln-M-  jnii-e>  .-.•ntain  a 
peciiliai-  amylaceous  substance,  to  which  Undoubtedly  must  l>e  attributed  tin- 
baneful  influence  exerted  on  the  rubbers  which  are  extracted  from  them,  ami  \\f 
are  thus  enabled  to  understand  how  it  is  that  it  is  necessary  to  treat  these  jiiic«->  in 
quite  a  special  manner  if  it  be  desired  to  produce  a  rubl>er  ]>crfectly  acceptable  to 
commerce  and  from  which  industry  may  draw  every  jtossiblr  ad\anta^e.  It  i>  1>\ 
the  simultaneous  and  rational  application  of  heat — natural  or  artificial — and 
sodium  chloride,  and  by  the  complete  elimination  of  the  serum  re-idiic  from  the 
coagulated  rubber,  and  finally  by  doing  it  up  into  very  attenuated  ball*  or  spindles, 
that  the  natural  defects  of  these  rubbers  may  be  minimised,  which,  when  \sell 
prepared,  quickly  acquire  a  greater  value,  and  which  are  destined  to  play  a  more 
and  more  important  role  in  the  rubber  industry.  Sodium  chloride  might  be  \er\ 
advantageously  replaced,  in  the  case  of  these  varieties,  by  ammonium  fluoride,  the 
mo>t  powerful  antiseptic  for  stopping  the  putrid  fermentation  of  amylaceous  bodies, 
if  its  cost  did  not  tend  to  debar  its  use. 

Action*  nf  i;>t<i<ntx  on  1 1  <  veo,  latex — 1.  Action  <>f  n'>tt'i\  /rAW/o/.  <///</  tf/tcr. — 
The  milky  juice  is  not  sensibly  altered  by  the  addition  of  a  small  quantity  of 
water.  In  greater  proj>ortion  the  water  hastens  the  separation  of  the  rubber 
globulites  and  accelerate  the  formation  of  the  creamy  layer  which  contains  the 
caoutchouc.  Alcohol  and  ether  have  an  analogous  action.  Both  of  these  emul- 
juices  mix  readily  with  water,  alcohol,  and  pyroxylic  spirit,  although  they  do  not 
become  at  all  cleaner.2 

'_'.  J «•///.<.  Mineral  as  well  as  organic  acids,  in  small  proportion*,  determine  the 
more  energetic  grouping  of  the  suspended  globulites,  and  thus  hasten  coagulation. 

3.  Concentrated  *ti!j>Iiin-!<-  n>-l<l  causes  a  great  change  in  the  latex  —  which, 
however,  does  not  concern  us  for  the  moment. 

4-.  Co/i/  riHHriifi-iit'-'f  niti'ir  in-ill  is  without  action  on  the  globulites  themsehc-, 
but  it  decomposes  the  serum,  in  which  it  produces  a  gelatinous  precipitate.  Nitric 
acid  converts  it  into  a  red  curdy  magma.3 

5.    Concentrated  acetic  acid  (ijlncinl)  acts   very  peculiarly  on  the  globulit 
suspension  in  the  latex;  at  the  same  time  it  hastens  their  amalgamation,  causing 
each  of  them  to  swell  in  a  very  energetic  manner,  whilst  at  the  sain*1    time  they 
maintain  their  primitive  texture. 

1  ?C8H806  as  on  p.  116.     All  the  formulae  and  equations  quoted  fronVGirard  are  evidently 
old  notations. — Tu. 

2  Ure,  in  re  juices,  footnote,  pp.  111-112.  3  Ure,  loc.  fit. 


118  INDIARUBBER 

6.  Alkalies. — In   contradistinction    to    acids,  alkalies — especially   ammonia- 
hinder  the  globulites  from  coagulating,  and  thus  contribute  to  their  remaining  in 
an  infinitely  divided  state  in  the  midst  of  the  liquid  vehicle.     They  develop  an 
amber  tint  in  this  liquid,  which  gradually  becomes  more  and  more  transparent, 
whilst  the  latescent  appearance  tends  more  and  more  to  disappear.     The  property 
of  ammonia  of  maintaining  the  rubber  globulites  in  a  great  state  of  division  or 
emulsion   has    often  been   taken  advantage  of   for    preserving  the  latex,  and   its 
conveyance  in   the  natural   condition   to  great   distances.     A    7  to  8    per   cent, 
solution  of  ammonia  has  so  been  used  with  success. 

7.  Salts — Alum — Chloride  of  sodium — Fluoride  of  ammonia.— Salts  in  general, 
but  especially  antiseptic  salts,  such  as  alum,  sodium  chloride,  ammonium  fluoride, 
are  powerful  coagulants  of  the  different   species  of   latex.     They  would   appear, 
however,  to  have  a  more  energetic  action  on  juices  of   rubber   trees  other   than 
Hevea,  on  which  their  action  is  less  marked. 

Halogens  (chlorine,  bromine,  iodine] — Sulphur. — Chlorine,  bromine,  and  iodine 
must  more  especially  occupy  our  attention.  There  need  be  no  question  as 
to  sulphur.  Its  insolubility  in  ordinary  vehicles  capable  of  being  mixed  with  the 
latex,  and  its  non-volatility  at  the  ordinary  temperature,  are  bound  to  render  its 
action  inefficacious  in  the  liquid  media.  But  it  is  not  so  with  chlorine,  iodine,  and 
bromine.  These  three  bodies,  being  soluble  in  water  and  alcohol  at  ordinary 
temperatures,  can  be  brought  in  contact  with  the  proximate  principles  of  the  latex, 
and  it  is  easy  to  determine  the  action  which  they  exert  thereon — especially  on  the 
rubber  globulites — which  interest  us  more  definitely  and  particularly.  Under 
their  influence  these  globulites  turn  brown,  agglomerate  rapidly  into  a  very  ductile, 
unique  mass,  which  may  be  drawn  out  into  long  filaments.  Their  presence  has 
therefore  evidently  modified  the  chemical  composition  of  the  gummy  matter  from 
that  which  it  possessed  in  the  midst  of  the  laticiferous  mass :  if  the  substance 
becomes  viscous,  that  must  be  attributed  to  an  excess  of  reagent  having  been 
added. 

Action  of  solvents.  —  The  latex  will  not  mix  with  caoutchine  or  with 
petroleum  naphtha,  but  remains  at  the  bottom  of  these  liquids  as  distinct  as 
mercury  does  from  water. 

Action  of  halogens  on  the  rubber  itself. — The  action  of  halogens  upon  rubber 
becomes  more  energetic  when  it  is  freed  from  all  the  other  bodies  constituting  the 
latex,  the  effects  produced  have  a  certain  analogy  with  the  very  singular  action  of 
sulphur  when  it  is  put  in  contact  with  rubber,  especially  if  heat  and  extreme 
division  aid  the  metalloid  to  act  more  energetically. 

Properties  of  indiarubber — Preliminary  observations. — Whilst  studying  the 
proximate  constituents  of  Hevea  latex,  we  examined  each  summarily,  reserving  to 
the  end  the  essential  principle,  the  ingredient  called  caoutchouc.  It  is  indispens- 
able to  examine  a  perfectly  determined  and  well-defined  body,  because,  as  already 
mentioned,  a  certain  sample  of  rubber  produced  from  Hevea  latex  possesses 
corresponding  properties,  which  another  that  has  been  prepared  with  less  care 
does  not  possess.  The  rubber,  the  structure  and  different  properties  of  which  is 
about  to  be  considered,  is  that  furnished  by  the  typical  latex  adopted  above,  freed 
from  the  other  proximate  constituents,  amongst  which  it  was  present  in  the  latex 
by  the  smoking  process,  to  the  exclusion  of  every  other  process.  To  examine  and 
determine  its  chemical  composition  and  its  formula,  we  shall  submit  it  to  the 
treatment  adopted  by  Payen  to  obtain  a  caoutchouc  absolutely  pure  and  exempt 
from  all  foreign  matter. 

Preparation  of  chemically  pure  rubber. — The  rubber  known  as  Para  prima,  is 
cut  up  into  very  thin  fragments  by  means  of  a  cutting  tool,  and  is  then  subjected 
to  prolonged  and  uninterrupted  desiccation  in  a  drying  oven.  Freed  in  this  way 
from  all  interstitial  moisture,  the  substance  is  digested  with  five  to  six  times  its 
weight  of  anhydrous  carbon  disulphide.  When  it  has  assumed  a  gelatinous, 
opalescent  consistency,  6  per  cent,  of  absolute  alcohol  is  added,  which  causes  the 
solution  to  become  clear  and  fluid.  Thinned  down  in  this  way,  the  rubber  is 


PROPERTIES   OF   LATEX   AND    INDIARUBBER  119 

tilt  r  red    through  a  plug  of  asbestos,  and   run  into  twice  ite  weight  of   absolute 

alcohol.      The  ilix>,,|\,-i|    substance    i-  immediately  pivrij.itated  to  the  liottom 

ve^el,  \\liiUt  the  rarlx.n   dUulphide  disM,|\ed  in  tin-   alcohol  float*  ul»o\- 

standing  t'l.r  a  siillicieiitly  long   tinn-,  the  li<|iii<{  is  decanted.  and  tin-  rr*uliu*  u.i-h-.l 

ivj.ratr.lly  \\ith    absolute   aleohnl  until    thr  latter  leavi  i>lui-<.n  9V*pCN 

Thr    precipitate  is    collected,  i|rir.|    at    7"'     <  '.   £158      I'.  I.  ami    tin-   treatment     H; 

as   before.      (  'lirinirally    purr   raiiiitrliMiir    i>    finally   obtained   of    ilnisilv    0*9! 

II     (  '.  (57*2     I1'.),  tin-  rlrmriitary  anal\>i-  ..I'  \\liirh  Ln\,^  thr  foll..\\  in-  iv-ti, 


TM-.I.I:    \\lll.       IIIIMMI:    AKALT8I8  OI    CHUOCALL1     PUM    |'\I:A    1'iclMA 

l\|.|  MM  r.r.i  i:. 


iit. 


1C 


It-  rhrinical  formula  therefore  convsp.»mls  to  the  atomic  formula  of  (    II. 
(  i.  Williams1  analysis  is  as  follows  : — * 

TABU:  XXIV. — ULTIMATE  ANALYSIS  OF  RUBBER  (G.   \\IIIIA 


Per  cent. 


Carbon  ...........  86'1 

Hydrogen      ..........  11  '3 


07 
Asli       .  .........  0-9 

99-0 


Williams  cannot  therefore  have  operated  on  a  sufficiently  pure  sample,  and,  with 
this  reservation,  his  analysis  only  confirms  the  above  results. 

Afl  to  the  chlorides  and  sulphides  mentioned  by  A.  CJirard  and  Cloe/,  tlu 
have  their  origin  in  an  impure  sample. 

TABLE  XXV.— ULTIMATE  ANAI.YM>  <»    /•' <-rs  RUBBKK  (\I.KI\M 

I'.  1    c«'llt. 


Carbon . 

Hydrogen 

Oxygen 


99*99 


At  Adriani  usrd  a  substance  which  had  remained  >everal  months  above 
sulphuric  acid,  and  had  become  quite  hard,  it  can  only  be  inferred  that  the  rubber 
had  become  altered,  and  that  his  results  in  n«»  way  invalidate  those  given  al 

CoHxtffnfion'1/  /nrnui/a^  —  According  to  the  distillation  products  of  juire 
rubber,  as  we  shall  see  further  on,  it  will  be  convenient  to  adopt  the  definite 
atomic  formula  of  C5HS,  and  thus  to  consider  rubber  as  a  mixture  of 
polymeric  carbides  of  high  equivalents,  derived  from  a  fundamental  carbide  C5Hg 
of  the  class  of  trrjii.es  or  polyterpenes  \\hicli,  under  the  influence  of  atmospheric 


120 


INDIARUBBER 


oxygen  and  light,  partially  change  into  resinous  bodies,  and  thus  yield  tin-  different 
rubbers  of  commerce. 

Density. — The  density  of  rubber  is  generally  given  as  varying  between  0'919 
and  G'942,  and  sometimes  even  the  figure  of  0'966,  as,  for  example,  by  Adriani, 
who  especially  studied  the  Ficus  rubbers.  These  variations  show  (1)  a  very  con- 
siderable difference  between  rubbers  from  different  sources,  but  they  also  demon- 
strate very  forcibly  how  necessary  it  is  to  use  as  a  starting-point  only  one  and  the 
same  type  always  taken  under  identical  conditions.  Chemically  pure  rubber, 
prepared  by  Faraday's  method  from  Hevea  latex,  has  a  density  of  0"919  at  the 
temperature  of  14°  C.  (57  "2  F.),  and  commercial  Para  prima  at  the  same 
temperature  has  a  density  of  0'930.  Under  the  same  conditions,  all  the  other 
varieties  have  a  greater  density,  which  is  due  not  only  to  a  higher  percentage  of 
water,  but  also,  more  or  less,  to  the  organic  matter  with  which  this  water  is  charged, 
and  which  helps  to  modify  the  resultant  densities,  as  well  as  to  the  juxtaposition 
to  the  pure  rubber  of  a  more  or  less  altered  substance  said  to  be  oxidised. 

Density  of  the  commercially  purified  rubber. — Chapel  and  Bouquillon  made  a 
series  of  experiments  upon  this  point  to  determine  the  specific  gravity  of  different 
rubbers  used  in  manufacture  after  these  rubbers  have  been  sliced,  purified,  and 
dried — namely,  when  ready  to  be  utilised.  These  experiments,  made  at  the 
temperature  of  16°  C.  (60 '8°  F.),  by  aid  of  a  very  sensitive  hydrostatic  balance, 
gave  the  following  results  : — 

TABLE  XXVI. — DENSITY  OF  COMMERCIALLY  PURE  RUBBERS  READY  FOR  VSK. 


Source  of  Rubber. 

Density  at 
160°  C. 

Source  of  Rubber. 

Density  at 
160°  C. 

(60  -8°  F.). 

(60-8°  F.). 

Para 

0-914 

Sierra  Leone  . 

0-923 

Colombia  . 

0-915 

Senegal  . 

0-929 

Madagascar 
Borneo 

0-915 
0-916 

West  India  Scraps 
Mozambique  . 

0-935 
0-939 

Sernamby  . 

0-918 

Ceara     . 

0-958 

Balls  and  Negroheads 

0-920 

Assam    . 

0-967 

As  rubber  contracts  and  expands,  its  density  varies  with  the  temperature.  The 
specific  gravity  of  the  best  Para  taken  in  dilute  alcohol  is  0'914567,  of  best  Assam 
0-942972,  of  best  Singapore  0*93650,  of  best  Penang  0'91978. 

Physical  properties. — The  physical  properties  of  rubber  cannot  be  examined 
on  a  chemically  pure  sample,  prepared  like  that  used  for  the  study  of  its  elementary 
composition  and  its  chemical  formula.  Each  time  it  is  dissolved  rubber  loses  a 
more  or  less  considerable  portion  of  its  essential  physical  properties,  and  it  is 
necessary,  in  the  examination  which  follows,  to  resort  to  another  process  in  order 
to  obtain  as  pure  a  sample  as  possible.  Faraday's  method  appears  the  most 
simple.  It  leaves  intact,  as  far  as  possible,  the  properties  of  so  easily  .altered  a 
substance. 

Preparation  of  commercially  pure  Hevea  rubber. — To  prepare  the  rubber 
required  for  examination,  the  juice  of  the  Hevea  is  diluted  as  soon  as  collected 
with  four  times  its  volume  of  water,  and  the  mixture  allowed  to  stand,  by  itself,  in 
a  cool  place,  sheltered  from  sunlight,  for  twenty-four  hours.  The  rubber  separates 
as  a  whitish  cream,  lighter  than  the  serum.  The  liquid  portion,  syphoned  off  from 
underneath,  is  replaced  by  very  cold  distilled  water,  acidulated  with  hydrochloric 
acid,  and  "  sharpened  "  with  a  little  pure  sodium  chloride,  then  the  washings  are 
continued  with  distilled  water  alone,  until  the  wash  water  no  longer  contains  a 
trace  of  any  foreign  bodies,  and  comes  away  perfectly  limpid.  The  mass,  con- 
sisting of  a  multitude  of  small  agglomerated  fibres,  is  then  collected.  Pressure 
causes  water  to  flow  from  it,  provided  that  the  operation  be  conducted  at  a 


PROPERTIES   OF   LATEX  AND   INDIARUBBER  li'l 

temperature  \\hich  doefl  not  exceed  14°  C.  (57*2°  F.).     Tin-  pure  mass  so  ob 

ia  completely  dried  on  pieces  of  porcelain  < -haded  tr«iu  the  son  a  v*ible) 

to  a   white,    opaque,    elastic    pellicle,    \\liidi,    when    ci.mplrtely   dried    in    daikn.-, 
eventually  becomes  diaphanous ;   it  ivniuins  colourless  with  a  slight  .HII|HT  tint,  and 

:l  tin-  properties  of  the  best  kinds  of  c lercial  ml. I,,  r.      h  is  under  thi- 

form  that  thepiv-enl  .-tud\  •  •!'  t  In-  serial  physical  proper!  ie-  ,,1  nil. her  \\ill  U-  made. 
////./•//-//  <t riK-t a r> .  In  tin-  diaphanous  condition,  rubl»er,  examined  under 
tlie  microscope  (an  extremely  dilliciilt  and  delicate  operation,  the  -ub-tance.  o\\in-r 
to  it-  elasticity,  doubling  up  under  the  pressure  ,,f  the  microtome,  and  only  allotting 
a  -lice  thin  enough  to  he  examined  l.ein^  obtained  \\ith  difficulty),  does  not 
exhihit  perceptible  vacuities  (Wie-ner).  Hut  I'ayen,  \\h"  examined  under  .similar 
condition-  \er\  thin  lamella-  of  1'ara  rubber  \\hil-t  -till  white  and  opaque,  oh 
numerous  irregularly  rounded  pores  communicating  with  each  other,  which  expand 
even  under  the  capillary  action  of  liquid  and  gases,  which  do  not  exert  a  so|\,-nt 
action  on  the  substance.  When  the  permeability  of  rubber  is  de-criln-d,  \\hut  applica- 
tions science  has  been  able  to  make  of  this  j)orous  structure,  which  i-  it-  natural 
structure,  the  diaphanous  and  anhydrous  structure  examined  by  Wiesner  only  Ix-in^ 
an  « -x. •« 'pi  ion  which  is  occasionally  met  with  in  Ceara  and  Madagascar  rubbei 

be  eviilellt. 

Colour. — Rubber,  prepared  by  Faraday's  method,  from  fresh  Hevea  milk, 
shaded  from  -unli^ht,  and  at  a  temperature  not  exceeding  1  1  ( '.  (">7 ••_'  F.),  is 
diaphanoafl  and  colourless  when  it  has  been  sufficiently  dried,  and  presents  a  more 
or  less  opaque  milky  aspect  when  dried  at  a  low  temperature.  The  \\hite.  ojjaque 
api>earance  observable  on  the  inside  of  the  section  of  freshly-cut,  recently-prepared 
rubber  is  therefore  a  characteristic  sign  of  a  greater  or  less  percentage  of  moisture, 
which  varies  in  Para  prirna  from  10  to  20  per  cent.;  but  in  certain  other  varieties, 
owing  to  defective  preparation,  the  moisture  may  exceed  50  per  cent. 

Colour  of  smoked  rubber. — This  same  rubber  recently  prepared,  but  by  the 
smoking  process — owing  to  coagulation  by  artificial  heat — is  amber  brown,  and 
slightly  opaque.  Its  coloration  is  due  to  empyreumatic  bodies,  and  to  carbon 
in  an  extreme  state  of  division,  incorporated  by  the  smoking. 

Colour  liable  tochani/c  with  age. — The  colour  of  rubber,  however  prepared,  has 
a  tendency  to  change  under  the  influence  of  light  and  atmospheric  oxygen. 
Hut  as  not  only  the  colour  is  altered,  but  also  the  chemical  coinjM»sition  "f  the 
substance  itself,  the  alteration  is  merely  notified  here,  and  will  again  be  referred 
to  under  the  action  of  reagents  on  rubber. 

Smell  and  taste. — Pure  rubber,  whether  prepared  by  Faraday's  process  or  by 
chemical  purification  of  commercial  brands,  is  by  itself  inodorous  and  insipid.  If 
sometimes  commercial  varieties  acquire  the  smell  and  the  taste  of  methyleue,  of 
old  rum, — if,  again,  it  contracts  a  foetid  smell,  which  is  often  the  case  with 
African  rubbers, — it  is  owing  to  more  or  less  defective  preparation  and  insutHeient 
elimination  of  the  putrescible  bodies  which  accomjuiny  it  as  it  issues  as  latex  from 
the  producing  plant. 

Conduction  of  /teat  and  electieity. — Indiarubber  is  generally  a  bad  conductor  of 
heat  and  electricity.  But  each  different  brand  possesses  this  negative  property  to 
a  more  or  less  pronounced  degree,  and  it  is  certainly  //  '  -ibU-r  \\hioh  poaaeaees 
it  in  the  highest  degree.  The  degree  of  purity  still  further  exalts  it  :  whilst  the 
change  which  the  rubber  undergoes  under  the  action  of  oxygen,  of  ozone,  a-  veil 
as  light,  sometimes  diminishes  it  to  such  a  point  that  a  rubber  so  altered  will  conduct 
very  well  both  heat  and  electricity.  It  was  thought  that  use  could  be  made  <.f 
a  covering  of  indiarubtor,  lined  with  e-parto.  to  preserve  the  steam  pi]  • 
engines  against  too  much  loss  of  caloric.  Experience  proved  that  the  envelope  rapidly 
lost  its  protective  properties.  The  same  thing  occurs  in  the  use  of  raw  rubber 
in  electrical  apparatus  :  excellent  at  first,  they  rapidly  lose  their  dielectric  value. 

Permeability—  PayetC*  esj*  /•///„///>•  ///  1852.— (1)  "  Art  ion  or  »,,>•  -The 
porosity  of  rubber  explains  its  easy  permeability  by  different  liquids  which 
have  no  appreciable  chemical  action  on  it.  Water  affords  one  of  the  most 


122  INDIARUBBER 

interesting  instances :  thin  cuttings  of  dry  rubber,  one  lot  from  a  white, 
rubber,  the  other  in  sheets  or  foil,  slightly  yellowish  and  translucid  (that  is  to  say, 
the  one  more  anhydrous  than  the  other) ;  immersed  for  thirty  days  in  water,  the 
former  absorbed  187  per  cent,  of  it,  and  the  latter  2  6 '4  per  cent.  The  first  lot 
increased  in  length  by  5  and  in  volume  by  15*75  percent.  Thick  slux-ts  of 
indiarubber  would  eventually  be  similarly  penetrated,  and  a  considerable  time  Avill 
be  required  to  completely  eliminate  it,  because  the  superficial  layers,  being  the  first 
to  dry,  contract  their  pores  considerably,  and  thus  hinder  the  final  desiccation  of 
the  central  points.  The  mechanical  hydration  ought  to  be  taken  into  account  in 
commercial  transactions,  since,  by  this  fact  alone,  the  real  value  may  be  diminished 
from  18  to  26  per  cent.,  and  a  white  shade  is  only  the  sign  of  a  purely  illusory 
superior  quality.  Moreover^,  the  presence  of  water  hinders  the  penetration  of 
the  liquids  used  in  industry  to  dissolve  or  swell  the  rubber,  and  diminishes  its 
tenacity  and  its  ductility.1  The  apparent  wrhiteness  and  opacity  are  generally 
due  to  moisture.  Complete  drying  causes  the  amber  coloration  and  translucency 
to  appear. 

(2)  Action  of  alcohol. — Anhydrous  alcohol  easily  penetrates  rubber,  more 
especially  at  a  temperature  of  78°  C.  (172 '4°  F.).  Dry,  thin,  translucent  slices, 
heated  repeatedly  in  the  liquid  during  eight  days,  became  opaque,  their  length 
being  augmented  by  TJJ^,  and  their  volume  by  TJ^j.  Their  adhesive  properties 
increase  remarkably,  even  in  the  midst  of  the  alcohol.  Their  weight  incren 
in  the  proportion  of  100  to  118*6,  and,  nevertheless,  they  cede  to  that  liquid 
Tzrero~  °f  a  fusible,  greasy,  fawn-coloured  substance.  The  slices,  after  the  evapora- 
tion of  the  alcohol,  were  more  transparent  and  more  adherent  to  each  other  than 
before  this  treatment.  As  far  as  their  tenacity  was  concerned,  it  was  appreciably 
diminished." 

Dialysing  power. — The  permeability  of  rubber  also  applies  to  certain  gases, 
without  solvent  action  upon  it.  These  gases  traverse  it  with  greater  or  less  facility, 
according  to  the  state  of  dilatation  of  the  rubber  and  the  pressure  of  the  gas. 
Thus  Graham,  in  1866,  used  thin  sheets  of  rubber  to  separate  gases,  liquefying 
them  in  the  passage.  'If  a  vacuum  be  made,  either  in  a  small  satchel  of  varnished 
silk  filled  with  thick  felt,  or  in  a  small  balloon  filled  with  sawdust  (the  felt  and  the 
sawdust  being  intended  to  support  the  thin  envelope  of  the  caoutchoucised  silk  or 
of  the  balloon),  the  pellicle  of  rubber  allows  a  mixture  of  gases  to  pass,  containing 
0'416  of  oxygen,  and  capable  of  inflaming  incandescent  wood,  whilst  air  only 
contains  0*21  of  oxygen.  The  caoutchouc  partition  therefore  retains  half  the 
nitrogen,  and  allows  the  other  half  to  pass  along  with  the  whole  of  the  oxygen. 
This  dialysed  air  therefore  is  a  gas,  exactly  intermediate  between  air  and  pure 
oxygen,  so  far  as  the  question  of  combustion  is  concerned.  Graham's  observations 
were  confirmed  by  Peyron,  who  found  that  atmospheric  air,  hydrogen,  nitrous 
oxide,  carbonic  acid,  are  easily  dialysed  through  natural  caoutchouc.  Aronstein 
and  Sirks  likewise  studied  this  property,  in  so  far  as  the  action  of  the  rubber  on 
carbonic  acid  and  protoxide  of  nitrogen  is  concerned.  They  rendered  caoutchouc 
impermeable  to  gas,  by  digesting  it  for  two  hours  in  linseed  oil  or  in  a  mixture  of 
asphaltum  dissolved  in  tar.  Finally,  Graham  observed  that  different  gases  traverse 
the  pores  of  the  rubber  with  greater  or  less  rapidity,  or,  in  other  words,  that  several 
gases  being  in  the  presence  of  each  other,  the  volume  of  each  which  passed  through 
was  variable  in  the  same  units  of  time. 

N  =  l;  CO  =  M13;  O  =  2-556;  H  =  3'500;  CO2=13'584; 

CO2  is  thus  soluble  in  thick  sheet  rubber  or  tubing;  they  absorb  this  gas  and 
swell  to  ten  times  their  original  volume,  then,  in  course  of  time,  the  gas  is  eliminated 
and  the  rubber  resumes  its  original  volume. 

Polarising  power. — Wiesner,  who  analysed  numerous  varieties  of  rubber, 
states  that  all  the  species  examined  by  him,  .without  exception,  allow  light  to  pass  in 

1  The  water  thus  absorbed  being  eliminated,  moreover,  but  very  slowly,  it  may  be  conceived 
that  this  is  a  frequent  cause  of  the  decay  of  those  rubbers  prepared  by  a  too  hasty  curing  of 
the  latex. 


PROPERTIES  OF    LATEX   AND   INDIARUBBER  123 


magnificent  prismatic  colours  between  tin-  Ni<»l-  p  i 

Tlii-    phenomenon,    Nery    mark'-d    with    Lrrea>y    ml'l"i,    \\.is    foga  SO   \Mth    |-H.-.tlv 
dry  pieces.      The  etle.-t   <ii    pol.trisition   i>  U'tter  and   more  decidedly  ohown  i; 
rubber  membrane  IK-  strongly  comprened  between  tun'object-gUneM.     I'.ut  the  plu\ 

of  colours  of  tliin  films  po^-iMy  inters 

('»/,,/,,:  x*ll>iliti/.  —  r.lo-SMin    >tatrs    lliat    a    ml  .....  1    nil.!..-!    ••! 

submitted   to  a   blow  of    1(H)   tons   diminishes    1O   |n-r  ccilt.    in   Volume.        This   pp.  i 
of  natural  caoutchouc  has  I.een  but    little    -tudied  l.y  Kjieciali  .   w  IIOM-  whole 

attention  in  this   respect    has   been    brought    to   bear  on    \ulcani>ed   andinin<i.i 
rubber.       The  subject     will    therefore    U-    reverted    to    in    more    detail     when   the  com 
possibility  of  vulcaiii-ed  rubber  i>  examined. 

/•Ji-jHtHXinit    <nnl   ••nntfti-liuit.-  -  liiil)lHT   easily    c\|»ainU    \\.ln-n    lu-atnl,    and    cold 
contracts  it  to  a  corresponding  extent.      Ure,  experimenting  on  n;  le<l  down 

until  it  had  lost   all   its  elasticity,  found  it  to  have  a  density  of  <)•'.»  r-  7       I:    ^i^ht 
hack  to  the  tein|>erat  lire  of  35°  (.'.    (05°   F.),  that  is  to  say,  to   the   jM.int  when  tin- 
sul)stance  regained  its  normal  elasticity,  its  density  had  sunk  to  0'\)'2^J.      1'nder  th- 
same  volume,  the  expansion  and  contraction  confirmed  the>r  \ariations  in  den-it\. 
The   following  point   is  worthy  of  notice;  it  is  one,  \\hich  has  been  taken  great 
advantage  of  l»y  the  rul>l»er  thread  industry:  if  natural  rubber  be  heated  to  1  I  .V  C. 
(I'.'tt)0  F.)  and  then  cooled,  it  loses  its  contractility  during  this  transition,  >\hil>t  all 
its  i.ther  properties  remain  intact.     A.  Gerard  utilised  this  property  to  obtain  thread 
of  extreme  tenuity.     Having  submitted  threads  which  had  been  >tivtrh<d  t-. 
times  their  length  to  a  temperature  of   115°  C.  (239°  F.),  this  e\trn-i«.n  Kecamr 
permanent  by  sudden  cooling,  and  the  threads  then   lent    themselves  to  a  second 
similar    extension.      15y   relating    this   experiment   five    times    in    succession,    the 
primitive  length    was  increased  in  the  ratio  of  1   to  IGG^"*.     The  dian 
diminished   in  proportion    to   this   enormous   elongation,    and    the    threads    v. 
obtained   in  a  degree  of  fineness    hitherto   unknown.      With  expansion    and 
traction  two  other  properties  of  indiarubber  are  closely  connected  : 

A'A/x/  //•////  mi'/  '  ••(,  ,t*il,ility.  —  Of  all  known  solid  bodies,  rubber  has  tin- 
greatest  degree  of  elasticity,  i.e.  the  property  of  being  but  little  capable  in  tin- 
natural  state  of  preserving  in  a  permanent  manner  the  changes  of  shape  \\hich  a 
mechanical  force  may  impart  to  it.  A  ball  cut  out  of  a  block  of  Para  pr  im>t. 
falling  with  only  the  velocity  imparted  to  it  by  its  own  weight,  rebounds  from  the 
ground,  and  rises  to  a  height  varying  between  one-half  and  three  quarters  of  the 
course  tra  \ersed  in  its  fall.  From  the  summit  which  it  reaches  it  falls  again,  to 
rise  once  more,  and  it  continues  thus  to  rebound  until,  the  oscillations  gi-tting  more 
and  more  reduced,  on  account  of  the  using  up  of  the  etl'ort  imparted  to  it  in  over 
coming  the  resistance  of  the  friction  of  the  ground,  it  tinall\  rtO]  I,  lint,  besides 
»A/x//r////,  rubber  possesses  the  property  of  r/7r//x//,//,V//%  /.,.  of  supporting  an 
elongation  which,  in  a  band  of  natural  J'<i,-'i  /.ri/nn.  may  amount  t<»  five  time 
primitive  length  without  breaking,  then  of  regaining  very  rapidly,  if  left  to  it-elf. 
its  primitive  dimensions,  unless  a  new  force  intervene,  «?.//.  alteration  in  temperature. 
Gerard  observed  that  fibres  elongated  to  tin-  extent  of  six  times  their  original  rfn 
could  again  be  elongated  to  the  same  extent  if  expo-ed  to  a  temperature  of 
108°  C.  (226*2  l\).  This  extensibility  may  be  brought  into  play  in  any  direction 
with  the  same  facility,  and  rubber  may  be  temporarily  deprived  of  its  ela<ti<  ity  : 
if,  for  example,  after  having  strongly  stretched  a  band  of  this  substance,  it  U- 
rapidly  cooled,  it  loses  its  elasticity,  and  may  remain  stretched  indefinitely  without 
recovering  it.  It  suffices  to  moisten  this  band  and  to  evaporate  the  water  b\ 
agitating  the  air. 

The  rubber  soon  regains  its  elasticity  if  it  be  >ul>j«cted  to  a  temperature  ,,f 
4-  2:T  C.  (71'6°  F.).  But  if  it  be  deprived  of  its  latent  heat  by  compression,  it  i 
be  exposed  even  to  26°  and  27°  C.  (78'8°  and  80'6°F.)  during  several  weeks  with- 
out reverting  to  its  normal  condition.  When  successive  portions  of  indiarubber 
thread,  deprived  of  its  elasticity,  are  pinched  with  the  fingers,  a  strong  contract  i  I. 
force  operates  exclusively  in  these  points,  without  the  untouched  j^ortions  altering 


124  INDIARUBBER 

their  texture;  the  thread  then  assumes  the  appearance  of  a  string  with  knots,  and 
it  can  preserve  this  condition  for  an  indefinite  time  if  it  be  not  manipulated  and  if 
it  be  kept  at  a  moderate  temperature.  The  different  intervals  between  the  swellings 
do  not  change  their  properties,  and  thus  show  that  the  latent  heat  has  no  tendency 
to  diffuse  itself  or  to  equalise  itself  in  the  mass.  If  an  indiarubber  band,  deprived 
of  its  elasticity,  be  held  in  the  palm  of  the  hand,  a  slight  feeling  of  cold  is  produced, 
which  proceeds  from  the  rapid  absorption  of  heat  by  the  elastic  substance.  This 
peculiarity  is  eminently  characteristic  of  native  rubber,  and  is  hardly  observable 
in  that  prepared  by  one  of  the  following  methods: — (1)  Solution  in  spirits  of 
turpentine,  followed  by  drying.  (2)  The  mastication  of  the  raw  material  until  it 
forms  a  paste,  which  is  connected  into  sheets  between  two  heated  rolls.  Para 
rubber,  in  preference  to  any  other,  lends  itself  marvellously  to  this  experiment.  In 
1840,  another  method  was  adopted  to  deprive  rubber  of  its  elasticity.  In  the 
manufacture  of  elastic  fibres  it  is,  for  the  moment,  indispensable  that  the  threads 
lose  their  elasticity,  to  render  any  further  transformation  possible.  To  effect  this, 
it  is  wound  on  a  reel,  turned  rapidly  by  a  workman,  whilst  another  workman 
conducts  it  to  the  reel,  keeping  it  stretched  so  as  to  impart  to  it  in  the  stretching 
seven  or  eight  times  the  length  it  formerly  had.  The  threads  are  then  left  in  this 
state  of  tension  during  two  or  three  weeks,  after  which  they  are  so  far  deprived  of 
elasticity  as  to  be  capable  of  being  wrought  without  thereby  regaining  their  original 
length.  But  it  suffices  to  expose  them  to  heat,  even  to  rub  them  between  the 
palms  of  the  hand,  for  them  to  regain  their  primitive  elasticity.  Sudden,  abrupt 
extension  of  rubber  gives  rise  to  considerable  disengagement  of  heat,  and  Brockedon 
raised  the  temperature  of  30  grammes  of  water  2°C.  (3'6°F.)  in  fifteen  minutes  by 
collecting  the  heat  produced  by  the  abrupt  tension  of  an  indiarubber  thread. 
Elasticity,  which  may  be  augmented  by  a  slight  elevation  of  temperature,  dis- 
appears about  3°  to  4°C.  (5'4°  to  7*2°  F.)  above  +0°C.  (32°  F.),  below  which 
rubber  becomes  rigid  like  old  leather,  but  not  brittle ;  it  is  frozen,  and  does  not 
regain  its  original  properties  until  it  is  exposed  to  a  temperature  of  +40°C. 
(140°  F.),  or  unless  it  be  drawn  out  and  compressed  alternately. 

Adheswn. — At  the  ordinary  temperature  natural  rubber  is  soft  and  so  viscous 
that  two  sections  of  the  same  fragment  of  rubber,  when  placed  together  and  slightly 
pressed,  adhere  with  such  tenacity  that  they  appear  to  consist  of  a  single  compact 
piece.  This  property  increases  with  rise  of  temperature,  whilst  it  so  decreases  on 
cooling  that  below  0°  C.  (32°  F.)  the  cut  surfaces  no  longer  unite.  This  subject  will 
be  further  discussed  when  treating  on  the  action  of  reagents,  chiefly  sulphur,  on 
rubber. 

Here  terminates  the  brief  examination  of  the  physical  properties  of  raw  rubber.  It 
could  have  been  dwelt  upon  further,  the  subject  is  so  interesting  from  many  points 
of  view.  But  although  the  plan  of  this  treatise  does  not  allow  of  too  many 
details,  the  subject  will  again  be  reverted  to  on  several  occasions,  when  vulcanised 
rubber  is  discussed.  A  special  paragraph  could  also  have  been  allotted  to 
the  permeability  of  this  substance  to  liquids  and  gases,  but  this  property  belongs 
more  especially  to  the  chemical  part,  which  now  falls  to  be  discussed. 

Action  of  chemical  agents— Heat — How  rubber  melts. — Pure  as  well  as  com- 
mercial rubber,  when  heated,  becomes  gradually  more  pliant  and  elastic,  but  at 
about  145°  C.  (293°  F.)  its  state  of  existence  is  modified,  it  becomes  viscous,  it 
adheres  to  hard  bodies,  it  gives  way  and  loses  its  elasticity.  Towards  170°  to 
180°  C.  (338°  to  356°  F.)  it  finally  melts  into  a  thick  liquid,  very  similar  to  molasses, 
and  does  not  regain  its  primitive  properties  until  after  a  very  long  time,  and  then 
only  but  partially  and  in  very  feeble  proportion.  It  is  then  almost  black,  tacky,  and 
viscous;  it  has  turned  "fatty."  At  220°  C.  rubber  becomes  oleaginous,  and 
decomposes  at  300°  C. 

How  it  burns. — Rubber,  so  altered  in  contact  with  an  ignited  body,  burns  with  a 
very  smoky  red  flame.  When  in  fairly  sized  blocks,  it  may  be  easily  extinguished, 
but  if  it  be  in  fragments  (factory  waste-cuttings),  the  heat  is  rapidly  propagated, 
the  whole  melts,  and  it  becomes  almost  impossible  to  stop  the  fire. 


PROPERTIES   OF   LATEX   AND   INDIARUBBI  K  125 

Destructive  distillation  qfrtMw,  On  •!•  >tru<-ti\,  distillation  rubU-r  generate* 
several  product- :  in  tin-  U^innin^  it  only  di -engages  a  little  carbonic  acid  (CO,)  and 
carbonic  it  xide  (( '(  )).  \\itli  traces  of  some  other  products  the  exact  nature  of  which  it 
is  almost  impossible  to  determine,  and  in  \\liirli  < irrard  ami  ( 'loez  thought  they 
encountered  sulphuretted  li\(li..Lrni  ami  hydrochloric  acid.  In  tin-  variety  taken 
hen-  as  type  thesr  bodies  \\eiv  n« »t  detected.  At  thi-  |.'»int  it  M  noccHHary  to 
i-aiM-  the  temperature,  so  as  to  "boil  "  the  rubber,  whieli  then  gradually  di>a]»|joan 
\\ithoiit  lea\iiii:  an  appreciable  residue,  irivin;:  birth  to  several  h  \drocarhides  which 
possess  the  property  of  dissoMn^  \vith  facility  sound  ruhlier,  amber,  copal,  etc. 

As  a  considerable  proportion  of  them  are  obtained,  it  \\a-  proposed  a  long  time  ago 
to  utili.-e  the  moxt  volatile  fractions  for  the  treatment  of  indiarubU'r  ami  in  th< 
preparation  of  various  varnishes  <  I  laniard,  ls.'»3). 

Th'  /it/'lrix-.i, •/>!</>.<  />,•<>  I m; 'I  l,ii  f/te  destructive  <li*i ill.it ',,,„  ,,i'  /•///,/„<,-.  Tin- 
hydrocarbides  generated  during  the  dry  distillation  of  rub) KM*  have  been  examined 
by  Gregory,  Dalton,  Himly,  Greville  Williams,  Bouchardat,  and  Sir  \V.  Tilden. 
Carl  Otto  Weber,  etc. 

1.    Volatile   hydrocarbides  liyht   spirit. — According  to  Bouchardat,   the    mo>t 
volatile  portions  of  the  distillation  of  indiarubber  collected  in  a   tree/in^'  mixture 
consists  of  Iiiiti/lt  ne  (C4HS),  caoutchouc,  and  eupione.     Caoutchene,  isomeric   \\ith 
butylene,  boils  at  14° C.  (57'2°F.);    its  density  is  O'GGO;    it  congeals  at    !«• 
(50°  F.)  in  the  form  of  needles. 

Hi  inly. — Rubber  on  distillation  yields  charcoal  and  three-quarters  of  its  weight  of 
a  volatile  thick  dark  oil  which  when  redistilled  yields  a  fraction  between  l."»o  and 
205°  C.,  which  is  resolved  on  redistillation  into  a  fraction.  The  density  of  the  most 
volatile  [>ortions  of  which  collected  by  Himly  is  0'654 ;  they  boil  between  33°  and 
44°  C.  (9T40  and  111-2°F.).  By  treating  them  by  concentrated  sulphuric  acid 
they  are  (Gregory)  transformed  into  isomers,  boiling  at  220°  C.  (428°  1 

Greville  Williantx — Isoprene. — The  more  recent  researches  of  Greville  William- 
show  that  after  several  rectifications  over  sodium  a  light  body  can  be  extracted  from 
these  oils,  to  which  he  gave  the  name  of  isoprene  (hem*hrpt*6\  IN  tiling  at 
from  37°  to  38°  C.  (98'6°  to  100'4°F.),  with  a  density  of  0'6823,  and  a  vapnnr 
density  of  2 '40.  The  same  hydrocarbide  is  produced  by  the  distillation  of  gntta 
percha.  Exposed  to  air,  it  absorbs  oxygen,  and  is  converted  into  a  white  solid 
amorphous  body. 

•_'.  Tfie  heavier  oils  from  the  dry  distillation  of  rubber. — The  less  volatile  fraction 
contains  a  hydrocarbide  (Himly's  caoutchine\  which  is  obtained  pure  by  treating 
the  crude  oil  with  sulphuric  acid,  diluted  with  eight  times  its  weight  of  \\atcr. 
After  washing  with  water,  and  a  distillation  over  potash,  it  is  saturated  with  hydro 
chloric  acid,  and  afterwards  dissolved  in  alcohol.  By  diluting  the  alcoholic 
solution  with  water,  an  oil  is  precipitated,  which,  dried  over  calcium  chloride  and 
rectified  several  times  over  baryta,  then  over  sodium,  presents  the  following 
proper!  ir>  : 

Properties  of  caoutchine. — Density  =  0'842.     Vapour    density     4 ••*«'»  1.      It    i> 
polymeric  with  isopivne,  and  should  be  represented  by  the  formula  C,,,!!,,  :  it  U.iU 
at   170   ('.  (IMS    K),  and    dor,    not    become   solid    by 'a    cold   of  -  30°  ('.  (       I"-'    ; 
it  is  insoluble  in  water,  and  ea>ily  dissolves  in  alcohol  and  ether,  essential  and  fatty 
oils;  hydrogen  peroxide  resin  i  ties  it.     It  is  attacked  by  chorine  and  bromine.     Chloro- 
caoutchine  is  viscous  ;  its  density  =  1*443  ;  it  decoinp<»r-  \\hen  distilled  over  a  base, 
and  yields  a  hydrocarbide  containing  more  carbon  than  caoutchine.      It  cmnl 
directly  with  hydrochloric  acid,  and  with   hydrobromic  acid  ;  the  hydrochloride  of 
caoutchine,  isomeric  with  the  solid  "artificial  camphor"  of  spirits  of  turpentine, 
brownish  oil, with  a  nause.  .us  taste.    Density  =  0'950.   It  is  decomposed  on  distillation, 
and  is  not  attackable  by  dilute  alkalies.      Concentrated  sulphuric  acid   transform- 
caoutchino  into  a  thick  oil  resembling  hexi-riie.  \\hilst  a  small  quantity  of  a  sulpho- 
conjugated  acid  is  produced  at  the  same   time.      \\\  treating  caoutchine  altern 
With  bromine  and  sodium,  two  atoms  of  hydrogen  are  abstracted  from  it.  and  it  i> 
converted  into  cymene  (C10H10)  : — ((i.  \\ 


126  INDIARUBBER 

3.  Tlie  heaviest  oils  from  the  dry  distillation  of  rubber. — Finally,  the  heaviest 
portions  J  of  the  distillation  of  rubber  contain  an  amber-yellow  oily  hydrocarbide,  of 
a  bitter  taste,  to  which  Bouchardat  has  given  the  name  of  hewfene,  and  which  is 
isomeric  with  ethylene.  Density  =  0'921  at  21°  C.  (71*6°  F.).  It  boils  between 
315°  and  350°  C.  (599°  to  662°  F.);  it  does  not  solidify  on  cooling,  is  soluble  in 
ether,  alcohol,  fatty  and  essential  oils.  It  absorbs  chlorine,  and  then  assumes  a 
waxy  consistency.  It  is  decomposed  on  boiling  and  resolved  into  gaseous  and 
liquid  products,  the  latter  of  which  have  a  lower  boiling  point.  Sulphuric  acid 
resinines  it  and  transforms  it  into  an  oil  boiling  at  228°  C.  (442 '4°  F.),  which  is 
not  attacked  by  concentrated  acids.  Bouchardat  concluded,  from  the  manner 
in  which  the  different  products  of  the  distillation  of  caoutchouc  behave,  and 
more  especially  isoprene,  that  all  these  products,  like  caoutchouc  itself,  are  polymers 
of  isoprene. 

Synthesis  of  Indiarubber. — houchardafs  researcJies. — Pushing  these  studies 
further  forward,  Bouchardat  claimed  to  have  obtained  artificial  or  synthetical  rubber 
by  causing  hydrochloric  acid  to  react  on  isoprene.  But  his  claim  has  never  been 
absolutely  substantiated  nor  confirmed  by  any  other  independent  authority.  One 
part  of  this  body  mixed  with  15  parts  of  saturated  hydrochloric  acid  was  subjected, 
in  a  sealed  tube,  to  the  action  of  a  freezing  mixture.  As  soon  as  the  tube  contain- 
ing the  mixture  was  agitated,  a  violent  reaction  was  produced,  accompanied  by  an 
abundant  disengagement  of  heat.  The  mass  obtained  is  abandoned  to  itself  for 
two  to  three  weeks  at  the  surrounding  temperature,  and  care  is  taken  to  agitate  it 
from  time  to  time.  If  the  product  then  be  subjected  to  distillation  after  having 
been  previously  diluted  with  water,  there  is  obtained,  besides  a  monohydrochloride 
and  a  dihydrochloride  of  isoprene,  a  solid  residue  which,  freed  from  the  chlorides 
formed,  by  prolonged  washing  with  boiling  water,  presents  the  following 
composition : — 

TABLE  XXVII. — ANALYSIS  OF  BOUCHARD AT'S  SO-CALLED  SYNTHETIC  RUBBER. 


Per  cent. 


Carbon 87*1 

Hydrogen      .         .         .         .         .         .         .         .         .         .,  11*7 

Chlorine 17 


100-5 


Bouchardat  does  not  consider  the  presence  of  this  latter  body  but  as  accidental,  and 
due  to  a  residuum  of  chlorides  from  which  it  is  difficult  to  free  the  mass.  It  is 
therefore,  he  claims,  a  substance  analogous  with  indiarubber,  insoluble  in  alcohol, 
and  which  swells  in  ether  and  carbon  disulphide. 

Submitted  to  dry  distillation,  this  new  substance  produced  the  same  hydro- 
carbides  as  iudiarubber,  and  Bouchardat  concluded  therefrom  that  his  product  was 
identical  with  natural  rubber.  But  J.  G.  M'Intosh,  in  his  efforts  to  deprive  pinene 
hydrochloride  of  its  HC1  (British  Patent),  always  obtained  a  small  quantity  of  a 
rubber-like  residue,  distended  by  alkaline  lye,  which  was  left  in  the  steam-  or  fire- 
heated  copper  still  at  the  close  of  the  operation.  He  has  no  doubt  that  this 
substance  is  identical  with  that  obtained  by  Bouchardat.  When  freed  from  the 
alkali  and  salt,  with  wilich  it  is  distended,  the  highly  swollen  elastic  pitch-like 
body  decreases  to  a  minimum,  and  loses  its  elasticity  and  crumbles  to  a  powder. 
This  "synthetic  rubber"  possibly  conies  from  the  free  resinous  acids  in  the 
turps,  etc. 

Sir  ^Y.  A.  Til-den's  researches. — Tilden,  resuming  the  researches  of  Bouchardat, 

1  Obtained  by  distilling  rectified  caoutchine  Avith  water  as  long  as  any  part  of  it  passed 
over  with  the  aqueous  vapour,  and  then  redistilling  the  residue  in  an  oil  bath. 


PROPKRTIKS   OF   LATEX   AND   INDIARUBBI  k  127 


ni--d  in  1SS-I  that  isopivn.'  \\a-  aU"  found  in  tin-  m<»t  volatile  portion^  of  the 
distillation  «.t'  turpentine,  and  of  certain  \egetable  oil-,  -ueli  if  ••••I/a  nil.  linsovd  oil, 
ami  castor  oil.  Isopivne.  thu-  obtained,  in  contact  \\itli  saturated  hydrochloric 

acid,  was  also  converted  into  •*  --lid  elastic  ma      nmilar  to  indiambber,     \t\\\ 
the  course  of  his  l*!'l  experiments,  Tilden,  after  ha\ing  ^par.it.d  iaopreae  froa 

different  vegetable  oils,  studied  iN  properties  attenti\e|\.       Kadi  part  icular  >j*'<  i: 

'•ndosed  in  a  llask  and    put    to   our   side    in  the  laboratory,  and  at  tin-  md  of  a 
feu    mouths    lie    found  that    tin-    -uhstaiice-    in    the    tla-k-    \\i-re  completely  altered 
in    a|>|>earan<v   and    pn.prrt  !••-.      The    liquid,    originalh    limpid    and    i-olotirleflS,  had 
I.  •••oiiii-  converted  into  a  >vrup\    mass,  in  \\hich  ili.-iv  ll«  ated  rather  bulky  ydlouUh 
lumps.      These,  on     further    examination,  lie    found    to   possess  all  the  projM-rti' 
eaoiitehoiic.  and  attributed  this  formation  to  the  generation,  l.y  oxidation,  of  a  small 
•  (iiautity  of   acetic  or  formic  acid.      The-e   acids,  in  their  turn,  induced   the   nan- 
formation    of    the    remainder   of    the    mass,  prol.al.ly  l»y  ferm.-ntation.      Thr   li«pii«l 
then    contained  a    little    unaltered    isoprene,    slightly  acid    t*t    te>t  paper.      Anal 
sh<>\\ed    that    the    solid   substance,    \\hich    floated    on    the    >urface,    \s;»,s    a    product 
>siim  all  the  constitutive   element.^   of   natural  ruMn-r.      Like  the  latter,  it  con- 
si-te<l  of  t\vo  suhsiaiices.  the  oiii«   inon-   soluhle   than    the  other,  iu  such  vehicles  as 
IHMI/O!  and  carliou  disulphide.      The   evapoi-ated  lien/ene  solution  yielded    a    iv-idue 

having  all  the  characteristics  of  the  residue  of  a  benzene  solution  of  /''//•»»/•/ 
nililuT,  evajiorated  in  the  same  conditions,  the  same  elementary  com]Misitiou.  the 
>ame  aillu-si\e  and  elastic  properties.  There  is  no  need  to  insist  UJM.U  the  im- 
portance of  the  researches  of  Bouchardat  and  Tilden  —  synthetically-  produced 
riil»l»er  has  passed  into  the  domain  of  facts.  80  far  as  the  industrial  question  is 
concerned,  the  production  costs  relatively  a  little  hi«rh.  In  regard  thereto,  then- 
is  uo  reason  to  doubt  the  sagacity  of  our  investigators.  Bouchardat  ex 
uieuted  on  a  derivative  of  iudiarubber  itself.  Tilden  operated  on  derivatives  of 
spirits  of  turpentine  and  of  vegetable  oils.  Further  advances  will  be  made, 
and  it  would  not  be  surprising  if  in  the  near  future  natural  rubber  had  to 
compete  with  the  synthetical  variety.  Certain  manufactured  samples  leave  ab- 
solutely nothing  to  be  desired  so  far  as  Duality  is  concerned,  whilst,  as  to  tin- 
price,  it  is  a  matter  of  time  and  patience;  the  subject  is  worthy  of  being  probed 
to  the  bottom,  for  although  only  a  rubber  of  uniform  quality  has  hitherto  been 
obtained,  it  is  at  least  free  from  all  impurity,  which  is  not  the  case  with  natural 
rubber.1 

Action  of  solvents  on  normal  rulthrr.  —  Insolubility  ///  /"//<  r.-  I  f  water  and  alcohol 
penetrate  rubber  and  cause  it  to  swell,  they  do  not  dissolve  it,  neither  when  hot  nor 
when  cold.  Certain  sorts  cede  to  water  a  feeble  quantity  of  extractive  matter  ;  these 
are  the  substances  which  Muspratt  (?  lire)  called  aloetic,  and  which  come,  almost 
al\\ays,  from  certain  juices  added  to  the  latex  to  hasten  coagulation.  Certain  r.i\\ 
rubbers  from  I'eru,  whilst  being  \\nnight  in  the  factory  make  the  \\orkers  engaged 
in  the  first  stage  of  their  manipulation  ill.  After  being  boiled,  these  almost  blark 
rubbers  come  out  of  their  bath  amber  coloured  and  inoffensive,  whilst  .the 
strongly-coloured  deep  brown  water  is  changed  into  a  rather  violent  purgative. 
But  the  pure  rubber  now  under  examination  is  absolutely  insoluble  in  that 

Vehicle. 

I,i»,lnl,ilifi/  in  ulnthnl.  —  It  is  likewise  insoluble  iii  alcohol,  and,  if  sometime- 
(in  rubber.-  on  being  treated  with  boiling  alcohol  cede  to  it  about  '2  JHT 
cent,  of  a  greasy  amber-coloured  fusible  Ixxly,  it  is  because  they  have  U-en 
subject.  -<1  to  the  oxidising  action  of  air  and  light,  an  alteration  which  will  l>e 
di.-cusM'd  when  the  influence  of  atmospheric  agents  on  caoutchouc  fall.-  to  be 
considered. 

Other   tolvent*.  —  Ether,  carbon  disulphide,  light   coal  tar   naphtha,   iK-troleum, 
spirits  of  turpentine,  fatty  and   essential   oiK.  several    mixture-   of   these  \\ith   other 

1  The  authors  are  moiv  saugiiiiu-   than   what    has   l>rm   .loin    in    tin's  direction    n/> 
justifies.  —  Tu.     [The  above  remark  was  eritirisM  in  certain  quarters  when  tin-  first  Kngluh 
edition  appeared  in  1903.     Time  has  justified  the  remark.] 


128 


INDIARUBBER 


liquids,  and,  finally,  according  to  Kletzinski,  even  boiling  naphthaline,  insinuate 
themselves  rapidly,  like  water  and  alcohol,  into  the  pores  of  the  caoutchouc, 
causing  it  to  swell  enormously,  and  apparently  to  dissolve  it.  But  what  is  often 
regarded  as  complete  solution  in  such  cases  is  only  in  reality  the  result  of  the 
interposition  of  the  dissolved  portion  in  the  very  swollen  portion,  the  latter  having 
preserved  the  primitive  form,  greatly  enlarged,  and  being  therefore  easily 
disaggregated. 

Separation  of  the  soluble  and  insoluble  portions. — We  can  therefore,  by  the  aid" 
of  a  sufficient  quantity  of  each  solvent,  almost  completely  separate  the  two  portions 
by  renewing  the  liquid  without  agitation  and  without  disaggregating  the  greatly 
swollen  but  undissolved  residue.  The  easily  dissolved  portions  vary  between  3  and 
7  per  cent.,  with  the  quality  of  the  samples  and  the  nature  of  the  solvent,  but  the 
properties  of  the  two  portions  remain  distinct  after  their  separation  and  evaporation 
of  the  liquid  solvent. 

TABLE  XXVIII. — SHOWING  SOLUBILITY  OF  INDIARUBBER  IN  VARIOUS  SOLVENTS 

(TSCHIRSCH). 


A. 

B. 

C. 

D. 

E. 

F. 

(Soluble    . 

54 

45 

62 

51 

59 

63 

Para-^  Insoluble          .         .45         52 

31-3 

46 

39 

33 

[Water      ...        1 

3 

6-7 

3 

2 

4 

(Soluble 

76 

73-8 

75 

64 

71-5 

96'5 

M          l    ,  -|  Insoluble 

22 

20-8 

24-5 

35 

25-0 

0-5 

asicae    [Water      .         .         . 

2 

— 

0-5 

1 

3-5 

3-0 

African  (Soluble    . 

94-0 

94-0 

94-0 

85-5 

92-0 

94-0 

Medium  -!  Insoluble 

3-0 

3-0 

2-0 

9-5 

3-0 

3-0 

Batanga  [Water      . 

3'0 

3-0 

4-0 

5-0 

5-0 

3-0 

A,  B,  C,  D  =  Petroleum  ethers  of  different  boiling-points  :  A,  boiling-point  over 
60°  C.  B,  boiling-point  under  60°  C.  C,  boiling-point  over  60°  C.  :  the 
rubber  was  then  treated  with  alcohol.  D.  boiling-point  under  60°  C.  ;  the 
rubber  was  then  treated  with  alcohol.  E,  benzol  boiling  between  35°  and 
110°  C.  F,  chloroform. 

Their  different  properties. — The  undissolved  portion  is  less  adhesive,  but  more 
tenacious  ;  it  retains  the  greatest  part  of  the  brown  colouring  principle  of  the 
commercial  varieties.  The  soluble  portion,  more  especially  that  first  dissolved,  is 
decidedly  more  adhesive,  softer,  more  elastic,  less  tenacious,  and  less  coloured. 
Anhydrous  ether  extracts  from  translucid  rubber  of  an  amber  colour  66  per  centr 
of  a  colourless  soluble  substance,  and  leaves  34  per  cent,  of  a  fawn-coloured  body. 
Anhydrous  and  well-rectified  spirits  of  turpentine  separates  distinctly  from  com- 
mercial brown-coloured  varieties  of  rubber  49  per  cent,  of  soluble  amber-matter, 
and  51  per  cent,  of  translucid  insoluble  matter  retaining  the  brown  coloration. 
The  ether  solution  of  rubber  is  precipitated  by  alcohol,  yielding  a  milky  emulsion 
analogous  to  the  natural  juice  of  the  latex.  Heavy  coal-tar  oils  dissolve  5  per 
cent,  of  their  weight  of  caoutchouc,  whilst  the  light  oils  dissolve  as  much  as  30  per 
cent.  Only  the  most  highly  volatile  solvents  used  in  the  industry. — The  best  solvent, 
according  to  Gerard,  is  a  mixture  of  100  parts  of  carbon  disulphide  and  5J  per 
cent,  of  absolute  alcohol.  A  clear  solution  like  water  is  claimed  to  be  obtained 
with  this  mixture,  which  on  evaporation  leaves  the  indiarabber  under  the  form  of 
an  extremely  thin  and  pure  pellicle  (British  Patent,  13,069;  1850).  Gerard, 
being  specially  engaged  in  drawing  rubber  out  into  cylindrical  threads,  prepared  the 
paste  by  using  carbon  disulphide,  mixed  with  5  per  cent,  of  ordinary  alcohol. 


PROPERTIES   OF   LATEX  AND   INDIARUBBER  129 

This  alcohol,  containing  15  per  cent,  of  water,  hinders  .solution,  and  condition**  are 

thus  realised  for  a  swelling  of  the  rubber  favourable  for  kneading,  ami  \\liirh 
facilitates  the  passage  to  tin-  ilra\\  plate  \\ithnut  i-H'iM-tin^  real  ^.lution,  \\liich 
\\niilil  much  iliininisli  th<-  tenacity.  <  lem-rally,  i  uM-T  iolationi  >  i'-l«l  "ii  ex.ijn. ration 

;i  pitchy,  taek\  residue;  tin-  slower  the  evaporation  tin-  m«.n-  do  these   |, 

manifest     them>el\e>.       In     industry,     therefore,    only     tin-     ni..-t     \«.|atil.-     >..|\ 
an-  iisrd.1 

'/'//'  in  ri'«ii.<  >tn<l  itilli'xii'i  ///•///(•//-/,  .<  i,t'  rnii/ifi'. — Solution  in  alx>v6  vehicles  U 
thus  .,iil\  partial.  Kubber,  in  fact,  consists  of  fcwo  i^»m«-ru:  substance*,  one 
of  \\hich,  solid  and  elastic,  resists  almost  all  reagents;  the  other,  semi-liquid  and 
tacky,  is  much  more  easily  attacked  and  dissolved.  It  is  to  this  second  body  that 
rubber  o\\es  its  property  of  soldering  itself  to  itself  when  its  recently  cut  surfaces 

Hourly  nonprossed.  To  the  first  body  the  name  of  t lervout principle  is  gi 
and  to  the  second  the  term  of  adhesive  principle  is  applied.  If  these  two  isom<  ric 
proximate  principles  In-  separated  by  appropriate  solution,  neither  of  them  preserves 
the  elastic  ami  extensible  properties  to  the  same  extent.  "It  would  appear,"  says 
Payen,  "that  the  adherence  between  the  lubricated  filaments  by  a  greasy  body, 
rendered  supple  by  the  soluble  and  soft  portion,  had  been  partially  destroyed." 
If  indiarubber,  cut  into  the  form  of  rectangular  prisms,  be  kept  immersed  in  a 
large  excess  of  solvent,  it  will  be  seen  to  swell  gradually  from  the  sujKjrficies  to  tin- 
centre.  The  augmentation  in  volume  of  the  undissolved  portion  may  be  determined. 
When  the  swelling  is  finished,  the  dimensions  of  the  sides  are  tripled  in  ben/ine, 
anhydrous  ether,  spirits  of  turpentine,  as  well  as  in  a  mixture  of  100  of  carbon 
di  sulphide  with  4  of  hydrated  ether.  The  total  volume  therefore  was  equal  to 
twenty-seven  times  the  original  volume,  even  though  this  increase  only  applied 
to  the  undissolved  portion,  the  soluble  portion  being  diffused  in  the  liquid.  A 
mixture  of  six  volumes  of  ether  with  one  volume  of  alcohol  swells  caoutchouc  so 
as  to  quadruple  its  volume,  but  only  appreciably  dissolves  the  less  nervous  and 
most  adhesive  portion.  In  cold,  rectified  petroleum  oil,  an  increase  of  thirty 
times  its  volume  has  been  observed,  but  without  taking  the  dissolved  portion  into 
account. 

Microscopical  examination  of  the  swollen  insoluble  portion  of  rubber. — If  the 
portion  of  rubber  most  resistant  to  solvents  be  examined  under  the  microscope  with 
a  magnifying  power  of  300,  it  shows  a  reticulated  texture,  the  anastomosed 
filaments  of  which  stretch  and  swell,  absorb  the  above  liquids,  and  contract 
proportionately  as  the  operation  goes  on. 

Parked  solvent — Thiocamf. — Parkes  patented,  as  an  excellent  solvent  for 
caoutchouc,  the  liquid  obtained  by  passing  a  current  of  gaseous  sulphurous 
anhydride  over  camphor  (British  Patent,  11,147;  1846).  See  also  Professor 
Kmerson  Reynold's  Thiocamf  (British  Patent). 

Caoutchoucene. — The  liquid  hydrocarbide  obtained  by  the  distillation  of 
caoutchouc  is  an  energetic  solvent.  But  it  and  the  preceding  are  too  dear  to 
permit  of  actual  use. 

The  extent  to  which  rubber  dissolves  in  benzol. — Heeren  determined  the  solvent 
[tower  of  benzol  on  twelve  principal  varieties  of  commercial  rubber.  The  samples, 
continuously  kneaded  by  hot  rollers,  were  afterwards  cut  into  strips  thin  enough  to 
be  placed  in  small  flasks,  and  then  drenched  with  a  sufficient  quantity  of  ben/.ol 
.to  completely  moisten  them.  After  sufficient  digestion,  enough  benzol  was 
gradually  added  to  convert  all  the  samples  into  a  syrupy  consistency  by 
frequent  agitation.  He  thus  got  an  equal  degree  of  liquefaction  with  all  tin- 
samples  tested.  A  small  j>ortion  of  the  liquid  so  obtained  was  taken  from  each 
sample,  weighed  on  tared  watch-glasses,  and  evaporated  in  the  drying-oven 

1  The  translator  in  the  first  edition  of  Livache  and  M'lntosh's  "  Varnishes,"  recommended 
warm  liquid  terebinthine  (pinene)  hydrochloride — an  artificial  camphor  residual— as  the  best 
solvent  for  rubber.     It  is  the  only  solvent  which  he  has  found  to  act  visibly  and  energetically. 
Possibly  this  is  the  rubber  solvent  referred  to  as  terpineol  by  W.  F.  Reid.     It  is  difl 
see  how  terpineol  can  be  an  artificial  camphor  residual. 
9 


130 


INDIARUBBER 


until   the  benzol   had   completely  disappeared.      The   following   table   gives   the 
results : — 

TABLE  >XXIX. — SOLUBILITY  OF  COMMERCIAL  RUBBER  IN  BENZOL  (HEEREN). 


Percentage 

That  is  to  say, 

Variety  of  Commercial  Rubber. 

of  Rubber  in 
Solution. 

100  Parts  of  Benzol 
dissolved. 

20'0 

25-0 

Para     

17-0 

20-0 

16-1 

18'0 

Borneo 

13-8 

15-0 

Africa  . 

127 

14-5 

Ceara   . 

12-0 

13-6 

Mozambique 

11-5 

13-0 

Quisambo 

9-1 

10-0 

Rangoon 

9-0 

9-8 

Knikels 

8-6 

9'4 

Niggers 

7-8 

8-5 

Madagascar 

5-8 

6'0 

A  very  curious  conclusion  may  be  drawn  from  Heeren's  results.  The  figures 
given  in  the  above  table  show  a  very  marked  solubility  in  the  case  of  Para  rubber, 
whilst  Madagascar  rubber  only  indicates  an  excessively  poor  relative  solubility. 
Nevertheless,  both  of  these  species  of  rubber  are  varieties  preferred  and  sought  after 
in  commerce  and  industry,  each  for  special  applications.  Obviously  the  two 
rubbers  are  not  esteemed  for  the  same  reason,  and  are  not  utilised  in  industry  for 
the  same  purposes,  the  one  containing  more  nervous  matter  and  the  other  more 
soft  and  adhesive  substance. 

General  remark  applicable  to  all  varieties  of  rubber  and  ail  solvents. — Both 
solvent  and  rubber  should  be  exempt  from  water  or  moisture  within  the  limits  of 
the  possible  ;  if  it  only  be  desired  to  soften  the  rubber  without  dissolving  it, 
hydrated  solvents  are  preferable. 

Action  of  atmospheric  agents — Modifications  in  colour  and  chemical  composi- 
tion— Miller's  experiments. — Atmospheric  agents  exert  a  very  decided  action  on 
natural  rubber.  Both  air  and  light  alter  the  colour  of  rubber,  and  the  longer  rubber 
is  exposed  to  these  agents  the  more  the  colour  is  accentuated.  Not  only  is  the 
colour  changed,  but  the  proximate  principles  constituting  the  substance  are  like- 
wise modified. 

TABLE  XXX. — PERCENTAGE  OF  OXYGEN  IN  DIFFERENT  PORTIONS  OF  PLANTA- 
TION RUBBER  FRACTIONALLY  SEPARATED  THEREFROM  BY  SOLUTION  IN 
PETROLEUM  ETHER  (FENDLER).  (See  TABLE  XXXVIII.) 


Oxygen  in  Portion 
Soluble  in  Petroleum 
Ether. 

Oxygen  in  Portion 
Insoluble  in  Petroleum 
Ether. 

Ceylon  Para     .... 
Togo  Manihot 
East  African  Manihot 

Per  cent. 
2-66 
5-48 

Per  cent. 
17-00 
26-09 
25-8 

Miller  made  interesting  experiments  on  this  subject.  He  exhausted,  by  benzine, 
a  piece  of  goods  waterproofed  by  indiarubber,  and  which  in  that  state  had  remained 
during  six  years  in  contact  with  the  air.  Benzine  only  partially  dissolved  the  rubber, 
and  the  dissolved  product  left  on  evaporation  of  its  solvent  possessed  altogether  new 


PROPERTIES   OF   LATEX   AND   INDIARUBHI-k  131 

properties:  it   resembled  >hellae  ;  it  dissolved  in  alcohol,  chloroform,  benzol,  and 
alkaline  solutions,  but   \\.is  insoluble  in  ipuito  of   turpeniin.-,  Htfboa  dM||B 


-,  so  s-,  ,,  ene,  c,u-,.,ii     i^upc\an 

ether;    «.n    distillation   it  yielded  uater,  which  pn.\vd    it    lo  .  "iilain   OZygBD,      Tin- 
author  LO'ive  its  composite  •• 

Txr.i.i     \\.\l.      SIIONMV.    I'I.IIMMI:    AjfALYSlH  OF    llii.r.n     KXTUAITKII   IBON 

\\'  \  I'KKI'i; i  MM:    Sl.X     vl  l   \i:-      EXPO    '    Etl      I"     \li:. 


Percent 

Carbon.  .......... 

64*0 

Hydrogen  .......... 
Oxygen  

8*46 

100-00 

This  alteration,  much  more  rapid  in  the  case  of  normal  caoutchouc  than  in 
that  of  the  natural  rubber,  is  more  apt  to  take  place  when  it  is  exposed  alternately 
to  air,  to  the  sun,  and  to  moisture.  The  substance  then  acquires  a  jK-netratin^ 
odour,  and  it  becomes  at  the  same  time  soft  and  less  resistant  ( I'uyen ».  Vulcanisa- 
tion impedes  this  alteration  or  rather  transformation  (Warren  de  la  Rue  and  Abel). 
The  action  of  light  on  natural  rubber  is  very  singular,  and  has  been  taken  advan- 
tage of  technically.  If  a  sheet  of  rubber  be  exposed  to  sunlight  for  a  few  hours, 
the  surfaces  exposed,  laid  on,  and  pressed  on  to  a  lithographic  stone,  it  comnmni 
cates  to  the  latter  the  property  of  assimilating  lithographic  ink,  \vhich  is  not  the 
ith  the  portions  which  have  remained  in  the  shade.  If  a  layer  of  indianil»Ker, 
dissolved  in  benzol,  be  spread  upon  paper,  and  if  after  evaporation  of  the  solvent 
this  sheet  be  exposed  under  a  negative,  it  may  then  be  laid  on  a  lithographic  stone 
and  used  to  make  very  delicate  reproductions.  This  property  is  utilised  in  photo- 
lithography. The  action  of  air,  in  absence  of  light,  would  appear  to  be  less 
energetic,  especially  during  a  more  or  less  prolonged  period.  If  the  action  of  heat 
be  combined  with  that  of  air  and  atmospheric  oxygen,  the  alteration  is  more 
appreciable,  and  light  is  not  even  indispensable.  Chapel  examined  a  sample  of 
decomposed  Accra  rubber.  It  appeared  to  the  naked  eye  as  a  sticky  substance, 
but  microscopic  examination  showed  that  decomposition  was  only  partial ;  tin- 
soft  substance  had  been  attacked,  but  the  nervous  part  had  resisted  alteration  more 
energetically. 

To  determine  why  rubber  perished,  L.  Clark  tested  natural  Para  prima  (A.) 
against  normal  Para  sheets  (/?.).  Here  are  the  results  as  given  in  the  Moniteur 
Scientifique  de  Quesneville,  March  1872.  (A.)  Natural  Para  jtrimn. — One  ounce 
(31-35  grammes)  of  rubber  was  used  in  each  experiment.  The  rubier  was  in  the 
form  of  a  narrow  riblxm,  drawn  out  while  hot,  and  suddenly  cooled.  Its  colour 
was  a  very  pale  brown.  The  different  samples  were  submitted  to  the  tests  at  the 
end  of  October  1859,  and  examined  nine  months  afterwards,  ith  August  1860. 
No.  1,  placed  in  a  net  and  exposed  in  the  sun,  open  to  air  and  rain,  had  become  rotten, 
but  it  was  neither  viscous  nor  pulverulent.  Its  weight  had  increased  '2  '23  grammes, 
say  7  per  cent.  No.  2,  exposed  to  air  and  light,  but  kept  dry  in  a  flask  turned 
upside  down,  had  increased  2 '8  per  cent,  in  weight  in  consequence  of  the  alworption 
of  oxygen,  and  had  become  brown,  soft,  and  viscous,  especially  in  the  parts  most 
exposed  to  the  light.  It  yielded  to  alcohol  11*81  per  cent  of  a  soft,  viscous, 
oxidised  resin.  No.  3,  exposed  to  diffused  daylight,  in  open  flask,  filled  with  soft 
water,  had  become  white  and  opaque  by  absorption  of  water,  and  increased  1 7  per 
cent,  in  weight,  but  it  hud  undergone  no  alteration  in  its  chemical  properties  J 
dried,  it  regained  its  original  properties.  No.  4,  exposed  to  diffused  daylight, 
in  open  flask,  rilled  with  sea  water,  had  absorbed  3 '6  of  its  weight  of  water,  and  its 
chemical  composition  was  not  altered.  (£.)  Sheet  of  rolled  Para. — A  similar  series 


132  INDIARUBBER 

of  experiments  were  performed  on  a  sheet  of  rolled  rubber.  No.  1,  exposed  to  sun 
and  rain,  had  segregated  into  a  tacky  mass,  and  lost  tenacity  and  elasticity. 
No.  2,  exposed  in  an  inverted  flask  to  air  and  diffused  daylight,  had  increased  in 
weight  0'52,  say  1'6  per  cent.  It  formed  a  small  viscous  mass,  and  Lad  lost  its 
elasticity,  more  especially  in  portions  most  exposed  to  action  of  light.  Treated 
with  alcohol,  it  gave  up  to  that  solvent  12 '04  per  cent,  of  its  weight  of  a  resinous 
body.  No.  3,  the  changes  presented  a  marked  contrast  with  preceding  observa- 
tions in  No.  3  of  first  series,  which  had  been  preserved  in  a  glass  flask  kept  in 
darkness,  but  open  to  air  during  same  time.  The  sample  had,  in  this  case  only, 
increased  0*6  per  cent.  It  showed  no  signs  of  alteration  so  far  as  tenacity 
and  elasticity  were  concerned,  and  only  yielded  2  per  cent,  resin  to  alcohol. 
No.  4  consisted  of  a  sheet  of  the  same  rubber  which  had  been  steeped  in  soft 
water  in  the  open  air  and  in  diffused  daylight.  It  had  increased  87  per  cent,  in 
weight  by  the  absorption  of  water,  i.e.  its  weight  had  almost  doubled.  It  had 
become  white,  opaque,  pitchy  and  tacky  to  the  touch,  and  on  pressure  allowed  the 
water  which  it  had  imbibed  to  escape.  Exposed  to  the  air,  it  quickly  lost  the 
weight  which  it  had  gained.  No.  5,  similar  to  the  preceding,  but  immersed  in 
sea  water ;  it  was  slightly  tacky  and  opaque,  but  had  only  increased  5  per  cent,  in 
weight  by  absorption  of  the  liquid.  A  second  sample,  placed  in  a  flask  filled 
with  sea  water,  gave  off  a  smell  of  sulphuretted  hydrogen,  and  gained  5*6  per  cent, 
in  weight.  It  had  neither  lost  in  elasticity  nor  in  tenacity.  Latimer  Clark's  experi- 
ments show  that  if  air  and  light  combined  have  a  baneful  action  on  rubber,  this 
action  is  worse  in  the  case  of  the  rubber  which  had  undergone  a  mechanical  trans- 
formation, and  that  the  natural  rubber  is  more  resistant.  They  show,  moreover, 
that  immersion  in  water,  and  particularly  sea  water,  is  a  preventative  against  this 
alteration.  It  is  the  duty  of  those  actually  engaged  in  the  industry  to  profit  by 
these  remarkable  properties. 

Action  of  reagents. — 1.  Acids  (dilute)    and   caustic  alkalies. — These  act   but 
little  on  indiarubber. 

2.  Hydrochloric  acid  (concentrated) — both  liquid  and  gaseous — attacks  rubber. 
The  change  it  undergoes  is  but  little  known. 

3.  Nitric  acid  (concentrated)  attacks  it  feebly  in  the  cold,  energetically  in  the 
hot ;  colouring  it  yellow  at  first  instance,  it  transforms  it  eventually  into  a  greasy- 
looking  body  with  disengagement  of  nitrogen,  and  finally  into  carbonic  acid  and 
oxalic  acid.     By  prolonged  ebullition,  the  greasy-looking  substance  is  resolved  into 
campho-resinic  acid.     Nitrous  vapours  act  very  violently  and  rapidly  decompose  it. 

4.  Sulphuric  acid  (concentrated)  acts  upon  rubber  as  it  does  upon  cork,  and 
clears  the  surface  even  in  the  cold.     The  hot  acid  decomposes  rubber  very  rapidly, 
with  disengagement  of  sulphurous  acid  and  carbonic  acid. 

A  mixture  of  sulphuric  and  nitric  acid  attacks  rubber  very  energetically. 

5.  Hydrofluoric  acid,  like  the  organic  acids,  has  no  action  on  rubber. 

6.  Halogens — Chlorine. — Gaseous   chlorine  exerts  a  very  energetic  action  on 
rubber,  deprives  it  of  its  elasticity,  and  finally  renders  it  hard  and  brittle.     Hartzig 
took  ad  vantage  of  this  property  to  make  some  experiments  in  vulcanisation  by  chlorine. 

7.  Iodine   and  bromine  exert  an  analogous   action  to  that  of  sulphur.     The 
reasons  why  the  former  acts  more  energetically  than  the  latter  are  given  in  the 
special  chapter  on  vulcanisation. 

8.  Sulphur. — The  same   remark   applies  to  sulphur.     Its  action — as  well  as 
that  of  the  alkaline   sulphides,  the  sulphides  of   the  alkaline  earth,  the  metallic 
sulphides,  and  chloride  of  sulphur — is  of  great  practical  importance.     If  in  some 
way  or  other  indiarubber  be  mixed  with  these  substances,  and  the  mixture  heated, 
the  sulphur  is  more  or   less  absorbed.      According   to   the  quantity   of   sulphur 
absorbed,  and  the  amount  of  caloric  which  has  intervened,  the   rubber  becomes 
transformed  into  a  more  or  less  hard  and  elastic   substance,  which   successively 
assumes  the   names  of  vulcanised  rubber,  hardened   rubber,  ebonite,    etc.     These 
transformations,  of  great  importance  industrially,  form  the  subject  of  a  special  chapter. 

9.  Alkalies,    even   if  caustic,  only   act  feebly  on  rubber.     This^is   not  quite 


PROPERTIES  OF   LATEX   AND   INDIARUBBBR 

tin-  case  it'  the  mixture  be  heated,  after  a  previous  more  or  le«8  prolonged  digestion. 
Tin-  substance  thru  >often-,  becomes  tacky,  ami  then  dis>ol\es  m  small  quantilv, 
according  to  Musjiratt.  I're,  mi  the  contrary,  UMftl  that  <MU>ti<-  jM.t.i-h.  - 
very  concentrated  solution,  leaves  tin-  >ul»tance  intact.  I  Jut  « •\i^-ri«-iM.-  t 
that  if  nil. her  he  heated  in  a  sealed  tul)O  to  100  ( '.  (  L'  I'J  F. )  for  l'..rt\  .-ight  hours 
with  ten  times  its  volume  of  liquid  ammonia,  the  mixture  is  tran-tormr.l  into  a 
kind  of  soapy  emulsion  having  almost  all  the  properties  of  the  latex.  TllU  wolnlion 
leaves  the  nil. her  on  evaporation  in  an  almost  chemieally  pure  Htate,  but  it  ivt.iin> 
a  slight  alkaline  reaction,  which  it  is  ditlicult  to  free  it  from  entirely.  Ammonia  may 
be  regarded  as  a  preservative;  immersed  in  dilute  ammonia  (1  to  '!)  nil iU-r  goods 
lien  urn-  slightly  more  pliant. 

Here  terminates  the  summary  study  of  the  phy>i«-al  and  chemical  prop,  rtiee  of 
natural  nil»l)er.  Following  the  logical  sequence,  this  >hmild  \*  the  place  to  treat 
of  the  chemical  transformations  which  rubber  undergoes  under  the  action  of  sulphur 
and  its  compounds,  and  of  chlorine,  bromine,  and  iodine.  But  for  the  better  under 
standing  of  our  subject  it  is  necessary,  before  commencing  this  >tudy,  to  know  the 
mechanical  transformation  which  natural  rubber  has  to  undergo  before  the  manu- 
facturer can  use  it  for  a  special  purpose.  Before  skirting  on  the  Mill-animation  of 
indiarubber,  it  is,  in  fact,  necessary  to  dwell  on  the  different  ojMiati'.ns  l.y  \\hich 
raw  rubber  is  purified  and  normal  rubber  prepared. 

TRANSLATOR'S  NOTE. — The  history  of  isoprene  is  interesting,  as  it  is  the  supposed 
source  of  synthetic  rubber.  Berthelot  was  the  first  to  express  the  U-lief  that  the 
terpenes  might  owe  their  existence  to  the  more  or  less  advanced  state  of  poly  me  i 
of  a  radical  with  the  formula  C5H8,  and  to  his  hypothetical  pentene  he  gave  the  name 
of  terene,  the  terpenes  C10H16  being  the  diterenes  and  the  products  of  more  ad\ 
condensation,  the  treterenes.  The  soundness  of  this  theory  has  been  proved  l.y  the 
examination  of  a  carbide  possessing  this  formula,  which  is  formed,  as  we  have  just 
seen,  in  the  destructive  distillation  which  indiarubber  or  spirits  of  turpentine 
undergoes  when  exposed  to  a  red  heat.  Long  ago  it  was  observed  that  volatile  and 
liquid  hydrocarbides  were  produced  by  the  action  of  heat  uj)on  indiarubK-r.  This 
is  a  phenomenon  of  retrogression  accomplished  by  the  destructive  force  of  heat, 
whieh  reduces  the  polymerised  terpenes  (C5Hs)n  into  the  formula  of  the  simple 
hydrocarbide  C5H8.  Greville  Williams'  and  Bouchardat's  researches  ha\e  .dr. -ady 
been  described,  and  need  not  be  further  adverted  to,  but  perhaps  the  most  salimt 
feature  in  the  history  of  the  pentene  C5HS  is  its  decided  transformation  into 
dipentene  (C5H8)2.  (As  already  mentioned,  Himly  had  observed  in  the  products 
of  the  destructive  distillation  of  caoutchouc  a  compound  Ixiiliiuz  at  171°  C., 
having  the  formula  C10H16,  which  he  called  caoutchine.)  This  condensation  is 
effected  by  simply  heating  isoprene  to  280°  to  290°  C.  in  sealed  tul.es  in  an  atmo- 
sphere of  carbonic  acid.  Amongst  other  products  a  carbide  is  obtained  Uiiling 
between  176°  and  180°  C.,  having  at  0°  C.  a  density  of  0'86G.  It  absorbs  gaseous 
hydrochloric  acid,  yielding  a  monohydrochloride  boiling  at  145°  C.  under  a  pressure 
of  10  millimetres,  and  a  solid  dihydrochloride  melting  at  49'6°  C.  It  then-fore  has 
all  the  proi>erties  of  dipentene.  Again,  this  identity  of  caoutchine  with  dijK-ntene  i- 
continued  by  its  transformation  by  Bouchardat  and  Lafont  into  inactive  terpineol. 
They  heated  caoutchouc  with  gracial  acetic  acid  to  100°  C.  for  sixty  hours.  An 
acetate  was  thus  formed  \\hieh,  soponified  by  alcoholic  potash,  produced  a  coloiirle--. 
viscous,  odourless  substance,  distilling  in  vacuo  between  114'  and  11S"C.,  corre- 
sponding to  the  formula  Cll(H|SO  and  crystals  melting  at  about  'J.V  C.  capable  of 
producing  the  crystalline  form  of  a  terpineol  prepared  from  terpin  hydrate.  In 
spite  of  the  too  low  melting  point,  due  to  a  trace  of  impurity,  there  is  no  doubt 
but  that  the  body  thus  obtained  is  inactive  terpineol. 

Mokie\sky  ha- examined  isoprene  originating  from  the  ^tstructiw  distillation  of 
spirits  of  turi>eiitine.  By  combining  it  with  hypochloroiis  acid  he  has  separated 
two  compounds  responding  to  the  formulae  of  C-Hn  CIO  ami  (All,.;  t'l  <  >.  'I  he 
tirst.  boiling  at  141°  C.,  treated  by  potash,  yielded  trimethyl-ethylene  oxide,  which 


134 


INDIARUBBER 


was  afterwards  transformed  into  the  corresponding  glycol.  The  second  compound, 
resulting  from  the  combination  of  the  carbide  C5H8  with  two  molecules  of  acid, 
boils  at  81°  C.  The  isoprene  in  question  therefore  contains  trimethyl-ethylene  as 
well  as  pentene. 

The  constitution  of  isoprene  has  been  reliably  established  by  Wipatieff  and 
Woeittf,  who,  working  on  isoprene  boiling  at  33°  to  38°  from  the  destructive  distilla- 
tion of  incliarubber,  treated  it  in  the  cold  state  by  an  excess  of  an  acetic  solution, 
hydrobromic  acid.  They  thus  obtained  a  mixture  of  the  hydrobromides,  which  they 
fractionated  under  reduced  pressure.  The  first  runnings  of  small  amount  distilled 
under  74°  C.  under  16  millimetres.  It  consisted  of  tertiary  amytic  bromide  from 
the  trimethyl-ethylene.  The  main  fraction  distilled  at  74°  to  75°  C.  It  consisted  of 
/3-dimethyl  briniethyl-ethylene  bromide. 


identical    with    that    yielded    by    dimethylallene    under    similar    circumstances. 
Isoprene  has  therefore  got  the  following  constitution  :  — 


This  formula  is  confirmed  by  synthesis.  /S-dimethyl-triniethylene  prepared  from 
dimethylallene,)treated  with  alcoholic  potash,  yielded  a  carbide  boiling  at  32°  to  33°  C., 
possessing  the  characteristic  odour  of  isoprene,  giving  none  of  the  reactions  of  the 
allenic  or  acetylenic  carbides,  and  possessing  in  fact  the  formula  C5H8.  Treated  by 
hypochlorous  acid  it  yielded  Mokievsky's  fusible  chlorhydrin.  This  formula,  more- 
over, fits  in  well  with  the  condensation  of  isoprene  into  dipentene. 

CH3 


1 


OH 


CH2 

H-'C  CH2 

CH 

C 


CH3    CH2 


CH3     CH2 


But  this  formula  has  been  further  confirmed  by  Euler's  synthesis.  Propylene 
bromide  treated  by  potassium  cyanide  yields  dicyanhydrin  identical  with  the 
dinitrite  of  pyrotartaric  acid. 

CN-CH-CH2-CN 

CH3. 

Reduced  by  sodium  and  alcohol  this  nitrite  yields  a  base  /?-methyl-tetramethylene- 
diamine. 

H2N  -  CH2  -  CH  -  CH2  -  CH2  -  NH2 

CH3 

starting  from  which  /2-methyl-pyrrolidine  is  prepared, 

NH 


H2C 
CH3  -HC 


CH2 
CH2 


PROPERTIES  OF   LATEX  AND   INDIARUBBBR 

a  ba-e  which  treated  by  niethylir  iodide  and  poi.i-h  \i-ld-  tin-  iodo  mrthx  l.i!«-  of  the 
methyl  derixative — 

('II 

OH"    N-l 

n-v 


CH3-HCL        <  M 

The  latter  distilled  over  solid    pota-h  yieltls  an  oily  base  IxiiliiMj  ;lt    1  1  •_'    t,,  1  | :,    ('  . 
having  the  constitution  of  diinethylated  /i-inethyl  pyrrolidine, 

N/CH» 

or 
H2C,  X,CH2  II  « 


1 

jl! to 


CH3-CI'        _ICH2  CH8-HC 


II 


This  new  base  in  its  turn  absorbs  methylic  iodide  producing  an  iodo  mrthylatc, 
wliich  distilled  with  jx^tash  splits  up  in  ita  turn  into  triinethylaninc  and  a  hytlru 
carbide. 

N(CH3)2I  N(CH3)2I 


H2C,,  X,CH2      or  H2C 


CH2-CL.  c'H-  CHa-HC 


H- 


CH 


CII       C        (II 


This  Iiydrocarbide  boils  at  33°  to  39°  C.,  is  endowed  with  the  smell  and  all  the 
reactions  of  isoprcne. 

The  following   synthesis  in    the    terpune  series  has  been  effected  by   Kel»oul, 
valcryllene  or  diniethylallene — 

(•'H    \n  _  p  _  PTT2 
CH:i/ 

is  polymerised  under  the  influence  of  sulphuric  acid.  Two  products  result  from 
this  polymerisation,  the  one  answers  to  the  formula  CjyH^O,  and  possesses,  accord- 
ing to  Reboul,  a  strong  smell  of  peppermint  and  tur^ieiitiiiu.  The  other  ha-  th« 
formula  of  a  sesqui-terpene  C15H24  or  (C5H8)3.  It  boils  between  265°  and  275°  C., 
and  smells  of  turpentine. 


CHAPTER  VI 

MECHANICAL  TRANSFORMATION  OF  NATURAL  RUBBER  INTO 
WASHED  OR  NORMAL  RUBBER  (PURIFICATION)— SOFTENING, 
CUTTING,  WASHING,  DRYING,  STORAGE. 

Preliminary  observations. — The  raw  material  as  it  comes  on  the  international 
markets,  to  be  afterwards  distributed  amongst  the  industries  which  are  to  transform 
it  into  manufactured  products,  has  alone  been  dealt  with  up  to  this  point.  But 
the  high  price  which  the  article  commanded  from  the  very  beginning  of  the  rubber 
industry,  together  with  the  ignorance,  apathy,  and  greed  of  the  collectors,  very 
soon  led  to  fraud,  and,  in  the  humorous  definition  of  Rousseau,  "  the  manufacture 
of  indiarubber  is  the  art  of  incorporating  with  it  cheap  substances  without  too  far 
diminishing  its  particular  properties"  To  be  just,  Rousseau  might  have  added, 
"  and  to  improve  it  in  certain  cases  " ;  for  there  can  be  no  doubt  that  sulphur  or 
its  compounds,  far  from  being  injurious,  can  only  increase  the  value  of  indiarubber. 
If  rubber  came  to  market  in  a  suitable  degree  of  purity,  the  manufacturer  could 
use  it  at  once  as  it  comes  from  the  producing  centres.  It  is  very  rare,  however, 
that  this  is  so,  and,  more  especially  wild  rubber,  some  sorts  of  Para  pi-ima  and 
plantation  rubber  excepted,  rubber  as  imported  always  contain  a  more  or  lejs 
important  quantity  of  foreign  bodies,  water,  salts,  earth,  sand,  vegetable  debris, 
introduced  into  the  goods,  either  during  the  collection  of  the  latex,  or  during 
coagulation,  or  even  during  packing  and  transport.  Para  prima  itself  is  not 
always  exempt  from  such  addition,  whether  fraudulent  or  not,  and,  some  lots  in 
bottles  excepted,  wild  rubber  must  undergo  a  series  of  preliminary  operations 
intended  to  purify  it  and  free  it  from  foreign  matter.  This  purification  process 
is  commonly  called  the  regeneration  of  the  rubber.  But  as  the  rational  cultivation 
of  rubber  extends  in  the  tropics,  accompanied  by  rational  methods  of  treating  the 
latex,  the  quality  of  the  rubber  put  on  the  European  markets  must  improve.  At  the 
present  moment,  however,  it  is  vexing  that  preliminary  purification  should  be 
necessary.  Besides  the  considerable  expense  which  it  entails — the  simple  process 
par  excellence  being  yet  to  be  discovered — this  preliminary  work,  more  or  less, 
deteriorates  the  quality  of  the  substance,  diminishes  its  resistance ;  in  a  word,  it 
unnerves  it.  Purification  is  absolutely  indispensable  in  any  case,  but  more 
especially  when  the  rubber  is  to  be  used  in  a  state  of  solution.  The  history  of 
purification  is  not  a  long  one.  Mechanical  processes  have  nowadays  superseded 
the  early-day  hand  processes.  The  former  cleanse  more  thoroughly;  but  the 
mechanical  pulling  about  in  every  direction  which  the  rubber  suffers,  far  from 
improves  its  elastic  and  plastic  qualities. 

The  storage  of  raw  rubber — Site  for  store — Precautions. — Before  discussing 
these  four  preliminary  operations,  it  will  be  useful  to  mention  what  a  well-equipped 
raw  rubber  store  should  be  like.  Generally,  the  manufacturer  does  not  use  up, 
all  at  once,  the  stock  which  he  has  received  from  the  port  of  landing.  He  buys 
according  to  foreseen  needs,  but,  as  prices  are  liable  to  rise  or  fall,  he  makes  his 
purchases  at  the  right  time.  He  must  therefore  store  this  stock,  and  the  choice 
of  a  suitable  site,  so  far  as  the  preservation  of  a  substance  so  liable  to  change  as 
rubber  is  concerned,  is  important.  The  most  appropriate  warehouse  is  a  rather 
dark,  well  ventilated  cellar,  so  arranged  that  one  lot  is  not  heaped  on  the  top  of 

136 


TRANSFORMATION    OK    NATl'RAI.    Rl'liUKR 


L37 


another,  OF  alongside,  but   wideK  si-parated  either  by  \M..M|I-II  "i   ma-onrv  partitions. 
If  mi'-  and  tin-  -aim-    lot    In-   too    bulky,  it   \\ill  not  do   to   pile   it    up  to   ton   - 
height.      Two  cubic    metres   ..!'   cake-   ..r    ball-   an-    tin-    e\tivnii-    limit    f.    uliidi   a 
tyuiQfaotarer  should   go   in    -torin^   In  .f   rubl>er,  \sith   a   con>tant  dm-i-m 

|U  inche-  bet  \\een  tin*  lots.  The  floor  of  tin-  warehouse  ought,  as  fiir  a* 
possible,  to  1)0  made  of  asphalt  or  cement.  In  concivting  a  tloor  on  a  level  with 
the  ground,  it  is  sometime-  n-» -I'ul,  in  case  of  flooding,  to  give  it  a  slight  ri>ing 
longitudinal  sl.jpc  from  one  gable  to  another.  These  precautions  an-  indi»|  leasable 
owing  to  behaviour  of  rubber  during  storage, 

The  cleansing  processes  as  curried  on  no\\..  four  in  number — 1.  Soft.-n 

ing,  or  superlicial  washing.      '2.  Slicing.      :\.  Washing.     4.  Drying. 

I.     X<i/(t  /////;/,    <>r     mi/,,  rlirin/    //W, i/i</.        As    it    come-    from    tin-    Wareholl-e,     the 

rubber   undergoes   the    process  of  softening.      It  is  then  too   tinn   and   hard   to  be 

wrought,  and  at  the  ordinary   temperature  of  our  climate  it  is  necessary  to 

it  whatever  may  be  the  form  of  the  block.     This,  the  most  simple  o|M-ration  of  all, 

consists  in  immersing  the  rubber  in  water,  heated  by  a  steam  jet  (a  wooden 

the  best  vessel),  and  keeping  it  in  this  bath  for  from  twelve  to  twenty -f«»ur  hours. 

With   certain  varieties  it  is  advisable  to  add  a  little  eaustie  >..da  to  the  water. 

Acidulated  water  is  not  to  be  recommended.     The  alkaline  ley  cleanMfl  the  surface 

better,  especially  any  re-entering  angles,  and  the  woody  fibre  is  better  disintegrated. 

A  sickening  smell  is  given  off  from  these  vats,  recalling  the  primitive  methods  of 

collection,    especially   in    case    of 

African  rubber. 

'2.  Slicing. — When  the  rubber 
is  sufficiently  soft,  the  large  blocks 
are  sliced.  They  are  generally  cut 
up  into  small  coarse  fragments  of 
3  to  5  cubic  centimetres  (say  1 1- 
to  2  cubic  inches)  in  volume. 
Those  kinds  which  come  to  the 
factory  in  very  small  lumps  do 
not  need  to  be  cut  up ;  they  pass 
directly  from  the  softening  vat  to 
the  washer.  The  slicing  is  done, 
either  by  hand,  by  means  of  a 


Fn;.  39. — Machine  for  cutting  up  raw  rubber. 


big  knife  with  a  long  blade  drawn  out  to  a  point,  or,  mechanically,  by  means  of 
a  circular  beater,  as  described  by  Heinzerling.  This  beater  consists  of  an  in-n 
wheel  of  30  centimetres  (say  12  inches)  in  diameter  and  l'U  centimetres  (say 
8  inches)  in  thickness,  provided  with  several  cutting  blades,  fixed  oblique  1 
going  beyond  the  periphery  some  millimetres,  and  working  as  shown  in  figure. 
The  wheel  is  driven  by  a  belt,  the  cake  of  rubber  is  placed  between  the  wheel  and 
the  palette,  working  in  connection  with  a  hinged  lever  attached  to  a  j»edal.  When 
the  workman  places  his  foot  on  the  pedal  and  adds  to  it  by  the  weight  of  his 
body,  the  inferior  rod  lowers,  and  the  lever,  by  means  of  the  palette,  pushes  the 
rubber  against  the  wheel.  To  stop  the  machine,  the  lever  is  drawn  behind  by  tin- 
hand  of  the  workman,  who  draws  his  foot  off  the  pedal;  the  latter  is  provided 
with  a  counterpoise  which  facilitates  this  movement.  The  wheel  revolves  at  great 
speed.  In  France,  different  machines,  based  on  the  mechanical  action  of  a 
circular  saw  without  teeth,  but  very  sharp,  are  used.  The  blade  of  this  saw  dijw 
into  a  small  trough  tilled  with  \\ater.  It  is  thus  kept  continually  moist  and  cool, 
to  prevent  adherence  or  heating,  and  enable  it  to  get  a  cutting  grip  of  the  rubber. 
•'».  H'-/x/< ///./.  This  ..peration.  the  essential  part  of  the  mechanical  tran- 
formations  \\hich  rubber  undergoes  during  purification  or  regeneration,  consists 
in  pas>ing  the  softened  rubber,  whether  cut  up  or  not,  through  very  )H,\Nerful 
machines  capable  of  freeing  it  from  foreign  bodies  imprisoned  in  it-  DIMIj 
which  would  be  prejudicial  to  any  further  treatment.  Tl,'.  old  pruceu,  that 
of  the  mortar,  is  now  obsolete.  The  German  process,  called  the  shredding 


138 


INDIARUBBER 


(a  raboter)  machine  process,  and  the  Dutch  process,  both  are  likewise  obsolete. 
The  British  process,  generally  adopted,  involves  the  use  of  the  shredding  or 
tearing  machine  (dechiqueteur  ou  e'craseur).  This  machine  consists  of  two  rolls 
of  hardened  cast-iron,  placed  horizontally  opposite  each  other ;  turning  in  opposite 
directions  and  with  differential  speed,  only  one  of  these  is  driven  directly.  It 
transmits  its  motion  to  the  second  by  straight  helicoidal  or  chevron  gearing 
according  to  force  required.  Sometimes  the  rolls  are  fluted  (covered  with  spiral 
hollows) ;  sometimes  they  are  smooth ;  sometimes  one  is  smooth,  the  other  striated 
or  fluted :  in  any  case  the  arrangement  is  the  same. 

British  and  American  types  of  washing  machines. — British  and  American 
factories  prefer  grooved  or  fluted  rolls.  The  grooves  in  America  are  made 
especially  of  a  spiral  shape ;  whilst  in  Britain  they  more  generally  intersect  in  the 
form  of  lozenges.  The  asperities  of  the  rolls  thus  facilitate  the  shredding ;  they 
penetrate  into  the  rubber,  and  crush  all  the  foreign  bodies  which  it  may  contain. 
The  two  rolls  (Fig.  40)  rest  upon  two  strong  cast-iron  supports  by  means  of 


FIG.  40. — Washing  machine. 

stuffing-boxes  fixed  in  the  spaces  left  vacant  for  the  purpose  in  the  casting.  The 
two  stuffing-boxes  of  the  roll  at  the  back  of  the  machine  abut  against  the 
building ;  the  two  stuffing-boxes  of  the  front  roll  are  supported  by  two  tightening 
screws.  The  two  rolls  are  driven  by  gearing  shown  in  the  drawing ;  they  revolve 
in  opposite  directions,  and  in  the  machine  illustrated  are  driven  by  an  intermediate 
shaft.  Washing  machines,  as  just  stated,  are  also  constructed  of  a  different  pattern, 
in  which  the  revolving  motion  is  directly  transmitted  from  one  roll  to  another. 

Tightening  and  slackening  the  rolls. — The  two  rolls  may  be  brought  in  contact 
by  manipulating  the  tightening  screws.  To  obtain  the  inverse  motion,  all  that 
has  to  be  done  is  to  slacken  the  screw ;  the  rubber  fed  into  the  machine  whilst  in 
motion  pushes  back  the  roll  by  the  simple  pressure  which  it  exerts.  Underneath 
the  rolls  is  a  wrought-iron  collecting  tank  covered  by  a  perforated  plate.  Water 
from  a  distributing  pipe  (Fig.  41)  flows  between  the  two  rolls,  and  the  wash  water 
runs  away  through  another  pipe  placed  in  the  bottom  of  the  tray.  This  water  is 
spread  automatically  on  the  periphery  of  the  rolls  by  a  pump  driven  by  the  motor 
shaft,  which  aspirates  it  from  the  tank  below  the  washer.  This  current  of  water 


TRANSFORMATION  OF  NATURAL  RUHBKU 


139 


t';irilit;iU-s  the  ••  \\ a-hin^  "  of  the  ruMier  it  dissolves,  or  removes  certain  impurities 
brought  to  the  surface  by  tin-  continuous  renewing  of  that  surface.  To  start  washing 

or  >hreddinur,  ;l  \,.|-y  small  quantity  »\  rubber  U  introduced  ljut\\c«-ii  tin-  roll-  whibst 
in  motion,  -ay  I  to  •_'  kilogrammes  < -ay  2£  to  4'j  11>.)  at  tin-  most,  according  to  the 
strength  of  tin-  macliiiir,  and  tin-  \sat-T  ta|.  i>  turned  on.  The  distance  is  regulat.-d 

to   3   to   5   ivntiiiH'tivs,  or    \r»\\\    I   to*'J  inches.      Tin-    roll,    i. -\..|\.-    in    i-oittiu-t    \\itli 


each  other,  the  sul>stan<v  i>  «lra\vn    in,  ••rushed   and   traii-forine.!    into  a   thin  >h«-et. 
which  is  jtasse.l  a  certain    iiuinl>ei'  of   times   throiii;h   the   rolls.       If   to.,   much  ^li«-ed 
rubber  were  ted  into  the    machines  at   onOS,  it   \\oiild    l»e    very  lial'le   t«-  l-i^-ak  them. 
The  rubber   is   crushed,  torn,  flattened,  laminated,  and   drawn    out,  the    \\;i>li 
finding    its  way  into   all    pores,    dislodges    earth\    matter,    and    carri-  foreign 

bodies  in  its  train.      The  resulting  product  is  a  kind  of  laeework,—  ei. 
the   surface  of  which  is  rugose  and  dotted  by  an  iniinite  number  of  asperities, 
separated  by  cavities  which  give  to  it  a  characteristic  appearance. 


140 


INDIARUBBER 


Size,  etc.,  of  rolls. — Machines  vary  in  size.  Generally  the  rolls  are  0'60  to  O65 
metre  (say  23^  to  25 J  inches)  long  and  0'40  to  045  metre  (say  15|  to  17f  inches) 
in  diameter ;  the  revolving  speed  is  then  eight  to  twelve  turns  of  the  one  to  three 
to  four  turns  of  the  other. 

Hollow  steam-heated  rolls. — In  certain  factories  the  rolls,  instead  of  being 
solid,  are  hollow,  and  so  designed  that,  as  occasion  requires,  a  current  of  steam 
may  be  injected  into  them.  They  then  serve  two  purposes.  All  varieties  of 
rubber  are  not  washed  with  the  same  ease.  Para,  as  it  contains  but  few  impurities, 
is  the  most  perfectly  and  most  rapidly  washed.  Greasy,  tacky  rubbers  are  not 
easily  freed  from  foreign  bodies,  and  one  is  often  obliged  to  give  up  the  idea  of 
eliminating  the  impurities  which  remain  glued  in  the  mass.  Some  Guayaquils 
are  especially  intractable.  Very  dry  1  rubbers  cannot  be  rolled  into  lacework,  the 
fragments  do  not  agglomerate  together,  and  in  certain  cases  they  come  out  of  the 
washing  machine  in  the  state  of  powder.  After  appropriate  washing,  the  shredded 


FIG.  42. — Rolls  for  washing  machines. 

lacework  or  sheet  contains  no  foreign  substance  except  water.     Drying  is  thus  the 
final  stage  of  the  "  washing  "  process. 

4.  Drying,  aeration,  and  illumination  of  drying-room — Loss  in  washing. — 
Washed  rubber  is  dried  by  spreading  the  "  skins  "  on  stretched  iron  wires,  or  in 
stoves  capable  of  being  heated  to  50°  to  60°  C.  (122°  to  140°  F.).  This  simple 
operation  requires  no  important  remark.  It  may,  however,  be  observed  that 
"greasy,"  "tacky"  rubbers  require  to  be  dried  at  a  low  temperature;  by  drying 
them  at  too  great  a  heat  their  natural  defects  would  be  accentuated,  the  skins 
would  be  torn,  would  fall  on  the  ground,  and  agglomerate  into  lumps,  from  which 
the  moisture  could  only  be  evaporated  very  slowly  and  with  great  difficulty. 
Good,  well  regulated  ventilation  accelerates  the  operation,  which  in  summer  is 
finished  in  a  few  days.  In  winter,  drying  naturally  takes  longer,  and  steam 
drying,  done  with  great  care,  assists  in  the  work.  In  regard  to  light,  there  is 
a  drawback  to  leaving  the  rubber  exposed  to  this  atmospheric  agent.  The  darker 
the  drying-room  is  kept,  the  more  valuable  is  the  resultant  dried  rubber.  Stor- 
ing the  washed  rubber. — When  dry,  the  rubber  is  lifted  off  and  formed  into 
bundles  by  folding  it  like  cloth,  or,  better  still,  by  rolling  it  up  on  itself.  The 


TRANSFORMATION    OF    NATURAL    kll.m  K 


Ml 


rubber  is  sto\\e<l   in   l.umlles   in   a  part  of  the  warehouse  uwod  Hjiccially  for  this 

|.m-|'o>e,  an. I    protected    t'n.ni   moisture  ami    li^lit,    \\li.-iv  it    remains  until"  riMjuin-d 

fur  industrial  purposes.     Loss  in  iveiyht  in  >'•'/>•/////»/  ,//,,/  ,/,///,/,/  ,,f  raw  n// 

Wa-hc-il  ami  dried  rubber  !"-«•>   in  wri^ht    in    tin-    process.      Tin-   «lill'i-ri  i 

tin-  \\eiijit  nt'  the  ra\\   ruM>er  ami    tin-  nrt   uri^lil    in  tin-  «lr\   H! 

//W/ /////•      ThU  factor  \.irie-   -iv.iily,  ami,  \\ith   intni'.r  kimU.  m.i\   riM  M   lii^h   »i« 

t'.o  |.,-r  criit.  «»f  the  initial  Nxri^ht  ;  ^U.M|  Borti  generally  looe   I •"•  i"  -<•  IHM 

The  toll. .\\iim  tablf  intli«Mt«->  th--  luss  in  tin-  6886  "I  -mu-  riil.l«-is.  '|'h«-  ti^nn-* 
arc  mil  at  all  uri\''ii  as  ronstant  or  al'soluto.  It  is  not  rare  to  meet  with  t\\«.  l-.t- 
of  the  same  ruMier,  8old  as  being  of  the  same  quality,  \vhi<-h  \ield  l«^se.s  which 
may  (litl'cr  to  the  extent  of  1">  to  '_'<)  |M-r  cent,  from  the  averages  indicated. 

TABLE  XXXII.— SHOWING  Loss  ON  WASHING  EACH  COMMKIXI.M.  UKA.M.  «.i 

CRUDE  RUUI.I  i 


Kind  of  Rubber, 

Loss  per 
cent. 

Kind  of  Rul.her. 

Loss  i»er 
cent. 

Para  

10  to  16 

Guatemala 

20  to  40 

Sernamby  .... 

15  to  35 

Assam  . 

10  to  30 

Mozambique  (spindles) 

15  to  25 

Java    . 

20  to  35 

Mozambique  (rose-red  balls) 
Colombia  .... 

15  to  25 
10  to  25 

Borneo 
Guayaquil 

10  to  45 
30  to  50 

Peru  (sheets)      . 

30  to  40 

Senegal,  Soudan 

20  to  35 

Good  dried  washed  rubber  contains  about  0'5  to  3  per  cent  of  impurities. 
Although  trade  exigencies  lead  to  the  use  in  factories  of  imperfectly  dried  rubber, 
it  would  be  highly  desirable,  from  a  manufacturing  point  of  view,  only  to  use  an 
absolutely  dry  substance. 


FIG.  43.— Washer  for  iudiarubber  (Werner  Pfleiderer). 


CHAPTER  VII 

MECHANICAL   TRANSFORMATION   OF  NORMAL   RUBBER   INTO 
MASTICATED  RUBBER 

Definition  of  mastication. — As  it  comes  from  the  washer,  the  dried  rubber  is 
ready  to  be  treated  with  solvents.  But  unless  it  is  to  be  used  industrially,  in  the 
state  of  solution,  washed  rubber  has  no  direct  application :  it  is  simply  a  stage 
through  which  the  substance  passes  before  being  transformed  into  manufactured 
products.  What  the  washing  machine  has  dissociated,  the  masticator  or  kneader 
has  to  reunite :  the  normal  rubber  is  thus  freed  from  the  air  and  moisture  which 
it  contains  in  its  pores,  and  a  more  dense  and  more  homogeneous  product  is 


^«^^Mm^» 

^vxxxxxvvvxxx^^ 

FIG.  44. — Mixer — Horizontal  rolls  in  juxtaposition  (elevation). 

obtained.     This   result   is   realised   by   forcing    the   different    portions    together, 
mechanically,  so  as  to  agglomerate  them  together  into  one  single  whole. 

Agglomeration,  mastication,  or  kneading. — As  in  the  "washing"  process, 
obsolete  superannuated  processes,  forsaken  by  actual  practice  on  the  larger  scale, 
have  not  been  described.  The  old  kneading  process  of  Thomas  Hancock  need  only 
be  mentioned.  It  is  unnecessary  to  describe  the  construction  of  the  wolf  or  devil, 
even  when  furnished  with  all  the  improvements  so  ingeniously  brought  to  bear 
upon  it  by  Auber  and  Gerard.  The  "  deviling  "  of  indiarubber  requires  much  time, 
and  gives  rise  to  an  elevation  of  temperature  prejudicial  to  its  quality ;  it  requires 

142 


TRANSFORMATION   OF   NORMAL   RUBBER 


143 


a  considerable  e\pt -nditure  of  force,  which  for  the  kneading  of  10  to  15  kilo- 
uaannm •-  ( -IN  •_'•_'  t<>  :n  11>.)  is  not  less  than  5-horse  power  (nominal).  Moreover, 

tin-    proceflfl    is    beriiniing   more   ;in<l    more   obsolete,    ;in«l    iVim-i.--,  t-.juij.jK-<l   aft- 
nmn-  iv. -nit   system  ha\e  advantageously  replared  it    liy  ;i  mi\.-r  \\ith    -n,<,\,d  |-,,||.. 
The    ina-tirator   is   eoinparat i\e|\   .-a-ily  dii\en,  tin-   «>|M-r;it imi    is    nnn-li    nimv   r.i-il\ 
watehed,    and     tin-    heating    of    the    nilil..  <ided    ;i^    \sell    as    ;ill    tin- 

^eniencee  incidental  thereto.     There  wo  two  kinds  of  mMticftton:  tin- 

with    parallel    hori/ontal    rolls    in    jii.xtaiM.sition,    ;in<l    tin-   iua>ticat«.r>    \\ith 
iinposol    r<»lls.      The  latter  juv  not  used  SO  much  in  I'Yance.      Figs.    11  and  45  show 

a  masticator  with  rolls  in  juxtaposition,  in  a  horizontal  MM*  It  w  the  American 
washing  machine  invented  by  Goodyear,  \\ith  this  difference,  ho\\c\cr,  that  th-- 
cylinders  move  at  the  same  speed,  the  rolls  are  always  hollow,  and  can  therefore 

l>e  heated  by  steam. 

r'igs.  46  and  47  represent  a  machine  with  superimposed  rolls. 

Description. — a  a  are  the  hollow  rolls;  the   lower  one  moves  in   the  frame  /,  /,. 


FIG.  45. — Mixer— Horizontal  rolls  in  juxtaposition  (plan). 

whilst  the  upper  roll  is  so  arranged  that  it  may  be  brought  near  to  or  withdrawn 
from  the  lower  roll  by  a  lever  and  counterpoise.  The  weights  c  lower  (by  the  levrr 
d,  and  the  rod  e),  the  levers/,  which,  controlled  by  the  rods  <;,  press  upon  the 
supports  of  the  upper  roll,  and  cause  it  forcibly  to  approach  the  lower  roll.  The 
upper  roll  thus  yields  to  an  abnormal  force,  such  as  would  be  caused  by  stones  in 
the  rubber.  Damage  to  one  roll  or  the  other  if  both  were  fixed  is  thus  avoided.  To 
regulate  the  machine  the  extremities  of  the  levers  d  are  furnished  with  chains  h  A, 
winding  on  shafts  i  i,  and  are  tightened  by  &,  wrought  by  the  lever  /.  The  rolls 
are  heated  by  the  steam  pipe  m ;  the  excess  of  steam  and  the  condensed  water  are 
evacuated  by  blow-off  cocks  n  n.  The  steam  pipe  is  regulated  by  a  screw  valve. 
The  dimensions  of  the  rolls  are  generally  1  '3  metre  (say  4  feet  3  inches)  long  by 
0'45  to  0'50  metre  (say  17|  to  19|  inches)  in  diameter. 

Recent  forms  of  masticators. — In  certain  recent  forms  of  masticators  the 
levers  and  counterpoises  are  replaced  by  spring  compressors  (which  can  be 
compressed  at  will),  fixed  in  the  stuffing-box  of  the  upper  roll.  They  serve  the 
same  purpose  as  the  old  system ;  they  hinder  the  rolls  from  being  damaged  by  the 
interposition  of  a  hard  resistant  body.  The  surface  of  one  of  the  rolls  is  smooth 


144 


INDIARUBBER 


and  uniform,  whilst  the  other  bears  all  over  its  circumference  and  parallel  with  its 
axis  deep  grooves  of  about  15  millimetres  deep  and  30  millimetres  wide  (0'59  by 


FIG.  46. — Mixer,  with  superimposed  rolls  (elevation). 

1*18  inch).     The   angles  which  these  grooves  make  with  the  surface  of  their  roll 
are  not  equa1,  but  alternately  obtuse  and  acute.     The  acute  angle  comes  first  in  the 


FIG.  47. — Mixer,  with  superimposed  rolls  (side  view). 

contact  with  the  smooth  roll  during  the  working  of  the  machine.  These  rolls 
revolve  at  unequal  speeds,  the  grooved  roll  making  two  revolutions  to  every  one  of 
the  smooth  roll.  When  the  laceworks  of  rubber  from  the  washing  machine  are 


TRANSFORMATION   OF   NORMAL   RUBHKK 


L46 


the  mils  are  tii'.-t     heated,   then    ;i.s    nmrh  i,|'    th,-    ^il-t.m.-  ||   ;•    ,    m    • 
is  ^radualfy    ted    into   tin-   maehiiie,   tliat    is,    1  1    to   'I'l   II*.    for  rolls  of    tin-  aliove 
dimensions.       Tin-    mai-hine  \\hen    eh..  !art«-d,  ami     is  HOOI1  U8    it  Woik->  it    i> 

gradually  tightened,  so  as  only  to  leave  a  space  of  a  few  millimetres  bet\\»-«-n  tin- 
rolls.  The  rul.l.rr  is  thus  constantly  forced  to  t-nti-r  the  grooves  \\lii<-h  come 
successively  in  front  of  tin-  surlacr  .,f  th.-  >niooth  roll,  and  it  is  eiirr-Mi.-ally  drawn 
in  \>y  the  acute  angle  of  the  groove  which  catches  there.  The  i 


i 


o  be 

II 


P 

i! 


and  ivpiMti-d  mastication,  wliicli  soon  renders  tin-  mass  of  nil>l»rr  very  homogeneous. 
The  rolls  generally  revolve  with  a  speed  of  twenty  revolutions  a  minute.  The 
substance,  once  masticated,  is  again  passed  between  the  rolls,  and  the  treatment 
repeated  as  many  times  as  necessary. 

Necessity  r'»r  care  in  mastication — >'/«»•/•//  /////.<//»v///o?i  of  African  rubbers. — 
The  mastication  of  rubber  is  a  most  important  operation,  and  requires  great  care 
to  avoid  grave  defects  in  the  rubber.  If  the  rubber  be  but  imperfectly  dried,  a 


10 


146  INDIARUBBER 

mastication  of  forty  to  forty-five  minutes  is  required  to  eliminate,  by  evaporation, 
the  excess  of  water  present.  In  many  factories  rubbers  from  different  sources  are 
masticated  separately.  To  the  African  sorts,  which  tend  to  become  tacky  under 
the  action  of  the  hot  rolls,  a  little  talc  (hydrous  silicate  of  magnesia)  is  added, 
and  the  steam  is  carefully  regulated.  Moreover,  they  require  to  be  masticated  for 
a  much  longer  time  than  good  sorts,  and  particularly  much  longer  than  Para. 

Incorporation  of  sulphur  and  colouring  principle. — After  mastication,  before 
being  blocked,  the  indiarubber  may  be  "  mixed  "  by  the  same  rolls  as  are  used  for 
mastication.  "  Mixing  "  is  the  introduction  into  the  rubber  of  the  sulphur,  or  the 
solid  derivatives  thereof  required  for  vulcanisation,  and,  if  need  be,  of  different 
mineral  or  tinctorial  substances  necessary  for  each  special  use  to  which  the  rubber 
is  to  be  put.  Vulcanisation  can  only  be  proceeded  with  after  that  has  been  done. 

Blocking — Passing  between  the  hot  rolls. — The  sheets  or  bundles  of  rubber  as 
they  come  from  the  masticator  are  very  irregular.  It  is  impossible  to  utilise  them 
in  that  state.  They  do  not  possess  the  desired  texture  :  certain  portions  are  more 
nervous  than  others,  and  sheets  made  from  them  would  swell  and  become  useless. 
The  rubber  must  therefore  be  subjected  to  a  fresh  process,  especially  if  it  be  desired 
to  make  cut  sheet  and  English  sheet.  This  operation  is  called  blocking.  The 
masticated  rubber  is  converted  into  regular  shaped  plates  by  being  passed  between 
two  hot  rolls — at  a  temperature  of  80°  C.  (176°  F.) — the  space  between  which 
varies  between  3  and  40  millimetres(0'1179  and  1'5720  inch).  Fairly  equal  sheets 
are  so  obtained. 

Hydraulic  pressure  of  the  rubber  in  frames  after  jessing  through  hot  rolls. — A 
certain  number  of  sheets  imparted  are  made  into  one,  whilst  the  heat  during 
rolling  still  causes  them  to  be  adhesive,  and  they  are  put  into  a  cast-iron  frame  of 
25  to  30  centimetres  wide  (say  10  to  12  inches)  and  2  metres  long  (say  6J  feet). 
They  are  pressed  very  forcibly  with  a  hydraulic  press,  and  let  cool  under  pressure. 

Storage  of  blocked  rubber — Changes  produced. — After  a  few  days  the  rubber 
sheets  are  taken  from  the  frames  and  piled  in  a  cool  cellar,  where  they  lie  for 
several  months.  During  this  prolonged  storage  a  change  supervenes  in  the  soft 
matter,  which  is  present  in  greater  or  less  abundance  in  each  parcel  of  rubber  in 
admixture  with  the  more  nervous  portions.  The  degree  of  hardness  is  equalised, 
and  the  mass  becomes  thoroughly  homogeneous.  It  is  then  cut  into  thin  sheets. 
No  marbling  nor  striae  due  to  the  greater  or  less  nerve  of  the  mixture  of  rubbers 
forming  the  block  can  any  longer  be  perceived.  By  prolonged  treatment  with 
masticating  rolls,  the  whole  mass  may  be  made  still  more  homogeneous,  but  this 
treatment  would  inevitably  result  in  heating  and  prejudicially  unnerving  the 
rubber  intended  to  be  used  in  the  normal  condition.  The  rubber  thus  blocked,  and 
stored  in  the  cellar  during  several  months,  naturally  assumes  the  form  of  the  mould 
employed.  Cubical  parallelopipedical  blocks  are  made  of  the  size  indicated,  and 
cylindrical  blocks  of  0;3  to  0'4  metre  (12  to  15f  inches)  in  diameter  and  0'4  metre 
(15|  inches)  in  height.  It  is  used  in  the  making  of  sheets  or  discs,  from  which 
ribbons  are  cut  by  a  mechanical  knife  for  making  block-rubber  thread,  but  this 
manufacture  is  now  almost  entirely  abandoned. 

English  sheet. — The  great  use  of  blocked  rubber  consists  in  the  manufacture  of 
cut  sheet  and  English  sheet.  The  rubber  which  has  been  stored  sufficiently  long  in 
the  cellars  is  used  for  this  purpose.  It  is  thawed  gently  in  the  stove,  then  it  is 
made  to  stick  with  a  solution  made  from  spirits  of  turpentine,  and  more  especially 
benzol,  on  the  car  of  a  saw,  in  which  the  blade  of  the  saw  has  been  replaced  by  a 
blade  without  very  sharp  teeth ;  a  jet  of  weak  soapy  water  continually  moistens 
the  blade  to  prevent  it  from  heating  and  adhering  to  the  rubber.  To  obtain 
sheets  of  double  width,  two  blocks,  by  means  of  a  little  of  the  previously  men- 
tioned solution,  are  soldered  together  by  their  extremities,  which  have  been  cut 
exactly  at  a  right  angle.  The  cutting  is  done  just  as  in  the  case  of  a  single  block ; 
it  only  requires  a  car  of  double  the  length.  In  another  system  the  cubical  block 
is  fixed  on  a  sliding  plate  like  the  plate  of  a  planing  machine.  The  plate  is  brought 
mechanically  to  the  front,  whilst  the  knife,  propelled  by  a  to-and-fro  movement  at 


TRANSFORMATION   OF   NORMAL   RUBBER 


147 


the  rale   uf    I  MX)    to  L'OOl)    cuts    a    minute,  -lice,  nil'  a  thin  sheet   of    rubU-r.      The 
•  f  the  machine  are    l.n  .ii;_dit    hack    to   their    original  po>ition,  the    I  «|ock  -carrier 
plate  is  loaded  with   a  quantity  corres[K»nding   to   the   thiekne--    dc-ir.-d.  and 
t  lie   \\  hole   has   been   Used   up. 

J  HI  lull's   sheet  or  continuous    cut   sheet. — The   cutting   of    cylindrical    block* 


1  i<;.   HI.  -Machine  for  cutting  a  continuous  sheet  of  ruhher. 
Lehlanc  system  (elevation). 

producing  so-called  continous  cut  sheet  differs.  This  system,  in\ented  byiluibal, 
(•'insists  in  taking  a  cylindrical  block  and  imparting  to  it  a  rotary  motion  round 
its  own  axis,  whilst  a  knife  blade  constantly  moistened  by  a  jet  of  water  cut>  it 
spirally.  The  length  of  the  sheet  thus  produced  varies  with  the  thickness;  it 


FIG.  50.— Machine  for  cutting  a  continuous  sheet  of  rubber. 
Leblanc  system  (plan). 

sometimes  attains  a  length  of  500  metres  (1640  feet).     Figs.  49  and  50  represent 

the  ele\ation  and  plan  of  (  Jiiibal's  machine  as  made  and  improved  by  Leblan.-. 

Feature*  of  tl,,    <;,<ii,,il  LMim-  ni<t<-l<i,i> .     As -the  cylindrical  block  diminishes, 
the  Speed  of  rotation   increases,  so  that    the   surface    in   contact  with  the   kir-1 
serves  a  uniform   speed  during  the  whole  of   the   operation.     This  arrangement  i 
intended  to  produce  sheets,  the  rays  of  which,  marked  by  the  knife,  are  perfectly 


148 


INDIARUBBER 


equidistant.  Leblanc's  machine  produces  thinner  sheets  than  hitherto.  They  can 
be  made  as  thin  as  0'18  millimetre,  whilst  a  little  more  than  ten  years  ago  0'30 
millimetre  was  the  thinnest  that  could  be  made. 

It  was  formerly  held  that  to  obtain  a  perfect 
cut  sheet  very  good  Para  rubber  must  be  used, 
and  the  blocks  cut  at  a  very  low  temperature. 
The  second  part  of  this  assertion  may  be  well 
founded.  But  as  to  the  first,  the  recent  researches 
and  analyses  of  Henriques  show  that  such  is  not 
at  all  the  case. 

Cut  sheet  is  not  treated  with  talc,  but  gently 
rubbed  with  a  very  clear  solution  of  soap  in  hot 
water.  This  solution  on  cooling  coagulates,  form- 
ing a  very  thin  layer  on  the  surface  of  the  sheets, 
which  hinders  them  from  adhering  together. 

Apparatus  for  ascertaining  thickness  of  india- 
rubber  sheets. — This  apparatus  (Fig.  51)  registers 
automatically  with  mathematical  precision  the 
thickness  of  every  description  of  rubber,  caout- 
chouc, web  fabrics,  felt,  paper,  cardboard,  etc. 
The  machines  can  be  supplied  graduated  in  inches. 
Fig.  52. — This  is  made  of  German  silver  and 
provided  with  a  sensitive  screw  and  large  measur- 
ing drum.  Fastened  by  two  springs  on  a  round  base,  the  apparatus  is  easily 
detached.  Graduation:  0  to  10  millimetres;  divisions  intOy^;  (a)  with  visible 
screw,  (b)  with  masked  screw. 


FIG.  51. — Schopper's  "  Automatic 
thickness  gauge. 


FIG.  52. — Micrometer  for  rubber 
(Schopper,  Leipzig). 


FIG.  53. — Micrometer  for  rubber,  etc. 
(Schopper,  Leipzig). 


Fig.  53. — Made  of  German  silver  and  provided  with  a  sensitive  screw. 
Graduation:  0  to  10  millimetres ;  divisions  in  yj^;  (a)  with  visible  screw, 
(b)  with  masked  screw. 


1        2      3       4       5      6      7     8     9     10  11    i2  13  14  15  16  17  18 

Thickness  in  millimetres. 

4.J5        3.26      2.58      2.35      1,85    1,66     1,40    1.140,960,83    0.62   0,54  0.44  0.41  0,37  0.33  0.20  0.18 


Illllllll 


FIG.  54. — Diagram  of  the  different  thicknesses  of  English  sheet  rubber. 

Use  and  application  of  sheet  rubber. — These  sheets  are  used  in  the  manufacture 
of  a  number  of  small  articles — tubes,  bracelets,  rings,  balls,  pears  for  surgical 
appliances,  air  cushions.  Method  of  manufacturing  sheet  rubber  into  commercial 


TRANSFORMATION   OF   NORMAL   RUBBER 


149 


IAI.*:*?! 

<—  _=  o  •*•*  S«O  c*^ 


150 


INDIARUBBER 


,/,7/Wt'*. — It  is  very  easy  to  make  these  different  objects:  the  two  edges  are  cut  a 
little  obliquely  and  the  two  sections  brought  together  with  a  little  pressure ;  they 
join  immediately,  if  care  be  taken  to  run  over  those  portions  with  a  brush  which 
has  been  slightly  dipped  into  benzol,  which  is  left  to  evaporate  before  uniting  them. 
Afterwards  the  point  where  the  junction  has  been  made  is  struck  witli  a  small 
round-ended  hammer,  and  the  joint  is  as  solid  as  if  the  sheet  had  not  been  cut.  It 
is  necessary,  if  the  sheet  has  been  "frozen,"  to  "thaw"  it  either  on  the  steam  table 
or  in  a  stove  before  starting  to  the  work.  It  is  only  then  that  it  regains  all  its 
adhesive  properties.  Cut  sheet  is  not  made  solely  from  pure  rubber.  It  is  also 
made  from  rubber  in  admixture  with  other  substances ;  in  such  cases  the  powders 
or  colouring  materials  are  mixed  with  the  rubber  in  masticators  with  special  rolls, 
and  the  mixture  so  obtained  is  treated  like  pure  rubber,  that  is  to  say,  blocked, 


FIG.  56. — Machine  for  cutting  circular  sheets  or  "washers." 


frozen,  and  then  cut.     Before  being  put  on  the  market,  all  articles  manufactured 
from  English  sheet  have  to  be  vulcanised  by  special  processes. 

Mixers  or  crushers — Rolls — Guide  plates — Collecting  tank — Shafting. — The 
mixer  (Fig.  57)  consists  essentially  of  two  horizontal  cast-iron  rolls  placed  alongside 
each  other,  turning  in  opposite  directions  and  at  different  speeds.  The  two  rolls, 
20-inch  diameter,  are  hollow  with  smooth  surfaces ;  they  rest  on  cast-iron  founda- 
tions by  horizontal  bearings  fixed  in  the  spaces  left  vacant  for  the  purpose.  The 
two  bearings  which  support  the  front  roll  are  acted  on  and  brought  near  to  the 
other  roll  by  two  strong  tightening  screws,  visible  on  the  front  part  of  the  machines, 
the  bearings  of  which  abut  against  the  framework.  The  inverse  movement  takes 
place  of  its  own  accord  by  undoing  the  screw,  for  the  substance  introduced  between 
the  two  cylinders  presses  against  the  mobile  roll  and  pushes  it  back.  Suitable 
guides  placed  between  the  rolls  prevent  the  substances  from  coming  out  or  slipping 
on  to  the  bearings  or  shaft  on  which  the  rolls  turn.  Underneath  there  is  placed 
a  sheet-iron  collecting  tank  (not  shown),  intended  to  receive  the  material  as  it 


TRANSFORMATION   OF   NORMAL   RUBBKR 


151 


• tefl  "lit  ot  the  niarliinr,  \\liidi  is  ilri\i-n  1>\  -."Mrini:.      In  iu;iny  of  tbefle 

tin-    rotar\  motion  is  imt  trunsmittnl  direct   f'nun  tin-  ..n,-  r,,||  to  tin-  «»tln-r,  ais  >hn\\n 
lien-,  but  I »v  an  intrriiH'iliati-  -liat't. 

Hnt  ,,//,/,-,,/,/  ,•„//.<.       'I'll.-  tuo    rolls    a iv    hollou,  :linl   iua\    U-  Ii.-al.-.|  1,1 


FIG.  57. — Rickkers'  crashing  mixer. 

will.  A  pii>e  runs  along  the  outside  of  each  roll  to  the  opposite  end  from  whence 
it  entered,  communicating  (1)  with  a  supply  of  cold  water,  and  (2)  with  the  steam 
boiler,  so  that,  by  opening  one  or  other  of  the  taps  which  regulate  these  conduits. 

ritlirr  steam  or  cold  water  is  shot  into  the  roll.     The  condensed  water  is  run  nil' 


FIG.  58.— Large  calibre  mixer  of  the  Birmingham  Iron  Foundry  (Connecticut). 

through  a  blow-off  cock.  The  pipe  system  passes  through  a  layer  of  tow  pressed 
against  it  by  suitable  means.  The  working  of  the  rubber  between  the  rolls 
develops  a  considerable  amount  of  friction,  and,  as  the  cylinders  become  gradually 
more  and  more  hoatrd.  an  injection  of  cold  water  is  required  to  bring  them  to  the 


152 


INDIARUBBER 


desired  temperature.  There  are  certain  kinds  of  work,  namely,  crushing  indiarubber 
waste,  which  can  only  be  done  quite  cold.  If  the  admixture  of  substances  added 
to  the  rubber  be  soft,  it  causes  the  block  to  be  wrought  to  become  more  ;md  more 
plastic,  and  consequently  sticky.  If  the  mixture  were  not  at  a  suitable  temi>erature 
the  paste  would  adhere  to  the  rolls,  and  would  render  work  impossible.  The  treat- 
ment to  which  the  mixers  subject  the  rubber  is  not  a  laminating  process,  as  might 
at  first  sight  be  supposed :  it  is  a  spreading  out  and  a  crushing  process,  produced 
by  the  roll  revolving  with  the  greatest  velocity  on  the  mass  retained  in  part  by 
the  roll  revolving  with  the  slower  speed.  It  is  a  work  of  the  same  kind  as  that 
of  the  muller  on  the  marble  slab,  where  the  painter  "rubs  up"  the  mixture  of  oil 
and  powdered  pigment.  Mixing  is  effected  by  introducing  the  masticated  rubber 
between  the  two  heated  rolls  of  the  mixer.  When  it  has  acquired  a  suitable  degree 


FIG.  59. — Heavy  two-roll  calender  driven  by  patent  friction  clutch. 


of  malleability,  the  powders  to  be  used  in  the  mixture-are  gradually  spread  over  the 
surface  of  the  sheet  of  rubber  around  the  far  roll.  A  large  proportion  of  the 
powders  fall  into  the  collecting  tray,  and  are  picked  up  by  a  shovel  and  brush  and 
passed  between  the  rolls  again  until  the  whole  is  well  incorporated  with  the  rubber. 
The  pasty  mass  is  passed  through  the  mixer  until  it  has  become  quite  homogeneous. 
Finally,  the  two  rolls  are  tightened  up,  and  it  is  again  passed  through  once  or  twice 
so  as  to  crush  any  particles  well  which  might  escape  the  action  of  the  machine.  The 
substance  issues  as  a  thin  sheet,  which  is  rolled  upon  itself  into  a  large  block  for 
subsequent  operations.  All  these  mixed  rubbers,  whatever  may  be  the  nature  of  the 
materials  incorporated,  are  passed  through  the  crushing  mixer. 

Automatic  mixer. — This  machine,  described  by  Bobet,  is  intended  to  lift  up 
automatically  the  substances  which  fall  into  the  collecting  tray  of  the  ordinary 
crusher.  Moreover,  it  does  not  differ  from  the  machine  just  described,  except  by 


TRANSFORMATION   OF   NORMAL   RUBBER 


the  addition  of  an  endless  apron  of  strong  canvas,   tiirnini:  underneath  the  roll* 

in    tin-    plan-    usually    occupied    by    tin-    collectin-    tra\.      Tin      u 

substances  it  collects   al>o\e   tin-    rolls   and    tilts   tlirm    uniformU   U'tween   till-   l\\«i 

This  arrangement  entires  constant  and  regular  feeding  and  a  homogtaeoas  mixture ; 

.  the  operation  js  accelerated  sin.-.-  all  the  mixing  -urlace  i>  utilised.  With 
the  ordinary  machine,  \\heii  the  sul»>lanceS  \\hidi  liavr  fallen  into  tin-  collecting 
tray  are  picked  up  with  a  shovel  and  a  brush,  their  re-spreading  out  w  irregular, 
ami  en-tain  portion-  of  the  >heet  of  nil. her  do  not  get  siny tiling.  Theoretically, 
then  tore,  this  machine  presents  some  advantages,  but  its  use  does  not  appear  to 
have  been  consecrated  l.y  time  and  practice. 

/ii>//fif  (In  initiated)  or  <//-<it>'/i  <>ut  sheets — Calendering. — Instead  of  cutting  thr 


FIG.  60.— Three-roll  calender. 

rubber  blocks  with  the  machine,  they  may  also  be  laminated  into  sheet  rubber  by 
means  of  calenders.  The  calender  is  a  machine  much  used  in  the  paper  and  textile 
trades,  and  consists  essentially  of  three  to  six  rolls  turning  alternatively  in  inverse 
directions,  the  one  in  the  direction  of  the  hands  of  a  watch  and  the  other  in  t hi- 
re verse  direction.  In  small  factories  they  sometimes  use  calenders  with  two 
hollow  rolls.  Fig.  59  represents  one  of  these  machines  of  British  construction. 
.In  the  3-roll  calendar  (Fig.  60)  the  middle  roll  is  the  driving  roll,  and  is  driven 
directly  from  an  independent  motor.  The  two  others  of  the  same  diameter  as  the  first, 
by  two  straight  or  helicoidal  pinions.  The  rolls  are  generally  smooth  :  their  speed 
is  not  uniform.  The  top  and  bottom  rolls  have  some  teeth  less  than  the  driving  roll ; 
the  rubber  is  thus  flattened,  laminated,  and  drawn  out.  The  distance  between  the 
rolls  can  be  adjusted  at  will  to  j1^  millimetre  by  a^tiy-wheel  wrought  by  hand. 


154 


INDIARUBBER 


Wooden  knives  lined  with  zinc,  the  shape  of  which  is  a  triangle,  with  two  curved 
sides,  are  fixed  between  the  rolls  to  limit  the  size  of  the  sheet.  The  hollow  rolls 
are  generally  made  of  high-class  steel,  are  of  an  absolutely  perfect  surface,  and  are 
heated  by  steam  or  hot  water  during  the  whole  duration  of  the  operation  ;  they  may 
intercommunicate  with  this  end  in  view,  the  heat  can  thus  be  varied  as  required. 
The  temperature  of  the  rolls  greatly  affects  the  uniformity  of  the  sheets.  Arrange- 
ments are  therefore  made  for  admitting  cold  water  through  the  end  axis  of  each 
roll,  and  there  is  a  pipe  for  discharging  spent  steam.  The  spent  steam  may  be 
recovered  as  it  is  issued  from  the  rolls  by  leading  it  to  the  water  feed  tanks  or  to 
the  washing  vats.  Before  catching  hold  of  the  mass  by  the  rolls  the  foreman 
calenderer  makes  sure  that  his  machine  is  at  the  right  temperature  by  circulating 


FIG.  61. — Six -roll  calender. 

steam  in  it  for  a  few  minutes  ;  then,  when  the  cake  comes  from  the  mixer  sufficiently 
homogeneous,  it  is  passed,  whilst  still  hot,  into  the  calender,  and  at  first  between 
the  two  top  rolls  separated  rather  far  apart  at  the  outset,  and  through  the  posterior 
side  the  rubber  passes  slowly  with  a  peculiar  noise.  The  rubber  is  laminated  and 
converted  into  a  sheet,  and  is  drawn  through  by  the  middle  roll  to  undergo  a 
second  lamination  between  the  second  roll  and  the  third  one  at  the  bottom ;  a 
vertical  section  of  a  calender  at  work  would  show  the  rubber  as  a  sinusoid.  The 
latter  is  a  little  nearer  to  the  middle  roll  than  the  top  one.  A  small  heap  is  thus 
formed  of  the  excess  of  material  from  the  first  and  second  rolls  (first  lamination). 
But  if  small  quantities  of  imprisoned  air  exist  in  the  original  substance,  and  have 
escaped  in  the  first  lamination,  forming  an  air-bell  in  the  thickness  of  the  sheet, 


TRANSFORMATION   OF   NORMAL   RUBHI-k 


these  IK-US  Invak   their  thin  envelopes  \\hen  theexceaaof  rubU-r  forms  in  a  heap 

in  front  nf   tin-    lo\\er   r«ills.      Tin-   -«•»•• .ml    lamination    tlirn-toi.-  \i-ld-   .1   sln-rt   fret- 
from   air  IK-MS.     Tin-  o|H-rati"ii  is  repeat'-d  until  a  |. la-tic  mass  is  ol.taim  d       A  •di-at 
sheet   is  rereised  ..n  .1  talced  taMe.  l.iit,  if  of  a   cnl;iin   length,  tip      ! 
from  tin-    rolls    is  taken    up    l.\   a  \\«-t  rli.th,  ami    to    pie\.-nt   agglutination    is   n,||rd 
with    it    on    to    a    spindle.      Calenders    equipped    \\ith   f..ur    rolls   an-   likuwiflO  con- 
struct"«l.       If    thrir    working    !•«•    inon-    com|.liratr.|    ami    tln-ir   cost   gr« 
machines  should  give  a  BUpcrinr  product    to  tin-  preceding,  from  th<-  fart   tliat    tin- 
sheet    is    moiv    j.iirr    and    frt-.-r    from    air  U'lls,    so   dreaded    l»y  the    iii:uiiifiirtun-r. 
Ki.^s.  \]~2  and  »',:;    ivprrsriit    calenders  with    four   mils      The    j.rocess    may  la-1 
hours;   w«-l.s  :.<)  to  65  feet  in  length  are  thus  produced,  1  •:>,  o-."i,  Q  :;  milli- 


Fio.  62.—  Four-roll  calender.     A,  A 


A.,  are  four  cast-iron  hollow  rolls  into 


which  either  water  or  steam  can  be  injected  ;  A  and  Aa  can  be  respectively  mored 
closer  or  further  away  from  Al  and  A3  by  gearing  wrought  by  the  wheels 
C,  Clt  C2. 

metres  thick.     During  the  o}>eration  the  thickness  is  constantly  gauged  to  keep  it 
mathematically  exact. 

friction  calender.  —  The  friction  calender  is  >imply  a  calender  with  three  hollow 
rolls,  heated  internally  by  a  current  of  steam.  It  does  not  differ  from  the  ordinary 
calender  except  in  its  speed.  The  central  roll  turns  twin-  ;w  quick  as  the  two 
others.  This  result  is  obtained  simply  by  the  use  of  a  cog-wheel,  with  a  diameter 
equal  to  half  that  of  the  two  other  wheels  geared  on  the  upper  and  lower  rolls. 
Sometimes  the  three  rolls  are  not  in  the  same  vertical  plane.  This  machine  serves 
to  stretch  a  very  thin  layer  of  rubber  over  the  fabrics  intended  for  the  manufacture 
of  hose-pipe  and  transmission  belts.  A  fabric  which  has  been  subjected  to  friction  in 
this  way  on  one  of  its  faces  may  afterwards  be  put  through  the  calender  to  i 


156 


INDIARUBBER 


a  thicker  layer  of  indiarnbber,  thus  making  sure   that  the  calendered  sheet  will 
adhere  firmly  to  the  fabric. 


FIG.  63.— Four- roll  calender. 


The  horse-power   required  to  drive   calenders. — This   force,   derived  from   an 
independent  motor,  is  rather  great,  especially  when  starting  with  a  block  of  very 


I 
FIG.  64.  ^Six-roll  double-effect  calender. 


TRANSFORMATION    OK    NORMAL   RUBBER 


iH-rvi.il>,  mill  riiM»iT.  Tin-  speed  nf  tin-  P. 11-  i-  10  tQ  80  revolutions  .1  immiU-. 
The  h-T.-f  | >o\\er  averages  10,  but  may  suddenly  reach  'Jo.  l^arge-uized  «^>«f>4ftrf 
revolve  at  about  •'•  centimetre*  per  second,  the  force  absorbed  varies  from  15  to  25- 
h<>rse  po\\rr.  When  tin-  number  <>t  mil-  is  four  or  five,  thrir  tenijierature  U* 
brought  to  GO"  to  75  ('.  From  three  to  four  persons  an*  n -'luned  to  attend  i->  a 
calender.  Iced  tin-  rubber,  adjust  the  rolls,  regulate  tin-  «li-t.uice  between  the 
knives,  gauge  the  thickness  of  the  sheet,  roll  it  up,  receive  it,  drive  the  motor, 
and  attend  to  the  clutches.  These  machines  are  generally  driven  \ty  a  special 
iidjuivnt  steam  m^inr,  aii  rnirinr  with  two  ol»li«|in-  cylinders  with  steam  of 
(•  kttogHUnmOfi  JMM-  stj.  cm. 

si i- mil  •••i/'-mlt-r  n'ltfi  double  effect. — This  machine,  of  more  recent  invention, 


FIG.  65.— Six-roll  douhle-Hu-ct  r.-iK-inlrr. 

is  constructed  by  the  Birmingham  Iron  Foundry,  U.S.A.  Figs.  61,  64,  and  6.0 
sent  this  powerful  machine  in  three  ditlerent  positions.  Without  occupying  greater 
space  than  the  ordinary  three-roll  calender,  it  does  double  work,  and  may  be 
used  either  as  an  ordinary  calender,  or  as  a  friction  calender,  <>r,  finally, 
simultaneously  as  an  ordinary  calender  and  friction  calender.  According  to  tin- 
work  of  the  factory.  A  thin  sheet  of  indiarubber  may  thus  be  applied 
simultaneously  on  the  two  faces  of  the  same  canvas,  or  it  may  be  uaed  to 
impart  friction  on  the  two  faces  of  the  canvas,  or,  finally,  to  line  the  canvas 
with  indiarubber  on  one  side,  whilst  the  other  side  is  simply  submitted  to  the 
action  of  friction.  As  the  speed  i-  abort  80 feet  i*-r  minute,  the  duplex 
of  the  machine  produces  therefore  160  feet,  if  one  or  the  same  work  !*•  .1 
both  sides  of  the  canvas.  If  care  be  taken  to  supply  a  sufficient  quantity  «.f 
raw  material  in  front  of  the  lainiiiator,  of  whatever  kind  it  may  be,  at  the 


158 


INDIARUBBER 


moment  when  the  preceding  lot  begins  to  get  scanty,  a  sheet  of  indefinite  length 
may  be  obtained. 

Gerard's  process. — In  Gerard's  process,  the  rolls,  instead  of  being  heated  to 
80°  C.  (176°  F.),  are  heated  to  115°  C.  (239°  F.),  and  the  speed  is  so  slow  that  in 
passing  through  the  rolls  the  rubber  has  time  to  get  annealed  over  again.  The 
sheets  so  produced  thus  preserve  and  retain  the  desired  thickness  to  a  great  extent. 
The  sheet  is  then  raised  on  to  drums,  on  which  it  is  coiled  mechanically, 
simultaneously  with  a  sheet  of  calico,  so  that  it  cannot  come  into  immediate 
contact  with  any  other  portion,  and  thus  cannot  adhere  to  itself.  In  another 
three-roll  calender,  the  sheet,  after  completion,  is  rolled  on  a  reel,  turning  at  the 
same  speed  as  the  lower  roll,  but  in  a  different  direction. 

Regulating  the  thickness. — The  thickness  of  the  sheet  may  be  regulated  to 
tenths  of  a  millimetre.  To  ensure  uniform  and  regular  working,  samples  are  taken 
from  time  to  time,  and  cut  not  only  from  the  side  of  the  sheet,  but  also  from  the 
centre.  They  are  calibrated  with  the  draw-plate,  and  the  distance  between  the 
rolls  rectified  until  the  requisite  thickness  is  attained. 

Imitation  cut  sheet. — It  has  been'  attempted  to  impart  to  the  laminated  sheet 
the  appearance  of  the  cut  sheet ;  and  this  has  been  done,  says  Chapel,  by  passing 
it  between  bronze  and  steel  rolls,  on  which  fine  grooves  are  engraved,  the  imprint 

of  which  resembles  the  strise  produced  by  the 
saw  on  the  English  sheet.  The  advantages  of 
the  lamination  and  calendering  process  are  that 
it  can  be  used  throughout  the  whole  of  the 
year;  it  does  away  with  costly  methods,  .and 
does  not  entail  that  enforced  locking  up  of 
capital  during  long  months  of  the  raw  material 
necessitated  by  the  freezing  process,  incidental 
to  the  manufacture  of  the  English  cut  rubber 
sheet.  But  consumers  esteem  more  highly 
the  articles  manufactured  from  English  sheet 
rubber. 

Raised  sheets. — The  laminated  sheet  has  only 
lately  been  used  in  the  manufacture  of  thread. 
Formerly,  raised  sheets  were  used  as  an  excellent 
but  costly  method.  As  the  method  of  working 
is  still  often  followed  in  actual  practice,  we 
shall  rapidly  describe  the  method  of  preparing 
the  raised  sheet,  although  mechanical  action 
plays  but  a  subordinate  part,  and  it  is  more  the  action  of  solvents  which 
intervene.  To  the  Para  rubber  used  in  this  class  of  work,  2  to  3  per  cent,  of 
sulphur  is  added  and  then  dissolved  in  a  convenient  solvent.  A  machine  is  used 
to  apply  this  solution,  consisting  of  two  uprights,  fixed  directly  into  the  floor  of  the 
workshop  or  into  a  massive  bed  of  cast-iron  or  of  wood,  united  on  the  top  by  a 
solid  cross-bar.  On  each  side  of  the  uprights  a  wooden  roller  is  fixed  capable  of 
turning  on  spindles  supported  by  bearings  fixed  on  the  uprights.  The  exterior 
roller  is  furnished  with  a  crank,  wrought  by  a  man  or  by  the  factory  engine. 
Just  below  the  inside  roll  is  an  iron  trough,  of  the  same  length  as  the  space 
between  the  uprights,  which  can  slide  up  and  down  on  two  grooves  on  the  uprights. 
The  trough  contains  the  solution,  and  can  be  raised  or  lowered  according  to  the 
greater  or  less  quantity  which  it  is  desired  to  get  out  of  it ;  when  the  proper 
height  is  reached,  it  is  fixed  by  bolts.  A  long  band  is  rolled  on  the  outside 
roller,  which  slowly  unrolls  during  the  operation,  passes  between  the  inside  roll 
and  the  trough,  and  there  becomes  charged  with  a  thin  layer  of  material,  and  is 
finally  caught  by  two  or  more  cords  stretched  horizontally.  The  coat  applied  is 
always  very  thin,  and  its  thickness  is  determined  beforehand  by  the  distance 
between  the  lower  part  of  the  feeding  trough  and  the  regulator  which  accompanies 
it.  When  the  solvent  used  is  carbon  disulphide,  ten  to  fifteen  minutes  suffice  to 


FIG.  66. — Machine  for  making  raised 
sheet-rubber. 


TRANSFORMATION  OF  NORMAL  RUBBER 


159 


evap'>rati-    it  :     wh.-n    liirht     -pi'  •   '•    t\\«»  «»r    thivc    lioiin*    are   retjii: 

'I'l,,.     layers    d.  p-nrd    are    so    thin    that    tin-    <>|>rrati»u    has   to   be    repeated 
several  times,    and    it    i-    <>nl\    l.\    tin-    -ii|.«T|><.sit i"n   ..i   >t-veral  such  coata  th.it 
the   desired   thickness   is   attain. •  I.      Th.-    dwet,    al't.T    tivatin«-nt    \\ith    tul< . 
(U-tachrd    l»v    iiinistening    it    undi-nu-ath    l»y   a   little    -..K.-nt,    and    il    th-  i.    BOf60ed 
on    tin-    \\indci-.       It     i-    i\<>\\     pivtrral.! v    n-<-d     I'm-    tin-    saiiu-  nl.jt-ct    in    tin?    w.i 

ai.id,    uum-    i..    tip-   steam   table** 


proofing 


with  which  the  ;ii»}>liaii(vs  aiv  always  pm\  i.U-d.  Tlu-  slieets  thus 
have  only  one  uniform  surfacej  tin-  l..\vrr  preserrea  thy  -rain  of  the  cloth  on 
which  it  has  been  laid.  >v»///»  r'*  /<r<><'(.^  rcnu-dies  this  dnvwback.  A  coating 
is  first  laid  on  the  cloth,  \\ith  tin-  sum.-  apparatus  jw  that  described  above, 
consisting  of  paste  glue  and  skin  ^lur.  t"  which  a  little  cane-sugar  molasses  has 
been  added  to  pivsi-nv  its  suppleness,  and  the  pn><-esa  conducted  ^as  before. 
The  solvent,  having  no  action  on  the  coating,  simply  spreads  over  it,  without 


160 


INDIARUBBER 


adhering  to  it,-and_it  thus  becomes  rpossible  to"  produce  sheets  with    a    smooth 
surface  on  both  sides. 

Casting  sheets  on  glass. — In  the  vulcanisation  of  moulded  objects,  it  is  possible, 
by  the  use  of  glass  moulds,  to  obtain  straight-away,  and  without  retouching, 
perfectly  polished  objects.  It  is  the  same  with  raised  sheets,  which  are  obtained 
as  thin  as  possible  and  of  great  transparency  by  preparing  a  very  dilute  solution 


FIG.  68.— Vertical  spreader. 

of  indiarubber  (1  of  rubber  to  15  of  carbon  disulphide),  and  spreading  this 
solution  on  smooth  glass.  Evaporation,  however,  must  not  be  too  much  accelerated, 
otherwise  considerable  cold  would  be  produced,  with  condensation  and  deposition 
of  the  superincumbent  moisture,  and  the  drops  of  water  thus  produced  would  spot 
the  facets  of  the  sheets. 

Vertical  spreader. — The  necessity  of  having  to  repass  the  fabric  to  be  water- 
proofed several   times   over   a  hot  table   is  a  drawback  to  the  working   of   the 


TRANSFORMATION   OF   NORMAL   RUBH1  K  161 


hori/.ontul    spreader,       \\itli    tin-    M-rtir.il    -piviioVr  tin-   '.p,-rati.,n   only  rri|iiiri!«  one 

-•  thr»n-li  tin-  m.fliiiM-.     Thi>  niarhim-  .-..n-i-i  -  of  t  \\  •  •  raat-ftteel  fraiut'8  with 

stout  <T»sspi<  •!•(•-<.     Tln-M-   hainr-  .sii|»|inrt   two  hull.iw  t-.iNt  in,  u  plates  heated  by 

strain,  wlii'-li  may  !«•  «lra\\  n    apart    or  Im.ii^lit    n.  ai    I  \   a  m.-rlianu-jil  amngiMiii-nt. 

'I'ln-    tal.rifN,  at'trr  l«-in^   ini|iri^ii;itt'il  \\itli    riil.l.»-r   in  tin-  tank  In-low  tin-  iiiurhinc, 

!.-luliTi-il    l.\    pa  —  iiiur    |irt\\.-.-n   t\\o    rolls.        r,y   IIHMII-    of    klii\fs,   \\iiiflicaii    I  «• 

rc^iilalnl  as  olcsiml,  tlit-  rulilu-r  on  tin-  tuo  fact's  of  tin-  fal«ric  is  •••jualisnl,  ami  thr 

lattrr    is    lf«l    l.rturri)    tin-    hot    platr>.    \\llirll    «'\  a|  H  .ratr   tip-    IM-II/.  nr.        Tin-     i   i\,intagC 

of  this  inarhinr  is  that   it   tivats  l.oth  >i.|rs  of  tin-  lal.ri.-  >iniiilt;iin-..u-l\. 


I  r 


CHAPTER    VIII 
VULCANISATION  OF  NORMAL  RUBBER 

Preliminary  considerations. — Defects  of  natural  rubber. — To  render  the  sequel 
more  intelligible,  we  must  recall  some  defects  of  natural  rubber.  (1)  Defects  visible 
on  heating. — All  natural  rubbers  soften  rapidly,  as  soon  as  their  temperature 
exceeds  30°  C.  (86°  F.)  and  gets  near  to  50°  C.  (122°  F.).  Their  adhesiveness 
increases  in  direct  ratio  with  the  softening,  so  much  so  that  at  50°  C.  (122°  F.)  the 
rubber  is  so  sticky  and  tacky  that  it  is  unfit  for  all  the  industrial  uses  for  which  it 
is  naturally  destined. 

(2)  Defects  on  cooling. — But  when  the  temperature  falls  to  10°  C.  (50°  F.),  rubber 
gradually  and  insensibly  loses  its  elasticity,  hardens,  and  at  0°  C.  (32°  F.)  becomes 
so  rigid  that  it  is  believed  to  be  frozen.  Such  rapid  modifications,  within  compara- 
tively narrow  limits  of  temperature,  constitute  great  drawbacks  to  the  use  of  natural 
rubber.  The  mere  transport  of  an  article  made  from  natural  rubber  to  a  hot 
country  or  to  a  cold  country  suffices  to  render  it  almost  useless  in  both  cases  ;  in 
the  latter  because  of  its  rigidity,  in  the  former  on  account  of  its  being  too  sticky 
and  tacky.  The  same  phenomena  occur  in  one  and  the  same  locality  in  consequence 
of  the  simple  variation  of  the  weather,  due  to  the  seasons.  Air  and  light,  especially 
in  presence  of  heat  and  moisture,  deteriorate  natural  rubber  very  readily,  converting 
it  into  a  viscous  substance,  without  any  of  the  properties  of  good  marketable  rubber  : 
the  rubber  has  perished  by  oxidation.  These  original  defective  qualities  would 
certainly  have  constituted  an  obstacle  to  the  use  of  rubber  ever  becoming  general, 
and  the  new  industry,  now  so  prosperous,  would  very  soon  have  been  in  danger,  had 
it  not  been  for  one  of  those  lucky  inventions  of  which  the  nineteenth  century 
furnished  so  many  examples  :  namely,  the  vulcanisation  <>f  i  n<Ii<t  rubber. 

Action  of  sulphur  and  halogens — Sulphur  passive  to  indiarubber  in  the  cold. — 
Sulphur  in  no  way  modifies  the  properties  of  indiarubber  so  long  as  there  is  no  rise 
in  temperature.  But  as  soon  as  heat  intervenes  this  passive  state  gradually  gives 
way,  and  disappears  altogether  as  the  temperature  rises. 

Payerfs  researches — Effect  of  heat  on  rubber  immersed  in  sulphur.  —  Payen  made 
the  most  interesting  investigation  of  this  subject.  A  sheet  of  rubber,  2  millimetres 
(52T  of  an  inch)  thick,  immersed  in  a  bath  of  molten  sulphur,  at  120°  C.  (248°  F.), 
swells  slightly,  its  pores  distend.  The  rubber  absorbs  sulphur  by  capillarity.  It 
behaves  as  if  it  had  been  plunged  into  water,  but  the  operation  is  more  rapid,  owing 
to  the  affinity  of  sulphur  for  rubber.  After  a  quarter  of  an  hour  no  appreciable 
change  has  taken  place  in  the  properties  of  the  rubber,  the  surfaces  of  which  may 
yet  be  amalgamated  by  contact.  The  porosity  only  is  lessened.  But  if  the 
temperature  be  raised  to  130°  to  140°  C.  (266°  to  284°  F.),  and  if  that  heat  be  con- 
tinued for  thirty  to  forty  minutes,  the  rubber  alters  both  in  appearance  and 
properties,  assumes  a  yellowish  tint,  and  does  not  amalgamate  with  itself.  Its 
elasticity  is  considerably  increased  and  become  permanent.  Cold  does  not  now 
cause  it  to  disappear.  The  same  results  ensue  if  rubber,  previously  mixed  with 
sulphur  reduced  to  an  impalpable  powder,  be  exposed  to  a  temperature  of  130°  to 
140°  C.  (266°  to  284°  F.).  There  are  still  other  cases  in  which  the  same  results 
are  produced.  Variable  temperatures  between  the  melting-point  of  sulphur  and 
160°  C.  (320°  F.)  may  be  used.  The  reaction  is  more  rapid  at  a  higher  tempera- 

162 


VULCANISATION   OF   NORMAL   RUBBER  163 

tun-,  I. nt  experience  provel  that  the  best  results  are  ol.t a in.,1  by  operating  at  PJO 
C.(L' is    F.),  and  proloiiging  the  operation*     Ebonite,     If  the  quantit\  •  .,i  Milplmi 
l»e  sufficient,  and  if  tin-  operation  be  conducted  between   1~><>   and    !•'•' 
and  .">•_'()    F. ),  there  is  obtained  after  u  few  hours  a  substance  which  is  n«» 
vulcanised   rubber.  Imt    a  new  product,  having   neither  extensibility  nor  ela»ticit\  : 
even   its  aspect    i<  modified — the  mixture  ha-  assumed  a  very  deep  brown  colour, 
and  becomes  as  hard  as  horn.       It  is  J,<,nite. 

Sulphur  not  the  <>nli/  vulcanising  agtnt,     Elemetitarj  salphnx  U  not  tin-  only 

body  which  induces  vulcanisation  of  rubber;  alkaline  sulphides,  sulphides  of  the 
alkaline  earths,  several  metallic  sulphides  sulphur  chloride,  induce  the  same 
modifications  in  rubber. 

Too    in<r<i>ti<-    tiff  inn    of   chlorine,  jl HO,  ,,«.  Chlorine. 

fluorine,  iodine,  and  bromine  act  similarly  to  sulphur,  Hut  these  bodies  are  much 
more  volatile  than  sulphur  at  the  ordinary  tenqierature  ;  their  action  i<  more 
fiHM-m-tic,  ofti-n  too  energetic  to  attain  in  a  uniform  manner  thr  dr.-iivd  object. 
Sometimes  this  object  is  overdone,  soniftinu-s  vulcanisation  is  insufficiently  rr 
-onu-times,  again,  the  reaction  is  rapidly  destroyed  by  the  volatilisation  of  the 
vulcanising  agent. 

Siilj>l,tr,-  ,•//«!/,  <n»l  «t*ih/ handled. — These  processes  cannot  be  easily  adopted 
in  practice.  Sulphur  gives  satisfactory  enough  practical  results;  it  is  cheap  and 
easily  handled.  It  would  be  idle  to  resort  to  other  processes,  the  application  of 
which  is  difficult  without  yielding  better  results.  The  examination  of  vulcanisation 
by  those  secondary  bodies  will  therefore  be  deferred,  retaining  only  sulphur  or  its 
derivatives,  which,  moreover,  present  a  sufficiently  extensive  field  for  inve>tigation. 
Of  the  innumerable  methods  of  vulcanisation  by  sulphur  and  its  derivatives 
proposed  and  attempted,  whether  in  Great  Britain,  France,  America,  Germany,  or 
other  countries,  we  shall  only  examine  and  describe  those  which  deserve  more 
especially  to  fix  the  attention  of  manufacturers,  with  a  brief  criticism  of  these 
different  methods,  showing  the  advantages  and  disadvantages  of  each  ;  the  machinery 
and  plant  most  generally  used  in  the  vulcanising  industry  will  also  be  described, 
terminating  this  chapter  with  a  discussion  of  the  theory  of  vulcanisation. 

The  hot  and  cold  processes  of  inc<>i-]><>r<itiini  tin  mi/jJun:—  The  most  imjM.rtant 
method  hitherto  considered  is  that  based  on  the  use  of  natural  sulphur.  It  i- 
divided  into  two  different  processes,  according  as  the  sulphur  is  incorporated  ( 1 )  in 
the  hot  (Goodyear's  process)  or  (2)  in  the  cold  state  (Hancock's  pro- 

1.  Goodyear's  jyrocess — Vulcanisation  of  rubier  /•;/  nut  ami  *nl]>hnr. — This, 
the  most  generally  adopted  process,  is  based  on  cold  mixing  of  a  predetermined 
quantity  of  sulphur  with  rubber,  and  on  W,-/////  or  curing,  i.e.  the  tran>formation 
of  this  mixture  into  vulcanised  rubber  by  a  predetermined  quantity  of  heat.  Thi> 
process  is  certainly  the  most  rational,  because  known  proportions  of  sulphur  can 
be  incorporated  with  the  rubber,  and  nothing  is  left  to  chance.  Moreover,  it  almost 
always  yields  results  which  cannot  be  attained  by  other  processes.  The  rubber, 
masticated  and  dried,  as  already  indicated,  is  put  through  the  mixer  with  7  to  |u 
per  cent,  of  sublimed  sulphur  (flowers  of  sulphur).  Hubber-  are  even  met  \\ith  in 
commerce,  vulcanised  with  only  2J  to  3  per  cent,  of  sulphur.  Hut  the  quantity  of 
sulphur  v;irie-  within  the  wider  limits,  and  certain  manufacturer-  have  been  kin»\\n 
to  use  as  much  as  25  per  cent.  The  first  proportion  is  amply  sufficient,  and  even 
6  i»er  cent,  of  sulphur  has  j:iven  excellent  results.  The  excess,  when  not  prejudicial, 
can  only  be  regarded  as  an  inert  makeweight,  ffomooeneout  ,<•>/ essential.— 
The  mixing  must  be  perfect  to  ensure  success,  and  the  mass  must  form  one 
homogeneous  whole.  Too  much  care  cannot  be  bestowed  on  mixing  so  as  to 
obtain  a  homogeneous  mass.  Four  or  five  kilogrammes  (say  9  to  11  lb.)of  wasted 
rubber  are  passed  related ly  through  the  hot  rolls,  diminishing  the  space  between 
them  as  the  operation  proceeds.  As  it  LS8U68  from  the  roll,  the  sheet  is  dusted  for 
the  first  time  with  sublimed  sulphur,  rolled  upon  itself,  and  again  passed  through 
the  mixer.  This  operation  is  repeated  as  often  as  necessary  to  exhaust  completely 
the  amount  of  sulphur  to  be  incorporated  and  obtain  a  really  homogeneous  mass. 


164  INDIARUBBER 

This  mass,  still  a  mere  mixture,  is  wrought  in  the  ordinary  way  for  conversion  into 
threads,  sheets,  tubes,  shoes,  or  any  other  object  of  definite  shape.  It  is  only  under 
this  final  shape  that  the  objects  are  transformed  by  heat.  They  are  introduced  into  a 
hermetically  sealed  boiler,  where  steam  is  injected  at  a  suitable  pressure,  generally 
3J  to  4  atmospheres.  A  sojourn  of  three  to  four  hours  in  the  boiler  is  sufficient  to 
produce  vulcanisation.  In  certain  cases,  the  boilers  are  replaced  by  a  hot  stove 
heated  from  130°  to  150°  C.  (266°  to  302°  F.).  Varnished  indiarubber  boots  are 
vulcanised  in  this  way  (as  steam  would  destroy  the  brilliancy  of  the  varnish) ;  so 
also  are  certain  waterproof  garments.  But  whether  boilers  or  stoves  be  used,  the 
same  result  is  attained  :  the  indiarubber  is  acted  on  by  the  sulphur  in  the  desired 
dose,  and  the  latter  is  distributed  throughout  the  mass  with  almost  mathematical 
uniformity. 

Goody  ear's  process  costly. — The  most  serious  objection  to  Goodyear's  process  is 
that  it  involves  great  initial  outlay,  and  a  large  amount  of  labour  for  its  perfect 
execution.  It  is  therefore  costly,  and  is  not  readily  available  by  the  small 
capitalist ;  but  that  defect,  not  easily  remedied,  need  not  be  dwelt  upon  further. 

The  excess  of  sulphur  effloresces  on  the  surface  of  the  object — Injurious  effect — 
Remedy. — A  more  serious  criticism  against  Goodyear's  and  also  the  bath  process, 
is  that  rubber  articles  vulcanised  directly  by  sulphur  always  contain  an  excess 
thereof,  which,  when  the  operation  is  finished,  has  a  tendency  to  separate  out,  and 
cover  the  surface  of  the  object  with  a  greyish  white  efflorescence,  disagreeable  to 
the  eye,  touch,  and  smell.  This  substance  (simply  sulphur  in  extremely  small 
crystals)  may  hasten  the  rapid  decay  of  the  manufactured  article.  In  contact  with 
the  moisture  of  the  warehouses,  the  sulphur  oxidises  to  sulphuric  acid,  always 
injurious  to  rubber.  Washing  with  alkaline  lye  is  the  usual  remedy  ;  but  if  con- 
tact be  prolonged,  which  is  nearly  always  necessary,  washing  gives  rise  to  another 
defect,  the  surface  of  the  article  is  exposed  too  much,  and  is  partially  devulcanised, 
so  to  speak,  and  some  of  the  defects,  inherent  in  normal  rubber,  are  restored  to  it. 

2.  Hancock's  process1  (the  hath  process) — Differentiation  from  Goodyear's  dry 
mixing  process. — Instead  of  mixing  sulphur  with  rubber  at  a  comparatively  low 
temperature,  and  then  submitting  this  mixture  to  the  heat  of  the  steam  from  a 
boiler  or  to  the  hot  air  of  a  stove,  the  heat  of  melted  sulphur  is  utilised  to  ensure 
vulcanisation,  i.e.  instead  of  baking  or  curing  with  steam  or  superheated  air,  the 
manufactured  objects  are  steeped  in  a  bath  of  molten  sulphur.  Mixing  and  curing 
proceed  simultaneously. 

(1)  Preliminary  drying. — But  prior  thereto  the  articles  must  sojourn  from  twenty- 
four  to  thirty-six  hours  in  a  hot  stove,  so  as  to  consolidate  the  joints  and  evaporate 
traces  of  the  solvent  used  in  the  manufacture  of  the  article,  otherwise  vulcanisation 
by  Hancock's  process  would  yield  blowholes,  which  would  deteriorate  the  goods. 

(2)  Immersion  in  bath. — When  perfectly  dry  the  articles  are  immersed  in  molten 
sulphur  at  130°  to  135°  C.  (266°  to  275°  F.).     But  as  they  are  much  too  light  to 
remain  immersed  by  their  own  weight,  they  are  loaded  by  small  weights  called 
reglettes.     Small  pieces   of   indiarubber    are   immersed   at  the  same  time  as  the 
articles,  and  so  arranged  that  they  can  be  withdrawn  at  will.     These  fragments,  or 
samples,  enable  the  progress  of  vulcanisation  to  be  watched.     They  ought,  as  far  as 
possible,  to  have  the  same  thickness  as  the  articles  to  be  vulcanised ;  the  indications 
which  they  furnish  have  thus  a  real  value  for  the  operator,  who  requires  to  have 
had  great  experience,  so  that  by  simply  inspecting  the  samples  he  can  judge  how  far 
vulcanisation  has  advanced.     When  the  articles  have  been  immersed  in  the  bath, 
vulcanisation  is  not  long  in  starting.     The  rubber  first  absorbs  the  sulphur  by 
capillarity,  and  so  increases  in  weight  by  one  half.     Its  colour  then  begins   to 
change  :  from  brown  it  changes  to  orange.     Taken  out  of  the  bath  in  this  state 
after  twenty  minutes'  immersion,  the  rubber  is  still  too  soft,  and  still  possesses  the 
property    of   uniting    with    itself;   the    normal    rubber    has    not    been    chemically 
modified.     But,    in    a  few  moments,   after  the  saturation  of  the  pores,  the  real 
reaction  starts ;  it  is  complete  in  two  or  three  hours ;  the  phenomena  is  accompanied 

1  British  Patent,  9952  ;  1843.— TR. 


VULCANISATION   OF   NORMAL   RUBBER  165 


l>y   tile   dUeng.iL'elnent    'it     sulphuretted     ||\dr«gr|l     from    the    lIUvx   "I    the    ll.jUl.l 

do.-s  imt  occur  in  tin-  beginning.      <  'hemical  n-act  i«.n  t.ik.  •-  pliire,  for  if  tin*  ij|**ratioii 

be  prolon^'-d  tin-  -ub-tance  becomee  .1-   ii.n-.i  u   u  .....  I.  .m.i   i    ti.ui>f«.rmed  int«« 

ebonite.       When     tin-     \\oikman     think>    the    substance     -ullicinitly     \iiliMnJM-il.     h.- 

imniei-M'N   it    as  qiiickh  '.|e    ill    cold    \\.iter.        II.-  .-\hailM-   It    .in.  I   tli 

from    Hi.-  excess    "I  -ul|>lmr   tli.tt    CO\  »r,  \\liich  -plit>  up  l.y  tin-  -ndd«-ii 

cooling,  so  th;it  it  niily    ;i»lli<-iv-   slightly   to   tin-   ruliln-r.      A  i.ipmg  uith  .1 

lilt-till    Made    NUllice-   to  free    tll«'   article    from    it. 

r///ivf///.xv,/  ,/,,.,./.<  H,tl»l<-  to  tiilfiluir  »///"/•<.«••  /><•>  /,'•  n»>ly.  —  But,  nevertheleiS, 
rubber  so  treated  always  retains  as  in  (i  .....  heap's  process,  a  certain  excess  of 
sulphur  over  and  above  that  re.|iiired  tor  \  idealisation,  \\hirh  form-  an 
substance,  more  injurious  than  useful.  Thi>  e\«vsH  IH  gnulnally  exuded  from  tin- 
interior  of  the  mass  as  a  \vliiie  powder,  forming  a  coating  "ii  the  surface  of  tin- 
ol.je.'t  \nleaiiised.  It  is  e.isy  to  free  it  from  a  certain  portion  of  thiscxccflHof 
sulphur  if,  a.s  soon  as  vulcanised,  it  In-  passed  through  a  boiling  solution  of 
can-tie  alkali.  The  excess  of  sulphur  is  rapidly  converted  into  alkaline  sulphide, 
and  simple  washing  afterwards  suffices  to  eliminate  the  resultant  sulphides. 

3.  Sublimation  jwocesx,  /M  ///>///,  riilcauixntion  l>tj  mbfotnotion.  Hancock  pro- 
posed another  modification,  baaed  on  the  simultaneous  action  of  steam  and  sulphur 
vapour,  \\hich  effects  vulcanisation  in  an  hour  and  a  half,  according  to  thickness 
of  pieces.  The  sulphur  bath  is  still  used,  but  no  longer  as  a  vulcaniner,  but  in 
place  of  steam  or  of  the  air-oven  for  vulcanisation  of  certain  moulds.  Alongside 
these  two  processes,  based  on  the  use  of  sulphur  acting  directly  on  the  rubber,  it  i« 
convenient  to  quote  — 

(1)  Parkes'  process,  or  the  steeping  process  —  Cold  process.  —  It  consists  in 
treating  rubber  with  sulphur  protochloride.  Discovered  by  Parkes  (British  Patent, 
11,147  ;  1846),  it  is  now  frequently  used,  especially  to  vulcanise  small  thin  objects. 
The  pro.  .---  works  in  the  cold  and  very  rapidly.  '2'~>  11>.  of  sulphur  chloride  are 
dissolved  in  100  Ib.  of  pure,  perfectly  anhydrous  carbon  disulphide.  The 
articles  to  be  vulcanised  are  immersed  in  this  liquid  from  a  half  to  three  minutes, 
according  to  their  thickness.  When  taken  from  the  vulcanising  bath,  the  article 
is  dried  at  a  temperature  of  about  25°  C.  (77°  F.),  again  steej)ed  in  the  bath  from 
a  half  to  one  minute,  then  washed,  first  with  a  very  dilute  solution  of  sodium 
carbonate,  then  in  pure  water,  and  finally  dried.  This  process  is  only  applicable  to 
small  thin  objects.  Thicker  articles  must  be  steeped  longer,  to-  let  the  liquid 
penetrate,  but  then  there  is  risk  of  overdoing  it;  the  rubber  may  be  burnt. 

(la)  T/ie  inventor's  and  Gerard's  -»kx////V/f//o//x.  —  Parkes  therefore  proposed  only 
to  use  i  part  of  sulphur  chloride  for  100  parts  of  carbon  disulphide,  and  to  prolong 
or  repeat  the  process.  G.  Gerard  recommends  to  u^e  only  the  tirst  proportiona, 
'.-.  '2\  per  cent,  of  chloride,  but  to  steep  the  articles  immediately  they  come  out  of 
the  bath  in  cold  water,  and  to  let  them  lie  there  for  some  time.  The  chloride 
thus  lias  time  to  penetrate  the  rubber,  whilst  tin-  sujK-rticial  part  already  vulcanised 
is  no  longer  liable  to  become  brittle,  the  excess  of  sulphur  chloride  on  the  surface 
is  transformed,  in  contact  with  water,  into  hydrochloric  acid,  sulphurous  acid,  and 
free  sulphur.  The  steeping  process  is  distinguished  by  great  simplicity  and 
extreme  rapidity.  It  requires  no  complicated  plant  nor  costly  raw  material.  I' 
Specially  adapted,  moreover,  for  surface-curing  in  the  manufacture  of  small  objects 
of  cut  rubber,  tobacco  pouches,  injectors,  syringes,  tubing,  rings,  etc.  But  it  cannot 
be  used  for  articles  exceeding  4  millimetres  (>a\  \  of  an  inch)  in  thickness,  other- 
wise vulcanisation  will  only  deteriorate  the  goods  profoundly,  cause  them  to 
become  fragile,  and  break  with  the  slightest  effort. 

Dittmar  points  out  that  the  method  of  working  -ince  Parkes'  time  has  been 
changed.  According  to  Mar/aim,  the  articles  are  dipped  one  to  three  minutes  in 
a  solution  of  sulphur  chloride  in  40  to  "><>  part-  "f  carbon  disulphide,  then  dried. 
If  necessary  the  Gyration  may  be  related.  Hoffer  recommends  the  following 
mixture  for  thin  objects  :  —  Sulphur  chloride.  1  part  :  <  -arboii  disulphide,  30  to  40parts; 
time  of  dipping,  sixty  to  eighty  seconds.  For  thicker  articles,  sulphur  chloride, 


166 


INDIARUBBER 


1  part ;  carbon  disulphide,  30  to  40  parts ;  time  of  dipping,  three  to  five  minutes.  For 
still  thicker  articles,  the  dipping  must  be  repeated  as  often  as  necessary  t<>  r<unpl«-tr 
the  vulcanisation.  Too  long  steeping  induces  hard  brittle  surfaces.  Washing 
after  steeping  prevents  the  sulphur  chloride  in  excess  from  continuing  its  action. 
Water  decomposes  sulphide  chloride ;  the  sulphur  separates  partly  as  such,  partly  as 
sulphurous  and  hyposulphurous  acids,  the  ratio  of  the  two  latter  depends  on  the 
amount  of  water.  The  chief  drawback  of  the  cold  process  of  vulcanisation  is  due 
to  the  injurious  effect  of  the  vapours  of  sulphur  chloride  and  carbon  disulphide  on 
the  workmen.  Attempts  have  been  made  to  substitute  petroleum  spirit,  which 
should  be  anhydrous,  for  carbon  disulphide.  Dittmar  tried  to  determine  the 
influence  of  the  time  of  steeping  on  the  tensile  strength  and  elasticity  of  Para 
rubber.  He  cut  small  samples  5  centimetres  long  from  a  large  band  2  metres  long 
by  3  centimetres  wide  and  7  millimetres  thick.  These  samples  were  dipped  into  the 
vulcanising  liquid,  consisting  of  sulphur  chloride,  1  part ;  carbon  disulphide,  80  parts. 
The  samples  were  stretched  by  Delaloe's  dynamometer.  After  drying,  the  measure- 
ment of  the  elongation  was  made  on  1  centimetre. 

TABLE  XXXIII. — VARIATIONS  IN  TENSILE  STRENGTH  OF  INDIARUBBER  CURED 
BY  PARKES'  PROCESS  ACCORDING  TO  DURATION  OF  STEEP. 


Duration  of 
Dipping 
in  minutes. 

Breaking  Load 
in 
kilogrammes. 

Elongation 
at  the  point  of  Rupture 
in  centimetres. 

1 

14 

3-6 

2 

15 

3-9 

3 

15-2 

8 

4 

15-62 

6-2 

5 

16-25 

5 

6 

12 

3-8 

7 

15 

37 

8 

15-25 

3-8 

9 

16-5 

7-4 

10 

18-5 

6-2 

The  pure  para  gave  7  kilogrammes  and  2 -2  centimetres.  The  tensile  strength 
therefore  increases  up  to  five  minutes,  then  diminishes,  then  increases  after  five  minutes. 
The  elongation  increases  up  to  four,  then  lowers  ;  after  eight  minutes  it  again  increases. 

Recommended  by  Fawsitt. — In  a  research  which  merits  attention,  Fawsitt 
in  1889  specially  examined  Parkes'  process  and  became  an  ardent  apostle  of  it. 
This  chemist  attributes  the  complaints  as  to  the  durability  of  the  rubber  to 
defective  manufacture,  and  he  quotes  samples  of  rubber  vulcanised  by  this  process 
having  preserved  all  their  elasticity  and  other  properties  after  twenty  years  from 
their  despatch  from  the  factory.  Vulcanisation  by  sulphur  chloride  dissolved 
in  carbon  disulphide  presents  numerous  difficulties,  only  surmountable  by  observing 
numerous  precautions.  The  first  of  these  is  to  use  only  sulphur  protochloride 
S2Cl2,  and  never  the  perchloride  SC12,  the  action  of  which  is  too  energetic.  One 
can  thus  use  more  concentrated  solutions,  the  better  to  attain  the  end  in  view. 
But  even  if  protochloride  be  used,  it  is  extremely  unstable,  especially  in  the  light, 
so  it  is  necessary  always  to  have  a  standard  solution  ready  to  make  certain  that 
the  protochloride  does  not  vary  from  one  operation  to  another.  Fawsitt  was 
perfectly  able  to  obtain  vulcanised  articles  of  excellent  quality,  but  the  dislike  of 
the  generality  of  manufacturers  for  this  process  is  none  the  less  justified.  A 
certain  solution  of  sulphur  chloride  which  succeeds  very  well  in  the  first  instance 
may  be  altered  by  the  use  of  imperfectly  dehydrated  carbon  disulphide,  or 
imperfect  storing  in  a  spot  badly  protected  from  light  and  moisture.  Vulcanisation 
with  such  a  solution  will  not  produce  the  original  effect,  and  the  negligent  or 
clumsy  worker  will  simply  have  employed  a  decomposed  liquid,  containing  only 


VULCANISATION    OF    NORMAL    RUBBER  167 


hsdiorhlorie   :t<  i<l    an.  I    .1    little    sulphur    d<  p"-it.-d    ..n    th.-    l,,,n.,u,    .,f   the 

Vulcanisation    \\ill    tllereloiv   either    IP.  I     I,,-   •  •thvtrd    ;tt    all    or   «,|||\     llll  |  •  •(  |,-,  \  \  \  . 

'/'//•  f  carbon  «//.«*///////•/'.     Again,  tin-  n|»  ,|  |,\ 

l'arke>,  i  .  dangerous  to  tin-  health  of  tin-  workman.  mul  .til  tin-  |*.—  iblt-  \«  ntil.itioiiH 
proposed  b\  Faw-itt  as  pre\entati\es  .-an  mily  iinTe.i>e  tin-  I-M!  :n-t..id  of 
remedying  it.1  Tin-  carb  m  disulphide  which  •  a  \ehiclr  does  nut  art  tr-.m 

it-    toxic    effect,     but     by    tin-    intense    mid    \\hi<-li    it    gnu-rales    during    its    rapid 
evaporation.       llapid    r\a|.«,  ration    being    increased  l,\   0neigetlO  \i-ntilation,  eeiebml 
!  ions  arc  frequent  and  fatal. 

]'•  t  i-o1'  inn  *j>irit  tin'/  l><H.t>!  f/\   nliirl  irl.nii  ilisii/jt/t  iil>-.        Petroleum 

s|iirit    slmuld    thus    In-   siil.st  it  ntcd,   as    |trn|Misrd    l»\    llun;ti«  \.   t-.r   the    v«-liirl«-    Q 
liy    rarkt-*.    m-,    i»,-tt"r   -till,    ln-n/'il,    \\liii-li    uri\''-    i-xci-lldit    result-.    |.|-M\id<-.|    r 

|.;Tlr.'tl\    drll\d|-atfd. 

I'li/i'int/*  :t'/<i/i  /it/  tin  t'.-ij.uiii-  tit'  I'/i/firt'/i  <>''  tulphur  ii/om.  Uut  tlirrr  artuallv 
a  iiiiifh  inun-  iii<>H'cn>i\  .•  prMi-r--  «\  \  uh-anisit  ion  liy  sul|iliiir  rhloridr. 
in  doth  l>lcacliin^,  a  kind  of  siilplmriitor  is  made,  lined  \\ith  lead,  and  ji-if,-.-t|y 
the  olijci-ts  to  !«•  vulcanised  are  sti>|  ended  therein.  The  sulphur  chloride 
is  placed  in  a  K>NV|,  standing  over  a  chaiin^  dish,  \\ith  a  tire  in  it,  and  the 
snlplmiMtor  is  dosed.  The  operation  goes  on  \\itliont  any  further  interventi  ..... 
and  the  simple  \\ashinur  of  the  objects  in  \sater,  to  which  a  little  annn<  niuin 
hydrate  has  l.een  added,  after  they  come  out  of  the  leaden  chainl  er,  rein. 
useless  and  injnrioii:;  sul.Mumvs  which  have  t'«  rnied  on  the  indiaruM  i-r  during  the 
reaction.  1'urke-'  prOC88B,  «»r  vulcanisation  in  the  cold  l,y  sulphur  chloride  dissolved 
in  carhon  disulphide,  petroleum  spirit,  or  lu-n/ol,  as  well  as  the  i>roce»  l.y  the 
vapour  of  sulphur  chloride  alone,  were,  until  recently,  used  to  the  exclusion  of  all 
others  for  the  vulcanisation  of  cloth  for  waterproof  gannuits,  or,  to  speak  n. 
correctly,  for  the  vulcanisation  of  the  thin  layer  of  rubber  which  renders  the  stutf 
impermeable. 

\'n/i'nnifi'ifiini  l>u  '//•//  steam,.  —  Since  then  it  has  l.een  thought  right  to  abandon 
the  cold  process,  as  well  as  the  process  of  vulcanisation  by  the  vapour  of  sulphur 
chloride  alone,  in  favour  of  vulcanisation  by  dry  steam.  Three  houses  only  in 
France  employ  this  new  process;  Britain  (more  esj>ecially  Scotland)  OOnntfl  a  rather 
greater  number  of  factories  which  have  adopted  the  vulcanisation  of  fabrics  l.y  dry 

in  ;  but  it  is  particularly  in  America,  where  the  process  was  invented,  that  the 
method  is  most  employed. 

Litharg*  a  neceuary  mljtmct.  —  This  vulcanisation,  in  a  special  oven,  does  not 
yield  good  results  unless  litharge  intervenes  with  the  sulphur,  the  litharge  acting. 
so  to  Bpeak,  as  a  drier.  Without  litharge  the  vulcanised  piece  \\oiild  remain 
greasy  and  tacky  to  the  touch.  Until  quite  recently  only  black  coloured  rubbers, 
or  rather  fabrics,  could  be  obtained  in  this  way. 

It  is  only  lately  that  a  French  house  has  produced  by  the  dry  steam  process 
vulcanised  cloth  of  all  shades,  \\ith  the  exception  of  a  perfect  white.  [JnfortanateJj 
the  process  i-  kept  secret,  and  it  is  impossible  to  yive  any  particulars  regarding 
it.- 

/•'</  //•>•/'//'.<  /  ,•/„  rinit'tits  arid  researc/ies  <>n  vulconiiation  by  dry  &CUR  in  ]m  fence 
<>/  iodides.-  Mr.  Charles  A.  Fawsitt,  the  numerous  iv<earche>  of  \\hom  on  the 
vulcanisation  of  indiarubb.T  by  sulphur  chloride  we-  have  already  had  ocra-i.  n  t<» 
mention.  ga\e  in  the  Jon  rmil  <>/  tl,<  .S-"/-///  qf  ('It,  ////»•///  Industry  for  l^'.M  the 
results  of  a  remarkable  iv>eaivh  on  the  new  process  of  \ulcaiii-atioii  by  dry  >t«am 
in  the  presence  of  iodide-. 

Whilst  reservingour  ojiininn  on  the  method^  adupted  and  more  particularly  extolled 
by  the  author,  experience  has  not  everywhere  gi\  en  equally  satisfactory  results,  and 
the  subject  is  yet  too  new  to  be  completely  eiucidatt  d.  Fawsitt  thinks  that  the  best 
way  of  enumerating  the  reasons  which  have  induced  llritish,  American,  ami  French 

lSee  also   the    /,'/N/.-.<  ami   Danger*  "/  1'arious   Occupations  (Scott,   Greenwood  &  Co.), 

pp.  168-172,  for  further  details  of  th«  i  mi  list  rial  liygii-iu-  «.f  rul.her  manufacture. 
•  The  litharge  is  possilily  replaced  liy  a  nuni^aiieM-  drier.      Ti:. 


168  INDIARUBBER 

manufacturers  to  adopt  this  new  vulcanisation  process,  is,  first  of  all,  to  explain 
the  advantages  and  disadvantages  of  both  processes.  The  advantages  of  t/ie  cold 
process  are: — 1.  The  production  of  what  is  called  the  transpaivnt  layer,  still  so 
much  appreciated,  although  a  •  little  less  so  for  simple  woven  goods.  *2.  The 
rapidity  and  the  cheapness  of  this  process  compared  with  the  dry  heat  process. 
What  is  here  meant  by  cheapness  does  not  apply  to  the  composition  itself,  but 
simply  to  the  cost  of  manipulation.  3.  The  non-efflorescence  of  good*  treated  in 
the  cold,  a  very  important  point,  which  has  not  been  satisfactorily  explained.  As 
bearing  upon  this,  a  short  digression  may  be  made  and  one  or  two  points  connected 
with  efflorescence  which  may  be  of  interest  mentioned. 

Points  connected  with  efflorescence. — How  is  it  that  with  rubber  treated  in  the 
cold  we  can  use  9  to  10  percent,  of  sulphur  without  fearing  efflorescence,  whilst  in 
the  dry  heat  process  3  per  cent,  would  be  dangerous?  Some  say  it  may  be 
explained  in  this  way  :  the  rubber  has  not  been  treated  above  the  melting-point  of 
sulphur.  Fawsitt  tested  this  assertion  by  heating  three  pieces  of  waterproof, 
prepared  in  the  cold,  and  containing  more  than  6  per  cent,  of  sulphur,  above  the 
melting-point  of  that  body,  but  Fawsitt  did  not  get  any  efflorescence. 

Disadvantages  of  the  cold  process. — 1.  The  principal  reason  wrhich  has  induced 
manufacturers  to  adopt  the  dry  heat  process  is  that  often  the  cold  process  deteriorates 
the  goods,  and  that  from  causes  which  have  not  been  explained.  This  deterioration 
is  generally  attributed  to  the  oil  contained  in  the  stuff,  but  in  that  case  it  is  only 
accidental ;  without  doubt,  manufacturers  make  defective  mixtures,  but  they  prefer 
to  attribute  the  fault  to  others.  2.  The  injurious  action  of  the  vapour  of  carbon 
disulphide  on  the  workpeople  attending  the  plant.  In  some  manufactories  this 
action  is  reduced  to  a  minimum,  and  does  not  give  rise  to  any  difficulty,  but  it  is 
not  so  in  the  generality  of  factories.  3.  The  greater  number  of  manufacturers  say 
that  goods  prepared  in  the  cold  do  not  stand  hot  climates  nor  cold  climates  so  well 
as  might  be  desired.  In  hot  climates  the  intense  light,  the  heat,  and  the  emanations 
from  the  ground  exert  a  powerful  decomposing  action.  Light  is  the  principal 
agent  of  this  alteration.  4.  It  is  not  possible  to  adulterate  rubber  so  easily 
when  sulphur  chloride  is  used,  which,  in  this  age  of  cheapness,  is  a  matter  of 
great  importance.  Rubber  vulcanised  in  the  cold  is  better  vulcanised  than  by  any 
other  way.  However,  is  it  easy  or  even  possible  to  accomplish  in  the  case  of  cloth 
what  can  be  done  with  a  sheet  of  rubber  1 

Advantages  of  the  dry  heat  process. — The  advantages  of  the  dry  heat  process 
are  explained,  for  the  most  part,  by  the  disadvantages  of  the  cold,  because — 

1.  There  are  few  complaints  as  to  damaged  goods,  and  cloth  with  a  proportion  of 
oil  may  be  used  which  could  not  be  done  in  the  cold  process.     But  if  the  damage 
arising  from  the  action  of  the  stuff  on  the  coating  of  rubber  may  be  greatly  reduced 
in  the  dry  heat  process,  it  must  not  be  inferred  that  this  damage  does  not  exist ; 
and  on  black  and  brown  calico,  a  good  layer  of  rubber  decomposes  within  twelve 
months ;  that  is  due  to  the  mordant  and  the  colours  used.     2.  The  use  of  carbon 
disulphide  is  avoided.     3.  The  coating  of  rubber  resists  great  cold  and  extreme 
heat  better  than  that  vulcanised  in  the  cold.     4.  Cheapness. 

Disadvantages  of  the  dry  heat  process. — As  far  as  the  disadvantages  of 
the  dry  heat  process  are  concerned,  we  have — 1.  The  danger  of  efflorescence, 
the  principal  cause  of  the  complaints  addressed  to  manufacturers;  and  as 
black  paramattas  become  more  and  more  fashionable,  this  is  a  very  important  point. 

2.  The  space  occupied  by  the  stoves.     3.   The  cost  of  vulcanisation  for  a  given 
length  of  stuff  is  double  that  of  the  cold  process ;  this  drawback  is  compensated  by 
the  possibility  of  making  a  cheaper  coating,  but  the  advantage  is  none  the  less  in 
favour  of    the    cold    process.      4.  The  impossibility    of    producing    a    transparent 
coating  which  is  both  supple    and  elastic.     It  may  be  asked  why  the  dry  heat 
process  is  not  used  for  waterproof  goods,  since  it  is  used  for  other  objects.     It  is 
because   although   the  rubber  is   well   applied,   and  with  less  danger  of  efflores- 
cence with  dry  heat,  this  process  would  be  fatal  to  the  colours  of  the  stuff,  and 
to  the  stuff  itself.     Before  the  invention  of  the  dry  heat  process,  the  steam  process 


VULCANISATION   OF   NORMAL  RUBBER  1  •; -.. 

\\.is    u-rd,  I, ut    never   "ii  tin-   larger   Male,  except    f..r   Mark   cloth   ami    \\liit.-   cloth. 
When  manufacturer-    \\li.,  \\ne   accustomi-d    to  \\ork    b\   tin-    -t«  -mi    proce**  and  1>\ 

t!l«-     cold      process     commenced     tn     ll>e     tllr    «lr\      llf.lt      process,     liUllleloUH    ditliru 

8,  \\hieh    \\rrr   nut    ea-ily  overcome.      If.  therefor,-,  \\,-  take  a   pii-ce  of  rul>U*r 

llli\ed    \\itll     I    per  rent,    of    -ulphlir.     aild     llrat    it     to     I  '_'  I      I  .    '    -        K.)   ill    U    Ntn\i* 

\\itlidry    heat,    tin-    rubber   soften-  and    become-    QSeleSSJ    but    if    tin-   same  pic. 
rubber  In-  heated   in  steam,  it    is    -at  i-!actorily    \ulrani-ed.       It    i-    tlm-   D606SSI 
make  dim-mil   mixtures  for  each  kind   nf   coating.       M"ieo\er,  tin-  ditliriilty  of  both 
preventing  efflorescence    and    producing   satisfactory  \ulcaiii-ation   ha-  i-aii-iil  much 
annoyance,    and    experience    has    often    been    gained   l.\   tin-    In--    «.t    emtOOOMn,    tin- 
\\rathrr  IM instituting  tlir  fartnr  \\hich  alVfi-t-  th«-  -air  "I   nilil,.-r  •_' I-  ni"-t    -!i"ii^l\. 

:ill,     IMTSOIIS    arriistuiiiril    to    Iniy    )  I  a  n-| -arrnt ,    \\  r||  tini  >hrd    ^ariiirlit -,    \i-l\rt\    \» 

tlir  tuiich,  an-  nut    rasil\    indm-rd    to    l.iiy  simjilr  \M.\rn    i: Is  \\ith    a   dark  mating; 

a \\antin_i;    in    s..t'tnr-s    to    tlir    lonch,  and    not    so   rla-tir.      (  )t    coiir-.-,  in   ii. 
lii:ht  coloiu-cd  stutl's  it  is  not  so   important  to  avoid  rlllon-crm-.-,  Imt  in  tlir  «-a 
l»lai-k    or   dark    stutl's   it    is    necr-<ar\    to  avoid   it    nmiplrtrly.      Th.-   evil    may    be 
avoided  liy  iisin^  a  hi^h  trni|»rrat  urr  or  a  rout  innoiis  hrat.  Imt  thru  tin-  -tuti'  wotilil 
suffer.     It  has  been  found  that  woollen  stuff  is  attacked  slightly  at  about  ll( 
(iMO*8°   F.),  hence  comes  the  importance  of  heating  .irradnally  and  for  a   longer 
time.     With  the  coating  applied   l>y   the  dry  hrat  prorr—  tlir  tnupcratun*  <-iinnot 
be  allowed  to  go  below  114°  C.  (237'2°  F.),  the  melting  point   of  sulphur.      II 
comes  the  necessity  of  bringing  the  heat  of  the  stove  as  promptly  as  po--il»lo  to 
this   trmprrature.     As  far  as  the  duration  of   tin-    hrat    is  eomvrnrd,   it  dejiends 
entirely  on  the  composition  of  the  coating,  but  it  requires  on  an  average  one  to 
two  boors  at  116°  to  118°  C.  (240'8°  to  244-4°  F.). 

The  use  and  construction  of  stoves  iv«jiiire  much  ]>ractical  knowlrd^r.  Steam 
at  l|  kilos,  (say  of  10  Ib.)  pressure  would  be  more  than  sufficient  to  produce  a 
teni|)erature  of  114°  C.  (237'2°  F.),  supposing  no  heat  was  lost  by  radiation;  but 
in  the  case  of  large  stoves  the  pressure  is  raised  to  L'7  kilos,  (say  GO  Ib.).  It  i- 
more  economical  to  work  with  even  greater  pressure,  for  then  the  heat  may  be 
brought  more  promptly  to  the  melting-point  of  sulphur,  and  more  work  can 
therefore  be  done  in  a  given  time. 

Some  years  ago  Fawsitt's  firm  were  asked  to  supply  a  mixture  capable  of  givini: 
a" transparent  coating  with  dry  steam.  He  made  a  number  of  exj»eriments,  which 
ended  in  the  production  of  a  substance  which  answered  \\ell  for  the  end  in  \ie\\, 
and  applicable  not  only  for  this  special  kind  of  work,  but  a  No  to  other-  \\hich  had 
not  l.een  foreseen.  When  the  laboratory  experiments  were  finished,  the  North 
British  llubber  Company,  Kdinluirgh,  which  had  the  longest  exjH'rience  of  tlir  dry 
process  of  any  firm  in  (Irrat  l.ritain,  were  good  enough  to  make  practical  tests, 
and,  in  1891,  under  the  supervision  of  Mr.  A.  Douglas,  they  succrrdrd.  It  was 
proved  that  this  substance  was  suited  for  the  production  of  transparent  coat. 
audit  was  introduced  into  the  manufacture  of  such  objects  as  fishing  stoekl] 
There  are  therefore  to  be  found  on  the  market  objects  i,o\\  being  manufactured  by 
this  firm,  tlir  most  important  of  which  is  thr  fishing  trousers.  The  rubU-r  is 
exceedingly  snpplu  ;  by  exj>osing  the  stuff  to  not  too  high  a  tein|H-rature,  and  for 
a  short  time,  the  risk  of  acting  on  it  is  diminished.  Two  transparent  .-ampl.'-  \\«  n- 
sprinkled  with  the  same  rubber  as  the  fishing  stockings.  The  silk  sample  was 
sprinkled  in  July  1891,  and  vulcanised  for  thivr  .jnartrrs  of  an  hour  at  116°  C. 
(240'8°  F.).  Another  silk  sample  was  sprinkled  in  .June  1  ^'.»:'>.  and  heated  for  one 
hour  only  at  the  same  temperature.  These  samples,  especially  those  which  were 
very  slightly  sprinkled,  are  >upple  and  pleasant  to  the  touch  and  of  a  beautiful 
appearance.  Two  samples  of  coloured  ,-heet  nil. her  were  prepared  by  Messrs.  \N . 
\Varne  <fe  Co.  These  samples  only  contain  *J  j»er  cent,  of  vulcanising  agent,  tha 
to  say,  of  the  iodides  of  the  heavy  metals  mixed  with  sulphur.  In  his  |>atent  I'.tu-itt 
claims  all  the  compounds  of  iodine  and  bromine  He  found,  however,  that  the 
iodides  and  the  bromides  of  the  heavy  metals  yield  the  best  results:  that  sulphur 
was  necessary,  and  that,  without  it,  it  was  imjHissihle  to  succeed. 


170  INDIARUBBER 

Deductions  and  ro//r/,/.</V*».s\ — The  following  air  tin-  points  established  in 
these  experiments : — 1.  The  minute  amount  of  the  compound  accessary  to 
ensure  complete  vulcanisation.  The  iodide  might  be  reduced  to  1J  per  cent.,  the 
sulphur  being  2  per  cent. ;  3J  per  cent,  of  mixture  does  not  in  any  way  affect 
the  transparency  of  the  rubber.  2.  The  comparatively  low  temperature 
required  for  complete  vulcanisation.  This  point  seems  important,  for  most 
manufacturers  experience  great  difficulty  in  vulcanising  in  a  satisfactory 
manner  at  a  temperature  which  does  not  injure  the  stuff.  The  extreme  sensibility 
of  the  vulcanising  agent  to  heat  was  rather  a  drawback  at  the  beginning  of  the 
experiments,  because  too  near  an  approach  was  made  to  the  operations  made  with 
mixtures  for  dry  heat.  In  the  first  trials,  15  per  cent,  of  iodine  and  6  per  cent, 
of  sulphur  were  used,  and  what  was  astonishing  was  that  these  samples  were 
vulcanised  between  93°  and  96°  C.  (199*4°  and  204*8°  F.),  much  below  the 
melting-point  of  sulphur,  which  was  quite  unusual,  and  proves  that  the  re- 
action which  takes  place  is  quite  different  from  that  which  occurs  in  the  ordinary 
process,  where  there  is  no  apparent  action  below  114°  C.  (237*2°  F.),  even  although 
there  be  a  considerable  proportion  of  vulcanising  agents.  Naturally,  when  such 
a  large  proportion  of  vulcanising  agents  is  used,  a  large  quantity  of  this  product 
remains  useless,  to  such  an  extent  that  it  may  later  on  affect  the  indiarubber. 
This  was  proved  by  heating  a  piece  of  rubber  of  this  kind  between  116°  and  118° 
C.  (240*8°  and  244*4°  F.),  but  for  thirty-nine  minutes  only.  The  piece  became 
quite  hard.  The  property  of  the  vulcanising  agent  of  acting  below  114°  C.  is  not 
of  any  great  importance  at  present,  but  it  may  receive  a  useful  application  later 
on.  3.  The  rapidity  of  the  operation  was  surprising,  for  half  an  hour  sufficed 
when  3  per  cent,  of  vulcaniser  and  2  per  cent,  of  sulphur  were  used;  when  a 
larger  quantity  was  taken,  and  a  high  temperature,  vulcanisation  was  effected  in 
a  few  minutes.  With  15  per  cent.,  ten  minutes'  heating  at  121°  C.  (249*8°  F.) 
was  sufficient.  Rapid  vulcanisation  is  distrusted;  that  is  quite  natural,  for  the 
method  generally  used  requires  no  less  than  two  hours  at  114°  C  (237*2°  F.). 
It  was  found  that,  with  the  new  compound,  it  was  best  to  only  use  a  small  pro- 
portion, and  to  prolong  the  heat ;  but  one  hour  appeared  to  be  sufficient  for  all 
ordinary  purposes  when  1  to  3  per  cent,  of  compound  was  employed  wich  2  per 
cent,  of  sulphur.  With  these  proportions  the  vulcaniser  appeared  to  be  exhausted 
after  one  hour's  heating.  To  prove  it,  Fawsitt  cut  a  piece  of  mixed  rubber  in 
two,  and  heated  one  portion  during  an  hour  at  116°  C.  (240*8°  F.)  and  the  other 
for  three  hours;  at  the  end  of  that  time  both  were  equally  vulcanised.  The 
vulcaniser,  by  acting  so  rapidly  at  so  slightly  elevated  a  temperatute,  is  very 
economical,  from  the  fact  that,  in  a  given  time,  a  stove  can  do  more  work.  That 
is  the  grand  advantage  of  the  dry  steam  process.  Mr.  Waddingtou  has  taken  out 
a  patent  for  a  continuous  stove,  and  Messrs.  Charles  Macintosh  &  Co.  and  other 
manufacturers  use  it.  In  this  stove  the  stuff  is  drawn  slowly  along  ;  it  rises  and  falls 
a  great  number  of  times  before  being  rolled  on  a  cylinder  outside.  It  would  appear 
Lhat  here  fresh  progress  had  been  made,  because  by  this  system  the  stuff  can  be 
tested  when  desired,  and  the  speed  of  the  rolls  regulated  according  as  the  rubber 
is  vulcanised  too  much  or  to  too  small  an  extent.  This  system  also  prevents 
the  false  folds  (kinks)  produced  in  the  ordinary  stoves,  and  will  be  specially 
applicable  when  the  new  vulcanising  agent  is  used,  as  it  is  more  sensible  to  heat 
than  any  of  the  substances  used  in  ordinary  working.  A  difficulty  presented 
itself  at  the  outset,  which  caused  some  annoyance,  but  a  way  was  found  of 
obviating  it.  On  wool,  vulcanisation  was  satisfactorily  effected  ;  not  so  with  calico, 
dyed  brown  or  black.  On  one  occasion  calico  with  black  and  white  squares  had 
been  operated  on.  On  the  black  the  coating  was  soft  and  not  sufficiently 
vulcanised;  on  the  white  it  was  perfect.  As  black  woollen  stuff  was  exempt 
from  this  peculiar  action,  it  could  only  be  due  to  the  different  way  in  which  the 
colours  had  been  fixed  in  the  two  cases.  The  failure  with  calico  was  thought  to 
be  either  due  to  the  mordant  alone,  or  to  the  mordant  combined  with  the  dye ; 
with  cloth  of  many  colours  it  was  difficult  to  say  which  were  those  which  exerted 


VULCANISATION   OF   NORMAL   RUBBER  171 

;lll     injurious      influence.         KaWMtt      therefore     procmvd      ,i     cotton     thread     i|\i-i|     \\itll 

dill'erent  colours,  an. I  made  \\o\en  -trip>  of  il,  »n  \\hirh  he  spivad  the  niKI..-!  pa-te, 
eOBtfcifflllg  a  proportion  of  \ul.-aniM-i  m«uv  than  ulliri.-nt  to  \uli-, ini^-  it.  Alter 
In-ill^  treated  I'm-  two  bOQn  l>et\\een  I  hi  and  11^  <  '.  (240*6  i:id'_'iri  I  .  .' 
was  found  that  tin-  coating  on  the-  white-,  tin-  Mm--,  the  greys,  an. I  certain  shade* 
of  l)n»\\ii  were  perfectly  vulcanised,  but  tliat  tin-  Mark.  ,uid  tin*  deep  KrowiiH 
were  not  sufficiently  vulcanised.  As  it  \\as  the  Mull'  dyed  black  which  hud 
given  the  -Tcatest  amount  of  trouble,  Fawsitt  tried  to  find  out  the  cause  of  it. 
•  inineiiced  liy  taking  the  opinion  of  an  expcrien.ed  .|\.T  to  try  to  lind  out 
what  hud  hern  the  process  employed  in  the  dyeing  of  tin-  thread.  After  a  critical 
examination  lie  said  tin-  mordant  was  an  iron  mordant,  the  tannin  "prepared," 
and  the  dye  logwood.  Fawsitt  then  took  three  pieOM  of  white  calico— 
was  steej>ed  in  a  solution  of  iron  mordant:  N«>.  -  in  a  >olution  of  tanni.  .u  M 
No.  3  in  a  solution  of  logwood.  Fsiwsitt  then  dried  them,  and  .spread  o\.-r  their 
surface  a  paste  of  rubber  of  the  same  composition  as  that  previously  used.  After 
vulcanisation  Fawsitt  dried  them  at  116°  C.  (240'8°  F.),  and  in  each  case  the 
coating  was  of  good  quality;  thus,  taken  separately,  the  reagents  did  not  him  lei- 
vulcanisation.  Three  pieces  of  stuff  were  cleaned  and  treated  as  follows  :- 
was  dipped  into  the  iron  mordant  and  then  into  the  tannic  acid.  No.  2  was  dipjK-d 
into  the  iron  mordant  and  then  into  the  logwood  extract.  No.  3  was  dipped  into 
the  iron  mordant,  then  into  the  tannic  acid,  then  into  the  logwood  extract.  After 
drying,  the  rubber  paste  was  spread  on  their  surface  and  they  W<T«-  n.  ated  as 
formerly.  No.  1  was  vulcanised,  but  Nos.  2  and  3  were  not  vulcanised,  which 
evidently  proved  that  the  fault  lay  with  the  compound  which  was  formed  between 
the  oxide  of  iron  and  the  colouring  matter  of  the  logwood.  Want  of  time  pit- 
vented  this  subject  being  further  studied,  and  the  cause  of  this  action  ascert 
How  could  this  dyeing  mixture  influence  the  iodide  or  the  mixture  of  iodide  and 
sulphur  to  the  point  of  preventing  the  vulcanising  action  1  It  seemed  almost  that 
this  tinctorial  compound  acted  on  the  sulphur,  or  combined  with  it  so  as  to  with- 
draw it  from  the  action  of  the  iodide  ;  for  the  addition  of  supplementary  sulphur 
was  an  antidote,  so  far  as  vulcanisation  was  concerned;  but  was  the  use  of 
this  addition  admissible  in  the  case  of  black  stuff',  on  account  of  the  danger  of 
efflorescence  1  A  possible  explanation  might  be  that  the  cloth  which  is  generally 
sold  might  contain  a  little  mordant  removable  by  washing  or  greasy  matter.  Ac- 
cordingly, pieces  of  stuff  containing  a  good  mixture  of  black  and  brown  were 
treated  as  follows: — No.  1,  treated  three  times  with  ether  to  remove  the  grease. 
No.  2,  boiled  three  times  in  water.  No.  3,  boiled  with  weak  acid,  thru  with 
water.  No.  4,  boiled  with  weak  alkali,  then  with  water.  After  drying,  1 
spread  the  rubber  paste,  and  vulcanised  two  hours  at  116°  C.  (240'8°  F.).  The 
coating  thus  formed  was  of  no  value,  which  condemned  the  theory,  according  to 
which  the  grease  or  the  mordant  remained  in  the  stuff'.  It  has  been  known  for  a 
long  time  that  copper  and  its  comjtounds  exert  a  deleterious  action  on  rubU'r. 
That  opinion  has  been  expressed  by  Thomson  (/  JournaJ, 

p.  328),  but  in  the  case  in  question  there  was  no  copier.  Fawsitt  asked  Mr. 
Christie,  of  the  firm  of  J.  Orr-Ewing  &  Co.,  a  very  com petent  chemist  in  regard 
to  cotton-dyeing,  if  he  could  give  an  explanation  of  this  fact.  He  thought  that 
it  might  be  due  to  the  presence  of  i>eroxide  of  iron,  and  advi>c.l  the  testing  of  a 
piece  of  the  buff  cotton  used  so  much  for  window  Minds  ;  this  stuff  was  free  from 
all  foreign  matter  such  as  tannic  acid  and  campt-aehy  wood  used  in  dyeing  l»n»\\n  <«r 
black.  His  advice  was  followed,  and  it  was  found  that  the  action  of  the  vulcanisini: 
agent  was  retarded,  which  almost  proved  that  the  peroxide  of  iron  was  the  sole 
cause  of  the  failure ;  but  if  that  were  so,  what  w;is  the  reaction  that  took  place  I 
Although  this  was  a  special  question,  and  almost  inexplicable,  the  remedy  was  to  allow 
its  use  on  calico.  This  remedy  consisted  in  first  giving  to  the  stuff  a  coating  of 
pure  iudiarubber  paste  mixed  with  2  per  cent,  of  sulphur,  a  mixture  often  used 
in  the  ordinary  dry  heat  process  to  prevent  efflorescence.  The  study  of  the  action 
of  dyed  fabrics  on  the  indiarubber  coating  is  ini|N>rtant,  not  only  for  indiarubber 


172  INDIARUBBER 

manufacturers,  but  also  for  dyers ;  and  it  seems  that  the  solution  of  the  problem 
ought  not  to  be  left  to  manufacturers,  but  submitted  to  the  dyeing  schools,  \vlio 
pay  but  little  attention  to  this  subject,  Some  rich  indiambber  manufacturers 
would  do  well  to  encourage  the  study  of  these  questions  in  technical  schools.  An 
important  point  is  that  by  means  of  the  new  vulcanising  agent  a  coating  of  coloured 
rubber  may  be  easily  obtained  without  the  addition  of  a  large  quantity  of  pigment 
to  the  rubber.  In  the  ordinary  dry  heat  process  it  is  difficult  to  obtain  a  good 
coloured  coating,  if  only  as  much  pigment  be  used  as  will  enable  the  mixture 
to  retain  its  elasticity.  Coloured  coatings  are  vulcanised  in  a  period  of  time 
depending  on  the  proportion  of  the  vulcaniser  and  the  material  added,  but  the 
general  time  is  from  three-quarters  of  an  hour  between  116°  and  118°  C.  (240'8° 
and  244 '4°  F.).  The  vulcaniser  in  question  mixes  very  well  with  pigments,  but 
some  retard  its  action.  It  seems  that  the  coatings  obtained  with  it  may  be 
finished  without  farina,  because  the  surface  is  dry  and  supple.  This  appears  an 
argument  in  its  favour,  for  farina  seems  to  exert  an  injurious  action  on  the  surface 
of  the  rubber,  because  it  is  liable  to  become  damp,  and  then  ferment.  But  not 
only  so,  the  moisture  brings  the  farina  to  the  surface  of  the  garments,  where  it 
leaves  aggravating  spots.  Fawsitt  adds  that  the  iodide  employed  by  him  in  the 
manufacture  of  fishing  stockings  was  antimony  iodide  chosen  in  preference  to  tin 
iodide  on  account  of  its  cheapness  and  the  good  results  obtained  by  its  use.  He 
also  used  tin  •  iodide  with  good  results ;  but,  having  started  with  antimony  iodide, 
it  was  not  afterwards  thought  worth  while  to  change. 

(2)  Modification   of  Parkes*  process. — Parkes'    modified   method   consists   in 
vulcanising  a  mixture  of   rubber  and  solid  sulphur  chloride  : — Four  pounds    of 
rubber  and  six  and  a  half  pounds  of  solid  sulphur  chloride  are  simultaneously 
put  through  the  mixer.     The  time  required  depends  on  the  speed  of  the  mixer, 
and  the  iveight  of  the  charge.     It  is  therefore  necessary  from  time  to  time  to  take 
samples  and  test  if   the   elasticity  be   sufficiently  developed.     The  mass  is  then 
taken  out,  compressed  in  a  mould,  whilst  still  hot,  and  afterwards  washed.     There 
is  no  advantage  in  this  process,  and  the  trade  do  not  use  it. 

(3)  Humfretfs  process   (British    Patent,    3183;    1863).— The   use   of   carbon 
disulphide,  in  the  steeping  process,  is  attended,  from  a  hygienic  point  of  view, 
with  grave   drawbacks,  which   it    is   important   to    remedy.     Humfrey  therefore 
proposes  to  replace  carbon  disulphide  by  another  solvent,  and,  according  to  him, 
petroleum  spirit  replaces  it  both  economically  and  hygienically.     But  the  petroleum 
spirit  must   be  perfectly  anhydrous.     To    render   it   anhydrous,   60  to   80  kilos. 
(132  to  176  Ib.)  of  petroleum  are  run  into  a  vessel  fitted  with  an  agitator,  and  10 
per  cent,  of  sulphuric  acid  of  168°  Tw.  sp.  gr.  1*84  added ;  the  mixture  is  stirred  for 
some  time,  and  then  it  is  allowed  to  stand  to  allow  the  sulphuric  acid  to  completely 
separate  from  the  hydrocarbide.     The  petroleum  is  then  transferred  to  another 
vessel  by  decantation,  200  to  250  grammes  of  quicklime  per  hectolitre  (from  7  to 
9  oz.  per  22  gallons)  are  added,  as  well  as  a  little  manganese,  and  distilled.     To 
test  if  the  petroleum  spirit  is  dehydrated  enough  to  dissolve  sulphur  chloride,  a 
small  fragment  of  potassium  is  dipped  into  it,  and  after  a  few  minutes,  if  the 
potassium    diminishes    in    brilliancy,    the    petroleum     is    not     dehydrated,    and 
the  potassium  is  covered  with  a  layer  of  potassic  hydrate.     The  function  of  the 
manganese  is  to  absorb  all  traces  of  sulphurous  acid  which  might  be  formed  by 
the   action  of   the   sulphuric    acid   on   the  petroleum.     Petroleum   spirit   is   not 
without  toxic  effects,   although  perhaps  not  so  dangerous  as  carbon  disulphide. 
The  abridgment    of    Humfrey's  English  specification  will   be   better  understood. 
In  it  no  mention  is  made  of  quicklime ;  calcium  chloride  is  the  dehydrating  agent 
specified :    "  Light    spirit  of   petroleum  dissolves  indiarubber  with  great  facility, 
but  on  evaporating  this  solution  the  deposited  gum  remains  sticky,  its  elasticity  is 
destroyed,  and  in  other  respects  it  is  unfit  for  use.     The  cause  of  this  appears 
to  the   inventor   to   be    owing  to   the    petroleum   spirit    being  a   hydrate,    and, 
in    order    to    deprive    it  of  its  water    of    hydration,   100    gallons    of    the  spirit, 
sp.    gr.    0'725,    are    mixed   with    10   gallons   of    sulphuric   acid,    of   a   strength 


VULCANISATION   OF   NORMAL   RUBBER  17:, 

not  less  than  1*840,  and|bmught  into  contact  by  \i«.l«nt  ,i-itati«.n  ;  allowed  to 
stand  I'm-  -mile  tiinr,  the  acid  drawn  nil'  l.y  a  stopcock  from  the  liottoin,  the  acid 
ojtcration  again  repeated,  and  tin-  -pirit  is  drawn  into  a  close  veMc),  avoiding 
exposing  it  t..  air.  e-pecially  damp  air  ;  about  '1  to  '-\  ll».  of  protoxide  of  cud  and 
1  Ib.  of  peroxide  of  n  -•  in  tine  po\\der  mu-t  then  I..-  added  to  100  gall.. n- 

•  >f   >pirit,    and    tin-    mixture    inn>t    In-    \\ell    and    r.  p<-atedly   agitated.      Tin-    -pint    is 

fit  for  use,  an<l  will  become  bright  by  a  fe\\  limn--'  resting.'1  Tlir  patentee  also 
rectifies  tin-  spirit  b\  first  agitating  vsitli  and  then  di-tilling  OW  calcium  chloride. 

At  tlu-  present  da\,  h< .\\e\vr,  thr  petn.ieum  di.-tiller,  wU  a  rectified 

petroleum  sjiirit  equally  pure  \\itli  any  that  could  !•»•  prepared  by  the  above 
process.  It  is  not  neee>-ary  f..r  the  manufacturer  to  multiply  '.pent  inns  by 
becoming  a  petroleum  spirit  refiner  and  rectifier. 

(4)  Gaultier  de  Glaubry's  pruces*. — This  process  (,-imilar  to  Tail  t>  in 
using,  in  place  of  sulphur  chloride,  a  mixture  of  sulphur  and  hy  poehlorite  of  Him.. 
Tin-   mixture  soon   heat-  and  .gives  oft'  sulphur  chloride.      If  tin-  mixture   i 
added  to  the  rubber,  vulcanisation  goes  on  of  its  own  accord,  or  by  aid  of  a  gentle 
heat;  the  results  are  the  same  as  with  I'arkes'  pro,. 

(5)  Gerard's   *<nfintn  polytvlpkidi    (//'>/•   <•/   .<//////////•)   y//-o/rxx. — It    Juts   IH.I-H 
claimed  for  Gerard  that  he  was   the    first  to  use    alkaline    sulphides,   es|H-cially 
p"ta--ium  penta  sulphide,  in  vulcanisation.      Hut  alkaline  sulphides  had  been  pre 
vioiisly   used    1>\    Charles    Hancock    in    the   preparation    of  gut t a    perdi.i    'liriti-h 
Patent,   11,874;   1847),  and  by  Moulton  in  the  vulcanisation  of  rul.U-r  (I'.ritish 
Patent,   13,721;    18ol).      Moreover,    Gerard    di<l    not   (or   could    not)   obtain    a 
British  patent  for  this  purpose.      He  immersed  the  articles  in  a  li\er  of  sulphur  of 
25°  Be.,  and  then  baked  them,  under  pressure,  at  138°  to  140°  C.  (280-4°  to  284°  F.). 
This  process  yielded  excellent  results;   the   rubber   is   vulcanised   well   and   very 
regularly.     When  it  is  carefully  washed  its  surface  is  smooth  and  soft  and  velvety, 
and  does  not  afterwards  t;i\e  any  alkaline  reaction.      Its  great  defect  is  that  it  is 
only  applicable  to  small  thin  articles.      On  boiling,  even  under  ordinary  pre»ure. 
potassium   sulphide  destroys  the  tackiness  of  rubber.     Liver  of  sulphur,  8  to  12 
per  cent,  added  to  rubber,  even  in  admixture  with  oxide  of  zine,  or  carbonate  «,f 
lime  and  quicklime,  gives  equally  good  results. 

(6)  Gerard *s  alkaline  process. — By  another  process,  Gerard  prevents  or  greatly 
9  the  spontaneous  decay  of  blocks  of  vulcanised  rubber  of  certain  size,  a 

which,  with  the  preceding  process,  can  only  be  effected  in  the  case  of  thin  articles. 
It  consists  essentially  in  mixing  lime  slightly  slaked  with  the  rubber,  which,  by  its 
great  fineness,  can  thus  become  incorporated  with  the  interior  of  the  mass.  After 
sprinkling  100  parts  of  rubber  with  a  mixture  of  6  parts  of  sulphur  and  «i  t«»  10 
parts  of  powdered  lime,  the  ingredients  are  thoroughly  mixed  by  passing  the  mixture 
through  mixing  rolls,  heated  between  4;V  and  50°  C.  (113°  and  r_"J  I'.).  Tin- 
mass  is  then  blocked,  cut  into  sheets,  and  made  into  objects  of  any  desired  shaj*'. 
Vulcanisation  is  effected  in  a  closed  vessel  in  a  steam  bath,  at  a  teni|ieratnrr  of 
140°  C.  (284°  F.).  The  operation  lasts  ..ne  and  a  half  to  three  Imurs,  according 
to  the  thickness.  It  then  undergoes  a  kind  of  washing  pmce>s,  in  which  the 
surface  loses  some  of  its  lime  and  sulphur.  It  is  therefore,  less  vulcanised,  yet 
more  supple,  whilst,  in  ordinary  processes,  the  .superficial  layer  is  vulcanised  more 
strongly,  and  is  thus  harder  and  more  brittle.  Thr  pre-ence  nf  lime  in  the  sheet 
is  opposed  to  the  internal  d:  -iient  of  sulphuretted  hydrogen,  and  conse- 

quently to  blowholes.  Again,  the  rubber  cannot  assimilate  an  excess  of  sulphur, 
which  combines,  in  preference  with  the  lime,  to  form  an  alkaline  earthy  >ulphide. 
Gerard  called  the  rubier  vulcanised  by  this  method  alkaline  rubber,  and  claimed 
that  the  substance  Assesses  all  the  properties  of  rubber  vulcanised  by  Goody ear'> 
and  the  potassium  polysulphide  processed,  and  is  Miperi"r  tin-ret"  by  In-ing  more 
tenacious,  from  the  fact  that  it  can  resi>t  temperature-  of  1  >"  ' 
several  years  without  undergoing  any  change,  a  circumstance  which  enables  it  to 
be  used  in  the  making  of  boiler  and  steam-pipe  joints. 

(7)  Burke's  antimony   sulphide  vulcanisation  process.      Antimony  sulphide   i-. 


174  INDIARUBBER 

certainly,  the  most  important  of  all  metallic  sulphides  suggested  or  tried. 
Experience  has,  moreover,  consecrated  it  for  certain  special  purposes.  Hancock 
(British  Patent,  11, 575;  1847)  recommended  it,  with  other  metallic  sulphides,  for  the 
vulcanisation  (sic)  of  gutta  percha,  and  W.  Burke  (British  Patent,  12,591 ;  1849)  for 
the  vulcanisation  of  waterproof  fabrics.  Burke  used  precipitated  antimony  sulphide, 
made  as  follows : — To  1  part  of  crude  antimony  sulphide  25  parts  of  crystallised 
sodium  carbonate  or  20  parts  of  potassium  carbonate  dissolved  in  250  parts  of 
water  are  added ;  the  whole  is  boiled  in  an  iron  pan  for  thirty  to  forty-five  minutes, 
after  which  the  undissolved  materials  are  allowed  to  settle.  The  solution  is  filtered 
whilst  still  hot,  and  the  potash  or  soda  is  neutralised  by  hydrochloric  acid,  in  slight 
excess.  There  is  thus  obtained  a  bulky  precipitate  of  orange  red  antimony  sulphide 
(Kermes),  which,  washed  to  free  it  from  hydrochloric  acid,  is  dried  very  gently  to 
expel  moisture.  Five  to  fifteen  per  cent,  of  Kermes  is  mixed  along  with  the  rubber, 
according  to  the  required  degree  of  elasticity,  then  vulcanisation  is  proceeded  with 
at  a  temperature  of  126°  to  137°  C.  (258'8°  to  278'6°  F.).  Rubber  so  prepared  has 
a  brown  colour ;  it  excels  not  only  in  strength  and  elasticity,  but  also  in  the  faculty  of 
resisting  the  influence  of  the  solar  rays,  and  of  preserving  its  softness  and  flexibility  at 
a  low  temperature — essential  qualities  for  garments.  It  has  the  further  property  of 
not  producing  an  efflorescence  afterwards  on  the  surface  of  vulcanised  articles,  and 
contact  with  metals  is  less  injurious  to  it  than  to  other  vulcanised  rubbers. 

(8)  Moultorts  lead  sulphide  process. — To  this  class  of  processes  belongs  that 
described  in  British  Patent,  11,567  ;  1847  (Moulton) — vulcanisation  by  sulphide  of 
lead.     Moulton  employed  lead  sulphide  for  elastic  articles,  or  mixed  with  magnesium 
carbonate  for  harder  articles  of  greater  tenacity.     This  same  inventor  (British  Patent, 
13,721  ;  1851)  likewise  recommends  a  mixture  of  sulphide  of  lead,  or  zinc  sulphide 
with  salts  of  lead  and  zinc.     Vulcanisation  by  lead  and  zinc  sulphides  appeared  to 
Moulton  to  impart  great  flexibility  to  rubber,  without  inducing  any  efflorescence. 
It  is  the  same  with  the  mercuric  sulphide  process ;  but  the  high  price  of  mercury 
prevents  its  use,  except  where  vermilion  fulfils  the  role  of  both  vulcanising  agent 
and  colouring  principle,  but  otherwise  it  gives  good  results  (British  Patent,  1218; 
1864,  Bateman:  and  2541  ;  1866,  Forster). 

(9)  Turner's  jirocess  is  based  on  the  simultaneous  employment  of  the  sulphides 
of  bismuth  and  lead  (melting  5  Ib.  of  bismuth  and  5  Ib.  of  lead,  to  the  fused 
alloy  of  which  5  Ib.  of  sulphur  are  added).     The  pulverised  mass  is  mixed  in  the 
proportion  of  1  part  with  3  parts  of  rubber,  and  vulcanisation  is  effected  at  a 
temperature  of  138°  to  142°  C.  (280'4°  to  287 '6°  F.).     It  is  claimed  for  rubber  so 
vulcanised  that  it  stands  heat  well.     According  to  Turner  (British  Patent,  305 ; 
1866),  it  would  support  200°  C.  (392°  F.)  without  either  hardening  or  becoming 
brittle.     But  test  experiments  by  Heinzerling  have  not  confirmed  these  predictions. 

(10)  Schivanitz's  glycerine  vulcanisation  process. — This  is  only  a  slight  modi- 
fication of  Goodyear's.     It  consists  in  adding  a  certain  dose  of  glycerine,  and 
heating  in   a  glycerine  bath.     According  to  the  inventor,   rubber  so  vulcanised 
stands  the  actions  of  oils  and  fats  well,  without  losing  any  of  its  other  qualities. 
The  glycerine  is  incorporated  by  itself,  or  a  mixture  of  glycerine  and  solid  bodies, 
such  as  oxide  of  zinc,  chalk,  flowers  of  sulphur.     The  inventor  specially  recom- 
mends the  following  mixture  : — 

;  TABLE  XXXIV. — SHOWING  INGREDIENTS  OF  MIXTURE  FOR  CURING  RUBBER 

BY    SCHWANITZ    GLYCERINE    PROCESS. 


Parts. 

Indiarubber 

3-0 

Chalk        ........ 

3-0 

Glycerine               ....... 

0-5 

Flowers  of  sulphur            .             .             .             .             . 

o-i 

VULCANISATION   OF   NORMAL   RUBBKk 

Article-  manufactured  t'r..in    tin-    mixture  .,ilt  t\\o  li. 

autoclave  at  a  pre--ure  of  al»Miit  l'  at  ino>|  .hdv-.  Tin-  duration  of  the  heating 
dep.-nd-  on  tli.-  thickne--  of  tin-  sheets.  Treatment  uith  pure  glycerine  should 
suffice,  according  to  Schwanit/,  in  tin-  majority  of  cases,  ,.,,.  \,t  i  en.  ler  t  he  i  uhU-r 
unattackalile  by  oils  ami  fat-.  (  >ne  is  at  a  loss  to  understand  ) low  glycerine  by 
itself  i-  capable  of  imparting  thi-  proper!  \  to  rubber.  Its  action  in  pre-en, 
litharge,  \\ith  \\hich  gl\  cerine  form-  a  very  -olid  i.  .  t.int  m.i-tic.  is  readily 

understood.1 

(11)  Thr  iiKtnllix'ttinii  prOMtt  of  tin-  Fi  'aiic'  •  A  liu-i  icaii  Company.  \\  hereby 
vulcanisation  is  effected  (according  to  tin-  .!/«////'///•  Induitriel^  I  N>o,  vol.  vii.  p. 
(ill  liy  tin-  intervention  of  lead  or  antimony  in  impalpable  jw.wder  may  al-o  U- 
mentioned,  but  a  decision  as  to  the  value  of  thi-  pTOOeSS,  t»  tin-  >|M'.-ial  method-  l,\ 
\\liii-li  tliis  mixture  is  applied,  cannot  In-  arrived  at  for  want  of  the  nec.-».ir\  data. 

(!'_')  The  same  remark  applies  to  the  vulcanisation  process  sii^i-Mrd  l.\  A'.//.//-./, 
in  which  sulphur  chloride  is  replaced  l«\  sulphur  Itromide,  the  |tnxjess  not  yielding 
any  marked  advantage  over  the  chloride. 

(l.'i)  Kinally,  the  process  of  Moiireley,  of  Mam-hrMer  (ISSJ),  which  ha-  the 
iindoul.ted  advautap-  of  not  leaving  in  the  rubber  any  ulterior  effect  from  free 
sulphur,  may  be  recalled.  It  consist-  in  vulcanising  rublier  with  '_'  to  :',  JK-I- cent. 
"t  sulphur  in  ammoniacal  solution  of  12  per  cent,  strength,  or  in  the  midst  of 
ammoniacal  vapours. 

I'ti/r.im'&ift'tt/ij.rii/u  -i-ft/xo  called — Definition — Influence  of temperature. — Vulcan- 
isation is  the  result  of  the  heating  of  rubber,  intimately  mixed  with  sulphur  or  its 
derivatives,  in  ;i  stove  or  by  superheated  steam.  The  most  favourable  tcmjirrutmv 
for  vulcanisation  is  from  120U  to  136°  C.  (248°  to  276'8°  F.).  The  ..pinion 
according  to  which  vulcanisation  takes  place  at  110°  C.  (230°  F.)  is  erroneous. 
Hein/crling  proved,  by  a  series  of  direct  experiments,  that  when  rubU»r  is  sub- 
mitted to  a  temperature  of  100°  C.  (212°  F.)  for  four  or  five  hours,  there  is  no 
trace  of  vulcanisation.  For  vulcanisation  to  take  place,  the  melting-point  of 
sulphur,  namely,  113°  C.  (235'4°  F.)  must  always  lie  exceeded.  The  selection  of  tin- 
right  heat  for  vulcanisation,  according  to  circumstances,  constitutes  tin-  most 
delicate  j)oint  of  this  operation.  Too  great  a  heat  scorches  the  material,  which 
thus  loeefl  it<  elasticity,  and  quickly  becomes  brittle,  especially  on  the  surface  :  with 
too  low  a  heat  vulcanisation  is  only  superficial,  and  does  not  reach  the  heart  of 
the  object. 

'/'••</  for  differentiating  between  perfectly  and  imperfect///  ;v//w///.W  ruMier. — 
A  characteristic  sign  by  which  an  incompletely  vulcanised  rubber  may  be  recog- 
ni-e  1  is  to  draw  it  out  at  a  gentle  heat;  if  completely  vulcanised,  the  rubU-r 
easily  i v.issiiine-  its  primitive  form;  if  not,  it  remains  partially  stretched.  If  a 
strong  pre— ure  l>e  exerted  on  incompletely  vulcanised  rubber,  a  permanent  hollow 
is  formed.  • 

I.*, i,ith  ,,('  fun,  required  for  perfect  w/A-<////W/o//. — The  time  reipiired  for 
complete  vulcanisation  depends  on — 1.  The  quality  of  the  rubber,  e.g.,  Para 
rubber  vulcanises  more  slowly  than  soft,  sticky  Mast  Indian  sorts.  •_'.  The  cross- 
section  of  sheet  to  be  vulcanised.  Thin  articles  are  vulcanised  within  the  tir-t 
hour;  thicker  objects  require  two  to  three  hour-. 

Xtnws. — Hot-air  masonry  stoves  were  formerly  used,  the  wrought  sheet  iron 
bottom  of  which  received  the  direct  heat  of  the  tlame  by  means  of  Hues  arranged 
ad  /ioc.  The  objects  to  be  vulcanised  were  placed  in  the  stove  and  kept  at  a 
certain  distance  from  the  bottom  by  means  of  special  hanging  lines,  either 
horizontal  or  vertical,  so  as  to  receive  the  heat  equally  all  over.  These  stoves  arc 
no  longer  used,  except  in  special  cases,  in  the  manufacture  of  varnished  indiarubber 
shoes  and  certain  garments  termed  stove-vulcanised.  But  in  vulcanising  by  hot 
air  the  presence  of  litharge-  in  the  vulcanising  matter  is  indisj>ensable ;  without  thi- 
body  no  vulcanisation  takes  place.  The-e  BtOVOfi  are  at  the  present  day  rephiced 

1  (dycerine  may  neutralise  the  free  fatty  acids  in  the  nascent  state,  and  thus  prevent  them 
from  accumulating  and  acting  on  the  ruM>er. -— TK. 


176 


INDIARUBBER 


by  superheated  water  or  steam  vulcanisers.  The  use  of  steam  under  press  lire 
enables  the  temperature  to  be  regulated  more  easily  than  by  hot  air. — Steam 
vulcanisers. — As  a  steam  bath  there  was  formerly  used  an  apparatus  in  which 
rubber  was  vulcanised,  whilst  at  the  same  time  steam  was  generated  therein. 
These  boilers  are  now  replaced  by  special  apparatus  in  connection  with  a  steam 
boiler.  The  pressure  is  regulated  by  a  valve,  which  is  controlled  by  a  manometer 
on  the  outside  of  the  vulcaniser.  Before  describing  a  vulcaniser  of  this  kind,  it 
will  be  useful  to  give  a  table  of  the  tensions  of  steam  at  different  temperatures 
between  100°  and  150°  C. 

TABLE  XXXV. — SHOWING  THE  TENSION  OF  STEAM  AT  DIFFERENT 
TEMPERATURES. 


Temperature. 

Tension 
of  the  Steam 

Tension  in 

in  Millimetres 

Atmospheres.1 

°C. 

°F. 

of  Mercury. 

100 

212 

760-000 

TOO 

105 

221 

906-410 

1-19 

110 

230 

1075-370 

1-41 

115 

239 

1269-410 

1-69 

120 

248 

1491-280 

1-96 

125 

257 

1748-880 

2-28 

130 

266 

2030-280 

2-67 

135 

275 

2353-730 

3-08 

140 

284 

2717-630 

3-57 

145 

293 

3125-550 

4-11 

150 

302 

3581-230 

4-71 

Karmarsch  andHeeren's  vulcaniser. — The  vulcaniser  illustrated  in  Fig.  69  is  made 
of  very  strong  wrought-iron.     It  is  often  14  to  20  metres  (say  45  to  65  feet)  long, 


FIG.  69. — Karmarsch  and  Heeren's  vulcaniser. 


which  enables  comparatively  large-sized  pieces  to  be  treated.  To  prevent  india- 
rubber  tubes  being  deformed  in  vulcanising,  they  are  mounted  on  an  iron  mandrel, 
the  diameter  of  which  corresponds  with  the  inside  bore  of  the  tubes.  This  vulcaniser 
is  50  to  65  feet  long,  with  a  diameter  of  16  to  20  feet.  Its  construction  is  identical 
with  an  ordinary  steam  boiler.  The  body  of  the  cylinder  is  provided  at  its  open 
end  with  a  cast-iron  flange,  fitting  an  identical  projection  on  the  lid,  so  as  to  form 
an  autoclave.  Sometimes  the  projection  of  the  door  fits  into  a  groove  made  round 
the  body  of  the  cylinder,  and,  so  that  closing  may  be  perfect,  half  filled  by  packing 

1  The  pressure  in  Ib.    per  square   inch   may  be    approximately  got   by  multiplying  the 
atmospheric  tension  by  15. 


VULCANISATION   OF   NORMAL   RUBBER 


177 


n>n<i-tiiiur  "f  -.r)  parts  of  to\v  ami  7")  part-  <»f  supple  alkaline  rubber.  The  lid  fiu 
int«»  this  projection  hy  means  of  collar-.  da-|>-,  hint's,  ami  IK>IU.  Moreover,  it  can 
In-  moved  l-y  lixed  taekle.  ««r  ;i  -mall  iT.me  \\hich  f.irilitat.-s  it-  iiiaiii|iiilation,  §O 


FIG.  70.— Apparatus  for  vulcanising  small  objects  by  high-pressure  steam. 


that  it  can  either  be  taken  away  from  or  brought  back  and  fitted  to  the  mouth  of 
the  cylinder.  To  facilitate  the  introduction  of  the  articles  to  be  vulcanised,  a 
tramway  is  laid  down  on  the  bottom  of  the  boiler,  on  which  moves  the  small 
waggons,  mounted  on  wheels,  and  fitted  up  to  receive  the  objects  to  be  vulcanised, 


1  ic.  71.— Coster,  Rickkers,  &  Co. 's  steam  vulcanis.r. 

either  laid  on  the  flat  or  hung  up  as  occasion  may  require.  A  steam  pipe,  fitted 
with  a  stopcock,  spreads  the  steam  uniformly  throughout.  It  goes  right  along  the 
upper  part  of  the  cylinder,  and  its  lower  part  is  perforated  by  an  infinite  uuml  er 


12 


178 


JNDIARUBBER 


of  small  holes.  The  cylinder  is  surmounted  by  a  safety  valve,  and  a  blow-off  cock 
for  either  air  or  condensed  water  is  fixed  to  the  lower  part.  The  inside  of  the 
boiler  is  furnished  with  a  number  of  hollow  cylinders,  provided  with  springs  and 


FIG.  72. — Vertical  steam-cased  vulcanisation  pan. 

supports  intended  to  keep  the  laminated  sheets  entabled  on  the  wrought-iron  plates. 
The  interior  arrangement  may  vary  from  one  factory  to  another,  according  to 
particular  requirements  of  special  branches  of  the  industry. 

Vulcaniser  for  small  objects  by  high-pressure  steam. — Fig.   70  shows  another 


VULCANISATION   OF   NORMAL   RUBBER 


179 


form   lit'   viiliMiii»iiiM    ln.il. -r,  n>cd   r>|H-cially  fur  small   ol.|cct».    ;m<l   I.T   \ul«, 
l-y    ni'-an-    nf    \\at.T     ln-.ili-:|    |,y    high  p:  '••alii.       It    i>     «i<>     !•.     <',:>     ii,. 

diameter  .mil   frmii    1C.  to  '_'<>  tret    in   Irn^tli. 

Tin-  Imilrr  .1   in. IN    1  «•  lmri/.i»iil;il  "i-  vnlir.il.       It'    \rrlir.il,  it    i-   j.r..\  i.|,-«|  \\n\t  an 
iih-nt   for  taking  off  and  imttin^  «iu   llu-   li'l  •/.       ll  Inii-i/niilal.  tlii>  li.l  « ,in  I,- 
niaiii|i||lati-il    at    \\ill    \>\    a   -iniilar   arr.iii^f|ii.-ni.       In   llial   .  a-«    a   \\aggOD   D1O1 

rail-  N  iu-t.ill-'tl  in  ilu-  lutilrr  to  >iij»|.«.it  the  objects  to  be  vulcanised  encloaed  in 


their  iron  moulds.      The  pipe  I,  n.imiiimi.-atis  uith  tl.o  >teani  lM.il.-r.      Tlie  p; 

in  tin-  iiitrriui-  ,,f   the  vulranisrr   is    iv^ulatr.l    l.\   a  \al\r;    ///   >li.,\vs  the  maimim-trr 

(steam  gauge),  and  c  tlie  l>l<»\v -otl'  (•••••k. 

//,,? .//-,//,  ,•/-,//.•;/*/.<.  ,-x.     These  are  -imilar  t«.  -t.-am  mlcanisera,  only  they  are 

iixed  in  a  vertical  position  ami  contain  \\ater  iij>  t<»  a  certain  level.  I  he  steain 
rcarln-s  the  \iilcanis,T.'rai-rs  thr  ti-niiieratun-  «•!'  the  \\aterfn-ni  I'J.i  to  130  C. 
(_~)7  t"  -'>»'.  I-'.),  and  vulcanises  tlie  articles  dipping  into  it. 

ttoam  vulcanuer.  -This  is  shown  in  Fig.  71.     By  fixing  it   vertically 


180 


INDIARUBBER 


and    suppressing  the  rails,   it   can    likewise   be   used    for    vulcanising    with   hot 


Steam-jacketed  pans  as  vulcanisers.  —  Double-bottomed  vessels  (steam-jacketed 
pans)  may  also  be  used  in  vulcanising.  The  steam  is  introduced  between  the  two 
cylinders,  and  heats  by  radiation  the  air  contained  in  the  inside  cylinder,  and 
consequently  dry  vulcanises  the  objects  it  contains. 

Vulcanising  2>ress  or  vulcanisation  by  contact.  —  It  is  an  advantage  in  a  rather 
large  establishment  to  have  a  small  vulcaniser  in  which  to  perform,  without  any 
great  expense,  experiments  on  the  vulcanisation  of  certain  rubbers  or  of  certain 
mixtures.  These  small  utensils  are  called  monkeys  (marmots).  For  this  kind  of 
work  (1)  screw  presses,  (2)  screw  presses  with  hinged  levers,  and  (3)  hydraulic 
presses,  etc.,  are  used. 

1.  Screw  presses.—  The  apparatus  is  arranged  like  a  letter-copying  press.  They 
consist  of  two  hollow  plates,  heated  in  the  interior  by  steam.  The  lower  plate  is 
fixed,  and  rests  on  a  table  or  support.  The  upper  plate  is  raised  and'  lowered  by 


Fro.  74. — Single-screw  vulcanising  press 
with  all  accessories.  Plates,  600  by 
600  millimetres. 


. 

FIG.  75.— Hand  power  vulcanising  press.  Plates, 
1250  by  1250  millimetres  (say  50  by  50 
inches). 


means  of  a  male  screw  turning  in  a  fixed  female  screw,  drilled  out  of  the  cross- 
piece.  It  is  guided  in  its  movements  by  the  lateral  columns.  A  manometer  or 
steam-pressure  gauge  communicates  with  one  of  the  plates,  so  that  the  steam 
pressure  may  be  ascertained  and  regulated  by  a  valve  fixed  on  the  steam  arrival 
pipes.  Articles  made  of  mixed  rubber  are  placed  in  moulds  between  the  two 
plates  of  the  press,  which  are  strongly  compressed.  The  length  of  time  taken 
varies ;  generally  matters  are  so  arranged  that,  with  a  pressure  of  between  2  J  and 

4  atmospheres,  vulcanisation  is  complete  in  two  hours  at  the  furthest.     The  time 
taken  is  often  reduced  to  an  hour,  and  even  to  half  an  hour.     All  depends  on  the 
proportion  of  the  sulphur,  the  steam  pressure  in  the  plates,  and  the  nature  of  the 
mixture.      The  two  organs  being  suitably  proportioned,   single-screw  presses    are 
constructed,  with  plate,   1   metre  (say  3  feet  3  inches)  to  1^  metres  (say  4  feet) 
square.     The  largest-sized  presses  have  plates  which  measure  3  to  4  metres  (say 
10  to  13  feet)  in  length,  with  a  width  of  1  to  1J  metre  (say  3  feet  3  inches  to 

5  feet).     These  machines  are  provided  with  two  or  three  pressure  screws.     So 
that  the  upper  plate  may  descend  regularly  and  bear  uniformly  throughout  all  its 


VULCANISATION   OF   NORMAL   RUBBER 


181 


t,  all  thr  screws  should  act  conjoint l\.      Kadi  sere*  carriec  MM  its  upper  part 
ft  toothed  wheel  of  the  same  diaineter.      Ka«-h   ..f  these   \\li.-«-|>  ^-ar-   \\itli  a  corre- 


FIG.  76. — Hand-power  screw  vulcanising  ] 

siK)ncling  endless  screw,  arranged  on  a  horizontal  shaft,  which  may  l>e  driven 
troin  a  fly-wheel  or  by  means  of  pulleys  drivm  1>\  the  factory  shaft,  which  in  that 
ease  works  tin-  movements  of  the  upper  plate  mechanically. 


Fn;.  77. — Vulcanising  press — doubte-flcreW — Leblanc  system. 


182 


INDIARUBBER 


la.  LeblanJs  double-screw  vulcanising  press. — This  press  is  shown  in  Fig.  77, 
and  is  of  the  two-screw  type  (Leblanc's  construction).  The  upper  plate  is  wrought 
mechanically.  It  is  3  metres  (say  10  feet)  in  length  and  4  metres  (say  13  feet) 
in  width,  which  dimensions  enable  it  to  be  used  for  vulcanising  indiarubber  belt 
and  sheeting. 

2.  The  screw  press  with  hinged  levers  is  less  common,  although  it  does  good 
work. 

Mongirts  three-plate  vulcanising  press. — This  press  consists  of  a  horizontal 
screw,  the  one  half  with  a  left  thread,  the  other  half  with  a  right  thread ;  four- 
hinged  levers ;  two  hollow  plates,  and  a  suitable  frame.  Two  levers  are  hinged,  on 
the  one  hand,  to  a  first  female  screw  which  surrounds  the  male  screw ;  and,  on  the 
other  hand,  one  to  the  movable  plate  and  the  other  to  the  fixed  head  of  the  press. 
The  two  other  levers  are  arranged  in  the  same  way  in  relation  to  a  second  female 
screw  on  the  other  part  of  the  male  screw.  By  working  with  a  fly-wheel,  gearing 


FIG.  78. — Vulcanising  screw  press  with  three  plates — Mongin's  strengthened  system. 

on  to  the  horizontal  screw,  the  female  screws  approach,  or  cause  by  means  of  the 
levers  raise  or  lower  the  suitably  guided  movable  plate.  The  hollow  plates  are 
heated  by  steam,  and  the  articles  arranged  in  moulds  are  compressed  between  the 
plates  as  in  the  ordinary  screw  press. 

Press  with  cylindrical  guide. — Coster,  Kickkers,  &  Co.  construct  cylindrical 
guide  screw  presses  of  a  particular  pattern.  The  screw,  wrought  by  a  shock  fly- 
wheel, acts  on  the  upper  cast-iron  plate  with  a  cylindrical,  vertical,  mobile  body 
placed  inside  another  fixed  cylinder.  The  plates  thus  remain  quite  parallel,  and 
the  pressure  is  very  uniform. 

3.  Hydraulic  press. — In  the  hydraulic  press  the  motion  of  the  plate  is  obtained 
by  water  pressure  and  by  the  intermediary  of  accumulators.  The  two  plates  are 
heated  in  the  ordinary  way,  and  compress  the  articles  introduced  into  the  moulds. 
This  class  of  press  is  used  more  especially  to  vulcanise  transmission  belts.  The 
plates  then  often  reach  4  to  5  metres  (say  13  to  16J  feet)  in  length,  and  1  to  1 J 
metre  (say  3  feet  3  inches  to  4  feet)  in  width.  A  three  "  nip  "  hydraulic  press  is 


VULCANISATION   OF   NORMAL   RUH1.I  U 


183 


Sri 


0 


•  — 

! 


184 


INDIARUBBER 


shown  in  Fig.  81.  The  plates  are  guided  by  four  uprights.  Fig.  80  shows  a 
hydraulic  press  for  belts,  driven  by  six  pistons.  The  powerful  machines  are  also 
made  by  the  Birmingham  Iron  Foundry. 

Vulcanisation  of  hollow  articles. — Hollow  articles,  such  as  balloons,  dolls,  etc., 
are  first  of  all  put  together  and  "soldered,"  then  a  small  quantity  of  volatile 
liquid,  without  action  on  the  substance  (water,  ammonia,  etc.),  is  introduced,  and 


1 

i 

\ 

i 

J  —  1 

q 

i 

T 

! 

! 

] 

the  article  carefully  closed  up.  In  this 
state  they  are  heated  and  vulcanised  in 
moulds  of  one  or  more  pieces.  When  the 
heat  begins  to  act,  the  water  is  converted 
into  vapour"  of  a  certain  tension,  the 
ammonia  is  volatilised,  and  the  gases  thus 
generated  exert  sufficient  pressure  to  push 
the  pellicle  of  rubber  against  the  sides  of 
the  mould,  which  impresses  itself  to  the 
verv  minutest  details  on  the  sheet  of  hollow 
rubber.  In  addition  to  these  machines, 
FIG.  81.— Plan  of  hydraulic  vul-  each  factory  may  design  and  construct 
canising  press  with  six  plates  appropriate  machines,  based  on  the  same 

principle  of  vulcanisation,  for  each  special 

article  of  manufacture,  such  as  the  hollow  rings,  the  envelopes  for  pneumatics 
(air  and  gas  vessels  and  appliances,  bicycle  and  motor  car  tyres),  etc. 

Decauville's  vulcanising  presses  are  fitted  with  hollow  plates,  in  the  interior  of 
which  steam  circulates,  and  the  presses  maybe  either  one  "  nip  "  or  two  "  nip  " ;  each 
hollow  plate  has  three  unions,  one  for  steam  inlet,  a  second  for  steam  exit,  and  a 
third  for  the  pressure  gauge. 

Preserving  the  initial  form  of  manufactured  ruller  during  vulcanisation. — 
During  vulcanisation,  whatever  may  be  the  shape  of  the  rubber,  it  will  soften, 
under  the  influence  of  heat,  so  as  to  warp  or  assume  the  imprints  of  the  supports 
which  keep  it  in  position,  if  care  be  not  taken  to  ensure  the  preservation  of  the 


VULCANISATION   OF   NORMAL    RUBBER 


185 


I 

.2 

t 


IMMMNIV 


186 


INDIARUBBER 


shape  by  suitable  packing.  Tubes  are  vulcanised  on  mandrels,  which  sufficiently 
preserve  their  shape.  Cushions,  rings,  and  articles  are  enclosed  in  special  iron  moulds. 
Solid  articles  are  placed  in  sheet-iron  cases  lined  with  talc,  sheets  of  a  certain  size 
between  sheet-iron,  and  thin  sheets  rolled  on  a  drum  with  calico  linings. 

Blowholes  and  their  remedy, — During  vulcanisation  a  defect  often  occurs,  as 
difficult  to  avoid  as  to  explain,  namely,  blowholes  which  form  on  the  surface  of 
technical  article-;,  or  which  in  lined  articles  (caoutchouc  and  canvas)  even  sever  the 
two  substances.  The  trade  market  refuses  articles  of  this  kind.  Experience  shows 
that,  where  these  blowholes  occur,  a  rupture  is  always  to  be  feared  in  time.  They 


FIG.  84. — Three  "  nip  "  hydraulic  press  for  vulcanising  rubber  sheets  6  ft.  4in.  by  4  ft.  4  in. 

are  due  to  the  use  of  imperfectly  dried  rubber  or  to  incomplete  evaporation  of  the 
solvent  in  lined  articles.  The  preparatory  mechanical  working  of  too  fresh  rubber, 
and  more  especially  the  compression  exerted  on  the  mass  by  the  tools,  collect  the 
interstitial  water  into  small  vesicles,  which,  under  the  influence  of  heat,  become 
converted  into  steam,  and  thus  form  the  bells  on  the  spots  where  they  occur.  The 
substance  often  becomes  quite  porous,  not  only  on  the  exterior,  but  also  in  the 
interior.  It  is  recommended  to  remedy  this  first  drawback  by  adding  from 
\  to  1  per  cent,  of  quicklime,  so  as  to  absorb,  in  the  mixer,  all  the  interstitial 
moisture,  experience  having  proved  that,  after  this  addition,  the  wrought  rubber 
only  very  rarely  showed  this  defect.  As  to  separation,  this  especially  occurs  in 


VULCANISATION   OF   NORMAL   KlT.nr.k 


lined  articles,  made  l.y  tin-  interposition  of  a  solution  of   rubber  l,.-t  NV.-.-II  tin-  -h 
ot'dotli,    an. I    not    in    the  case  of    laminated    sheets,    and    it    is    tin-    -.,|\,-nt,   c.iiU.n 

disillphide,    ben/.ol,    etc.,    \\llirll     SO    acts    518    to    plVNelit     JU I  lleiviire.        (ViUlli     ,.\; 

think   that    it    i>  <lur   t<»  sulpliurnu^   ;n-itl    ur«-ii.'iMtr.|   ilurin^  vnl<-ani>iition.      Tli. 
not   so,  ami  o\i.lr  ..f    lead   aiMol  to  al»sorl»   siil]>liur«ius  r    |.r«-\ni!«-il    l.|o\\ 

holes    I'roin    l.»-iiiur    I'-minl.      Attention    has    ahva.l\    l.r.-n   drawn  to  the  action    of 


I'n;.  85.      llv'lr.iulir  vulcanising  autoclave  (Dccauville,  Paris). 

iin]»uritii-<,  an<l   of  oxidise,!   rnl.l.er  ii|»on  sulphur,  and  it  i-  |...>-il-K'  that    th- 
pMirratcd  h\   -iich  n-artimis  aid  tin-  f"rniation  of  tlu-st-  l>lo\\ho|r<. 

////J/vf ////,-  ,,,it,H'ln>>,    preua      1  >,«<•,-, /.timi. — The   nuinrrous  advantages  of  vul- 
canisation in  dosed    vrsseU  have  led  to  the  stinlv  <>f   new  type-  ..f  hydraulic  i 
coinliininu-    the    principle    of     the     autoelave.      The    auto.-la\c    is    cylindrical,    and 
consists  of  an  iron  plate  rivetU'd  to  a  Hango  <T  collar  and  a  bottom  ol  I.      It 

is  fixed  to  the  lid  by  means  of  the  collar,  and  is  closed  by  nuts  and  screw  bolts. 


188  INDIARUBBER 

The  cast-steel  bottom  of  the  autoclave  carries  a  stuffing-box  in  which  the  piston  of 
the  press  glides.  The  moulds  placed  on  the  plate  are  therefore,  whilst  subjected 
to  hydraulic  pressure,  in  an  absolutely  closed  space,  and  are  thus  brought  to  a 
strictly  uniform  temperature.  This  autoclave  moves  in  a  vertical  direction  by 
three  hydraulic  methods  of  working.  When  it  is  about  to  be  charged  the  autoclave  is 
lowered  by  means  of  the  three  hydraulic  methods,  then  the  piston  of  the  press  is  caused 
to  ascend  and  consequently  the  plate  in  such  a  way  that  the  latter  is  level  with  the 
upper  part  of  the  autoclave.  It  is  charged  with  moulds,  and  the  piston  lowered 
gradually  to  a  height  equal  to  that  of  the  moulds  on  the  plate.  Once  charged  the 
autoclave  is  raised  by  means  of  the  screwjack  of  the  press.  All  that  has  to  be  done 
now  is  to  turn  on  steam  on  to  the  autoclave.  During  the  operation  the  autoclave 
rests  on  the  screwjack  in  constant  communication  with  the  accumulator,  conse- 
quently the  expansion  of  the  autoclave  occurs  freely.  When  by  inadvertence  the 
communication  between  the  screwjack  and  the  accumulator  are  obstructed,  Belle- 
ville washers,  placed  between  the  bottom  of  the  autoclave  and  the  top  of  the 
pistons,  will  give  sufficient  play  for  this  expansion.  The  usual  dimensions  are — 
power,  70  tons;  hydraulic  pressure,  per  square  centimetre,  100  kilos. ;  diameter  of 
the  plate,  1  '2  metre ;  course  of  the  piston,  1  *2  metre ;  useful  space  in  height, 
1*5  metre;  approximate  weight,  9  tons.  The  autoclave  is  fitted  with  three 
adjustments,  namely,  steam  injection,  steam  exit,  and  pressure  gauge. 

Theoretical  review  of  vulcanisation. — The  effects  of  vulcanisation  are  due  to 
ill-defined  causes,  as  yet  hardly  understood.  The  chemical  reactions  which  occur  in 
the  process  have  hardly  been  studied,  far  less  satisfactorily  explained.  Authorities 
are  all  more  or  less  undecided.  They  describe  vulcanisation  as  the  result  of  an 
"  absorption  "  of  sulphur,  but  omit  to  state  exactly  what  they  mean  thereby.  They 
acknowledge  that  the  rubber  absorbs  2  per  cent,  of  sulphur,  but  they  do  not  agree 
as  to  the  nature  of  that  absorption.  Some  state  that  vulcanisation  is  the  result  of 
a  real  chemical  reaction,  commencing  at  120°  C.  (248°  F.)  and  terminating  at 
160°  0.  (320°  F.).  Vulcanisation  properly  so  called,  i.e.  the  transformation  of 
normal  rubber  into  a  rubber  which  is  pliant  and  elastic  in  all  temperatures,  would 
be  the  starting-point  of  this  reaction,  and  the  production  of  hardened  rubber,  ebonite, 
the  final  result  1.  Pay  en  sums  up  the  reactions  which  occur  as  follows: — "As 
soon  as  the  sulphur  commences  to  react,  and  during  the  whole  process,  i.e.  between 
135°  C.  (275°  F.)  and  145°  C.  (293°  F.),  combination  of  sulphur  with  a  small 
quantity  of  the  hydrogen  of  the  organic  body  takes  place,  and  there  is  thus  a 
continual  formation  of  sulphuretted  hydrogen,  of  which  the  sulphur  may  absorb  as 
much  as  its  own  volume ;  hence  a  peculiar  phenomenon  results  in  working  with  the 
bath  process  :  when  the  temperature  lowers  after  vulcanisation,  the  sulphur  in 
crystallising  liberates  a  portion  of  sulphuretted  hydrogen.  This  gas  is  disengaged 
between  the  crystals,  and  rises  up  the  semi-fluid  mass.  The  converse  occurs,  and 
contraction  is  manifested  during  the  cooling,  and  the  sulphur  crystallises  exempt 
from  sulphuretted  hydrogen."  Payen,  having  examined  a  sheet  of  rubber  vulcanised 
by  the  bath  process,  found  that  the  sulphur  combined  with  [the  rubber  was 
unequally  distributed  in  gradually  decreasing  proportions  from  the  interior  of  the 
pores  to  the  dense  portion  of  the  organic  substance.  "  Thus,"  says  he,  "  there  can 
be  perceived,  under  the  microscope,  concentric  circles  indicating  this  decrease,  and  we 
can  extract  in  rotation,  by  appropriate  solvents,  carbon  disulphide,  ether,  etc., 
4  per  cent,  of  caoutchouc,  1  to  1'5  per  cent,  of  fatty  matter,  besides  the  free 
sulphur."  Payen's  theory,  supported  by  arguments  developed  above,  is  not  con- 
clusive. Disengagement  of  sulphuretted  hydrogen  might  proceed  from  a  small 
quantity  of  rubber  decomposed  by  sudden  immersion  in  sulphur  at  the  high 
temperature  of  its  melting-point,  otherwise  the  disengagement  would  not  cease, 
even  after  the  goods,  vulcanised  by  steeping,  had  been  sufficiently  washed  with  an 
alkaline  solution,  which  is  not  the  case.  The  latter  remark  of  Payen  is,  moreover, 
in  contradiction  with  the  first,  and  indicates  at  least  that  chemical  combination, 
if  it  does  exist,  is  only  partial,  since  the  combined  sulphur  is  unequally  distributed 
in  decreasing  proportions  from  the  interior  of  the  pores  to  the  dense  portion  of  the 


VULCANISATION   OF   NORMAL  RUBBER  189 

organic  matter,      i'.    /A ///-.» /•//////,  for  different  reasons,  and  in  a  much  less  affirm  a 
five  manner,  believes  also  in  real  chemical  combination.     ••  \\  V  do  not  yet  know, 

really,    whether    suljiliur,    in    combining  chemically    \\ith    rubber,    f«.nns    a    simple 
juxtaposition  of  an  addition  product  or  if  it  >nl.st  it  ntrs  itself  partialK   for  h\dr-.. 

Tli'it  flu  combination  oftulpkw  fif/i  rubber  fonm  »  /•"//  i-ln  nm-nt  <•"//,/  </,///./  //•«////,/ 
fi/,/»<ir  tn  i,<  tli,  nn<i, , iii.t, <i  ,-,*nit  ot'  //>'  r'.ir/  f/i.i/  rubber  and  tulphvr,  both  .>••//»//,/. 

//*«•»//•/„,//  »//>•////////. A    /»/.„-,    I,,!, 1,1  ,<!„,*,, I  I,,   /,,, it, .'if    liianlulilt   /// 

The  proof  seems  a  decided  on.-,  am)  \et,  metallic  sulphide-,  like  antinion\   >ulphide, 

throughout     all     r\.-r||r||t    lliea!l-o|     \  1 1  |ra  1 1  i>at  iul  1,    l»llt     are    ill     llo    \\JIV    soluble     ill 

carbon  disulphide.  This  also  is  the  case  with  the  sulphide-  of  im-p-ury  and  lead. 
Vet  two  metals  may  have  isolately  certain  properties  which  disappear  completely 
when  they  are  united,  not  by  a  simple  mixture  but  through  the  intervention  of 
heat,  through  alloying,  which  very  often  gives  them  diametrically  oppo>ite  pro 
perties.  '.\.  l'iKi<'r  agrees  up  to  a  certain  point  with  Hein/erling,  but  for 
ditlerent  reasons.  "  We  do  not  know,"  says  he,  "the  nature  of  the  organic  sulphur 
compound  formed  by  vulcanisation ;  it  miyht  be  possible  that  the  white  coating 
formed  on  the  surface  of  the  large  lumps  of  rubber,  which  appears  under  the  mien. 
scope  as  small  brilliant  crystals,  consists  of  sulphur  and  hydroearbide,  and  that  it 
is  this  compound  which,  spread  throughout  the  mass,  communicates  to  it  tin- 
properties  of  vulcanised  rubber."  It  has  now  been  proved  that  this  efflorescence  is 
no  other  than  crystallised  sulphur,  and  that  the  contraction  of  the  cooled  globulite- 
push  it  to  the  surface  of  the  indiarubber.  4.  Vulcanisation  I  i>y  t/te 

"<-f  inn  of  presence. — Certain  authors  try  to  explain  thu  effects  of  vulcanisation  by 
the  theory  of  juxtaposition,  by  the  action  of  presence,  "catalysis."  This  theory 
is  simple  and  easily  formulated,  but  it  proves  absolutely  nothing,  and  is  in  flagrant 
contradiction  with  facts.  The  action  of  presence  might  in  case  of  necessity  justify 
the  increased  suppleness,  the  greater  elasticity  of  the  rubber ;  but  how,  then,  can 
the  absolute  insolubility  of  the  really  vulcanised  rubber  in  carbon  disulphide  be 
explained1?  How  can  a  greater  resistance  to  chemical  reagents  be  explained1? 
How  is  the  transformation  of  vulcanised  rubber  into  ebonite,  by  an  elevation  of 
temperature,  a  prolongation  of  the  process,  and  an  increase  of  the  sulphur,  to  be 
interpreted  1  How,  finally,  in  vulcanisation  by  steeping,  can  there  be  disengage- 
ment of  hydrochloric  acid  according  to  this  theory1?  5.  Vulcanisation  an 
indefinite  combination  as  in  alloys. — A  certain  number  of  chemists — e.y.  Donath — 
consider  vulcanisation,  not  as  a  phenomenon  of  a  purely  chemical  order,  resolving 
itself  into  combination  in  definite  proportions,  but  the  formation  of  molecular 
combinations  in  indefinite  proportions,  as  is  supposed  to  occur  with  certain  series 
of  alloys.  They  urge  against  combination  in  definite  proportions  the  objection 
that  vulcanisation  is  produced  equally  well  with  a  metallic  sulphide  as  with  free 
sulphur.  How,  then,  can  the  sulphides  of  antimony,  mercury,  or  lead  abandon 
the  whole  of  their  sulphur  to  some  complex  rubber  com^und?  rnvulcanised 
rubber  hardens  at  moderately  low  temperatures,  whilst  it  softens  and  loses  its 
elasticity  when  it  is  heated  between  50°  C.  and  60°  C.  (122°  F.  and  140°  F.),  and, 
moreover,  its  resistance  towards  reagents  is  feeble.  But  vulcanised  rubber 
preserves  its  elasticity  both  in  the  heat  and  in  the  cold,  resists  chemical  reagents 
better,  and  behaves  altogether  differently  towards  solvents  and  reagents.  These  pi  •  >- 
perties  recall  those  of  alloys,  whose  behaviour  is  so  often  dissimilar  to  that  of  their 
com|K)nents,  even  when  one  exists  only  in  but  relatively  minimum  proj>ortion8. 

Vulcanised  rubber  may  tfterefore,  be  regarded  as  a  sort  of  alloy  of  the  "/•</<//>/<• 
of  the  rubber  with  .tn/^hur  or  with  a  .W/ >///'•/•,  or  >'•'<>  >'-ifti  *u/j'hnr 
,  bromide,  or  iodide.  This  condition  /*  not  »V/////,/'//»///M//  properly  to-caUed^ 
t'ro,,t  o'hich  th>>  fonnntion  of  a  well-defined  clomir.il  i ,,,11  ri,l n.iliti/  ,i-,,,il,l  r<.<ii/f; 
it  differs,  however,  from  simple  solution  or  mechanical  mixture.  Neither  of  these 
three  explanations  of  vulcanisation  is  satisfactory,  if  taken  individually,  and  their 
collection  into  a  well  co-ordinated  single  aggregate  would 'at  the  most  be  capable  of 
giving  a  barely  plausible  theory.  Vulcanisation  is  not  the  same,  whether  free 
sulphur  or  sulphur  chloride,  or  even  and  more  especially  metallic  sulphides,  be  the 


190  INDIARUBBER 

vulcanising  agents.  6.  Vulcanisation  by  free  sulphur.— Before  formulating  any 
theory  relative  to  this  process,  it  is  right  to  recall  some  properties  of  normal  rubber, 
which  ought  constantly  to  fix  the  attention  of  any  one  who  wishes  to  study  the 
phenomenon  of  vulcanisation.  Hitherto  the  action  of  sulphur  and  its  derivatives 
on  normal  rubber  has  more  especially  engaged  attention,  but  neither  the  result  of 
the  action  of  heat  at  different  degrees  of  intensity  on  normal  rubber,  nor  the  mode 
of  action  of  different  vulcanising  agents  at  these  different  temfieratures,  in  presence  of 
rubber,  has  bean  taken  into  sufficient  account.  It  is  necessary  to  recall — (1)  That 
normal  rubber  is  to  a  certain  extent  porous.  (2)  That  under  the  action  of  heat  it 
expands.  (3)  That  it  may  absorb  by  capillarity  liquid  and  gaseous  bodies  in 
contact  with  it,  and  that  more  energetically  as  it  is  itself  more  expanded  by  heat. 
(4)  That  what  wre  call  rubber  is  not  a  fixed  and  determined  hydrocarbide,  but  a 
mixture  of  at  least  two"  polymeric  hydrocarbides  of  high  equivalents  derived  from 
a  fundamental  hydrocarbide  C5H8,  and  of  which  one  possesses  nervousness  in  the 
highest  degree,  and  the  other  adhesiveness.  (5)  That,  under  the  influence  of  heat, 
normal  rubber  commences  to  become  viscous  about  145°  C.  (293°  F.)  and  to  lose 
its  elasticity,  and  it  is  only  after  prolonged  cooling  that  this  elasticity,  the 
exclusive  property  of  the  nervous  hydrocarbide,  partially  regains  a  part  of  its 
power :  normal  rubber,  as  soon  as  it  has  been  once  heated  to  the  temperature  of 
145°  C.  (293°  F.),  will  be  partially  and  irrevocably  innervated.  This  fact  being 
taken  as  granted,  the  following  is  the  way  in  which  we  interpret  the  complex 
phenomena  which  constitute  vulcanisation  by  free  sulphur  (Goodyear's  method)  : — 
The  nervous  hydrocarbide  and  the  adhesive  hydrocarbide  are  intimately  mixed  with 
the  vulcanising  body,  sulphur — by  the  preliminary  operation  of  kneading — at  the 
moment  when  heat  intervenes.  Up  to  118°  to  120°  C.  (244*4°  to  248°  F.) 
no  reaction  takes  place,  but  simple  juxtaposition.  From  this  point  the  sulphur 
modifies  its  condition,  it  melts  at  the  same  time  that  the  pores  of  the  rubber  are 
sufficiently  dilated  to  allow  of  the  gradual  absorption  of  the  liquid  vulcaniser, 
sulphur.  But,  at  the  same  time  as  the  chemical  action  commences,  the  liquid 
sulphur  combines  with  the  adhesive  hydrocarbide,  and  forms  with  it  a  new 
chemical  body,  or  rather  an  alloy.  This  action  naturally  continues  if  the  process 
be  prolonged  at  the  same  temperature,  so  that  it  penetrates  further  and  further 
into  the  mass.  Total  penetration  being  attained,  let  us  stop  the  operation  (a  good 
cuiseur  knows  perfectly  when  to  seize  the  propitious  moment  for  this  purpose). 
Vulcanisation  will  have  taken  place,  or  rather  the  sulphuration  of  the  adhesive 
body  will  have  been  accomplished.  But  the  nervous  substance  will  not  have  been 
attacked.  But  if  the  temperature  be  raised  gradually  so  as  to  bring  it  to  145°  C. 
(293°  F.),  the  nervous  hydrocarbide  will  lose  its  particular  structure  so  as  to  be 
mixed  up  with  the  vulcanised  part,  and  another  reaction  will  intervene  between 
the  two  bodies,  namely,  complete  sulphuration  resulting  in  hardened  rubber  or 
ebonite.  The  phenomenon  which  ive  now  include  under  the  name  of  vulcanisation 
is  therefore  only  the  first  stage  of  a  series  of  transformations  which  the  hydrocar- 
bides constituting  indiarubber  undergo  under  the  influence  of  fixed  temperatures, 
and  in  presence  of  sulphur  in  excess,  and  the  real  terminal  reaction  of  these 
transformations  is  hardened  rubber  or  ebonite,  which  it  is  therefore  necessary,  so  as 
to  enter  into  the  views  of  Carl  Otto  Weber,  to  regard  as  an  amalgamation  of  one  or 
more  double  atoms  of  polyprene  (perhaps)  by  the  intermediary  of  one  or  more 
atoms  of  sulphur.  Vulcanisation  is  simply  the  result  of  a  quick  turn  of  the  wrist  on 
the  part  of  manufacturers  and  experimenters  to  arrest,  at  the  opportune  moment,  a 
chemical  reaction  which  has  but  commenced,  and  the  termination  of  which  would,  in 
no  way,  yield  the  product  ivhich  it  is  desired  to  obtain. 

It  will  suffice  to  quote  this  characteristic  fact  in  proof  of  the  above  contention  : 
rubber  in  which  an  excess  of  sulphur  has,  by  some  means  or  another,  been  incorpor- 
ated, and  which  remains  supple  after  the  cuiseur  has  judged  his  operation  finished, 
may  become  hard  and  brittle  some  time  afterwards.  The  reaction  has  not  been  arrested 
sufficiently  either  by  the  elimination  of  the  excess  of  sulphur,  or  by  a  rapid  enough 
dissipation  of  the  intervening  heat  retained  in  the  interior  of  the  mass. 


VULCANISATION   OF   NORMAL   RUBBER  191 

Hut  rulilM-r  regarded  as  imperfectly  \nlcani-ed,  U  it  comes  from  tin-  vulcanising 
apparatus  may  bee. .im-  sufficiently  BO,  after  -iinr   linn-.  pn.\  ided  there    I..-   -utli<-i.-nt 
sulphur,  ami  kept  in  ;i  sufficient  ly  \\arm  place.     iJi-xide*,  the  reaction  arrested  tOO 
nia\   I..-  restarted  ami  brought   to  tin-  doired  point   1>\    heating-       I 
experiments   sii|i|Mirt     tlii-  contention.       "  Ktlier   ami    carbon    disulphide.  kept   for  a 
long    time    in    contact    \\itli    \nlcani*ed    rubber,    retain    in    solution    I   to    ~>  j*-r    cent. 
nf    rubber    \\liifli     may     be    isolated     by     repeated     ,-\  aporat  ion>,    an. I      taking    up 
each   tillir   by  ether  which  rli  mi  na  t e,   five    xulphlir,   thru    by    anil  \  .  In  HIS  alcohol  \\liirli 

removes  I  to   !•:>  |><-i   cent  "t  tatty  matter  (1).     Tin-  nil.l.<-r  • -\trartn I  in  thi> 

may  !•••  M-|.ara1.-.|  into  t\\«.  JM.I-I ions—  the  one  very  dnrtilr,  «li—  .|\.-.l  l.y  l.«-n/ol, 
\\hi.-li  deposits  it  on  evaporation  ;  the  other  more  tena.-i-.n^  !••<-  .AtciiMl.le, 
umlissolveil.  These  t  \\  o  portions  eome  tVoni  the  interior  of  the  nu 
certain  «leptli,  \\here  eoinl.inat ion  is  less  intimate  and  less  altitmlant  in  snlj.hnr 
than  near  the  surface.  KiiM.er.  after  \  ulcanisat ion,  still  CODSfota  of  t\\o|,.,it 
cndoweil  \\ith  unequal  cohesion  and  solul.ility,  by  kee])in^  a  vulcani>ed  strip 
immersed  for  two  months  in  a  mixture  of  10  of  carbon  disulphide  and  1  of  absolute 
alcohol.  The  dissolved  portions  consist  of  interstitial  sulphur,  which  is  removed 
after  desiccation  by  a  solution  of  caustic  soda  ;  there  then  remains  the  less  aggregated, 
feebly  resistant,  yellow,  translucent,  organic  substance  (adhesive  hydrocarbide 
transformed  by  siilplmration).  The  undissolved  portion  remains  under  the  form  of 
a  tenacious  strip,  more  brown  and  not  so  transparent  (our  nervous  hydrocarbide  not 
yet  sutliciently  got  at  by  proximity  to  the  transformed  adhesive  part)."  The 
results  of  the  experiment,  with  the  exception  of  the  fatty  substance,  were  as 
follows : — 

TABU.  XX  XVI. — SHOWING  RESULT  OF  ACTION  OF  CARBON  BISULPHIDE  ON 
VULCANISED  RUBBER  (PAYEN). 


Insoluble  tenacious  portion       ...... 
Soluble  soft  portion           ....... 

65*0  per  cent. 
25-0 

Sulphur  in  excess      10  '0 

M 

lOO'O 

If 

Payen's  fatty  matter  is  nothing  more  or  less  than  a  little  oxidised  tacky  rubber 
\\hich  always  accompanies  caoutchouc.  The  manufacture  of  medium  hardened 
rubber,  more  .supple  than  ebonite,  less  supple  than  vulcanised  rubber  projK-r, 
supports  above  theory  sufficiently  to  allow  of  rapid  absorption  by  the  pores.  \\'«- 
consider  their  action  as  the  result  of  a  true  alloy,  giving  rise  to  the  same  effects  as 
actual  vulcanisation,  with  this  ditierence  that  true  chemical  action  does  not  occur; 
there  is  no  transformation  into  ebonite  at  M."»  ( '.  (i>930  F.). 

Viitt'-iniantinn  l>i/  niif/i/mr  chloride. — As  far  as  vulcanisation  by  sulphur 
chloride,  bromide,  and  iodide,  the-e  substances  are  naturally  liquid,  and  can  thus 
more  easily  penetrate  into  the  ]X)res  of  the  rubber,  just  softened  in  the  carbon 
disulphide  or  other  solvent  in  which  the  chloride  is  suspended.  The  liability  to 
decomposition  of  the  reagent  in  presence  of  organic  matters  with  great 
atlinity  for  haloid  bodies  generates  free  sulphur.  The  solvent  partially  replaces  heat 
and  facilitates  the  reaction,  which  besides  limits  itself  to  the  tirst  stage  of  the 
transformation.  It  does  not  become  complete  without  the  intervention  of  effective 
heat,1  and  then  may  go  as  far  as  the  terminal  reaction,  the  production  of  ebonite, 
provided  that  the  quantity  of  vulcanising  agent  be  sufficient. 

Siiiitimirii  <>/  < '.  n.  \V,  i,i,>  >•'.<  i'mn-l n*inH». — The  results  of  an  investigation  by  C.  O. 
Webber  on  vulcanisation  may  be  summed  up  as  follows:  1.  The  reaction  of 
sulphur  chloride  on  j)olyprene  is  analogous  to  that  of  sulphur  chloride  on  the  non- 
saturated  hydrocarbides  of  the  ethylenic  series;  it  has  the  etleet  of  joining  two 
molecules  of  polypreue  by  the  medium  of  one  or  several  double  atoms  of  sulphur, 
1  See  Fawsitt's  researches,  Moniteur  Seientifiqu^  de  Quesneville,  1890,  p.  1851  and  May  1893. 


192  INDIARUBBER 

giving  rise  in  the  molcule  of  polyprene  to  a  number  of  ethylenic  bonds  correspond- 
ing with  the  number  of  molecules  of  sulphur  chloride  taking  part  in  the  reaction. 
2.  There  exist  at  least  ten  chloro-sulphides  of  polyprene,  formed  by  the  combina- 
tions of  two  molecules  of  polyprene  by  means  of  one  and  even  as  many  as 
ten  double  atoms  of  sulphur.  3.  Vulcanisation  by  sulphur  chloride  depends  upon 
the  formation  of  these  chloro-sulphides  of  polyprene.  The  state  of  vulcanisation  is 
due  to  the  double  atoms  of  sulphur  (single  or  multiple)  which  unite  two  molecules 
of  polyprene.  The  chlorine,  which  is  fixed  at  the  same  time  in  the  substance,  has 
no  appreciable  influence  on  this  state  of  vulcanisation,  although  it  has  contributed 
in  creating  it,  in  the  sense  that  it  is  the  active  chemical  agent  of  the  sulphur  in 
the  sulphur  chloride.  4.  The  present  method  of  vulcanisation  by  sulphur  chloride 
is  very  irrational,  because  it  cannot  lead  to  homogeneous  vulcanisation  of  the  rubber. 
A.  sulphur  chloride  process,  by  which  homogeneous  vulcanisation  would  be  produced, 
would  be  of  incalculable  practical  value. 


CHAPTER  IX 

CHEMICAL  AND  PHYSICAL  PROPERTIES  OF 
VULCANISED  RUBBER 

HIM  it  is  impracticable  to  work  on  a  chemically  pure  substance.  Vulcanisation 
is  an  unfinished  reaction,  arrested  in  ]»vs, -nee  of  excess  of  vulcanising  agent. 
It  is  thus  difficult  to  determine  tlie  density  and  elementary  composition  of  the 
product,  its  colour,  its  smell,  or  its  taste.  In  this  examination,  the  course  pursm-d 
in  the  examination  of  the  latex  and  (as  pure  as  possible)  rubber,  is  impracticable. 
The  examination  must  be  limited  chiefly  to  a  demonstration  of  its  prnjM-rtica,  by 
•  outlasting  it  with  natural  rubber,  from  which  it  differs  essentially  in  many  of  ite 
properties,  both  physical  and  chemical.  Many  of  these  properties  are  unimportant, 
either  scientifically  or  technically. 

Elementary  composition. — It  is  quite  impossible  to  give  an  elementary  com- 
position, however  imperfect,  or  to  ascribe  any  formula  to  vulcanised  rubber. 
Those  who  have  ascribed  to  it  a  definite  chemical  composition,  have  neglected  to 
formulate  it,  and  rightly  so.  A  reaction,  interrupted  from  one  moment  to  another, 
according  to  circumstances,  cannot  be  formulated. 

Density. — Normal  rubber  has  a  density  of  O925 ;  vulcanised,  it  rarely  weighs 
less  than  water,  and  often  goes  as  high  as  1  '20  and  even  1  '30.  But  it  is  evident 
that  this  maximum  density  is  only  produced  by  an  excessive  loading  with  inert 
matter,  and  that  the  elastic  properties  of  the  substance  must  thus  be  gravely 
compromised.  A  good  vulcanised  rubber  ought  always  to  have  a  lower  density 
than  unity,  and  this  fact  may  be  made  to  serve  as  a  starting-point  to  establish  a 
method  of  testing  the  purity  of  vulcanised  rubber.  A  remarkable  observation  of 
Thomas  (Monde,  1869),  bearing  upon  this  subjec^Jias  reference  to  the  dilatability 
of  rubber,  which  is  great  enough  to  render  it  necessary  to  take  into  account  the 
temperature  at  which  the  density  is  determined.  If  a  sample  of  rubber  rather  den>ei 
than  cold  water  be  taken,  or  a  piece  ballasted  by  means  of  a  small  piece  of  metal, 
if  it  be  lighter  than  water,  and  the  whole  afterwards  heated,  the  rubber,  in 
spite  of  the  expansion  of  the  water,  will  very  soon  be  seen  to  rise  to  the  surface. 
According  to  Puschl  and  Schmilewitsch,  vulcanised  rubber  is  a  subntnn*- 
whose  density  becomes  a  minimum  at  a  certain  temperature.  Tfie  temper<ii  <n'< 
incidental  to  this  minimum  varies  with  the  mechanical  effort  exerted  on  the  rubber, 

TABLE  XXXVII. — SHOWING  DENSITY  OF  DIFFERENT  SORTS  OF 

iNDfARUBBER    (JAMES    SYMEN). 


Rubber. 

Density. 

0-922 

„        ,,      regenerated     
„         ,,      regenerated  and  pressed  .... 
,,         ,,      mixed  with  sulphur          .... 

0-882 
0-935 
0  '990)  diminution 
0-986/     0-004. 

Java  rubber  crude  as  imported    ..... 

0-920 
0-872 

194  INDIARUBBER 

and  is  greater  the  greater  the  effort.  Taking  a  rubber  unstretched  by  'mechanical 
effort,  the  temperature  of  minimum  density  is  always  higher  than  tJie  ordinary 
temperature,  and  approaches  it  by  an  addition  of  caloric  ;  its  coefficient  of  expansion 
is  positive,  but  diministies  in  proportion  with  the  increase  of  caloric.  Taking, 
on  tfo  otlier  hand,  a  rubber  strongly  stretched  by  a  pulling  /orce,  t/ie  temperature 
of  minimum  demity  is  lower  than  the  ordinary  temperature.  Its  coefficient 
of  expansion  is  therefore  negative,  and  will  diminish  numerically  with  the 
temperature. 

It  may  be  interesting  at  this  point  to  draw  attention  to  the  experiments  of 
Symen,  to  determine  the  density  of  rubber  vulcanised  by  sulphur,  compared  with 
that  of  rubber  to  which  other  substances  had  been  added. 

TABLE  XXX VIIL— SHOWING  EFFECT  OF  VARIOUS  MIXTURES  ON 
DENSITY  OF  RUBBER  (SYMEN). 


No.  1.  Pure.  —  Mixed  with  sulphur,  but  unvulcanised 

1-024)  decrease 

,,        ,,         Vulcanised    ..... 

1*013  /of  0-011. 

No.  2.  Grey.  —  Mixed  with  sulphur,  but  unvulcanised 

1-1  60  \increase 

,,        ,,         Vulcanised    . 

. 

1-180/of  0-020. 

No.  2.  Brown.  —  Mixed  unvulcanised 

1-145  \increase 

,,        ,,           Vulcanised. 

. 

1  -163  J"  of  0-018. 

No.  3.  Grey.  —  Mixed  unvulcanised 

1*489)  increase 

,,        ,,        Vulcanised    . 

, 

1-520/of  0-031. 

No.  3.  Brown.  —  Mixed  unvulcanised 

m 

1  -451  \increase 

,,        ,,           Vulcanised. 

1-460  J  of  0-009. 

The  density  of  vulcanised  Para  rubber  diminishes,  its  volume  increases :  other 
species,  especially  those  which  are  strongly  mineralised,  have  a  greater  density, 
whilst  their  volume  diminishes.  It  is  necessary  to  remember  this  when  vulcanising 
in  moulds. 

Colour. — The  colour  of  rubber  may  be  appreciably  modified  during  the 
vulcanisation.  But  that  matters  little,  and  need  occasion  no  great  concern.  If 
one  tint  of  vulcanised  rubber  be  preferred  to  another,  the  methods  of  supplying  it 
are  well  known. 

Smell — Deodorisation. — The  same  remark  does  not  apply  to  smell.  Vulcanised 
rubber  has  a  peculiar  odour  of  its  own,  scarcely  appreciable  with  an  isolated  small 
article,  but  which  reveals  itself  very  quickly  if  the  temperature  be  raised  from 
35°  to  40°  C.  (95°  to  104°  F.).  Even  at  the  ordinary  temperature  this  smell  is 
immediately  felt  on  entering  a  room  where  there  are  articles  of  this  nature.  It  is 
due  to  a  slight  disengagement  of  sulphuretted  hydrogen,  the  presence  of  which  is 
explained  in  the  chapter,  but  also  to  the  vulcanised  rubber  itself.  The  disengagement 
of  sulphuretted  hydrogen  is  greatly  prevented  by  treating  the  vulcanised  articles  by 
alkaline  solutions.  So  far  as  disinfection  of  the  vulcanised  substance  itself  is 
concerned,  many  methods  have  been  proposed,  but  none  succeed,  because  of  the 
property  which  rubber  possesses  of  absorbing  and  retaining  gaseous,  odoriferous 
bodies.  Bourne's  process  for  complete  deodorisation  of  vulcanised  rubber  is 
based  upon  the  great  affinity  which  charcoal,  more  especially  animal  charcoal, 
possesses  for  all  gaseous  bodies.  He  covers  the  articles  with  finely  pulverised 
charcoal,  and  allows  them  to  remain  so  from  three  to  six  hours  at  a  temperature 
of  40°  to  50°  C.  (104°  to  122°  F.)  ;  after  which  they  are  taken  out,  having  suffered 
no  further  change  than  that  of  having  lost  their  smell  and  of  being  incapable  of 
imparting  any  taste  whatever  to  the  liquids  with  which  they  are  brought  in 
contact.  With  certain  precautions,  even  the  most  delicate  fabrics  may  be  so 
treated  without  altering  their  substance  and  their  appearance.  But  the  odoriferous 
principles  are  only  partially  absorbed,  the  charcoal  only  acting  by  contact,  i.e. 
superficially,  and  after  some  time  the  odour  reappears.  Attempts  have  been 
made  to  mask  the  smell,  and  some  scent  employed  as  a  palliative.  Essential  oils 
are,  however,  volatile,  and  the  momentarily  badly  masked  smell  soon  returns.  It 


PROPERTIES   OF   VULCANISED   RUBBER  195 


would    !>«•  a    ditliciilt     niattrr    to    pl.-asr  tin-    taste    in    scents    of    each    individual 

customer. 

Conductibility  of  heat  <t*d  >/<  ••?,•/'<•<'/  //.     it  \\ill  readily  be  seen  why 

rubber  i>  a  still  \\OI-M-   OOUdllOtOf   of    heat    ami    electricity  than    normal    rubber,  ,in«l 
that   thi-     property     milx     increase-    in     proportion     U    tin-    1  1  .1  n-|oi  mat  ion    |MT< 
more   complete.        Siil|ihur,     like    indiaraboer,     i>    a     bad    c.Miiluctor    of    heat     and 
electricity;    the    t\\o    combined    by  juxtaposition,    by    allo\,    «.r    b\    chemical    coin 
hination,  therefore  totalise  the  >mn   of   the-e    propert  ie-  render  vulcani^-d 

rubber  one   «.f   the    bodies    \\hidi    iimM    energetically  n-^M  -    the    p.  i  -sage   of   these 
il.ii.U. 

•  lift/  —  Power  of  dialysis.  —  The  porosity  of  vulcanised  rubber  in  less  than 
tliat  of  natural  rubber.  Tlie  experiments  of  Payen,  who  discovered  this  jK-culiarity. 
have  already  been  »|iioted.  Samples  «»f  normal  rubber,  vulcanised  rubber,  and 
finally  totally  sulphuretted  rubber,  were  suspended  for  two  months  immer-ed  in 
\\ater:  the  first  had  absorbed  0*2  to  0'26  of  water,  the  second  0'042,  and  the 
third  n-m;  l,  /.,.  natural  rubber  absorbed  five  times  more  water  than  vulcanised, 
and  the  latter  a  third  less  than  that  from  which  the  free  sulphur  which  obstructed 
the  pores  had  been  eliminated.  Repeating  these  experiments  on  balloons  of  '2  milli- 
metres (.,-'.  of  an  inch)  in  thickness,  tilled  with  water  under  a  pressure  strongenough 
to  double  their  diameter,  and  keeping  them  at  a  temperature  of  +  16°  C.  (60*8°  F.), 
I'ayeii  found  a  loss  by  sweating.  This  loss,  per  twenty-four  hours  per  square 
metre  of  surface,  was  23  grammes  in  the  case  of  the  normal  rubber,  against 
1  grammes  for  the  vulcanised.  But,  on  repeating  the  same  exi>eriinent  with  air 
instead  of  water,  Payen  only  found  but  a  barely  appreciable  loss  after  eight  da\-' 
observations. 

These  results  would  lead  to  the  conclusion  that  vulcanised  rubber  is  less 
P  rnieable  to  liquids  without  solvent  action  upon  itself  than  normal  rubber,  but 
that  the  permeability  to  gas  is  the  same  in  both  cases.  Such  a  conclusion  is 
negatived  by  the  curious  observations  of  Julkowski  on  the  dialytic  power  of 
vulcanised  rubber  for  gases,  and  principally  illuminating  gases. 

./////,-o>/'.s7r/"x  i.i-/  >'/•/'///•  at*  t  HI  dial  i/tic  action  of  rubber  on  coal  gas.  —  The  experi- 
ments of  this  chemist  show  that  vulcanised  rubber  removes  from  gas  a  portion  of 
its  illuminating  power  by  the  absorption  of  the  heavy  hydrocarbides.  Relying  on 
the  data  of  Knapp,  who  in  his  Chemical  Technology  states  that  rubber  rings 
used  to  connect  gas  pipes  had  notably  increased  in  weight  and  appeared  swollen, 
he  showed  that  an  illuminating  gas  of  1T2  to  13'2  candles  was  reduced  to  7  "5 
and  10  '7  candles  by  simple  passage  through  a  rubber  tube  14  feet  long.  He 
also  states  that  vulcanised  indiarubber  in  contact  with  coal  gas  for  fifty-one  hours, 
absorbed  3  '64  of  its  weight  of  hydrocarbide,  which  it  gave  up  very  rapidly  under 
the  air  pump,  and  more  slowly  in  free  air.  Pure  ethylene  and  benzol  vajKmrs 
are  both  given  off  from  the  hydrocarbides  absorbed  by  rubber.  Julkowski  concludes 
that  the  use  of  rubber  tubing  always  gives  rise  to  a  diminution,  of  little  imjiortanre 
it  is  true,  of  the  illuminating  power  of  coal  gas  —  a  loss,  liowe\er,  which  ought  to 
be  taken  into  account  in  photometrical  tests. 

II-  in  I"  /'x  experiments  on  tlie  absolution  of  CO2  and  NO  by  i~ubber.  —  Walter 
Henipel,  \\iththe  view  of  determining  the  influence  of  indiarubber  joints  in  gas 
analysis,  submitted  carbonic  oxide  and  protoxide  of  nitrogen  to  the  same  t« 
The  rubber  behaved  exactly  like  a  liquid  solvent.  He  placed  fragments  of 
vulcanised  rubber  in  a  graduated  flask,  containing  the  above  gases,  until  the  gradua- 
tions indicated  absorption;  he  then  replaced  the  unabsorbed  gas  by  air.  He  thus 
demonstrated  that  very  small  fragments  of  indiarubber  tubing  of  3  centimetres  (say 
1J  inch)  in  length,  and  from  4  to  5  millimetres  (say  \  to  \  of  an  inch)  in  exterior 
diameter,  had  absorbed  about  2  cubic  millimetres  of  carbonic  acid  and  3  cubic 
millimetres  of  protoxide  of  nitrogen,  and  that  these  fragments  afterwards  placed  in  a 
measured  volume  of  air  completely  gave  up  to  it  this  same  volume  of  gas.  Con- 
I'/iiKimt.t.  —  If  in  very  precise  analysis  i  n<  I  iarubl)er  joints  are  debarred,  moreover,  the 
absorptive  power  of  indiarubber  is  not  so  great  that  it  need  be  considered  in  tests 


196 


INDIARUBBER 


where  rigorous  precision  is  not  absolutely  necessary ;  besides,  the  gases  generally  pass 
through  glass  tubes,  and  indiarubber  is  only  used  to  connect  these  with  one  another. 
Elasticity,  compressibility,  dilatability,  extensibility. — These  properties  are 
highly  important  to  industry  in  general,  especially  in  motor-car,  etc.,  tyre  manu- 
facture, and  in  the  construction  of  railway  rolling-stock  transmission  belts,  etc. 
Vulcanisation  has  more  especially  modified  and  developed  these  properties  to  the 
great  advantage  of  the  raw  material. 

Stewart's  experiments  en  the  elasticity,  etc.,  of  vulcanised  rubber. — A.  Stewait, 
in  charge  of  the  Railway  Management  Course  at  the  School  of  Mines  of  Liege, 
made  experiments  on  vulcanised  rubber,  especially  in  regard  to  elasticity,  and 
the  manner  in  which  it  behaves  when  it  is  pulled  and  compressed. 

All  the  experiments  were  made  on  one  and  the  same 
species  of  specially  vulcanised  Para  rubber.  Its  density  was 
comprised  between  1  '060  and  1  '065,  and  Stewart  considered 
it  as  one  of  the  best  types  of  commercial  rubber.  Stewart 
preserved  the  majority  of  the  pieces  which  were  used  in  the 
experiments,  and  some  of  these  would  appear  to  have  lost  none 
of  their  elastic  I  properties  after  eighteen  years.  But  others 
had  undergone  those  great  alterations  which  often  render  vul- 
canised rubber  absolutely  unfit  to  be  used  for  a  long  time  for 
the  purposes  to  which  it  is  usually  put.  They  have  become 
hard,  brittle,  and  almost  like  sealing-wax.  Parallel  with 
Stewart's  experiments,  Professor  Emilio  Villari,  Bologna, 
undertook  similar  experiments.  The  results,  although  ab- 
solutely independent,  agree  and  dovetail  into  each  other 
upon  several  points. 

Steivarfs  experiments  on  elongation. — These  experiments 
were  made  on  seven  samples,  having  the  form  of  bands  or 
rings  of  rectangular  section,  very  uniform,  and  of  a  rather 
large  diameter  compared  with  the  transversal  dimensions. 
The  subjoined  Table  shows  the  different  elements  forming 
the  data  of  the  question,  which  were  very  carefully  determined  before  testing. 


experiments. 


TABLE  XXXIX.  —  DIMENSIONS  AND  WEIGHT  OF  THE  RUBBER  BANDS  SUBMITTED 
TO  THE  EXPERIMENTS  (STEWART).1 


A. 

B. 

Q. 

D. 

E. 

F. 

G. 

D,  Diameter,  exterior 

118-2 

107-2 

108-8 

108-8 

106-1 

106-1 

108-7 

e,  Width 

9-2 

5-2 

5-8 

6-0 

4-8 

5-0 

5-5 

d',  Diameter,  average 

109-0 

102-0 

103-0 

102-8 

101-3 

101-1 

103-2 

c,  Circumference,  average 

342-0 

320-9 

324-0 

323-0 

318-0 

318-0 

324-0 

Weight  in  grammes 

36-95 

1875 

11-4 

11-17 

9-48 

8-59 

18-81 

Density  . 

1-060 

1-060 

1-065 

1-065 

1-061 

1-061 

1-060 

V,  Volume 

34-858 

17-689 

10-704 

10-488 

8-935 

8-111 

17-745 

S,  Section  =  — 

101-92 

55-28 

33-04 

32-57 

26-53 

25-51 

50-77 

e 

h,  Height  -A 

11-1 

14-6 

57 

5-4 

5-5 

5-1 

10-0 

h',  Height  observed 

10-9 

10-4 

5-5 

5-4 

5-3 

5-0 

10-2 

The  exterior  diameter  D  is  calculated  according  to  the  value  of  the  exterior  cir- 
cumference measured  directly ;  it  is  the  only  process  which  gave  uniform  results  in 
several  consecutive  measurements.  The  width  e,  difference  between  the  exterior  and 
the  interior  radius,  was  measured  directly  by  the  thickness  compass  (callipers) 

1  All  throughout  the  following  the  kilogramme  and  the  millimetre  are  taken  as  unity, 
unless  the  unit  be  expressly  stated. 


PROPERTIES   OF   VULCANISED   RtJHBKk 


197 


tin-  truth  lit'  a  millimetre.  The  average  diameter  d'  it*  deduced  fp-in  tin- 
two  j)irrcdiiiur  \alut^  d'  —  D  —  e.  The  average  circumference  r  is  ralriiUtrd  by 
means  of  d'.  Tin-  <len-it\  was  taken  each  time  of  tin-  uholr  sample  weighed  con- 
secutively in  air  ami  in  water.  The  \<.lume  i>  calculated  from  tin-  1»—  «\  uei^lit 
in  \\ater.  The  meridional  >eetion  S  is  obtained  much  more  accurately  than  by 
direct  measurement,  by  dividing  the  volume  l>y  the  average  riiviimi'nvinv. 
Kinally,  for  pur}>o8es  of  verification,  tliere  is  placed  >ide  l>y  Hide  the  height  //, 
cal.-idated  by  dividing  the  .section  by  the  thickness  and  the  observed  height  h '. 
During  the  whole  time  taken  up  by  the  experiments,  the  temperature  varied 
between  14°  to  16°  C.  (57'2°  to  60'8°  F.).  Table  XL.  gives  the  results  of  experi- 
ments made  on  the  six  rubber  bands  A,  B,  C,  D,  E,  F.  An  important  |M>int  will 
be  observed  at  the  first  glance  which  is  made  at  these  figures,  namely,  that  the 

TABLE  XL. — ELONGATION  OF  BANDS  OF  DIFFERENT  SECTIONS  UNDER 
VARYING  WEIGHTS. 


« 

A 

B 

C 

D 

E 

• 

F 

.=  1 

oi 

oS 

ri 

09 

o- 

00 

if 

3 

1 

I 

t 

3 
0 

1 

oo 
1 

1 

tn 

_: 

1 

;3 

i 

a 
.2 

1 

03* 

1> 

J 

1 

1 

c 

O 

p 

B 

§ 

o 

o 

a 

JD 

3 

w 

3 

w 

3 

W 

£ 

3 

0 

120 

120 

120 

120 

120 

120 

g 

0-5 

... 

125 

5 

130 

10 

130 

10 

133 

13 

134 

14 

1 

1-0 

127 

7 

134 

9 

145 

15 

146 

16 

152 

19 

158 

24 

1-5 

130 

3 

143 

9 

165 

20 

164 

18 

181 

29 

193 

35 

. 

20 

134 

4 

153 

10 

190 

25 

190 

26 

216 

35 

236 

43 

2.2 

2-5 

139 

5 

167 

14 

221 

31 

219 

29 

258 

42s 

280 

443 

3-0 

145 

6 

182 

15 

252 

313 

251 

32* 

294 

36 

318 

38 

1| 

3'5 

150 

5 

200 

18 

283 

31 

281 

30 

328 

34 

351 

33 

II 

4'0 

157 

7 

220 

20 

312 

29 

310 

29 

359 

31 

384 

33 

8*3 

4-5 

164 

7 

241 

213 

337 

25 

334 

24 

388 

29 

416 

32 

^-  <0 

5-0 

171 

7 

262 

21 

361 

24 

358 

24 

414 

26 

440 

24 

"&"*•* 

5'5 

179 

8 

281 

19 

385 

24 

380 

22 

436 

22 

4632 

23 

«  ts 

6-0 

188 

9 

300 

19 

405 

20 

402 

22 

458 

22 

492 

19 

'flj'S 

6-5 

197 

9 

317 

17 

425 

20 

422 

20 

478 

20 

510 

18 

"+*  2 

7-0 

207 

10 

333 

16 

442 

17 

439 

17 

495 

17 

528 

18 

-2 
*>  a 

7'5 

217 

10 

348 

15 

459 

17 

454 

15 

514 

19 

546 

18 

3  S) 

8-0 

227 

10 

361 

13 

474 

15 

469 

15 

5281 

14 

560 

14 

.5^ 

8'5 

... 

379 

18 

489 

15 

483 

14 

550 

14 

si 

9-0 

248 

21' 

392 

13 

502 

13 

497 

14 

562 

12 

»«5 

9-5 

406 

14 

515 

13 

510 

13 

575 

13 

... 

( 

o  s 

10-0 

269 

21 

416 

10 

525 

10 

522 

12 

588 

13 

2  o 

10-5 

... 

... 

430 

14 

535 

10 

535 

13 

600 

12 

«2'" 

11-0 

289 

20 

440 

10 

549 

14 

613 

13 

•u  *" 

11-5 

164 

14 

... 

558 

9 

620 

7 

-      O 

308 

19 

462 

8 

B65 

7 

3  CO    ~ 

12-5 

472 

10 

576 

11 

be^I   fc* 

13*0 

326 

18 

481 

g 

584 

8 

•5-0  J 

13-5 

.s»S  ° 

14-0 

344 

18 

"c  §   -^ 

14-5 

§  I*     «M 

15-0 

360 

16 

-s  "**   2 

15-5 

653 

69 

Tc  ;?  £ 

16-0 

376 

16 

>  ^   > 

17'0 

390 

14 

v  «   S 

18'0 

404 

14 

682 

29 

=  "-   2 

19-0 

418 

14 

*  o"  -S 

20-0 

430 

12 

... 

.. 

1  21  '0 

i  440 

10 

c™1  ^^  4 

22  '0 

450 

10 

§"* 

23'0 

460 

10 

*§ 

; 

198 


INDIARUBBER 


increases  in  length  by  successive  additions  of  equal  weights  go  on  increasing  up 
to  a  certain  point,  then  gradually  diminish  to  the  end  of  the  experiment.  The 
extensibility  of  vulcanised  rubber  increases,  therefore,  with  the  load  until  it  reaches 
a  maximum,  after  which  it  diminishes  in  proportion  as  the  load  increases.  The 
maximum  elongation,  per  kilogramme,  on  the  six  bands  tested  was  240,  i.e.  double 
the  initial  length,  measured  between  the  bench-marks,  from  which  Stewart  formu- 
lates the  following  laws :  Under  a  uniformly  increasing  load  the  elongations  of  a 
vulcanised  rubber  band  go  on  increasing  up  to  the  point  where  it  has  attained  tJie 
double  of  its  primitive  length,  after  ivhich  the  successive  elongations  have  a  decreas- 
ing value.  The  weight  necessary  to  quadruple  the  length  of  the  band  is  the  triple 
of  that  under  which  it  is  doubled,  whatever  may  be  the  section  of  the  band.  These 
elongations,  which  we  can  produce  on  rubber  up  to  jive  or  six  times  its  primitive 
length  without  bringing  tenacity  into  play,  are  not  pt*oduced  ivith  metals,  but  to  the 


V/          1/8  V8- 

FIG.  87.— Graphical  representation  of  elongation  experiments  on  a  rubber  band. 

extent  of  a  few  hundredth  parts  of  their  initial  length.  In  this  way  an  iron  wire 
of  1  square  millimetre  of  section  would  not  double  its  length,  except  under  20,000 
kilogrammes,  and  the  extension  is  invisible  except  under  a  load  of  30  or  40 
kilogrammes,  whilst  a  thread  of  vulcanised  indiarubber  of  the  same  section  doubles 
in  length  under  a  few  grammes,  and  is  not  broken  under  a  quadruple  load.  It 
remains  to  be  ascertained  whether  the  length  submitted  to  the  extension  has  any 
influence,  and  if  so,  to  what  extent  the  elongations  vary,  when  the  weights  which 
produce  them  act  during  a  greater  or  less  length  of  time. 

The  band  G  (see  Table,  XXXIX.)-was  used  to  make  five  experiments  upon  this 
point.  These  yielded  the  results  given  in  Table  XLL,  and  traced  graphically  in  the 
annexed  diagram  (Fig.  87).  Experiments  1  and  2  were  made  simultaneously  by 
measuring  the  distance  between  the  two  couples  of  arbitrary  bench-marks  on  the 
band,  giving  the  respective  initial  lengths  of  75  and  140 : 

lo  =  75  and  lo  —  140. 


PROPERTIES   OK   VULCANISED   RUBBER 


199 


TABLE  XLI. — ELONGATION  OF  TJIK  SA.MK  I:\.M.  1.1  KIN 

I '  \  I'ERlMENTs    (SriWA  KT). 


1  ill 

Kilo- 

gramtiirs. 
I  laud  G. 

ExficriMirnl 
No.  1. 

liinont 

•j. 

Experiment 
No. 

incut 

1. 

iment 

N... 

0 

75-0 

140 

200-0 

200-0 

200-0 

0-25 

... 

... 

0-50 

77-8 

2u-o 

211-0 

075 

80-0 

217-0 

216-0 

1-00 

82-3 

223-0 

223-0 

1  -J", 

84-5 

231  -0 

231-0 

1-50 

87-5 

239-0 

i-::. 

90-5 

... 

248-0 

247-5 

2-00 

93-8 

... 

257-0 

256-5 

97-0 

... 

268-0 

267-0 

. 

2-50 

101-5 

2800 

279-0 

275 

106-0 

292-0 

291-0 

... 

3-00 

110-5 

305-0 

304-0 

1-25 

115-0 

319-5 

318-0 

3-50 

120-5 

222-5 

335-0 

335-0 

375 

126-0 

232-0 

352-0 

352-0 

4-00 

131-5 

243-0 

370-0 

369-0 

4-25 

138-0 

254-0 

388-0                388-0 

4-50 

144-0 

265-0 

406-0 

407-0 

4-75 

150  -O1 

276-5  « 

424-0 

426-0 

i   = 

5-00 

156-0 

288-0 

443-0 

445-0 

5-25 

463-0 

463-0 

11 

5-50 

169-0 

310-0 

483-0 

481-0 

... 

575 

502-0 

4990 

7i- 

6-00 

182-0 

332-0 

520-0 

518-0 

11 

8-25 

... 

538-0 

535-0 

-   = 
=   = 

6-50 
6'75 
7-00 

193-0 
203-0 

353-0 
373-0 

554-0 
570-0 
586-0 

552-0 
569-0 
584-0 

1! 

15  '^ 

7'25 

... 

... 

598-0 

*-*  »-* 

7-50 

213-0 

393-0 

612-0 

11 

7-75 

626-0 

a  a 

8-00 

224-0 

414-0 

639-0 

.3  2 

8'25 

... 

... 

652-0 

&g 

8-50 

665-0 

... 

8-75 

677-0 

'«'« 

9-00 

241-0 

444-0 

689-0 

c  = 

9-25 

698-0 

—  — 

9-50 

709-0 

... 

sM 

9-75 

720-0 

(t 

I  I 

10-00 

258-0 

475-0 

729-0 

743'-0 

10-25 

737-0 

761-0 

10-50 

7440 

770-0 

107". 

... 

752-0 

779-0 

11-00 

272-0 

500-0 

760-0 

788-0 

1  1  -jr. 

... 

... 

770-0 

796-0 

11-50 

781-0 

806-0 

11-75 

789-0 

0  !•» 

12-00 

286-0 

525-0 

795-0 

820-0 

12-25 

801-0 

826-0 

12-50 

... 

808-0 

832-0 

12-75 

814-0 

839-0 

13-00 

300-0 

550-0 

819-0 

843-0 

i:i-j:. 

829-0 

13-50 

385-0 

13-75 

840-0 

859-0 

14-00 

847-0 

865-0 

14-25 

... 

... 

... 

855-0 

870-0 

200  INDIARUBBER 

The  successive  -lengths  under  the  same  weight  remain  in  constant  ratio 
with  those  two  numbers.  In  bringing  the  proportion  of  their  initial  lengths 
to  200,  it  is  found  in  the  same  figure  that  the  two  curves  almost  coincide.  The 
difference  which  exists  between  the  two  may  be  attributed  to  the  fact  that  the 
readings  of  the  distances  were  always  made  on  No.  2  before  No.  1.  Owing  to  an 
accident,  having  broken  the  band,  Stewart  performed  the  experiments  3,  4,  5  with 
an  unrolled  band,  the  extremities  of  which  were  held  between  the  jaws  of  two 
small  vices  lined  with  rubber,  and  it  was  thus  possible  to  work  upon  a  much 
greater  initial  length.  The  graphical  curves  were  identical  with  those  resulting 
from  the  experiment  of  Table  XL.,  only  their  co-ordinates  rise  further  in  curve  3 
than  in  curve  2,  and  in  curve  5  than  in  curve  4.  Stewart  explains  this 
phenomenon  as  follows :  It  has  been  noticed,  for  a  long  time,  that  if  a  rubber 
band  be  suddenly  extended,  a  notable  rise  of  temperature  occurs  which  may  be 
attributed  to  the  diminution  of  its  total  volume.  The  experiments  to  elucidate 
this  point  are  far  from  complete ;  certain  authors  assert  an  increase,  others  a  non- 
alteration  in  volume.  Thomson  (Lord  Kelvin)  and  Tait,  in  their  book,  Elements  of 
Natural  Philosophy,  say  distinctly :  "  An  indiarubber  band  when  pulled  out 
experiences  no  sensible  change  of  volume,  though  a  very  sensible  change  of  length." 
Villari,  of  Bologna,  on  the  contrary,  obtained  decreasing  densities,  in  proportion  as 
the  extension  of  the  rubber  increased.  The  lateral  deformation  would  therefore  be 
in  a  contrary  sense  to  that  of  all  other  bodies  submitted  to  extension.  This 
volume  resumes  its  original  dimensions  at  the  end  of  a  certain  time.  If  the 
tension  continue  to  be  exerted,  the  length  increases  in  consequence  in  such  a 
manner  that  the  elongation  obtained  suddenly  is  always  less  than  that  observed 
after  a  slow  and  gradual  action.  Stewart  also  made  certain  rupture  experiments, 
which  have  added  a  final  characteristic  to  the  peculiarities  of  indiarubber,  and 
which  demonstrated  to  him  that  this  substance  seems  to  have  no  limit  to  elasticity, 
except  rupture.  At  any  rate,  the  two  parts  of  the  broken  band,  if  they  do  not 
immediately  revert  to  the  primitive  length,  continue  to  shorten  during  a  very  long 
time  more  than  twenty-four  hours,  and  do  not  show  after  that  any  trace  of  altera- 
tion or  of  permanent  elongation.  The  breaking  load  varied,  according  to  the 
greater  or  less  rapidity  with  which  each  experiment  was  pushed,  from  500  to  800 
grammes  per  square  millimetre  of  original  section;  a  band  of  9*01  square  milli- 
metres of  section  was  not  broken  under  a  load  of  7 '5  kilogrammes.  The  results  of 
these  experiments  have,  moreover,  been  adopted  in  actual  practice,  and  the 
specifications  of  the  Belgian  State  Railways  embody  them,  so  far  as  the  supplying 
of  the  membranes  required  in  its  service  are  concerned  (1888).  The  author  sums 
up  this  first  part  of  his  work  as  follows : — 1.  An  indiarubber  band,  submitted  to 
a  longitudinal  pull,  immediately  assumes  a  certain  length,  which  notably  increases 
if  the  load  continues  to  act,  but  which  when  measured  immediately  is  proportional 
to  the  primitive  length.  2.  That  the  relation  between  the  length  and  the  load 
which  produces  it  is  very  complicated,  and  may  be  graphically  represented  by  a 
curve,  the  degree  of  which  is  probably  higher  than  the  third,  and  which  shoivs  a 
point  of  curvature  of  which  the  co-ordinates  are :  x  =  ES,  y  —  2  lo ;  lo  repre- 
senting the  initial  length  of  the  band,  S  the  section,  E  the  modules  of  rigidity  or 
the  weight  necessary  to  double  the  initial  length.  3.  That  nevertheless  the  weight 
required  to  increase  the  original  length  in  a  given  ratio  is  always  proportional 
to  the  section.  4.  That  under  a  weight  triple  that  which  doubles  the  length  the 
latter  is  quadrupled.  5.  That  the  weight  under  which  the  length  is  doubled  being 
80  grammes  per  square  millimetre  of  section,  the  value  of  the  modulus  of  rigidity 
^  is  therefore  E  =  0'084.  6.  That  if  the  definition  of  the  modulus  be  rectified  it 
ivill  vary  in  the  case  of  vulcanised  rubber :  in  the  beginning  it  has  a  value  of  0'168 
as  a  maximum  corresponding  to  the  minimum  of  extensibility ;  it  aftewards 
diminishes  to  the  third  of  this  value  at  the  moment  when  the  length  is  doubled,  then 
again  increases  to  the  point  of  rupture.  It  passes  twice  through  the  average  value 
'0'084.  7.  That  the  extensibility  per  unit  of  load  added  is  variable :  that  it  in- 
creases until  the  length  is  doubled,  and  thenceforward  decreases.  8.  That,  finally, 


I'ROI'KRTIKS    OF   VULCANISED    RUBBER 


20J 


////.<///</,  riiniiin    irt,  nailiilitii  i*    '.ntctl,/    ,;/,,;*.,,  t.  , I    I,,/    f/lf   j, ,  ,-„,,/  I,,    . 

////•». x-   ///»     •I'niii-ltinn    /<>,•     1     kil<,,iflii,in'     <>f    /'«"/    (tddcd   "f    flu     niniit'itt     tft,     /,,,;/t/t     is 

don  I, led. 

Stewart t  •  vpennnentt  »»  »/•/»/»•>•/"//.  When  a  solid  body  i>  •  nclcned  between 
t\\o  parallel  plains  \\hich  a  force  tends  to  bring  together,  the  I..M|\  i-  .-aid  to  U? 
ro////,/vs.W.  Ordinary  bodirs  >ulunitted  to  a  rather  eon-.ideral.lr  force  of  this  kind 
>uhYr  a  >light  diniiiiiitiiiii  "n  the  depth  included  between  the  two  planes  during 
compression,  accompanied  by  a  modification  of  tin-  trans\r-r>al  iliinrn-i'.ns,  of  \\liidi, 
m-nrrally,  no  account  is  takt-n  so  long  &s  the  limit  of  elasticity  i.s  not  reached. 
This  transversal  defi>nnation  is  estimated  as  being  rqual  to  the  fourth  of  that  \\hirh 
is  nlisei-M-tl  in  the  direction  of  compression.  It  Is  altogether .  different  \vit!i 
viilcanisi'd  nililn-r:  that  is  why  Stewart  calls  the  action  by  which  the  rul.U-r 
becomes  deformed  l>etween  the  two  approaching  plan-  <">n,  whilst  ib< 

dimensions,  perpendicular  to  the  force,  increase  to  a  considerable  extent,  llemark  : 
tli,  *,-ft'n/i$  normal  to  the  compressing  force  enlarge  whilst  remaining  simil'n  t» 
Thus  a  round  plate  strongly  compressed  extends  equally  in 


(3) 


.,s 


(•*) 


FIG.  88. — Etfect  of  pressure  on  indiarubber  bands. 


direction,  a  square  plate  remains  square,  a  rectangular  plate  is  deformed  according 
to  a  similar  rectangle.  The  sha}>e  most  often  employed  in  industry  is  that  of  a 
ring  of  uniform  rectangular  section,  Fig.  86;  and  this  revolving  solid  is  intended 
to  resist  forces  directed  along  its  axis.  Such  a  body  undergoes  the  following 
deformations:  The  parallel  sections  remain  circles:  Fig.  88  shows  what  happena 
to  the  meridional  sections — the  dotted  lines  show  their  original  shape.  They 
may  be  regarded  as  rectangles,  terminated  interiorly  and  exteriorly  by  semicircles, 
so  that  the  surfaces  not  in  contact  with  the  parallel  planes,  and  which  were 
primitively  two  cylinders,  become  two  senii-toruses  (2).  If  the  height  h  of  the  ring 
is  much  greater  than  its  thickness  e,  the  deformation  takes  place  differently ;  the 
exterior  toric  surface  remains  convex,  but  the  interior  becomes  concave,  as  shown  in 
(3).  This  phenomenon  commences  when  the  height  reaches  1  .'.  times  the  thickness. 

,4.  ' 

If  two  superimposed  bands  be  compressed,  they  at  first  behave  as  if  the  two 
were  only  one.  Afterwards  they  separate,  gaping  at  the  j)oint  of  exterior  contact, 
as  shown  in  (4).  But  whut>  r,  /  /,/,///  be  tfie  eft/"/1///'///"//  n mien/one,  vn/<->i,u.<>,l  rubber 
invariably  preserve*  if*  ///•////////•,  /•»///////».  The  results  of  trials  which  experi- 
mentally established  this  fact  are  given  in  Table  XLII.  1'ieces  Nos.  1  to  7  were 


202 


INDIARUBBER 


bands  having  the  form  of  Fig.  86 ;  No.  8  was  a  full  circular  sheet,  and  No.  9  a 
square  sheet,  the  whole  of  indiarubber  identical  with  the  preceding. 

TABLE  XLII. — INVARIABILITY  OF  VOLUME  OF  DEPRESSED  CAOUTCHOUC 

(STEWART).1 


D, 

Exterior 
Diameter. 

d, 
Interior 
Diameter. 

*, 

Weight. 

V, 

Volume. 

Ratio  of 
Exteution  to 
Volume. 

1.  Circular  band     .         .   {^ 

130 
193 

50 
36 

55 
22 

622,050 
621,214 

j-  0-0013 

2.  Circular  band     .         .   (^ 

97 
140 

45 
18 

26 
10 

150,080 
151,390 

j+0'0088 

3.  Circular  band     .         .   (^ 

75 

120 

30 
16 

30 
10 

111,330 
111,090 

j-  0-0023 

4.  Circular  band     .         .   {^ 

120 
161 

68 
35 

25 

10 

191,950 
193,960 

l+o-oioo 

5.  Circular  band     .         .   {^^ 

125 
165 

75 

42 

25 
10 

196,325 
197,970 

j+0-0085 

f     frpp 

6.  Circular  band     .         .    {^ 

119 
156 

85 
55 

17 
5-5 

92,599 
92,054 

j-  0-0059 

7.  Circular  band     .         .   Ufa 

84 
129 

40 
28 

29 
10 

124,265 
124,530 

j+0-0021 

8.  Circular  sheet     .         .   (^ 

110 
172 

0 
0 

22 
9 

209,066 
209,115 

j+0-0003 

9.  Square  sheet       .         .   {J^ 

110  side 
170  side 

24 
10 

290,400 
289,000 

}-  0-0048 

The  volume  of  each  circular  band  was  calculated  by  multiplying  the  meridional 
section  by  the  average  circumference.  The  differences  between  the  volumes  of  free 
rubber  and  depressed  rubber  are  very  small,  having  regard  to  this  primitive  volume, 
and  in  no  case  exceed  the  error  of  a  tenth  part  of  a  millimetre  in  direct  measure- 
ment. The  following  law,  experimentally  true  within  the  limits  of  actual  practice, 
may  therefore  be  formulated :  Throughout  all  the  different  shapes  which  a  mass  of 
vulcanised  rubber  may  be  made  to  assume,  its  volume  remains  constant.  The  flat 
surface  varies  inversely  with  the  height,  or,  when  a  circular  band  is  concerned, 
its  average  diameter  extends  in  the  same  proportion  as  the  meridional  section 
diminishes.  Stewart  thus  thinks  that  if  a  cylindrical  cavity  was  integrally  filled 
with  a  mass  of  rubber  of  the  same  shape,  the  action  of  the  piston  in  this  cylinder 
would  be  as  little  perceptible  as  if  it  had  been  filled  with  water,  which  is  equivalent 
to  saying  indiarubber  is  incompressible  to  the  same  extent  as  fluids.  These 
experiments,  made  in  1871,  were  confirmed  by  W.  Thomson  (Lord  Kelvin)  and 
P.  G.  Tait  in  1873.  "Clear  elastic  jellies  and  indiarubber  are  probably  all  of 
very  nearly  the  same  compressibility  as  water."  But  Stewart  differs  slightly  from 
Clapeyron  :  "  The  cubic  compressibility  of  indiarubber  measured  in  the  workshops 
of  the  Chemin  defer  du  Nord  was  found  equal  to  0 '00009295  of  the  primitive 
volume  per  kilogramme  of  pressure  per  sq.  cm.,  which  is  about  double  the  cubic 
compressibility  of  water"  (Comptes  Rendus,  1858,  p.  112).  Thus,  during  the 
deformation  of  a  circular  band  of  indiarubber,  the  substance  floivs,  so  to  speak,  a 
little  towards  the  interior,  much  towards  the  exterior,  producing  considerable 
surface  tension.  It  is  the  exterior  surface  which  supports  the  maximum  effort, 
and  that  at  its  equatorial  circle.  It  is  there,  consequently,  that  rupture  occurs 
when  the  pressure  suffices.  Stewart  has  seen  pieces  as  neatly  ruptured  at  the 
exterior  equator  as  if  they  had  been  cut  by  a  razor,  resume  their  original  shape 
when  the  pressure  was  removed,  which  confirms  the  idea  that  even  rupture  does 
not  lead  to  true  permanent  deformation.  A  vulcanised  indiarubber  band  under- 
going elongation  disengages  a  certain  amount  of  caloric,  and  there  is  cooling 
absorption  of  heat  when  the  matter  resumes  its  original  shape.  They  have,  more- 

1  See  note,  p.  196. 


PROPERTIES  OF   VULCANISED  RUBBER  203 

rj  observed  that  a  kind  of    \nlcani>ed    indiarnl.l>cr,  Mi-etched  1,\   a  u.-iu'ht   \\hich 
doubles   its   length,  foreshortened  one-tenth  it'   tin-   temperature  was  rawed  to  4-50° 
122     K)  (Jonk  and  Thomson). 

A'//.  This    property,    characteristic   ..!'    natural    ruli  oinpletely 

destroyed  hy  vulcanisation.      Thi-    modification    of   the    pmpcrt  ies   of   riibU.T  under 
the  influence  i.f    vulcanising   a^cnN   and   lira!    has   aliva.lv  been  -utlideiitly  in-'. 
MM.      It   \\ill   sutlice   to   state   that   vulcanisation   causes    indiarul.l.cr   to   lo«e    its 
property  of  uniting  with    itsdf.     Two   sections   of   the  same   block,    even 
recently  cut  and  brought   together   and    pressed   with  considerable  force,  are  no 
longer  capable  of  uniting. 

Action  of  heat. — Yulcani.-ed  rubber,  unlike  normal  rubber,  still  preserves  its 
pliancy  and  elasticity  much  below  0°  C.,  and  if  it  be  subjected  to  tensile  strain, 
however  pvat,  at  a  low  temperat ure,  so  long  as  it  does  not  reach  the  ]mint  of 
rupture,  it  reassiimes  its  original  shape  \\hen  it  is  left  to  itself.  It  behaves 
similarly  \\hen  heated,  and  it  loses  neither  its  elasticity  nor  its  pliancy;  at  the  li'-at 
of  boiling  \\ater  it  is  even  more  clastic,  whilst  at  the  same  time  it  does  not,  like 
natural  riihl>er,  undergo  viscous  decomposition.1  Brought  to  a  temperat  m 
1  BO"  to  200°  C.  (356°  to  392°  F.),  if  the  excess  of  sulphur  be  dissipated,  it  softens 
and  melts,  and  when  once  melted  it  remains  "tacky,"  and  completely  loses  its 
elasticity.  If  the  heat  be  maintained,  the  melted  rubber  becomes  hard  and  brittle, 
until  finally  nothing  remains  but  a  charred  mass. 

Action  of  light. — The  destructive  action  of  light  on  normal  rubber  has  already 
been  described.  Light  acts  similarly  on  vulcanised  rubber,  more  esj>ecially  if  tin- 
rubber  has  not  been  freed  from  its  excess  of  sulphur.  Thomson  found  that  even 
vulcanised  rubber  suffered  to  a  greater  extent  than  natural  rubber,  more  especially 

*-.  hen  light  acts  an  elevation  of  temperature  simultaneously  intervenes.  He 
considers  desulphuration  with  alkaline  lyes,  not  as  a  remedy,  but  as  an  aggravation 
of  the  evil ;  absorption  of  sulphur  increases  the  volume  of  the  rubber,  and  if,  after 
vulcanisation,  it  be  attempted  to  remove  the  excess  of  sulphur,  a  diminution  in 
volume  to  2J  per  cent,  results.  A  rubber  so  treated  decays  very  rapidly,  and 
Thomson  explains  it  by  the  fact  that  the  pores,  originally  filled  with  sulphur,  then 
become  filled  with  air.  Hence  arises  oxidation,  and  (1)  formation  of  hard  brittle 
resins,  and  (2)  of  a  soft  greasy  substance  slightly  volatile  at  the  ordinary  tempera- 
ture. The  action  of  light  gave  rise  in  1866  to  an  extremely  curious  observation 
by  Seely,  who  found  that  rubber  mixed  with  free  sulphur  vulcanised  equally  as 
well  under  the  action  of  light  as  that  of  heat.  Industry  has  utilised  the  fact;  and 
a  thin  leaf  of  rubber  applied  on  a  lithographic  stone,  and  exposed  to  sunlight,  can 
impart  to  that  stone  the  property  of  retaining  printing  ink  on  the  isolated  spots. 
This  is  the  point  of  departure  of  Caoutchoutocopy.  There  is  no  disengagement 
of  light  without  a  simultaneous  disengagement  of  heat,  and  this  singular 
phenomenon  is  thereby  explained.  Threads  strongly  stretched  in  vessels  filled 
with  different  gases,  and  exposed  to  sunlight,  behave  quite  according  to  the  nature 
of  the  gas.  In  dry  or  moist  oxygen,  the  threads  break  very  rapidly,  whilst  in 
carbonic  acid,  hydrogen,  and  a  vacuum  they  are  completely  unaltered  (Thomson). 

Action  of  solvents. — If  vulcanised  rubber  be  immersed  for  rather  a  long  time 
in  ordinary  solvents — essential  oils,  benzol,  carbon  disulphide — it  does  not  dis^.lvt -. 
but  swells  considerably,  and,  when  the  solvent  has  been  completely  eliminated, 
the  properties  of  the  rubber  so  treated  are  again  modified.  "Carbon  disulphide, 
benzol,  spirits  of  turpentine,  and  anhydrous  ether  swell  vulcanised  indiarubber  to 
nine  times  its  original  volume;  these  vehicles  may  also  dissolve  and  remove  the 
excess  of  uncomhined  sulphur.  Solution  in  anhydrous  ether  is  very  peculiar:  at 
thM  a  small  portion  is  taken  up  an.l  deposited  on  the  sides  then,  gradually,  fresh 
quantities  are  dissoKcd,  \\hidi  ^o  to  enlarge  the  crystals  adhering  t<»  the  sides 
of  the  vessel,  and  even  on  thr  external  sides  of  the  sheets  of  rubber  they  may 
become  bulky  enough  to  show  their  octohedral  form  to  the  naked  eye"  (I'ayen). 

1  But  the  continuous  passage  of  steam  at  ordinary  or  slight  pressure  through  laboratory 
rubber  tubing  soon  swells  and  bursts  it. — TK. 


204  INDIARUBBER 

Benzine  and  carbon  disulphide  do  not  possess  this  property.  If  vulcanised  rubber 
be  left  long  enough  in  contact  with  spirits  of  turpentine  at  a  high  temperature,  it 
is  completely  dissolved  (Heinzerling).  Ether  and  carbon  disulphide  dissolve  4  to  5 
per  cent,  of  vulcanised  rubber,  whilst  they  likewise  dissolve  the  excess  of  sulphur. 
From  the  evaporation  residue  of  this  solution,  1J  per  cent,  of  soluble  matter, 
oxidised  caoutchouc  may  be  extracted  by  absolute  alcohol.  Payen,  by  submitting 
vulcanised  rubber  to  the  solvent  action  of  10  per  cent,  of  carbon  disulphide  and 
4  per  cent,  of  absolute  alcohol,  obtained  the  following  results : x  undissolved 
rubber,  75  per  cent. ;  dissolved  rubber,  25  per  cent. 

Action  of  oils. — The  first  observations  upon  the  action  of  oils  on  vulcanised 
rubber  are  also  due  to  Thomson.  By  treating  threads  successively  with  1  to  100 
per  cent,  of  oil  and  setting  them  aside  for  six  or  seven  years,  he  found  that  the 
threads,  treated  with  a  small  quantity  of  oil,  preserved  all  their  properties  and 
their  elasticity,  whilst  a  larger  quantity  facilitated  oxidation.  Kubber  first  forms, 
with  the  oil,  a  plastic  mass,  which  finally  oxidises  very  rapidly  in  the  air. 
Cocoanut  oil  and  palm  oil  acted  most  energetically,  and  castor  oil  had  the  least 
action.  In  the  case  of  special  decay  in  a  fabric  waterproofed  by  indiarubber,  it 
was  the  excess  of  oil  which  was  the  determining  cause  of  the  mishap,  and  Thomson 
advises  that,  before  waterproofing  certain  fabrics,  a  sample  should  be  submitted 
for  one  or  two  days  to  a  temperature  of  100°  C.  (212°  F.).  More  than  1  per  cent, 
of  oil  in  a  fabric  exerts  a  deleterious  action  on  the  rubber. 

Action  of  atmospheric  agents. — If  vulcanised  rubber  were  a  wrell-defined  sub- 
stance, it  would  be  interesting  to  study  the  alterations  which  it  successively 
undergoes  in  air,  light,  heat,  and  humidity,  either  collectively  or  individually ;  this 
examination  might  perhaps  furnish  means  of  correcting  the  inherent  defects  of  the 
transformed  rubber.  Vulcanised  rubber  is  only  the  result  of  an  incomplete  and 
intermediate  transformation  between  normal  rubber  and  ebonite,  the  inherent 
defects  in  the  substance  can  only  be  pointed  out,  attributed  either  to  one  cause  or 
to  another,  and  a  few  palliatives  proposed ;  but  to  make  a  truly  useful  study,  either 
for  the  elucidation  of  the  scientific  question,  or  for  the  purpose  of  perfecting 
industrial  processes,  such  efforts  would  be  useless  and  in  vain.  The  turn  of  the 
wrist  of  the  skilful  workman,  of  the  manager  who  is  a  good  observer  of  daily  facts, 
would  be  much  more  efficacious.  Objects  made  of  vulcanised  rubber  are  liable  to 
deteriorate  in  various  ways.  After  a  certain  time,  a  molecular  change  occurs, 
which  gives  rise  to  a  sort  of  fermentation,  the  pliancy  and  nervousness  seem  to 
disappear,  and  the  rubber  is  sometimes  quite  deteriorated.  This  effect  may  be 
due  to  a  slight  humidity  in  the  pores  of  the  substance,  and  to  insufficient  heat 
during  vulcanisation.  Again  decay  manifests  itself  by  a  partial  loss  of  elasticity 
in  the  rubber,  which  cracks  over  all  the  surface  exposed  to  the  air,  the  small  cracks 
becoming  accentuated  towards  the  centre  of  articles,  the  rubber  feels  harsh,  and  ends 
by  becoming  pulverulent.  If  drawn  out  it  breaks;  it  looks  as  if  it  had  been 
burnt.  Or  the  rubber  softens,  becomes  pitchy,  tacky ;  when  drawn  out  it  elongates 
but  does  not  return  to  its  original  form.  Sometimes  it  breaks.  This  defect, 
the  result  of  insufficient  vulcanisation,  is  still  further  aggravated  by  air  and  light, 
more  especially  by  abnormal  heat.  This  defect  is  similar  to  that  in  normal  rubber, 
the  final  result  of  which  is  oxidised  or  resinified  rubber.  But  the  action  is  more 
energetic  on  rubber  already  enervated  by  repeated  working  in  various  ways  during 
the  long  preparation  of  the  substance,  than  with  a  virgin  substance  fresh  from  the 
hands  of  the  producer.  How  to  prevent  or  stop  the  decay  which  takes  place 
sometimes  on  certain  parts,  whilst  the  neighbouring  zones  are  sound  is  not  known, 
It  may  be  due  to  the  unequal  distribution  in  the  mass  of  the  vulcanised  portions 
and  the  vulcanising  substances.  Even  moonlight  sometimes  affects  the  quality  of 
vulcanised  rubber  (Chapel).  This,  he  says,  has  been  observed  numerous'  times  on 
threads  remaining  under  tension  for  several  days.  Chapel's  observation  may  be 
classified  amongst  those  real  but  inexplicable  phenomena  which  those  in  the  trade 
often  come  across,  and  are  the  cause  of  serious  trouble.  The  action  of  the  lunar 
1  ?  Parts  by  volume  or  by  weight  instead  of  per  cents. — TR. 


PROPERTIES   OF   VULCANISED   RUBBER 

rays  is  often  fatal  to  dyed  drapery,  ami    tli.-    sagacity  of    rxjH-rt-    ha-    not  UMMI  able 

to  afford  a  tatisteDtory  explanation  of  mishap-  ..f  tliis  kind.     Thc-c  mi-hap>  m.t\ 

In-  mitigated  liy  treating  the  vulcaniaed  article  with  boiling  I.  daor|M,t., 

bio    or    carl atcd.       I'.ut     thc-c    \\a*liin^s   only    art    -up«Tticiall\ ,    ami    tlio   «-\il 

soon    ivap|MMi-<.      (  Jrrard's    process  of    vulcanisation,   called    the  alkaline   process, 
also    partially  remedies   these  diseases   of   \ulcani>cd    rubber,      lint    sncli   n-iiM-.li,^ 
an-  merely  palliatives  ;    tin-  evil,  in    itself,  is    insurmountable,  because  vulcaiii-ation 
is  not   a  finished  operation.      Vulcanisation  by  metallic  sulphides  would   • 
be  the  best  means  to  use,  if  it  did  not  entail  other  drawbacks. 

Action  of  reagents  and  metals. — Vulcanised  rubber  resists  chemical  reagents, 
acids,  alkalies,  and  the  greater  number  of  salts,  better  than  normal  rubljer.  There  is 
one  exception,  the  action  which  metals  exert  upon  it,  or,  more  exactly,  the  action  of 
vulcanised  rubber  upon  metals, — iron,  copper,  and  the  alloys  mo-t  commonly  used 
for  industrial  puq>oses.  These  metals,  in  contact  with  vulcanised  rubber.  become 
corroded  and,  reciprocally,  corrode  the  rubber.  Either  because  the  sulphur,  in 
excess,  has  formed  a  metallic  sulphide,  or  that  the  affinity  of  the  sulphur  for  the 
copper  and  the  iron  is  greater  than  for  the  hydrocarbide,  the  metals  in  contact 
with  the  vulcanised  rubber  become  coated  with  a  black  layer  of  metallic  sulphide, 
and  the  substance  itself  perishes  and  loses  its  natural  properties.  The  same  effect 
is  observed  with  gold,  silver,  and  lead;  but  that  is  a  less  important  point :  these 
metals  do  not  often  come  in  contact  with  rubber.  If  it  be  desired  to  avoid  gra\. 
mistakes,  these  reciprocal  corrosions  must  be  taken  into  account.  Hence,  in 
the  manufacture  of  electric  cables,  care  must  be  taken  not  to  apply  vulcani-  d 
indiarubber  directly  on  the  copper  wires.  The  wire  would  (1)  rapidly  lose  its 
conductive  power,  and  (2)  the  dielectric  some  of  its  efficacy.  Again,  in  the  making 
of  moulds,  where  iron  is  the  raw  material  preferably  used,  it  is  necessary  both 
before  and  after  each  operation  to  clean  the  moulds  perfectly  with  emery  jtap-  r. 

Reclamation  and  desulphuration  of  vulcanised  rubber — Differentiation  beta;,  „ 
(a)  normal  rubber  iva&te,  (b)  waste  from  unheated  mixtures  of  sulphur  and  normal 
ruti/ier,  and  (c)  vulcanised  rubber  waste. — If  it  be  easy  to  utilise  normal  rubber 
waste,  and  also  that  of  mixtures  not  yet  vulcanised,  since  simple  mixing  suffices  t  < . 
restore  almost  entirely  the  whole  of  their  properties,  it  is  not  so  with  rubber  which 
has  l>een  heated  with  sulphur  or  its  derivatives.  If  it  is  often  indisixmsable  in  the 
manufacture  of  technical  articles  to  free  them  after  vulcanisation  from  an  excess  of 
sulphur,  simply  in  juxtaposition,  which  would  tend  to  exercise  an  ulterior  prejudicial 
action  on  the  quality  and  durability  of  the  article,  it  is  equally  important  to  utilise 
factory  waste,  and  articles  condemned,  either  because  they  are  defective,  or  because 
prolonged  usage  has  made  them  unfit  for  further  use.  The  almost  absolute  resi-t 
ance  of  vulcanised  rubber  to  the  action  of  solvents  does  not  allow  this  problem  to 
be  easily  solved,  and  all  the  efforts  of  successive  inventors  have  only  ended  in  a 
palliative.  Many  methods  have  been  proposed  for  utilisation  of  waste,  and  also  for 
desulphuration  of  vulcanised  rubber.  Heinzerling  classes  them  in  three  distinct 
categories — 1.  Mechanical  division  of  waste,  and  use  of  the  powder  as  an  addition  to 
virgin  paste.  2.  Fusion  of  waste,  and  use  of  the  pitch  as  an  addition  to  new 
mixtures.  3.  Partial  desulphuration  and  solution  in  appropriate  solvents,  evai>ora- 
tion  of  solvent,  and  utilisation  of  residue.  (1)  To  the  first  of  these  methods  belongs 
Goodyear's,1  the  oldest  known  process  for  reclamation  of  vulcanised  rubber.  He 
reduced  the  waste  to  a  finely  divided  state,  and  then  mixed  it  and  combined  it  with 
normal  rubber  and  the  sulphur  required  by  the  latter,  and  used  the  mass  so 
obtained  for  a  fresh  batch  of  vulcanised  rubber,  or  the  waste,  impregnated  with  a 
little  benzine,  is  digested  from  twenty-four  to  fifty -six  hours  in  a  closed,  slightly 
heated  reservoir ;  the  waste  swells  to  from  three  to  four  times  its  original  bulk,  and 
is  thus  easily  reduced  by  the  rolls  to  a  very  fine  powder.  This  process  appears 
simple  and  seems  to  solve  the  question.  This  is  not  so,  however.  The  waste  once 
vulcanised  has  undergone  this  first  attack  of  the  sulphur,  and  the  heat  which  pro- 
duced the  incomplete  transformation  stopped  at  a  desired  point  for  the  determined 
1  British  Patent,  2933  ;  1853.— Ti!. 


206  INDIARUBBER 

industrial  requirements  of  vulcanisation.  Mixed  with  the  sound  part  which  has 
not  yet  been  heated,  the  substance  will  certainly  not  behave,  during  vulcanisa- 
tion, in  the  same  way,  and  the  product  will  not  have  the  properties  ot  "<,<,<! 
vulcanised  rubber.  Moreover,  the  vulcanising  foreman  would  he  quite  ;it  sea  and 
would  not  know  when  to  arrest  the  process.  It  i,s  not  so  if  the  waste,  swollen  as 
above,  be  reduced  to  powder,  and  again  passed  through  the  slightly  heated  mixer. 
The  sheets,  of  little  consistency,  it  is  true,  may  then  }>erfectly  well,  either  after 
compression  in  moulds,  or  in  the  state  of  powder,  undergo  the  final  treatment  by 
which  ebonite  is  produced.  A  rational  use  without  any  great  expense  is  thus  found 
for  this  waste.  The  only  drawback  is,  that  it  occurs  in  rather  large  quantity,  and  the 
manufacture  of  ebonite  is  limited.  (2)  The  second  method  of  reclaiming  waste 
consists  in  fusing  the  finely  divided  waste  in  a  pot.  A  pitchy  mass  is  obtained, 
extremely  tacky,  which,  on  cooling,  becomes  converted  into  almost  solid  blocks,  if 
the  surrounding  temperature  be  sufficiently  low.  But  if  the  operation  be  conducted 
during  very  hot  weather,  the  product  assumes  a  semifluid  characteristic  condition. 
This  product,  mixed  with  other  substances — linseed  oil,  for  example — may  be  used 
in  waterproofing  certain  fabrics.  Mixed  with  normal  rubber,  it  may  again  serve  to 
coat  the  canvas  with  which  certain  hose  pipes  with  metallic  spirals  are  surrounded. 
(See  special  chapter  on  Rubber  Substitutes.)  (3)  It  now  remains  to  examine  the 
third  category  of  rubber  waste  reclamation  processes.  This  method,  moreover,  is 
intimately  connected  with  the  question  of  desulphuration.  The  solution  of  this 
waste,  in  an  appropriate  solvent,  would  be  the  most  rational  reclamation  process ;  it 
would  naturally  yield  the  most  easily  utilisable  substance.  But  the  true  solvent 
has  not  yet  been  found,  and  all  these  processes  run  very  dear. 

Newtoris  process  (British  Patent,  No.  1687  ;  1854),  based  on  steeping  from  two 
to  fourteen  days  in  camphine  (oil  of  turpentine  rectified  over  bleaching  powder), 
is  not  intelligible  from  the  patent. 

Heinzerling  and  Lipmann's  British  Patent,  1874. — The  finely  divided  waste 
rubber  is  washed,  then  boiled  in  a  10  per  cent,  solution  of  caustic  soda  for  some 
hours.  After  complete  drying,  the  substance  is  run  into  a  stove,  heated  by  steam  to 
a  temperature  of  80°  to  100°  C.  (176°  to  212°  F.),  in  presence  of  benzol,  spirits  of 
turpentine,  or  other  solvent  of  that  nature,  with  which  it  remains  in  contact  until 
complete  solution  is  effected.  To  obtain  a  reclaimed  rubber  as  free  as  possible 
from  mineral  admixture,  the  solution  is  allowred  to  stand  to  deposit,  and  the  clear 
liquid  is  decanted,  sometimes  filtered ;  complete  separation  is  thus  effected.  The 
solution  is  distilled  in  a  retort  by  direct  or  indirect  steam ;  the  addition  of  appro- 
priate substances  prevents  any  initial  vulcanisation.  If  an  absolutely  pure  product 
be  not  required,  the  mass  as  it  comes  from  the  digester  may  be  distilled.  The 
evaporation  of  the  solvent,  which  requires  to  be  conducted  at  an  extremely  low 
temperature,  must  be  as  complete  as  possible,  if  it  be  desired  to  avoid  blowholes 
and  air-bells.  In  each  batch  only  waste  of  the  same  composition  if  possible  should 
be  used.  The  waste  is  therefore  sorted  out  into  lots  before  being  used.  The  more 
the  shreds  are  cut  up  before  being  put  into  the  digester  the  more  rapidly  will  solution 
be  effected.  It  is  thus  advisable  to  combine  this  process  with  the  swelling  and 
shredding  previously  described. 

Burgkard,  Roivlay,  and  Salmonson's  process  (British  Patents,  525  and  2340 ; 
1878)  (both  provisional). — The  object  of  these  patents  is  more  to  free  weighted 
rubber  than  to  actually  reclaim  it.  They  treat  the  waste  with  hot  hydrochloric 
acid,  and  so  carbonise  all  vegetable  fibre  incorporated  writh  the  rubber,  whilst 
any  metallic  oxides  present,  such  as  zinc,  oxide,  are  also  dissolved.  The 
rubber  is  then  dissolved  in  petroleum  spirit,  carbon  disulphide,  linseed  oil,  benzol, 
or  any  other  solvent,  by  aid  of  heat,  and  the  solution  finally  evaporated.  If 
linseed  oil  be  used  as  solvent,  an  ulterior  treatment  with  ammonia  is  necessary. 
The  residual  caoutchouc  is  vulcanised  afresh.  The  acid  solutions  contain  the 
dissolved  metallic  salts,  which  can  be  precipitated  as  carbonate  and  again  used. 
The  novelty  rests  in  stripping  the  waste  and  in  the  separation  of  the  metallic  oxides. 

Nathaniel    Chapman,  and    Mitchell's  process    (British   Patent,    5048;    1881, 


PROPERTIES   OF   VULCANISED   RUBBER 


207 


In  tin-  same   lino  of  ideas  Nathaniel  Chap 
ecial    apparatus   for  tin-  t  ivatiin-iit  of  iinlia 
chloric   acid,  un,|«-r  a    pnflfOTC  "f   7)0  Hi.  JHT 
.1    i  -    a     N;I'    \\ith    iu  lid    />'.       I  loth    arc    lead  lined  sn  a 
OttVr  acids.      Al"ii^  t  lie  l»ot  t«.m  o|'    the    \at    pa-<e>  a  pijio  O, 
from  there  l.ranch  out  ot  her  en  .-s  tnl.es,  like\\i-e  perforated  ; 
e  f>,  \\hich   enierLrc>   I'I-DIII  the  lid.      //  communicates  \\ith  the 
a  in«»val>le  indianilil.er  joint  a.     I'.y  lifting  tlic  joint  the  li.l  c.,n 
ney  for  the  diaengagement  of  gases  and  \ipui-.     It  con 

forms  juirt  of  the  l»ody  of  the  lid   H  ami  is  conne<-ted  \\ith 

the  l»odv  of  the  iixed  chimney  //  l»y  a  nio\al.le  collar  //.  It  the  collar  //  l.e  pushed 
on  -/  the  case  becomes  portable.  A  lead  «l:im]K>r  i  serves  to  regulate  tin-  BBCape  "f 
steam  and  «#is.  The  acid  is  ]»oiired  on  the  bottom  of  the  vat  A  ;  after  \vliieh  the 

waste  is  packed  into  it.      The  lid  replaced,  steam  is  run  on  From  tl  into  //,  then  into 


\\liieh  B66  tor  supplementary  detail.-). 
mail  and   Mitchell  patented  in    1  ><s  I   a  s 
rul.l.er  \\astr   liv  sulhuric    or    \>\    hydr 
so  i  ia  re    inch.    |''i^.    *' 
resist   the  action   ..!' 
pierced  \\ith  h«>le>,  a 
,/  cuds  in  a   \crt 
sti'am  supply  pi[ 
beraised.     D  is  a  ch 

of  two  parts,  /  and  // 


FIG.  89. — Chapman  and  Mitchell's  apparatus  for  the  regeneration  of  imliaruhber  waste. 

a,  and  then  spreads  through  the  perforations  throughout  the  whole  of  the  acid 
liquid  in  the  bottom.  The  pressure  of  steam  ought  always  to  equal  50  to  75  Ib. 
PIT  square  inch.  The  process  lasts  from  one  to  five  hours,  according  to  the  com- 
position of  the  waste.  A  syrupy  mass  is  thus  obtained,  which,  when  drawn  from 
the  apparatus  At  is  passed  through  a  washing  machine  to  separate  the  rubber  from 
the  foreign  bodies  and  the  acid  which  accompany  it.  The  rubber  regenerated  in 
this  way  is  dried,  then  masticated,  and  wrought  up  afresh.  The  quantity  and  the 
strength  of  the  acids  necessarily  depend  on  the  quantity  of  foreign  matter  contained 
in  the  waste.  The  following  are  the  proportions  generally  used : — 

TABLE  XLIII. — SHOWING  AMOUNT  OF  MIXED  ACIDS  USED  IN  RECLAIMING 

RUBBER  WASTE. 


W.istc    . 

Sulphuric   acid   66° 
168°  Tw.,  sp.  gr.  1 
Hydrochloric  acid 

l-.,\ 
•840J    ' 

1000   Ib. 
300  to    500    ,, 
400  to    750    „ 

The  vegetable  fibres  destroyed  by  the  acids  fall  to  dust  at  the  slightest  touch, 
whilst   the   metallic    oxides    are    converted    either   into   sulphates   or   chlorides. 


208 


INDIARUBBER 


Sulphuric  acid  is  used  on  account  of  its  energy  and  cheapness,  but  hydrochloric 
acid  is  preferable  when  more  complete  purification  is  desired.  To  swell  the  rubber 
by  benzine,  in  this  apparatus  it  suffices  to  close  the  chimney  D  by  means  of  tin; 


damper  i,  until  complete  absorption,  and  then  to  open  it  afterwards.  Waste  from 
3  to  15  per  cent,  of  sulphur  is  only  treated  to  eliminate  extraneous  matter,  and  the 
reclaimed  mass  then  exists  in  the  state  of  complete  vulcanisation.  If  the  waste  is 


PROPERTIES   OF   VULCANISED   RUBBKR 

in  it  d» -sulphuretted  it  can  u  I  \\a\s  be  used  ii|i  ;  in  this  cast-,  moreover,  it  il  always  to 
I..-  preferred  t<>  -round  waste,  tin-  d.-n^ity  of  which  is  al\\:is>  much  higher.  A 
.L'reat  drawback  t»i  tin-  commercial  articles  made  from  reclaimed  rubl«-r  i>  the 
disagreeable  <mell,  from  which  it  is  impossible  to  free  it.  and  \\hich  it  communicates 
•  •\eu  to  sound  rul)l.cr.  It  has  not  l»ccn  hitherto  found  possible  to  n-j<-n«Tate 
ebonite,  \\hicli  resists  every  known  solvent,  whatever  may  be  tin-  duration  of  the 
reaction.  Sucli  waste  can  only  be  utilised  in  the  pondered  condition,  eitlier  b\ 
moulding  and  compiv-Miiu'  by  aid  of  sonic  binding  agent  or  \>y  mixing  the  melted 
po\\der  \\itli  fresh  paste.  Up  to  now  we  have  only  examined  tho>.-  dc-ulj»hurettin^ 
processes  which  are  used  in  the  reclamation  of  waste.  We  have  yet  to  SJMM; 
technical  -oods  \\heiv  tin-  [>rol)lem  is  simply  to  eliminate  by  a  simple  pr.nv.ss,  hut 
in  as  short  a  time  as  possible,  the  excess  of  sulphur  which  would  injure  the  market 
value  of  the  product.  The  excess  of  sulphur — the  uncombined  sulphur  in  juxta- 
position— can  very  well  be  eliminated  by  the  same  ]•  as  those  used  to 
remove  the  bad  smell,  i.<:  by  caustic  or  simply  carbonated  solutions  of  jxrtash  or 
soda,  at  a  temperature  of  80°  to  90°  C.  (176°  to  194°  F.).  But  this  in  not  done 
without  injuring  the  goods  to  a  certain  extent.  In  this  operation  alkaline  \*>\y- 
sulphides  are  formed,  with  disengagement  of  carbonic  acid.  If  the  contaH  of  the 
substance  with  the  alkaline  liquid  in  presence  of  heat  is  very  prolonged,  and  if 
caustic  alkaline  solutions  have  been  used  in  too  great  excess,  the  rubber 
hard  and  brittle.  Moreover,  the  desulphuretted  matter,  even  under  favourable 
conditions,  again  becomes  so  adhesive  on  its  surface  that  articles  so  treated  and 
piled  above  each  other,  after  a  certain  lapse  of  time,  become  stuck  together  under 
the  action  of  the  pressure  exerted :  in  this  case  the  substance  neither  becomes  hard 
nor  brittle.  In  the  case  of  real  waste, — where  it  is  necessary  to  extract,  if  not  all 
the  sulphur,  at  least  a  sufficient  quantity,  to  re-endow  the  substance  with  the 
property  of  being  attacked  by  the  ordinary  solvents,  of  being  again  wrought  under 
some  form  or  another,  to  restore  to  it  the  adhesive  quality  which  it  lost  by  vulcani- 
sation, to  render  it  apt  to  be  vulcanised  again  in  some  manner  or  another, — the 
results  hitherto  attained  have  not  always  been  in  direct  proportion  to  the  efforts 
exerted. 

( 'hrlttopher  and  Gidley  (British  Patent,  1461 ;  1853)  proposed  "to  macerate  the 
vulcanised  rubber  in  a  hot  solution  of  carbonated  alkali,  or  in  a  solution  of  hydrate  of 
lime,  till,  through  the  action  of  these  reagents,  the  requisite  quantity  of  sulphur  is 
abstracted,  that  is,  either  as  much  sulphur  withdrawn  as  reduces  the  relative  proportion 
of  the  sulphur  and  the  rubber  to  those  required  for  any  special  purpose,  or  so  far 
removes  the  sulphur  as  to  leave  the  residual  matter  in  a  condition  to  be  acted  on  by 
the  usual  solvents  or  softeners  of  indiarubber,  so  as  to  adapt  it  for  re-formation  into 
manufactured  articles,  and  of  being  re-vulcanised  with  sulphur  or  other  material 
when  required.  If  the  rubber  be  not  in  the  form  of  bands,  it  must  be  reduced  to 
small  pieces  so  as  to  facilitate  the  action  of  the  alkali  or  the  lime,  and  the  higher 
the  temperature  of  the  solution  or  of  the  water  the  more  rapid  is  the  operation.  We 
generally  employ  the  heat  of  boiling  water,  and,  for  economical  reasons,  we  first 
boil  with  lime,  which  desulphurises  on  the  surface,  or  to  a  small  depth  below  the 
surface,  then  we  run  off  the  solution  and  the  lime  and  then  boil  with  a  solution  of 
carbonate  of  soda.  At  the  end  of  a  short  .time  all  the  excess  of  sulphur  or  the 
uncombined  sulphur  is  extracted,  as  well  as  the  other  substances  introduced  into  the 
rubber  during  vulcanisation  or  after  manufacture.  In  this  state  the  desulphurised 
rubber  is  soluble  in  spirits  of  turpentine,  naphtha,  chloroform,  and  other  liquids 
generally  used  to  dissolve  or  soften  rubber.  .  .  . 

"...  If  it  be  found  that  the  sulphur  compounds  thus  formed,  and  which  are 
partially  dissipated  into  the  atmosphere,  are  objectionable,  a  metallic  oxide  is  added^  . 
to  the   boiling  solution  :   oxide  of  copper,  for  example,  or  a   metallic  carbonate    jl 
capable  of  forming  with  the  sulphur  dissolved  by  the  alkali  an  insoluble  sulphide   I 
without  disengagement  of  sulphuretted  hydrogen." 

Parke's  process. — Before  Christopher  and  Gidley,  Parkes  proposed  to  boil  rubber 
waste  in  a  solution  of  hypochlorite  of  lime  until,  by  slight  pressure,  the  pieces  can 
14 


210  INDIARUBBER 

be  readily  united.  He  then  washed  the  waste  prepared  in  this  way  in  hot  alkaline 
water,  and  afterwards  in  clean  hot  water.  British  Patent,  11,147;  1846,  gives 
the  solution  as  one  of  muriate  of  lime. 

These  processes  have  a  greater  or  less  relative  value  which  each  manufacturer 
can  alone  appreciate.  The  same  remarks  apply  to  the  palliative  proposed  for  the 
first  time  by  Newton  (British  Patent,  158 ;  1860),  and  which  has  since  been  remark- 
ably improved. 

Newton's  patent. — But,  little  satisfied  with  the  process  of  Parkes  and  Christopher 
and  Gidley,  Newton  (communication  from  John  Haven  Cleever)  patented  a  new 
process  for  treating  waste  vulcanised  indiarubber  (British  Patent,  158  ;  1860).  The 
waste  rubber  is  first  ground  into  a  coarse  powder  and  steeped  in  or  mixed  with  wood 
tar  or  with  crude  turpentine  (or  with  the  tarry  or  pitchy  products  derived  from  the 
distillation  of  rosin  when  producing  rosin  oil),  preferring  what  is  known  in  the 
U.S.A.  as  pine  oil,  a  semi-refined,  dark  sherry-coloured,  rather  limpid  rosin  oil. 

The  mixture  of  oil  and  ground  rubber  having  remained  from  about  four  to  five 
days,  the  superfluous  tar  or  oil  is  run  or  strained  off,  and  there  is  then  to  be  added 
to  the  now  softened  rubber,  by  kneading,  new  or  raw  vulcanisable  rubber,  in  any 
desired  proportion  to  suit  the  quality  as  respects  tenacity  of  the  compound  desired. 
Petroleum  residues  (British  Patent,  2634;  1862)  and  vegetable  oil  pitches  have 
been  used,  under  pressure,  at  a  temperature  bordering  upon  ebullition.  For 
certain  special  purposes  these  substances  may  be  of  use,  but  the  matter  dealt 
with  is  no  longer  rubber ;  it  is  a  rubber  substitute. 

Summary. — If  it  be  possible  partially  to  desulphurise  vulcanised  rubber,  this 
desulphurisation  is  never  complete,  and  the  portion  chemically  combined  with  1^ 
to  2  per  cent,  of  sulphur  always  remains  intact.  In  a  word,  we  do  not  yet  know 
the  chemical  agent  capable  of  producing  the  double  decomposition  of  the  sub- 
stance called  vulcanised  rubber.  Even  if  it  were  found,  the  desired  end  would 
not  be  attained,  because  after  it  had  done  its,  work  the  rubber  obtained  would 
certainly  have  lost  the  qualities  which  cause  it  to  be  esteemed. 

The  following  is  an  abstract  of  a  lecture  by  Mr.  W.  F.  Reid  to  the  Liverpool 
section  of  the  Society  of  Chemical  Industry.  It  shows  what  has  been  done  in  the 
way  of  reclaiming  waste  of  late  years  : — 

In  the  rubber  industry  all  the  output  eventually  becomes  "  waste,"  that  is,  it 
has  become  useless  for  the  purpose  for  which  it  had  been  used.  This  "  waste  "  finds 
its  way  back  to  the  manufacturer  for  the  recovery  of  the  rubber.  It  was  in  1846 
when  the  first  attempts  were  made  to  recover  rubber  from  "waste,"  and  in  recent 
years  a  great  advance  has  been  made  in  this  direction.  The  increased  demand  for 
rubber  in  late  years  for  the  electrical  and  motor-car  industries  has  so  taxed  the 
supply  that  some  process  for  the  recovery  of  rubber  from  the  "  waste  "  has  become 
more  necessary.  Last  year  the  rubber  output  was  68,000  tons,  there  having  been 
a  large  annual  increase  during  the  last  five  years.  America  is  first  with  42,800 
tons,  Brazil  contributing  41,000  tons.  Much  has  been  said  about  Mexico  rubber 
lately  of  an  exaggerated  nature.  Africa  produces  about  23,400  tons,  the  Congo 
Free  State  contributing  the  largest  amount.  Ceylon  rubber  has  not  come  quite  up 
to  expectations.  Much  of  it  is  of  good  quality,  but  for  some  reason  it  does  not  find 
favour  with  the  manufacturer.  In  the  manufacture  of  rubber  for  industrial  purposes 
the  crude  rubber  is  treated  with  sulphur  for  vulcanisation,  and  with  filling  materials 
as  chalk,  barium  sulphate,  litharge,  etc.  It  is  the  sulphur  which  causes  the  difficulty 
in  treating  "waste"  for  the  recovery  of  rubber.  Vulcanisation  at  present  is  a 
necessity,  but  it  is  possible  that  some  other  substance  may  be  discovered  which  will 
take  the  place  of  sulphur,  and  so  make  the  recovery  of  rubber  less  difficult.  Crude 
rubber  will  keep  almost  any  number  of  years  without  deterioration ;  it  is  on  account 
of  the  sulphur  that  rubber  is  perishable.  The  author  here  exhibited  two  pieces  of 
crude  rubber  which  had  been  kept  for  a  number  of  years  and  were  quite  as  pliable 
as  when  they  first  came  into  his  possession.  He  had  not  been  able  to  obtain  any 
vulcanised  which  had  been  kept  for  nearly  as  long.  He  had  a  rubber  stopper  which 
he  had  had  in  his  possession  twenty  years,  but  it  was  quite  hard'  on  the  surface. 


PROPERTIES   OF   VULCANISED   RUBBER  211 

Of  course  it  is  the  sulphur  \\hieh   makes  tin-  rul.l.rr  >,,  that    it   U  not  ail',  ,-u-d  by 
changes  of  temi>eraturu,  and    renders  it   iiM-fnl    in   tin-   \arious  industries,   l,i; 
believed    tliiit    inertness  \\itliuiit    sulphur   may  yet    !•«•    po^il,],-.      All   old  vulcanised 
rul>l>er  contains  traces  of  sulphuric  acid,  evidently  produced  from  the  sulphur.      At 
present    rubber    brittle  \\ith  agq  cannot  be  renovated.     The   principal    SOUP 
••  \\aste"  rubber  is  inner  tnl»es  and  diseai.  of  motor-care  and  cycles.     Thi- 

kind  of  "waste"  material  is  the  beat  available  for  the  recovery  of  rubber,  ben 
though  physically  useless  fur  the  purpos,.  required,  it  has  not  chemically  deteriorated, 
and  is  tlu-refore  \sell  suited  for  the  recover)  of  rubber.  In  regenerating  or  recover- 
ing rubber  it  is  not  necessary  to  remove  all  the  tilling  materials.  Fibre  i>  the  most 
troublesome  to  remove.  Mechanical  methods  are  the  best  for  removing  fif/re.  The 
material  is  ground  to  a  fine  powder  and  t/ie  fibre  blown  out.  In  some  instances  the 
fibre  cannot  be  removed  by  mechanical  means,  and  has  therefore  to  be  treated  by 
-•me  chemical  process  depending  upon  the  nature  of  the  fibre,  the  decomposed  matter 
being  washed  out.  There  is  some  action  on  the  rubber  by  the  acid  or  alkali  used 
which  causes  deterioration.  Vulcanised  rubber  becomes  insoluble  in  solvents  which 
,  dissolve  raw  rubber,  and  only  a  portion  of  rubber  can  be  dissolved  out  by  the 
ordinary  solvents  for  raw  rubber.  Many  samples  of  recovered  rubber  on  the  market 
have  been  sailed  by  overheating  in  the  recovery  process.  Recently  a  French 
chemist  has  discovered  a  new  solvent  for  rubber,  and  a  factory  has  U-en  erected  for 
the  recovery  of  rubber  from  "waste."  The  "waste"  is  reduced  tu  a  powder,  and 

(subjected  to  treatment  with  terpineol,  a  bye-product  of  the  artificial  camphor 
industry,  and  then  diluted  with  benziiie  when  the  mineral  matter  settles  down. 
The  supernatant  liquid  is  then  treated  with  alcohol,  which  precipitates  the  rubber. 
This  process  produces  very  good  rubber  indeed,  and  is  the  best  known  to  the  author. 
There  is  a  considerable  amount  of  rubber  recovered  by  old  processes ;  in  America 
alone  last  year  380  tons  of  rubber  was  recovered.  In  replying  to  the  discussion  which 
followed,  Mr.  Reid  said  that  he  understood  the  boiling-point  of  terpineol  was  high, 
and  that  it  is  very  volatile  in  steam.  The  process  takes  place  at  from  100°  to  150°  C. 
He  could  not  say  what  the  cost  of  the  production  of  rubber  was  by  this  process. 
He  understood  that  there  was  plenty  of  terpineol  available  for  this  process  of 
recovery.  Rubber  tubing  keeps  very  well  in  water,  light  being  the  principal  cause 
of  deterioration. 


CHAPTER  X 
HARDENED  RUBBER  OR  EBONITE 

Preliminary  observations — Resume  of  the  theory  of  vulcanisation. — Vulcanisa- 
tion properly  so  called  is  defined  as  only  the  first  stage  of  a  series  of  transformations 
which  the  hydrocarbides  constituting  natural  rubber  undergo  under  the  influence 
of  a  high  temperature  in  presence  of  an  excess  of  sulphur.  The  real  terminal 
reaction  of  these  successive  and  graduated  transformations  results  in  the  formation 
of  hardened  rubber  or  ebonite.  The  full  and  complete  confirmation  of  this  theory 
will  follow  from  the  attentive  observation  of  the  facts  about  to  be  described. 

Goodyear's  process. — The  discovery  of  hardened  rubber  or  ebonite  is  due  to 
Goodyear.1  In  1852  he  communicated  the  result  of  his  experiments.  By  using  a 
larger  proportion  of  sulpur,  and  by  further  increasing  the  temperature,  indiarubber 
acquires  the  elasticity  and  durability  of  horn  and  whalebone,  and,  by  adding  other 
mineral  substances,  such  as  magnesia,  zinc  oxide,  chalk,  etc.,  it  can  be  transformed 
into  manufactured  articles  which  could  only  be  previously  made  from  horn,  ivory, 
metal,  or  leather. 

Rapid  development  of  the  industry. — The  manufacture  of  ebonite  then  made 
rapid  progress,  and  from  the  new  material  articles  of  prime  necessity,  as  well  as 
de  luxe  articles,  and  even  tools  were  produced. 

Subsequent  reaction. — But  a  reaction  occurred  about  1870  :  buyers  rejected 
ebonite  so  much  that  it  fell  into  discredit.  The  principal  reasons  are  easily  com- 
prehended. In  consequence  of  the  grievous  events  on  which  it  would  be  useless 
and  inopportune  to  insist  here,  fashion  neglected  at  this  epoch  objects  of  pure 
fancy  or  luxury,  the  ever-increasing  applications  of  raw  rubber  raised  the  prices 
of  ebonite  articles  so  much  that,  although  of  superior  value  for  the  purpose,  they 
could  not  compete  with  articles  manufactured  with  less  solid  and  resistant  but 
cheaper  materials,  and  the  high  price  of  the  raw  material  induced  manufacturers,  at 
bay,  to  load  their  goods  with  inert  substances  in  such  a  proportion  that  the  quality 
of  the  goods,  instead  of  being  superior  to  similar  articles,  was  often  inferior  in  every 
respect.  We  have  now  returned  to  less  fatal  vagaries  in  this  branch  of  the 
industry,  and  ebonite  again  begins  to  find  favour  with  buyers.  But  it  must  not  be 
forgotten  that  a  substance — not  absolutely  indispensable  in  daily  life — cannot  hope 
to  lead  a  long  commercial  career,  except  by  its  qualities,  which  should  always  be 
beyond  all  criticism.  No  longer  must  a  technical  writer  be  able  to  say,  like  Donath, 
in  1887,  that  "in  ebonite  articles  the  'gum  resin'  only  plays  an  accessory  role  in 
regard  to  the  additional  substances  which  form  the  base ;  it  no  longer  intervenes  as 
an  elastic  substance,  but  simply  as  an  appropriate  binding  agent  which  is  preferred 
to  other  cheaper  agglutinants  on  account  of  its  resistance  to  chemical  agents  and 
solvents"  (Moniteur  Scientifique  de  Quesneville,  1887,  p.  77). 

Secret  processes  and  contradictory  infwmation. — "The  essential  processes  of 
this  manufacture  are  at  the  present  time  considered,  with  more  or  less  reason,  as 
veritable  secrets.  The  data  are  so  contradictory  that  one  can  flatly  say  that  they 
are  all  more  or  less  short  of  the  truth.  Goodyear,  for  instance,  takes  out  a  patent 
for  curing  at  the  temperature  of  120°  to  150°  C.  (248°  to  302°  F.),  whilst  other 
inventors  affirm  that  a  temperature  of  160°  to  165°C.  (320°  to  329°  F.)  is  indis- 

1  British  Patent,  Nos.  6,  16,  19,  24,  28,  30,  33,  37,  43,  163  ;  1852.— Tn. 

212 


HARDENED   RUBBER   OR   EBONITE  213 

Some  state  that  the  process  lasts  four  to  live  hours,  whilst  others  assert 
that  riirht  to  twelve  lioiirs  arc  required"  (Heinzerlin^). 

'  Imli'tH  'i/»/  J'f-t  /•///./.»/•-  /  • ...../  /»,  /''?/•»  and  .I/ /•/••/»«  rubbers  in 
iit.iint/iir/,,,;  ,,f  ,tllt,iit,.  All  \arieties  are  not  c.jiially  es^-eim-d  t,,r  tin,  ~|--,ial 
branch  o|  tin-  imlustry,  an. I  I'ara  rubber  is  not  that  pretenvd  by  tin-  trade,  not 
brraii>e  this  >nbstan<v  dues  not  the  requisite  o^ialitir*.  In  the  U-mning, 

I'ara  was  the  only  rubber  u^-d  for  ebonite,  and  very  beautiful  products  resulted 
from  its  use;  but  as,  in  tin-  social  working  of  ebonite,  elasticity  (which  is  the 
property  JKLT  excellence  of  Para)  is  destroyed  by  the  fact  of  the  vulcanisation  being 
al\\a\s  pushed  almost  to  tin  extreme  point,  it  has  not  been  found  profitable  to 
use  nervous  rublx3rs  for  this  purpose.  This  way  of  looking  at  the  matter  has  its 
justification  so  far,  in  the  fact  that  it  allows  of  the  making  of  cheaper  articles;  and 
the  majority  of  manufacturers*  at  the  present  day  prefer  East  Indian  and  Java 
rul>l>ers  to  Para.  African  rubbers  are  less  esteemed;  they  yield  too  dry,  too  brittle 
a  product. 

Imjjror.m,  nt  Jioped  for  in  African  rubber. — It  would  be  easy  to  explain  this 
bad  repute  of  African  rubbers  by  the  imperfections  inherent  to  the  present  method 
of  coagulation.  Hut  these  methods  are  in  the  way  of  l>eiiig  improved  from  day  to 
day,  and  before  long  we  hope  to  witness  a  better  appreciation  of  these  raw 
materials. 

] ''/•»  juratory  work — Ordinary  vulcanising  plant  sufficient. — The  work  properly 
so  called  is  divided,  as  in  the  case  of  other  articles,  into  a  preliminary  preparation 
of  the  rubber,  consisting  in  softening,  washing,  drying,  masticating,  mixing  tin- 
rubber  with  sulphur  and  other  conditions  more  or  less  useful,  and  the  machines  and 
tools  for  vulcanisation  are  more  than  sufficient. 

/'  .xti  of  sulphur  increased  according  to  nature  of  object. — The  only  difference 
(which  naturally  follows  from  the  end  in  view)  is  that  the  proportion  of  sulphur  is 
no  longer  the  same.  If  it  be  desired  to  obtain  goods  endowed  with  a  certain 
amount  of  pliancy  and  elasticity,  like  whalebone  substitute,  canes,  etc.,  it  should  be 
less,  say  12  to  14  per  cent.;  if,  on  the  contrary,  it  be  desired  to  obtain  a  j>aste  suitable 
for  making  rigid  objects,  drawing-rulers,  discs  of  electric  machines,  knife  handles, 
buttons,  etc.,  the  proportion  of  sulphur  should  be  greater,  24  to  35  per  cent.  The 
making  of  combs  requires  an  intermediate  quality,  and  the  quantity  of  the  sulphur 
should  be  so  adjusted.  The  elasticity  of  hard  rubber  combs  from  different  makers 
was  found  by  Ebermayer  to  vary  with  the  sulphur  content.  Those  with  a  sulphur 
content  of  11*95  per  cent,  could  be  easily  bent  but  not  fractured.  Those  with 
:_'  1  •  tG  i»er  cent,  were  not  easily  fractured,  whilst  one  with  2 8 '2 5  per  cent,  was  very 
hard  and  brittle  indeed.  In  fact,  combs  are  most  often  made  from  rubber  with 
20  to  24  per  cent,  of  sulphur  calculated  on  the  weight  of  the  rubber. 

Minimum  and  maximum  amount  of  sulphur. — Experience  proves  that  the 
quantity  of  sulphur  should  never  be  less  than  20  per  cent.,  lest  an  incomplete 
reaction  ensue  and  thus  produce  an  ebonite  destitute  of  all  desired  qualities.  As 
an  extreme  limit,  35  per  cent,  of  sulphur  must  never  be  exceeded,  lest  an  absolutely 
brittle  ebonite  result. 

Curing. — Whilst  vulcanisation  is  the  terminal  point  of  the  phases  of  supple 
rubber  manufacture,  it  is  not  so  with  ebonite,  except  in  a  few  instances.  Two 
methods  are  available — the  masticated  and  laminated  paste  is  cured  in  sheets  or 
bands  of  different  thickness,  then  wrought  as  required  by  the  turner  with  the  file, 
the  saw,  the  lathe,  etc.,  just  as  whalebone,  horn,  wood,  etc.  The  paste  conies  out 
of  the  mixer  as  a  sheet,  the  thickness  of  which  may  be  varied  at  will  by  bringing 
the  two  rolls  nearer  each  other  by  means  of  the  pressure  screw  with  which  they  are 
provided,  or,  better  still,  by  Mongin's  mixer,  the  improved  arrangements  of  which 
are  such  that  a  single  touch  regulates  this  distance  in  a  perfectly  uniform  manner, 
which  is  not  always  the  case  with  other  mixers.  For  ordinary  articles,  the  thick- 
ness is  usually  2  to  7  millimetres  (^  to  |£  of  an  inch).  As  soon  as  a  sheet  is 
rolled  it  is  cut  into  tablets  of  the  desired  dimensions :  for  example,  60  centimetres 
in  length  by  40  centimetres  in  width  (say  24  inches  by  16  inches).  These  tablets. 


214 


INDIARUBBER 


are  still  soft.  They  are  collected  on  frames  covered  with  moistened  canvas,  and 
immersed  for  a  few  instants  in  tepid  water  so  as  to  render  them  firmer  by  freeing 
them  from  the  excess  of  heat,  and  to  enable  them  at  that  stage  to  contract  to  a 
certain  extent.  If  this  contraction  were  produced  during  curing,  it  would  deform 
the  articles.  Finally,  they  are  wiped,  arranged  on  glass  or  on  tin  plates  previously 
coated  with  a  slight  layer  of  an  unctuous  greasy  body.  A  polished  iron  roller 
previously  powdered  with  talc  to  prevent  adherence  is  passed  over  them,  and  they 
are  allowed  to  freeze,  during  twenty-four  hours,  in  a  horizontal  position.  They  are 
then  ready  for  curing  by  means  of  steam  or  superheated  air.  In  curing  by  steam  the 
frames  on  which  the  tablets  are  placed  are  arranged  so  that  the  latter  are  always  in- 
clined under  an  angle  of  45°.  This  inclination  is  necessary  so  that  the  tablets  do  not 
sink  or  "  run  "  when  softened  by  the  heat,  and  that  the  water  which  condenses  during 
the  operation  cannot  remain  there.  The  steam  is  introduced  so  as  to  raise  the  interior 
temperature  up  to  135°  C.  (275°  F.)  very  regularly  and  gradually,  and  from  that 
point  forward  it  is  kept  at  that  temperature  during  a  fixed  period  of  time.  A  few 
degrees  above  this  temperature  will  burn  the  substance ;  a  few  degrees  lower,  and 
the  want  of  regularity  will  result  in  the  operation  having  to  be  done  over  again. 
The  period  when  the  temperature  should  have  reached  the  desired  degree  varies  with 
the  thickness  of  the  object.  The  same  principle  applies  to  the  duration  of  the 
curing  process,  starting  from  the  moment  when  the  proper  temperature  is  reached. 
With  thicknesses  of  9  millimetres  (say  J  inch)  and  under,  the  temperature  ought  to 
reach  135°  C.  (275°  F.)  in  two  or  three  hours,  and  the  curing  should  not  last  longer 
than  seven  hours.  With  thicknesses  of  10  to  12  millimetres  (say  §  to  J  inch),  the 
temperature  ought  to  be  raised  more  slowly  to  the  desired  degree  in  about  four 
hours,  and  curing  prolonged  from  that  time  forwards,  during  eight,  nine,  ten,  and 
even  twelve  hours.  This  margin  of  two  to  twelve  hours  may  appear  rather  elastic, 
but  no  fixed  standard  has  been  found  for  curing  hardened  rubber.  Thus,  pieces 
of  the  same  thickness,  consisting  of  the  same  ingredients,  with  the  same  proportion 
of  sulphur,  have  been  repeatedly  cured  at  the  same  temperature  and  with  identical 
supervision,  and  in  eight  hours  the  pieces  have  been  perfectly  cured ;  whilst  on 
other  occasions,  after  ten  hours,  the  pieces  had  to  be.  re-cured  for  from  twenty 
minutes  to  three  hours.  Thick  pieces  are  often  quite  cured,  while  other  and 
thinner  pieces  are  still  underdone.  When  the  curing  process  is  judged  to  be 
complete  the  steam  is  turned  off,  the  whole  allowed  to  cool  down  for  some  time, 
then  dismantling  is  effected,  but  the  frames  are  not  stripped  until  completely 
cold. 

Differentiation  between  perfectly  cured,  undercured,  and  overdone  goods. — When 
curing  has  been  done  to  a  nicety,  the  rubber  is  resistant  and  beautifully  black. 
When  it  is  not  cured  enough,  it  is  soft,  nerveless,  like  boiled  leather,  and  of  a 
greenish  colour,  which  is  deeper  the  nearer  it  approaches  the  perfect  stage  of  the 
curing  process.  When  curing  has  been  pushed  too  far,  so  that  the  ebonite  is 
burnt,  it  remains  spongy,  and  resembles  the  blocks  of  soot  agglomerated  by  pitch 
often  found  on  the  sides  of  chimneys ;  it  is  then  irretrievably  lost,  and  is  not  fit 
for  any  earthly  use  whatever. 

Defects  of  the  wet  steam  process. — The  steam  condensing  in  the  vulcaniser  causes 
drops  of  condensed  water  to  fall  back  on  the  still  soft  sheets  :  now  this  condensed 
water  brings  in  its  train  the  lamellae  of  rust  from  the  inside  of  the  cylinder,  which 
sometimes  digs  holes  in  the  sheets,  and  spots  them  right  into  the  interior  of  the 
paste.  Payen's  remedy,  consisting  of  a  kind  of  protecting  shield,  seems  only  a 
palliative,  and  it  would  be  better  to  obviate  such  an  evil  as  is  often  done  by 
substituting  superheated  air,  or  dry  steam,  for  the  action  of  wet  steam. 

Curing  in  tfo  mould — Prevention  of  air-bells. — In  certain  cases  the  mixed 
paste  is  compressed  into  moulds  in  which  it  is  immediately  cured.  But  then  air- 
bells  are  often  disengaged  between  the  paste  and  the  side  of  the  moulds,  which 
cause  damage.  Engel  proposes  to  remedy  this  evil  thus  : — The  substance  is  com- 
pressed in  the  mould,  previously  filled  with  a  liquid  capable  of  mixing  with  the 
rubber,  e.g.  linseed  oil.  The  compression  exerted  in  all  directions  naturally  pushes 


HARDENED   RUBBER   OR    EBONITE  215 

out  the  liquid,  and  the  inventor  claims  to  eliminate  in  that  iray  all  traces  <>f  air 

I.elk      Thr   oil    incorporated    \\ith    tin-    pasty   matter,  imlt-ss   6Z06Mive,  in    no    P 

injures  tin-  subsequent    operations. 

l>,i,,<i'i-   •  •/'  •  •/•«/«•/•///»/   ///    f/»    ninii/,1.      It'  ebonite   is   to   IN-    mail*-  liy  moulding  a 

paste   "I    little    consistency,    tin-re    is    danger   of    breaking   ,„•   er.u-king   during 

curing  or  subsequent    ......lin^   owin^'   to    the  diHerence    betueen    the  coefficient  of 

expansion  of  rubber  and  that  of  the  moulds  (brass,  zinc,  etc.). 

Curing  should  not  therefore  be  done  in  moulds  unless  in  thin  hollow  articles,  or 
objects  which  do  not  require  to  have  a  perfectly  glazed  surface.  If  the  object, 
\ulrani>ed  in  a  mould,  be  too  thick,  the  surface  is  covered  with  alternate 
elevations,  sometimes  remedied  by  protecting  the  paste  before  curing  with  a  piece 
of  tin,  l>ut(  there  are  still  inequalities  to  be  removed  by  the  plane,  file,  etc.,  before 
the  articles  are  marketable.  In  any  case,  moulded  ebonite  must  be  polished  after 
cutting ;  it  takes  up  time,  and  besides  involves  a  considerable  addition  to  the  cost 
price.  Moreover,  moulded  articles  are  difficult  to  polish. 

Cowper's  process  (British  Patent,  2288;  1858). — To  obviate  these  drawbacks, 
Cowper  exposed  the  objects  to  be  vulcanised,  in  their  brass  or  zinc  moulds,  from 
half  an  hour  to  three  hours  to  the  action  of  steam  or  a  current  of  hot  air.  The 
temperature  and  the  duration  of  this  process  vary  with  the  proportions  of  sulphur 
and  rubber.  If  as  high  as  1  of  sulphur  to  2  of  rubber,  Cowper  recommends  a 
first  heating  process  of  one  hour  at  a  temperature  of  148°  C.  (say  380°  F.).  If 
the  proportion  of  sulphur  is  less,  the  time  must  be  increased  proportionately. 
If  the  heat  be  greater  than  148°  C.  (say  300°  F.),  less  than  an  hour  will  be 
required.  The  mould  is  then  allowed  to  cool,  and  removed  from  the  articles, 
which  as  yet  are  only  partially  hardened.  All  defects,  such  as  blisters,  holes,  or 
asperities  or  other  surface  imperfections,  are  now  apparent ;  and  the  manipulator 
first  covers  them  with  a  slight  layer  of  rubber  solution,  and  the  holes  are  then 
filled  up  and  smoothed  with  the  original  paste  to  be  vulcanised,  and  the  mended 
articles  are  then  pressed  again  in  the  mould  and  the  heating  resumed  for  a  half  to 
three  hours  at  such  a  fixed  temperature  as  the  case  demands. 

If  the  heating  be  done  in  a  bath  of  wet  steam,  care  must  be  taken  not  to  let 
water  penetrate  into  the  moulds,  which  are  therefore  hermetically  sealed. 

This  second  heating  does  not  yet  produce  perfect  ebonite;  the  articles  are 
removed  from  the  mould  to  pass  a  fresh  inspection.  If  still  imperfect,  the  mending 
and  heating  is  repeated  as  before.  If  otherwise,  the  article  is  placed  loosely  in  a 
box  without  the  mould ;  this  box  with  the  loose  articles  is  then  hermetically  sealed, 
and  the  hardening  is  completed  by  a  final  heating,  which  may  vary  from  six  to 
eight  hours.  A  practised  hand  can  thus  make  articles  of  a  restricted  size  with 
a  single  re-heating,  whilst  those  of  larger  dimensions,  whatever  be  the  skill  of 
the  workman,  nearly  always  require  two  re-touchings  and  consequently  two  re- 
heatings.  Nevertheless,  the  articles  as  they  come  from  the  boiler  have  always  a  dull 
api>earance,  and  show  seams  which  have  to  be  pared  or  filed,  and  if  there  be 
punctures,  they  must  be  filled  up  with  shellac.  They  are  then  polished  with 
emery  or  pumice-stone  and  oil,  and  finally  they  are  polished  if  need  be  with  rounds 
of  felt. 

For  articles  requiring  a  more  perfectly  polished  surface,  Cowper  uses  two 
different  moulds.  In  the  first,  the  first  preparatory  heating  is  conducted,  and  the 
object  as  it  comes  out  of  this  first  mould  undergoes  the  necessary  mendings  and 
re-touchings.  When  the  mass  so  treated  has  acquired  about  three-quarters  of  the 
desired  hardness,  it  is  then  removed  from  the  heat  and  from  the  mould,  and  is 
deposited  in  the  second  mould,  in  the  interior  of  which  are  engraved  the  finer  and 
more  delicate  designs.  The  article  is  then  firmly  pressed  into  the  mould,  and  the 
hardening  is  completed. 

Otto  and  T-rauu's  process. — They  harden  rubber  in  glass  moulds,  the  interior 
surface  of  which  is  dressed  en  mat  (ground  fiat  and  smooth).  The  single  or 
made  up  articles  made  by  this  process  have,  it  is  claimed,  a  perfectly  homogeneous 
texture  and  do  not  require  any  re-touching.  The  sheets  of  ebonite  obtained  on 


216  INDIARUBBER 

frosted  glass  have  the  brilliancy  and  uniformity  of  cut  glass,  and  come  out  of  the 
vulcanising  apparatus  with  an  intense  black  lustre  not  otherwise  attainable  up  to  now.1 

Powdered  ebonite. — Ebonite  powdered  by  the  rasp  is  used  as  a  solder  to  join 
the  different  faces  of  boxes  and  coffers.  It  is  employed  in  that  condition  daily  to 
produce  by  moulding  and  pressure  •  a  host  of  objects  of  complicated  or  delicate 
shape,  such  as  statuettes,  knitting-needles,  umbrella  and  parasol  handles,  knife 
handles,  imitation  deerhorn,  picture-frame  ornaments.  When  agglomerated  by 
heat  and  pressure,  the  grains  of  this  powder  form  a  coherent  surface  which 
perfectly  espouses  all  the  delicate  intricacies  of  the  moulds,  and  which  can  be 
brightened  with  metallic  and  other  incrustations  absolutely  like  shell. 

Colouring  ebonite. — "The  Americans,"  says  Chapel,  "are  able,  it  would  appear, 
to  colour  ebonite  superficially  by  two  processes,  of  which  we  shall  term  the  one 
dusting  or  sprinkling,  and  the  other  veneering.  Dusting  consists  in  sprinkling  the 
sides  of  the  mould  with  finely  powdered  colour,  and  moulding  and  vulcanising  the 
article  therein.  Veneering  or  enamelling — Here  the  object  itself  is  covered  with  a 
sheet  of  coloured  rubber,  after  moulding  it  in  the  press,  so  as  to  cause  it  to  take 
the  imprints  of  the  mould  in  which  it  is  replaced  to  be  vulcanised.  We  tried  to 
enamel  hardened  indiarubber  by  Brianchon's  process — a  process  which  had  a  great 
success  in  the  ceramic  arts  thirty  years  ago.  This  inventor  was  able  to  impart  the 
multicoloured  lustres  and  reflections  of  pearl  to  porcelain  by  means  of  a  composition 
of  which  nitrate  of  bismuth,  rosin,  and  Venice  turpentine  formed  the  base.  We 
covered  the  small  cubes  of  hardened  rubber  with  this  varnish,  and  introduced  the 
sample  into  a  decorator's  2  furnace  and  left  it  there  for  ten  minutes  at  a  temperature 
of  300°  C.  (572°  F.),  and  we  obtained  a  most  beautifully  brilliant  effect.  During 
the  operation  the  heat  in  no  way  altered  the  cubes,  the  edges  of  which  preserved  all 
their  distinctness.  This  enamelling  process  might  receive  useful  applications,  and 
would  enable  coloured  articles  to  be  produced  if  metallic  oxides,  like  those  used  to 
colour  porcelain,  were  incorporated  with  the  varnish." 

Enamelling  with  a  coat  or  veneer  of  ebonite. — Ebonite,  in  virtue  of  its  elasticity 
and  durability,  has  been  applied  as  a  protective  enamel  or  veneer  to  metallic 
objects.  The  article  is  coated  by  means  of  a  brush  with  a  solution  of  indiarubber 
dissolved  in  petroleum  spirit  or  benzol,  after  which  it  is  dusted  over  with  flowers  of 
sulphur.  When  the  first  coat  is  dried  the  same  treatment  is  again  applied,  and 
when  the  second  coat  is  dried  the  articles  so  "treated  are  vulcanised  by  rapidly 
heating  them  to  160°  to  170°  C.  (320°  to  338°  F.).  The  articles  when  taken  out  of  the 
vulcanising  apparatus  are  enamelled  with  a  coat  of  ebonite.  Bad  spots  can  be 
made  good  by  giving  the  article  another  coat,  and  again  dusting  it  over  with 
flowers  of  sulphur  and  once  more  vulcanising.  To  produce  a  superfine  jet  black, 
the  object  should  be  dusted  with  either  gas  black  or  Frankfort  black,  after  being 
dusted  with  flowers  of  sulphur.  Lampblack  should  not  be  used ;  it  is  too  greasy, 
and  cannot  be  so  readily  brushed  off  as  either  of  the  above-named  blacks. 

Colouring. — More  massive  enamels  may  be  made  by  applying  to  the  object  to  be 
so  enamelled  a  rather  viscous  solution  of  indiarubber,  previously  mixed  with  the 
colouring  principle  and  sulphur  calculated  on  about  12  per  cent,  of  the  weight  of 
the  original  rubber,  so  as  to  obtain  a  mixture  having  the  consistency  of  thick  liquid  . 
paint.  If  too  viscous  to  apply  with  a  brush,  it  may  be  thinned  with  turps ;  or  if 
too  thin,  pigment  may  be  added  to  bring  it  to  the  right  consistency.  If  benzene 
or  carbon  disulphide  have  been  used  as  vehicle  or  thinners,  great  difficulty  will  be 
experienced  in  evenly  applying  the  viscous  coating.  The  best  results  are  obtained 
by  swelling  the  rubber  in  benzene  or  carbon  disulphide,  and  thinning  down  with 
turps  or  rectified  petroleum  spirit.  The  successive  coatings  should  be  thin,  the 
necessary  thickness  being  obtained  by  applying  several  repeated  coats.  Marbled 
designs  can  be  produced  on  a  white  ground  by  tinting  with  different  colours. 
When  the  desired  result  is  attained,  the  coat  is  first  of  all  dried  at  a  temperature 
not  exceeding  100°  C.  (212°  F.),  and  any  bad  places  made  good.  Finally,  the 

1  See  also  British  Patent,  4944  ;  1878.—  TB. 

2  ?  Japanner's  oven  or  stove. — TR. 


HARDENED   RUBBER  OR   EBONITE  217 

win.].-    is    vulcanised    at    a    temperature    of    !'''<)     ( '.       Ml", nit. •   enamel   so    mad. 
.•ptil.le   ..f    a     ma.umiticent     polish,    and     its   adherence    to    me  Teat 

Moreover,  it  ia  eapaMr  of  \\ith>tandinur  a  temperature  «>f  200*  C.  (392°  K.).    It  can 

l»e  used  for  enamelling  tin-  outride-  ..(  |tOT6fl  and  Mirh  like. 

•'/LI,-, /'  „>•!  rnl>l»  r  is   produced    l.y   diminishing   tin-  proportion  of  ffllpliar  Ol 
the  mixture,  \\hiUt  at   the  >ame    time  tin-  heat   is  not   pushed  BO  1'ar.       It  respond>  t«. 
a  limited  demand  \\ln-n  absolute  rigidity  in  the  article  is  not  required.      An 
are  s..  prepared  \\hich,  ha\in^  a   ratlier  compact  grain  ami  great  resistance, 
still  jM.ssess  a  relative  elasticity.     Certain  articles  ought  to  be  made  so  as  to  be 
verv  pliant  in  certain   points,  whilst  other  [.arts   should    l>e  very  hard  and  resistant. 
The   result  is  obtained    by  alternating   pliant    portions   \vith   hard  portions.      So  as 
to   prevent   the  pliant    parts  from  hardening  during  heating,  mixtures  of  only  3 
to  4  per  cent,  of  sulphur  are  used  ;  they  stand  heating  for  a  long  time  without 
alteration. 

/',-<>/„  ,-fi'es  and  multitudinous  uses  of  hardened  rubber  (ebonite). — Ebonite  in 
ral  of  its  properties  resembles  wood,  horn,  ivory.  Its  polish  is  su^rior,  and  it 
is  much  preferred  in  the  making  of  small  and  large  imitation  horn  combs,  because 
it  supports  the  cleansing  action  of  hot  water  better  than  horn.  Hot  water  does 
not  cause  ebonite  to  become  rough  to  the  touch  and  to  be  liable  to  crack  like  horn. 
Even  after  prolonged  usage,  the  teeth  of  such  toilet  articles  remain  sufficiently 
smooth,  and  good  quality  ebonite  is  sufficiently  elastic  not  to  break  under  a  rather 
perceptible  bending  strain.  It  is  a  substance  eminently  adapted  for  the  develop- 
ment of  static  electricity,  by  rubbing,  which  justifies  its  use  in  the  making  of  the 
discs  of  electric  machines.  Its  dialectric  properties  are  well  known,  and  explain 
its  use  as  an  insulator  for  electrical  cables  and  apparatus  in  which  electricity  plays 
tin-  preponderant  role. 

Action  of  acids,  etc. — It  resists  the  action  of  strong  acids,  such  as  sulphuric  and 
hydrochloric  acids  admirably,  and  thus  justifies  the  application  which  has  been 
made  of  it  in  the  construction  of  pumps,  taps,  and  hose  specially  intended  for 
handling  corrosive  liquids.  Owing  to  its  rigidity  at  the  ordinary  temperature, 
rules,  set  squares,  netting-needles,  buttons,  etc.,  may  be  made  from  it.  Its  colour, 
an  intense  black,  aided  by  the  natural  polish  with  which  it  is  endowed,  enables  it  to 
be  made  into  relatively  cheap  articles  of  ornament  and  luxury.  Solvents. — It  is 
insoluble  in  ordinary  solvents  for  raw  rubber  and  vulcanised  rubber.  Carbon 
disulphide  and  coal-tar  hydrocarbides  are  only  capable  of  making  it  swell  slightly. 
Coefficient  of  expansion. — It  posseses,  in  the  highest  degree,  the  property  of  expan- 
sion. Kohlrausch,  in  determining  its  coefficient  of  expansion,  found  that  it  was 
three  times  that  of  zinc. 

TABLE  XLIV.— SHOWING  EXPANSION  OF  EBONITE  AT  DIFFERENT  TEMPERATURES. 

For  1°  C.  ebonite  expands— 

0-0000770  between  16°'7  and  25°'3  C.  (61°'86  and  77°'54  F.). 
0-0000842        ,,       25° -3  and  35° '4  C.  (77° '54  and  95° '72  F.). 

This  coefficient  thus  increases  with  the  temperature.  Two  bands,  one  of  white 
iron,  the  other  of  ebonite,  soldered  together,  warp  appreciably  when  slightly  heated. 
It  is  the  same  with  ivory.  A  small  sheet  of  ivory  (8  in.),  united  by  isinglass  to 
a  sheet  of  ebonite,  becomes  an  excellent  thermometer  without  any  need  of  a 
thermometric  scale;  the  terminal  unglued  part  elongates  several  millimetres  for 
each  degree  C.  of  rise  of  temperature.  A  simple  plate  of  ebonite  shows,  moreover, 
the  singular  pro]>erty  of  this  substance  of  becoming  dull  and  warping  when  the  mass 
is  unequally  heated.  If  only  one  side  of  a  plate  be  heated,  it  immediately  becomes 
perceptibly  dull.  The  above  coefficients  of  expansion  show,  moreover,  that  ebonite 
possesses  a  power  of  expansion  equal  to  that  of  mercury,  if +  0°  C1.  be  taken  as  the 
point  <>f  departure  :  if  the  point  of  departure  be  higher,  this  power  is  even  greater. 

Siiiiuinii'y.  —  These  are  the  salient  features  of  ebonite,  a  product  of  tin- 
action  of  sulphur  in  sufficient  quantity,  and  under  the  influence  of  a  certain 
temperature,  on  normal  rubber.  The  physical  and  chemical  proj Arties  of  ebonite 


218  INDIARUBBER 

have  nothing  in  common  with  the  natural  and  primitive  product.  Rubber, 
as  imported,  is  excessively  liable  to  decay  under  the  influence  of  atmospheric 
agents;  vulcanised  rubber  is  less  so;  and  ebonite  not  at  all.  If  hctit  still  appears 
to  have  some  action  upon  it,  the  effects  thereof  are  diametrically  opposite  if  the 
initial  condition  and  final  result  be  considered.  Natural  rubber  yields  at  high 
temperatures  volatile  products  and  liquids  of  different  densities  and  compositions ; 
ebonite  only  gives  a  final  product,  carbon.  Finally,  if  natural  rubber  has  for 
the  greater  part  of  the  time  a  faint  odour  of  its  own,  if  pliant  or  vulcanised  india- 
rubber  be  easily  known  by  its  quite  peculiar  odour,  from  which  it  is  difficult  to  free 
it  definitely  and  completely,  hardened  rubber  is  completely  inodorous,  although  the 
proportion  of  sulphur  be  infinitely  greater.  There,  again,  is  one  of  the  most 
powerful  arguments  that  could  be  invoked  in  favour  of  our  theory  of  vulcanisation. 
The  same  remark  applies  to  the  property  of  ebonite  of  producing,  with  time, 
neither  efflorescence  of  any  sort — the  special  property  of  vulcanised  rubber ;  nor 
resinous  pitchy  matter — the  special  property  of  natural  rubber. 


CHAPTER  XI 

CONSIDERATIONS  ON  MINERALISATION  AND  OTHKIi  MIXTURES 
—COLORATION  AND  DYEING  —  ANALYSIS  OF  NATURAL  ni; 
NORMAL  RUBBER  AND  VULCANISED  RUBBER. 

Preliminary  Observations. — The  impurities  and  the  inert  substances  which 
indiarubber  may  contain,  either  accidentally  or  fraudulently,  have  been  dwelt 
upon  sufficiently  in  Chapter  III.  But  normal  rubber  that  is  sufficient ly 
purified  by  special  treatment,  so  as  to  be  capable  of  Ixjing  used  in  the 
manufacture  of  technical  articles  or  to  undergo  the  different  phases  of  the  trans- 
formations which  terminate  in  vulcanised  rubber  and  ebonite,  would  not  always, 
by  itself  alone,  be  adapted  for  the  numerous  purposes  for  which  it  is  intended. 
There  are  even  cases  where  no  single  natural  rubber  of  unique  origin  will  ans\\<  r 
the  desired  requirements,  and  recourse  must  be  had  to  mixtures  of  rubbers 
from  different  sources.  Thus,  in  the  preparation  of  very  elastic  articles  of  a 
white  colour,  Para  is  often  mixed  with  Madagascar  and  fine  Borneo.  To  reduce 
the  price,  inferior  quality  rubber  is  mixed  with  superior  quality.  The  irasta  t'rmii 
natural  rubber  is  often  used  in  that  case,  and  without  drawback. 

The  endless  series  of  substances  incorporated  ivith  rubber. — The  manufacturer, 
according  to  the  different  uses  to  which  he  intends  to  employ  it,  must  therefore  impart 
to  it  new  properties  which  it  does  not  naturally  possess.  The  incorporation  of  sulphur 
and  its  derivatives,  as  already  seen,  modify  to  a  greater  or  less  extent  the  nature  of 
the  nornfal  article.  To  impart  to  the  substance  a  greater  or  less  degree  of  con- 
sistency, to  colour  it  with  different  hues,  to  give  it  more  or  less  weight,  and  thus 
allow  cheaper  articles  to  be  made,  an  endless  series  of  substances  are  incoqwrated 
with  it.  Some  are  useless,  from  a  technical  point  of  view ;  others  only  serve  to  load 
the  manufactured  article,  most  generally  to  the  detriment  of  its  quality  and  durability. 
A  rubber  for  ink  erasers  is  not  necessarily  heavily  loaded  with  barytes,  silica,  ground 
pumice,  etc. ;  it  is  the  rubber  that  should  wear,  not  the  paper,  and  the  rubber 
should  not  act  on  it  like  a  file.  The  numerous  compositions  so  made,  says  Chapel, 
are  the  subject  of  receipts  which  each  manufacturer  preserves  with  great  secrecy. 

Difficulties  in  matching  samples. — It  is  not  enough  to  know  the  substances  wliieh 
enter  into  the  composition  of  any  given  mixture;  to  produce  a  similar  article, 
there  are  proportions  to  be  observed.  Even  with  numerous  gropings  in  the  dark. 
it  is,  if  not  impossible,  at  least  very  difficult  to  imitate  a  product,  so  long  as  the 
exact  quantities  of  the  substances  entering  into  its  composition  and  the  details 
relating  to  its  vulcanisation  have  not  been  determined.  We  now  proceed  to 
enumerate  the  chief  substances  employed  in  the  industry  for  either  one  purpose 
or  another.  To  increase  hardness  and  elasticity,  gutta  percha,  corrongit,1  balafci, 
and  rosin  are  chiefly  used,  but  the  latter  body  only  in  limited  quantity  ;  whilst 
numerous  other  substances,  such  as  chalk,  plaster  of  Paris,  calcined  magnesia, 
asphaltum,  coal-tar,  only  serve  to  increase  the  bulk,  to  the  detriment  of  the  quality. 
Magnesia,  however,  has  the  property,  more  than  any  other  addition,  of  hardening 
the  rubber.  There  can  thus  be  incorporated  with  the  rubber  as  much  as  80  i>er 
cent,  of  foreign  substances,  in  the  form  of  impalpable  powder,  without  rendering 
it  unfit  for  certain  intended  uses.  It  is  in  vulcanised  rubber  that  these  addition* 
are  now  chiefly  used,  and  the  mixing  is  always  done  during  mastication,  at  the 
same  time  as  the  sulphur  or  metallic  sulphides  are  added. 

1  A  species  of  elastic  bitumen,  particulars  of  which  are  given  under  "Rubber  Substitutes." 

219 


220 


INDIARUBBER 


TABLE  XL V.— LIST  OF  ORGANIC  AND   INORGANIC   SUBSTANCES  THAT  ARE 

OR   HAVE    BEEN    MIXED  WITH   MANUFACTURED    INDIARUBBER. 


Albumen. 

Chrome  green. 

Epsom  salts. 

Gypsum. 

Paraflin. 

Starch. 

Asbestos. 

Clay. 

Fibrin. 

Iron,  oxide  of.     Pitch. 

Steariue. 

Asphaltum. 

Coke. 

Flock.                Lamp-black.       Plaster  of 

Talc. 

Balata. 

Collodion. 

Fucus.                 Leather  waste.         Paris. 

Tar. 

Barytes. 

Copper  oxide. 

Gelatine. 

Lime,  caustic.     Rape  oil. 

Tungstic  salts. 

Bitumen. 

Cork. 

Glue.                  Lime,  slaked. 

Red  lead. 

Varnish. 

Camphor. 
Casein. 

Cotton  wool. 
Dextrine. 

Graphite.           Litharge. 
Gum-arabic,    i  Magnesite. 

Sawdust. 
Shellac. 

Zinc  oxide. 
Zinc  salts. 

Chalk. 

Earths. 

Gutta  percha.    Mune. 

Soap. 

etc.    etc. 

Charcoal. 

Emery. 

TABLE  XL VI. — INDIARUBBER  COMPOSITIONS  FOR  VARIOUS  PURPOSES. 


• 

A. 

B.             C. 

D. 

E. 

F. 

G. 

Rubber  ..... 
Garnet  shellac 
Calcined  magnesia  . 
Sulphur.         .... 
Antimony  pentasulphide 

Lb. 
100 
20 
20 
25 
25 

Lb.           Lb. 
100           280 

40-50 
20-25     i      ... 

40-50     ! 

Lb. 
280 

-    Lb. 

280 

Lb. 

280 

Lb. 
280 

84 

Coal-tar  pitch         . 

50-60     ! 

Powdered  emery 
Graphite          .... 
Lamp-black    .... 
Zinc,  white    .... 
Yellow  ochre  .... 

... 

1120 

'.'•'.          "ii 

51*2 
ft* 

488 
0i 

84 
1120 

1120 

A.,  artificial  whalebone  ;  B.,  plastite ;  C.-G.,  composition  for  grinding, 
sharpening,  and  polishing  knives. 

Many  of  these  substances  find  a  useful  application  in  special  cases,  others  are 
chiefly  used  in  the  making  of  rubber  substitutes,  intended  to  take  the  place  of 
indiarubber  in  the  manufacture  of  cheap  goods. 

Colouring  and  dyeing. — Maigne  has  made  a  special  point  of  summing  up  the 
facts  known  up  to  now.  We  quote  him  as  follows  :  "  Artificial  tints  are  often 
given  to  rubber,  so  as  to  vary  the  appearance  or  to  produce  more  or  less  artistic 
effects.  This  result  is  obtained  in  two  ways  :  either  by  mixing  the  rubber  in  paste 
or  in  solution  with  mineral  matter  in  impalpable  powder,  or  by  treating  it  after  the 
manner  of  dyeing."  The  powders  the  most  frequently  employed  are  the  following  : — 

TABLE  XLVII. — PIGMENTS  USED  IN  COLOURING  RUBBER. 


Colours  Required. 

Pigments  Used. 

Red      . 

Vermilion,  red  lead,  antimony  sulphide. 

Orange  red    . 

Mars  orange. 

Blue     . 

Ultramarine  blue,  Prussian  blue,  cobalt  blue,  indigo. 

White  . 

Zinc  oxide,  zinc  sulphide. 

Green   . 

Guignet's    green,    chrome    green,    Scheele's    green, 

emerald    green, 

verdigris,  terra  verte. 

Yellow  . 

Cadmium,  sulphide  orpiment,  yellow  ochre,  chrome 

yellow,  oxide  of 

uranium,  chromate  of  zinc. 

Black   . 

Ivory  black  (i.e.  bone-black),  lamp-black  (lead  oxides  and  salts1  give 
black  lead  sulphides  with  vulcanisation  sulphur),  seldom  used. 

1  Black  lead  sulphide  is  often  used  as  a  vulcanising  agent, 
increases  the  elasticity. 


It  gives  excellent  results  and 


CONSIDERATIONS   ON    MINERALISATION,    ETC. 


Iheing   iiM-tlnuU    ha\e    hitherto    liiinlly    l>ecii    applied    -at  Ma<-t'  .ril\  ,   e\.  «-pt    by 
means   i.f   alkan.  -t    root    or  aniline   dye-.      The  incorporation    of  coloured   linoIeatCB 
—  made  l«v    dissolving   an  aniline   d\  e  in    a  lin-erd  oil   soft   8Oap  ami    precipitating 
l'\     a    suitable   reagent  —  might    prove  ;in    excellent  method   ot   co  louring   rubber. 
Unfortunately  self-coloured    metallic    linol.-ai,-^   \\.,iil,|   not    \\ith-tand    th-    action 
of   the    vulcanisation    sulphur.       It    is    necessary,    in    fact,    to    work    upon    >ul> 
stances    which  dissolve  rubber,   and  these  sul.>tanc«  >   are   not   common.     Light 
foot  has  suggested   to  d\e  the  rubber  by  previously  covering  it  with  a  lav- 
gelatiiu-,  to  act  as  a  mordant.     In  one  of  his  patents  I'arkes  speaks  thus  of  the 
dyeing  of  indiaruhher  :  — 

"In  order  to  dye  it  black,  it  is  heated  for  a  quarter  to  hall   an  hour  in  the 
following   preparation:  —  Sulphate  of  copper,  50    Ib.  ;    water,  40  to   50  gall- 
ammonia  or   ammonium  chloride,    ~>Q  Ib  :     or  boil   the  rubber   in  —  bisulj.ha 
P«»ta.sh,  50  Ib.;  sulphate  of  copper,  25  Ib.  ;  water,  40   to    50   gallons.     In    order 
to  dye  indiarubber  green,  take  —  ammonium  chloride,  50  Ib.  ;  sulphate  of  copper, 
51    Ib.  ;    quicklime,  100    Ib.  ;    water,  40   to    50  gallons.     Boil  for  a  quarter   to 
half  an  hour. 

"  Other  English  receipts.  —  To  dye  black,  boil  a  quarter  of  an  hour  to  half  an 
hour  in  the  following  bath:  Copper  sulphate,  50  Ib.  ;  ammonium  chloride  or 
ammonia,  50  Ib.  ;  quicklime,  50  Ib.  ;  water,  50  gallons;  or  —  bisulphate  of 
potash;  50  Ib.  ;  sulphate  of  copper,  25  Ib.;  water,  50  gallons.  For  green,  boil 
the  rubber  for  a  quarter  to  half  an  hour  in  the  following  bath:  —  Sal-ammoniac, 
50  Ib.  ;  sulphate  of  copj>er,  25  Ib.  ;  quicklime,  100  Ib.  ;  water,  50  gallons. 
For  lilac,  boil  a  quarter  to  half  an  hour  in  —  sulphate  of  }K>tash,  500  11'.  : 
sulphate  of  copper,  125  Ib.  ;  sulphate  of  indigo,  125  Ib.  ;  water,  500  gallons. 

"Whatever  process  is  used,  care  must  betaken  to  guard  against  using  poisonous 
colours  for  objects  intended  to  be  frequently  handled,  such  as  children's  playthi: 
or  to  be  brought  in  contact  with  our  respiratory  organs.     Such  are   those  into 
which  copper,  lead,  mercury,  and  arsenic  enter.     In  such  cases  it  is  absolutely 
necessary  to  use  harmless  colours,  such  as  those   in    Table    XLVIII.     We   may 


TABLE  XLVIII. — HARMLESS  PIGMENTS  THAT  MAY  BE  USED  IN 
COLOURING  RUBBER. 


Colour. 

Pigment. 

Blue 
White  . 
Red      . 
Yellows 

Green  . 
Black   . 
Lilac    . 
Brown  . 

Indigo,  ultramarine. 
Non  -arsenical  zinc  oxide. 
Cochineal  and  lakes,  archil. 
Persian  berries,  quercitron,  turmeric,  fustic  and  lakes, 
yellow  wax,  chromate  of  zinc  or  magnesia.1 
Guignet's  green  ;  mixtures  of  above  yellows  and  blues. 
Carbon  in  all  its  forms. 
Mixtures  of  ammoniacal  cochineal  and  ultramarine. 
Terra  di  Sienna  and  lamp-black. 

also  mention  the  eosin  lakes.  As  is  known,  these  beautiful  colouring  matters 
are  the  result  of  the  combination  of  eosin  with  oxide  of  zinc.2  Added  to 
chromate  of  zinc,  in  different  proportions,  they  yield  bright  colours,  which  may 
replace  red  lead  and  chrome  yellow.  Finally,  with  ultramarine  they  form  more  or 
less  intense  violets.  All  these  colours  perfectly  resist  light  and  heat  They  may 
be  incorporated  in  the  rubber  paste,  then  submitted  to  the  temperature  necessary 

1  Poisonous  salts  of  lead,  tin,  antimony,  and  barium  are  often  used  in  precipitating  lakes  of 
all  colours  ;  such  lakes  are  of  course  poisonous,  and  chromates  as  a  class  are  far  from  innocuous. 

2  In  Great  Britain,  at  any  rate  for  paint  purposes,  the  eosin  is  most  generally  in  the  form 

of  cos  in  ate  of  lead. 


222 


INDIARUBBER 


for  vulcanisation,  without  undergoing  the  least  alteration."  As  to  the  coloration 
of  ebonite,  sufficient  details  have  been  given  at  the  end  of  the  chapter  devoted  to 
that  substance,  so  that  there  is  no  necessity  to  revert  to  the  subject. 

The  toxic  cation  of  zinc  oxide  on  rubber  teats,  etc. — To  terminate  this  paragraph, 
and  not  to  be  under  the  necessity  of  returning  to  the  question  of  the  toxic  sub- 
stances often  entering  into  technical  mixtures,  let  us  recall  that  Tollens  has  collected 
a  certain  number  of  facts  which  prove  the  unwholesome  influence  of  tubes,  teats, 
ends  of  sucking-bottles,  joints,  etc.,  loaded  with  a  notable  quantity  of  oxide  of  zinc. 
He  also  thinks  that  the  rubber  employed  in  dental  surgery  is  not  always  exempt 
from  defective  composition  in  this  respect.  In  support  of  his  statement  he  quotes 
the  composition  of  a  white  rubber  employed  by  certain  dentists : — 

TABLE  XLIX. — COMPOSITION  OF  RUBBER  USED  BY  CERTAIN  DENTISTS 

(TOLLENS). 


Substance. 

Per  cent. 

Oxide  of  zinc     . 
Chalk        . 
Oxide  of  iron     . 
Sulphur    . 
Rubber      . 

43-96 
0-62 
traces 
26-60 

28-82 

100-00 

Vermilion  also  enters  sometimes  into  such  mixtures,  but  this  substance  is 
possibly  the  most  innocuous  of  all  mercurial  compounds. 

Methods  of  analyses  of  indiarubber.  — No  one  had  taken  the  trouble  to  give  a 
scheme  for  the  analysis  of  either  raw  rubber  or  of  vulcanised  rubber,  until 
Heinzerling  in  1883  attempted  the  undertaking.  His  work,  unfortunately,  is  not 
complete ;  and  if  he  omits  certain  details,  such  as  the  determination  of  oxidised 
rubber  in  commercial  raw  rubber  (an  important  point),  he  nevertheless 
insists  on  certain  analytical  processes  in  the  analysis  of  transformed  rubbers 
which  prove  absolutely  nothing  if  they  remain  isolated  and  not  co-ordinated 
with  others.  Thus  the  determination  of  the  density  of  vulcanised  or  mineralised 
rubber,  without  a  qualitative  analysis  at  least,  has  no  signification;  a  technical 
rubber  may  be  mixed,  not  only  with  cork  dust,  but  also  with  barytes. 
The  density  of  the  first,  therefore,  may  be  as  near  as  possible  to  the  natural  rubber, 
whilst  containing  a  much  smaller  quantity  of  real  rubber  than  a  second  sample  of 
greater  density  but  with  a  much  higher  proportion  of  real  rubber.  Heinzerling 
states  that  it  answers  very  well  for  determining  approximately  the  quantity  of 
mineral  matters  which  enter  into  a  mixture,  but  owns  that  it  is  not  conclusive,  as 
it  gives  no  information  as  to  a  mixture  in  which  the  rubber  has  lost  a  portion  of 
its  properties  by  an  addition  of  substances  equal  to  or  lower  in  density  than  I/O, 
or  even  when,  by  these  same  additions,  the  mixture  has  acquired  a  greater  bulk 
than  that  of  genuine  vulcanised  rubber.  The  following  additions  require  special 
mention  :  boiled  linseed  oil,  and  other  fatty  derivatives,  paraffin,  etc.,  the  use  of 
which  in  this  industry  tends  daily  to  become  greater.  It  is  difficult  to  discover  the 
presence  of  one  of  these  bodies  by  qualitative  analysis.  As  to  the  exact  determination 
of  the  quantities  used,  Heinzerling  finds  the  difficulty  insurmountable.  E.  Donath, 
in  1887,  was  engaged  in  the  same  kind  of  work,  but  more  especially  in  regard  to 
vulcanised  rubber.  Availing  ourselves  of  the  researches  of  the  scientists  who  have 
investigated  the  matter,  and  completing  them  when  there  is  a  possibility  of  doing 
so,  we  shall  attempt  to  establish  as  complete  a  method  of  general  application  as 
the  actual  state  of  science  will  allow.  Not  that  we  are  the  victims  of  any  great 
illusion,  but  few  of  these  scientific  determinations  are  made,  either  in  the  trade 


CONSIDERATIONS   ON    MINERALISATION,    ETC. 

iic  in  the  industry  generally.  It  it  !>«•  ;i  tpieslion  of  raw  material*,  the 
buyer  generally  tru-N  t«»  his  o\\n  experience  ;  |M-  jud-e-  tin-  rul.U-r  <l> 
/•/x//,  and  should  In-  I.e  \\rong  a  hundred  tinn-N  In-  uill  not  o\sntoit  until  it  is  too 
late.  Should  he,  on  (lie  other  hand,  In-  five  from  th-  :..-ei\ed  ideas  he 

U  oi  i  M  not    al\\,i\  >   li.i\e   tin-   tillir  to   h;i\r  reroiir-e  tu  t  he  lilt  er\  i-iit  ion  of  tin-  ch.-niM. 

and,  before  the  analysis  of  a  given  l"t  \\a>  imMied,  it  vroTild  be  in  the  hands  of  hit 

rivals.      A^  far  as  tini-hed  products  are  coiuvrnrd,  tin    l.im-r  tnM-  to  th.-  reputation 
of  such  and  such  a  tinn  in  the  piircha-inur  "f  any  ^i\«-n    arti<-lr.      Anal\>i>  ifl  ,i  ! 
and  costly  pr0060&       \N'hy,  then,  should  he  report   to  it   \\ln-n  In-  knows  tin-  >kill  and 
the    probity    of    the   maker  1     To  the  manufacturers  who  wi*h  to   trail-form    tin- 
raw    matt-rial    into    manufactured    article-    under   >uch  conditions    that     they    may 
advantageously  sustain  that  pacific  but  continual  struggle  without  truce  and  uithout 
mercy,  which  is  called  competition,  \\hether  local  or  foreign,  a  method  of  anal 
as  simple  and  rapid  as  possible — is  of  the  utmost  importance. 

Analysis  of  commercial  crude  rubber. — In  the  synthetical  Table  of  the  principal 
varieties  of  commercial  rubber,  to  be  found  at  the  end  of  Chapter  IV..  a 
columns  are  devoted  to  the  principal  physical  properties  characteristic  of  each 
variety.  This  summary  information  certainly  has  its  value,  but  it  is  not 
sutlicient  to  guide  and  inform  the  manufacturer  exactly  as  to  what  uses  he 
can  convert  any  given  lot  of  rubber.  What,  then,  are  the  principal  point-  on 
\\hich  he  must  be  enlightened1?  The  answer  is  short  and  precise. 

Points  to  be  determined  and  elucidated. — 1.  Moisture. — The  quantity  of 
interstitial  water  in  the  pores  of  the  rubber,  and  whether  it  does  not  exceed  t  he- 
normal  quantity.  2.  Extraneous  mineral  matter. — The  quantity  of  inert  mineral 
matter,  whether  incorporated  accidentally  or  intentionally.  3.  Extraneous  organic 
matter. — The  amount  of  extraneous  organic  matter  of  the  same  origin  as  the 
mineral  matter.  4.  Extraneous  matter  introduced  by  method  of  coagulation. — The 
quantity  of  foreign  bodies,  whether  organic  or  inorganic,  the  presence  of  which  is 
chiefly  due  to  the  methods  of  coagulation.  5.  Oxidised  rubber. — The  quantity  of 
oxidised  rubber,  that  is  to  say,  rubber  which  has  lost  the  properties  indispens- 
able to  its  industrial  use.  6.  Ash. — The  quantity  and  nature  of  the  ash  which  a 
given  weight  of  substance  may  yield  on  incineration.  7.  Resistance  to  st, 
The  total  resistance  yielded  by  the  sample  under  a  determined  strain.  8.  Micro- 
scopical examination. — A  microscopial  examination  may,  on  the  other  hand, 
complete  this  analysis,  and  yield  information  in  regard  to  the  origin  of  the  rubber 
which  direct  analysis  can  only  with  difficulty  afford. 

Sampling. — The  great  difficulty  in  testing  rubber  lies  in  getting  a  fair  average 
sample.  The  method  which  appears  to  us  to  give  the  best  i>ossible  results  is  as 
follows  :  (1)  To  take  different  samples  from  different  parts  of  the  inside  as  well  as 
the  outside  of  the  cakes  or  blocks  to  be  analysed.  (2)  To  shred  and  roll  these 
sufficiently,  and  to  take  from  the  few  samples  at  different  points  so  as  to  get  a  fair 
average  sample. 

Determination  of  interstitial  moisture. — This  operation  is  delicate,  because 
rubber,  even  the  purer  kinds,  always  contains  in  its  pores  some  5  \vr  cent,  of 
water,  which  we  shall  call  the  normal  quantity,  which  is  not  eliminated,  even  by 
prolonged  drying  at  100°  C.  (212°  F.).  The  sample,  reduced  to  as  thin  a  sheet  as 
possible,  by  passing  through  cold  rolls,  is  weighed,  then  laid  upon  a  watoh-ghiss  and 
dried  in  the  hot-air  oven  between  110°  and  120°  C.  (230°  and  248°  F.),  until  it 
ceases  to  lose  weight.  By  taking  a  few  precautions,  the  total  interstitial  moisture 
may  be  thus  determined  in  about  two  hours.1  Two  watch-glasses,  ground  so  as  to 
form  a  hermetic  joint,  and  capable  of  being  bound  by  an  indiarubber  band,  are 
used.  The  rolled  sheetlets  of  rubber  are  placed  on  one  of  these  glasses,  and  so  taken 
to  the  oven.  After  the  lapse  of  an  hour,  the  sample  is  taken  out  along  with  tin- 
glass,  and,  after  being  covered  with  the  second  glass,  the  caoutchouc  ligature  is  put 
in  position,  and  the  whole  cooled  in  a  desiccator  and  then  weighed.  The  processs 
is  gone  over  again  until  no  further  loss  in  weight  occurs.  The  loss  in  weight  P 
1  Gypsum  (Terra  alba)  loses  its  water  of  crystallisation  between  these  temperatures.  —  TR. 


224  INDIARUBBER 

constitutes  the  total  moisture.     By  deducting  5  per  cent,  of  normal  water  j.. 
in  every  rubber  of  whatever  kind  it  may  be,  we  then  get — 

Water  =  (P -  5  per  cent.). 
The  sample  so  dried  is  put  aside  for  future  use. 

Determination  of  inert  vegetable  and  mineral  matter. — For  the  determination  of 
fragments  of  wood  and  stones  of  a  certain  size,  often  met  with  in  certain  blocks, 
quantitative  analysis  is  not  practicable,  and  the  examination  of  sections  of  several 
blocks,  by  the  naked  eye,  is  sufficient  for  any  practical  man  however  little 
experienced.  It  is  only  the  amount  of  sand,  clay,  and  vegetable  debris,  so  minute 
as  to  escape  detection  de  visu,  that  is  now  in  question.  Ten  grammes  of  rubber, 
laminated  as  described,  are  dissolved  in  spirits  of  turpentine  or  in  benzol  at  40°  to 
55°  C.  (104°  to  131°  F.).  The  insoluble  is  collected  on  a  filter,  washed  several 
times  with  the  same  vehicle  until  no  rubber  is  left  on  evaporation.  The  residue 
is  dried  and  weighed.  The  difference  in  weight  gives  the  total  organic  and  in- 
organic matter  in  the  sample.  By  incinerating  the  residue  in  a  suitable  manner, 
the  quantities  of  organic  and  mineral  matters  are  obtained  separately  by  difference. 
If,  however,  only  the  weight  of  the  mineral  matter  be  required,  simple  incineration 
of  the  rubber  in  a  platinum  crucible  is  sufficient.  But  to  obtain  a  mineral  ash, 
perfectly  exempt  from  carbon,  produced  by  the  incomplete  combustion  of  the 
organic  matter,  a  few  pinches  of  nitrate  of  ammonia  must  be  added,  with  infinite 
precaution,  to  the  red-hot  mass  after  prolonged  ignition,  slightly  inclining  the 
crucible.  The  results  obtained  by  this  second  summary  method  are  not  strictly 
accurate ;  the  total  ash  would  include  alum,  common  salt,  etc.,  from  the  coagulation 
process,  besides  mineral  residues  originating  from  the  intimate  constitution  of  the 
rubber  itself ;  the  latter  may  be  neglected,  unless  it  be  a  question  of  determining 
by  analysis  the  exact  origin  of  a  certain  kind  of  rubber. 

Determination  of  the  organic  and  inorganic  matter  derived  from  the  process  of 
coagulation. — To  determine  the  total  organic,  or  inorganic,  acid,  or  saline  matter  in 
the  rubber  being  analysed,  the  dried  rubber  used  for  the  determination  of  moisture, 
and  the  percentage  of  moisture  in  which  is  therefore  known,  is  boiled  in  a  small  flask 
for  a  long  time  with  distilled  water.  The  substance,  after  nitration  and  repeated 
washing,  is  dried  in  the  hot-air  oven,  with  the  same  precautions  as  formerly,  and 
finally  weighed ;  the  loss  in  weight  gives  the  soluble  matter,  and  this  loss  P'  will 
be,, if  we  represent  the  loss  in  water  by  (P  -  5),  the  initial  weight  by  C,  and  finally 
the  weight  actually  found  by  C', 

F  =  C-(C'-(P-5)). 

A  qualitative  examination  of  the  wash  water,  added  to  the  water  in  which  the 
rubber  was  first  boiled,  will  give  information  as  to  the  mixture  of  acids  and  salts 
eliminated. 

Determination  of  the  oxidised  rubber.— This  determination,  very  important 
with  certain  kinds  highly  charged  with  this  substance  so  prejudicial  to  the  nerve  of 
the  rubber,  is  made  thus :  A  weight  is  taken  equal  to  that  taken  for  the  estima- 
tion of  the  water,  and  treated  with  boiling  90  per  cent,  alcohol  for  half  an  hour. 
The  residue  is  thrown  on  a  filter,  washed  repeatedly  with  boiling  water,  then 
placed  as  formerly  in  the  hot-air  oven  and  dried  at  120°  C.  (248°  F.),  until  it 
ceases  to  lose  weight.  If  we  represent  the  oxidised  rubber  by  P"  and  the  weight 
found  by  C",  we  get — 

P"  =  C-(C"-(C'-(P-5)). 

The  evaporation  of  the  alcohol  liquid  and  its  suitable  treatment  will,  moreover, 
furnish  indications  as  to  the  nature  and,  if  need  be,  the  quantity  of  the  substances 
so  eliminated. 

Analysis  of  vulcanised  rubber.  —  From  the  phenomena  observed  in  the 
study  of  vulcanised  rubber  Donath  enunciates  the  following  law : — The  value  of 
vulcanised  rubber  articles  is  perceptibly  proportional  to  the  rubber  content,  and 
dependent  upon  the  ratio  betiveen  rubber  and  the  quantity  of  sulphur  or  metallic 
sulphides  used  in  their  vulcanisation. — Suppose  we  call  (1)  the  value  of  the  rubber, 


CONSIDERATIONS   ON    MINERALISATION,    ETC. 

V;  (•_')   it-    pereeiitage  of  sulphur,   S.  (:\)  its  percentage  of   mineral  or  organic 
matter,  I-!,  we  get — 

V_100-(S  +  E) 
S 

To  determine  tin-  elements  of  V,  therefore,  a  simple  proximate  chemical  analyst* 
is  Mitlirieiii.  and  it  is  only  in  special  cases  that  we  have  also  to  examin.-  the 
elasticity  :uid  re>istanee  of  tin-  rubber. 

Donath's  la\v  is  too  absolute  (Dr.  Lobry  and  Van  Leent  (''//<//,//,•</•  /£•//«/»/, 
is'.'l,  1 1.  ."»<''.»)):  it  presupposes  tin-  identity  in  proper!  irs  of  tin-  rubln-i- employd  in 
th.-M-  dim-rent  articles  —  a  very  doubtful  supposition,  e\en  it'  tin-  roins  in  dinVivnt 
quantities  and  of  diverse  qualities  which  accomjiany  natural  rubbers  of  dill.-ivnt 
origin  be  eliminated.  Practice  shows  that  two  rubbers  prepared  from  ' 
raw  rubber,  the  OHO,  however,  containing  :\  and  the  other  6  per  cent.  of  sulphur, 
may  be  equally  good,  although,  aceording  to  Donath's  law,  the  first  sample  ought 
t-i  be  of  double  the  value  of  the  second. 

1.  ,s/«W//v  </,•<!>•/ ft/ — Ash. — The  opinion  expressed  by  the  generality  of  special  i-t 
writers  that  the  knowledge  of  the  8}>ecific  gravity  of  manufactured  rubber 
].owerful  factor  in  its  valuation  has  already  been  refuted.  A  density  Io\\«-r  than 
from  o-Di'ii  to  0*948  does  not  decisively  show  the  good  quality  of  a  rubbn.  - 
dust  and  cork  raspings,  far  from  weighting  this  substance,  on  the  contrary  lighten 
it,  and  nevertheless  these  substances  are  classed  with  the  most  injurious  additions. 
Ten  per  cent,  of  vermilion  or  of  ealeimn  fluoride  influences  the  density  in  quite  an 
opposite  direction  to  that  of  an  equal  quantity  of  talc  or  magnesia,  etc.  It  is  \\ell, 
however,  to  know  in  certain  cases  the  density  of  the  substance  to  be  analysed.  It 
may,  up  to  a  certain  point,  aid  in  the  valuation,  but  only  where  the  mineral 
substances  added  are  not  vulcanising  agents  like  vermilion,  sulphide  of  antimony, 
etc.,  because  such  agents  increase  the  density  much  more  than  talc  or  other 
lighter  mineral  substances,  and  yet,  far  from  injuring,  they  almost  always  improve 
its  quality  and  increase  its  durability.  To  determine  the  density  of  a  sample  of 
rubl>er  by  the  picnometer  (a  modification  of  the  classical  specific  gravity  hot 
the  sample  is  divided  into  small  thin  strips  of  equal  length ;  after  being  weighed, 
they  are  boiled  with  water  in  the  apparatus,  which  is  first  tared  empty  and  then 
weighed  full  of  water  so  as  to  get  rid  of  the  air-bells  which  adhere  rather  strongly 
to  certain  places.  Many  samples  which  float  on  the  surface  of  the  water  fall  to 
the  bottom  after  the  operation.  This  done,  the  picnometer  is  again  filled  with 
water  to  the  mark  and  again  weighed  ;  the  increase  or  decrease  in  weight  is 
obtained  by  simple  calculation.  An  example  will  render  this  simple  operation 
easily  understood— 

TABLE  L. — SHOWING  A  TYPICAL  RESULT  IN  FINDING  DENSITY  OF  RUBBER, 
WITH  NECESSARY  CALCULATION. 


the  weight  of  the  empty  picnometer  to  be     10  grammes!  weight  of  {licnonirtiT  full, 
,,  ,,  water  to  fill  it          ,,       100      ,,         j  110  grammes. 

,,  „  rubber  ,,          5      ,, 

And  finally  tin-  weight  of  the  pirnometrr  contain- 
ing the  rubber,  and  filled  with  water,  to  be  111       ,, 


The  rubber  having  therefore  replaced  the  water,  has  -:i\vn  an  increase  of  1 
UM. inline.  Dividing  the  absolute  weight  of  the  rubber  (5  grammes)  by  the  weight 
of  the  water  displaced,  that  is  to  say,  4  grammes,  the  density  of  the  substance  tested 
will  be  |  =  1'L'"><>.  //<///>/////,/ s  approximate  method. — Heinzerling  uses  a  more 
rapid  and  simple  but  less  exact  method,  which  should  be  of  use  in  factories.  He 
prepares  a  series  of  test-glasses  on  feet  filled  with  liquids  of  gradually  and  uniformly 
increasing  density.  He  uses  for  this  purpose  various  solutions  of  calcium  chloride 
up  to  a  density  of  1*40.  As  calcium  chloride  is  insoluble  in  water  after  that 
15 


226 


INDIARUBBER 


density  has  been  reached,  his  density  experiments  did  not  go  beyond  that.     He  in 
that  way  established  the  following  scale  :— 

TABLE  LI. — SCALE  OF  DENSITIES  AND  FORMULA  OF  SALINE  SOLUTIONS  FOR 
DETERMINING  DENSITY  OF  RUBBER  (HEINZERLING). 


Test-Glass  on  Foot. 

Density. 

°Twaddell. 

0 

2.  Water  and  calcium  chloride 

1-025 

5 

3. 

1-050 

10 

4. 

1-075 

15 

5. 

1-100 

20 

6. 

1-125 

25 

7. 

1-150 

30 

8. 

1-175 

35 

9. 

1-200 

40 

He  determines  the  density  of  rubber  by  dipping  a  sample  into  each  test-glass  in 
rotation,  and  observes,  after  a  little  time  of  contact,  when  all  the  air-bells  have 
disappeared  from  the  sections  of  the  sample,  in  which  of  the  solutions  the  rubber 
floats  between  two  liquors  without  going  to  the  bottom.  The  specific  gravity  of 
the  liquid  in  which  it  floats  is  the  same  as  that  of  the  rubber  tested.  Tests, 
made  in  Belgium,  on  tubes  of  different  quality,  gave  the  following  results  by 
the  picnometer  : — 

TABLE  LII. — SHOWING  INFLUENCE  OF  PERCENTAGE  OF  ASH  ON  DENSITY 

(HEINZERLING). 


Prime  Quality. 

Low  Quality. 

Density          ...... 
Ash       

0-99-1-20 
2-83-25  per  cent. 

1-26-1-52 
3  4  -30  -38  "60  per  cent. 

The  ashes  of  low  qualities  consisted  chiefly  of  chalk  and  the  oxides  of  zinc  and 
iron.  This  latter  oxide  dominates  in  red-coloured  tubing.  Reinhardt  gives  the 
following  results : — 

TABLE  LIII. — SHOWING  INFLUENCE  OF  PERCENTAGE  OF  ASH  ON  DENSITY 

(REINHARDT). 


Sample  1. 

Sample  II. 

Density          .... 

1*480 

1-958 

Ash        

53'57  per  cent. 

62-66  per  cent. 

The  ash  consisted  chiefly  of  fluor  spar  and  zinc  oxide.     Donath  gives  his  own 


TABLE  LIV. — SHOWING  INFLUENCE  OF  PERCENTAGE  OF  ASH  ON  DENSITY 

(DONATH). 


White  Gas 
Tubes, 
(a.) 

Red  Tubes 
of  Excellent 
Quality. 
(6.) 

Red  Tubes 
of  Average 
Quality. 

(c.) 

Red  Balls 
Half  Full. 
(d.) 

Density         .         .         . 

]  -Q12 

1  '1  '34 

1'089 

1-133 

Ash      .... 

6  '62 

Q.I  A 

n-79 

21*86 

Predominant  substance  in  the  ash 

Zinc  oxide. 

Sb204 

Vermilion. 

Vermilion. 

CONSIDERATIONS  ON   MINERALISATION,    ETC. 

The  (li-iisiiy  «>f  the  product  then-tore  does  not  de^nd  solely  on  the  nature  and 
the  amount  of  additional  substance,  Imt  al>.>  u|».n  the  method  of  vul« Mnisatiun  and 
tin-  mechanical  process  by  which  tin-  mineral  substance  is  incorporated. 

A  n nth,  /•  •  ninlynt —  • 

TABLE  LV.— Sim  WIN.;  THE  INFLUENCE  OP  PERCENT  A<JE  op  AKH  ON 
DENSITY  (DONATH). 


Iii'liurubber  Sheet  or  Foil. 

«. 

/• 

Density         
A^li       
Predominant  substance  in  the  ash 

1-566 
56-08 
Chalk  and  gypsum. 

1-488 
72-10 
Oxide  of  zinc. 

In/ the  ash  retained  the  shape  of  the  small  cubes  of  the  cut  sample. 

N.B. — Rubbers  having  a  greater  density  than  1'3  should  invariably  be  regarded 
as  (defective,  because  they  contain  not  less  than  25  per  cent,  of  mineral  matters 
which  lower  their  value. 

2.  Estimation  of  mineral  additions. — Direct  calcination  always  yields  erroneous 
results  (Donath).  Thus  vermilion  in  admixture  will  partially  volatilise  on  calcina- 
tion,1 whilst  carbonate  of  lime  will  decompose.  It  results  from  this  want 
of  precision  that  the  operation  is  not  always  an  easy  nor  a  simple  one.  The 
following  is  an  approximate  method  of  estimation : — From  J  to  1  gramme  of  the 
sample  is  cut  into  thin  strips  and  steeped  in  a  solution  of  ammonium  nitrate, 
and  the  strips,  previously  dried,  are  thrown  one  after  the  other  into  a  porcelain 
crucible  lying  almost  horizontally  on  the  flame ;  the  crucible  is,  moreover,  brought 
to  a  red  heat  before  commencing  the  incineration.  If  it  has  been  previously 
ascertained  by  qualitative  analysis  that  the  substance  is  not  very  highly  charged 
with  lime,  the  calcined  product  may  be  weighed  directly ;  but  if  the  ash  is  likely 
to  contain  much  free  lime  it  is  moistened  with  a  concentrated  solution  of 
ammonium  carbonate  and  heated  slightly  before  weighing.  Keinhardt  treats  the 
rubber  with  boiling  nitric  acid  to  dissolve  organic  matter,  and,  after  evaporating 
the  liquid  to  dryness  with  hydrochloric  acid,  he  estimates  according  to  the  ordinary 
classical  methods  the  oxides  of  zinc,  calcium,  magnesium,  etc.  This  evidently 
more  exact  but  too  long  process  is  not  usually  necessary:  the  approximate 
percentage  which  is  determined  from  the  weight  of  the  suitably  prepared  ash  gives 
indications  which  are  always  sufficient  to  decide  as  to  the  value  of  the  sample 
examined.  Donath  found  a  minimum  of  6 '62  per  cent,  ash  in  a  gas  tube,  and 
72'21  per  cent,  in  a  "washer."  Donath  gives  the  following  order  of  frequency  for 
the  different  mineral  substances  added — chalk,  oxide  of  zinc,  gypsum,  ihior  spar, 
talc.  He  has  never  found  oxide  of  iron  in  appreciable  quantity. 

Estimation  of  sulphide  of  mercury. — Weigh  out  from  J  to  1  gramme  of  the 
sample,  reduce  to  a  fine  jrcwder  by  the  grater,  or  cut  into  small  fragments,  and 
treat  in  a  precipitation  flask,  which  will  stand  heat,  with  30  c.c.  of  ordinary  nitric  acid, 
and  heat  until  bright  red  fumes  cease  to  be  disengaged.  The  hydrocarbide  is 
entirely  dissolved,  the  vermilion  remains  intact.  The  clear  liquid  is  decanted  after 
cooling,  and  the  residue  washed  two  or  three  times  with  nitric  acid.  It  would  not 
do  to  immediately  wash  with  water,  as-  long  as  there  remains  any  hydrocarbide 
dissolved  in  the  acid ;  in  contact  with  water  it  would  be  precipitated,  and  become 
mixed  with  the  mineral  residue.  The  residual  sulphide  is  run  into  a  tared  glass 
vessel,  washed  with  water,  dried  at  180°  C.  (212°  F.),  and  weighed.  Vermilion 
can  nearly  always  l>e  detected  in  a  mixture  by  the  bright  coralline  red  colour 
which  it  imparts  to  the  rubber.  Rubber  vulcanised  by  vermilion  is  almost  always 

J  Genuine  vermilion  by  itself  is  practically  completely  volatile,  leaving  only  an  infinitesimal 
ash.— TR. 


228  INDIARUBBER 

heavier  than  water.  Donath  found  1T72  per  cent,  in  gas  tubing,  21 '8  per  cent, 
in  a  half-filled  ball.  These  two  samples  were  excellent  quality  rubbers  which  had 
preserved  both  elasticity  and  pliancy  for  several  years.  N.B. — The  fresh  section  of 
this  rubber  shoivs  an  amount  of  adhesiveness  not  met  with  in  rubber  vulcanised  by 
any  other  process. 

Estimation  of  antimony  sulphide. — Rubber  of  not  so  deep  a  red  colour,  or  of 
a  brown  red,  generally  contains  antimony  sulphide.  It  is  used  alone  (Unger),  but 
it  is  now  generally  replaced  by  a  solution  of  sulphantimoniate  of  lime,  hyposulphite 
of  lime,  and  polysulphide  of  lime.  This  mixed  solution  is  precipitated  by  sulphuric 
acid.  The  product  so  obtained  is  a  mixture  of  golden  sulphide  of  antimony, 
sulphate  of  lime,  and  free  sulphur  in  variable  proportions.  1.  Unger 's  method. — 
The  best  method  of  estimation  is  that  of  Unger :  Heat  1  '5  gramme  of  the  finely 
divided  sample  in  a  capacious  porcelain  crucible  with  10  grammes  of  crystallised 
sodium  sulphide,  moderate  heat  until  intumescence  ceases,  and  heat  gradually  to 
dull  redness.  After  cooling,  the  residue  is  extracted  from  the  crucible  by  distilled 
water,  filtered  to  separate  the  charcoal  produced  by  incineration  of  the  organic 
matter,  and  the  filtered  liquid  is  precipitated  by  hydrochloric  acid  (HC1).  The 
antimony  sulphide  and  the  sulphur  is  collected  on  a  double  tared  filter,  dried  and 
gently  calcined  in  a  double  crucible,  until  the  sulphur  is  completely  dissipated ;  the 
weighed  residue  constitutes  the  antimony  sulphide.  2.  Alternative  method. — The 
sulphide  of  antimony  and  sulphur  are  dried  until  of  constant  weight,  a  known 
quantity  is  taken  and  converted  into  Sb2O4.  3.  Another  method. — Or,  better  still, 
if  there  be  not  much  antimony  sulphide :  wash  by  decantation,  passing  the  wash 
water  through  a  filter,  redissolve  the  precipitate  in  ammonium  sulphide,  with  the 
addition  of  a  little  warm  ammonia.  This  liquid  is  passed  through  the  same  small 
filter  which  has  been  used  to  collect  the  antimony  sulphide  carried  along  during 
decantation ;  it  contains  all  the  antimony  sulphide.  It  is  gently  evaporated  in  a 
porcelain  crucible,  and  the  sulphide  finally  converted  into  oxide  Sb2O5.  In  an 
excellent  quality  rubber,  used  in  making  laces  and  thread,  11 '80  per  cent,  of 
antimony  sulphide  was  found.  Articles  vulcanised  by  antimony  sulphide,  recog- 
nisable by  their  brown  brick-red  colour,  and  often  sold  under  the  name  of  supple 
rubber,  are  generally  regarded  as  of  excellent  quality.  They  not  only  exhibit 
remarkable  suppleness  and  elasticity,  but  are  very  durable.  Samples  preserved  for 
eight  years  were  intact  in  regard  to  quality.  But  these  are  precisely  the  dearest 
kinds  of  rubber. 

Estimation  of  the  total  sulphur — Donath's  original  method. — This  is  an  element 
important  to  estimate.  Donath  firstly  estimated  it  (in  this  instance  rubber  not 
loaded  with  any  sulphate,  such  as  gypsum  or  barytes)  thus  : — He  took  a  gramme 
of  the  substance  finely  divided  either  by  rasp  or  file,  and  heated  with  nitric  acid 
until  no  more  bright  red  fumes  were  evolved ;  he  evaporated  the  solution  to  dry- 
ness  with  hydrochloric  acid  and  chlorate  of  potash,  dissolved  the  residue  in  hot 
water,  acidulated  with  hydrochloric  acid,  and  he  precipitated  in  the  filtrate  the 
sulphuric  acid  as  barium  sulphate.  The  organic  bodies  from  the  oxidation  of  the 
rubber  are  partially  precipitated  by  dilution,  and  render  nitration  difficult  and 
tedious.  Donath's  improved  piwess. — Donath,  therefore,  adopted  Eschka's  process 
for  estimating  sulphur  in  fuel,  but,  owing  to  the  difficult  combustion  of  rubber,  he 
added  to  his  oxidising  mixture,  magnesium  nitrate,  in  addition  to  ammonium 
nitrate.  He  intimately  mixes — 

TABLE  LVI. — DONATH'S  MIXTURE  FOR  CALCINING  RUBBER  FOR  ASH 
DETERMINATION. 


Finely  divided  rubber 
Calcined  magnesia 
Nitrate  of  magnesia 
Nitrate  of  ammonia 
Carbonate  of  soda 


0'5  to  1.  gramme. 
\  gramme. 


CONSIDERATIONS   ON   MINERALISATION,   ETC.         221 

He  places  tliis  mixtmv  iii  ;i  tail   narrow  crucible,  and  co\er-  it  \\ith  a  layer  of 

tin-  above  mixture.      Tin-   enieil.le,  li\ed    obliquely.  alni"M   tl.it,  i-  at  tir>t  heated  ,,|, 

the  upper  portion,  then  gradually  to  wardfl  iln-  bottom,  ami  tin-  heating  continued 

to   redlie--.         Its    perlertly    \\llitr  nuitenls  aiv  e\tr,ieted,    \\itli  al»«,tlt    .",()()  giainili' 
hot   \\jiter,  tin-   .solution    filtered,  acidulated    l>y  h\droehloric   aeid,    and    precipitated 
l'\  liariiun  chloride.     By  this  method  then-  is  estimated,  along  with  the  milplmr 
used  in  vul<  -anisation,  th.it  present  as  gypsum  or  barytes,  etc.     To  get  the  vuli  ai 
tion  sulphur,   the  latter  substances  must  be  estimated.     Utu/er'*  met/iod. — Total 
sulphur  i*  determined  by  fusing  alxmt  0'")  gramme  of  the  sample  divided  into  100 
pieces,   \\ith  a  mixture  of   I  •_'   per  cent,  of  copper  oxide  and  2  grammes  of  Hodic 

carbonate.       This  method  is  likewise  to  l>e  recomiueiided. 

Kttiiit'ition  «f  n/tranisation  sulji/mr  o /////—  AV/// //«/•< lt\  process. — The  sample  i> 
introdiK -ed  into  a  hard  glass  tube,  closed  at  one  end  and  enlarged  about  its  middle. 
The  open  extremity  is  drawn  out  over  the  blowpipe  and  closed.  The  i>ortion  of 
the  tube  containing  the  rubber  is  heated  over  the  naked  flame,  the  vulcanisation 
sulphur  distils  and  condenses  with  the  other  dry  distillation  products  in  the  bloun 
out  portion  of  the  tube.  The  sulphur  is  then  estimated  by  one  of  the  known 
processes.  Precaution: — A  portion  of  the  vulcanisation  sulphur  may  \er\  \scll  be 
retained  in  the  state  of  sulphite  by  the  oxide  of  zinc,  or  by  the  chalk,  and  thus 
escape  distillation  and  estimation.  Xo  method  for  direct  determination  of  vnlc.m 
i  sat  ion  sulphur  is  known  and  only  a  more  or  less  approximate  estimation  can  be 
made  of  the  proportion  in  certain  cases  by  means  of  an  indirect  calculation.  The 
author !  obtained  the  following  results  by  Eschka's  process  : — 

TABLE  LVII. — RESULTS  OBTAINED  IN  CALCINING  RUBBER  BY  ESCHKA'S  PROCESS 
FOR  DETERMINATION  OP  MINERAL  INORGANIC  INGREDIKM  -. 


Kul.ber  for  stoppers 


liul.W  for  joints 


(Ash      .  25 '85  per  cent. 

\Sulphur  6-47 

fAsh      .  23-78 

\  Sulphur  7-21 

/Ash      .  50-08 

•\  Sulphur  5-48 

/"Vermilion 

Rubbers  (two)  containing!  Sulphur  calculated  on  6  per 

vermilion      .         .         .  j     cent,  of  vermilion      .         .       1  '61 

VTotal  sulphur  found  directly       T90 


Consisting  principally  of  chalk, 
magnesia,  and  silica. 


Consisting  of   zinc  oxide  and 

chalk. 
1 1  -72  per  cent.      21  -86  per  cent. 


3-01 
3'28 


From  the  two  last  analyses,  these  two  rubbers  appear  to  have  been  vulcanised 
by  vermilion  alone,  which  would  accord  with  the  function  of  vermilion  as  a  vul- 
canisation  agent.  This  is  a  very  serious  argument  against  the  theory  of  chemical 
combination  between  sulphur  and  rubber  through  the  medium  of  metallic  .sulphides. 
Because,  by  dissolving  with  nitric  acid,  the  rubber  gives  up  all  its  vermilion  as 
such,  and  consequently  also  the  total  of  its  sulphur,  which  could  not  be  the  case  if 
a  portion  of  the  sulphur  had  entered  into  chemical  combination  with  the  rubber. 
By  the  following  process  we  can  ascertain  the  amount  of  vulcanisation  sulphur, 
roughly  it  is  true,  but  near  enough  in  most  cases.  One  gramme  of  rubber,  of 
which  the  i>ercentage  of  sulphur  is  known,  is  cut  up  and  boiled  for  a  certain  time, 
half  hour  to  one  hour,  with  caustic  potash  of  average  concentration  (Sp.g.)  =  l*2. 
The  sample  to  be  tested  is  treated  in  exactly  the  same  manner  at  the  same  time, 
The  liquors  are  decanted  and  brought  to  the  same  degree  of  concentration,  and 
1  c.c.  of  a  solution  of  lead  acetate  is  added  to  each.  The  respective  amount  of 
sulphur  present  in  each  is  judged  from  the  relative  abundance  of  the  black  pre- 
cipitate in  the  two  glasses.  Kuhhers  vulcanised  by  metallic  sulphides  cannot,  of 
course,  be  so  tested.  The  two  samples  containing  vermilion,  the  analyses  of  which 
are  given  above,  only  yielded,  when  acetate  of  lead  was  added  to  their  alkaline 

1  ?  Reinhardt.— TR. 


230 


INDIARUBBER 


decoction,  a  faint  brownish  tint — a  fact  which  supports  what  has  been  said  in 
regard  to  vulcanisation  by  vermilion  alone. 

Estimation  of  ammonia. — This  substance  is  only  present  accidentally  in  the 
composition  of  trade  mixtures  when  it  is  required  to  prepare  a  porous  and  spongy 
substance.  Incineration  eliminates  it  totally.  It  may  be  detected  by  treating  a 
fragment  of  the  substance  to  be  tested  with  a  little  quicklime.  Ammoniacal  salts 
are  detected  by  the  disengagement  of  ammonia,  the  smell  of  which  is  characteristic. 
It  is  easily  estimated,  quantitatively,  by  Will  and  Warrentrap's  process. 

Examination  of  the  action  of  concentrated  alkaline  solutions  and  solvents. — It 
is  often  necessary,  in  testing  rubber,  to  treat  it  with  concentrated  alkaline  solutions 
and  solvents.  If  the  rubber  contains  a  fat,  resin,  or  paraffin,  all  of  which  approach- 
ing rubber  in  density  and  the  presence  of  which  cannot  be  detected  by  taking  the 
density,  recourse  is  had  to  a  solvent  like  spirits  of  turpentine,  or  to  carbon  sulphide 
to  which  5  per  cent,  of  alcohol  has  been  added.  By  digesting  the  finely  divided 
sample  for  several  hours  in  one  of  these  solutions,  heated  from  60°  to  70°  C.  (140° 
to  158°  F.),  fatty  substances  unattacked  by  vulcanisation,  resins,  and  paraffin  dis- 
solve before  the  rubber,  which  remains  as  a  residue.  If  the  solvent  be  evaporated 
after  sufficient  digestion,  a  residue  is  obtained  containing,  along  with  a  small 
quantity  of  dissolved  rubber,  the  whole  of  the  above-named  substances.  When  the 
residue  is  treated  with  caustic  soda  solution,  the  resins  and  fats  are  saponified, 
leaving  a  residue  of  unsaponifiable  paraffin.  A  more  exhaustive  examination  of 
the  fats  is  hardly  possible,  and,  moreover,  is  only  of  secondary  interest.  Again, 
paraffin  may  be  detected  in  the  product  evaporated  as  above,  by  treating  it  with 
benzol  or  carbon  disulphide,  in  which  it  dissolves  more  rapidly  than  fats  and 
resins. 

In  spite  of  the  drawbacks  which  will  always  exist  in  methods  of  separation 
of  substances  of  the  character  of  those  by  which  rubber  is  sophisticated,  it  will  be 
seen  from  the  following  results  of  an  analysis  of  a  sample  of  known  composition 
that  information  of  real  value  to  the  manufacturer  is  obtained  by  what  is  called  the 
solution  method  of  indiarubber  analysis. 

The  sample,  a  grey  vulcanised  rubber,  was  made  from  the  following  mixing : — 

TABLE  LVIII. — MIXTURE  USED  IN  MAKING  TYPICAL  VULCANISED  RUBBER 
FOR  ANALYSIS  (GRIMSHAW). 


Native  rubber     . 
Recovered  rubber  (para  No.  12) 

8    1 
3 

b.   =  13'3  per  cent. 
=     5'°       i) 

9  >                                                    35 

12 

=  20-0       ,, 

Zinc  oxide  . 

8 

Whiting     .... 

20 

Magnesia    .... 

\ 

2 

=   59-2       „ 

Litharge     .... 

5 

Lime  .... 

J^ 

Sulphur      .... 

H 

=     2-5 

60 


100-0 


TABLE  LIX. — CLASSIFICATION  OF  INGREDIENTS  IN  TABLE  LVIII. 


(a.) 


Per  cent. 


Indiarubber 
Mineral  matter 
Sulphur     . 


31-8 

657 

2-5 

100-0 


CONSIDERATIONS   ON   MINERALISATION,   ETC.         231 


Turning  to  tin-  percentage  r"iiip<Mti'.u  ,,1  tin    ~,nnpl.-  M  •!•  t<-rmined  l.y  ;inal\-i-, 
we  get 

TAHI.K    I.\.      Ui. -i  ii    ••!    AjfALYBie   01    \i  i.<  LNISBD    MivruKK  OF 
TM-.I  i-   LVIII.  AM.    LI.V 


(6.) 

Perotnt 

•>•>  ,;<•. 

Ki-sins.  oils,  ai.il  1.  iliiiiiiin.il>  m.itl.  i     . 
M  iin-ral  luatti-r  ....... 
Sulphur      

8-97 
6.V9 
2-48 

• 

100-00 

The  aiial\-i-  Afl  r.il.-ulated  from  the  mixing  is  really  as  follows: — 

TABLE  LXI. — ANALYSIS  CALCULATED  FROM  ABOVE  TABLEH. 


(c.) 

Per  cent. 

Indiambber       ....... 
Resins        ........ 
Mineral  matter  ....... 

277 
4-10 
65'70 

Suljihur      ........ 

2-5 

100-00 

Comparing  the  found  (t>)  with  the  calculated  (c)  there  is  4*87  i«r  cent  more 
resins,  etc.,  shown  by  the  analysis  than  originally  existed  in  the  mixing.  Some 
of  this  discrepancy  is  no  doubt  due  to  the  want  of  absolute 
accuracy  in  the  process,  but  even  the  highest  grades  of  rubber 
are  by  the  heat  of  friction  during  mixing,  and  action  of  the 
ingredients  during  vulcanisation  subject  to  the  formation  of  a 
small  percentage  of  soluble  resinous  and  bituminous  bodies  as 
shown  in  the  figures  just  discussed. 

Testing  I-;/  mechanical  strain. — In  certain  cases  it  is  desir- 
able to  make  a  mechanical  resistance  test — traction,  compres- 
sion,  bending,   and    breaking  strain.     In  the  special  chapter 
the  physical  and  chemical  properties  of  vulcanised  rubber,  the 
interesting  work  of  Stewart  on  the  resistance  to  elongation  and 
compression  of  vulcanised  rubber  has  been  summarised.     As 
the  apparatus  which  he  used  for  these  elongation  experiments 
\v;w  very  simple,  and   within  reach  of  every  manufacturer,  it 
will  he  useful  to  give  an  illustration  of  it  (Fig.  91),  which 
indicates  the  arrangement  which  the  shape  of  the  bands  tested 
allowed  to  be  adopted,  so  as  to  avoid,  as  far  as  possible,  fraying 
the  surface  of  the  rubber  and  the   rounded  sections ;  the  iron 
hooks  between  which  the  hand  is  caught  are  polished.     One  of 
these  hooks  is  fixed  to  a  solid  crosspiece,  the  other  carries  a 
plate  to  support  the  weights.     The  lower  plate  and  its  hook 
are  balanced  so  as  together  to  weigh  1  kilogramme  (2 '2  lb.),    Fll{-  91--Aw>aratiu 
the  weight  of  the  rubber  itself  is  quite  neglectable.     Under  a      £rim2Sr 
certain    load    the    indiambber   band   is    at    first   round,  then, 
elongating  itself,   its  two  sides  become   straight  and  parallel.     Two  datum  lines 
have  to  be  marked  on  each  side  of  the  ring  giving  the  exact  length  of  a  portion  of 
the  band  comprised  between  the  two  hooks.     This  is  done  by  pressing  the  unloaded 
ring   between   two   rules   until  the  two  sides  touch,  and  drawing  with  ink  t\\<.  tine 
marks,  starting  from  a  given  point,  which  is  the  initial  length  of  the  band  being 


232 


INDIARUBBER 


tested.  By  working  so,  and  measuring,  after  each  addition  of  weight,  the  vertical 
distance  between  the  two  divisions,  all  error  arising  out  of  the  friction  of  the 
rubber,  or  its  lamination  on  the  hooks  which  sustain  it,  is  avoided.  During  the 
whole  course  of  the  experiments  the  temperature  ought  to  be  as  constant  as 
possible,  varying  between  +14°  and  + 16°  C.  (57 '2°  and  GO'S  F.). 

Stewart  also  used  a  more  complicated  apparatus  to  determine  the  breaking 
strain,  consisting  of  an  English  balance  for  test  springs  of  every  nature  at  the 
arsenal  (Stores  Department)  of  the  Belgian  Railways  at  Malines.  A  A  are  the 
bands  to  be  tested,  previously  well  measured.  A  single  piece,  or  several  pieces, 
with  intercalated  iron  plates,  were  used  according  to  their  height.  B  is  an  iron 
screw,  turning  in  a  bronze  nut,  fixed  on  the  cast-iron  framework  of  the  apparatus; 
it  is  terminated  (1)  by  a  large  fly-wheel,  with  six  arms,  the  circumference  of  the 
felly  of  which  is  divided  into  thirty-six  equal  parts ;  and  (2)  by  a  round  head 


LUJ 


FIG.  92. — Apparatus  for  determining  the  breaking  strain  of  indiarubber  bands. 

which  advances  without  turning,  thanks  to  two  claws,  C  C,  sliding  on  the  frame- 
work. The  bands  are  held  between  this  head  of  the  screw  and  a  strong  wooden 
crosspiece  D  covered  with  iron  plate.  This  latter,  receiving  in  its  centre  all  the 
effort  of  pressure,  transmits  it  by  means  of  the  two  levers  E  E,  mounted  on  steel 
knives,  to  the  large  elbow  lever  F,  the  large  arm  of  which  carries  two  different 
running  weights  and  two  corresponding  graduations.  One  of  the  running  weights 
weighs  10'4  kilogrammes  (22*88  lb.),  and  allows  a  force  of  1500  to  3300  kilo- 
grammes (3300  to  7260  lb.)  being  produced;  the  other,  G,  weighs  32*2 
kilogrammes  (70 '84  lb.),  and  allows  of  pressures  on  the  crosspiece  varying 
between  2100  and  7000  kilogrammes  (4420  and  15,400  lb.)  being  measured.  A 
great  difficulty  was  encountered  in  measuring  exactly  the  thickness  of  the  reduced 
rubber ;  to  surmount  it  with  the  greatest  precision  possible.  Stewart  counted  the 
number  of  divisions  through  which  the  fly-wheel  was  turned,  and  deduced  from 
the  path  of  the  screw  the  amount  of  the  compression  the  bands  underwent,  so  that 


CONSIDERATIONS  ON   MINERALISATION,   ETC.        233 

tin-  apparatus  slni\\i-i|  radi  time  in  its  |K>-iti»n  ,,f  equilibrium  tin-  large  lever  fa 

tu    the    hori/nntal     position    marked    ..n    a    lix.-d     index.      Th--  ,    threads 

on  a  path   oi    170   millimetres  (ls-i71   inches);   the  tlm-ad  \\,^  therefore    r_'-7 

millimein-  (>ay  \    inch),  ami    for  one  tliirtx -sixth  or   one   division    <•!    the  Jl\  \sh.-.-l 
tin-    head    advanced    <)•;;:>:;     millimetre    (>a\     -'.Jill   of   ail    inch).       The    apparati; 
transformed     into    a    gigantie    spheroineter,     \sas     precise    enough     to    r«tiinatr   the 
depression    at    each    Neighing    to   about    a    di\Uion,    i.> .,     \\ith    an   approximation  of 
."»  t.i    I   truths  ,,f  a  niillinieiiv. 

'.••ii'/t'n;/.  Kor  tests  of  resistance  tu  Lending  to  tin-  point  of  rupture, 
no  special  apparatus  is  in  existence.  I  Irin/.rrling  thinks  that  it  \vonl«l  IK-  |nis«ili|r 
to  test  Mililit-r  for  this,  JIM  is  connn'only  'lour  \\ith  li-atln-r,  |>ro\idi-i|  tliat  in 
adapting  tin-  nilthor  hands  to  the  l>ol»  of  a  pcndiilinn  a  sntlicimt  to  and  fro  n 
nicnt  could  la-  produced  to  cause  rupture.  In  fact,  if  the  manner  in  which  the 
-miples  l.chave  to  the  point  of  rupture  he  observed  simultaneously  \\ith  the  SJN-«-«| 
of  the  pendulum,  siit}icii>nt  data  should  be  got  to  appreciate  the  resistance  ,,f  tin- 
object  to  a  bending  strain  up  to  the  point  of  rupture.  It  must  not  be  forgot t- n, 
if  exact  comparative  results  l.e  desired,  to  attach  the  samples  to  the  pendulum  >o 
that  the  Iwndin^  is  always  and  in  every  sense  produced  under  the  _rle. 

/,'•  tutana  f<>  h«it.  .\<-c,.rdin^  to  Dr.  C.  A.  Lobry  and  F.  H.  Van  Leent  (/•„:  ,-,>. ». 
tin  Hi-iti*/!  inn>t/  Ims  t/s></  /<>,•  a  In, 1,1  /////-  //  (><•,•//  ximple  method  far  testiny  tlie  w///- 
»/  i,i,i;,i,;ii,i,, ,-.  Tin-  objects  are  submitted  to  a  dry  heat  of  about  135°  C.  (1J750  F.), 
and  to  moist  heat  in  water  of  about  170°  C.  (338°  F.).  Heat  acts  very  ditterently 
on  pure  good  quality  rubber  from  what  it  does  upon  inferior  kinds  containing  a 
greater  or  less  proi>ortion  of  natural  resin,  or  on  the  qualities  mixed  with  spurious 
rubber  and  other  adulterants.  Para,  pure  or  mineralised,  and  suitably  vulcanised, 
resists  this  test  for  two  to  four  hours  without  a  too  marked  destruction  of  its 
original  qualities.  But  inferior  sorts  present  little  or  no  resistance  at  all  to  the 
action  of  heat,  become  brittle,  tacky,  lose  their  elasticity,  etc.  The  loss  of  weight 
of  rubbers  exposed  in  thin  sheets  for  one  or  three  hours  to  a  dry  heat  of  135°  C. 
( -7-")d  F.)  hardly  reaches  the  figures  shown  below  in  the  case  of  good  qualities — 

TABLE  LXII. — Loss  SUSTAINED  BY  RUBBERS  HEATED  FOR  5  HOURS  TO  DKY 
UK  AT  OF  135°  C.  (275°  F.). 


Name  of  Rubber. 

Loss  after 
One  Hour. 

Loss  after 
Three  Hours. 

Para    
Mozambique         
Borneo         ....... 

Per  cent. 
0-15 
0-20 
170 

Per  cent 
0-2". 
1-30 
3-90 

,,,^  comparative  method  of  analysis. — Kissling  in  his  determination  of 
commercial  vulcanised  ruM)er,  looks  at  the  matter  from  quite  a  special  point  of 
view.  After  an  impartial  resume"  of  existing  literature,  he  claims  that  in  tin- 
analysis  of  vulcanised  and  manufactured  robber  the  uses  to  which  the  object  is 
to  be  put  ought  to  be  taken  into  consideration.  A  joint  for  water  pij»es  might 
to  have  different  properties  and  a  different  comjNisitimi  from  a  gas  tube  or  the 
lining  of  a  manhole  intended  to  resist  the  action  of  excessive  pressure.  A  pump 
Naive  to  resist  the  action  of  corrosive  mineral  acids  should  not  have  the 
same  eoni position  as  one  which  has  to  remain  in  prolonged  contact  with  oil. 
Unfortunately  there  is  little  agreement  in  the  proportions  of  rubber  indicated  as 
required  for  each  special  manufacture.  As  there  is  not,  according  to  Kissling,  a 
simple  and  practical  method  for  determining  in  an  absolute  manner  the  quantity 
of  rubber  present  in  vulcanised  rubber,  as  the  determination  of  the  ash  alone 
proves  nothing,  and  it  has  been  already  shown  how  the  methods  of  determining 
sulphur  in  its  different  conditions  are  not  in  any  way  more  decisive,  it  was  deemed 
well  to  rest  content  with  a  simple  comparative  analysis  of  the  ash  of  the 


234 


INDIARUBBER 


substances  soluble  in  one  or  two  appropriate  solvents,  and  then  to  expose  to  a 
temperature  of  110°  C.  (230°  F.)  for  forty-eight  hours  the  types  chosen  for  tin- 
manufacture  of  the  same  kinds  of  articles,  whether  they  came  from  one  factory 
or  from  another.  He  then  examined  their  suppleness  and  elasticity,  and  finished 
by  a  test  of  resistance  to  rupture.  In  the  Table  LXIII.  Kissling  has  condensed  the 
analytical  results  of  twenty-nine  tests  according  to  his  method. 

TABLE  LXIII. — COMPARATIVE  TECHNICAL  ANALYSIS  AND  VALUATION 
OF  VULCANISED  RUBBER  WARES  ACCORDING  TO  KISSLING. 


Consecutive 
Number  of 
Samples. 

Nature  of  the 
Ware 
Manufactured. 

| 

I1 

•Sfl.| 

III 

lal 

Soluble  in 
Ether. 

3 

Condition  after  being  heated 
tollO°C.  (230°  P.)  for  48 
Hours. 

Coetlicient  of 
Resistance. 

er  Cent. 

Per  Cent. 

Per  Cent. 

1 

Steam  pipe  joints. 

I. 

4-20 

8-76 

1-78 

61-04 

Very  hard  and  very  brittle. 

9 

2 

: 

I. 

4 

8-74 

0-74 

61-08 

9 

3 

9) 

I. 

3-80 

7-82 

1-94 

59-50 

4 

I. 

3-70 

5-28 

1-18 

62-66 

5 

I. 

3 

9-96 

0-73 

63-78 

9 

6 

}j 

I. 

3-30 

6-93 

1-45 

61-42 

9 

7 

I. 

3-60 

7-56 

0-88 

59-64 

Rather  hard   very  brittle. 

8 

8 

II. 

4-38 

1-04 

64 

Hard  but  not  brittle. 

4 

9 

II. 

7-60 

1-18 

66-84 

Hard  and  brittle. 

7 

10 

|j 

III. 

l'-93 

4-82 

0-34 

72 

Very  hard  and  very  brittle. 

9 

11 

}> 

Til. 

1-93 

5-52 

0-32 

70-8 

12 

^ 
" 

III. 

2-53 

5-64 

0-28 

66-64 

Hard  and  brittle. 

'7 

13 

III. 

3 

17-12 

0-44 

60-36 

Very  hard   and  exceedingly 

10 

brittle. 

14 

IV. 

5 

9-36 

0-44 

65-56 

Very  hard  and  very  brittle. 

9 

15 

9            » 

V. 

4-40 

16-30 

0-32 

60-52 

Very  hard  and  exceedingly 

15 

brittle. 

16 

VI. 

3-50 

9-80 

0-08 

62-16 

Very  hard  and  very  brittle. 

3 

17 

ti 

VII. 

5-30 

G-30 

3-06 

48  32 

Hard  but  elastic. 

8 

18 

VII. 

4 

8-44 

0-26 

56-60 

Very  hard  and  rather  brittle 

5 

19 

}) 

VII. 

5-30 

7-30 

1-80 

4952 

Very     hard     and     slightl} 

8 

brittle. 

20 

M 

VII. 

4 

9-32 

0-38 

35-12 

Very  hard  and  rather  brittle 

3-4 

21 

Water  pipe  joints. 

III. 

14-04 

5-20 

0-44 

54-72 

Rather       brittle,       slighth 

2 

elastic. 

22 

M 

VIII. 

10-18 

8-42 

1-24 

55-20 

Rather  soft,  slightly  elastic. 

5 

23 

3  J 

IV. 

11-55 

778 

3-62 

6304 

Hard  and  rather  brittle. 

1 

24 

Rubbers  of  differ- 

VII. 

17-60 

6-66 

2-04 

2-16 

Quite  soft,  very  elastic. 

2 

ent  kinds    and 

quality. 

25 

}> 

JJ 

10-60 

4-70 

3-14 

2-2 

Quite  soft,  rather  elastic. 

2-3 

26 

}J 

8-80 

7-74 

1-10 

32-40 

Slightly  hard  but  elastic. 

3-4 

27 

.} 

)5 

6-64 

6-24 

1-22 

55-10 

Rather    hard    but    slightly 

5 

elastic. 

28 

3  9 

H 

4-44 

7-10 

0-92 

35-44 

Slightly  hard  but  elastic. 

id. 

29 

Rubber  for  lining 

VIII 

4-44 

3-88 

1-10 

39-48 

.  » 

td. 

id. 

canvas  pipes. 

| 

Correlation  of  ash  and  price  of  rubber. — It  results  undeniably  from  an 
attentive  examination  of  these  figures,  that  there  is  always  a  correlation  between 
the  price  demanded  and  the  total  ash.  That  is  readily  understood.  But  this 
correlation  cannot  be  at  all  absolute,  because  not  only  does  the  price  vary  from 
one  article  to  another,  but  vulcanised  rubber  goods  do  not  consist  solely  of  rubber, 
sulphur  and  other  mineral  additions,  but  often,  in  the  case  of  floating  articles,  that 
is  to  say  approaching  nearer  to  the  destiny  of  normal  vulcanised  rubber,  organic 
matter,  cork,  sawdust,  etc.,  are  also  incorporated.  The  real  deduction  to  be  drawn 
from  the  above  Table  is  that  more  than  50  per  cent,  of  ash  cannot  but  be  very 
prejudicial  to  the  preservation  of  the  manufactured  article.  It  is  better  to  buy 
rather  dear  goods  than  to  acquire  a  bad  article  because  it  is  cheap.  But  here 
again  reservations  must  be  made.  Samples  21,  22,  23,  water  pipes  from  three 


CONSIDERATIONS  ON   MINERALISATION,    ETC.          235 

ditl'erent   factories,    show    clearly  that    \<>.  '_'_  is   decidedly  tin?  l>e«t,   although  iniirli 
tin-   cheapest.      Kissling  examines   tin-    pric.-  ami   qualities  of    No-.  •_' I 

ami     I'*,     de-i^m-d     l.\     ilir     Mine     manulact  mvr.    a-    •_: I-    "I     dill'i-n-nt     qiiulit 

Mineral    substances,    ami     |.«.--il-l\    al  ••_Miiic     l»,,|;,-,    ha\e    .-\  idi-nt Iv    nut    l*&n 

added  to  No..  L'  I  and  IT.;    t  hey  n-iM  a  tei,q  „-,  at  MIV  ,  ,|    II-     •  .)"  admirably, 

hut   their  selling  price    is    too    hi^h.       No.  '1 1    was   made  with    I'ara    riil.l..-r,    N... 
with  a  lower  class  rubber  to  which  combu.-tiblc   matter   has   IK-CM   a. I. led.      No**.  26 
ami  27  seem  to  contain  mineral    additions   i»nl\.   \\hiUt    No.  L'S,  tin-    price  of    which 
is  low,  in  spite  of  so  low  a  percentage  of  ash  as  35,  certainly  indicates  admixture 
\\ith   organic   matter    such    as   rubber    \\aste,    reclaimed    or    othrr\\  i-c.       It     -ho\\> 

itself  to  be  naort  resistant  to  a  temperature  of   II"    C,  (230a  I-1.)  than  No.  27  of 

a  higher  price.  In  regard  to  tin;  first  experiments,  Nos.  1  to  I'd,  ((i»  rul>l»er  for 
joints,  it'  we  compare  the  numbers  c-osted  at  the  lowest  price  with  those  the  p 
of  which  would  indicate  a  greater  richness  in  rubber,  it  must  In-  com  hided  that 
the  cheapest  only  contain  but  relatively  small  percentages  of  sound  rubln-r,  smaller 
even  than  that  indicated  by  the  analytical  data,  if  the  richness  in  rubber  be  taken 
by  difference. 

//>///•/</ nest   results. — The   beautiful   investigations   of    Dr.    Rul>.    Il>i>, 
published  under  the  title  "Contributions  to  the  Analysis  of  Manufactured  Kul-i 
(CfonUker  A  ////////,  1892,  pp.   1515,  1623,  1644;  1893,  pp.  644,  807:  and  1  >'.'!. 
PI  i.  411,  442),  cannot  be  overlooked.     The  method  of  analysis  adopted  is,  mon<. 
the  starting-point   of   a   rational   method  for  detecting   and  valuing  indiarui 
substitutes,  which  play  such  an  important  role  in  the  rubber  industry,  and  the 
influence  of  which  is  almost  always  so  injurious  to  the  durability  of  the  goods. 
(See  under  Rubber  Substitutes.) 

/A  ///  :>  i-ling  and  PahVs  metlwd  ("  Annals  of  the  Society  for  the  Advancement  of 

lo'lmtrial  Science,  Berlin,   1891-92  ")  for  determining  t/ie  mineral  and  organic 

substances  on  tJie  industrial  value  of  t/te  vulcanised  rubber  with  which  they  are 

incorporated. — Struck  with  the  almost  insurmountable  difficulties  encountered  in 

the  exact  quant itative  determination  of  each  of  the  substances  which  enter  into  the 

composition  of  vulcanised  rubber,  Heinzerling  and  Pahl  have  attempted  to  get  over 

the  difficulty,  and-in  a  series  of  very  elaborate  and  detailed  investigations  studied  the 

effect  of  the  principal  products  most  frequently  added  to  rubber,  on  its  durability, 

resistance,  elasticity,  and  dielectric  properties.     Unable  to  follow  the  usual  method 

in  the  choice  of  samples  of  a  determinate  composition  coming  within  the  scope  of 

their  researches,  since  (1)  direct  analysis  is  almost  impossible,  especially  for  the 

quantitative  determination  of  the  organic  substances,  other  than  rubber ;  and  ( - ) 

manufacturers  generally  being  unwilling  to  divulge  the  little  secrets  of  their  >]>ccial 

.manufacture,  these  two  chemists  had  typical  samples  made  from  their  data  of  definite 

proportions,  varying  in  this  way  at  will  the  total  amount  of  the  substances  incor- 

I>orated  so  as  to  study  more  exhaustively  the  manner  in  which  each  of  them  behaved. 

Inorganic  and  organic  substances  incorporated. — Besides  sulphur  and  antinu»ny 

sulphide — the  principal   vulcanising   agents  used, — the   authors  incorporated  the 

following  inorganic  substances: — The  oxides  of  zinc  and  lead,  chalk,  caustic  lime, 

calcined  magnesia,  calcium  fluoride  ;  and  the  following  organic  bodies  :  rubber  sub 

stitutes,  oils  vulcanised  by  free  sulphur,  and  by  sulphur  chloride  in  the  cold,  paraffin, 

rosin,  or  colophony,  terebenthine  (turpentine),1  asphaltum,  reclaimed  rubber  powder, 

and  finally  glycerine.     Ten  per  cent,  of  free  sulphur  was  added  as  a  vulcanising 

agent  to  all  the   supple   substances    thus    obtained,  with   the  exception  of  those 

containing  antimony  sulphide,   and   those    already  treated  by   sulphur  chloride  in 

the  cold;  a  small  addition  <>t   sulphur  was  made  to  the  supple  substances  already 

containing  antimony  sulphide,  and  all  submitted  for  one  hour  to  vulcanisation  at 

a  temperature  of  135°  to  138°  C.  (275°  to  280° '4  F.),  under  a  pressure  of  3  t 

atmospheres.     The   special   articles   called   technical   were   made   in   one   of   the 

principal   manufactories   of  Northern  Germany  in    the   usual  proportions,  which 

1  Possibly  Venice  turpentine  or  turpentine  oleo-resiu.     Spirits  of  turpentine  in  this  country 
is  often  termed  "  turpentine."    Hence  much  confusion  with  the  oleo-resins. — TR. 


236  INDIARUBBER 

the  managing  director  with  great  courtesy  communicated  to  the  authors  of  this 
investigation.  The  experiments  on  ebonite  were  less  numerous;  the  substances 
added  in  this  manufacture  are  necessarily  more  restricted,  this  branch  of  the 
manufacture  being  of  itself  less  important.  Two  kinds  of  tests  were  made,  the 
one  based  on  chemical  action,  the  other  on  physical  and  mechanical  action. 

Chemical  tests. — The  chemical  tests  were  made  from  the  point  of  view  of 
the  substances  with  which  rubber  most  often  comes  in  contact.  These  are — 1. 
Sulphuric  acid. — (This  acid  was  chosen  because  its  corrosive  action  has  the 
greatest  effect  on  rubber,  with  the  exception  of  nitric  acid,  which  destroys  it.)  2. 
Acetic  acid. — (This  is  the  organic  acid  with  the  most  characteristic  energy;  it, 
moreover,  is  the  one  which  comes  most  often  in  contact  with  rubber.)  3.  Soda 
lye  and  ammonia. — (Both  very  often  come  in  contact  with  rubber.)  4.  Colza  oil. 
5.  Mineral  lubricating  oil,  as  well  as  these  oils  mixed  with  tallow  in  definite  pro- 
portions. These  substances  frequently  exert  a  destructive  action  on  pump,  etc., 
valves,  upon  pipe  joints,  etc.  6.  Coal  gas. — (We  have  already  shown  the  effect 
of  this  gas  on  rubber  tubing.)  7.  Physical  tests. — The  physical  and  mechanical 
tests  were  made  with  the  object  of  determining — 

1.  The  modulus  of  load  (module  de  charge).1  2.  The  coefficient  of  resistance. 
3.  The  limit  of  elasticity.  4.  The  modifications  in  shape  under  the  influence  of 
strong  pressure.  5.  The  modifications  in  shape  under  the  influence  of  repeated 
blows.  6.  The  effect  of  prolonged  heat.  7.  The  variation  in  the  insulating  power. 

All  the  samples  were  submitted  to  the  following  tests  : — 

1.  Sulphuric  acid   test. — In  a  solution   of   sulphuric  acid  of   specific  gravity 
1-1562  (say  31°  Twaddell),  which  is  equivalent  to  27'5  per  cent.  H2SO4,  there 
were  macerated  after  previous  weighing  in  the  cold  the  types  I.  to  XVIII.  for 
twenty  days,  the  types  XIX.  to  XXXII.  for  ten  days.     Taken  out  of  the  steep 
and  conveniently  dried,  they  were  again  weighed,  care  being  taken  to  note  the 
modifications  of  the  normal  texture  which  might  be  presented. 

2.  Acetic  acid  test. — The  acetic  acid   used   had   a  density  of  1'0584  (11° '68 
Twaddell)  =  46 '5  per  cent.  C2H4O2.     Contact  in  the  cold  only  lasted  three  days, 
the  action  of  the  acid  manifesting  itself  much  more  rapidly. 

3.  Soda   lye  and  ammonia   test. — Soda   lye,    of  specific   gravity  1'3084  (say 
62°  Twaddell),  equivalent  to  21 '5  per  cent,  of  NaHO,  was  left  in  contact  for  three 
days.     Not  only  was  the  weight  before  and  after  the  operation  taken,  but  also  the 
initial  and  final  densities  of  the  samples  tested,  and  the  same  was  done  in  the  case 
of  the  acetic  acid  and  ammonia  tests.     The  ammonia  used  (specific  gravity  0'9775, 
equivalent  to  6  per  cent.  NH3)  was  left  in  contact  for  four  days. 

Drying  the  samples  after  the  tests. — The  samples  Nos.  I.  to  XVIII.  were 
washed  and  dried  for  six  hours  at  a  temperature  of  100°  C.  (212°  F.).  Nos.  XIX. 
to  XXXII.  were  exposed  when  they  came  out  of  the  bath  for  forty-eight  hours  to 
the  open  air,  and  then  dried  for  half  an  hour  at  100°  C.  (212°  F.). 

4.  Colza  oil  test. — The  colza  oil  had  a  density  of  0'9102.2     After  five  days' 
contact,  the  volume  of  the  sample  was  determined  before  and  after  the  experiment, 
as  well  as  in  the  case  of  the  two  following  tests. 

5.  Lubricating  mineral  oil. — Density  =  0'8991,  five    days     of  contact.     5a. 
Mixture  of  90  per  cent,  mineral  oil  and  10  per  cent,  talloiv  was  put  in  contact 
with  the  samples  for  five  days  at  a  temperature  of  100°  C.  (212°  F.).     6.   Coal 
gas  test. — In  the  test  with  coal  gas,  the  authors  placed  the  sample  in  the  gas  pipe 
between  the  burner  and  the  tap;  the  jet  was  lit,  the  experiment  lasted  twenty 
consecutive  days,  so  that  the  sample  was  in  constant  contact  with  the  gaseous 
current.     The  determinations  were   made  by  weighing.     7.  Physical  tests. — For 
alterations  in  volume,    the  micrometer  was  used  so  as  to  determine  alterations  to 
the  extent  of  —-$  of  a  millimetre.     To  obtain  the  modulus  of  elasticity  and  the 
limit  of  elasticity,  etc.,  use  was  made  of  a  special  apparatus,  with  more  than  one 

1  ?  Modulus  of  elasticity.  — TR. 

2  If  this  gravity  were  taken  at  the  ordinary  temperature,  it  is  remarkably  low  for  pure 
colza  oil. 


CONSIDERATIONS   ON   MINERALISATION,    ETC. 


point  of  resemhlanee  to  the  sipparatn>  described  l.y  M.  St.-u.irt.  Dinietution*  of 
samjilt'x  ti'xtf<(  -Alt<r<tti»nx  in  tli'ifx  ////-/•/  ///V.VX///V.  — The  samples  had  earh  ;i 
siijMTtieie.N  of  ()•()•_'  metre  long,  <)•()< ).~)  metre  \\  ide,  and  O'OOJ  metre  thiek.  The 
alterations  iii  shape  under  great  pressure  were  studied  \sitli  the  apparatus  used 
to  test  building  materials  in  tin-  S\\is<  Federal  Polyterhnie.  Each  compression 
equivalent  to  4900  kilogrammes  on  a  sample  «\  \"2  centimetre  for  one  minute; 
the  variable  thickness  of  tin-  sample  was  controlled  before  and  after  each  test  by 
the  micrometer  in  every  direction,  and  it  could  thus  easily  l»e  determined  \\hetlier 
the  deformation  took  place  uniformly  in  all  directions.  As  the  edges  were 
generally  more  swollen  than  the  centre,  the  thickness  of  the  centre,  of  tin- 
and  tin-  distance  Let  \\eeii  thi'  two  furthest  .-ides  uvre  taken.  The  alteration*  in 
shape  under  the  action  of  repeated  bh»\\>  \\cn-  made  with  the  apparatn>  of  the 
Xnrieh  Polytechnic.  One  square  centimetre  of  a  thickncHH  determined  U-forehand 
was  put  under  the  action  of  a  hammer  of  "2  kilogrammes  in  weight  (say  1't  IK), 
with  a  fall  of  0'25  metre  (say  10  inches),  and  underwent  fifty  blows  each  time. 
Maximum  compression  for  one  minute,  4900  kilogrammes  (10,780  lb.).  The 
deformation  was  not  uniform  as  in  the  preceding,  but  showed  excentric  undulation ; 
they  were  measured  as  in  the  foregoing.  The  deformation  undergone  by  energetic 
compression  is  shown  in  A,  Fig.  93,  and  in  B  that  undergone  under  the  action  of 
fifty  repeated  blows. 

TABLE  LXIV. — COMPARATIVE  TRIAL  OF  TWO  SAMPLES  OF  INDIARUBBKB, 
STROM  ;   PRESSURE,  TO  DETERMINE  ALTERATION  IN  SHAPE. 


Type. 

Initial  Thickness. 

Thickness  of  the 
Extreme  Sides 
after  the  Test. 

Thickness  of  the 
Centre. 

Displacement  »( 
the  Furthest 
Edges. 

I. 
III.    . 

Millimetres. 
0-95 
1-08 

Millimetres. 
1-18, 
1*16 

Millimetres. 
0-93 

roi 

Millimetres. 
9-00 

8-25 

No.  I.  is  therefore  more  resistant  than  No.  III. 

TABLE  LXV. — RESULTS  OF  TEST  OF  Two  SAMPLES  UNDER  REPEATED 
BLOWS  OF  THE  HAMMER  TO  DETERMINE  ALTERATION  IN  SH  M  i 


Type. 

Initial  Thickness. 

Thickness  of  the 
Extreme  Sides 
after  the  Test. 

Thickness  of  the 
Centre. 

Displacement  of 
the  Kurthest 
Edges. 

I.   , 
III.   . 

Millimetres. 
0-95 

no 

Millimetres. 
1-54 
1-40 

Millimetres. 
0-71 
0-90 

Millimetres. 

•_'•:;. 

5-00 

No.  I.  therefore  does  not  stand  repeated  blows  of  the  hammer  so  well. 

Action  of  heat. — To  test  the  action  of  prolonged  heat  the  samples  wen-  plaeed 
in  an  oven  with  a  glass  door.  Heat  was  applied  slowly,  so  as  to  get  an  increase 
of  temperature  of  10°  C.  (18°  F.)  every  half-hour  on  each  occasion.  All  the 
accidents  which  ini^ht  happen  could  thus  be  observed  until  the  final  temi»erature, 
i.e.  150°  C.  (302°  F.),  was  reached. 

Skctncal  resistance  test. — Finally,  Weber's  electrometer  (see  Mascart'>  M 
d' filectricite  Statique)  was  used  to  determine  the  variations  in  the  insulating 
power  of  the  samples.  Previous  to  the  test  they  were  placed  in  a  drying  oven  for 
half  an  hour,  to  remove  all  traers  of  moisture.  The  electrometer  at  rest  marked 
500°  charged  before  each  test,  the  needle  oscillated  u^m  L'b'O0.  From  time  t«. 
time  the  apparatus  \\a>  verified  to  make  any  necessary  corrections.  The  test 
was  made  during  the  day  at  a  temperature  of  12°  C. 


238 


INDIARUBBER 


Remarks  on  Heinzerling  and  PahVs  experiments. — It  is  unnecessary  to  follow 
the  deductions  which  Heinzerling  and  Pahl  draw  from  each  of  their  experiments. 
The  Tables  and  their  indications  are  sufficient,  and  readers  can  themselves  draw 
the  appropriate  deduction  from  the  facts  given.  Attention  is  drawn  to  the  experi- 
ments on  commercial  articles,  as  delivered  by  the  factory,  Table  B,  in  which  three 
species  of  vulcanising  agents,  S.  metal,  pasta  (paste),  and  mixture,  have  replaced 
sulphur,  in  whole  or  in  part,  as  a  vulcanising  agent.  These  products,  the 
composition  of  which  the  vendors  always  keep  secret,  yield,  in  the  majority  of 
cases,  inferior  products,  the  defects  of  which  only  become  manifest  after  a  certain 
time.  Heinzerling  and  Pahl  tried  to  ascertain  the  composition  of  these  three 
bodies,  and  they  think  they  recognised — 1.  Sulphur  and  the  different  compounds 
of  ultramarine  blue.  2.  Paraffin,  or  a  resin  to  which  rubber  waste  has  been 
added,  the  whole  dissolved  in  spirits  of  turpentine,  and  mixed  with  plaster,  lime, 
and  magnesia.  3.  Terebenthine  (spirits  of  turpentine),  acting  as  a  vehicle  for  the 
regenerated  rubber. 

The  conclusions  of  this  long  and  important  work  are : — 

1.  All  organic  and  mineral  substances  added  to  supple  rubber  diminish  its 
elasticity.  Ten  per  cent,  of  sulphur  as  a  vulcanising  agent  gives  the  best  results 
so  far  as  elasticity  is  concerned.  On  the  other  hand,  certain  organic  additions, 
such  as  terebenthine,  colophony,  bitumen,  as  well  as  certain  mineral  additions, 
such  as  mercury  sulphide,  slaked  lime,  far  from  injuring  the  elasticity,  sometimes 
even  accentuate  it.  2.  The  modulus  of  load  (module  de  charge)  is  increased  in 

A  B 


\ 


FIG.  93. — Deformation  of  pressed  rubber. 


supple  rubber  by  the  addition  to  a  certain  extent  of  bitumen,  chalk,  fluor  spar, 
oxide  of  zinc,  and  especially  calcined  magnesia.  The  modulus  of  ebonite  is 
increased  by  the  addition  of  mercury  sulphide,  as  well  as  by  more  prolonged 
vulcanisation  and  a  greater  dose  of  sulphur.  All  other  mineral  additions,  lead 
oxide,  slaked  lime,  and  all  organic  additions,  with  exception  of  bitumen  in  small 
quantities,  can  only  diminish  the  modulus  of  elasticity  of  ebonite.  3.  Mineral 
additions,  such  as  zinc  oxide,  lead  oxide,  chalk,  magnesia,  slaked  lime,  bitumen,  and 
glycerine,  accentuate  the  coefficient  of  electrical  resistance  of  pliant  indiarubber. 
The  coefficient  becomes  much  higher  in  ebonite  by  the  use  of  a  large  quantity  of 
bitumen,  terebenthine,  and  rosin,  to  which  lime  or  magnesia  has  been  added,  so 
long  as  certain  limits  are  not  exceeded.  It  is  the  same  with  vermilion.  But  the 
tensile  strength  of  rubber  is  perceptibly  diminished  by  the  intervention  of 
vulcanised  oils,  turpentine,  and  paraffin.  4.  Pure  rubber,  containing  sulphur,  has 
wrongly  been  considered  as  the  best  insulator  :  a  whole  series  of  mixtures  of  rubber 
with  certain  metallic  oxides,  zinc  oxide,  slaked  lime,  calcined  magnesia  (in  small  pro- 
portion), antimony  sulphide,  as  well  as  all  the  organic  additions  commonly  used ; 
oils  vulcanised  by  sulphur,  those  vulcanised  in  the  cold  by  sulphur  chloride  (in 
very  moderate  proportions),  terebenthine,  rosin,  paraffin,  yield,  so  far  as  insulating 
power  is  concerned,  a  far  better  result  than  pure  vulcanised  rubber.  The  insulating 
power  of  pliant  rubber  containing  paraffin  is  the  greatest.  Vermilion  and  lead 
oxide,  on  the  other  hand,  diminish  the  dielectric  properties  of  rubber.  It  is 
the  same  with  an  excess  of  magnesia.  Rubber,  vulcanised  in  the  cold,  gives  the 
worst  results  in  this  respect. 


CONSIDERATIONS   ON   MINERALISATION,    ETC. 

."").  All  mixtures  containing  organic  additions  gi\r  oil'  fumes  if  heated  to  130° 
t..  1")0  c.  (L'tit;  t..  :;()•_'  I'.i;  such  a  mi\nuv  is  therefore  to  i»  .i\.,idrd  if  the 
rubber  is  liable  to  be  e\p..>--d  to  a  rather  high  temperature.  The  other  mixtam 
generally  behase  \\.-ll  in  tin-  resp 

r..  All  the  mixtmvs  containing  chalk,  tluor  spar,  lead  oxide,  zinc  oxide, 
an-  stn.ngly  JU'ted  on  by  sulphuric  ari«|,  as  \\ell  as  by  acetic  acid,  and  tin-  \\. 
regularly  increases,  either  because  there  is  (urination  of  insoluble  salts,  like  sulphate 
of  lit i ic,  or  also  of  basic  salts  (basic  acetates  ..t  x.inc  ami  lead).  The  destructi\e 
action  of  oils  is  diminished,  especially  by  the  addition  of  zinc  oxide  and  lead  oxide. 
The  other  inorganic  substances  added  are  less  efficacious.  Alkali«->  and  coal  ga^  do 
not  altn-  the  ditleivnt  inixtuivs  studied  to  such  an  extent  as  to  enable  any  definite 
conclusion  to  be  drawn.  Finally,  the  organic  addition,  employed  ;i|j  t.-nd  to 
preserve  tin-  substance,  more  or  less,  from  the  corrosive  action  of  acids. 

7.  The  generality  of  rubber  compounds  which  have  been  mixed  with  mineral 
matters  harden  and  become  brittle  after  a  more  or  less  prolonged  period  of  storage. 
They  are  then  less  resistant  to  mechanical  strains.  So  far  as  insulating  capacity 
is  concerned,  they  do  not  appear  to  suffer  any  loss. 

s.    Kbonite  has  not  such  an  extensive  use  as  supple  rubber.      It  is,  hou 
used  in  making  chemical  apparatus  and  in  the  manufacture  of  dielectrics.      In  the 
first  case  it  should  not  contain   mineral  additions.     In  the  second  case  it  gains  b\ 
being  associated  with  rosin  and  paraffin. 

In  order  to  terminate  this  investigation  of  the  methods  of  analysis  adopted, 
the  following  are  the  requirements  to  be  exacted  from  manufactured  rubber, 
according  to  Dr.  Lobry  de  Bruyn's  sjxjcifications  (Chem.  Zeitung,  1894,  p.  329). 

The  tests  to  which  it  should  be  submitted  are — 

1.  The  loss  in  weight  on  extraction  with  alcoholic  potash. — Tills  weight  should 
not  exceed  8  per  cent,  of  the  organic  substance  (deduction  made  for  ash  and 
sulphur).  The  experiment  is  made  on  5  grammes  of  rubber  reduced  to  a  thin 
sheet;  it  is  heated  for  six  hours  in  a  vessel  attached  to  a  reflux  condenser,  with 
50  cubic  centimetres  of  a  6  per  cent,  solution  of  pure  caustic  soda  in  96  \m  cent, 
alcohol.  The  alcoholic  extract  should  not  contain  anything  more  than  sulphur 
and  resins ;  no  soaps.  The  loss  of  weight  is  determined  by  washing  the  extraction 
residue,  letting  it  stand  for  twenty-four  hours  in  water,  collecting  and  drying  on  a 
tared  filter  at  100°  C. 

i'.  The  effect  of  dry  /teat. — Two  grammes  of  the  sample  to  be  tested,  cut  into 
thin  strips,  are  heated  in  an  oven  to  135°  C.  (275°  F.)  for  two  hours.  After  this 
treatment,  the  rubber  ought  to  have  maintained  all  its  original  projierties  intact. 
It  ought  to  have  lost,  at  the  most,  1 J  per  cent,  in  weight. 

3.  I'tie  effect  of  superheated  water  (under pressure). — A  piece  of  known  weight  is 
heated  for  four  hours,  at  a  temj>eratiire  of  170°  C.  (338°  F.),  dipping  into  the  \\atn-. 
The  properties  of  the  rubber  thus  treated  ought  not  to  be  j>erceptibly  altered. 

4.  Ash. — Calcine  J  to  1  gramme  with  care,  \\ith  a  very  low  flame  at  tiiM. 

It  will  be  noticed  that  Lobry  de  Bruyn  does  not  impose  any  maximum  of 
sulphur.  He  in  fact  found  rubbers  with  T  and  7'3  jier  cent,  of  sulphur  as 
satisfactory  as  those  which  contained  3  to  4  per  cent.  On  the  other  hand,  the 
limit  tixed  for  the  loss  on  extraction  by  alcoholic  potash,  S  per  cent.,  prevents  the 
addition  of  too  large  an  excess  of  sulphur.  He  limits  himself  to  requiring  that 
the  rubbers  stand  the  above  tests  well.  He  allows  the  addition  of  mineral 
substances,  in  greater  or  less  proportion,  according  to  the  purposes  for  which  they 
are  intended  to  be  used.  He  has  had  through  his  hands  excellent  sorts  containing 
25  per  cent,  and  above  that  of  mineral  substances.  Amongst  these  it  seems  to  him 
that,  weight  for  weight,  zinc  oxide  alters  the  properties  of  rubber  to  the  least  extent. 
In  regard  to  red  rubbers,  it  might  be  stipulated  that  they  be  coloured  exclusively 
with  antimony  sulphide  and  not  with  ochres.  Venetian  red,  and  analogous 
pigments ;  it  is  a  well-known  fact  that  the  former  last  much  longer  than  the  latter. 

The  Tables  giving  the  results  of  Heinzerling  and  Pahl's  experiments  now 
follow  : — 


240 


INDIARUBBER 


TABLE  LXVL— RESULTS  OBTAINED  BY  HEINZERLING  AND  PAHL 

CHEMICAL 


A.  SAMPLES  PREPARKD  FROM  TUB  AUTHORS'  DATA. 

! 

Action 
of 
Sulphuric 
Acid. 

Consecutive 
Number  of 
Sample. 

Para  Rubber. 

M 

Qualities  and  Nature  of  the 
Substances  added. 

Density 
before 
Testing. 

ce 

Altera- 
tion in 
Weight. 

I 

Per  Cent. 
90 

85 
75 
80 
50 
10 

80 
50 
10 
50 
10 
50 

10 

Could 
50 

30 
50 

30 

87 
87 
75 
65 
Could 
Could 
75 

65 
85 
80 
80 
70 
60 

30 

English 
sheet 
vulcan- 
ised 
in  the 
cold. 

PerCent. 
10 

5 
5 
10 
10 
10 

»{ 

»{ 

io{ 

»{ 

»{ 

M 
»{ 

not  be 
10 

10 
10 

10 

10 
JO 

10 
10 
not  be 
not  be 
10 

10 
10 
10 
10 
10 
10 

10 

)• 

0 

10 
20 
10 
40 
80 
5 
5 
20 
20 
40 
40 
20 
20 
40 
40 
20 
20 
40 
40 
perform 
40 

60 
40 

60 

3 
3 
15 
25 

perform 
perform 
15 

25 
5 
10 
10 
20 
30 

60 

Antimony  sulphide. 
Antimony  sulphide. 
Zinc  oxide. 
Zinc  oxide. 
Zinc  oxide. 
Zinc  oxide. 
Chalk. 
Zinc  oxide. 
Chalk. 
Zinc  oxide. 
Chalk. 
Zinc  oxide. 
Calcium  Huoride. 
Zinc  oxide. 
Calcium  fluoride. 
Zinc  oxide. 
Lead  oxide. 
Zinc  oxide. 
Lead  oxide, 
ed. 
Vulcanised  oil. 

Vulcanised  oil. 
Oil  treated  with  chloride 
of  sulphur. 
Oil  treated  with  chloride 
of  sulphur. 
Calcined  magnesia. 
Slaked  lime. 
Paraffin. 
Paraffin, 
ed. 
ed. 
Terebenthine. 

Terebenthine. 
Glycerine. 
Glycerine. 
Bitumen. 
Bitumen. 
Reclaimed        rubber 
(powder). 
Reclaimed       rubber 
(powder). 

0-999 

1-070 
1-101 
1-087 
1-283 
1-514 

1-184 
1-255 
1-452 
1-295 
1-502 
1-340 
1-569 

1  -053 

1-052 
1-054 

1-031 

1-130 
1-027 
1-075 
1-041 

1-030 

1-065 
1-062 
'1-060 
1-080 
1-085 
0-101 

1-101 
0-925 

The  samples  in  this  series  were  vulcanised  for  one  hour  at  135°  to  138°  C.  (275°  to  280  '4°  F.), 
under  a  pressure  of  3  to  3£  atmospheres. 

PerCent. 
-r  4-259 

-  3-099 
-  3-521 
-  3-274 
-  2-074 
-  1-810 

-  2-930 
-  2-280 
-  1-802 
-  1-464 
-  1-527 
-  1-864 
-  1-406 

-  4:081 

-  2-473 
-  6-076 

-  6-306 

-  0-932 
-  0-924 
-  4-806 
-  3-273 

-  3:367 

-  3-582 
-  5-921 
-  6-571 
-  3-686 
-  2-421 
-  2-336 

-  3-889 
-f-  1-344 

II  

Ill  
IV  

v 

VI  

VII  
VIII.       .     .     . 
IX  

X  . 

XI  

XII  

XIII  

XIV  
XV    .    .    . 

XVI  
XVII.     .     .     . 

XVIII.   .    .     . 
XIX  

xx 

XXI  
XXII.     .     .     . 
XXIII.   .     .     . 
XXIV.    .     .     . 
XXV.      .     .     . 

XXVI.    .     .     . 

xxvi  r.  .    .    . 

XXVIII.      .     . 
XXIX.    .     .     . 
XXX.     .     .     . 
XXXI.    .     .     . 

XXXII.  .     .     . 
IA  

Explanation  of  the  Signs  :  +  Augmentation  ; 


CONSIDERATIONS  ON   MINERALISATION,   ETC.          241 


IN  THEIR  EXPERIMENTS  ON  VULCANISED  RUIJHKR  AND  EBONITE. 

Kxri  KIM! 


Mixture 

A»«  t 

Art  ion  of  Acetic 
Acid. 

Action  »M 
Soda  I,ye. 

A.  tion  of 
'Ammonia. 

Action 

r,,l/..i«>,l. 

Hot-Mi 
LubrtoaJ 

Mineral  oil 

-.,..  r 

\            :, 

n:  MhMl 
log  Qei 

Tallow  10 

I-  r  •  lBt 

Alteration.  Alteration    Alu-ration 

Alt.r.-Ui.m 

Altera- 

Altera-    Alteration 

Alteration 

Attention 

Alteration 

in                  in                 in 

in 

tion  in 

lion  in 

in 

in 

in 

in 

Volume. 

Weight 

Volumr. 

Weight. 

WHOM, 

\\Y,,ht. 

Volume. 

Volume. 

Volume. 

Weight. 

IVMVnt. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

PerCenU 

iv,  CM 

2*012 

r     0-932 

_ 

-r     4-354 

-r    0-727 

+  23-214 

+  42718 

entirely 

-f    9-765 

dteofod, 

+    2-985 

+     2-097 



-r     4-354 

_ 

-r    0-974 

+  20-617 

.  80-604 

+  63-846 

MM 

+    3*846 

+     3-048 

_ 

-J-     4-271 

_ 

ii-  •>'.'»> 

.    2S--1-J1 

+  61-485 

+  34-616  +    7-561 

+    4-854 

+  29-132 

_ 

_ 

+    0-326 

.   '>$->\-> 

+  39-423 

.    LM-7VJ    -    11  -07;, 

+  28-155 

.  i  :,.-{•«  Kir, 

_ 

I    -0-084 

_ 

-r    0-314 

+  32-110 

+  43*19 

+  58-878 

10086 

+  116-950 

- 

-r     0-087 

_ 

-r    0-779 

•    17-27-' 

+  36-440 

+  78-947 

+    7-674 

+    5-357 

+  30-887 

- 

+     2-824 

- 

+    0-629 

+  24-137 

+  40-178 

86*786 

+  10-863 

+  28-828 

+  131-899 

- 

+     2-059 

- 

+    0-856 

+  37-247 

+  46-296 

+  77-570 

+    7-870 

;   20484 

+  160-09? 

+     0-892 

:     i  •  i-j-j 

— 

-r    0-507 

+  27-193 

+  35-593 

66*881 

+    5-821 

+  17-475 

82-816 

+     1-000 

-r     3-348 

- 

-r    0-455 

+  28-853 

+  40-384 

+  51-928 

+    8-549 

+  31-730 

+  124-539 

- 

+     2-160 

— 

-r    0-512 

+  28-571 

+  41-121 

+  65-048 

+    1-462 

+  12-765 

+  78-542 

— 

-r     1-150 

_ 

+    0-011 

+  37-894 

+  38-613 

58-788 

+  10-043 

;   23-711 

+  77-411 

- 

-r     0-282 

- 

-r    0-388 

+  28-712 

+  30-000 

+  47-916 

+    8-695 

_ 

+    0-560 

-r     1-388 

+     5745 

-r    0787 

+  21*428 

+  60714 

entirely 

+  11793 

dissolved. 

_ 

+    2-180 

_ 

-r     4-965 

-r  3-571 

-r    0-744 

.  20*889 

+  32-773 

+  14-047 

+    1709 

+     6-373 

-r    7-017 

-r     9-723 

-r  1724 

-r    2-147 

+  11-111 

+  44-545 

ii 

+    7-574 

+    2-970 

+     8-695 

+    9-708 

-f     9-658 

-r  1-941 

-r    1-649 

+  14-423 

+  55-445 

n 

+    7-987 

+    4-231 

+  18718 

-r     1-321 

-r    0-247 

+    6-250 

+  36-440 

+  10-143 

•       1-J7:! 

-r    0-847 

-r     6-569 



+    0-327 

+  18-487 

2'.'75'J 

ii 

+  10-043 

+    5-063 

-r    0-354 

-j-  10-588 

•f     5-602 

—  . 

-r     1722 

+  23-595 

+  43*760 

•   12*758 

+    2-197 

-r     0-674 

-r    7-692 

•r    4-847 

- 

-r    2-882 

+  10-000 

+  35-781 

» 

+  13-581 

- 

+    2732 

_ 

-r     5*-210 

_ 

+    0-239 

+  20-491 

+  39*603 

i-ntiri-ly 
•*•"*•* 

+  10:368 



+    6-442 

_ 

-r     5-961 

_ 

+    0-496 

+  26732 

+  31-460 

+  11-382 

— 

+     0-420 

-r     5-940 

-f     7-628 

_ 

.     <)•:;(  is 

+  23-904 

ls-'_'l  l 

••• 

+  11-618 

_ 

+     2-400 

-:-     :{-84»J 

:     7  •'.".••-' 

_ 

+    3-909 

+  21-551 

+  45-794 

+    8-905 

+    1-980 

+     0-650 

+     4-382 

_ 

+    0-121 

+  10-434 

+  45714 

.    7.  ;•('.>«! 

+  12  514 

:     <••<;<  17 

_ 

-:-     3-425 



+    0-225 

+  17-647 

+  40-740 

ft-TW 

-    11-.M- 

_ 

-f    2-849 

_ 

+    0-718 

+  14-160 

+  53-846 

entirely 

+  10-810 



lissolved. 

+    1-769 

i      0-72D 

-r    0-833 

-r    3-473 

+  0-869 

-r    2-031 

+  15-789 

+  47-000 

„       U    5-807 

- 

- 

- 

- 

- 

+    1-592 

+  28-461 

+  51-198 

ii 

+  15-121 

diminution  ;  -  no  change. 

16 


242 


INDIARUBBER 


TABLE  LXVlA.— RESULTS  OBTAINED  BY  HEINZERLING  AND  PAHL 

CHEMICAL 


B.  COMMERCIAL  GOODS  THE  COMPOSITION  OF  WHICH  WAS  GIVEN  BY 

- 

THE  FACTORY. 

'if 

§.<?  . 

=  | 

Consecutive 
Number  of 
Sample. 

Rubber. 

1 
1 

Quantities  and  Nature  of  the 
Substances  added. 

Density  given  by 
the  Factory 
after 
Manufacture. 

Density  found 
2*  Years 

aftenvanls. 

Modules  of  Resist 
Grammes  for  1  S 
Millimetre. 

-Modulus  of  Lo£ 
Grammes  for  1  S 
.Millimetre. 

Pr.  Ct. 

Pr.  Ct. 

Pr.  Ct. 

1 

91 

9 

0 

0-990 

0-999 

33-5 

201 

2 

82 

8 

10 

Chalk. 

MOO 

1-111 

40 

230 

3 

43 

M 

7 
45 

Vulcanised  oil. 
Oxide  of  zinc. 

1-400 

1-490 

21 

349 

4 

47 

M 

27 
19 

Chalk. 
Zinc  oxide. 

1-400 

1-500 

38-5 

124 

5 

66 

j 

16 
9 

Antimony  sulphide. 
Chalk. 

1-200 

1-304 

43 

173 

( 

9 

Zinc  oxide. 

6 

70 

7 

23 

Chalk. 

1-465 

1-222 

15 

86 

7 

92 

0 

8 

Metal  (1). 

0-999 

1-111 

16 

25 

8 

71 

7  1 

16 
6 

Chalk. 
Zinc  oxide. 

1-450 

1-660 

31-5 

63 

r 

6 

Vulcanised  oil. 

9 

58 

oj 

30 
5 

Chalk. 
Metal  (1). 

1-215 

1-330 

12 

33 

^ 

1 

Pasta  (2). 

c 

4 

Vulcanised  oil. 

10 

36 

6J 

27 

Chalk. 

1-550 

1-720 

37-5 

183 

1 

27 

Oxide  of  zinc. 

( 

6 

Vulcanised  oil. 

11 

31 

6 

15 
40 

Chalk. 
Oxide  of  zinc. 

1-600 

1-806 

36 

145 

I 

2 

Pasta  (2). 

4 

Vulcanised  oil. 

10 

Chalk. 

3 

Zinc  oxide. 

12 

39 

0  - 

3 

Metal  (1). 

1-650 

1-920 

24 

81 

i 

Paraffin. 

8 

Fluor  spar.    .  . 
Mixture  (3).  .. 

!' 

8 

Antimony  .sulphide. 

6 

Vulcanised  oil. 

13 

21 

52 

Chalk. 
Paraffin. 

not  given 
by  the 
factory. 

1-760 

41-5 

116 

Pasta. 

. 

Regenerated. 

( 

40 

Chalk. 

14 

30 

o 

25 
3 

Zinc  oxide. 
Metal  (1). 

id. 

1-803 

38-5 

161 

1 

2 

Pasta  (2). 

{" 

18 

Chalk. 

3 

Metal  (1). 

15 

30 

2 

Pasta  (2). 

id. 

2-041 

22-5 

61 

35 

Fluor  spar. 

12 

Lead  oxide. 

Explanation  of  the  Signs  :  +  Augmentation 


CONSIDERATIONS   ON    MINERALISATION,    ETC. 


243 


IN  TIIKII;  EXPERIMENTS  "N  VULCANISED  i;i  I'l'.KK  AND  Kr.'»\m. 


• 

A   •  M 

of  a 

Action  of  Acetic 

A.  -lion  ..f  Caustic 
l.\e. 

Action  of 
Ammonia. 

Action             of 

1  !        1.  nl.  neat 

• 
•    iicta 

inu  oil. 

)..    r    •   •    ':' 

Alteration 

Alteration 

Altera- 

Alteration 

Alteration 

Alteration 

Alteration 

Alteration 

Alteration 

\:  ••  i  .-     • 

in 

in 

tion  in 

in 

in 

in 

in 

in 

in 

Volume. 

UYiuht. 

Volume. 

Weight 

Volume-. 

Weight 

Volume. 

Volume. 

Volume. 

PerCent 

IVr(Vnt. 

IVr  Tent. 

PerCent 

Per  Cent. 

Per  Cent. 

Per  Cent 

Per  Cent. 

ftrOtafc, 

Per  Cent. 

4-    0-711 

2-640 

_ 

4    1-934 

_ 

4    1-503 

4  18-045    f  36-641 

i   19-083  4  37-688 

- 

4    2-332 

4    3-937 

4    3-357 

4    6-666  4  23-664 

re-en 

4  12-139 

4  51-319 

- 

-:-    3-058 

+    0-402 

4    4-309 

4  47-663   4- 

-I-.-:.;. 

4    6-027 

4  46-216 

.  M  •;<.'<) 

— 

-r    1-847 

4    4-001 

4    4-722 

4-    3-703 

4  10-077 

.  56-1M 

4    5-596 

4  42-975 

4  90-209 

- 

-r    0-564 

4  16-071 

4    2-877 

4-    6-140 

4  12-931 

4    7-692 

4    8-271 

4  37-190 

4-  72-947 



4-    1-534 

+    5-660 

5-600 

4-    5-737 

4  12-068 

4  18-333 

4    8-059 

i       L'-'JOf) 

4  26-263 

:     1-170 

4    1-266 

4  11-450 

4  23-550 

4    8-450 

434-677 

4    8-413 

4    9-278 

4  53-321 

- 

4-    1-600 

4  15-217 

4  17-652 

4-    6-382 

4  18-556 

4  54-347 

4    4-836 

4    7-627 

4  78-623 

- 

-=-    4-650 

4  10-250 

4  22-405 

- 

4    5-042 

4  13-559 

4    4-133 

4-  19-841 

4  11-298 

- 

4  19-083 

+    6-299 

4    6-863 

4  27-480 

4  30-708 

4  81-679 

4    4494 

4  21-481 

,13,,, 

-r    0-699 

4  20-551 

4    4-347 

+    6-238 

4  20-595 

4  21-428 

4  64-492 

4    5-069 

un- 

4  15-126 

4  31-422 

-r  14-724 

4    6-009 

4  27-168 

•    "2'2-ll-'{ 

inc.-iMir- 

.'•••*;  ; 

able. 

f  17-35f> 

4-  21-078 

- 

4    1-601 

4    9-090 

4    8-391 

t  15-125 

L4-8W 

4  47-580 

4    4-020 

:     ,1-700 

4  15-703 

_ 

4    1-655 

4  10-156 

4    8-665 

4    7-031 

4    8-064 

433-W3 

4    3-837 

•  -ji  •;.:•> 

4  15-228 

4    0-163 

4    6-666 

•     6-171 

4  10-687 

4  ii-t>-'; 

r  27-480 

..    3-12-2 

~  diminution  ;    -  no  chain:.'. 


244 


INDIARUBBER 


TABLE  LX VII.— RESULTS  OBTAINED  BY  HEINZERLING  ANJ)  PAHL 

PHYSICAL 


A.  SAMPLES  PREPARED  FROM  THE  AUTHORS'  DATA. 

=  1 

•*§ 

£ 

Ilg3 

?  a1 

12  B 

• 

LJ 

0 

•2 

pl 

111 

Consecutive 
Number  of 
Sample. 

1 
a 

1 

Quantities  and  Nature  of  the 
Substances  added. 

{! 

8 

j2  <8  5  .  "5  S  5 

1 

i 

"^O 

3° 

Pr.  Ct. 

Pr.  Ct. 

Pr.  Ct. 

I.            ... 

90 

10 

0 

0-999 

48-5 

213 

II.          ... 

85 

5 

10 

Antimony  sulphide. 

1-070 

38 

213 

III.        .     .     . 
IV.         ... 

75 

80 

5 
10 

20 
10 

Antimony  sulphide. 
Zinc  pxide. 

1-101 
1-087 

47-5 
48-5 

259 
427 

V.          ... 

50 

10 

40 

Zinc  oxide. 

1-283 

47-5 

480 

VI.         ... 

10 

10 

80 

Zinc  oxide. 

1-514 

43-5 

543 

VII.      .    .     . 

80 

10- 

5 
5 

Zinc  oxide.                      -\ 
Chalk. 

1-184 

jj 

46 

440 

VIII.    .     .    . 

50 

10- 

20 
20 

Zinc  oxide. 
Chalk. 

1-255 

o 

"3* 

65 

542 

IX  

10 

10- 

40 
40 

Zinc  oxide. 
Chalk. 

1-452 

1 

69 

653 

X  

50 

10- 

20 
20 

Zinc  oxide. 
Calcium  fluoride. 

1-295 

0 

48 

404 

XI  

10 

10  | 

40 
40 

Zinc  oxide. 
Calcium  fluoride. 

1-502 

£1 

77-5 

563 

XII.      .     .    . 

50 

10  | 

20 
20 

Zinc  oxide. 
Lead  oxide. 

1-340 

So 

CO 

31-5 

404 

XIII.     .    .    . 

10 

10  { 

40 

40 

Zinc  oxide. 
Lead  oxide. 

1-569 

31 

352 

XIV.     .     .    . 

Could 

not  be 

execu 

ted. 

0      gj 

... 

XV  

50 

10 

40 

Vulcanised  oil. 

1-053 

^^ 

22-5 

220 

XVI.     .    .     . 

30 

10 

60 

Vulcanised  oil. 

1-052 

11 

22-5 

77 

XVII.  .    .    . 

50 

10 

40 

Oil  treated  with  chloride 

1-054 

rCtfT      ' 

16 

66 

XVIII.  .     .     . 

30 

10 

60 

of  sulphur. 
Oil  treated  with  chloride 

1  031 

p« 

15 

55 

XIX.     .     .    . 

87 

10 

3 

of  sulphur. 
Calcined  magnesia. 

1-130 

ii 

70-5 

427 

XX  

87 

10 

3 

Slaked  lime. 

1-027 

•§  1 

45 

225 

XXI.     .     .     . 

75 

10 

15 

Paraffin. 

1-075 

1  * 

15 

109 

XXII.   .     . 

65 

10 

25 

Paraffin. 

1-041 

»  g 

14 

115 

XXIII..     .     . 

Could 

not  be 

execu 

ted. 

§3  'd 

XXIV.  .     .     . 

Could 

not  be 

execu 

ted. 

i  5 

XXV.    .     .     . 

75 

10 

15 

Terebenthine. 

1-030 

1 

15* 

96 

XXVI.  . 

65 

10 

25 

Terebenthine. 

1-065 

49 

12 

51 

XXVII.     .     . 

85 

10 

5 

Glycerine. 

1-062 

| 

29-5 

376 

XXVIII.    .     , 
XXIX.  .    .     . 

80 
80 

10 
10 

10 
10 

Glycerine. 
Bitumen. 

1-060 
1-080 

3 

25-5 

45 

365 
342 

XXX.    .     .     . 

70 

10 

20 

Bitumen. 

1-085 

1 

67-5 

407 

XXXI.  .     .     . 

90 

10 

30 

Reclaimed         rubber          1-101 

•f. 

29 

178   | 

XXXII.     .     . 

30 

10 

60 

(powder). 
Reclaimed         rubber 

1-101 

1 

25-5 

156 

English 

(powder). 

sheet 

IA  

vulcan- 
ised 

• 

... 

0-925 

38-5 

230 

in  the 

cold. 

CONSIDERATIONS  ON   MINERALISATION,   ETC.          245 


IN  THKIK  I.XPERIMENTS  ON  VULCANISED  RUBBER  AND  EBONITE. 
EXPERIMENTS. 


ii 

Alt 

Deration  of 

Strniiu-  1 

Sli;i|H-  l 

'r«---urv 

mder 

Alton 

K,, 

it  i-  .11  Of 

••"ill,1. 

feajM  . 

l,,«H,.f 

II..I.T 

th. 

1  Mutilating 
Power. 

•S.= 

ll 

It 

lu 

°S£ 

I.I 

ill 

ll 

|E| 

s  j3 

lit 

Afltton  of  Heal. 

JU    *• 

** 

^  = 

Se£ 
s|i 

ill 

||| 

^1 

111 

ill 

ii] 

CfcMtHJ 

is 

I* 

f  SS 

II  s 

!i£ 

•g?s 

r= 

i-l^ 

11 

'S.S 

j|oo.£ 

g  -s 

s 

=  '5 

gco.5 

—  -  -  — 

1100 

0-95 

M8 

0-93 

9-00 

0-95 

1-54 

0-74 

2-75 

117 

Normal 

790 

1-36 

l-is 

1-27 

9-00 

1-31 

1-68 

1-03 

4-60 

12 

850 

1-08 

1-16 

1-01 

8-25 

1-10 

1-40 

0-90 

5-00 

6 

825 

1-01 

1-07 

0-98 

'.  '•.">(> 

1-00 

1-31 

0-82 

1  •.">'• 

171 

725 

1-12 

1-15 

1-10 

9-50 

1-09 

1-40 

0-91 

4-75 

123 

680 

1-17 

1-20 

1-11 

9-50 

1*11 

l-3f> 

0-99 

5-50 

4 

tl 

760 

1-05 

1-15 

1-01 

9-00 

1-05 

1-30 

0-91 

4-25 

4 

„ 

710 

1-09 

1-20 

1-02 

9-00 

1-02 

1-28 

0-90 

4-75 

4 

,, 

665 

1-14 

1-21 

1-03 

9-00 

1-13 

1-56 

0-95 

5-00 

3-5 

,, 

660 

0-98 

1-02 

0-91 

9-00 

1-00 

1-42 

0-82 

4-75 

2 

640 

1-03 

1-07 

0-95 

9-00 

1-09 

1-26 

0-89 

4-50 

3-5 

•  « 

225-7 

490 

0-94 

0-89 

0-85 

8-25 

0-93 

1-15 

0-82 

3-50 

3'  15" 

ii 

220-5 

305 

0-91 

0-84 

0-86 

8-00 

0-91 

1-19 

0-78 

4-00 

3'  45" 

ii 

750 

0-85 

0-96 

0-75 

6-50 

0-78 

1-22 

0-67 

4-75 

"9 

Fumes  if  temper- 

ature be  raised. 

360 

1-19 

unmea.s- 

0-92 

4-25 

M5 

1-21 

0-91 

5-00 

2 

urable. 

600 

0-96 

1-21 

0-84 

5-50 

1-02 

105 

0-73 

3-75 

50 

,, 

455 

1-00 

1-29 

0-91 

unmeas- 

0-94 

0-96 

0-64 

4-50 

222 

ii 

urable. 

3'  30" 

465 

1-04 

1-08 

1-03 

10-00 

1-01 

1-26 

0-91 

4-50 

7'5 

Normal. 

665 

1-23 

1-35 

1-06 

8-50 

1-21 

1-55 

0-96 

3-25 

9-5 

99 

830 

0-91 

1-18 

0-78 

7-50 

1-21 

1-55 

0-96 

3-25 

1 

At  a  higher  tem- 

perature fumes. 

1025 

1-15 

1-20 

1-01 

7-25 

1-11 

1-45 

0-77 

6-75 

0 

" 

... 

825 

1-06 

1-25 

0-97 

8-50 

1-16 

1-54 

1-01 

3-25 

1-5 

At  a  hight-r  ti-m 

peraturv  fumes 

become  i>it«-hy. 

630 
975 

1-02 
1-07 

1-21 
1-41 

0-91 
1-00 

8-50 
7-75 

1-09 
1-03 

1-26 
1-64 

0-89 

4-00 
4-25 

1-5 
1 

At  a  higher  tem- 
perature fumes. 

1050 

1-14 

1-35 

1-03 

8-00 

1-16 

1-92 

0-92 

2-50 

5 

19 

950 

1-25 

1-92 

1-15 

4-50 

1-28 

1-73 

1-06 

375 

2 

Normal. 

876 

1-07 

1-l-J 

0-9f. 

1-08 

1-1!' 

0-90 

2-00 

2 

-j 

650 

1-04 

1-35 

0-91 

2-50 

l-ii-; 

0-91 

2-75 

3-5 

M 

600 

1-25 

Ml 

1-17 

4-50 

1-42 

1-86 

1-08 

4-00 

1-5 

II 

772 

1-38 

1-88 

l  ••_>:. 

10-00 

1-38 

1-56 

1-29 

7-7.-. 

2-22 

ft 

3' 

246 


INDIARUBBER 


TABLE  LXVIU.— RESULTS  OBTAINED  BY  HEINZERLING  AND  PAHL 

PHYSHAL 


B.  COMMERCIAL  GOODS  THE  COMPOSITION  OF  WHICH  WAS  GIVEN  BY 
THE  FACTORY. 

din  Gramim- 
Millimetre. 

nice  in  Grammes 
Millimetre. 

Consecutive 
Number  of 
Sample. 

Rubber. 

a 

"3 
oc 

ek    A 

.  -     - 

Quantities  and  Nature  of  the          -^ 
Substances  added.                      >.EH  'j;  "5 

=     x 
111 

Ul 

1*1 

Io<luli;s  of  loa 
for  1  ,S<|ii;ire 

Jz 
— 

"c  ^ 

I5     1 

0      rt        "' 

I 

Pr.  Ct. 

Pr.Ct 

Pr.Ct 

1 

91 

9 

0 

1    0990 

0999 

33-5 

201 

2 

82 

8 

10 

Chalk.                                    MOO 

1-111 

40 

230 

3 

43 

M 

7 
45 

Vulcanised  oil.                   ;    J^QQ 
Zinc  oxide. 

1-480 

21 

349 

4 

47 

M 

27 
19 

£halk-  .,                     1-400 

Zinc  oxide. 

1-500 

38-o 

124 

5 

66 

16 
9 

Antimony  sulphide. 
Chalk.     '                           ,    1-200 

1-304       -}:; 

173 

I 

9 

Zinc  oxide. 

6 

70 

7 

23 

Chalk.                                    M65 

1-222 

15 

86 

7 

92 

0 

8 

Metal  (1).                              0-999 

1-111       16 

25 

8 

71 

7{ 

16 
6 

Chalk.                                    i.^ 
Zinc  oxide. 

1-660      :5lv) 

63 

{' 

6 

Vulcanised  oil. 

9 

58 

30 
5 

Chalk.                                     i  .01  ? 
Metal  (1). 

1-330 

12 

33 

• 

. 

1 

Pasta  (2). 

4 

Vulcanised  oil. 

10 

36 

6- 

27 

Chalk.                                    1-550 

1-720 

37-5 

183 

l 

27 

Zinc  oxide. 

f 

6 

Vulcanised  oil. 

11 

31 

6{ 

15 

40 

Chalk.                                     j-eoo 
Zinc  oxide. 

1-806 

36 

145 

V 

2 

Pasta  (2). 

4 

Vulcanised  oil. 

10 

Chalk. 

3 

Zinc  oxide. 

12 

39 

0 

3 

Metal  (1).                                1-650        1-920       24 

81 

1 

Paraffin. 

32 

8 

Fluor  spar. 
Mixture  (3).                        ] 

13 

21 

°( 

8 
6 
52 

Antimony  sulphide. 
Vulcanised  oil. 
Chalk.                                  notgiveii 
Paraffin.                                    bY 

1-760 

41-5 

116 

I 

i 

Pasta.                                    factory. 

i 

11 

Regenerated. 

( 

40 

Chalk. 

14 

30 

0 

25 
3 

Zinc  oxide. 
Metal  (1).                                  "/- 

1-903 

38-5 

161 

2 

Pasta  (2). 

r 

18 

Chalk. 

15 

30 

° 

3 
2 
35 

Metal  (1). 
Pasta  (2).                                   ?V7. 
Fluor  spar. 

2041 

22-5 

61 

: 

12 

Lead  oxide. 

Explanation  of  the  Signs  :  +  Augmentation 


CONSIDI. RATIONS   ON    MINERALISATION,    ETC. 
IN  THKIK  KM'KKIMENTS  ON  VULCAMM.D  EtUBBBB  AND  EBONITK. 


Alteration  of  Shape  uml.  i 
strong  Pressure. 

Alt<  i                      i|x-  under 

i:.  |..-:it«-d   HloUHof  Uu- 

Intiilating 

41 

i.iii. 

metres  for  IIHI  Mill 

Initial  Thickness 
in  Millimetres. 

Thickness  of  the 
It-n  Edges 
in  Millimetres. 

Thickness  of  tlu- 
Middle 
in  Millimetres. 

Displacement  of 

Hi--  Extreme  Edges 
in  Millimetres. 

Initial  Thickness 
in  Millimetres. 

ThtofcMHoftlM 

Swollen  Edges 

in  Millimetres. 

Thickness  of  the 
in  Millimetres. 

Displacement  of 
the  Extreme  Edges 
in  Millimetres: 

Constant 

l>.  |.|.  --:,.•   - 

Acti... 

675 

1-36 

1-62 

1-29 

9 

1-42 

2-04 

M8 

2-75 

Normal. 

600 

1-26 

1-75 

1-24 

5-50 

1-32 

1-72 

1-08 

1-50 

,, 

580 

MO 

1  "-7 

1-04 

7-50 

i-ii 

1-48 

1-02 

1-7:. 

At  a  liiuh  ten,- 

IN-niturvghrw 

off  fumes,  and 

tiie  gum   be- 

comes yellow. 

160 

1-18 

1  •'_'."• 

1-04 

5-25 

1-28 

1-42 

1-07 

4-50 

36-5 

Becomes  brink. 

changes  colour. 

235 

MO 

1-20 

1-03 

6-50 

1-09 

1-16 

1-01 

5 

120-5 

Becomes  soft  and 

spoiiL'V  at  150° 
C.  (302°  F.). 

'  190 

1-25 

1-32 

1-16 

7-25 

1-29 

1-36 

1-10 

5-25 

146 

IV.-.ime-,      hanl 

and  brittli*. 

110 

1-21 

1-06 

0-91 

7-50 

1-24 

1-01 

0-90 

6-25 

5 

Becomes      hard 

(12-50) 

and  .still  more 

brittle. 

nr. 

0-39 

0-76 

0-82 

7-50 

0-92 

0-87 

0-75 

7 

221-5 

Intiimesces  and 

(13-25) 

after  4'  15" 

Itecomett  brittle. 

110 

M2 

0-82 

0-87 

9-25 

M5 

Q-86 

0-82 

9-24 

15 

Still  mn  iv  brittle 

(14) 

than  the  pre- 

,-,-,: 

550 

1-29 

1-35 

1-20 

7-75 

1-29 

1-64 

M2 

4 

157 

From  40°  to  50° 

F.).  shrivels  ami 

becomes  brittle. 

310 

1-34 

1-41 

1-27 

6-50 

1-38 

1-46 

1-24 

5-25 

250-5 

Shri\ 

270 

I"'- 

1-21 

1-04 

6-50 

1-24 

1-08 

1-05 

7 

ft? 

Becomes  very  soft. 

(12-50; 

140 

MI; 

0-91 

M8 

6-25 

i-j:; 

1-07 

1-03 

9 

134 

.-s  -jHdiiry 

(12) 

and  brittle  abort 

130°  (266°  F.). 

128 

1  -_7 

0-78 

1-M7 

8-26 

1  -2  1 

1-06 

1-03 

101 

Becomes  brittle. 

UK.", 

(12-50) 

110 

1-31 

0-88 

0-90 

8 

1-32 

1-22 

1-ni 

8-25 

226 

C,        :    •      •      :.jv 

(15-50) 

(12) 

and  brittle.  * 

diminution  ;  -  no  change. 


248 


INDIARUBBER 


TABLE  LXVIIL— RESULTS  OBTAINED  BY  HEINZERLING  AND  PAHL 

1.  CHEMICAL 


C.  SAMPLES  OF  EBONITE  PREPARED  FROM  THE  AUTHORS'  DATA. 

Action 

of 

X 

Sulphuric 

£ 

Acid. 

Consecutive 
Number  of 
Sample. 

Rubber. 

Sulphur. 

Quantities  and  Nature  of  the 
Substances  added. 

Density. 

1 

Alteration 

in 

- 

Weight. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

XXXIII.     .     . 

80 

20 

0 

1-095 

-f     2-028 

XXXIV.     .     . 

60 

20    -| 

10 
10 

Terebenthine.1 
Rosin. 

4-  15-133 

XXXV.      .    .         50 

20    I 

15 
15 

Terebenthine. 
Rosin. 

-f     2-018 

XXXVI.     .     .         60 

20 

20 

Bitumen  of  Judea. 

+  28-531 

XXXVII.  .     .         40 

20 

40 

Bitumen  of  Judea. 

-f     9-504 

XXXVIII.      .         70 

20 

10 

Mercury  sulphide. 

1-177 

-r     3-225 

XXXIX.     .     .         60 

20 

20 

Mercury  sulphide. 

1-384 

+  17-551 

XL  

40 

20-| 

10 
30 

Terebenthine. 
Calcic  hydrate. 

1-275 

-J-     2-603 

XLI.      .     .     . 

10 

2M 

10 
60 

Terebenthine. 
Calcic  hydrate. 

1-311 

-f     7-880 

XLII.    .     .     . 

40 

*\ 

10 
30 

Terebenthine. 
Calcined  magnesia. 

1-203 

-:-     4-203 

XLIII.  .     .     . 

10 

20{ 

10 

60 

Terebenthine. 
Calcined  magnesia. 

1-428 

-r     8-333 

XLIV.  .     .     . 

65 

35 

... 

... 

— 

Explanation  of  the  Signs :  +  Augmentation  ; 

2.  PHYSICAL 


C.  SAMPLES  OF  EBONITE  PREPARED  FROM  THE  AUTHOR'S  DATA. 

_c 

-  d 

o  a 

Its 

—  *"  £ 

Pj 

Remarks. 

PH  £  S 

Consecutive 
Number  of 
Sample. 

Rubber. 

1 

CO 

Quantities  and  Nature  of  the 
Substances  added. 

Density. 

Modulus 
Grammes 
Milli 

Modulus  of 
Grammes 

Milli 

Pr.  Ct. 

Pr.  Ct. 

Pr.  Ct. 

XXXIII.     . 

80 

20 

0 

1-095 

43-5 

105 

XXXIV.      . 

60 

20    j 

10 
10 

Terebenthine 
Rosin. 

15 

142 

XXXV.  .     . 

50 

20    -[ 

15 
15 

Terebenthine. 
Rosin. 

12 

46 

XXXVI.      . 

60 

20 

20 

Bitumen  of  Judea. 

17 

69 

XXXVII.    . 

40 

20 

40 

Bitumen  of  Judea. 

24 

244 

XXXVIII.  . 
XXXIX.      . 

70 
60 

20 
20 

10 
20 

Mercury  sulphide. 
Mercury  sulphide. 

1-177 
1-384 

32-5 
61 

197 
341 

XL.    ... 
XLI.  .     .     . 

40 
10 

20    | 
20    -j 

10 
30 
10 
60 

Terebenthine. 
Calcic  hydrate. 
Terebenthine. 
Calcic  hydrate. 

1-275 
1-311 

22-5 
10 

122 
55 

XLII.      .     . 

XLIII.    .     . 

40 
10 

20    -j 

20    | 

10 
30 
10 
60 

Terebenthine. 
Calcined  magnesia. 
Terebenthine. 
Calcined  magnesia. 

1-203 

1-428 

31-7 
25-9 

390 
272 

XLIV.     .     . 

65 

35 

excel- 

excel- 

lent. 

lent. 

Presumably  turpentine  oleo-resin. 


CONSIDERATIONS   ON   MINERALISATION,    ETC. 

VUi.i. \MSKI.  KI T,I;I:I;  .\M.  KIIOMTK. 


LM<» 


IN  T1IKIK  EXPERIMENTS 

KXI'KUMI   S  I  I. 


A'-tii'ii  ..I  A'  die 
A.-i.l. 

Action  o 
Soda 

Altrlllliiill 

in 
Volunu-. 

QMNtta 

in 

Weight. 

A.tion  of 
Aininonia. 

Action 
..l 
Colza  Oil. 

Mineral 

Lnbrfoat- 

tag  on* 

Alteration 
in 

Vol.,,,,,.. 

\   ;.   • 
of  a 
Mixtur. 
Of 

Mineral  Oil 

'••    )..  r 

cent.,  and 

Talli.w  1" 

)..  r  01  "' 

Alteration 
in 
VoHune. 

vr 

COAlOM. 

AlU-ratiun 
Volume. 

Alteration 

in 

Volume. 

Uteration 

in 
Weight. 

Ml.  T.iti..n 
in 
Volume. 

Alt,r.,ti..n 

in 
Weight. 

Alteration 
in 
Volume. 

Per  Cent. 

Per  Cent 
+     0-746 

Per  Cent. 

IVr  (  '«nt. 
:       '2-W2 

Per  Cent. 

Per  Cent. 
4-     0-490 

Per  Cent. 
r-  12-068 

I'.-r  i  -.-Hi. 

4-    7-874 

N       11  ••;-.. 

- 

+     3-501 

- 

:     i  •  ii"; 

- 

4-     0611 

•J-7-JS 

- 

+    2-982 

.     II-:;:;:. 

4-    2-608  -f     4-989 

_ 

-r    0-187 

— 

4-     0-428 

4-     1-428 

_ 

+    6-293 

+     8-053 

_     7  •::i:, 
-     H-1-J7 
:      -J-OOO  -     0-114 

- 

-f     0-112 
-r     3-192 
-r     3-182 
-r     2-361 

- 

4-     0-344 
+    0-478 
+     0-406 
4-     0-281 

+     6-440 
+     4-918 

4-     1-418 
4-     1-515 

.    11  •'.«:,»; 
7-777 

W-OM 

].;•-.; 
4-  41-758 

4-  83v-r 

4-  11-804 
+  10-062 
4-    8-571 
4-    0-581 

4-     3-200 

25*464 

- 

+     1-404 

- 

:     0-68Q 

4-     0-862  +     0-862 

4-  20-000  4-     9-311 

4-     4-964 

4-  61-148 

-r     2054 

-r  14-145 

-r      1-351 

4-     8-198 

- 

- 

4-     7-284  4-     7-296 

- 

-r     1-296 

- 

-r     1-278 

- 

4-     0-396 

- 

- 

- 

7-17'J 

_ 

-r     2-886 

_ 

-r     0-539 

_ 

+     0-396 

_ 

_ 

_ 

1-    4-510 

- 

- 

- 

+     0-646 

— 

- 

- 

- 

- 

4-    3-569 

4-  diminution  ;  -  no  change. 
EXPERIMKNTS. 


11 

Alteration  of  Shape  under 
Strong  Pressure. 

Alteration  of  Shape  under 
Repeated  Blows  of  the 
Hammer. 

Insulating 
Power. 

s* 

% 

Limit  of  Elasticity 
metres  for  100  Mill 

Initial  Thickness 
in  Millimetres. 

Thickness  of  the 
Swollen  Edges 
in  Millimetres. 

Ihicknessofthe 
Middle 
in  Millimetres. 

Displacement  of 
the  Extreme  Edges 

in  Millimctr.-. 

Initial  Thickness 

in  Millimetres. 

Thickness  of  the 
Swollen  Edges 
in  Millimetres. 

Thickness  of  the 
Middle 

in  Milliin.  • 

Displacement  of 
the  Extreme  Edges 
in  Millimetres. 

Constant 
Depressions. 

Action  of  Heat. 

145 

1-25 

1-44 

1-17 

4-50 

i  •-«; 

1-23 

1-20 

103 

Normal. 

175 

2-30 

1-71 

... 

10-50 

2-38 

•_'-_':. 

2-25 

10-000 

575 

Disengages  funu-j*. 

135 

1-04 

0-89 

0-89 

11-50 

2-07 

1-57 

1-57 

8 

M 

145 

1-67 

1-65 

1-66 

1! 

1-92 

1-67 

1-67 

11-25 

60 

IV,  OOMI  Hit 

17:.         !    172 

1-54 

1-55 

12-25 

2-81 

•_'•_'  i 

2-25 

11 

2 

M 

185            0-96 

0-86     0-87 

10 

0-87 

0-87 

11  -_'.-,              Ill             Normal. 

190 

0-91 

10 

0-96 

093 

093 

10                   46 

If 

275 

1-20 

1-1-J 

i-o-j 

7-50 

1  -_'J 

1-41 

0-98 

6-50             105-5 

Disengages  HjS. 

285 

1-56 

i->;7 

1-21 

3-50 

1-36 

hroken 

3 

» 

105 

i  -;•_' 

0-79     0-88 

12-50 

0-97 

0-85 

11-50 

220 

Normal. 

after  3'  45" 

101-25 

0-61 

0-50     0-50 

1  1  -_':, 

0-62 

0-56 

r>57 

11 

1M> 

„ 

after  3'  15"  I 

unknown.       1"_'7       1  "17       \"17 

10 

i  -_>:, 

1-29 

1"_".' 

,,L,.-              .:> 

»> 

scaly. 

1 

250  INDIARUBBER 

Dynamo-metrical — The  testing  of  rubber. — The  indiarubber  articles  commonly 
employed  are  subjected  to  complicated  mechanical  stresses,  which  vary  with  the 
use  the  articles  are  put  to.  Their  behaviour  in  each  case  is  highly  variable,  as 
are  the  stresses,  and  it  will  be  necessary  to  consider  simple  cases  in  order  to  draw 
simple  conclusions  concerning  their  mechanical  properties.  In  the  first  case  we 
will  consider  the  modifications  of  form,  volume,  etc.,  which  occur  when  a  certain 
volume  of  rubber  is  subjected  to  strains  along  a  known  direction,  where  the 
deflections  can  be  measured  with  exactitude.  The  stress  may  be  caused  either  by 
extension  or  compression,  and  these  are  the  two  most  interesting  and  easy  cases  to 
examine.  We  will  take  first  of  all  the  case  of  rubber  subjected  to  a  tensile  strain. 
In  by  far  the  majority  of  cases  the  articles  supplied  by  factories  to  their  customers 
are  in  their  daily  use  subjected  more  or  less  to  mechanical  strains,  and  it  is  essential 
that  users  should  satisfy  themselves  that  the  articles  are  adapted  to  support  such 
strains.  This  cannot  be  done  without  a  dynamometer,,  which  will  subject  their 
materials  to  an  accurate  test  in  conditions  approximating  as  closely  as  possible  to 
those  to  which  they  will  be  subject  in  use.  These  conditions  are  extremely  variable. 
It  must  be  an  accurate  and  convenient  apparatus,  capable  of  supplying  all  possible 
data  by  means  of  the  tests  which  it  furnishes.  Nothing  is  more  difficult  than  to 
fulfil  the  conditions  which  are  essential  for  the  contrivance  of  an  apparatus  of  this 
kind.  One  apparatus  for  the  industries  concerned  consists  of  the  new  P.  B.  dynamo- 
meter, which  enables  woven  fabrics,  indiarubber,  wire,  cord,  thin  sheeting,  etc.,  to  be 
tested  ;  it  can  be  used  for  tensile  tests,  compression  tests,  bending  tests,  slow  or 
repeated  tests ;  it  will  serve  for  tests  of  abrasion,  for  determining  the  coefficient  of 
friction,  plasticity,  etc.  By  its  aid  tests  can  be  carried  out  at  ordinary  atmospheric 
temperature,  or  at  temperatures  above  and  below  that  of  the  surrounding  air.  Finally, 
diagrams,  which  are  automatically  traced  out,  may  combine  all  the  interesting 
coefficients  of  the  above-mentioned  tests. 

The  dynamometer  illustrated  is  horizontal.  It  consists  of  a  solid  cast-iron 
table  p,  faced  perfectly  true  in  its  upper  part,  which  rests  on  two  strong  cast-iron 
legs  stiffened  by  cross-stays ;  on  the  table  are  the  two  principal  parts  of  the  dynamo- 
meter :  the  apparatus  producing  the  stresses  and  the  appliance  for  measuring 
them. 

(a)  Appliance  for  measuring  the  stresses. — In  its  design,  balance  levers,  which 
are  very  cumbersome  without  being  more  accurate  than  the  special  steel  spring 
adopted,  were  put  on  one  side.     A  well-gauged  and  thoroughly  tempered  spring, 
not  working  under  a  maximum  load,  wilich  crushes  it  down  completely,  is  a  highly 
accurate  and  very  convenient  measuring  appliance.     The  spring  a  is  compressed 
against   a   small   cross-piece    t,  by   a   rod    passing    along   its  axis   and   carrying 
one  of  the  locking  jaws  e,  for   the  test  pieces.     On  this   rod   there   is  gripped, 
between  two  nuts,  a  cam  6,  which  governs  a  rack .  j,  the  latter  rotating  a  gear 
wheel  k  with  vertical  shaft.     On  the  shaft  of  this  gear  wheel  is  fixed  a  needle  I, 
which  shifts  along  graduation  marks  m.     When  the  test  piece  breaks,  the  spring 
expands,  but  leaves  the  needle^'  in  its  position  ;  consequently  the  breaking  load  can 
always  be  precisely  read  off.     Every  measuring  appliance  must  be  capable  of  being 
thoroughly  checked  from  time  to  time.      To  provide  for  this  checking  the  measuring 
spring  is  fitted  between  two  small  columns  x  x  which  connect  the  two  small  cross- 
pieces.    The  end  cross-piece  carries  an  eye-bolt  A,  and  the  whole  of  the  spring  of  the 
two  cross-pieces  may  be  unbolted  and  taken  off  the  apparatus.     By  suspending  the 
whole  to  a  hook  by  the  eye-bolt  h,  and  hanging  marked  weights  on  the  clamp  e,  the 
apparatus  for  measuring  the  dynamometer  strains  may  therefore  be  tested  at  all 
times. 

(b)  Strain  producing  apparatus. — The    piece   to  be  tested   (by  tension,  for 
instance)  is  locked  between  the  two  clamps  e  and  /,  as  shown  on  Fig.  94.     This 
latter  jaw  is  connected  with  a  slide  g,  which  in  turn  is  connected  with  another  slide 
o  by  a  screw  n.     This  screw  is  actuated  at  two  speeds ;  at  the  higher  speed  (when 
desired  to  operate  quickly)  by  means  of  the  horizontal  hand- wheel  carried  on  the 
support  o ;  this  wheel  controls  the  screw  by  a  bevel  gearing ;  at  the  smaller  speed 


CONSIDERATIONS   ON    MINERALISATION,    ETC. 


252  INDIARUBBER 

(when  a  great  pull  is  to  be  developed)  by  means  of  a  tangent  screw  actuating  the 
gear  wheel  carried  on  the  front  of  the  support  o. 

(c)  Oscillating  apparatus. — The  two  parts  g  and  o  may  be  locked  on  the  table 
or  loosened  as  desired.     To  the  lower  part  of  o  is  attached  a  connecting  rod  q,  con- 
trolled by  an  eccentric  wheel.     If  therefore  the  two  slides  g  and  o  are  set  free,  and 
this  eccentric  wheel  is  put  in  motion,  a  series  of  repeated  tensions  may  be  exercised 
on  the  test  piece.     The  width  of  travel  may  be  varied  by  altering  the  position  of 
the  crank  pin  on  the  eccentric  wheel.     The  eccentric  wheel  is  carried  at  the  end  of 
a  horizontal  shaft,  at  the  other  end  of  which  is  keyed  the  gear  wheel  r,  operated  by 
a  tangent  screw  s  :  on  the  spindle  of  this  latter  is  fitted  a  three-step  cone  capable  of 
giving  varying  speeds,  and  a  small  motor  of  some  kind  (preferably  electric)  can 
operate  the  whole  by  means  of  a  small  belt.     A  crank  may  be  used  for  the  same 
purpose.     The  eccentric  wheel  may  be  raised  or  lowered  vertically ;  the  purpose  of 
this  will  be  seen  below. 

(d)  Tensile  tests  at  varying  temperatures. — To  carry  out  tensile  tests  at  the 
ordinary  temperature  the  pieces  are  locked  between  the  twro  clamps.     These  clamps 
have  channels  of  increasing  depth  from  their  end  to  the  bottom  in  order  to  avoid 
cutting  the  fabrics  and  indiarubber ;  moreover,  other  locking  devices  may  be  fitted 
when  it  is  required  to  test  hard  bodies,  such  as  ebonite  and  steel  wdre ;  channeled 
wedge  locking-pieces  are  then  used.     For  hemp  cords  small  drums  are  employed. 
All  these  are  absolutely  indispensable  precautions  for  obtaining  correct  results.    When 
it  is  desired  to  test  pieces  of  various  materials  by  tension  at  a  temperature  differing 
from  the  atmospheric,  these  pieces  are  placed  in  a  vat  containing  a  liquid  which 
may  be  heated  or  cooled.     The  clamps  then  have  a  bend  to  enable  them  to  pass 
over  the  edge  of  the  vat. 

(e)  Compression  tests  at  various  temperatures. — Compression  tests  are  very  well 
carried  out  by  the  dynamometer  by  fitting  up  between  the  clamps  e  and  /  a  small 
so-called  reversion  appliance,   which  contains  four  plates  coupled  in  pairs,  and 
arranged  in  such  a  way  that  when  the  outside  plates  move  apart  the  inside  plates 
draw  together.    The  pieces  to  be  compressed  are  arranged  between  these  two  latter 
plates,  and  the  test  is  carried  out  without  any  difficulty,  with  convenient  measure- 
ments of  the  stresses  and  deformations.    These  tests  may  be  made  cold  or  at  various 
temperatures  under  the  same  conditions  as  the  tensile  tests,  and  on  bodies  of  every 
kind. 

(f)  Plasticity  tests. — The  plastic  materials  employed  in  industry  are  legion.    Their 
chemical  constitution  is  perfectly  well  known,  but  when  their  characteristic  feature, 
plasticity,  is  in  question,  there  are  hardly  any  data  available.     The  dynamometer 
P.  B.  system  here  once  more  fills  a  gap.     It  allows  of  measuring  with  precision  the 
plasticity  of  soft  bodies.     For  this  purpose  the  latter  are  enclosed  in  a  small 
cylinder  shut  at  the  bottom  by  means  of  a  plug  in  which  a  hole  is  drilled.     On  the 
soft  body  (wax,  plastic  mixture,  etc.)  a  piston  is  rested,  which  rises  without  friction 
in  the  cylinder,  and  it  is  noted  what  pressure  is  required  to  make  the  soft  body  flow 
out  through  the  aperture  in  the  plug,  and  what  quantity  of  matter  can  flow  out  in 
a  given  time.     To  make  the  test  the  arrangement  is  fitted  up  in  a  small  reversion 
appliance  as  for  compression.     The  plasticity  test  may  be  made  cold  or  hot.     Special 
attention  is  asked  to  the  importance  of  this  most  essential  point. 

(g)  Repeated  bending  tests. — The  work  to  which  certain  parts  are  subjected  when 
in  use  is  not  only  the  result  of  slow  stresses,  but,  above  all,  repeated  stresses.    That 
is  why  this  dynamometer  is  provided  with  all  that  is  required  for  carrying  out 
tension,  compression,    and   repeated   flexion   tests.     The   apparatus    for   bending 
tests   is  somewhat  different  from    that  for   tension  and  compression.     Take  for 
instance  a  layer  of  woven  fabric  in  a  pneumatic  tyre,  and  see  how  it  behaves  under 
use.    In  the  first  place  the  fabric  is  distended  by  the  pressure  of  the  air  in  the  inner 
tube,  and  afterwards,  in  use  of  the  tyre,  this  fabric  will  have  to  undergo  repeated 
bending.     It  is  essential  to  approximate  to  these  combined  modes  of  strain  and  stress 
when  required  to  test  pneumatic  tyre  webbing. 

The    dynamometer   in    question    admits    of   doing   this    with    facility,  and  is 


CONSIDERATIONS   ON   MINERALISATION,   ETC. 

applicable  to  many  similar  eases.    For  this  purpose  the  fabric  (or  ;iuy  piece  of  india- 
rubber,  cord,  thin  sheeting,  etc.)  is  first    dra\\n  out   to  a  kno\\n   tui-i..n  by  ineaiUI 
of  the  ordinary  ten-ion  ja\\s  >  and  /of  th«-  d\  n  amometer.      On  tin-  frame  «»f  the 
dynamometer   a   small  column    is  glared  carryini:   a   >lide  pr<i\id«-d  \\itli  t\\o  p,|!. 
betueen    which    the  stri|»  of    fabric   to    be    IM-HI     passes.      Tliis   slid*-    i-    m-.\,-d    ,.M 

l)oth    sides   alternately    of    the    run    ..!'   tin-  strip  of    fulirir    (..r    mi    •    nd--   «nl. 

desired)  by  means  of  a  Hinall  ronin  -et  iir_r  rod  o|H-ratcd  by  the  eccentric  wlitfl 
already  referred  to.  It  \\ill  I.e  clearly  seen  that  the  -trip  ma\  tlm>  b«-  indent. -.1  hv 
known  tpiantities,  ami  t  he  niunlicr  of  bending  n<>'  :upted.  The 

information  which  may  In-  trained  in  this  \\;ly  is  of  the  utnio>t  iiujHirtiiin-e.      It  Mill 
be  observed  that  the  damps  e  and/  of  the  apparatus  are  fitted  on  liori/.ont.tl  -h 
which  allow  the  strip  to  oscillate  \\ithin  |>erfectly  defined  and  accurate  limit-, 
this  arrangement  it  can  be  ascertained  what  range  of  stresses  in  the  distended  strip 
correspond  to  a  deformation  in  that  strip.    The  speed  and  width  of  the  deformations 
can  he  varied  just  as  in  the  tensile  or  bending  tests  already  referred  to. 

(h)  Abrasion  tests  and  determining  coefficients  of  friction. — One  of  the  most 
important    features    of    this   dynamometer    relates    to    the    (mssihility    of   deter 
mining  l»y  its  aid  both  the  wear  and  tear  and  the  eoetlicient  of  friction  .,f  \\ 
fabrics,  indiarubber,  wood,  metal,  etc.     The  following  is  the  procedure  adopted  to 
this  end : — 

On  the  table  of  the  dynamometer  a  small  column  is  placed  carrying  a  graduated 
double-arm  lever  arrangement,  along  which  an  index  moves,  to  \\hich  a  marked 
weight  may  be  suspended.  This  lever  is  supported  on  a  vertical  rod  accurately 
guided  in  the  column,  and  on  its  lower  part  this  rod  carries  a  pillow  \\hich 
presses  on  the  piece  to  be  abraded.  This  test  piece  may  be  of  any  kind;  win -n 
it  is  a  long,  soft  body,  it  is  held  between  the  two  damps  -  and/',  drawn  out  to  a 
suitable  tension,  and  the  pillow  on  the  above  rod  pressed  upon  it.  On  the  other 
hand,  the  rim  of  the  eccentric  wheel  is  provided  with  a  removable  abrasion  crown, 
and  contact  made  between  the  bottom  of  the  strip  to  be  abraded  and  the  abrading 
crown.  The  process  of  operation  will  be  immediately  understood:  the  eccentric 
wheel  wears  down  the  test  piece,  whether  it  is  a  fabric,  a  rubber  strip,  an  eln.nite 
rod,  or  a  metal  strip,  under  conditions  of  speed  and  friction  surface  which  may  be 
varied  as  required.  But  the  lever  applying  the  pillow  indicates  the  pressure  under 
which  the  abrasion  takes  place  ;  this  pressure  is  evidently  a  highly  imjwrtant  factor 
in  the  wear,  and  this  wear  is  ascertained  by  the  loss  of  weight  of  the  substance 
tested  after  a  certain  number  of  wheel  revolutions.  The  coefficient  of  friction  of 
the  substance  tested  is  easy  to  determine,  because,  under  the  action  of  the  abrading 
crown,  the  strip  tends  to  pull  on  the  dynamometer  spring ;  the  variation  of  tension 
caused  by  this  action  will  be  read  off  immediately  on  the  appliance,  and,  on  1>< 
referred  to  the  initial  tension  to  which  the  strip  is  subjected,  will  give  the  coefficient 
of  friction  of  the  latter.  (1)  Perforating  tests  in  fabrics  or  soft  substances. — A 
strip  of  fabric  or  indiarubber  drawn  tight,  as  in  the  abrasion  test,  can  be  perforated 
or  cut  without  difficulty  if,  at  the  end  of  the  pressure  rod,  a  needle  jKiint  or  knife 
be  fitted ;  and  the  value  of  this  arrangement  lies  in  the  fact  that,  on  the  one  hand, 
tests  of  this  kind  can  be  carried  out  on  a  strip  the  degree  of  taut  ness  of  which  i- 
known,  and  with  a  precise  measurement  of  the  perforating  pressure;  and  that,  on 
the  other  hand,  the  perforation  or  the  cutting  can  be  carried  out  on  the  free  strip 
without  supjKjrt,  or  on  the  strip  supported  on  the  eccentric  wheel.  An  approxima- 
tion is  thus  made  to  what  would  take  place  in  many  cases  in  practice.  The 
dynamometer  is  thus  adapted  for  tests  of  an  exceedingly  wide  range,  and  is  thus 
so  far  superior  to  the  ordinary  dynamometers  used  in  industry.  Its  value  is  still 
further  enhanced  by  the  fact  that  it  can  supply  a  faithful  record  of  the  tests  carried 
out.  This  is  effected  by  a  diagrammatic  record  of  the  slow  tensile  and  compression 
tests,  owing  to  an  improved  record  apparatus  fitted  on  the  table  of  the  appliance. 
This  recorder  consists  of  a  drum  which  can  revolve  as  a  function  of  the  deforma- 
tions of  the  pieces  tested,  by  means  of  a  wire  which  accurately  follows  the 
deformation  at  two  points  in  these  pieces.  A  special  arrangement  of  tongs  is 


CONSIDERATIONS   ON   MINERALISATION,    ETC.          255 


provided  for  this  porpoae,     On  th«-  recm-din^  drum  a  tracing  pen  runs,  following, 

and  enlaruriiiu'  tin-  deformations  of  tin-  measurement  spring  of  tin-  apparatus. 

|-'iur.  '•'•">  slin\\s  tin-  d\  nanometer,   as   titled   up    for  carrying  out  tin-   principal 

trst>   fur  \\hirh   It    is  designed.  i 

KiiC-   -1''  represents    the   dynamometer  in-tailed   for   a    trn-ilr  i«->t    on  indiarnltber 
or   a    fabric.       Tin-    t«->t    piece   subjected    to  tension    can  1,«-    viit.mitted  to    alternating 
force    by    mean-    of    the   connecting    rot  I,    \\lii.-h'  ran    U-   dri\en    at    .lillnvnl 


FIG.  96. — Dynamometer  for  the  tensile  testing  of  indiarabber. 


The 


sj^eeds  by  the  wheel  operated  by  the  tangent  screw  and  the  large  pinion, 
figure  also  shows  the  recording  appliance. 

The  small  wire  bridging  connects  points  on  the  two  jaws,  which  follow  the 
stretch  of  the  strip,  l>et  \\ern  two  standard  points,  passes  along  the  small  support, 
which  is  plumb  with  the  drum,  and  goes  on  from  this  point  to  operate  the  latter. 

Fig.  97  shows  the  dynamometer  as  installed  for  compression  tests.     These  tests 


FIG.  97. — Dynamometer  for  compression  t 

are  carried  out  by  means  of  a  four-plate  appliance,  which  reverses  the  direction  of 
tension  of  the  dynamometer,  and  enables  a  te>t  picre  to  be  crashed  between  its 
middle  plates.  The  bent  form  of  the  parts  attaching  this  reversing  appliance  to 
the  dynamometer  damps  has  been  adopted  to  enable  hot  compression  tests  to  be 
carried  out.  The  small  trough  or  tray  used  for  these  tests,  with  its  gas  connections, 
is  supported  against  one  of  the  legs  of  the  appliance.  The  connecting  rod  and 
eccentric  wheel  allow  these  compression  tests  to  be  carried  out  on  a  continuous 


256 


INDIARUBBFR 


system.  On  the  dynamometer  bench  there  will  be  observed  a  small  piston  and  the 
cylinder  used  for  tests  on  plastic  bodies.  The  compression  diagrams  can  be  made 
in  the  same  way  as  tension  diagrams.  The  recorder  has  been  taken  off  for  the 
purpose  of  photographing. 

Fig.  98  shows  the  dynamometer  equipped  for  carrying  out  tests  on  fabrics  or 
other  substances  by  means  of  repeated  bending.     For  this  purpose  the  large  con- 


FIG.  98. — Dynamometer  for  repeated  bending  tests. 

necting  rod  is  taken  down  and  a  small  one  fitted  in  its  place,  and,  on  the  other 
hand,  on  the  bench  of  the  apparatus  there  is  fitted  a  support  with  slide  carrying 
two  rollers,  between  which  the  specimen  to  be  bent  passes.  This  specimen  is 
previously  drawn  tight  between  the  two  locking  jaws,  and  the  bends  give  it  an 
additional  tension  until  it  breaks.  The  bends  may  vary  in  width  as  required  up 


FIG.  99. — Dynamometer  for  abrasion  tests. 

to  50  millimetres,  the  slide  of  the  large  wheel  being  graduated  and  allowing  of 
accurate  measurement  of  this  width.  The  clamps  are  jointed  on  their  shafts  and 
follow  the  bends  of  the  fabric. 

Abrasion  tests. — Fig.  99  represents  the  dynamometer  arranged  for  abrasion  tests 
on  various  specimens.  The  specimen  mounted  in  and  seen  on  the  figure  is|a  strip 
of  fabric.  This  strip  is  first  drawn  to  a  given  tension  between  the  clamps,  and  the 
eccentric  wheel  is  then  placed  so  that  the  upper  part  of  this  rim  forms  a  tangent  to 


CONSIDERATIONS   ON    MINERALISATION,  ETC. 


hhe  tension  shaft;  it  then  comei  in  to  contact  with  the  ^--riiiH-n  piece  to  be  abraded 

On  this  |:ltter   is  brought  to  bear  a  surfaced  pillow,  \\hi  >«d  again  M   tin- 

fal.rir  by  nirans  of  a  vn-tiral  rod  guided    in   a   bearing  the  ptwetOT    ;  •   i«-  Uo\sn 
and  regulated  by  meant  of  a  i.alan.-r  level  Uid.-d  unh    ,  U|H(.|,  r;iu  u. 

varied  «    desired.     Tin-  rrrmtrir  \\hrrl  is  put  in  motion,  ;i,.,l  uith  it  ti 

tin-    lattrr    exercising    an     mhlitinmtl    tt-n>i<»n    mi    tin-    met 
wl.liliinint  trn<i,,u.  di\idrd  l,y  tin-  \\riirht   pri-ssin^  ,,M  thr  fal.ri.-,  inn,. 
the  coefficient  of  friction    l,rtwvn    thr    lal.rir   an.l  th.-  rim   of  tin-  \\l,,,-l.      TJn 
may  be  covered  with  emery  cloth  or  any  other  abrading  uubstance.     As  it  conniM* 
of  a  (ILsinoimtal.lr  rim  h«-l.i  latmtlly  by  two  hoops,  it  may  l>e  replaced  as  dcnirtil  l.\ 
the  oixjrators,  and  the  appliance  attached  to  the  screw,  so  that  thr  h-ver  in  always 
horizontal,  \vhirh  is  shown  l.y  a  small  in.l.-x  ;  in  this  way  the  fabric  will  be  perform 
and  the  load  causing  the  i>erforation  noted. 

Fig.  100  represents  the  dynamometer  installed  for  abrasion  tests,  and  in  front 
of  it  are  exhibited  all  its  numerous  accessories.     The  tracer  pencil  ho|,|,-r  i*  <i< 
by  a  cam  cast  on  the  tensile  clamp  attached  to  the  mrasui  im:  -prim:,  and  records 
the  compressions  of  the  spring  along  the  generating  lines  of  thr  «lrnm.  and  «  "n 


FIG.  100.— Dynamometer  with  all  its  accessories  for  abrasion  tests. 

sequently  the  stresses  exercised.  The  diagram  is  thus  traced  automatically,  which 
is  of  capital  importance  in  a  mechanism  of  the  kind  with  which  we  an-  »lralin^. 
hand-traced  diagrams  being  generally  defective.  The  spring  which  serves  for  thr 
measurement  of  the  stresses  of  the  appliances  can  easily  be  removed,  and  may  U« 
of  varying  power.  In  the  dynamometer  represented  on  the  preceding  figures  fan 
are  available  three  springs,  measuring  50,  200,  and  1000  kilos.  ivsi*vtivrly.  Tin- 
sensitiveness  of  the  appliance  is  therefore  variable  as  required  and  according  to  th. 
nature  of  the  test,  which  is  of  great  advantage.  Of  course  there  is  a  graduation  of 
each  spring  on  the  dial  of  the  apparatus,  and  the  same  needle  allows  of  reading  off 
on  the  three  scales,  by  aid  of  an  alidade  fitted  with  crossed  threads  in  which  thi- 
needle  terminates.  The  person  in  the  illustration  standing  beside  the  apparatus 
shows  the  comparative  size  of  the  latter  and  its  parts. 

Patent  -rnUter  tester  (System  Sctwpper-Dale'n.) — For  mechanical  testa,  i.e.  for 
ascertaining  the  strength  and  elasticity  of  rubber,  a  new  api>aratu8  suitable  for 
testing  rubber  on  the  basis  of  the  lever  construction  of  strength  testers,  has 
been  devised.  The  difficulty  encountered  in  mechanical  tests  was,  at  the  suggestion 
of  Professor  Dalen  of  the  Royal  Testing  Institute  at  Gross-Lichterfelde,  overcome 
17 


258 


INDIARUBBER 


by  employing  for  the  tests  ring-shaped  test  bodies  instead  of  strips.  This  idea  in 
conjunction  with  that  of  Schopper  to  move  the  ring-body  positively  proved  to  be  an 
excellent  one,  and  the  apparatus  now  in  question  meets,  in  the  most  perfect  manner, 
all  demands  to  be  made  from  the  point  of  view  of  material-testing  technics.  It 
admits  the  exact  establishment  of  the  strength  and  elastic  qualities  of  rubber  in 
figure  values,  the  exact  determination  of  which  had,  hitherto,  been  found  to  be 
a  matter  of  impossibility.  The  ring-shaped  standard  test  bodies  are  cut  out  of 


FIG.  101.— Machine  for  indiarubber  tests  (L.  Schopper,.  Leipzig). 

vulcanised  plates  on  a  cutting  press.  If  it  is  necessary  to  test  the  quality  of  trial 
mixtures  in  the  laboratory  mechanically,  trial  plates  are  first  vulcanised  by  means 
of  devices  accompanying  the  apparatus ;  then  the  standard  bodies  required  for  the 
test  are  cut  out  of  them,  or  the  material  to  be  tested  is  vulcanised  in  annular 
moulds. 

The   apparatus   is  worked   by   water   power,  is  fitted  with  the  return  valve, 
System  Martens,  and  can  be  joined  to  any  water  pipe  of  about  three  atmospheres 


CONSIDERATIONS   ON    MINERALISATION,    ETC. 


DPft      At    tin-    liniment    «.t    rupture,    tin-    u<-L'lit  lever    an.!   the-    sttvt«-h  j«.int»-r 
;uv   cut  Ollt  automatically.       An   a.vuratr  mard  "I    -tiviitfth  ami    -trt-li-li.  tli> 
is  given.      In   order   to   lu-in^   tin-   a|.|-aratiw  to  a  stan«l>till   ;it   any  tinu-  in  th«« 
feOUne    «•!'    tin-  test,  tin-  -tt-.-rin.j  \al\i-   i-  r.|iii|.|M-,|  \\itli  ;in  in-t.tntalieOIW 
ruck. 


d 


Fio.  102.— Catting  press  for  making  standard  test  samples  with  two  circular  knives. 


CHAPTEE  XII 

RUBBER  SUBSTITUTES— IMITATION  RUBBER— ANALYSIS  OF 

INDIARUBBER 

THE  high  price  to  which  rubber  often  rises,  from  one  cause  or  another,  has 
stimulated  manufacturers  to  try  to  find  whether  it  were  not  jx>ssible  to  replace  this 
substance,  wholly  or  partially,  by  cheaper  natural  or  artificial  products  with 
analogous  properties. 

Elaterite — Coorongite. — Nature  yields  few  substances  capable  of  being  used 
directly  as  substitutes  for  the  solid  hydrocarbides  called  rubber.  That  is  why  we 
simply  mention  the  fossil  rubber  of  Faujas  de  Saint  Fond,  found  in  the  natural 
fissures  of  the  Castleton  mines, — a  blackish,  bituminous,  compressible,  even  elastic 
substance  resembling  pieces  of  old  leather,  which  was  afterwards,  under  the  name 
of  Elaterite,  shown  to  occur  in  the  quarries  in  the  neighbourhood  of  Angers  in 
France,  and  of  Newhaven,  Connecticut,  U.S.A.  But  this  substance,  only  met  with 
accidentally,  and  in  infinitely  small  quantities,  in  the  two  localities  above 
mentioned,  is  found  at  Coorony,  Adelaide,  and  in  South  Australia,  and  is  an 
article  of  commerce  there.  It  has  not  been  sufficiently  examined  to  decide 
definitely  as  to  its  vegetable  origin.  It  is  found  in  rather  thick  deposits,  in  the  sand  of 
certain  localities.  Some  authors  assert  that  this  product  is  simply  the  dried  juice 
of  a  defunct  vegetation,  transformed  by  heat  and  the  pressure  of  the  deposits  in 
which  it  is  enclosed  into  resino -bituminous  masses.  Others  attribute  it  to  a  mineral 
origin  identical  with  that  which  produces  naphtha  and  petroleum.  Elaterite  is  a 
hydrocarbide  of  specific  gravity  of  0*982  to  0*990 ;  it  rather  resembles  certain 
varieties  of  rubber ;  it  is  soft,  elastic,  and  ductile,  burns  with  a  fuliginous  flame, 
but  with  no  smell ;  it  is  adherent,  but  does  not  soil  the  hands  ;  its  natural  smell  is 
that  of  rubber,  and  it  is  easily  cut.  A  finely  cut  lamina  examined  by  the  microscope 
exhibits  a  cellular,  granular  structure,  traversed  by  a  fibrous  matter,  just  like  a 
dried  mushroom.  This  fact  confirms  the  vegetable  origin  of  coorongite,  but  it  is 
difficult  to  conclude  that  it  is  simply  the  result  of  the  heating  and  compression 
of  vegetable  tissue  altogether  altered  in  its  nature,  or  that  it  is  the  dried  juice 
of  some  plant.  On  dry  distillation  it  yields  82  per  cent,  of  gaseous  and  liquid 
hydrocarbides  (Heinzerling).  The  special  technical  literature  gives  no  indication 
of  the  direct  use  of  this  substance,  but  there  is  every  reason  to  believe  that  it  is 
used  as  an  ingredient  of  certain  inferior  quality  rubbers.  There  are  no  facts  to 
prove  the  utility  of  such  a  mixture. 

The  list  of  natural  rubber  substitutes  is  therefore  not  a  long  one.  It  is  not  so 
with  imitation  rubbers,  preparations  due  to  the  ingenuity  of  inventors  or  manu- 
facturers :  these  products  are  more  or  less  similar  to  rubber  in  some  of  their 
properties.  Imitation  rubbers  generally  have  drying  oils  as  basis,  e.g.  linseed  oil, 
walnut  oil,  etc.  (this  latter  oil  is  too  dear,  and  is  only  mentioned  to  show  that  the 
same  results  can  be  got  with  it  as  with  linseed  oil).  Receipts  are  innumerable ; 
each  maker  has  his  own  sleight-of-hand ;  practice  and  experience  play  an  important 
part,  and  an  irreproachable  imitation  is  not  made  on  the  first  attempt.  Numerous 
experiments  are  necessary  to  arrive  at  right  proportions  and  proper  temperature. 
It  is  not  intended  to  enumerate  all  known  and  proposed  receipts  for  making 
imitation  rubber.  Published  receipts  are  generally  obsolete,  fit  to  guide  beginners  in 


RUBBER  SUBSTITUTES 

practical  reseaivh.-s  I, ut  not  -utlieieiit  for  immediate  and  profitable  use  in  trade. 
It  will  sntlicv,  therefore,  to  describe  tin-  pivparati-.n  <-!  th.-  two  j.riiii-ij^l  \.irietiei 
of  imitation  rubbers  in  m-M  ur'-n«-i;il  UM-,  n.iin.-ly  (h  oxjdised  oils;  ( J »  \  ul 

c.uii-ed   oik 

1.  O.i- id i8t'< I  ni/s  if  acid  cm  linired  oil. — 

SaCC,    \\hiUt    studviuo;   in    l*H'»    tin-   sapmiiticutinn   ,,f   linked  oil   by  cailM 
6Zftinined    the    action    ••!'    nitric   aci.l   on    that    oil.       When    1<>(»    j  art*  of  HliMCfd 
and    '100    parts    o|'   nitric    aci.l,  dilutrd    with    tour  times    its   volume  of  water,  Are 
gently  heated  \\itli  continual  stirring,  the  i.il   a-iiines  a  l.r«. \\ni-li  ivd  colour;  there 
U  alumdant  disengagement  of  nitrous  \apours  the   oil    thirki-iw,  and  after  four 
hour*  the  mass  ac.|iiiiv>  a  \ery  derided  >vrup.  r,cy.      <'>i.»it.-Uoucdc*  kuUe*.— 

L.  /onas,  resuming  in  |S|s  th.-  i-.\|K-niin-i!-  tin-  to  linseed  oil  previously 

viscous,   tlu-n,  after  having  jMirtially  burnt   it,  hr  tiv.it,-,!   tin-  residue  \\itli  dilute 
nitric  acid.      This  was  the  beginning  of  oxidised  oil  rubber  >ul.>titutcs  (caoutchouc 
«!«•-  liuiles).     Sollier  and  Rattier's  attempts. — In  l.^-M.  I     >"llier,  whether  ignorant 
or  not  of  these  laboratory  experiments,  took    in   hand    researches  with  the 
preparing  from  linseed  oil  a  product  cabbie  of  replacing  rubier  in  some  1-1 

ntial    applications.      Rattier  patented   a   product    of   the   ^.m,  ]'i'-*ent 

process. — A  certain  proportion  of  linseed  oil  is  heated  until  it  i*  con\«ited  into  a 
brown  viscous  mass.  To  thus  convert  10  kilos,  (-ay  L'L'  ll>. ),  it  i-  m  cetwary  to 
heat  for  at  least  twenty-four  consecutive  hours.  The  viscous  mass  w  afterwards 
treated  in  the  hot  state  for  a  few  hours  with  nitric  acid  until  it  has  assumed  a 
thick  plastic  consistency,  and  when  cooled  in  the  air  becomes  solid.  Tin-  pi"d 
lived  from  excess  of  acid  by  kneading  it  for  some  time  in  a  rather  weak  alkaline 
lye  until  it  no  longer  has  an  acid  reaction.  When  cold  it  exhibits  the  ap|>earance 
of  natural  rubber;  it  is  rather  elastic,  softens  in  hot  water,  and,  unlike  rubber, 
becomes  plastic  like  gutta  percha.  It  is  soluble  in  spirits  of  turi»entine,  carbon 
disulphide,  and  alkalies.  Acids  precipitate  it  unchanged  from  its  alkaline  solution. 
The  product  was  at  once  utilised  for  manufacture  of  waterproof  canviis,  imitation 
leather  for  saddlery  and  carriage  building,  and  travelling  articles  of  a  suppleness 
and  fitness  leaving  nothing  to  be  desired.  Its  use,  although  less  and  less  consider- 
able for  some  time  back,  is  still  in  vogue,  and  if  it  be  but  rarely  used  alone,  it  is 
still  sometimes  added  to  articles  made  from  pure  rubber.  As  it  adheres  j»ert. 
to  all  fabrics  without  injuring  them  or  penetrating  them  too  deeply,  the  manu- 
facturers of  waterproof  canvas  often  resort  to  it.  It  may  also  U-  applied  without 
any  ditlieulty  to  wood,  to  stone,  and  to  metals,  and  in  so  doing  it  contracts  a  most 
remarkable  adherence.1 

2.  Vulcanised  oils. — Nickles  and  Rochleder  first  observed  the  action  of  sulphur 
chloride  on  fatty  oils,  by  which  they  are  transformed  into  a  rubber-like  siiK-t^- 
Mixed  with  any  vegetable  oil,  sulphur  chloride  immediately  converts  that  oil,  almost 
at  the  ordinary  temperature,  into  a  solid,  sometimes  very  hard  substance. 

r-irkes1  patent. — Parkes,  to  whom  the  process  of  vulcanising  rubber  by  sulphur 
chloride  is  due,  patented  a  process  for  vulcanising  linseed  and  rape  oils,  also  by 
sulphur  chloride  (British  Patent,  22ud  October  1855  :  N  -  '>59). 

linn. Dili's  researcties. — In    1S.")S,    Koussin    communicated    to    the    Acadcn 
Sciences  the  result  of  his  researches  on  the  action  of  sulphur  chloride  on  oil  r_M.»th 
November).     One  hundred  parts  of  linseed  oil  and  about  25  parts  of  sulphur  ehloride 

1  Although   nitric  acid   and   linseed   oil   as  described  above  yield  a  product  somewhat 

aiiiilojjous  to  the  one  next  to  be  descril-oi!,  namely,  that  obtained  by  tin-  ;i«-tion  of  sulphi 

chloride  upon  oils,  yet  in  the  latter  case  it  wonM  appear  to  be  the  sulphur  win 

agent,  which  rxpluins  why  we  can  get  a  similar,  if  nut  the  same,  substance  byusin^eitl 

or  nun-drying  oils  in  tin-  present  case.     However,  in  the  solid  ilii-.-itimi  of  linseed  oil  by  oxi-l.iti.. 

1>\   nitric  acid,  we  arc  ct.nfrontc.l  with   a   rapid  oxidation   pr-x-ess  exclusively  ronfin- • 

oxidisahlc  principles  which  an-  only  found   in  drving  oils.     The  oil  is  first  heated  S4i  fat 

render  it  viscous;  it  is  then  boiled   for  a  lung  time  with  dilute  nitrio  acid.     .\ 

brown  substance,  which  does  not  stick  to  the  tinkers,  is  obtained,  analogous  to  caoutchouc.  \vh« 

its  name  of  Hack  artificial  rubber.     The  same  substance  is  obtained  with  the  different  drying 

oils,  but  in  proportion  to  the  intensity  of  their  di  vim:  probities.     Linseed  and  walnut 

yield  eight  to  ten  times  as  much  as  poppyseed  oil.—  1 


•2(>'2  INDIARUBBER 

yield  a  compound  possessing  the  maximum  of  hardness.  One  hundred  parts  of  lins* -i •<  1 
oil  and  15  to  20  parts  of  sulphur  chloride  yield  a  more  supple  product ;  whilst  100  parts 
of  oil  and  5  of  chloride  thicken  the  oil,  but  do  not  harden  it.  This  latter  compound 
is  soluble  in  all  ordinary  oils,  but  thicker  combinations  only  swell  in  these  vehicles. 
When  a  certain  quantity  of  linseed  oil  is  diluted  with  thirty  to  forty  times  its 
weight  of  carbon  disulphide,  and  if  one-fourth  of  the  weight  of  oil  be  replaced  by 
the  same  quantity  of  sulphur  chloride,  a  product  is  obtained  which  remains  liquid 
for  a  few  days.  If  this  solution  be  applied  on  glass,  wood,  etc.,  the  carbon 
disulphide  evaporates  immediately,  and  a  coat  of  varnish  is  soon  obtained.  Several 
precautions  must  be  taken  in  order  to  produce  mixtures  of  chloride  of  sulphur  and 
oil  possessing  the  properties  just  referred  to.  A  sulphur  chloride  containing  the 
strongest  possible  proportion  of  sulphur  must  be  selected.  This  liquid  product  is 
poured  rapidly  into  the  oil,  and  the  mixture  agitated  in  order  to  obtain  a  uniform 
mass.  Soon  the  oil  heats,  the  reaction  is  finished,  and  the  oil  hardens  or  forms  a 
soft  compound,  according  to  the  proportions  of  chloride.  It  is  essential  only  to 
operate  on  small  quantities  at  a  time,  and  to  avoid  such  an  elevation  of  temperature 
as  would  volatilise  the  chloride,  produce  bubbles,  and  even  blacken  or  carbonise 
the  oil.  Sulphur  dichloride  should  never  be  used ;  its  action  is  too  strong  and  too 
rapid ;  the  oil  being  treated  would  carbonise  very  rapidly,  and  the  preparation 
would  be  irremediably  burnt.  When  the  two  substances  are  intimately  mixed,  the 
product  is  run  on  to  a  glass  plate,  or  upon  another  plane  polished  surface,  where  it 
is  equalised,  then,  after  the  lapse  of  five  to  ten  minutes,  according  to  the  tempera- 
ture, combination  is  complete.  As  a  final  result  a  pellicle  is  obtained,  which  it  is 
easy  to  raise;  one  of  the  corners  is  detached  by  the  point  of  a  knife,  and  the 
remainder  gently  pulled  off  by  means  of  this  corner.  Moreover,  several  of  these 
layers  may  be  superimposed,  taking  care  so  that  they  may  amalgamate  together 
well,  to  apply  one  above  the  other  when  the  latter  is  cold.  In  order  to  ensure 
perfect  amalgamation,  moisture  must  be  avoided,  which  decomposes  the  chloride 
and  prevents  adherence.  By  working  as  just  described,  solid  plates  are  obtained 
capable  of  being  used  in  making  numerous  articles  which  could  only  be  done 
previously  with  rubber.  These  articles  are  perfectly  transparent,  provided  care  has 
been  taken  after  making  them  to  keep  them  in  an  oven,  or  in  a  hot  chamber,  for  a 
sufficiently  long  time  for  the  vapours  disengaged  by  the  chloride  to  escape.  They 
resist  atmospheric  influences,  acids,  and  weak  alkalies;  but  they  are  brittle,  and 
emit  a  peculiar  odour,  from  which  it  is  difficult  to  free  them.  All  vegetable  oils 
may  be  used  in  the  making  of  these  substitutes,  but  linseed,  rapeseed,  earthnut  and 
colza  oils  are  preferred.  Sometimes  the  action  is  moderated  by  the  use  of  a  solvent 
for  both  the  oil  and  the  sulphur  chloride.  One  hundred  Ib.  of  the  oil  are  mixed 
with  4  gallons  of  benzoline,  and  there  is  added  a  mixture  of  25  Ib.  of  sulphur 
chloride  in  2  gallons  of  benzoline.  The  work  should  be  done  in  a  closed  vessel 
provided  with  a  stirrer,  and  the  sulphur  chloride  should  be  added  only  in  small 
quantities  at  a  time.  Some  heat  is  generated,  which  causes  the  petroleum  spirit 
to  vaporise,  whilst  a  little  gentle  heat  at  the  end  is  sufficient  to  drive  off  the 
remainder.  These  sulphur  chloride  substitutes  are  generally  of  a  pale  yellowish 
colour,  rather  spongy  in  texture.  They  contain  but  little  free  oil  and  no  free 
sulphur.  They  work  with  the  rubber  better  than  do  the  oxidised  substitutes 
previously  described. 

Oils  vulcanised  by  flowers  of  sulphur. — Rubber  substitutes  made  from  sulphur 
chloride,  as  we  have  just  seen,  are  colourless,  and  in  texture  in  no  way  resemble 
commercial  rubber.  Their  manufacture  is  also  delicate,  and  liable  to  very  frequent 
failures,  due  principally  to  the  too  energetic  action  of  the  chloride  upon  the  oil 
in  presence  of  however  slightly  elevated  a  temperature.  It  has  been  found  possible 
to  overcome  this  difficulty  by  the  direct  vulcanisation  of  linseed  oil  by  flowers  of 
sulphur,  which  produces  a  black  substance  approaching  more  nearly  to  the  natural 
colour  of  rubber,  which,  by  its  slower  and  more  gradual  elaboration,  avoids  the 
innumerable  accidents  of  a  reaction  accomplished  too  rapidly.  This  substitute, 
which  at  the  present  day  has  in  the  greatest  number  of  instances  displaced  oil 


RUBBKR    SUBS'!  H  t'THS 

rolcanifl&d  h\  chloride  ..i  sulphur,  i>  prep.ir.-d   i  I   M  •  •  d    d  j>revioiwly 

heated  to  a  temperature  of  100°  ('.,  i»  intimately  mixed  \\nh  :.  \,,  10  per  cent.  of 

llouers   «»!'   sulphur,    aceording    t<»    tin-    objee-  .    then    heated  gradual  I. 

temperature  of  about    !•"•"    Q  i-'WF.).     Tin-  mixture  rapi«lly  turn*  brown,  and 


when  it   h;i>  -"t   to  the  de-in-d  temperature  and   acquired  a  \er\    pr»inHinerd 

consistency,  it  i>  left  to  itself,  \\ithuut  h«>\\c\,-r  aflowmg  the  femp6fmtare  to 

below    KMI     0,    (212     I''.).      Vulcanisation    is    kn»\\n   to   U-    Implied    bs    th- 
l»r.i\\n,  almost   black,  colour  of  the  ma^,  and  its  0T6f  inciv.t>ing  thickn.-^.      At  thi* 
pnint  tin-  pr«»ce^  is  conducted  in  the  >ame  way  its  in  the  e;isc  of  chloride  ..f  -ulpliur 
substitute-.     That  is  to  say,  the  vessels  are  emptied  mi  smooth,  «-.,ld  surfaces  so  as 
to  be  able  to  detach  the  product  after  complete  cooling.      In  making  rubU-r  -ub-tj 
tutes  tV.nii  nun  tlryinu  oils,  the  f«i||i»\\iii^  turmiila  has  been  given  :  —  Take  100  Ib. 
good  Stettin  col/a  oil,   mix   it    intimately   with    1  ~>   11).  of  flo\\ 
gradually  heat  the  mixture  \\ith  freipu'iit  stirring  t«»  a  temperature  of  about  .".« 
until   a   dark  coloured,  almost   so  lid,  mass  is  obtained.      On  e.x.ling   the   -uUtitute 
is  of  a  rubber-like    character,  but   devoid   of   the    same    elasticity    and    t. 
characteristic   of  rubber.      During   the    process    part    of   the    sulphur    enters    into 
co  ml.  inatiou  with  the  oil,  part  remains  free.      It  is  desirable   that    the   free  sulphur 
should  be  very  small.     The  average  amount  is  L'-.~>  J*T  cent.  ;   when  the  amount 
reaches   5   per  cent,  it  becomes  objectionable,  as  it  tends  to  produce  di-; 
goods. 

llnlfar  substitute  from  maize  oil.  —  The  manufacture  of  rubier  Hubrtitutaa  ifl 
such  a  simple  matter  as  to  lie  easily  within  the   means  of   factories  of  ordinary 
capacity.      It  is   assumed  that  the  factory  has  the   ordinary  con\eniences,  and    is 
piped    for   illuminating  gas,   for  in  the  manufacture  of  "hlaeksub"  great  heat 
is  important,  and  is  supplied  by  gas  quickly  and  economically.     A  tank  of  boiler 
iron   should  be  provided,  cylindrical  in  shape,  capable  of  holding   one   or  more 
barrels  of  corn  oil,  and  placed  so  it   may  be  tilled  at  its  top.     Such  a  tank,  located 
in  the  factory  basement,  could  be  filled  from  barrels  on  the  main  Hoor  with  little 
trouble  or  waste  by  placing  the  tank  immediately  beneath  the  Hour,  which  had 
been  provided  with  a  small  hatchway  or  trap-door.     The  tank  should  U-  pn»\ided 
with  faucet  for  drawing  oft*  oil  as  required,   or  it  may  be   pi|»ed   directly   to  the 
kettle  tor  boiling.      Gas  jets  should   be  arranged  around  the  base  (.f  this  tank,  so 
that  its   contents  can  be  heated  in  advance  of  use.      Thi>   i-  simply  economy  in 
time.      Within  convenient  distance  of  the  tank  should  be  another  dust- 

jets  in  a  chamber  shut  in  at  the  sides,  ,,j>i-n  at  the  top,  pr..|«erly  e««n-trueted, 
and  of  a  strength  to  sustain  a  kettle  having  a  capacity  of  8  gallons.      Still  another 
cluster  of  gas  jets  should  be  provided  over  which  sulphur  can   be  melted.      A  No 
a  cooling  box,    '2   by   :*    by    ^    feet,    constructed  of    wood.     The    apparatu 
consists   <.f   a   boiler   iron  tank  for  holding   the  supply  of  corn  oil,  a   heat 
boiling  the  oil,  a  heater  for  melting  sulphur,  and  a  cooling  1».,\.      T\\"  -tn-ng  men 
are   required  t»  handle  the  work   pro|>erly.     Eight  gallons  of  corn  oil  are  drawn 
on"  from  the  tank,  and    L'OJ  Ib.    of   sulphur  weighed   into   a    large   dipl-er.    and  each 
(.laced  over  its  respective   heater.      The  oil,  having  been    previously  heated,  attain- 
the  boiling-i»oint  quickly,  and  for  thirty  minutes  should  IK-  kept  at  a  temj-eiature  of 
470°  F.,  and  constantly  stirred.      The  sulphur,  being  now  melted,  i-  added  to  the 
boiling  corn  oil.      It  must  be  added  hot  to  present    cr\  -tallisatinu.      The  workmen 
must  be  prepared  for  prompt   and   skilful  action  at   this  jM>int.  for  no  sooner  d«-r> 
the  sulphur  mix  with  the  boiling  oil    than   the  contents  of  the   kettle  ri>e  rapidly, 
and     before    it     can     boil    .,ver    must    be    removed    and    emptied    into     tl  ......  H.hm: 

box,    where    it    may    be   stirred.        When    cold    it    U   dumj>ed    ii|»on   and 

large  el.it  h>.  or  placed  in    pans    reads    f..r    u--,  as   convenience   or   necessity  suggest 

In  this  manner  black  substitute  is  manufactured. 

The  boiling  \\ill  reduce  the  quantity  -omeuhat.  WJ  -  |"-r  ecnt..  and  fp-m  a 
\\eight  oi  h'.i;  Ib.  material  a  batch  should  result  weighing  aUut  «'•*  H>.  It  \\ijl 
be  noted  that  something  over  11  j.er  cent,  of  sulphur  i-  required  to  make  tin- 
substitute,  while  to  oxidise  (vulcanise)  cottonseed  oil  or  rai«seed  oil  requiio 


264  INDIARUBBER 

but  26  per  cent.     A  recipe  which  has  been  given  for  making  sulphur  chloride 
substitute  from  rapeseed  oil  is  as  follows  : — 

Rapeseed  oil  .            .             .  .                      \  gallon. 

Benzine  .             .  .             .             .  .             .                      1       ,, 

Sulphur  chloride  ...  .14  ounces. 

Magnesia             .  .             .             .  .             .  -in 

The  above-described  rubber  substitutes  are  sometimes  employed  alone  in  the 
manufacture  of  waterproof  cloth,  water  pipes,  etc.  ;  sometimes  in  combination 
with  natural  supple  rubber  for  all  other  industrial  uses. 

But  another  substance  likewise  enters  in  considerable  quantity  into  the  class 
of  rubber  substitutes  and  imitations,  namely,  vulcanised  rubber  waste  from  the 
making  of  industrial  objects  or  the  rubbish  of  the  trade,  and  which  constitute  the 
real  rags  of  rubber  articles.  The  Americans,  who  excel  in  the  utilisation  of  this 
kind  of  substitutes,  reclaimed  rubber,  consume  enormous  quantities  of  rubber 
waste,  and  produce  from  it  really  admirable  articles.  The  processes  for  utilising 
this  waste  have  already  been  given,  and  it  would  be  simply  repetition  to  return  to 
them.  The  attention  of  manufacturers  is  called  to  this  lucrative  branch  of  the 
trade.  The  rubber  substitute  Dertnatine  was  said  to  be  discovered  by  Maxim 
Zingler,  and  recognised  as  such  in  England  and  Germany  since  1885.  This  sub- 
stitute is  a  simple  mechanical  mixture,  agglomerated  by  heat  and  pressure,  of 
supple  rubber  waste,  textile  fibres,  leather  shavings,  and  carbonate  of  magnesia, 
and  identical  with  the  vegetable  ivory  which  Eugen  Turpin  presented  to  the 
Societe  d'Encouragement  in  July  1877,  a  report  on  which,  by  M.  Cloez,  appeared 
in  the  "Bulletin"  of  that  Society  (1877,  p.  559).  The  product  may  interest 
certain  manufacturers. 

Notwithstanding  the  cheapness  of  substitutes,  the  favour  in  which  they  are 
esteemed  in  the  majority  of  manufactories  is  a  subject  for  regret,  because  they 
are  far  from  adding  anything  to  the  value  of  the  mixtures  into  which  they  enter. 
A  method  of  analysing  qualitatively  and  quantitatively  a  supple  rubber  loaded 
with  substitutes,  as  well  as  the  substitutes  themselves,  is  therefore  a  necessity. 
Dr.  Robert  Henriques,  already  quoted,  has  published  a  series  of  researches  on 
this  subject,  as  novel  as  they  are  interesting,  in  the  Chemiker  Zeituny  (1892, 
1893,  and  1894),  reproduced  by  the  Moniteur  Scientifique  de  Quesneville  (4th 
Series,  VII.,  September  1893,  and  VIII.,  August  1894).  This  research  throws  a 
new  light  on  the  analysis  of  supple  rubber,  and  also  familiarises  us  with  the  study 
and  intimate  knowledge  of  substitutes  : — 

Contribution  to  the  analysis  of  manufactured  rubber  and  the  detection  of 
substitutes  (R.  Henriques). — The  analysis  of  manufactured  rubber  is  amongst 
the  most  complex  analytical  problems  which  the  technical  chemist  may  be  called 
upon  to  solve.  The  determination  of  mineral  substances  used  as  make-weights, 
already  difficult  enough,  becomes  almost  impossible  when  it  is  a  question  not  only 
of  ascertaining  the  proportions  of  the  different  oxides  used,  but  also  the  form 
under  which  they  were  incorporated  with  the  rubber.  These  difficulties  are 
still  further  increased  when  it  is  desired  to  estimate  the  vulcanisation  sulphur, 
because  none  of  the  published  methods  are  reliable.  Not  the  slightest  indication  is 
given  in  regard  to  the  separation  of  the  rubber  from  the  make-weights  of  organic 
origin  and  substitutes ;  it  would  appear  that  no  chemist  has  dared  to  enter  this 
domain.  Moreover,  this  is  not  a  matter  for  surprise ;  the  substances  in  question 
consist  of  an  assemblage  of  bodies  whose  properties  are  badly  known,  which  are 
about  equally  indifferent  to  all  reagents,  and  which  do  not  represent  homogeneous 
chemical  combination,  but  complex  mixtures,  like  rubber  itself,  of  dissimilar  com- 
pounds. Having  had  to  make  numerous  researches  in  this  difficult  path,  Henriques 
was  led  to  study  a  series  of  methods  which  appeared  to  remove,  at  least  in  part, 
the  analytical  difficulties  referred  to ;  and  although  this  research  may  be  far  from 
throwing  complete  light  on  the  obscure  chemistry  of  rubber,  it  may  be  useful  to 
those  who  may  be  occupied  with  similar  questions,  and  contribute  to  augment  and 


RUBBER   SUBSTlTU'l 

improve  the  literature  pertaining  to  tliis  industry.  \\hich  liithn-t..  »nly  promt*  but 

meagre  document*. 

Difficulties  in  obtaining  «  /•///•  averayt  The  taking  of  Dimple*  for 

ySLB  l>  ;tt  the  outset  tin-  I'nM  dilliculty.      Manilla.  t  HIT.  I  rubU-r  U  nut  ir 
bDfflOgeneOUS  substance,  -.tenor  aspect   mi^ht      ij.--    •      • 

of  manufacture  of  which  it  is  tin-  product  readily  explain  it>  h.  ! 

ally  tin-   heated    an«l    pla.stic  rul.l.rr   is    mixed  \\ith   sulphur   ami   "tli,-r    .ub-t.tiiceB; 
tin-   moulded  paste  is  trt-at.-,!   \\ith  >u[»erheated  steam.     The  masses  of  mineral 
b..dies  ob.ser\ed  ..n  cutting  are    tin-    natural  consequence  of    this  incomplete  n,.  • 
of  mixture.      Henri.  pies  analysed  a  large  sheet  of  pliant  rubb.-r.  containing  am- 
other  substances  a  rather  large  percentage  of  sili.-...  .ire  was  taken,  the 

analysis  yielded  \(-ry  di\ergent   results  :  at  One  time,  a  I  M.I  it   In  jn-r  c.-ni.  -.1  >;•>,;  at 
another  time,  L'S  per  cent.  ;   \\hilst,  at  still  anothn-  time,  only  \'\  |-  r  OBBt      It  was 
only  afhT  taking  an  avrra^r    .sample   throughout  tin-  \\li«»le    m.i->,  by  mtti: 
along  the  axis  and  diagonals  of  the  sheet,  and  afterwards  dividing  these  .strips  im<. 
small    fragments,  and   thoroughly  mixing  the  whole,  that  concordant  remJu  were 
obtained.     Hcnriques  used  the  same  method  for  ebonite,  by  tiling  with  a  rough  til.- 
likewise  in  the  direction  of  the  axis  and  diagonals  of  the  piece  to  be  analysed.     If, 
at  the  outset,  such  variations  are  observed  in  regard  to  the  pulverulent  tiller*,  how 
niueh  more  must  they  increase  when  the  substances  are  coarse,  sueh  a-  fr.i^n 
of  glass,  shavings,  or  cuttings  of  metal,  which  are  frequently  encountered!     I1 
then,  so  to  say,  iuq>ossible,  unless  by  previously  disintegrating  the  \vh<>l«   piece,  to 
obtain  a  satisfactory  average  sample. 

The  conclusions  to  be  drawn  are  therefore  :  — 

(1)  In  the  analysis  of  rubbers  it  is  always  desirable  to  start  with  as  copi..us 
samples  as  possible,  and  to  prepare  therefrom   the  average  simple  \\hieh  LB  to  be 
tested  with  as  great  care  as  possible. 

(2)  Care  must  be  taken  not  to  conclude,  from  the  analysis  of  small  samples  of 
goods,  that  the  analysis  of  the  bulk  is  identical  therewith. 

1.  Ash.  —  The  determination  of  the  ash  is  always  recommended  as  the  basis  of 
all  analyses  of  rubber.     In  my  opinion,  this  determination  teaches  nothing  in  t  la- 
majority  of  cases;  at  the  most,  it  is  only  useful  in  tin-   preliminary  examination 
of  containing  only  a  small  amount  of  mineral  bodies.1      Hut  then  then-  is  nothing 
to  show  that  ignition  has  not  eliminated  carbonic  acid  nor  volatile  metallic  -.alt>, 
reduced  sulphates  to  sulphides,  sulphuretted  oxides,  or,  finally,  burned  free  carbon, 
Several   writers   have   already    pointed    out    ditliculties    in    the   a>h   determinat; 
but   some   try  to   cope  with    these   by  careful    ignition,    others,  l>y  addition   of 
ammonium  nitrate  or  carbonate  —  processes  which  might  IHJ  of  use  in  particular 
cases,  but  which  are  no  more  capable  than  the  rough  determination   of  grnn-.il 
application.      In    any   case,  a  separate  heading  has   been    given    to   the   a>h,    the 
bearing  of  which  is  most  often  nil.     For  the  quantitati\e  analjrifl  oi   the   mil. 
substances,  the  previous  estimation  of  the  ash  is  of  no  use.      Kven   for  qualitathe 
analysis,  Henriques  only  used  it  with  hesitation,  Urause  it    is  dilhVnlt  t«>  carry  "Ut 
in  a  porcelain  crucible  (clinkering  of  the  sul»tance),  and  the  presen-  :  un 
bodies,  litharge,  for  instance,  does  not  allow  of  it  being  informed  without  risk  in 
a   platinum  crucible.      Henriques  always  detennined  the  mineral  matter   simul 
taneously  with  the  sulphur,  as  in  No.  2. 

2.  Kulj.hiii-   <l't>  nnuintioii.  —  To   determine    total    sulphur,    it     is    generally 
recommended  to  unite  the  rubber  with  soda  and   saltpetre,  with   the  addition  "I 
ammonium   or    magnesium    nitrate.        In    whatever    way     Henri.  pies   applied    the 
method,    he    \\iis   never  al>le  to   obtain    concordant    results.      If    the    nitrate-    U- 
insufficient,     the    rubber    burns.     partialK.    \\ith    a    luminous     tlaine,    and    a    mm 
ueglectable  portion  of  sulphur  is   dissipated   with   the  ignition   products.      If  the 
dose  of  ammonium  nitrate  be  I'.-ived,  the  combn>ti..n  i-  .1-  ••    mpanied   by  i  series  of 


1  This  does  not  apply  to  tin-  analysis  of  raw  rubber,  and   tin-  rubbers  called  jmn  Para, 
which  only  contain,  hrsid.s  n  small  .|iiaiitity  of  ash,  sand,  aliuiiin  •  »»d  tsome- 

times  a  small  proportion  of  lime.     The  determination  of  the  ash  is  then  quite  necessary. 


266 


INDIARUBBER 


small  explosions,  and  it  is  difficult  to  avoid  loss  by  projection.  Even  when  the 
rubber  is  introduced  into  the  fused  oxidation  mixture  in  very  small  fragments,  it 
is  difficult  to  avoid  loss  by  deflagration.  But  Henriques  obtained  very  good 
results  by  oxidising  the  rubber  with  nitric  acid,  and  finishing  the  combustion  by 
fusion  with  nitrate.  Oxidation  by  nitric  acid  to  the  point  where  the  addition  of 
water  no  longer  yields  a  precipitate  is  not  enough,  for  with  barium  sulphate  the 

insoluble  salts  of  the  organic  acids 
separate,  and  the  calcined  sulphate 
shows  an  alkaline  reaction.  It  is  to 
destroy  these  organic  acids  that  it  is 
necessary  to  thoroughly  finish  the 
nitric  acid  oxidation  by  an  oxidising 
igneous  fusion. 

Henriques  fixed  a  reversed  funnel 
— the  shank  of  which  had  been  cut  off 
near  the  neck — over  a  deep  porcelain 
capsule,  and  poured  into  this  capsule 


Flu.  103. — Battery  of  extractors  for  extracting 
resin,  etc.,  from  rubber  (Altmann,  Berlin). 


FIG.  104. — Autoclave  used  by  Dittmas 
in  analysis  of  rubber. 


20  c.c.  of  pure  fuming  nitric  acid  (in  the  case  of  rubbers  containing  but  little  mineral 
matter,  ordinary  60  per  cent,  acid,  specific  gravity  1  '42,  is  sufficient),  and  into  the 
acid,  which  is  kept  hot,  by  the  orifice  of  the  funnel,  3  to  4  grammes  of  the 
substance,  cut  up  into  very  fine  pieces,  waiting  before  each  addition  until  the 
brisk  reaction  produced  has  subsided,  were  introduced.  When  the  reaction  is 
particularly  tumultuous,  it  is  well  to  take  the  precaution  to  stop  the  upper 
aperture  of  the  funnel  by  means  of  a  second  smaller  funnel,  the  stem  of  which,  cut 
off  at  the  neck,  should  riot  dip  into  the  liquid.  ^- 


RUBBER   SUBSTITUTES 

The  lirst  decomposition  terminated,  the  whole  is  evaporated  u'cntlv,  on  the 
water  bath,  to  a  >\rupv  OOBUfltency.  Ten  to  20  C.C.  of  nitric  acid  a^ain  added, 
and  the  bulk  reduced  to  the  same  extent.  TO  the  highly  concentrated  liquid,  add 
I  grammes  of  a  mixture  of  ."»  parts  i.f  [K)tassium  nitrate  and  I  parts  of  calcined 
soda,  sodium  carbonate.  The  uln»|e  is  dried  and  cautiously  ignited  until  tranquil 
fusion  is  etlected.  The  mass  .-dioidd  not  be  too  alkaline,  so  as  not  to  attack  the 
enamel  of  the  capsule,  nor  dissolve  appreciable  quantities  of  silica,  alumina,  and 
lime,  which  would  ati'ect  the  results  of  the  analysis.  With  rubbers  charged  \sith 

prolonged  fusion  is  required  to  burn  off  the  carbon.1     The  fused  mass  IB 

in  hydrochloric  acid,  evaporated  to  dryness,  to  render  >ilica  insoluble, 
^solved  in  nitric  acid.  If  all  dissolves,  il  U  diluted  to  a  known  volume 
sulphur  estimated  in  an  aliquot  part,  and  the  remainder  used  for  the 
atiou  of  the  mineral  matter.  If  a  residue  remain,  it  can  only  COHMM  of 
silica,  barium  sulphate,  and  lead  sulphate.  It  is  digested  with  a  fresh  solution  of 
ammonium  acetate  (obtained  by  supersaturating  ammonia  \\ith  H)  per  cent, 
acetic  acid).  The  lead  sulphate  dissolves  quickly  and  completely.  The  insoluble 
portion  is  collected  on  the  same  lilter  through  which  the  nitric  acid  solution  was 
passed,  to  Avhich  the  fresh  liquid  is  added.  If  cloudiness  ensue,  which  i- 
frequently  the  case,  it  is  made  to  disappear  by  the  addition  of  25  to  30  c.c. 
of  nitric  acid.  It  is  diluted  to  a  known  volume,  and  the  sulphur  and  oxide- 
estimated  as  above. 

There  now  only  remain  the  residual  insoluble  silica  and  barium  sulphate, 
which  are  separated  by  known  methods.  If  barium  sulphate  be  found  in  the 
residue,  sulphuric  acid  or  baryta  may  be  found  in  the  liquid,  according  as  sulphur 
or  baryta  predominated  in  the  rubber.  This  method  has  always  given  exact 
results,  both  for  total  sulphur  and  metallic  oxides.  When  a  rubber  leaves  little  or 
no  ash  on  the  preliminary  incineration,  and  if  it  be  only  required  to  estimate  the 
sulphur,  it  will  suffice  to  operate  on  0'25-0'5  gramme  of  substance.  Sulphur 
may  also  be  estimated  by  Carius'  process;  but  on  account  of  the  time  required 
to  seal  the  tubes,  and  the  risk  of  rather  frequent  explosions,  when  more  than 
0'2  to  0'3  gramme  of  substance  is  operated  on,  it  is  preferable  to  operate  as 
described.  To  ascertain  the  quantity  of  sulphur  employed  in  vulcanisation, — not 
only  the  sulphur  which  serves  for  vulcanisation,  but  also  the  sulphur  in  e.v 
remaining  in  the  free  state  in  the  mixture, — it  is  necessary  to  deduct  the  total 
sulphur  which  may  exist  as  sulphate  and  sulphide.  Of  all  methods  proposed  for 
this  purpose,  only  one  is  reliable:  dissolving  the  rubber  and  the  free  sulphur  in 
spirits  of  turpentine.  This  method  yields  accurate  results,  but  is  very  long  and 
inconvenient  The  rubber  must  be  digested  in  spirits  of  turpentine  for  six  to 
ei-ht  days,  at  a  temperature  of  60°  to  70°  C.  (140°  to  158°  F.).  Moreover,  this 
period  does  not  always  suHice.  The  end  is  accomplished  more  quickly  by  heating 
the  spirits  of  turpentine  to  boiling,  the  sample  is  then  dissolved  in  one  or  t\\o 
days;  but  at  that  temperature  sulphur  acts  on  spirits  of  turpentine,  and  the 
sulphuretted  hydrogen  which  is  formed  may  act  on  the  metallic  oxides  present  and 
metamorphose  them  into  sulphides,  thus  giving  rise  to  erroneous  results.  But 
these  are  not  the  only  drawbacks  of  this  method.  It  is  not  economical,  on 
account  of  the  large  quantity  of  spirits  of  turpentine  required ;  and  the  nitration 
of  the  solution  is  always  difficult,  sometimes  impossible.  With  a  sample  of  rubber 
highly  charged  with  zinc  oxide,  Hemiques  was  not  able  by  any  scheming  to  obtain 
a  limpid  solution.  The  operation  is  always  so  protracted  that  the  spirits  .of 
turpentine  partially  resinities  on  the  sides  of  the  lilter,  and  it  becomes  \ery 
difficult  to  remove  it  by  lighter  solvents,  such  as  ben/inc.  carbon  disulphide,  etc. 
lleitriques  therefore  sought  a  substitute  for  spirits  uf  t  ur|  cut  ine,  and  found  it  in 
ordinary  well-rectified  petroleum  spirit.-  Heated  above  the  melt  im:  point  of 

sulphur,  petroleum  -pirit  easil\  dissolves  \ulcani>ed  rubber.     Solution  is  completely 

1  Cut  few  chemists  would  make  or  recommend  a  MHUI.  far  le»  a    prolonged,  alkaline  i'usi<m 
in  a  porcelain  vessel. 

"  Petrole  ordinaire"  of  the  author's  is  taken  to  mean  ".spirit." — Tu. 


268  INDIARUBBER 

effected  in  oue  or  two  days.  It  will  be  observed  that — 1.  Commercial  petroleum 
spirit  often  contains  a  little  sulphur,  from  which  it  is  freed  by  repeated  agitation 
with  caustic  soda,  drying,  and  rectifying,  collecting  the  portions  passing  between 
140°  and  150°  C.  (284°  and  302°  F.).  2.  If  the  temperature  rises  above  a  certain 
limit,  petroleum  may  be  attacked  by  sulphur,  but  Henriques  found  that  the  action 
of  sulphur  on  petroleum  spirit  may  be  neglected  up  to  about  150°  C.  (302°  F.). 
To  avoid  this  error,  it  is  only  necessary  to  work  below  this  limit.  Five  grammes 
(in  the  case  of  but  slightly  charged  qualities,  10  to  15  grammes)  of  the  sample  arc 
weighed  into  a  tared  ^-litre  flask  and  150  c.c.  of  purified  petroleum  spirit  added, 
and  the  whole  heated  in  an  oil  bath  at  140°  to  150°  C.  (284°  to  302°  F.)  until  the 
rubber  is  disintegrated  and  dissolved,  and  the  insoluble  portions  are  deposited  in 
the  purverulent  state.  As  control,  a  second  flask  is  installed  alongside  the  first, 
containing  petroleum  spirit  and  sulphur,  in  which  the  disengagement  tube  dips 
into  a  small  wash-bottle  containing  acetate  of  lead.  If  the  solution  of  lead  does 
not  blacken,  it  may  be  taken  that  the  temperature  has  not  exceeded  the  proper 
limit.  Solution  effected,  it  is  allowed  to  stand  in  a  warm  place,  and  the  liquid  is 
decanted  through  a  tared  filter,  washing  once  or  twice  by  decantation,  and  then  the 
residue  is  finally  run  on  to  the  filter ;  the  flask  is  again  washed  with  hot  petroleum 
spirit,  and  the  washings  filtered  without  detaching  the  insoluble  particles  adhering 
to  the  glass ;  the  washing  is  finished  with  petroleum  ether  (gasolene),  the  flask 
dried,  and  filtration  done  at  110°  C.  (230°  F.).  The  estimation  of  sulphur  in  the 
insoluble  portion  gives  the  amount,  and  qualitative  and  quantitative  analysis 
determines  the  form  in  which  the  sulphur  exists.  The  difference  between  the 
total  sulphur  and  that  found  in  the  residue  gives  the  sulphur  added — i.e.  (1)  the 
amount  of  sulphur  used  in  vulcanisation  and  (2)  the  free  sulphur.  It  is  necessary, 
however,  to  remove  a  possible  error :  the  presence  of  oxidising  agents,  such  as 
litharge,  alkaline  earths,  or  carbonates,  may  have  rendered  a  portion  of  the  sulphur 
insoluble  by  transforming  it  into  sulphates  or  sulphides.  Thus,  Henriques  found 
in  a  rubber,  along  with  much  chalk  and  oxide  of  lead,  a  small  quantity  of  gypsum. 
It  is  scarcely  possible  that  this  salt  was  mixed  in  its  natural  state  with  the 
rubber,  and  it  was  more  likely  generated  during  vulcanisation  itself.  That  is  a 
point  upon  which  chemical  analysis  alone  cannot  decide.  The  insoluble  residue 
may  be  used  for  the  quantitative  analysis  of  metallic  oxides,  but  it  lends  itself 
especially  to  a  proximate  analysis  for  the  purpose  of  ascertaining  the  precise  form 
under  which  these  oxides  have  been  employed.  In  the  great  majority  of  cases,  not 
only  can  the  total  composition  of  a  rubber  be  ascertained,  but  also  the  nature  and  the 
proportions,  and  even  the  degree  of  fineness,  of  the  salts  employed  in  the  manufacture 
of  the  rubber  in  question.  To  determine  the  proportion  of  organic  matter  undis- 
solved  by  petroleum  spirit,  different  methods  are  pursued,  according  to  circum- 
stances. If  all  the  metals  have  been  determined,  and  all  the  latter  give  stable 
sulphates  on  ignition,  the  simplest  method  consists  in  calcining  an  aliquot  part  of 
the  residue  with  sulphuric  acid.  The  proportion  of  organic  matter  burnt  is 
calculated  from  the  weight  of  the  sulphates  and  that  of  the  salts  from  which  they 
originated.  The  organic  matter  can  also  be  deduced  from  the  difference  between 
the  total  residue  and  the  total  weight  of  the  salts  of  which  it  is  composed.  If  the 
latter  be  soluble  in  an  acid,  that  again  furnishes  a  convenient  method  of  separating 
the  insoluble  organic  matter ;  it  is  the  method  used  to  separate  metallic  salts  from 
graphite,  so  often  met  with  in  door  and  stair  mats.  It  is  rare  that  pliant  rubber 
leaves  a  residue  insoluble  in  petroleum  spirit.  Those  which  contain  substitutes 
sometimes  dissolve  with  difficulty,  but  substitutes  can  be  so  separated  that  the 
remainder  of  the  rubber  dissolves  without  difficulty.  This  vehicle  likewise  dissolves 
the  other  organic  substances,  fatty  oils,  paraffin,  asphaltum.  As  to  the  insoluble 
organic  matter,  e.g.  cork  powder,  sawdust,  etc.,  they  have  only  a  potential  existence 
hi  technical  treatises  dealing  with  rubber  and  its  applications.  Henriques  never 
met  with  them  in  any  of  the  samples  from  every  source  which  he  analysed.  But 
there  is  an  important  group  of  manufactured  rubbers  which  do  not  dissolve  in 
petroleum  spirit,  namely,  the  ebonites,  which  offer  the  greatest  resistance  to  all 


RUBBER   SUBST1TI"! 

chemi<  -;il  reagents.  These  are  dealt  with  in  the  sequel.  The  courae  of  hw  rv 
led  lleuriques  to  ex^'riim-nt  on  tl..-  wpantbn  of  rubU-r  from  organic 
i-hN.  lii  chemical  literature  hut  sarse  and  inconclusive  indication* 


make  uei-hN.      lii  chemical  literature  hut  sparse  and  inconclusive  indication*  are 

fiiiiiiil  nn  this  jNiint.  although  the  use  o!'   mi  itut.-.  imitation*,  and  r, 

make  \sei^ht>  i>  iiioxi    extensive,      There    U    n.,t    .,    ,-l.i.s.s  of   natural  \\lii.-li 

h;i^  not   been  tried  I'm-  this  purpose  ;   hut  tin-  more  tin-  properties  ami  tin-  durability 
of  rulil.  .'indited  \\ere    Mudied,  tin-    more  \\.i-    their   niaiiut'ai-liire   .il,.u.. 

It   \\niilil  appear  that   n«»w  only  one  r|as.s   of  organic   coinjMMimU  play  an  iin; 
n",|e  in  (h,-  industry.      These  are  tin-   products  sold   under  the  name  of  mi.!» 
stitutes,  artificial  rubl)cr,  or  imitation  nil.  her,  made  l,\   heating  oiU  \\itli  -.ulj.hur  «.r 
sulphur  diloi-ide.      Some  non-sulphuretted   sul^tituten,  made  by  "xidi-in^'  .. 
also  encountered.     This  category  of  com]  winds  ap|N>aivd  to  Henrique-  to  U 
exaniiiiiu^.     Substitutes  are  generally  mrt   with   in  the  form  of  yellow  or  l,|-,,\\n 
elastic  masses,  without  cohesion,  breaking   up   under   prOMTO,  '-'''••  i-\    l&d    n  .••:••  • 
the  touch.     Two  of  these  substances  gave  the  following  reunite  :  — 

TABLE  LXIX.  —  MOISTURE,  SULPHUR,  AND  AMI  IN   RUBBER  SUBSTITUTES. 


I. 

11. 

Moisture  ...... 
Sulphur  ...... 

TOO 

li'17 

0-85 
6*4 

Ash  

:,  B  i 

0*8 

The  ash  consisted  of  lime,  alumina,  with  traces  of  iron  oxide  and  silica.  Sob- 
stitutes  )>ehave  towards  solvents  almost  like  rubber  itself;  in*..lubl«-  in  alcohol, 
they  only  dissolve  with  difficulty  and  incompletely  in  benzol,  carbon  disnlphide. 
ami  spirits  of  turpentine,  etc.  To  detect  oils  or  fats  in  manufactured  rubber,  a 
method  has  been  proposed  which  yields,  in  experienced  hands,  useful  results.  The 
rubber  is  digested  in  carbon  disulphido  to  which  5  per  cent,  of  spirits  of  turjteiitinc 
has  been  added,  the  solution  is  filtered  after  a  few  hours,  and  distilled.  An 
appreciable  residue  indicates  the  presence  of  foreign  bodies  of  a  fatty  nature.  The 
method  has  several  drawbacks  :  first,  vulcanised  rubber  is  slightly  soluble  in  the 
mixture  of  carbon  disulphide  and  alcohol;1  the  exijeriment  is  not  condusi\e  unless 
the  fats  are  present  in  notable  quantity;  finally,  free  sulphur  is  likewise  dU-i-i- 
and  may  give  rise  to  error.  Notwithstanding  these  drawbacks,  for  qualita 
purposes,  the  method,  applied  with  discretion,  may  yield  useful  indications.  For  a 
quantitative  estimation  the  process  cannot  be  adopted,  because  substitutes  only 
dissolve  partially,  even  when  isolated  and  repeatedly  digested  in  alcoholised  carbon 
disulphide.1  The  sorts  which  were  examined,  in  dissolving,  gave  up  from  L'O  to  30  JOT 
cent,  of  their  weight,  and  on  each  treatment  afterwards  still  further  lost  1  to  2 
PIT  cent.,  so  that  it  cannot  be  admitted  that  substitutes  are  insoluble,  and  that 
the  proportion  of  unchanged  oil  or  fat  which  alone  dissolves.  Substitutes  dissolve 
completely  in  petroleum  spirit  at  a  high  temperature,  as  vulcanised  ruhU'r  does 
itself.  Ligroin2  only  dissolves  them  partially.  Aqueous  soda  dissolve.-  them  with 
difficulty  and  incompletely.  The  action  of  alcoholic  soda  will  be  described  further 
on.  HiibFs  iodine  addition  method  seemed  likely  to  yield  indications,  in  it>  way, 
for  rubber  hardly  absorbs  iodine,  whilst  the  sulphuretted  oils  should  readily  tix 
iodine,  like  the  oxidised  oils  which  almost  retain  their  primitive  iodine  value, 
Preliminary  experiment  led  to  this  unexpected  result:  sulphuretted  oils  d<> 
absorb  iodine  and  behave  like  quasi-saturated  compounds.  Henrique*  then  tried 
to  separate  the  sulphur  from  the  substitutes  and  to  isolate  and  weigh  the  reg« 
ated  fatty  acids.  He  treated  the  substitutes  with  alcoholic  soda,  to  which  different 

1  There  is  here  an  obvious  discrepancy  as  to  the  nature  of  the  mixed  solvent,  whether  it  ia 
alcohol  or  "turps"  that  is  added  to  the  CS2.— TR. 

2  Intermediate  between  gasolene  and  petroleum  spirit     Density  070-073  B.P.,  110M200 
C.  (230°-248°  F.).— TK. 


270  INDIARUBBER 

salts  which  ought  to  fix  sulphur  were  added, — salts  of  lead,  mercury,  copper,  and 
zinc ;  but  in  whatever  way  he  operated,  the  fatty  acids,  isolated  from  the  alcoholic 
lye  in  very  variable  quantity,  always  contained  equally  variable  quantities  of 
sulphur.  He  attempted,  without  any  better  success,  to  effect  saponification  HIM  I 
desulplmrisation  in  a  closed  vessel  at  a  high  temperature,  by  replacing  rthylir 
alcohol  by  amylic  alcohol.  However,  it  was  found  by  these  experiments  that 
.substitutes  dissolve  totally  and  without  trouble  in  alcoholic  soda,  and  on  this 
property  may  be  based  at  least  an  approximate  method  of  analysis.  To  effect 
decided  separations  such  as  can,  for  example,  be  done  in  inorganic  analysis,  is 
impracticable  in  this  field.  Results  can  only  be  approximate,  as  we  have  to  deal 
not  with  simple  combinations  but  with  very  complex  mixtures,  like  rubber  itself, 
which  may  contain  substances  belonging  to  different  classes  of  bodies.  The 
following  experiment  shows  that  substitutes,  or  at  least  their  organic  constituents, 
are  completely  soluble  in  alcoholic  soda.  One  gramme  of  substitute  is  boiled  in  a 
flask  attached  to  a  reflex  condenser,  with  an  excess  of  caustic  soda  (7  to  8  per  cent. 
Na2O).  After  a  few  hours  the  alcohol  is  distilled  off,  the  residue  dissolved  in 
water,  and  filtered  through  a  tared  filter.  Weight  of  the  dry  residue  =  0 '041  =  4*1 
per  cent. ;  weight  of  the  ash  =  0 '04 13  per  cent.  The  residue,  therefore,  no  longer 
contains  any  trace  of  organic  matter.  Another  substitute  which  left  no  ash  dis- 
solved without  residue.  On  the  other  hand,  vulcanised  Para  rubber  was  treated 
similarly  (sample  A).1  This  sample  yielded  on  analysis — Ash  =  2 '54  per  cent.; 
sulphur  =7  "12  per  cent.  Extraction  by  caustic  soda  gave — Dry  residue  =  94 '9  per 
cent.;  containing  sulphur  =  2 '75  per  cent.  By  difference  wre  get  in  solution — 
Total  substance  =  5 -10  per  cent.;  less  sulphur  (7'12-2'75)  =  4-37  per  cent. ; 
organic  matter  dissolved  =  0*7  3  per  cent. 

The  result  is  not  quite  so  fine  as  above  figures  would  indicate.  On  incinerat- 
ing the  insoluble  residue  of  the  extraction,  8 '4  per  cent,  of  ash  was  found,  say  7*7 
per  cent,  on  the  original  rubber.  As  the  latter  only  contained  2*54  per  cent,  of 
ash,  we  get,  after  extraction,  an  excess  of  5 '16  per  cent,  of  fixed  substances.  The 
ash  of  rubber,  treated  with  alcoholic  soda,  is  in  great  part  soluble  in  water,  has  a 
strong  alkaline  reaction,  and  contains  sulphates.  It  would  appear  that,  as  a 
result  of  treatment  with  alcoholic  soda,  rubber  fixes  a  certain  quantity  of  alkali 
separated  by  washing.  The  same  occurred  in  all  subsequent  experiments  and  with 
all  varieties  of  rubber.  It  is  not  practicable  to  separate  the  alkali  from  a  rubber 
treated  with  alcoholic  soda  by  boiling  it  with  dilute  acetic  acid,  not  even  with 
hydrochloric  acid.  An  acid  extraction  would,  moreover,  complicate  the  analysis  of 
the  mineral  matter ;  Henriques  gave  that  up,  and  attributed  the  facts  observed  to 
the  formation  of  an  insoluble  salt  of  sodium,  at  the  expense  of  one  of  the  con- 
stituents of  the  rubber.  It  must  not  be  concluded  from  the  fact  that  the  residue 
insoluble  in  alcoholic  soda  was  found  to  contain  5 '16  per  cent,  of  mineral  matter, 
which  did  not  pre-exist  in  the  rubber,  that  the  latter  had  lost  an  equal  quantity 
of  substance,  as  (1)  the  ash  contains  sulphur,  the  weight  of  which  has  to  be 
deducted;  then  (2)  this  sulphur  is  present  as  sulphuric  acid — the  incineration 
having  been  done  in  this  instance,  as  in  every  case,  in  presence  of  ammonium 
nitrate.  For  each  part  of  sulphur  in  the  residue  2  J  parts  of  SOb  must  therefore  be 
deducted.  To  ascertain  the  amount  of  matter  extracted  from  rubber  by  alcoholic 
soda,  it  is  necessary  (1)  to  estimate  the  ash;  (2)  to  estimate  the  sulphur  in  the 
initial  rubber  ;  (3)  to  weigh  the  extraction  residue ;  (4)  to  estimate  the  sulphur 
therein ;  (5)  to  incinerate  it,  and  weigh  the  ash.  To  almost  be  certain  of  the  results, 
it  is  necessary  to  make  each  experiment  in  duplicate,  slight  errors  being  liable  to 
seriously  affect  the  final  result.  Analyses  of  this  nature  are  neither  simply  nor 
easily  executed.  To  ascertain  whether  this  method  gave  reliable  results  and 
yielded  constant  figures,  Henriques  repeatedly  analysed  another  variety  of  Para 
rubber  (sample  B).  The  results  are  given  in  Table  LXX.  :  - — 

1  By  Para  rubber  is  meant  rubber  containing  only  the  sulphur  added  for  vulcanisation,  and 
not  rubber  from  any  particular  source. 

2  All  these  results  are  brought  to  per  cent,  of  the  rubber. 


RUBBER   SUBSTITUTES 


TM-.I  r  I. XX.     I  OF  RBPRAI 

l;.  LI  i  i 


AvALvni  "i     \MK  SAMPLE  or  PARA 

i   t  -  i. 


I 


I! 


III. 


IV. 


I.    Ash           
2.  Sulphur  
3.   KxtiMi'ti'Hi  ivsitlm-   .... 
4.  Ashes  i.f  iv.sidiu-  111. 
5.  Sulphur  "I'  r.-.siiluo  III.     . 
6.   Dissolved  .sulphur    .... 

9*5 

• 

95-40 
8-49 

1'.     ,    •  • 

95:00 
9-02 
4-50 

-,     , 

i'         •  ' 

•      ". 
9-21 
4*85 
5  'IS 

•ot 

•-     1 
9-17 

I'll 

1  "  '  i 

• 

8.  Corresponding  amount  of  S08  . 
9.  Nil/)  in  ashes  (=4.—  1.—  8)    . 
10.  Real  organic  residue  of  extraction 
=  (3.-9) 
11.  Hence  :  there  were  f  sulphur    . 
dissolved              \organic  matter  . 

... 

5-00 

•.•!••   I 

5-00 
3-37 

3-10 
3-31 

n  M 

2-61 

2-70 
8-67 

•'•- 

8-12 

The  agreement  between  the  analyses  is  very  satisfactory.  The  figure*  of  V. 
were  obtained  by  again  treating  the  residue  from  extract!', n  IV.  with  alcoholic 
soda.  Nothing  further  was  dissolved  by  tlu>  second  extraction.  The  anal\ 
conducted  «w  before:  3  to  5  grammes  of  the  substance  cut  into  small  fragment*  won 
boiled  iii  a  flask  attached  to  a  reflux  condenser  (Fig.  103)  for  fight  hours,  with  about 
ten  times  their  weight  of  alcoholic  soda,  containing  6  to  8  per  cent  Na,O.  The 
whole  was  then  diluted  with  water,  and  the  alcohol  boiled  off"  on  the  water  Iwth,  tin- 
residue  collected  on  a  tared  filter,  and  carefully  washed,  dried  at  100°  ('.  <_  1  •_'  I'  i 
until  constant,  and  then  weighed.  The  ash  determination  of  the  residue  was  always 
done  with  addition  of  ammonium  nitrate,  so  as  to  make  sure  of  convert  in;;  all  thf 
sulphur  into  sulphuric  acid.  We  may  conclude  that  vulcanised  rubU'r  of  the  follow- 
ing composition — ash  2'S,  sulphur  9*5,  and  rubber  80*7=100'0  j 
on  an  average  of  alcoholic  soda,  sulphur  5'05  per  cent.,  and  rubber,  3O3  |«-r 

Does  it  follow  from  these  figures  that  the  dissolved  sulphur  existed  in  the  free 
state  in  the  rubber,  and  that  what  remains  in  the  insoluble  is  the  chemically 
combined  sulphur  of  vulcanisation?  Henriques'  experiments  do  not  give  a  j 
reply.  That  different  Para  rubbers  (containing  nothing  but  sulphur  and  rubU-r) 
leave  variable  quantities  of  insoluble  sulphur  on  extraction  does  not  up>ct  this 
hypothesis;  in  fact,  the  quantity  of  combined  sulphur  may  vary  greatly  with  the 
temperature  of  vulcanisation  and  the  whole  of  the  conditions  of  manufacture. 
Samples  A  and  B,  the  analyses  of  which  have  already  been  given,  left— 

TABLE  LXXI.  —  SIH»WIN«:   VAKIATION  IN  RATIO  OP  INSOLUBLE  SULPHUR  TO 
RUBBER  IN  PURE  VULCANISED  r\i:\. 


Per  cent,  of  Ruhher. 

Per  cent,  of  Insoluble  Sulphur. 

A  with  or. 

B     „     87-7 

275 
4-45 

\\ith  reference  to  the  organic  matter  dissolved,  the  proj»ortion  of  which  may 
vary  according  to  the  sample  from  2  to  4  JUT  cent,  it  may  differ  much  in  its 
nature.  It  probably  consists  of  the  vegetable  oils  and  fate  which  all  rubbers 
contain  in  small  quantity.  Another  hypothec  presents  itself  to  my  mind,  namely, 
that  raw  rubber  would  cede  a  i>ortion  of  its  substance  to  alcoholic  soda,  and  that 
the  portions  dissolved  originated  in  the  portions  of  the  ruW>er  which  had  escaped 


272 


INDIARUBBER 


vulcanisation.     The  following  results,  obtained  by  treating  100  parts  of  dry  and 
purified  rubber,  shows  that  this  hypothesis  is  unsound  : — 

TAKU;  LXXII. — EFFECT  OF  TREATMENT  WITH  ALCOHOLIC  POTASH  ON  ANALYSIS 
OF  PURE  DRY  RUBBER  (HENRIQUES). 


Per  cent,  of  Initial  Rubber. 

1.  Ash. 

0-32 

2.  Moisture  . 

0-35 

3.  Extraction  residue 

98-04 

4.  Ash  of  residue  II. 

1-89 

5.  Na20  in  ash  IV. 
6.  Hence  dissolved 

1-57 
3-53 

Alcoholic  soda  dissolves  almost  the  same  weight  of  organic  matter  in  raw  rubber 
as  in  vulcanised  rubber.  With  hardened  rubber  (ebonite,  durci)  analogous  results 
are  obtained.  Henriques  found — 

TABLE  LXXIII. — EFFECT  OF  TREATMENT  WITH  ALCOHOLIC  SODA  ON  ANALYSIS 

OF  EBONITE  (HENRIQUES). 


Ebonite  A. 

Ebonite  B. 

Per  cent. 

Per  cent. 

1.  Ash    . 

o-oi 

O'Oo 

2.  Sulphur      . 

31-20 

40-12 

3.  Extraction  residue 

92-14 

90-94 

4.  Ash  of  residue  III. 

3-87 

6'99 

5.  Sulphur  of  residue  III 

22-60 

29-43 

6.        ,,         dissolved 

8-60 

10-69 

7.        ,,         of  ash  IV. 

0-49 

1-51 

8.    =S03 

1-22 

3-78 

9.  Na20  in  ash  IV. 

1-57 

3-21 

10.  Real  extraction  residu 

e 

90-57 

8773 

11.  Portion  dissolved  |^ 

ranic 

matte 

r 

8-60 
0-83 

10-69 
1-58 

The  portion  of  ebonite  insoluble  in  alcoholic  soda  is  more  difficult  to  extract 
than  in  the  case  of  pliant  rubber.  Thus  sample  B,  after  the  first  extraction  of  six 
hours,  yielded,  on  a  second  extraction  of  the  same  duration,  0*8  per  cent,  of 
sulphur  and  1*47  of  organic  matter.  The  following  analyses  show  how  the  method 
is  applied  to  the  analyses  of  rubber  sophisticated  with  substitutes.  The  insoluble 
extraction  residue  is  treated  with  warm  petroleum  spirit,  in  which  it  dissolves  com- 
pletely ;  it,  moreover,  presents  all  the  characteristics  of  pure  rubber ;  as  the  whole 
of  the  preceding  experiments  render  it  possible  to  predict,  the  separation  of  the 
rubber  from  the  substitute  is  complete. 

What  proportion  of  the  total  sulphur  comes  from  the  substitute  1  What 
quantity  has  been  added  for  vulcanisation  purposes  1  That,  the  method  cannot 
tell  us.  Rubber  substitutes  dissolve  in  alcoholic  soda,  whilst  natural  rubber  cedes 
only  a  minimum  fraction  of  its  ingredients  with  this  restriction,  at  least  in  the  case 
of  the  samples  which  Henriques  was  able  to  procure.  Natural  rubbers  are  so 
various,  and  the  number  of  substitutes  so  great,  that  it  would  be  rash  to  draw 
general  conclusions  from  the  analyses  of  a  few  samples.  Henriques  was  the  first  to 
recognise  that  his  conclusions  would  have  gained  in  precision  if  they  had  been 
controlled  by  the  analyses  of  mixtures,  the  composition  of  which  had  been 
made  known  to  him  by  manufacturers.  He  spared  no  pains  to  secure  this 


RUBBER   5UBSTI1  i   i 

IAKI.I:    I. \.\IV.  -  .\NAM-I.~    m     Ki  i;m.i>   .snriii-i  !•  \m. 

Ill     M     :• 


Quality  A. 

Quality  B. 

PH    but 

i 

1.  Ash    . 

1  '90 

••AA    . 

-ilplmr      

I      IFW 

6-10 

3.  Kxtrartii'ii  iv.sidm-      ..... 

10*60 

--  •; 

4.  Ash  of  ivsi.lur  III  

5.  Sulphur  ul'  ivM.lur  111  

0-66 

6.        ,,         dissolved        ..... 

fii 

1*88 

7.       „        of  ash  IV  

0-29 

O'&O 

8.       „        asSOj,  .... 

0-72 

j  •  1  ;, 

9.  NajO  iu  ash  IV  

s«ia 

1*2 

10.  Kr.il  r\  traction  n->i«luc        .... 

Th.  i  <  has  therefore  (sulphur 
been  dissolved      \orgauic  matter    . 

in 

52-88 

1*88 

There  remains  uu-|sull'hur       ;         '         • 
dissolved                 organic  matter    .         . 

0-66 
1011 

1-90 

2-38 
11-97 

3-00 

TABLE  LXXIVA. — COMPOSITION  CALCULATED  OF  KUBBKKS  WHOSE  ANALYSES 

ARE    GIVEN    IN    TABLE    LXXIV. 


Quality  A. 

Duality  B. 

Rubber     
Substitute         ....... 
Sulphur    ........ 
Ash  

Per  cent. 

1  1  •:{•_' 
51-68 
5-10 
1-90 

Mt 

84-43 
8-31 

3-00 

100-00 

100-00 

control;  but  there  reigns,  to  a  high  degree,  in  the  camp  of  rul.U-r  inanufacturera, 
that  mistrust  and  a  mysterious  way  of  hiding  trifling  things  which  the  rhcmi-t 
still  meets  in  those  branches  of  industry  where  science  has  up  to  now  found  link- 
er no  opportunity  of  seeing  her  services  put  to  the  test 

Amongst  substances  most  frequently  used  in  the  rubber  industry,  a  place  in  the 
first  rank  must  be  given  to  the  compounds  sold  under  the  most  diverse  names, 
which  result  from  the  action  of  sulphur,  or  of  chloride  of  sulphur,  ni»on  oila — 
substances  the  whole  of  which  are  classed  under  the  p-m-rii-  name  of  *n/>ftitute4 
(factices).  Two  chief  sorts  are  known  in  the  trade — the  whiten  and  the  browns; 
and,  in  fact,  these  kinds  are  altogether  ditteivnt  from  a  clifinical  j»oint  of  view. 
In  a  previous  memoir,  Heuriques  had  already  given  an  analysis  of  two  kinds  of 
white  substitutes,  reduced  to  percentage  of  water,  moisture,  and  fixed  ash.  A  more 
thorough  examination  of  these  same  products  has  been  made.  Both  are  slight 
yellowish,  clotted,  elastic  masses,  with  a  neutral  reaction  and  a  slightly  ]*>netrating 
oleaginous  odour.  Water  extracts  nothing ;  acids  and  alkalies  but  little ;  neither 
do  the  majority  of  neutral  organic  solvents.  The  characteristic  of  these  products 
is  their  high  percentage  of  chlorine,  almost  as  high  as  their  percentage  of  sulphur. 
According  to  tin-  1« -haviour  of  the  products  with  solvents,  the  chlorine  should  i 
in  organic  combination.  If,  as  all  facts  indicate,  and  as  the  experiments  detail. •-! 
further  on  show,  the  substitutes  examined  result  from  the  action  of  chloride  of 
sulphur  upon  oils,  that  reagent  has  entered  entirely  (body-bulk),  chlorine  and 
18 


274 


INDIARUBBER 


sulphur,  into  the  molecule  of  the  oil  (fatty  body).  In  order  to  facilitate  the  exphiii- 
tion  of  the  results,  the  analytical  data  upon  which  the  developments  and  conclusions 
of  Henriques'  work  are  based,  are  appended  : — 

TABLE  LXXV. — ANALYSES  OF  COMMERCIAL  RUBBER  SUBSTITUTES 
(HENRIQUES). 


* 

White  Substitutes. 

Brown  Substitutes. 

A. 

B. 

c. 

A. 

B. 

Sulphur  in  the  substitute 

6-4 

6-17 

8-25 

15-48 

17-71 

Chlorine     „          ,, 

5-0 

5-86 

8-88 

0-7 

0-36 

Water         „ 

0-85 

1-0 

... 

Ash 

0-8 

5-51 

Percentage  of  fatty  acids 
Sulphur  in  the       ,, 

90-45 
6-12 

73-58 
6-45 

8  '-15 

14-14 

15:20 

Chlorine     ,,           ,, 

0-83 

0-43 

... 

... 

Iodine  value  of  the  substitute 

30-9 

31-0 

32-6 

42-0 

42-0 

,,               ,,      fatty  acids 

91-3 

91  -a 

102-3 

129-0 

125-6 

TABLE  LXXVI. — ANALYSES  OF  SUBSTITUTES  PREPARED  FROM  VARIOUS  OILS 

(HENRIQUES). 


A. 

B. 

C. 

D. 

E. 

F. 

G. 

H. 

I. 

Sulphur  in  the  substitute      . 

9-34 

478 

8-28 

6-59 

7-68 

4-82 

10-6 

6-23 

Chlorine     „           „ 

8-84 

4-85 

7-62 

5-95 

7-44 

0-70 

8-95 

5-36 

Water 

3-02 

0-85 

Ash             „            „ 

o-o 

o-o 

o-o 

o-o 

o-o 

o-o 

o-o 

d-b 

o-o 

Percentage  of  fatty  acids 

79-6 

81-67 

86-89 

87-95 

74-90 

85-35 

Sulphur  in  these  acids  . 

9-88 

4-06 

8-34 

6-54 

8-32 

5-32 

6-44 

Chlorine     ,,            „ 

traces. 

0-60 

little. 

little. 

0-20 

traces. 

traces. 

Iodine  value  of  the  substitute 

56-3 

52-6 

32-5 

26-9 

33-6 

42-8 

35-2 

21-9 

30-3 

„      acids       . 

160-3 

141-21 

101-5 

102-8 

133-3 

129-2 

136-22 

143-5 

91-5 

Acetyl  value  .... 

21'0 

19-6 

31-0 

105-6 

51-3 

A,  Raw  linseed  oil  (fresh).  B,  Oxidised  linseed  oil.  C,  Rape  oil  (fresh).  D,  Oxidised 
rape  oil.  E,  Oxidised  poppy-seed  oil.  F,  Mixture  of  oxidised  linseed  and  poppy  oils.  G, 
Castor  oil  with  a  minimum  dose  of  sulphur  chloride.  H,  Castor  oil  with  a  maximum  dose  of 
sulphur  chloride.  I,  The  oil  termed  soluble  castor  (oxidised  cotton-seed  oil). 

The  determination  of  the  sulphur  of  substitutes  necessitates  the  same  precau- 
tions as  with  rubber.  Oxidation  by  nitric  acid,  followed  by  fusion  with  an  alkaline 
oxidising  agent,  alone  yields  concordant  results.  To  estimate  chlorine,  silver 
nitrate  was  added  to  the  nitric  acid,  so  as  to  avoid  all  loss  by  volatilisation  of 
hydrochloric  acid.  After  alkaline  fusion,  the  whole  is  digested  in  water,  the 
insoluble  silver  compounds  are  separated  (generally  metallic  silver),  and  the  sulphur 
estimated  in  one  portion  of  the  liquid  as  barium  sulphate,  and  the  chlorine  by 
titration  with  nitrate  of  silver  and  sulphocyanate.  Oils  solidified  by  sulphur 
chloride  only  absorb  insignificant  quantities  of  iodine.  Sample  A,  Table  LXXV., 
gave  an  iodine  value,  according  to  Hubl,  of  7  "2.  However,  this  value  is  only 
apparent.  The  feeble  iodine  absorption  is  partly  due  to  the  fact  that  the  product 
is  almost  insoluble  in  chloroform.  By  frequently  agitating  the  finely  divided  sub- 
stitute in  suspension  in  that  liquid  with  an  excess  of  iodine  solution,  and  leaving  it 
in  contact  for  twelve  hours,  Henriques  obtained  from  A  and  B,  Table  LXXV.,  iodine 
values  of  30  "9  and  31.  Compared  with  the  iodine  values  of  the  drying  oils  used  to 
make  these  substitutes,  these  figures  are  still  very  low.  Apparently,  sulphur  chloride 

1  Another  determination  gave  iodine  value  =  121 '0. 

2  Two  other  determinations  gave  147 '4  and  152'1. 


RUBBER   SUBSTITUTES 

partially  saturate*  ill--  n<.   \alencie-  o!  tin-  oil  to  as  great  an  extent  b\  u«  chlorine 

ulpliur.  po»ibly  i.\  it-  .-lil'-riii.    al"n--.     Sui»stitnte«  treated  vu'Ji  i' "lints 

in  ehloi-ofonnie  solution,  strongly  retain  tin-  nietall'-id,  ai.d    .•        nectvMttry  to  iiuut 

much  in  the  kick  t it r.ii i< >n  b\  li  \  i  ••  •  '  1 1  pint .-.  of   -turnip  energetical  1>  un«l  for  a  long 

time  so  as  to  destroy  ,ill  tin-  todiM  inexcesa     h  -hould  U-  int.  i. -ting  to  obaoire 

ho\\  si  institutes  behave  <>ii  -aponitirati»n.     They  are  coin  pl«-t«-l\  -«.lubl.-  m  ul.-,,|,,.iir 

In  tliis  reaction    the  rhl.irine  i-   almost  eliminated.  \\hil-t    tin-  percentage  of 

sulphur  in  tin-  tat;  iv.jKjnda  exactly  \\ith  th.-  percentage  oJ  ntohn  ii  tin- 

substitute.      Hou,.\er,    the   proportion   of   fatty  acid*  found  w  al\\.i\  'halt 

simple  -aponiticatioii  \\niilil  iinj.l;.  ikin^  into  account    the  rliin::  the 

chlorine.      Thus  ^ani|)lo  A  gave  IMi  JKT  r.-nt.,  sanijilc  I',  only  7'.'  1   |«  i 

acids.      A  portion  of  tin-  oil  and  a  <-onv>|>ondin^  <|iiantity  of  .sulphur  n. 

have  iindfr^oiir  a  Iran-formation  of   a  ditirivnt  ord«-r.      Th.-   Inpiid  lr<*iu  thr  *a|«»ni 

tiration    rontains    much    chlorine    l»nt     no    ajipan-nt     -ulphur    nor    Miilphui 

Bnipharetted  hydrogen  nor  >ulphur«nis  acid.     r.m.  «n  eraporatmg  tln-.se  lii|ui<i 
[•IVM-II.V  ..t  th  ..f  hydrochloric  acid  added  to  HU-ratr  tin-  fatty  acids  to  the 

point  where  hydrochloric  acid  fmnc>  U-^iii  t..  !>••  ^i\.-n  otr,  tin-  presence  of  nnu-h 

sulpiiric    acid    is   dcinonst rat.-d.      Tlif    >ulj»liur    chloiid.-,    \si«h    tin-    aid    ••!     "\ygBH 
liorro\\vd  i-ithrr  from  the  air  or  tin-  snl.-titntr  it-.-il,  si-t-m-  tlu-n-fon-  to   ti m.sfonn  a 
portion  of   the  oil  into  a   sulpho-oleic  acid   analogous  to  those    pio«ln<-»-d   in  the 
manufacture  of    turkey  -ml  oil.       In   all   the    substitute-    m.ule    l,y    Hi-m 
the   sequel,  he  demonstrates  the  formation,  in  greater  'heie 

sulphooK-'u-     acids,    and    a    consequent     diminution     of    >ul-tituted    fatty    a. 
These   concomitant    reaction-    are    difficult  to   regulate.    f.,r.  ,-ven  when  working 
under  apparently  identical  conditions,  he  obtained  variable  proportions  ol  insoluble 
fatty  acids.  .    *. 

As  saponification  eliminates] chlorine  from  the   molecule  ..f  tin-  .-uUtitu 
WSJ  to  be  foreseen  that  the   isolated  acids  would  appreciably  absorb  mo: 
than  the  substitutes  from  which  they  were  derived,  whilst   the  ordinary  fa- 
yield  an  iodine  value  approaching  that  of  the  oils  from  \vhich  th.  \  ved. 

The  iodine  values  of  the  saponified  acids  are  almost  triple  th<»e  of  tl 
Little  had  been  published  on  the  action  of  sulphur  chWid- 

The  most  recent  communications  are  those  of  Bruce  Warren1  and  BosnaSK1 
\\anen  asserts  that  drying  oils  yield  solid  masses  with  chloride  of  sulphur, 
insoluble  in  carbon  disulphide,  \vlul.-t  the  non-drying  «-ils  yield  products  soluble 
in  that  solvent.  Stolmann,  in  the  last  (German)  edition  of  Mu-prar  nary, 

writes  that  these  results  merit    but   little  reliance,    because  olive  oil      thetxi 
the  noii -drying  oils — is  transformed  by  the  action    of  sulphur  chloride  into  a  maSB 
analogous    with   rubber,    insoluble   in  ether.      The    facts   pointed   out    in   S. miner's 
patent,   as  well  as  Henrique-'    per-onal   e\|»erience.    formally   contradi.-t 
assertions.     If  a  sufficient  quantity  of  sulphur  chloride  l>e  added  to  a  tatty  «.d.  tin- 
two  liquids  soon  mix.     After  a  few  moments  of  contact,  energetic  reaction  -et-  in. 
accompanied  by  considerable  disengagement  of  heat.     The  mixture  froths.  -\\,  1!-. 
gives  off  vapours  of  sulphur  chloride,  with  a  little  hydrochloric  arid,  sulpln; 
gas,  and  after  a  few  tecoadl  becomes  converted  into  a  solid,  elastic,  scarcely  tacky, 
amber-coloured    mas-,  capable   of   being   ground    and   crushed  under  the  pestle. 
Exposed  to  the  air.  the  mass  loses  the   excess  of  sulphur  chloride  employed  and 
the  adherent  hydrochloric   acid:  it    then    resemble-  -ry  respect   the  white 

rubber  substitutes  of  commerce.      If  one  or  other   of    th, 

diluted  with  a   neutral   -o| vent,  carbon  disulphide  or  l«en/..l.  tl  nger 

in  being  manifested,  its    violence    is    moderated,  but    the    final   result   W   the  • 
The  substitute  is  a   little  more  porous  in  consequ--  he  volatil 

solvent.      That  is  how  tin-  reaction  goes  on   in   presence  of  a  sufficient  qua 
sulphur  chloride.      In   the  contrary  case,  along  \\ith  a   tea  disengagement  of  heat, 
a  pasty,  tacky  residue  is  obtained,  which  even  a  long  time  afterwards,  whether  hr.t 
or  cold,  does  not  solidify. 

1  Chemical  News,  1888,  p.  110.  a  German  Pateut,  No.  50,282. 


276  INDIARUBBER 

TABLE  LXXVII. — SHOWING  HOW  THE  QUANTITY  OF  CHLORIDE  OF  SULPHUR 
REQUIRED  TO  TRANSFORM  AN  OlL  INTO  A  SOLID  SUBSTITUTE  VARIES 
WITH  THE  NATURE  OF  THE  OIL,  ACCORDING  TO  HENRIQUES'  EXPERIMENTS. 


Parts  S2C12 

Parts  S2C12 

(Linseed 

If 

25 

}/• 

30          A 

100  parts  of 
oil  of 

Poppy 
Rape 
Cotton 
Olive 
Castor 

do  not  yield  1 
a  solid  pro-  -! 
duct  with 

30 

20 
40 
20 
18 

but  do  so  J 
well  with  1 

35 
25 
45            | 
25 
20 

Inspection  of  these  figures  shows  that  there  is  no  relation  between  the  drying 
properties  of  oils  and  their  aptitude  to  solidify  under  the  action  of  sulphur 
chloride.  Having  thus  fixed  the  required  proportions  of  chloride  of  sulphur, 
Henriques  prepared  and  analysed  substitutes  with  a  linseed  oil,  rape  oil,  and  a  poppy 
oil  base,  and  with  a  mixture  of  equal  parts  of  linseed  oil  and  rape  oil.  The  results 
are  given  in  Table  LXXVI.  Neither  of  these  are  analogous  with  substitutes  A  and 
B  of  Table  LXXV.,  products  of  English  origin,  of  which  it  would  be  desirable  to 
know  the  method  of  preparation.  Indeed,  the  commercial  sample  C  (Table  LXXV., 
yielded,  on  analysis,  figures  so  similar  to  those  of  the  rape  oil  substitutes  C,  of 
Table  LXXVI.,  that  they  may  be  rightly  regarded  as  identical.  The  iodine  values 
of  the  fatty  acids  isolated  from  substitutes  present  such  wide  differences  from  one 
kind  to  another  that  agreement  in  the  iodine  values  may  be  taken  as  proof  of 
identity.  Moreover,  Henriques  learned  from  a  manufacturer  that  the  bulk  of  the 
substitutes  made  in  Germany  are  made  from  rape  oil.  The  distinctive  character- 
istics of  the  English  substitutes  A  and  B  are  their  relatively  low  percentage  of 
sulphur  and  chlorine,  according  to  which  only  20  per  cent,  of  sulphur  chloride  had 
been  used  to  solidify  the  oil.  With  the  exception  of  castor  oil,  Henriques 
demonstrated  that  only  the  oxidised  oils  can  be  solidified  with  that  proportion  of 
chloride  of  sulphur.  Raw  linseed  oil,  for  example,  which  requires  at  least  30  parts 
of  S2C12  to  solidify  it  when  it  is  fresh,  only  requires  15  to  18  per  cent,  when  it 
has  been  heated  for  some  hours  at  200°  to  250°  C.  (say  392°  to  482°  F.)  in  contact 
with  air.  If  the  temperature  be  pushed  to  250°  to  300°  C.  (482°  to  572°  F.), 
10  per  cent,  of  S2C12  suffices.  A  substitute  prepared  in  that  way  would  run  into 
4'78  per  cent,  of  sulphur  and  4 '85  per  cent,  of  chlorine.  All  drying  oils  behave 
in  this  respect  like  linseed  oil.  By  pursuing  this  method,  Henriques  identified  the 
English  substitutes  with  the  product  obtained  by  the  action  of  sulphur  chloride 
on  oxidised  cotton-seed  oil,  known  in  the  English  trade  under  the  name  of  soluble 
castor  oil  (lardine).  Brown  substitutes  will  be  dealt  with  more  briefly.  They 
are  met  with  in  commerce  sometimes  as  deep  brown,  tacky  blocks ;  sometimes  in 
powder.  Analysis  shows  the  presence  of  a  much  greater  quantity  of  sulphur  than 
in  the  substitutes  previously  examined.  But  chlorine  is  almost  entirely  absent. 
These  substitutes  are  certainly  obtained  by  heating  oil  with  sulphur.  They  also 
dissolve  in  alcoholic  soda;  the  soap,  treated  by  an  acid,  disengages  appreciable 
quantities  of  sulphuretted  hydrogen ;  the  isolated  fatty  acids,  however,  contain  a 
smaller  proportion  of  sulphur  than  the  substitutes  from  which  they  were  derived. 
The  iodine  values  of  these  substitutes  and  those  of  the  fatty  acids  are  rather  high, 
which  induced  Henriques  to  believe  that  it  is  linseed  oil,  or  a  mixture  of  linseed 
and  rape  oil,  which  is  used  in  their  manufacture.  He  did  not  pursue  the  examina- 
tion of  these  substitutes,  which  are  much  less  interesting,  from  the  scientific  point  of 
view,  than  the  previous  ones.  It  was  interesting  to  ascertain  whether  the  vulcanisa- 
tion of  rubbers,  sophisticated  with  substitutes,  influenced  the  percentage  of  chlorine 
in  the  product.  Henriques  examined  a  number  of  manufactured  rubbers  con- 
taining substitutes,  and  always  detected  chlorine  in  appreciable  quantity.  As  no 
other  chlorinated  compounds  are  employed  in  the  manufacture  of  rubber— with 
one  exception— we  may  conclude  that  the  presence  of  chlorine  in  the  alkaline 


RUBBER   SUBSTITUTES  277 

alcoholic  extract  of  a  rubber  is  due  to  the  use  of  a  white  substitute.  Quantitative 
ho\\e\er,  showed  tluit  tin-  proportion  of  chlorine  in  manufactured  nil. UTS  is 
much  less  than  that  which  corresponds  \\ith  the  quantity  of  substitute  adiled. 
Thus,  in  two  samples  the  peiventage  of  substitute  of  whi«-h  came  out  at  .1.".  and 
I  •_'  per  cent.,  lli'iiriqurs  mily  found  (>•">  and  0'37  of  chlorine,  \\hiUt  ralculat  MIL: 
on  an  average  of  7  percent,  chlorine  in  the  substitute  he  ought  to  have  found  3 -7  and 
0*9  per  cent.  Cl.  On  vulcanisation,  a  portion  of  the  chlorine  is  therefore  dis- 
engaged either  under  the  form  of  sulphur  chloride  or  as  hydrochloric  acid,  or  in 
some  other  way.  If  alcoholic  soda  extracts  an  appreciable  quantity  of  substance 
from  a  sample  of  rubber,  and  the  extract  contains  no  chlorine,  the  question  is, 
whether  the  rubber  is  mixed  with  brown  substitute  or  contains  a  fatty  body.  The 
fatty  acids  liberated  from  substitutes  contain  a  rather  smaller  proportion  of 
sulphur  than  the  substitutes  themselves.  Those  of  brown  substitutes  generally 
contain  more  than  10  per  cent.  If,  therefore,  the  fatty  oils  have  not  fixed  sulphur 
during  vulcanisation, — if  they  have  not  by  the  heating  itself  of  the  rubber  been 
transformed  into  substitute,  we  should  be  able,  by  isolating  the  fatty  acids  from 
the  treatment  with  alcoholic  soda,  and  by  estimating  their  percentage  of  sulphur, 
to  distinguish  between  the  addition  of  an  oil  heated  with  sulphur  and  an  ordinary 
oil.  To  solve  this  point  experimentally,  Henriques  heated  rape  oil  wi!h  an 
excess  of  sulphur  for  several  hours  at  a  temperature  of  130°  to  135°  C.  (266°  to 
275°  F.),  the  highest  temperature  reached  in  vulcanisation.  The  oil  then  dissolved 
large  quantities  of  sulphur,  which  for  the  greater  part  re-crystallised  out  on  cooling. 
After  filtration  the  limpid  oil  was  saponified,  and  the  fatty  acids  separated  in  the 
usual  way.  Finally,  the  latter  were  dissolved  in  90  per  cent,  alcohol,  to  separate 
the  precipitated  sulphur,  and  the  sulphur  was  estimated  in  the  acids  thus  purified, 
in  which  were  still  deposited  some  crystals  of  sulphur  after  filtration.  Found 
sulphur  =  0'98  per  cent.  The  quantity  of  sulphur  so  found  may  be  neglected, 
when  compared  with  that  which  brown  substitutes  contain.  The  problem  to 
detect  the  presence  of  white  substitute  in  rubber,  brown  substitute,  or  in  an  ordinary 
fatty  oil,  and  to  estimate  them  therein,  may  therefore  be  regarded  as  solved.  The 
presence  of  appreciable  proportions  of  chlorine  points  to  the  addition  of  white 
substitute.  The  estimation  of  the  sulphur  in  the  fatty  acids  liberated  from  the 
alcoholic  soda  extract  decides  between  brown  substitute  and  a  fatty  oil.  The 
method  is  inapplicable  if  a  rubber  contains  all  these  three  categories  of  substances 
simultaneously,  but  evidently  that  only  occurs  very  rarely.  What  is  to  be 
understood  by  "patent  rubber "1  In  Muspratt's  Technical  Dictionary,  fourth 
(German)  edition,  it  is  said  that  the  term  is  applied  to  those  vulcanised  rubbers 
the  excess  of  sulphur  in  which  has  been  removed  by  boiling  in  caustic  alkaline 
lyes.  This  assertion  is  altogether  erroneous.  By  patent  rubbers  is  always  meant 
those  which  are  prepared  from  cut  sheet,  or  the  English  sheet,  cut  by  the  saw 
from  blocks  of  normal  rubber.  The  method  of  making  these  sheets  is  known. 
The  well-purified  rubber  is  agglomerated  in  a  masticating  mixer  into  cakes  of 
3  to  5  kilogrammes  (say  6 J  to  11  lb.).  A  certain  number  of  these  cakes  are 
amalgamated  into  a  large  block  by  means  of  a  hydraulic  press.  This  large  block 
should  be  brought  to  such  a  decree  of  hardness  that  it  can  be  divided  into  sheets 
of  any  thickness.  Formerly,  this  object  was  obtained  by  abandoning  the  blocks 
for  several  months  in  cool  cellars.  At  the  present  day,  without  doubt,  artificial 
cold,  to  which  the  blocks  are  exposed  for  some  days,  is  alone  used  for  this  purpose. 
The  characteristic  of  the  English  sheet  is  the  striated  aspect  which  it  owes  to  the 
action  of  the  saw,  and  which  every  one  has  seen  in  good  quality  pliant  rubber,  used 
for  surgical  or  scientific  purposes.  It  would,  however,  be  risky  to  admit  that  all 
rubbers  which  show  the  stria?  of  which  we  speak  have  actually  been  obtained  from 
the  cut  sheet,  because  it  is  not  difficult  to  obtain  the  same  appearance  by  calender- 
ing the  rubber,  made  in  the  ordinary  way,  between  rolls  carrying  grooves  which 
imitate  on  the  sheet,  while  it  is  still  soft,  the  imprints  left  by  the  saw.  Objects 
made  from  English  sheet  are  almost  always  vulcanised  in  the  cold  by  sulphur 
chloride.  A  small  proportion  only  is  vulcanised  by  the  old  process  of  immersion 


278 


INDIARUBBER 


in  a  bath  of  molten  sulphur.  It  would  be  interesting  to  complete  this  examination 
of  the  analysis  of  rubber  and  substitutes  by  the  analysis  of  rubber  vulcanised 
according  to  Parkes'  process.  It  would  be  necessary  to  know,  on  the  one  hand,  if 
this  rubber  also  resists  the  action  of  alcoholic  soda,  and  if  the  above  method  of 
analysis  applies  to  rubbers  vulcanised  in  the  cold.  On  the  other  hand,  it  would 
be  interesting  to  know  if  sulphur  chloride  acts  upon  rubber  as  upon  oils,  and  fixes 
itself  on  the  molecule  of  hydrocarbide  by  its  chlorine  and  its  sulphur  at  one 
and  the  same  time.  Henriques  analysed  numerous  samples  of  patent  rubber, 
and  generally  found  more  sulphur  than  chlorine.  The  following  are  some 
of  the  results  obtained.  He  first  cut  as  thin  sheets  as  possible  out  of  a  block 
of  pure  dry  Para,  which  he  treated  with  chloride  of  sulphur.  The  analysis 
gave— 

TABLE  LXXVIII. — RESULTS  OF  ANALYSES  OF  PURE  PARA  RUBBER  TREATED 
WITH  SULPHUR  CHLORIDE. 


I. 

II. 

1.  Ash  of  the  initial  rubber  . 

0-46 

0'46 

2.  Sulphur  
3.  Chlorine  

5-19 
5-61 

0-50 
0-57 

4.  Matter  extracted  by  alcoholic  soda  . 

2-90 

2-20 

5.  Ashes  contained  in  residue 

0-67 

0-90 

;  Alcoholic  soda  therefore  no  more  attacks  rubber  vulcanised  in  the  cold  than 
rubber  vulcanised  in  the  ordinary  way.  The  method  of  analysis  is  therefore 
applicable  to  both  of  these  commercial  sorts.  Sample  I.  was  supervulcanised 
almost  hard  and  barely  elastic.  Sample  II.,  on  the  contrary,  was  insuffi- 
ciently vulcanised,  and  at  100°  C.  (212°  F.)  had  already  become  tacky.  These 
analyses,  therefore,  represent  limited  sorts.  Henriques  procured,  on  the 
other  hand,  authenticated  English  sheet,  which  he  analysed  before  and  after 
vulcanisation — 


TABLE  LXXIX. — ANALYSES  OF  ENGLISH  CUT  SHEET  PREVIOUS  TO  AND  AFTER 
VULCANISATION  BY  SULPHUR  CHLORIDE. 


English  Sheet. 

Normal. 

Vulcanised. 

Per  cent. 

Per  cent. 

1.  Ash 

0.1  Q 

2.  Sulphur  .... 

lo 
I'M 

3.  Chlorine  .... 

(it 

O.CQ 

4.  Alcoholic  soda  extract 

1*94 

1*66 

5.  Sulphur  in  extract  IV.     . 
6.  Chlorine  in  extract  IV.     . 

0-571 
0-55 

7.  Dissolved  rubber  (by  difference) 

1-94 

0-54 

It  would  be  expected  that  these  patent  rubbers  of  commerce  would    behave 

in  an  analogous  manner  when  treated  with  alcoholic  soda.     Books  dealing  with 

the    mdiarubber   industry   repeat,    in    fact,    that    patent   rubber    cannot   be   cut 

except  from  blocks  of  good  quality  Para.     Great  was    Henriques'  astonishment 

1  All  these  figures  are  brought  to  per  cent,  of  initial  substance. 


RUBBER    SUBSTITUTES 


279 


t<»    find  ;iiiti«-i|.atiniis  deoetred    l>y  a  great  nuinl.t-r  M   >;miplrs   like  tin-   following, 
for  (>\;ini|>Ie — 

T  \I:I.K    LX.X.V      AN  LLYB1  HUB  i  LI   Mil  i  i     EtUBl 


I. 

II. 

III. 

Per  cent. 

Per  cent. 

Per  cent. 

1.  Ash 

0-67 

0-20 

•J.  Sulphur  . 

3  '68 

2-37 

T86 

3.  Chlorine. 

3-63 

2-51 

1-33 

4.  Extraction  residue 

84-30 

92-10 

94-50 

5.  Ash  in  residue  IV. 

1-80 

... 

0-88 

6.  Sulphur  in  IV. 

1-92 

177 

0-83 

7.  Chlorine  in  IV. 

1-31 

1-54 

1-17 

rs+ci 

4-08 

1-67 

1-57 

Soluble  matter^  organic 

12-50 

6-50 

5-00 

(  (about) 

Sample  I.  was  a  cheap  quality  of  North  German  manufacture.  Samples  II.  and 
III.  were  rubber  tubings  of  unknown  origin.  To  ascertain  the  nature  of  the 
soluble  product  in  sample  I.,  50  grammes  of  this  substance  were  extracted  by 
alcoholic  soda,  the  alcohol  evaporated,  the  liquid  acidulated  and  taken  up  by  ether. 
The  latter  abandoned  an  apparently  oily  residue,  containing  sulphur,  6 '29 ; 
chlorine,  0'35 ;  iodine  value,  92. 

The  analogy  of  these  figures  with  those  previously  obtained  in  the  analysis  of 
ordinary  rubber  sophisticated  with  white  substitute  did  not  appear  to  leave  any 
doubt  as  to  the  presence  of  a  similar  substitute  in  the  patent  rubber  examined. 
Henriques,  moreover,  learned  from  a  manufacturer,  that  for  some  years  back  it  is  not 
rare  to  meet  with  cut  sheet  containing  substitutes  sometimes  to  the  extent  of  one-third. 
It  seems  desirable  to  point  this  out,  as  many  people  are  still  persuaded  that  in  buying 
cut  sheet  or  patent  rubber  they  will  get  pure  rubber.  The  above  analyses  show  how 
far  this  way  of  thinking  is  from  being  justified.  The  author  has  been  able  to  control 
the  results  of  his  method  by  applying  it  to  the  analysis  of  manufactured  rubber  made 
by  a  rubber  manufacturer  with  known  proportions  of  white  or  brown  substitues  or 
colza  oil.  He  has  simplifed  and  improved  his  method  so  that  it  takes  much  1-  — 
time  and  requires  fewer  precautions  than  at  the  outset.  "  I  have  found,"  says  he, 
"that  rubber  treated  with  alcoholic  or  aqueous  soda  retains  a  non-neglectable 
quantity  of  alkali,  the  weight  of  which  must  be  determined  so  as  to  add  it  to  that 
of  the  dissolved  substances  obtained  by  difference  (see  preceding).  This  is  not  all. 
To  the  dissolved  substances,  it.  was  necessary  to  estimate  the  sulphur  in  the  initial 
sample  and  in  the  extraction  residue.  In  washing  the  extracted  rubber  by  boiling 
it  with  dilute  hydrochloric  acid,  and  washing  until  neutral,  the  quantity  of  alkali 
retained  by  the  rubber  is  so  small  that  in  calculating  the  results  it  may  be 
neglected."  The  complete  analysis  of  a  mixture  of  substitute,  fatty  oil,  rubber, 
and  sulphur  comprises  the  following  six  determinations :  (a)  total  sulphur ;  (b) 
total  ash ;  (c)  weight  of  the  substance  extracted  by  alcoholic  soda ;  (d)  weight 
of  the  sulphur  in  the  extract  (c)  calculated  to  the  sample  analysed ;  (e)  ash  of  the 
extract  calculated  to  the  sample  analysed  ;  (/)  sulphur  of  the  fatty  acids  (dissolved). 
To  determine  c,  1 J  to  2  grammes  of  the  substance  are  sufficient.  In  general,  the 
extraction  may  be  considered  as  finished  after  two  or  three  hours'  boiling  with  a 
reflux  condenser  with  alcoholic  soda.  But  it  is  well  to  renew  the  extraction  from 
one  to  two  hours  with  fresh  lye,  for  the  sake  of  precaution.  Even  the  small 
quantity  of  the  rubber  itself  which  dissolves  in  alcoholic  soda  is  taken  into  account 
by  deducting  from  the  alcohol  extract  2J  per  cent,  of  the  weight  of  the  rubber 
found  by  difference.  This  correction  is  the  result  of  the  average  of  ten  determina- 
tions, the  results  of  which  varied  between  0*9  and  3*5  per  cent.  Having  the  six 


280 


INDIARUBBER 


results  indicated,  the  percentage  of  fatty  acids  (y)  in  the  mixture,  sulphuretted  or 
otherwise,  and  the  percentage  of  rubber  (,)  are  obtamed  by  means  of  the 
equations  — 


from  which  it  follows  — 


. 

The  following  results  were  so  obtained  in  the  case  of  three  kinds  of  rubber,  the 
composition  of  which  was  given  by  the  manufacturer  :— 

TABLE  LXXXL—  ANALYSES  OF  VULCANISED  RUBBER  CONTAINING  SUBSTITUTES. 


I. 

II. 

Ill 

Rubber  with  Brown 
Substitute. 

Rubber  with  White 
Substitute. 

Rubber  with  Oil. 

Per  cent. 

Per  cent. 

Per  cent. 

(a\ 

19-46 

11-38 

21-55 

(h\ 

/        072 

0-40 

0-40 

\u) 
if\ 

68-37 

67-68 

63-40 

(d) 

2-64 

1-51 

3-06 

ie\ 

270 

2-81 

3-17 

tf\ 

16-60 

9-27 

3-20 

\J  ) 
Chlorine 

Nil. 

Very  strong  reaction. 

Nil. 

From  which  we  calculate  the  composition— 

TABLE  LXXXII. — COMPOSITION  OF  RUBBERS  WHOSE  ANALYSES  ARE  GIVEN  IN 

TABLE  LXXXL 


I. 

II. 

III. 

Found. 

Indicated. 

Found. 

Indicated. 

Found. 

Indicated. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Sulphur    . 
Brown  substitute 

16-13 
18-50 

16-4 
19-3 

9-19 

9-6 

21-55 

23-5 

White  substitute       . 

... 

25-43 

25-8 

Oil  . 

20-42 

17-7 

Rubber    . 

64-65 

64-3 

64-98 

64-6 

57-63 

58-8 

Ash. 

0-72 

0'40 

0-40 

... 

100-00 

100-00 

100-00 

100-00 

100-00 

100-00 

The  agreement  is  very  satisfactory.  Henriques  likewise  sought  methods  of 
estimating  asphaltum  or  bitumen,  a  substance  which  is  very  often  met  with  in 
pliant  rubber  and  ebonite.  The  usual  solvents  capable  of  dissolving  asphaltum 
without  residue,  chloroform,  spirits  of  turpentine,  for  example,  swell  non- vulcanised 
rubber  into  a  porous  mass,  which  renders  all  separation  impossible.  Nitrobenzol 
has  not  this  drawback,  and  easily  dissolves  bitumen.  On  that  fact  the 
following  method  is  based.  One  gramme  of  the  sample  to  be  tested,  as  finely 
divided  as  possible,  is  placed  in  a  test-glass  on  foot,  to  digest  with  30  c.c.  of 


RUBBER   SUBSTITUTES 


281 


nitrobenzol.  After  ;m  li"iir  in  tin-  cold,  tin-  \\holr  i-  thrown  on  a  filter,  and  the 
I'ra.L'iiiriiN  nf  rul.l.rr  piv^rd  apiin^t  \\ith  :i  glass  rod,  and  washed  \\itli  30  C.C. 
•  •I'  tin-  same  -"Kent.  The  contents  of  the  filter,  expressed  as  f;n  ^il.le 

I.etueen  !',.|,U  ,,|  filter  |i;i|u-r,  are  \Na-dn-d.  l>\  mean-  ..I  tin-  \\.-i-li  buttlr,  into  a 
eajKide  :  \\atrr  added  ami  bnilrd  until  all  smell  of  nitroU'ii/ol  lias  disappeared.  It  i- 
again  bnniirlit  mi  t<>  a  tared  filter,  \\ashrd,  dried,  and  \\rLdird.  \\'hen  the  nil.  her 
is  charged  with  mineral  si  distances,  the  particles  of  which  become  detached  on 
boiling,  or  partially  dissolve,  the  contents  of  the  capsule  are  evaporated  to  dryness, 
after  elimination  of  the  nitrobenzol.  By  so  treating  several  kinds  of  non-bitu- 
mi  in  HIS  rubber  a  loss  was  found  of  1*44,  2  '03,  1*10,  1'54  per  cent,  say  an  average 
of  1J  per  cent.  l>v  allowing  for  the  correction  resulting  from  this  partial  solubility 
of  robber  itself  in  nitrobenzol,  if  we  analyse  a  mixture  containing  only  non- 
vulrani.M'd  rubber  and  asphaltum,  supposing  x  to  be  the  percentage  of  rubber  in 
the  mixture,  we  get  — 

1*5  x  x 


In  applying  the  process  to  the  analysis  of  vulcanised  rubbers,  matters  become 
a  little  more  complicated  by  the  presence  of  free  sulphur,  a  portion  of  which 
dissolves  in  the  nitrobenzol.  But  if  such  sulphur  be  eliminated  beforehand,  the 
results  become  normal.  The  extraction  of  the  sulphur  is  best  effected  by  the 
alcoholic  soda  used  to  dissolve  the  substitutes  and  the  oils.  It  suffices,  therefore, 
to  proceed  to  the  estimation  of  the  asphaltum  on  the  sample  which  has  been  used 
to  determine  the  substitute.  (Before  filtering  the  liquid  resulting  from  the  extrac- 
tion by  alcoholic  soda,  it  is  necessary  to  eliminate  all  the  alcohol,  as  already 
recommended.)  Henriques  found  that  asphaltum  itself,  under  these  circumstances, 
oidy  suffers  a  neglectable  loss  of  weight,  4  to  5  milligrammes  for  1  gramme,  whilst 
several  vulcanised  rubbers,  previously  desulphurised  by  alcoholic  soda,  washed  and 
dried,  subjected  to  the  same  treatment,  lost  2'7,  2*33,  4*11,  3*51  per  cent,  of  their 
weight,  say  an  average  of  3  per  cent.  This  figure  may  be  taken  as  the  coefficient  of 
solubility  of  vulcanised  rubber  in  nitrobenzol.  It  is  allowed  for  in  calculating  the 
analysis.  The  process  was  applied  to  four  mixtures,  in  known  proportion,  of 
vulcanised  rubber  and  asphaltum.  It  gave  the  following  results  :  — 

TABLE  LXXXIII.  —  ANALYSES  OF  RUBBER  MIXTURES  CONTAINING  ASPHALTUM 
DETERMINATION  OF  ASPHALTUM  THEREIN. 


Loss  on 

Percentage  of 

treating 

Asphaltum. 

Loss  on 

the  Desul- 

Ingredients of  Mixture  analysed. 

Desul- 

phurised 

phurising. 

Sample 

In  the  De- 

In the 

with  Nitro- 

sulphurised 

Original 

benzol. 

Sample. 

Sample. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

A 

/Rubber  and  sulphur     90'00\ 
\Asphaltum  .         .         10'OOJ 

8'40 

14-18 

11-53 

10-57 

B 

/Rubber  and  sulphur     80'00\ 
\Asnhaltum  .         .         20'OOJ 

5-89 

23-05 

20-68 

19-45 

C 

/  Rubber  and  suphur      77  '27  \ 
\Asphaltum  .         .         22'73/ 

6-84 

26-48 

24-20 

22-54 

D 

(Rubber  and  sulphur     71  '46  \ 
\Asphaltum  .         .         28'54/ 

4-86 

31-46 

29-34 

28-05 

The  process  is  also  applicable  to  the  analysis  of  ebonite.  The  coefficient  of 
solubility  in  nitrobenzol  would  appear  to  be  a  little  smaller  in  ebonite  than  in  that 
of  pliant  rubber.  The  loss  in  the  case  of  three  kinds  of  pure  ebonite— rubber, 
sulphur,  and  mineral  vulcaniser — was  1*59,  3*22,  2'22  per  cent.  Still,  in  the 


282 


INDIARUBBER 


absence  of  more  experiments  upon  this  point,  3  per  cent,  may  lie  taken  as  the 
solubility  of  ebonite  desulphurised  by  alcoholic  potash.  The  analysis  of  an  elxmite 
consisting  of  80  per  cent,  of  rubber  and  sulphur  and  20  per  cent,  of  asphalt  mil 
gave — 

TABLE  LXXXIV.— ANALYSES  OF  EBONITE  CONTAINING  ASPHALTUM. 


Weight  on 
Desulphurising. 

Loss  on  treating 
the  Desulphurised 
Sample  with 
Nitrobenzol. 

Percentage  of 
Asphaltum  in  the 
Desulphurised 
Sample  (2  per 
cent,  for  the 
Rubber). 

Percentage  of 
Asphaltum 
calculated  on  the 
Original 
Sample. 

Per  cent. 
5-96 

Per  cent. 
22-50 

Per  cent. 
21-01 

Per  cent. 
19-76 

Artificial  asphaltum,  made  from  coal-tar  pitch,  dissolves  completely  in  nitro- 
benzol,  like  natural  asphaltum. 

Pontio's  scheme  for  analysis  of  Rubber  based  on  Henriques'  &  G.  0.  Weber's 
Methods. — Pontio,  like  Weber,  separates  the  constituents  of  rubber  into  four  groups, 
each  of  which  has  its  own  characteristic  solvent — (1)  the  absolute  alcohol  group, 
comprising  free  sulphur,  rosin,  paraffin,  oils,  and  fats ;  (2)  the  alcoholic  soda  group, 
substitutes,  sulphur  combined  with  substitutes ;  (3)  the  acetone-lavender  group, 
mineral  oils,  bituminous  products ;  (4)  the  cumol  group,  rubber  and  sulphur  com- 
bined with  rubber,  mineral  matter,  and  free  carbon. 

The  first  and  fourth  group  separation  may  be  used  for  natural  unmixed  rubbers, 
and  would  be  of  great  use  in  buying.  The  whole  four  groups  are  necessary  for 
black  and  grey,  red  and  white  rubbers.  The  fourth  separation  could  be  replaced  by 
estimating  the  mineral  matter  by  direct  ignition,  the  rubber  and  vulcanisation 
sulphur  being  then  got  by  difference;  but  this  mode  of  operation  is  impossible 
when  the  presence  of  vermilion,  free  carbon,  or  free  sulphur  is  suspected,  and  in 
that  case  the  whole  four  groups  must  be  worked  through.  Absolute  alcohol, 
employed  for  the  determination,  by  difference,  of  free  sulphur  and  resins,  is  a  fairly 
good  solvent  for  the  purpose;  100  parts  of  absolute  alcohol  dissolve  in  weight 
0'425  grammes  of  sulphur,  or  700  c.c.  or  555  grammes  of  absolute  alcohol  can 
dissolve  2 "3 60  grammes  of  sulphur.  As  700  c.c.  555  (grammes)  is  the  quantity 
necessary  for  the  simultaneous  determination  of  resins  and  free  sulphur  for  four 
sample  trials  of  0'500  grammes  each,  it  will  be  seen  that  for  each  sample  this 
corresponds  to  0*590  grammes  of  sulphur,  a  weight  greater  than  the  sample  taken. 
As  manufactured  rubbers  contain  generally  a  maximum  of  10  per  cent,  of  sulphur 
with  a  minimum  of  6  per  cent,  of  which  two-thirds  are  combined,  it  will  be  seen 
that  there  remains  a  margin  quite  large  enough  for  determining  the  remaining  free 
sulphur ;  the  same  liquid  can  therefore  serve  for  two  series  of  four  samples.  The 
imitations  and  the  sulphur  combined  with  them  can  be  estimated  without  difficulty 
by  alcoholic  soda,  as  Henriques  recommended.  But,  after  the  free  sulphur  has 
been  eliminated  by  absolute  alcohol,  and  the  sample  treated  with  alcoholic  soda, 
the  residue  from  the  alkaline  extract  may  be  used  to  estimate,  quantitatively,  the 
sulphur  combined  with  the  substitutes.  This  method  only  applies  to  samples 
treated  separately ;  but  as  this  estimation  is  only  of  relative  importance  in  most 
cases,  it  is  estimated  by  difference.  The  bituminous  matter  and  the  unsaponifiable 
products  should  only  be  estimated  with  the  acetone-lavender,  after  treatment  with 
alcoholic  sodium  hydrate,  for  the  imitations  are  slightly  soluble  in  this  mixture, 
whilst  asphaltum  and  mineral  oils  do  not  dissolve  in  alcoholic  soda.  Pontio  uses 
a  peculiar  digestor-lixiviator,  constructed  by  G.  Fontaine  of  Paris.  This  apparatus 
comprises  a  heated  2-litre  flask  containing  the  alcohol  and  solvents.  This  flask  was 
originally  surmounted  by  a  series  of  bulbs,  each  of  which  carries  a  watering  rose, 


RUBBER   SUBSTITUTES  283 

\\here  tin-  tample  in  pla«-ed.     A  gibbet  with  four  n.nvx|M,Mding  small  bask( 

|>l;uv<l  dirertly  OTWf  tin-  bath  of  hot  alcohol.  Alto\e  the-e  Lull.  \g  .,  condenser  in 
\\hieh  tin-  alcohol  \a|M»iirs  an-  condensed,  and  from  \\henee  they  fall  bark  into  the 
Bask,  after  having  rewaahed  tin-  >amples  placed  in  the  biillis  ;  eight  >ample>  -.MI 
thus  l>e  treated  at  onee.  I'ontio  lias  lately  altrivd  tin-  <-on>t  met  ion  of  his  extractor 
so  that  (\\rl\r  samples  can  no\\  In-  treated  at  mice.  It  now  connMs  of  tuo  >nper 
imposed  recei\ers  of  hard  gla^.  «\  a  l>lo\\n  glass  arrangement  and  a  Soxhlrt 
condenser.  The  lower  vessel  is  a  digestion  flask  fitted  with  a  stopi>er  forming  a 
cork,  in  the  centre  of  which  are  adjusted  (1)  the  ground  stem  of  the  upper  vessel 
(the  lixiviator);  (2)  a  support  to  hold  six  funnels.  Inside  the  lixiviator  there 
are  adjusted  in  the  centre  of  a  second  ground  stopper  six  "roses,"  fitted  with 
hooks  on  which  to  fix  the  tunnels.  Each  "rose"  is  surmounted  by  an  elbow 
forming  a  tube,  which  connects  it  with  the  condenser  through  a  ground  ai>erture. 
M'tkc4  of  working. — Remove  the  stopper  from  the  apparatus,  place  it  on  a 
support  so  as  to  fix  the  samples  in  the  special  funnels  and  hang  them  on  the 
bracket  hooked  into  the  lower  aperture  of  the  lixiviator,  grease  the  stopper  with 
vaseline  in  its  ground  part,  and  insert  stopper  after  introducing  necessary  solvent. 

1.  Method  of  operating — Absolute  alcohol  group — Determination  of  free  sulphur, 
resins,  and  paraffin. — Weigh  out  0*500  gramme  of  finely  divided  rubber,  place  in  the 
bottom  basket,  heat  the  sand  bath,  and  let  the  boiling  alcohol  act  during  six  hours. 
The  sample  is  then  raised  into  a  higher  bulb  in  the  old  apparatus  and  underneath 
one  of  the  circular  battery  of  "  roses  "  in  the  newer  design,  where  it  is  washed  by 
the  condensed  alcohol  vapours.     The  washed  products  are  then  placed  with  their 
funnels  in  the  carbonic  acid  oven,  and  maintained  at  a  temperature  of  115°  C.  for 
two  hours,  and,  after  cooling  under  a  desiccator,  each  sample  is  weighed.     The 
difference  in  weight  gives  the  sulphur,  resins,  paraffin,  and  water  contained  in  0'500 
grammes  of  the  product  under  analysis. 

2.  Alcoholic  soda  group — Substitutes  and  substitutes  combined  ivith  sulphur. — 
The  solid  residue  left  from  the  preceding  operation  is  allowed  to  digest  in  limpid 
alcoholic  soda  (8  per  cent,  of   NaOH  in  95  per  cent,  alcohol).     After  digesting 
for  six  hours  it  is  removed,  together  with  the  funnel   containing  it,  washed  in 
boiling  water  until  completely  neutralised,  and  then  with  hot  alcohol.     It  is  dried 
at  115°C.  and  afterwards  weighed.     After  checking  the  losses  due  to  determination 
of   the   preceding   elements,   the  difference  in   weight   indicates   the  quantity  of 
substitutes  and  of  sulphur  combined  with  these,  contained  in  0'5  gramme  of  the 
sample. 

3.  Acetone-lavender  group — Bituminous  products,  mineral  oils. — The  residue  left 
from  the  two  preceding  groups  is  again  placed  in  a  funnel  and  allowed  to  digest 
in   the  boiling  mixture  of  acetone-lavender  (40    per  cent,   of   essence  of   aspire, 
dextrorotary  lavender,  and  60  per  cent,  of  acetone)  for  the  same  number  of  hours. 
The  above  manipulations  are  then  repeated,  and  the  loss  of  weight  gives  the  weight 
of  the  elements  soluble  in   this  mixture,   i.e.    the  asphaltum,  the  unsaponifiable 
oils,  etc.,  plus  those  soluble  in  alcoholic  soda,  which  are  to  be  deducted  from  the 
total  loss. 

4.  Petroleum-benzine  group — Rubber  and  sulphur  combined  nnth  rubber — //"  rt 
matter. — One  or  several  fresh  samples  are  now  taken  of  0'500  gramme  each.     These 
are    placed    on    specially   dried   filter    papers   (selected    Schleicher;    diameter   7 
centimetres)  that  have  been  previously  freed  from  grease  by  the  solvent  employed 
for  the  determination.     About  10  to  12  milligrammes  per  filter  paper  are  regularly 
lost  in  this  washing.     The  solvent  employed  is  cumol  vapour.     The  sample  is  first 
placed,  as  already  said,  in  a  tared  filter  of  8  c.c.  diameter  containing  a  known  weight 
of   china   clay    (washed    and    calcined).     The    folding   of   this  paper   is  of   vital 
importance.     There  must  be    no  adherent  surfaces    to  avoid  capillary  ascension. 
The  paper  is  first  folded   in  two.  then  .|iiartcred,  the  inner  fold  is  brought  back 
once  upon  itself  by  folding  it  again  into  two,  then  a  horn  is  made  as  on  a  carte  de 
visite.     The  parts  in  contact  are  then  separated  by  a  forceps  or  the  blade  of  a  knife. 
After  introducing  the  kaolin,  the  paper  is  moistened  with  a  few  drops  of  cumol  and 


284 


INDIARUBBER 


the  kaolin  laid  in  the  bottom  of  the  filter.  That  done,  the  filter  is  furnished  with 
its  platinum  wire  support  and  the  whole  suspended  about  1  centimetre  above  the 
top  of  the  liquid,  the  cumol  is  boiled,  and  after  twelve  hours'  digestion  the  samples 
are 'withdrawn  and  washed,  first  with  crystallisable  benzol  from  a  wash  bottle  and 
then  with  boiling  95  per  cent,  alcohol.  They  are  dried  at  115°  or  120°  C.,  and  then 
weighed.  The  solid  residue  is  composed  of  mineral  salts,  free  carbon,  vegetable 
debris,  etc.  The  part  dissolved  contains  the  pure  rubber  and  the  sulphur  combined 
with  rubber.  The  mineral  matter  may  be  determined  by  igniting  the  sample  in 
closed  capsules ;  the  muffle  should  not,  however,  be  heated  above  a  dull  red  until 
all  smoke  disappears,  when  the  lids  are  removed  and  the  capsule  so  arranged  that 
its  bottom  is  not  in  direct  contact  with  the  muffle,  which  ought  only  at  this  moment 
to  have  reached  a  dull  red  heat.  When  the  carbon  on  the  sides  of  the  capsules  has 
disappeared,  the  residue  is  weighed.  The  ashes  after  cooling  under  the  desiccator 
are  weighed.  This  method  is  not  so  perfect  as  the  solution  method.  M. .  Pontio 
afterwards  gives  the  complete  results  of  the  analyses  that  he  has  carried  out  by  this 
method,  which,  although  not  possessing  the  exactitude  of  certain  more  complicated 
methods,  is  amply  sufficient  for  all  practical  purposes.  He  also  publishes  the 
processes  he  has  employed  for  separate  determination  of  sulphur  in  the  different 
states  in  which  it  occurs  in  manufactured  rubber.  As  above  stated,  he  has  altered 
(Bull,  de  la  Soc.  Chim.,  4  Ser.  t.  5,  p.  428, 1909)  the  design  of  his  lixiviating  digester, 
so  that  the  roses  with  funnels  underneath  each  are  arranged  in  a  circular  battery 
form,  their  number  being  increased  to  six,  and  made  several  other  modifications  in 
his  processes.  But  we  cannot  afford  further  space  to  his  methods,  except  to 
remark  that  his  group  4  solvent  is  now  cumol  vapour,  and  that  a  layer  of  about 
2  grammes  of  china  clay  is  placed  in  an  8  c.c.  diameter  filter  in  which  the  sample 
is  placed  in  the  extracting  funnel. 

Some  years  ago,  Dr.  Schultze  of  London  claimed  that  the  greater  number  of  the 
prejudices  against  the  use  of  "substitutes  are  unfounded.  Dr.  Axelrod,  Chief 
Chemist  of  the  Kabelwerk-Oberspree,  near  Berlin,  also  urges  that  the  same  is 
the  case  with  brown  floating  substitutes,  and  that  these  substitutes  are  not 
oxidised  by  atmospheric  oxygen,  and  the  perishing  of  the  rubber  need  not  be 
feared  from  that  cause.  Further,  it  need  not  be  made  a  grievance  against  substitutes 
that  they  contain  free  non-saponifiable  oil ;  on  the  contrary,  this  oil  which  may  exist 
with  a  percentage  of  35  per  cent,  facilitates  the  homogeneous  distribution  of  the 
substitute  in  the  rubber.  One  knows  that  the  substitute  will  mix  well  with  the 
rubber  when  it  can  be  rolled  into  a  thin  transparent  sheet.  It  is  even  advan- 
tageous, he  urges,  to  have  a  larger  proportion  of  oil  than  the  above,  in  the  case  of  certain 
mixtures.  It  may  even  be  found  up  to  45  per  cent. ;  acetone  and  hot  alcohol 
easily  extract  this  oil.  As  it  is  not  oxidisable  it  plugs  up  the  pores  of  the  rubber, 
and  the  latter  does  not  oxidise  so  readily.  The  same  result  may  be  obtained  by 
the  use  of  a  certain  amount  of  resin  or  paraffin.  The  following  is  a  mixture 
for  red  washers  :— 

TABLE  LXXXV.— MIXING  FOE  RED  WASHERS. 


Manaos  rubber    . 
Golden  sulphide  . 
Flowers  of  sulphur 
Brown  floating  substitute 


Per  cent. 


x 

7 

0'063x-3-15 
96'15x-l-063x 


In  the  above  formula,  x  may  be  taken  as  having  a  value  between  90 '44  and  50  per 
cent.  The  tensile  strength  will  be  higher  the  greater  the  amount  of  rubber 
used. 

Nobel's  Patent.— Patent  No.   235,829,  taken  out  by  Mr.  Nobel  on  the  26th 


RUBBER   SUBSTITUTES  285 


January  1  *'.'!,  for  obtaining  a  new  substance  capable  <rf  bein^  used  as  a  substitute 
for  rubber,  as  well  as  for  gutta  percha,  leathers,  ami  \arni>hes,  of  which  the 
originality  alone  o\ten»  a  new  field  of  investigation  to  our  n  •>•  -ar»  -h  <  -In  -ini-t-,  as  \\rll 
as  to  those  in  the  trad.-  always  in  ipu-st  of  the  new  and  the  best:  —  By  dissolving, 
in  a  substance  which  lends  itself  to  the  purpose,  nitrocellulose,  oxynitrocellulose,  or 
hydronitrocellulose,  products  are  obtained,  tin-  con^trncy  of  which  is  proportionate 
to  the  pi-ojM.rtion  of  nitrocvlluloM-  etl'ectively  dis.-olveo!  ;  it  is  in  this  way  that 
celluloid  is  formed,  which  consists  most  generally  of  two  i>arts  of  nitrocellulose  for 
one  part  of  camphor.  Leaving  decidedly  explosive  substances  out  of  account, 
celluloid  is  the  only  substance  thus  obtained  which  can  be  utilised  in  industry. 
However,  many  attempts  have  been  made  to  produce  more  or  less  analogous 
substances,  but  less  rich  in  nitrocellulose,  and  capable  of  replacing  rubber,  gutta 
percha,  leathers,  as  well  as  form  utilisable  leathers:  even  the  substance  patented  in 
liritian  in  1891  by  Fredr.  Crane,  under  the  No.  3315,  and  which  consists  of 
sulphuretted  oils,  does  not  yield  the  results  promised.  It  is  for  want  of  solvents 
really  fulfilling  the  end  in  view  that  attempts  have  failed.  My  researches  have 
enabled  me  to  discover  numerous  solvents  for  nitrocellulose,  oxynitrocellulose,  and 
hydronitrocellulose,  bodies  which  I  shall  hereafter  call  by  the  inclusive  name  of 
nitrocellulose,  in  proportions  appropriate  to  the  end  in  view  —  substances  of  such 
an  elasticity  and  consistency  that  they  may  advantageously  replace  rubber,  gutta 
percha,  leather,  and  varnishes.  To  be  suitable  for  the  above-named  purposes,  a 
solvent  should  possess  the  following  properties  :  —  (1)  It  should  dissolve  nitro- 
cellulose as  freely  and  completely  as  possible,  without  there  being,  within  the 
ordinary  limits  of  temperature,  either  exudation  or  separation^  of  the  solvent,  or 
want  of  plasticity  of  the  product,  or  a  tendency  to  become  brittle.  (2)  It  ought 
to  enable  products  to  be  obtained  which  withstand  moisture  and  direct  contact  with 
water.  (3)  It  ought  to  be  as  little  inflammable  as  possible,  so  that  the  product 
obtained  be  neither  so  explosive  nor  so  combustible  as  to  render  its  use  seriously 
dangerous.  (4)  It  ought  to  be  fixed,  or  at  least  so  little  volatile,  that  the  products 
obtained  undergo  no  change  in  consequence  of  the  gradual  evaporation  of  the 
solvent.  (5)  It  ought  to  have  sufficient  chemical  stability,  so  that  no  spontaneous 
decomposition  may  take  place.  In  order  to  find  solvents  for  the  production  of  the 
above-named  substances  fulfilling  these  conditions,  I  have  had  to  search  amongst 
substances  unknown  as  solvents  of  nitrocellulose,  for  the  above-mentioned  purposes. 
They  are  enumerated  below  :  — 

1.  The  chloro  and  bromo,  as  well  as  the  chloro-  and  bromo-nitro  derivatives  of 
camphor,  —  nitrocamphor,  nitrocymenes,  nitrotolulols,  di-  and  tri-nitrobenzols,  nitro- 
xylols,  nitrocumols,  nitronaphthalines,  mtranilines,  as  well  as  the  chloro  and  bromo 
derivatives  of  all  these  substances  ;  chloro-  and  bromo-nitro  benzol,  chlorhydrins, 
acetins,  acetochlorhydrins,  and  camphorins,  nitrated  rosin  oils,  in  particular  those 
obtained  by  the  distillation  of  rosin  soaps,  as  well  as  their  chloro  and  bromo 
derivatives.  Castor  oil  may  be  added  to  the  above-named  solvents,  provided  that 
it  be  not  used  to  such  an  extent  as  to  endanger  the  solubility,  so  that  exudation 
occurs  either  on  heating  or  cooling.  2.  The  above-mentioned  solvents  mixed  or 
combined  with  one  another. 

By  chloro  and  bromo  derivatives  I  mean  here,  and  throughout  this  descriptive 
memoir,  chlorine  and  bromide  addition,  as  well  as  substitution  products.  The 
solvents  which  are  solid  at  the  ordinary  temperature  should  be  melted  or  dissolved 
in  a  liquid  solvent,  so  as  to  facilitate  the  incorporation  of  nitrocellulose  with 
these  solvents.  As  nitrocellulose  is  never  a  homogeneous  substance,  the  most 
suitable  kind  for  the  puri>ose  can  only  be  chosen  by  experience,  the  more  so  as  for 
economical  or  other  reasons  one  solvent  will  be  preferred  to  another,  and  because 
the  best  cellulose  for  one  solvent  is  not  always  the  best  for  another.  But  a  slight 
preliminary  test  will  easily  determine  whether  the  right  degree  of  elasticity  or 
consistency  has  been  obtained.  It  is  important  to  note  that,  with  equal  solubility, 
the  least  nitrated  cellulose  (obtained  by  direct  nitration  by  weak  acids,  or  by 
denitration  by  means  of  known  processes  of  a  strongly  nitrated  nitrocellulose)  is  to 


286 


INDIARUBBER 


be  preferred,  since  by  its  use  the  inflammability  of  the  product  may  be  reduced  to 
a  minimum.  Amongst  these  solvents  the  above-mentioned  chloro  and  broino 
derivatives  are  those  which  most  attenuate  the  inflammability  of  the  product. 
Nitrocellulose  may  be  dissolved  in,  or  incorporated  with,  the  above-mentioned 
solvents,  either  in  the  moist  or  in  the  dry  state.  In  the  first  case,  incorporation 
with  the  liquid  solvent,  dissolved  or  melted,  is  very  easily  accomplished  by 
mechanical  mixing.  In  the  second  case,  it  is  preferable  to  facilitate,  by  the 
addition  of  good  volatile  solvents,  such  as  acetone,  ether,  alcoholised  ether, 
methylic  alcohol,  ethylic  acetate,  the  incorporation  of  the  dry  nitrocellulose.  In 
both  cases  the  substance  should  be  mixed,  either  in  a  good  mechanical  mixer, 
heated  by  steam,  or  between  the  cylinders  of  a  roller  machine,  likewise  heated  by 
steam,  and  the  work  should  be  continued  until  the  substance  becomes  perfectly 
homogeneous  and  presents  the  desired  consistency.  If  the  final  product  be 
intended  to  be  used  at  a  temperature  above  the  normal,  the  proportion  of  dissolved 
nitrocellulose  ought  to  be  increased,  as  the  consistency  of  the  product  decreases  in 
direct  ratio  with  the  temperature.  It  would  be  useless  to  specify  here  the  great 
number  of  solvents  which  may  be  obtained  by  mixing  or  combining  the  above- 
named  solvents,  and  I  confine  myself  to  enumerate  below  some  good  solvents  which 
may  serve  as  types  : — 

TABLE  LXXXVI. — SOLVENTS  CAPABLE  OF  BEING  USED  TO  DISSOLVE  NITRO- 
CELLULOSE CLAIMED  IN  NOBEL'S  PATENT. 


1.  Five  parts  of  nitrocumol, 

Three  parts  of  mononitronaphthaline. 

2.  One  part  of  nitrocymene, 
One  part  of  nitrocumol, 

One  part  of  mononitronaphthaline. 

3.  Bromocamphor. 

4.  Chloro-  or  bromo-nitrotoluol. 

5.  Chloro-  or  bromo-nitrocamphor. 


6.  One  part  of  nitrated  rosin  soap  oil, 
One  part  nitrocumol, 

One  part  mononitronaphthaline. 

7.  One  part  bromonitrotoluol, 
One  part  mononitronaphthaline, 
Two  parts  of  nitrocumol, 

Two  parts  of  nitrated  rosin  soap  oil. 


By  dissolving  in  one  of  the  above  or  equivalent  solvents  15  to  20  per  cent,  of 
its  weight  of  nitrocellulose,  a  very  elastic  mass  is  obtained,  so  much  resembling 
rubber  that  it  may  be  mistaken  for  it.  Between  30  and  40  per  cent,  the  substance 
approaches  in  properties  more  to  the  nature  of  gutta  percha.  If  the  nitrocellulose 
be  still  further  increased,  the  product  presents  the  appearance  and  consistency  of 
leather. 

If  the  solvent  be  very  viscous,  as  is  the  case  with  the  nitrated  rosin  oil,  it 
requires  much  less  nitrocellulose  to  be  dissolved  to  obtain  the  same  consistency  than 
is  used  with  very  fluid  solvents. 


SECOND  PART 


GUTTA    PERCH A 

I'M>KR  the  name  of  gutta  percha  are  described  \rry  diverse  products,   an 
\vhich  there  is  thus  established  a  confusion  which  is  very  annoying  and  prejudicial 
to  industry  in  general 

"  It  is  of  great  interest  to  see  light  dawn  on  a  question  which  up  to  now  has 
been  so  obscure.  The  study  of  the  botanical  origin  of  those  products  which  up  to 
the  present  time  have  been  grouped  under  the  name  of  gutta  percha  is  still  but 
very  little  advanced,  in  spite  of  the  works  of  numerous  savants.  It  is  necessary 
that  the  greatest  efforts  be  made  to  establish  the  botanical  origin  of  all  the  com- 
mercial varieties  of  gutta  percha,  and  that  as  far  as  possible  the  methodical 
cultivation  of  the  trees  which  yield  good  varieties  be  propagated  and  developed  so 

as  to  prevent  their  disappearance." 

DR.  BEAUVISAGE,  Paris. 


HISTOKICAL  INTRODUCTION 

IK,    mi    the   one    hand,    I'Yance   can    claim    tin-    In nr   of  being  tin-    first    Kuropean 

nation  t<>  re.-ei\ .-  and    utilise   sample-   of    I  n<l  i,i  ,-nl,l,,  /•„  (Ireat    Britain,   on  the   other 
hand,  wa-  tin-  first   Kuropean  country  to  rcceixe  and   utilise  samples  of'//"""  /"/•'•//</. 

Cutta  percha,  which  the  native  Malay  race  of  the  peninsula  .if  Malacca,  of  the 
islands  of  Sumatra  and  IJorneo,  utilised  from  a  very  remote  but  undeteriiiined 
epoch.  \\a-  first  introduced  into  Kurope  by  the  Kngli>h  traveller  .John  Tradescant 
under  the  name  of  .!/":</•  \\'<><>d.  According  to  Obach,  tlie  first  sample  of  gutta 
percha  was  brought  into  Europe  by  those  "indefatigable  travellers  ami  curiosity 
hunters,  the  Tradescants,  father  and  son,  somewhere  about  the  middle  of  the 
seventeenth  century.  On  page  I  I  of  .!///>•.///,«.  Tradesca ./////////////,  or  a  Collection  »'' 
Rarities  preserved  cU  Smith  Lamheth  neer  London  (a  small  book  by  John  Trade- 
si-ant  the  younger,  published  in  1656),  there  is  included  in  a  list  of  such  rarities  as 
"  Birds'  nests  from  China,"  "Indian  Fiddle,"  "Blood  that  rained  in  the  Isle  of 
Wight,"  and  so  on,  a  descriptive  entry  of  a  very  interesting  item,  namely,  "  The 
plyable  .)/</:'/•  ll'o"/,  l>eing  warmed  in  water,  will  work  to  any  form."  This  entry 
is  believed  to  have  referred  to  a  sample  of  gutta  percha,  because  no  other  substance, 
adapted  for  use  as  a  raw  material  for  making  mazers  or  goblets,  having  the 
peculiar  property  of  becoming  plastic  in  warm  wrater,  and  capable  of  being  worked 
to  any  form,  in  the  same  way  as  the  "plyable  mazer  wood,"  is  known  at  the 
present  day.  What  eventually  became  of  this  sample  of  "mazer  wood''  i- 
unknown.  The  renowned  Elias  Ashmole  obtained  possession  of  the  collection  after 
the  decease  of  the  younger  Tradescant,  which  occurred  in  1662.  The  new  owner 
removed  the  collection  to  Oxford  to  form  the  nucleus  of  the  Ashmolean  Museum, 
oj>ened  in  1 683,  but  the  historical  sample  in  question  is  now  neither  at  the  Museum, 
nor  at  the  Botanic  Garden  at  Oxford. 

In  the  year  1843,  two  rival  candidates,  both  of  whom  were  surgeons,  and  both 
residents  of  Singapore,  claimed,  each  for  himself,  the  honour  of  reintroducing  gutta 
percha  into  Kurojie.  One  of  those,  whose  name  betokens  Spanish  descent, 
Dr.  Jose  d'Almeida,  carried  samples  with  him  to  London  in  the  spring  of  !SI-">. 
These  samples  consisted  of — (1)  "a.  riding  whip,  made  of  the  concrete  milk  of  a  tree 
indigenous  in  Singapore,  called  gutta  percha  by  the  Malays;  also  ('2)  a  specimen  of 
the  concrete  milk  in  the  lump,"  with  the  remark  that  "  it  becomes  ductile  by  being 
placed  in  hot  water."  The  secretary  of  the  Royal  Asiatic  Society  appears  to  have 
acknowledged  the  receipt  of  the  above  specimens  in  a  letter  dated  8th  April  1^  !•">. 
and  to  have  handed  for  analysis  a  portion  of  the  raw  substance  to  Dr.  J.  F.  Royle. 
It  would  also  appear  that  Mr.  W.  C.  Crane  had  previously  received  a  similar 
portion,  also  for  analysis,  but  from  d'Almeida  himself.  But  neither  of  these  two 
gentlemen,  entrusted  \\ith  the  samples  for  analysis,  seem  ever  to  have  discharged 
the  duty  which  devolved  ui>on  them.  They  apparently  made  no  experiments, 
or  at  least  no  report  on  the  samples  with  which  they  were  entrusted,  and,  had  it 
not  been  for  the  samples  of  the  rival  candidate  having  fallen  into  more  discreet, 
skilful,  and  fortunate  hands,  it  does  not  seem  far  from  improbable  that 
d' Almeida's  samples  WOUld  ha\e  shared  the  same  fate  as  Trade-rant's  "  ma/cr  wood." 
In  ;iny  case,  no  results  were  immediately  forthcoming  as  the  result  of  d'Almeida 
submitting  hi-  >amples  to  the  1  loyal  Asiatic  Society.  Better  fortune,  however, 
attended  the  course  pursued  by  the  rival  candidate  to  Dr.  d'Almeida,  for  the 
19 


290  GUTTA   PERCHA 

honour  of  reintroducing  gutta  percha  into  Europe.  This  was  ])r.  William 
Montgomerie,  who,  through  the  medium  of  his  brother-in-law,  Mr.  H.  Gouger, 
submitted  samples  to  the  Society  of  Arts  during  the  summer  of  1843.  These  samples 
consisted  of — (1)  "One  bottle  of  the  juice";  (2)  "specimens  of  thin  sheets 
resembling  scraps  of  leather  " ;  (3)  "  specimens  of  the  substance  formed  into  a 
mass  by  agglutinating  the  thin  sheets,  by  means  of  hot  water."  In  this 
instance,  as  already  hinted,  almost  immediate  results  attended  the  submission 
of  the  samples.  At  a  meeting,  held  on  30th  November  1843,  the  Joint  Committee  of 
Chemistry,  Colonies,  and  Trade  took  into  consideration  specimens  of  a  substance 
called  "  gutta  percha,"  from  Singapore,  sent  to  the  Society  by  Dr.  Montgomerie ; 
and  at  a  subsequent  committee  meeting,  on  23rd  January  1845,  it  was  resolved 
"  that  this  substance  appears  to  be  a  very  valuable  article,  and  might  be  employed 
in  great  advantage  in  many  of  the  arts  and  manufactures  of  the  country."  Again, 
at  an  ordinary  weekly  meeting  of  the  Society  of  Arts,  on  10th  March  1845, 
Mr.  Francis  Whishaw,  the  secretary  of  the  Society  of  Arts,  described  the 
specimens,  and  exhibited  a  piece  of  pipe,  and  a  lathe  band  of  gutta  percha, 
which  he  had  made  therefrom,  and  which  were  afterwards  on  show  at  the  Great 
Exhibition  of  1851.  Mr.  Whishaw,  not  content  with  these  practical  demonstrations, 
covered  the  bottle,  in  which  the  milky  juice  was  originally  received,  with  gutta 
percha,  softened  in  hot  water.  It  is  supposed  to  have  been  at  this  meeting  that 
Mr.  Christopher  Nickles,  as  one  of  the  audience,  acquired  his  first  knowledge  of 
gutta  percha,  and  so  impressed  was  he  with  the  intrinsic  value  of  the  product, 
that  he  induced  Messrs.  Wilkinson  and  Jewesbury,  dealers  with  Singapore,  to  import 
a  small  trial  order.  Mr.  (afterwards  Sir)  William  Siemens  first  saw  the  product  at 
the  same  meeting,  and  he,  then  and  there,  secured  the  samples,  which  he  afterwards 
despatched  to  his  brother,  Werner  Siemens,  in  Berlin,  to  test  their  suitability  for 
insulating  telegraph  wires,  a  suggestion  which  has  been  attended,  in  the  insulation 
of  submarine  cables,  with  results  the  effects  of  which  cannot  be  over-estimated. 

It  followed  as  a  natural  sequence  that  the  Society  of  Arts,  having  so  promptly 
and  efficiently  assessed  the  value  of  gutta  percha,  and  found  several  uses  for  it, 
awarded  Dr.  Montgomerie  on  2nd  June  1845,  its  gold  medal.  Montgomerie  first 
became  acquainted  with  indiarubber  in  1822,  when  he  acted  as  assistant-surgeon 
to  the  Presidency  at  Singapore.  He  then  lost  sight  of  it  for  twenty  years,  namely, 
until  in  1842,  when  he  noticed  a  parang  or  woodchopper,  in  the  hands  of  a  Malay 
woodman,  the  handle  of  which  appeared  new  to  him.  His  curiosity  was  still  further 
aroused  when  he  learnt  that  the  substance  had  the  peculiar  property  of  becoming  soft 
and  plastic,  like  clay,  in  boiling  water,  and  he  at  once  possessed  himself  of  the  article, 
and  asked  the  Malay  to  procure  him  as  much  of  this  substance  as  possible. 

French  writers  assert  that  the  first  experiments  in  the  use  of  gutta  percha  were 
not  encouraging ;  English  manufacturers,  they  claim,  were  not  able  to  appreciate 
this  very  peculiar  substance  at  its  real  value.  But  some  of  these  samples  were  sent 
to  Paris,  where,  on  the  data  of  Montgomerie,  they  were  made  into  probes  and 
other  surgical  instruments  formerly  made  of  rubber.  Montgomerie  failed  to 
persuade  the  London  surgical  instrument  makers  to  give  it  a  trial.  In  1845 
Lagrenee  brought  back  with  him,  on  his  return  from  an  expedition  to  China,  a 
certain  quantity  of  gum  plastic  which  he  was  able  to  secure  during  his  passage 
through  Singapore ;  he  submitted  it  to  the  French  Minister  of  Commerce.  The 
substance  put  at  the  disposal  of  the  French  manufacturers  was  better  examined, 
and  in  the  following  year,  Alexander,  Cabriol,  and  Duclos  took  out  the  first 
French  patent  for  the  use  of  gutta  percha  (28th  July  1846).1  This  first  patent 
is  here  given  as  a  historical  document.  It  shows,  moreover,  all  the  illusions  which 
were  readily  conceived  at  the  outset  in  regard  to  this  new  gum — illusions  which 
were  not  long  in  being  dispelled. 

The  Cabriol  French  Patent  of  28th  July  1846.— "It  consists  in  lining 
both  sides  of  a  fabric  of  any  kind  of  cloth,  paper,  or  leather,  with  gutta  in  very 

/But  Hancock,   Brooman,   and   Nickles  had   previously  taken   out  British   patents   for 
utilising  gutta  percha. 


HISTORICAL    INTRODUCTION  291 


itself, 
I 

fcfc 

and  IP  'in'  iLjvne'  iii-*,  tit  t< 
nie( hate  tal >ric  < >r  c« ire,  and  am 
position  of  the  two  slie"ts  of  gutta  percha,  s 
thread  of  the  roller,  preyed  in  the  hot  state 
of  birth  amongst  us,  and  a  new  indiiMrv  wa- 
follow  step  hv  step  the  various  phases  through  which 
the  moment  when,  its  essential  properties  being  better  studied  and  better  known, 
gutta  percha  took  its  definite  place  in  the  diU'erent  applications  to  which  it  was 
thought  it  should  In-  applied.  It  \\ill  >ullice  to  say  that,  as  a  new  product,  it  was 
employed  for  all  the  purposes  first  re-erved  for  rubber.  People  became  infatuated 
with  it.  Patents  multiplied,  one  in  emulation  with  another.  Corks,  cements, 
threads,  slippers,  surgical  instruments,  garments,  pipe>,  sheathing  for  ships,  were 
all  made  of  it,  and  even  boats  were  made  wholly  of  gutta  percha;  and  it  is  only 
necessary  to  read  the  reports  of  the  regretted  M.  P.allard  on  the  London  Kxhibition 
of  1851,  to  be  conxinced  of  the  exaggerated  enthusiasm  incited  by  this  new  di> 
covery.  Of  all  these  applications — more  or  less  judicious — there  now  only  remain- 
but  the  memory,  and  if  it  were  not  for  some  quite  social  uses,  the  gutta' percha 
of  Sumatra  would  very  soon  have  been  abandoned  by  industry.  In  fact,  tin 
characteristic  properties  of  gutta  percha  are  such  that  they  are  opposed  to  all  tin- 
uses  to  which  it  was  put  at  first.  An  eminently  plastic  substance  at  a  but  slightly 
elevated  temperature,  it  was  natural  to  see  garments  as  well  as  slippers  made  of 
this  material  soften  with  the  heat  of  the  fire  when  it  was  approached.  It  was 
attempted  to  correct  this  defect  by  vulcanisation,  wrhich  had  just  imparted  to 
rubber  its  real  industrial  importance,  but  there  again  they  were  deceived  in  regard 
to  the  real  properties  and  the  nature  of  the  body  which  they  tried  to  vulcanise. 
The  action  of  sulphur  and  halogens  upon  gutta  can  in  no  way  be  compared  to  that 
of  these  reagents  on  rubber.  The  illusions,  therefore,  held  in  regard  to  this  sub- 
stance were  only  of  short  duration,  and  it  was  really  to  the  special  properties  of 
gutta  percha,  and  more  particularly  to  its  malleability  at  a  comparatively  low 
temjieratiiiv,  as  was  well  said  by  M.  Ouibal  in  his  report  on  the  Kxhibition  of 
1878,  that  the  cause  of  the  relative  non-success  of  the  new  industry  was  due.  It 
must  not  be  imagined  that  gutta  percha  is  a  substance  now  little  utilised  and 
capable  of  being  easily  replaced.  It  is  a  very  necessary  substance  indeed,  and 
its  discovery,  as  well  as  the  study  of  its  properties,  occurred  at  the  jxsychological 
hour  (at  the  right  time),  and  that  it  was  thus  enabled  to  find  its  true  place  in 
industry.  Suppose  gutta  percha  had  been  put  on  the  international  market  simul- 
taneously w  ith  rubber,  it  is  evident  that  at  that  moment,  when  dynamical  electricity, 
electro-metallurgy,  as  well  as  the  real  scientific  work  of  chemical,  medical,  and 
photographical  laboratories  were  hardly  known,  gutta  percha  would  have  been 
relegated  to  the  class  of  substances  of  but  little  importance,  and  assuredly 
Seligmann  Lui,  P.eauvisage,  Serrula/.,  P.urck,  and  ever  so  many  others,  would  not 
have  been  sent  to  the  Indian  Archipelago  to  search  for  gutta  j>ereha,  nowadays 
regarded  as  indispensable  to  international  life  and  transactions.  Discovered,  on 
the  contrary,  at  tin-  moment  when  dynamical  electricity  had  already  commenced  to 
play  a  rather  important  n'.le.  the  insulating  properties  of  gutta,  its  extraordinary 
plasticity,  and  finally  it-  inalterability  in  water,  or,  better  still,  in  salt  water,  were 
very  soon  perceived,  and  thus  ^utta  percha  came  to  be  used  in  the  making  of 
telegraph  cables  (Patents  of  \V.  11.  P.arlow  and  Th.  l-'orster,  1847,  and  K.  \V. 
Siemens,  -jjJnl  April  1850).  Wheatstone,  who  from  1 S37  had  tried  to  con- 
nect England  telegraphically  with  the  Continent,  had  perceived  the  advantages 


292 


GUTTA   PERCHA 


presented  by  wires  covered  with  gutta  percha,  but  his  idea  was  not  realised  by 
Walter  Breit,  who,  on  the  10th  January  1849,  immersed  the  first  submarine  cable 
at  Folkestone  of  two  miles  in  length.  In  the  interval,  gutta  percha  had  been  used 
for  the  preparation  of  moulds  intended  to  reproduce  designs  of  very  fine  delicacy 
by  electro-metallurgical  processes.  The  resistance  which  gutta  percha  presented  to 
acids  was  likewise  taken  advantage  of  in  the  making  of  vessels,  funnels,  and  tubes, 
the  use  of  which  has  become  general  in  chemical  manufacture,  in  photography,  and 
in  laboratories.  The  medical  art  has,  in  fact,  found  in  it  a  precious  auxiliary  in 
the  manufacture  of  a  great  number  of  surgical  instruments.  Gutta  percha  has 
therefore  only  changed  its  employment ;  but,  in  spite  of  the  fact  that  this  substance 
was  very  soon  only  used  sparingly,  and  that  the  immoderate  waste  in  the  beginning 
has  ceased,  its  use  has  none  the  less  assumed  such  an  extension  that  the  limited 
resources  which  nature  presents  to  us,  under  this  head,  would  appear  to  be  likely 
to  be  exhausted  in  the  near  future.  The  governments  of  all  civilised  nations  are 
therefore  justified  in  becoming  alarmed  at  this  state  of  affairs,  more  so  that  the 
Malays  and  Papuans,  more  greedy  of  immediate  lucre  than  anxious  to  ensure  the 
future  of  their  production,  have  neither  sought  a  rational  method  of  collection  nor 
of  improved  culture,  the  only  methods  capable  of  increasing  or  maintaining  the 
original  annual  production.  Felling  mercilessly  the  producing  trees,  and  only 
extracting  the  guttiferous  latex  but  very  imperfectly,  they  make  a  gap  round  about 
them  to  such  an  extent,  that  if  we  look  at  the  prices  paid  in  the  beginning  and 
those  now  paid  for  even  inferior  goods,  we  are  really  frightened  at  the  constant 
progressive  rise  in  the  price  of  gutta  percha.  But  not  to  anticipate ;  we  shall  have 
occasion  to  return  to  this  subject,  so  full  of  interest,  and  examine  what  has  been 
done  and  what  remains  to  be  done  to  cope  with  the  danger  of  an  eventual  dearth 
of  gutta  percha.  The  elucidation  of  the  reasons  why  governments,  scientists,  and 
manufacturers  attach  so  much  importance  to  this  question  will,  moreover,  be 
facilitated  by  the  study  of  the  botanical  sources  and  the  chemical  and  physical 
properties  of  this  substance.  But  let  us  state  at  the  outset  that  this  study  bristles 
with  difficulties.  We  get  swamped  in  a  labyrinth  where  others,  more  competent 
than  we,  have  gone  helplessly  astray,  and  we  have  only  one  object :  to  profit  by 
their  experience  and  their  weary  efforts  to  be  able  finally  to  throw  some  light 

TABLE  LXXXVII. — OBACH'S  ANALYSIS  OF  HISTORICAL  SAMPLES  or  THE 
COAGULATED  LATEX  OF  ISONANDRA  GUTTA  (HOOKER). 


No. 

After  Drying  in  Vacuo. 

Gutta  Percha  Proper. 

Percentage  Composition. 

Total. 

Ratio. 

Percentage  Composi- 
tion. 

Gutta. 

Eesin. 

Dirt. 

G.  P. 

(G.+R.). 

Gutta. 

Gutta. 

Resin. 

Resin. 

1    . 
2    . 
3    . 

70-4 
74.5 
75-6 

17-6 
14-2 
18-3 

3-0 
4-3 
16-1 

97-0 
95-7 
83-9 

4-5 
3-0 

o-i 

81-8 
74-6 
90-1 

18-2 
25-4 
9-9 

1.  Piece  of  riding  whip  sent  by  Lobb  from  Johor,  and  so  described  on  slip  of  paper  found  with 

another  of  Lobb's  samples  to  Kew  Herbarium  in  1846,  and  described  by  Sir  W.  Hooker 
as  wood  (London  Journal  Sot.,  1847,  vol.  vi.  p.  33).  Very  light,  hard,  fibrous,  showing 
ebony  black  lines;  yielded  very  light  strong  gutta  and  light  yellow  soft  resin.  A 
sample  from  Johor,  collected  about  1890,  contained  90  per  cent,  of  gutta  proper  with  only 
8  per  cent,  resin  quality. 

2.  Cover  of  tin  box  in  which  flowering  branch  of  Isonandra  gutta  was  sent  toSir  W.  Hooker 

(Land.  Journal  Bot.t  1847,  vol.  vi.  p.  464).  Dark  brown,  hard,  containing  dirt  and 
small  pieces  of  bark  ;  yielded  light  brown  strong  gutta  and  light  yellow  soft  resin. 

3.  Coagulated  latex  of  offspring  of  same  tree  as  Lobb's  botanical  specimen,   collected  by 

hemilaz  in  1847.  Light  brown,  hard,  contained  5  per  cent,  water ;  yielded  light  brown 
not  very  strong  gutta,  and  light  yellow  soft  resin  (Lum.  Elcctr.,  1890,  vol.  38,  p.  411). 


HISTORICAL   INTRODUCTION  293 

where    it    would    appear    pleasure    had    IM-I-M    taken    in    increasing   the    darkness. 
|)r.     l>ran\  !-.!•_:<•.    in   a    l-rilliant    inaugural    tln^i-.    "<  'out  riltiit  ions   to   the   Study  of 
Gutta   I'ercha,  "  deli\eivd    in    I'.iri      OH    tin-    Mtli    |-VI,niar\    |SS|,  took  a-  his  motto 
I    Lafoiitaine 

"D'uUml  il  -s'y   pi'it   m.-il,   puis  1111   JHMI  niit-nx,   puis  liini, 
I'uis  i-uliu  il  n'y  nciiuiii.i  ricn."1     (Livrc  XII.  f.  ix.  ) 


\\Vdu  n«»t  li-»|n'  that   in  <mr  l»«>ok  //  //•  mctnqWTQ  /•/'.  it  (nothing  will  be  deficient)  ; 

hut  \\f  have  tin-  tirin  n.nvictitin  that  \\itli  thr  lii-lp  of  iln-  niinici-oii-  rorarch- 
our  jii-rdcct-ssors,  and  as  far  as  tin-  actual  state  of  tin-  knowledge  that  haa  been 
actjuircd  will  allow  —  -we  also  will  mntri!»nt«'  to  make  tin-  s|»hinx  sj»t-ak,  of  which 
Lron  lirassc  rt-ct-ntly  said,  "tin-  more  he  studied  ^utta  |>erdia  from  a  practical 
point  of  view,  the  more  obscurities  he  found  in  it"  (Ltunii,;  /•,'/,  r/  /•/'-////,  October 
.  vol.  4G,  pp.  51,  109,  160). 

1  "First  he  set  about  it  badly,  theii  a  little  better,  then  well  ; 
Then  at  last  he  was  quite  proficient  at  it." 


CHAPTEK  I 


DEFINITION  OF  GUTTA  PERCHA— BOTANICAL  ORIGIN-HABITAT 


THE  gutta  percha  latex  is  contained  in  isolated  receptacles  or  sacs  mainly  in  the 
inner  parts  of   the  bark.     It  is  also  present  in  the  leaves.     Fig.   105  B   shows 

a  section  through  a 
small  branch,  and 
(Fig.  105^)  through 
a  leaf.  Numerous 
latex  receptacles,  L, 
in  the  primary  and 
secondary  bark, 
B.P.  and  S.B.  of 
the  branch,  as  well 
as  in  the  pith,  P. 
The  sections  through 
the  leaf  show  in  one 
case  the  termination 

of  two  latex  sacs,  and  in  the  other  the  course  of  one  of 
them  within  the  imperfect  cellular  tissue  or  merenchyma. 
The  club-shaped  end  and  general  bone-shaped  form  of 
the  lacticiferous  vessels,  with  their  segmentary  division, 
is  characteristic  of  true  gutta  percha  plants,  and  is  not 
found  in  other  Sapotaeese.  When  the  bark  is  cut  or 
bruised,  and  the  capillary  sacs  and  tubes  which  contain 
the  latex  are  ruptured,  it  flows  out  with  greater  or  less 
abundance  according  to  the  species  of  the  tree.  This 
milk  possibly  serves  in  the  plant  economy  as  a  protection  ; 
still  it  is  primarily  an  excretion,  since  it  is  discarded  by 
the  tree  in  its  dead  leaves  and  bark,  and  the  bark  of  the 
live  tree  can  be  tapped  and  the  latex  removed  with  no 
apparent  injury  to  the  tree. 

A  chemical  examination  of  the  milk  or  latex  coming 
from  the  gutta  percha  trees  upon  wounding  the  bark, 
shows  it  to  be  composed  of  an  emulsion  of  water  and  oil 
in  a  finely  divided  state.     According  to  the  species  of 
tree,  the  water  varies  from  a  small  (best  species)  to  a  very 
large   percentage  (poor  species).     A   drop   of  the   milk 
caught  on  the  finger  undergoes  no  apparent  change  for 
a  few   minutes,   but  by    the   end    of   this  time   a   thin 
rubbery  scum  can  be   observed  to  have  formed  on  the 
surface.     If  this  be   removed,  a  second  film  will  form, 
FIG.  105. — Microscopic  sec-  and  so  on  until  the  entire  drop  has  become  a  small  piece 
tion  through  A,  leaf  of  of  a  tough,  leathery  substance.     When  a  fresh  drop  is 
branch"'  B>   worked   between   the    fingers    the  hardening  process    or 

coagulation  takes  place  very  quickly,  and  by  boiling  or 

adding  certain  chemicals,  such  as  mineral  or  vegetable  acids,  alum,  salt,  etc.,  it 
takes  place  almost  instantaneously.     What  the  nature  of  this  hardening  process 


DEFINITION   OF  GUTTA   PERCHA  295 

is  appears   in   be  unknown.      Tin-  subject    is   being   in\e>tig.it«-d    in    tin-  Philippine- 
laboratory.       .\Mi-r   <•.. adulation    BOte    in,  tin-   "il\    portion  becomes  hard  and   tough, 

while  most  of  the  water  sep  i  i-  endo-ed  mechanically  (Sherman). 

Gutta  percha  a>  it  .-Mines  to  Kur« -pean  market-  is  usually  in  the  form  of  large 
blocks  of  \arious  shapes  cylindrical  rolls,  sijiiaiv  cakes.  Hat  bottles,  etc. — which 
arc  characteristic  to  a  certain  extent  of  the  district  win-no-  th«-\  OOma  >omct  ime- 
the  nati\e  collect., r  -hou-  arti-tic  tendencies,  and  moulds  the  gutta  |e|,-ha  into 
the  shape  of  birds  alligators,  etc. 

Ihtfi  r>  iiti'itinn  t,,tii;,  i,  iinli'iriibb,  ,•  ii,nl  </nff<t  /»  rr/m  ;  .«/////////•  », •,'</,', >  <,t'  I ,,(!>. 
At     first    sight    t/iitfn    IH  ,-,'lm    (///////////I-/////    /i/iisfinim) — which    should    I.e    written 
t/in  itffn  i"i-t'-h'<,  to  gi\e  it  its  true  proiiunciat  ion-  -is  a  vegetable  product  aii«il«'_- 
to  rubber,  as   much    by   its   method   of   format  ion    in    nature  as  by  its  composition. 
Like    rubber,    it    originates    in    the    milky  juice   of    certain    trees,    and   again,    like 
rubber,  it  would  appear  to  consist    essentially  of  a  hydrocarbide,  in  which   its  two 
elements,  carl.on  and  h\drogen,  arc  ]>rcsent  in  somewhat  similar  proportion-. 

.1  iri'l.  ,1 1  <]',,-,  ,n;  l>,tir,,,i  f/tn'r  /,/•<>/„  ,-f  <'<•*. — But  there  the  likeness  stops  ;  and 
it  is  difficult  to  understand  how  t\\o  substance-,  so  dissimilar  in  propertie-,  \\,-i-e 
COapled  together,  at  random  as  it  were.  Tlu-sc  propi-rtics,  so  very  different,  \sere 
admirably  described  by  Moi'ellct  in  his  inaugural  thesis  pre\  ioiisly  <|Uoted. 

Ih'tJ'i-n  nt  net  inn  of  t/t>  <•//<!  ,//<;i/  f'u,-«->-  nn  f//>  f/ro  liodies. — "  Kubl>er,' 
Morellet,  "is  essentially  an  elastic  body,  i.e.  but  little  capable,  in  its  natural 
state,  of  preserving  in  a  permanent  manner  the  change  in  shai>e  which  a 
mechanical  force  acting  upon  it  causes  it  to  undergo;  whereas  gutta  i>ercha  can 
preserve  those  changes  of  shape  produced  on  it  by  the  action  of  forces  of  the 
same  nature." 

Comparative  action  of  heat  on  indiaiiibber  and  gutta  perc/ia. — "Natural 
rublnir,  that  is,  rubber  wrhich  has  not  been  treated  with  sulphur,  indeed  softens 
and  becomes  more  malleable  under  the  action  of  heat,  but  it  preserves  its  elasticity 
if  the  heat  does  not  exceed  certain  limits,  beyond  which  it  loses  its  properties,  and 
consequently  is  profoundly  altered,  not  only  in  its  physical  properties,  but  in  its 
chemical  proj>erties  as  well.  But  under  the  action  of  a  heat  so  regulated  that  it 
doea  not  exceed  100°  C.  (212°  F.),  in  boiling  water,  for  example,  gutta  pcivha 
becomes  a  highly  plastic  and  malleable  substance,  capable  of  preserving,  on 
cooling,  the  api>earance  and  shapes  given  to  it  at  that  temperature." 

Their  essential  differences  embodied  in  ttie  Latin  names  of  the  two  substances. — 
These  two  principal  characteristics  are  distinctly  brought  out  in  the  Latin  terms 
by  which  science  has  designated  the  two  different  substances,  in  giving  to  rubber 
the  name  of  i/nnuin'i-mn  rArxV/o////,  and  to  gutta  jiercha  the  name  <>f  <IH minn-tun 
phuticum. 

Comparative  action  of  air,  liyht,  and  moisture  on  the  two  bodies. — Rubber, 
under  the  simultaneous  action  of  the  air,  of  a  regulated  temperature,  and  time, 
gradually  loses  its  properties,  and  becomes  converted  into  a  tacky,  viscous,  more 
or  less  fluid  substance.  Gutta  percha,  under  similar  conditions,  behaves  quite 
differently,  and  changes  into  a  brittle,  resinous  body.  These  transformations  are 
more  or  less  long  in  manifesting  themselves,  according  to  the  different  varieties 
and  the  conditions  of  the  experiment.  Water  and  a  low  temperature  retard  these 
changes  of  state  in  the  two  products.  It  is  i»erhaps  in  these  properties  that  the 
greatest  difference  exists  between  the  two  substances  wrhich  are  being  differentiated 
from  one  another. 

Comparative  action  <>?'  *///y //////•  <>n  rubber  and  gutta  percha.  —  Another  dis- 
tinction of  capital  importance  is  that  exhibited  when  these  two  substances  are 
treated  with  sulphur.  It  is  easy  to  combine  rubber  with  sulphur  so  as  to  obtain 
a  homogeneous  elastic  substance,  preserving  at  different  temj>eratures  below  150° 
C.  (302°  F.)  the  same  pro{»erties  as  at  the  ordinary  temperature  ;  whilst  if  it  be 
attempted  to  combine  gutta  percha  directly  with  sulphur  the  operation  is 
unsuccessful,  in  spite  of  every  precaution  which  may  be  taken;  and  if  it  be  tried 
to  combine  an  intimate  mixture  of  rubber  and  gutta  percha  with  sulphur,  more 


296  GUTTA  PERCHA 

or  less  negative  results  are  obtained,  just  as  gutta  percha  enters  into  the  mixture 
in  greater  or  less  proportion.  When  gutta  percha  enters  into  the  rubber  mixture 
to  a  greater  extent  than  10  per  cent,  the  operation  fails,  and,  on  vulcanisation, 
there  is  only  obtained  a  product  showing  on  the  surface,  and  also  when  cut, 
numerous  blowholes  and  vesicular  cavities.  In  the  trade  the  mixture  is  said  to 
puncture  on  vulcanisation. 

Difference  in  dielectric  properties.  —  The  dielectric  properties  of  the  two 
substances  are  far  from  being  identical,  and  that,  moreover,  is  one  reason  why  it 
is  not  desirable  to  confuse  gum  elastic  with  gum  plastic.  The  above  are  the  most 
striking  characteristics  which  differentiate  essentially  between  the  two  products. 
They  are,  moreover,  further  explained,  as  by  the  essentially  different  botanical 
origin  of  the  plants  from  which  they  are  produced,  as  well  as  by  the  nature  of  the 
latex  secreted.  But  before  proceeding  further  it  is  necessary  to  define  well  the 
value  of  the  term  gutta  percha.  Here,  again,  we  are  in  presence,  not  of  different 
properties,  but  of  data  furnished  by  men  of  science,  explorers,  and  manufacturers, 
which  have  nothing  in  common  with  similar  information  on  the  botanical  origin 
of  rubber.  Whilst  every  one  is  agreed  in  acknowledging  that  it  is  the  Heveas 
which  yield  Para  rubber,  i.e.  the  prototype  of  the  species,  all  is  obscurity  and 
contradiction  when  it  is  a  question  of  establishing  the  botanical  origin  of  com- 
mercial gutta  percha,  and  it  would  seem  that  a  malignant  pleasure  had  been  taken 
in  obscuring  the  question  rather  than  in  bringing  some  perspicuity  and  method 
to  bear  upon  it. 

Manufacturers,  merchants,  travellers,  scientific  men,  and  even  governments, 
tried  to  find  sources  of  gutta  percha  in  other  regions  of  the  intertropical  zone, 
in  other  trees,  whether  belonging  to  the  Sapotacece  or  not,  and  which  had 
not  been  previously  examined  from  this  point  of  view.  "This  period  of 
research  is  still  going  on.  The  results,  collected  by  science  in  different 
parts  of  the  world,  are  very  numerous,  but  very  imperfect,  and  have  not,  as 
yet,  given  the  desired  practical  results.  Scientific  men  discovered,  in  the  Indian 
Archipelago,  Indo-China,  Hindostan,  tropical  Africa,  the  Guianas,  Brazil,  etc.,  trees 
the  juice  of  which  may  yield  a  good,  a  mediocre,  or  a  bad  gutta  percha.  They 
determined,  with  greater  or  less  care  and  exactitude,  the  physical  and  chemical 
properties  of  these  different  products,  but  their  investigations  ended  there,  whilst 
manufacturers  continued  to  receive  most  diverse  substances,  through  numerous 
savage  or  civilised  merchants,  who  could  not  or  would  not  (for  a  very  good  reason  if 
we  consider  the  point  well)  give  exact  indications  upon  the  botanical  origin,  nor 
even  upon  the  exact  geographical  origin  of  these  products.  The  diversity  of  these 
is  such  that  it  would  appear  impossible  to  determine  the  properties  by  which  one 
could  recognise  the  substance  designated  under  such  and  such  a  commercial  name. 
Any  attempt  to  scale  the  commercial  price  current  is  absolutely  vain ;  to  clear  up 
this  question,  another  road  must  be  followed,  and  we  must  try  to  recognise,  at  the 
place  of  arrival,  products  whose  origin  and  properties  could  be  better  studied  at 
their  point  of  departure.  That  is  ivhat  I  attempted  to  do,  but  in  which  I  have  in 
no  way  succeeded.  The  success  of  such  a  tentative  does  not  appear  impossible  to 
realise,  but  it  would  require  long  years  of  profound  research,  and  collaboration  of  a 
great  number  of  enlightened  but  disinterested  persons."  That  which  was  an  almost 
insurmountable  difficulty  for  Dr.  Beauvisage  in  1881  is  a  little  less  so  to-day,  thanks 
to  the  labours  not  only  of  Beauvisage  himself  and  his  predecessors,  from  the  days 
of  Montgomerie,  i.e.  Lobb,  Bentham,  Hooker,  Oxley,  Wight,  de  Vriese,  Burck, 
Pierre,  Seligmann  Lui,  Brau  de  St.  Pol  Lias,  and  Serrulaz,  but  also  and  more 
especially  to  the  labours  and  discoveries  of  Heckel,  Schlagdenhaufen,  Jungfleisch, 
and  of  L.  Brasse,  Obach,  etc.  L.  Brasse,  in  La  Lumiere  Electrique  (see  Biblio- 
graphy), imparted  at  last  some  order  to  the  classification  of  commercial  gutta 
perchas,  and  thus  enabled  us  to  get  at  the  real  origin  of  the  producing  plants. 

Leon  Br usse's  researches. — Leon  Brasse,  whom  a  long  experience  of  practical 
manufacture  initiated  into  the  real  wants  of  the  industry,  seems  to  have  best  grasped 
the  only  way  of  looking  at  the  question,  and  his  work  may  be  resumed  in  that 


DEFINITION   OF  GUTTA  PERCHA  297 

charai-t>Ti-tic    phra-r  \\hidi    limits   out    all    its    |. radical  value  :    "'/'//•    •///•  s'/'./i  hat 

,i/<r,,,/.<  been  /«/<//// /«x'"/"/"/ .•  tl«r>  />•  n»t  «  //""  /  /•///•/  «*/'//////«/  /»/•••/,,,  /,„/  teveral 

</-,<>,/    kin-It.   ><«•/,    <>l'    irliii'l,    ,-,  sy  ,.///./>•    A-    '/    i;  rl,i  i,,    IM6,   .//ii/    //     /x    ///..<-     x/,,o,  x   //•///<•// 
n/i'ui/'t    I"    propagab   ;          !'•>    W    po-iulatin;:    tin-   «|ii«v-ti«.n,    l.ron    I'.rasse    not    nnl\ 

(NUlltfil     ..lit      tllf      real      road      \\hich      should      In-      taken      to     elucidate     >o     important 

and  >till  9Q  obeCUre  a  -uKjrct,  l.iit  In-  also  supplied  us  with  pivcioiis  docum.-nt-. 
tin-  lu-st  .if  their  kind  kii"\Mi  up  to  n<>u,  and  ue  do  not  hesitate  to  appropriate 
tin-in,  I'Ut  ii'it  \\ithoiit  rendering  homage  to  tin-  -cienee  and  to  tin-  talent  of  tin- 
\\riter.  lint  In-  lia>  made  u-e  of  and  I.e.-n  aided  hy  the  ri'sean-hi-s  of  the  mm  of 
sci.-nce  previously  quoted,  lie  has  l.een  abl<-  to  coordinate  tin-in  in  such  a 
inanner  thai  to  attempt  to  do  Letter  \\oiiM  In-  ditlieiilt  in  the  pre-mt  Mate  of  OUF 
knouled^e.1  At  the  coniineiicriiient  of  the  manufacture  of  submarine  cal.l.-<.  • 
were  abundant,  only  good  qualities  were  used,  only  large  trees  were  exploited,  and 
those  which  yielded  an  inferior  product  not  at  all.  "But,  as  we  can  satisfy 
oiir-rlves  b\-  examining  tin-  pi'oduets  preserved  in  collections,  different  qualities 
of  gutta  percha  were  even  then  used  in  admixture.  What  proves  it  is  that  the 
tools  used  at  this  epoch  for  the  cleansing  of  the  gum  resin — tools  still  in  use  at 
the  present  day  in  some  manufactories — could  not  have  purified  Isonandra  gutta, 
if  it  had  not  been  previously  mixed  with  more  plastic  varieties.  Later  on,  owing 
to  the  good  qualities  becoming  rare,  more  and  more  inferior  kinds  were  introduced 
into  the  mixture,  and,  to  obtain  the  good  qualities  which  were  used  in  less 
proportion,  but  which  it  was  necessary  to  use  as  far  as  possible,  recourse  had  then 
to  U-  made  to  barely  adult  trees.  The  production  of  prime  quality  gutta  percha 
had  thus  become  reduced  to  such  a  minimum,  and  its  price  so  high,  that  at  the 
Electrical  Congress  of  1881  the  necessity  was  recognised  of  applying  a  system 
of  rational  culture  to  the  gutta  percha  plants.  Hence  the  mission  of  Seligmann 
Lui,  who  visited  the  east  coast  of  Sumatra  and  the  western  coast  of  the  Malay 
Peninsula.  Early  in  1883,  Wray  explored  the  State  of  Perak  on  its  western 
coast,  and  Burck  studied  all  the  guttifers  of  Sumatra.  Since  then  Serrulaz 
attempted,  in  several  voyages,  to  finish  the  work  of  Seligmann  Lui,  and  in  1871 2 
he  refound  the  Isonandra  Hooker  in  the  same  ravine  of  Boukett-Timah  where 
Lobb  first  discovered  it  in  1847.  These  expeditions  revolved  in  the  same  circle. 
They,  however,  agreed  passably  between  each  other.  Seligmann  and  Burck  give 
tin-  preference  to  the  Dichopsis  oblonyifolium.  Wray,  who  explored  Perak,  reports 
in  it  the  Dichopsis  pustulatum  (Pierre),8  and  Serrulaz,  who  remained  in  the  environs 
of  Singapore,  refound  the  Dichopsis  gutta  or  Isonandra  gutta.  It  is  to  be 
regretted  that  these  explorations  were  all  conducted  on  the  rivers  of  the  Strait 
of  Malacca,  because  the  gutta  percha  produced  by  this  region  is  not  the  best  of 
that  which  we  use;  and,  besides,  the  yield  in  yutta  percha  of  an  Isonandra  is 
•i*i,nlnf,lij  miserable.  There  ought  to  be  three  of//'/'  <intta  percha-proiln<-ii"ti  y/A» ///>•. 
<iii'iii<i  <>  /niter  dtnl  iiini-f  tiiiiiinhnit  <intt<i,  <ind  that  is  what  Leon  Brasse  proposed 
i-amine.  If,  in  the  future,  the  juice  of  the  Dichojtsis  or  Palaqtriwn  <iutf>t, 
oblon<ii/<>tiinii  or  pustul< it /////,  should  be  alone  available  for  industrial  purposes,  it 
would  be  necessary  to  modify  the  methods  of  manufacture,  and  the  result  might 
be  quite  different  from  that  expected.  Whilst,  with  a  continuous  supply  of  the 
kinds  UM-d  in  the  beginning,  before  the  dearth  forced  very  inferior  secies  of  gutta 
percha  to  be  used,  future  submarine  cables  will  last  equally  long  as  those  which 
have  given  such  good  results."  Byzantine  discussions  as  to  whether  the  word 
</ntt<i  i»  ,-<•//'!  is  indeed  the  appellation  which  should  be  given  to  the  substance,  or 
it  ,/nffti  to!,-!,!  or  tiil.nii  should  1x3  substituted  for  it,  need  not  find  a  plan-  In  re. 
Custom,  rightly  or  wrongly,  has  adopted  the  name  gutta  percha  to  designate 

1  Obach  (Cantu,  lias  since  thrown  more  light  on  the  problem.     The  translator 
has  condensed  and  embodied  some  of  his  Tables. — TR. 

2  See  translator's  Preface.     The  correct  date  on  the  face  of  it  is  1887.— TK. 

3  W ray's  samples,  analyses  of  which  are  given  on  p.  318,  are  in  custody  of  Kew  authori- 
ties and   Institute  of  Electrical  Engineers.     He  started   on  his  expedition  early  in  1883. 
l)iuvk,   who  started  towards  end  of  that  year,  discovered  fourteen  species  of  gutta  percha 
yielding  ti 


298  GUTTA   PERCHA 

commercial  gum  plastic.  We  shall  therefore  definitely  adopt  that  term;  and  it 
only  now  remains  to  find  out,  at  the  proper  time,  if  there  be  not  several  varieties 
of  the  species,  and  if  it  be  not  desirable  to  give  to  the  chemically  pure  substance 
another  designation  by  which  it  may  be  distinguished  from  the  raw  product  from 
which  it  is  extracted.  As  to  the  true  meaning  of  the  term  gutta  percha  or  pertcha, 
according  to  Serrulaz,  the  word  gutta  (guetah  or  gueutta  in  the  Malay  language)  is 
only  used  in  an  absolutely  general  sense,  and  means  gum,  and  the  word  gom/nit<inftc 
(gamboge)  according  to  him  is  a  pleonasm.  The  word  Pertcha  or  Perfia,  which 
the  French  alone  pronounce  percha,  in  no  wise  signifies,  as  all  explorers  assert, 
Sumatra.  Sumatra,  in  Malay,  is  termed  Perna,  that  is  to  say,  the  world,  the 
terrestrial  portion  inhabited;  whilst  Pertcha  signifies  rag,  strip  of  cloth  (Efty/ix/i, 
scraps),  and  designates  very  exactly  the  appearance  of  gums  which  before  treat- 
ment with  hot  water  present  ;  the  appearance  of  rags  reduced  to  paste  and 
compressed.  It  would  not,  therefore,  be  astonishing  if  this  designation,  which 
does  not  belong  to  common  Malay,  had  been  employed,  not  by  the  native  working 
in  the  forest,  but  much  rather  by  the  merchant  belonging  to  a  higher  class  in 
those  countries.  This  opinion  may  be  taken  as  true,  or  at  least  the  most  probable, 
and  the  matter  allowed  to  drop.1 

The  botanography  and  habitat  of  gutta  percha  trees. — The  botanical  origin  of 
gutta  percha  as  well  as  the  questions  which  relate  to  the  habitat  of  guttiferous 
plants  must  now  be  dealt  with.  As  soon  as  the  valuable  properties  of  gutta  percha 
had  been  recognised  in  Europe,  and  a  demand  had  been  created  for  the  article,  the 
countries  all  around  Singapore  were  searched  with  great  avidity  for  Taban  trees, 
and  almost  a  craze  for  getah-collecting  sprang  up  amongst  the  indigenous 
population.  The  consequence  was  that  an  immense  number  of  trees  of  great  size 
and  age,  probably  hundreds  of  thousands,  were  ruthlessly  destroyed  during  the 
first  four  or  five  years,  and  whole  forests  denuded  of  them,  like  those  of  Singapore. 
The  exploration  was  conducted  with  such  assiduity,  that  before  the  year  1848 
came  to  a  close,  the  much  coveted  Taban  tree  had  already  been  discovered  in 
Pahang,  Johore,  Malacca,  Selangor,  Perak,  and  Penang  on  the  Malay  Peninsula, 
besides  the  islands  of  Rhio,  Gallang,  and  Singga  in  the  Johor  Archipelago.  It 
had  also  been  met  with  in  Siak,  Kampar,  Indragiri,  Tongkal,  Jambi,  and 
Palembang,  on  Sumatra,  and  in  Coti,  Passir,  Pontianak,  Sarawak,  and  Brunei  on 
Borneo.  Since  that  time  the  tree  has  been  found  in  the  northern  and  north- 
eastern parts  of  Borneo,  on  the  west  coast  of  Sumatra,  and  in  some  other  districts 
on  the  east  and  west  coasts  of  the  Malay  Peninsula.  But  if  the  flora  of  temperate 
climates  contains  a  certain  number  of  rubber-producing  plants,  in  relatively  feeble 
quantities  it  is  true,  and  if  the  tropical  and  intertropical  zones,  bounded  by  the 
thirtieth  degrees  of  north  and  south  latitude,  are  the  chief  rubber-producing 
districts,  it  is  not  so  with  gutta  percha.  Only  an  extremely  limited  zone — 
represented  by  that  belt  of  land  situated  between  the  third  degree  of  south  and 
fifth  degree  of  north  latitude — is  adapted  for  guttiferous  vegetation.  Moreover, 
every  one  knows  that  the  Asiatic  continent  is  separated  from  the  geological 
Oceanian  continent  by  a  deep  submarine  fault  of  at  least  200  metres  (656  feet), 
stretching  along  the  Islands  of  Sumatra  and  Java,  to  enter  by  the  Strait  of  Bali 
into  the  Java  Sea ;  there  it  distinctly  separates  the  Celebes  (Australian  continent) 
from  the  Borneo  group  (Asiatic  continent),  goes  round  about  Borneo  to  divide 
into  two  ramifications,  one  towards  the  Soulon  Isles  and  the  other  towards  the 
Gilolo  Islands.  The  fauna  as  well  as  the  flora  on  each  side  of  this  fault  are 
perfectly  distinct.  On  the  Australian  side  neither  arengani  palms,  teak-wood, 
ferns,  orchids,  nor  the  mosses  of  the  Java  flora  are  to  be  found.  There  are  no 
more  tigers  nor  other  felines,  and  the  greater  number  of  the  birds  which  live  in 
the  woods  of  Borneo,  Java,  and  Sumatra  are  unknown.  It  is  the  same  in  regard 
to  the  plants,  which  readily  yield  real  gutta  percha. 

The  real  gutta  percha  country  forms  only  a  very  limited  extent  of  land,  and 
belongs  exclusively  to  the  Asiatic  continent,  and  is  situated  between  the  102°  and 
1  Tschirsch  Die  Harze,  etc.,  p.  894,  1906,  says  Percha  is  an  old  name  for  Sumatra. 


DEFINITION   OF  GUTTA  PERCHA  L>99 

112°  of  French  longitude.  Tin-  French  meridian  passes  tlin.ii^li  I'ari-.  Accurd- 
ing  to  Obaeh,  tin-  u'Utta  percha  re-jimi  extends  <i  <>n  either  side  •  •!  tin-  r<|iiat<>r,  and 
from  '.>'.»  in  111*  longitalde  east  of  Greenwich.  Total  area,  1,1  10,000  .Mj  nan-  miles. 
Of  terrestrial  area  I'Sfi.Ooo  -ipiaiv  miles  (  10  per  rent.)  «.nl\  l»nt  small  portion 
locally  suitable  for  growth  of  gutta  percha  trees.  The  A-iatie  part  is  the  productive 
region  of  gutta  percha  in  the  proper  sense  of  the  word. 

That  is  nut  tci  say  that  .it her  countries  situate* I  near  to  the  equator,  and 
bounded  on  the  north  as  well  as  on  the  south  by  the  above-mentioned  latitud 
incapaltle  of  furnishing,  if  nut  gutta  |>ereha  properly  so  called,  at  least  analogous 
resins,  (^uite  the  contrary ;  and  \\eshall  see  in  the  sequel  that  it  is  precisely  in 
those  parts  of  the  g]ol,r,  and  in  those  parts  only,  that  the  sagacity  of  the  searcher 
should  l»e  exercised,  so  as  to  remedy  the  ever-increasing  gutta  pen1  ha  dearth  of 
.Malasia  and  I'apua. 

\o\shere  else  on  the  globe,  outside  the  area  of  the  Malay  Archipelago,  have  any 
•funftie  gutta  j)ercha  trees  Uvn  found,  and  this  is  the  more  remarkable  as  the 
Sti/Hitmrii-  to  which  they  belong  are  distributed  all  over  the  tropics,  and  are  also 
of  great  a ntiquity,  having  even  representatives  amongst  the  fossil  plants.  It  might, 
pei  haps,  1,,.  asked  whether  gutta  trees  have  not  been  found  in  the  islands  adjacent 
to  those  confined  by  the  boundary  line  on  the  map ;  for  instance,  in  the  large  group 
to  the  north  of  Borneo,  the  Philippines,  or  the  islands  Celebes  and  Java,  to  mention 
only  the  more  important  ones.  The  answer  is,  that  hitherto  no  genuine  gutta  perch  a 
trees  have  been  discovered  there.  Getah  trees,  in  the  Malayan  sense  of  the  word, 
exist,  no  doubt,  but  none  of  the  right  description.1 

Sapotacece  or  Sapotads. — However  that  may  be,  as  it  is  the  family  of  Sapotacece 
which  yields  the  greater  portion  of  guttiferous  plants,  it  will  be  useful  to  give, 
according  to  Baillon,  a  very  summary  botanical  description  of  this  family  of  the 
yaniopetalous  sapotaceous  dicotyledons.  Of  gamopetalous  dicotyledons,  with  regular 
flowers  and  convex  receptacles :  The  corolla  is  generally  imbricated,  and  bears  four 
or  five  fertile  stamens,  placed  above  its  divisions.  Moreover,  alternate  staminodes 
are  often  observed.  The  latter  may  be  awanting ;  and  sometimes  also  the  number 
of  stamens  exceeds  those  of  the  lobes  of  the  perianth.  The  superior  ovary  is 
hollowed  by  1  to  5  cells,  rarely  more,  placed  above  the  sepals,  and  each  containing 
an  ascending  ovule,  with  an  exterior  and  inferior  micropyle.  The  fruit  Is  a  berry, 
and  the  grains  have  often  a  long  and  wide  hilum,  which  occupies  a  large  portion  of 
their  internal  edge,  cutting  moreover  into  the  surface  of  the  seed,  which  is  smooth 
and  polished.  The  ascendant  seed  is  albuminous  or  exalbuminous.  Trees  or  shrubs 
of  tropical  regions,  generally  rich  in  milky  juice,  which  often  forms  gutta  percha. 
Leaves  generally  alternate,  with  or  without  stipules.  Flowers  solitary  or  in  cymes, 
often  implanted  in  the  wood  of  the  stems.  This  family  is  often  divided  into  the 
Bassice  (Illipo3\  Zi/r////m.-,  .!////<//*'/«/,  Hum- 1  in-,  and  Chrysophyla;.  [This  latter 
group  should  perhaps  disappear  (Pierre).]  Amongst  the  numerous  tribes  of 
Sapotacece  it  is  evidently  those  belonging  to  the  genus  Dichopsis  (or  Palaquunn  or 
IfiHtndra)  which  yields  the  greatest  number  and  the  best  varieties  of  guttiferous 
trees.  The  only  really  important  ones  would  appear  to  be — 1.  The  Dickopsi*  gutta 
(Th.  Lolih,  Ik-nth,  et  Hook.),  or  Pabi^unun  ;/nf(<i  (Burck),  or  honatnlr<t  </»ft<i 
(Serrula/).  i'.  The  /;/r//o/,x/x  oblongifoliwn  (Beauvisage,  Burck),  or  PalaqtUum 
nhlmnt (folium  or  Isonandra  oblonyifolia  (Brau  de  St.  Pol  Lias,  Teysmann).  3.  The 
Dichoptii  or  Palaqwwm  Borneense  of  Teysmann,  the  Dichopsis  or  Palaquium 
'/'/>  n'lii  and  its  variety  parvifolium  (Burck).  4.  After  the  genus  Dichopsis  or 
Palaqmwn  come  the  genus  Payena,  that  of  the  J///////xo/>«,  and  finally  that  of  the 
Bassia. 

1.  Dichopsis  gutta — (Botanical  details  according  t<>  /in irk). — Folia  petiolata 
obovatb-obl<> />•/»  fa  rfter  acuminata,  nervis  secundariis  infolii  substantiamiin 
20-30  utrinque :  Aroor  elata,  ramuli  junior es  rubiyinoso-pubescentes.    Folia  niodice 

1  Sherman,  loc.  cit.,  says  the  area  of  the  other  [than  Palaquium  gutta]  or  inferior  species 
IH  extended  eastward  so  as  to  take  in  the  Philippines,  Celebes,  Java,  and  the  northern  half  of 
the  Malay  Peninsula. 


300 


GUTTA   PERCHA 


petiolata,  sub-coriacea,  obovata-oblonga,  supra  viridia  subtus  aureo-nitentia,  breviter 
acuminata  1 1  centim.  longa,  supra  medio  4/2  centim.  lata,  basi  in  petiolum  gradient 
l'5-2'5  centim.  longum  attenuata,  nervis  lateralibus  arcuatis,  parallelis  subhori- 
zontali-patentibus  20-30  utrinque  in  folii  substantiam  immersis  via  conspicuis. 
Alabastrum  ellipso'ideum.  Flores  axillares,  soepius  in  axillis  foliorum  delapxonnn, 
fasciculati.  Fasciculi  2-6  flori.  Flores  2  millim.  longi,  pedunculati.  Pedunculi 
3  millim,,  ,  Calyx,  ellipso'ideo-campanulatus,  laciniis  ovatis,  aureo-nitidis,  exteriori- 
bus  coriaceis  subvalvatis,  interioribus  tenuioribus.  Corolla  subrotata :  tubo 
calicem  vix  superante,  laciniis  tubo  cequilongis  lanceolo-ovatis  v.  dipticis^  obtusis, 
patentibus.  Stamina  12  biserialia.  Filamenta  cequalia  filiformia  laciniis  corolla 
cequilonga.  Anther  OB  ovatce,  glabrce,  acutce.  Ovarium  subglobosum,  pubescens. 
Stylus  filiformis  staminibus  longior.  Stigma  obtusum.  Bacca  carnosa,  ovoidea 
calycis  laciniis  suffultafusco-tomentosa,  3  "5  centim.  longa,  2*5—3  centim.  lata,  pluribus 
loculis  abortientibus  obsoletis.  Semina  1,  2,  v.  3,  ellipso'idea  vel  a  latere  compressa 
testa  crustacea  nitida,  kilo  magno,  seminis  sufterficiei  majorem  partem  obtegente. 


FIG.  106. — Branch  of  Dichopsis  gutta  (Palaquiun  gutta,  Isonandra  gutta). 


Burck  gives  the  above  description,  as  this  species  up  to  then  had  not  been 
exactly  and  completely  described,  no  botanist  having  seen  either  the  fruit  or  the 
seeds ;  and  because  the  Dichopsis  gutta  is  a  plant  which  yields  an  excellent  product, 
and  which,  in  virtue  thereof,  should  be  cultivated  by  the  Netherlands  Government. 
To  these  details  it  will  be  useful  to  add  those  given  by  Obach,  Professor  Baillon  or 
Dr.  Beau  visage. 

Obach  describes  the  Dichopsis  gutta  as  follows  : — "  It  is  a  lofty  tree  with  a  per- 
fectly straight  cylindrical  trunk,  and  has.  when  fully  grown,  a  height  of  from  60 
to  80  feet,  and  a  diameter  of  2  to  3  feet ;  but  it  appears  that  in  some  localities,  Perak, 
for  instance,  trees  considerably  over  150  feet  high,  and  4  to  5  feet  in  diameter,  have 
been  met  with.  The  leaves  are  crowded  together  at  the  ends  of  the  branches  and 


DEFINITION   OF  GUTTA   PERCHA  301 

;uv  placed  alternately  ;  their  form  i>  oln.vate  lanceolate,  ;in<l  tln-\  lia\.-  a  -mall   pn.jec 

(inn  or  beak  at  tin-  a|»ex.  Leaves  from  old  trees  mea-mv  about  4  to  5  inches  in 
length,  and  !•'•  tii'J.l  indies  in  \\idtli  at  tin-  middle:  u  heivas  t  IK  ,-.-  from  young  trees 
are  mudi  larger,  reaching  ;i  length  ..t  !»  inches  and  a  breadth  of  nearly  .'i  indies. 
I  purpnsdy  mention  this  in  order  to  slm\\  that  \  ariat  ion*  in  t  he  shajM-  and  HI 
the  leaves  are  not  alone  siitlicient  to  indicate  a  ditlerence  of  species,  a8  has  sou i e 
times  Keen  suppo-ed.  The  upper  surface  .if  the  lea\v>  is  bright  -iv.-n  and  the 
underside  golden  l.r..\vn,  \\hen  the  trees  are  young,  and  reddish  bro\\n  \\hen  old, 
this  colour  ln-iii-,'  due  to  the  presence  of  a  dense  layer  of  silky  hairs,  which  abb 
cover  the  mid  rib  and  the  petiole ;  the  latter  is  usually  about  an  inch  or  a  little  more 
in  length.  The  secondary  veins  branch  out  laterally  from  the  mid-rib,  nearly  at 
right  angles,  and  are  not  very  conspicuous,  being  sunk  in  the  substance  of  the 
leaf.  They  number  20  or  30  on  each  side,  which  is  of  some  iin|M,rtance  to 
know,  as  we  shall  see.  The  flowers,  of  which  there  are  four,  grouped  together  in 
the  axil  of  the  leaves,  are  white,  the  calyx  being  of  a  golden  brown  colour :  there 
are  twelve  stamens  in  single  series,  inserted  into  the  throat  of  the  corolla  with  sagit- 
tate anthers,  turned  outwards.  The  ovary  is  su^rior  and  six-celled,  terminating  in 
a  single  style,  which  is  much  longer  than  the  stamens.  The  fruit  is  a  fleshy  egg- 
shai>ed  berry  about  1 J  inches  long  and  1  inch  in  diameter." 

Further  botanical  details  of  Dichopsis  gutta  (Jiaillon,  Beauvisaye). — The 
group  of  young,  unexpanded  flowers  comprises  six  flowers  in  a  dichotomous  cyme, 
in  the  middle  of  which  is  a  cicatrice,  apparently  left  by  the  fall  of  the  flower  of 
the  first  generation.  This  inflorescence  is  accompanied  by  decussate  bracts.  The 
gamosepalous  calyx  consists  of  three  external,  coriaceous  subvalvular  divisions, 
and  of  three  thinner,  internal,  imbricated  divisions,  alternating  with  the  former. 
The  corolla  consists  of  six  twisted  divisions,  alternating  with  the  sepals,  so  deep 
that  the  corolla  is  hardly  gamopetalous.  The  androecium  comprises  twelve  stamen-, 
all  apparently  fertile,  so  far  as  can  be  judged  in  so  young  a  flower.  In  spite  of 
their  small  dimensions,  two  different  sizes  may  be  recognised.  The  six  larger  are 
opposite  the  divisions  of  the  corolla;  the  six  smaller  are  alternate  with  tin- 
former,  and  with  the  divisions  of  the  corolla.  The  anthers  are  extrorse.  The 
">':i, •//  is  six-celled,  each  containing  an  ascending  ovule,  incompletely  anatropous, 
with  the  micropyle  inferior  and  exterior.  The  style  is  cruciform,  truncate,  then 
conical  at  the  apex.  The  young  fruit  is  ovoid,  conical.  Around  it  are  the  six 
persistent  sepals.  The  young  elongated  seed,  acute  at  the  top,  is  furnished  with 
a  coriaceous  envelope,  in  the  interior  of  which  there  would  appear  to  be  a  viscous 
albumen.  Serrulaz's  botanical  description  of  Isonandra  gutta. — Serrulaz  (Academic 
des  Sciences,  1890,  pp.  433-426),  gives  some  complementary  details  of  this  plant 
(the  prototype  of  the  gutta  percha  tree).  In  chronological  order  it  is  the  first 
plant  mentioned  as  a  producer  of  gum  plastic,  of  so  great  dielectrical  power,  and 
it  would  appear  to  have  played  the  same  role  in  the  history  of  gutta  percha  that 
the  Hevea  Guyanensis  has  done  in  that  of  indiarubber.  Both  of  them  known  and 
mentioned  from  the  outset,  the  one  as  yielding  gum  elastic  and  the  other  as  gum 
plastic  par  excellence,  at  the  present  day,  being  rare,  they  are  neglected ;  the  one 
being  replaced  in  industrial  exploitation  by  Hevea  Brazil  ii-nni*,  the  other  by 
Dichopsi*  oMongifoliwn.  "The  Isonandra  gutta,  at  the  age  of  thirty  years,  i.e. 
when  full  grown,  has  a  trunk  of  13  to  14  metres  (43  to  40  feet)  up  to  the  origin 
of  the  lowest  branches,  and  a  very  regular  circumference  of  0'9  metre  (say  3  feet) 
at  2  metres  (say  6J  feet)  above  the  ground.  This  trunk  is,  moreover,  almo>t 
cylindrical.  The  leaves  of  the  young  tree  are  often  as  much  as  22  to  23  cm.  in  length 
by  7  cm.  wide  in  the  middle,  whilst  in  the  full-grown  tree  they  are  only  11  to  12 
cm.  in  length  by  1  t<»  ~>  to  (}  cm.  The  shape  and  size  of  the  leaf  in  the  !)!>•!,. ,j,.<;.< 
vary  so  much  with  the  age  of  the  plant  in  consideration  that  there  is  nothing 
astonishing  in  the  great  number  of  species  introduced  into  botany  from  the 
examination  of  the  branches,  destitute  of  floral  elements,  and  not  comparable 
between  themselves.  The  petiole  has  ;l  length  varying  between  1*75  and  3*75 
cm.  The  flowers  are  from  13  to  14  mm.,  and  the  peduncle  4  to  6  to  7  mm. 


302  GUTTA   PERCHA 

The  fruit  presents,  in  the  two  perpendicular  directions,  the  average  dimensions  of 
3  to  3 '5  cm.  by  2 '5  to  5  cm.,  and  sometimes  4  by  3  to  3 -5  cm.  The  seed  is 
generally  1'8  to  2  cm."  In  the  Malay  forests  traversed  by  Serrulaz,  during  four 
years  he  only  found  five  tress  capable  of  being  confounded  at  first  sight  by  their 
foliage,  and  in  reality  by  the  latex,  with  the  Isonandra  gutta.  There  can  be  no 
possible  confusion  with  the  other  Dichopsis,  which  are  likewise  differentiated  from 
it,  having  regard  to  the  quality  of  their  gutta,  by  the  Payena  Lerii  (Gutta 
Sandeck).  Serrulaz  considers  gutta  sandeck  as  a  complex  mixture,  but  he 
only  studied  the  Isonandra  gutta ;  he  thinks  it  the  plant  par  excellence  which 
furnishes  the  raw  material  for  the  manufacture  of  submarine  cables,  and  he 
regards  the  Bassia  Parkii  and  Mimusops  balata  guttas  as  only  giving  negative 
results.  He  regards  the  Payena  Lerii  as  only  of  service  in  yielding  an  apt 
adulterating  agent.  The  only  guttas  which,  according  to  Serrulaz,  can  be  used 
as  dielectrics  in  the  core  of  cables  are  secreted  by  trees  of  the  genus  Isonandra, 
with  an  exclusive  habitat  in  Malasia.  In  his  communication  to  the  Academy  of 
Sciences,  of  date  15th  September  1890  (pp.  423-436),  Serrulaz  says:  "The 
clearing  or  deforesting  of  the  interesting  zone  of  Malay  forests  is  going  on  at  a 
rapid  rate ;  the  native,  by  cutting  all  the  barely  ripe  trees  he  encountered,  and 
by  acting  similarly  with  their  shoots — that  is,  by  hindering  them  from  reaching 
the  adult  stage — has,  so  to  speak,  for  forty  years  suppressed  their  reproduction 
and  multiplication.  The  gutta  perchas  that  were  used  at  the  outset  of  the 
industry  are  now  only  found  exceptionally ;  those  which  have  replaced  them  will 
have  the  same  doom  in  about  fifteen  years.  Exportation  is  beginning  to  cease 
from  place  to  place  in  the  Malay  ports.  The  insufficient  plantations  undertaken 
in  the  Dutch  Indies  have  produced,  above  all  things,  not  the  best  species,  but 
those  whose  latex  is  most  abundant,  that  is  to  say,  the  least  valuable  kinds. 
Submarine  telegraphy  is  on  the  eve  of  seeing  itself  deprived  of  an  article  that  is 
indispensable  to  it  in  the  present  state  of  the  science,  and  the  origin  of  this  gutta 
remains  badly  known.  In  chronological  order,  the  first  plant  mentioned  as  a 
producer  was  the  Isonandra  gutta  (Hooker).  This  tree,  the  only  one  of  which 
the  coagulated  latex  was  sent  to  Europe  at  the  same  time  as  the  commercial 
samples,  and  which  had  been  passed  as  satisfactory  by  practical  men,  has  remained 
incompletely  described.  It  is  described  as  a  species  extinct  since  1857  in  the 
Island  of  Singapore,  which  no  longer  exists  in  the  Malay  forests.  In  reality 
this  species  has  become  very  rare,  but  it  still  subsists.  Adult  representatives  still 
multiply  (in  1887)  on  Chasseriau  estate,  in  the  ravines  of  Boukett-Timah  (tin 
hills),  situated  in  the  centre  of  Singapore,  where  it  was  discovered  in  1847  by 
Thomas  Lobb.  When  I  refound  it  in  1887,  all  exploitation  had  for  a  long  time 
(thirty  years)  ceased,  and  the  extinction  of  its  species  was  regarded  as  an  accom- 
plished fact.  Yet,  barely  three  years  ago,  in  the  last  scraps  of  the  ancient  forests 
of  this  island,  trees  of  this  nature,  then  already  full  grown,  still  existed,  represented 
more  especially  by  shoots.  There  only  existed  there  but  one  variety  of  a  single 
species  of  gutta  percha  tree,  which  agreed  with  the  specimens  figured  in  Plate 
XVII.  of  the  London  Journal  of  Botany,  vol.  vi.,  given  by  Hooker  of  his 
Isonandra  gutta"  (See  p.  284  and  translator's  Preface.) 

2.  Dichopsis  oblongifolium — Botanical  details  according  to  Burck). — Folia 
petiolata  v.  lanceolato-oblonga  longe  acuminata,  nervis  lateralibus  20-30  utrinque 
in  folii  substantiam  immersis  (Isonandra  gutta  var.  oblongifolia  de  Vriese, 
Isonandra  gutta  var.  B.  Sumatrana  miq.  Dichopsis  nov.  sp.  Beauvisage). 
Arbor  elata ;  ramuli  juniores  rubiginoso-pubescentes.  Folia  modice  petiolata 
oblonga  v.  lanceolato-oblonga  subcoriacea,  supra  viridia  subtus  aureo-nitentia,  longe 
acuminata  ;  folia  juniora,  reliquis  majora  usque  ad  22  centim.  longa,  7*5  centim. 
lata.  basi  in  petiolem  gracilem  l'5-2'5  centim.  longum  attenuata  nervis  lateralibus 
arcuatis  parallelis  horizontali  patentibus  20-30  utrinque  in  folii  substantiam 
immersis  vis  conspicuis.  Alabastrum  ov'iodeum.  Flores  axillares :  soepius  in 
axillis  foliorum  delapsorum  fasciculati.  Fasciculi  1-6  flori.  Flores  10  millim. 
longi  pedunculati. 


DEFINITION   OF  GUTTA   PERCHA 


303 


• 

l.n, 


\  '•>    '_'    inilliiit.: 
int,  rim-H'ii*  t'  /////"/•//,//>.        (',,,-olln  till,  ii.«'«l  i/,;  „,.*,  if*  r.in.x 

f»lt.   ,,l.   <    ////</<     XI/A     if/HI/i,tli/tl;         SliliiliilH       \  I'/,/.*  ,-i'lfi'l. 
tUit'nrilli'l      /ill-ill  flK      fn,-nUil      <  I  '  /  ll  i  I  •  >  II  ,/,  I  .          Alltkt'l'H      <//<{',  f<l      outfit 

()>;,,  -inin     sn/t;//iif>nsiini    pn6e*rr//x.        Sti/lux  jiliformis    ituiiiiniltus   A///./. 
n',t  n*n  in.      I  nosa,  avoid"!  rmliim  nt<>  x(t//i  <-<>r<>u<tt>i,  <-<ili/ri8  lacinnii*  *!///''///•/. 

/'">•'•  -  f'Hnentosa  3*5—  t  «v  //////*.  A»//./»/,  :?  :>-.")  r/  -///////.  A////.  /!////•/////.%•  A«-////x  ni><>i-ti,  /////,,/>• 
Semina  1,  2,  v.  3tellij)*o'idea  v.  a  latere  comprt*  nitida, 

seminis  majorem  j»irt>  ///  >•///.•  /;//.•/•  /  obtegente. 


FIG.  107. — Dichopsis  oblongifolium. 

Discovered  in  Sumatni  by  Teysmann  and  Burck. 
„  Borneo  by  Teysmann  and  Troinp. 

„  Rhio  Arcliij»elago  by  Teysmann. 

„  .Malacca  by  Bran  de  St.  Pol  Lias. 

On  the  eastern  coast  of  Sumatra  l.y  Srliuriiiann  Lui  (under  the  name  of  Mayang 
Derrian).  The  I)i<-ltnj,*i*  ni.luixi'i folium  is  the  Taban  Sutra  of  Perak.  It  is  very 
closely  allied  to  the  Taban  Mrrah,  and  its  <lisn.\vrn%  <lc  Vrir<r.  considered  it  merely 
a  variety  of  Hooker's  Isonandra  gutta.  However,  it  is  now  understood  to  be  an 
independent  species.  It  is  a  tree  of  smaller  si/.r,  \\itli  leaves  of  a  more  decided 
brown  on  surface.  The  flowers  have  a  reddish  tinp-.  and  the  general  appearance  of 
the  bark  is  said  to  be  quite  ditVerent.  This  tree  yields  the  best  product  of  all 
^utta  p-relia  trees  in  the  upper  regions  of  Padang,  and  this  gutta  jK?rcha  is  tin- 
best  of  all  the  sorts  encountered  by  explorers  (Brasse).  This  is  the  opinion  of 
both  SeligmanD  Lui,  who  found  it  on  the  eastern  watershed  of  Sumatra,  and  of 


304 


GUTTA   PERCHA 


Brau  de  St.  Pol  Lias,  who  reports  it  from  Perak  (Malacca).  It  is  also  found  in 
Borneo  (Pontianak,  Banjermassin).  The  hamlet  of  Bloran  (district  of  Djambon, 
Sumatra)  possessed  in  1884  seventy-seven  of  these  trees,  the  remainder  of  400  feet 
planted  on  the  28th  August  1856.  These  plants  were  brought  to  the  number  of 
2000  from  the  western  coast  of  Borneo  on  the  3rd  March  1856,  and  distributed 
amongst  the  different  residents.  It  is  not  known  what  has  become  of  the  others. 
A  plantation  of  trees  of  this  species  was  tried  in  Borneo.  It  did  not  succeed. 
It  is  on  the  mountains  of  no  great  height  or  on  the  smaller  hills  beyond  reach  of 
the  floods  that  the  finest  trees  are  found.  The  less  the  situation  is  exposed  to 
stagnant  water,  the  better  they  grow.  This  plant  is  so  sensible  to  the  influence  of 
a  good  situation  that  a  choice  of  bad  ground — as  in  the  Borneo  plantatations  under 
colonial  inspection,  and  entrusted  to  individuals— is  enough  to  kill  it.  The  gutta 
yielded  by  the  Dichopsis  oblongifolium,  getah  Taban  Sutra,  is  of  excellent 
homogeneity  and  durability.  Freed  from  bark  and  woody  particles,  it  becomes 


FIG.  108. — Dichopsis  Borneense  (after  Burck). 

very  tenacious  and  elastic,  and  may  be  easily  bent  without  breaking. 
Immersed  in  hot  water,  it  may  be  moulded  and  caused  to  assume  any  shape 
without  becoming  tacky,  and  on  cooling  resumes  its  ordinary  solidity.  The 
colour  varies  from  red  to  deep  brown.  As  in  all  kinds  of  gutta  percha,  the  juice 
is  a  milky  white  when  it  flows,  and  remains  so  if  it  be  preserved  without  mixture. 
The  brown  colour  is  due  to  admixture  with  cortical  and  ligneous  particles  which, 
during  heating,  communicate  their  colouring  principle  to  the  thickened  juice.  The 
Dichopsis  Borneese,  the  Dichopsis  Treubii,  the  Parvifolium,  and  the  Palaquium 
Vrieseanum  would  appear  to  be  botanical  varieties  without  influence  on  the  quality 
of  the  gutta.  The  Dichopsis  calophylla  (Benth.  et  Hook.)  would  appear  to  be 
the  Mayang  Baton  of  Seligmann  Lui,  which  yields  a  brighter  and  redder  gutta  than 
the  Dichopsis  oblongifolium,  with  not  so  fine  a  fibre,  and  perhaps  also  not  so  rigid. 
It  is  described  by  Burck  as  follows  : — 

3.  Dickop.ns    calophylla. — Folia  petiolata,   obovato-oblonga  breviter   et    obtuse 
acuminata,  nervis  lateralibus   10-12  prominentibus.       Petiolus  1-15  centim.   (sen 


DEFINITION   OF  GUTTA   PERCHA 


305 


[tbncmdra  <•<(/«/>//  //?/a  T.  et  B.  honandra  chry&onopta  et  n>*t:\i,t  <jt>  Vriese,  Njata- 

di/aii</k<ii:    in    //"/•/.     /;,//.    /!<,</,,,-.    /'//A/./////////   a/A  »/.///////////    rierre}.      Arltor   nlta 
ram  a  H  a    jii  11  ioril.iix    it  u  n  ••  tn,,,  /•'•>/  in    j»  fii,/nf,i,     eOTUIMO,      »l,<,>;i1,,  ,,',/•,  HI/H 

xiifii-it  riri.lni  x///,///.x-  <IH,  ••»<>  >•'<••  'I  '•!  ••>•>'/,,-,/  ,,  1,1  ii  *    tli-n  mi  until    Id     I  .">   »•,////'///.    A,//,/////, 

i/>  <-,/,•/•>  //tin,  nirvu  oofffciltfaj  Hi   rj  ////•///•//"  patoUit  n&tutproinMiGntibus.     /•'//,/>.< 

it  rill-tri  *    I'ltti-ii-iilitti.        /',/,/,>••,  t/t     'JO    •_'."»     iiii/HiH.     loin/i,     >//••/.-/'/,  x    /••//-//.          ('u/i/r 

•  -r,i  iiifni  iiiilntiix  lin-i  niix  <>i'ittix<>l,ttisi.<.      (  'oroUciSU^rotaf't  t  nl«>  <-<tl  i/<;  ,i  ,j  H  ,1,  ,H<I<>, 

l<triitii*     ni'it/is,      m-iifis,      /><i  tint  Unix      fu/n,     l<  >n<l  mri/nix.          St'imiii't      1  L\      //A///,,///// 


<t<-ti  mi  intt'i  .        Oi'itri  ii  in   globotttm    aureo-puhweHx.       Mi/lux   fifij'nruiix 

fongior,     N/  /)////'?  <>i>tnxiiin.     H<K-<;I    r.//-//o.xv/,  dtpretf&globoKii  calyci» 

Im-inilx  xulj'iilfit,  itiii'i  <>  tuna  iif<ix<t    L'.1,    i-intini.  /<tt<t,  '_'  ••'iifini.  lnini<i.  //,//</-  j,,  <l  H  in-,ilnlit  . 
S,  HI'  n   null-inn  xii'it/ln'mx  inn,   tutu  ,-,-n.^t,t,;,i   nifi'lii,  hitu  III<I<IH<>. 


FIG.  IW.—Dichopsis  Trcubii  (after  Burek). 

The  Dichopsis  selendit,  or  Mai/nn<i  l\<>rrik  of  Seligmann  Lui,  which  the 
native  Malays,  according  to  Burck,  call  Njatoeh  selendit,  and  the  native  of 
Sumatm  /A/A//,,/,/,  yields  a  very  hard  gutta,  unfit  for  cable  manufacture,  but 
perfectly  fit  for  being  used  in  the  industrial  mixings  to  be  dealt  with  later  on. 
The  Hnijun;/  l\l>  i-in'i'ni  and  the  ///•//"////  Knrta*  of  Seligmann  Lui  belong  to  an 

idfiitiral  variety;  the  gum  resins  which  proceed  from  them  have  the 
and  defects  of  the  Dichopsis  selendit.  The  Dic/uym'*  A'/v//// :/.///»/  «.f 

was  specially  studied  by  Beauvisage.     This  tree,  the  characters  of  whi«-h 

to  approach  the  Ison'imli-n  </nff<i  of  Hooker  and  Serrulaz,  grows  in 
Cambodia,  where  tlie  natives  call  it  '/'///"/•.  ;is  well  as  in  Cochin-China,  where  it  is 
known  under  the  name  of  r//////,  yields  an  altogether  inferior  gum  resin,  which 
can  only  be  used,  at  the  most,  in  industrial  mixtures  of  very  doubtful  value. 
This  very  striking  botanical  analogy  between  the  Dirhoj,*;*  K ,-« nt-.inna  and  the 
i/nffn,  and  the  surprising  dissimilarity  of  the  products  which  they 

20 


306 


GUTTA   PERCHA 


secrete,  are  explained  by  the  difference  in  latitude,  arid  entirely  justify  the  remarks 
at  the  beginning  of  this  chapter  on  the  narrow  and  limited  zone  to  which  the 
production  of  gutta  percha,  possessing  the  qualities  required  by  science  and 
industry,  is  confined. 

Dichopsis  pustulatum  of  Pierre.  Thi«  tree,  found  at  Perak,  succeeds  well  in 
Ceylon,  where  it  is  cultivated  as  a  gutta  percha  producer.  The  French  writers 
complain  they  have  no  information  on  this  point,  and  that  does  not  surprise  them. 
If  the  culture  at  Ceylon  has  succeeded  (the  latitude  and  the  climate,  moreover, 
permit  of  this  being  supposed),  the  English  they  say  will  make  use  of  the  fact 
as  long  as  possible  without  spreading  the  news.  As  a  practical  people,  they 
keep  the  results  of  their  experiments  and  researches  to  themselves.  Let  the 


FIG.  1IQ.— Payena  Lerii  (after  Burck). 

investigators  of  other  nations  do  the  same,  and  control  the  truth  of  the  fact 
on  the  spot.  The  genus  Payena  supplies  the  Payena  Lerii  as  almost  its  only 
guttiferous  tree.  Burck  gives  the  botanical  details  of  this  variety  of  Payena  :— 

4.  Payena  Lerii. — Folia  e  basi  acuta  ovalia  v.  oualia-oblonga  apice  subito  in 
acumen  breve  attenuata,  nervis  secundariis  in  folii  substantiam  immersis  via  con- 
spicuis.  Florum  fasciculi  axillares  ad  apices  ramulorum  conferti.  (Azaola  Lerii 
T.  et  B.  ;  Keratophorus  Lerii,  Hassk,  Geratophorus  Lerii,  Miq. ;  Tuinbouw-Jlora, 
de  Vriese  ;  Beauvisage.}  r 

Folia  e  basi  acuta  ovalia  v.  ovalia-oblonga  apice  subito  in  acumen  breve  attenuata, 
coriacea;  integerrima,  margine  subundulata,  glabra  supra  lucida  5-10  centim. 
longa,  2  '5-4  lata,  nervo  medio  supra  prominulo,  subtus  prominente,  nervis  costalibus 
fere  in  folii  substantiam  immersis  vix  conspicuis,  rectis  patentibus  ad  marginem 


DEFINITION   OF   GUTTA   PERCHA 


307 


fere  percurrentibu*  ibique  arcuatum  unit  in.     Pe&iolu*  tenuis  5-7  miUim.   /<•/< 
Florum fasciculi  ad  apices  >•»////>///»/•/////  A,<  yium  <onferti  axillares  scepius  ex  axillis 
t'nl infii in  <l,  lii  fisnfn  in   1-8  Jlori.     Calyris  lacinice,  rotundatas,  ovatce  aureo-sericcoK 
twbatqvilongcB)  conococo  3    //////////.  /<»//</'/.     (',,t;,//,i  f,  ,->•   i(n/,/<,  /<>/i</t<>/-  egfau   <t 

intus,  <il«l,f<i,  tiil,n  1'  iiiillini.  /"//«/",  I'li-nuis  S  nlilnm/n  hi n<; ',/<it is  n/,1  n<is  .",  /////////<. 
Inin/is.  Still/Hint  I  I)  .  ti/il  nt,  iifit  iliit/lifils  siinii  if  n  i/nin/ii  t//,i/>r<i,  iiiit/t>f<i  ,,i;itn 
/>itsi  rofJii/ii  fi  ni  in  ft  i  rn  itilfn''  ss<  tiffin/iinn/ii/iiso^  siij>f<t  Im'uloS  prodlicto  et  «/"'•- 
l»  ni,;tl,tf,t,  Ui>,ii-iiiiii  fniiifinn  /n/is  <l,ns<  ,>',f,r(inn  l<)  I  l'  /..»•///./ ,-.  .  Stl/fat  lo*O( 
rtus.  I-' f  art  us  carmtm  o/towtto-<>/jlon</i,  ro/mv,  iitrtfiu  wftttix  />  /•//»/•  ,-n, •,•,!/>  .",  1 
I'cntiiii.  loin/i,  sti/li  finl i  in' iit»  <i jiifiil'if  i .  kemen  untcutn  fereti-ohlongwn  18  L'"» 

lltill  I  III.  IniK/ll  III,  Illln  nUnilt/n  I, it,  /•////  ;  /, •>•/'/  f<tfi'tf>'<l    H  I  f  l<  I  <t ,    l'n  Sf  I   ;    ,///,,//,,,  ,,  COpioSUm, 

,  cor  it 'a  ii  i  '  /a'  'fi/nii,,,,  includens  ejusdem  longitudinis  ;  cotyledones  carnosa, 
'••aft i<ii,  rtnffrn/,1  feres.  The  gutta  i>ercha  from  Payena  Lerii  in  known  as 
f.w<///  Xitndek  or  Soonie  or  Soondie,  the  latter  being  the  correct  Anglo-Malay 
i-xpression  (in  Sumatra,  Banca,  Borneo,  Riouw,  and  Ambon). 

The  Payena,  though  likewise  belonging  to  the  Sapotacece,  differs  much  more 
t'r<«m  the  Isonandra.  The  small  leaves  are  differently  shaped  and  have  a  reddish 
tint  wlu-n  young.  The  flowers  are  white,  and  the  fruit,  which  is  fleshy  and 


FIG.  111. — Cake  of  Gutta  Scundek  (after  Beau  visage). 

provided  with  a  kind  of  horn,  has  a  sweet  taste  and  is  eaten  by  the  natives. 
Beauvisage  analysed  a  plant  found  by  Brau  de  St.  Pol  Lias  in  the  Malacca 
Peninsula,  and  sent  by  him  to  the  Paris  Musruin.  This  savant  concludes  from 
his  analysis  that  the  Gutta  Sandek  is  none  other  than  the  Kemtophorm*  I. 
Hasskand.  Without  any  doubt,  the  Malacca  Peninsula  must  be  regarded  as  the 
habitat  of  the  Payena  Lerii,  one  of  the  principal  gutta  percha  producers,  the  gum 
resin  of  which  is  very  widely  distributed  in  commerce.  In  regard  to  the  /sow //<//•/ 
/A  11,'Hitui't  ch  Vriese,  it  is,  according  to  Burck,  none  other  than  the  Payena  Lerii. 
De  Vriese,  after  a  rather  short  description  of  the  plant,  adds  that  the  thick  and 
coriaceous  leaves  are  covered  as  with  a  varnish,  and  that  the  plant  produces  a 
superb  red  gutta,  which  much  resembles  that  of  the  real  JV// ''"'"'•//  Mtrah.  The 
indigenous  names  of  the  Payena  Lerii  are  Ngiatoeh  balain  ///•///////».  on  the  western 
coast  of  Sumatra,  Sanda'i,  Sunta'i  in  Sonpayang,  Sundeck,  Sundeli,  >'////'//•  on  the 
eastern  coast  of  Sumatra  (Selijrm.inn  L.).  Gutta  Souni,  often  confounded  with 
the  gutta  of  the  Payena,  is  simply  a  mixture  of  several  resins  of  different  botanical 
origin.  Payena  Lerii  are  met  with  on  the  upper  plateaux  of  Padang  (Sumatra), 
and  also  in  other  localities  in  Sumatra,  in  Banca,  in  Riouw,  in  Amboyna,  and  in 
Malacca ;  they  are  rather  rare  in  Assaham  (Sumatra),  abundant  at  Siak  (id.).  The 
gutta  percha  which  it  yields  is  often  mixed  with  Bouha-balam,  which  produces  a 


308  GUTTA   PERCHA 

very  inferior  quality.  The  zone  of  culture  of  the  Payena  Lerii  stretches  from  the 
seashore  to  an  altitude  of  500  feet,  where  the  Dichopsis  oblongifolium  begins  to 
be  encountered.  The  Payena  Lerii  shares  the  low  ground  with  the  Bouha-balam 
tree;  the  Payena  prefers  dry  ground,  the  latter  marshy  localities.  The  name  of 
Bringint  which  the  Payena  sometimes  bears,  arises  from  the  resemblance  of  its 
leaf  to  that  of  the  Waringin  (Urostiym>i  ]i'-nj<uninnin\  cultivated  successfully  at 
Tijetpir. 

5.  Balata. — The  genus  Mimusops  yields  as  guttifers  the  Mimmops  Balata, 
the  Mimusops  Globosa,  and  the  Minvuwps  Schimperi  et  Kummel.  We  give, 
according  to  Dr.  Martin  (Flora  Braziliensis),  the  known  botanical  details  of  the 
Mimusops  Balata.  Mimusops  Balata  (Guertin)  seems  to  be  the  same  plant  as 
the  Mimusops  Balata  (Blume),  the  Achras  Balata  (Anblet),  the  Lucuma  mam- 
mosa  (de  Vriese),  and  the  Sapota  Mulleri  (Blume).  Glabra,  foliis  ovatis  obovatis 
ovato  vel  obovato  oblongis  obtusis  vel  rotundatis,  basi  subacutis ;  pedicellus  fasci- 
culatis  petiolum  subcequantibus  ;  lobis  calycinis  exterioribus  3  glabris  vel  minute 
fusco-puberulis,  interioribus  albido-velutinis,  corollce  lobis  sub  anthesi  reflexis, 
staminibus  sterilibus  ligulatis  subintegris,  antheris  spiculatis  ovario  G-10-gono 
locularique ;  bacca  globulosa  rotundato  Q-10-gona.  Rami  crassi  validi  nodosi, 
cum  ramulis  teretibus  crebre  lenticellosis  cortice  obducti  sordide  fusco.  Folia 
3J-8  p0n,  longa,  1^-3 J  poll,  lata  coriacea,  sujwa  ylaberrima,  fuscentia, 
subtus  rufo-fusca  ut  plurimum  glabrata,  hie  inde  lepidote-albenti-subsericea,  pilis 
minimis  in  pelliculam  contiguam  arctissime  complicatis  ;  costa  centralis  supra 
sulcata  subtus  semicylindrica,  valida  costulce  striiformes  tenerrimce,  densissimce 
vix  conspicuce.  Petiolus  pollicaris  vel  longior,  subteres.  Stipules  2  lix.  Ig. 
lanceolatce.  Florum  fasciculi  10-20-Jlori.  Pedicelli  teretes  sursum  subincrassati, 
crebre,  lenticellis  linearibus  jlavicantibus  obsiti,  glabri  vel  minute  parceque  puberuli, 
pilis  sublente  solum  conspicuis,  longitudinum  petioli  ut  plurimum  ffiquentes,  nunc 
paullo  longiores,  nunc  breviores.  Calycis  3  lin.  longi  lobi  6  ovato-lanceolati  acuti, 
sub  anthesi  refracto,  patentes  v.  subrejlexi,  intus  glaberrimi  fuscati,  pube  jxigince 
exterioris  compositce  pilis  minimis  stellatim  fasciculatis.  Corolla  calycis  longi- 
tudine  vel  paullo  brevior,  lobis  lineari-lanceolatis,  acutis,  extus  glabris,  intus 
levissime  parceque  puberulis.  Filamenta  staminum  fertilium  e  basi  subdilatata 
filiformi-subulata,  antheris  ellipticis  basi  cordatis  subcequilonga,  basi  brevissime 
connata  cum  staminibus  sterilibus  dimidio  brevioribus  ovatis,  obtusis  sub 
coriaceis.  Pubes  minuta  et  parca  in  antherarum  dorso  facieque  interiore  fila- 
mentorum  staminiumque  sterilium  et  annuli  'basalis  (per  coalitionem  illorum 
nati).  Ovarium  stylusque  glabra,  fabrica  congenerum.  Fructus  globosus,  apice 
paullulum  depressus,  rudimento  styli  apiculatus,  vallibus  levibus  tot  quot  locula 
meridianaceis  percursa,  in  sicco  foliorum  colore,  cerasi  magnitudine,  elevationibus 
minutis  scabratus  ;  pericarpio  crasso  coriaceo ;  seminibus  compluribus,  rotundato- 
triangularibus,  testa  glaberrima  lucida,  pallide-ferruginea,  area  umbilicali  parva, 
umbilico  exserto.  Albumen  semini  conforme,  carnosum  (sec.  Gcertner  albuni)  in 
sicco  rubescens.  Embryo  magnitudine  albuminis,  cotyledonibus  foliaceis,  sub 
pellucidis  nervo  centrali  pluribusque  lateralibus  tenuioribus  perensis ;  rostello 
cylindrico,  brevi,  obtuso.  Habitat  per  Guyanam  gallicum  et  anglicam  in  montibus 
Canuku,  et  ad  ripas  fluminis  Barama,  in  Barbados  et  in  aliis  insulis  antillensibus 
obvia :  Teste  Aublet  ex  insula  Mauritii  in  Guyanam  gallicam  introducta  est,  ubi 
pear-leaved  mat-tree  vel  small-leaved  mat-tree  dicitur.  In  Surinama  vocatur 
Bolletrie  v.  Bullet-tree  uti  diversce  Sapotece. 

Botanical  description  of  Balata  according  to  Obacht. —  The  only  natural 
substitute  for  gutta  percha  which  really  deserves  that  name  is  Balata.  It  is  the 
coagulated  latex  of  a  large  forest  tree,  belonging  to  the  Sapotacece,  which  is  known 
under  the  name  of  "bullet tree,"  "bully  tree,"  or  "bolletrie."  The  botanical  name 
is  Sajwta  Mulleri  Blume,  Mimusops  globosa  Gcertner,  or  Mimusops  balata  G«  rimr 
fit.  The  tree  reaches,  at  maturity,  a  height  of  120  feet,  and  usually  has  a  large 
spreading  head.  Its  cylindrical  trunk  is  60  to  70  feet  high,  and  4  to  5  feet  in 
diameter.  The  wood  is  hard,  dense,  and  has  a  reddish  tinge,  which  accounts  for 


DEFINITION   OF   GUTTA   PERCHA 


the  name   «>t'  /«/"/•</< ////'. W/    (horx-    tlr-h  ),  ^iven    \<>    it    in    tin-  Dutch  coloni.^.      Tin' 
ire  «.l,|()nur  '»val.   I   to  (5  inehe-   Ion-,  ;IIH|  •_»  to  2j  inches  broad ;  they 

ale   acuminated,    |  >et  i<  i|;it « '.    .1  IK  I     alternate.    U'illg  crowded     together    to\\anU     tllerilds 
of   till'    braiiehrs. 

According  to   Rousseau,  Venr/nela   produces  yum.   /"//<//</,  extraeted    from   the 
Sfim>UiOp8  fflobaa  («»f  (la-rtner).      Tin-  native  (iuarani  give  the  name  of  .)/; 
and   the  iWtiiijMese   tin-    iiainc  <»f    /'uri'in  or  /'///•//////.  to   the   resin.      According   to 
.Noun-  -ani|'!cs  \\liidi  lia\i-    IH-I-II    rxaniincd,  tin-re    i-    nn  iin-at   ditVerem-r  l.rtut-rii  tin- 
pnulurK    and     tlie     J///////XM//X    tjlnhnmt    es|»eeially    may     In-    confounded    \vitli    the 

. I// 'inn.* >/>*  >/>if'i.     In  n-^ard  to  the  Mimtuops  Scniinperi  <f  Kwrwnel  or  AbywinicM 

J///////x'7/s,  l.otani.-al  details  are  eompletely  a\\anting.     We  shall  have  occasion  to 
return  to  it  when  \\e  treat  on  the  clieinieal  eonijH.sition  of  giittu  pereha. 


Km.  \\'L—Mimusops  Balata  (after  Baillon). 
1.  Entire  flower  and  longitudinal  section.       |  2.  Seed  and  longitudinal  section. 

The  MiiiuixnjiecB  are  distributed  all  over  the  globe,  and  not  long  ago  Dr. 
Schweinfurth  found  the  leaves  of  J////«//x«i//x  Sckimjmri  Jfochstetter  within  tlie 
wrajij  »ings  of  Egyptian  inununies  4000  years  old.  The  bullet  trees  are  found  in 
•laniaiia,  Trinidad,  Venezuela,  British,  Dutch,  and  French  Guiana;  they  are  also 
said  -to  occur  on  the  Amazon  River.  In  the  colony  of  British  Guiana  they  are 
most  plentiful  between  the  east  bank  of  the  river  Berbice  and  the  Coreutyn. 

According  to  Jos4  Saldanha  da  Gama,  other  Brazilian  Sapotacece  should  be 
capable  of  yielding  gutta  percha  analogous  with  that  called  B«l<tt>i. 

The  names  of  these  are  as  follows  : — 

TABLE  LXXXVIII. — LIST  OF  SAPOTACEOUS  PLANTS  WHICH  SHOULD  YIKI.I. 

GUTTA  PERCHA. 


Miniii-Mips  elatii   . 

. 

Ma^araiicluba. 

I.iK-umus  ^ipuitea 

Jiupia. 

,,         fissilis 

(  iuaracua. 

,,         laseiocarpa 
,,         laurifolia 

Abiarana. 
(Juapeba  vennelha. 

„         proeera  . 

Mu'viruinlul  >a  brancha. 

Chrysophylluin  ranrillonmi 

Oaca. 

.. 

Guaraita. 

I  »ut  only  the  first  of  these  plants  would  apj>ear  to  have  been  the  object  of  any 
experiments  in  regard  to  the  quality  of  its  product,  experiments  which  wmild 
not  a  1. 1  .ear  to  have  a  Horded  very  sati>faci«.ry  results. 

G.  Bassia  Parkii. — Amongst  the  /;//xx/»/.  tlie  I'KI**;<I  I^irlcil,  described  by  Kil. 
Heckel,  Professor  of  the  Faculty  of  Science,  Marseilles  (La  Nature,  1885,  2  Sem., 
pp.  :>'-_).">,  :'.7<>.  in.')),  deeeryea  >|.e,-ial  mention.  "Amongst  all  the  Ba**ia,  large 
Indian  or  African  trees,  the  >eed>  of  which  yield  by  expression  fats,  which  find 
very  useful  application  in  industry  under  the  name  of  'Illipe^  Butter,'  there  is 
one  which,  more  interesting  than  its  congeners,  remains  ignored  up  to  now  so  far 


310 


GUTTA  PERCHA 


as  regards  one  of  its  principal  products  (gutta  percha),  the  whole  value  of  which 
has  been  misconceived  up  to  my  researches.  I  refer  to  that  one  which,  scientifically 
named  Butyrospermum  (Bassia)  Parkii,  Kotschy,  is  a  native  of  Africa,  where  it 
bears  the  common  name  of  Tree  of  Karite,  Ghee  and  the  fatty  products  of  which, 
of  buttery  consistence,  reaches  us  under  the  name  of  Galaam  Butter,  Ghi  Butter, 
or,  better,  Karite  Butter,  and  which  is  utilised  in  different  ways  in  domestic 
economy  by  all  the  equatorial  Africans.  As  the  buttery  product  of  this  precious 
tree  establishes,  at  least  nominally,  a  point  of  contact  between  the  two  kingdoms 
of  nature,  the  vegetable  and  the  animal,  I  have  thought  that  already  from  that 
point  of  view  its  history  would  be  of  real  interest.  But  here  this  interest  is 
doubled  by  what  is  adapted  for  the  special  habitat  of  the  plant.  Essentially 
African,  the  Karite  tree  belongs  exclusively  to  that  continent.  Few  researches  up 


FIG.  113.—  Bassia  Parkii  (after  Schweinfurth). 


to  now  have  been  published  on  this  subject  beyond  the  now  very  old  researches  of 
bruil  irt  and  more  recently  the  summary  but  interesting  researches  published  by 
M.  .-toucher,  naval  pharmacist.  These  two  unique  works,  notwithstanding  the 
merit  by  which  they  are  characterised,  retain  grave  errors  and  important  gaps  in 
the  history  of  this  precious  plant.  It  has  therefore  appeared  to  me  necessary  to 
again  take  up  its  study,  and  at  the  same  time  to  endeavour,  as  far  as  I  can,  to 
spread  the  plant  over  the  most  diverse  points  of  the  tropical  zone,  and,  in  particular, 
in  our  French  colonies."  Botanical  description.— The  Butyrospermum  Parkii, 
KoUchy,  is  a  beautiful  tree,  reaching  the  height  of  30  to  40  English  feet,  having 
a  trunk  of  I'oO  to  1-80  metre  (5  to  8  feet)  in  diameter,  ramified  like  an  oak,  and 
Lmg  an  abundant  milky  juice  which  easily  coagulates  (gutta  percha.).  Con- 
densed at  the  top  of  large  glabrous  and  rugose  branches,  the  leaves  are  entire, 


Di:i  INITION  OK  GUTTA   PERCHA 


311 


coriaceous,    petiolaled.  and    M  i  |  .11  hit ,  •.  I.         I'etiolfs    measuring  fi-i  .111   O'05toO'7~'    DEM 
«{labrons,    but     pllb.-sr.-nt     at     fir«tj     >tipllle.s    lanreolated,    >ub  pei-iMent,   aU.nt     (Mill1 

metre  IMII-J.  xilky  on  tin-  l.a.-|<  ;  liinl)  oblong,  lanreol.it  e,|.  mea-uri  ii'j  <  »•  1  •")  metre  to 
0"20  met iv  in  length  by  0'7«r)  to  O'lO  metre  in  width,  \\id«-ly  cuneiform  or  rounded 
at  the  base,  siibcoriarroiis  glabrous  at  maturity  mi  the  superior  -urtace,  highly 
jMilH-sccnt  uiulrnifatli,  forniahed  \\ith  t\\»-nty  in  t\\«-nt\  ii\(-  primary  smooth  open 
veins.1  |-'|i»\\vrs  in  uiiilii-U,  >|.rinurin^  t'rnin  tin-  axils  of  tin-  leaves  at  the  top  of  tin- 
l»raiifln-s  ;  pnlmn-lrs  «)•<»!  L*  nn-tre  t«»  O'dL'-")  inctrf  or  l«m^»-r.  tliirkly  roxen-il  in 

thrir  y..iui,ur  >tatr  with  a   Irrru^inmis   na|..      C.ilyx    campanulatc,  coriar is,  \\itha 

short  tiilir,  ainl  Lr'-ncrall\  t-i^ht  nlilmi^  lancfolatnl  sc^ini-nt-.  tin-  four  i-xt»-ri«»r 
covered  with  a  thick  ferruginous  i|o\\n.  ('orolla,  as  long  as  the  calyx,  with  a 
sliort  tul.c  and  oblong,  imbricated,  glabrous  si^ini-iiU  StamenH,  opposite  to  the 


KM;.  11  1.— Fruit  and  branch  of  Jinssia  Parkii  (after  Baillon). 

segments  of  the  corolla  and  iiiM  rtcd  at  their  base;  anthers  oblong,  lanceolate, 
measuring  i>  on;}  metre,  that  is  to  say,  half  the  length  of  the  glabrous  and  awl- 
shaped  filaments;  pollen  spherical,  exhibiting  four  pores.  Staminodes  wide, 
oblonii,  pointed,  dentate  (like  a  saw)  on  their  edges,  which  give  them  the  appearance 
of  fimbrication,  shorter  than  the  alternate  stamens  \\ith  the  stamina!  filaments. 
Ovary  globular,  silky,  ten-celled,  each  containing  an  anatropous  ovule ;  style 
lanky,  varying  in  length,  sometimes  inserted  on  the  exterior,  at  other  times  in: 
eluded  in  the  corolla  (heterostyled  dimorphism).  Fruit  ellii>soid  (berry),  with  a 
thin  solid  p'-rirarp  and  generally  a  simple  seed,  provided  with  very  thick  cotyledons. 
The  fruit  is  of  the  size  of  an  ordinary  nut;  it  is  furnished  with  a  savoury  sarcocarp, 
succulent  and  excellent  to  the  taste.  The  seed  is  covered  with  a  smooth  thin 

1  Some  of  the  nirasuivnunts  j^iven  in  this  sentence  by  the  authors  socni  beyond  all  possi- 
bility.    The  proper  reading  of  0'75  metre  is  apparently  0'075  metre  in  each  case. — TR. 


312  GUTTA  PERCHA 

crustaceous  episperm  of   a   maroon   colour,  which  shelters  a  very  bulky  kernel 
without  endosperm. 

Synonyms— Habitat. — This  plant  is,  moreover,  known  under  the  name  of  Bassia 
Parkii  (De  Candolle)  and  Butyrospermum  Niloticum  (Kotschy).  Genus,  Sapotacece, 
Lind.  End.  Oliver.  (Bassia  Butyracia,  Roxburgh.)  (Branch  and  fruit.)  Upper 
Guinea,  kingdom  of  Bambara,  where  it  was  discovered  by  Mungo  Park,  in  the 
Niger  country,  at  Nupe,  leba,  etc.,  Abbeokuta  (of  Irving  and  Barter)  in  the  Nile 
country,  the  White  Nile,  Gondo  Koro,  Djur,  Kosanga,  and  the  countries  of 
Niams-Niams,  Madi.  To  these  localities  or  stations  we  may  add  the  following, 
which  is  more  exact : — The  Karite  is  very  well  known  in  the  valley  of  the  Upper 
Niger  and  in  that  of  Bakoy  and  of  Baoule  and  their  affluents ;  real  forests  of  it 
are  found  in  the  Beledonga,  the  Fouladougon,  the  Handing,  the  Guenickalaris, 
etc.  (Exploration  of  the  Upper  Niger  by  Commandant  Gallieni).  According  to 
Baucher  (Archives  de  Medecine  Navale,  t.  xl.,  November  1883),  it  grows 
spontaneously  in  the  argilo-silicious,  ferruginous,  gravelly,  and  fissured  soils 
which  are  met  with  in  the  plains  of  Upper  Senegal  when  the  Niger  route  is 
taken.  In  a  general  way,  it  may  be  said  to  exist  throughout 
the  whole  of  the  valley  of  the  Upper  Niger,  i.e.  in  all  the 
country  situated  to  the  east  of  the  old  French  Senegalese 
possessions  before  their  penetration  into  the  Soudan.  It  is 
especially  well  known  amongst  the  Bambaras,  particularly  in 
Beledonga.  It  is  already  reported  in  Borne  and  to  the  east 
of  Fouta-Djallon,  where  it  is  better  known  under  the  name 
of  Kare.  It  is  very  well  known  in  Segon  and  Timbuctoo. 
In  the  Nile  region,  Schweinfurth  mentions  it  amongst  the 
Bongos,  the  Mittous,  and  the  Niams-Niams.  We  are  going 
to  show  that  the  Bassia  may  be  classed  in  the  first  rank 
alongside  the  Isonandra,  the  product  of  which  it  imitates 
so  much  as  to  be  mistaken  for  it. 

Microscopical  examination  of  a  section  of  a  young  branch 
of  Bassia. — If  we  examine  the  section  of  a  young  branch  of 

FIG.  115. Bassia  Par-   tn*s  tree,  we  observe  that  the  laticiferous  vessels  c.L,  arranged 

kii,  cross  section  of  in  packed  circular   rows,  are  situated  in  the  centre  of   the 
a  young  branch.          cortical  parenchyma  p.c.,  itself  placed  under  a  tuberose  not 
s.,  suber;  p.c.,  cortical  very  thick  layer  s.     It  is  therefore  easy  to  reach   them   at 
parenchyma  ;     c.l.,   Once  by  means  of  any  cutting  instrument.      It  is  the  same 
jaticiferous  ^  canals ;  witll  tlie  y0ung  stem  ;   but  when  arrived  at  maturity,  both 
p.i.\  liberian  paren-   *n  tne  caulinary  system  and  in  that  of  the  young  branches, 
chyma ;  b.,  wood.       there     is    produced    in    this   same     paren chymatous    tissue 
numerous  secondary  ligneous  formations,  very  near  to  each 
other,  arranged  in  circles,  and  composed  of  an  abundant,  very  resistant  wood  b, 
and  of  a  very  reduced  liber  /.     The  growths,  on  account  of  their  rapid  develop- 
ment, almost  touch  each  other,  and  thus  form  a  protective  barrier,  behind  which 
are  hidden  the  vessels  of  the  latex,  driven  into  a  corner  against  the  wood.     It 
then  becomes  difficult,  if  not  impossible,  to  reach  the  laticiferous  vessels :  thus, 
it  is  only  possible  by  a  deep  cut  from  a  powerful  instrument  to  make  an  incision 
capable  of  giving  vent  to  an  abundant  flow  of  milk,  in  the  case  of  adult  stems  or 
branches.     This  abnormal  constitution  is  present,  without  doubt,  in  all  the  Bassia, 
the  result  of  which  is  to   render   the  whole  of  them  equally  refractory  to  the 
necessary  cortical  incision.     All  the  difficulty  consists  in  the  necessity  of  breaking 
or,  better  still,   of  removing  this  barrier.     This  resistance,   once  conquered,  the 
operation  gives  birth  to    a   thick  white   milk  which  very  easily  solidifies,  and, 
coagulated   by   the   same   process   as   gutta   percha,    gives  eventually  a  product 
comparable    with    that    of   the    Isonandra.      The    Madar   gutta   of  India. — The 
inspissated  and  sun-dried  sap  (milk)  from  the   stem  of  the  Callotropis  procera 
constitutes  the  Madar  gutta  of  India.     Hooper  (Kept.  Labor.  Ind.  Mus.  (Indus. 
Sec.  1905-06))  describes  it  as  a  pseudo-gutta,  with  the  composition  : — Resin,  52 '9  ; 


DEFINITION   OF  GUTTA   PKRCHA 


313 


in>olub|,-,  .".7'1.':  a-h.  '.''I'  100.  It  contain-  albane  an. I  Hiiaxile  n->in«i  in  large 
amounts.  Tin-  tree  is  n. .t  .mis  the  on,-  iii.iM  fivqm-ntly  inrt  \\ith  in  tin-  vast 
tracts  of  saii.lv  dfiMftfl  of  Central  India  ami  Uajpntana  ami  Sin.l,  hut  itifl 
almost  tin-  oid\  form  of  plant  lit'.-  encountered.  It  seems  to  act  as  tin-  pi..ne.-r 
plant  in  tin-  r«vlamat  imi  ..('  l.anvn  land.  An  outlet  for  it>  products  is  thu- 
greatly  In  In-  de>iivd.  Cult  i\  at  i»n  and  -election  might  lead  it  to  be  tin-  it-cognised 
tree  for  poor  soils.  Hut  unless  tin-  shoots  cut  for  libre  could  I..-  tapped  for  milk,  it 
is  improbable  that  tapping  for  gutta  alone  would  pay,  as  stem  and  t  \\  igs  are  too 
small.  I'.—  ide-.  tin-  ivsin  ha-  tin-  disadvantage  of  conducting  electricity  lairl\ 
\\ell,  \\hich  debars  it  from  liring  marketed  for  insulation  jmrpo>i->.  The  milk 
changes  \cm-tal»le  lilues  to  givm  instead  of  reddeninur  them. 

/luf.i/n'fi/  niinnii'iry.  —  Here  terminates  tlie  enuineration  of  the  different 
varieties  <»f  >',//.../»/.-,  /  known  a.s  capable  of  yielding  commercial  gutta  percha. 
I'.ut  the  question  has  not  yet  l-een  suHieiently  studied  so  as  to  close  definitely  tin- 
list  of  the  S<i/>"t<"-«i  eapaMe  of  producing  gutta  i>ercha  or  a  similar  substunee. 
Not  only  have  the  known  species  not  been  sufficiently  studied,  but  we  do  not 
know  some  Borneo  species  which  are  included  in  the  herbaria  of  Buitenzorg  or 
Saigon,  but  whieh  have  never  yet  been  met  with  living,  at  least  by  Europeans. 
Again,  no  species  from  the  eastern  watershed  of  the  Malay  Peninsula,  and 
especially  from  the  State  of  Pahang,  has  yet  been  examined  in  a  complete  manner. 
It  is  the  same  with  the  species  of  equatorial  Africa  and  of  India.  It  will  require 
a  number  of  years  yet  before  we  can  lay  down  some  reliable  data  on  the  plants  of 
these  regions  capable  of  yielding  commercial  gutta  percha.  For  reference  purposes 
the  few  plants  belonging  to  other  orders  than  the  Sapotacew,  and,  rightly  or 
wrongly,  reputed  as  guttiferous,  are  enumerated  below,  but  they  are  merely 
indianil.lier  hearing  plants,  yielding  a  less  sensitive  and  a  less  elastic  rubber,  and 
not  guttiferous  plants  : — 


Asdejtiadat  — 

Cynanchum  viniinalc 
Callotropis  gigantea 
Asclepias  acida  . 


Himlostan. 


Alstouia  scolaria 


k't(/>h<>rbiacecc — 
Euphorbia  trigona 
,,  nerei  folia. 

,,  tortillis 

,,  tirucalli 

Macaranga  tomentosa 
Pedilanthus  tithymaloides 


Himlostan  and  the  Cape. 


To  conclude,  we  give  in  Table  LXXXIX.  the  nomenclature  of  the  principal 
varieties  of  the  guttiferous  species  or  reputed  as  such,  whilst  admitting  with  M. 
Serrula/.  that  this  long  list  is  due  probably  to  the  fact  that  the  shape  and  dimensions 
of  the  leaf  vary  enormously  with  the  age  of  the  plant  and  with  the  parts  thereof, 
and  that  a  great  number  of  the  species  introduced  into  botany  from  branches 
deprived  of  floral  elements  and  not  comparable  amongst  each  other  will  disappear 
in  proportion  as  observations  have  been  more  often  controlled  on  the  spot  on  a 
fully  developed  plant. 


314 


GUTTA   PERCHA 

TABLE  LXXXIX.—  SYNOPTICAL  TABLE  OF 


Family. 

Tribe. 

Variety. 

Scientific  Synonym. 

Local  Synonym. 

SAPOTACE<B. 

Palaquium  or  Di- 
chopsis. 

Palaquium  gutta. 

Isonandra  gutta. 
Dichopsis  gutta. 

Gueutha-Tuban-Merah  . 

id. 

id. 

Palaquium      oblongi- 
folium. 

Dichopsis      oblongi- 
folium. 

Mayang  Doerrian. 
Njatoeh  -  Balam  -  Tem- 

baga. 

N  jatoeh-Balam  -Sirah  . 

,,           ,,      Soeson 

(in  Sumatra). 

Njatoeh  -  Balam  -  Doer- 

rian. 

Ka  -  Malan  -  Paddi  (in 

Borneo). 

Gueutta-Taban  -  Merah 

(western  coast  of  the 

ill. 

id. 

Palaquium  borneense. 

Dichopsis  borneense. 

Malay  Peninsula). 

id. 

id. 

Palaquium        Treubii 

Dichopsis        Treubii 

Dadauw. 

and    variety    parvi- 
folium. 

and  variety  parvi- 
folium. 

id. 

id. 

Palaquium        Vriese-   Dichopsis        Vriese- 

Njatoeh-Bindaloc. 

anum.                          ;     anum. 

id. 

id. 

Dichopsis  callophylla. 

Isonandra       chryso- 
nata 
Isonandra       chrvso- 

Mayang  Batou. 
Njatoeh-Djankar. 

philla. 

Isonandra  costata. 

Isonandra     oblongi- 
folia. 

id. 

id. 

Palaquium  Selendit. 

Halaban. 

- 

Njatoeh-Selendit. 

Mayang-Korsik. 

,,        Sikkum. 

,,        Djerinjin. 

id. 

id. 

Palaquium  Njatoeh. 

,,        Kartas. 
Njatoeh. 

id. 

id. 

Palaquium  Pistula- 

tum. 

id. 

id. 

Dichopsis  elliptica. 

'auchontee. 

id. 

id. 

Palaquium        Kranzi- 

^hior  in  Cambodia. 

ana. 

Chay  in  Cochin-China. 

id. 

Payena. 

Payena  Lerii. 

Keratophorus. 

'jatoeh-Balam-Baringin. 

Isonandra         Benja- 

tf  jatoch-Balam  -  Warin- 

mina. 

gin. 

Azaola  Lerii. 

Njatoeh-Balam-Sundeck 

„      Soendai. 

,           ,,      Sandai. 

,           „      Soentai. 

,            ,,      Pipis. 
3alam  Tandjong. 

,       Tjabee. 

,        Tandock. 

,        Troeng. 

f 

,,      Soute. 

All     these     denomina- 

tions   belong    to    Su- 

matra.) 
ioelan  (in  Banka). 

Vjatoeh    Ka-Malam  (in 

Borneo),  Ranas. 

Balam  Soentai  (Riouw). 
Gutta-Selendit     (Malay 

Peninsula). 

DEFINITION   OK   GUTTA   PERCHA 

Till.  PRINCIPAL  OUTTIFEROUS  PLANTS. 


315 


IS..tanists  and  Kxplo.er-. 


Th.  Lobb. 
Dr.  <>\|,.\. 
Hooker. 

I'.enthani. 

Bonk. 
Brook* 

Selii;maiin  Lui. 
Haillon. 
Serrula/. 
I '.can  visage. 


Selimnann  I.ui  and  \  .  -|ii.  . 

r.i  -an  visage. 

lirau  ih-  St.  Pol  Lias. 

Te\Miiann. 

P.u'rck. 


Teysmann. 

I'.un-k. 

Burck. 


Benth.  and  Hooker. 

Pierre. 

l>e  \'riese. 

Teysmann. 

Beugmann  Lui  and  Vesque. 


Seligmann  Lui  and  Vi-sque. 
Burck. 


Tcysmann. 
Pierre. 


Pierre. 


l!enth.  and  Hooker. 


Do  Vriese. 

Seli-mann  Lui  and  V 

Beauvisage. 

Burck. 

Teysmann. 

Tromn. 

Hasskari. 

Bran  de  St.  Pol  Lias. 


Malasla-Singapore    (> m- 

tains  of  that  is|.,atChas. 

.'...    ravine    "t 
P.ouquetl-Timah). 

Cultivated  at  Ti  jetpir,  Java. 


In  all  parts  of  Sumatra, 
especially  at  Loche- Along 
(eastern  coast),  Lampon^. 

South-west  of  Borneo (Pon- 
tinak). 

South  of  Borneo  (P.anjer- 
inassin). 

Rhio  Archipelago. 

Malacca. 

Perak. 

Cultivated  at  Tijetpir.. lax  a. 


Borneo. 

Cultivated  at  Ti  jetpir,  Java. 

Isle  of  Banka. 

Tijetpir  plantations  of  this 

variety     demolished     as 

gutta  was  inferior. 
Sumatra  (Mount  Sagoh). 


Borneo. 


Remark*. 


Sumatra. 
Malay  Peninsula. 


Java    (province  of   Banje- 
rang> 

Perak,  Ceylon. 


It  la  this  species  whirl. ,  rightly  or  wrongly,  would 
appear  to  yield  the  best  specimens  of  gutU 

|H  -rclia. 

llou,  \. T  that  may  be,  it  would  not  appear  to 

exist    nowa-i.  in   \ery   rare   CMC*. 

ami  would  app> -:n-  to  IK-  completely  neglected 
for  tin-  follow  in-..'  I] 

"  \Vhili-  I'lit'i'/in'i'iii  t.l.ii.ii.n  I"',  an i(P,urck)iH  but  u 
\arid  \  of  r.iiuttii,  still   h\  ci-rtain  \M 
held  to  t>e  a'di^tiint  roecm.  and  U>yi«-ld  Hi. 
Taban  Sutra  of  Perak  "  (Wat t ). 

It  is    umjuestionably  the  guttiferouK  tn«    /"/ 

MM  'I,-, H-,-  ;is  regards  ipialit  \ . 
lialam-tembaga  is,  in  Malay,  yellow  copper  leaf. 
The   plant,  shrinking  from  drought,  IH  satisfied 

with  mediocre  exposure. 
Deposit  of  calcium  oxalate  in  tin-  leaves. 
Abundant  colourless  transparent  latex. 
Alkalies  do  not  colour  it. 
The  Taiian  Merah,  according  to  Burn  Murd«>.-|i. 

i>    /'.   •,!,(„, ,,ili,,liiiin;  Tahan  Chaier  :- 

Taban  Puteh  is  /'.  pistulahun  ;  and  Taban  Back 

is  P.  *p. 


These  three  species  are  only  varieties  of  P. 
obloiigifolhnn. 

The  quality  of  the  gutta  percha  is  the  same. 

But  the  Netherlands  authorities  in  Java  have 
demolished  their  /'.  Treiihii  plantations  as  in- 
ferior and  to  prevent  hybridisation. 


Yields  a  brighter  and  redder  gutta  than  /'. 
oblongifolium.  Its  fibre  is  not  so  fine  and 
perhaps  not  so  rigid. 

The  Mayang  Batou,  according  to  Vesque,  aj>- 
proaches  the  Palaquium  of  Pierre,  but  i»  not 
identical.  It  would  appear  to  IK-  better  adapted 
to  stand  drought  and  to  support  more  intense 
light  than  the  P.  oblon<jifoli\t,n. 

Very  hard  gutta,  unfit  for  cable  manufacture. 
A  plant  relatively  well  adapted   to  stain!  short 

droughts. 
Very  mediocre  light  (exposure  to  sun). 


Cultivated  rationally   and  smvessfullx    by   the 
British. 

Horny  resin,  brittle  in  the  cold. 


Wvnaad,    Coorg,    Travan- 
core  (British  India). 

French    Protectorate      of  I  Only  yields  a  defective  product,  probably  owing 
Indo-China.  to  climatic  conditions. 


Sumatra  (Padang,  Assahan, 

and  Siak). 
1'anka. 
Borneo. 

Rhio  Archipelago. 
Amboin. 
Malaooa. 
Tawi-Tawi. 


Owes  its  name  of  Baringin  or  Waringin  to  the 
resemblance  .if  it-  leaves  to  those  of  the 
ri;,*t;>iiiin  II,  mniHfn— in  Malay,  Baringin  or 
Warinuin. 

This  is  the  gutta  percha  which  enters  into  the 
majority  of  the  commercial  mixtures  which 
come  to  our  markets  under  the  name  of  raw 
gutta  percha. 

The  uutta  perdia  wants  homogeneity. 

The  tree  an  i\  c  -  .it  maturity  sooner  than  the 
/'.  olifnniiifoliinn. 

Cultivated  by  the  I'.ritMi  at  I'ard.  ni.i  .md  !!•  in 
eratgoda. 

All  the  tissues  of  the  plant   contain  a  substance 
which    blackens    with    alkalies     in    absorbing 
oxygen,  possibly  due  to  Kurz  transferring  Kfra- 
topSonu   Lrrii'  to   Pat/ma,   hut  his  Burmese 
species  is  different  from  above.     / '    / 
evergreen  tree  of  Assam,  Tenasserim,  and  the 
Straits,  yields  gutta    percha.      /'.     '/ 
(Clarke)  of  Penang  and  Malacca  abounds    in 
gutta  percha  (Clarke). 


316 


GUTTA   PERCHA 

TABLE  LXXXIX.— SYNOPTICAL  TABLE  OF  THE 


1 
Family.                      Tribe. 

Variety. 

Scientific  Synonym. 

Local  Synonym. 

SAPOTACE^E.              Payena. 

Payena  macrophj'lla. 

Kacosmanthus  mac- 
rophyllus. 

Goetah  Moendirig. 

id. 

Bassia. 

Bassia  Parkii. 

Bassia   Butyrosper- 
mum 
,,       Niloticum. 
,  ,       Butyracea. 

Tree  of  Charity. 
Ghi  tree. 
Saga. 

id. 

Mimusops. 

Mimusops  Balata. 

Mimusops  Balata. 
Achras  Balata. 
Lucuma  mamosa. 
Sapola  Mullerii. 
Higucrona. 
Mastota. 

Small-leaved    or    pear- 
leaved  mat  tree. 
Bullet    tree    or    Bolle- 
trie. 
Manyl-Kara. 
Fresh  or  bleeding  Balata. 
Red  Balata. 
Galibis  Balata. 
Muirapiringa. 

id. 

Mimusops. 

Mimusops  globosa. 

Purvio. 
Purgua. 
Mbea-r-ata  (hard  thing) 
in  Guarani. 

id. 

Mimusops. 

Mimusops  elata. 

•• 

Ma§aranduba. 
Apraiu. 

id. 

Mimusops.                 Species. 

Maparauba. 

id. 

Mimusops. 

Species. 

Lucuma  gigantea. 
fissilis. 
,,       lastiocarpa. 
,,       laurifolia. 
,,       procera. 

Jaqua. 
Garaqua. 
Abiarana. 
Guapeba  vermelha. 
Ghana  or  White  Mao.ar- 
anduba. 

id. 

Mimusops. 

Mimusops  sp. 
,,        speciosa. 
,,        Schimperi. 
,,        Kummel. 

Abyssinian  Mimu- 
sops. 

Cafequesu. 

id. 

Chrysophyllum. 

Chrysophyllum  rami- 
florum. 
Chrysophyllum 
species. 

Baca,  Guarita. 
Leitero  de  Mato. 

id. 

Achras  Australis. 
Sano  Manilla. 
Imbricaria  coriacea. 

ASCLEPIADK«. 

Cynanchum. 
Callotropis. 
Asclepias. 

Cynanchum  viminale 
Callotropis  gigantea. 
Asclepias  acida. 

Madar  or  Akanda  Chat- 
wan. 

APOCYNE.E. 

Alstonia. 

Alstonia  scolaris. 

Kath  Mandu. 

EUPHORBIACE^G. 

Euphorbia. 
Macaranga. 
Pedilanthus. 

Euphorbia  trigona. 
„          nereifolia. 
,,          royleana. 
„           tortilis. 
,,          tirucalli. 
Macaranga    tormen- 
tosa. 
Pedilanthus     tisthy- 
maloides. 

Species  which  may 
be  classed  amongst 
the  rubber  guttas  ; 
otherwise        little 
studied. 

Milk  hedge  or  bush. 

DEFINITION   OF  GUTTA   PERCHA 
PRINCIPAL  GUTTIFEROUS  PLANTS-«m/// 


317 


I  lot. mists  and  Kxplnren. 


Te\  -IIKlllll. 

Hlquel. 

Imrck. 


D»OuidoOe. 
Roxburgh. 
Kotachy. 
Quibourt 

llaiicher. 

He.-kel  .v  Srhla-denhaufcn. 

Miingo  1'ark. 

Qallleni. 

Si'hueinfurth. 

Aublet. 

GuTtner. 

l»r.  Martin. 

Illume. 

De  Vriese. 

Schomhurgk. 

Santa  Anna  de  NCr\. 

Biollcy. 


it«  (known). 


Ocertner. 

K. »u--'  au. 


Bernardin    da    Silva    Con- 
tinho. 


nt. mil. 


.  .HUM. 

:  I'xiinttara. 

White  Nile, 

count  r\  <>f  tin-  Niams- 
Niams.  Uakoc  \allc\, 
l::i..nl.-.  tin-  i:H:ii|..ii^.i. 
the  r'eladongo.  tin-  Man 
diarg.  the  GuenickalariH, 
in  the  Bougos. 


Krriirh,   ISritish.aml  l>iit.-li 

t.uinea. 

M.«imt  Ciumkut. 
Rivers  of  Baraina. 
Surinam. 
r..irl>a<loes. 
\\fst  Inilics. 
Hraxil  (Amazonia). 
Costa  Ki.-a. 


Remark*. 


nfi  ii»r  ,|u.iin  \  i«i  th»-  preceding. 


Venezuela    (province     of 
Maturia). 


Brazil. 

Venezuela  (Inirido  and  Gua- 
vaire). 

Brazil. 
Brazil. 


Angola. 
Gaboon. 
Abyssinia. 


Brazil. 
Niger. 


Queensland. 
New  South  Wales. 


Maurice  Island. 
British  India. 

id. 

India  and  the  Cape. 


According  to   I!.,  k.  I,    th.-    ISu»»ia   would   1«-   an 

Atri.-au  u'Uttifi-roiis  plant  .-apal,!.-  ,.f  .-..liiiK-tinu 
with  the  I'alaquium  of  1  1.  hipeUgo. 


Borneo);  latrx  an  iiift-rior-utta.  Tlir<  .•  >.:iinpl.  -• 
olB.latijnlin  |:itc\  from  lli)-haii-.i)i,ul 
48'9  gutta,  38-8  resin,  anrl  rj-,'5  ash.  ll  \\a«. 
light  gri'.s  plastic.  hut  \  i»-ld  P<T  tn-t  *m;ill.  l^klt-v 
'"iKilfiilin  from  Tinni-M-lh  gave  22*6 
gutta,  «WT  n-siii,  and  1  -J-7a-.il. 

Intermediate  lietween  rubber  ami  uutta  p-  -r>  -ha. 
Although  its  d<-n>it\  is  near  fimugh  to  gutta 
percha,  it  is  not  din-tile  i  -nou^h  to  h»-  u«--d  fur 
covering  ssirc.  and  can  «.nl\  !»«•  ustfl  f,,r  this 
purpose  when  mixed  with  vcr\  ^IMK!  gutta 
percha.  Softer  at  the  ordinary  tcni] 
it  does  not  harden  so  much  on  cooling  as 
ordinary  gutta  percha,  from  which  it  differs 
essentially  hy  the  manner  in  which  it  behave* 
in  tin-  air.  Whilst  gutta  pt-n-ha,  expoaed  to 
the  air  and  light,  is  rapidly  transformed  into  a 
hard,  brittle,  and  resinous  substance,  a  trans- 
formation which  eventually  jtenelrates  the 
whole  mass,  tuilata,  on  the  contrary,  remains 
for  a  very  long  time  without  any  perceptil.U- 
change. 

Same  properties  as  the  preceding  ;  may  be  con- 
fused with  it. 


May  be  classed  amongst  the  series  of  rubber 

guttas. 
Harder  than  Minmsops  Balato. 

As  above. 


All  these  scarce  and  little  known  species  require 
to  be  better  studied  before  it  would  be  possible 
to  classify  them  in  any  satisfactory  manner. 

Species  examined  more  esjHTially  by  Ileckel  and 
Schlairdeiihaufen.  In  addition  to  thes,-  there 
are  the  Indian  >pceics  M.  Kutiki.  M.  Kl-n-ii. 
M.  ll'-jritniirn,  M.  Roxbiir<jhian(i  —  \\\  i 
which  no  effort  has  been  made  to  see  whether 
latex  might  not  be  of  similar  value  to  Balata. 


318 


GUTTA   PERCHA 


TABLE  XC. — ANALYSIS  OF  GUTTA  PERCHAS  OF  KNOWN  BOTANICAL 

ORIGIN  (WRAY'S  PERAK  SAMPLES). 
Received  at  Kew,  1883-84;  analysed  1885  (OBACH). 


Percentage  Composition. 

Totals. 

Ratio. 

Percentage 
Composition. 

No. 

Gutta. 

Resin. 

Dirt. 

Water. 

G.  P. 

(G.+R.). 

Waste 
(D.+W.). 

G.  P. 

Waste. 

Gutta 
Resin. 

Gutta. 

Resin. 

(1) 

84-3 

107 

37 

1-3 

95-0 

5-0 

19-0 

7'9 

88-8 

11-2 

(2) 

77-1 

16'9 

4-6 

1-4 

94-0 

6-0 

157 

4-6 

82-0 

18-0 

(3) 

47-0 

48-4 

3-6 

1-0 

95-4 

4-6 

207 

1-0 

49-3 

507 

(4) 

45'3 

49-6 

3-4 

1-7 

94-9 

5-1 

18'6 

0-9 

47-8 

52-2 

(5) 

23-1 

71-5 

4'2 

1-2 

94'6 

5'4 

17-5 

0-3 

24-4 

75-6 

(6) 

43-9 

37-6 

5-1 

13-4 

81-5 

18-5 

4-4 

1-2 

53-9 

46-1 

(7) 

31-6 

65-2 

1-8 

1-4 

96-8 

3-2 

30-2 

0-5 

32-6 

67-4 

(1)  Dichopsis  oblongifolia   (Burck)   (getah    taban   sutra)   (silky),    nearly  white,    clean,    New 

Kennering,  Upper  Perak,  1884,  yielded  light  brown  elastic  prime  gutta,  and  yellow  very 
soft  resin. 

(2)  D.  Gutta  (Benth.  et  Hook.)  (g.  t.  merah)  (red),  very  light  pinkish,  clean,  River  Plus, 

Upper  Perak,  1883,  yielded  light  pinkish  elastic  prime  gutta,  and  brownish  yellow  very 
hard  resin. 

(3)  D.  Polyanthe  (Benth.)  (g.  t.  puteh)  (white),  clean,  Waterfall  Hill,  2500  feet,  Larut,  1883, 

yielded  light  brown  elastic  gutta,  and  light  broAvn  brittle  resin,  a  moderate  sized  tree  of 
Cachar,  Chittagong,  Arakan,  and  Pegu. 

(4)  D.  Pustulata  (Hemsely)  (g.  t.  chaier)  (liquid),  white,  dense,  clean,  Waterfall  Hill,  600  feet, 

Larut,  1884,  yielded  light  brown  elastic  gutta,  and  light  brown  very  brittle  resin. 

(5)  D.  Maingayi  (Clarke)  (g.  t.  simpor),  nearly  white,  clean,  crumbly,  Changkat  Serdang, 

Larut,  1884,— a  better  sample,  also  from  Wray,  received  1886,  analysed  1896,  gave  93 '5 
G.  P.  (1  part  gutta,  2  resin), — yielded  light  pinkish  brown  elastic  gutta,  and  very  light 
hard  resin.  A  tree  of  Penang  and  Malacca  abounds  in  gutta  percha  Maingay. 

(6)  Payena  Lerii  (Burck)  (g.  sundek),  nearly  white,  dense,  clean,  Tapstang,  near  coast,  Larut, 

1884,  yielded  light  pinkish  elastic  gutta,  and  pale  yellow  nearly  liquid  resin. 

(7)  Bassia  Motleyana  (Clarke)  (g.  gahru),  the  Kotian,  a  tree  of  Malacca  and  Borneo,  nearly 

white,  clean,  crumbly,  Waterfall  Hill,  2000  feet,  Larut,  1384,  yielded  white  very  brittle 
gutta  and  light  hard  resin. 


CHAl'TKU    II 
CLIM  A T( )  LOGY— SOIL— RATIONAL  CULTURE 

Ir  it  has  liccn  possible  to  i^ivr  \\itli  certainty  some  informal  ion  on  tlic  cliinato|n<_<\ 
\\hii-h  rules  the  growth  of  indiarubber-bearin^  plants,  it  is  not  so  in  tin-  etteci 
gUttiferoUfl  plants.  llo\v  could  it  lie  <»t hens isc-,  since  at  tin-  present  day  no  one  is 
agreed  as  to  the  plant  producing  the  best  commercial  i^utta  percha,  any  more  than 
on  the  producing  countries  1  Seligmann  Lui  is  the  only  one  who,  in  his  examina- 
tion of  the  guttifers  of  Sumatra,  has  attempted  an  essay  on  the  climatology  of  the 
gutta  percha  mayangs  (trees).  The  opinions  expressed  by  this  French  telegraphic 
engineer  are  entitled  to  respect.  This  part  of  his  work  is  therefore  given  in  full. 
"The  Straits  Archipelago,  of  eruptive  origin,  with  several  volcanoes  still  in  full 
activity,  exhibit,  owing  to  this  activity,  two  very  distinct  kinds  of  soil.  In  tin- 
centre  is  a  mountainous,  sometimes  very  elevated,  region.  The  rivers,  in  t lu- 
mmy season,  receive  an  enormous  mass  of  water.  They  descend  \\ith  iinjtetuosity, 
and  cut  up  the  banks  of  the  higher  valleys  into  deep  ravines,  thus  l.eo.ming 
charged  with  a  considerable  quantity  of  mud,  which  they  deposit  farther  on,  when 
the  current  has  spent  itself  to  a  great  extent.  There  are  thus  formed,  at  the  foot 
of  the  mountains,  belts  of  flat  ground,  which  extend  daily,  and  which,  below  sea- 
level,  are  prolonged  by  banks  to  a  great  distance  from  the  coast.  Of  these  alluvial 
deposits,  the  most  recent  are  still  half  under  water ;  their  shape  and  arrangement 
are  altered  daily,  and  this  inextricable  labyrinth  of  muddy  moving  islets  disappears 
under  the  foliage  of  the  mangroves  and  the  water  palms.  Beyond,  older  deposits, 
already  dried  up  by  the  sun,  form  a  firm  but  absolutely  flat  soil,  of  no  great  height, 
and  often  flooded  by  the  rise  of  the  rivers.  In  these  very  fertile  parts  are  the 
establishments  of  the  Malay  population,  who  have  established  some  clearances.  It 
is  there  also  that  the  Europeans  have  started  some  plantations,  and  grown  tobacco 
at  Delli  and  at  Langkat,  cinnamon  and  tapioca  at  Benkalis,  cane-sugar,  coffee,  and 
pepper  at  Palembang  and  on  the  western  coast.  Higher  up — in  fact  as  soon  as  the 
tirst  movements  of  the  soil  embank  the  rivers  in  the  deeper  valleys,  and  prevent 
overflowing,  as  soon  as,  consequently,  the  rocky  soil  commences  to  emerge  from  the 
thick  layers  of  transported  soil — we  enter  into  the  regions  of  the  large  forests.  It 
is  there,  on  banks  of  sandstone,  covered  with  scanty  humus,  that  we  come  across 
the  nt'tf/'iH'i*  (the  gutta  percha  trees).  Numerous  streams,  which  do  not  dry  up 
during  the  dry  season,  and  frequent  rains,  spread  over  the  whole  of  the  year, 
preserve  the  freshness  and  humidity  of  the  soil.  The  altitude  is  still  too  low  for 
the  temperature  to  be  j>erceptibly  lowered,  and,  on  the  coast,  the  average,  during 
the  coolest  months  of  the  year,  does  not  go  below  25°  C.  (77°  F.).  I  will  not 
venture  to  affirm  that  these  an-  the  only  conditions  of  soil  and  climate  adapted  to 
the  innii<in<i*  (/'n/ti'/nnmi  >in</  /'"//<  H<I).  All  I  can  say  is,  that  such  is  the  case 
there,  where  I  have  seen  these  trees,  and  it  was  likewise  there  that  Murton 
encountered  them  before  me."  The  considerations  formerly  elaborated  on  the 
subject  of  the  geographical  distribution  of  niayangs  have  left  no  illusions  in  the 
minds  of  the  true  explorers  of  the  guttiferous  countries.  They  have  not  been  able 
to  find  those  plants  in  the  wild  state  beyond  the  guttiferous  zone.  All  regard  the 
researches  of  Pierre,  in  Cochin-China,  as  in  this  respect  futile.  The  T/iior  is 
merely  a  bad  quality  rubber,  and  can  in  no  way  be  regarded  as  even  an  inferior 

SJ19 


320  GUTTA   PERCHA 

gutta  percha.  The  plants  to  which  the  same  writer  drew  attention  in  no  way 
respond  to  the  Sumatra  species.  Seligmann  Lui  ascertained,  at  Bangkok,  that  an 
Englishman,  in  the  service  of  Siam,  had  brought  gutta  percha  back  with  him  after 
a  journey  to  the  environs  of  Pre-Tcha-Bouri,  situated  in  the  centre  of  the  Gulf  of 
Siam,  on  the  western  coast,  towards  the  13°  of  N.  latitude.  That  engineer  found 
that  the  substance  in  question  was  none  other  than  Borneo  rubber,  which  is  likewise 
found  in  Burmah,  on  the  Pegu  coast.  The  second  king,  who  is  especially 
interested  in  these  matters,  affirms,  moreover,  that  gutta  percha  exists  at  Trigano, 
but  not  higher. 

Acclimatisation. — There  is  nothing  astonishing  in  the  fact  that  the  difficulties 
of  acclimatising  the  mayangs  are  almost  insurmountable  beyond  the  guttiferous 
zone,  and,  in  localities  under  the  sphere  of  French  influence,  there  are  local  obstacles 
such  as  the  torment  of  the  wind  in  the  mountains  of  Kamchay,  then  general 
obstacles  such  as  the  nature  of  the  country.  Seligmann  Lui  well  remarked  that 
the  natural  zone  of  habitat  is  limited  to  about  the  5°  of  N.  latitude,  and  the 
French  possessions  are  situated  beyond  the  tenth  parallel.  There  is  also  the 
difference  in  climate  between  French  establishments  and  the  isles  of  the  Straits 
Settlements.  In  Java  and  Sumatra,  near  the  coast,  the  average  winter  temperature 
does  not  fall  below  25°  C.  (77°  F.),  whilst  at  Saigon  it  falls  to  22°  C.  (71 '6°  F.). 
This  difference  is  much  more  perceptible  in  the  rainy  regions.  In  the  Malay 
Archipelago  the  annual  rainfall  exceeds  2  metres  (78*6  inches),  whilst  in  Cochin- 
China  it  varies  between  1  and  2  metres  (39 '3  and  78*6  inches).  The  rainfall  is, 
moreover,  distributed  in  a  different  way.  In  Malasia  there  is  not,  properly 
speaking,  any  dry  season,  and — after  wdnter  time,  during  wThich  the  periodical 
rains,  heralded  in  by  the  south-west  monsoon,  prevail — frequent  showers  con- 
stantly enrich  the  soil.  But  in  Cochin-China  and  Cambodia,  after  a  season  of 
daily  storms,  another  of  absolute  dryness  is  endured.  Trees  transplanted  into  a 
soil  under  an  unsuitable  climate  will  perish,  or,  at  best,  are  sickly  and  degenerate ; 
they  grow,  but  only  yield  produce  of  an  inferior  quality.  To  these  difficulties, 
in  the  experimental  acclimatisation  of  guttiferous  trees — not  insurmountable 
difficulties  if  the  experiments  be  conducted  within  the  guttiferous  zone — other  great 
difficulties  have  to  be  added.  As  recognised  by  Seligmann  Lui,  it  is  not  the 
electric  properties  or  the  plastic  properties  which  alone  characterise  a  good  gutta 
percha,  but  also  its  durability.  Since  the  time  of  the  construction  of  the  first 
cables,  we  have  tried  to  increase  the  insulation  by  different  processes  :  by  a  mixture  of 
different  kinds,  this  has  been  done  much  beyond  what  is  necessary.  But  of  the 
substances  employed,  how  many  are  as  durable  as  the  pure  products  of  superior 
quality  used  in  the  beginning  1  Whatever  results  may  be  obtained  in  the  laboratory, 
great  stress  should  be  laid  on  that  important  element,  previous  experience.  If  a 
new  gutta  percha  appears  to  present  advantages,  without  doubt  its  culture  should 
be  attempted,  but  as  an  experiment  only,  as  such  gutta  percha  has  not  been  proved. 
But  substances  the  value  of  which  has  been  determined  long  before,  ought  to  inspire 
quite  different  confidence.  In  the  first  rank  of  the  latter,  Seligmann  places  gutta- 
derrian  or  taban.  White,  when  pure,  this  product  is  generally  tinted  brownish 
red  by  foreign  matter.  It  has  all  the  appearances  of  a  good  gutta  percha.  It  is 
the  quality  most  highly  esteemed  on  the  market,  and  it  is  it,  without  doubt,  which 
was  exploited  in  the  first  instance.  We  fell  back  on  other  kinds  when  this  became 
rare.  According  to  the  same  writer,  the  second  place  always  belongs  to  gutta 
sundek  and  gutta-babou ;  this  is  also  in  accordance  with  commercial  tendencies. 
Gutta-sundek  exhibits  a  white  compact  mass,  the  smooth  and  brilliant  cut  of 
which  has  the  appearance  of  ivory.  Generally,  the  products  placed  on  sale  have  a 
reddish  colour,  due  to  the  mixture  of  gutta  percha,  properly  so  called,  produced 
from  the  latex,  which  circulates  between  the  bark  and  the  wood,  with  a  coloured 
juice,  which  flows  from  the  exterior  cortical  tissue.  This  gutta  percha  would 
appear  to  be  less  plastic  than  the  dernan.  The  gutta-babou,  of  a  brighter  and 
redder  colour  than  the  derrian,  has  not  so  fine  a  tissue.  It  is,  perhaps,  also  more  > 
rigid.  The  guttas,  belouk  and  gapouk,  confused  in  commerce  under  the  name  of 


CLIMATOLOGY 


321 


,j,itt,i  l,nut,lt  (white),  are  hut  little  esteemed.     They  exhibit,  in  fact,  a  property 

whirl)    inakrs    them    rlosely    approach     the    f/iiffa    called    Itoiilut  l.'tl'iin,    a    Substance 

from  tin-  |n\\ci  islrs  ami  marshy  lands,  whieh  is  of  no  value.  It  IM-.-MIH,  •>  friable  and 
pulverulent  after  ,»  romparativrly  short  time.  Future  conscientious  and  intelligent 
re-e;iivhi's  \\ill  s!m\\  \\liether  this  transformation  is  a  simple  ph\-ieal  change,  or 
\\hether  the  pheiinnien.-i  "f  •  ».\ i« lat i« in  and  resin ification  observed  in  the  case  of 
all  -.Id  i^utta  pen-has  are  pp.dueed  im.iv  rapidly  in  these  two  kinds.  They  \\\\\ 
show  \\hether  the  heating  processes  are  capable  of  preventing  or  retarding  these 
phenomena,  «»r  \\hether  we  should  al>olish  the  use  of  these  substances,  at  least  for 
telegraphic  purposes,  on  account  of  their  short  durability.  They  would  then  find 
their  use  in  certain  industries,  where  the  low  price  will  compensate  for  the  prompt 
deterioration,  as  in  electro-metallurgical  moulds.  The  mayang  producing  the  latex 
of  the  ijiiftn  >l,  /-/-A///  may,  at  any  rate,  be  used  in  rational  culture  and  trans- 
plantation experiments.  The  value  of  the  other  species  will  be  ascertained  when 
lon.^  and  delicate  researches  have  thrown  light  on  the  subject.  To  elucidate  this 
point,  not  only  should  the  electrical  properties  be  examined,  insulation,  and  specific 
inductive  capacity,  but  all  the  other  physical  and  chemical  properties — whether  the 
gutta  percha  be  elastic,  its  behaviour  towards  heat,  at  what  temperature  it  softens, 
what  consistency  it  assumes  after  having  been  melted,  how  it  resists  oxidising  agents, 
if  it  be  permeable  to  water  under  pressure,  etc.  etc.  And  when  the  answer  to  so 
many  questions  has  been  favourable,  when  prolonged  trial  has  been  joined  to  the 
testimony  of  experience,  then  only  will  be  the  time  to  reply  and  to  propagate  the 
new  culture.  As  the  results  of  these  researches,  shall  we  get  better  results  than 
that  afforded  by  gutta-derrian'\  It  is  possible ;  but  if  to  the  fifteen  to  twenty 
years  required  before  a  plantation  yields  its  first  products  we  add  the  number  of 
years  which  will  be  required  for  the  durability  test  to  be  conclusive,  we  throw  any 
conclusion  back  thirty  to  forty  years. 

TABLE  XCI. — ANALYSIS  OF   COMMERCIAL  SAMPLES  ON  BOUNDARY  OP 
GEOGRAPHICAL  AREA  OF  GROWTH  OF  GUTTA  PERCHA  TREES  (OBACH). 


No. 

Percentage  Composition. 

Totals.                     Ratios. 

Percentage 
Composition. 

Gutta. 
G. 

Resin. 
R. 

Dirt. 
D. 

Water. 
W. 

C*     "P 

(G.+R.) 

Waste. 
(D.+W.) 

G.  P. 

Gutta. 

Gutta. 

Resin. 

Waste. 

Resin. 

(1) 
(2) 
(3) 
(4) 
(5) 
(6) 

68-5 
42-0 
50-4 
317 
72-8 
41-5 

18-1 
14-4 
12-9 
26-0 
13-6 
19-5 

11-9 
16-9 
12-6 
22-3 
9-5 
14-0 

1-5 
267 
24-1 
20-0 
4'1 
25-0 

86'6 
56-4 
63-3 
577 
86-4 
61-0 

13-4 
43-6 
367 
42'3 
13-6 
39-0 

6-5 
1-3 
17 
1-4 
6-4 
1-6 

3-8 
2-9 
3-9 
11 
5-4 
2-1 

79-1 
74-5 
79-6 
54-9 
84'2 
68-0 

20*9 
25-5 
20-4 
45-1 
15-8 
32-0 

(1)  N.N.E.  (or)  British  North  Borneo  ;  light  brown,  little  fine  bark. 

(2)  E.  (within),  Coti,  Borneo  ;  brown,  grey,  woody. 

(3)  S.S.E.  (well  within),  Banjermassin,  Borneo  ;  light  pinkish  brown,  woody. 

(4)  S.S.W.  (within),  Lampong,  Sumatra;  brown,  woody. 

(5)  W.  (without),  Achin,  Sumatra ;  light  brown,  dense,  clean. 

(6)  N.N.W.  (within),  Penang,  Malacca ;  brown,  much  fine  bark. 

The  questions  of  soil,  climate,  and  cultivation  of  gutta  percha  are  long  and 
difficult  ones.  Many  years  must  pass  before  science  can  definitely  decide  the  point. 
The  British  have  prosecuted  these  experiments  for  a  long  time.  Choosing  the 
island  of  Ceylon  as  an  experimental  field,  they  are  within  the  territorial  limits 
essential  to  success;  and  if  Pierre,  in  Cochin-China,  has  had  no  chance  of  pro- 
ducing any  results,  it  is  to  the  zone  selected  to  which  the  unsuccess  must  alone  be 
attributed.  Were  these  same  experiments  resumed  in  the  line,  more  near  to  the 
Equator,  of  the  new  French  African  possessions,  the  French  imagine  that  they 
21 


322  GUTTA   PERCH A 

also  would  be  in  possession  of  a  real  gutta  percha  market,  in  addition  to  their 
excellent  indiarubber  market.  But  all  plants,  in  order  to  prosper,  ought  to  be  able 
to  enjoy  a  minimum,  though  variable,  quantity  of  heat  and  moisture.  The 
minimum  qualities  ought  to  be  exactly  determined  for  each  species.  To  lie  at 
fault  in  any  of  those  requirements  in  any  acclimatisation  experiment  is  to  court  a 
check.  The  plants  submitted  to  a  regime  which  is  not  theirs  are  doomed  to  die  ; 
and  if  death  spares  them,  the  impoverishment  is  such  that  complete  degeneration 
takes  place,  not  only  in  regard  to  the  vigour  of  the  foliage,  the  trunk  and  branches, 
but  also  in  their  productive  value,  whatever  it  may  be.  An  example  amongst 
many  will  make  this  better  understood.  In  Europe  the  stem  of  our  hemp  pro- 
duces textile  fibres.  Transplanted  into  India,  the  same  grass  produces  a  resinous 
volatile  oil,  known  under  the  name  of  Ganga,  with  very  energetic  narcotic 
properties.  The  resin  is  evidently  formed  at  the  expense  of  the  fibre,  which 
becomes  useless,  and  no  longer  furnishes  anything  but  bad  fuel. 

The  Netherlands  Indian  Government  gutta  percha  plantation  in  Java. — 
Dr.  W.  Burck,  who  in  1883  received  an  order  from  the  Netherlands  Indian 
Government  to  institute  an  inquiry  regarding  the  gutta  percha  yielding  trees, 
claims  the  credit  of  having  brought  to  light  the  trees  which  produce  the  different 
kinds  of  gutta  percha  collected  by  the  natives.  From  his  researches  it  appeared 
that  the  gutta  percha  which  is  specially  needed  for  the  cable  industry  was  only 
obtained  from  a  very  few  species  of  trees,  whose  presence  in  the  forests  was 
becoming  more  and  more  rare.  According  to  Burck,  they  are  trees  belonging  to  the 
family  of  Sapotacece,  namely, — the  genus  Palaquium,  from  which  Pal.  ohlongifoliurn. 
Pal.  borneense,  and  Pal.  gutta  yields  the  best  gutta  percha.  The  existence  of  these 
trees  is  limited  to  a  small  area  extending  to  6°  on  either  side  of  the  Equator, 
and  from  99°  to  119°  E.  longitude.  As  may  be  seen,  the  greatest  part  of  this 
area  lies  in  Netherlands  India,  where  also  the  largest  quantity  of  gutta  percha 
is  obtained. 

When,  through  the  researches  of  Burck,  Wray,  Seligmann,  Serullaz,  and  van 
Romburgh,  the  veil  which  hid  the  mystery  of  gutta  percha  and  its  origin  was 
lifted,  it  also  became  known  that,  unless  measures  were  taken,  the  gutta  percha 
yielding  trees,  owing  to  the  ruinous  manner  of  collecting  adopted  by  the  natives, 
would  be  entirely  exterminated  in  a  very  short  time.  Already  in  the  forests  of 
Borneo  and  Sumatra,  in  the  neighbourhood  of  rivers,  no  gutta  percha  trees  are  to  be 
met  with,  and  the  natives  have  to  travel  for  days  into  the  jungle  to  find  them. 
What  the  position  would  be  if  the  236,840  miles  (439,047  kilometres)  of  submarine 
cables  now  in  use  had  to  be  renewed,  can  easily  be  understood,  if  it  is  known 
that  for  1  kilometre  of  cable  about  25  kilogrammes  of  gutta  .percha  of  the  best 
quality  is  required,  and  a  fifteen-  to  twenty-year-old  tree  when  felled  yields  no 
more  than  400  grammes  of  the  product.  For  the  insulating  of  236,840  miles  of 
submarine  cable  it  would  thus  be  necessary,  at  a  moderate  estimate,  to  fell  fully 
27,000,000  gutta  percha  trees.  With  these  figures  before  them,  and  bearing  in 
mind  the  great  interest  that  all  civilised  nations  have  in  common  in  the  continued 
existence  of  the  submarine  cables,  the  Netherlands  Indian  Government  soon 
realised  that  on  their  part  steps  must  be  taken  to  prevent  the  entire  extermination 
of  the  gutta  percha  yielding  trees.  Although  it  was  at  first  thought  that  this 
object  would  be  obtained  by  a  sharper  control  over  the  collecting,  whereby  the 
natives  would  be  forbidden  to  fell  trees  below  a  certain  measurement,  it  soon 
appeared  in  practice  that  the  maintenance  of  these  regulations  in  the  almost 
inaccessible,  uninhabited,  virgin  forests  of  Sumatra  and  Borneo  was  most  difficult, 
if  not  impossible.  Notwithstanding  the  fact  that  repeated  attempts  have  been  made 
to  replace  gutta  percha  by  some  other  insulating  material  for  submarine  cables, 
these  efforts  have  not,  up  to  the  present,  been  crowned  with  success.  The 
determination  to  discover  other  insulating  materials  was  due  to  the  fact  that 
with  the  considerable  extension  of  the  submarine  cable-net  a  proportionately  greater 
use  was  made  of  gutta  percha.  There  was  thus  every  reason  for  anxiety  as  to 
whether  in  the  future  the  necessary  quantity  of  gutta  percha  could  be  reckoned 


CLIMATOLOGY 


323 


iiji  >ii  t'-n-  tin-  manufacture  "1  submarine  cables.  As  so  little  was  known  regarding 
tin-  nvrs  which  yielded  the  so  valuable  gutta  percha  as  already  mentioned,  one 
I'Viich  (Si-li^muim  Lui),  «.nc  Kn^lisl,  (Wroy),  and  OIK;  Dutch  (Burck)  expedition 

\\.i-  littril  out   \\ith  the  ul.jrrt  of  throwing  \\g\\l  UJM.H  th«-  matter. 

On    tin-    ailvii t'     lYolV^.n-    Tiviib,     Din-ctor    "I"    tin*     llut.inical     (iar«l'': 


FIG.  116. — Netherlands  Government  gutta  percha  plantation  in  Java. 

Buitenzorg,  Mr.  Cremer,  then  Dutch  Minister  of  Colonies,  whose  attention  had 
Kvn  drawn  to  the  subject,  was  recommended. to  promote  the  cultivation  of  gutta 
percha  trees  on  a  larger  scale  than  had  until  then  taken  place.  The  Minister 
acceded  to  this  proposal,  and  in  1900  it  was  decided  to  establish  a  Government 
gutta  percha  plantation,  with  the  carrying  out  of  which  the  Director  of  the 
Botanical  Gardens  at  Buitenzorg  was  entrusted.  The  cultivation  on  a  large  scale 


324  GUTTA   PERCHA 

would  not  have  been  practicable  within  a  short  time,  if  Treub  and  Burck  had  not 
previously  adopted  measures  for  the  planting  of  seed  trees,  it  being  evident  that 
no  quantity  of  seed  worth  mentioning  could  be  obtained  from  forest  trees.1  Dr. 
Burck  had  brought  with  him  several  seedlings  from  his  journey  in  the  Padang 
Highlands  in  1883,  and  these  were  planted  in  the  Agricultural  Gardens  at 
Buitenzorg.  In  1856,  through  the  intermediacy  of  Teysmann,  a  small  garden 
of  Palaquim  oblongifolium  and  borneense  was  planted  in  the  Residency  Banjcemas. 
As  the  space,  however,-  was  limited,  a  somewhat  larger  plantation  was,  on  the  advice 
of  Professor  Treub,  laid  out  in  1885  at  Tjipetir,  in  the  Residency  Preanger 
Regencies,  for  which  the  seed  was  obtained  from  the  first-mentioned  garden. 
When,  therefore,  in  1900  it  was  decided  to  open  up  a  large  gutta  percha  plantation, 
there  was  no  difficulty  in  obtaining  seed,  owing  to  the  existence  of  a  great  number 
of  seed-bearing  trees  in  the  small  plantations  already  mentioned.  If  there  was 
for  a  moment  any  doubt  as  to  which  place  in  Java  was  most  suitable  for  the  new 
plantation,  the  preference  was  speedily  given  to  Tjipetir.  Evidence  had  shown 
that  gutta  percha,  although  not  growing  wild  in  any  part  of  Java,  nourished 
there.  Moreover,  the  opportunity  was  favourable,  as  there  were  about  5000  acres 
of  forest  ground  available  at  Tjipetir.  The  immediate  neighbourhood  of  the 
seed  trees,  the  presence  of  cheap  labour,  and  the  nearness  to  a  railway  station 
and  to  Buitenzorg,  were  other  considerations  which  influenced  the  decision 
come  to. 

The  Government  gutta  percha  plantation  at  Tjipetir. — This  plantation  is 
situated  in  the  Residency  Preanger  Regencies,  eight  miles  from  the  railway  station 
Tjibadak,  and  seventeen  miles  from  Wynkoops  Bay,  on  the  south  coast  of  Java,  at 
an  elevation  of  about  1700  feet  above  the  sea,  on  the  spurs  of  the  extinct  volcano 
Salak.  The  plantation  is  divided  into  the  following  subdivisions :  Pasir  Kilang, 
Tjirawa,  Tjipetir,  and  Panjindangan.  The  climate  is  healthy  and  pleasant,  with 
a  maximum  temperature  by  day  of  27°'4C.  and  by  night  of  19°'7C.,  while  as 
regards  moisture,  it  may  be  classed  with  those  regions  having  an  abundant  rainfall. 
In  the  neighbourhood  of  the  plantations  are  situated  a  number  of  flourishing 
tea  estates.  The  cultivation  of  tea  prospers  here  exceedingly.  Soil. — The  gardens 
are  hilly,  and,  consequently,  the  composition  of  the  soil  varies  in  different  places. 
On  the  summits  of  the  hillocks,  and  in  places  which  have  formerly  served  as 
farm  ground  for  the  native  cultivators,  who  took  no  measures  to  prevent  washing 
away  of  the  ground,  it  is  less  fertile  than  in  those  areas  which  were  formerly 
covered  by  forest.  The  soil  consists  principally  of  a  brown  porous  clay  with 
about  9  per  cent,  of  sand.  The  subsoil  is  also  porous  to  a  considerable  depth, 
so  that  no  drainage  precautions  have  to  be  taken.  In  the  rainy  season  it  is 
easily  worked,  for  which  purpose  the  native  hoe  is  exclusively  used.  No  use 
is  made  of  European  farm  implements,  such  as  ploughs,  harrows,  rollers,  spades, 
etc.,  they  being  too  expensive  and  unsuitable.  A  great  advantage  lies  in  the 
capacity  of  the  soil  for  retaining  moisture,  so  that  even  in  the  event  of  a  drought 
of  two  months  there  is  still  sufficient  water  in  the  ground,  and  it  has  not  yet 
happened  that  the  leaves  of  the  trees  have  drooped  owing  to  drought.  Method 
of  cultivation. — Although  gutta  percha  trees  in  the  forests  originally  grow  in 
the  shade,  it  is  not  necessary  to  cultivate  them  in  this  manner  any  more  than  it 
has  been  found  necessary  in  the  case  of  Para  rubber  trees,  which,  in  the  natural 
state,  grow  between  other  surrounding  trees.  On  the  summits  of  hillocks  and 
other  exposed  situations  it  is  desirable  to  give  the  young  plants  some  shelter. 
This  is  possible  by  planting  at  the  same  time  dadap  (Erythrina)  or  other  plants 
which  are  useful  for  green  manuring,  such  as  Tephrosia,  Indigofera  and  other 
Leguminosece.  In  the  beginning  gutta-percha  was  planted  at  a  distance  of  fully 
12  feet  by  12  feet.  When  more  planting  material  was  available,  and  it  appeared 
that  by  closer  planting  the  upkeep  was  cheaper,  and  that  the  plantation  by  the 

1  Bats  are  very  fond  of  the  ripe  fruit,  which  they  consume  on  the  wing,  so  that  it  is  very 
difficult  to  find  seeds  amongst  the  dense  undergrowth  of  the  virgin  forest.  Moreover,  the 
greater  part  of  the  seeds  lose  their  germinating  power  within  four  weeks  after  being  plucked. 


CLIMATOLOGY  325 

extraction  of  gutta  percha  from  the  leaves  could  iinnv  rapidly  IK-  brought  t<» 
the  stage  <>f  j»ri.diieti«ni,  a  closer  method  of  planting  u.i>  adopted,  and  the  j. hinting 
distance  reduced  to  4  to  G  feet  s.|ii;uv.  As  t  he  gun  l'-n-  •  >\  Tjip't  ir  are  hilly,  tin- 
rows  of  plants  follow  the  >|..|,rsof  the  gardens,  in  the  same  manner  as  is  u>iial 
in  the  cultivation  of  tea.  Measures  must  be  taken  to  prevent  \\a>limg  a\\.i\ 
..t'  the  Around  l.\  the  al.iindant  rains.  Young  plants  in  the  beginning  have  to 
struggle  against  crickets  and  white  ants;  and  At  a  later  age  leaf-eating  caterpillars 
such  as  /Shu-fun.  n,-'t  iHf/i-titfi  Drnri/,  ()j>liin*,i  Mrva  I''"1'!-.,  can  cause  a  great  deal 
of  injury  to  the  plants,  the  first-named  being  specially  to  be  feared.  Planted 
1  feet  apart  in  favourable  gardens,  the  plants  have  closed  up  in  their  third  year, 
and  recourse  must  be  had  to  thinning. 

Wantiii;/  ni'it'  ,-inl. — As  already  mentioned,  the  planting  material  is  principally 
drawn  from  the  seed  hearing  trees  planted  by  Dr.  Uurck  at  Tjipetir  in  188G.  In 
the  beginning  Dr.  Burck  planted  Pal.  oblongifolium,  Pal.  yutta,  Pal.  bameente,  and 
/'<//.  Trtubti.  The  planting  material  of  these  trees  as  regards  P«l.  obloiuflfofaun, 
\\as  obtained  partly  from  plants  collected  by  Dr.  Burck  in  the  Padang  Highlands, 
and  partly  from  the  plantations  in  Banjcemas.  The  seeds  of  /'.//.  </"""  and  Pal. 
Ixirneense  came  from  the  Botanical  Gardens.  Tin-  propagating  <>f  the  last  named 
species  was  less  rapid  than  that  of  Pal.  o/>/o//y //'<////////,  owing  to  want  of  planting 
matt-rial.  The  seed-bearing  trees  at  Tjipetir  therefore  consist  mostly  of  ./'•//. 
o'llniiiil/nliiini.  When  it  appeared  from  a  subsequent  examination  that  the  product 
of  Pal.  T,:  ii'til  had  to  be  ranked  with  the  inferior  kinds,  and,  moreover,  that  the 
nature  of  its  leaf  did  not  readily  admit  of  the  mechanical  serration  of  the 
gutta  percha  therefrom,  all  Treubii  trees  were  cut  down  shortly  after  the  establish 
ment  of  the  plantations,  to  make  certain  that  no  hybridising  could  take  place  with 
the  superior  species.  Pal.  gutta,  Pal.  oblongifolium,  and  Pal.  borneenze,  which 
possess  a  great  similarity  one  with  the  other,  all  yield  a  superior  product.  On 
the  Government  gutta  percha  plantations  these  three  species  are  now  exclusively 
cultivated.  At  Tjipetir  the  gutta  percha  trees  blossom  about  August,  and  the  fruit 
ri{>ens  in  February-March.  Not  all  gutta  percha  trees  blossom.  From  the  8596 
trees  older  than  fifteen  years,  2360  bore  fruit  in  1906.  Before  the  tenth  year 
the  quantity  of  fruit  borne  is  unimportant.  A  single  seven-year-old  tree  bore  some 
fruit  a  short  time  ago.  It  must  here  be  noted  that  a  crop  of  seed  cannot  be  looked 
for  every  year,  as  in  some  years  the  crop  is  a  failure.  The  seeds  soon  lose  their 
germinating  power.  If  they  are  not  planted  within  four  weeks,  then  the  majority 
have  lost  their  germinating  power.  The  seeds,  which  are  as  big  as  an  almond,  are 
planted  in  covered  nursery  beds  at  distances  of  15  centimetres.  The  germination 
takes  place  within  fourteen  days.  The  seeds  must  be  superficially  planted,  as  tin- 
young  stalk  grows  twisted  if  they  are  planted  too  deep.  After  nine  or  ten  months 
the  young  plants  are  fit  for  transplanting.  It  is,  however,  better  to  transplant  them 
when  over  a  year  old.  When  transplanting,  the  tap  root  and  young  stem  are 
shortened.  Propagating  of  gutta  percha  trees  by  means  of  cuttings  or  grafts  is 
ditlicult,  so  that  for  planting  on  a  large  scale  one  is  entirely  dependent  on  seeds.1 

The  planting  distance  is,  as  already  stated  above,  not  everywhere  alike. 
During  the  last  three  years  the  trees  of  several  plantations  have  been  planted  at 

1  This  seems  in  conflict  with  what  Obach  says  in  his  Cantor  Lectures  :— "  It  has  variously 
been  asserted,"  says  Obach,  "that  gutta  trees  cannot  be  reared  from  seeds.  But  I  can  a«fUiv 
you,  on  the  high  authority  of  Dr.  Treub,  that  this  mode  of  propagation  is  quite  feasible,  although 
the  seeds  do  in  it  kerp  their  g«  Tininating  power  very  long,  and  a  more  certain  method  is  that 
technically  known  ;is  maivuttage,  which  consists  in  luirving  a  branch  of  the  tree  in  the  ground, 
allowing  it  to  take  root,  and  afterward  separating  it  from  tin-  parent.  According  to  informa- 
tion obtained  for  me  from  a  Chinese  gutta  planter,  cutting  from  oM  tre. •>  .an  also  be  used  for 
propagation,  and  it  is  best  to  HIM  it  tlu-m  into  a  cocoanut  to  take  root  there  and  then  transplant 
tin-in.  Young  plants  reared  in  this  way  can  be  bought  at  Penang  and  Batavia  at  fjO  cents  a 
piece.  Saplings  from  the  jungle  where  ..litainaMe.  or  from  plantations,  are  al>o  .suitable  for 
transplanting.  an>l  they  can  now  be  bought  in  Malacca  at  a  very  low  price.  Dr.  Treul>  linus 
young  plants  reared  from  Marcottes  more  vigorous  than  those  from  seeds.  Grafting  is  declared 
to  be  impossible  by  Mr.  Ridley,  on  account  of  the  fungi  and  bacilli  which  attack ^the  plant. 
M.  Serrulaz  took  the  whole  stools  from  the  forest  and  transferred  them  to  a  nursery." 


326  GUTTA  PERCHA 

a  distance  of  4  feet  by  4  feet,  while  in  the  older  gardens  the  distance  is  12  feet  by 
12  feet.  Where  the  gutta  percha  does  not  nourish,  other  kinds  of  trees  are  planted. 

Obtaining  the  product. — As  is  already  known,  the  gutta  exists  not  only  in  the 
bark  but  also  in  the  leaves.  The  bark  contains  about  5  per  cent,  gutta  percha,  of 
which  about  3  per  cent,  is  gutta,1  and  the  fresh  leaves2  of  the  superior  kinds 
contain  about  10  per  cent,  gutta  percha,  of  which  about  5  per  cent,  is  gutta, 
calculated  on  the  basis  of  dry  matter.  Fresh  bark  contains  about  65  per  cent, 
water,  and  in  the  case  of  freshly  plucked  leaves  this  figure  amounts  to  about  60 
per  cent.  Young  bark  and  young  leaves  contain  a  larger  percentage  of  water. 
A  portion  of  the  latex  is  obtained  in  a  very  simple  manner  from  the  bark.  For 
this  purpose  it  is  necessary  to  make  an  incision  in  the  stem,  and  after  a  short  time 
the  latex  exudes  from  the  wound.  To  obtain  as  much  product  as  possible  from 
the  stem,  the  natives  first  fell  the  tree  and  afterwards  proceed  with  the  real  tapping. 
For  this  purpose  they  ring  the  stem  at  distances  of  a  foot.  The  latex  that  exudes 
from  the  circular  wounds  is  caught  up  in  basins.  A  portion  coagulates  in  the 
wounds,  which  is  later  on  collected  together  with  a  scraper.  The  liquid  latex  is 
placed  in  a  pan  above  a  slow  fire  to  coagulate,  softened  in  warm  water,  and  after- 
wards kneaded  firmly  together.  The  gutta  percha  which  the  leaves  contain  is  not 
obtained  in  so  simple  a  manner.  At  a  comparatively  early  date  people  concerned 
themselves  with  the  preparation  of  gutta  percha  from  leaf.  The  first  idea  was  to 
obtain  the  gutta  percha  from  the  leaves  by  extraction  with  chemical  substances, 
such  as  toluol,  benzine,  etc.,  but  no  practical  results  were  obtained  by  these 
methods,  as  the  gutta  percha  after  being  treated  by  these  agencies  undergoes  a  change 
which  makes  it  unsuitable  for  the  insulating  of  submarine  cables.  Better  results 
were  however  obtained  from  mechanical  preparation.  This  method  was  first 
brought  into  use  by  a  Frenchman  named  Arnaud.  Later  on  it  was  improved 
and  applied  on  a  large  scale  by  Ledeboer,  who  for  that  purpose  established  a  large 
factory  at  Singapore.  The  method  is  in  principle  to  grind  the  fresh  leaves  to  a 
pulp,  which  is  then  boiled  with  water,  after  which  the  gutta-percha,  which  rises  to 
the  surface,  is  skimmed  off.  Dr.  Tromp  de  Haas  has  also  succeeded  in  obtaining 
gutta  percha  from  old  fallen  leaves  by  mechanical  means.  The  yield  is  in  this 
case  not  so  large  as  from  fresh  leaves. 

The  preparation  from  leaves  has  the  following  advantages  : — 1.  In  the  case  of 
cultivated  trees,  a  commencement  may  be  made  with  the  obtaining  of  the  product 
in  the  third  and  fourth  year,  whilst  otherwise  at  least  fifteen  years  must  elapse 
before  the  stems  can  be  tapped.  2.  In  this  manner  the  largest  yield  per  planted 
acre  is  obtained.  3.  This  method  of  collecting  is  the  least  injurious  to  the  tree. 
It  is  intended  to  work  the  Government  gutta  percha  plantation  according  to  both 
systems,  namely,  by  obtaining  the  product  from  the  leaves,  by  mechanical  process, 
and  by  obtaining  the  product  from  the  stem.  This  is  possible  if,  from  the  be- 
ginning, the  trees  are  planted  closely  together.  In  the  course  of  years  a  thinning 
out  takes  place  in  such  a  manner  that  at  last  a  certain  number  of  well  developed 
trees  remain  standing,  which  must  serve  for  the  obtaining  of  the  product  from  the 
stem.  For  this  purpose  they  will  not  be  felled  but  regularly  tapped.  From  the 
leaves  and  young  twigs,  obtained  from  the  thinning  out,  the  gutta  percha  will,  in 
the  meantime,  be  extracted  by  mechanical  process.  In  order  to  obtain  an  idea 
as  to  the  probable  results,  the  following  leaf-production  was  obtained  in  an  ex- 
perimental plot  at  Tjipetir.  From  a  three-year-old  garden  with  trees  planted 

1  The  latex  consists  chiefly  of  water,  gntta  percha,  salts,  proteids,  and  some  other  substances. 
The  proportion  of  gutta  percha  amounts  to  about  40  per  cent.     Gutta  percha  itself  consists  of 
a  mixture,  probably  of  some  solid  gutta  liydrocarbides  with  different  quantities  of  oxygenous 
coinpounds,  to  which  the  general  name  of  resins  has  been  given.     Gutta  is  the  most  important 
ingredient,  and  the  properties  of  gutta  percha  are  for  the  most  part  dependent  thereon.     The 
produce  from  the  stem  of  the  best  kinds  contains  about  85  per  cent,  gutta  and  about  15  per 
cent,  resinous  matter.     Gutta-percha  prepared  mechanically  from  the  leaves  contains  about  90 
per  cent,  gutta  and  10  per  cent,  resinous  matter. 

2  The  quantity  of  gutta  and  resinous  matter  in  the  leaves  is  not  always  the  same.     This  is 
dependent  on  various  factors,  such  as  age  of  the  leaf,  of  the  tree,  etc. 


CLIMATOLOGY  .rJ7 


1  feet  apart,  from  Q*8fi  MN  's'.">  kilos,  of  fivsh  l«-af  ua-  obtained  by  pruning  and 
thinning  out,  and  tin-  following  \ear  -Til  kil<-.  After  tin-  thinning  out  tln-iv 
still  ivmaiiir.l  I  :;•_'()  trees  per  0'88  acre.  For  the  following  yean*  no  particulars 
an-  yd  kiioun.  1-Yoin  an  experimental  ar>  iriog  n-.",r>  acre,  coinpri 

"».")  treea  planted  in  1SSS.  tin-  «|iiantity  of  fallen  leaf  \\as  \\.-igh.-d  during  twoy< 
Tin-  average  fall  on  leaf  amounted  per  year  to  13GS  kilos.,  or  about  25  kilos.  per 
tree,  Above  figures  \\\\^\  not  I..-  taken  as  a  l.a-is  for  the  whole  plantation,  because 
tin-  condition  of  tin-  experimental  plots  is  generally  more  favourable  than  that  of 
the  \\holt-  plantation,  but  they  allow  us  to  make  a  cautious  estimate.  Kxp<  •rimcnte 
regard  ing  the  tapping  of  the  trees  according  to  the  native  method,  i.e.  by  felling 
tin-  trees,  gave  the  following  results:  —  S  twenty-year  old  trees  yielded  1831 
grammes  gutta  pereha,  or  an  average  per  tree  of  0'228  kilo;  363  twenty-year- 
old  trees  t  a  pi  Kid  according  to  the  herring-bone  method  yielded  after  three  tappings 
(after  the  third  incision  no  more  juice  exuded  from  the  wounds),  30'048  kilos. 
gutta  pi-rcha,  or  an  average  per  tree  of  about  80  grammes;  25  nineteen-year-old 
tapped  according  to  the  same  method  yielded  1819  grammes  gutta  pereha,  or 
an  average  per  tree  of  73  grammes.  In  1912  the  plantation  will  be  in  full  pro- 
duction as  regards  the  crop  of  leaf.  With  the  winning  of  product  from  the  stem, 
a  commencement  cannot  be  made  before  1915  as  regards  the  gardens  planted  in 
1900.  The  oldest  trees  will  then  be  fifteen  years  old.  The  yearly  yield  from  the 
stem  products  is  estimated  to  be  1  1  kilos,  dry  gutta  pereha  per  acre  for  the  whole 
of  the  Tjipetir  plantation. 

(intta  perc/uifat.  —  The  seeds  of  the  gutta  pereha  tree  contain  a  great  amount 
of  a  vegetable  fat  of  high  melting-point,  which  can  very  well  be  used  for  several 
technical  purposes.  The  seeds  consist  of  about  85  per  cent,  kernels  and  about  15 
per  cent,  husk  (or  shell).  The  composition  of  the  fresh  kernels  is  as  follows  :  —  Water, 
!.">  per  cent  ;  ash,  1*6  per  cent.  ;  proteids,  4  '8  per  cent.  ;  fat,  32'5  per  cent.  ;  carbo- 
hydrates, 14  per  cent.  ;  fibre,  2'1  per  cent.  Based  on  water  free  substance  —  ash, 
2-90  per  cent.;  proteids,  875  per  cent.;  fat,  59'09  per  cent.;  carbohydrates, 
25-46  per  cent.  ;  fibre,  3  '8  2  per  cent.  The  melting-point  of  the  fat  is  about 
40°  C.,  and  it  is  thus  solid  at  ordinary  temperatures.  It  is  composed  of  the 
following  fats:  —  Stearine,  57*5  per  cent.;  oleine,  36  '0  per  cent.;  palmitine,  6'5 
per  cent.  To  make  an  estimate  of  the  future  fat  production  is  not  easy,  seeing 
that  the  fruit  bearing  of  the  trees  is  very  irregular.  In  1906,  of  8596  gutta  pereha 
trees  over  ten  years  old,  only  2360  bore  fruit,  which  produced  3795  kilos. 
dry  kernel,  and  this  quantity,  if  worked  to  obtain  the  fat,  would  have  yielded  1850 
kilos.  In  1918  all  trees  at  Tjipetir  will  be  ten  years  old.  Supposing  that 
the  number  of  trees  per  acre  averages  142,  then  the  total  number  of  trees  would 
be  347,000.  If  we  take  the  figures  of  the  year  1906  as  a  basis,  of  the  347,000 

I  only  27  '4  per  cent,  nor  fully  95,000  trees,  would  bear  fruit,  with  a  production 
of  fully  150,000  kilos,  dry  kernels,  out  of  which  fully  74,000  kilos. 
fat  could  be  extracted.  In  1904  the  value  of  100  kilos,  of  this  fat  was 
estimated  to  be  £2,  14s.,  a  value  higher  than  that  of  Chinese  vegetable  tallow 
(from  Stillingia  Sebifera). 


CHAPTER   III 

METHODS  OF  COLLECTION  —  FELLING  AND  RINGING  VERSUS 
TAPPING— EXTRACTION  OF  GUTTA  PERCHA  FROM  LEAVES 
BY  TOLUENE,  ETC. 

IN  Sumatra,  wild  gutta  percha  is  got  by  felling  the  tree.  When  the  trees  are  of 
colossal  size,  they  are  swollen  at  the  base.  This  enlargement  takes  the  form  of 
vertical  plates,  and  the  wood-cutters  are  obliged  to  erect  a  scaffolding  from  which 
to  fell  them.  Such  giants  are  rare,  and  are  only  met  with  in  forests  where  the 
natives  have  not  yet  penetrated  regularly  to  secure  the  resin.  The  native  collectors 
of  gutta  percha  go  to  the  forest  generally  in  gangs  of  three  to  four,  and  as  the 
producing  trees  are  found  in  the  densest  parts  of  the  virgin  forest,  and  as  the  woods 
adjoining  the  kampongs  (villages)  have  for  a  long  time  been  denuded,  the  gutta 
percha  searchers  have  to  make  a  home  for  several  days  in  the  forest,  and  build  a 
common  hut  for  the  purpose.  They  know,  with  marvellous  skill,  how  to  discover 
the  gutta  percha  tree  in  the  densest  part ;  and  if  they  have  the  slightest  doubt  in 
regard  to  the  tree  they  want,  the  leaves  of  which  they  cannot  discover  under  the 
vault  of  foliage  which  often  overhangs  it,  a  simple  incision  in  the  trunk  causes  a 
milky  juice  to  run  into  their  hands,  the  quality  of  which  they  can  thus  easily 
determine.  Moreover,  they  can  distinguish  the  species  without  risk  or  error 
by  the  trunk,  by  the  thickness  of  the  bark,  and  the  greater  or  less  hardness  of  the 
wood.  If  they  find  a  tree  which  appears  to  them  to  be  rather  big  to  be  exploited, 
they  fell  it  with  an  axe,  after  which  they  "  ring  "  it,  i.e.  trace  semicircles  on  it  by 
means  of  a  hatchet  30  to  50  centimetres  (say  12  to  20  inches)  apart.  In  some 
localities,  e.g.  Borneo,  before  ringing  the  trunk,  they  prune  or  strip  the  fallen  tree 
to  the  summit,  so  as  to  hinder  the  milky  juice  from  spreading  through  the  branches 
and  leaves  of  the  cyme.  The  juice  collects  with  greater  or  less  speed,  according  to  the 
species,  in  the  rings  traced  by  the  hatchet.  Obach  collected  some  figures  as  regards  the 
quantity  of  solid  gutta  percha  yielded  by  an  adult  tree.  The  data  given  are,  he  points 
out,  very  conflicting.  Older  writers  like  Oxley  and  Logan  give  as  the  average  13£  Ib. 
and  5J  Ib.  for  Singapore  and  Johor  respectively,  but  later  observers  quote  much 
smaller  figures.  Wray,  for  instance,  obtained  only  2  Ib.  5  oz.  of  fairly  clean  gutta 
percha  from  a  Taban  merah  at  least  a  hundred  years  old,  and  2  Ib.  11  oz.  from 
a  Taban  puteh.  Burck  obtained  on  an  average  only  11  oz.  from  adult  trees  in 
West  Sumatra,  and  Serrulaz  13  J  oz.  from  a  giant  tree  felled  in  Pahang  by 
Dyaks.  The  yield  evidently  depends  greatly  upon  the  kind  of  tree,  manner  in 
which  it  is  bled,  the  season,  etc.,  the  milky  sap  being  said  to  run  most  freely 
directly  after  the  rainy  season  is  over.  When  the  tree  is  wounded  without  first 
being  felled,  the  latex  flows  much  more  tardily  and  sparingly  and  also  coagulates 
quicker,  the  output  is  therefore  notably  smaller, — this  being  one  of  the  reasons  why 
the  Malays  still  resort  to  the  old  method  of  cutting  the  trees  down  before  bleeding 
them.  Sherman  (1907)  says,  "Trees  of  inferior  grade  have  been  found  to  give  as 
high  as  8  Ib.  Probably  the  best  average  obtainable  is  3  Ib.  In  the  Tiruray  district 
of  Mindanao  I  secured  1  Ib.  of  clean  gutta  percha  from  a  tree  135  feet  high  and 
5  feet  4  inches  in  circumference  at  the  base.  The  work  was  carefully  done  by  the 
natives.  Taking  a  measured  amount  of  the  bark  of  this  tree  after  no  more  gutta 
percha  could  be  collected  by  the  native  method,  and  extracting  all  of  the  gutta 


METHODS   OF   COLLECTION 

percha  which  it  still  contained,  it  \\a^  e-t  imated  that  after  c<  illeet  ion  there  still 
remained  •>.',  ll>.  of  ^utla  p'-reha.  Taking  into  consideration  tin-  t'art  that  had  tin- 
tree  not  lalleii  in  -iich  a  u.i\  as  to  lea\e  almost  all  o!  thf  trunk  propjn'd  hi^h 
enough  above  the  ground  to  allow  the  milk  to  be  extracted  from  tin-  bark  on  the 
Underside,  the  amount  extracted  would  undoubtedly  ha\e  U-en  much  less,  or,  in 
other  \\onU,  ten  times  more  gutta  |»ereha  would  ha\e  U-en  l«-tl  to  rot  with 

th«-  tree  than  was  taken  lY«»m  it  l.y  the  natives,  other  investigators  have 
secured  figures  as  large  as  these,  and  some  found  that  forty  times  more  gutta 
peivha  \\as  left  l.ehind  than  was  secured  by  the  careless  eolle,  • 
of  the  Pay ena  Lerii^  of  the  Tuban  derrian  and  tembaya  of  Soupayang, 
does  not  coagulate  immediately;  but  that  of  Dichopsis  oi,l»n,i(i',,i;,i  \<  tin. 
easily  gelantises,  and  condenses  between  the  bark  and  the  fibres  of  the  wood. 
In  regard  to  the  Dichopsis,  the  searcher  splits  with  his  hatehet  the  bark  of  the 
open  ring,  and  reduces  it  to  a  soft  pulp,  which  stops  leakage  on  the  outside. 
Some  say  the  native  only  regards  as  good  gutta  percha  that  which  solidities  in  his 
hand.  That  is  a  great  error,  and  Burck  affirms  that  the  gutta  percha  searcher 
knows  well  that  the  species  which  yield  a  clear  juice  may  furnish  a  very  utilisable 
gutta.  The  collection  of  liquid  gutta  percha  is  made  in  certain  localities  with 
extreme  . -a relessness ;  whilst  the  operator  traces  the  rings  at  the  base  of  the  c\ 
a  considerable  quantity  of  juice  flows  away.  He  does  not  take  the  trouble  to 
collect  this  liquid  in  the  bowls  or  in  the  receivers  cut  in  the  bark  of  the  trees. 
Certain  searchers  pretend  that  the  gutta  percha  which  thus  flows  away  is  of  inferior 
•  [iiality,  and  is  only  sold  at  a  low  price  in  commerce;  it  is  too  white,  and  they 
know  that  the  red  or  brown  colour  is  preferred.  Others  give  no  reason  for  their 
negligence.  The  tree  having  been  ringed  up  to  its  summit,  it  is  necessary  to 
collect  the  juice,  which  immediately  shows  itself  in  the  rings  or  depressions. 

Everything  in  the  depression — as  much  bark  as  solidified  juice — is  drawn  out 
with  an  iron  scraper,  and  packed  into  a  bag  made  from  the  matweed.  "When  the 
rings  have  been  scraped,  the  task  is  regarded  as  finished,  and  they  go  on  to  repeat 
the  same  operation  on  another  tree.  The  milky  juice  often  continues  to  flow  into 
the  rings  rather  abundantly;  it  is,  however,  neglected,  and  the  tree  is  wholly 
abandoned.  The  incisions  are  only  made  on  the  upper  half  of  the  fallen  tree. 
The  other,  the  lower  half,  touching  the  soil,  remains  intact;  it  is  impossible  to 
turn  this  half  to  incise  it,  as  it  would  entail  too  much  manual  labour,  too  many 
workmen,  and  the  situation  of  the  tree,  in  the  middle  of  the  forest,  on  uneven 
ground,  presents  numerous  insurmountable  difficulties.  The  tree,  halt  freed  of 
its  gutta  percha,  remains  neglected  in  the  wood,  yet  that  tree  yields  a  workable 
wood  and  excellent  building  timber.  In  other  localities  these  same  trees  are  felled, 
to  be  split  into  boards  or  planks,  without  bothering  to  collect  the  gutta  percha 
This  method  of  working  shows  incredible  improvidence.  Each  giant  tree  felled 
l-rings  with  it  a  certain  number  of  others.  It  is  sometimes  necessary  to  previously 
fell  those  which  surround  it,  and  which  are  bound  to  it  by  climbers  which  would 
hinder  its  fall.  The  consequences  of  such  a  destruction  of  guttiferous  trees  were 
easily  fun-seen,  and  have  been  more  acutely  felt  every  year  for  a  long  period. 

As  the  adult  trees  are  already  felled  where  it  has  been  possible  to  penetrate, 
the  natives  are  forced  to  content  themselves  by  exploiting  the  young  trees,  which 
only  yield  an  insignificant  quantity  of  latex.  It  is  said  that  a  gutta  percha  search er 
does  not  look  upon  a  Dichopsis  as  worth  exploiting  until  the  tree  reaches  the  size 
of  a  cocoa  nut  tree,  about  1  metre  (3'28  feet)  in  circumference.  But  now  it  rarely 
happens  that  trees  of  this  si/e  are  encountered,  and  it  is  then-fore  necessary  to  fall 
back  upon  the  young  plants.  In  the  forests  a  considerable  quantity  of  large 
guttiferous  trees  may  still  be  found  yielding  a  product  <>f  inferior  quality,  not  ex- 
ploited formerly.  These  have  only  commenced  to  be  exploited  within  the  last  twenty 
five  years,  as  the  better  sorts  became  more  and  more  rare,  and  the  demand  grew 
from  day  to  day.  "It  is  fortunate  that  only  the  full  grown  trees  contain  enough 
gutta  percha  to  repay  the  work  of  felling  and  wringing,  otherwise  the  complete 
extermination  of  the  gutta  forest  would  only  be  a  matter  of  a  year  or  so.  On  the 


330  GUTTA   PERCHA 

other  hand,  the  felling  of  all  the  trees  old  enough  to  bear  seed  works  to  the  same 
end  with  a  longer  limit." — Sherman,  loc.  cit.  Obach  gives  the  following  account  of 
how  the  latex  is  obtained  :— In  order  to  get  at  the  latex,  it  is  therefore  neceo; in- 
to cut  through  the  bark  and  cause  it  to  exude.  The  practice  of  the  Malay  gctah- 
collector  is  invariably  to  fell  the  tree,  chop  off  the  branches,  and  ring  the  bsirk 
at  distances  of  12  to  18  inches  all  along  the  trunk.  The  milky  sap  soon  fills  the 
grooves  cut  into  the  bark,  and  with  the  better  kinds  of  trees  quickly  coagulates ; 
it  is  then  scraped  off  with  the  point  of  a  knife.  In  the  case  of  inferior  trues, 
the  latex  requires  a  much  longer  time  to  curdle,  and  has  to  be  collected  in  a 
receptacle  of  some  sort,  a  cocoa-nut  shell  or  the  spathe  of  a  palm,  for  instance, 
placed  under  the  trunk.  The  latex  is  then  taken  to  the  huts  and  gently  boiled 
either  by  itself  or  with  the  addition  of  water.  The  material  obtained  without 
water  is  called  a  goolie,  the  other  a  gutta ;  but  the  two  kinds  are  mostly  mixed 
together.  The  goolie  is  more  compact  than  the  gutta,  and  it  has  a  dough-like 
smell.  For  felling  the  trees  the  Malays  use  a  small  axe,  called  a  billiong  ;  it 
has  a  chisel-like  edge.  The  gutta  percha  which  Leon  Brasse  and  Seligmann  Lui 
saw  collected  undergoes  a  preparation  which  varies  with  the  species.  The  milky 
juices — such  as  that  of  the  Payena — are  carried  to  the  hut  in  the  liquid  state, 
whilst  that  of  the  Dichopsis,  which  is  thicker,  is  of  necessity  mixed  with  woody 
fragments  as  soon  as  it  issues  from  the  tree.  On  the  way  the  juice  further  con- 
denses, the  operator  takes  out  the  largest  pieces  of  debris  by  hand,  and  throws  the 
mass  into  a  pot  filled  with  hot  water.  The  gutta  percha  softens  therein  and 
becomes  plastic,  and  is  easily  transformed  into  a  compact  mass.  Good  qualities 
do  not  stick  to  the  fingers.  The  plastic  mass  is  reduced  to  as  thin  and  flat  a  band 
as  possible,  and  the  remainder  of  the  ligneous  corpuscles,  however  thin,  are  removed 
from  the  surface  of  the  band  by  hot  water,  or  by  rubbing  with  the  hand,  or  in  any 
other  way.  Generally,  the  same  operation  is  repeated  a  second  time ;  the  gutta, 
again  softened,  is  kneaded,  drawn  into  sheets,  washed  and  rubbed,  and  finally  rolled 
on  itself  into  lumps  or  pieces  of  different  size  and  shape.  Hence  the  foliated 
appearance  seen  in  the  body  of  the  cakes.  Twice  purified  gutta  percha  is  distin- 
guished by  its  superior  quality  from  once  purified.  But  as  put  on  the  market  it  is 
far  from  being  pure,  and  is  still  mixed  with  an  enormous  quantity  of  woody 
particles,  which  cannot  be  removed  without  undergoing  various  tedious  operations 
described  in  the  sequel.  In  Sumatra,  far  from  purifying  the  gutta  percha  previ- 
ously, crushed  bark  is  added  to  it  by  the  handful.  Gutta  percha  changes  colour  in 
the  course  of  these  operations.  As  it  issues  from  the  tree  it  is  always  white. 
Boiling  with  the  debris  of  the  bark  and  the  wood  causes  it  to  contract  a  deeper 
tint  and  diversely  coloured  hues  ;  and  if  the  gutta  of  the  Payena  takes  a  yellowish 
tint  in  contact  with  air,  the  colour  of  the  Dichopsis  is  entirely  due  to  the  colouring 
matter  absorbed  on  boiling.  Certain  writers  assert  that  collectors  boil  the  gutta 
percha  with  a  tinctorial  substance,  to  impart  to  it  the  colour  sought  after  in 
commerce.  There  is  no  need  for  such  trouble,  at  least  in  Sumatra,  where  the 
gutta  is  red,  because  it  is  not  possible  for  it  to  be  otherwise  when  it  comes  from  a 
Dichopsis,  as  it  is  always  mixed  with  fragments  of  bark  sufficient  to  colour  it. 
It  is  rare  that  such  gutta  percha  is  put  on  the  market  pure.  Balam-tembaga,  balam 
bringin  consist  for  the  greater  part  of  a  mixture  of  several  kinds.  This  mixing  is 
so  general  that  it  is  altogether  impossible  to  procure  pure  samples  free  from  ad- 
mixture from  the  native  merchant.  The  most  successful  mixtures  often  bear  the 
name  of  balam-tembaga,  even  when  the  juice  of  Dichopsis  oblongifolium  is  alto- 
gether absent.  Every  mixture  regarded  as  a  falsification,  if  we  look  at  the  matter 
from  a  purely  scientific  point  of  view,  cannot  be  regarded  as  such  unless  done  on 
purpose  and  with  a  view  to  a  premeditated  fraud.  The  gutta  percha  searchers  who 
have  got  a  certain  quantity  of  superior  quality  balam  soon  see  that  they  have  not 
enough  to  sell  it  profitably.  They  go  in  quest  of  a  tree  capable  of  yielding  a 
substance  of  the  same  kind,  and,  as  the  search  would  take  too  much  time,  they 
have  recourse  to  the  first  tree  they  meet,  until  they  have  got  as  much  as  they  want. 
Returned  into  their  kampong,  they  have  in  hand  several  kinds  of  gum  resins,  but 


METHODS  OF  COLLECTION  331 

to*,  little  of  each  kind  to  sell  it  separately  :  it  is  thru  they  make  tin-  mixture.- 
ahvady  described.  Kx]H-rience  tells  the  kinds  which  would  sjM)il  the  mixture,  and 
they  take  good  care  not  to  us,-  them  to  their  own  detriment. 

} '/,  / ,/  ,,t'  ,/nffn  jM-rr/Ki,  </>:-t  ,,t'  t'roin  a  Dichojuit. — According  to 

Etarck's  Calculations,  •_'•"><>  gr  ilmiit   ^  ll>.)  of   completely  purified    gum    is   tlit; 

amount  produced  l.y  a  /;/<7/<y<s/'x  ,,',/,,„<//' t',,// ,t ,,t  ..|  •  '>.">  |i-.-t  in  height,  \sitli  trunk 
1' 1  indies  in  circumference  at  a  man's  height,  whilst  a  tive  of  the  same  species  of 
only  16  inches  in  circumference  only  yielded  160  grammes  (about  5  oz.).  J5ut 
a  DfehoptU  of  1C)  inches  in  circumference  is  far  from  l.i-ing  in  the  adult  BfajgQ  :  itl 
circumference  would  have  to  be  doubled  before  it  would  be  of  age  to  bear  flowers 
and  fruit.  Now  a  tree  of  16  inches  i.s  very  rare  in  our  days.  However  that  may 
l»e,  it  may  lx?  taken  for  granted  that  a  Di<'l< 'y/x/x  of  twenty-six  years  of  age  yields 
300  grammes  (rather  over  10  oz.).  The  figures  given  by  Serrulaz,  which 
certainly  refer  to  the  /W/<//Ws,  are  very  approximate  to  the  above.  According  to 
that  writer,  a  four-year-old  tree  does  not  as  yet  yield  latex;  from  fifteen  to  twenty 
years  it  gives  90  to  110  grammes  (say  3  to  4  oz.).  At  thirty  it  may  yield  250  to 
•_'»;<>  gamines  (say  8|  to  9  oz.).  When  fully  developed,  its  production  might 
amount  to  500  grammes  (say  17J  oz.)  (exceptional  maximum  reached). 
Finally,  in  declining  old  age  its  production  is  reduced  to  nil. 

It  has  often  been  asked  if  there  were  any  absolute  necessity  for  felling  the  trees, 
and  if  it  would  not  suffice  to  incise  the  trunk  to  obtain  gutta  j»ercha.  The  native 
Malay  knows  very  well  that  this  more  rational  method,  applied  to  the  same 
for  a  determined  series  of  years,  will  in  that  way  yield  each  time  a  certain  quantity 
of  gutta  j>ercha ;  but  it  is  difficult  to  wrest  from  him  the  idea  that  this  method 
would  considerably  diminish  the  annual  production,  and  would  give  but  a  very 
insufficient  remuneration  for  his  efforts.  In  his  work  of  destruction  he  thinks  of 
nothing  but  his  immediate  tangible  interests,  without  the  least  care  for  the  future. 
Nothing  appeals  to  him  but  the  greater  or  less  degree  of  trouble  inherent  to  his 
work.  If  climbing  the  tree  and  incising  the  bark  appeared  to  him  more  easy 
than  felling,  then  he  would  incise,  as  he  does  with  the  indiarubber  tree.  As 
to  the  gutta,  he  is  convinced  that  felling  will  give  him  less  trouble  than  incision, 
and  he  does  not  see  why  he  should  incise  for  a  production  which  he  regards  as 
insignificant.  Yet  incision  without  felling  yields  at  least  one-half,  if  not  two-thirds, 
of  the  amount  yielded  by  felling ;  for  do  not  let  us  forget  that  by  felling  only  half 
of  the  available  gutta  percha  is  obtained,  since  the  substance  is  only  extracted  frcm 
that  part  of  the  tree  which  does  not  repose  on  the  ground.  Moreover,  a  partial 
flow  of  the  milky  juice  causes  no  injury  to  the  vegetative  vigour  of  the  tree,  and 
IJmvk  tapped  four  trees  of  the  same  species,  and  it  did  not  even  hinder  them  from 
flowering  six  months  afterwards, — a  sure  proof  of  the  harmless  nature  of  upright 
tapping.  The  incision  of  living  trees  is  therefore  not  only  possible  but  more 
advantageous,  and  yields  a  continuous  supply  without  drying  up  the  sources  of  the 
precious  hydrocarbide  so  rapidly  as  felling. 

Extraction  of  gutta  in  Borneo. — Leys,  Consul-General  of  the  British  possessions 
in  North  Borneo,  describes  the  process  of  collection  followed  in  the  north-west  of 
that  island,  i.e.  in  Sarawak,  in  Portianak,  Labuan,  etc.  etc.  The  different  sorts 
are  the  products  of  different  trees,  but  the  pure  red  gutta  jiercha  of  Borneo  is  the 
product  of  a  Dichopsis.  Other  sjiecies  yield  inferior  quality  latex,  which  are 
mixed  l»y  the  natives  with  good  gutta  percha.  The  red  quality  is  obtained  from 
trees  of  100  to  150  feet,  which  grow  in  old  jungles  on  the  hill  sides.  Tin-  raw 
product  is  extracted  as  follows  :  When  the  >earehers  have  found  a  tree  ..Id  enough 
to  be  profitably  exploited,  /.,.  having  a  circumference  of  1  •_'  indie-  at  a  m 
height,  they  fell  it,  cut  off  the  top,  and  ring  the  hark  at  distances  ,,f  aUut  a  foot. 
The  latex  Hows  for  two  or  three  days;  it  is  collected  in  any  kind  of  a  M.— <  I. 
such  as  leaves  or  a  split  cocoamit  :  it  is  then  1. oiled  in  a  i»ot  for  half  an  hour 
with  a  small  quantity  of  water,  which  hinders  it  from  hardening  on  the  outside 
later  on  by  exposure  to  the  air,  and  thus  be  so  far  deteriorated  as  to  be  of 
no  commercial  value.  It  is  difficult  to  estimate  the  yield  of  a  tree,  because  the 


332  GUTTA  PERCHA 

quantity  varies  with  its  size  and  the  season;  the  flow  of  the  latex  reaches  its 
maximum  when  the  foliage  is  fully  developed ;  but  the  yield  varies  greatly  with 
the  age.  A  small  tree  generally  yields  33  lb.,  whilst  a  larger  tree  may  yield  as 
much  as  100  lb.  Another  Dichopsis1  yields  a  white  inferior  gum  resin.  It  is 
smaller,  and  only  attains  a  height  of  50  to  60  feet.  Its  foliage  differs  slightly, 
and  barely  produces  but  12  to  13  kilos.  (26  J  to  28J  lb.)  of  gutta  percha.2 

Dr.  Sherman,  jun.,  of  the  U.S.A.  Government  Laboratories,  Manilla,  gives  the 
following  description  of  both  the  mechanical  and  the  chemical  process  of  extracting 
gutta  percha  from  bark  and  leaves : — (1)  Mechanical :  The  leaf  is  ground  to  a 
powder  and  then  treated  in  hot  water  so  that  the  gutta  percha  is  gradually 
worked  into  a  compact  mass,  while  the  pulp  of  the  leaf  is  washed  away.  Up  to  the 
present  (1903). the  process  has  not  been  perfected,  for  though  the  gutta  percha 
contained  is  of  good  quality,  the  percentage  of  recovery  is  smaller  than  it  should  be. 
The  largest  factory  of  this  kind  is  being  erected  near  Singapore,  and  it  proposes  to 
use  the  leaves  from  a  plantation  of  100,000  trees  on  the  island  of  Rhio,  some  five 
hours  from  Singapore.  (2)  The  chemical  process  is  carried  out  in  the  same  lines 
as  the  mechanical  one  so  far  as  the  grinding  of  the  leaves  is  concerned.  The 
powder  is  then  extracted  with  solvents,  and  the  dissolved  gutta  percha  recovered 
either  through  precipitation  or  through  evaporation  of  the  solvent.  The  details  of 
the  process,  as  well  as  the  solvents  used,  are  kept  secret,  and  no  patents  for  this  or 
the  mechanical  process  have  been  taken  out  (sic).  The  largest  factory  producing 
gutta  percha  for  the  market  is  located  at  Sarawak,  North  Borneo,  and  is  very 
advantageously  situated  as  regards  securing  leaves  from  the  surrounding  gutta 
percha  forests.  It  has  been  claimed,  however,  that  the  factory  defeated  its  avowed 
object  of  preventing  the  destruction  of  the  trees,  for  the  native  collectors  employed 
would  never  risk  their  lives  trying  to  collect  leaves  from  forest  trees  over  100  feet 
high  when  they  could  gather  them  much  easier  by  felling  the  tree  and  collecting  a 
goodly  amount  of  gutta  percha  in  addition.  It  thus  appears  that  the  supply  of 
leaves  must  come  from  a  plantation  where  supervision  can  be  exercised.  The  plan 
of  felling  the  gutta  percha  trees  of  the  forest  and  securing  all  of  the  material  from 
the  bark  and  leaves  is  worthy  of  serious  consideration.  In  the  first  place,  the  trees 
are  surely  doomed  as  long  as  present  conditions  obtain.  If  the  native  can  sell  the 
entire  bark  and  leaves  for  more  than  he  could  get  for  the  gutta  percha  which  he 
could  extract,  he  will  be  tempted  to  bring  them  in.  A  second  inducement  for  this 
method  is  the  fact  that  many  gutta  percha  trees  cut  dowrn  even  years  previously 
have  still  much  perfectly  sound  gutta  percha  in  the  rotting  bark  which  could  also 
be  secured.  The  process  of  recovering  the  substance  from  the  bark  is  practically 
the  same  as  from  the  leaves,  and  about  the  same  per  cent,  is  found  there  as  well. 
With  a  yield  of  10  to  15  times  the  present  amount  recovered  from  each  tree,  the 
gutta  percha  market  would  be  relieved  at  once  and  the  extermination  of  the  trees 
put  off  many  years,  long  enough  at  any  rate  to  allow  plantation  trees  to  take  their 
place. 

A  large  amount  of  work  has  been  done  in  this  laboratory  with  the  purpose  of 
finding  a  practical  method  for  extracting  the  gutta  percha  from  the  bark  and  leaves 
of  the  gutta  percha  trees.  The  process  calls  for  a  solvent  for  the  gutta  percha 
which  will  dissolve  it  easily,  can  be  recovered  and  again  used,  and  above  all  has  no 
deleterious  effects  on  the  substance. 

The  result  of  the  experimentation  led  to  a  modification  of  the  Obach 
hardening  method  for  gutta  percha.  The  process  consists  in  extracting  the  gutta 
percha  bark  and  leaves  by  means  of  hot  gasoline,  the  apparatus  being  provided 
with  reflux  condensers.  While  the  gutta  percha  has  entirely  dissolved,  the  solution 
is  allowed  to  stand  until  all  of  the  dirt  and  most  of  the  colouring  matter  has 
settled.  The  clear  supernatant  liquid  is  then  poured  off  and  cooled  to  10°  or  15°  F. 
below  freezing.  The  gutta,  with  a  small  amount  of  resin,  is  thereby  precipitated, 
and  can  be  filtered  off  through  cloth  bags  and  dried.  The  resulting  gutta  can  be 
further  purified  by  redissolving  in  distilled  gasoline  and  reprecipitating. 
1  D.  Macropliylla.  2  20  catties,  26£  lb.  per  tree.  These  yields  seem  abnormally  high  . 


METHODS  OF  COLLECTION  333 

The  filtrate  containing  the  dissolved  resins  is  redi-tillrd  and  the  recovered  gasoline 
MS.-.I  t'«.r  eiVecting  further  solution  of  gutta  i>ercha,  thu«  making  tin-  pro 

rolitillllolis. 

Tin-   gutta   so  Mvured,   ..11    bring  warmed,  ran  I,.-  piv^.-d  into  ,in\   drsiiv,|  f,,n,i 

t'..|-    exp.-rilll. 'Illation.        The    gutta     U>ed     ill     the    aboVO   CX|  M-rillU'llt  -    \\a-    N   prepared, 

ami  tin-  results  .if  tin-  phy-iral  and  rheinieal  tests  Allowed  it  to  IK;  unaHrrt.-d  l,\  the 
proceae  to  any  appre.-iaUe  extent.  A  year's  exposure  to  laboratory  fumes  has  not 
changed  tin-  sal. stance  in  any  way. 

It  is  to  IK-  noted  that  the  process  gives  practically  pure  gutta  and  not  gutta 
percha,  the  resins  remaining  dissolved  in  the  gasoline.  This  is  in  itself  a  great 
advantage,  as  the  gutta  could  be  used  directly  for  bringing  up  the  jKjrcentage  in 
interior  grades  of  gutta  percha,  and  so  make  them  suitable  for  cable  insulation. 
The  roimiiereial  value  of  this  gutta  has  not  been  determined,  but  should  be  rated 
at  about  $600  Mexican  per  picul,  judging  from  the  price  of  the  best  gutta  percha. 
In  this  way  three  piculs  of  Philippine  gutta  percha  at  £:M<)  Mexican  will  produce 
1  picul  of  pure  gutta  valued  at  $600  Mexican,  or  a  gain  of  $390  for  every  .'»  piruls 
of  gutta  percha  (or  the  equivalent  in  bark  and  leaves)  handled. 

Extraction  of  gutta  in  t/ie  Philippines. — Sherman,  from  whom  we  have  already 
•  I noted,  gives  the  following  interesting  account: — The  method,  which  is  still  in 
vogue  from  the  westernmost  j>art  of  Sumatra  to  the  easternmost  point  of  Mindanao, 
is,  with  various  minor  modifications,  practically  as  follows : — The  tree  is  first  cut 
down  and  the  larger  branches  at  once  lopped  off,  the  collectors  say,  to  prevent  the 
gutta  percha  milk  from  flowing  back  into  the  small  branches  and  leaves.  As  has 
I >een  previously  stated,  the  milk  or  latex  is  contained  in  the  inner  layers  of  the 
bark  and  leaves,  in  small  capillary  tubes  or  ducts.  (See  Fig.  14.)  To  open  these 
so  as  to  permit  the  maximum  amount  of  the  milk  to  escape,  the  natives  cut  rings 
in  the  bark  about  2  feet  apart  along  the  entire  length  of  the  trunk.  The  milk 
as  it  flows  out  is  collected  in  gourds,  cocoanut  sheila,  large  leaves,  or  in  some 
districts  in  the  chopped-up  bark  itself,  which  is  left  adhering  to  the  tree  for  the 
pui'i>ose  of  acting  as  a  sort  of  sponge.  After  one  or  two  hours,  when  the  milk 
has  ceased  to  flow,  the  contents  of  the  receptacles  are  united  and  boiled  over  a  fire 
for  the  purpose  of  finishing  the  partial  coagulation.  The  warm,  soft  mass  is  then 
worked  with  cold  water  until  a  considerable  amount  of  the  liquid  is  mechanically 
enclosed.  To  further  increase  the  weight,  chopped  bark,  stones,  etc.,  are  added, 
and  the  whole  mass  worked  into  the  required  shape  with  most  of  the  dirt  on  the 
inside. 

The  gutta  percha  gathered  in  this  way  well  repays  the  amount  of  work  ex- 
pended. The  two  vital  defects  of  the  method  are: — (1)  The  method  is  very 
\\-isteful,  the  yield  from  each  tree  being  a  small  proportion  to  the  total  amount. 
What  this  per  cent,  is  has  been  investigated  by  scientists  with  the  result  that  the 
figures  differ  widely.  Remembering  that  the  gutta  j>ercha  milk  is  contained  in 
capillary  ducts  and  tubes,  it  will  be  seen  that  a  considerable  amount  cannot  flow 
out  on  account  of  capillary  attraction,  no  matter  how  much  cutting  is  done.  It  very 
seldom  happens  also  that  a  tree  falls  in  such  a  way  that  all  its  trunk  is  exposed  so 
as  to  admit  of  ringing  on  all  sides.  As  a  general  thing,  from  one-third  to  one-half 
of  it  is  inaccessible  to  the  process  of  ringing,  and  all  the  milk  within  this  portion  is 
consequently  lost.  Even  the  larger  limbs  are  not  deemed  worth  ringing,  and  con- 
sequently all  the  milk  in  them  and  in  the  leaves  also  goes  to  waste ;  to  this  must 
be  added  the  considerable  quantity  spilled  on  the  ground  through  carelessness  and 
lack  of  enough  receptacles  for  every  cut  or  bruise  from  which  the  milk  flows. 
The  method  employed  to  find  what  percentage  of  gutta  percha  has  been  removed 
from  a  tree  by  the  native  collectors,  was  to  determine  the  per  cent,  of  gutta  percha 
remaining  in  a  given  area  of  the  bark,  multiplying  this  by  the  total  bark  area  of 
the  tree,  and  adding  15  per  cent,  of  this  amount  for  that  contained  in  the  bark 
of  the  branches  and  in  the  leaves. 

M -irk' ting. — Having  been  collected  and  put  in  marketable  shape,  the  gutta 
percha  is  carried  in  baskets  on  the  backs  of  the  collectors  to  the  nearest  waterway, 


334  GUTTA   PERCHA 

and  thence  by  boat  to  the  most  accessible  town,  where,  applying  the  description  to 
the  Philippines,  it  is  exchanged  for  barter  to  some  Moro,  Chinese,  or  Filipino 
merchant  (commerciante)  living  there  for  the  purpose  of  dealing  in  all  kinds  of 
native  products.  From  here  it  is  shipped  to  one  of  the  ports  doing  an  export  tra<l<- 
with  Borneo  and  Singapore.  The  entire  gutta  percha  trade  is  practically  in  1  la- 
hands  of  the  Chinese  in  the  latter  city,  and  they  guard  the  secrets  of  boiling,  work- 
ing over,  mixing,  adulterating,  and  colouring  the  gutta  percha  for  Euro] -can 
markets  most  zealously.  All  who  have  tried  to  investigate  their  methods  agree 
that  there  is  no  connection  between  the  various  grades  and  the  different  tree  species, 
and  that  pure  gutta  percha  from  the  species  Palaquium  gutta  is  no  longer  found 
on  the  market  unmixed  with  inferior  grades. 

Strangely  enough,  Sherman  was  unable  to  find  in  Singapore  any  statistics 
regarding  the  importation  of  Philippine  gutta  percha.  The  Chinese  dealers  denied 
receiving  any,  and  beyond  a  few  piculs  noted  in  the  annual  report  statistics  no 
mention  of  it  was  found  anywhere.  He  afterwards  ascertained  that  the  gutta 
percha  first  goes  to  Sandakan  and  Labuan,  in  British  North  Borneo,  and  is  there 
transhipped  to  Singapore,  entering  as  North  Borneo  gutta  percha. 

Unfortunately  the  amount  collected  for  exportation  cannot  be  given  with  any 
degree  of  accuracy,  as  the  export  statistics  include  gutta  percha  with  all  other 
gums.  It  is  known,  however,  that  the  amount  reaches  into  tens  of  thousands  of 
pounds. 

BALATA. — Finally,  Balata  is  obtained  by  condensation  of  the  milky  juice,  but 
in  order  to  extract  it  from  the  tree  it  is  not  sufficient,  as  in  the  case  of  indiarubber, 
to  make  a  few  incisions  in  the  bark.  The  liquid  is  thicker,  and  coagulates  so 
soon  that  the  incisions  would  become  obstructed  in  a  very  short  time.1  In  the 
beginning,  collectors  felled  the  trees  at  their  feet  (close  to  the  ground)  and  then 
raised  them  afterwards  on  to  supports,  so  as  to  allow  the  vessels  to  be  placed 
underneath  for  collecting  the  milk  as  it  ran  from  deep  cuts  barely  a  foot  apart. 
In  this  way  each  incision  gradually  allowed  the  milk  to  exude,  and  thus  be 
collected.  By  this  barbarous  method  a  tree  of  average  height  yielded  3  to  6 
kilos,  of  balata  (6J  to  13  lb.).  At  the  present  time,  portable  pi-esses  are 
used  in  which  the  bark  is  submitted  to  great  pressure.  A  press  yields  9  to  13 
litres  of  juice  hourly,  which  produces  2  to  3  kilos,  (say  4J  to  6J  lb.) 
of  dry  balata.  There  are  large  trees  encountered  towards  Maturin  which  yield 
by  this  process  several  quintaux  of  balata.  This  destructive  system  is  pursued 
at  the  present  time,  and  with  great  profits.  It  will  very  soon  destroy,  if  continued, 
all  the  balata  trees  of  Maturin,  where  they  are,  however,  very  numerous.  The 
Purvio  is  met  with  in  British  Guiana,  and  is  wrought  in  a  more  sensible  way, 
from  the  point  of  view  of  the  preservation  of  the  producing  tree.  Some  longitu- 
dinal incisions  are  made  on  the  trunk,  between  which  the  bark  is  removed,  but 
leaving  from  point  to  point  fibres  of  this  bark,  which  serve  as  points  of  support 
to  the  new  bark,  gradually  covering  that  which  was  torn  off.  The  best  process 
consists  in  removing,  and  allowing  to  remain,  rectangles  of  bark  of  equal  surface. 
The  bark  is  afterwards  pressed.  A  tree  of  average  size  gives  by  this  method  of 
collecting  about  2  lb.  of  balata,  but  the  process  may  be  repeated  indefinitely  by 
removing  annually  the  portions  of  the  bark  which  were  not  touched  the  preceding 
year.  The  quantity  of  milk  is  greater  during  the  rainy  season ;  the  coagulation 
is  also  slower  at  that  time.  The  native  collectors  say  the  extraction  gives  a 
better  yield  during  the  waxing  of  the  moon,  an  observation  or  prejudice  which 
guides  many  European  harvests.  The  milk  of  the  Purvio  is  reddish,  with  an 
astringent  taste.  It  is  collected  in  wooden  vessels.  Iron  vessels  impart  a 
blackish  colour,  which  diminishes  the  commercial  value  of  the  dry  product.  The 
balata  milk  is  sold  as  it  is,  fetching  about  one  dollar  per  gallon,  or  it  is  evaporated 

1  According  to  Obach,  it  was  formerly  the  custom  in  Jamaica  to  fell  the  trees  and  ring 
the  bark  as  in  the  case  of  true  gutta  trees  ;  but  this  method  has  been  abandoned,  and  the 
trunk  simply  tapped,  which  is  quite  practicable,  as  the  balata  milk  is  much  more  liquid  than 
that  of  the  gutta  percha  tree.  In  Surinam  the  trees  are  likewise  tapped. — TE. 


METHODS  OF  COLLECTION  335 


to  obtain  tin-  pinkish  or  <_rre\i>h  coloured  solid  l.al.it;i.  A  gallon  of  milk 
about  I  ll>.  of  dry  balata.  A  Mceder  of  average  skill  obtains  alxwt  4  gallons  and 
a  half,  and  a  very  successful  one  as  much  as  l<)  gallons  per  day  thus,  n-ali-in^ 
over  :\  ox.  (Obarln.  Ka«-|i  Lrnl!.i  percha  tree  thus  \ield-  al  —  .lute|\  ditl'.-ivnt 
Dualities  and  ijiiaiitit  ii-s,  according  to  >pn-irs,  agr,  and  LfeoL'raphical  and  climato 
logical  situation.  This  explains  tin-  apparent  rout  radict  ions  in  the  \\ritings  of 
Si-iTiila/.,  I'.ilivk,  and  BMUM6,  etc,  In  an\  CA86,  the  ((notion  of  (In-  deaill: 
!_Mitta  |Tivha  is  a  \ital  one,  \\hich  incessant  ly  and  acutely  occupies  public  attention, 
not  only  in  the  industrial  Imt  also  in  the  adininist  rat  i\  e  world. 

'/'//,  fii/min-  •  .i-ti-'i'-tinn  ,,f'  A»//vx,  etc.  —  From  this  j>oint  of  view,  a  research  of 
M.  .liingtleisi'h,  Professor  aw  Conservatoire  National  de*  Art*-'  .l/,'//»-/-x,  published 
in  the  I'm/I,  tin  de  la  Socie'te'  dy  encouragement  (Octol>er  1892,  p.  709)  is  of  hi- 
torical  interest.  The  memoir  commences  by  making  allusion  to  the  communication 
made  by  Dr.  Serrulaz  to  the  same  Society,  in  its  session  of  the  sth  April  1892, 
in  uiving  an  account  of  the  expeditions  with  which  he  was  entrusted,  in  Malaria, 
to  seek  the  plant  capable  of  yielding  the  best  gutta  percha.  Serrula/.  there,  for 
tin-  fust  time,  said  a  few  words  regarding  a  new  method  of  extracting  that 
substance  —  a  method  in  which  he  took  pleasure  in  ascribing  to  Professor  Jung- 
lleiseh,  although  he  had  himself  taken  an  important  part  in  it.  Jungll.-is.-li 
had  for  a  long  time  studied  the  proximate  principles  of  which  the  mixture  called 
gutta  pcn-ha  is  constituted.  With  the  assistance  of  one  of  his  students,  M. 
haiiMUM'au,  he  obtained  them  all  in  a  crystalline  state,  i.e.  under  a  form  which 
would  hardly  foretell  the  so  highly  accentuated  plasticity  of  the  mixture.  llo\\ 
ever,  the  invgular  composition  of  the  commercial  raw  material,  certain  ditl'ercnce< 
found  between  the  properties  of  the  principles  obtained  from  different  guttas, 
the  dread  of  not  being  able  to  reproduce  with  certainty  with  a  second  gutta  the 
results  obtained  from  the  first,  had  adjourned  the  publication  of  the  common 
results.  The  desire  of  pursuing  these  researches  upon  a  product  of  certain  origin 
had  necessarily  drawn  the  attention  of  M.  Jungfleisch  to  the  results  obtained  by 
the  French  exi>editions,  which  were  then  at  work  to  throw  light  on  the  question 
of  the  origin  of  gutta  percha,  and  in  particular  on  the  questions  dealt  with  by 
the  expeditions  of  Seligmann  Lui  and  Serrulaz.  Seligmann  explained  to  him 
all  the  difficulties  in  procuring,  even  in  small  quantity,  a  gutta  of  perfectly 
authentic  origin  from  a  well-defined  plant.  He  was  thus  glad  to  get  from 
Serrulaz  the  information  collected  by  him  during  his  first  expeditions.  Jung- 
tleiseh  had  hopes  of  resuming  his  researches  on  a  sample  of  gutta  i>ercha  of 
certain  origin,  and  so  bring  his  contingent  of  light  to  bear  on  so  obscure  a 
question  naturally,  but  rendered  more  so  by  those  interested.  Information 
as  to  gutta  plants  was  quite  vague  and  contradictory.  In  any  case  the  Malay 
method  of  working  was  essentially  a  method  of  laying  waste,  and  was  to  cause 
the  forests  to  disappear  in  the  near  future,  and  along  therewith  the  raw  material 
indispensable  to  the  electric  industry.  The  Malays  can  only  work  upon  fa 
of  twenty-eight  to  thirty  years  old,  or  upon  shoots  of  fourteen  to  fifteen  years, 
and  the  felling  of  a  thirty-year-old  tree  only  furnishes  them  with  but  205  grammes 
(say  9J  oz.)  of  raw  gutta,  often  charged  with  nearly  half  its  weight  of  foreign 
matter  of  no  use,  and  often  injurious  for  manufacturing  puqxiscs.  Operating 
with  more  care  and  patience  than  the  Malays,  Serrulaz  was  only  able  to  extract 
from  a  thirty-year-old  tree  220  grammes  (say  8  oz.)  of  purer  gutta,  it  is 
true,  and  he  has  seen  a  tree  of  1*20  metre  (say  4  feet)  in  diameter  operated  on 
which  only  gave  328  grammes  (say  11J  oz.)  of  raw  product. 

Such  primitive  and  poorly  productive  processes  are  peculiarly  astonishing  \\hen 
viewed  alongside  the  enormous  consumption.  In  1884,  for  example,  M.  N.  I'. 
Trevenen,  after  summing  up  the  quantities  of  good  and  bad  gutta  percha  exported 
from  the  Malay  ports,  got  a  total  of  52,067  piculs  (say  :>,  1  I  1.1  17  metric  tons), 
which,  according  to  the  preceding  data,  would  correspond  with  the  destruction 
of  more  than  12,000,000  of  thirty-year-old  guttiferous  trees.  All  these  trees  do 
not  yield  prime  quality  gutta  percha,  and  the  Malays  add  to  the  substance 


336  GUTTA   PERCHA 

collected  vegetable  and  even  mineral  matter  of  the  most  different  kinds.  Whilst 
the  Chinese  intermediary,  under  the  pretext  of  imparting  a  commercial  shape 
to  the  substance,  works  the  product  with  so  ihuch  skill  as  to  singularly  increase 
the  weight.  Again,  the  European  merchant  .purifies  the  goods  by  rebelling  tln-m, 
a  process  which  results  in  a  fresh  multiplication  of  cakes.  But,  granting  with 
Jungfleisch  the  coefficient  of  growth  which  these  operations  bring  about,  yet 
the  consumption  of  trees  is  still  enormous,  and  so  much  out  of  proportion  that 
the  precious  plant  is  bound  to  disappear  rapidly. 

The  production  thus  tends  to  diminish  whilst  the  demand  increases  daily, 
and  on  every  hand  the  great  European  States  are  driven  to  safeguard  such  an 
important  interest  by  seeking  a  remedy  for  the  evil  in  acclimatisation.  The 
possible  results  of  forest  culture  experiments  of  this  kind  undertaken  20,000 
kilometres  from  Europe,  on  a  necessarily  gigantic  scale  if  they  are  to  be  sufficient, 
have  already  been  discussed,  and  the  cause  of  the  poor  results  obtained  up  to 
now  is  well  understood. 

Discovery  of  gutta  percha  in  the  leaves  of  the  tree. — These  difficulties  led 
Jungfleisch  to  doubt  the  efficacy  of  the  method,  and  to  try  if  the  question  could 
not  be  regarded  from  another  point  of  view.  The  examination  by  M.  Serrulaz 
of  small  samples  in  1888  demonstrated  the  presence  of  gutta  in  all  parts  of  the 
plant.  The  organs  other  than  the  trunk  contained  gutta  in  quantities  which 
was  thought  to  be  very  superior  to  that  which  the  trunk  itself  yielded  in  such 
minimum  quantities  to  the  Malays.  May  not  the  coagulable  matter  of  the 
latex  accumulate  in  some  organ  of  the  plant  where  it  would  be  possible  to  seek 
it  by  more  delicate  methods  than  those  of  the  Malays  1  If  perchance  these  organs 
were  those  which  may  be  separated  from  the  plant  without  compromising  its 
life,  the  question  would  have  made  a  great  advance.  The  unpublished  researches 
formerly  made,  in,  .fact,  left  no  room  for  doubting  the  possibility  of  finding 
solvents  for  extracting  the  gutta  from  the  organs  in  question,  and  to  extract 
it  alone.  Serrulaz,  then  about  to  start  for  Indo-China,  undertook  to  verify 
several  of  numerous  hypotheses  included  in  a  programme  of  experiments  performed 
in  this  line  of  ideas,  and  to  despatch  to  France  samples  collected  in  determinate 
conditions,  so  as  to  permit  of  the  necessary  experiments  being  executed.  Omitting 
all  preliminary  groping  in  the  dark,  and  suppositions  shown  to  be  incorrect, 
the  following  facts  have^been  established  : — 

The  solvents  by  which  gutta  percha  may  be  extracted  from  living  cells  are 
numerous.  Up  to  now  toluene  seems  the  best.  It  dissolves  the  three  principles 
of  which  the  resin  is  composed,  and  except  a  little  chlorophyll,  does  not  appreciably 
dissolve  the  other  substances  which  accompany  it.  Comparative  experiments 
were  made — 

(1)  On  air-dried  leaves,  i.e.  which  had  dried  by  exposure  to  oxidation  by  the 
air ;  (2)  on  fresh  leaves  brought  home  in  antiseptic  water,  then  dried  on  arrival ; 
(3)  on  dried  buds  stripped  of  leaves ;  (4)  on  two-year-old  wood,  dried  and  stripped 
of  leaves.  Contrary  to  expectation,  each  of  these  parts  of  the  plant  yielded  gutta 
in  almost  constant  but  always  considerable  quantities.  This  first  result  enabled 
a  favourable  issue  to  be  predicted.  He  immediately  fixed  his  attention  on  the 
part  of  the  plant  which  could  be  most  advantageously  treated.  By  detaching 
the  leaves  which  the  plant  constantly  renews,  and  which  it  would  not  itself 
be  slow  in  eliminating,  the  injury  to  the  development  of  the  plant  is  reduced 
to  a  minimum.  The  method  of  extraction,  moreover,  is  very  simple.  The 
pulverised  substance  is  exhausted  by  digestion  at  100°  C.  (212°  F.),  and  finally, 
by  displacement  with  a  solvent,  e.g.  toluene,  a  solution  of  gutta  percha  is  obtained, 
coloured  green  by  a  little  chlorophyll.  The  direct  evaporation  of  the  solvent 
not  being  practicable  without  injuring  the  product,  it  is  distilled  off  in  a  current 
of  low-pressure  steam,  i.e.  at  100°  C.  (212°  F.)  at  the  maximum.  One  volume 
of  water  vaporised  in  this  way  carries  over  four  volumes  of  toluene.  The  gutta 
percha  remains.  The  whole  of  the  toluene  is  expelled  by  prolonging  the  action 
of  steam  on  the  agitated  mass  kept  at  100°  C.  (212°  F.).  The  yields  were  above 


METHODS  OF  COLLECTION 


all    expectations,    ami    ..M-illate,|    Letueen    «.»  and     1<»A    JH-I-    (•••ill  iinii    to    tin- 

part-  nl'  the  plant   treated,  M  shown  in  tin-  follow  in::  Table: — 

TABLK    XCII.       PBRODVTAOI  OF  QUTTA  PlBOHA  BXTEACTXD  ntOM  TK    V\ 
ORGANS  OF  THE  TREK  r^  T..IMM.     (JuNOi 


Quantity  in 

Organ  of  Plant. 

<:  11  tu  Percha 
extracted  in 

Pmoitag   «; 
Gun 

I.I.UIKII'  t. 

extracted. 

2000 

Old  wood. 

200 

10 

2000 

... 

183 

9-15 

1000 

Dry  hud  s. 

102 

10-20 

2000 

... 

211 

10-50 

2000 

Dry  leaves. 

204 

10*09 

500 

Incompletely  dried  leaves. 

453 

9-06 

200 

Leaves  received  in  water. 

21 

10-05 

200 

... 

18 

<J 

Hut  might  not  these  high  yields  be  due  to  admixture  of  the  gutta  with 
table  principle  extracted  by  the  solvent1?  The  ^rerni-h  appearance  of  the 
product  would  appear  to  give  force  to  this  objection,  Malay  gutta  jieivha  bein^  red. 
In  reality,  gutta  percha,  almost  naturally  colourless,  is  coloured,  in  the  tir>t 
case,  by  traces  of  chlorophyll,  which  may  be  removed  by  appropriate  x,,|vent>.  and, 
in  the  second,  by  the  debris  of  bark  and  by  peculiar  vegetable  principles,  from 
which  the  substance,  extracted  by  solvents,  is  altogether  free.  The  capital  {loint  is, 
that  all  competent  persons,  merchants  or  manufacturers,  who  have  examined  the 
gutta  percha  yielded  by  the  new  process,  have  been  unanimous  in  recognising  it  as 
quite  superior,  and  to  liken  it  to  the  best  sorts  which  commerce  no  longer  supplio 
to  industry,  to  those  of  which  the  electrical  trade  regret  more  and  more  tin- 
increasing  rarity.  It  is  evident  that  more  important  quantities  should  be  made, 
so  that  the  research  be  followed  under  conditions  adapted  to  decide  upon  certain 
particular  points.  But  the  use  of  solvents  will  lend  itself,  if  used  judiciously,  not 
only  to  the  extraction  of  gutta  percha,  but  also  to  its  industrial  treatment,  and 
even  to  its  purification.  M.  Jungfleisch  placed  before  the  members  of  the  Society  a 
series  of  samples  obtained  by  the  solvent  process.  Contrary  to  what  might  have 
been  feared  from  the  extreme  tendency  to  oxidation  of  gutta  carbide,  the  lea\e-. 
although  they  came  largely  exposed  to  the  action  of  renewed  air,  yielded  a  product 
of  very  good  quality.  We  can  therefore  now  imagine  an  exploitation  of  the 
Isonandra  which  survive  in  Malasia,  based  on  the  harvesting  of  the  leaves,  on  the 
importation  into  Europe  of  dried  leaves,  and  their  treatment  with  solvents.  The 
very  social  character  of  these  leaves  would  protect  manufacturers  from  any 
adulteration,  and  would  ensure  to  them  the  production  of  an  excellent  quality 
gutta.  Moreover,  if  it  were  a  question  of  producing  leaves  or  thin  branches,  the 
proximity  of  the  harvest  would  encourage  the  cultivators  of  the  extreme  East  to 
sacrifices  the  remuneration  for  which  would  not  be  delayed.  Under  these  condi- 
tions, it  is  justifiable  to  hope  much  more  from  private  initiative  than  from  the 
perseverance  and  foresight,  in  reality  very  great,  which  were  demanded  of  European 
States.  In  the  meantime  we  may  hope  to  see  the  actual  method  of  exploitation 
more  or  less  quickly  stopped.  The  Malays  will  sell  leaves  as  easy  to  collect  a- 
the  gutta  is  difficult  to  extract.  Thus  a  thirty-year-old  tree,  like  those  taken 
as  examples,  bears,  according  to  observations  made  by  M.  Serrulaz,  from  25 
to  30  kilos,  (say  55  to  66  Ib.)  of  green  leaves,  say  about  11  kilos,  (say 
24  Ib.)  of  dry  leaves,  which  would  yield  by  the  new  method  1000  to  1100 
grammes  (say  2J  to  2J  Ib.)  of  gutta,  whilst  the  fallen  tree  would  yield  at  the 
most  365  grammes  (say  13  oz.).  Moreover,  in  the  Malay  method  there  is  left 
with  the  leaves  and  small  branches,  on  the  soil  of  the  forest,  a  quantity  of  gutta 
22 


338  GUTTA   PERCHA 

equal  to  several  times  that  collected  from  the  trunk.  The  Malays  will  understand 
soon  enough,  without  doubt,  that  the  collection  of  the  leaves  practised  in  several 
seasons  of  the  year  ought  to  bring  them  in  much  more  than  the  felling — alw;i\  > 
laborious  work — of  large-sized  trees.  To  continue  the  same  example,  it  will  suffice 
for  a  thirty-year-old  tree  to  give  them  each  year  7  kilos,  (say  15  J  Ib.)  of 
fresh  leaves,  which  appears  little,  to  bring  them  in  as  much  continuously  as  its 
wholesale  destruction  will  do  once.  Trees  of  all  ages  and  all  sizes,  now  of  no 
immediate  use,  would,  moreover,  be  capable  of  profitable  exploitation.  The  com- 
plete transformation  of  the  actual  method  of  obtaining  gutta  percha  seems  therefore 
capable  of  shortly  ensuring  the  supply  of  this  interesting  substance  to  European 
industry.  It  leads  us  to  hope,  moreover,  that  the  future  will  be  provided  for  by 
the  private  initiative  of  planters — an  initiative  to  which  we  seem  justified  in 
promising  very  quick  returns. 

Summary  of  solvent  processes  for  extracting  gutta  from  leaves — 1.  Rigole's 
CS2  process  (British  Patent,  4252 ;  3rd  March  1892. — This  apparatus  resembles 
Dreschel's  form  of  Payen's  percolator.  Pounded  leaves  are  put  into  an  upper  vessel 
A,  communicating  by  pipe  a  with  an  inferior  vessel  JB,  in  which  CS2  is  boiled,  by  heat 
of  a  water  bath  D ;  the  vapours,  which  pass  through  a,  are  condensed  in  C  (the 
top  part  of  A\  and  flow  back,  charged  with  gutta,  into  the  boiler  B.  After 
exhaustion  of  the  leaves,  steam  is  passed  into  A,  and  the  solution  in  B  is  distilled 
off  into  a  condenser.  The  gutta  percha  remains  in  the  boiler,  floating  on  the 
water  condensed  from  the  steam.  2.  Serrulaz's  toluene  pi*ocess  uses  a  jacketed 
digester,  with  agitator  A ;  runs  toluene  into  upper  vessel  B,  heated  by  external 
steam,  and  then  suddenly  discharges  hot  toluene  on  leaves  by  syphon.  When 
solvent  has  done  its  work  it  is  drawn  off  into  retort,  from  which  it  is  distilled 
(British  Patent,  11,166;  14th  June  1892);  or  the  gutta  may  be  precipitated  by 
acetone  (British  Patent,  654  ;  9th  Jan.  1896).  3.  In  Ramsay's  process  toluene  as  a 
solvent  is  replaced  by  rosin  oil  (British  Patent,  17,936;  30th  July  1897.  Patent 
lapsed ;  non-payment  of  first  renewal  fee).  4.  Obach  takes  advantage  of  solubility 
of  gutta  in  boiling  light  petroleum  to  re-precipitate  it  by  cooling  below  60°  F.  His 
plant  differs  in  no  essential  point  from  ordinary  oil  extraction  plant.  He  uses  a 
battery  of  two  extractors,  and  works  them  alternately  (British  Patent,  19,046; 
28th  Aug.  1896).  The  density  of  gutta  percha  from  leaves  with  |  =  5-19  is  0-9625 
(Obach).  Extraction  by  solvents  brings  injurious  matter  in  its  train  and  thus 
impairs  durability  of  gutta,  especially  its  resistance  to  air  and  light,  and  seems 
likely  to  be  abandoned  in  favour  of  mechanical  extraction. 


CHAPTER  IV 

CLASSIFICATION  OF  THE  DIFFERENT  SPECIES  OF  COMMERCIAL 

GUTTA    I 'KUCHA 

IT  is  more  esi>ecially  in  this  section  that  recourse  has  to  be  made  to  the  interesting 
v>. >rk  of  L.  Brasse.     Understanding  how  difficult  it  is  in  tin-  present  state  of  our 
knowledge  to  proceed  in  a  really  scientific  manner,  persuaded  moreover  that   tin 
superannuated    terms  of  Macassar,  Singapore,  Java,  Sumatra,  and   Itorneo  gutta 
convey  absolutely  nothing  to  the   mind,  and  that   they   an-    more    apt    to   lead 
astray  than  to  enlighten  the  opinion  of  any  one  who  wishes  to  get  an  idea  of  the 
value  of  a  gutta  percha  from  these  denominations,  Brasse  takes  each  of  th 
and  studio  its  probable  origin,  the  form  under  which  it  comes  en  the   international 
markets,  examines  its  appearance,  the  section,  the  nature  and  amount  of  for- 
matter which   it  contains,   its   industrial  properties,   such  as  it-  '-ness,  its 
hardness,  its  greater  or  less  facility  of  cooling,  the  quality  of  the  thread  obtained. 
Again,  he  determines  the  ratio  of  the  gutta  to  the  resin  in  each  secies  examined. 
and    finally   its   specific  resistance   in   megohms-centimetres.     The  i>ercentage   of 
impurities  refers  in  his  work  to  the  industrial  washing. 

Ratio  ofyutta  to  resin. — He  determined  the  ratio  of  the  gutta  percha  to  the 
resins  in  the  following  way  : — Taking  about  5  grammes  which  had  been  industrially 
washed,  he  dissolved  them  in  benzine  on  the  water  bath,  so  as  to  get  a  solution  «-t 
200  c.c.  He  drew  off  50  c.c.  after  filtration,  and  poured  them  in  drop  by  drop  into  100 
c.c.  of  boiling  absolute  alcohol.  The  pure  gutta  is  precipitated,  whilst  the  resinou> 
substances  (albane  and  fluavile)  remain  in  solution.  He  filters  through  tared 
filters,  washes  with  absolute  alcohol,  and  dries  at  110°  C.  (230°  F.)  in  a  current  of 
dry  carbonic  acid,  and  he  thus  obtains  the  weight  of  pure  yutta.  Another  50  c.c.  of 
the  li.jiiid  is  evaporated  and  dried  at  110°  C.  (230°  F.)  in  a  current  of  dry  carbonic 
acid,  and  the  difference  between  the  two  weighings  gives  the  weight  of  the  resinous 
substances.  The  specific  resistance  is  calculated  from  a  resistance  test  made  on  a  \\  iiv 
insulated  with  the  gutta  percha  to  be  tested.  This  work  done  on  the  whole  seri«- 
of  known  varieties  is  a  model  of  its  kind ;  and  if  it  be  here  condensed  into  one  Table 
it  is  not  in  order  to  assume  the  paternity,  but  rather  to  facilitate  for  the  reader 
the  rapid  understanding  of  the  work,  and  to  enable  him  by  simple  insj>ectiou  of  the 
Table  to  make  any  comparative  researches  which  may  be  necessary.  Brasse  had 
no  intention  of  giving  an  idea  of  the  constitution  of  the  gutta  pereha  market. 
Many  sortings  of  the  commercial  varieties  were  necessary  before  he  could  reunite 
thesr  types.  The  information  as  to  the  origin  was  furnished  to  him  by  impor 
well  versed  in  gutta  percha,  and  by  Singapore  merchants.  All  types  which,  though 
constituting  a  homogeneous  whole,  yet  in  virtue  of  all  their  physical  and  chemical 
characters,  have  given  rise  to  divergences  of  appreciation  by  expert-,  have  been 
eliminated.  So  also  certain  well-known  species,  but  which,  by  the  want  of  con- 
stancy in  their  results,  appeared  to  be  species  liable  to  variation  rather  than  \\ell 
defined  types,  have  been  rejected.  Only  one  of  these  determinations,  so  as  to  well 
show  in  it  this  very  elastic  character,  has  been  included.  These  are  the  two  sorts, 
Sarapong  or  Souni.  Care  has  been  taken  not  to  mention  those  numerous 
anomalous  mixtures  daily  put  on  the  market,  the  work  of  Chinese  intermediaries. 
any  more  than  the  kinds  called  reloiled,  of  altogether  inferior  quality,  which 

889 


340  GUTTA   PERCHA 

originate  most  often  in  the  bottoms  of  cellars  and  in  the  bottoms  of  the  holds  of 
ships.  It  is  impossible  to  buy  from  an  importer  a  lot  of  authenticated  origin. 
The  lots  must  be  bought  as  they  come,  i.e.  as  the  Singapore  or  Macassar  merchant 
constitutes  them.  The  lots  marked  by  an  assemblage  of  letters,  which  vary  with 
the  firms,  are  made  solely  according  to  their  mechanical  properties.  This  occasions, 
after  each  delivery,  surprises  which  are  often  very  disagreeable.  Some  species 
arrive  ordinarily,  with  a  certain  specific  resistance,  and  here  is  a  fresh  consignment 
under  the  same  mark,  possessing  a  specific  resistance  ten  times  greater.  It  very 
simply  happens  that  one  of  the  kinds  generally  employed  in  making  up  the  lot 
happens  to  be  wanting,  and  has  been  replaced  by  another  sort  which,  at  first  sight, 
seemed  to  present  the  same  properties.  If  that  be  a  matter  of  little  importance,  so 
far  as  the  ordinary  uses  to  which  gutta  percha  is  put  are  concerned,  where  cheap- 
ness is  more  important  than  durability,  it  is  not  so  in  the  case  of  electric  cables, 
especially  submarine  cables.  All  those  laid  have  a  rather  low  insulation,  and  their 
success  has  been  complete,  whilst  so  much  cannot  be  foretold  in  regard  to  the 
durability  of  species  showing  a  high  insulation,  since  we  want  experience  on  this 
subject,  and  the  little  that  we  do  know  does  not  enable  us  to  hope  for  anything 
very  good.  Now,  amongst  all  the  species  just  enumerated  in  the  order  of  their 
approximative  value  which  they  have  shown  in  practice — an  order  which  is  about 
that  of  the  specific  resistance — it  will  be  seen  that  the  Sumatra  species  do  not  shine 
in  the  first  rank,  and  consequently  the  best  species  of  that  isle  may  not  indeed  be 
the  best  species  to  propagate.  If,  therefore,  we  almost  know  the  guttiferous  trees 
of  Sumatra  and  the  western  coast  of  the  Malay  Peninsula,  yet  we  are  still  very 
ignorant  of  the  sources  of  the  eastern  coast  of  Malacca  and  those  of  Borneo.  Now 
the  gutta  percha  of  Sumatra  has  never  been  regarded  as  the  best  sort,  and  the 
superiority  has  always  been  accorded  to  the  kinds  called  "  Macassar,"  and  these 
sorts  in  reality  are  only  species  coming  from  Banjermassin,  Kotaringin,  Coti, 
Bolungan,  Sandekan.  The  Isle  of  Celebes  does  not  belong  to  the  guttiferous  zone 
properly  speaking,  and,  so  far  as  known,  does  not  contain  guttiferous  trees.  As 
to  the  State  of  Pahang,  it  only  recently  put  on  the  market  products  the  quality  of 
which  surpasses  all  others,  and  thus  confirms  the  indications  furnished  by  Selig- 
mann  Lui.  Yet  it  is  difficult  to  admit  that  the  Pahang  as  well  as  the  Borneo  sorts 
are  the  products  of  any  Palaquium. 

The  gutta  perchas  of  this  origin  are  characterised  by  immediate  thickening  of 
the  juice,  which  causes  it  to  be  impossible  to  collect  the  latter  free  from  fragments 
of  bark.  All  explorers  are  unanimous  on  this  point.  Moreover,  the  gutta  percha 
which  comes  from  these  trees  is  always  coloured  by  the  colouring  principle  of  the 
bark,  when  it  is  purified  by  boiling  water.  Again,  the  yield  of  an  adult  Pala- 
quium is  always  very  small.  Nevertheless,  what  do  we  see  1  Pahang  gutta 
percha  is  yellowish  white,  and  contains  very  few  impurities.  That  can  only  imply 
two  things :  either  the  flowr  of  the  juice  is  abundant  and  coagulation  is  not  imme- 
diate, and  things  go  on  as  in  the  case  of  Payena  Lerii,  the  trees  of  Soupayang  and 
Halaban,  or  that  the  gutta  percha  of  this  kind  is  indeed  very  pure,  and  is  not  of 
the  same  species  as  that  of  the  Palaquium,  since  it  has  assumed  no  coloration  at 
the  expense  of  the  bark  during  purification.  As  we  have  no  information  as  to  the 
yield  of  the  guttiferous  trees  of  Pahang,  nor  as  to  the  method  of  exploitation, 
we  can  only  base  our  reasoning  on  hypotheses ;  but,  in  regard  to  the  guttas  of 
Borneo,  we  possess  further  information  in  the  report  of  Leys,  which  is  in  absolute 
contradiction  as  to  the  results  yielded  by  a  Palaquium,  both  in  regard  to  yield  and 
coloration.  It  is  therefore  admissible  to  think  that  the  guttiferous  tree  of  North 
Borneo  is  not  a  Palaquium.  Sandakan. — The  gutta  of  Sandakan  resembles  that 
of  Pahang ;  it  is  very  pure  and  yellowish  white  in  colour.  That  of  Sarawak,  is 
much  redder,  but  it  is  at  the  same  time  very  mixed  with  fragments  of  bark  which 
would  appear  to  be  added  over  and  above,  and  there  is  always  found  in  it  white 
veins  very  free  from  foreign  matter.  Pontianak. — It  is  very  difficult  to  give  an 
opinion  on  the  provinces  of  Pontianak;  however,  trees  of  the  genus  Palaquium 
have  been  signalised  in  this  region.  Kotaringin  and  Banjermassin. — The  two 


CLASSIFICATION   OF  COMMERCIAL  GUTTA   PERCHA      341 


s|..-.-ir>    A'.»/.//-///«///<    and    //•//»./»  rm<i*sin  are  interesting  to   coinj«ire. 
/\iit'iriiit/in,  a    v.-ry  tinr    -_riiH.i,  i^    ->•  nm-t  iim->   CM-H    .piit.-    \\hii.-,   \\liiUt    tin-    H-ini'i 
iinixxiii    is   al\\a\>    li.-.ivil\   .-liar^'d  \\itli  l»ark  drl.ri-,  .in.  I    al 

Iftlir  piv-M-mv  iif  I'nmmriiN  «.|  Lark  \\riv  inherent  to  tin-  in<th<"l  ..(  enHri-timi,  ami, 
as  has  IHVH  des,Til>ed  in  tlie  case  of  tin-  /'"A/-////////',  tin-  -'itta  ••  uln  '  undergo  a 
c.-rtaiii  inimU-r  ..f  manipulations  to  l»c  t'n-ed  fr..m  it,  it  uoiild 
which  should  IK-  tin-  most  wrought  and  the  most  coloured.  Now,  absolutely  the 
contrary  is  the  case.  It  is  therefore  probable  that  the  impurities  of  Banjcrmassin 
are  added  afterwards  to  mislead  researches  and  preserve  the  monoply  of  an  ind> 
n'ldch  is  certainly  lucrative.  The  gutta  of  J////v/»/,///,/,  \.  i  y  white  and  containing 
few  impurities,  gives  rise  to  two  considerations.  The  gutta  perchas  of  Bagan  and 
of  Pekan  present  something  very  peculiar  which  separates  them  not  only  from  tin- 
Palaquium  guttas  but  from  the  guttas  of  which  we  have  just  spoken.  They 
greatly  resemble,  in  all  their  properties,  the  Balata  of  the  Mimufops  batata,  and 
we  believe  that  Bagan  gutta  percha,  in  particular,  may  not  indeed  be  the  result  of 
the  coagulation  of  a  juice,  but  rather  of  an  evaporation  such  as  that  practised  in 
Guiana,  or  some  analogous  operation. 

As  to  the  Sumatra  kinds,-  they  are  the  products  of  the  Palaquium  oblongifolium^ 
more  or  less  mixed  with  that  of  the  Payena  Lerii,  with  Bouha-balam  and  other 
trees  incompletely  studied.  The  gutta  percha  of  Padang  exhibits  many  of  the 
properties  described  by  all  explorers  as  characteristic  of  the  Palaquium  : 
fragments  of  bark,  red  colour,  etc.  As  regards  Souni,  it  is  simply  an  indeter- 
minate mixture  in  diverse  proportions. 

A  very  difficult  question  is  the  origin  of  the  Bolungan  and  Coti  kinds.  \NVn- 
it  not  for  their  specific  resistance,  we  could  apply  to  them  the  remarks  made 
regarding  other  Borneo  species.  But  here  we  have  a  high  specific  resistance,  and 
much  higher  the  more  recent  the  collection  of  the  samples.  Nos.  29,  30,  and  32  of 
Table  XCIII.  are  kinds  collected  some  ten  years  ago.  All  the  others  are  more  recent. 
The  reason,  no  doubt,  arises  from  mixtures  now  made  by  the  natives,  because 
species  of  the  Sandakan  genus  are  now  awantiug  and  no  longer  suffice  to  meet  the 
consumption.  The  greater  specific  resistance  is  probably  due  to  the  addition  of  the 
juice  of  the  Payena  Lerii.  This  tree  yields  a  juice  with  a  higher  specific  resistance, 
as  Nos.  35  and  36  of  Table  XCIII.  show  ;  but  this  juice  has  at  endency  to  resinifica- 
tion,  and  the  specific  resistance  is  then  lowered  at  the  same  time  that  the  gutta 
percha  becomes  brittle  (see  Nos.  37  and  38),  which  explains  why  they  system- 
atically rejected,  in  the  making  of  cables,  the  exclusive  use  of  gutta  perchas 
of  high  insulation.  A  certain  amount  is  indeed  required,  but  the  dose  strictly 
necessary  for  the  futherance  of  the  work  must  not  be  exceeded,  unless  miscalcula- 
tions occur,  which,  from  being  a  long  time  in  maturing,  are  none  the  less  grave  on 
that  account,  as  the  inconvenience  may  only  supervene  when  the  responsibility  of 
the  manufacturer  has  ceased. 

The  species  from  Assahan,  Trenganu,  and  the  white  gutta  of  Pahang,  are 
certainly  mixtures  of  the  juices  of  the  Payena  with  the  Bouha-balam.  In  No.  43 
of  Table  XCIII.  an  analysis  of  this  latter  product  is  given,  which  shows  that  the  resin 
present  in  it  is  twice  the  amount  of  the  gutta.  All  these  white  gutta  perchas  have 
a  weaker  specific  resistance  than  that  of  Payena  gutta  percha.  Perhaps  this  may 
be  due  to  the  mixture  of  the  Payerui  with  the  very  resinous  gutta  Bouha-balam  ;  but 
it  is  impossible  to  verify  this  assertion,  because  it  is  not  possible  to  determine 
the  specific  resistance  of  this  latter  product. 

Nummary  (Leon  Brasse).  —  1.  All  gutta  perchas  of  superior  quality  have  a 
feeble  specific  resistance,  and  it  is  in  no  way  demonstrated  that  they  are  the 
products  of  the  Palaquium.  2.  The  Pahang  gutta,  product  of  the  Palaquium 
oblongifolium,  is  a  gutta  percha  of  average  quality,  and  its  specific  resistance  is  rather 
high.  3.  The  Bolungan  and  Coti  gutta  used  in  the  past  had  a  feeble  resistance. 
Those  which  come  to  market  now  have  a  higher  and  higher.  It  is  necessary  to  use 
them  with  great  prudence.  4.  The  white  guttas  each  exhibit  a  high  resistance  ;  they 
can  neither  be  employed  alone  nor  in  large  proportion  for  the  manufacture  of 


342 


GUTTA   PERCHA 

TABLE  XCIII.— THE  VARIETIES  OF 


«  «-i 

J>  O     . 

•^  t-»  £ 

II  S 

II* 

Variety. 

(  M-igin  of 
the  Variety. 

Form  of  the 
Cakes. 

Coating  of  the 
Cakes. 

Section  of  the 
Cakes. 

Nature  and  Amount 
of  Impurities. 

i 

Pahang. 

State    of    Pa- 
hang. 

Generally     small, 
the       pear  -  shaped 

Yellowish,    rarely 
reddish,  more  often 

Yellowish     white, 
very  rarely  reddish 

A     little    woody 
matter. 

East  coast  of 
Malay    Pen- 
insula. 

lumps  weighing  not 
more  than  1^  to  2} 
Ib.  Flat  lumps  with 

inclining  to  green. 

yellow.      Compact, 
rarely  foliated. 

33  per  cent. 

rectangular      base, 

reaching    6£  Ib.   at 

the  most. 

2 

id. 

id. 

id. 

id. 

id. 

id. 

25  per  cent. 

3 

id. 

id. 

id. 

id. 

id. 

id. 

33  per  cent. 

4 

id. 

id. 

id. 

id. 

id. 

id. 

28  per  cent. 

5 

id. 

id. 

id. 

id. 

id. 

id. 

6 

id. 

id. 

id. 

id. 

id. 

24  per  cent. 
id. 

41  per  cent. 

7 

Sandakan. 

North-east  of 
Borneo. 

Lumps   of  4?    Ib. 
in  parallelipipedons 

Bright  yellow 
colour. 

.. 

A  few  fragments 
of  bark, 

with  flat  trapezoid 
bases   elongated  in 

22  per  cent. 

the  shape  of  boats  ; 

sharp       angles. 
Moulded  gutta. 

8 

Maragulai. 

1 

Very  flat  cakes  of 
IjV  Ib.    or  less,  or 
in  flat    spindles    or 

Greyish       white  ; 
greyer  spots. 

Horny       appear- 
ance. 

No  shapeless  frag- 
ments of  bark  dis- 
seminated   in     the 

squares  of  6f  to  8| 

mass,  but  pieces  of 

Ib. 

about      1-3     centi- 

metre,  all    of    the 

same    shape,    quite 

separate,    and    cer-l 

* 

tainly      added      as 

make-weight. 

9 

Bagan. 

Probably    be- 
tween    Ma- 
lacca     and 

Pear-shaped  lumps 
of  4,5  to  6?  Ib.,  or 
in  carrots  of  13?  to 

Wine    colour, 
soapy    touch,     hot 
and  cold. 

More  or  less  pro- 
nounced,     unequal 
section,  many  holes 

Without  frag- 
ments   of    dissemi- 
nated bark,    or    at 

Singapore. 

17f  Ib. 

in  the  mass  coming 

least   very    few    of 

from  the  imperfect 

them. 

juxtaposition  of  the 

29  per  cent. 

fragments  com- 

bined  to  form  the 

cake. 

10 

id. 

id. 

id. 

id. 

id. 

29  per  cent. 

11 

B  a  n  j  e  r  - 

massin. 

South       of 
Borneo. 

Sticks    80    centi- 
metres (31£  inches) 

Spongy      appear- 
ance.   More  or  less 

Section. 
Salmon-red, 

Many  fragments  of 
bark. 

long    by  10   to    15 
centimetres  (say  4  to 
6  inches)  in  diame- 

brown    and     even 
black. 

foliated. 

45  per  cent. 

ter,  rounded  at  the 

extremities;  or 

parallelipipedons  of 

50  to  60  centimetres 

(20   to    24    inches), 

with  acute    angles 

in  the  shape  of  pig 

lead,     bearing     on 

two   opposite  faces 

sculpture,       repre- 

senting    an     orna- 

mental monster  on 

the    one    face    and 

; 

foliage  on  the  other. 

12               M.                    id. 

id. 

id. 

id. 

40  per  cent. 

CLASSIFICATION   OF  COMMERCIAL  GUTTA   PERCHA      343 

li.\\V  COMMERCIAL  GUTTA  PERCHA. 


Valuation  of  tin- 
Duality. 

Nature  of  tin- 
Thread. 

04  tl.«-  CJulta 

to  til,    1 

SIM-,.  iti,-  Batotoaa 

SlItftfuM 

Centiinetrc^l 

Remarks 

Good        working 

«|ii:ilit\  ;  lianl  ;  \<-r\ 
n.-rxon*; 
its  pri-tim-  lianlni-- 
•  iui<-kly     on 
OOOOOff. 

Slightly  rugose. 

6'20 

ano 

id. 

id. 

4*60 

10 

/./. 

id. 

4-94 

60 

.. 

id. 

id. 

3-89 

15 

></. 

id. 

575 

6 

.. 

id. 

id. 

5-25 

H 

•• 

As  above. 

Thread     more 
smooth. 

2-29 

Be 

This  gutta  percha  would  appear 
to  t*  rolled  before  moulding. 

Very   hard  u'uttu. 
cooling  quickly. 

Rugose  thread. 

1-27 

43 

* 

Rather  hard   and 
nervous  gutta,  cool- 
ing quickly. 

Very  smooth  thread. 

1-47 

30 

Smell  of  opium.     Gutta  difficult 
bo  clean. 
Much    resembles   Balata  )>y  its 
behaviour   on   cleaning    and    on 
drawing  out  into  a  thread. 

id. 

id. 

1-42 

17 

Gutta   very   hard 

ami   vi-ry   nervous; 
cools  quickly. 

Rugose  thread. 

4-00 

141 

id. 

id. 

2-20 

52 

1  Obach's  determinations  of  the  insulation  in  megohms  and  inductive  capacity  in  microfarads  per  cubic 
knot  of  the  various  brands  of  commercial  gutta  percha  are  given  in  Tables  XI.  and  XIV.,  pp.  63  and  66 
of  his  Cantor  Lectures. — Tu. 


344 


GUTTA   PERCHA 

TABLE  XCIIL— THE  VARIETIES  OF 


Consecutive 
Number  of 
Sample. 

Variety. 

Origin  of 
the  Variety. 

Form  of  the 
Cakes. 

Coating  of  the 
Cakes. 

Section  of  the 
Cakes. 

Nature  and  Annum 
of  Implicit 

i      13 

Kotaringin. 

South  of 
Borneo. 

Spindles    pointe< 
at  both  ends,  squar 
or  flat  section  fron 
IT\J  to   2£  lb.,  and 
square  parallelipipe 
dons  of  6?  to  8£  lb 
withslightlyattenu 
ated    and    rounde( 
extremities. 

Colour  brighte 
than  Banjermassin 

Salmon-red 

foliated. 

32  per  cent. 

14 

id. 

id. 

id. 

id. 

id. 

26  per  cent. 

15 

Pekan. 

State  of  Pa 
hang  on  the 
coast. 

Cakes   of    4  to  5 
centimetres  (say  1 
to  2  inches)  thick 
weighing    4g  to  1! 
lb. 

Deep  reddisl 
plum  -  brown  wit! 
a  mouldy  appear 
ance. 

Wine    red  ;    very 
homogeneous. 

Few  impurities. 
23  per  cent. 

16 

id. 

id.. 

id. 

id. 

id. 

29  per  cent. 

17 

Sarawak. 

North-west  of 
Borneo. 

Cakes  light  in 
weight  compared 
with  their  size  when 
dry. 

Spongy       cakes 
varicose  reticulatec 
surface,    with    im- 
bedded bark,  brown, 
earthy. 

Reddish  whit 
section  with  white 
veins. 

Many    fragments 
of  bark. 
50  per  cent. 

18 

id. 

id. 

id. 

id. 

id. 

45  per  cent. 

19 

Pontianack. 

South-west  of 
Borneo. 

Blocks  of  11  to  22 
lb. 

Very  spongy  cakes 
Reddish     yellow 
more      grey     than 
Sarawak. 

Same    section    as 
Sarawak  with  white 
or  grey  veins. 

Loaded  with  im- 
purities. 
44  per  cent. 

20               id. 

id. 

id. 

id. 

id. 

33  per  cent. 

21 

Padang. 

West  of 
Sumatra. 

Blocks  in  form  oi 
very  much  flattened 
square  parallelipipe- 
lons  of  about  5f 
b.,  branded,  or 
more  bulky  cakes 
up  to  66  lb. 

Very  deep  reddish 
yellow. 

Same   section    as 
the    coating;   it   is 
decidedly  foliated. 

Large  amount  o 
debris. 
40  per  cent. 

22 

Sarapong 
or  Souni. 

East  of 
Sumatra. 

Oval-shaped  cakes 
with  pointed  at- 
renuated  extremi- 
iesof  I,1nto2ilb. 

Surface  rugose 
and  earthy. 

Homogeneous 
-ellowish  white  sec- 
tion. 

Very  peculiar. 
30  per  cent. 

23 

•;<L 

id. 

id. 

id. 

id. 

27  per  cent. 

24 

Siak. 

East  of 
Sumatra. 

Sticks  of  4|  to  6g 
b.,      swollen       to- 
wards the  middle. 

Reddish  yellow. 

Brighter    tint  on 
utting  ;       foliated 
ppearance. 

Heavily       loaded 
-ith  bark. 
50  per  cent. 

CLASSIFICATION   OF   COMMERCIAL  GUTTA   PERCHA         1 

I!A\V  r-'KMMKUCIAL  GUTTA  PERCHA— cont; 


Valuati.  Hi  of  ih, 

Quality. 

•  ihe 
Thread. 

to  the  1 

NjH'.-ll 

in  Mr-ohms 
Centimetres.1 

Retliurk  •. 

sli-hth   less  ner- 
\..ii-    than    Hanjer- 

ma>.Mii. 

Kill;..-.-  thr.-a.l. 

4*82 

25 

*  * 

id. 

id. 

4-89 

11 

Slightlv  hard,  in-r- 
\oii-;      OQOb     diffi- 
cultly. 

smooth  thread. 

1-03 

90 

• 

tf, 

id. 

1-42 

17 

nervous  ; 

COOls       Well  ;        \rr\ 

good  qualitv  . 

Rugose  thread. 

3-23 

65 

- 

id. 

VL 

2-85 

128 

5,'ood  gutta. 

Rugose  thread. 

3-57 

141 

id. 

..  .  
id. 

—  
8-02 

—  - 
171 

.. 

Ilaril     and     ner- 
vous; cools  well. 

Nervous  thread. 

2"24 

457 

Owing  to  its  hi-h  insulation,  it  is 
not  possible  to  use  the  pure  article 
for  telegraphic  purposes. 

Inferior    qualitv  ; 
rather     hard,      !>nt 
little  nervous;  cools 

w.-ll. 

Thread     v  o  r  y 
smooth. 

1'49 

Under  the  name  of  Souni  are  in- 
cluded  a    number    of    mixtures 
made  by  the  natives  of  Sumatra. 
These  mixtures   contain    various 
proportions    of    red    and    white 
gutta. 
Here  is  a  formula  which 
maim  Lui  saw  made  up  with  his 
own  eyes  : 
Gutta   Derrian   (Dichopsit 
oblongifoiia)    ...    2 
Gutta    Sundeck    (Payfna 

QuttnPouteli(Bouha-balaiii)  1 
No.    22    is   the    tyjHi  of  a  good 
mixture  for  telegraph  cables. 

«. 

id. 

1-42 

692 

•• 

Rather  hard;  little      Thread     very 
nerve;    cools  quite  smooth, 
well. 

1-05 

900 

This  is  a  gutta  of  the  Souni  kind. 
Ih.  t\i-«   examined  is  a  very  bad 
ane  of  the  kind. 

1Seeiiote,  p.  343.— TR. 


346 


GUTTA   PERCHA 


TABLE  XCIIL— THE  VARIETIES  OF 


Consecutive 
Number  of 
Sample. 

Variety. 

Origin  of 
the  Variety. 

Form  of  the 
Cakes. 

Coating  of  the 
Cakes. 

Section  of  the 
Cakes. 

Nature  and  Amount 
of  Impurities. 

T 

25 

Bolungan. 

East  of 
Borneo. 

Cakes    of    invari- 
able  size,  in   form 
of  lumps  terminated 
by  an  (Billet.    Made 

Blackish,     almost 
fuliginous,    knotty, 
like  badly  trimmed 
sticks  or  batons. 

White    or    violet 
coloured,    allowing 
a    juice    to    exude 
which          solidifies 

Very  peculiar,  but 
adulterated       with 
bulky  pieces  of  bark 
from       5       to      20 

by  folding  the  thin 

immediately  in  con- 

grammes   (i    to    | 

part  of  the  mass  on 

tact  with  the  air. 

of  an  ounce),  some- 

the   body    of    the 

Foliated. 

times    50   grammes 

latter,  several  con- 

(say If  ounce),  all 

volutions  being 

of  the  same  shape 

made. 

and     nature,     and 

Small  cakes  of  4| 

coming       probably 

to  11  lb.,  the  best 
in       large       cakes 

from  the  producing 
tree  ;   they  are   all 

weighing  as   much 

too   similar   not  to 

as  66  lb. 

belong  to  the  same 

species,  and  as  they 

are     never     absent 

they  certainly  belong 
to  a  species  which  is 

met  everywhere  in 

the    neighbourhood 

of   the  gutta  tree, 

and  most  likely  to 

the  latter  itself. 

30  per  cent. 

26 

» 

» 

»» 

M 

» 

30  per  cent. 

27 

„ 

,, 

„ 

„ 

M 

46  per  cent. 

28 

i, 

., 

M 

>» 

„ 

45  per  cent. 

29 

,, 

„ 

» 

M 

H 

27  per  cent. 

30 

Coti. 

East  of 

Cakes   all  of   the 

Reticulated 

Decidedly        foli- 

But little  bark. 

Borneo. 

same    size,    consist 
of  sticks  of  80  centi- 
metres (31£  inches) 

appearance.       The 
meshes  of  the  net- 
work filled  by  frag- 

ated,   yellowish    or 
greyish  white.   Like 
Bolungan,   allows  a 

30  per  cent. 

long    by    15    centi- 

ments   of   wood  of 

liquid  to  exude. 

metres  (say  6  inches) 

a  viscous  yellowish 

in    diameter,  made 

or    reddish    yellow 

by  rolling  up  a  thin 
sheet. 

colour. 

The      extremities 

Some    sticks    are 

More    reddish    on 

More  bark  debris. 

of  the  roll  are  held 

branded,  and  then 

cutting. 

in  the  hand.    They 

are  more  reddish. 

preserve  the  form  of 

the    fingers    which 

have    kneaded    the 

gutta  percha  whilst 

still  hot. 

31 

„ 

„ 

„ 

» 

„ 

26  per  cent. 

32 

M 

„ 

„ 

,, 

H 

33  per  cent. 

33 

.. 

„ 

M 

M 

„ 

33  per  cent. 

34 

„ 

,, 

„ 

,, 

,, 

42  per  cent. 

35 

Cotoman. 

Small  cakes  m  the 

Very  smooth  sur- 

Very white,  allow- 

30 per  cent. 

form  of    a  torsade 

face. 

ing  a  viscous  exuda- 

(twisted  spiral)    of 

tion  to  escape. 

4|  to  6£  lb. 

36 

Keletan. 

North-east 

Cakes  of  1TV  to  2| 

Recent,  waxy  rose 

30  per  cent. 

of    Malay 

lb.,  in  form  of  balls 

appearance. 

Peninsula  ; 
north  of 

of  twine  analogous 
to  the  rubber  balls 

Old,  white  chalky. 

Pahang. 

of  Africa. 

37 

» 

40  per  cent. 

38 

>' 

" 

" 

» 

M 

33  per  cent. 

CLASSIFICATION   OF  COMMERCIAL  GUTTA   PERCHA      347 

RAW  COMMERCIAL  GUTTA  PERCHA 


\  .ilii.ilinii  of  the 

Quality. 

Natur.  of  the 

Ratio  of  ih.-«.:,ii., 

>,..,  ui,    i;.  •     •    • 

Remark*. 

II.  ml. 
j;iitta  ;  cools  well. 

Kugone  thread. 

3-52 

304 

It  is  the   best  gutta  amongst 
those  of  high  insulation. 
It  is  very  dittieuit  t.,  work. 

n 

1-26 

310 

M 

,, 

2-47 

208 

H 

,, 

3-39 

no 

.. 

n 

„ 

3:03 

30 

Hard,    rather 
nervous;  gutta  cools 
well. 

Thread  smooth. 

1-87 

72 

equality    absolutely    comparable 
with  lioltingan  gutta. 

Better  quality. 

•• 

•• 

1-81 

120 

M 

,, 

1-54 

43 

,. 

,, 

1-90 

161 

.. 

., 

,, 

1-20 

829 

Hard    gutta,    but 
wants  nerve. 

Thread     very 
smooth. 

1-56 

3045 

Smell  of  sweat  ;  old  cheese. 
Loss  on  washing,  30  per  cent.,  of 
which    only   \i.  j>cr  cent  .is  solid 
matter. 

Very  nervous  and 
friable.      Not    very 
Man  I  on   the  whole, 
and     totally     want- 
ing   in    nerve,   and 
does  not  cool  verv 
MB. 

Thread     \  e  r  y 
smooth. 

»i 

1 
0-96 

2101 
743 

Two  kinds  of  gutta  are  included 
under    this    name.      One    has   a 
IK-culiar  appearance,  which  shows 

that  it  is  much  as  collected;  that 
is  the  r  i,-.i,'  n  :intt<i  No.  20.2    The 
other  consists  of  two  |<arts,  one 
inferior  in  th<-  cmtre.  Inn 
..M  tin'  surface  with  a  lK-ttt  -i 
This  second  «|uality  -utta  \ii-lds 
a  pnidud  which  oecomeo  brittle 
in  a  short  time. 

» 

»» 

0-98 

1038 

•- 

1  See  note,  p.  343.— TR. 


2  ?  36.— TR. 


348 


GUTTA   PERCHA 

TABLE  XCIIL— THE  VARIETIES  OF 


e* 

. 

Consecuti 
Number  < 
Sample. 

Variety. 

Origin  of 
the  Variety. 

Form  of  the 
Cakes. 

Coating  of  the 
Cakes. 

Section  of  the 
Cakes. 

Friable. 

Nature  and  Amount 
of  Impurities. 

39 

Pahang- 
white. 

State  of 
Pahang. 

Large  round  cakes, 
in  balls  larger  than 
a  man's  head. 

White  chalky. 

40  per  cent. 

40 

id. 

id. 

id. 

id. 

id. 

19  per  cent. 

41 

Assahan. 

North-east  of 
Sumatra. 

Same  appearance 
as  above. 

id. 

id. 

20  per  cent. 

42 

Tringanou. 

North-east  of 
the     Malay 
Peninsula  ; 
on  the  shore 
of  Kelatan. 

id. 

id. 

id. 

31  per  cent. 

43 

Bouha- 
balam. 

Malacca. 

Fragments  of  no 
shape,  which  must 
be  quickly  blocked 
for  fear  of  crum- 
bling to  powder. 

44 

Gutta 
Pouteh. 

Sumatra. 

tt 

.. 

45 

Balata. 

Guiana     and 
Venezuela. 

Greyish  blocks,  or 
reddish  plates  of  1 
to  2  centimetres  in 
thickness,  preserv- 
ing the  form  of  the 
boxes  in  which  the 
j  nice  has  been  dried. 
Width  of  the  rect- 
angular blocks,  0'40 
metre  (17'6  inches). 
Length,  0-80  metre 
(31£  inches). 

Vague  appearance 
of  dried  skins,  soapy 
to  the  touch. 

Very  little  foreign 
matters  ;  little  bark. 
Often    mixed    with 
lime. 
The  natives  have 
for  a  certain   time 
adulterated         the 
juice    with    water, 
adding  lime  to  bring 
back  its  consistency. 

TABLE  XCIV.— ANALYSIS  OF  VARIOUS  BRANDS  OF  COMMERCIAL 


Genuine  from  Palaquium  Sp. 

Pahang. 

Bolungan  Red. 

Banger  Red. 

D  =  0-9858.     *L  3-9. 

D  =  0'9911.     J  3-4. 
K>. 

D=  0-9868.     G-  4  0. 

6   .  fGutta      .       . 
&  §  J  Resin      . 
|S  I  Dirt         
0  »  [Water     

A. 

57-0 
13-3 
11-5 

18-2 

I. 

61-5 
13-1 

10-0 

15-4 

74-6 
25-4 

2-9 
4-7 

II. 

54-7 
13-8 
161 
15-4 

III. 

52-1 
14-0 
14-1 
19-8 

A. 

51-8 
18-2 
10-8 
19-2 

I. 

53'5 
17-5 
9-0 
20-0 

II. 

48-1 
21-9 
12-2 

17-8 

III. 

41'4 
23-8 
12-0 

22-8 

A. 

40-7 
20-0 
17-4 
21-9 

46-5 
18-9 
13-1 
21-5 

ii. 

41-5 
20-4 
17-4 
20-7 

III. 

35-5 

22-8 
19-2 
22-5 

58-3 
41-7 

G.  P.  (G.+R.)  . 
Waste  (D.+W.)        

70-3 
29-7 

2'4 
4'3 

81-1 
18-9 

93 
233 

68-5 
31-5 

661 
33-9 

70-0 
30-0 

2-3 

2-8 

71-0 
29-0 

70-0 
30-0 

65-2 
34-8 

60-7 
39-3 

65-4 
34-6 

61-9 
38-1 

.  r  G.P.  > 
JJwStel      
SI    G.P.  i 

P3  1  r>_a- 

2'2 
4-0 

2-0 
3-7 

78-9 
21-1 

2-4 
3-1 

2-3 
2-2 

687 
31-3 

1-9 
1-7 

1-5 

2-0 

1-9 
2-5 

1-6 
2-0 

1-4 
1-6 

60-9 
39-1 

III)  Gutta  . 
g  S3  2  f  Resin  

82-4 
17-6 

26 

54£ 

79-8 
20-2 

13 

26* 

74-0 
26-0 

75-4 
24-6 

63-5 
36-5 

6 
3i 

67-1 
32-9 

71-1 

28-9 

67-1 
32-9, 

Lots  ... 

15 

28J 

37 

60 

10 

10 

6 

3 

91 
232 

28 
35 

27       22 
39i     48J 

Tons  

A  =  Average  of  all  grades  ;  I.,  II.,  III.,  different  grades.     D  =  density.    — '  =  ratio  of 

K. 


CLASSIFICATION   OF  COMMERCIAL  GUTTA   PERCHA      349 

RAW  COMMERCIAL  GUTTA  PERCH A-comV 


Valuation  of  tlu- 
Duality. 

Nature  of  the 

Thread. 

Katio  of  the  Gutta 
to  the  Resin. 

Remarks. 

in  itfobn* 

Centimetre*.  » 

Soft,       enough 

nrnr;    cools    well, 

bMkjr, 

Very      smooth 

ihn-iui.  bm  dithVuii 
to   work   alone,  as 
it   adheres   to    the 

1*11 

000 

The  surface  of  the  coke  to  often 
•    of    nervous 
-utiua  i.  «  oMtfanrtra  thi.  It 
The  fresh  cake*  have  a  smell  of 

rolls. 

ript-  dwtM. 

•  • 

,. 

rie 

743 

•• 

i'.ulity       .slight  1> 

id. 

0*90 

743 

(i 

interior    t«'    thr    prr- 

ci-d  i  11  x  ;        more 

tackv  ;     does     not 

cool  so  w  oil. 

UL 

" 

1-18 

743 

M 

Soft    guttu    \vitli- 
out     IHTM-;     does 

Cannot  be  wrought 
alone,  as  it  is  too 

0-52 

Impossible  to  de- 

t  iTininr. 

Producing  tree  (not  described), 
which  grows  in  the  inar»h>    <li-- 

not  cool  at  all,  i.f. 
t\cii    ;ift«-r    several 

tacky. 

tricts  of  the  gutta  )>ercha  coun- 
tries, and  whirh  is  used  to  adul- 

days of  cooling  llu- 

terate  all  sort*  a  little. 

plutt-s  of  this  sub- 

V.-ry little  used  in  spite  of  its 

stance  are  capable 
i  >f  st  icking  together. 

low  price,  probably  bv<-an-.-  th.-r. 
is  already  sufficient  of  it  in   tin- 

Thev  must  be  pow- 

white gutta  pen-ha,  which  is  Hied 

dered  with  talc  to 
1  TCM  nt  them  from 
uniting  to  a  single 

to  render  the  working  of  the  good 
kinds  possible. 

block. 

Soft  gutta  ;    very 

1-49 

800 

Forms   the    transition    between 

nervous  ;      slight! 
elastic. 

rubber  and  gutta  peivha. 
Heated,  it  does  not  soften  cm  >u:;h 

Cools  very  slowly. 

so  as  to  be   used  for  insulating 
wire  like  gutta  percha. 

It  is  employed  in  mixtures,  to 

which  it  communicates  iU  slow- 

ness of  cooling. 

RAW  GUTTA  PERCHA  DURING  1889-96  (OBACH). 


Soundi  from  Payena  Sp. 

White  from  Unknown  Species. 

Miv.Un.l  I:. 
boilwl  from  t  '„. 
nown  Sources. 

Bagan. 

Kotaringin. 

Sorapong. 

Bolungan. 

1 

Banger. 

1! 

Ij 

lj 

D  = 

a 
B 

A. 
44-1 
30-4 
6-3 
19f 

=0-9709. 
:  1-44. 

D=  0-9729. 
G-1-S 

R713- 

D=  0-9767. 

|m 

D  =  1-0093. 

;;:  '•"• 

I. 
44-2 
29-7 

«;••_• 
19-9 

78-9 
26-1 

II. 
43-7 
3*2-2 
6-8 
17-3 

75-9 
24-1 

3-2 

T4 

57-6 
42*4 

10 
10* 

A. 
46-1 
81-5 
8-3 
14-1 

77-6 
22-4 

3-5 

IT. 

59*4 
40-6 

I. 

48-8 
29-9 
7-6 
13-7 

78-7 
21-3 

3-7 
1-6 

62-0 
38-0 

II. 

45-0 
32-3 
8-6 
14-1 

III. 

42-1 
38-7 
9-1 
15-1 

A. 

:{'.••;, 
BM 
3-3 
26-3 

40-6 
29-5 
3-1 

_>.;-.x 

70-1 

•_•!>•!• 

2-3 

1-4 

57-9 
42-1 

26 
87 

II. 
38-5 
32-3 
3-6 
25-6 

A. 

1  >l"_> 

20-2 

40-3 
30-7 

10-1 

18-9 

II. 

nt 

:«-n 
10-4 
21-8 

68-3 
31-7 

2-2 
1-1 

:.!•: 

48-3 

28 
73 

A. 
M1 

:;,r,i 
5-6 
29*9 

64*5 
85-5 

1-8 
1-2 

:,::•:, 
46-5 

56 

227 

A. 
M-8 
M-fi 

!»•> 

;;:;-.» 

51*8 

48-7 

ri 
l-i 

52-2 

ir-a 

I. 

._,,,.,, 

•J.'rl 
12-.I 
82-1 

II. 

-.;•! 
•_•:;•  i 
16-fl 
Mf 

»;»•:, 
50-6 

1-H 
11 

47-8 

ill. 
•_••_••:, 
31-1 
14-7 
31-7 

Bf 

46-4 

If 

M 

ttf 
58-0 

A. 

•_•:,., 
15-0 
•JJ-7 

60-8 
897 

If 

N 

UNI 
579 

A. 
26-5 
•Of 

18*4 

29-8 

:,«;•> 
48*2 

A. 

:.:,•:, 
89-1 
5-6 

•JL-> 

:-.-«; 
27-4 

2-6 
0-9 

»r,-i 

:,:;•:. 

47 

138 

74-5 
26-5 

77-3 
22-7 

75-8 
24-2 

70-4 
29-6 

2-4 
1-3 

56-1 
43-9 

62 
101 

70-8 
29-2 

(HIT, 
80-4 

7T" 
29-0 

•1-4 
If 

56-8 
43-2 

22 

83* 

66-0 
46-0 

If 
If 

54*4 
I6f 

r:. 

:.!»••_' 
40-8 

33 
36 

2-8 
1-5 

.--!»•> 

40-2 

3-4 
11 

:»••_' 
41-8 

8-1 
1-2 

55-5 

44-;. 

IT 

15J 

2-4 
1-2 

54-4 
45-6 

24 
42} 

J! 

45-5 

4:. 
156 

0-9 

46-7 

:,:;•:; 

H 
190 

15 
16* 

71 

25 
32J 

22 
23* 

s; 
ttO 

68 

:i4 

108 

15 

a 

gutta  percha  to  resin  in  separate  samples  used  to  determine  density. 


note,  p.  343.— TB. 


350 


GUTTA   PERCHA 


cables.  5.  Finally,  one  cannot  believe  that  it  was  the  product  of  a  Pala<j //////// 
which  was  used  by  itself  alone  as  the  dielectric  of  the  submarine  cables  laid  in  the 
beginning.  Its  specific  resistance  is  always  about  400  102  megohms,  and  wr  do 
not  know  of  a  cable,  in  Great  Britain  at  least,  the  specific  resistance  of  which  exceeds 
120  106  megohms.  6.  The  best  quality  of  gutta  percha  is  that  of  Pahang, 
Sarawak,  and  Sandakan. 

TABLE  XCV.— ANALYSIS  or  GETAH  TABAN  MERAH  AND  GETAH  SOONDIE  FROM 
VARIOUS  SOURCES  (OBACH). 


Description. 

Percentage 
Composition. 

Totals. 

Ratios. 

Percentage 
Composition 

Quality. 
do) 

0. 

Type. 

Name  and  Source. 

Gutta 
G. 

Resin 

R. 

Dirt. 

p. 

Water 
w. 

G.P. 

(G.+R.) 

Waste 

(D.+W.) 

G.P.  Gutta 

Gutta 
Q. 

Resin 

R. 

Waste 

Resin 

Getah 
Taban 
(Merah) 

Getah 
Soondie 

1.  Gutta  Taban 
(from  Selangor) 
2.  Pahan  Taban     •  . 

3.  Getah  Taban  Merah   . 
(Dichopsis  Gutta,  Benth.) 
4.  Pahang  A.  . 

5.  Gutta  Mantah     . 
(from  Borneo) 
6.  Gutta  Sundek     . 
{Payena  Lerii) 
7.  Getah  Sundek     . 
(Payena  spec.) 
8.  Goolie  Soondie    . 
(from  Bagan) 

75-5 
68-8 
667 
66-2 

50-8 
46-4 
43-0 
51-5 

13-5 
10-1 
14-0 
11-6 

38-9 
34-7 
32-6 
38-3 

2-0 
5-4 
6-2 
13-2 

9'3 
2-6 
5-1 

2-8 

9-0 
15-7 
13-1 
9-0 

1-0 
16-3 
19-3 
7'4 

89-0 
78-9 
80-7 

77-8 

89-7 
81-1 
75'6 
89-8 

11-0 
21-1 
19-3 
22-2 

10-3 
18'9 
24-4 
iO'2 

81 
3-7 
4-2 
3-5 

5'6 
6'8 
4-8 
5'7 

84-8 
S7'2 
82-6 
85-1 

15-2 
12-8 
17-4 
14-9 

lh 
1» 
1= 
!»' 

Mean 

84-9 

15-1 

]>' 

8-7 
4'3 
3-1 
8'8 

1-3 
1-3 
1-3 
1-3 

56-6 
57-2 
56-9 
57-4 

43-4 

42-8 
43-1 
42-6 

4» 
4* 
4a 

4a 

Mean 

57-0 

43-0 

4. 

Particulars  of  above  samples. — 1.  Colonial  and  Indian  Exhibition,  1886,  Straits  Settlements, 
very  light  pinkish,  not  dense,  yielded  light  pinkish  brown  gutta  ;  hard  dark  brown  resin. 
2.  Singapore  market,  1890,  very  light,  clean,  not  dense,  yielded  very  light  brown  strong  gutta, 
and  nearly  hard  light  brown  resin.  3.  H.  N.  Ridley,  Esq,.  F.L.S.,  Singapore,  1892,  light  pinkish, 
brown,  clean,  dense,  yielded  light  pinkish,  very  strong  gutta,  and  hard  reddish  brown  trans- 
lucent resin.  4.  Homogeneous  piece  picked  out  from  large  lot  1897,  yielded  pink,  dense,  little 
fine  bark  gutta,  and  hard,  very  dark-brown  resin.  5.  James  Collins,  Esq.,  1880,  Kew  Gardens, 
very  light,  crumbling,  clean,  yielded  very  light  brownish  gutta,  and  hard  yellowish  brown  resin. 
6.  Sir  Hugh  Low,  Perak,  1885,  Kew  Gardens,  very  light,  dense,  clean,  yielded  nearly  colour- 
less gutta,  and  very  soft  light  brown  resin.  7.  H.  N.  Ridley,  Esq.,  Singapore,  very  light, 
dense,  clean,  yielded  nearly  white,  very  strong  gutta,  and  very  soft  light  brown  resin. 
8.  Homogeneous  piece  picked  out  from  large  lot  1897,  very  light,  dense,  clean,  yielded  very 
light  brown,  very  strong  gutta,  and  soft  light  yellow  resin. 

TABLE  XCVI. — ANALYSES  OF  SINGAPORE  GUTTA  PERCHAS  BY  VAN  ROMBURG 

AND  TROMP  DE  HAAS. 


Dirt. 

Water. 

Resins. 

Gutta. 

Price 
per  picul. 

$ 

Bila  of  red  Soondi    

33-6 

7-0 

31'4 

28-0 

150 

Sarawak  Soondi  No.  2       .... 

37-1 

6'8 

25-5 

29-6 

135 

Penang  Gutta  Palelo  No.  1        ... 

2-1 

5-8 

53-8 

38-3 

180 

Sarawak  red  Soondi  No.  1         ... 

19-0 

3-9 

35-5 

41-6 

350 

Bagaii  white  Soondi  No.  1         ... 

07 

8-6 

36-5 

54-2 

350 

Koatei  Gutali  Merah  No.  2       ... 

217 

5-1 

28-5 

447            360 

Indragiri  white  Soondi     .... 

2-0 

4-1 

46-2 

477 

370 

Sambas  white  Soondie       .... 

1-0 

4'4 

53'6 

41-0 

380 

Koatei  Gutah  Merah  No.  1 

14-8 

3-8 

34-8 

46-6 

500 

Pahang  white  Soondie  No.  1     . 

4-2 

0-5 

12-8 

82-5            500 

CHAPTER  V 
PHYSICAL  AND  CHEMICAL  PROPERTIES  OF  GUTTA  PERCHA 

I-'KOM  the  previous  details  the  reader  will  readily  appreciate  how  ditliciilt  is  tin- 
examination  of  the  physical  and  chemical  proi>erties  of  a  substance  so  variable  in 
composition,  and  the  properties  of  which  differ  infinitely  from  one  species  to 
another.  How  can  a  substance  of  which  not  even  the  real  botanical  origin,  which, 
most  generally,  is  only  a  simple  mixture  of  several  products  of  different  origin  and 
different  properties,  be  determined  with  any  scientific  certitude. 

Still  more  than  in  the  case  of  indiarubber,  we  regret  that  researches  up  to  now 
have  only  i>een  on  goods  imported  into  Europe,  and  that  the  latex  of  the  >'<//, <//aceee 
and  the  gutta  percha  derived  therefrom  have  not  be.en  examined  ina  methodical  manner 
on  the  spot  of  production.  In  default  of  such  data,  it  would  have  been  desirable 
to  examine  the  proi>erties  of  a  gutta  percha  taken  from  the  wrapping  of  a  cable, 
the  good  qualities  of  which  had  been  tested  fora  length  of  time.  This  resource 
also  failed  us,  as  it  failed  our  predecessors.1  Dr.  Miller  in  1860  was  indeed  able 
to  study  the  chemical  composition  of  the  gutta  percha  used  in  the  construction  of 
a  cable,  but  this  cable  was  of  recent  construction,  and  its  qualities  had  not  been 
consecrated  by  time.  We  therefore  condense  the  observations  made  and  the 
results  obtained,  not  upon  a  natural  product  of  certain  origin,  but  on  a  simple 
commercial  type,  even  though  this  type  be  often  described  as  pure  Isonandra  gutta. 

Colour,  smell,  etc. — The  latex  is  coloured  by  a  certain  amount  of  colouring 
matter  which  exudes  from  the  bark  when  incised,  and  this  colour  is  embodied  in 
the  resultant  gutta  percha.  Certain  species  impart  a  characteristic  colour  to  their 
product,  so  the  Chinese  boil  low  grades  with  bark  of  best  species  to  get  the 
desired  colour.  Pure  gutta  percha  is  colourless ;  translucid  when  thin.  But 
a  cut  slice,  ^  of  a  millimetre  thick,  laid  on  a  white  surface  shows  a  special 
coloration  varying  between  rose  and  greyish  white.  Under  the  polariscoiKj,  it 
presents  a  magnificent  appearance,  appearing  to  consist  of  prisms  which  sink  into 
each  other,  and  so  give  rise  to  the  most  varied  hues.  It  is  inodorous  and  insipid, 
and  it  is  only  under  the  action  of  certain  transforming  and  decomposing  agents 
that  it  assumes  an  acrid  characteristic  smell.  Structure. — It  possesses  naturally 
a  cellular  structure,  but  when  strongly  pulled  it  is  drawn  out  and  its  texture 
becomes  fibrous,  and  in  this  condition  it  is  much  more  resistant.  If  its  length  be 
doubled,  by  a  strong  pull  it  supports  without  breaking  the  action  of  a  force  double 
that  which  has  been  required  to  stretch  it.  But  it  does  not  exhibit  resistance  in 
e\ery  direction,  like  indiarubber,  and  it  is  easily  torn  under  the  action  of  a 
transversal  force. 

This  cellular  structure,  capable  of  modification  and  of  passing  to  the  fibrous 
state,  is  not  equally  developed  in  all  kinds  of  gutta  perchas,  and  in  general  the 
more  easily  a  gutta  percha  passes  from  one  condition  to  another,  the  more  it 
possesses  the  requisite  qualities,  and  the  more  it  is  separated  from  those  bastard 
species  known  under  the  name  of  gutta-caoutchoucs.  But  exaggeration  of  this 
structure  leads  to  too  brittle  gutta  perchas,  which  cannot  be  used  alone  in  cable- 
making.  Gutta  percha  does  not  amalgamate  or  join  with  itself  at  the  ordinary 
temperature.  If,  however,  two  surfaces  be  heated,  placed  in  contact,  and 
1  The  necessary  data  have  since  been  supplied  by  Obach,  Table  OIL,  n.  361. — TB. 

851 


352 


GUTTA   PERCHA 


simultaneously  pressed  rather  energetically,  the  parts  in  contact  join  and  form  a 
single  piece,  which  is  quite  incapable  of  reverting  to  its  first  position.  But  in 
this  operation  care  must  be  taken  not  to  use  too  great  a  heat,  because  when  the 
gutta  reaches  its  melting-point  it  remains  pitchy  after  cooling,  and  is  no  longer 
endowed  with  its  natural  properties. 

Tensile  strength. — At  the  ordinary  temperature  gutta  percha  is  solid,  pliant, 
very  tenacious,  but  slightly  elastic.  It  does  not  break  until  submitted  to  a  load 
of  24'5  kilos,  per  square  millimetre,  whilst  elongating,  according  to  the 
species,  50  to  60  per  cent.  It  may  be  folded,  tied,  and  drawn  without  incon- 
venience, but  it  is  easily  cut  by  a  point  or  by  a  cutting  instrument.  Its  elasticity 
in  that  condition  is  that  of  softened  leather. 

TABLE  XCVII. — TENACITY  OF  GUTTA  PERCHA,  COHESIVE  PROPERTIES  OF  GUTTA 
PERCHA  TUBES  OF  DIFFERENT  DIMENSIONS,  AND  TENSILE  STRENGTH  OF 
GUTTA  PERCHA  (STORER  AND  STODDER,  1856). 


Length  of  the  Tubes 
in  Metres. 

Interior 
Diameter 
in  Metres. 

Exterior 
Diameter 
in  Metres. 

Pressure  per  Square  Centimetre. 

Supported 
in 
Kilogrammes. 

Occasioned 
Rupture 
Kilogrammes. 

30-4779 

Samples  varying    in  | 
length  from  0'0254  J 
metre  to  0'0762.       < 

0-0254 

0-0255 
0-0160 
0-0127 
0-0127 
0-0063 

0-0301 

0-0302 
0-0285 
0-0262 
0-0160 
0-0160 
0-0160 

7-02770 
18-69368 
21-08310 
19-67756 
22-48864 
16-44482 
25-29972 
50-59944 

19-1*1584 

22-48864 
21-36421 
25-29972 
16-86648 
and  ruptured 
53-41052 

The  tensile  strength  of  gutta  percha  is  the  chief  mechanical  property  of 
interest  to  the  technologist.  When  gutta  percha  is  subjected  to  a  pulling  force  it 
becomes  more  resistant.  When  a  thin  strip  is  pulled  it  at  first  stretches  easily, 
but  after  a  certain  point  it  becomes  so  resistant  to  stretching  that  it  cannot  be 
elongated  any  further.  If  a  thin  rod  of  gutta  percha  with  a  thickened  end, 
technically  termed  a  "  gut,"  be  hung  from  the  bracket  at  the  top  of  the  stand  S, 
and  a  weight  w  of  4  Ib.  applied  to  it,  it  stretches  at  once  to  a  certain  point  on  the 
scale  a,  but  it  does  not  break  even  if  twice  that  weight  be  applied,  although  the  gut 
has  become  considerably  thinner  than  at  first.  (Fig.  117).  If  it  now  be  loaded  with 
say  21  Ib.  it  stretches  further,  and  then,  if  the  experiment  be  carefully  made,  and  the 
breaking  strain  per  square  inch  of  original  area  taken  as  usual,  it  would  work  out 

TABLE  XCVIII. — ELASTICITY  OF  GUTTA  PERCHA. 


Length  of  the 
Band  in  Metres. 

Contraction  due 
to  Elasticity  in 
Metres. 

Unloa 
Loade 

Jed       

0-66628 
0-66987 
0-67944 
0-66904 
0-66850 
0-66795 
0-66758 
0-66679 

0-00043 
0-00040 
0-00046 
0-00063 
0-00037 
0-00097 

i  with  3  kilogr. 
2-5 
2-0 
1-5 
1-0 
0-5 
0-4 

immes 

PHYSICAL  AND  CHEMICAL  PROPERTIES 


353 


s- 


bctwccn  2000  to  3000  11).  for  that  particular  material  ;  but  if  instead  of  the  original 
area  the  final  sectional  an-a  at  bivakiii.tr  had  been  taken,  the  strain  would  have 
been  found  t«i  be  about  IL'.OIIO  lli.  per  square  inch.  Gutta  perchas  with  different 
percentages  ,,f  resin  have  dilt'eivnt  breaking  strains.  Their  tensile  strength  depends 
largely  mi  tin-  percentau'c  of  re>in.  A  mall-rial  haxing  about  \~>  p<-r  cent,  of 
gutta  ami  .Vi  per  cent,  of  resin,  breaks  at  about  770  Ib.  to  tin-  square  inch.  When 
such  revin  is  extracted  by  petroleum  ether  from  the  same  material,  it  would  stand 
up  to  about  twice  that  breaking  >train. 

Dr.  Sherman  (loc.  dt.\  in  reporting  the 
result^  of  certain  tensile  tests  on  various  samples 
of  gutta,  remarks  that,  in  order  that  t lie  measure 
menN  made  might  be  within  the  limits  of  the 
instruments  at  hand,  only  small  strands  of  gutta] 
percha  could  be  used  in  testing.  To  make  these 
strands  free  from  minute  air-bubbles  was  well- 
nigh  impossible,  in  consequence  of  which  the 
breaking  \\as  in  most  cases  brought  about  by 
weakness  due  to  this  source.  The  figures, 
while  thus  only  approximate,  are  below  and  not 
above  the  true  values,  and  show,  he^claims, 
clearly  the  enormous  tensile  strength  of  his 
samples.  Obach,  continues  Dr.  Sherman,  gives 
a  tensile  strength  of  5000  Ib.  for  the  best  gutta 
percha,  while  for  the  gutta  from  it  he  found 
about  6500,  which  closely  corresponds  with 
Sherman's  results,  and  this,  he  claims,  brings 
out  most  clearly  the  excellent  quality  of  the 
best  Philippine  gutta  percha 

Elasticity,  etc. — Table  XCVIII.  gives  results 
of  careful  experiments  made  by  Adriani  to  de- 
termine the  permanent  expansion  and  elasticity 
of  gutta  percha.  Ho  likewise  determined  the 
weight  capable  of  rupturing  a  gutta  percha  band 
with  a  given  force.  He  used  a  piece  of  engine 
belt  0-001755  metre  in  thickness  by  0'06  metre 
wide.  The  extension  and  contraction  were  deter- 
mined by  means  of  an  ink  tracer  for  drawing 
very  fine  lines,  by  which  divisions  of  0 '00001 
metre  might  be  distinguished.  The  trials  were 
made  at  a  temperature  of  17°  C.  (62 '6°  F.). 
Observations  were  taken  every  ten  minutes,  so 
that  each  result  tabulated  above  is  an  average 
of  six  observations  which  together  took  an  hour. 

The  elastic  elongation  for  a  weight  of  3  kilos, 
is  therefore  equal  to  0*00308  metre,  the  per- 
manent elongation  being  0*0005  metre.  By 
loading  the  band  more  and  more,  it  ruptured 
with  186  kilos. 

The  elongation,  according  to  Obach,  or  the 
extent  to  which  a  "  gut "  stretches  before  it  breaks,  is  also  affected  by  the  per- 
centage of  resin.  In  the  last  two  cases  cited  under  "tensile  strength"  the 
elongation  was  460  and  500  per  cent,  respectively,  but  it  also  depends  on  the 
nature  of  the  gutta  percha. 

Hardness — Resistance  to  pressure,  to  a  blow,  or  to  shearing. — These  properties 
are  also  all  influenced  by  the  percentage  of  resin. 

J'>  rnwaltUity. — Gutta  percha  seems  very  impermeable,  but  in  thin  sheets,  as 
obtained  by  the  evaporation  of  a  solution  thereof  in  carbon  disulphide,  it  would 
23 


Fie.  117.— Golfball  testing  apparatus, 
as  used  by  Obach,  showing  an  actual 
application  of  stretching  test. 


354  GUTTA  PERCHA 

appear  to  be  endowed  with  a  peculiar  porosity  :  under  the  microscope,  the  cavities 
by  which  it  is  riddled  are  easily  observed.  These  allow  water  to  penetrate  by 
the  expansion  of  the  sides  of  the  cavities.  The  quantities  of  salt  and  soft  water  *n 
absorbed  by  gutta  percha  are  in  the  ratio  to  each  other  of  3  to  5.  For  sea  water 
the  absorbing  power  of  the  gutta  becomes  twice  greater  when  the  temperature  rises 
from  4°  to  49°  C.  (39°'2  to  120°'2F.).  In  fresh  water  the  increase  is  a  little  more 
rapid.  Pressure  has  no  appreciable  influence  on  this  property.  The  water  absorbed 
seems  to  penetrate  only  to  a  certain  very  small  depth  into  the  pores  of  the  gutta 
percha.  Beyond  this  limit  the  weight  of  water  does  not  increase,  no  matter  how 
thick  the  block.  The  water,  interposed  mechanically,  does  not  in  any  way  alter 
the  dielectric  properties  so  long  as  it  does  not  exceed  2  to  3  per  cent,  of  the  weight 
of  the  gutta  percha.  [Obach's  results  quite  confirm  this  statement;  see  Table 
CXXIIL,  p.  397.] 

Density. — The  density  of  gutta  percha,  generally  given  as  varying  between 
0-999  (Adriani)  and  O979  (Soubeiran),  is  in  reality  greater  than  that  of  water. 
This  divergence  is  explained  by  Payen  as  due  to  the  different  methods  of  preparation 
of  the  gutta  percha.  He  strongly  compressed  a  band  of  softened  gutta  percha,  and 
reduced  under  water  the  ribbons  obtained  in  quantity  into  small  fragments.  The 
majority  of  these  instantly  fell  to  the  bottom  of  the  vessel,  whilst  others  floated  on 
the  liquid  for  some  time,  to  sink  after  having  been  sufficiently  penetrated  by  the 
aqueous  liquid.  Gutta  percha  is  thus  only  apparently  lighter  than  water  because 
of  its  porosity.  This  porosity  is  less  the  more  care  taken  in  purifying  it.  By 
compressing  gutta  percha  its  porosity  is  diminished  and  its  density  is  increased. 
Payen's  opinion  is  confirmed  by  numerous  other  scientists,  and  it  is  now 
admitted  that  the  density  of  laminated  gutta  percha  varies  between  I'OIO 
and  1-020. 

Action  of  heat. — At  37°  C.  (98° *6  F.)  gutta  commences  to  soften,  and  its 
properties  are  so  perceptibly  modified  that  a  gutta  percha  cable,  after  being  made, 
should  not,  according  to  Wunschendorff,  be  submitted  to  a  temperature  above  32° 
to  33°  C.  (89°-6  to  91°-4  F).  If  the  temperature  rises  to  +50°  C.  (122°  F.)  the 
change  is  still  more  accentuated,  and  if  we  can  knock  it  about  with  impunity  or 
hurl  it  against  a  wall  in  this  condition,  it,  on  the  other  hand,  becomes  very  sensitive 
to  a  slow  pressure  exerted  on  its  flat  surface.  It  is  capable  of  receiving  the  most 
fine  and  delicate  impressions,  which  it  afterwards  retains.  At  90°  C.  (194°  F.)  it 
becomes  adhesive  and  undergoes  a  sort  of  pasty  fusion,  which  enables  it  to  be 
kneaded  and  moulded  at  will.  All  imaginable  shapes  may  thus  be  given  to  it,  and 
these  remain  permanent  when  it  has  regained  the  normal  temperature.  This 
characteristic  property,  likewise  possessed — though  to  a  less  extent — by  other 
plastic  substances,  is  due  to  the  air  interposed  in  the  pores  of  the  substance. 
Masticated  gutta  percha  swells  in  a  vacuum,  and  its  surface  tears.  If  it  be  very 
dense  it  does  not  immediately  swell-  in  the  bell  of  the  air-pump,  but  if  it  be 
immersed  in  mineral  oil,  and  a  vacuum  be  afterwards  made,  it  gives  rise  to  an 
abundant  and  prolonged  disengagement  of  air.  Thus  prepared,  and  again  exposed 
to  the  open  air,  it  loses  its  property  of  hardening  after  cooling,  and  resembles 
strongly  greased  leather.  At  100°  C.  (212°  F.)  the  pasty  fusion  is  completely 
terminated,  the  substance  resinifies  in  contact  with  air,  absorbing  one-quarter  of  its 
weight  of  oxygen.  At  130°  C.  (266°  F.)  it  melts;  heated  further  it  boils  and 
distils,  leaving  a  light  block  of  charcoal  as  a  residue.  The  colourless  oils  from  this 
distillation  consist  principally  of  isoprene  and  caoutchene.  Gutta  percha  does  not 
lose  its  suppleness  at  10°  C.  below  zero  (14°  F.),  whilst  rubber  is  very  sensitive 
to  cold. 

Determination  of  temperature  at  which  gutta  percha  becomes  plastic. — This 
temperature  depends  almost  entirely  on  the  relative  proportion  of  gutta  and  resin. 
The  apparatus  used  by  Obach  consists  of  a  rectangular  frame  in  which  three  strips 
(Nos.  1,  2,  and  3)  of  gutta  percha  are  each  held  under  the  tension  of  a  spring,  it  being 
so  arranged  that  an  electric  contact  is  established  and  an  alarm  sounded  as  soon  as 
one  of  the  strips  becomes  soft  enough  to  allow  the  spring  to  pull  it  apart.  In  a 


PHYSICAL  AND  CHEMICAL  PROPERTIES  355 

eertaiu  experiment   N.».    1  omtainnl  2J,  No.  2,  38,  and  No.  ;>,  <!0  per  n-nt.  of  resin; 
No.  1  being  artificially  prodmvd.      Tin-  frame  \\itli  tin-  strips  is  mum-rued  in  water 
in  a  large  beaker  slowly   heated  on  a  sand   bath.      I'p  to  10   ( '.  nothing  occurs. 
At    12    <J.    the    l»rlls    sMiiml,    ami    tin-   shutter    No.    3   of   the    indicator    dp 
\\hirli    shous   that    No.    ."•    -ample,    n.ntainm.u'    <;n    I"'''    Cent,    of     n->in,    ha>    -utliri 
ently    >o|'trned    to   yield    to    tin-    -prini:.      Tip-    ln-ll    rings  a   second   time   ,r 
A     ratln-r    lung   time    rla|»r-    before    the    Iwll    rin^s    for    the    third    time,    before 
No.    I     >lmtter    drops,    and    tin-    strip    No.     I,    \\ith    L'.1,    per   <-.-nt.    ••!'   re>in. 

0. 

I)'  f'  i-iitliKition  <>t'  /,////»  r«t in-*  'if  n'liirli  i/iitfn  IH  ,-i'/ta  softens.1 — This  has  only  a 
relative  value,  and  depends  on  the  particular  method  of  testing  employed.  A  thin 
plate  of  the  gutta  percha  to  be  tested  is  placed  in  a  large  shallow  water  bath  heated 
slowly  over  a  gas  burner.  A  rather  long  lever  is  supported  at  one  end  by  a  pivot, 
and  carries  a  1  Ib.  weight  at  the  other.  Half-way  along  the  under  side  of  the  lever 
is  fixed  a  vertical  stud  of  3  mm.  diameter,  and  under  this  stud  the  gutta  percha 
is  plated  from  time  to  time  to  see  whether  any  permanent  impression  is  made. 
When  such  occurs,  the  temperature  of  the  water  is  recorded  as  that  at  which  the 
gutta  percha  begins  to  soften. 

The  action  of  heat,  says  Sherman,  in  softening  gutta  percha  and  making 
it  plastic,  has  previously  been  used  as  a  test  of  value.  It  has  been  found 
that  the  best  grades  require  a  higher  temperature  to  soften  them  than 
the  lower  grades.  According  to  the  results  obtained  by  him,  an  inferior 
grade  of  gutta  also  possessed  the  property  of  softening  at  a  lower  tempera- 
ture than  superior  gutta.  The  softening  point  was  determined  by  moulding 
a  piece  of  gutta  into  the  bottom  of  a  glass  tube  sealed  below,  placing  a 
sharp-pointed  glass  rod  in  contact  with  the  surface,  and  gradually  heating  in 
a  bath  of  sulphuric  acid  until  the  point  of  the  glass  rod  just  began  to  enter 
the  gutta. 

Determination  of  the  temperature  at  which  gutta  percha  becomes  pliable.* — A  strip 
of  the  gutta  percha  to  be  tested,  about  70  mm.  long,  25  mm.  wide,  and  2  mm. 
thick,  is  held  vertically  in  a  tall  water  bath.  The  upper  end  is  provided  with  a  clip, 
and  to  this  a  thin  cord  is  fixed,  which  passes  over  a  pulley  and  carries  a  half 
ounce  weight  at  the  other  end.  A  definite  pull  being  thus  exerted  on  the 
strip,  the  temperature  is  observed  at  which  this  pull  is  just  sufficient  to  tear  it 
asunder. 

Determination  of  t/ie  time  of  hardening  of  gutta  percha.1 — The  time  taken  by 
the  gutta  percha  to  become  sufficiently  rigid  to  resist  the  pressure  of  the  stud  in  the 
apparatus  used  for  'the  softening  temperature,  but  filled  with  water  kept  exactly 
at  75°  F.,  the  material,  which  is  in  the  form  of  a  2  mm.  plate,  having  previously 
been  heated  to  the  temperature  at  which  it  becomes  pliable.  The  time  of 
hardening  is  greatly  influenced  by  the  amount  of  resin  in  the  gutta  percha,  and 
the  variation  with  the  percentage  of  resin  can  be  represented  by  a  continuous 
curve. 

Action  of  atmospheric  agents. — Exposed  to  air  and  to  light,  gutta  percha  under- 
goes rapid  decay,  due,  to  all  appearance,  to  oxidation.  It  at  the  same  time  gives 
off  a  very  acrid  smell.  This  decay  is  more  rapid  when  the  substance  is  exposed  to 
the  air  at  a  temperature  of  25°  to  30°  C.  (77°  to  86°  F.)  in  thin  sheets  or  ribbons, 
and  if  it  be  moistened  frequently  and  then  left  to  dry  in  the  sun.  Gutta  percha 
does  not  perish  instantly  in  a  stream  of  ozonised  air,  like  indiarubber.  It  in  this 
way  becomes  brittle,  friable  'like  rosin ;  it  increases  in  weight  and  in  solubility  in 
alcohol  and  alkalies ;  and,  finally,  it  becomes  a  good  conductor  of  electricity, 
a  property  which  it  did  not  before  possess.  W.  A.  Miller  and  C.  Hoffmann 
(Ainmft-*  de  Chimie  et  de  Ph<irm<t<-l<;  215,  297)  attribute  this  change  to  oxidation. 
The  oxidised  portion  is  insoluble  in  water  and  benzine;  it  only  melts  at  100°  C. 
(212°  F.).  According  to  the  above  writers,  all  the  gutta  perchas  of  commerce 
contain  it  up  to  15  per  cent. 

1  Obach. 


356  GUTTA  PERCH A 

Tlie  following  is,  according  to  Miller,  the  composition  of  this  oxidised  resin  : — 
TABLE  XCIX. — ANALYSIS  OF  OXIDISED  PORTION  OF  GUTTA  PEROHA. 


Per  Cent. 

7615 

Hydrogen  .......... 
Oxygen      

11-16 
12-69 

100-00 

Gutta  percha  rendered  brittle  by  oxidation  in  air  and  light  may  be  reclaimed 
to  be  used  for  certain  purposes  if  digested  for  some  time  in  tepid  water,  and  then 
kneaded  again,  but  it  soon  cracks  and  becomes  useless  for  any  purpose.  Its 
tendency  to  deteriorate  in  contact  with  air  and  light  naturally  greatly  limits  the 
industrial  uses  of  this  substance.  K.  M.  Blossom  (Moniteur  Scientifique  de 
Quesneville,  iii.  Series,  t.  ix.  p.  240  et  seq.)  has  summarised  the  works  of  Clark  and 
W.  A." Miller  on  the  action  of  air  and  light  on  gutta  percha.  32 '35  grammes,  say 
an  ounce,  of  gutta  in  a  thin  sheet  were  successively  submitted  during  eight  months 
to  the  following  conditions  : — 

(1)  In  a  flask,  open  to  the  air,  but  protected  from  water;  (2)  in  a  flask,  open 
to  the  air,  but  kept  in  the  dark ;  (3)  in  soft  water,  in  the  open  air,  and  exposed  to 
light;  (4)  in  soft  water,  in  the  open  air,  but  protected  from  light;  (5)  in  soft 
water,  protected  from  air  and  light ;  (6)  in  salt  water,  in  the  open  air,  exposed  to 
light ;  (7)  in  salt  water,  in  the  open  air,  but  protected  from  light ;  (8)  in  salt 
water,  protected  from  air  and  light.  Samples  (3),  (4),  (5),  (6),  (7),  (8)  underwent 
no  change  except  a  slight  increase  in  weight,  due  to  absorption  of  water.  After 
being  exposed  to  air  for  two  hours  they  abandoned  the  water  absorbed,  and  the 
tenacity  and  structure  of  the  gutta  percha  were  not  altered.  No.  (1)  which  had 
been  rolled  up  and  run  on  into  an  inverted  flask,  with  its  mouth  open,  had  absorbed 
5  per  cent,  of  oxygen,  and  a  part  of  the  mass  (55  per  cent.)  was  converted  into  resin. 
The  outside  layers  exposed  to  light  were  resinous  and  brittle,  but  the  interior  portions, 
protected  from  light  by  the  outside  folds,  were  but  little  altered  either  in  texture  or 
appearance.  No.  (2)  had  suffered  little  or  no  change.  It  had  increased  -J  per  cent, 
only  in  weight,  and  only  ceded  7 '4  per  cent,  of  resinous  matter  to  alcohol. 

Another  sample,  only  exposed  to  light  for  two  months,  had  become  brittle, 
had  increased  3 '6  per  cent,  in  weight,  and  ceded  21 '5  per  cent,  of  resinous  matter 
to  alcohol,  whilst  another  sample  of  the  same  sheet  kept  in  darkness  had  undergone 
no  appreciable  modification.  It  thus  follows  that  it  is  the  oxygen  of  the  air, 
aided  by  sunlight,  which  acts  on  gutta  percha  so  as  to  profoundly  modify  its 
proximate  constitution.  The  extent  of  the  decay  varies  with  the  gutta  percha 
itself.  Every  step  taken  to  prevent  oxidation  is  therefore  a  useful  preventive 
against  the  destruction  of  the  gutta  percha.  Thus  Gerard  has  suggested  as  a 
preventive  the  incorporation  of  10  to  12  per  cent,  of  wax  or  tallow.  But  the 
only  process  hitherto  known  as  of  any  use  for  preventing  resinification  consists 
in  placing  this  substance  under  water.  Practically  it  is  indestructible  therein, 
and  there  is  not  a  single  example  of  a  submarine  cable  the  gutta  percha  of  which 
in  its  submerged  part  has  suffered  from  the  action  of  oxygen.  Certain  companies, 
therefore,  enclose  the  subterranean  lines,  constituting  the  continuation  of  the 
submarine  cables,  especially  in  hot  countries,  in  water  pipes  permanently  filled 
with  water,  by  means  of  reservoirs  placed  on  culminating  points  of  the  ground. 
In  dry  conduits,  where  the  cable  is  in  contact  with  air,  the  gutta  eventually  shrinks 
up,  becomes  friable,  and  leaves  the  copper  conductor  exposed.1  Edwin  Clark 
found  in  1852  that  in  the  purifying  gutta  percha  the  latter  unites,  mechanically, 

1  A  G.P.O.  collection  of  short  lengths  of  gutta  percha  covered  wires  which  had  been  used 
in  underground  street  cables,  and  showing  numerous  places  where  the  gutta  percha  had 
perished,  was  used  by  Obach  to  illustrate  his  Cantor  Lectures.— TR. 


PHYSICAL  AND  CHEMICAL   PROPERTIES 


357 


with  a  certain  quantity  of  water,  which,  under  the  influence  of  the  variations  of 
temperature  t<>  which gutta  percha  i-  i-xp-.-ed  during  tin-  process,  partially  evaporates, 
leaving  a  nn.iv  or  less  porous  resin.  A  good  gutta  j>ereha,  taken  from  a  eable  of 
recent  manufacture,  and  analysed  l.y  Miller  in  1860,  contained  I ."»  p.-r  Cent  of 
ivsin  and  •_'•.">  per  cent,  of  water.  Although  purification  processes  have  been  much 
perfected  since  then,  it  Mema,  fr-.m  «-x|M-rinieiits  made  in  1*7<>  by  Professor  Al><-l. 
that  as  iv^ards  the  oxidised  products  produced  at  the  expense  of  the  gutta  and 
the  interposed  water,  no  real  progress  had  been  made.  A  sheet  of  extra  fine  gutta 
percha  yielded  1  -j-7  per  cent,  of  resin  and  5  per  cent,  of  water.  These  proportions 
varied  respectively  between  L'<>  ;l,ul  27'5per  cent,  and  3  and  1:5  per  cent,  respectively, 
in  seven  other  samples  which  he  examined.  Classifying  them  afterwards  according 
to  their  commercial  value,  he  found  that  there  did  not  exist  any  direct  relation 
between  these  values  and  the  proportions  of  resin  and  water  contained  in  the  ^utta 
perchas  tested.  The  analyses  of  gutta  percha s  of  superior  quality  exj>osed  for 


FIG.  118.— Single  cable  (Hen- 
ley's). The  figure  illustrates  a 
single  cable  conductor,  0'9 
square  inch  area,  insulated  with 
one  coat  of  pure  Para  rubber  and 
two  coats  of  vulcanising  india- 
rubber  to  a  thickness  of  0'137 
inch,  taped,  braided,  and  com- 
pounded, suitable  for  a  working 
pressure  of  660  volts  ;  guar- 
anteed minimum  insulation 
resistance  between  the  con- 
ductor and  earth,  2500 
megohms  per  mile. 


Fie.  119.— Section  of  Anglo- Belgian  Tele- 
phone cable  (four  core  submarine  cable) 
constructed  by  Henley's.  The  figure 
illustrates  a  section  of  a  four  core  sub- 
marine cable  manufactured  for  the 
General  Post  Office  (usually  known 
as  the  Anglo-Belgian  Telephone  cable), 
and  was  laid  between  St.  Margaret's 
Bay,  England,  and  La  Panne,  Belgium. 
Total  length  of  cable  about  48  knots  ; 
weight  of  conductor  per  knot,  160  Ib.  ; 
weight  of  guttii  percha  per  core  per 
knot,  300  Ib.  ;  thickness  of  gutta  percha 
on  each  core,  0'145  inch  ;  inductive 
capacity  per  knot,  0'275  microfarads. 


several  years  to  air  and  light  show  that  oxidation  caused  thereby  only  proceeds 
slowly  when  the  gntta  percha  lias  been  rendered  sufficiently  compact  by  prolonged 
mastication.  To  prevent  its  decay,  gutta  percha  has  been  varnished  in  the  case 
of  gnu-impressions,  and  it  has  been  suggested  to  treat  it  with  a  4  per  cent,  solution 
of  formaldehyde  (in  the  case  of  museum  specimens).  The  proportion  of  interposed 
water  enables  the  approximate  state  which  the  sample  has  reached  in  this  respect 
to  lie  a-Mvrtained.  Moreover,  this  transformation  or  oxidation  does  not  take  place 
in  a  constant  manner.  whiUt  certain  article-  iv-ist  all  deterioration,  other  .-amples, 
submitted  to  the  same  condition.  so  far  peri-li  as  to  crumble  to  dust  as  soon  as 
touched.  This  anomaly  is  easily  explained,  it'  we  consider  that  the  commercial 
gutta  peivhas  used  in  the  ex|icrimenN  are  essentially  of  variable  composition,  and 
never  come  (\\e  may  Imldly  atiirni)  either  from  the  >ame  plant,  or  even  from 
a  mixture  in  identical  proportions  of  different  species  of  gutta  perchas.  The 
elementary  compositions  of  these  resins  were  studied  by  Hoffman  and  Miller, 
but  their  results  do  not  agree. 


358 


GUTTA   PERCHA 


TABLE  C. — ELEMENTAKY  ULTIMATE  COMPOSITION  OF  GUTTA  PERCHA 
(HOFFMAN  AND  MILLER). 


Carbon. 

Hydrogen. 

Oxygen. 

Hoffmann 

62-79 

9-29 

27-92 

100-00 

Miller     . 

76-15 

11-16                12-69 

100-00 

Gutta  percha  is  preserved  indefinitely  when  immersed  in  water,  more  par- 
ticularly in  sea  water  Nevertheless,  time  finished  by  getting  the  better  of  this 
substance,  unattackable  by  the  chemical  agents  held  in  solution  in  sea  water. 
Another  enemy  came  to  replace  them,  namely,  the  minute  organisms  which  live  in  the 
sea.  When  a  copper  wire  covered  with  gutta  percha  is  laid  on  the  bottom  of  the 
sea,  it  must  be  protected  as  shown  in  Figs.  120  and  121.  The  least  injurious  of  the 
organisms  which  attack  gutta  percha  is  the  Teredo  navalis.  The  Teredo  navalis 
is  a  sort  of  worm,  of  a  greyish  colour,  belonging  to  the  genera  of  acephalous 
mollusca,  which  sometimes  attain  30  cms.  (say  a  foot)  in  length.  It  is  said 
that  animals  of  the  teredo  genus  attack  gutta  percha  no  further  than  to  taste  it, 
and  facts  would  seem  to  affirm  this  assertion.  During  repairs  to  the  Dover  to 


IRON  SHEATHING 
TAPE  ON  WIRE. 


TANNED  JUTE 


COPPER  CONDUCTOR 
CUTTA  PERCHA 


TAPE 


DEEP  SEA  TYPE 

FIG.  120.— Submarine  cable.     Cross-section,  showing  arrangement,  nature,  and  con- 
struction of  the  different  layers. 

Calais  cable  in  1851,  it  was  found  that  the  hemp  had  completely  dissappeared  in 
all  those  points  where  the  corrosion  of  the  iron  was  discovered;  but  the  core 
was  only  perforated  by  two  holes  penetrating  to  the  copper  wire.  But  all  the 
ends  of  the  Dover  to  Calais  experimental  cable  which  have  been  brought  up  from 
the  sea  up  to  now  have  been  found  without  the  least  trace  of  any  animal  attack 
whatever.  Now  this  cable  only  consisted  of  a  copper  wire  covered  with  gutta 
percha  without  any  exterior  protection  whatever. 

TABLE  CI. — CLASSIFICATION  OF  SUBMARINE  CABLES,  LENGTH  OF  CORE,  AND 
WEIGHT  OF  GUTTA  PERCHA  (OBACH). 


No.  of 
Group. 

Description  of  Cables. 

Approximate 
Length  of 
Core. 

Approximate 
Weight  of 
Gutta  Percha. 

I. 

Trans-oceanic         .         .         . 

Nautical  miles 
(Knots). 

42  000 

Tons. 
6  000 

II. 
III. 

IV. 

Round  coasts  of  America 
Round  east  and  west  coasts  of  Africa 
Round  coasts  of  Europe  and  Asia,  and  to 
Australia    ...... 

41,000 
18,000 

83,000 

2,600 
1,200 

"6,200 

Total 

184,000 

16,000 

PHYSICAL  AND  CHEMICAL  PROPERTIES 


359 


The  A//// //••/•/./  Iniiinriiin  nr  t<ii>  ///••///>•,  tin-  IIIM-I  n-iluiihtablu  enemy  of  gutta 
percha,  i>  a  Mii.tll  crustiuvaii  of  tin-  si/,-  ..fan  ant,  \\liidi  easily  >lijis  |M-I\M-.MI  tin- 
narrowest  int<T-ti.Ts  left  lu-tucni  tin-  \\in-s  (»f  tin-  armature,  SO  as  to  get  at  the 


CONDUCTOR 


ROCK   TYPE 


FIG.  121.— Submarine  cable.     Cross-section  showing  arrangement,  nature,  and  con- 
struction of  different  layers. 


CONDUCTOR    7  COPPER  WIRES 
INNER  IRON  SHEATHING 
TARRED  JUTE  SERVING 
TARRED  JUTE  SERVING 


TANNED  JUTE 
CUTTA  PFRCHA 
OUTER  IRON  SHEATHING 


SHORE  END 
Fit;.  122.— Submarine  cable.     Cross-section  showing  nature  and  construction  of  different  layers. 


360 


GUTTA  PERCHA 


core,  which  it  perforates  from  point  to  point.  Its  head  is  armed  with  five  or  six 
pairs  of  hooks ;  its  feet,  like  those  of  the  lobster,  are  attached  to  the  first  six  rings 
of  its  body.  The  latter  likewise  carries  a  pair. 

On  land  gutta  percha  is  still  exposed  to  attack  by  other  animals,  e.g.  rats, 
whose  ravages  in  sewers  are  well  known,  and  the  Templetonia  cristallina,  a 
microscopic  insect  of  the  Podura  family.  The  wires  may  be  preserved  by 
embedding  them  covered  with  gutta  percha  in  cement.  Like  all  hydrocarbides 
with  a  high  coefficient,  gutta  percha  is  extremely  inflammable,  burns  with  a 
bright  flame,  emitting  sparks,  allowing  a  black  residue  to  drop,  after  the  manner 


FIG.  123.— Lead  press  forcovedng  electric  cables  and  for  making  lead  pipes. 

of  sealing-wax,  which  it  resembles  in  the  way  it  burns.  It  is  a  bad  conductor  of 
heat,  but,  as  it  is  very  impressionable  under  ever  so  slightly  elevated  a  temperature, 
this  property  has  not  been  utilised  either  by  science  or  by  industry.  Gutta  percha 
as  an  electrical  insulator  is  likewise  so  bad  a  conductor  of  electricity  that  it  is  justly 
regarded  as  the  dielectric  plastic  substance  par  excellence.  It  is  rapidly  electrified 
by  rubbing,  and  the  too  brittle  glass  disc  in  electro-static  machines  was  therefore 
replaced  by  one  of  gutta  percha,  equally  good  and  much  less  fragile.  Unfortunately, 
these  discs,  in  time,  as  they  resinified  in  contact  with  the  air,  split,  and  the 
advantage  of  the  first  few  hours  became  a  serious  drawback.  Rubbed  with  glass, 
wool,  etc.,  gutta  percha  becomes  electro-negative.  However,  according  to  Ries, 


PHYSICAL  AND  CHEMICAL   PROPERTIES 


361 


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362  GUTTA  PERCHA 

when  gutta  percha,  which  has  been  left  for  some  time  exposed  to  the  open  air,  and 
thus  acquired  a  peculiar  greyish  blue  coloration,  is  so  rubbed,  it  becomes  electro 
positive.  Freed  from  this  coloured  layer  by  washing  with  ether  or  spirits  of 
turpentine,  if  rubbed  with  wool  or  glass  it  rebecomes  electro-negative,  whilst 
unwashed,  in  the  same  conditions,  electro-positive.  By  rubbing  gently  with  a  piece 
of  silk,  sparks  of  0'025  metre  (say  1  inch)  in  length  may  be  obtained.  Faraday 
in  1843  was  the  first  to  point  out  the  insulating  property  of  gutta  percha,  and  to 
forsee  the  application  which  might  be  made  of  this  substance  as  a  dieletric.1  This 
remarkable  property  is  not  lessened,  even  in  those  atmospheric  conditions,  when 
glass  becomes  a  good  conductor.  Sunk  under  water,  and  in  the  ground,  in  spite 
of  deteriorating  causes  of  all  kinds  of  moisture,  of  mould,  and  even  of  insects,  gutta 
percha  preserves  intact  its  highly  remarkable  insulating  properties.2  The  insulating 
power  of  gutta  percha,  or  the  resistance  which  this  substance  presents  to  the 
passage  of  the  electric  current,  measured  relative  to  copper  taken  as  unity, 
according  to  Wunschendorff,  all  dimensions  being  equal,  at  a  temperature  of  24°  C. 
(75°'2  FA  is  approximately  60,000,000,000,000,000,000  or— 

6  x  1019. 

An  idea  of  the  magnitude  of  this  number  may  be  got  by  remarking  that  light, 
the  speed  of  which  is  about  77,000  leagues  per  second,  would  take  longer  than 
six  thousand  years  to  traverse  the  distance  which  this  number  would  express  in 
metres. 

Obach  demonstrated  the  two  principal  electrical  properties  of  gutta  percha 
experimentally.  He  took  an  electroscope  with  a  flat  brass  disc  at  the  top  and  two 
pith  rods  underneath,  suspended  on  either  side  of  a  fixed  strip  of  brass.  A  thin 
piece  of  gutta  percha  is  spread  over  the  brass  disc  like  a  tablecloth,  and  on 
charging  the  electroscope  by  aid  of  the  brass  knob  at  the  side,  the  pith  rods  diverge 
and  remain  stationary.  On  laying  the  fingers  on  the  top  of  the  disc  so  that  they 
are  separated  from  it  by  the  gutta  percha  tissue,  the  rods  slightly  converge  and 
then  remain  stationary.  On  withdrawing  the  hand  they  again  take  up  their 
former  position.  This  simple  experiment  demonstrates  simultaneously  the  two 
electrical  properties  of  gutta  percha.  The  fact  that  the  hand  (which  through  the 
body  is  connected  with  the  earth)  could  be  held  on  the  upper  side  of  the  thin 
tissue  for  a  considerable  time  without  discharging  the  electroscope,  shows  its 
excellent  insulating  quality,  and  the  binding  of  the  electrical  charge  of  the  disc  of 
the  electroscope,  indicated  by  the  temporary  partial  collapse  of  the  pith  rods  whilst 
the  hand  rests  on  the  tissue,  showing  the  inductive  capacity  of  the  gutta  percha. 
The  insulation  should  be  as  high  as  possible,  and  the  inductive  capacity  generally 
as  low  as  possible ;  but  as  the  inductive  capacity  is  generally  accompanied  by 
other  good  qualities  in  the  gutta  percha,  etc.,  such  is  not  always  the  case  with  a 
high  insulation.  Obach  further  points  out  that  Faraday  had  some  difficulty  in 
1848  in  obtaining  gutta  percha  with  a  sufficiently  good  insulation  for  his  purpose, 
and  he  found  that  this  was  due  to  an  excess  of  water  in  the  commercial  article. 
Obach  demonstrated  the  effect  of  water  in  gutta  percha  on  its  insulating  proper- 
ties, by  taking  some  strips  containing  about  15,  10,  5,  and  2J  per  cent,  of  water 
respectively.  On  charging  the  electroscope,  and  on  touching  the  brass  knob  with 
the  strip  containing  15  per  cent,  of  water,  and  on  pressing  the  finger  against  the 
other  side,  the  pith  rods  gradually  converge,  but  as  they  do  not  regain  their 
former  position  when  the  strip  is  removed,  it  shows  that  the  charge  has  been  dis- 
sipated by  contact  with  the  gutta  percha.  Repeating  the  experiment  with  the 
charge  containing  15  per  cent.,  the  charge  disappears  much  more  slowly,  whilst  the 
5  per  cent,  sample  is  found  to  be  a  good  insulator,  equal  in  fact  to  that  with 
2J  per  cent,  water.  But  different  kinds  of  gutta  perchas  behave  differently  in 
that  respect. 

The  different  natural  gutta  perchas  have  different  properties,  and  mix  superior 

1  Obach  gives  the  date  of  Faraday's  researches  as  1848,  and  those  of  Werner  Siemens,  who 
would  thus  have  the  prior  claim,  as  1846. 

2  Decaying  organic  matter  also  acts  injuriously  (Obach). 


PHYSICAL  AND  CHEMICAL   PROPERTIES 


363 


fibrous  gutta,  i>erchas  of  givatrr  durability  and  greater  mechanical  resistance  with 
interior  guttas  of  considerably  greater  insulating  capacity,  ami  a  less  electro-static 
capacity.  Itiv-ulK  thrivfi.iv,  that  tin-  insulating  resistance  and  tin-  >jM-citic  electro- 
static capacity  of  gutta  privha,  brought  to  unity  of  volume,  varies  between  certain 
limits,  ami  ou^ht  to  I..-  ilcti-nninr.l  in  each  particular  case.  Moreover,  the  gutta 
l>t  ivhasof  commerce  being  mi \tun-s  (jf  natural  guttas,  the  makers  of  electric  cables, 


to 

I 

8 

-2 

I 

71 


to  ascertain  tin-  exact  valin-  of  tin-  ^utta  |»rn-ha  \\liicli  tliry  luiy,  «>r  \vliidi  tlu-y 
propose  t..  us,-,  mils!  makr  about  ")00  im-tivs  (1640  feet)  of  core  \\ith  the  gutta 
percna  from  each  lot^fad  afterwards  study  it>  rlrctrical  prujM-rtii-s.  Tlie  insulatini: 
resistance  R  of  any  uri\'-n  ilirln-triral  annular  cylimlor  is  n-jnvsontod  by  the 
formula — 

A  log  7 


364 


GUTTA   PERCHA 


in  which  A  indicates  a  constant,  D  and  d  the  exterior  and  interior  diameters  of  the 
cylinder,  L  its  length.  For  a  gutta  percha  cable  we  get  approximately  per  knot— 

R  =  750  log  —megohms,  at  the  end  of  a  minute  of  electrisation,  and  after  twenty- 

Cl 

four  hours'  immersion  in  water  at  24°  C.  (75°'2  F.).  With  recently  made  cables, 
the  value  of  A  may  be  less  than  two-thirds  of  that  given  above.  The  insulating 
resistance  of  gutta  percha  diminishes  as  rapidly  as  the  temperature  rises.  The  law 
of  variation  is  represented  by  the  formula  — 


in  which  R  and  r  respectively  represent  the  lowest  and  the  highest  of  the  two 
temperatures  the  difference  of  which  is  t  degrees  and  A  a  constant.  The  coefficient 
A  should  be  determined  for  each  quality  of  the  gutta  percha  of  commerce.  If  t  be 
expressed  in  °C.,  the  value  of  A  for  average  quality  gutta  is  about  0'87604.  We 
then  get  —  log  R  =  log  r  +  log  0*87604.  Table  GUI.  affords  an  idea  of  the  varia- 
tion of  the  resistance  of  gutta  percha  at  different  temperatures,  but  cannot  be 
applied  with  any  precision  to  any  and  every  species  of  gutta  percha  (J.  Munro  A. 
Jamieson's  Pocket  Book,  1885).  Pressure  increases  the  resistance  of  gutta  percha  : 

TABLE  GUI.  —  VARIATIONS  IN  THE  RESISTANCE   OF  ORDINARY  GUTTA  PERCHA 
AT  DIFFERENT  TEMPERATURES  (MUNRO). 


Temperature. 

Relative 
Resistance. 

jogarithms  of  the 
Resistance. 

Temperature. 

Relative 
Resistance. 

Logarithms  of  the 
Resistance. 

•F. 

°c. 

•F. 

-a 

32 
33 

o-o 

0-5 

23-622 
21-947 

1,373,317 
1,341,375 

67 
68 

19-4 
20-0 

1-801 
1-673 

0,255,516 
0,223,496 

34 

1-1 

20-391 

1,309,439 

69 

20-5 

1-555                  0,191,730 

35 

1-6 

18-945 

1,277,495 

70 

21-1 

1-444 

0,159,567 

36 

2-2 

17-602 

1,245,562 

71 

21-6 

1-342 

0,127,753 

37 

2-7 

16-354 

1,213,624 

72 

22-2 

1-247 

0,095,867 

38 

3-3 

15-995 

1,181,701 

73 

22-7 

1-158 

0,063,709 

39 

3-8 

14-117 

1,149,742 

74 

23-3 

1-076 

0,031,812 

40 

4-4 

13-116 

1,117,801             75 

23-8 

1-000 

0,000,000 

41 

5-0 

12-188 

1,085,861             76 

24-4 

0-9418 

1,973,959 

42 

5-5 

11-322 

1,053,923 

77 

25-0 

0-8870 

1,947,924 

43 

6-1 

10-520 

1,022,016 

78 

25-5 

0-8354                1,921,895 

44 

6-6 

9-774 

0,990,072 

79 

26-1 

0-7867                1,895,809 

45 

7-2 

9-081 

0,958,134 

80 

26-6 

0-7410                1,869,818 

46 

77 

8-437 

0,926,188 

81 

27-2 

0-6978 

1,843,731 

47 

8-3 

7-839 

0,894,261 

82 

27-7 

0-6572 

1,817,698 

48 

8-8 

7-283 

0,862,310 

83 

28-3 

0-6190                l,79l',681 

49 

9-4 

6-767 

0,830,396 

84 

28-8 

0-5829                1,765,594 

50 

10-0 

6-287 

0,798,444             85 

29-4 

0-5490 

1,739,572 

51 

10-5 

5-841 

0,766,487 

86 

30-0 

0-5171 

1,731,575 

52 

11-1 

5-427 

0,734,560 

87 

30-5 

0-4870 

1,687,529 

53 

11-6 

5-042 

0,702,603 

88 

31-1 

0-4586 

1,661,434 

54 

12-2 

4-685 

0,670,710 

89 

31-6 

0-4319 

1,635,383 

55 

12-7 

4-353 

0,638,789 

90 

32-2 

0-4068 

1,609,381 

56 

13-3 

4-044 

0,601,811 

91 

32-7 

0-3831 

1,583,312 

57 

13-8 

3-757 

0,574,841 

92 

33-3 

0-3608 

1,557,267 

58 

14-4 

3-491 

0,512,950 

93 

33-8 

0-3398 

1,531,223 

59 

15-0 

3-244 

0,511,081 

94 

34-4 

0-3000 

1,505,150 

60 

15-5 

3-013 

0,478,999 

95 

35-0 

0-3014 

1,479,143 

61 

16-1 

2-800 

0,447,158  ' 

96 

35-5 

0'2^fc9 

1,453,165 

62 

16-6 

2-601 

0,415,140 

97 

36-1 

0-2674 

1,407,161 

63 

17-2 

2-417 

0,383,277 

98 

36-6 

0-2518 

1,401,051 

64 

17-7 

2-245 

0,351,216 

99 

37-2 

0-2371 

1,374,932 

65 

18-3 

2-086 

0-319,314 

100 

37-7 

0-2233 

1,348,889 

66 

18-8 

1-938 

0,287,354 

PHYSICAL  AND   CHEMICAL   PROPERTIES 


365 


if  we  indicate  by  /•  its  resistance  to  atinnsplierif  piv-smv,  by  11  in  iv>i<tanee  to 
tin-  pressure  p  expressed  in  kilogramme-  \»-\-  >i|iuiv  centimetre.  \\e  get  —  R  =  r 
(1+0-00327  //).  The  >|>e.-itic  electro-static  capacity  of  guttti,  relative  to  that 
-I  air,  taken  as  unity,  is  almiit  \"2.  The  capacity  <'  of  an  annnl.tr 
exterior  and  interim-  diameter  l>  ami  ./  i>  eXpPBiied  l»v  tin-  ratio— 


log 


tl 


L  representing  the  length  of  the  cylinder  ;  A  being  a  constant.     For  a  gutta  pereha 
ruble  we  get  aj>jn-»i-ii"'it''ly  per  marine  mile 


0-18769 

D 
10g  d 


microfarads. 


The  constant  0*18769  varies  with  the  quality  of  the  gutta  percha. 

ll,f<it'i>'.  nMMfcmca  (after  a  minute  of  electrisation)  at  di/<i-<-nt  temperatures  of 
Ordinary  <jntt<i  jxrcka  <i*  m/vx  ///  a'/n'r/i  flic  tlt'u'km-nx  of  f//>'  </nff<i  j»r<-lt<i  </^-x  m,t 
exceed  2'7D  mi  Hi  metres  (-f-f  of  an  inch)  (Willoughby  Smith). 

The  weight  of  gutta  j>ercha  necessary  to  obtain  a  core  of  diameter  Z),  with  a 
conductor  of  diameter  d,  D  and  d  both  being  expressed  in  millimetres,  is  about — 

1-43  (D2— d2)  kilogrammes. 

Dielectric  Strength — An  important  electrical  property,  which  has  recently  come 
into  prominence,  is  what  is  called  the  dielectric  strength  or  resistance  to  piercing  by 
high  voltages.  Table  CIV.  gives  the  dielectric  strength  of  various  gutta  percha- 
covered  wires  (cores),  and  the  corresponding  thickness  of  the  insulating  material 
or  dielectric;  it  also  gives  for  comparison  the  dielectric  strength  of  caoutchouc- 
covered  wires  and  of  ebonite.  A  thickness  of  a  little  over  -J-  inch  of  gutta  percha 
breaks  down  with  40,000  volts,  and  one  of  about  ^  inch  with  28,000  volts. 

TABLE  CIV. — COMPARATIVE  DIELECTRIC  STRENGTH  OF  GUTTA  PERCHA 
CAOUTCHOUC  AND  EBONITE  (OBACH). 


Nature  of  Dielectric. 

Thickness  of 
Dielectric  in 
decimals  of 
an  inch. 

Voltage 
at  which 
Dielectric 
broke  down. 

GUTTA  PERCHA  — 

Copper               G.  P. 

per  knot           per  knot 

Ib.                     Ib. 

/         500                   320 

0-127 

40,000 

Cores    of    various           450                    280 

0-109 

28,000 

sizes  from  SuW         107                   150 

0-0925 

18,000 

marine  Cables.              107                    130 

0-0825 

15,000 

130                    130 

0-0805 

14,000 

fPahang 

0-051 

19,000 

KmjcrRed. 

0-058 

20,000 

Test  core,  n,ade  Ho,,,    i^;^;;,,!;t     | 

0-048 
0-049 

19,000 
15,000 

Serapong  Soondie 
HJ.  P.  from  leaves 

0-054 
0-047 

18,000 
17,000 

CAOUTCHOUC— 

Core  of  Overland  Telegraph  Cable  .... 

0-102 

20,000 

Core  of  Submarine  Cable          .... 

0*078 

19,000 

EBONITE  (Sheet)—     

0-130 

38,000 

366  GUTTA   PERCHA 

Action  of  solvents. — Gutta  percha  resists  most  solvents.  It  is  completely 
insoluble  in  cold  water,  softens  in  boiling  water  and  in  steam ;  it  none  the  less 
remains  quite  entire,  whatever  may  be  the  temperature  of  the  water  vehicle,  and  is 
preserved  almost  unalterable  therein.  Gutta  percha,  however,  swells  in  boiling 
water,  and  absorbs  about  5  to  6  per  cent.,  which  it  afterwards  only  parts  with 
slowly  when  left  to  itself.  But  if  it  be  heated  to  150°  C.  (302°  F.)  in  the  swollen 
hydrated  condition,  it  rapidly  abandons  its  interstitial  water  without  undergoing 
any  constitutional  change.  It  is  almost  insoluble  in  cold  weak  alcohol,  its 
solubility  augments  with  the  increase  of  alcoholic  strength  and  on  heating,  and 
if  it  be  boiled  in  absolute  alcohol,  it  loses  about  15  to  20  per  cent,  of  oxidised 
resinous  bodies.  If  ether  only  dissolves  a  small  quantity  of  gutta  percha  (Payen),  it 
dissolves  completely  therein  provided  the  ether  be  absolutely  pure,  i.e.  free  from 
alcohol  (Arpe).  Ether  containing  even  a  small  quantity  of  alcohol  loses  the 
property  of  completely  dissolving  gutta  percha.  It  dissolves  partially  in  hot  spirits 
of  turpentine,  shale  oil,  olive  oil,  and,  better  still,  in  benzine.  The  best  solvents 
are  carbon  disulphide  and  chloroform.  These  solvents  do  not  cause  it  to  swell  like 
rubber.  Solution  takes  place  gradually  from  the  surface  to  the  interior.  The 
cloudy  liquids  so  obtained,  after  nitration,  become  perfectly  limpid  and  colourless. 
By  evaporating  the  solvents,  the  pure  gutta,  percha  so  obtained  has  the  appearance 
of  virgin  wax.  Hot  solutions  deposit  gutta  percha  in  clots  on  cooling :  alcohol 
precipitates  it  from  this  solution,  but  the  precipitated  product  often  retains  traces 
of  the  solvent  used,  especially  benzine  between  its  pores,  which  renders  it  tacky. 

Action  of  reagents — Gutta  percha  bottles' alone  stand  hydrofluoric  acid. — Concen- 
trated alkaline  solutions,  dilute  acid,  even  hydrofluoric  acid  itself,  are  without 
action  upon  gutta  percha,  and  it  was  the  researches  of  Staedeler  on  this  point 
(published  in  the  Annales  de  Chimie  et  de  Pharmacie,  Ivii.  p.  137),  which  gave  birth 
to  the  gutta  percha  bottle  industry  for  the  transport  and  storage  of  fluoric  acid  in 
the  liquid  state.  Concentrated  sulphuric  acid  dissolves  gutta  percha,  colouring  it 
brown,  and  disengaging  sulphurous  acid.  Nitric  acid  attacks  it,  producing  nitrous 
fumes,  and,  according  to  Oudemans,  the  products  of  the  reaction  consist  of  formic 
and  hydrocyanic  acids.  Very  concentrated  hydrochloric  acid  likewise  attacks  it 
eventually.  According  to  Berthelot1  (Bulletin  de  la  Socie"te  Chimique,  1869,  xi.  p. 
33),  one  part  of  gutta  percha,  as  pure  as  possible,  heated  to  280°  C.  (536°  F.),  with 
80  parts  of  hydriodic  acid,  produces  complete  hydrogenation  of  the  substance.  It 
yields  saturated  carbides  (paraffins),  boiling  at  a  very  high  temperature. 

Having  examined  the  product  of  this  reaction,  Berthelot  ascertained  that  it  did 
not  contain  any  hydrocarbide  volatile  at  a  low  temperature,  nor  any  carbide  volatile 
below  360°  C.  (688°  F.).  It  is  a  viscous  matter,  rather  similar  to  fused  rubber, 
which  obstinately  retains  interposed  water.  When  heated  it  swells  much,  and  in 
an  explosive  manner,  as  the  water  is  being  disengaged.  But  the  water,  in  evaporat- 
ing, does  not  carry  along  with  it  any  volatile  hydrocarbide.  When  the  water  is 
entirely  eliminated,  the  temperature  may  be  raised  to  350°  C.  (662°  F.)  without 
any  carbide  distilling,  and  it  is  only  by  still  furthur  raising  the  temperature  that  it 
finally  distils,  but  without  undergoing  apparent  decomposition.  The  carbide  thus 
obtained  presents  the  reactions  of  the  formenic  carbides  (paraffins) :  resistance  to 
bromine,  to  fuming  and  cold  nitric  acid,  to  fuming  and  lukewarm  sulphuric  acid. 

Chemical  composition. — Commercial  gutta  percha,  even  when  absolutely  pure, 
is  not  a  simple  substance  the  elementary  principles  of  which  one  can  study  forth- 
with. It  consists  of  several  proximate  principles  in  more  or  less  variable  propor- 
tion, according  to  its  botanical  origin  and  the  different  manipulations  it  has  under- 
gone. It  is  therefore  impossible  to  examine  its  chemical  composition  before 
demonstrating  (1)  the  method  of  preparing  chemically  pure  gutta  percha,  and  the 
process  (2)  of  separating  its  known  proximate  principles.  Payen  commenced  the 
preparation  of  the  pure  substance  by  dissolving  raw  gutta  percha  in  carbon 
disulphide,  filtering  and  evaporating  it  in  the  air  on  a  marble  or  glass  slab  without 

1  See  Preface  to  second  English  Edition  for  translator's  justification  of  the  chemical  termin- 
ology used  here. 


PHYSICAL  AND  CHEMICAL   PROPERTIES 


367 


amalgam.     After   complete  desiccation,   tin-   plates   of  purified  gutta  percha   are     \ 
.letadie,!  ami  covered  with  cold  \\atrr,  \\hicli  stops  the  tackiness  in  a  few  «^«^«*- • 
100  parts  of  gutta  pnvha  SO  treated  gave  the  following  results 


T.\ i-.i.i   CV,     RESULTS  01   ANALYSIS  OF  GUTTA  i'i  i;«  \\  \  r.\   PATBM 

Mi  1 111  n>  i  Mn  i  IK). 


ant 

Purified  gutta  percha 

1!<  --ins 
t.iMr  lil.iv 
Water       . 
Ash. 

7'.'-7'i 
15-10 
2*16 
2'50 
0'52 

, 

100-00 

From  a  gutta  percha  so  purified  Arpe  extracted  seven  different  resins,  which 
present i'«l  pmvptible  variations  in  solubility  in  ether,  and  in  alcohol  of  different 
stivn-ths  and  temperatures.  Arpe  gave  formulae  for  the  composition  of  these 
resins  which,  moreover,  are  absolutely  hypothetical,  as  saline  compounds  of  these 
resins  which  would  enable  their  atomic  weight  to  be  fixed  are  unknown.  Payen, 
by  treating  gutta  percha,  purified  as  above  by  cold  alcohol,  then  by  boiling 
alcohol,  has  shown  that  there  existed  therein  three  quite  distinct  proximate 
principles  in  the  following  average  proportion  : — 

1.  Gutta  (insoluble  in  cold  alcohol  and  in  boiling  alcohol),  78  to  82  i*-r 
cent.  L\  Mnavile  (insoluble  in  cold  alcohol),  4  to  6  per  cent.  3.  Allans  (solublr 
in  boiling  alcohol),  14  to  16  per  cent.  To  isolate  each  principle,  the  |>mitir<l 
gutta  i>ercha  is  treated  for  several  hours  with  boiling  alcohol,  and  filtered.  The 
alcoholic  solution  deposits,  after  standing  for  one  or  two  days,  an  abundant  granula- 
tion of  white  opalescent  matter,  forming  a  nucleus,  soluble  in  absolute  alcohol 
(amorphous  yellow  substance),  whilst  the  exterior  envelope  is  insoluble,  and 
becomes  more  and  more  white  and  diaphanous.  By  repeatedly  washing  the 
granulated  mass  with  cold  alcohol,  the  fluavile  is  dissolved,  whilst  the  albane 
remains  insoluble.  After  having  repeatedly  boiled  the  gutta  percha  in  alcohol, 
then-  remains  the  chemically  pure  substance  called  by  Payen  gutta. 

Obach  hardens  gutta  percha  by  dissolving  it  in  j>etroleum  ether,  and  then 
cooling  to  60°  F.  The  gutta,  or  hardened  gutta  percha,  is  precipitated  whilst  the 
albane,  fluavile,  etc.,  remain  in  solution  (see  p.  386). 

TAHLE  CVI. — CHEMICAL,  PHYSICAL,  MECHANICAL,  AND  ELECTRICAL  PROPERTIES 
OF  HARDENED  GUTTA  PERCHA  (OBACH). 


G. 

R. 

D. 

w. 

G 
~R 

Id 

~0 

!• 

a 

'*  i 

3  .2 

e   3 

^    C 

if* 

If 

l| 

•3  I3 

ftl 

I- 

£ 

WS 

Hfi| 

ii 

s  £ 

—     — 

"^  ca  i; 
^°'2 

A 

54-7 

39-4 

2*7 

3-2 

1-4 

377 

58-8 

17 

1592 

860 

34,970 

•0613 

B 

93'0 

2-8 

2-6 

T7 

33'2 

57'2 

91-1 

I 

5662 

285 

27,410 

•0575 

C 

97-3 

1-2 

0-3 

1-2 

78-5 

58-3 

'.'  1  •  1 

1| 

8757 

380 

6,640 

•0471 

D 

'.'1-1 

1  "J 

•'•ii 

27 

78'4 

60-5 

'.HIM) 

5937 

125 

10,030 

•0608 

E 

94-9 

0-8 

2-2 

2-1 

120-0 

61-6 

93-3 

1 

5008 

8,350 

•0588 

A  =  Medium  quality  cleaned  in  ordinary  way ;  B  =  same  material  hardened  by  extracting 
the  resin  ;  C,  D,  E,  various  other  materials  harden< 


lened  by  extracting  the  resin. 


368 


GUTTA   PERCHA 


Fluavile  is  a  yellowish  diaphanous  resin,  a  little  heavier  than  water ;  it  is  hard 
and  brittle  at  0°  C.  (32°  F.),  softening  towards  50°  C.  (122°  F.),  becoming  pa-sty 
at  60°  C.  (140°  F.)  [at  42°  C.  (105'6°  F.)  according  to  Oudemans],  and  completely 
fluid  at  100°  to  110°  C.  (212°  to  230°  F.).  It  is  decomposed  at  a  higher  tempera- 
ture into  different  badly  defined  hydrocarbides.  It  is  soluble  in  the  cold  state  in 
alcohol,  ether,  benzine,  spirits  of  turpentine,  carbon  disulphide,  chloroform. 
When  the  solvents  evaporate,  amorphous  fluavile  is  deposited.  It  resists  dilute 
and  concentrated  acids  and  alkaline  liquids,  but  is  rapidly  destroyed  by  sulphuric 
and  nitric  acids.  Its  composition  was  determined  by  Oudemans  (Rep.  de  Chimie 
appliquee,  1858-59,  p.  455).  It  yields1— 

TABLE  CVIL — ELEMENTARY  COMPOSITION  OF  FLUAVILE  (OUDEMANS). 


I. 

II. 

Carbon  ....... 
Hydrogen      
Oxygen          ...... 

Per  cent. 
83-36 
11-17 
5-47 

Per  cent. 
83-52 
11-42 
5-06 

100-00 

100-00 

and  thus   corresponds  with  the  formula   C20H32O.     Fluavile   is  thus    simply   an 
oxidation  derivative  of  gutta. 

Albane  is  a  white  crystalline  lenticular  resin ;  examined  under  the  microscope, 
it  appears  as  diaphanous  radiated  follicles.  It  is  heavier  than  water,  only  melts 
at  160°  C.  (320°  F.)  [140°  C.  (284°  F.),  Oudemans];  not  acted  on  by  hydrochloric 
acid.  It  is  soluble  in  benzene,  spirits  of  turpentine,  carbon  disulphide,  ether, 
chloroform,  and  boiling  anhydrous  alcohol.  100  parts  of  cold  alcohol  dissolve 
5'1  parts  and  54  parts  on  boiling.  It  crystallises  out  on  cooling  from  its  solutions. 
The  following  is  its  composition  : — 

TABLE  CVIII. — ELEMENTARY  COMPOSITION  OF  ALBANE.  (OUDEMANS). 


I. 

II. 

Carbon  ..... 

Per  cent. 

78  '87 

Per  cent. 

78  '95 

Hydrogen      ...... 

10*58 

10-31 

Oxygen          

10-55 

10-74 

100-00 

100-00 

which  corresponds  with  the  formula  C20H32O2.  Heated  to  130°  C.  (266°  F.),  it  is 
changed  into  C20H300.  When  the  boiling  alcohol  which  has  been  used  to  extract 
the  gutta  percha  is  allowed  to  cool,  it  deposits  white  rounded  granulations,  consist- 
ing of  a  nucleus  of  fluavile,  covered  with  a  crystalline  incrustation  of  albane,  which 
may  be  separated  from  each  other  by  means  of  cold  alcohol. 

Gutta,  the  principal  element  of  commercial  gutta  percha,  is  solid,  pliant, 
extensible,  but  not  elastic  between  10°  and  30°  C.  (50°  and  86°  F.).  It  softens 
about  45°  C.  (113°  F.),  and  begins  to  assume  a  deep  brown  coloration.  As  the 

1  Obach,  agreeing  with  Oudemans,  found  for  albane  C.  =  78 '96,  H.  =10'58,  0.  =  10'46,  but 
for  fluavile  C.  =80'79,  H.  =11,  O.=8'21,  or  C^H^Oa,  which  neither  agrees  with  Oudemans 
nor  with  Osterle,  who  found  C40H6403  for  albane  and  (C10H16)n  for  fluavile,  thus  reversing 
Oudemans'  results. — TK. 


PHYSICAL    AND    CIIKMICAL    I'ROPKRTIKS 


369 


.    it    l.e, ttfl  in-. iv   \isc.Mis  and  trail-parent.       At  100°  to  110°  C.  ('2  1- 

to -j.'Kr  F.)  it  ,     .in  intoaaofl  p^te,  and  li.|iietiesat  130°  C.  (266°  F.),  and 

thru  commence*  t..  "boU,w  yielding  <>n  distillation  several  hydrocarbides  analogous 

with  tli-iM-  \  ielded  l»y  tin-  «list  illat  ion  «if  rubber.  Tin-  property  of  //>//>  ;/////<*,  of 
becoming  plastic  at  higher  tem|»erat un-s,  shows  that  it  i-  imt  a  Dimple  body,  l.iit  <. 
mixture  (alloy)  of  several  hydrocarbons,  ditl'ering  probably  only  in  their  molecular 
.•Miistitntii.il.  Tli,-  OASe  is  .similar  t«.  that  ••!'  tin-  tininaii '-  -older  in  the  state  in 
which  it  is  iiM-.l  f..r  making  what  i>  technically  call.-.!  ;,  ••  \\ijn-d  joint."  In 
pre-eiicr  •>!'  a--i«ls.  dilute  alcnlnd,  ether,  and  chloroform,  ^utta  IM-IIMM--  like  gutta 
pcrdia.1  (Jiitta,  unless  piv\imis|y  ti'eated  \\itli  alcohol  (Arpe),  is  not  insolnl.le  in 

ether,  lleat-'d  \\  ith  nitric  acid,  it  giveBoff  formic  and  hydrocyanic  a<  ids.  lii-ilm-cd 
to  p(. \\der,  it  rajiiilly  al.sorl.s  oxygen;  gaseous  hydrochloric  acid  transforms  it  into 
a  l»ro\\  nUh  black  BUbetance,  \\hich  contracts  on  its  surface  and  presents  the  appear 
ance  of  a  tn<ed  >ul'>tance.  Its  insta,l)ility  is  very  #ivat,  and  it  is  ditliciilt  to 
I  .reserve  intact  except  in  a  solution  of  common  salt.  Soulxjiran  was  the  first  to 
analyse  gutta,  but  he  did  not  succed  in  completely  separating  the  albane  from  tin- 
tluavile. 

TABLE  CVIIlA. — ELEMENTARY  COMPOSITION  OF  GUTTA  (SOUBIERAN). 


Per  cent. 

o«i.r. 

HvdroLjt'll   ......... 

1  1  •;> 

ii        ......... 

i.-Q 

100-0 

TABLE  CIX. — ELEMENTARY  COMPOSITION  OF  GUTTA  (OUDEMANS) 


-» 

I. 

II. 

III. 

Per  cent. 

Per  cent. 

Per  cent. 

Caihon  ...... 

87-64 

88-10 

88-20 

Hydrogen      ..... 

11-79 

1177 

12-0 

Oxygen           

OT,7 

0-13 

... 

100-00 

100-00 

100-20 

The  composition  of  gutta  would  thus  correspond  with  the  formula  ^'..Jl^  or 
C5H8  (Oudemans).  Uaumliauer  confirmed  Oudemans'  results  as  to  the  eleniei 
composition  of  gutta,  all>ane,  and  tiuavile.  According  to  him.  pure  commercial 
,ufutta  pi'rcha  would  consist  essentially  of  a  hydrocarbide  C.,UH ...„  identical  with  the 
gutta  of  Oudemans  and  with  several  oxidation  products  of  the  same  >ul»tance. 
Batunhauer  exhausted  commercial  gutta  percha,  previously  washe<l  with  water  and 
hydrochloric  acid,  either  l»y  ether,  which  abandons  the  gutta  as  a  white  pulverulent 
substance,  or  by  dissolving  the  substance  in  chloroform,  aud  pouring  the  solution 
into  alcohol,  which  precipitates  the  gutta  in  Hocks,  which  are  purified  by  careful 
washing  \\ith  boiling  absolute  alcohol.  Miller's  formula  for  gutta  would  be  C<>0H30, 
but  the  pure  commercial  gutta  percha  contains  a  hydrocarbide,  C^H.j.,,  mixed  with 
ditt'erent  oxidation  products.  C._.,H .,_,(.)  and  C^H^C^  (Oudemans").  the  relations 
which  may  exi<t  Let  ween  the  latter  products  and  tin"  products  of  the  spontaneous  and 


is  insoluble  in  ether  and  light  petroleum  spirit  at  the  ordinary  temperature, 

Ibane  and  Huuvili-  dissolv  readily  in  tin-so  menstrua.  Ol.arh's  so-called  "chemical 
hardening  process  "  consists  simply  in  extracting  the  resin  from  the  gutta  percha  by  means  of 
light  petroleum  spirit  extraction  plant  on  a  large  scale.- — Ti:. 


370  GUTTA   PERCHA 

ultimate  oxidation  of  gutta l  are  unknown.  On  distillation,  gutta  is  decomposed  in 
the  same  way  as  rubber.  C.  Greville  Williams  has  separated  the  following  hydro- 
carbons :  iosoprene,  caoutchine,  and  heveene,  in  the  following  proportions  :— 

TABLE  CX. — DESTRUCTIVE  DISTILLATION  PRODUCTS  OF  GUTTA  PERCHA 
(GREVILLE  WILLIAMS). 


1 

Per  cent. 

Caoutchine        
1    Isoprene   .......... 

20 
5 

During  distillation  a  volatile  acid  is  given  off,  which  Blossom  regards  as  one  of 
the  lower  members  of  the  series  CnH2nO2.  We  may  thus  regard  pure  caoutchouc 
and  pure  gutta  (the  unoxidised  principle  of  gutta  percha)  as  two  isomeric  com- 
pounds of  the  same  series.  According  to  Blcekrode,  Palaquium  juice  contains  but 
one  and  the  same  principle,  namely,  gutta.  The  different  substances  which  are  found 
therein  arise  exclusively  from  the  deterioration  it  undergoes  during  collection, 
which  explains  the  difference  found  in  the  qualities  of  the  products  now  imported 
which  are  undoubtedly  superior  to  those  imported  a  few  years  ago,  when  the 
process  of  tapping  the  trees  was  unknown,  and  felling  alone  was  in  vogue. 

Physical  and  chemical  properties  of  gutta  percha,  called  yellow  yutta,  of  the  Straits 
Archipelago  (botanical  origin, — Payena  Lerii,  May  any  Sundeti). — Ed.  Heckel  and 
L.  Schlagdenhauffen  made  a  comparative  study  of  the  gutta  perchas  of  the' 
Palaquiums,  and  the  gutta  perchas  produced  by  (1)  the  Payenas,  (2)  the  Mimusops, 
and  (3)  the  Bassias.  Some  extracts  from  their  patient  researches  will  be  useful, 
even  if  their  conclusions  cannot  always  be  accepted,  but  discussion  spreads  light ; 
and  light  on  such  a  subject  as  the  present  one  is  very  necessary. 

(1)  Payena  Lerii. — The  samples  analysed  had  the  form  of  a  hard  yellow 
mass,  easily  scratched  by  the  thumb-nail,  softening  more  than  Mimusops  guttas 
(to  be  referred  to  later  on),  and  adhering  more  strongly  to  the  hand,  which  softened 
them  by  its  warmth.  They  uniformly  assume  the  garb  of  round  balls  of  150  to 
200  grammes  (say  5  to  7  ounces),  somewhat  uneven  and  flattened  in  certain  points, 
which  gives  them  a  striking  resemblance  to  a  freshly  peeled  potato.  By'treating 
the  substance  with  boiling  alcohol,  a  yellow  tacky  liquid  is  obtained,  which,  after 
spontaneous  evaporation,  leaves  small  needle-shaped  crystals.  By  working  on 
5  grammes  only,  1*5  grammes  remained,  consequently  3*5  grammes  were  dissolved 
in  the  alcohol. 

Alcoholic  extract. — Fifty  grammes  of  raw  material  yielded  35  grammes  of 
extract,  which,  taken  up  by  petroleum  ether,  yielded  a  tacky  portion  soluble  in  the 
vehicle,  with  silky,  almost  colourless,  crystals.  The  crystals  so  obtained  are  in- 
soluble in  water,  soluble  in  alcohol,  ether,  chloroform,  benzine,  carbon  disulphide ; 
they  do  not  act  on  litmus,  melt  at  +  65°  C.  (149°  F.),  and  yield,  on  cooling,  a  hard, 
transparent  varnish.  It  resists  fused  potash.  Concentrated  sulphuric  acid  colours 
it  brownish  yellow,  passing  eventually  to  violet.  Nitric  acid  attacks  it  even  in  the 
cold,  and  very  violently  at  the  temperature  of  the  water-bath.  The  reaction 
neither  yields  oxalic  nor  picric  acids.  The  composition  of  the  crystalline  substance, 
according  to  their  analysis,  is  as  follows  : — 

TABLE  CXI. — ULTIMATE  ANALYSIS,  CRYSTALLINE  BODY,  PROM  PAYENA  LERII, 
GUTTA  PERCHA  (HECKEL  AND  SCHLAGDENHAUFFEN). 


Carbonic  acid      .... 
Water         

0-4615  whence  C    67  '930  per  cent. 
0-2175              H    12*083        ,, 

Difference  . 

0    19'987 

100-000 

1  Otto  Osterle  found  a  fourth  substance,  guttane,  in  gutta  percha,  yielding,  after  several 
cipitations  from  its  chloroformic  solution  by  alcohol,  C.  =  86'4,  H.  =12  per  cent — TR. 


PHYSICAL   AND   CHEMICAL   PROPERTIES  371 

hence  the  formula  ('  II  (  '.  Tin-  i.n-k\  matter  mentioned  ;il.o\e  i-  t«.uii<l  in  the 
mother  liquor  nt  1 1  :  ved  an<l  •  :  temperature 

t'riiiii  -V  to  -f  IS  ('.,  it  remain-  JM-I  feet  ly  limpid.  Anal\>i-  >ho\\>  almost  com- 
plete identity  \\itli  tin-  crystalline  product,  e\en  in  ivgard  to  >o|uliility  in  ditleivnt 

menstrua,    \\itli    tin-   exception    of    pet  minim    ether,    which    r pletek    di-sohvs    it, 

whilst   it  BOtTCely  aota    upon    tin-   cr\Mal>:    the    sum-    i«-d   coloration    \\itli    >ulphuric 

arid,  tin-  same  dei position  \\  it  h    nitric   acid,  the  tin-  action  of 

fu-ed   potu-h.      Applied  (iii  chloroformic   solution,  or  di--ol\ed    in  petroleum  H  ! 

on    glass     \\ |,     oi    any    other     hard    body,     it    may     rc|.lace    varnisli.        lint    its 

elementary  composition  is  not  tin-  same.  Tin-  ant  h-.rs  only  found  in  it  I'Milto  of 
carbon  in-t.-ad  of  liT'lM),  and  1  \-:\(^>  of  hydrogen  in  place  of  llMIS.",.  It  therefore 
contains  much  nioiv  o\ygen.  Kroin  its  (.hysical  propcrt  ic-  it  mi^lit  at  tin-  outset 
l»r  taken  fury//////'//'-,  luit  it>  molecular  compovit  i,,n  i.  complrtcly  ilihViviit.  The 
sulistancc  \\hich  I'cmain-  after  tin-  rxti-action  of  the  ra\\  material  by  absolute 
alcohol,  |  .  according  to  the  authors,  all  the  (jualities  of  an  excellent 

caoutchouc.       It    may   In-   drawn  into   thin    threads,  and    s|irin.ur*    oark    <>n    it>elf,   on 

•unt  <>f  its  gnMt  elasticity.  Armnling  to  Heckel  and  Schlagdenhautlen,  tlie 
yellow  irutta  of  tin-  Straits  Archipelago  is  merely  a  mixture  of  30  jier  cent,  of 
gutta  and  of  two  resins,  the  out-  crystallisal»le  and  the  other  tacky. 

<  •_!  i  /'// //>•/'•'// '///</  flu  iii!i-<il  IH-I>IH  i-ti,  x  nt'  Abyuinfan  gutta  extracted  tKnn  f/it 
Mimiit'iji*  Si-hint/*  /•/  /•/  Kiuiiiiiil  (of  Hochst). — The  samj»les  analysed  ueiv  recei\cd 
from  a  M.  .lainln-rt,  of  French  origin,  who  had  become  Menetik'a  Minister  at  S 
The  sul.stance  was  a  hard  brown  mass,  of  not  so  dark  a  colour  as  the  /'//A/.////*//// 
gutta  of  commerce.  Easily  scratched  with  thumb-nail,  it  softened  >lightly  in 
the  hand,  and  became  tacky,  although  heat  did  not  make  it  tackier.  The  authors 
first  treated  the  substance  with  tepid  ^ater,  then  with  boiling  water,  t<>  separate  as 
far  as  possible  the  vegetable  debris  and  other  impurities  which  it  contaiued.  By 
cooling  the  liquid  afterwards,  and  stirring  it  vigorously,  they  fixed  on  the  stirrer  a 
more  or  less  elastic  substance  of  the  same  colour,  entirely  different  from  the  non- 
adherent  granular  deposit  at  the  bottom  of  the  dish.  In  spite  of  repeated  treatment 
with  hot  water,  they  were  not  able  to  agglutinate  this  latter  portion.  The  cause  of 
its  resistance  to  plasticity  is  due  to  the  considerable  quantity  of  fixed  salts  con- 
tained in  the  deposit,  since  an  analysis  of  0'627  of  substance  gave  0'127  of  ash. 
The  deposit  which  falls  to  the  bottom  of  the  water  contains  therefore — 

TABLE  CXII. — ANALYSIS  OF  ABYSSINIAN  GUTTA. 


,     Percent.1 

Organic  matter          
Ash  

72'54 

•J7-11 

The  adherent  elastic  matter  of  an  earthy  brown  colour  was  kneaded  between 
the  lingers  until  a  homogeneous  mass  was  obtained.  In  appearamv  this  mass 
i-  rather  analogous  with  ordinary  gutta  i>ercha.  It  softens  in  water,  but  al\\ 
preserve-  consideraMe  elasticity.  Owing  to  these  defects,  in  can  never  be  sub- 
stituted for  good  commercial  gutta  prn-lia  without  piwiou-  modification  and 
transformation.  Numerous  attempts  to  eliminate  or  minimise  these  drawbacks 
were  unsuccessful.  Sudden  variation  of  temperature  and  pressure  gave  negative 
results.  As  a  last  resource,  attempts  were  made  to  mix  the  gum  with  ordinary  gutta 
peivha,  with  the  ho]^  that  the  exce-s  ,,f  i-lasticity  and  adhesi\eness  might  be  masked 
1>\  the  plasticity  of  the  better  quality  gutta  percha  Two  mixtures  containing 
Abyssinian  gutta  were  made  and  sent  to  the  printing-works  of  I'erger.  Kvrault,  to 
ascertain  if  the  new  product  might  find  an  industrial  use,  and  be  capable  of  being 

1  The   figures   given   by  the  authors  calculated    to   per  cent,    give  7974  and  20'26   re- 
spectively.— TR. 


372 


GUTTA   PERCHA 


used  for  taking  impressions  of  the  moulds  of  blocks  for  steel  engravings  used  in 
making  galvanos.  The  answer  was  prompt :  the  experiment  gave  excellent  results. 
To  ascertain  the  cause  of  so  marked  a  difference  between  these  two  varieties  of  gutta 
percha,  the  authors  (H.  and  S.)  tried  to  find  out  how  they  behaved  in  presence  of  differ- 
ent chemical  reagents.  The  first  experiments  were  naturally  with  such  solvents  as 
alcohol,  ether,  carbon  disulphide.  Now,  whilst  alcohol  does  not  dissolve  ordinary 
gutta  percha,  the  Abyssinian  substance  dissolved  therein  to  the  extent  of  42  per  cent. 
The  boiling  solution  is  colourless.  On  cooling,  a  white  mamillated,  but  non- 
crystalline,  product  is  deposited.  The  microscope  shows  some  rare  needles,  which 
cannot  be  eliminated  by  any  of  the  vehicles  successively  employed  for  this  purpose. 
The  authors  conclude  that  the  substance  is  amorphous,  with  a  tendency  to 
crystallisation.  By  repeated  solution  in  boiling  alcohol,  it  was  at  last  obtained  of 
a  snow-white  colour.  The  compound,  of  a  fusible  nature,  melts  at  107°  C. 
(224-6°  F.).  Heated  to  230°  C.  (446°  F.),  it  remains  liquid  without  the  least 
alteration,  but  at  a  higher  temperature  it  turns  brown  and  decomposes.  It  dis- 
solves in  ordinary  alcohol,  wood  spirit,  acetone,  benzene,  chloroform  ether,  spirits 
of  turpentine,  petroleum  ether,  and  carbon  disulphide.  It  does  not  dissolve  in 
boiling  potash,  and  does  not  yield  double  decomposition  products  by  the  action  of 
fused  potash.  Nitric  acid  attacks  it  very  energetically  —  a  crystalline  body, 
oxalic  and  picric  acids,  and  other  substances,  being  produced.  Its  formula  is 
C5HSO  or  C20H32O4.  It  may  therefore  be  considered  as  an  oxidation  product  of 
albane,  C20H32O2,  contained  in  ordinary  gutta  percha,  but  it  differs  from  it  in  its 
chemical  properties.  Moreover,  it  does  not  possess  any  of  the  characteristics  of 
fluavile,  C20H32O,  which  accompanies  the  albane  of  ordinary  gutta  percha.  These 
two  resins,  the  former  of  which  is  white  and  crystallisable,  the  other  amorphous 
and  translucid,  are  associated  with  the  gutta — 

TABLE  CXIII. — PROXIMATE  ANALYSIS  OF  ORGANIC  PORTION  OF 
ABYSSINIAN  GUTTA. 


Per  cent. 

Gutta         
Albane       ..;....... 
Fluavile     

75-82 
19-14 
6-14 

101-10 

whilst  the  mimusops  gutta  percha  only  contains  the  white  non-crystalline  resin  of 
which  we  have  given  the  analysis,  and  which  amounts  to  42  per  cent,  of  the  raw  pro- 
duct. The  remainder,  i.e.  58  per  cent,  of  matter  insoluble  in  alcohol,  forms  a  dark- 
coloured  substance,  the  appearance  of  which  recalls  that  of  ordinary  gutta,  and,  like 
it,  it  is  soluble  in  ether,  and  completely  insoluble  in  ordinary  alcohol,  wood  spirit, 
and  acetone.  The  product  contains  9 '8  per  cent,  of  fixed  residue,  consisting. almost 
solely  of  sulphate  of  lime.  The  composition  of  the  mimusops  gutta  percha  may 
therefore  be  put  down  as — 

TABLE  CXIV. — COMPOSITION  OF  MIMUSOPS  GUTTA  PERCHA. 


Per  cent. 

Gutta         
Fixed  salts         ......... 

48-20 
9-80 
.  42  -00 

100-00 

PHYSICAL  AND   CHEMICAL   PROPERTIES 


373 


The  raw  product,  as  well   ;t-  tin-  «rntta   purified  by  tho  |.iwi«.u^  elimination  of 

tin-    \\hole   M|    id,-    i.  -in,   i,r,    1,1-tti-r   -till,    by    niils   a    pm-tinn    «\    that    roin,  may  l.e 

utili  'I.     To  obtain  '//>   ///"»•'  *ntt<i/,i,  compound  for  tfa  //*•//•/// 

,/,1/r,  ///,,.»•.    thr\     I...JI    tin-    -iiltM.iiMv    \\illi   its  OWIl    U'-i-ht    "|    '.)n    percent    .ilc«.|i«il, 
filter  ami  inct.rpor.ite   tin-  rake,  \\hidi    remain-   in    e.|iial    propm  i  i<.n>    u  it  li  ..nlinai  \ 


/'/f//.s/m/  <i/i</  <•!«  //<«;,/  prop*  /  '"  I  '/  '/"  </""'"  /-  /•••//•/  •  /  '  fitted  from  ttte  Bassia 

I'.irkii  ,n-  i/uiii  •>/  tli>    K-irtt,'  t,-"        /J.um'tt/.-    -Tin-  <  IriiMtV  «  .1'    thi>    j.ioduct  W  0'976, 

whilst  1'ayt'ii  assigns  to  the  mule  ^utta  jiercha  of  the  /'<//<"/>///////x  that  of  0'(.»7"'. 
ln.<iil<ttiii<i  i>ropertie8.  —  It  IK.M-«UIICS  electrical  l>y  rul^bing  as  easily  as  the  latter,  and 
may  t  lu-ivl'i.iv  l»r  likewise  used  as  an  insulator.  It  softens  in  hot  water  in  thu  saim- 
\\ay  as  coininrrcial  gntta,  and  heroines  ailln-sivc  like  it  at  a  temiHjratuiv  hordcrinu 
on  fltiillition.  From  a  dicniical  point  of  view,  however,  some  ditl'rivin-rs  c\i-t. 
.{••film  <>/  an/  vents.  —  For  tin-  t\\<»  products  do  not  behave  in  an  identical  manner 
with  suhrnts.  llassia  ^utta  ti'catrd  \\ith  prtrolrmn  ether,  ordinary  ether,  spirits  of 
tiirpentiiK',  and  boiling  acetic  acid,  ccdrs  to  these  solvents  a  less  amount  of  soluble 
principles  than  ordinary  gutta.  Moreover,  tin-  evaporated  solutions  do  not  leave 
identical  products.  The  residues  of  the  Bassia  gutta  are  tacky,  whilst  those  of  com- 
mercial gutta  consists,  so  to  speak,  of  a  dry,  non-adhesive  varnish.  Identity  i> 
alnmst  complete,  from  the  point  of  view  of  solubility,  in  carbon  disulphide,  chloro- 
form, l>enzene,  and  cold  and  boiling  alcohol.  With  the  two  first  solvents,  only  an 
insignificant  insoluble  residue  remains  of  quite  a  black  colour,  provided  always 
that  a  sufficient  quantity  be  taken.  As  to  the  solvent  power  of  ben/ene,  it  is 
likewise  similar.  The  insoluble  residue  is  identical  in  the  two  products,  but  a  little 
more  pronounced  than  in  the  former  instance.  As  to  the  solubility  in  95  per  cent. 
alcohol,  it  is  equal  in  both  instances,  but  this  latter  solvent  only  dissolves  7  per 
cent,  of  the  substances  treated.  Summing  up  the  solvent  powers  of  the  different 
vehicles,  and  bringing  the  results  to  per  cent.,  we  get  the  following  Table  :  — 

TABLE  CXV.  —  SHOWING  THE  SOLUBILITY  OF  ORDINARY  GUTTA  PERCHA 
AND  BASSIA  GUTTA  PERCHA  IN  DIFFERENT  SOLVENTS. 


Carbon 
Disul- 
phide. 

Chloro- 
form. 

Ben- 

7.111*. 

Ordin- 
ary 
Ether. 

Petro- 
leum 
Ether. 

Spirits 
of  Tur- 
pentine. 

Acetic 
Acid. 

Alcohol 
96  per 
cent. 

Commercial    gutta 

IM  Trim  .             .             .          9972 

98-68 

93-20 

40-8 

34-0 

20 

19-2 

7 

Bassia  gotta  peroha  <       97  '92 

92-28 

92-80 

20-1 

18-1 

8   , 

12-8 

7 

TABU  CXVI. — SHOWING,  BY  PAYENS  PROCESS,  THE  COMPARATIVE  PROXIMATE 
COMPOSITION  OF  CRUDE  AND  PURIFIED  COMMERCIAL  GUTTA  PERCHA  AND 
BASSIA  GUTTA  PERCHA. 


Crude 
Commercial 
Gutta  Percha. 

Crude 
Bassia  Gutta 
Percha. 

Commercial  Gutta 
Percha  No.  1  Puri- 
fied by  Carbon 
Disulphide. 

Bassia  Gutta 
Percha  Purified 
by  Carbon 
Disulphide. 

Gutta      . 

AH>;iiic'    . 
Kluavile  . 

I.             II. 

92           91-5 
6             6-5 
2             2 

91 
5-5 
3 

92 
5-8 

•2-2 

91-5 
6-0 

2-3 

f 

100-0    100-0 

99-5 

100-0 

99-8 

374 


GUTTA    PERCHA 


By  heating  these  two    gutta   perchas  until  carbonised,  and    incinerating    tin- 
product,  ashes  of  similar  appearance  were  obtained — 

TABLE  CXVII. — SHOWING  THE  COMPARATIVE  AMOUNT  OF  ASH  IN  BASSIA 
GUTTA  PERCHA  AND  COMMERCIAL  GUTTA  PKurn.\. 


10  grammes  of  Bassia  gutta  left  . 

10        ,,        of  commercial  gutta  percha 


Residue  in 
Grammes. 


Per 

cent. 


0-120    = 
0-126    = 


1-20 
1-26 


Spectrum  analysis  gave  sodium,  potassium,  and  lithium.  There  is  almost 
complete  identity.  Summing  up : — The  products  of  the  Mimusops  approach  in 
composition  and  properties  true  Palaquium  gutta  percha,  whilst  the  Payena  seem 
more  allied  by  their  composition  and  chemical  properties  with  caoutchouc.  Both 
products  are  much  further  away  in  their  nature  from  real  gutta  percha  than  the 
Bassia  Parkii  product,  whose  identity  with  Palaquium  is  nearly  complete. 
Although  the  conclusions  of  scientific  chemists  and  professors  cannot  always  be 
accepted,  and,  until  a  new  order  of  things  and  proof  to  the  contrary  is  forthcoming, 
it  may  be  safely  asserted  that  the  gutta  perchas  of  the  Payena  Lerii  are  powerful 
and  almost  indispensable  adjuncts  in  the  making  of  mixtures  of  industrial  gutta 
perchas,  we  have  nevertheless  not  hesitated  to  reproduce  this  research  almost  in  its 
integrity.  Comparative  researches  of  this  nature  alone  enable  the  truth  to  come 
soon  to  light,  to  the  great  profit  of  commerce  and  industry.  The  opinions  on  the 
products  of  Bassia  Parkii  require  more  ample  information.  If  their  scientific 
data  should  have  to  be  recognised  as  exact,  and  the  Ghee  tree  should  really  have 
to  be  regarded  as  capable  of  yielding  a  utilisable  gutta  percha,  it  would  be  an 
urgent  matter  to  undertake  its  rational  culture  as  promptly  as  possible.  It  would 
then,  without  doubt,  be  one  of  the  most  useful  trees  of  tropical  Africa,  the  more  so 
as  this  plant  loves  dry  gravelly  soils,  and,  moreover,  it  is  extremely  hardy.  We 
could  then  apply  to  it  the  term  applied  to  the  Manihot  Glazoivii  with  respect  to 
caoutchouc  :  the  Bassia  Parkii  would  be  the  gutta  percha  tree  of  the  future.1 

Obach  is  not  so  enthusiastic  as  HeckeL  From  the  samples  at  his  disposal  he 
formed  an  unfavourable  opinion  of  Bassia  gutta.  He  says : — The  solid  oil  or  fat 
of  the  shea  butter-tree,  which  is  largely  used  for  soap-making,  contains  from 
0'5  to  0'7  per  cent,  of  a  hydrocarbon  said  to  be  similar  to  gutta,  and  which  has 
been  termed  "  gutta  shea."  I  have  examined  a  specimen  of  the  concrete  milk 
from  the  trunk  of  the  tree ;  also  some  of  the  gutta  from  shea  butter,  and  some 
slightly  fermented  gutta  from  the  trunk,  which  I  received  in  1891.  They  were 
taken  from  samples  sent  to  the  Kew  Museum  from  Western  Africa  some  years  ago 
by  Sir  George  Goldie,  of  the  Royal  Niger  Company.  Two  of  the  samples  con- 

TABLE  CXVIIL — ELEMENTARY  ANALYSIS  OF  BASSIA  GUTTA  PERCHA 

BY  FENDLER. 


I. 

II. 

III. 

Carbon 
Hydrogen     . 

86-93 
10-93 

87-07 
10-98 

87-29 
11-21 

Calculated 
for 


88-14 
11-86 


J  Serrulaz  and  Houraut  (British  Patent,  654  ;  1896)  claim  the  extraction  of  gutta 
the  raw  material  of  Bassia  Parkii  by  toluene  and  subsequent  precipitation  by  acetone  i 


by 
they  extract  ordinary  gutta  from  the  leaves. — Tn. 


from 
subsequent  precipitation  by  acetone  just  as 


PHYSICAL   AND   CHEMICAL    I'ROPERTIKS 


tained  about   II  per  cent,  oi  --mi -\\hat  n-~.  ml-li:  but  j«»^- 

MM  -treimth  «»r  t;-nacit\,  .iii.l  partaking  mop-  oi  tin-  nature  of  a  wax.     The  material 
could,   then-tore,   har«ll\    M-place   -uti.i  peiciM  f«ir   Home  special 

application.       H«. \\e\er,    I     -hoiild    not    like    t.,    expreM    a    definite   opinion    on 
substance  until   I   ha\r  examined  it   in  a  perfectly  fn^li  ami  in: 

P.a>sia  gutta  yields  potassium  riimam  u  \\itli  alcoholic  j. 

(  >\\  -ell   containing   b'idie  .    pre.-ellt. 

TAIM.I.   (  '\  I  V       ANALYSIS    Of    Six    S  \\iri  i  -    o|     I1,  \-  -i  \    (  ii   n  \    IO|.I.K»  TKl»    HY 

Ku:>i  us-,    is    LAMA. 


1. 

8. 

i. 

fit, 

Percent. 

1'rl-  .  -i  lit 

I'd    ci'llt. 

I'.T  rrht. 

r.  i  •-.•MI. 

Per  it-iit. 

Cutta      . 

•J:V,il 

19-8 

1D-0               'Jl-J 

l.VO 

i:-; 

u       ... 

50-5 

G5-0 

:i  •:, 

A>li 

7""1 

0-80 

5-2 

0(5 

7'8 

1,  Old  l;it.  \  :  2  and  3,  fresh  latex  preserved  by  ammonia  ;  4,  fresh  latex,  water  added,  and 
preserved  1'V  .mmionia  :  r»,  lit>h  lat«  \  jtn-st-rved  by  ammonia.     Fresh  latex  air  dried. 


and 


properties.     In  tin-  preceding  research,  Heckel 

,  lia\c  rrfrrrnl  t<»  Al'\»inia  L,rntta,  a  pnxlurt  «»f  .!/ 
-I  >  f  l\  a  in  in'  I.  l)iit  not  to  the  product  of  tlui  .!///////>"/'.<  Ilnlnt'i  ,t  /;/,, 
put  on  tli«-  market  under  the  name  <>f  1-alata.  Thr  hitter  sul»>taii«f,  l.oides  its 
great  strength,  possesses  the  property  of  ln-in^  slightly  elastic  \\lien  it  is  pulled,  a 
property  of  irivat  inipoilanee  in  the  manufacture  of  t  ran  -mission  belts:  and  it  was 
this  property  whieh  made  Stagneri,  an  American  manufacturer  of  rubber  goods, 
declare  that  balata  was  the  best  rubber  in  the  world.  This  >uUtam  v  \\.uihl  tind  a 
lie  in-  and  more  extended  consumption  if  a  sufficient  supply  \\ere  put  on  the 
market  ;  but  as  matters  stand  its  production  is  very  limited.  Its  price  is  e.jual  to 
if  not  higher  than  that  of  gutta  percha,  and  that  is  the  best  proof  that  indi. 
knows  ho\\  to  use  it.  In  the  generality  of  cases  where  gutta  (terclia  is  utili.-ed. 
balata  is  capable  of  usefully  replacing  it,  and  it  is  only  its  relatively  high  pri<  ••• 
which  routines  it  to  certain  special  uses.  The  manufacturing  trade  regards  balata 
as  a  gutU  i>ercha,  and  one  of  the  best;  once  wrought  up,  its  generic  name  \\ould 
disappear,  to  be  confused  with  the  other  sorts  of  industrial  gutta  pen-ha-.  V  \.  T 
theless.  the  product  is  far  from  being  the  same  from  a  physical  and  chemical  jntint 
of  view.  It  is  softer  at  the  ordinary  temperature,  and  remains  pliant  at  low 
temperatures.  The  gutta  contained  in  balata  is  very  strong  and  tough,  l«-ing 
altogether  of  excellent  quality  ;  but  the  percentage  of  resin  is  a  large  one,  and  the 
material  can  consequently  only  l»e  regarded  as  a  substitute  for  second,  or  ]*'r! 
even  third-class  gutta  {>ercha.  Balata  is  somewhat  more  flexible  than  gutta  percha. 
containing  an  equal  amount  of  resin,  which  api>ears  to  be  due  to  the  softness  of 
the  resinous  constituents.  (Obach  had  several  times  ol.M-ned  an  oily  substance 
exuding  from  balata  on  stretching,  which,  after  drying  up,  left  a  whitish  powder 
behind,  resembling  mildew).  A  loss  in  weight,  usually  observed  during  analysis, 
indicates  the  presence  of  volatile  constituents.  To  determine  the  composition  of 
the  resin  contained  in  balata,  a  specimen  extracted  with  ether  \\as  carefully  heated 
by  Obach  until  the  weight  remained  constant,  whereby  it  lot  IM;  :  it 

was  then  repeatedly  treated  with  l>oiling  alcohol,  from  which   the  albanr  was   pn 
cipitated  on  cooling  as  a  white  crystalline  powder,  leaving  the  fluavile  in  solution. 
It  was  then  found  that  the  resin  consisted  of  about  two  parts  of  <ili><m>  and  three 
parts  Qifluamlc. 

Some  of  the  specimens  of  balata  sent  to  this  country  perished  quickly  when 
exposed  to  air  and  light,  and  this  rather  prejudiced  the  manufacturers  against  the 
material;  but  others  retained  their  good  qualities  a  long  time,  and  a  sheet  of 


376 


GUTTA   PERCHA 


balata,  which  was  manufactured  in  January  1881,  nearly  seventeen  years  after- 
wards, was  still  as  sound  as  one  could  wish  it.  The  sheet  had  been  kcj.t  in  a 
comparatively  cool  cellar,  but  without  any  special  precautions.  Obach  was  in- 
clined to  think  that  the  materials  which  decayed  so  prematurely  had  either  been 
carelessly  prepared  from  the  latex,  or  else  were  obtained  by  some  special  method 
of  coagulation.  The  behaviour  of  balata  towards  atmospheric  oxygen  is  referred 
to  in  the  sequel. 

If  the  commercial  substance  be  purified  by  washing  with  boiling  acidulated 
water,  then  by  boiling  alcohol,  a  residue  remains,  which,  dissolved  in  carbon 
disulphide,  filtered  and  evaporated,  gives  a  similar  composition  to  gutta,  i.e.— 

Carbon  .  .  .  .  .  .  .88-5  per  cent. 

Hydrogen        ...  .  •     H'5        ,, 

100-0 

The  colour  of  balata  is  reddish  white,  with  dark  spots  and  veins.  It  has  no 
taste,  and,  when  heated,  emits  the  same  agreeable  odour  as  pure  gutta,  when  slowly 
heated,  under  a  layer  of  water  and  gradually  brought  to  the  boiling-point.  Its 
specific  gravity  is  1'05.  It  may  be  cut  like  gutta  percha,  but  it  has  much 
greater  tenacity. 

TABLE  CXX. — ANALYSIS  OF  VARIOUS  HISTORICAL  SAMPLES  OF  BALATA  (OBAcn).1 


Percentage  Composition. 

Totals. 

Ratios. 

Percentage 
Composition. 

No. 

Gutta. 

Resin. 

Dirt. 

Water. 

Balata. 
G.+R. 

Waste. 
D.  +W. 

Balata. 

Gutta. 

Gutta. 

Resin. 

Waste. 

Resin. 

(1) 

43-2 

40-3 

14-5 

2-0 

83-5 

16-5 

5-1 

1-1 

517 

48-3 

(2) 

47-4 

43-6 

8'3 

0-7 

91-0 

9-0 

10-1 

1-1 

52-1 

47-9 

(3) 

43-3 

41-6 

13-0 

2'1 

84-9 

15-1 

5'6 

1-0 

51  0 

49-0 

(4) 

44-5 

41-6 

12-2 

1*7 

86-1 

13-9 

6'2 

1-1 

517 

48-3 

(5) 

41-1 

42-6 

14-1 

2-2 

83-7 

16-3 

5-1 

0-97 

49-1 

50-9 

(6) 

42-6 

48-0 

3-7 

5-7 

90-6 

9-4 

9-6 

0-89 

47-0 

53-0 

(7) 

31-1 

27-0 

4-3 

37'6 

58-1 

41-9 

1-4 

1-2 

53-5 

46-5 

(8) 

52-4 

39-8 

5-3 

2-5 

92-2 

7-8 

11-8 

1-3 

56-8 

43-2 

(9) 

43-5 

36-9 

14-3 

5-3 

80-4 

19-6 

4-1 

1-2 

54-1 

45-9 

(10) 

41-5 

34-8 

9'9 

13-8 

76-3 

23-7 

3-2 

1-2 

54-4 

45'6 

Analysed. 

(1)  Berbice  (Dr.  Van  Hoist),  1860         .  1886 

(2)  British  Guiana  (Intern.  Exli.),  1862 

(3)  „  (James  Collins),  1868 

(4)  Trinidad  (J.  R.  Longden),  1874 

(5)  Demerara  (E.  F.  M.  Thurm),  1882  . 

(6)  ,,         (J.  S.  Jenman),  1884 


Analysed. 

(7)  Demerara  (J.  S.  Jenman),  1886      .   1897 

(8)  British  Guiana  (Col.  &  Ind.  Exh.), 

1886   .         .         .         .     •    .         .      „ 

(9)  Surinam  (Tubergen  &  Daarn),  1896      ,, 
(10)  Mostly    British    Guiana    (various) 

Importers,  1889-94*.         .      1889-94 


*  Average  of  ten  commercial  lots  representing  50  tons. 

Action  of  solvents  and  reagents. — Spirits  of  turpentine,  and  more  especially 
benzine  and  carbon  disulphide,  dissolve  it  completely  in  the  cold  state.  It  with- 
stands caustic  alkalies  like  gutta  percha  and  rubber,  likewise  hydrochloric  acid. 
But  sulphuric  acid  attacks  it,  carbonising  it.  Nitric  acid  transforms  it  into  hydro- 
cyanic and  formic  acids.  If  Balata  resists  acids  less  energetically,  Rousseau  rightly 
attributes  this  fault  to  the  balata  being  always  impure  and  charged  with  putres- 
cible  milky  juices.  Examined  by  the  polariscope,  balata,  like  gutta  percha,  ex- 
hibits in  a  very  high  degree  the  beautiful  phenomenon  of  prismatic  decomposition 
of  colours,  especially  after  having  been  strongly  pressed.  But  what  essentially 
differentiates  balata  from  gutta  percha  is  the  way  it  behaves  under  the  action  of 

1  A  sample  with  |  =  1'16  had  a  density  of  0 '97 15  (Obach). 


PHYSICAL  AND   CHEMICAL   PROPERTIES 


377 


atmospheric  agents.  \Ve  know  tin-  transformat ions  \\hich  i^iitta  undergoes  in  con- 
tart  with  li^ht  and  t  lir  ,,\  \ -,-n  ••(  the  air:  iN  surface  re-initie-,  rapidly,  and  it  i- 
tran-loinied  into  a  dry.  I. little  siil.  This  t  ran.-t'-.riiiat  imi  jM-in-t  rates  h"!n 

tin-    surfiii-'-    into    the    interior   of    tin-    Muck-,    and    tin-    uhole    \. 
It    is    not    so    \\itli    l-alata,   \\liirli.  iindi-r  -iniilar   intlm-n-  their   di--t  i  m-i  i\f 

action  admiral. l\,  and  for  a   lon^  time. 

limtiiiitiiiij  /'/«/"/•/,<  x. — As  to  the  insulating  resistance  of  l.alata,  the  authors 

assign  to  it  an'avera^e  specific  resistance,  and  allow  it  to  take  a  high  plaee  in  the 
>erie>  of  niiimieivial  uruH;i  I'erdia-.  At  the  onlinary  temperature  it  r.ither 
re-end. les  a  horny  substance ;  it  softeio  e\en  at  T.t  ( '.  (I  •_'<)••_'  I-'.),  and  can  then  l.e 
made  to  assume  any  -liape.  m-  i'ecei\e  any  imprint. 

If  in  Talilr  ('\.\.  t\\«t  speeimens  are  disregarded,  -ays  (  )l»aeh  in  valuing  the 
l-alata  from  his  aiial\>is.  there  is  not  very  inneh  ditl'erenee  Letwi^en  the  other 
ones  as  far  as  the  ratio  l.et\\een  pure  guttii  and  resin  is  oimvriH-d,  the  <|iialit\ 

7    varyin-r   only  Between   4a  and  5,  V=i/)-      Tin-  larger  amount  of   \\at<-r  \\lii.1i  the 

commercial  materials  enclosed  in  comparison  \\ith  the  other  s|ieeimen-,  is  partly 
to  he  explained  l.y  the  circumstance  that  the  former  \\ere  mostly  analysed  sliortly 
after  they  arrived  in  London,  whereas  the  other  s|  eeimens  had  l>een  in  mu-eiim- 
foi  many  years  l>efore  the  anal\>i<  \\a-  made.  The  quality  of  the  commercial 
kilata  as  represented  l>y  Nos.  S,  i»,  and  1<>,  is  superior  to  that  of  any  of  the  >|K-cial 
samples  I  to  5.  (The  Duality  i>  expressed  l.y  dividing  the  percentage  ,,f  r«->in  l>y 
In.  fractions  of  a  per  cent.,  j,  £,  -J-  being  rep  resented  l.y  <i,  />,  c,  see  Table  X<  \ 

T.\l:i  K    CXXI. — BALATA   COLLECTED    IN    AND    EXPORTED    FROM    BRITISH    GuiAN\. 

1885-96. 


1885. 

1886. 

1887. 

1888! 

1889. 

1VMI    III. 

iv  u  :••_'. 

1892-93. 

1893-94. 

IIN4L 

iv..-,  •••;. 

ToUl. 

Cwts.  496 

606 

783 

2219 

tttf 

2025 

1039 

2120 

1832 

1867 

1424 

17,596 

esiis 

2979 

MM 

14,000 

15,652 

10,078 

6807 

11,296 

8283 

11,484 

8923 

,  (>,.,.  II,   I 

,,,'m-e  J9'1 

10-54 

10-37 

14-17 

10-84 

10-66 

14-05 

11-42 

9-69 

13-18 

1  ::-|  :  -| 

Av.  val.  i»  r 
11..  11-59 

CHAPTER  VI 
MECHANICAL  TREATMENT  OF  GUTTA  PERCHA 

LIKE  rubber,  but  more  so,  commercial  gutta  percha  which  comes  to  market  contains, 
in  greater  or  less  quantities,  a  certain  number  of  impurities,  such  as  sand,  soil, 
wood,  bark  of  trees,  either  fraudulently  added  by  the  collector  with  a  view  to  fraud, 
or  because  the  imperfection  of  the  available  collecting  processes  did  not  allow  him 
to  do  better.  Before  employing  it  for  any  purpose,  gutta  percha  must  be  purified 
and  freed  from  all  sorts  of  inert  matter,  which  might  give  rise  to  serious  inconveni- 
ence during  the  ulterior  transformations  which  the  substance  has  to  undergo. 
These  purification  processes  are  very  simple,  but  rather  numerous  :  manufacturers 
do  not  use  them  all,  and,  according  to  the  nature  of  the  raw  material  and  special 
exigencies,  one  or  more  operations  may  be  eliminated.  Thus,  in  the  making  of 
different  laboratory  apparatus,  it  is  possible  to  dispense  with  almost  all  the  pro- 
cesses of  purification,  whilst  in  the  making  of  submarine  cable  dielectrics  we  cannot 
multiply  too  many  times  the  method  of  purification.  Inspired  by  the  researches  of 
Heinzerling,  Siemens,  Wunschendorff,  Obach,  and  Bobet,  we  shall  follow  step  by 
step  all  the  purification  processes. 

Prelimiiiary  work. — Operations  are  commenced  by  dividing  the  crude  gutta 
percha  into  rather  small  fragments  by  a  play  of  knives,  or  by  a  circular  saw,  but 
not  without  having  previously  softened  the  gum  in  a  little  hot  water  :  for  this 
purpose  many  factories  still  use  at  the  present  day  the  cutting  machine  patented 
by  Hancock  in  1847,  No.  11,575.  Fig.  127  shows  a  front  view  (I.),  a  side  eleva- 
tion (II.),  and  a  section  along  a  line  a  b  (III.).  This  machine  is  nothing  other 
than  a  kind  of  turnip  slicer,  the  principal  organ  of  which  consists  of  a  circular 
cast-iron  or  hard  wooden  plate  or.  disc  B  £,  mounted  on  the  frame  A  A.  The 
plate  is  pierced  by  three  slots,  in  one  part  of  which  are  inserted,  like  the  cutting- 
iron  of  a  plane  or  spokeshave,  three  radial  knives,  slightly  inclined  and  projected 
slightly  on  the  plane  of  the  plate.  The  latter  turns  on  the  end  of  a  shaft  B, 
driven  by  a  belt  from  a  steam-engine  or-  by  any  other  gearing.  The  speed  is 
regulated  as  required,  and  generally  the  plate  makes  200  revolutions  a  minute 
against  the  sides  of  a  cast-iron  inclined  table  ./),  which  serves  as  a  hopper.  When 
the  machine  is  in  motion,  the  lumps  of  crude  gutta  percha  fall  down  an  inclined 
shoot  against  the  knives,  by  which  they  are  cut  into  slices,  corresponding  to  the 
degree  of  projection  given  to  the  knives,  and  fall  into  a  receiver  beneath.  If  the 
gutta  percha  to  be  shredded  is  harder  than  usual,  the  flat  knives  are  replaced  by 
more  curvilinear  blades,  which  cut  it  up  better.  Then  commences  the  series  of 
successive  operations  which  are  to  transform  the  raw  gutta  percha  into  normal 
gutta  percka,. 

The  fragments  in  the  receiver  are  freed  by  hand  (hand-picked)  from  the 
coarser  substances  present.  They  are  then  collected,  placed  in  an  iron  tank  filled 
with  hot  water,  which  a  steam  coil  maintains  at  the  right  temperature,  and  in 
which  a  mechanical  agitator  is  constantly  kept  revolving.  A  part  of  the  impurities 
falls  to  the  bottom  of  the  tank,  the  pieces  of  softened  gutta  percha  float  to  the 
top,  agglomerate  into  a  compact  mass,  which  is  fished  out  by  a  perforated  metallic 
shovel,  and  carried  to  the  mincing  machines  and  washers.  Hancock  was  the  first 
to  invent  a  well-conceived  arrangement  for  conducting  these  operations  system- 

378 


MECHANICAL  TREATMENT   OF   GUTTA   PERCHA        :!7'» 

atirally.  I'.ritish  I'atent,  11, :>:><>,  K»th  l-'ebrua.-y  l>'17.  T  ( V ig.  I'.'S)  is  a  Urge 
:-voir  divided  intii  three  compart  im-nts  /'  /••'  / ;.  'I'll.-  \\ater  l«-\el  in  tin-  emu 
partmniN  /'  f'  \-  higher  than  in  tin-  compart  nn-nt  /  '.  Thn-e  i..||-.  /•"  /  /'.  turn 
tian^d.  rl\  t-i  tin-  reservoir  ami  abo\e  tin-  le\el  of  tin-  \\at.-r.  TIn-M-  mils  are 
titled  with  a  great  number  ••!'  blade>  ami  circular  -aw-  u  it  h  altrm.it.-  teeth.  In 
front  of  tin-si-  crushing  mils  air  a  pair  "f  tinted  feed  mils.  Thr  softened  gutta 
percha  fmm  thr  table  //'  is  fed  into  the  pair  of  tlutnl  feed  mll>  /•''.  //  i-  an 
i-inllr>s  url.  rolling  Knind  two  cylindere ;  the  lower  j»art  dip-  into  the  eoinpartinent 
fl,  whilst  the  up|M-r  part  eoiinnnnicates  with  the  crushing  roll  71'2.  A  fMM'ond 
endless  weh  //:;  i-  arranged  similarly,  to  l»rin^  the  material  to  the  crushing  r«»ll 
The  mincing  cylinder  A"  is  similar  to  the  machine  \\Iiidi  in  \>&\Kr  mills  is 
used  to  shred  rags.  It  is  fitted  with  blades  all  over  its  circumference,  and  turns 
around  an  arrangement  of  edge  plates  fitted  \\ith  similar  blades.  These  are  SO 
fixed  that  the  blades  of  the  cylinder  shall  in  resolving  come  into  HUch  close 


Fie.  125.— Machine  for  cutting  up  raw  gutta  percha  (slicing  machine)  (Hancock's  system). 

parallelism  \\ith  them  as  to  produce,  by  their  approximate  conjunction,  a  scissors- 
like  bolt  of  action.  'Phis  mincing  roll  is  ao  fixed  as  to  be  opposite  the  bottom  of  the 
rolls  r[  I-"1  I™,  and  is  always  half  immersed  in  the  liijuid  of  the  compartment  t3. 
The  two  series  of  blades  of  the  mincing  roll  act  like  scissors,  and  do  not  lease  a 
particle  intact  that  comes  in  contact  with  it.  The  mincing  roll  A'  is  likewise 
provided  with  an  endless  web  //;,  and  two  feed  rolls.  M  is  a  rotary  mechanical 
agitator,  \\lmlly  immersed  in  the  water  of  the  tank.  Finally,  a  revolving  endless 
web  X,  dipping  to  the  bottom  of  the  tank,  divides  the  compartment  /:!  into  t\\o 
sections.  The  second  section  of  this  compartment  is  titled  with  a-  series  of 
rollers  R  R  R,  mounted  over  this  after- part  of  the  tank,  so  that  the  under 
rollers  revolve  in  the  water  and  the  upper  just  free  of  it.  Under  each  of  these 
set  of  rolls  is  a  bench  or  table.  The  feed  rolls,  the  rolls  connected  with  the 
endless  webs,  and  the  rolls  A'  A',  move  round  from  left  to  right,  whilst  the  crushers 
/.M  /.-.'  //.:^  tj1(,  mi,u.i,,jr  cylinder  A",  and  the  rotary  agitator  J/,  move  in  an  <>p]  • 
direction.  The  sj>eed  of  the  crushing  rolls  and  the  mincing  cylinder  should  be 
equal  to  about  GOO  to  800  revolutions  a  minute  ;  whilst  that"  of  the  feed  rolls 


380  GUTTA   PERCHA 

and  the  endless  webs  should  only  be  driven  at  a  speed  six  times  less.  The  first 
series  of  rollers  E  R  need  only  turn  at  a  speed  of  fifteen  to  twenty  turns  a  minute, 
whilst  the  last  pair  may  revolve  at  a  great  speed,  so  as  to  give  more  tension  to 
the' substance.  The  first  crusher  Fl  reduces  the  raw  gutta  percha  to  small  frag- 
ments, and  thus  eliminates  a  considerable  quantity  of  earthy  matter  and  other 
extraneous  substances.  The  whole  falls  into  the  water  of  the  compartment  //. 
There  the  particles  of  pure,  or  almost  pure,  gutta  percha  float,  whilst  the  impurities 
fall  to  the  bottom  of  the  tank.  The  endless  band  II2  seizes  hold  of  the  floating 
gutta  percha,  brings  it  to  the  feed  rolls  of  the  second  compartment,  and  causes 
it  to  pass  into  the  second  crusher  F'2.  The  gutta  percha  coming  from  the  surface 
of  the  water  of  the  compartment  t2  is  carried  by  the  endless  web  //3  to  the  feed 
rolls,  then  to  the  crusher  F3,  and  is  thus  crushed  a  third  time  so  as  to  free  it 
from  all  impurity.  The  web  7/4  seizes  it  and  brings  it  to  the  mincing  cylinder 
A",  revolving  at  full  speed,  where  it  is  ground  into  extremely  finely  divided 
fragments,  and  from  which  it  falls  into  the  liquid  in  the  compartment  tB.  The 
rotary  agitator !  M  beats  it  continually  in  the  water  and  finishes  the  purification. 
The  revolving  endless  web  N  conveys  the  purified  gutta  to  the  rollers  ERR. 
From  the  last  of  these  rollers  it  is  taken  by  an  endless  web  0  to  a  pair  of  metal 
pressing  and  finishing  rollers  Yl  Y2,  set  to  the  size  required,  where  it  is 
laminated  and  freed  from  all  interstitial  water.  Passing  over  the  topmost  of 
these  rollers  Y2,  and  over  a  wooden  drum  U,  it  is  wound  on  the  taking-up  roller 
V.  Contrary  to  certain  authors,  the  water  in  the  tanks  should  always  be  cold ; 
if  the  gutta  percha  should  have  an  abnormal  smell,  which  is  very  often  the  case, 


FIG.  126. — Section  of  breaking,  mincing,  and  rolling  machine  and  washers  (Hancock's 

system). 

it  would  be  prudent  to  add  a  little  bleaching  powder.  According  to  Maigne, 
there  is  another  process  having  some  analogy  with  the  preceding.  After  having 
cut  the  lumps  with  a  constantly  moistened  circular  saw  into  irregular  prisms, 
these  prisms  are  submitted  to  a  mincing  machine  like  the  preceding,  with  blades 
and  circular  saws  with  strong  alternate  teeth,  on  which  a  dribble  of  water 
constantly  flows.  The  pulp  thus  obtained  is  washed  three  times  in  cold  water, 
in  the  same  number  of  vats,  through  which  it  is  passed  in  succession,  and  where 
it  abandons  foreign  bodies,  some  dissolved  in  the  liquid,  the  others  in  suspension, 
or  fallen  to  the  bottom.  As  it  is  issues  from  the  last  vat,  the  pulp  is  well  cleansed. 
It  is  then  spread  on  a  pavement  or  on  a  sloping  asphalt  floor,  where  it  is  left 
to  drain,  after  which  it  is  passed  five  or  six  times  between  the  two  cast-iron 
cylinders  of  a  set  of  rolls.  These  hot  rolls  are  1  metre  (3 '28  feet)  long  and  40 
centimetres  (15 '7  inches)  in  diameter,  and  are  heated  internally  by  a  current 
of  %  steam,  and  continually  moistened  on  the  outside.  They  deliver  the  gutta 
percha  in  the  form  of  a  consistent  paste.  The  rolls  are  then  adjusted  so  as 
almost  to  come  in  contact,  so  that  they  can  only  pass  but  a  very  small  quantity 
of  purified  gutta  percha  between  them.  They  are  then  put  in  motion.  This 
fresh  rolling  converts  the  paste  into  very  thin  sheets.  Two  workmen  seize  each 
sheet  as  it  issues  from  the  rolls,  then,  by  a  regulated  pull,  they  stretch  it  so  as 
to  double  its  width,  whilst  at  the  same  time  they  remove  any  small  particles  of 
wood  or  bark  remaining  in  the  paste,  which  are  then  readily  seen.  The  sheets 
thus  produced  being  thin,  dry  rapidly  in  the  air.  When  they  have  lost  nearly 
all  their  water,  they  are  placed  in  a  shallow  pan,  heated  by  a  steam  coil  to  100° 


MECHANICAL   TREATMENT   OF   GUTTA   PERCHA        381 


Kn:.  127.— Slicing  machine  or  ch 


U)    II")   C,    (212     to    I'."''.'    I-'.).       By   the  action  ,,,.   ,1,,-v    ;IIV   ,.,„„ 

plete|\  dried,  and   moreover   they  begin  t.i  enter  into  a    pa-.iv  Minion,  \\hi.-h  cements 
all  their  part-. 

Another  /»•'><•> -KH  ,  m/,/,,,/,,/  more  rtctnthj  in   II  / //.     The  cuttings, 

obtained  from  the  rutting  up  machine,  an-  run  into  an  iron  tank  tilled  \sith 
water,  ami  heated  to  tin-  boiling  point .  Tin-  agitation  produced  b\  tin-  >tcam 
tr tin-  steam  pipe  facilitates  the  washing  of  the  gum,  and  frees  it  from  it- 
impurities.  A  mechanical  agi- 
tator, i..  motion,  greatly  ass  /  Mmm!^ 

in   the    work.        I  lu-  heat    softens 

tin*  gutta  percha,  which  aggluti- 
nates in  the  form  of  irregular 

balk     These    arc    placed    in  a 

larger    cylindrical     wrought  iron 

tank,  in  which  there  is  a  drum, 

fitted  with    IK-HI    toothed  cla\\s, 

touching    tin-    pcrijtlicry  of    the 

cylinder.      The  drum  makes  800 

revolutions    in    a    minute,    tears 

the  ur,im  int.,  threads  of  extreme 

tenuity,     which     a    current    of 

\\ater^  carries    into  a  vat    fixed 

In-low   the   tank.      Owing  to  its 

low   specific  gravity,   the  gutta 

jH-ivlia  floats,  and  the  impurities 

fall    to  tlu-  Mtoni.      The   floating  shredded  gum  is  again  softened  in  uater  of 

!».VC.    (203° F.),    in    which    it   agglutinates,    and   is   again    passed    through    the 

masticator.     Instead   of   mechanical   shredding,   recourse   has  also   been   had    to 

solvents  such  as  carbon  disulphide,  benzine,  chloroform,  etc.,  a.s  purifying  agents. 

The  gutta  percha,  softened  in  the  solvents,  is  introduced  into  the  body  of  a  pump, 

with  very  resistant  sides,   in   which  a  piston  moves  up  and  down.     The  bottom 

of  this  cylinder  is  furnished  with  a  diaphragm  of  perforated  plates,  such  as  are 

used  in  the  hydraulic  pn-sses  of 
vermicelli  works.  These  plates  are 
arranged  in  such  a  manner  that  tilt- 
calibre  of  the  holes  diminish  from 
the  top  plate  to  the  bottom,  the 
meshes  of  which  are  more  num«  r 

ous- 

Instead  of  softening  gutta  i  K-rcha 

by  solvents,  it  has  also  been  pro- 
posed to  proceed  to  purify  it  by 
first  softening  it  by  the  action  of 
heat,  and  then  passing  it  in  that 


condition  into  a  filter  press  like  the 
preceding.  The  jacket  which  sur- 
rounds the  cylinder  enables  tin- 
latter  to  be  heated  by  steam,  and 
too  soon  cooling  of  the  gum  is  in  that  way  piwentrd.  Thi->  >\-tem  of  purification 
is  utilised  to  complete  the  washing  of  the  guni  to  be  purified.  According  to 
Wunschendorti',  the  following  is  the  method  adopted  in  English  factories  in 
the  purification  (properly  so  called)  of  gutta  percha: — The  >•//,•,'//./  m>n'/n'n<'  (Fig. 
1-J7)  consists  of  a  <-a-t  iron  drum  J,  on  the  periphery  of  which  are  inserted 
knives  with  steel  >a\\  teeth.  This  drum  makes  .")()(»  revolutions  a  minute.  The 
pasty  mass  of  gutta  which  is  fed  into  the  hopper  II  passes  U-tween  t\\o  -mall 
rolls  C  and  /),  the  one  with  a  smooth,  the  other  with  a  striated  surface,  which 
leads  them  under  the  drum  A,  the  knives  of  which  shred  it  into  small  pieces. 


FIG.  128.  — English  washing  machine 
(after  Wunschendorff). 


382 


GUTTA   PERCHA 


These  pieces  fall  into  a  large  iron  tank  full  of  cold  water,  beaten  by  an  agitator, 
with  paddles  always  in  motion.  The  gutta  remains  there  for  two  or  three  hours, 
and  is  freed  from  a  fresh  quantity  of  its  impurities ;  it  floats,  whilst  the  extraneous 
substances  sink  to  the  bottom  of  the  reservoir.  After  being  cleaned  in  this  way, 
the  gutta  percha  is  run  into  a  tank  of  boiling  water,  and  when  it  is  sufficiently 
soft,  it  is  washed  thoroughly  in  a  special  machine  called  a  washing  machine.  A 
solid  cylinder  A,  the  surface  of  which  is  covered  with  grooves,  turns  inside  a 
hollow  cylinder  Z>,  pierced  with  holes,  and  itself  enclosed  in  a  hollow  cylinder  C. 


FIG.  129.— Filter  press  (strainer),  English  system  (after  Wimschendorff). 

The  gutta  percha  is  placed  between  the  grooved  cylinder  and  the  cylinder  B  • 
the  interior  of  the  two  annular  cylinders  is  filled  with  water  heated  by  a  steam 
jet  from  the  small  pipe  D.  The  rotation  of  the  grooved  cylinder  compresses  the 
gutta  percha  against  the  cylinder  B,  and  forces  it  to  spread  out.  All  the  portions 
of  the  gutta  percha  thus  come  successively  in  contact  with  the  hot  water,  which 
removes  the  impurities  from  them.  These  collect  at  the  bottom  of  the  cylinder 
C,  and  are  removed  by  the  door  E.  Gutta  percha  treated  in  this  way  most 
generally  contains  only  very  small-sized  particles  of  organic  debris,  which  it  is 
preferable  to  free  it  from  by  a  purely  mechanical  operation.  Too  prolonged 

washing  with  water  has  the  disadvantage  of  incor- 
porating a  certain  amount  of  water  with  the  gutta, 
which  it  is  afterwards  very  difficult  to  completely 
eliminate.  This  purely  mechanical  intervention  is 
accomplished  by  means  of  the  filter  press  (strainer), 
already  described.  The  plant  employed  in  England 
consists  of  a  very  thick  cast-iron  cylinder  A,  open  at 
one  of  its  ends,  and  in  which  a  piston  moves  JB 
(Figs.  129  and  130),  of  which  the  rod  C  is  submitted 
to  the  action  of  a  hydraulic  press,  which  receives  from 
a  horizontal  shaft,  by  means  of  a  toothed  wheel, 
FIG.  130.— Piston  of  above  gearing  witn  a  screw  part  of  the  rod,  a  very  slow 
filter  press  (strainer).  movement  of  translation  towards  the  bottom  of  the 
cylinder.  This  cylinder  is  closed  with  a  strong  iron 

plate,  pierced  with  holes,  on  which  is  placed  a  sheet  of  wire  gauze  with  very  close 
meshes.  The  sides  of  the  cylinder  are  hollowed  (jacketed),  and  filled  with  steam, 
to  prevent  the  gum  from  solidifying.  The  cylinder  being  filled  with  the  gutta 
percha  to  be  purified,  pressure  is  applied  to  the  piston,  the  substance  is  pressed, 
and  forced  to  pass  through  the  wire  gauze,  and  is  collected  in  the  receiver  beneath 
the  cylinder.  When  the  piston  is  1  or  2  centimetres  from  the  bottom,  the  motion  is 
stopped,  and  the  cake  in  which  all  the  impurities  are  collected  is  withdrawn.  Mongin, 
of  Argenteuil,  has  constructed  a  filter  press  (Fig.  131)  built  on  the  same  principle. 


MECHANICAL   TRK ATM KNT   OF   GUTTA    1'KRCHA        383 


process. — A  much   simpler    purifying    prnoMB  was   proposed   :in«l    put 
in    practice    by  G.   (Jerard,    \\hieh    In-   >av<   KDBWen    uell.        It   consists    in   simply 

treating  tin-  crude  gutta  puvha 
with  the  shredder  used  \<>r 
rubber.  Only,  instead  of  culd 

SVater,     lint      \\atlT      is      r!llpl(>\cd. 

If     the     process  \\ould     accont 

plish  tin-   end   in  \ie\\,  it    \\mihl 

evidently  IK-   the  best,  luit  thrrt- 

is     .'s.-i)     rr.i-on  to     doubt     its 

efficiency. 

Drt/iiHj.  —  The  \\aslicd  «riitta 
prr.-ha  i<  placed  in  the  drying 
iivi-n,  a  strain  jacketed  cast-iron 
rectangular  case  A  BCD  (Fi^r. 
\'.\'l}  closed  in  its  upper  part  by 
a  semi-cylindrical  lid  A  E  J), 
provided  with  a  movable  part 
/'.'  /•'.  \\liich  can  be  kept  in 
place  by  solid  imn  bars.  Inside 
the  case  are  two  rolls  with 
parallel  axes,  bearing  lielieoidal 
grooves  iu  opposite  directions. 
and  turning  contrary  to  each 
other.  The  gutta,  seized  between 
the  two  rolls,  spreads  into  the 
empty  grooves,  and  thus  con- 
stantly presents  fresh  surfaces 
to  the  contact  of  the  hot  air  in 
the  case.  The  condensed  water 
collected  in  the  bottom,  is  evacu- 
ated through  0,  the  expelled 
moisture  through  F. 

l\ii"iditnj  or   iwiafirnf. 
Before    trying    to    convert    the 
gutta    peivha  thus   purified   into 
industrially  wrought  articles,  it 
is  necessary  to  free  it  from  all 
traces  of  water,  and  especially 
from  interstitial  air,  and  to  con- 
vert it  into  a  united  homogeneous  mass.     The  elimination  of  air  is  very  imjwrtant, 
because  the  presence  of  the  least  trace  diminishes,  if  it  does  not  completely  sup- 


FIG.  131.— Mongin's  filter  press  (strainer). 


FK;.  132.  — Sect i<.n  of; 

machine   (after   Wunsehen- 


drying 
ch( 


Fi«..  133.— Helicoid  grooves  of 
the  cylinders  of  the  \nf- 
(vdiiii,'  'Irving  niachim-. 


press,  the   adherence  of  its  different  parts.      Purified  ^utta  pereha,  tlu»ret'»iv.  i>  u»t 
employed  without  having  been  passed  through  a  m a-ticator,  a  "devil,"  or  a  "wolf," 


384 


GUTTA   PERCHA 


if  it  be  not  desired  to  work  a  defective  gutta  percha,  called  in  the  language  of  t In- 
trade  strawy  gutta. 

Masticator. — The  purified  gutta  percha  is  softened  in  a  double-bottomed  cast- 
iron  pan  by  steam,  and  then  passed  through  the  masticator  (Fig.  134),  consist- 
ing of  a  cylindrical  case  laid  horizontally,  in  the  axis  of  which  turns  a  solid  cast- 
iron  roll,  the  surface  of  which  is  covered  with  longitudinal  grooves  in  such  a 
manner  that  in  a  cross-section  it  exhibits  the  appearance  of  a  toothed  pinion.  The 
diameter  of  the  roll  is  a  little  less  than  that  of  the  cylindrical  case  which  envelopes 
it.  In  turning,  it  draws  with  it  the  gutta  percha  which  has  been  introduced 
between  the  two,  compresses  it  between  its  grooves  and  the  sides  of  the 
cover,  brings  the  molecules  together,  and  agglomerates  and  binds  them  to  eacb 
other,  whilst  the  imprisoned  air  is  at  the  same  time  expelled.  The  lower  half  of 
the  cylindrical  case  is  often  jacketed,  so  that  a  jet  of  steam  may  be  run  in  as 
required.  The  grooved  roll  is  driven  round  by  means  of  the  pulleys  and  cog-wheels 
shown  in  the  drawing.  At  the  commencement  of  the  masticating  process,  a  current 


FIG.  134. — Leblanc's  masticator. 

of  steam  is  passed  through  the  double  bottom,  the  steam  is  then  regulated  so  as 
to  maintain  a  suitable  temperature,  taking  care  to  take  into  account  the  heat 
produced  in  the  mass  by  friction.  After  having  been  masticated,  gutta  percha  is 
ready  to  be  utilised.  It  is  generally  passed  through  rolls,  converted  into  sheets ; 
it  is  afterwards  stored  in  this  form  in  cellars. 

The  kneading  machine  or  masticator  as  described  by  Obach  resembles  the 
washer,  but  the  roller  has  a  smaller  diameter  and  the  flutings  are  more  numerous 
and  not  so  deep.  The  hinged  lid  is  kept  down  by  a  bar  and  suitable  catches.  The 
gutta  percha  is  kept  hot  during  mastication,  and  the  water  escapes  in  the  form  of 
steam  through  the  large  openings  at  the  top.  The  washers  usually  hold  f  cwt., 
the  masticators  1  cwt.,  and  the  strainers  J  cwt.  of  gutta  percha. 

Obach  determined  the  percentage  of  water  and  dirt  in  various  kinds  of  gutta 
percha ;  some  of  it,  about  3  per  cent.,  is  removed  during  the  preparation  for  the 
washer,  but  the  greater  part  is  eliminated  during  the  first  washing  operation.  The 
straining  hardly  affects  the  percentage  of  dirt.  Straining  is  in  fact  more  of  a 
precaution  to  avoid  large  particles  of  dirt  of  a  fibrous  nature  being  left  in  ther 


MECHANICAL  TREATMENT   OK   GUTTA   PERCH  A 


dean  irutta  |M-rclia.  'I'hr  BOCOnd  u.i-liin^  M|MTation,  th.it  ,i!t.-r  tin-  Mr,  lining,  irt  also 
efficacious  as  it  eliminates  al»out  anotl  .-rut.  Then-  still  remains  al«oi  u  lv 

J«T   rent.  of   impurities  \\liich   are  allowable   l'..r   «;.-n.  -ral    |>ui  i    >|M-,-i.il 

uses  tli.-  pem-iitii-e  «.f  impurities  has  to  be  lowered  to  a  minimum. 

Like   imliaruMier  the  tlifferent  specie**  of  gutta   jM-n-lia    thus    >ntl> 
appreciable  loss  during   tin-    purification    p  ir\in«i  \\itli    tin-   sources   and  the 

qualities.      Tin-  loss  <luriuur  cleaning  and   .Irvin.-:.  syys  Obach,  i-  a  li.-a 

ionally  fully  ~><»  per  cent  Tin-  l"--t  BOrtfl  Mem-rally  !"-«•  1  •")  to  L'U  JHT  cent.; 
intermeiliate  kinds  •_'<)  t«.  •_».")  j^r  cent.  ;  and  int'i-ri"»r  «|Ualit  !••-.  -J.'i  t«.  :i<»  [><•[•  cmt. 
and  iin.iv.  Taking  tin  into  arcmint,  the  cost  price  of  the  puriticd  ^ntta 

pcrcha  can  In-  li\i-d.      Thus   a  siil.xtaiicr  which    is  bought    raw  at    !'_'  fraiic>  tin-  kilo 
^raniinf  (say  4s.  4d.  the  lb.),  and  which    during    i»uriti«-ati«»n    loses  'JO  JKT  cent  . 
fxaniplr,   costs    15    francs    the    kilo^rainn  I.    per   ll».),    without  takinu'   int«» 

ace,  ,iint  th«-  heavy  expenses  incidental  to  pnrilication. 

The   percentage  of  gutta  percha  actually  olttained   in   the   \\nrks  is  invarialily 
louer   than   that    shown   by  analysis.      In  samjiling   both   moisture  and  dirt  escape, 

and  large  stones  are  not  included.  To  counterbalance  this,  an  allowance  i>  made 
of  9  per  cent,  on  the  gutta  percha  found  by  analysis  or  say  (J  per  cmt.  <m  the  raw 
material.  The  J;  is  better  with  cleaned  gutta  percha  than  with  rau  material-.  The 
analysis  extracts  resin  from  raw  material  and  from  wood  and  bark.  This  does  not 
occur  on  cleaning.  Again,  raw  gutta  percha  is  more  porous  and  thus  more  pervious 
to  solvent  than  the  denser  clean  material,  the  resin  is  therefore  more  completely 
extracted  from  the  former  than  the  latter. 


TABLE  CXXII.  —  SHOWING  GUTTA  PERCHA  AND  WASTE  AS  FOUND  BY  ANALYSIS 
AND  AS  ACTUALLY  OBTAINED  ON  WORKS  BY  MniIANICAL  CLEANING 
(OBACH). 


I.  Genuine. 


II.  Sound!.-.          III.   White. 


IV.  Mix., land 
Reboiled. 


Average — 

Gutta  percha  G  +  R  . 

Waste  D  +  W    . 

Ratio  £     . 
Analytical  results — 

Gutta  percha  G  +  R 
proper  . 

Waste  D  +  W    . 

Ratio  [i     . 
Actual  works'  results— 

Gutta  percha  (cleaned) 

Waste  D  +  W    . 

Ratio  2     . 

Ratio  of  G.  P.  by 
analysis  and  on 
cleaning 


'S 

T 

| 

_ 

£ 

*O 

a 

. 

• 

M 

"g 

~-« 

f 

M 

1 

o> 

J 

I 

fi 

1 

J3 

"B 

1 

i 

1 

t 

t* 

p 

1 

I 

M 

BE 

M 

1 

70-3 

70-0 

607 

74-5 

77-6 

70-4 

69-6 

64'5 

51-8 

60-3 

56-8 

72-6 

297 

30-0 

39-3 

25-5 

JIM    29-6 

30-4 

35-5 

487 

397 

43-2 

27-1 

4-3 

2-8 

2-0 

T5 

1-5 

1-3 

1-2 

1-2 

M 

1-4 

0-9 

0-9 

69-8 

70  -o 

61-6 

75-8 

78-9 

-.,.- 

66-8 

65-2 

58-3 

62-6 

587 

74-1 

30-2 

29-5 

38-4 

_'  I  "J 

2M 

87-8 

33-2 

34-8 

11-7 

41-3 

4-2 

2-5 

•2-1 

i-i 

T4 

l-j 

1-1 

1-1 

M 

1-4 

1-0 

0-8 

657 

'••I-7 

68-0 

74-2 

64'3 

;„;., 

64-1 

53-5 

55*5 

34-3 

35-3 

1C7 

25-8 

35-7 

43-6 

35'9 

;•;•:. 

117 

29  -2 

4-2 

2-5 

2-3 

1-4 

1-3 

1-4 

1-2 

1*1 

1-2 

1-4 

1-1 

0'9 

1-06 

1-09 

Ml 

M2 

1-06 

M3 

1-18 

1-02 

1-09 

M3 

1-06 

i  -or 

1-09                       1-10                       I'lO                       1-08 

1-092 

386  GUTTA   PERCHA 

Chemical  purification  of  gutta  percha. — Hancock  (Charles)  in  his  British 
Patent  (11,  208  O.L.)  of  15th  May,  1846,  steeps  raw  gutta  percha  after  being  cut 
into  small  pieces  in  a  caustic  alkaline  lye  or  in  a  solution  of  bleaching  powder  to 
neutralise  acidity  and  remove  any  bad  smell.  If  hot  alkaline  lye  is  used  in  the 
washer  instead  of  water,  the  crude  gutta  is  cleaned  far  better  and  is  much  paler  in 
colour.  Obach  washed  a  particular  raw  gutta  (belonging  to  a  class  which  do  not 
readily  cede  their  impurities)  twice  with  water,  then  rolled  it  out  into  a  sheet  and 
analysed  it.  It  contained  12 '7  per  cent,  of  water  and  1'7  per  cent,  of  dirt. 
Another  portion  of  the  same  raw  gutta  percha  was  washed  with  a  5  per  cent, 
solution  of  caustic  soda,  then  with  water ;  on  being  rolled  out  into  a  sheet  gave  on 
analysis  only  5 -2  per  cent,  of  water  and  0'4  per  cent  of  .dirt.  Alkaline  lyes 
not  only  lower  the  percentage  of  dirt  to  less  than  a  quarter  the  amount,  but  it  also 
reduced  the  capacity  for  retaining  mechanically  enclosed  water.  But  the  washing 
of  gutta  percha  with  hot  alkaline  lyes  or  other  chemicals  must  be  done  with  care 
and  judgment,  and  the  subsequent  washing  with  water  must  be  done  very 
thoroughly,  otherwise  the  gutta  percha  may  be  damaged  and  perish  within  a  short 
period. 

The  chemical  hardening  of  gutta  percha. — Obach  hardens  gutta  percha  by 
extracting  the  resin  from  it  by  petroleum  ether  extraction  plant  on  a  large  scale. 
He  uses  gasolene  of  0'65  to  0'67  gravity.  He  first  chops  the  gutta  percha  then 
throws  it  through  a  screen  on  to  a  long  drying  platform  heated  underneath  by 
steam  pipes.  It  is  shovelled  along  and  continuously  turned  over  until  it  reaches 
the  end  of  the  first  platform,  where  it  is  thrown  on  to  a  second  and  lower  platform 
and  then  similarly  moved  along  to  the  other  end.  It  is  then  fairly  dry,  but  to  com- 
pletely dry  it,  it  is  thrown  into  a  hopper  of  a  long  iron  drum  with  narrow  shelves, 
which  take  it  round  a  certain  distance,  when  the  drum  is  rotated  and  at  the  same 
time  moves  it  along,  since  the  rotation  axis  is  slightly  inclined  towards  the  other 
end.  A  gentle  current  of  warm  air  passes  through  the  drum  in  an  opposite 
direction,  carries  away  the  moisture  given  off  by  the  material  and  so  accelerates 
drying.  After  leaving  this  drum  the  pieces  enter  a  sifting  drum  and  the  coarser 
pieces  move  along  inside  until  discharged  at  the  other  end,  where  they  fall  into  an 
upright  iron  vessel  fitted  with  a  distributing  arrangement.  But  the  finer  material 
drops  on  to  an  endless  band  and  is  carried  to  a  bin.  The  coarse  and  fine  matter 
are  thus  separated.  A  galvanised  iron  tank,  fitted  with  a  hinged  lid  and  a  movable 
plate  in  front,  and  capable  of  being  carried  about  by  an  overhead  travelling  crane, 
is  first  charged  with  a  layer  of  coarse  pieces  from  the  upright  iron  vessel,  then  with 
finer  stuff  from  the  bin,  and  finally  with  coarse  pieces,  the  depth  of  each  layer  de- 
pending on  the  material.  This  facilitates  percolation  during  extraction.  The 
bottom  of  the  tank  is  perforated  and  fitted  with  wire  gauze,  when  charged  it  is 
deposited  in  one  of  a  series  of  larger  tanks  connected  up  en  cascade  by  piping. 
These  tanks,  after  each  having  received  one  of  the  smaller  ones  filled  with  raw 
gutta  percha,  are  worked  in  groups  of  three.  Gasolene  from  a  large  store  vessel 
overheated  is  admitted  to  No.  1  tank  of  each  group  and  flows  over  into  No.  2  and 
thence  into  No.  3,  filling  all  three  in  succession.  The  circulation  of  the  spirit  is 
continued  until  it  is  found  to  be  quite  clean  as  it  leaves  No.  1.  This  tank  is  then 
disconnected  from  the  other  two  and  a  tank  with  fresh  raw  material  connected 
with  the  former  No.  3.  The  former  No.  2  now  becomes  No.  1,  and  so  on.  The 
solution  from  No.  3  is  pretty  thick,  containing  a  large  amount  of  resin.  It  is  run 
into  a  tank,  and  from  there  in  a  continuous  stream  into  a  large  still  fitted  with  a 
steam  coil  at  the  bottom.  The  contents  of  the  still  are  heated,  the  spirit  distilled 
off  and  condensed  in  a  suitable  cooling  arrangement,  which  delivers  it  into  the 
main  store  tank  in  the  cellar,  whence  it  is  pumped  up  again  into  the  feed  tank.  The 
spirit  from  tank  A  is  run  off  into  the  store  tank,  the  gutta  percha  further  washed 
with  clean  spirit,  then  allowed  to  drain  whilst  communication  still  exists  with  the 
store  tank.  The  inner  tank  is  now  lifted  out  and  brought  in  front  of  a  large 
masticator.  It  is  laid  on  its  side,  pushed  into  the  masticator,  and  the  contents 
discharged  by  withdrawing  the  side  of  the  tank  which  now  forms  the  bottom,  the 


MECHANICAL  TREATMENT  OF   GUTTA   PERCH  A        387 


masticator  having  be,  -n  previously  tilled  with  cold  water.  .  \fter  remo\iii:4  the 
t;ink,  tin-  laru'e  s\\inur  ,|1M,r  «»f  tin-  masticator  is  closed.  Steam  is  tunnel  mi  ami 
tin-  roller  -ft  in  ninti'iii.  >..  a>  t"  knead  the  y;utta  perdia  \\liil-t  tin-  solvent  is  \>uing 
distilled  oil'.  When  tin-  distillation  ceases  thr  remainin;:  \  ••  blo\\n 

into  tin-  eondeiKer  by  steam,  the  masticator  is  then  opened,  the  ^una  per,  -ha  taken 
out  and  washed  in  tin-  u-iial  way  with  water,  ,.r  if.  necessary  \\ith  an  alkaline 
solution.  Tin-  distillation  of  tlie  resinous  solution  is  earried  on  until  the  contents 
of  thr  still  ha\e  become  very  thick  and  the  solvent  in  consequence  distils  over  .,nly 
tardily.  The  supply  •,!'  fresh  solution  is  then  interrupted,  the  \al\e  U-tueen  -till 
and  condenser  closed,  luit  the  heitin^  continued  until  a  certain  prc>>ure  ha-  lieen 
produced  l.y  the  vapour,  \\hich  is  tlien  utilise.l  to  foree  the  contents  ..f  the  still 
into  another  still  situated  at  a  safe,  distance  outside  the  building,  where  the  h«-a\i«-r 
[.arts  of  the  solvent  are  distilled  off  by  direct  lire  heat.  The  .-.•ntt-nts  of  the  still 
are  then  disehai'^ed  through  a  kind  of  treacle  valve  and  run  into  Barrels  or  other 
suitable  receptaclefl  for  further  usi-  or  >ale.  All  the  variou-  tank-  are  e.,nneeted 
!>y  a  >\-t"in  of  steam  pipes  and  air  pipes  pro\ivi,,n  l»ein^  made  that  flamcH  cannot 
spread  from  oiu-  to  the  other  in  case  of  fire.  The  main  pij»e  of  this  system  is 
finally  carried  to  the  vessel  containing  the  coarse  pieces  of  dried  gutta  percha  (1 
of  these  vessels  ore  u-ed  alternately).  The  air  in  passing  through  the  gutta  percha 


Fn..  135.— Mixer  with  three  cyli 


Siemens'  factory,  London. 


l>efore  1.1-in.i:  discharged  into  the  ojKin  is  thus  deprived  of  all  vapours,  which  is  very 
rable  for  safety  as  well  as  economy.  Obach  describes  an  experiment  to 
demonstrate  the  efficacy  of  the  hardening  process.  Two  pieces  of  raw  gutta  percha 
are  cut  from  the  same  block;  one  piece  is  kept  in  its  original  condition,  but  the 
other  is  heated  with  petroleum  spirit  to  extract  the  resin  as  completely  as  possible, 
and  tlu-n  freed  from  the  resin  hi  >''i<'n<>  at  a  slightly  elevated  temi>erature.  A  large 
vessel  containing  water  is  heated  on  a  sand  bath  until  the  water  acquires  a  tem- 
perature of  50  per  cent.  A  smaller  glass  Leaker  also  containing  water  is  immersed 
in  the  outer  vessel,  and  its  contents  therefore  have  practically  the  same  temperature 
or  if  it  should  Ke  different  a  slightly  lower  one.  The  original  matter  is  now  thrown 
into  the  inner  vessel  and  the  hardened  one  into  the  outer,  and  they  are  left  there 
for  a  short  time  until  they  have  acquired  the  temperature  of  the  water.  The  p: 
of  treated  «;iitta  percha  is  then  squeezed  between  the  fingers,  but  it  resists  the 
-ure  as  it  is  still  quite  hard.  The  >ame  test  is  applied  to  the  origipal  material 
inside  the  Leaker,  and  it  will  be  found  to  be  quite  soft  and  plastic. 

Tin-  mii-iii'i  nt'  </nff<r  /»  ,-r/t<i. — Purified  -jntta    peivha    is  often    mixed  with  other 
substance-,  either  to  ln\ver  its  cost  or  to  make   it    harder  and  more   resistant.      The 
substances  most  often  used  are  chalk,  sulphate  of  lime,  sulphate  of  baryta  (ban: 
asplialtum.  oxides  of  xine  and  of  lead.  etc.  etc.     By  varying  the  proportions  and 
the  nature  of  the  substances  incorporated  with  gutta  i>ercha,  products  of  variable 


388 


GUTTA   PERCHA 


consistency  are  obtained,  which  are  for  the  most  part  firmer,  but  very  inferior  to 
the  primitive  product.     By  adding  a  certain  amount  of  caoutchouc,  its  suppleness 


FIG.  136. — Mixer  with  three  cylinders  at  work  iii  Messrs.  Siemens'  factory,  London. 


FIG.  137. — Mixer  with  three  cylinders  at  work  in  Messrs.  Siemens'  factory,  London. 


FIG.  138.— Mixer  with  three  cylinders  at  work  in  Messrs.  Siemens'  factory,  London. 

and  elasticity  are,  on  the  contrary,  increased.  An  infinite  number  of  substances 
may  be  incorporated  with  gutta  percha,  and  from  that  fact  alone  it  will  be  easily 
perceived  that  an  infinite  number  of  mixtures,  endowed  with  different  properties, 


MKCHANICAL  TREATMENT   OF  GUTTA   PERCHA        389 


may  U'  obtained.     Tin*  incorporation  <>f  accessory   sul  \\ith  gutta  |»ercha 

may  be  dour  i  luring  mastication.  Tin-  purified  ^utta  pnvha  is  tir-l  ma-tinitecl 
ami  urolith!  I,,  tin-  machine  until  it  is  \\ell  si,|'t.-ni-d.  Tin-  -ul-tun<  •<•>  in  tine 
J»»\M|«T  aiv  tln-n  -ra«luall\  int  1-1  M|II»T.|  int<.  tin-  iiia->t  ic;it«.r,  \\liidi  is  put  in  iiiMtimi. 
ami  inaili-  t«>  ad  until  tin-  ma--  become!  li'»m<>^riir«.u-.  'I'liis  process  of  uiixinu', 
"i-  mastication,  ]\.^  the  .li-a-Kaiitaur  «\  not  alu,i\-  ounplrtrly  i-liiiiinatin^  th«- 


air-bells.  Now,  for  certain  uses,  such  for  example  as  the  manufacture  of  sub- 
marine cables,  one  of  the  essential  conditions  of  perfect  success  consists  in 
obtaining  a  paste  tree  from  all  traces  of  these  air-bells.  The  masticator  shown 
in  Fig.  134  has  been  designed  with  this  end  in  view.  Like  the  ordinary  masticator, 
this  machine  consists  of  a  steam-jacketed  cylindrical  vessel,  but  instead  of 
having  only  one  grooved  cylinder  it  is  provided  with  three  of  these  organs.  The 


390 


GUTTA  PERCHA 


masticating  cylinders  are  much  less  in  diameter  than  the  interior  periphery  of  the 
vessel  and  each  of  them  is  furnished  along  its  length  with  a  cutting  blade,  fixed 
somewhat  crosswise,  and  slightly  twisted.  This  blade  does  not  tend,  the  sides 
of  the  vessel,  from  which  it  is  always  5  centimetres  (say  2  inches)  apart.  A 
drivino-  shaft  gears  on  to  the  cogwheel  fixed  at  one  extremity  of  the  cylinder,  and 
imparts  to  it  a  speed  of  twenty-five  revolutions  a  minute.  Each  of  these  masticat- 
ing cylinders  is  arranged  in  such  a  way  that  its  driving  wheel  is  in  an  opposite 
direction  to  its  neighbour.  The  cylinders  therefore  revolve  in  opposite  directions, 
in  direction  of  arrows.  Their  relative  speed  against  one  another  is  about  4  to 
5.  It  is  in  this  arrangement  that  the  economy  of  the  machine  consists,  for,  whilst 
the  cylinders  work  with  different  speeds,  the  cutting  edges  meet  each  other  at 
each  revolution  in  different  places,  and  cut  the  gutta  percha  each  time  at  a  fresh 
spot.  As  soon  as  cut,  the  substance  is  pushed  through  the  empty  space  which  is 
produced  between  the  blade  and  the  cylinder  as  far  as  the  centre,  where  it  is 
again  cut,  finally  going  to  the  right  or  to  the  left,  where  the  wings  of  the  cutting 
blades  raise  it  up  on  to  the  cylinders,  so  as  to  cause  it  to  again  fall  to  the  centre. 
In  this  way  the  gutta  percha  never  remains  agglomerated  into  a  single  mass,  and 
is  always  being  cut,  now  on  the  one  side,  and  again  on  the  other ;  it  is  masticated 
throughout,  eliminating  any  small  air-bells  which  it  may  contain.  This  process, 
it  is  said,  yields  a  perfect  gutta  percha,  whilst  it  only  takes  half  as  long  as  the 
ordinary  process.  The  cylinders  are  hollow,  so  that  the  substance  does  not 


Fio.  140.— -English  rolling  mill  (after  Wunschendorff). 


become  adherent  during  the  process,  and  a  current  of  cold  water  is  passed  through 
as  required.  As  it  comes  from  the  masticators,  gutta  percha  is  ready  for 
industrial  use,  whether  it  be  used  directly,  oriafter  it  has  been  converted  into 
sheets,  by  being  rolled,  and  in  that  form  subjected  to  ulterior  operations. 

Lamination  or  rolling, — The  soft  gutta  percha  from  the  kneading  machines 
is  laid  on  a  table  in  front  of  a  pair  of  parallel  rollers.  I*,  is  then  fed  between  the 
two  very  smooth  rolls,  turning  in  opposite  directions ;  the  substance  passes  through 
the  free  space  between  the  two  rolls,  and  is  caught  by  a  long  endless  web,  of  the 
same  width  as  the  rolls  on  which  it  travels,  some  distance  to  and  fro,  until  it  is 
sufficiently  cool  and  hard  to  be  sent  into  the  shorter  lengths  for  storing.  The 
thickness  of  the  layer  of  gutta  percha  is  about  2  centimetres  (say  f  of  an  inch) ; 
it  is  cut  into  pieces  of  30  to  40  centimetres  (say  11 -8  to  15 '7  inches)  wide,  so  as 
to  form  sheets  which  can  be  stored  in  the  cellar,  protected  from  the  air,  light,  and 
dust,  until  required  for  use  (which  gives  ^  to  J  inch  thick  and  6  feet  in  length  as 
suitable  dimensions). 

French  methods. — The  English  method  of  purification  has  now  been  given 
with  full  details.  French  manufacturers,  whilst  seeking  a  high  degree  of 
perfection  in  their  products,  aim  at  more  simple  methods.  At  Benzons,  gutta 
percha,  as  it  comes  from  the  mincing  machine  and  simply  re-heated,  is  brought 
direct  to  the  filter  press,  and  from  there  into  the  washing  machine  called  the 
Truman  (Fig.  143)/ of  quite  a  special  arrangement  (British  Patent,  637;  1861). 


MECHANICAL  TREATMENT  OF   GUTTA   PERCHA        391 

This  washing  machine  consists  of  three  rolls,  of  about  10  cent  inn -tivs  (say  4 
indies)  in  diameter,  arranged  at  intervals  «.('  iL'O  round  a  central  axis,  to  which 
they  a  IT  lixed  l.y  ca-t  inm  CgOOfl  pieces,  ami  driven  l.y  tin-  u'eneral  Imri/mital  -haft 
of  the  lart.,r\.  The  axis  turns  with  the  three  rolls,  inside  a  hol|o\\  ca-t  iron 
cylinder,  furnished  \\ith  a  lid,  which  is  pierced  l.y  two  lar^e  \\<>\c-  /,'.  \shidi  may 
l>e  tiniily  fixed  on  the  cylinders.  The  whole  is  endued  in  a  lar-e  wrought-iron 
I/  .V  O  /',  tilled  \\ith  water.  The  gutta  percha,  pressed  by  the  rolls  against 
the  cylinders,  constantly  presents  fresh  surfaces  to  the  contact  of  the  water,  and 
abandons  a  portion  of  its  impurities,  which  fall  to  the  bottom,  whence  they  are 
\\itlulrawn  when  the  operation  is  terminated.  The  gutta  percha  is  treated  for 
two  hours  at  least  in  the  machine,  and  then  wrought  in  the  drying  masticator, 
which  is  in  every  \\ay  analogous  with  the  English  drying  machine.  The  grooves, 
however,  are  interrupted  on  the  cylinders  at  intervals  of  10  centimetres  (4  inches), 
so  as  to  force  the  material  in  contact  with  the  air  to  renew  itself  more  frequently. 
As  it  issues  from  the  masticator,  the  gutta  goes  directly  to  the  rolling  mills.  In 
M  filler's  factory  at  Grenelle,  the  rolls  of  the  laminator  are  very  close  to  each 
other,  so  as  to  produce  very  thin  sheets,  which  are  exposed  to  the  air  for  seven  or 
eight  days,  so  as  to  dry  completely.  These  sheets  are  then  re-masticated,  and 


FIG.  141. — Truman  (after  Wunschendorff). 

passed  through  a  second  rolling  mill,  which  yields  cakes  for  warehousing.     This 
gutta  contains  less  water,  but  it  is  more  liable  to  oxidation. 

Bleaching  of  dental  gutta  percha. — The  dental  profession  utilise  gutta  percha, 
not  only  as  a  mastic  to  fill  the  gaps  due  to  caries,  but  also  to  make  mouth-plates 
for  artificial  teeth.  The  substance  ought  to  be  perfectly  white  for  this  special  use, 
and  it  will  not  be  out  of  place  to  know  the  different  bleaching  processes  adopted. 
In  a  close  vessel  500  grammes  of  gutta  percha  are  digested  with  10  kilogrammes 
of  chloroform  (say  j  Ib.  of  gutta  percha  and  10  Ib.  of  chloroform).  When  the 
substance  is  entirely  dissolved,  200  to  300  grammes  of  water  (say  3  to  5  oz.  for 
the  above  English  proportions)  are  added  and  energetically  stirred,  and  the  mixture 
abandoned  to  itself  for  a  fortnight.  All  impurities  collect  on  the  surface  of  the 
water,  floating  on  the  chloroform.  The  clear  limpid  solution  is  drawn  off  into  a 
porcelain  dish,  fitting  into  a  copper  still  made  for  the  purpose.  After  covering  the 
liquid  with  a  small  layer  of  pure  water,  water  is  run  into  the  still  up  to  about  the 
third  of  the  exterior  height  of  the  porcelain  dish,  and  the  chloroform  is  distilled  off. 
The  white,  slightly  yellowish,  rather  honeycombed  residue  consists  of  purified  gutta. 
Sometimes,  before  distilling,  the  solution  is  treated  by  animal  charcoal,  which 
makes  it  still  more  white.  This  honeycombed  mass  is  masticated  so  far  that  it 
may  be  made  into  very  homogeneous  sticks,  which,  preserved  for  some  time  in  ether 


392 


GUTTA  PERCHA 


or  alcohol  become  more  and  more  decolorised,  and  end.  by  taking  a  white, 
LphTnous  appearance,  like  the  best  ivory.  All  trace  of  chloroform  must  be 
eliminated,  other  wise  the  gutta  percha  will  become  brittle 

Another  process.-0ne  part  of  fine  gutta  percha  is    dissolved   in  2 J  ]»ait, 
weight  of  hot  benzol,  and  ^  P^t  of  plaster  of  Paris      After  digesting  for  two 
dayX  the  perfectly  limpid,  liquid  portion  is  decanted,  then  poured  into  twice  i 
volume  of95  per  cent,   alcohol.      The  gutta  percha  is  precipitated  as  a  white, 
brilliant,  rather  soft  mass,  which  is  collected,  masticated  and  preserved  m  block 
in  a  place  free  from  all  contact  with  dust  and  light      If  it  be  desire d  to ,  im: 
the  natural  rose  colour  of  the  gums,  one  part  of  cochineal  carmine  for  8 
parts  of  gutta  percha  is  crushed  in  a  little  water,  thickened  with  gum  arable   and 
the  product  mixed  with  the  chloroform  solution   before  distilling, 
tion  residue  takes  a  uniform  rose  tint  when  masticated. 

Reclamation    of  gutta   percha    waste.— The    processes    for    reclaiming    gutta 
percha  waste,  whether  from  old  objects,  worn  out  through  long  use  or  whether 
simple  factory  waste,  are   very  simple.  .  Certain    precautions   must,  however,   t 
taken  if  a  really  practical  result  be  desired.     All  old  articles  are  not  equally  worth 
reclaiming,  and  it  would  be  better  to   neglect  some  of  them   altogether. 


Fm.  142. — Masticating  drying  machine  (after  Wunschendorff). 

bottles  which  have  been  used  to  hold  acids  for  some  time,  and  chiefly  hydrofluoric, 
are  worthless.  They  cannot  be  again  "  cured,"  according  to  the  typical  expression 
of  Guillot,  one  of  our  most  skilful  practical  men  in  this  class  of  industry,  who, 
with  his  usual  courtesy,  has  been  good  enough  to  initiate  the  authors  into  the 
little  secrets  of  his  manufacture.  It  is  the  same  with  certain  photographic  dishes, 
which,  after  a  certain  time,  resinify  completely.  It  is  then  impossible  to  soften 
them  so  as  to  utilise  them  again.  One  of  the  best  kinds  of  gutta  percha  waste  is 
that  from  spindles  for  weaving,  whether  it  comes  from  spindles  discarded  by 
too  long  use,  or  whether  it  consists  of  cuttings  originating  in  the  manu- 
facture of  these  appliances.  In  regard  to  waste  wires  of  electrical  conductors, 
a  previous  sorting  out  is  necessary,  some  being  really  of  superior  quality,  others 
being  prepared  with  very  inferior  guttas,  often  mixed  with  vulcanised  rubber. 
The  latter  sorts  are  reclaimed  with  exceeding  great  difficulty,  and  the  industrial 
results  obtained  are  of  little  commercial  value.  The  best  thing  to  do  with  waste 
of  this  nature  is  to  heat  it  in  water  to  which  a  little  caustic  soda  has  been  added, 
then  to  swell  it  in  benzine  or  spirits  of  turpentine.  In  this  condition  it  is  passed 
to  the  filter  press.  The  solvent  employed  is  evaporated  at  a  rather  low  temperature. 
The  product  obtained  is  used  as  an  adjunct  in  a  fresh  manufacture  of  the  same 


MECHANICAL  TREATMENT  OF   GUTTA   PERCHA 

i 


393 


kind.  II<>\vr\vr,  tin-  reclaimed  \\a-te  i-  far  from  I.eini:  e^ual  in  value  to  tliat 
about  to  In-  de-cril)rd.  Tlit-  tollo\\inur  is  the  pn.ce—  generally  adopted  to  work  up 

-iitt-i  percha  waste  of  a  good  quality  :     The  manufacturer  lia\inur  a  lot  of  knoun 

value  and  composition,  softens  it  in  ordinary  wati'r  at  admit  tin-  luiiliiig  jNiint. 
If  the  ^utta  peivha  l>e  m»t  too  resinilied,  this  softening  is  soon  accomplished  (in 
jilmiit  one  hour).  In  tin-  contrary  0886,  the  time  required  is  longer,  and  pn.por 
tional  to  the  altt-ration.  The  siitlicit-nt  ly  plastic  substance  is  taken  from  the  pan 
}>vja  sho\i-|,jand  throun  on  the  floor,  lini-d  \\itli  a  piece  of  tinned  sheet  iron,  in 


' 


Fi«;.  143.— Masticator,  Bertram,  Leith. 

front  of  a  set  of  double  rolls,  capable  of  bciiuj  set  at  various  distances.  After 
having  sufficiently  moistened ^ the  rolls,  to  prevent  adherence,  the  very  hot  paste 
is  passed  several  times  between  the  rolls,  pa--in^  them  each  tinu1  in  a  direction 
contrary  to  that  of  the  preceding  passage,  so  as  to  obtain  the  greatest  po— ilile 
homogeneity,  and  leaving  a  siitlieient  space  lietween  the  rolls  for  the  cake  to  pass 
through  with  such  rapidity  that  it  has  not  time  to  get  cool.  As  it  comes  from  the 
cylinder,  the  gutta  percha  is  each  time  rolled  upon  itself  so  as  to  forma  rather 
bulky  Mock,  which  the  workman  receives  on  his  table,  or  \\hirh  he  seizes  by  hand, 


394  GUTTA  PERCHA 

to  again  pass  it  through.  Finally,  the  rolls  are  squeezed  near  to  each  other,  and 
the  cakes  obtained  are  passed  through  a  second  time,  but  this  time  without  retold 
ing  the  sheet  on  itself,  but  allowing  it  to  spread  out  in  a  flat  "  pig"  on  the  shed 
of  tinned  iron  below  the  rolls.  Unless  the  waste  so  reclaimed  be  intended  to  In- 
used  forthwith,  the  sheets  are  stored  in  a  place  protected  from  air,  light,  and 
moisture,  to  be  sold  later  on,  or  made  into  articles  of  manufacture.  In  the  latter 
case,  whether  the  waste  be  used  alone,  or  whether  it  be  mixed  with  fresh  gutta 
percha,  the  sheets  are  again  softened  in  a  bath  of  hot  water,  and  passed  between 
the  laminating  rolls,  but  this  time,  after  being  spread  between  two  sheets  of  tinned 
iron,  which  pass  between  the  rolls  at  the  same  time  as  the  gutta  percha,  to  be 
rolled.  The  sheets  of  reclaimed  gutta  percha  are  thus  uniformly  extended  between 
the  sheets  of  tinned  iron,  and  the  desired  thickness  is  obtained,  regulating  ap- 
propriately the  distance  between  the  rolls.  Gutta  percha  waste  (generally  black) 
loses  its  colour  more  and  more  after  a  prolonged  passage  through  hot  water,  and 
reclaimed  gutta  percha  thus  acquires  a  chocolate  brown  colour,  which  becomes  less 
and  less  intense.  If,  finally,  the  waste  be  much  oxidised,  it  is  better  to  use, 
instead  of  ordinary  water,  water  rendered  alkaline  by  a  little  caustic  soda.  It  is 
necessary  to  conduct  this  operation  with  great  caution,  so  as  not  to  deteriorate  the 
substance. 

The  so-called  vulcanisation  of  gutta  percha. — In  a  number  of  treatises  in  the 
special  literature  of  the  subject,  processes  for  the  vulcanisation  of  gutta  percha  are 
treated  with  the  greatest  of  seriousness.  That  it  was  attempted,  in  the  first 
moments  of  infatuation,  to  apply  vulcanisation  to  gutta  percha  may  be  readily 
conceived,  but  it  is  incomprehensible  how  chemists  of  the  standing  of  Heinzerling 
could,  thirty  years  after  the  first  attempts,  still  describe  the  early  formulae,  although 
they  knew  perfectly  well  that  the  action  of  sulphur  and  halogens,  far  from  having 
a  satisfactory  action  on  gutta  percha,  are,  on  the  contrary,  injurious  to  it,  and  can 
only  compromise  the  value  of  a  substance  the  selling  price  of  which  is  already 
sufficiently  high,  without  spoiling  it  foolishly  and  unreasonably.  Heinzerling,  after 
having  described  at  length  what  has  been  attempted  in  this  connection,  concludes 
with  this  melancholy  phrase,  which  well  depicts  the  small  confidence  which  he 
accords  to  these  processes  :  "  We  have  giv&n  these  ^ocesses  of  vulcanisation  to  be 
complete,  but  we  cannot  believe  that  at  the  present  time  any  one  still  makes  articles 
of  vulcanised  gutta  percha"  It  will  be  well  to  pass  the  unfortunate  experiments 
silently.  Homogeneity  and  plasticity  being  the  principal  qualities  to  exact  from 
gutta  percha,  too  great  care  cannot  be  taken  to  prevent  the  introduction  into  it  of 
a  body  which  would  diminish  this  homogeneity,  and  which  would  deprive  it  to  a 
great  extent  of  its  plasticity.1 

1  Fayol,  Lc  Caoutchouc,  1909,  p.  122,  treats  the  vulcanisation  of  gutta  percha  quite 
seriously.  He  says  "it  is  washed,  scoured,  reduced  to  sheets,  masticated  and  laminated, 
then  it  is  vulcanised  with  2  to  3  per  cent,  of  sulphur ;  it  is  also  vulcanised  with  orpiment. 
This  operation  renders  it  less  fusible  and  gives  it  more  resistance  towards  acids. 


CHAPTER  VII 
M  KTHODS  OF  ANALYSING  GUTTA  PERCHA. 

Crudt  iintt'i  percha.-  Is  there  any  need  of  insisting  M]HUI  ilie  necessity  for  a 
method  of  analysing  commercial  gutta  percha?  As  in  tin-  case  of  robber,  the 
principal  physical  properties  characteristic  of  each  of  the  principal  commercial 
varieties  an-  uiven  in  a  synthetic  Table;  lint  such  data  are  not  sntl'n-ient  \\hen  it  is 
a  question  of  important  jmrchases  or  delicate  work,  such  as  covering  the  insulators 
ot'  electric  wireB,  ami  especially  of  those  of  submarine  telegraph  cables.  If  it  be 
useful  tor  manufacturers  to  know  (a)  the  precise  quantity  of  water  exceeding  the 
normal,  (6)  the  total  amount  of  the  inert  substances,  accidentally  or  intentionally 
interposed,  («•)  the  ijiiantity  of  oxidised  or  resinified  gutta,  (d)  the  total  amount  of 
ash  which  would  be  produced  on  incineration  of  each  of  the  varieties  on  the  market, 
it  is  also  necessary  to  know,  (e)  at  least  approximately,  the  quantity  and  nature  <>f 
the  foivimi  resins  incorporated  intentionally  into  gutta  percha  (1)  to  lower  the 
price,  or  (2)  rather  to  increase  the  profit  of  the  collector,  the  native  merchant,  the 
middleman  required  between  the  working  collector  and  the  merchant  of  Maca->ar 
or  Singapore.  If  a  determination  of  (/)  its  tensile  strength  is  likewise  useful,  tin-re 
is  still  a  more  indispensable  test  when  it  is  a  question  of  making  wires  for  sub- 
marine cables,  namely,  (c/)  the  specific  electrical  resistance  of  any  given  sample  of 
gutta  percha. 

1.  Sampling  and  moisture  determination. — The  methods  pursued  are  those  de- 
scribed for   the   analysis   of   crude   rubber.     Montpelier,  chemist  of  the  French 
Telegraph  Administration,  prescribes  that,  in  the  estimation  of  water,  the  gutta 
percha  to  be  tested  should  be  dried  at   100°  to  110°  C.    (212°  to  230°  F.)    in  a 
current   of  carbonic  acid.     The  oxidation  of  the  gutta  percha  is  thus  prevented, 
and  there  is  no  reason  to  fear  an  increase  in  weight  which  may  exceed  that  of  the 
water  evaporated.     Water  can  be  determined  with  sufficient  accuracy  for  most 
practical  purposes  by  gently  heating  a  weighed  quantity  first  in  the  open  air  and 
then  ///  vacuo  over  an  absorbent  substance  until  no  further  loss  occurs,  but  some- 
times it  has  to  be  ascertained  by  direct  weighing.     Obach,  in  the  analysis  of  cleaned 
urutta  percha,  heats  the  gutta  percha  in  a  current  of  rarefied  air  or  hydrogen,  and 
absorbs  the  moisture  in  sulphuric  acid  in  a  weighed  U-tube.     The  gutta  j>ercha, 
preferably  fee  a  thin  sheet,  is  cut  into  small  pieces  and  divided  into  two  portions;  in 
one  the  water  is  determined  by  heating  in  a  current  of  rarefied  air  or  hydrogen,  and 
absorbing  the  moisture  by  sulphuric  acid  in  a  weighed  U-tube  ;  in  the  other  portion, 
re-in.  initta,  and  dirt  are  determined. 

2.  Ash. — The  ash  in  pure  gutta  percha  should  not  exceed  0'570  per  cent. 

:;.  I'n/tnifimi  t'rnni  'iii'i/i/tical  results. — Finally,  according  to  the  numerous 
experiments  of  Lagarde,  the  gutta  perchas  used  as  dielectrics  having  a  maximum 
of  (K><>  per  cent,  of  mineral  matter  and  5  per  cent,  of  water  are  held  to  be  good 
\\hen  they  contain  at  least  58  to  60  j>er  cent,  of  pure  gutta,  and  very  good  with 
(I.")  per  cent. 

4.  Adventitious  wyetaftte  ati>l  mimral  matter. — The>i-  are  determined  in  the 
lumps  as  in  the  case  of  rubber,  but,  instead  of  spirits  of  turpentine  or  benzol  as 
solvent,  it  is  preferable  to  use  carbon  disulphide  and  toluene,  which  dissolve  gut  t  a 
percha  better  than  all  other  vehicles. 

395 


396  GUTTA  PERCHA 

5.  Resin.— This  is  one  of  the  most  important  points  in  the  analysis  of  gutta 
percha,  namely,  the  determination  of  the  oxidised  resinous  principles  which  are 
naturally  present  in  the  sample,  and  the  amount  and  nature  of  the  resina  ac- 
cidentally added  for  some  purpose  in  one  way  or  another.  The  point  is  diUiriilt 
and  complex,  and,  without  completely  solving  the  problem,  the  following  are  some 
useful  hints :— The  method  of  preparing  pure  gutta  and  separating  it  from  nuavile 
and  albane  furnishes  the  most  natural  analytical  method  for  determining  the 
amount  of  the  oxidised  products  which  always  accompany  gutta  percha.  This 
amount  varies  with  the  nature  of  the  plant,  its  age,  the  soil,  and,  finally,  with  the 
more  or  less  recent  date  of  the  preparation  of  the  gum  resin.  But  this  process, 
based  on  the  prolonged  boiling  and  repeated  washing  of  the  finely  divided  raw 
product  in  95  per  cent,  alcohol,  has  the  drawback  of  extracting  a  little  gutta  percha 
in  the  alcoholic  solutions,  and  cannot  be  regarded  as  rigorously  exact.  The  boiling 
alcoholic  solution  contains,  besides  albane  and  nuavile,  the  foreign  resins  used  to 
sophisticate  the  commercial  product,  as  well  as  the  oxidised  resins  due  to  contact 
with  air  and  light.  The  following  is  the  method  adopted  by  the  authors  in 
the  analysis  of  a  commercial  gutta  percha  whose  abnormal  structure,  colour,  and 
smell  pointed  to  an  evidently  adulterated  gutta  percha,  and  which  had  certainly 
become  oxidised  after  its  preparation.  By  the  previously  described  process  there 
was  found  in  the  sample  analysed — 

Abnormal  water  .  .  .  4 '5  per  cent. 

Vegetable  debris  and  mineral  matter      .  3'0      ,, 

Pure  gutta  ....  68'0      „ 

The  boiling  alcoholic  washings  were  allowed  to  stand  for  five  days  at  a  tem- 
perature of  10°  C.  (50°  F.),  then  repeatedly  filtered  until  the  filtrate  was  perfectly 
limpid.  The  granular  precipitate,  which  consisted  of  albane  and  nuavile,  dried 
during  eight  days  in  vacuo,  yielded  12  per  cent.,  and  consisted,  according  to  all 
known  reactions,  of  the  two  proximate  principles,  fluavile  and  albane.  The 
evaporation  of  the  mother  liquor — consisting  of  alcohol,  and  of  resin,  whether  of 
spontaneous  oxidation  or  added,  dried  in  vacuo,  and  protected  from  air  and  light — 
yielded  a  residue  similar  to  an  amber-yellow  varnish,  almost  transparent,  rather 
soft  and  tacky,  weighing  12  per  cent.  This  residue,  redissolved  in  weak  alcohol 
(50  per  cent.),  and  treated  with  caustic  soda,  after  one  and  a  half  hour's  boiling, 
only  left  an  insoluble  residue  of  8  per  cent.,  whilst  the  soda  solution  had  evidently 
absorbed  about  4  per  cent,  (resin  soap).  The  4  per  cent,  of  residue  dissolved  by 
the  caustic  soda  may  be  regarded  as  the  product  of  the  spontaneous  alteration  of 
the  gutta  percha,  whilst  the  8  per  cent,  appears  to  come  from  a  resinous  substance 
added  purposely.  This  substance — very  difficult  to  dry,  rather  like  glue,  of  a 
straw-yellow  colour — burned  with  a  very  smoky  flame,  and  gave  off  a  characteristic 
smell  rather  similar  to  that  of  Borneo  caoutchouc. 

Obach's  methods  for  analysing  gutta  percha — 1.  Determining  resin. — The  resin 
is  extracted  by  means  of  cold  ether,  the  solution  distilled,  and  the  residue  carefully 
heated  and  weighed.  (The  gutta  and  dirt  remaining  after  extraction  of  the  resin 
are  dried  in  vacuo  and  weighed  so  as  to  check  the  other  result.)  2.  The  determina- 
tion of  gutta. — The  gutta  in  its  turn  is  then  dissolved  in  carbon  disulphide  or 
chloroform,  the  solution  filtered,  and  the  solvent  distilled  off.  The  gutta  so  obtained 
is  dried  in  vacuo,  and  weighed  and  then  softened,  and  pressed  into  the  form  of  a  plate, 
which  is  tested  for  elasticity  and  strength.  3.  Dirt. — To  facilitate  the  separation  of 
dirt  from  the  gutta  solution,  the  latter  is  centrifuged,  or  it  is  mixed  with  alcohol 
or  water,  according  as  the  solution  has  been  made  in  carbon  disulphide  or  chloro- 
form respectively.  In  standing  the  two  hot  liquids  separate  again,  and  the  lighter 
one  rising  to  the  top  carries  the  dirt  with  it,  the  clear  solution  can  then  be  drawn 
off  at  the  bottom.  In  this  way  results  can  be  obtained  which  are  sufficiently- 
accurate  for  most  practical  purposes,  although',  scientifically  speaking,  they  are  not 
correct,  as  the  resin  is  not  completely  separate  from  the  gutta,  and  the  latter  still 
contains  a  certain  amount  of  colouring  matter.  However,  these  disadvantages  are 


METHODS   OF   ANALYSING  GUTTA   PERCHA 


397 


in.. iv   l.alaneed    J>y  the  great    convenience    of    this    method    for    daily  use   in   the 

laboratory    in    o.mparis. m    with    the  other   method   of   preeipitat  in.ur    tin-    pun-   <:utta 
with  aleoho]. 

A/,  ,-iiiniiii'i  til--  /-,•<•'  iif'K/'    "/'  /»•///    ///   i/iiff'i   /»fr/<, i   I,//  the  density  of  t tie  ex- 

tractdl    «n/,iti,,n.        Where    i.ni\     til--     approximate     |  .eiveiM  ;e_r.-     "t      ivsin    is    iv.juiivd, 

•h  elaborated  a  process  based  on  the  increase  of  the  >|.. .  iti«-  gravity  of  a  solvent 
ether,  fur  instance,  through  the  presence  of  re>in.  'I'he  apparatus  consists  of  two 

s  tubes  closed  at  j  their  l«»wer  ends  and  tilted  with  rubber  stoi>i>er  through 
whieh  pass  the  two  ends  of  a  narrow  glass  tube  bent  in  the  form  of  a  f|.  A 
Neighed  .(iiaiitity  of  gutta  percha,  cut  into  very  small  pieces,  is  put  into  one  of  the 
larger  tnl.es,  and  a  measured  quantity  of  ether  into  the  other.  The  ether  is  forced 
«>ver  into  the  first  tube,  and  left  for  a  certain  time  in  contact  with  the  gutta  percha. 
It  is  then  driven  l.a.-k,  and  its  specific  gravity  measured  with  a  special  hydrometer 
which  is  provided  with  a  thermometer.  The  apparatus  stands  in  a  wooden  box, 
with  ijlass  windows  back  and  front,  so  as  to  ensure  uniformity  of  temperature,  and 
speeiul  precautions  have  to  be  taken  to  guard  against  loss  by  evaporation,  etc. 
The  percentage  of  resin  can  be  read  off  directly  from  the  increase  of  gravity  by 
special  tables.  With  a  less  volatile  solvent  the  viscosity  might  also  afford  useful 
indications. 

Gutta  perchas  in  which  the  percentage  of  resin  reaches  that  of  gutta,  or  even 
Mir  passes  it,  are  of  a  decidedly  inferior  description.  However,  if  the  relative  pro- 
portion of  gutta  and  resin  forms  an  important  criterion  for  estimating  the  com- 
mercial value  of  a  gutta  percha,  yet  this  in  itself  is  not  sufficient.  Even  putting 
aside  for  the  moment  the  variable  composition  of  the  resinous  components,  there 
are,  says  Obach,  guttas  and  guttas,  and  although  the  ultimate  analysis  of  two 
different  specimens  may  give  exactly  the  same  result,  the  physical  and  mechanical 
properties,  and  most  important  of  all,  the  durability  may  widely  differ,  owing  to 
a  difference  in  their  molecular  constitution.  It  is  therefore  absolutely  indispensable, 
in  addition  to  the  quantitative  determination  of  the  components,  to  scrutinize  the 
gutta  itself,  which,  it  need  hardly  be  said,  requires  much  judgment  and  experience. 

TABLE  CXXIII. — INSULATION  IN  MEGOHMS  AND  INDUCTION  IN  MICROFARADS  PER 
CUBIC  KNOT  OF  VARIOUS  BRANDS  OF  GUTTA  PERCHA  WITH  Low  AND  HIGH 
PERCENTAGES  OF  WATER  (OBACH). 


I.  Genuine.                                     II.  Soondie. 

Pahang. 

Banjer  Red. 

Bagan. 

Kolaringin. 

Water  per  cent.      . 
Insulation 
Induction 

1-5 
6,173 
•5480 

6-5 
5,480 
•0675 

1-4 
6,427 
•560 

5'2 
5,625 
•0592 

1-7 
7,950 
•0521 

7'3 
4,350 
•0682 

0-8 
7,730 
•6080 

7'2 
6,080 
•0662 

III.  White.                         IV.  Mixed  and  Reboiled. 

Banjer. 

Bolungan. 

Sarawak  Mixed. 

Banca  Reboiled. 

\Vai.i  PIT  cent.     . 
Insulation 
Induction 

0-6 
10,410 
•0555 

7-1 
6,454 
•0898 

0-9 
57,910 
•0575 

11-2 
39,030 
•0890 

1-1 
24,250 
•0664 

7'0 
24,250 
•0718 

ro 

82,320 
•0648 

10-0 

68,020 
•0753 

Mechanical  testiny  of  yutta-percfia. — As  to  resistance  tests  to  a  determined  force, 
they  should  be  conducted  according  to  the  method  given  for  vulcanised  rubber. 


398  GUTTA   PERCHA 

The  difference  in  the  nature  of  the  two  substances  must,  however,  be  taken  int.) 
account.  Rubber  may  be  pulled  in  any  direction,  whilst  gutta  percha  offers  no 
resistance  in  a  cross  direction,  and  can  only  be  pulled  longitudinally. 

Calculation  of  specific  electrical  resistances.—  Before  describing  the  most  simple 
methods  for  ascertaining  the  specific  resistance  of  different  varieties  of  gutta  percha, 
it  will  be  well  to  recall  some  indispensable  definitions  for  the  perfect  understanding 
of  what  follows.  The  resistance  of  a  conductor  is  proportional  to  a  factor,  de- 
pending on  the  nature  of  the  body  forming  the  conductor  and  inversely  proportional 
to  its  section;  the  factor  /has  been  called  the  specific  resistance  of  the  body. 
R,  be  the  resistance  of  a  conductor,  L  its  length,  and  S  its  section,  these  quantities 
are  associated  by  the  relation  — 


The  resistance  of  a  conductor  being  proportional  to  a  factor  depending  on  the 
nature  of  the  body,  the  factor  called  specific  resistance  is  measured  in  ohms- 
centimetres  and  in  microhms-centimetres  for  weak  resistances,  and  megohms- 
centimetres  for  great  resistances. 

Insulators.  —  Bodies  exhibiting  great  specific  resistance  are  called  insulators. 
In  general  their  resistance  varies  with  the  conditions  in  which  they  are  placed. 
It  varies  with  the  temperature,  with  the  weather  during  which  the  substance  is 
submitted  to  the  electric  current,  with  the  pressure  to  which  it  is  submitted.  If 
caoutchouc  at  0°  C.  (32°  F.)  has  a  specific  resistance  of  32,000  x  106,  if  caoutchouc 
at  24°  C.  (75'2°  F.)  has  a  specific  resistance  of  75,000  x  106,  megohms-centimetres, 
the  different  varieties  of  gutta  percha  have  a  specific  resistance  varying  from  25 
to  500  x  106  megohms-centimetres. 

Jenkirfs  method  by  the  electrometer.  —  The  insulation  of  a  cable  may  also  be 
ascertained  by  measuring,  by  means  of  the  electrometer,  the  potential  V  of  the 
battery  with  which  the  cable  is  charged,  and  that  of  v  of  the  charge  which  remains 
in  it  after  t"  seconds,  and  embodying  these  values  in  Siemens'  formula  — 

0-4353  t 


J.t—  TT- 

Clog- 

V 

But  with  these  very  high  resistances  the  differences  between  V  and  v  are  very 
slight ;  and  even  under  these  conditions  the  values  of  V  and  v  are  limited  by  the 
condition  of  being  contained  within  the  scale  of  the  instrument,  which,  as  is  well 
known,  only  contains  720  divisions.  Fleeming  Jenkin  devised  a  method  by 
virtually  prolonging  the  scale  so  as  to  count  the  deviations  from  the  starting-point 
of  a  very  distant  imaginary  zero.  By  suitably  choosing  the  zero  in  each  particular 
case,  deviations  may  always  be  obtained  extending  over  the  whole  of  the  length 
of  the  actual  scale.  Suppose  that  one  of  the  poles  of  a  battery  of  100  elements 
be  run  to  earth,  and  the  other  connected  with  one  of  the  pairs  of  quadrants,  the 
second  pair  being  itself  in  communication  with  the  distant  end  of  the  insulated 
cable.  If  the  cable  be  charged  for  a  few  moments  to  the  same  potential  as  the 
battery,  the  needle  of  the  electrometer  will  first  remain  at  zero ;  but  in  proportion 
as  the  charge  is  dissipated,  the  deviation  increases.  If  the  electrometer  deviates 
100  divisions,  for  example,  for  a  difference  of  potential  equal  to  the  electromotive 
force  of  one  element  of  the  battery,  a  deviation  of  100  divisions  of  the  scale  will 
be  obtained  each  time  that  the  potential  of  the  cable  lowers  one  hundredth  of  its 
value.  The  deviation  will  be  200,  300,  400  divisions  when  this  potential  diminishes 
2,  3,  4  per  cent. ;  in  fact,  if  the  potential  becomes  nil,  the  deviation,  supposing 
that  the  construction  of  the  instrument  allows  it,  will  attain  a  rather  prolonged 
point  of  the  scale  that  may  be  called  the  fictitious  zero.  In  the  above  example 
the  fictitious  zero  would  be  at  the  division  10 '000. 

In  actual  practice  the  pole  of  the  battery  (Fig.  146),  which  is  connected  with  a 
pair  of  quadrants,  instead  of  being  insulated  is  run  to  earth  through  a  resistance 


METHODS   OF   ANALYSING  GUTTA   PERCHA  :JOO 

coil  1!  with  ;ui  indicator  m  large  enough  for  tin;  battery  not  to  l>e  appreciably 
reduced  by  the  closing  of  tin-  circuit  during  the  experiment.  A  double  commutator 
key  J/j  cnal>les  the  current  to  be  established,  interrupted,  or  reversed.  The 
indicator  of  tin-  instrument  is  connected  \sith  a  sec,,nd  doiil.le  commutator  key  .I/.. 
\\hicli  a#iin  communicates — (1)  by  means  of  a  circuit  breaker  /  \\ith  t\\«.  pairs  of 
quadrants  of  the  electrometer  /:'  :  ( •_' )  \\iili  a  c'lmmutatur  II  of  se\eral  direct  ions  to 
which  the  earth  plate  T  is  attached,  and  the  different  cables  L  L  to  I..-  tested,  and 
which  can  !.«•  done  simultaneously. 

M.t/K,  I  »,/'  ,>i»  r.ition. — The  electrometer  is  charged  by  means  of  the  ndiarger, 
and  the  luminous  ima.u'e  is  brought  to  the  real  zero  of  tin*  scale.  The  indicator  M 
is  made  to  glide  so  that  the  ratio  of  the  resistance  ac  comprised  between  the  mm 
and  the  indicator,  to  the  resistance  «£=100,  is  a  very  simple  fraction;  ocasa  rule 
is  chost -a  as  =10,  which  gives  ^  for  the  ratio  of  the  two  resistances  ac,  ob,  and 
consequently  for  the  fraction  of  the  battery  which  serves  to  determine  the  fictitious 
zero.  The  plug  of  the  circuit  breaker  /  is  removed  ;  the  commutator  I!  is  plaeed 
on  the  earth  stud,  then  the  springs  of  the  key  M  are  successively  lowered  and  one 
of  those  of  the  key  J/2.  One  of  the  pairs  of  quadrants  is  thus  put  in  communica- 
tion with  the  indicator  ///,  the  other  directly  with  the  earth;  the  product  by  10  of 
the  division  at  which  the  luminous  image  stops  on  the  scale  represents  the  division 
Z  corresponding  with  the  fictitious  zero.  The  same  measurement  is  retaken  by 
i excising  the  poles  of  the  battery;  then  the  keys  Ml  and  J/2  are  fixed  in  their 
normal  portion  ;  the  plug  is  put  into  the  circuit  breaker  /,  and  the  indicator  Is 
passed  along  to  the  100  division  of  the  coil  R.  One  of  the  springs  of  Ml  and  J/2 

r.iin  lowered,  and  at  the  tinie'fixed  for  the  commencement  of  the  charge  the 


L 

FIG.  144.— Electrometer. 

handle  of  the  commutator  B  is  turned  so  as  to  place  its  axis,  and  consequently  the 
complete  battery  P,  in  communication  with  the  cable  L  to  be  tested  :  a  charge  of 
fifteen  seconds  generally  suffices  for  100  miles  of  cable.  At  the  end  of  this  time 
the  plug  of  the  circuit  breaker  /  is  withdrawn  ;  in  proportion  as  the  potential  of  tin- 
cable  decreases,  the  luminous  index  deviates  further  on  the  scale  from  the  zero  of 
the  graduation.  If  we  wish,  for  instance,  to  have  the  insulation  at  the  end  of  the 
second  minute,  the  deviations  clv  cl2  are  taken  corresponding  to  the  time  1'  45" 
and  2'  15"  from  the  commencement  of  the  first  contact  of  the  battery  with  the 
cable  and  brought  into  the  following  formula — 

0-4343  x  30 
•- C  [log  («- dj)  -  log  T<> -#)]•• 

Readings  are  taken  at  4'  45"  and  5'  15",  and  the  deviations  brought  into  the 
above  formula  if  it  be  desired  to  get  the  insulation  at  the  end  of  the  fifth  minute. 
When  by  exceptional  lowering  of  the  potential  the  luminous  index  would  emerge 
beyond  the  limits  of  the  real  scale,  it  is  made  to  re-enter  by  causing  the  indicator 
in  to  pass  to  the  zero  of  the  coil ;  there  are  then  added  to  each  of  the  readings  on 
the  scale  the  number  of  the  divisions  corresponding  to  the  permanent  displacement  of 
the  indicator.  The  measures  so  taken  are  very  exact,  not  being  affected  by  variations 
in  the  current  of  the  testing  battery,  and  are  remarkably  delicate,  which  may  be 
increased  indefinitely  by  increasing  the  sensibility  of  the  instrument,  the  strength 


400  GUTTA   PERCHA 

of  the  battery,  and  the  interval  of  time  which  separates  the  two  readings. 

over,  with  a  single  instrument  in  a  manufactory  a  number  of  cables  may  be  tested 

simultaneously. 

Specific  resistance  of  the  dielectric.  —  These  results  obtained,  let  L  be  the  length 
of  a  cable  the  insulating  resistance  of  which  is  R,  and  p  the  specific  resistance  of 
the  dielectric  used  ;  i.e.  of  a  cube  having  the  unity  of  length  as  its  sides.  Let  us 
make  in  the  cable  a  section  perpendicular  to  the  axis,  and  let  us  consider  the  layer 
of  dielectric  of  the  thickness  dx  situated  at  the  distance  x  from  the  axis.  The 
resistance  will  be  — 


If,  therefore,  d  and  D  represent  the  interior  and  exterior  diameters  of  the 
insulating  envelope  — 

D 


/ 

Jd 


due        p    i      D 

n 


2 
Hence  — 


log  representing  the  common  logarithms. 

The  resistance  at  the  temperature  of  24°  C.  of  a  cube  of  a  metre  of  side  is  on 
an  average  for  gutta  percha 

3*55  x  106  megohms. 

—  (Jenkin's  Cantor  Lectures.) 

Testing  manufactured  gutta  percha.  —  It  is  sometimes  important  for  the 
electrician,  or  the  manufacturer  of  telephonic  apparatus,  to  ascertain  the  greater 
or  less  degree  of  purity  of  the  gutta  percha  which  he  is  using.  A  comparative 
analysis  can  alone  give  him  useful  data.  He  ought  to  compare  —  by  the  estimation 
of  the  ash  and  by  its  approximate  analysis  —  the  suspected  sample  with  a  standard 
sample  of  known  purity.  If  incineration  is  not  sufficient,  solution  in  carbon 
disulpide  or  toluene  of  the  gutta  percha  to  be  analysed  will  give  the  amount  and 
the  nature  of  the  mineral  matter  fraudulently  added.  As  regards  resins,  bitumens, 
etc.,  they  are  easily  estimated  by  treating  the  sample  with  boiling  alcohol.1  On 
cooling,  the  natural  gutta  resins  are  completely  deposited  by  operating  as  described. 
The  quantity,  colour,  smell,  tint  of  the  evaporation  residue  from  the  mother  liquors, 
give  sufficient  data  as  to  the  proportion  and  nature  of  the  adulteration. 

1  But  even  boiling  alcohol  has  only  a  partial  solvent  action  on  bitumens,  has  little  or  no 
action  on  such  pitches  as  rosin,  pitch,  etc.  On  treating  a  gutta  percha  suspected  of  containing 
bitumen  with  alcohol,  much  bitumen  and  other  pitches  will  remain  behind  untouched  mixed 
with  the  gutta.  Some  scheme  similar  to  Henriques'  nitre-benzol  method  for  the  separation 
of  asphaltum  from  rubber  is  evidently  required  (see  pp.  254,  255).  —  TR. 


[TABLE 


MliTHODS   OF  ANALYSING  GUTTA   PERCHA 


401 


TABU-         ('XX  IV.      -(  '..Ml-  \i:  \  1 1\  i:       BLBCTBIOAI       PROPERTIES      OF      DIFFERENT 

SAMPLES     OF     GUTTA    PEK«  n.\,     INDIARUBBER,     |{J->I.N-,    PARAFFIN     \V\\, 

Si  i  rin  i:.     \M.    \\'  \n:i:. 


Insulation  Resistance. 

Inductive  Caiu. 

Megohms. 

._•                  Microfarads.    "               ^ 

Materi.il. 

'l 

++ 

| 

Per  Cube 
Knot. 

Per  Knot 
(log^  =  l). 

•S 

Air  =  l. 

Cube 

Per  Kn.it 

— 
a 

(Jiitta  percha  — 

(  'loaned  commercial,  highest. 

139,300        51,050 

(1)1   4-496       0-0801 

0-2184 

(1) 

,,               ,,            lowest   . 

382  i          140 

(1)     2-619       0-0466 

0-1272 

(1) 

Willoughby  Smith's  special   . 
From  leaves  —  Serrulax  . 

955             350      Hi 
57,980        21,260     1(2) 

3-122       0-055(5 
2-JOo        u-0525 

o-i. 

0-1433 

(4) 
(2) 

»>                   »> 

120,700  i      44,260      (3)     3'120       0'0555 

0*1518 

(3) 

Obacli      . 

48,630 

17,830      (1)     2-707       0'0482 

O-l.'ii:. 

(1) 

Balata       

2,1  ir.             786      (1)     2-724       0-0485 

0-1323 

(1) 

Caoutchouc 

Pure  vulcanised 

130,000        47,660 

(1) 

o-t'.tj-j 

0-0474 

0-1293     ; 

(1) 

.Mixed  vulcanised  . 

81,700        29,950 

(1) 

3-405       0-0606 

0-1654       (1) 

Pure  un  vulcanised  . 

15,440          5,659 

(1)     2-505       0-01  n; 

0-1217 

(1) 

Submarine  cable    . 

37,100        13,600 

1  1  1    .'5  -561      0'0»;;;  i 

0-1730 

(1) 

Overland  telegraph  cable        .  ; 

61,770        22,650 

(1)     :',-405       0-0606 

0-1654 

(1) 

Kl.onite    

16,5H»          6,061 

(1) 

3-160       0-0562 

0*1584 

(6) 

Part  Ilin  wax       .... 

34,230        12,550 

(1) 

2-310 

0-0411 

0*1122 

(6) 

Sulphur    

21,180          7,764 

(5) 

3-825       0-0681 

0-1858     j 

(6) 

Resin  — 

Colophony  (common  rosin)     . 
Kxtracted  from  gutta  percha  . 

21,700 
14,360 

7,952 
5,264 

(1) 

(1) 

2-550 
3-270 

0*0454 

o-o. 

0-1230 
0-1587 

(6) 
(1) 

Watrr          

... 

75-700 

1-3480 

3-6770 

I 

7) 

(1)  Obach.    (2)  Lord  Kelvin.    (3)  Dr.  Hopkinson.    (4)  Clark  and  Sabine.    ('>)  Foussereau.    (6)  Bott/.maini 
(7)  E.  H.  Rosa. 


CHAPTEK  VIII 
GUTTA  PERCHA   SUBSTITUTES 

As  with  rubber,  the  excessive  prices  to  which  good  quality  gutta  percha  has  risen 
have  caused  the  trade  to  try  to  replace  it,  wholly  or  partially,  for  special  purposes  by 
(A)  natural  products,  or  (B)  by  more  or  less  analogous  compositions  (Table  CXXV.). 
(A)  Natural  Products. — A  great  number  of  substances  have  been  proposed  for  re- 
placing gutta  percha  in  cable  manufacture,  and  so  obtain  cheaper  insulators,  or 
insulators  more  resistant  to  oxidation,  variations  of  temperature,  attacks  of  insects, 
and  other  destructive  influences.  Several  of  the  substances  present  in  the  beginning 
remarkable  dielectric  properties,  but  up  to  now  none  of  them  have  shown  the 
almost  indefinite  unalterability  of  gutta  percha  preserved  under  water.  ( 1 )  Paraffin. 

It  was  at  first  attempted  to  use  paraffin,  but  this  hydrocarbide  is  too  brittle,  and 

it  is  only  used  to  protect  temporarily  from  the  air  the  extremity  of  wires  covered  with 
gutta  percha.     (2)  Ozokerit. — Then  came  the  turn  of  Ozokerit.     This  substance, 
also  called  ceresin  or  mineral  wax,  is  a  hydrocarbide  which  is  found  naturally 
intercalated  in  rather  thick  layers  in  the  schistose  rocks,  in  the  vicinity  of  petroleum 
wells,  in  Galicia,  Hungary,  Baku,  Caspian  Sea,  the  States  of  Utah  and  Arizona  in 
North  America.     The  raw  material,   previously  melted  to  free  it  from  mineral 
gangue,  which  amounts  to  about  15  per  cent.,  is  afterwards  distilled.     It  yields  on 
distillation  about  15  per  cent,  of  paraffin  oil,  from  which  ozokerit  solidifies  on  cool- 
ing.    The  deposit  is  freed  from  the  excess  of  oil  by  centrifugal  force  and  strong 
pressure.    The  yield  is  generally  25  per  cent,  of  the  crude  material.    It  is  a  slightly 
amber-coloured  body,  with  a  very  fine  granular  fracture ;  it  melts  between  70°  and 
80°  C.,  is  not  saponifiable  by  alkalies,  and  is  not  attacked  by  sulphuric  acid,  even 
when  heated  to  100°  C.  (212°  F.).     Atmospheric  agents  have  no  action  on  the 
substance.       It   is   at  the  same   time  a  good  dielectric.     Combined   with  small 
quantities  of  rubber,  it  yields  softer  and  more  plastic  products,  which  may  compete 
with  it  as  an  insulating  medium,  and  in  regard  to  inductive  capacity.     Henley  uses 
ozokerit  in  the  following  manner ; — The  conductor  of  plated  (polished)  copper  is  first 
covered  with  pure  rubber,  then  with  a  separate  grey  composition,  then  with  a  black 
composition  substance  kept  secret,  and  finally  pure  ozokerit.     The  core  is  covered 
with  a  layer  of  felt  soaked  in  ozokerit.     The  insulation  of  these  cables  would 
appear  to  rise  as  high  as  5000  megohms  per  marine  mile,  after  five  minutes  of 
electrisation  and  twenty-hours'  immersion  in  water  of  24°  C.  (75*2°  F.).     The  pitch 
left  in  the  still  from  the  destructive  distillation  of  mineral  wax  is  also  used  for 
cable  insulation.     Edison  gives  the  resistance  of  crude  ozokerit  as   450   million 
megohms  per  c/m.,  whilst  that  of  paraffin  is  only  110  million  megohms;  the  in- 
sulating capacity  of  the  paraffin  free  residue  must  be  higher,  and  in  fact  has  proved 
to  be  very  satisfactory,  whilst  the  power  of  resisting  heat  is  also  considerable. 

(B)  Mixed  Compositions.  (1)  Nigrite. — By  masticating  together  at  the  lowest 
temperature  possible,  to  bring  them  into  a  plastic  condition,  indiarubber  and  the 
residue  from  the  distillation  of  ozokerit,  a  substance  mechanically  superior  to  gutta 
percha,  is  obtained,  less  sensitive  to  the  action  of  heat  than  rubber,  possessing  a 
superior  insulation  power  to  gutta  percha,  and  a  notably  inferior  inductive  capacity. 
Clark  and  Muirhead  have  made  torpedo  cables  which  appear  to  have  given  good 
results  for  several  years.  (2)  White  Birch  Tar  or  Gutta  Franmise. — The  so-called 
yutta  Francaise  (E.  Mourlot  Fils,  French  Patent,  No.  13,310;  1879,  and  additional 
one  of  3rd  September  1 880),  besides  improving  the  gutta  by  making  it  more  dur- 
able in  air,  was  also  said  to  be  a  specific  against  the  attacks  of  rats  in  underground 


402 


GUTTA   PERCHA   SUBSTITUTES 


403 


conduits.  lint,  according  t<.  <  >l..i.-li,  it  renders  gutta  percha  coarse  and  brittle,  and 
aUo  impairs  it-  electrical  properties.  \\'r  >liall  only  mention,  a-  .1  matt--r  »i  refer 
ence  (l\)  kerite,  (!)  IJnnv  Warren's  rubber,  ami  Co  tinally  the  dielectric  emplo\..l 
in  tin-  llni'ik's  cables,  certainly  composed  of  resins  and  resinous  oils,  -"lid  at 
ordinary  temperature.  Tin-  insulation  ..f  tlieM-  CabJ08  i-  extremely  hiu'h. 
-ample-  te-ted  in  Knu'land  after  several  months'  interxal  ha\e  IH-M-I  i  |i,-|,-»  ivpilarK 
pven  an  insulation  of  M),00()  megohm-  per  mile.  We  shall  not  du«-ll  f'urtln-r  "ii 
\\  IMV'S  coiii|iii>itiMH.  ii^rd  fs|..-ci;illy  in  hot  fliniatr>  \\hrn-  irutta  |.«-ivha  cannot  \\ith- 
stand  the  a-'tion  •»!'  tin-  surrounding  iitniusjilu-rf  without  softening  or  rvrn  inciting. 
Tin-  «Miu|iositi.ui.  prepared  l.y  a  mixture  of  shellac,  caoutchouc,  silica,  and  juilvcri-.-il 
alum,  to  \\hirh  '  of  its  \\-cight  of  gutta  percha  has  been  added,  i->  protoiindly  and 
rapidly  deteri«»mted  by  sea  water. 

(6)  Will  the  nitrocellulose  in  appropriate  solution  as  proposed   l.y  Nol.el  yield 
the   results   which  the  inventor  claims']     Time  will  tell;   and  until  proof  to  the 
contrary  \\e  must  hold  to  the  opinion  that  we  have  expressed  at  the  commencement 
of  this  chapter. 

(7)  \'rfrri/.      A  mixture  of  collodion  cotton  and  nitrated  castor  or  lin>eed  oil 
\\ .  I',  le-id  and  .1.  V.  Karles,  British  Patent,  No.  21,995  ;  1895)  is  one  of  the  recently 

proposed  siil.-titntes.  The  Velvril  paste  is  moulded  like  gutta  percha.  but  after 
hardening  it  cannot  be  softened  by  heat  alone.  Cord  can  be  made  l»y  squirting 
the  paste  through  a  die,  and  it  has  been  proposed  to  use  it  as  an  insulating  envelojKJ 
in  place  of  pitta  percha. 

(8)  Chatttrto*'*  <•< unbound,  consists  of  a  mixture  of  gutta  percha,   rosin,  and 
Stockholm  tar.     It  is  used  as  a  binding  material  between  the  copper  conductor  and 
the  pitta  percha  envelope,  or  between  the  different  layers  of  gutta  percha  on  tin- 
core.     It  is  also  used  for  cementing  gutta  percha  to  wood.     It  is  prepared  thus  : - 
Stockholm  tar   1   cwt.,  rosin    1    cwt.,  are  heated  in  a  steam    jacket  ted    pan,   then 
strained  and  mixed  with  3  cwts.  of  clean  shredded  gutta  percha,  the  mass  being 
intimately  mixed  by  horizontal  stirrers  working  on  a  vertical  shaft. 

TABLE  CXXV. — SOREL'S  GUTTA  PERCHA  SUHSTITI  TBS. 


A 

B 

C 

D 

Rosin         ...... 
Pitch         
Rosin  oil    . 
Coal  tar     . 

Ib. 
2 

8 

Ib. 

"a 

4 

Ib. 

Ib. 
12 

Slaked  lime 
Water        
China  clay          ..... 
Gutta  percha     ..... 

•£>  CO  0  C^ 

r-t  i—  i 

6 
16 

6 

16 

6 

In  formula  A  the  rosin  oil  is  very  evidently  meant  to  act  a-  solvent  for  the 
rosin  and  pitch,  the  China  clay  is  a  mere  tiller  for  which  other  fillers  can  be  sub- 
stituted. The  rosin,  rosin  oil,  and  pitch  are  heated  in  a  pan  until  dissolved.  The 
lime  made  into  a  paste  with  the  water  is  added,  and  then  the  gutta  i>eivha  :  and 
when  the  pitta  percha  is  melted,  then  the  China  clay  is  stirred  in.  Additional 
\\ater  is  added  and  the  whole  brought  to  100°  C.  212°  F. 

Several  formula'  for  compositions,  for  insulation  purposes,  are  pven  in 
\\''>,ves  (Scott,  (Iivenwood,  A:  Son). 


THE  END 


INDEX 


Abyssinian  gutta,  371-373. 
Acacia  decurrens,  66. 
Acclimatisation  (gutta),  318-327. 

,,  (rubber),  57. 

Accra  rubber,  102-103,  131. 
Acetins,  285. 
Acetochlorhydiins,  285. 
Acetone,  66,  282-283,  286,  372. 
Achin  gutta,  321. 
Acid,  acetic,  66,  117,  127,  236,  239,  240-243, 

248-249,  373. 
arsenious,  52. 
carbolic,  53,  66. 
citric,  51,  66. 
formic,  66,  127. 
hydriodic,  116,  366. 
hydrobromic,  125. 
hydrochloric,  52,  66,  217,  369,  376. 
hydrocyanic,  366,  369. 
hydrofluoric,  366. 
nitric,  52,  117,  261,  366,  368-370. 
oxalic,  66, 
phosphoric,  76-79. 
picric,  372. 
sulphuric,  50,   52,   66,  117,  208,  217, 

236,  366,  370. 
sulphurous,  187,  366. 
tannic,  66. 
Adhesion  (rubber),  124. 

,,         (vulcanised  rubber),  203. 
Africa,  rubber  in,  5,  12,  25,  37,  45,  46,  48-49, 
50-51,  53,  57,  84-86,88-89,  92,  100-107, 
114,  117,  128,  130,  137,  213,  296,  312,  317. 
Albane,  338,  368-369,  372,  396. 
Albumenoids,  43,  66-67,  89,  111,  114,  220. 
Alcohol,  absolute,  282. 

ethylic,  28,  51-52, 117, 120, 122,  128, 

366-373,  400. 

Alcoholic  soda  group,  282-283. 
Alkalies,  118,  165,  173,  230,  239. 
Alkaline  salts,  52. 

,,       sulphides,  173. 
Alkanet  root,  221. 
Aloetic  matter,  127. 
Alstonia,  20,  23,  28,  313. 
Altitude  of  rubber-plantations,  33,  56-57,  80, 

82,  86-87. 
Alum,  66. 
Amazonian  rubber,  5,  6,  7,  33-37,  40-45,  58- 

60,  62,  74,  94-95,  112. 
Ammonia,  43.  52,  133,  236. 


Ammoniacal  cochineal,  221. 
Ammonium  ferrocyanide,  66. 
,,  fluoride,  118. 

,,  nitrate.  224. 

Amylaceous  bodies,  115. 
Analysis  of  balata,  376. 

,,       ,,  ebonite,  280-282. 

„  gutta  percha,   342-348,    348-350, 

367,  373,  385. 
,,        ,,  cut  sheet  rubber,  278-279. 

.,  vulcanised  rubber,  222,   229-231, 

233-234,  271-281. 
Anastomosed  vessels,  12. 
Angola  rubber,  104-105. 
Animal  oil  (Dippel's),  8. 
Annam,  rubber  in,  48,  60,  106-107. 
Anodendron,  20. 
Antimony  iodide,  172. 

„          sulphide,  173-174,   220,   228,  240, 

242,  244,  246. 
Apocynacese,  guttiferous,  313. 

,,  caoutchouciferous,    12,    13,    20, 

29,  82,  84. 
Arboriculture  (gutta),  321-327. 

(rubber),  56-89. 
Archil,  221. 
Artificial    rubber.      See    "Substitutes"    and 

"  Synthetic  rubber." 
Artocarpeoe,  13,  18,  19. 
Asbestos,  220. 
Ash  (gutta),  367,  371,  375,  395. 

,,    (rubber),  94,  109,  225-230,  234,  239. 
Asiatic  rubber,  7,  33,  106-107. 
Asphaltum,  219,  235-240,  280,  283,  400. 
j    Assahan  gutta,  341,  348. 
Assam  rubber,  7,  48,  58,  106-107,  120,  141. 
Assinia,  102,  108-109. 
!    Atmospheric  action  on  gutta,  355. 

,,  ,,        ,,  rubber,  204. 

Attalea  excelsa,  41. 
Aurantiacese,  51. 
Australian  gutta,   317. 

rubber,  108-109. 
Autoclave  for  dissolving  rubber,  266. 

,,          vulcanising,  187-188. 
Axe  for  gutta  felling  and  ringing,  328-330. 
,,    for  tapping  wild  rubber,  35. 

;    Babou  gutta,  304-342. 
Bagan  gutta,  341-342,  349,  385,  397. 
Bahia  rubber,  40,  48,  50,  57,  96-97. 


404 


INDEX 


405 


Balata,  308-309,  334-335,  341,  348,  375-377, 

401. 
Banca,  rebelled,  307,  328-329,  380-331,  349, 

385. 
Banjermassiii  gutta,  304,  321,  340-342,  .348, 

349-385,  :;:'7. 
Kirk,  gntta,  294,  326,  332,  333,  340. 

,,      rubber,  33,  53,  75. 
IJ.-isii-  slug  li-rtiliser,  78. 
I  lu-i.i  Taikii,  L'!U>,  309-313,  316,  318,  373-375. 

Ilitali/a  rubber,   128. 

llauhitiia  reuticulata,  9. 
i ',<•!. mk  gutta,  320. 
I'.rlts.  vulcanising,  182-184. 
Benguela  rubber,  104-105. 
Birch  tar,  403. 
Biscuit  rubber,  42,  81. 
Bitumen.      "See  Asphaltum." 
1  ill  -aching  gutta,  391-392. 
Bleeding.     "See  Tapping." 
Blocking  factory — rubber,  146. 

,,         plantation — rubber,  71,  81. 
Boiling  rubber  latex,  45. 
Bolungaii  gutta,  340-341,  346,  348-349. 
Bone  naphtha,  8. 

Borneo  gutta,  298-299,  304,  307,  315,  321, 
322,  328,  331,  332,  334,  340,  341, 
350,  396. 

,,       rubber,  27,  87-88,  108,  141. 
Bornesite,  117. 
Botanical  Gardens,  Buitenzorg,  323. 

,,  .   ,,        Gold  Coast,  88. 

,,  ,,        Kew,  292. 

,,  ,,        Libreville,  62. 

,,  ,,        Saigon,  62. 

Botany  of  gutta,  294-313,  314,  317. 

,,      „  rubber,  7,  11-31. 
Brass  wire  in  rubber  tubes,  8. 
Bromine,  118. 

Brotuo  and  bromo-nitro  camphor,  etc.,  285. 
Butylene,  125. 
Butyrospermuni  Parkii,  310.     See  "  Bassia."    i 

Cable  covering  machine,  363. 
Cables,  submarine,  292,  357,  361. 

,,      telephone,  357. 
Calcined  magnesia,  235,  238,  240-241,  244- 

245,  244-249. 
Calcium  chloride,  52. 
„        fluoride,  235. 
,,        hydrate,  244-245,  248-249. 

sulphate,  220,  223. 
Calenders,  153-158. 
Calico,  vulcanising  dyed,  170-172. 
Calotropis,  30,  108-109,  113,  312. 
Cambodian  gutta,  305-320. 

,,          rubber,  20. 
Cameroon  rubber,  25,  49,  50,  85. 
Candle  material,  rubber  as,  7. 
Caoutchouc  des  huiles,  261. 

„          etymology,  5,  6,  7. 
Caoutchoucine  (CJO  H16),  125. 
Caoutchoutocopy,  203. 

Castilloar ubber,  59.    See  "  Central  American." 
Castor  cake  as  fertiliser,  76-77. 
Caucho,  7. 
Caustic  soda,  230. 
Cayenne  rubber,  6,  96-97. 
Ceara   rubber,    16,   30,    33,    40,  46,   47,    48, 

57,  60-62,  88,  94-95,  120. 


i-ia,  19-20. 

Celebes,  85,  108-109,  298-299,  340. 
(VniciiN.  gutta.  L".'l. 

Central  American  rubbers,  4,  37,  48,  57,  92. 
Ceylon,   28,  29,  32,  33,  56,  60,  61,  62,  67, 

76,  79,  82,  306,  821, 
Chalk  as  a  rubber  till.-r,  'J38,  240-241,  242- 

243,  244-245,  246-217. 
Chatterton's  compound,  403. 
Chavanesia,  27,  57. 
Chemistry  of  gutta,  351-377. 

,,          „  rubber  (normal),  118-135. 
,,          ,,       ,,      (vulcanised),  188-192. 
Chiahuahua  (Guayule),  82. 
Chiapas  plantations,  65. 
China  clay,  403. 
Chloral  (coagulant),  67. 
Chlorine,  274,  278. 
Chloro  camphor,  etc.,  284-286. 
Chloroform,  366,  368-373,  396. 
Chloro-nitrotoluol,  etc.,  286. 
Chrysophyllum,  299,  309. 
Churning  latex,  67. 
Coagulation,  Bobet  on,  38. 
,,  Dittmar  on,  39. 

Weber  on,  191. 
Coagulent,  alum,  49. 

antiseptic,  44,  66,  118. 
,,          chloral,  .67. 
,,          iron  perchloride,  51. 

soap,  50. 

Collecting-cups,  35,  62. 
Compressibility,  123,  252,  255. 
Conductivity,  heat,  and  electricity,  gutta,  630. 
,,  ,,       ,,  ,,        rubber,  121, 

195. 
Congo  gutta,  291. 

,,      rubber,  25,  46,  48,  49,  85. 
Coorongite,  260. 
Coti  gutta,  298,  341. 
Cottoman  gutta,  346. 
Creosote,  44. 
Crepe  rubber,  71. 
Crotonese,  13-16. 
Cryptostegia,  13. 
Curana,  4. 
Cut  sheet,  146-150. 
Cutting  machines,  71. 
Cynanchum,  29,  106-107,  313. 

Dambonite,  115-117. 
Dambose,  115-117. 
Deformation  of  rubber,  237-259. 
Density  of  gutta,  354. 

,,       ,,  latex  (rubber),  111. 
,,        ,,  normal  rubber,  120. 
,,       ,,  oils  distilled  from  rubber,  125-126. 
,,       ,,  vulcanised  rubber,  193-194. 
Depression  of  rubber  tests,  201. 
Dermatine,  264. 
Dialysing  power  of  rubber,  123. 
Dichopsis  borneense,  314,  324,  325. 
calophylla,  304-305,  314. 
gutta,    297,    299-301,    314,    318, 

325,  334. 

Krantziana,  305,  314. 
Maingayi,  318. 
oblongifolium,  297,  301,  302,  304, 

318,  324-325. 
polyanthe,  318. 


406 


INDEX 


Dichopsis  pustulatum,  297,  306,  314,  318. 
.,        selendit,  305. 

Treubii,  314,  325. 
Dielectric  strength  (gutta,    rubber,  ebonite), 

296,  364. 

Diplorhynchus,  20. 
Distillation,  destructive,  of  fatty  oils,  127. 

„  gutta,  368. 
,,  ,,  »  rubber,  125, 

„  turps,  133. 

Drying  in  gutta  analysis,  395-397. 
„      of  rubber,  68-69,  71,  140.  , 
"Dusting"  (ebonite  colouring),  21.6. 
Dyeing  rubber,  220. 
Dynamometrical  testing  of  rubber,  250-257. 

E.  African  rubbers,  93,  100-105. 
Ebonite,  212-218,  238-239,  401. 

analysing,  281-282. 
,,       colouring,  216. 

curing,  214-215. 
,,       enamelling,.  216. 
,,       manufacture  of,  212-218. 
modulus  of,  238. 

Otto  and  Traun's  process,  215-216. 
powdered,  216. 
properties,  217-218. 
rubber,  sorts  for,  217. 
substitutes,  272.  . 
waste,  rubber  used  in,  206. 
Ecdysanthera  micrantba,  29. 
Ecdysanthereae,  20. 
Elasticity  of  gutta  percha,  352-353. 

,,  rubber,  123,  196,  203,  244-249. 
Eiaterite,  260. 

Electric  conductivity  of  gutta,  360-365. 
,,  ,,  ,,  rubber,  121. 

,,       induction  of  gutta,  362-367,  401. 
,,  ,,        ,,  rubber  362-367,  401. 

insulation  of  gutta,  342,  349,  360,  401. 
,,  ,,         ,,  rubber,  237,  401. 

Emerald  green,  220. 
Engine  for  calenders,  157. 

,,       ,,    plantations,  73. 
Enzyme,  noxious,  of  rubber,  67.  , 
Euphorbiacese  (gutta),  313,  316-317. 

(rubber),  13-16.  ~ 
Euplumeriae,  20. 
Extensibility  of  rubber,  123. 
Extraction  of  gutta  from  bark  and  leaves,  332. 
Extractors,  rubber,  analysis  of,  266,  282-284. 
,,          for  hardening  gutta,  386-387. 

Fatty  acids  in  substitutes,  269,  274-275. 
Felling  balata  trees,  334. 

„      gutta  trees,  328-334. 

,,      rubber  trees,  33-34. 
Ferric  salts  as  coagulants,  51. 
Fertilisers  for  rubber  plantations,  74-79. 
Ficus  elastica,  7,  12,  13,  17-18,  32,  37,  54,  57, 

58,  87-88,  110-113. 
„     Vogeli,  89. 
Fillers  for  rubber,  238-247. 
Filter  presses  for  gutta,  381-383. 
Fluavile,  367-368,  375. 
Fluorine,  63. 

Foutah-Djallon,  25,  100,  312. 
Formaldehyde,  66-67. 
Formenic  carbides,  366-367. 
Fosteronia  floribuncla,  13-20, 


Funtumia  elastica,  20,  27,  32,  84-86,  89. 
Fustic  in  rubber  dyeing,  221. 

Gaboon  gutta,  317. 

„    rubber,  85,  102-103,  115. 
Galam  butter,  310. 
Gambia  rubber,  51,  53,  63,  100-101. 
Gas  absorption  by  rubber,  195. 
Glycerine,  52,  174,  240-241,  244-245. 
Gold  Coast  rubber,  88-89. 
Golf  ball  tester,  353. 
Graphite,  220. 

Green  dyes  and  pigments  for  rubber,  220-221. 
Guayule,  82,  100-101. 
Guignet's  green  in  rubber,  220-221. 
Gutta,  368-369. 

Gutta    percha,   analysis  of,    342,    348,    367, 
373,  385. 

boiling,  333,  339. 

botany  of,  287-301. 

chemistry  of,  367. 

fat,  327. 

extraction  of,  326. 

sampling,  395. 

vulcanising,  394. 
• 

Halogens  action  on  rubber,  118. 

,,       in  vulcanising,  162. 
Hancornia,    20,  28,    33,    49-50,    51,  57,  95, 

96-97. 

Hardened  rubber.     See  "Ebonite." 
Hardening  gutta  percha,  386-387. 

,,          of  rubber  by  cold,  9. 
Hatchet  for  gutta  felling  and  ringing,  330. 

,,         ,,  rubber  tapping,  35. 
Heat,  action  of,  on  gutta,  354. 

,,          ,,       ,,     ,,  rubber,  124-126. 
Heavy  oils  from  rubber  distillation,  124-126. 
!    Hevea  Braziliensis,  6,  13,  14-16,  32-33,  37, 
40-45,    51-53,   54,    56-57,    65-67,5  88-91, 
94-97.  106-107,  112-115,    118,    133.     ,sv,; 
Amazonian  rubber. 
History  of  gutta  percha,  289-293. 
,,      ,,  rubber,  3-10. 

Indo- Malay  rubber,  13,  91. 
Indragiri  white  soondi,  350. 
;    Insulation  of  balata,  377. 
„         ,,  ebonite,  365. 
,,         ,,  gutta,  360-365. 
Iodides,  metallic,  in  vulcanising,  167. 
Iodine,  118,  132,  133. 

,,        absorption  of  substitutes,269, 274, 276. 
j    Ire  (Ireh  or  Ereh}.     See  "Funtumia." 
Iron  perchloride  coagulant,  51. 
Isoprene  from  rubber,  125-127,  133. 
„         ,,      gutta,  370. 

!    Java  gutta,  298-299,  315,  320,  322-327. 
„     rubber,  106,  107,  108-109. 

Karopar  gutta,  298. 
Kassai  rubber,  104-105. 
Kicksia.     See  "  Funtumia  elastica." 
Kneading  rubber  and  gutta.     See  "Mastica- 
tion." 
Kotaringin  gutta,  344-345,  348-349. 

Labuan  gutta,  331. 
Lampblack,  216. 


INDEX 


407 


iipoiig  gutta,  321. 
Un.lul|,hia.    18,    '-'I   -«:,  32,  -18,   49,  53,  64, 

57,  89,  111.',  li:>. 
Latex  of  bula t... 

,,      ,,  ^utt.i.  294,  :^6. 

„      ,,  rubber,  11,  82,  110,  111-114,  118. 
Liti'-iferous  vessels,  11-12. 
l..-;i.l  acetate*,  '-'39. 
L«-ad  Milphi.lr,  ; 
Lianrs  (rlimliriN),  13. 
Librria  rubbrr,  KI-J-I 
1,'Miulo  rubber,  104. 

Macassar  gutta,  339. 

Machinery  I'm  mitta.  manufacture,  379-393. 

,,  rubber  manufacture,  136-161. 
Mackintosh  and  waterproofs,  8. 
Madagascar    rubber,    13,    40,   51,    106,    107, 

219. 
Ma. lav  gutta  of  India,  312,  313. 

-iu,  ealrine<l,  235,  238,  240,  244. 
Manicaria  saxifera,  41. 
Manihot  glax.iowii,   7,   13,  16,  32,  46,  47,  48, 

54,  56,  57,  60,  130.     Sec  "Ceara." 

ulai  gutta,  342-343. 
Mastication  of  gutta,  384-394. 

,,  rubber,  142-161. 
Matezite,  117- 
Matezo  dambose,  117. 
Maturin,  balata  of,  334. 
Maximiliaua  regia,  41. 
Mcteza  roritina,  116. 
Mcthylamine  (Carthagena  rubber),  97- 
Mexican  rubber,  4,    18,   37,   40,    65,   82-84, 

98-99. 

Micrandra,  15-16,  40. 
Mi.  ro-tnillimetre  defined,  37. 
Microscopy  of  rubber,  37. 
"Milk."  "  Se,'  "Latex." 
Mimusops,  308-309,  316-317. 
Minaes-Geraes  rubber,  97- 
Mixer,  automatic,  152. 
Molleudo  rubber,  94-95. 
Mozambique  rubber,  104,  105,  113. 

"  Xegroheads,"  45. 

"Niggers,"  102-103,  101-105,  130. 

Nigrite,  402. 

Nitrobenzol  in  rubber  analysis,  285-286. 

Nitrocellulose  and  solvents,  285-286. 

Oils,  action  of,  on  vulcanised  rubber,  204, 

241-243,  249. 

,,    dry-distilled  from  rubber,  125. 
,,    free  unsaponi liable,  in  substitutes,  284. 
,,    oxidised,  261. 
,,    vulcanised,  261-284. 

Padang  gutta,  307,  324,  344-345. 
Pahang  gutta,  342-343,  348,  350,  365,  385. 
Palaquium.     See  "Dichopsis." 
Para  latex,  10,  43,  66-67. 

,,   rubber.     &e"Hevea." 
Paraffin,    235,    240-241,    242-243,    244-245, 

246-247,  268. 
Patani  rubber,  19. 
Payena  Lerii,  299,  302,  306, 308,314-315,  315- 

316,  318,  330-341,  345,  370-371. 
Pckang  gutta,  344-345. 
Pempeni  rubber,  89. 


1'eriplocagneca,  30. 
lYiim-al.ility  ,.r  rubber,  121-122,  195. 
Peroncel  (sulphur  chloride),  10. 
Petroleum  .spirit,  172,  386. 
Plantations,  implements  for,  66-74. 

,,          profits  and  loss  on,  91. 

,,          rubber,  63-91. 
Plasticity  tests,  252,  261. 
Plumericae,  20. 
Pneumatic  tyres,  10. 
Polarising  power  of  rubber,  122-123. 
Polymerisation  in  terpcnes,  133. 
Pontianaek  gutta,  344-345. 
Poppyseed  oil,  261-274. 
Presses,  filter,  381-383. 

,,       vulcanising,  182,  185. 
Propagation  of  rubber  plants,  60-62,  € 

Quito  rubber,  5. 

Raised  sheet  rubber,  150. 
Rangoon  rubber,  106. 
Rape-cake,  as  fertiliser,  76. 
Reclamation  of  rubber,  206. 

,,     gutta,  392-394. 
Ringing  balata  trees,  334. 
,,        gutta  trees,  328. 
Rolled  sheet  rubber,  153-158. 
Rolling- machinery,  rubber,  138-161. 
Roots,  laticiferous,  32. 
Rosin,  403. 

,,       oil,  338,  403. 
Rubber,  biscuit,  42,  81. 

,,     block,  71,  83,  146. 

,,     brands  of,  94-109. 

„     crepe,  71. 

Sapotaceae,  295,  299. 

Seringa,  15. 

Sernamby,  para  45,  141. 

Sheet  rubber,  146-160. 

Siphonia  Braziliensis.     See  "Hevea." 

Slicing  rubber,  137. 

Smoke  curing  of  latex,  41-45. 

Sodium  polysulphide,  173. 

Softening  rubber,  137. 

,,        point  gutta,  367. 
Soil  for  rubber  plants,  57. 
Solvents,  acetone.     See  "Acetone." 
alcoholic.    See  "Alcohol." 
benzol,  370,  395. 
petroleum,  172,  386. 
for  asphaltuni,  280-282. 

balata,  375-377. 

gutta,  366. 

latex  (rubber),  117-118. 

nitrocellulose,  285-286. 

paraffin,  282. 

rosin,  282. 

rubber,  127. 

substitutes,  282. 

vulcanised  rubber,  204. 
Sonchus  Oieratus,  31. 
Spreader,  Decauville's,  160. 
Steam  joints,  rubber  parking  for,  234. 
Stearine  in  gutta  fat,  327. 
Storage  of  rubber,  136-137. 
Stove,  Waddington's,  176. 
Sublimation  vulcanising  process,  165. 
Substitutes  for  rubber,  261,  264,  276. 


408 


INDEX 


Substitutes,  iodine  absorption  of,  269,  274, 

276. 

Sulphides,  vulcanising  by,  173-174. 
Sulphur,  44,  118,  394. 

„        chloride,  165-173, 191-192, 261-280. 

,,         estimation,  229. 
Synthetic  rubber,  126-127. 
Syphocampylus,  31. 

Tabernsemontana,  20. 

Talc,  10,  225. 

Tapping  gutta  trees,  327. 

,,        rubber  trees,  33-38,  63. 
Tests,  abrasion,  253,  257. 

bending,  233,  256. 

cable  insulation,  398,  400. 

depression,  201. 

electrical  resistance,  389. 

golf  ball,  353. 

Heinzerling's,  235-249. 

perforation,  253. 

plasticity,  252,  261. 

strain  and  stress,  250. 

tensile,  196-203. 


Tigelinha,  32,  62. 

Tin  iodide,  172. 

Tools  for  rubber  plantations,  64,  90,  91, 

Triganou  gutta,  330-331. 

Urceola,  13,  27,  32. 
Urostigma,  108. 
Urticacese,  16. 

Vahea.    See  "Landolphia." 
Valves,  10. 

Vermilion,  220,  227-228. 
Vulcanisation  of  rubber,  162,  192. 
Vulcanised  oil,  261. 

„          rubber,  193-285. 
Vulcanising  dyed  calico,  170. 

Walnut  oil,  oxidised,  261. 

,,        ,,  vulcanised,  261  ct  seq. 
Waterproofing,  6,  7,  159-161. 
Willoughbeia,  13,  29,  57. 

Zanzibar  rubber,  104. 


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